RU2210608C2 - Method of extraction of noble metals from sulfide materials - Google Patents

Abstract

FIELD: metallurgy of noble metals; gold extracting plants reworking sulfide raw materials. SUBSTANCE: proposed method includes grinding of materials, preparation of aqueous pulp, bubbling air through pulp in presence of Tiobacillus Ferroosidance microorganisms, use of waste aqueous phase in circulation, sorption cyanide leaching of gold and silver from solid phase followed by separation of ion-exchange resin containing noble metals, desorption of noble metals and electrolytic production of gold and silver. Prior to sorption cyanide leaching, enriched concentrate of noble metals is separated from solid phase by gravitational concentration; tailings of gravitational concentration are subjected to sorption cyanide leaching. EFFECT: enhanced efficiency.

Description

 The invention relates to the field of metallurgy of precious metals and can be used in gold mining enterprises that process sulfide raw materials.

 A known method of extracting gold and silver from refractory gold-arsenic concentrates, which is also the closest analogue of the invention ("Conduct semi-industrial testing of the technology of bacterial opening and sorption cyanide concentrates of the Nezhdaninsky GOK". Report of the institutes TsNIGRI, Gidrotsvetmeta, Irgiredmet, MISiS and Institute of Microbiology of the USSR Academy of Sciences Moscow - Tula - Irkutsk - Novosibirsk, 1987 UDC 622.7: 622.342.1, State registration number 0187.0041496).

According to him:
1. A mixture of gravity and flotation concentrates of the Nezhdaninsky GOK is subjected to processing.

 2. The size of the material used is 85-95% of the class -0.044 mm.

 3. Concentrates are mixed with circulating water of the technological scheme to T: W = 1: 5.

4. Sulfides of the starting material are oxidized by bubbling air through a mixture of concentrates and recycled water in four series-connected reactors operating continuously at a temperature of 28-33 ^o C and a pH of 1.7-2.1.

5. The oxidation is carried out in the presence of microorganisms Tiobacillus Ferrooxidance, playing the role of a catalyst (content up to 7.5 g / DM ³ ); the culture of microorganisms is introduced into the technological scheme when the technology is launched, then under the conditions of bacterial leaching (BV) it self-reproduces.

 6. The required duration of bacterial oxidation of sulfides is 80-100 hours. During this period, the oxidation state of arsenopyrite reaches 96-97% and pyrite 78-79%.

7. KV BK is isolated from the pulp by thickening and filtration, mixed with water to T: L = 1: 1, the pulp is neutralized with lime to pH 11.5-12, subjected to special electrochemical treatment and, after addition of sodium cyanide, to sorption cyanidation using AM resin -26 at T: W = 1: 2, sodium cyanide concentration of 1 g / dm ³ , lime concentration of 0.3 g / dm ³ , resin consumption of 10-20% to solid and duration of 10-12 hours

8. Gold and silver from the saturated sorbent after preliminary treatment of the latter are desorbed in the form of thiocarbamide complexes, the resulting thiocarbamide solution is subjected to electrolysis with the extraction of gold and silver on the cathode in the form of metals at a current density of 40 A / m ² and a solution productivity of 1 m ³ per 1 m ² cathode surface per hour.

 9. The total extraction of gold from concentrates according to the described technological scheme is 92% and silver 55.1%.

 10. Arsenic is removed from the aqueous phase after separation of BV cake in the form of calcium arsenate with lime, and the aqueous phase after separation of this precipitate (stored production waste) is fed to the head of the process for preparing the initial BV pulp.

 11. The residue after cyanidation of gold and silver is subjected to special treatment with elemental chlorine and iron compounds and stored.

 12. Resin AM-26 after desorption of gold and silver and washing again served on sorption cyanide.

 A disadvantage of the known method for extracting gold and silver from sulfide materials is the relatively low degree of extraction.

 The basis of the invention is the technical task of increasing the completeness of the extraction of gold and silver from refractory sulfide materials.

 To solve this problem, in a known method for the extraction of precious metals from refractory sulfide materials, including grinding these materials, preparing their aqueous pulp, bubbling air through the pulp in the presence of reproducible microorganisms Tiobacillus Ferrooxidance, using the spent aqueous phase in circulation, sorption cyanide leaching of gold and silver from solid phase, followed by separation of the noble metal-containing ion-exchange resin, desorption of the noble metals and electrolytic production of allicheskih gold and silver, from the solid phase before sorption cyanide leaching previously isolated gravitational enrichment rich concentrate of precious metals, followed by separate processing it according to known techniques.

 In refractory sulfide raw materials, gold and silver are in a finely dispersed state, enter the structure of grains of metal sulfides, and can be recovered only after the destruction of this structure and the release of fine particles of gold and silver. However, even in this case, the cyanide extraction of precious metals from degraded sulfide materials continues to be a problem, since the noble metals in these materials are often accompanied by carbonaceous materials capable of sorbing cyanide complexes of gold and silver. The process of BV sulfides is associated with the appearance in the leach pulps of waste products and the breakdown of microorganisms Tiobacillus Ferrooxidance. These compounds (amines, carboxylic acids, phospholipids, etc.) cover the surface of carbon particles, prevent sorption of noble metal cyanide complexes on them, and make it possible to extract gold and silver from bacterial pulps using cyanidation.

 In the known method, sorption cyanidation of noble metals from bacterial pulps is carried out by supplying the solid phase of BV without prior treatment to the cyanidation operation. In the present invention, a rich concentrate of precious metals is isolated from this phase by a pre-gravity method. Gold and silver contained in this concentrate are thereby excluded from participation in the process of cyanide sorption leaching; only tails of gravity pass through this process, in which gold and silver are in a finely dispersed state and are easier to interact with sodium cyanide.

 Gravity-rich concentrate rich in precious metals, containing more than 7 kg / t of the sum of gold and silver, can be processed according to well-known technological schemes.

 The high content of gold and silver in a rich gravitational concentrate is due to the aggregation of fine gold and silver particles of sulfide source materials into large ones in the pulp of BV under the influence of vital products and decomposition of microorganisms Tiobacillus Ferrooxidance, as well as the large difference between the specific gravities of large particles of noble metals and finely dispersed glandular particles of pulp BV.

 The separation of a rich concentrate of precious metals from the solid phase of the biologically active substances and the processing of it and gravity tails according to separate technological schemes leads to an increase in the degree of extraction of gold and silver from refractory sulfide materials (by the example of pyrite concentrate - by 5.5 and 13.8%, respectively).

Example 1
At a plant similar to that described in the prototype, 100 kg of pyrite concentrate is processed, containing, wt.%:
Fe - 33.6
S - 38.7
Au - 13 g / t
Ag - 93 g / t
As a result of processing according to the technological scheme of the prototype, 603 mg of the cathode deposit containing 1,200 mg of gold (92.3% recovery) and 5,403 mg of silver (58.1% recovery) are obtained.

Example 2
100 kg of the pyrite concentrate of the same composition are processed as in Example 1. Processing is carried out on the same installation as in Example 1, but the resulting pulp is subjected to gravitational enrichment on an Itomak centrifugal apparatus. The output of the gravity concentrate of the centrifugal apparatus is 0.55 kg, including:
Au - 0.849 g (1.54 kg / t)
Ag - 3.236 g (5.88 kg / t)
The extraction into this concentrate from the initial load with pyrite concentrate is:
Au - 65.3%
Ag - 34.8%
Gravity dressing tailings are processed according to the technological scheme of the prototype. As a result of processing, 3.869 g of cathode deposit are obtained, including:
Au - 0.423 g (32.5% of the initial load)
Ag - 3.446 g (37.1% of the initial charge)
The total extraction of gold and silver in the concentrate apparatus of the company "Itomak" and in the cathode deposit is:
Au - 97.8%
Ag - 71.9%
As can be seen from the above examples, the proposed method allows to increase the extraction of gold and silver from refractory sulfide materials; recovery in the case of tested pyrite concentrate increases from 92.3 to 97.8% and from 58.1 to 71.9%, respectively.

Claims (1)

 A method of extracting precious metals from refractory sulfide materials, including grinding these materials, preparing their aqueous pulp, bubbling air through the pulp in the presence of reproducible microorganisms Tiobacillus Ferrooxidance, using the spent aqueous phase in circulation, sorption cyanide leaching of gold and silver from the solid phase, followed by separation containing noble metals of ion-exchange resin, desorption of noble metals and electrolytic production of metallic gold and silver, distinguish This is due to the fact that a rich concentrate of precious metals is preliminarily separated from the solid phase before sorption cyanide leaching by gravity enrichment, followed by its separate processing according to known technologies, and tails of gravity enrichment are subjected to sorption cyanide leaching.