Patent Application
20140314640
This invention claims priority to, and incorporates by reference, Kazakhstan Patent Application No. 2012/0454.1, filed Apr. 18, 2012, now issued as a Patent No. KZ 26589.
The claimed invention relates to the field of non-ferrous metallurgy and can be used for extracting beryllium from genthelvites when processing the raw minerals (e.g. ores, concentrates) by heap and vat leaching.
Modern methods of beryllium extraction from the minerals mentioned above, in particular, from ore and concentrates, all exclusively use the pyrometallurgical method at high temperature. Processing of the beryllium-containing ore can be accomplished in several ways: (a) Melting with alkalis; (b) Sintering, with sodium fluorosilicate in different variations; (c) Chlorination (using chlorine gas) with charcoal at a temperature of approximately 800° C.; (d) Roasting the concentrate at a temperature of 1400-1500° C. (US method); (e) Melting-cooling in an electric furnace at 1600-1650° C.
Disadvantages of beryllium extraction by the pyrometallurgical production method include: release of harmful toxic gases, high energy costs, and need for fire-resistant materials, all of which are not economically or environmentally beneficial.
With regard to this, there is presently a great urgency to develop new technologies for processing beryllium-containing raw materials by hydrochemical method and to search for new effective active reagents tor extracting beryllium minerals that are difficult to dissolve.
A more economical and environment-friendly process (compared to known methods) for extraction of beryllium from raw beryllium-containing minerals of the genthelvite group (i.e. danalite, genthelvite, helvite). The process employs the use of a leaching solution containing technical grade hydrochloric acid at concentrations in the range of 0.8% -8% (by weight) per liter of leaching solution. The leaching solution is placed in contact with the genthelvite material and heated at 80° C. for one (1) hour, allowing for extraction of beryllium from the beryllium-containing minerals.
Replacement of the high temperature method for extracting beryllium from beryllium-containing raw materials, presented mainly in the form of mineral groups of the genthelvite group (danalite, genthelvite, helvite), then chrysoberyl (Be(AlO2)2), euclase (Al2Be2(Si2O8)(OH)2), bertrandite (Be4(Si2O8)(OH)2), then bavenite (Ca4(BeAl2Si9)25)(OH)2, phenakite (Be2Si6O4), and lastly the beryllium concentrates using the cheaper hydrochemical method with effective solvents is very urgent.
Since there is interest abroad in genthelvites as promising sources of raw material, they form the basis of genthelvite concentrates.
The basis of this invention is the disclosure of a novel method for extracting beryllium from danalite (Fe8(BeSiO4)6S2), helvite (Mg8(BeSiO4)6S2), and genthelvite (Zn8(BeSiO4)6S2), thus expanding the range of raw minerals used for processing and providing more economical production and improved environmental impact via use of an effective active reagent at low temperatures by hydrochemical method. This method has no analogs in worldwide application.
The main objective of the invention is beryllium extraction from the genthelvite group of minerals (ores, concentrates), providing economical, environment-friendly production via use of the cheap hydrochemical method.
The technical result is achieved by leaching beryllium from minerals of the genthelvite group (danalite, helvite, and genthelvite) by immersing monomineral samples of ore or concentrates in the leaching solution. Such solution contains technical hydrochloric acid in quantities of 1.2% to 8% by weight (the ratio of HCl:H2O is 1:3) per 200 mL of solution. The samples are then boiled in solution at a temperature of 80° C. for 1 hour (i.e. leaching beryllium from the given product occurs in a very small period of time). The role of hydrochloric acid is two-fold: to ensure that it inhibits hydrolysis, and also to ensure that stable bonding of BeCl2 occurs.
Experimental studies have been performed on the dissolution in hydrochloric acid of monomineral samples of beryllium-containing minerals. The mineral purity is as follows: helvite—99.1; genthelvite—99.0; chrysoberyl—98.4; bertrandite—98.5; phenakite—98.3; beryl—99.0.
Verification of the data was conducted on monomineral samples of danalite, helvite, and genthelvite with concentrations of hydrochloric acid from 0.8 to 8% (by weight). These experiments showed that when the concentration of hydrochloric acid is 0.8%, 31% of beryllium is extracted from helvite, 22% from genthelvite, and 25% from danalite (Table 1). Only increasing the HCl concentration up to 5% and higher leads to complete dissolution of beryllium.
The preliminary experimental results on the behavior of helvite, genthelvite, and danalite relative to the concentration of hydrochloric acid yielded information about the primary factors influencing the process being studied: concentration of hydrochloric acid, mixing duration, and temperature.
In order to find the most effective set of optimal conditions for complete dissolution of helvite, genthelvite, and danalite, an orthogonal design for an experiment of the 2nd order with star shoulder
α±1.215.
The ratio of components, including concentrations of potassium chlorate and hydrochloric acid used during leaching, was chosen experimentally using the multifactor orthogonal experiment design. Deviations from the design lead to decreases in the degree of beryllium extraction from beryllium-containing raw materials.
To confirm the technical result of the claimed method, there are several examples of implementation: experiments were performed in a 500 mL leaching solution corresponding to the S:L ratio of 1:5. The degree of extraction was measured by existing methods.
Pour 500 mL of technical hydrochloric acid with concentration of 8% (by weight) onto 250 g of monomineral helvite or genthelvite. Components were heated to 80° C. for 1 hour. Results of the experiment are shown in Table 2.
Test was conducted similarly to Example 1, except with a technical hydrochloric acid concentration of 6% (by weight). Results are shown in Table 2.
Test was conducted similarly to Examples 1-2, except with a technical hydrochloric acid concentration of 2.4% (by weight). Results are shown in Table 2.
Test was conducted similarly to Examples 1-3, except with a technical hydrochloric acid concentration of 1.2% (by weight). Results are shown in Table 2.
On the basis of the experimental data (Table 2), the following most effective sets of optimal conditions for extracting beryllium from helvite and genthelvite were chosen: 500 mL of 5-8% solution of hydrochloric acid heated for 60 minutes. Under these conditions, the degrees of beryllium extraction from helvite and genthelvite were determined, and they were 100%.
From Tables 1 and 2 it follows that the claimed method allows carrying out the process in a hydrochloric acid medium (in concentrations ranging from 5% and higher) heated to a temperature of 80° C. for 1 hour. Beryllium extraction ranges from 99% to 100%. The claimed method for leaching beryllium from the group of genthelvites was also tested by the addition of certain amounts of monomineral samples of helvite or genthelvite to ore with original content of 0.028%. Leaching method: separately add 500 mg of monomineral helvite or genthelvite to a batch of 0.25 kg of ore. Then, pour 500 mL of hydrochloric acid of various concentrations into the mixture and heat on a stove for 1 hour. The mixture was cooled and then filtered through a filter. Beryllium content was determined by spectrophotometric method with beryllium II. Results are shown in Table 3, below.
Since danalite, helvite, and genthelvite have almost identical chemical activity, tests were only conducted with helvite. Verification of the degree of beryllium extraction from danalite and genthelvite showed it is also 100% for the optimum conditions for helvite dissolution discovered.
A new method for extracting beryllium from the genthelvite group of minerals in the context of processing mineral raw materials (ore, concentrate) may be recommended as the basis for innovative technologies for beryllium extraction from genthelvite concentrates and ores.
It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed in the scope of the claims.
