CN100386450C - Combined Leaching Method of Low-grade Refractory Gold Ore - Google Patents

Abstract

The invention relates to a combined leaching method for hydrometallurgy of low-grade refractory gold ores. After the ore is crushed, a combined leaching agent is prepared with low-concentration ammonium salt, ammonia water and an oxidant, and the leaching agent is directly heap leached or broken and ground before tank leaching. A leach solution with low impurity content and high gold concentration is produced. This leaching solution can be extracted by conventional methods such as replacement, activated carbon adsorption or resin exchange, and regenerated to cooperate with the leaching agent for reuse. The method has the advantages of simple process, short process, fast leaching speed, high leaching rate, low cost, non-cyanide and non-toxicity, and is a gold extraction method that is easy to realize industrial production and has good economic and environmental benefits.

Description

Combined Leaching Method of Low-grade Refractory Gold Ore

[technical field]

The invention relates to a method for coordinating leaching gold from gold ores in nonferrous metallurgy, in particular to a method for coordinating and leaching gold from low-grade copper-bearing gold ores or carbon-carrying gold ores.

[Background technique]

The smelting methods for low-grade and refractory gold ores can be mainly divided into three categories: the first category is the traditional xanthate-black medicine combined flotation method to obtain gold concentrate, which is roasted, then leached with cyanide, and activated carbon adsorption , and finally desorption, electrowinning. The recovery rate of this method is low, generally only 50%, and the cost is high, the flow process is long, and there is pollution of sulfur dioxide flue gas and cyanide. The second type is to use low-concentration cyanide solution to directly heap leach low-grade gold ore, then use activated carbon column to adsorb, then desorb and electrowinning. This method has the advantage of low cost and is widely used in developed countries such as the United States. However, this method pollutes groundwater sources and poses a serious threat to the environment. The third category is to use low-concentration thiosulfate and ammonia solution to directly heap leaching low-grade gold ore, followed by replacement and fire refining. Because this method uses less toxic thiosulfate as the leaching agent, there are currently many studies in the world, but because thiosulfate is unstable and easy to decompose, there are not many real industrializations.

[Content of the invention]

The purpose of the present invention is to provide a method for coordinated leaching of low-grade refractory gold ores.

The purpose of the present invention is achieved through the following technical solutions of heap leaching or tank leaching:

First, crush the mined mixed ore into qualified crushed ore or continue to finely grind it into ore powder, and then pile it up according to a certain method or in the stirring tank, implement oxidant-containing ammoniacal ammonium salt solution with cyclic heap leaching or tank leaching, leaching Agent composition: the concentration is 0.1-5mol/L ammonium chloride, the concentration is 0.1-0.5mol/L industrial grade ammonia water, the liquid-solid ratio is 0.1-3L/Kg ore during heap leaching, the oxidant can be air and Cu ²⁺ , oxygen With Cu ²⁺ , sodium hypochlorite, bleaching powder or single Cu ²⁺ , the amount of oxidant added is: bleaching powder is 5g-100g per kilogram of ore; sodium hypochlorite is 1-25g per kilogram of ore; air or oxygen and Cu ²⁺ are used as oxidant 0.005-0.05mol/L Cu ²⁺ is added to the compound leaching agent containing copper ore, and Cu ²⁺ is not added to the compound leaching agent containing copper ore; when Cu ²⁺ is used alone as the oxidant, the leaching The concentration of Cu ²⁺ in the agent is 0.01-0.1mol/L.

Finally, the qualified leaching solution is extracted by traditional displacement or adsorption methods and regenerated with the leaching agent.

During the complex leaching process, the main reactions that take place are:

Au+kNH ₄ Cl→AuCl _k ^jk +k NH ₄ ⁺ +je

In the formula: k is the coordination number of Cl ^- , and j is the valence number of the corresponding gold ion.

The oxidation-reduction reaction is:

O ₂ +2H ₂ O+4e ^- → 40H ^-

Cu ²⁺ +e ⁻ →Cu ⁺

C10 ^- +H ₂ O+2e ^- →Cl ^- +20H ^-

The present invention utilizes the principle that ^Cl in the leaching agent forms a stable complex with gold ions and that Cu ²⁺ has a catalytic or activating effect on leaching gold, because Cu ²⁺ has oxidative properties, and the air is easy to oxidize Cu ⁺ into Cu ²⁺ , thus forming an oxidation-reduction cycle mechanism. Therefore, when air or oxygen is used as the oxidant, if the gold ore does not contain copper, 0.005-0.05mol/L Cu ²⁺ should be added when preparing the compound leaching agent, and there is no need to add Cu 2+ to the compound leaching agent containing copper ore. Cu ²⁺ .

In the production process of the present invention, no flue gas and dust are produced, which greatly reduces the comprehensive cost of resource extraction and scale production investment, and the gold leaching rate of combined gold mines is ≥ 65%, and the gold leaching rate of natural gold mines is ≥ 92%; Low cost, less investment, and non-polluting gold extraction provide non-cyanidation and non-toxic advanced technology for the recovery and utilization of gold from refractory gold mines.

[Detailed ways]

The mined mixed type minerals are crushed to a particle size between 0.5mm and 20mm for heap leaching. The height of the heap is 5-8m, start spraying with a pre-prepared compound leaching agent of a certain composition, and then spray circularly with the leaching solution that has not reached the qualified concentration, the liquid distribution intensity is 4-25L/(m ² ·h), The leaching time is 50-150d, the natural gold ore leaching time can be slightly shorter, and the combined gold ore leaching time can be slightly longer. The gold ore for tank leaching must be ground to below 140 mesh, and then leached in a stirred tank at a liquid-solid ratio of 2-6:1 at 20-60°C for 2-12 hours.

The process conditions of the method of the present invention are further illustrated with the following non-limiting examples, and the percentages described in the examples are all percentages by weight.

Example 1 is from a low-grade, difficult-to-handle copper-bearing gold mine in Gansu, which is enriched by conventional flotation, and the gold recovery rate is only 50%. The copper in the copper-bearing gold ore exists in the form of oxide ore, and the gold in it exists in the form of extremely small gangue-type wrapped gold. The chemical composition of the gold ore is shown in Table 1.

Table 1. Chemical composition of a low-grade refractory copper-bearing gold ore

^* means g/t

The particle size of the raw ore is 30-0.1mm. Use 2mol/L NH ₄ Cl, 0.2mol/L NH ₄ OH, and use a plexiglass column of Φ125×1500mm to carry out 10Kg column leaching. Add 500g of bleaching powder to the ore column, and leaching for 100d , the gold leaching rate was 76.4%.

Embodiment 2 adopts the above-mentioned low-grade copper-containing gold ore, grinds it to -200 mesh>80%, takes 1Kg and joins it in an 8L leaching tank, and adds 20 grams of bleaching powder at the same time, and then uses 4mol/L NH ₄ Cl and 0.5mol/L NH ₄ OH mixed leaching agent 5L, stirred and leached at room temperature for 12h, the gold leaching rate reached 82.5%.

Because the reserves of low-grade refractory gold ores containing copper or carbon are very rich, the development is economically reasonable, environmentally friendly, and can replace the cyanidation method. The simple and effective gold extraction method suitable for the development and utilization of such resources should have important practical significance.

Claims (2)

1. one kind cooperates the method that leaches low-grade intractable gold mine, it is characterized in that: with concentration is 0.1～5mol/L ammonium chloride, and concentration is 0.1～0.5mol/L technical grade ammoniacal liquor, and air and Cu ²⁺, oxygen and Cu ²⁺, clorox, chlorinated lime or single Cu ²⁺Oxygenant is prepared and is cooperated leaching agent to leach difficult-treating gold mine, and the leaching mode comprises dump leaching or drill traverse, and the leach liquor that contains gold reclaims golden valuable metal with ordinary method, and regeneration cooperation leaching agent, and recycle cooperates the major technique condition that leaches to be:

Liquid-solid ratio is 0.1～3L/Kg ore deposit during dump leaching, and spray rate is 4～25L/ (m ²H), the time is 50～150d; Liquid-solid ratio is 2～6: 1 during drill traverse, and temperature is 20～60 ℃, and the time is 2～15h.

2. method according to claim 1 is characterized in that, the add-on of described oxygenant is: chlorinated lime adds 5g～100g for the per kilogram ore; Clorox per kilogram ore adds 1～25g; Adopt air or oxygen and Cu ²⁺Make oxygenant, do not allocate the Cu of 0.005～0.05mol/L in the cooperation leaching agent of copper-containing ore into ²⁺Use Cu separately ²⁺As oxygenant, Cu in the leaching agent ²⁺Concentration be 0.01～0.1mol/L.