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INVENTION
Russian Federation Patent RU2081193
METHOD OF EXTRACTION PERCOLATION silver and gold out of ores and dumps
Name of the inventor: Potashnikov Yuriy Moiseevich; Lutsyk Vladimir; Chursanov Yuri V.
The name of the patentee: Potashnikov Yuriy Moiseevich; Lutsyk Vladimir; Chursanov Yuri V.
Address for correspondence:
Starting date of the patent: 1994.05.31
Usage: As for ways to extract silver and gold from the sulfide, oxide ores, concentrates and tailings materials. The inventive treatment of the starting materials are leaching water solution containing ferric ions and a ferric thiocyanate and silver and the gold recovered by passing the solution after each leaching cycle through the layer of scrap iron or aluminum shavings, and the return of this solution after adjustment for a new cycle.
DESCRIPTION OF THE INVENTION
The invention relates to a hydrometallurgical precious metal, in particular, to methods of extracting silver and gold from sulphide, oxide ores, concentrates, and tailings materials.
Known process for leaching gold from poor crushed ore with an alkali metal cyanide and an oxidant, which is used as the sparingly soluble divalent metal peroxide. As used cyanide NaCN solution with a concentration of 0.005-0.02 mole / dm3 at pH = 9-13; CaO 2 as oxidant at a rate of 1-20 parts per 1,000 parts of dried raw material. The peroxide was injected in the formation of heaps in an aqueous slurry [1]
The disadvantage of this method is the use of highly toxic cyanide, which is especially dangerous for heap leaching, and the need for expensive and divalent metal peroxide.
The closest in technical essence is a method for the hydrometallurgical recovery of precious metals, in which poor ore and other products containing An, Ag, treated with thiourea in an acidic aqueous medium at a concentration of thiourea 0,01-7,0 g / dm 3 in the presence of ferrous sulfate ( III) in acid solution (2).
The disadvantage of this method is low stability due thiourea oxidation by atmospheric oxygen and iron ions (III), the complexity of the process because of the need sorption concentrating and separating the dissolved gold and silver and the absence of closed loop solutions used.
The object of the invention is to provide a technology that provides the ability to extract silver and gold from the ore and waste dumps with a low content of these metals, in which other methods can be economically unjustified, multi-use leaching solution regeneration difficulty leach solution at the same time provide a level of environmental safety of a higher, technology than cyanide, and no lower than with thiourea.
The technical result is achieved by a high degree of extraction of gold and silver with low reagent consumption due to repeated use of the solution in a closed cycle. Improving the environmental safety associated with the use of low-toxic reagents and small volume solutions used by the closed cycle of treatment.
A percolation method of extraction of gold and silver from ores and tailings containing lead, zinc, iron, calcium, magnesium, silicon and sulfur, which consists in that irrigate the particulate material with a solution containing 10-50 g / dm3 thiocyanate ions 0 , 1-5,0 g / dm 3 of ferric iron at a pH of 0.5-7.0, conducting leaching process. A predetermined concentration of the ferric sulfate to provide the addition of ferric nitrate solution, or (III) or by dissolving it out of leachable material. Isolation of lead silver and gold leaching solution after passing through the layer of scrap iron or aluminum shavings. After capture of gold and silver from the solution and adjust the composition solution is returned for re-irrigation. The described cycle is repeated many times.
Leaching is carried out at ambient temperature (0.1 to 50 o C) from 2 weeks to achieve the maximum degree of leaching. Each irrigation cycle depending on the thickness of the material layer extends from one to several days. In the solution passes the silver and gold. After each cycle, the solution flows through the bed of scrap iron or aluminum shavings. The solution was then, if necessary by adding reinforcing thiocyanate and sulfuric acid is aerated for oxidation of iron (II) to iron (III) and fed to the next leaching cycle.
The degree of extraction of silver is 82.1% gold and 69.4% for the 15 -day period processing leachable material.
The proposed method makes it possible to extract gold and silver from the material processing by other methods is not economically justified, but also provides a higher level of environmental safety than previously known.
Carrying out the leaching process in a strong acid medium (pH <0,5) results in the oxidation of thiocyanate, pH environment above 7.0 leads to a decrease of the oxidizing ability of the solution used.
The concentration of iron ion (III) 0,5 g / dm 3 is sufficient for the flow of the leaching process at a significant rate, while its excess of 5 g / dm 3 slows down gold into solution.
When the content of thiocyanate ions in the solution is less than 10 g / dm 3 of silver and gold is leached practically and maintain their concentration at a level greater than 50 g / dm 3 due to unreasonable costs without increasing the efficiency of the leaching material by spraying.
Temperature limits correspond to the extraction conditions geotechnological methods without the use of heating at temperatures below freezing may freeze the solution, and the limit of 50 o C is practically not exceeded under natural warming of the upper layers of leached mass sunlight.
The inventive parameters are optimal for percolation extraction of silver and gold from the ore and waste dumps and ensure high process efficiency at maximum ecological safety.
As seen from the description and the drawing method, in comparison with the prior art composition of the leach solution and its use in a closed loop are new.
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The advantages of this method will become apparent from the flowsheet of FIG. 1 with 1 pressurized container, percolator 2, 3 tray (cementing), 4 reception capacity, fitted with airlift.
Example
As the material containing the precious metals, tailings sample is taken containing silver 125 g / t gold, 78 g / t of lead zinc 0.3% 0.5% iron, 4.2% cobalt 1.1% 1.1% magnesium sulfur 0,4% SiO 2 60.6% particle size of 2 mm.
The percolator 2 of 1 dm 3 was charged 1.5 kg leachable material and moistened with water prior to leaching. From the pressure tank 1 for the material fell into irrigation percolator 0.2 dm3 leach solution (NCS - 40 g / dm 3, Fe 3+ 1 g / dm 3, pH = 3). For NCS - ions used potassium thiocyanate, and Fe 3+ - iron sulfate (III). One leaching cycle was 10 hours (irrigation density of 0.3 m 3 / m d.). The solution after the percolator flowed through cementing three tray filled with 20 grams of the fired and washed with sulfuric acid (1: 3) iron filings, then fell into a receptacle 4, where periodically includes AeroLift solution was supplied to the tank 1 where carried out adjustments of the leach solution.
All experiments were performed at 15-day duration of the leach. After shaving experience iron dissolved in nitric acid.
From the solution after filtration of precipitated silver chloride from the precipitate and the filter cake recovered gold.
As seen from tablitsyizvlechenie silver and gold within the parameters specified by the claims (experiments 1, 2 and 3) provide a degree of recovery of silver is not less than 41.6% gold and 26.8. Terms of the lower limits specified parameters (experiment 4) and upper (experiment 5) do not provide sufficient extraction of silver and gold.
The simplicity and efficiency of the proposed method allows to widely use it to extract gold and silver, where other methods are unsuitable:
1) because of the low concentrations of precious metals in the starting compounds;
2) requires a process of environmental safety.
The proposed method allows to extract silver with the degree of extraction - 82.1 and 69.4% of the gold in just 15 -day treatment period leachable material.
CLAIM
A percolation method of extraction of gold and silver from ores and tailings comprising an aqueous leaching solution containing thiocyanate ions and trivalent iron, characterized in that the leaching is carried out in the irrigation mode, 0,1-50 o C at pH 0.5-7.0 Content thiocyanate ions in a solution of 10-50 g / dm 3 and ferric 0.1-5.0 g / dm 3 with separation of gold and silver from the resulting solution by passing the solution through a bed of iron or scrap aluminum chips correcting solution followed by pH value, the content of thiocyanate and ferric ions and returning the leaching solution obtained.
print version
Publication date 05.12.2006gg
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