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INVENTION
Russian Federation Patent RU2151210
METHOD FOR PROCESSING alloy Dore gold
Name of the inventor: Karpuhin AI .; Stelkina I.I .; Medvedev LA .; Dementiev VE
The name of the patentee: Joint Stock Company "Irgiredmet"
Address for correspondence: 664000, Irkutsk, bul. Gagarina 38, OJSC "Irgiredmet", Patent and License Department
Starting date of the patent: 1998.11.24
The invention relates to metallurgy of precious metals, particularly the refining of gold and silver. A method of processing an alloy of gold ligature comprises granulating alloy pellets aqua regia leaching, separation cake silver chloride and precipitation of gold from solution. Thus after the leaching pulp is diluted with water to a residual concentration of acids is not more than 3 mol / l. Precipitated from a solution of sodium gold sulfite in two stages. The method allows gold precipitate without prior removal of the nitric acid solution.
DESCRIPTION OF THE INVENTION
The invention relates to metallurgy of precious metals, particularly the refining of gold and silver.
On the refining facilities, the main raw material is a pre-alloy of gold and silver alloy, which is obtained after receiving the melting of all feedstocks (except zinc rainfall) entering the plant.
An alloy of gold ligature is a carbide solution of gold and silver, which explains the difficulty of processing.
A method of processing an alloy of gold ligature, which is taken as a prototype as the most close to the claimed technical solution / 1 /.
The known method includes granulation alloy, gold leaching with aqua regia, cake filtering silver chloride, the removal of free nitric acid solution by evaporation, dissolving the salts in water and the precipitation of gold from a solution of oxalic acid or iron sulphate. After washing, filtering, drying and melting of the mass fraction of gold bullion is 99,8-99,9%.
The disadvantages of the method chosen as a prototype, are as follows:
- The inability to use oxalic acid and ferrous sulfate as the reducing of gold from solutions containing nitric acid, for the use of these reagents must be removed by evaporation of nitric acid, which is more time-consuming operation, and;
- Duration of the operation the deposition of gold using oxalic acid (over 4 hours);
- Received gold does not meet the requirements on commercial products - refined gold.
The task to be solved by the claimed invention is to provide a finished marketable products - refined gold - and a decrease in "zadalzhivaemosti" metal in the process.
This object is achieved by achieving the technical result, which consists in the fact that the gold deposition from solutions containing nitric acid, takes place without removing it.
Said technical result is achieved by that in the known method for processing the alloy pre-alloyed gold, comprising granulation alloy, leaching granules aqua regia, separating cake silver chloride and the precipitation of gold from the solution according to the invention the leach slurry is diluted with water to a residual concentration of acids is not more than 3 mol / l, and a solution of gold sodium sulfite deposited in two stages. Thus in the first stage gold is deposited on 95-98%.
The invention consists in the fact that when diluting the solution with water (to a concentration of acids is not more than 3 mol / l) occurs doosazhdenie silver present in the solution in the form of complexes AgCl 2-4 and AgCl -3 the concentration of silver in solution decreased to 5 - 10 times, and doosazhdennoe silver combined with the main part of the undissolved silver in the form of its chloride. During the deposition of gold from tsarskovodochnogo sodium sulfite occurs in two steps further purification of gold especially in the first step by precipitation makroosnovy and increase the concentration of hydrochloric acid (formed by the reaction 2HAuCl 4 + 3Na 2 SO 3 + 3H 2 O ---> 2Au + 3Na 2 SO 4 + 8HCl), which helps keep the impurities in solution. The second stage is carried out substantially complete precipitation of gold, and if the original pulp diluted with water, the amount of impurities deposited in the second step is less than the precipitation without dilution.
Comparative analysis of the proposed method with the prototype shows that the proposed method of processing an alloy of gold ligature is different from the prototype. Thus, the claimed technical solution meets the criterion of "novelty". In order to prove compliance of the claimed invention, the criterion of "inventive step" was compared with other technical solutions known from the "prior art".
The sign - gold deposition in two steps known / 2 /, but this method is not used for tsarskovodochnogo solution, and to the chloride solution, and as precipitator used sulfur oxide (SO 2), wherein the first step is precipitated only 80% of the gold, t .e. "zadalzhivaemost" gold compared with the proposed method is increased by 5-7 times.
The use of sodium sulfite to precipitate gold from tsarskovodochnyh known solutions and / 3 /, but this method does not enable to obtain a high quality commercial product ligature of gold and lead a more complete precipitation of gold from solution.
In addition, known methods are used for the other raw material, ie. E. Anodic slimes, which are relatively easily processed, as noble metals in sludge are mainly in the form of mechanical mixtures of the individual metals.
In the claimed method uses the same combination of these known features that allow you to get out of a difficult feedstock (ligature gold) fine gold with a small amount of impurities (no more than 50 g / t) and full precipitate the gold from solution. Thus, the claimed invention meets the criteria "inventive step" because the sum of its distinguishing features, namely the dilution of the pulp with water leaching and deposition of gold in the two stages of sodium sulfite helps to ensure a high-quality marketable products - refined gold - and a decrease in "zadalzhivaemosti" metal in a process that does not follow explicitly from the prior art.
Method is as follows
Granular ligature gold alloy with a mass fraction,%: Au - 80,0 - 98,0 ; Ag - 1,0-17,0 leached with aqua regia at 60 o C for 5 hours. The pulp is then diluted with water to a concentration of 3 moles of acid / liter. After separating the silver chloride from the gold-containing cake is precipitated gold solution in two stages with sodium sulfite at a temperature of 50-60 o C for 0.5-1.0 hours. A second deposition step of the first stage are the solution. Spongy gold obtained from the first and second phases are washed with a solution of hydrochloric acid and then with distilled water, then dried, melted into ingots.
Examples of the methods are presented in the table.
Example 1 (the prototype)
A portion of 20 g granules ligature gold alloy with a mass fraction of Au - 89,0%;
Ag - 10,8% leached with aqua regia at a temperature of 6 0 o C for 5 hours.
After separation of the silver chloride was evaporated cake solution for 6 hours to remove the nitric acid, then water was added to dissolve precipitated salts and gold iron sulfate. The precipitate was washed with a solution of gold (5%) hydrochloric acid and distilled water, dried and melted.
Examples 2-8 (according to the proposed method)
Hinge (weighing 20 g each) of the pellets of the same ligature gold alloy as in Example 1 was leached with aqua regia at 60 o C for 5 hours and poured calculated amount of water was determined by molar concentration of the acid by titration, and then the pulp was filtered, and from solution of gold sodium sulfite solution was precipitated in two steps. The first deposition step conducted until the residual mass of gold concentration in the solution 5.7 g / l, the degree of deposition of 95-98%.
The second step of the first stage are the solution. Mass concentration of gold in solution obezzolochennom 0.05-0.3 mg / l.
The precipitation of 99.999%.
The resulting precipitates were washed with gold in the same way as in Example 1, dried and melted.
The experimental results show:
- Optimum leaching conditions pulp dilution is to obtain a solution pH of not more than 3 mol / l. Increasing pH increases the content of impurities in the gold alloy. And at a lower pH (e.g. 2.8 mol / l) gold quality obtained is high enough, but it increases the volume of processing solution which is subsequently supplied to the purification of non-ferrous metals;
- Optimum degree of deposition of gold in the first stage is 95-98%.
With higher impurity content increases extracting a gold alloy, but at a lower gold recovery, although the quality of fine gold is high, the amount of gold is increased, resulting in the second precipitation stage, i.e. improved technology "debt" metal.
The developed method of processing acidic gold alloy ligature is proposed to use in the Kolyma Refinery.
Sources of information taken into account in the examination
JH Maslenica, L.V.Chugaev. Metallurgy of precious metals. Metallurgy. - M., 1972, p.313 - prototype.
MA Meretukov, A.M.Orlov. Metallurgy of precious metals. Foreign experience. - M .: Metallurgy. - 1991, p. 252.
RJ Metallurgy, 1984. 4G353.
CLAIM
A method of processing an alloy ligature gold comprising alloy granulation, leaching granules aqua regia, separating cake silver chloride and the precipitation of gold from the solution characterized in that after leaching, the pulp is diluted with water to a residual concentration of acids is not more than 3 mol / l, and gold from the solution is deposited sulfite sodium in two stages.
The method of claim 1, wherein the first stage gold deposited on 95 - 98%.
print version
Publication date 05.12.2006gg
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