Patent Application
20160160312
The present invention relates to the production and utilization of oxygen in hydrometallurgical processes for obtaining one or more metal values from a metal-bearing material like mineral ore and/or concentrate.
Hydrometallurgical processes are wet processes to extract and recover metals. They rely on leaching one or more valuable metals, so-called metal values, like gold, silver, platinum group metals, copper, nickel, cobalt, lead, zinc, manganese, molybdenum, rhenium, rare earth metals, and uranium from metal-bearing materials such as ore, concentrate, tailings, matte, slag, and calcine. The one or more metal values of interest are dissolved from the metal-bearing material into an appropriate solution. The solution is then separated from insoluble residue. The leaching process may employ one or more of a variety of chemicals such as dilute sulfuric acid and/or dilute aqueous cyanide. The lixiviant in solution may be acidic or basic or neutral in nature. Methods for contacting the metal-bearing material and the lixiviant can include agitating comminuted solids and solution (slurry) in open tanks, agitating slurry at a high temperature in a pressure vessel, and percolating lixiviant through crushed ore that has been piled in a heap or vat and collecting the solution that issues from the bottom. Enhanced- or high-temperature and pressure leach processes are performed in autoclaves. Autoclaves may be operated under oxidizing, acidic, or alkaline conditions. Oxidizing or reducing gases, such as air, oxygen, and sulfur dioxide, may be used, taking into account the gas-liquid contact requirements.
The metal-bearing material may be pre-processed, as is the case e.g. with refractory materials like refractory ores, concentrates and tailings, to liberate the metal values and make them accessible to leaching. Common pre-processing options include roasting, pressure oxidation, bio-oxidation, and ultra-fine grinding. In roasting, pressure oxidation, and bio-oxidation, the metal-bearing material is oxidized. In ultra-fine grinding, the material is ground to small particle sizes such that the significant surfaces of the metal values are exposed, enabling high contact of the metal values with the lixiviant solution.
Hydrometallurgical processing facilities have large oxygen requirements, in particular, in pressure oxidation, roasting, and oxidative pressure leaching. Oxygen may also be required for atmospheric leaching, for activation of the metal-bearing material e.g. in a grinding process, for on-site production of acid, and/or for the remediation of lixiviant. Bio-oxidation and bio-leaching may also require oxygen.
U.S. Pat. No. 3,741,752 (Evans et al.), for example, discloses a process for the recovery of nickel and copper from copper-nickel-sulfide matte by means of a three-stage leaching process. Air is introduced into each of the leaching stages and furthermore into a copper purification stage following the second leaching stage.
According to U.S. Pat. No. 4,093,526 (Blanco et al.) nickel-copper-sulfur concentrates are leached in a combination of a first stage atmospheric leaching unit and two subsequent pressure leaching stages. In each of these leaching stages or units, air or oxygen is used to create oxidizing conditions.
U.S. Pat. No. 5,645,708 (Jones) utilizes a pressure oxidation pre-processing unit and an atmospheric leaching unit for the extraction of copper from sulfide copper ore or concentrate.
U.S. Pat. No. 6,569,224 (Kerfoot et al.) teaches a hydrometallurgical process for the recovery of nickel and cobalt values from a sulfidic flotation concentrate with atmospheric chlorine leaching as pre-processing followed by downstream oxidative pressure leaching. Oxygen is introduced in the oxidative pressure leaching unit, and may also be used in the atmospheric leach pre-processing unit to maximize the reaction of sulfuric acid with sulfide minerals.
U.S. Pat. No. 8,623,115 (Langhans et al.) discloses hydrometallurgical processing of precious metal-bearing materials in which the precious metal-bearing material, in this case a refractory material, is comminuted and conditioned to form a slurry of a desired density which is subsequently subjected to pressure oxidation in an autoclave. The autoclave discharge slurry is flash cooled, neutralized and the neutralized discharge slurry is subjected to leaching with a suitable lixiviant. Cyanide, ammonium, sodium, and calcium thiosulfate and also halides (iodide, bromide, chloride), and thiourea are mentioned as typical leaching agents. The sorbed precious metal is recovered from the pregnant leach solution e.g. by electrowinning or cementation to form the precious metal product. Considerable amounts of oxygen are consumed in the pressure oxidation pre-processing circuit.
U.S. Pat. No. 8,025,859 (Jones), as a further example for precious metals recovery, discloses a combination of pressure oxidation and downstream pressure cyanidation with optional intermediate atmospheric leaching and flotation. An initial metal-bearing material in the form of a concentrate slurry is subjected to pressure oxidation at elevated temperature and pressure, using high purity oxygen as oxidant. Pressure cyanidation is carried out under an elevated oxygen pressure to reduce the duration of the cyanidation and minimize thiocyanide formation.
U.S. Pat. No. 8,268,037 (Kummer et al.) discloses a method of recovering molybdenum from a molybdenum bearing sulfide material by bioleaching mentioning that adequate aeration is required as oxygen is the preferred terminal electron acceptor for enzymatic bio-oxidation of iron and sulfur compounds in the bioleaching process.
The prior art processes exemplify the variety of applications of oxygen in hydrometallurgical processing facilities. As far as air is employed in the various processes the air may be enriched by the addition of oxygen or substituted by a higher oxygen content gas or high purity oxygen to intensify the respective one or more oxidative reactions.
For remote facilities, an oxygen production unit is required. This would typically be a pressure or vacuum swing adsorption (PSANSA) unit. The compressors and vacuum blowers of PSA or VSA units, however, consume considerable amounts of electric power for cyclic pressurization and depressurization of adsorbent beds, power that has to be produced on-site if the facility is remotely located. The cyclic nature of PSA and VSA impedes integration with hydrometallurgical processing. The adsorbed gas fraction is desorbed by depressurization. Work can hardly be recovered from this fraction.
Industry desires to improve the economics for providing oxygen to hydrometallurgical processes.
It is object of the present invention to improve the economics, including energy efficiency, operating costs, and/or capital costs, of hydrometallurgical processing by the use of an ion transport membrane device and/or process for the production of oxygen used therein.
It is another object of the present invention to improve the overall economics of hydrometallurgical processing and oxygen production by integration of said hydrometallurgical processing process and said ion transport membrane device and/or process.
There is a need for improved integration of oxygen supply and hydrometallurgical processing enabling on-site production of at least a portion of the oxygen needed by one or more material processing units of a hydrometallurgical processing facility.
The present invention accomplishes economic supply of oxygen by integration of a hydrometallurgical processing circuit and an ion transport membrane assembly for the production of an oxygen product from an oxygen- and nitrogen-containing feed gas. The hydrometallurgical processing circuit is operatively disposed to receive an oxidant gas containing at least a portion of the oxygen product from the ion transport membrane assembly and/or activated oxygen generated from at least a portion of the oxygen product from the ion transport membrane assembly. The oxygen-containing feed gas to the ion transport membrane assembly may in particular be pressurized and heated air or a pressurized and heated gas mixture formed from air and one or more other sources. Gaseous effluent from the hydrometallurgical processing circuit, e. g. vent gas and/or bleed gas from pressure oxidation and/or oxidative pressure leaching, may in particular be such a source.
Oxygen can be separated from oxygen-containing gases, e.g. from air, at high temperatures by mixed metal oxide ceramic materials utilized in the form of nonporous ion transport membranes (ITM). An oxygen partial pressure differential or a voltage differential across the membrane causes oxygen ions to migrate through the membrane from the feed side to the permeate side. Ion transport membrane assemblies comprising one or more ion transport membranes each with one or more membrane layers and their utility in recovering oxygen from air or other oxygen-containing gases are known in the art (e.g. U.S. Pat. Nos. 5,681,373, 7,179,323, and 7,955,423). Particularly suited for the present invention are ion transport membrane assemblies with one or more membranes of the mixed conductor type, i.e. membranes in which an oxygen partial pressure differential across the respective membrane causes oxygen ions to migrate through the membrane from the feed side to the permeate side where the ions recombine to form electrons and oxygen product gas.
U.S. Pat. No. 5,643,354 (Agrawal et al.) discloses a high-temperature ion transport membrane assembly to recover oxygen for use in a direct iron making smelting process. Heat for the integrated oxygen recovery is obtained from the combustion of fuel gas and/or indirect heat exchange with a hot gas from the iron making process. A combined cycle power generation system is included so that the product portfolio of the ion transport membrane assembly includes oxygen product gas, electric power and steam. The steam is exported or expanded in a steam turbine to make additional electric power. The electric power is exported or used internally.
U.S. Pat. No. 5,855,648 (Prasad et al.) discloses the integration of an ion transport membrane assembly in a pyrometallurgical process. The oxygen product of the membrane assembly is added to the feed gas stream of a blast furnace for the production of iron from ore.
The prior art has not yet considered utility of the ion transport membrane technology for the production of oxygen needed in the hydrometallurgical processing of metal-bearing materials to recover one or more of its metal values.
The present invention proposes advantageous integrations of an ion transport membrane assembly with a hydrometallurgical processing circuit in a hydrometallurgical processing system and in a hydrometallurgical process.
The hydrometallurgical processing circuit comprises a leaching unit and one or more pre-processing units. It may furthermore comprise one or more post-processing units and/or an acid production unit. The pre-processing unit is operatively disposed to receive a metal-bearing material and adapted to process the metal-bearing material, for example, by grinding or oxidation. The pre-processing unit is disposed upstream of the leaching unit. The leaching unit disposed downstream of the pre-processing unit may therefore be termed ‘downstream leaching unit’, not the least because an upstream leaching unit may constitute the pre-processing unit. The pre-processing unit may be any one of a grinding unit, in particular a ball mill, for grinding the metal-bearing material, a roasting unit for roasting the material, a pressure oxidation unit, a bio-oxidation unit, an atmospheric leaching unit, a bio-leaching unit, a pressure leaching unit, and a solution or slurry preparation unit, e.g. a solution or slurry neutralization unit. A solution or slurry preparation unit, for example a solution or slurry neutralization unit, or a lixiviant remediation unit or a further leaching unit may constitute the optional post-processing unit. The pre-processing and post-processing units mentioned are potential oxygen consumers, the downstream leaching unit and the optional acid production unit as well. The hydrometallurgical processing circuit may comprise one or more pre-processing and/or post-processing units not requiring oxygen to perform their specific processing function. Identifying certain pre-processing and/or post-processing units as potential oxygen consumers does not mean necessarily that the respective unit, should the hydrometallurgical processing circuit comprise that unit, does need oxygen to accomplish its specific processing function, or is supplied by the ITM assembly. For example, the hydrometallurgical processing circuit may comprise a grinding unit and/or a bio-oxidation unit and/or a bio-leaching unit and/or a remediation unit with no oxygen supply at all, and/or a pressure oxidation unit and/or an oxidative leaching unit not supplied with oxygen product from the ITM assembly.
The hydrometallurgical processing circuit may comprise an acid production unit. The downstream leaching unit may in those embodiments operatively be disposed to receive acid from the acid production unit. If the one or more pre-processing units comprise a pressure oxidation unit and/or an upstream leaching unit, at least one of these units may operatively be disposed to receive acid from the acid production unit. This includes embodiments in which only one of these units, i.e. only the downstream leaching unit, or only a pressure-oxidation unit, or only an upstream leaching unit, is operatively disposed to receive acid from the acid production unit, and also embodiments in which any two or all three of these units are present and operatively disposed to receive acid from the acid production unit.
The hydrometallurgical processing circuit may comprise a post-processing unit as mentioned above. The post-processing unit is in those embodiments operatively disposed to receive at least a portion of the discharge material from the downstream leaching unit e.g. for subsequent solution or slurry neutralization, subsequent further leaching, or remediation of lixiviant. The optional subsequent further leaching unit may operatively be disposed to receive acid from the acid production unit, if present.
In embodiments, the integrated processing system comprises one or more pre-processing units and one or more post-processing units, and optionally an acid production unit for producing acid which could be utilized in a leaching or pressure oxidation unit of the system, in particular, in one or more of the leaching units mentioned above.
If, for example, the hydrometallurgical processing circuit comprises a grinding unit and the downstream leaching unit, the downstream leaching unit is operatively disposed to receive at least a portion of the material ground by the grinding unit. The ground material may be subjected to intermediate pre-processing, e.g. pressure oxidation, upstream leaching, and/or flotation on its way from the grinding unit to the downstream leaching unit.
Typically, a roasting unit, a pressure oxidation unit, and a bio-oxidation unit are alternatives one to the other. On the other hand, the hydrometallurgical processing circuit may comprise any two or all three of these types of pre-processing units, such as, a roasting unit and a pressure oxidation unit in parallel, or a bio-oxidation unit and a pressure oxidation unit in series, only to mention examples of suitable combinations.
One or more upstream leaching units, if present, may be adapted to separate different metals from one another by dissolving metals selectively. The downstream leaching unit may, for example, operatively be disposed to receive either the fraction with the one or more dissolved metals or the fraction with one or more other metals not dissolved in upstream leaching.
These are only examples of a recovery process that might be implemented in the hydrometallurgical processing circuit. The hydrometallurgical process and the hydrometallurgical processing circuit as such can be designed as known in the art. The background art acknowledged above discloses examples of hydrometallurgical processes suited for integration taught by the invention.
According to the invention, at least one of the pre-processing unit, the downstream leaching unit, the acid production unit, if present, and the post-processing unit, if present, is an oxygen consuming unit and operatively disposed to receive an oxidant gas containing at least a portion of the oxygen product from the ion transport membrane assembly or activated oxygen, typically ozone, generated from at least a portion of the oxygen product from the ion transport membrane assembly. This includes embodiments in which only one of the four units mentioned is an oxygen consuming unit and operatively disposed to receive the oxidant gas and also embodiments in which any two or any three or all four of the units mentioned are oxygen consuming units and operatively disposed to receive the oxidant gas. Furthermore, any two or any three or all four of the units mentioned may be oxygen consuming units, but not each of the oxygen consuming units must be provided with oxidant gas from the ion transport membrane assembly. Rather, oxidant gas containing oxygen product from the ion transport membrane assembly or activated oxygen generated therefrom may be provided to only a subgroup of oxygen consuming units of the hydrometallurgical processing system.
The ion transport membrane assembly is adapted to provide at least part of the oxygen consumed by the hydrometallurgical processing circuit during operation in at least one oxidative process performed by the at least one oxygen consuming unit. The oxygen product may be used as such as oxidant in one or more oxygen consuming units of the hydrometallurgical process circuit. It may however be advantageous to use instead or in combination with the oxygen product an activated oxygen, preferably ozone, as oxidant in one or more oxygen consuming units of the hydrometallurgical process circuit.
Activated oxygen may be used as oxidant, for example, in the downstream leaching unit and/or an upstream leaching unit and/or a further leaching unit downstream of the downstream leaching unit and/or in a pressure oxidation unit and/or in a lixiviant remediation unit. Use of activated oxygen, in particular ozone, is known for example for cyanide remediation.
The oxygen product from the ion transport membrane assembly and/or activated oxygen generated therefrom may constitute the oxidant gas and may constitute, in particular, all of the oxidant used for oxidation in one or more oxygen-consuming units of the hydrometallurgical process circuit. Oxygen product from the ion transport membrane assembly and/or activated oxygen generated therefrom may constitute all of the oxidant used in oxidation in the hydrometallurgical process circuit. In principle, however, the oxidant gas may contain diatomic oxygen and/or activated oxygen from one or more oxygen sources other than the ion transport membrane assembly. The oxidant gas may comprise, as oxidant, not only oxygen but also one or more other oxidants, such as, chlorine.
The invention has recognized that the product portfolio of an ion transport membrane assembly, namely, the permeate oxygen product, the non-permeate nitrogen-enriched product, power, and steam which can be generated by each of the two products, in particular the non-permeate product, matches ideally with the needs of hydrometallurgical processing. Furthermore, instead of or in addition to steam generation, the thermal energy of one or both of the two products can be heat exchanged with one or more process streams of the hydrometallurgical processing circuit. Ion transport membrane assemblies typically produce a permeate oxygen product comprised of at least 95 vol. %, or at least 97 vol. %, or at least 99 vol. % oxygen. High purity oxygen is required in many applications of hydrometallurgical processing. The high oxygen purity of the oxygen product is a further advantage of integrating an ion transport membrane assembly.
In basic embodiments of integration, only the oxygen product gas from the ion transport membrane assembly and/or activated oxygen generated therefrom is/are utilized in the hydrometallurgical processing circuit, e.g. for activating the metal-bearing material during grinding in the grinding unit and/or for oxidation purposes in a roasting unit and/or in a pressure oxidation unit and/or in a bio-oxidation unit and/or in an upstream leaching unit and/or in a solution neutralization unit. Instead or in addition to employing all or part of the oxygen product and/or activated oxygen generated therefrom in one or more oxygen consuming pre-processing units, oxygen product gas from the ion transport membrane assembly and/or activated oxygen generated therefrom may be employed in an optional oxygen consuming post-processing unit, e.g. for remediation (detoxification) of lixiviant, and/or in the acid production unit, if present, for the production of acid which can be provided into a slurry or solution fed to or contained in an oxygen consuming unit, e.g. an optional pressure oxidation unit, and/or an optional upstream leaching unit, and/or the downstream leaching unit.
Integration of the ion transport membrane and the hydrometallurgical processing circuit can be improved by recycling a gaseous oxygen-containing effluent from the hydrometallurgical processing circuit. At least a portion of that recycle effluent may be mixed with fresh oxygen-containing feed gas and the mixture fed to the feed side of the ion transport membrane assembly, and/or at least a portion of the recycle effluent may be mixed with at least a portion of the oxygen product from the ion transport membrane assembly. Such recycling enables oxygen recovery and recovery of the internal energy (heat and/or pressure) of the recycle effluent to the greatest possible extent. For example, vent gas and/or bleed gas withdrawn from a pressure oxidation unit and/or an oxidative pressure leaching unit to maintain a certain minimum oxygen purity in the respective unit may have an oxygen purity higher than that of ambient air, rendering it a prime candidate for recycling as at least a portion of the recycle effluent.
In embodiments, one or more of the other products of the ion transport membrane assembly can be utilized in the hydrometallurgical processing circuit. If the ion transport membrane assembly is of the pressure-driven type, as preferred, an oxygen-containing feed gas is fed to the ITM assembly at a high temperature, typically in the range of 700° C. to 1000° C., and a high pressure, typically in the range of 1000 to 4000 kPa (absolute) resulting in the co-production of high-temperature permeate oxygen product gas and high-temperature high-pressure non-permeate nitrogen-enriched product gas.
At least a portion of the nitrogen-enriched product may be used as flotation gas to float one or more metal values, e.g. molybdenum, in a flotation unit to deliver flotation concentrate and flotation tail. The at least a portion of the nitrogen-enriched product may be provided to the flotation unit at or near the pressure at the outlet of the non-permeate side of the ion transport membrane assembly, or may be reduced in pressure before use for flotation. Before used for flotation, the at least a portion of the nitrogen-enriched product may be reduced in temperature by indirect heat exchange with feed gas to the ion transport membrane assembly and/or a process stream of the hydrometallurgical process circuit.
Flotation with an oxygen-deficient flotation gas, i.e. a flotation gas having a lower oxygen concentration than air, is advantageous in flotation processing where oxidation of metal values soluble in the flotation liquid should be impeded in order to have the one or more metal values dissolved in the flotation liquid precipitate from the solution in a metallic form that can more readily be floated than the respective metal oxide. The oxygen-depleted, nitrogen-enriched product gas from the ion transport membrane assembly is oxygen-deficient as compared with ambient air and may therefor serve as a relatively inert flotation gas.
In embodiments incorporating recycling of recycle effluent from the hydrometallurgical process to the feed side of the ion transport membrane assembly the nitrogen-enriched product gas from the ion transport membrane assembly may also comprise considerable amounts of carbon dioxide which, however, can also be regarded as inert with respect to flotation processing. The nitrogen-enriched product gas from the ion transport membrane assembly may be purified in a nitrogen purification unit providing a purified nitrogen product. At least a portion of the purified nitrogen product may be used as flotation gas or blended with unpurified nitrogen-enriched product from the ion transport membrane assembly to form the flotation gas for oxygen-deficient flotation.
At least a portion of the nitrogen-enriched product may be used for drying at least a portion of the metal-bearing material. In applications where excess water makes it difficult to process initial metal-bearing material, as for example, mineral ore, at least a portion of the hot nitrogen-enriched product may be used to dry the wet material or only a portion thereof by indirect heat exchange and/or by direct contact. This includes embodiments in which a first portion of the nitrogen-enriched product is used as drying agent and heat is recovered from a second portion by indirect heat exchange, and also embodiments in which heat is recovered from at least a portion of the hot nitrogen-enriched product first by indirect heat exchange and subsequently by using the already temperature reduced gas as drying agent and/or drying by indirect heat exchange.
Grinding in oxygen was mentioned before with respect to the oxidant gas. Depending on the metal-bearing material to be ground and/or the hydrometallurgical process performed, it might in alternative embodiments be advantageous to provide an oxygen-deficient gas to the optional grinding unit in order to prevent or at least impede oxidation of one or more metal values during grinding. At least a portion of the nitrogen-enriched product from the ion transport membrane assembly may in those embodiments be provided to the optional grinding unit for grinding under inert conditions or at least under conditions more inert than grinding in air.
Ion transport membrane assemblies of the pressure-driven type advantageously integrate with turbo-machinery-based power cycles (e.g. Brayton cycles). The nitrogen-enriched product can be expanded in a hot gas expander or combustion turbine to recover useful work. Further downstream processing in a heat recovery steam generator (HRSG) can result in an overall product mix of oxygen product gas, mechanical and/or electric power, and/or steam. The mechanical and/or electric power can be used to drive one or more agitators in one or more autoclaves for agitating the slurry in a pressure oxidation unit and/or a bio-oxidation unit and/or any of the leaching units mentioned. Instead of, or in addition thereto, all or part of the mechanical and/or electric power can be used to drive one or more pumps and/or compressors for feeding one or more process streams of the hydrometallurgical processing circuit and/or support the drive of the optional grinding unit and/or drive one or more fuel pumps and/or one or more compressors for compressing one or more oxygen-containing feed gas streams for the ITM assembly.
Autoclaves of pressure oxidation units and pressure leaching units are operated at a temperature typically in the range between 80° C. to 300° C. and at a pressure typically in the range between 300 kPa and 5000 kPa (absolute) making the oxygen product a perfect match also in this respect. The ion transport membrane assembly can be operated to provide the oxygen product at a pressure close to the lower limit of this pressure range and does therefore not require extensive compression if injected into a slurry or solution processed, for example, in a pressure oxidation unit or oxidative pressure leaching unit. Oxygen product from the ion transport membrane assembly or activated oxygen generated therefrom may be cooled before providing it to the at least one oxygen consuming unit or process by indirect heat exchange with a process stream to or from the hydrometallurgical processing circuit and/or a process stream between units of the hydrometallurgical processing circuit and/or with a slurry or solution contained in a vessel of the hydrometallurgical processing circuit and/or with feed gas to the ion transport membrane assembly to recover heat from the oxygen product.
At least a portion of the non-permeate nitrogen-enriched product from the ion transport membrane assembly can be used for the production of ammonia in an ammonia production unit. In those embodiments the hydrometallurgical processing system comprises the ammonia production unit. The nitrogen-enriched product can be purified in a nitrogen purification unit. In those embodiments the nitrogen purification unit is operatively disposed to receive the nitrogen-enriched product from the ion transport membrane assembly, and the ammonia production unit is operatively disposed to receive the purified nitrogen product from the nitrogen purification unit.
The hydrometallurgical processing system can comprise a hydrogen production unit, e.g. a steam-methane reformer (SMR), to provide a hydrogen-containing product. The hydrometallurgical processing circuit can operatively be disposed to receive the hydrogen-containing product from the hydrogen production unit. The hydrogen-containing product can for example be used for neutralization purposes in the hydrometallurgical processing of the metal-bearing material. Hydrogen may be used in a reduction process, e.g. in nickel and/or cobalt reduction units, and/or for the generation of heat and/or introduced into the reducing atmosphere in a sintering unit.
The ammonia production unit, if present, may be operatively disposed to receive at least a portion of the hydrogen-containing product from the hydrogen production unit and at least a portion of the nitrogen-enriched product from the ion transport membrane assembly to produce ammonia. At least one of the hydrogen-containing product from the hydrogen production unit and the nitrogen-enriched product from the ion transport membrane assembly can have undergone purification on its way the ammonia production unit to deliver a purified hydrogen product and/or a purified nitrogen product to the ammonia production unit.
Advantageous features are also described in the sub-claims and the combinations of the same.
In the following, specific aspects of the method and system will be outlined. The reference signs and expressions set in parentheses are referring to example embodiments explained further below with reference to figures. The reference signs and expressions are, however, only illustrative and do not limit the respective aspect to any specific component or feature of the example embodiments. The aspects can be formulated as claims in which the reference signs and expressions set in parentheses are omitted or replaced by appropriate others.
Aspect 1. A hydrometallurgical processing system for processing a metal-bearing material, such as mineral ore, concentrate, tailings, matte, slag, and calcine, the system comprising:
Aspect 2. The system of aspect 1 wherein the ion transport membrane assembly (10) is operatively disposed to receive at least a portion (25.1, 25.2, 25.3, 25.4) of an oxygen-containing effluent gas (25) from the hydrometallurgical processing circuit (20).
Aspect 3. The system of any one of the preceding aspects wherein the hydrometallurgical processing circuit (20) comprises at least one outlet for an oxygen-containing effluent gas (25), this outlet operatively connected with one or both of
Aspect 4. The system of any one of the preceding aspects wherein the pre-processing unit (230) and/or the downstream leaching unit (260) and/or the post-processing unit, the latter if present, comprises or comprises each a pressure vessel, preferably an autoclave, adapted to be operated at or above 80° C. and at or above 300 kPa (absolute), preferably at or above 100° C. and/or at or above 600 kPa (absolute), the pressure vessel operatively connected with one or both of
Aspect 5. The system of any one of the preceding aspects wherein the pre-processing unit (230) and/or the downstream leaching unit (260) and/or the post-processing unit, the latter if present, comprises or comprises each a pressure vessel, preferably an autoclave, and is adapted to control the oxygen concentration of an atmosphere within the pressure vessel to be greater than 20 vol. % oxygen, preferably greater than 30 vol. % oxygen, the pressure vessel operatively connected with one or both of
Aspect 6. The system of any one of the preceding aspects wherein the pre-processing unit is a pressure oxidation unit (230) operatively disposed to receive at least a portion (151) of the oxidant gas.
Aspect 7. The system of any one of the preceding aspects wherein the downstream leaching unit (260) is an oxidative leaching unit operatively disposed to receive at least a portion (152) of the oxidant gas.
Aspect 8. The system of any one of the preceding aspects wherein the pre-processing unit is a grinding unit (210) operatively disposed to receive at least a portion (150) of the oxidant gas for grinding the metal-bearing material (21) in an oxygen containing gas or liquid.
Aspect 9. The system of any one of aspects 1 to 7 wherein the pre-processing unit is a grinding unit (210) operatively disposed to receive an oxygen-deficient grinding gas containing at least a portion of the nitrogen-enriched product (13) from the ion transport membrane assembly (10) and adapted to grind the metal-bearing material in an oxygen-deficient environment.
Aspect 10. The system of any one of the preceding aspects wherein the pre-processing unit is an oxidative solution neutralization unit (240) operatively disposed to receive at least a portion (153) of the oxidant gas.
Aspect 11. The system of any one of the preceding aspects, wherein
Aspect 12. The system of the preceding aspect wherein
Aspect 13. The system of any one of the preceding aspects wherein the pre-processing unit (230) and/or the downstream leaching unit (260) and/or the post-processing unit, if present, comprises or comprises each an autoclave operatively disposed to receive at least a portion (151, 152) of the oxidant gas.
Aspect 14. The system of the preceding aspect wherein the autoclave is operatively disposed to receive an autoclave slurry or solution (22, 24) containing one or more metal values of the metal-bearing material, and comprises a gassing system for introducing, preferably in the autoclave, at least a portion (151, 152) of the oxidant gas into the autoclave slurry or solution (22, 24).
Aspect 15. The system of any one of the preceding aspects wherein the hydrometallurgical processing circuit (20) comprises:
Aspect 16. The system of any one of the preceding aspects further comprising a turbine (30) operatively disposed to receive at least a portion of the nitrogen-enriched product (13) from the ion transport membrane assembly (10), wherein the turbine (30) is a gas turbine, a combustion turbine, or a pressure letdown turbine.
Aspect 17. The system of the preceding aspect wherein the turbine (30) is operatively disposed to provide at least a portion of the first feed gas (11) to the ion transport membrane assembly (10).
Aspect 18. The system of aspect 16 or aspect 17 further comprising a compressor operatively connected to a turbine wheel of the turbine (30) to be driven by the turbine wheel and operatively disposed to provide at least a portion of the first feed gas (11) to the ion transport membrane assembly (10).
Aspect 19. The system of any one of aspects 16 to 18 further comprising a generator (50) for producing electric power (57), the generator (50) operatively connected to the turbine (30) to receive shaft work from the turbine (30).
Aspect 20. The system of the preceding aspect wherein the hydrometallurgical processing circuit (20) is operatively disposed to receive at least a portion of the electric power (57) produced by the generator (50).
Aspect 21. The system of any one of the preceding aspects further comprising a heat recovery steam generator (40) operatively disposed to receive a steam generator feed stream (31), wherein the steam generator feed stream (31) is an effluent stream (31) from the turbine (30), the heat recovery steam generator (40) adapted to recover heat from the steam generator feed stream (31).
Aspect 22. The system of any one of the preceding aspects further comprising a heat recovery steam generator (40) operatively disposed to receive one or more steam generator feed streams (26, 31) and feed water (41), the heat recovery steam generator (40) adapted to produce steam (43) from the feed water (41), preferably by recovering heat from the one or more steam generator feed streams (26,31), wherein the one or more steam generator feed streams (26, 31) comprise at least a portion (31) of the nitrogen-enriched product (13) from the ion transport membrane assembly (10) and/or a hot off-gas (26) from the hydrometallurgical processing circuit (20).
Aspect 23. The system of the preceding aspect wherein the hydrometallurgical processing circuit (20) is operatively disposed to receive at least a portion of the steam (43) from the heat recovery steam generator (40).
Aspect 24. The system of aspect 22 or aspect 23 wherein the heat recovery steam generator (40) is operatively disposed to receive the at least a portion (31) of the nitrogen-enriched product (13) from the ion transport membrane assembly (10) as the steam generator feed stream (31) and the hot off-gas (26) from the hydrometallurgical processing circuit (20) as a further steam generator feed stream (26).
Aspect 25. The system of any one of aspects 22 to 24 wherein the at least a portion (31) of the nitrogen-enriched product (13) is an effluent stream (31) from the turbine (30) of claim 16.
Aspect 26. The system of any one of aspects 21 to 25 wherein the steam generator feed stream (31) is combusted with fuel (47), the heat recovery steam generator (40) adapted to recover heat from the combustion of the steam generator feed stream (31) with the fuel (47) and/or from at least a portion of a hot combustion product of that combustion.
Aspect 27. The system of any one of aspects 21 to 26 wherein the heat recovery steam generator (40) is operatively disposed to receive feed water (41), the heat recovery steam generator (40) adapted to recover heat from one or more of the following heat sources:
Aspect 28. The system of any one of aspects 21 to 27 further comprising a steam turbine (60) operatively disposed to receive at least a portion of the steam (43) from the heat recovery steam generator (40) to generate power and/or low pressure steam for the hydrometallurgical processing circuit (20) and/or for export.
Aspect 29. The system of any one of the preceding aspects further comprising a hydrogen production unit (70) operatively disposed to receive a hydrogen production feed stream (71) and to provide a hydrogen-containing product (73);
Aspect 30. The system of the preceding aspect further comprising a heat exchanger (19) adapted to heat the hydrogen production feed stream (71) by indirect heat transfer with a heat exchanger feed stream comprising at least a portion of the oxygen product (15) and/or at least a portion of the nitrogen-enriched product (13) from the ion transport membrane assembly (10).
Aspect 31. The system of aspect 29 or aspect 30 further comprising a heat exchanger (18) adapted to heat at least a portion of the first feed stream (11) by indirect heat transfer with a heat exchanger feed stream comprising at least a portion of the hydrogen-containing product (73) and/or a hydrogen production unit flue gas (74).
Aspect 32. The system of any one of the preceding aspects further comprising:
Aspect 33. The system of the preceding aspect wherein the hydrometallurgical processing circuit (20) is operatively disposed to receive at least a portion (94) of the ammonia product (93) from the ammonia production unit (90).
Aspect 34. The system of aspect 32 or aspect 33 wherein the hydrometallurgical processing circuit (20) comprises a solvent extraction unit (97) and/or a hydrogen reduction unit (98, 280) and/or a selective catalytic reduction unit (99) operatively disposed to receive at least a portion (94) of the ammonia product (93) from the ammonia production unit (90).
Aspect 35. The system of any one of the preceding aspects wherein the hydrometallurgical processing circuit (20) comprises a flotation unit (215) operatively disposed to receive a flotation slurry containing at least a portion of the metal-bearing material (1, 21) and operatively disposed to receive an oxygen-deficient flotation gas containing at least a portion (32) of the nitrogen-enriched product (13) from the ion transport membrane assembly (10), the flotation unit (215) adapted to pass the flotation gas through the flotation slurry to float one or more metal values of the flotation slurry with the floatation gas and provide a flotation concentrate and a flotation tail.
Aspect 36. The system of the preceding aspect wherein the downstream leaching unit (260) is operatively disposed to receive at least a portion (24) of the flotation concentrate or of the flotation tailing for leaching.
Aspect 37. The system of aspect 35 wherein the downstream leaching unit (260) is operatively disposed to provide at least a portion of the metal bearing material to the flotation slurry.
Aspect 38. The system of any one of aspects 35 to 37 wherein the hydrometallurgical processing circuit (20) comprises a grinding unit (210) operatively disposed to receive at least a portion (21) of the metal bearing material and operatively disposed to provide at least a portion of the ground material to the flotation slurry.
Aspect 39. The system of any one of the preceding aspects wherein the hydrometallurgical processing circuit (20) comprises a drying unit (208) operatively disposed to receive at least a portion of the metal bearing material (1) and operatively disposed to receive at least a portion (34) of the nitrogen-enriched product (13) from the ion transport membrane assembly (10), the drying unit (208) adapted to reduce a liquid content of the at least a portion of the metal bearing material (1) by direct contact and/or indirect heat exchange of the at least a portion of the metal bearing material (1) with the at least a portion (34) of the nitrogen-enriched product (13) and to provide a dried metal bearing material (21).
Aspect 40. The system of the preceding aspect wherein the downstream leaching unit (260) is operatively disposed to receive at least a portion (24) of the dried metal bearing material (21) for leaching.
Aspect 41. The system of aspect 39 or aspect 40 wherein the hydrometallurgical processing circuit (20) comprises a grinding unit (210) operatively disposed to receive at least a portion (21) of the metal bearing material dried in the dryer (208).
Aspect 42. The system of any one of the preceding aspects wherein the hydrometallurgical processing circuit (20) comprises an oxygen activation unit (160) operatively disposed to receive at least a portion of the oxygen product (15) from the ion transport membrane assembly (10) and adapted to generate activated oxygen, preferably ozone, from the at least a portion of the oxygen product (15), and operatively disposed to provide at least a portion of the activated oxygen to one or more of the pre-processing unit (210, 230, 240) and/or the downstream leaching unit (260) and/or the post-processing unit, the latter if present, for at least partial consumption in oxidation.
Aspect 43. A hydrometallurgical process for processing a metal-bearing material, such as mineral ore, concentrate, tailings, matte, slag, and calcine, containing one or more metal values, the process comprising the steps of:
Aspect 44. The process of the preceding aspect further comprising:
Aspect 45. The process of aspect 43 or aspect 44 further comprising:
Aspect 46. The process of any one of aspects 43 to 45 wherein at least one of the one or more units (230, 260) of the hydrometallurgical processing circuit (20) comprises a pressure vessel, preferably an autoclave, the process furthermore comprising the steps of
Aspect 47. The process of any one of aspects 43 to 46 wherein at least one of the one or more units (230, 260) of the hydrometallurgical processing circuit (20) comprises a pressure vessel, preferably an autoclave, the process furthermore comprising the steps of
Aspect 48. The process of aspect 46 or aspect 47 wherein the pressure vessel is operatively disposed to receive at least a portion (22, 24) of the metal-bearing material, the process furthermore comprising the steps of
Aspect 49. The process of any one of aspects 43 to 48 wherein
Aspect 50. The process of the preceding aspect wherein at least a first portion of the oxidant gas (150, 151, 153) is introduced into the pre-processing unit (210, 230, 240) and/or at least a second portion (152) of the oxidant gas is introduced into the downstream leaching unit (260) for oxidation.
Aspect 51. The process of any one of aspects 43 to 50 comprising
Aspect 52. The process of the preceding aspect, furthermore comprising the step of recovering heat from the at least a portion (151, 152) of the oxidant gas before introducing the at least a portion (151, 152) of the oxidant gas into the at least one oxygen consuming unit (230, 260) in step (g).
Aspect 53. The process of any one of aspects 43 to 52 wherein the pre-processed portion (24) of the metal-bearing material is leached in step (f) in the downstream leaching unit (260), and at least a portion (152) of the oxidant gas is introduced in step (g) into the downstream leaching unit (260) to provide oxidant for oxidative leaching.
Aspect 54. The process of any one of aspects 43 to 53 wherein at least a portion (150) of the oxidant gas is introduced into a grinding unit (210) of the hydrometallurgical processing circuit (20) for grinding the at least a portion of the metal-bearing material (21) in an oxygen-containing gas or liquid, and wherein at least a portion of the ground material is leached in step (f).
Aspect 55. The process of any one of aspects 43 to 53 wherein at least a portion (150) of the nitrogen-enriched product (13) from the ion transport membrane assembly (10) is introduced into a grinding unit (210) of the hydrometallurgical processing circuit (20) for grinding at least a portion of the metal-bearing material (21) in an oxygen-deficient environment, and wherein at least a portion of the ground material is leached in step (f).
Aspect 56. The process of any one of aspects 43 to 55 wherein at least a portion (151) of the oxidant gas is introduced into a pressure oxidation unit (230) for oxidizing at least a portion (22) of the metal-bearing material, and wherein at least a portion (24) of the metal-bearing material from the pressure oxidation unit (230) is leached in step (f).
Aspect 57. The process of any one of aspects 43 to 56 wherein at least a portion (151, 153) of the oxidant gas is introduced into a pre-processing unit (230, 240) for oxidizing or leaching at least a portion (22) of the metal-bearing material or neutralizing a solution (23) containing at least one metal value of the metal-bearing material in solution, and wherein at least a portion (24) of the pre-processed material from the pre-processing unit (230, 240) is leached in step (f).
Aspect 58. The process of any one of aspects 43 to 57 wherein at least a portion (150) of the oxidant gas is introduced into a grinding unit (210) for grinding at least a portion (21) of the metal-bearing material in an oxygen containing gas or liquid and/or into a roasting unit for roasting at least a portion of the metal-bearing material, and wherein at least a portion (24) of the ground and/or roasted material is leached in step (f).
Aspect 59. The process of any one of aspects 43 to 58 furthermore comprising one or more of the following steps:
Aspect 60. The process of any one of aspects 43 to 59 wherein the hydrometallurgical processing circuit (20) comprises a flotation unit (215), the process furthermore comprising the steps of:
Aspect 61. The process of any one of aspects 43 to 60 furthermore comprising the steps of:
Aspect 62. The process of any one of the aspects 43 to 61 wherein the hydrometallurgical processing circuit (20) comprises an oxygen activation unit (160), the process furthermore comprising the steps of:
The invention is explained below by way of examples with reference to figures. Features disclosed there, each individually and in any combination of features, advantageously develop the subjects of the claims and also the embodiments and aspects described above.
The ensuing detailed description provides preferred exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the ensuing detailed description of the preferred exemplary embodiments will provide those skilled in the art with an enabling description for implementing preferred exemplary embodiments of the invention, it being understood that various changes may be made in the function and arrangement of elements without departing from scope of the invention as defined by the claims.
The articles “a” and “an” as used herein mean one or more when applied to any feature in embodiments of the present invention described in the specification and claims. The use of “a” and “an” does not limit the meaning to a single feature unless such a limit is specifically stated. The article “the” preceding singular or plural nouns or noun phrases denotes a particular specified feature or particular specified features and may have a singular or plural connotation depending upon the context in which it is used. The adjective “any” means one, some, or all indiscriminately of whatever quantity.
The term “and/or” placed between a first entity and a second entity includes any of the meanings of (1) only the first entity, (2) only the second entity, and (3) the first entity and the second entity. The term “and/or” placed between the last two entities of a list of 3 or more entities means at least one of the entities in the list including any specific combination of entities in this list. For example, “A, B and/or C” has the same meaning as “A and/or B and/or C” and comprises the following combinations of A, B and C: (1) only A, (2) only B, (3) only C, (4) A and B and not C, (5) A and C and not B, (6) B and C and not A, and (7) A and B and C.
The phrase “at least one of” preceding a list of features or entities means one or more of the features or entities. For example, “at least one of A, B, or C” has the same meaning as “A and/or B and/or C” and comprises the following combinations of A, B and C: (1) only A, (2) only B, (3) only C, (4) A and B and not C, (5) A and C and not B, (6) B and C and not A, and (7) A and B and C.
The phrase “at least a portion” means “a portion or all.” The at least a portion of a stream or material may have the same composition as the stream or material from which it is derived. The at least a portion of a stream or material may include all or only specific components of the stream or material from which it is derived. A stream or material may be subjected to one or more material processing steps, for example chemical treatment and/or physical treatment, to form the at least a portion of that stream or material.
As used herein, “first”, “second”, “third”, etc. are used to distinguish from among a plurality of steps and/or features, and is not indicative of the relative position in time and/or space.
In the claims, letters may be used to identify claimed steps (e.g. (a), (b), and (c)). These letters are used to aid in referring to the method steps and are not intended to indicate the order in which claimed steps are performed, unless and only to the extent that such order is specifically recited in the claims.
An ion transport membrane layer is an active layer of ceramic membrane material comprising mixed metal oxides capable of transporting or permeating oxygen ions at elevated temperatures. The ion transport membrane layer also may transport electrons as well as oxygen ions, and this type of ion transport membrane layer typically is described as a mixed conductor membrane layer. The ion transport membrane layer also may include one or more elemental metals thereby forming a composite membrane.
The membrane layer, being very thin, is typically supported by a porous layer support structure and/or a ribbed support structure. The support structure is generally made of the same material (i.e. it has the same chemical composition), so as to avoid thermal expansion mismatch. However, the support structure might comprise a different chemical composition than the membrane layer.
A membrane unit, also called a membrane structure, comprises a feed zone, an oxygen product zone, and a membrane layer disposed between the feed zone and the oxygen product zone. An oxygen-containing gas is passed to the feed zone and contacts one side of the membrane layer, oxygen is transported through the membrane layer, and an oxygen-depleted gas is withdrawn from the feed zone. An oxygen gas product, which may contain at least 95 vol. % or at least 97 vol. % or preferably at least 99 vol. % oxygen, is withdrawn from the oxygen product zone of the membrane unit. The membrane unit may have any configuration known in the art. When the membrane unit has a planar configuration, it is typically called a “wafer.”
A membrane module, sometimes called a “membrane stack,” comprises a plurality of membrane units. Membrane modules in the present ion transport membrane assembly 70 may have any configuration known in the art.
An “ion transport membrane assembly” comprises one or more membrane modules, a pressure vessel containing the one or more membrane modules, and any additional components necessary to introduce one or more feed streams and to withdraw two or more effluent streams formed from the one or more feed streams. The additional components may comprise flow containment duct(s), insulation, manifolds, etc. as is known in the art. When two or more membrane modules are used, the two or more membrane modules in an ion transport membrane assembly may be arranged in parallel and/or in series with respect to the predominate direction of flow of either the feed or permeate streams.
Exemplary ion transport membrane layers, membrane units, membrane modules, and ion transport membrane assemblies are described in U.S. Pat. Nos. 5,681,373, 7,179,323, and 7,955,423.
The ion transport membrane assembly 10 comprises one or more membranes each with one or more membrane layers. The one or more membranes are of the mixed conductor type, wherein oxygen ions migrate through the membrane driven by an oxygen partial pressure differential. The hydrometallurgical processing circuit 20 comprises a pre-processing unit for pre-processing at least a portion of the metal-bearing material 1 for a downstream leaching process in a downstream leaching unit also comprised by the hydrometallurgical processing circuit 20. The pre-processing unit, if present, may be one of a grinding unit, a roasting unit, a pressure oxidation unit, a bio-oxidation unit, an upstream leaching unit, and a solution neutralization unit. The hydrometallurgical processing circuit 20 may comprise at least one post-processing unit operatively disposed to receive at least a portion of a discharge material from the downstream leaching unit for post-processing. The at least one post-processing unit, if present, may be one of a further leaching unit, a solution neutralization unit, and a remediation unit for the remediation of toxic lixiviant. Should hydrometallurgical processing in the hydrometallurgical processing circuit 20 include, for example, cyanidation as the downstream leaching process cyanide may be oxidized to cyanate in the optional remediation unit. The hydrometallurgical processing circuit 20 may comprise an acid production unit for the production of acid. In operation each of the units specifically mentioned may consume oxygen. The hydrometallurgical processing circuit 20 comprises at least one such oxygen consuming unit and may comprise two or more of these oxygen consuming units.
In operation, an oxygen-containing first feed gas 11 is introduced through an inlet on a feed side of the ion transport membrane assembly 10 at a feed temperature of typically 700° C. to 1000° C. and a feed pressure of typically 1000 kPa to 4000 kPa. A stream of gaseous oxygen-depleted nitrogen-enriched product 13 is withdrawn through a first outlet on the feed or non-permeate side of the membrane assembly 10 at near feed temperature and near feed pressure. A stream of gaseous oxygen product 15 is withdrawn on the permeate side through a second outlet of the membrane assembly 10 at near feed temperature and a second outlet pressure. In pressure driven embodiments the permeate or second outlet pressure may be selected to fall into the range of, for example, approximately 20 to 300 kPa (absolute); and more preferred into the range of, for example, approximately 40 to 150 kPa; and may most preferred be in the order of around 50 kPa.
At least a portion of the oxygen product 15 is fed to the hydrometallurgical processing circuit 20 to provide at least a portion of the oxygen consumed in the one or more oxygen consuming units of the processing circuit 20. All or only part of the oxygen product 13 fed to the hydrometallurgical processing circuit 20 can provide heat to one or more oxygen consuming units by contact and/or reaction with the material processed in the respective unit and/or by indirect heat exchange during the process and/or before introduction into the process. The at least a portion of the oxygen product 13 can be cooled by indirect heat exchange with one or more effluent streams and/or internal material streams of the hydrometallurgical processing circuit 20 before introducing the at least a portion of the oxygen product 15 into the one or more oxygen consuming units.
Dashed lines illustrate units and connections which are only optional although advantageous to the process and processing system of the invention. One or more or all of the units and connections illustrated in dashed lines may be present in advantageous developments of the basic process and processing system of the invention. Whereas units and connections optional to the invention are characterized this way in
Integration of the ion transport membrane 10 and the hydrometallurgical processing circuit 20 can be improved by recycling gaseous oxygen-containing effluent 25 from the hydrometallurgical processing circuit 20 to the ion transport membrane assembly 10 and/or to at least a portion of the oxygen product 15 from the ion transport membrane assembly 10. Oxygen-containing recycle effluent 25 may accordingly be mixed with the oxygen-containing feed gas 7 to form the first feed gas 11 which is separated by the ion transport membrane assembly 10 into the non-permeate and permeate products 13 and 15. Instead of feeding to the feed side of the ion transport membrane assembly 10 the oxygen-containing recycle effluent 25 may be mixed with at least a portion of the oxygen product 15. In yet a further alternative, the oxygen-containing recycle effluent 25 may be split into at least two portions (streams), a first of these portions mixed with the oxygen-containing feed gas 7 to form the first feed gas 11 or at least a portion thereof, and a second of the portions of recycle effluent 25 mixed with the oxygen product 15, as illustrated in
Recycle effluent 25 may originate from the downstream leaching unit and/or from one or more pre-processing units such as a grinding unit, a roasting unit, a pressure oxidation unit, and an upstream leaching unit, in particular an oxidative pressure leaching unit, and/or from one or more post-processing units such as a further leaching unit. In embodiments, in which one or more hydrometallurgical processing units comprise one or more autoclaves, for example, one or more autoclaves for pressure oxidation and/or one or more autoclaves for oxidative pressure leaching, the oxygen-containing recycle effluent 25 may advantageously originate from at least one of these autoclaves. One or more autoclaves may each comprise an effluent outlet through which oxygen-containing recycle effluent can be withdrawn from the pressurized gas built-up above the slurry or solution treated in the respective autoclave.
Effluent 25 may originate from a single unit of the hydrometallurgical processing circuit 20. In alternative embodiments, oxygen-containing effluent from two or more units of the hydrometallurgical processing circuit 20 may be mixed to form recycle effluent 25, e.g. oxygen-containing effluent from two or more autoclaves and/or one or more of the other units mentioned may be combined to form recycle effluent 25 as a combined recycle effluent 25. Effluent 25 may be fed back and mixed with oxygen-containing feed gas 7 expediently at a location where the temperatures and/or pressures and/or oxygen concentrations of the two streams 7 and/or 15 on the one and 25 on the other hand are matching closest. Various alternative and complementary options for recycling effluent 25 taking its temperature and/or pressure and/or oxygen concentration into account are available. Specific options 25.1 to 25.5 are denoted in
Numerous other arrangements are possible, and will readily be configured by one skilled in the art.
Any of streams 25.1 to 25.4 is mixed with oxygen-containing feed gas 7 upstream of membrane assembly 10. Valuable is in particular oxygen-containing recycle effluent 25 of high temperature and/or high pressure and/or high oxygen concentration which can be mixed with at least a portion of the oxygen product 15 and/or oxygen-containing feed gas 7 after compression of feed gas 7, e.g. by a compressor driven by turbine 30, and/or after heating of feed gas 7, e.g. by indirect heat exchange in heat exchanger 16. Particularly valuable is effluent gas from an autoclave operated with an oxidant gas having a high oxygen purity as is often the case in pressure oxidation and oxidative pressure leaching. A pressure oxidation unit and/or an oxidative pressure leaching unit of circuit 20, for example, the downstream leaching unit, may be operated to keep the oxygen concentration of the atmosphere within a pressure vessel of the respective unit at an operational level above that of ambient air, e.g. at or above 50 mol. %, or 70 mol. %, or 80 mol. %. To maintain the oxygen concentration at the high operational level despite oxygen consumption, bleed gas containing oxygen at the operational level may be withdrawn and oxidant gas of higher oxygen purity introduced. Such a bleed gas may in particular be recycled as or in the recycle effluent 25 or any of the recycle effluent streams 25.1 to 25.5.
Oxygen-containing recycle effluents from two or more units of the hydrometallurgical processing circuit 20 may be kept separate from one another and fed back as separate streams, in particular, if recycle effluents of different sources (units) differ widely with respect to temperature and/or pressure and/or oxygen concentration. If, for example, gaseous effluent of a first unit has a higher oxygen concentration than gaseous effluent of a second unit, the effluent of the first unit may be recycled as recycle effluent 25.5 mixed with at least a portion of the oxygen product 15 sent to circuit 20, and gaseous effluent of the second unit may be recycled in or as any one of recycle effluents 25.1 to 25.4 mixed with oxygen-containing feed gas 7 upstream of membrane assembly 10. If, as a further example, gaseous effluent of a first unit has a higher temperature than gaseous effluent of a second unit, the effluent of the first unit may be recycled in or as recycle effluent 25.3 or 25.4, and gaseous effluent of the second unit may be recycled in or as any one of recycle effluents 25.1 to 25.3. Reference sign 25 may accordingly denote either a combined recycle effluent stream or a plurality of separate recycle effluent streams complying with any two or more of streams 25.1 to 25.5.
The internal energy (heat and work) of the nitrogen-enriched product 13 can be recovered at least partially to generate electric and/or mechanical power and/or steam and/or by indirect heat exchange with one or more other process streams and/or by combustion with fuel 17. A turbine 30 may operatively be disposed to receive at least a portion of the nitrogen-enriched product 13 from the ion transport membrane assembly 10 at a turbine high-pressure side to drive the turbine 30 by expansion. An oxygen-containing feed gas 7, for example air, may be compressed by a compressor coupled with the turbine 30 to be driven either directly by means of a mechanical coupling or indirectly by means of an electric coupling. The compressed oxygen-containing gas 7 may be fed to the ion transport membrane assembly 10 as the first feed gas 11 directly or after further compression and/or heating by indirect heat exchange in a heat exchanger 23 and/or combustion with fuel 5. All or only a portion of the oxygen-containing gas 7 compressed by mechanical and/or electric power generated by the turbine 30 may constitute all or only a portion of the first feed gas 11.
Turbine 30 driven by expansion of the nitrogen-enriched gas 13 may be coupled with a generator 50 to produce electric energy 57 which may be utilized to drive one or more agitators in one or more units of the hydrometallurgical processing circuit 20. For example, the generator 50 alone or in combination with some other source of electrical energy may drive one or more agitators in an autoclave of a pressure oxidation unit and/or a pressure leaching unit and/or an atmospheric leaching unit and/or a bio-oxidation unit.
The integrated hydrometallurgical processing system may comprise a heat recovery steam generator (HRSG) 40 operatively disposed to receive a steam generator feed stream 31 comprising at least a portion of the nitrogen-enriched product 13 from the ion transport membrane assembly 10. The HRSG 40 may receive all or only part of the nitrogen-enriched product 13 directly from the ion transport membrane assembly 10, i.e. without intermediate energy recovery from product 13. In expedient embodiments however the at least a portion of the nitrogen-enriched product 13 is fed to the HRSG 40 after having recovered work by means of a turbine such as turbine 30. In alternative embodiments of a combined recovery of work and heat a turbine may be arranged downstream of the HRSG 40 to recover work after having extracted at least part of the thermal energy of the at least a portion of the nitrogen-enriched product 13.
HRSG 40 extracts thermal energy from steam generator feed gas 31 by indirect heat exchange with feed water 41 to make steam 43. The steam 43 generated by HRSG 40 can be fed to the hydrometallurgical processing circuit 20 for heating and/or conditioning purposes, for example, in an autoclave of a pressure oxidation unit or leaching unit, and/or for heating a feed slurry 21 of metal-bearing material, only to name examples for utilization. The processing system may comprise a steam turbine 60 operatively disposed to receive at least a portion of steam 43 generated by HRSG 40 to recover work. Steam expanded in steam turbine 60 can be fed to the hydrometallurgical processing circuit 20 and utilized there for at least one of the purposes mentioned in connection with steam 43. Steam turbine 60 may be coupled with a generator, mechanically or electrically, for the production of electrical energy which may be used in the hydrometallurgical processing circuit 20. HRSG off-gas 45 may be purified in a purification unit to produce a nitrogen product for ammonia production. Steam generator feed gas 31 may be heat exchanged with feed water 41 in HRSG to recover only sensible heat from steam generator feed gas 31. At least a portion of steam generator feed gas 31, however, may be combusted with fuel 47 to produce additional thermal energy, and the combustion gas heat exchanged with feed water 41.
The hydrometallurgical processing system may comprise a heat exchanger 100 for heating initial material 1 and/or one or more slurries or solutions of metal-bearing material which may be formed at different stages of a multi-stage processing circuit 20, such as slurries 21 to 24, as will be explained later. Slurry 22 and slurry 24 may for example be fed to autoclaves of the hydrometallurgical processing circuit 20. At least part of the heat for heating initial material 1 and/or one or more of slurries 21 to 24 can be provided by nitrogen-enriched product 13 from the ion transport membrane assembly 10. Heat exchanger 100 may therefore be operatively disposed to receive at least a portion of the nitrogen-enriched product 13 directly or, more preferred, at least a portion 33 of the nitrogen-enriched product 13 after expansion by optional turbine 30. One or more of initial material 1 and slurries 21 to 24 is/are preferably heated in heat exchanger 100 by indirect heat exchange with this at least a portion 33 of product 13. In the example embodiment the at least a portion 33 is a portion of steam generator feed gas 31.
At least a portion 32 of the nitrogen-enriched product 13 may be used in the hydrometallurgical process performed in hydrometallurgical processing circuit 20 as flotation gas in an optional flotation unit to float a portion of a flotation slurry containing one or more metal values, for example, to float molybdenum. Alternatively or in addition to a use as flotation gas, at least a portion 34 of the nitrogen-enriched product 13 may be used to dry the initial metal-bearing material 1 before slurry 21 has been formed and/or to dry ground material, only to mention examples for drying. The at least a portion 34 may be used as drying agent to dry by contact and/or to dry by indirect heat exchange. Furthermore, at least a portion of the nitrogen-enriched product 13 may be used for grinding in an oxygen-deficient gas. By “oxygen-deficient” it is meant that the respective gas or environment is either substantially free of oxygen or, if the respective gas or environment does contain some oxygen, the molar fraction of oxygen is smaller than the molar fraction of oxygen contained in ambient air. An oxygen-deficient gas or environment does preferably contain less than 15 mol. %, or less than 10 mol. % of oxygen. Oxygen concentrations of less than 5 mol. % are even more preferred.
The hydrometallurgical processing system may comprise a hydrogen production unit 70 operatively disposed to receive a hydrogen production feed stream 71 and adapted to provide a hydrogen-containing product 73. The hydrogen production feed stream 71 may comprise natural gas or any hydrocarbon-containing feedstock known for hydrogen production. All or only a portion of the hydrogen-containing product 73 can be exported at 74. More preferred, at least a portion 75 of the hydrogen-containing product 73 is fed to the hydrometallurgical processing circuit 20 and used for metal reduction and/or pH adjustment and/or other conditioning purposes within circuit 20. In addition or instead of utilizing the hydrogen-containing product 73 or at least a portion 75 thereof directly, i.e. as molecular hydrogen (H2), all or only part of the hydrogen-containing product 73 can be used to produce ammonia in an optional ammonia production unit of the hydrometallurgical processing system. A material processing system comprising an ammonia production unit 90 is shown in
A first portion 75 of hydrogen-containing product 73 is fed to the hydrometallurgical processing circuit 20 to be used directly for one or more of the purposes already mentioned with respect to the first example embodiment. Ammonia production unit 90 is operatively disposed to receive a second portion 77 of hydrogen-containing product 73 either directly or after one or more purification steps. Ammonia production unit 90 is furthermore operatively disposed to receive at least a portion of the nitrogen-enriched product 13 from the ion transport membrane assembly 10. Nitrogen-enriched product 13 is expediently purified in an optional nitrogen purification unit 80 operatively disposed to receive product 13 from the ion transport membrane assembly 10 and deliver a purified nitrogen product 87 to the ammonia production unit 90. Hydrogen-containing product portion 77 is expediently purified in a hydrogen purification unit operatively disposed to receive hydrogen product portion 77 and deliver a purified hydrogen product to the ammonia production unit 90. At least a portion of the ammonia product 93 of ammonia production unit 90 can be utilized in one or more units of the hydrometallurgical processing circuit 20. Hydrometallurgical processing circuit 20 may therefore be operatively disposed to receive at least a portion 94 of the ammonia product 93. All or preferably only a portion of the ammonia product 93 may be exported as export ammonia 95.
All of the ammonia product 93 that is produced by ammonia production unit 90, or only product portion 94 may be incorporated in various integrations with the material processing in hydrometallurgical processing circuit 20. Utilization examples that are shown in
Any of the options of integration explained with reference to
In operation, a metal-bearing material 1, for example, crushed mineral ore, is ground in grinding unit 210. Grinding unit 210 can in particular be a ball mill. If the initial material 1 contains excessive water material 1 may be dried in a drying unit 208 to reduce its water content before grinding to form a dried material to be ground as such or in a slurry 21. Nitrogen-enriched product portion 34 may be used for drying at least a portion of the initial material 1 by indirect heat exchange and/or direct contact, i.e. by passing the at least a portion of nitrogen-enriched product 13 through material 1.
At least a portion of the ground material may be subjected to flotation in a flotation unit 215 to produce a flotation concentrate and a flotation tail. Nitrogen-enriched product portion 32 of adequate pressure and temperature, as indicated e.g. in
Pressure oxidation unit 230 comprises at least one autoclave, preferably a multi-compartment autoclave, operatively disposed to receive autoclave slurry 22 from slurry preparation unit 220. Autoclave slurry 22 from slurry preparation unit 220 may be heated by indirect heat exchange in optional heat exchanger 100, as explained above with respect to
Pressure oxidized discharge slurry 23 from the pressure oxidation unit 230 is neutralized in a solution neutralization unit 240 to separate the pressure oxidized discharge in different portions (fractions) in a subsequent separation unit 250. A slurry 24 of a resultant fraction containing one or more metal values to be recovered, e.g. one or more precious metals, is sent to downstream pressure leaching unit 260 for leaching, preferably oxidative pressure leaching. The discharge of separation unit 250 may have to be subjected to intermediate conditioning and/or one of cooling and heating to produce slurry 24 for downstream leaching. If heating is required slurry 24 may be heated by indirect heat exchange in optional heat exchanger 100, as explained above with respect to
Downstream leaching unit 260 may in particular be an oxidative leaching unit, preferably an oxidative pressure leaching unit. It may comprise at least one autoclave, preferably a multi-compartment autoclave, operatively disposed to receive slurry 24 for leaching. A metal value containing solution from downstream leaching unit 260 is sent to a post-processing circuit for extraction/purification in an extraction/purification unit 270 and/or subjected to hydrogen reduction in a hydrogen reduction unit 280. A metal value containing portion (fraction) discharged from the post-processing circuit is further refined in a refining unit 290 downstream of hydrogen reduction unit 280 to produce refined metal product 27.
In embodiments in which the integrated hydrometallurgical processing system of the invention comprises an on-site acid production unit 300 for the production of acid 302, for example, sulfuric acid, and/or an on-site hydrogen production unit 70 such units 70 and/or 300 may also need oxygen. At least a portion 154 of the oxygen product 15 may therefore be sent to optional on-site acid production unit 300, and/or at least a portion 155 may be sent to optional on-site hydrogen production unit 70. At least a portion of a hot flue gas 74 of hydrogen production unit 70, if present, may be heat exchanged with water in an optional heat recovery steam generator 315 to generate steam 79 for use in the hydrometallurgical processing, e.g. in hydrogen reduction unit 280. A comparable set-up is shown for the optional acid production unit 300. At least a portion of a hot flue gas from acid production unit 300 may be cooled by indirect heat exchange with water in a heat recovery steam generator 305 to generate steam 309 for use in the hydrometallurgical processing, e.g. in pressure oxidation unit 230. Heat recovery steam generator 305 and/or heat recovery steam generator 315 may be combined with HRSG 40 or may be combined one with the other to generate steam for one or more of the units of the hydrometallurgical processing circuit 20, for example, to generate steam for the pressure oxidation unit 230 and/or hydrogen reduction unit 280, as illustrated, or a leaching unit of circuit 20, for example, the downstream leaching unit 260.
Grinding unit 210 may grind metal-bearing material 1 or slurry 21 containing at least a portion of material 1 in an oxygen-containing gas or liquid, in particular in example embodiments in which grinding unit 210 is a fine or ultra-fine grinder. Grinding in oxygen can provide for metal activation already during grinding. At least a portion 150 of the oxygen product 15 may therefore be sent to grinding unit 210 for grinding in oxygen or in an oxygen gas mixture, e.g. in oxygen air. In alternative embodiments it might be desirable to impede oxidation during grinding. In those embodiments grinding unit 210 may operatively be disposed to receive an oxygen-deficient gas containing at least a portion of the nitrogen-enriched product 13 from the ion transport membrane assembly 10 for grinding in an oxygen-deficient environment.
Any autoclave receiving at least a portion 151 or 152 of the oxygen product 15 may comprise a gassing system for the introduction of the assigned portion 151 or 152 to inject the same into the slurry or solution within the respective autoclave. The gassing system is preferably adapted to sparge the received at least a portion 152 or 152 through the slurry or solution in the respective autoclave. One or more mechanical agitators, typically arranged in an autoclave, may agitate the slurry or solution to intensify contact with the metal-bearing material in the slurry or solution.
The oxygen product 15 from ion transport membrane assembly 10 may provide for all of the oxidant or at least all of the oxygen consumed in the hydrometallurgical process, as preferred. In alternative embodiments, however, ion transport membrane assembly 10 may supply only part of the oxidant consumed in circuit 20. Oxidant gas provided to one or more oxygen consuming units of circuit 20 contains at least a portion of oxygen product gas 15 and may contain one or more other oxidants, such as, chlorine, and/or oxygen from some other oxygen sources.
Furthermore, oxygen product 15 from ion transport membrane assembly 10 may be provided as such, i. e. as diatomic oxygen, to one or more oxygen consuming units of circuit 20. In developments, at least a portion of the oxygen product 15 from ion transport membrane assembly 10 may be activated in an oxygen activation unit and provided as activated oxygen, in particular, as ozone, to one or more oxygen consuming units of circuit 20 to increase the rate of oxidation in the respective unit. Oxidant gas introduced into one or more oxygen consuming units of circuit 20 may accordingly consist of or comprise activated oxygen generated from at least a portion of the oxygen product 15 from ion transport membrane assembly 10.
This invention was made with government support under Cooperative Agreement No. DE-FC26-98FT40343 between Air Products and Chemicals, Inc. and the U.S. Department of Energy. The United States Government has certain rights in this invention.
