RU2566231C1 - Method of heap leaching of disperse gold from refractory ores - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: before ore stacking it is crushed and separated into undersize and oversize ore products. The undersize product is agglomerated using the solution containing oxidizers for the mineral forming elements associating with gold. Ore is stacked layer-by layer. The bottom layer is poured out from oversize products and irrigated by the solution containing oxidizers for the mineral forming elements associating with gold. Then on the bottom layer the agglomerated undersize products are poured out for formation of top layer of the stack. After holding the whole stack is irrigated at first with the low-concentrated solution containing oxidizers for the mineral forming elements associating with gold or with water. Then the top layer of the stack is impregnated with the concentrated solution containing oxidizers and complexing compound for gold, the second pause is held, and then the whole stack is irrigated with the low-concentrated solution containing oxidizers and the complexing compound for gold or water.

EFFECT: increase of extraction of disperse gold and decrease of consumption of complexing compound during leaching.

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Description

The invention relates to hydrometallurgy of precious metals, namely to the hydrometallurgical processing of gold-bearing ores and technogenic mineral raw materials, and is intended to extract gold from them.

A known method of heap leaching of gold from ores, according to which the ore is crushed, after which it is stacked and irrigated with a solution of alkali metal cyanides. (Dementiev V.E. et al. Heap leaching of gold and silver. Irgiredmet, 2001).

The disadvantage of this method is its low efficiency due to the impossibility of extracting dispersed gold, which makes up the bulk of the reserves of deposits of refractory ores and technogenic formations, which is associated with insufficient access of complexing agents to nanosized gold particles contained in the crystal lattices of carrier minerals.

Closest to the claimed is a method of heap leaching of ores containing finely divided gold, including irrigation of the ore mass with potassium cyanide solutions, which are fed to the ore stacks in an amount not exceeding the pore volume of the ore mass, they are aged and then gold is leached out with a cyanide-free caustic solution potassium or caustic soda (see RF patent No. 2009234, IPC C22B 11/08, publ. March 15, 1994).

The disadvantage of this method is its low efficiency due to the high consumption of sodium cyanide and insufficiently high dispersed gold recovery, as a result of its interaction at the stage of aging (diffusion leaching), with mineral-forming elements associated with gold and partial transition to rhodanides, as well as insufficient structural transformation of mineral matrices containing dispersed gold.

The technical result of the invention is to increase the efficiency of a method for processing technogenic mineral raw materials by reducing the consumption of complexing agents and increasing the extraction of dispersed gold.

The specified technical result is achieved in that the method of heap leaching of dispersed gold from refractory ores, including stacking and stage irrigation of the stack with various solutions, differs in that before laying the ore into stacks, the raw materials are crushed and screened with separation into sublattice and sublattice crushing products, sublattice crushing product is agglomerated using a solution containing oxidizing agents for mineral-forming elements associated with gold, laying mineral The raw material in the stacks is carried out in layers: the lower layer is sprinkled from the superlattice (coarse) classes of ore and irrigated with a solution containing oxidizing agents for mineral forming elements associated with gold, after which the agglomerated sublattice products of ore crushing are dumped onto the lower layer, which forms the upper layer of the stack and after exposure, the entire stack is irrigated with an initially low-concentrated solution containing oxidizing agents for mineral-forming elements associated with gold s or water, and then the upper layer of the stack is impregnated with a concentrated solution containing oxidizing agents and complexing agents for gold withstand second pause, then the entire stack is performed irrigation low concentrations of a solution containing oxidizing agents and complexing agents for gold or water.

Distinctive features of the proposed method is that before laying the ore in stacks, crushing and screening of the raw materials is carried out with separation into sublattice and sublattice crushing products, the sublattice crushing product is agglomerated using a solution containing oxidizing agents for gold-forming mineral-forming elements, laying mineral raw materials in stacks carried out in layers: the lower layer is sprinkled from the superlattice (coarse) classes of ore and irrigated with a solution containing oxidizing agents for associated with gold mineral-forming elements, after this, the agglomerated sublattice products of ore crushing are poured onto the lower layer, which forms the top layer of the stack, and after exposure, the entire stack is irrigated with an initially low-concentrated solution containing oxidizing agents for gold-forming mineral elements or water, and then the upper the stack layer is impregnated with a concentrated solution containing oxidizing agents and complexing agents for gold, withstand the second auzu, and then irrigate the entire stack with a low-concentration solution containing oxidizing agents and complexing agents for gold or water.

A solution containing oxidizing agents for mineral-forming elements associated with gold and an active solution containing oxidizing agents for gold (before complexing agents for gold are introduced into it) are prepared by air sparging and subsequent electrolysis and / or photolysis (irradiation with UV light in the range of 180-300 nanometers) of a water-gas suspension obtained during the electrolysis of an initial solution of reagents producing a group of hydrogen peroxides during processing, including a hydroxyl radical and / or hypochlorous acid. The resulting solution containing oxidizing agents for mineral-forming elements associated with gold is used for agglomeration preparation of a fine ore fraction for leaching and during initial irrigation of stacks by it. An active solution containing oxidizing agents for gold is used to prepare the actual leaching solution (by introducing complexing agents for gold into it), which, in turn, is used in the second stage to actually leach the gold.

The method is as follows.

In photoelectrochemical reactors, an active oxidizing solution and a leaching solution are prepared by sparging with air and subsequent electrolysis of a solution of the initial reagent, at the final stage of which the resulting water-gas suspension is irradiated with UV light in the range of 180-300 nanometers, and then a complexing agent or substance is introduced into the leaching solution , forming it in the interaction with the products of photoelectrochemical synthesis. During the electrolysis of a solution of a number of easily dissociating alkalis, salts and acids, bubbles of oxygen, chlorine (or other halogens), carbon dioxide, which also contain water vapor, are released on the anode. During subsequent photochemical reactions, in the volume of bubbles emitted at the anode, the molecules of water and electrolytic gas, for example, diatomic oxygen, excited as a result of absorption of UV radiation quanta, decompose into active atoms and radicals or ionize, and the decomposition products interact with other excited molecules form secondary active radicals, ions, radical ions or strong molecular oxidizing agents:

, $$S_2{O}_8^{\ast }$$

, $$S_2{O}_2^{+}$$

, $$S_2{O}_4^{+}$$

, Cl*, HCl*. HClO*, ClO*.During the coalescence of oxygen and hydrogen bubbles (emitted at the cathode), mutual diffusion of these gases occurs, which ensures the increase in the yield of active oxygen and hydrogen compounds during UV irradiation of such a water-gas suspension. Since the bubbles of electrolytic gases are surrounded by water, ozone, atomic oxygen, hydroxyl radical, and other active compounds obtained as a result of photochemical reactions diffuse into film water before recombination, forming active hydrate complexes. Thus, photoelectrochemical synthesis allows high yield in a solution of H ₂ O ₂ , OH *, and also, if necessary, using the corresponding starting soluble substances and active compounds with other elements, in particular, sulfur, carbon and chlorine: $$S_2{O}_3^{\ast }$$

, $$S_2{O}_8^{\ast }$$

, $$S_2{O}_2^{+}$$

, $$S_2{O}_{\mathrm{four}}^{+}$$

, Cl *, HCl *. HClO *, ClO *.

Hydroxyl radicals, having a high redox potential (2300 mV), present in any of the three types of solutions, provide the possibility of oxidation by them of atoms not only of iron and sulfur, but also of dispersed forms of gold and platinoids, and, therefore, their conversion to ionic shape and growth of diffusion activity in the volume of the crystal lattice of minerals.

In the preparation of the actual leaching solutions, an active water-gas suspension obtained in a photoelectrochemical reactor due to the formation of ion-radical clusters of the type H ⁺ · nH ₂ O · HO * ^- in it ensures the association of cyanide complexes with the formation of complex cluster structures containing two and more complexing CN ^- anions, which leads to the intensification of leaching of dispersed gold due to not sequential, but simultaneous interaction of a gold atom with two CN anions (or radicals):

In parallel with the preparation of solutions, ore is crushed and screened, followed by agglomeration of sublattice crushing products. In this case, cement, calcium oxide and a solution obtained during photoelectrochemical processing using oxidizing agents for mineral-forming elements associated with gold are used for agglomeration. After that, laying in the lower layer of the stack of over-lattice (coarse-grained) classes of ore, and pouring on it the upper layer of agglomerated sublattice products of ore crushing. Before filling agglomerated material, a layer of coarse mineral mass is irrigated with an oxidizing solution. Next, two layers of the mineral mass are aged to oxidize it for leaching for 2-5 days, after which the entire stack is irrigated with an initially low-concentrated solution containing oxidizing agents for mineral-forming elements associated with gold or water, and then the top layer of the stack is impregnated with a concentrated solution containing oxidizing agents and complexing agents for gold, withstand a second pause, and then irrigate the entire stack of low-concentration a saline solution containing oxidizing agents and complexing agents for gold or water.

An example of a specific implementation of the method.

The method was tested on the ores of the Amazarkan deposit. Ore samples were represented by at least 3 genetic types: metasomatites formed by leucocratic granitoids (about 80% of the total), metasomatized intrusive rocks of the diorite and gabbro-diorite series, metasomatized gneisses formed mainly by granodiorites. Metasomatic changes are manifested by sulfidization, turmanization, sericitization and silicification. In the samples, individual dikes of hybrid porphyries with less pronounced than in mineralization-bearing rocks, sulfidization, silicification and seritization, were found. Samples taken from the receiving hopper DSK-1. have an average diameter of pieces of ore in the range of the order of 30-350 mm The gold content in the average ore samples, according to the assay-atomic absorption analysis, is 0.55-0.65 g / t (presumably, the ore did not go through the stage of average crushing due to its low content and was left in place).

Averaged ore sample from the DSK-1 receiving hopper with a total weight of 12 kg was sent for crushing to the SGS-East Limited laboratory (Chita), after which the ore material was sieved and weighed (by fractions). An input analysis confirmed the low content of samples of all types of Amazarkan ores (0.5-0.65 g / t). Moreover, in the fine fraction (-5 mm), the yield of which was 1.4%, the concentration of sulfide-quartz aggregates and, accordingly, gold (0.93 g / t) is noted. The crushed ore was divided into three 3 kg samples, which were placed in plastic columns. In the first (control) column, standard droplet irrigation with a cyanide solution was simulated, in the second with preliminary treatment with an active solution of a fraction of 5-10 mm in a cuvette for 5 days, followed by drip irrigation with cyanides, in the third with agglomeration of a -5 mm fraction using an oxidizing peroxide-carbonate solution obtained in a photoelectrochemical reactor, drip irrigation with this oxidizing solution of the bulk of the sample. After a pause of 5 days, the ore in the column was irrigated with a weak oxidizing solution, after which the solution was discharged from the column. Next, irrigation was carried out with a concentrated peroxide-cyanide solution of the upper part of the column with agglomerated material. A pause of 3 days and irrigation of the entire material of the column with a weak solution of cyanide for 7 days. Moreover, the extraction of gold into the liquid phase according to this activation scheme amounted to 85% for the entire duration of the experiment, according to the 2 other schemes, 43% and 57%, respectively.

Claims (1)

The method of heap leaching of dispersed gold from refractory ores, including stacking the ore into stacks and stage-stage irrigation with solutions of various composition, characterized in that before stacking the ore into stacks, ore is crushed and screened with separation into sublattice and sublattice crushing products, sublattice ore crushing product agglomerate using a solution containing oxidizing agents for mineral-forming ore elements associated with gold, ore is stacked in layers, with the lower loya is poured from the superlattice coarse-grained classes of ore and irrigated with a solution containing oxidizing agents for the mineral-forming elements of ore associated with gold, then the agglomerated sublattice products of ore crushing are poured onto the lower layer and the upper layer of the stack is formed, then the first exposure is carried out and the entire stack is irrigated with a low concentrated solution containing oxidizing agents for mineral forming elements associated with gold, or water, then the top layer of the stack is impregnated with a concentrated solution ohm containing oxidizing agents and complexing agents for gold, and the second exposure is performed, and then the entire stack is performed irrigation low concentrations of a solution containing oxidizing agents and complexing agents for gold, or water.