Patent Application
20230416869
The present disclosure relates to a method and a smelting unit for pyrometallurgical smelting of metal-containing raw materials, waste materials and/or secondary waste materials in the presence of an oxidizing, reducing and/or inert gas.
In principle, methods and corresponding smelting units for pyrometallurgical smelting of metal-containing raw materials, waste materials and/or secondary waste materials are known from the prior art. For example, WO 91/05214 discloses a TSL (top submerged lancing) system and a method for feeding a fluid into a pyrometallurgical melt, wherein the fluid, for example oxygen, is injected directly into the melt.
European patent EP 0 723 129 B1 discloses a smelting method for scrap, mixtures of scrap and cast iron, and mixtures of scrap and sponge iron in electric arc furnaces. In the furnace, an oxidizing gas is fed through blowing nozzles located in the bottom of the furnace at pressures of a maximum of 10 bar and flow rates in the range of 168-360 Nm3/h. In addition, oxygen is fed to the melt bath by means of supersonic lances operating in a working position immediately above the surface of the molten metal and thus within the slag phase. The supersonic lances introduce the oxygen into the melt bath at an angle of 40° to 50° from the horizontal.
Furthermore, Chinese patent application CN 104928493 A discloses a method for recovering metals from secondary materials by means of a smelting reactor. This has a circular chamber that is bounded by a coolable reactor wall. A plurality of oxygen lances are arranged in the reactor wall below a slag opening, at an angle of 5°-60° to the horizontal and with an offset to the center of the chamber, such that the oxygen can be injected directly into the melt and the melt can be made to rotate within the circular chamber.
Due to the direct contact of the lances with the melt, the lances known from the prior art are subject to high wear due to the very rough conditions. As such, there is a continuing desire among experts to improve such methods along with the corresponding smelting units.
The present disclosure is based on the object of providing a method along with a smelting unit that overcome the disadvantages of the prior art.
The object is achieved by a method as disclosed herein and by a melting unit as disclosed herein.
In accordance with a method for pyrometallurgical smelting of metal-containing raw materials, waste materials and/or secondary waste materials, these are fed in shredded form to a smelting unit, which comprises a smelting zone, a main reaction zone and a secondary reaction zone and are smelted in the presence of an oxidizing, reducing and/or inert gas and/or gas mixture, such that a liquid melt phase, a liquid slag phase and a gas phase are formed.
The method is characterized in that the oxidizing, reducing and/or inert gas and/or gas mixture is injected into the liquid slag phase via at least one injector arranged in the smelting unit above and without contact with it and oriented at an angle of 5° to 85°, preferably at an angle of 15° to 80°, more preferably at an angle of 25° to 75°, still more preferably at an angle of 35° to 70°, with respect to the horizontal.
In the same manner, the disclosure provides a smelting unit suitable for pyrometallurgical smelting of metal-containing raw materials, waste materials and/or secondary waste materials in the presence of an oxidizing, reducing and/or inert gas and/or gas mixture, comprising a smelting zone, a main reaction zone and a secondary reaction zone bounded by a reactor wall, and at least one injector arranged in the reactor wall.
The smelting unit is characterized in that the at least one injector is arranged in the secondary reaction zone and is oriented at an angle of 5 to 85°, preferably at an angle of 15° to 80°, more preferably at an angle of 25° to 75°, even more preferably at an angle of 35° to 70°, with respect to the horizontal, such that the oxidizing, reducing and/or inert gas and/or gas mixture can be blown into the liquid slag phase above it.
Thus, the oxidizing, reducing and/or inert gas and/or gas mixture is injected or can be injected into the liquid slag phase via at least one injector arranged above the bath level of the liquid slag phase and positioned at a specific angle to the horizontal. Such an injection of the oxidizing, reducing and/or inert gas and/or gas mixture causes the liquid slag phase to become highly turbulent, such that it splashes into the gas phase located above the liquid molten phase and in the secondary reaction zone. Surprisingly, it has thereby been shown that this results in a surface area that is at least a factor of 5, preferably at least a factor of 6, more preferably at least a factor of 7, and most preferably at least a factor of 8 larger than that of the liquid melt phase in the process, which leads to particularly intensive contact along with an increased mass and energy transfer with the gas phase arranged above the liquid melt phase and located in the secondary reaction zone. By arranging the at least one injector at a specific angle to the horizontal, the liquid slag phase is also set in rotation, such that a vortex is formed within the main along with the secondary reaction zone, which additionally supports the turbulence. In this manner, a maximum turbulent environment can be created within the smelting unit, which ensures a particularly effective metallurgical reaction.
Further advantageous embodiments are indicated in the dependent formulated claims. The features listed individually in the dependent formulated claims can be combined with one another in a technologically useful manner and may define further embodiments of the invention. In addition, the features indicated in the claims are further specified and explained in the description, wherein further preferred embodiments of the invention are illustrated.
In the context of the present disclosure, the term “without contact” is understood to mean that the at least one injector, via which the oxidizing, reducing and/or inert gas and/or gas mixture can be injected into the smelting unit, both during injection and in the process steps in between, is not in continuous contact with the liquid slag phase, but is positioned at a specific distance therefrom and thus above the bath level throughout the entire process. This does not include temporary contact of individual drops of the liquid slag phase and/or the liquid melt phase, which can occur during the process as a function of the strong turbulence and thus cannot be prevented.
In the context of the present disclosure, unless otherwise defined, the term “injector” means a lance or injection tube formed substantially of a hollow cylindrical element.
In the context of the present disclosure, the term “smelting unit” is understood to mean a conventional bath smelting unit, which comprises a hollow cylinder, hollow cone or hollow cuboid standing on a round or angular base surface, wherein the height of the hollow cylinder, hollow cone or hollow cuboid is a multiple of its length and width. Preferably, therefore, the main reaction zone of the smelting unit arranged above the smelting zone has a substantially circular and/or oval-shaped cross-section.
Other smelting units known to those skilled in the art from the prior art, such as electric arc furnaces (EAF), submerged arc furnaces (SAF) or induction furnaces (IF) are not included in the present invention.
Advantageously, it is provided that the at least one injector, via which the oxidizing, reducing and/or inert gas and/or gas mixture is injected into the liquid slag phase without contact, has a minimum distance of 0.10 m, preferably a minimum distance of 0.15 m, more preferably a minimum distance of 0.20 m, still more preferably a minimum distance of 0.25 m, and most preferably a minimum distance of 0.30 m from the surface of the liquid slag phase, relative to the injector tip. In addition to the agitating effect already explained and the turbulent mixing of the liquid slag phase with the adjacent gas phase, which leads to a particularly effective metallurgical reaction, the arrangement at a distance from the liquid slag phase also results in a significant reduction in wear of the injector. This also effectively prevents clogging of the injector, which requires a very high and cost-intensive maintenance effort with the solutions known from the prior art.
However, the at least one injector via which the oxidizing, reducing and/or inert gas and/or gas mixture is injected into the liquid slag phase without contact should not exceed a maximum distance from the surface of the liquid slag phase. Therefore, it is advantageously provided that the at least one injector has a maximum distance of 2.50 m, preferably a maximum distance of 2.0 m, more preferably a maximum distance of 1.50 m, even more preferably a maximum distance of 1.0 m, and most preferably a maximum distance of 0.80 m to the surface of the liquid slag phase, relative to the injector tip.
In this connection, it is noted that the bath level of the liquid slag phase does not have a static bath level or slag level throughout the process; rather, this can vary due to the different process phases. Therefore, it is particularly preferred that the at least one injector, via which the oxidizing, reducing and/or inert gas and/or gas mixture is injected into the liquid slag phase without contact, is positioned in the smelting unit in such a manner that a distance in the range from 0.30 m to 2.0 m, very preferably a distance in the range from 0.50 m to 1.70 m, from the surface of the liquid slag phase is ensured.
Preferably, the oxidizing, reducing and/or inert gas and/or gas mixture is injected into the liquid slag phase such that it penetrates into it to a minimum depth of ¼, preferably to a minimum depth of ⅓, more preferably to a minimum depth of 2/4, even more preferably to a minimum depth of ⅔, and most preferably to a minimum depth of ¾. By means of specific adjustment of the speed along with the gas flow pulse of the injected oxidizing, reducing and/or inert gas and/or gas mixture, the penetration depth is adjustable, such that, if required and depending on the two parameters, penetration into the liquid melt phase can also be achieved. This means that, if necessary, the metal-containing molten phase located below the liquid slag phase can also be manipulated. In addition, the gas jet can briefly rupture cavitations in the liquid slag phase, into which the metal-containing raw materials, waste materials and/or secondary waste materials are then torn and better decomposed within the slag phase.
In an advantageous embodiment, the oxidizing, reducing and/or inert gas and/or gas mixture injected into the slag phase via the at least one injector can be injected at a speed of at least 50 m/s, preferably at a speed of at least 100 m/s, more preferably at a speed of at least 150 m/s, even more preferably at a speed of at least 200 m/s, further preferably at a speed of at least 250 m/s, and most preferably at a speed of at least 300 m/s, wherein the speed values mentioned in the present case are exit speeds that the respective gas has upon exiting the injector, that is, at its tip.
With regard to the maximum speed, it is preferably provided that the oxidizing, reducing and/or inert gas and/or gas mixture is injected into the liquid slag phase at a speed of a maximum of 1000 m/s, more preferably at a speed of a maximum of 800 m/s, still more preferably at a speed of a maximum of 600 m/s, further preferably at a speed of a maximum of 550 m/s, and most preferably at a speed of a maximum of 450 m/s.
In this connection, it is particularly preferred that the at least one injector comprises a Laval nozzle via which the oxidizing, reducing and/or inert gas and/or gas mixture is blown into the liquid slag phase. A Laval nozzle is characterized by comprising a convergent section and a divergent section, which are adjacent to each other at a nozzle throat. The radius in the narrowest cross-section, the outlet radius along with the nozzle length can be different as a function of the respective design case. Such a Laval nozzle is known from the publication DE 10 2011 002 616 A1, to which reference is made herein and which constitutes part of the disclosure of the present invention.
In a further advantageous embodiment, the Laval nozzle additionally has a coaxial nozzle or an annular gap nozzle, via which a second oxidizing, reducing and/or inert gas and/or gas mixture can be blown onto the slag phase. While by means of the injector, preferably comprising a supersonic Laval nozzle, the first oxidizing, reducing and/or inert gas and/or gas mixture is injected into the liquid slag phase in such a manner that it penetrates it, the second oxidizing, reducing and/or inert gas and/or gas mixture is merely blown onto the slag phase via the annular gap nozzle and does not penetrate it. The second oxidizing, reducing and/or inert gas and/or gas mixture is therefore referred to as “sheath gas” in the context of the present disclosure, whereas the first oxidizing, reducing and/or inert gas and/or gas mixture is further referred to as “reaction gas.”
The first and/or second oxidizing gas and/or gas mixture is preferably selected from the series comprising oxygen, air and/or oxygen-enriched air. The first and/or the second reducing gas and/or gas mixture is preferably selected from the series comprising natural gas, in particular methane, carbon monoxide, water vapor, hydrogen, in particular green hydrogen, and/or gas mixtures thereof. The first and/or second inert gas and/or gas mixture is preferably selected from the series comprising nitrogen, argon, carbon dioxide and/or gas mixtures thereof.
In the context of the present disclosure, the term “green hydrogen” is understood to mean that it has been produced electrolytically by splitting water into oxygen and hydrogen, wherein the electricity required for electrolysis comes from renewable sources such as wind, hydropower and/or solar power.
The possibility of introducing, in addition to the reaction gas, a reactive and/or an inert sheath gas and/or a sheath gas mixture into the smelting unit advantageously permits open-loop control of the chemical potential along with closed-loop control of the oxygen partial pressure in the liquid slag phase along with the gas phase. Thereby, the chemical potential of the gas phase is formed by the reaction gas bubbles in the liquid melt and slag phase resulting from the metal-containing raw materials, waste materials and/or secondary waste materials to be melted down, the reaction gas introduced via the injector along with the sheath gas fed.
In a preferred embodiment, the composition of the reaction gas injected into the liquid slag phase can be kept constant, while the composition of the sheath gas can be selectively changed as a function of the requirements for the optimum open-loop control of the chemical potential of the gas atmosphere.
As a supplement and/or alternatively, in a further preferred embodiment, the composition of the sheath gas blown onto the slag phase can be kept constant, while the composition of the reaction gas or reaction gas mixture added to the liquid slag phase can be selectively changed as a function of the requirements for optimum control of the chemical potential.
Preferred flow rates at which the reaction gas is injected into the liquid slag phase are at least 300 Nm3/h, preferably at least 350 Nm3/h, more preferably at least 400 Nm3/h, even more preferably at least 450 Nm3/h and most preferably at least 500 Nm3/h. Since flow rates are a reference-dependent variable, they can be larger as a function of the unit size.
As explained previously, the arrangement of the at least one injector causes the liquid melt phase to rotate at a specific angle to the horizontal, such that a vortex within both the main and secondary reaction zones is formed. In order to achieve a particularly efficient vortex in the liquid slag phase, also one which has a beneficial effect with respect to the addition of the shredded metal-containing raw materials, waste materials and/or secondary waste materials, it is preferably provided that the reaction gas is blown into the slag phase via the at least one injector tangentially with respect to a notional flow ring, wherein the flow ring comprises a diameter that corresponds to 0.1 to 0.9 times the inner diameter, more preferably 0.1 to 0.8 times the inner diameter, even more preferably 0.2 to 0.7 times the inner diameter, and most preferably 0.2 to 0.6 times the inner diameter of the main reaction zone. Advantageously, it has been shown that, at a specific rotational speed of the liquid slag phase, a drum can be formed in the center of the latter, via which the shredded metal-containing raw materials, waste materials and/or secondary waste materials can be introduced directly into the liquid molten phase and/or can at least be taken up directly by the liquid slag phase and thus decomposed much faster in the process. In contrast to the processes known from the prior art, the decomposition process takes place in the desired main reaction zone or in the liquid slag phase, and not on its surface.
In a particularly advantageous embodiment, it is therefore provided that the metal-containing raw materials, waste materials and/or secondary waste materials are selectively fed into the center of the slag phase through an opening of the smelting unit arranged above the liquid slag phase.
The effect described above is particularly advantageous if the reaction gas is injected into the liquid slag phase via at least two, more preferably via at least three, still more preferably via at least four, and most preferably via at least five injectors arranged in a wall of the smelting unit, wherein the plurality of injectors are particularly preferably arranged at an equal distance along the circumference of the smelting unit.
In addition and/or alternatively, the shredded and/or possibly powdered metal-containing raw materials, waste materials and/or secondary waste materials can be added to the liquid slag phase via at least one, preferably via at least two, more preferably via at least three, injection lance(s) that are arranged in the region of the at least one injector. Via the at least one, advantageously a plurality of, injection lances, the shredded and/or optionally powdered material can be injected directly into the liquid slag phase, more preferably directly into the cavitation generated by the at least one injector within the liquid slag phase, and/or blown directly into the gas jet of the injector, by which the shredded and/or optionally powdered metal-containing raw materials, waste materials and/or secondary waste materials then enter the liquid slag phase. Thus, these may be effectively implemented with minimal losses. A particularly effective conversion is achieved if the material has a mean particle size of 0.01 to 5.0 mm, preferably a mean particle size of less than 3.5 mm, more preferably a mean particle size of less than 3.0 mm.
In another preferred embodiment, the reaction gas injected into the slag phase via the at least one injector can be pulsed.
The metal-containing raw materials, waste materials and/or secondary waste materials used in the present smelting process, if they comprise a noticeable proportion of hydrocarbons, may have a high energy content that requires intensive cooling of the smelting process. In a particularly preferred embodiment, it is therefore provided that the oxidizing, reducing and/or inert gas and/or gas mixture is fed in compressed form via the at least one injector and is adiabatically expanded within the smelting unit and then injected into the liquid slag phase as an adiabatically expanded gas and/or gas mixture. The adiabatic expansion of the oxidizing, reducing and/or inert gas and/or gas mixture or reaction gas results in a direct cooling effect inside the smelting unit, which allows the energy/heat balance of the process to be controlled in a targeted manner. Thus, by adjusting the pressure, the flow and/or the nozzle geometry of the injector, which preferably comprises a Laval nozzle, the adiabatic expansion of the reaction gas can be adjusted such that a cooling effect of at least J/Nm3, more preferably a cooling effect of at least 100 J/Nm3, still more preferably a cooling effect of at least 1.0 kJ/Nm3, and most preferably a cooling effect of at least 5.0 kJ/Nm3 is achievable.
With regard to the power values, it is pointed out that this is a power specification that is based on a standard cubic meter (Nm3) in accordance with DIN1343:1990-01.
In principle, the maximum value of the achievable cooling effect is physically limited by the Joule-Thompson effect. Therefore, by adjusting the pressure, the flow and/or the nozzle geometry of the injector, which preferably comprises the Laval nozzle, the adiabatic expansion of the reaction gas can be adjusted in such a manner that a cooling effect of a maximum of 100 KJ/Nm3, more preferably a cooling effect of a maximum of 90 kJ/Nm3, even more preferably a cooling effect of a maximum of 80 kJ/Nm3, and most preferably a cooling effect of a maximum of 70 kJ/Nm3 is achievable.
It should be noted that the cooling effect specified here can only be achieved with gases and/or gas mixtures that have a positive Joule-Thompson coefficient μ.
Furthermore, it has been shown advantageously that the adiabatic expansion of the reaction gas within the smelting unit can further increase the formation of the large specific surface of the liquid slag phase, which ultimately leads to the particularly intensive contact with the surrounding gas atmosphere and increases the chemical reactions along with their degree of conversion.
By direct cooling inside the smelting unit by means of the reaction gas, which is thus also used as a cooling medium, the external cooling measures usually carried out by using cooling panels and/or cooling channels may advantageously be extended, which significantly simplifies and improves the overall cooling management. Furthermore, direct cooling can extend the service life of the refractory lining of the smelting units, which has a beneficial effect on the operating efficiency of the smelting units.
In principle, the method is provided for pyrometallurgical smelting of metal-containing raw materials, waste materials and/or secondary waste materials. In particular, these are raw materials, waste materials and/or secondary waste materials containing antimony, bismuth, lead, iron, gallium, gold, indium, copper, nickel, palladium, platinum, rhodium, ruthenium, silver, zinc and/or tin, such as in particular organic-containing scrap.
In the context of the present disclosure, organic-containing scrap is understood to be any scrap comprising an organic component. Preferred organic-containing scrap is selected from the series comprising electrical scrap, auto shredder scrap and/or transformer shredder scrap, in particular shredder waste (light fraction).
In the context of the present disclosure, the term “electronic scrap” is understood to mean old electronic equipment as defined in accordance with EU Directive 2002/96/EC. Categories of equipment covered by this Directive relate to large household appliances; small household appliances; IT and telecommunications equipment; consumer electronics equipment; lighting equipment; electrical and electronic tools (with the exception of large-scale stationary industrial tools); electrical toys and sports and leisure equipment; medical devices (with the exception of all implanted and infected products); monitoring and control instruments; along with automatic dispensers. With regard to the individual products that fall into the corresponding equipment category, reference is made to Annex IB of the Directive.
In a further aspect, the present disclosure also relates to a method for pyrometallurgical smelting of metal-containing raw materials, waste materials and/or secondary waste materials, wherein these are fed in shredded form to a smelting unit, which comprises a smelting zone, a main reaction zone and a secondary reaction zone and are smelted in the presence of an oxidizing, reducing and/or inert gas and/or gas mixture, such that a liquid smelting phase, a liquid slag phase and a gas phase are formed, wherein the oxidizing, reducing and/or inert gas and/or gas mixture are fed in compressed form via at least one injector and are adiabatically expanded within the smelting unit and are then blown as adiabatically expanded gas and/or gas mixture into the liquid slag phase, preferably in such a manner that a cooling effect of at least 10 J/Nm3 is achieved.
The invention and the technical environment are explained in more detail below with reference to the figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly shown otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description and/or figures. In particular, it should be noted that the figures and in particular the size relationships shown are only schematic. Identical reference signs designate identical objects, such that explanations from other figures may be used as a supplement if necessary. The following are shown:
The smelting unit 1 shown here is designed in the form of a conventional bath smelting unit, which comprises a base surface 2 in the lower region along with a substantially cylindrical reactor wall 3 extending vertically from the base surface 2 and having a first conical region 4 and a second conical region 5. The smelting unit 1 comprises a smelting zone 6, a main reaction zone and a secondary reaction zone 7, 8.
The first conical region 4 of the smelting unit 1 is configured such that it comprises the smelting zone 6 along with the main reaction zone 7. The secondary reaction zone 8 extends above the main reaction zone 7.
In the first conical region 4, the shredded material M to be smelted is smelted in the presence of the reaction gas G, such that a liquid melt phase 9 and a liquid slag phase 10 are formed.
As can be seen from the illustration in
In the embodiment shown here, the reaction gas G is injected into the slag phase 10 via the injectors 11 arranged in the smelting unit 1 above the liquid slag phase or in the secondary reaction zone 8. As can be seen based on the illustration, the injectors 11 are oriented at a specific angle and are arranged above the liquid slag phase 10. For example, the angle can be in the range of 5° to 85° with respect to the horizontal H.
Each of the injectors 11 has a respective Laval nozzle 14 through which the reaction gas G can be injected into the slag phase 10 at supersonic speed. Furthermore, the reaction gas G is fed in compressed form into the smelting unit 1 via the injectors 11, which preferably each comprise a Laval nozzle 14, and is adiabatically expanded within the smelting unit 1 and then injected into the liquid slag phase 10 as adiabatically expanded reaction gas, particularly preferably in such a manner that a quantity of heat adapted to the process can be extracted in an exothermically proceeding reaction process.
On the outside, each of the injectors 11 further comprises a coaxial nozzle 15 through which a sheath gas (not shown) can be blown onto the liquid slag phase 10.
The material M to be smelted can be fed into the center of the slag phase 10 through an opening 17 of the smelting unit 1 arranged above the slag phase 10. In addition or alternatively, this can also be added to the liquid slag phase 10 via an injection lance 18 arranged in the region of the injector 11.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 215 140.7 | Dec 2020 | DE | national |
This application is a national stage application, filed under 35 U.S.C. § 371, of International Patent Application PCT/EP2021/083555, filed on Nov. 30, 2021, which claims the benefit of German Patent Application DE 10 2020 215 140.7, filed on Dec. 1, 2020.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/083555 | 11/30/2021 | WO |
