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INVENTION
Russian Federation Patent RU2095478
METHOD OF EXTRACTION OF GOLD FROM WASTE
Name of the inventor: Bogdanovskaya VA .; Tarasevich MR .; Krylov IA .; Krasnoshtanova AA .; Manakov MN
The name of the patentee: Russian Chemical-Technological University Mendeleev
Address for correspondence:
Starting date of the patent: 1996.04.25
The invention relates to methods of electrochemical dissolution of gold in the process of removing it from waste galvanic production and gold ore in the presence of complexing protein nature. The essence: in the way of raw materials processing is performed at the anodic polarization of gold-bearing raw materials (waste electroplating, gold ore and waste) at the potentials of 1.2-1.4 V (n.v.e.) in the presence of complexing protein nature - an enzymatic hydrolyzate of proteins biomass of microorganisms having a degree of hydrolysis of not less than 0.65 at a content of amine nitrogen in a solution of 0.02-0.04 g / l and 0.1 M sodium chloride solution (pH 4-6). The effectiveness of the method of gold dissolution is achieved through the use of cheaper available complexing agent.
DESCRIPTION OF THE INVENTION
The invention relates to methods of electrochemical dissolution of gold in the process of removing it from waste galvanic production and gold ore in the presence of complexing protein nature.
Traditional methods of dissolution of gold is based on the use of cyanide leaching method. A significant disadvantage of high toxicity is used cyanogen complexing compounds causing environmental pollution and requires the creation of complex wastewater treatment systems [1]
The closest to the technological essence and attainable effect to the proposed method is an electrochemical method of gold dissolution [2] includes an anode polarization of gold-bearing raw material in the electrode rotation rate of 2.5 × 10 -3 / s in buffered solutions of amino acids in a concentration of 10 -2 -10 - 3 mmol / l.
As the buffer used potassium monophosphate. As the amino acids can be used histidine, cysteine or dipeptide glycyl-glycine.
The disadvantage of this method is the low efficiency of the process due to the use of highly purified preparations of individual amino acids and low rates of gold dissolution.
The object of the invention is to provide a more effective method of gold dissolution due to the use of cheaper and affordable complexing.
The problem is solved in that in the method of treating gold ores it serves to conduct during anodic polarization at a potential of 1.2-1.4 V (n.v.e.) in the presence of a complexing agent, which is used as an enzymatic hydrolyzate of proteins biomass Industrial Microorganisms having a degree of hydrolysis of not less than 0.65 at the amine nitrogen content of 0.02-0.04 g / l in 0.1 M sodium chloride. A hydrolyzate prepared from microbial and biological materials, the latter being preferred since it allows to obtain standard compositions and contains a large number of proteins, based on air-dry substance.
The hydrolyzate obtained from the microbial cells by first removing ribonucleotides in optimum conditions, proteins and then using aqueous extractant containing mineral alkali, acid or technical enzymes. The resulting extractant is separated from the solid phase by separation. The resulting protein solution was freed from impurities by precipitation of protein carbohydrate components at the isoelectric point at pH 4,2-4,7 and is then hydrolyzed with an enzyme preparation containing protease and peptidase. The hydrolysis is carried out until the degree of hydrolysis ratio of amino nitrogen to total at least 0.65. Obtained from fermentative doochischayut macromolecular peptides and carbohydrate impurities by ion exchange by adsorption of amino acids and lower peptides on cation exchanger followed by elution with 3.1% ammonia. The resulting eluate was neutralized with concentrated hydrochloric acid, evaporated, and spray dried. Finished product has the following characteristics (a DIA): peptide 20; 60 amino acids; 0.1 carbohydrates; chlorides 2,0; ammonia 1.0; 16.9 inorganic impurities.
Using the preparation obtained, the processing is carried gold objects in an electrochemical cell (electrolyzer) in a 150 ml solution with magnetic stirring. The electrolyte used 0.1M sodium chloride solution with pH 4-6, in which the hydrolyzate is added to achieve the desired amine nitrogen content of 0.02-0.04 g / liter. The treatment is performed by maintaining the electrode (gold-bearing material) a potential of 1.2-1.4 V (n. VE). Electrolysis was carried out for 30-60 min. As a result, the process speed is increased as compared with the known method and 1.5-2.0 times using a simpler and cheaper complexing agent.
example 1
The cell volume of 150 ml was poured 100 ml of sodium chloride solution with pH 6,0 and the hydrolyzate is added to the amine nitrogen content of 0.02 g / l.
Use hydrolyzate having a degree of hydrolysis of 0.65.
The solution is immersed the gold plate with a geometrical surface of 2 cm 2 and is maintained at a potential of 1.2 V it. The solution was stirred with a magnetic stirrer. Electrolysis was conducted for 30 minutes.
The amount of gold, transformed into a solution of 600 mg / l · cm 2.
Examples 2 and 3
Electrolysis was carried out as in Example 1 at a concentration of amino nitrogen 0.03 and 0.04 g / l.
The amount of gold which has passed into solution, is respectively 330 and 340 mg / l · cm 2.
example 4
Electrolysis was carried out as in Example 1, with the amine nitrogen content of 0.02 g / l.
The amount of gold which has passed into solution in this case was 120 mg / l · cm 2.
example 5
Electrolysis was carried out as in Example 1, with the amine nitrogen concentration of 0.03 g / l.
Use hydrolyzate having a degree of hydrolysis of 0.52.
The amount of gold was passed into a solution of 150 mg / l · cm 2.
As seen from the data obtained at amine nitrogen contents of below 0.02 g / l of gold dissolution rate decreases. Increasing the amino nitrogen concentrations above 0.04 g / l leads to a significant increase in process efficiency. Thus, the object of the invention is achieved when the concentration of the amine nitrogen of 0.02-0.04 g / liter.
Comparing the proposed method and the prototype is shown in Table.
Compared with the prior art method has the following advantages:
1) increases the rate of dissolution of gold;
2) use a cheaper drug hydrolyzate compared to the amino acid;
3) the presence of a less aggressive environment, pH 4.6 solution (sodium chloride).
CLAIM
A method of extracting gold from the wastes comprising electrochemical dissolution of gold in anodic polarization at a potential starting material in 1.2-1.4 (N.V.E.) in the presence of a complexing protein nature, characterized in that the complexing agent is used as an enzymatic protein hydrolyzate substances from microbial biomass with a degree of hydrolysis of not less than 0.65 at the amine nitrogen content of 0.02-0.04 g / l of sodium chloride solution with concentration of 0.1M at pH 4.6 environment.
print version
Publication date 05.12.2006gg
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