RU2557024C2 - Method for heap leaching of gold from ores - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to a technique of heap leaching of precious metals, for example gold, from ores, and can be used at development of deposits of refractory ores. A method for heap leaching of gold from ores involves ore crushing, formation of piles from crushed ore, leaching of gold by supplying a solution of a reagent to the pile till reduction of content of gold in productive solutions below a process limit, drilling of wells, arrangement of explosives in them, blast firing, additional leaching of mineral mass, collection of productive solutions with further extraction from productive solutions of gold. At well drilling, testing of the mineral mass is performed, as per the results of which outlines of colmatation zones with increased content of slurry and clay fractions are defined; concentrated alkali-cyanide leaching solutions are pumped under pressure to those zones through wells, thus performing diffusion leaching of gold by means of them. After a pause is held, explosive charges placed into ampoules filled with water are arranged in well parts located within the colmatation zones. Blasting of charges is performed, thus loosening the material with simultaneous blasting and injection treatment with a water-and-gas mixture formed at blasting of charges; after that, additional leaching of mineral mass is performed by sprinkling the whole pile with a weak alkali-cyanide solution.

EFFECT: improving leaching efficiency.

1 ex

Description

The invention relates to the technology of heap leaching of precious metals, such as gold, from ores and can be used in the development of deposits of refractory ores.

A known method of heap leaching of gold and silver from ores with an alkaline or acid solution containing complexing agents: alkali metal cyanides, chlorides, sodium hypochlorite, etc. (see Heap and underground metal leaching M .: Nedra, 2007, v. 1).

The known method of heap leaching is characterized by a low recovery of valuable components due to a decrease in the permeability of the mineral mass for leaching solutions during the gradual filling of the stack free space with clay mineral particles and sludges, as well as due to the reprecipitation of complex gold and silver anions formed upon leaching on them.

Closest to the claimed is a leaching method, including crushing ore, forming stacks from crushed ore, leaching of gold by feeding a reagent solution into the stack until the gold content in the productive solutions falls below the technological limit, drilling wells, placing explosives (BB) in them, blasting charges, pre-leaching of the mineral mass, collection of productive solutions, followed by extraction of gold from productive solutions (see AS USSR No. 1168701, ЕВВ 43/28, publ. 23.07.1985).

The disadvantage of this method is the low extraction of gold and its accompanying silver from the upper zone of the stored mineral mass, due to its low permeability for working solutions due to colmatization with fine particles and clay minerals, as well as the destruction of complexing agents by hot explosive gases.

The technical result of the proposed method is to increase the leaching efficiency by increasing the permeability of the entire volume of mineral mass for working solutions, the absence of degradation of gold complexing agents due to the exclusion of their direct contact with hot explosive gases, and the reduction of gold losses due to its reprecipitation on clay and sludge minerals.

The result is achieved in that a method of heap leaching of gold from ores, including crushing ore, forming stacks from crushed ore, leaching of gold by supplying a reagent solution to the stack until the gold content in the productive solutions falls below the technological limit, drilling wells, placing explosives in them, blasting charges, additionally leaching the mineral mass, collecting productive solutions, followed by extraction of gold from productive solutions, is different in that it is carried out while drilling a well mineral mass testing, according to the results of which the contamination zones with a high content of sludge-clay fractions are established, concentrated alkaline cyanide leaching solutions are pumped into these zones through wells, performing gold diffusion leaching, and after holding a pause, explosive charges are placed, placed in ampoules with water, in parts of wells located within the zones of mudding, they explode charges, carrying out loosening of the material with simultaneous explosion oinektsionnoy treatment resulting in the explosion of the charge of water-gas mixture, whereupon dovyschelachivanie mineral mass through irrigation all stacks weak alkaline cyanide solution.

The method is as follows.

The crushed ore or the agglomerated mineral mass obtained on its basis is poured into stacks, an irrigation system is mounted on their surface and leaching alkaline cyanide solutions are fed through it into the mineral mass in a circulating mode. When the gold content drops in the formed productive solutions at the second stage, the irrigation system is temporarily dismantled, wells are drilled and equipped in the stack, with the help of which the mineral mass is tested, the results of which establish the contours of zones with an increased (from 20% by volume) sludge content clay fractions, concentrated alkaline cyanide solutions are injected under pressure into these zones through wells, with a concentration of sodium cyanide from 0.5% (weight), they are carried out using diffusion leaching, and after holding a pause of 2-5 days, place ampoules with water in the corresponding sections of the wells, inside which explosive charges are placed, and fill the upper part of the well with clogging - a small fraction of ore and carry out explosive loosening of the material in these zones with simultaneous explosion-injection processing of the material water-gas mixture formed during the explosion of explosive charges. In the explosion of charges of this design, water under the pressure of the resulting explosive gases penetrates into the space between the relatively large parts of the ore, increasing the distance between them and, accordingly, weakening their bonds with sludge-clay particles, which allows the working solution formed by mixing water and concentrated solution to leach gold. In addition, the temperature of the resulting working solution increases significantly, which is especially important when conducting the process in the autumn-winter and spring periods. After explosive activation of the mineral-reagent mixture, the irrigation system is re-mounted in the zones of colmatization and the entire stack is irrigated with low concentrated (0.02-0.2% NaCN) alkaline cyanide solutions, and when they are fed into the leachable material, a low concentrated (0.03-0.3%) ) a working solution of leaching reagents, which, when interacting with the mineral mass of the stack, provides additional leaching of gold from it with extraction from productive solutions on a sorbent to an economically viable level.

An example of a specific use of the method.

The ores of the Savkinskoye gold ore deposit are predominantly mineralized metasomatites of 2 basic genetic types (argillized metamorphic rocks and hydrothermally modified intrusive rocks of the diorite series with a high (up to 20%) quartz-tonalite content. Oxide-hydroxide is the basis of productive mineral paragenesis associated with gold minerals of iron and manganese. Gold is predominantly thin and fine (from 1 to 60 microns), while it is highly likely to be in dispersed form with cluster and atomic scattering levels in the crystal lattices of oxide-hydroxide and sulfide minerals-carriers, in clay minerals (in the latter it can also be in the form of sorbed ions). From the standpoint of applicability of heap leaching technology for processing Savkinsky ores, the following set of problems causing a low level of gold recovery:

- the difficulty of ensuring full contact of working solutions with fine particles and dispersed inclusions of gold, diffusion of cyanides and oxygen to the surface of its relatively large particles, often covered with "shirts" of oxides and hydroxides of iron and manganese, a carbonaceous substance;

- high sludge ores, causing clogging in certain areas of stacks, even when using their preliminary agglomeration;

- due to the presence in the ores of a significant amount of manganese dioxide-pyrolusite, clay minerals and mica, parasitic sorption of dissolved gold is manifested;

- oxides and hydroxides of manganese determine the oxidation of cyanides with their conversion to cyanates.

The proposed method for the processing conditions of the ores of the Savkinsky deposit can be implemented as follows.

After crushing, the ore is screened, and a small class (-5 mm) is agglomerated with cement and lime. A large class is laid in the base of the stack on a waterproofing coating (clay-sand-clay-polymer film) and a drainage pipe system is mounted in its lower layer. An irrigation system is mounted on the surface of the stack, including hoses, distribution pipes and emitters, and active alkaline cyanide leaching solutions (cyanide concentration 0.05%) are fed through them into the agglomerated mineral mass in a circulating mode. At the same time, solutions from the accumulating sump are analyzed for the content of gold and residual cyanides and, when a concentration of more than 1 mg / l is reached, they are fed to sorption columns, after which they are further strengthened with reagents and again fed for irrigation. When the gold content in the productive solutions drops to less than 1 mg / l, the irrigation system is temporarily dismantled, wells are drilled and equipped, and the mineral mass is tested, the results of which establish the position of the upper and lower boundaries of the zone with an increased (from 20% volume) content of sludge-clay fractions formed when the free space of the lump fraction was filled with small particles of destructible pellets from the upper part of the stack moving with leaching solutions. The wells are equipped with locally perforated plastic pipes and pumped through them under pressure into the formed mud zones, concentrated (with a sodium cyanide content of 1%), active alkaline cyanide leaching solutions at the rate of 30 l of solution per ton of ore, using which gold diffusion leaching is carried out, and after a pause of 3 days, thin-walled (1.5 mm thick) ampoules of water (which are plastic sealed from the ends) are placed in the wells (in the area of mudding) tubes with water) with a diameter of 100 mm, inside which charges of emulsion explosives are placed in plastic tubes with a diameter of 50 mm, and explosive loosening of the material in these zones is carried out with simultaneous explosion-injection treatment of the material with a water-gas mixture. At the end, the irrigation system is re-mounted and the entire stack is irrigated with low concentrated (0.02% NaCN) alkaline cyanide solutions to form a working solution with a concentration of 0.05% in the stack and add gold to it, the resulting product solutions are collected in drainage-collector openings (grooves and sumps) at the base of the stack and pumped into sorption columns filled with activated carbon, which is unloaded as it is saturated and sent to desorb gold from it. If necessary, de-gilded solutions are strengthened with cyanide and fed to the next irrigation cycle.

The final gold recovery for coal from the ores of the Savkinsky deposit according to the simulation results in the explosive chambers of this scheme is 80%.

Claims (1)

A method of heap leaching of gold from ores, including crushing ore, forming stacks from crushed ore, leaching of gold by supplying a reagent solution to the stack until the gold content in the productive solutions falls below the technological limit, drilling wells, placing explosives in them, exploding charges, adding mineral mass, the collection of productive solutions, followed by extraction from the productive solutions of gold, characterized in that they carry out testing of mineral mines when drilling wells According to the results of which, the contours of the zones of mudding with a high content of sludge-clay fractions are established, concentrated alkaline cyanide leaching solutions are injected under pressure into these zones through wells, performing gold diffusion leaching, and after holding pauses, explosive charges placed in ampoules with water, in parts of wells located within the zones of mudding, they explode charges, carrying out loosening of the material with simultaneous explosion-injection treatment of which develops during the explosion of charges with a water-gas mixture, after which additional mineralization of the mineral mass is carried out by irrigation of the entire stack with a weak alkaline cyanide solution.