The method of extracting gold from solutions


(57) Abstract:

Use: for the extraction of gold from gold-bearing solution by sorption. Entity: recovery of gold from solutions carried out by sorption using as a sorbent of hydrated gas II patterns, with higher sorption capacity. It receives sufficient conditions for hydrate formation in the intensive mixing of fresh water with gas. Improved efficiency of extraction. 1 table, 1 Il.

The invention relates to the physical chemistry of solutions and can find application in mineral processing, specifically for the recovery of precious metals from enriched concentrates, as well as for the extraction of gold from sea water and other solutions.

The known method, which is widely used and implemented on the technological cycles of Ziph (1). This technology involves the leaching of the concentrate, washing gold and cyanide extraction of gold adsorption column, pre-saturated resin AM 25. However, because of the difficulty of manufacture of sorbent resins, its sorption capacity is limited. A relatively small capacity of the sorbent undergoes further ominaisuus negative impact on the development process of sorption.

There is also known a method of extracting gold from solutions consisting in the adsorption of gold on polyamine (2). This method is complicated by the observance of secondary and tertiary nitrogen atoms in the structural sorbent of polyethylenimine, which determine the interval of measuring the acidity of a solution. Sorption conditions at pH 5-1 requires additional energy costs. Synthesis of nitrogen-containing hetero-chain sorbents on the basis of Iminov and guanidino different basicity requires the consumption of expensive chemical reagents, holding a thin chemical reactions with directional properties of the obtained substances and parameters of sorption complicates the technological process.

The invention consists in the fact that the proposed method comprising processing the original gold-bearing solution sorbent, characterized in that before the sorption pH of the initial solution is brought to a value of 7.6, and sorption is carried out at 274 275 K, a pressure of 0.2 MPa using as adsorbent crystalline received by the fresh water connection gas gidratoobrazovaniya, size 0,22 0,4 mm Solid crystalline previously used for technological purposes for fresh water, the dehydration of gases and of oil for storage gasometric fossil, namely, for the recovery of gold from solutions were not used. Thus, the proposed solution meets the criterion of "novelty". In comparison with the known technical solutions in the proposed method the new properties are:

use as a sorbent cheap molecular compounds from local material on the basis of water (hydrated), distinguish the ease of synthesis and dissociation after the process of adsorption for water, gas and gold, which simplifies further fine-tuning of the known methods;

improving the efficiency of gold recovery due to higher sorption capacity and specific surface area of the proposed hydrated, and also due to the fact that the crystalline not absorb water, its sorption capacity is stable. Thus, the claimed method meets the criterion of "inventive step".

The essence of the method is illustrated on the drawing, which shows a General flow chart of extraction of gold from solution. The crystalline get under intensive mixing of fresh water and gas under conditions sufficient for their education. Gases and liquids, in which the sizes of the molecules d>0,66 nm can not form hydrates due to steric conditions. In the event that apolnet two large and six small cavities KC-1. If gases gidratoobrazovaniya with the size of the molecules 0,501<d>is 0.59 nm (COS, (CH2)3and so on) fill only two large cavity hydrates patterns KC-1. Large molecule gases-gidratoobrazovaniya 0,59<d<0,66 nm (propane, isobutane, and others ) form a crystalline structure two (KC-2) and fill only eight large cavities hydrate. This sixteen small cavities hydrates of this structure are filled with gases with smaller molecules, i.e., less of 0.48 nm (methane, hydrogen sulfide, and others).

The obtained crystals of the hydrate is cooled below 253 K for 8 to 10 h, after which they are crushed, sieved and select the faction 0,22 0,4 mm of the Crystalline fraction 1 fill pre-thermostated column 4 pressure gauge 5. The input column, fitted with a valve for regulating flow 6, connect under pressure, at which the crystalline sustainable, in the processing system for the extraction of gold from solution and thermostatic at a temperature of 274 275 K, a pressure of 0.2 MPa. Demolition of crystalline prevents safety nets 7 in the upper and lower parts of the column. To maintain a positive pressure column is provided with a check valve 8. The flow of filtrate is measured rhodometra the good ions. In crystals of gas hydrates sorption is subjected only neutral atoms, these crystals sustainability are in a neutral medium at a pH of 7.6. Therefore, the acidic solution timesaving complex is neutralized with caustic soda solution. While gold ions are restored to the neutral atom according to the scheme:

< / BR>
Neutral gold atoms form in the liquid medium of the colloid-dispersed system, cleanse it from the sludge and thermostatic at 274 275 K.

Molecular compounds gas with water to form a second crystal structure of the hydrate with the ideal formula 8M1x 16M2x 136 H2O, where M1and M2respectively the large and small cavities. Gas molecules fill only eight large cavities, sixteen small cavities remain free. When passing the solution through the hydrated sorbent gold atoms gradually accumulate in small cavities of the crystal structure to form a face-centered cubic structure of the fourteen atoms.

Lattice parameters, particle size and degree of filling of small cavities hydrate in the table.

In these tables, the degree of filling of cavities 1,0 characterizes the maximum 100%resultsstart small cavities. Each cavity may include one face-centered cubic structure of 14 gold atoms. Thus, 136 g-mol (2448 g) of water when full, cavities can absorb 224 g-atom (44 130 g) of gold. From the data, the maximum capacity of the sorbent, it follows that if one hundred free of cavities in the crystal structure of the sorbent is at least one cavity is filled recentrifuging cubic structure of gold, 2.5 kg of water can absorb 300 500 grams of gold. The dimensions of the structural units of iron, its compounds and other metals do not allow absorb in the small cavities of molecular compounds.

The degree of extraction of gold from solution is increased by the repetition of cycles of sorption and increase the degree of filling of the cavities of molecular structures.

Example. In the pressure vessel to control the temperature and pressure is placed 100 ml of fresh water and thermostatized at 275 K. At this temperature in the vessel is pressurized to 0.5 MPa gas. In these conditions of intense mixing system produces crystal structure of KC-2. Username crystals at subzero temperatures below 253 To fill the sorption column with a diameter of 5 mm, height 150 mm In order to create an ISI of 0.2 MT and at a pH of 7.6 is set solution flow rate 2 l/h The test was subjected to 15 grams of gold concentrate (primary bulk concentrate), the gold content in it to 17.7 g/T. After leaching in the original tiomochevina solution (1 l) contained 0,266 mg of gold, 27 g of oxides and salts of iron (magnetites). The original solution is pre-processed with alkali solution to pH of 7.6. At a temperature of 275 K, the addition of 0.2 MPa solution is passed through a sorbent for 30 min (flow rate 2 l/h). After sorption in eluent the gold content is of 0.066 mg, the content of oxides and salts of iron and 26.8 g Sorbent (hydrate) decompose and it is determined by the sorbed amount of gold (0.2 mg), the percentage of extraction 75,2, the presence of oxides and salts of iron, a small amount (about 0.2 mg). A face-centered structure of iron oxide have a size 0,839 nm that cannot fit in the available cavity hydrates (of 0.48 nm).

The method of extracting gold from solutions, including sorption, characterized in that before the sorption pH of the initial solution is brought to a value equal to 7.6, and sorption is carried out at 274 275 K, 0.2 MPa using as adsorbent crystalline received by the fresh water connection gas gidratoobrazovaniya, size 0,22 0,4 mm


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