Method for reducing consumption of sodium cyanide in copper-containing gold ore

Abstract

The invention discloses a method for reducing sodium cyanide consumption of copper-containing gold ore, and belongs to the technical field of hydrometallurgy. The copper-containing gold ore and the gold concentrate cyanogen residues are mixed according to a certain proportion and then pretreated, acid generated in the pretreatment process reacts with carbonate in the copper ore to expose the copper ore, and after ammonium salt is added, copper in the copper ore is complexed with ammonia. And through solid-liquid separation, copper does not enter a cyanidation leaching system any more, so that the purpose of reducing the consumption of sodium cyanide is achieved. The method is simple in technological process and low in production cost, and can effectively solve the problem of high consumption of sodium cyanide in the cyanidation leaching process of the copper-containing gold ore. After the sodium cyanide is treated by the method, the consumption of the sodium cyanide is reduced by more than 75%.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgy and relates to a method for reducing the consumption of sodium cyanide in copper-bearing gold ores. Background Art

[0002] Copper-bearing gold ores are one type of refractory gold ores. During the cyanidation leaching of gold from copper-bearing gold ores, copper complexes with cyanide, consuming a large amount of sodium cyanide and causing a significant increase in the costs of enterprises. At the same time, the formed copper-cyanide complexes not only affect the leaching rate of gold but also consume a large amount of acid during the treatment of lean solution.

[0003] On the other hand, a large amount of cyanide residue is produced in gold smelting. As hazardous solid waste, the cyanide residue contains valuable metal elements and toxic elements with high mobility such as Au, Ag, As, Cu, Pb, Zn, and CN - etc. Long-term stacking not only affects the ecological environment but also causes waste of resources. Therefore, the harmless treatment of cyanide tailings in the gold smelting industry is very urgent. The Chinese patent application with the publication number CN113025821A discloses "a comprehensive treatment method for the resource utilization of cyanide tailings". After proportioning gold-copper concentrate, cyanide tailings, quartzite, coal, etc., and through high-temperature smelting, the cyanide in the cyanide tailings is destroyed by pyrometallurgy to generate carbon dioxide and nitrogen oxides. Compared with other cyanide tailings disposal methods, this method can reduce the treatment cost of cyanide tailings to a certain extent and realize the recovery of valuable metals such as gold, silver, and copper in the cyanide residue. However, this method belongs to a high-temperature treatment method, with large energy consumption during the treatment process, and there is still the problem that copper complexes with cyanide and consumes a large amount of sodium cyanide.

[0004] The Chinese patent application with the publication number CN108018418A discloses "a wet pretreatment method for sulfide-coated refractory gold ores". By wet-preprocessing the coated refractory gold ores, the coating of gold is opened to achieve the purpose of improving the leaching rate of gold. During the implementation process, the acid generated by the pretreatment is neutralized with lime. Although it can increase the pretreatment reaction rate, after pretreatment, copper still consumes a large amount of sodium cyanide during the cyanidation leaching of copper-bearing gold ores. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for reducing the consumption of sodium cyanide in copper-bearing gold ores, which can effectively reduce the consumption of sodium cyanide in copper-bearing gold ores on the premise of realizing the recycling of cyanide residue.

[0006] The technical solution of the present invention is as follows: A method for reducing the consumption of sodium cyanide in copper-bearing gold ores, comprising the following steps carried out in sequence: (1) Ultrafine grind the gold concentrate cyanide residue to P 80≤30 μm, and finely grind the copper-bearing gold ore to P 80 ≤100 μm; (2) Mix the cyanidation residue of gold concentrate after ultrafine grinding and the copper-bearing gold ore after fine grinding in proportion, and make the effective sulfur content after mixing ore be 18% - 25%; (3) Modulate the mixed product after mixing ore into pulp with a concentration of 10% - 30%; (4) Pass oxygen into the said pulp, and control the dissolved oxygen concentration in the pulp within the range of 9 - 15 mg / L, and react for 8 - 15 h under stirring; (5) Adjust the pH value of the pulp to 10.5 - 11.5, add ammonium sulfate or ammonium chloride as ammonium salt, and carry out copper leaching for 8 - 24 h under stirring; (6) Carry out solid-liquid separation on the pulp after copper leaching; the obtained liquid is used to produce blister copper; the obtained solid is adjusted to the pulp concentration and then leached with sodium cyanide for gold extraction.

[0007] Preferably, in step (1), the cyanidation residue of gold concentrate is ultrafinely ground to P 80 ≤20 μm.

[0008] Preferably, in step (2), the effective sulfur content after mixing ore is 20% - 23%.

[0009] Preferably, in step (4), the stirring linear velocity ≥ 12 m / s.

[0010] Preferably, in step (5), control the reaction temperature at 60 - 95 °C.

[0011] Preferably, the calculation method of the ammonium salt addition amount in step (5) is as follows: ; In the formula: Q represents the ammonium salt addition amount per ton of cyanidation residue of gold concentrate and copper-bearing gold ore, unit kg / t; K represents the adjustment coefficient of ammonium salt addition amount, taking 1.5 - 2.5; M represents the relative molecular mass or relative atomic mass of the anion in the ammonium salt; N represents the molar ratio of the cation to the anion in the ammonium salt; P represents the mass ratio of copper-bearing gold ore to cyanidation residue of gold concentrate; β represents the copper grade in the copper-bearing gold ore, unit kg / t.

[0012] Preferably, the liquid obtained by solid-liquid separation in step (6) is used to produce blister copper by electrowinning process.

[0013] Compared with the prior art, the present invention has the following beneficial effects: First, in the present invention, after pretreating the carbonate and copper minerals in the copper-bearing gold ore with the acid generated during the oxidation of cyanide slag from gold concentrate, an ammonium salt is added to complex copper with ammonia. Through solid-liquid separation, the reaction of copper with sodium cyanide is reduced, thereby achieving the purpose of reducing the consumption of sodium cyanide in the copper-bearing gold ore. Further, according to the steps of the present invention, the cyanide slag from gold concentrate is ultrafinely ground and then oxidized under high dissolved oxygen and high shear conditions. The generated acid reacts with the carbonate in the ultrafinely ground copper-bearing gold ore, enabling the copper minerals to be fully exposed. The copper minerals react with the ammonium salt to form copper-ammonia complex ions. After solid-liquid separation, contact with cyanide is avoided, thus reducing the consumption of sodium cyanide during the subsequent gold cyanidation process. Experiments show that after treatment by the method of the present invention, the reduction rate of sodium cyanide consumption reaches more than 75%.

[0014] Second, according to the method of the present invention, the addition amount of the ammonium salt is related to the molecular weight of the anion in the ammonium salt, the molar ratio of the cation to the anion in the ammonium salt, the mass ratio of the copper-bearing gold ore to the cyanide slag from gold concentrate, and the copper grade in the copper-bearing gold ore. Through repeated experimental exploration, the present invention has obtained a calculation formula for the addition amount of the ammonium salt. With the help of this formula, the addition amount of the ammonium salt that meets the requirement of reducing the consumption of sodium cyanide in the copper-bearing gold ore of the present invention can be accurately calculated. Specific Embodiments

[0015] The present invention will be further described below in conjunction with examples, comparative examples, and experimental data.

[0016] In the copper-bearing gold ore used in the examples of the present invention, the copper content (i.e., copper grade) is 8.6 kg / t, and the effective sulfur content is 1.2%; the effective sulfur content of the cyanide slag from gold concentrate used in the examples of the present invention is 43.22%.

[0017] Example 1 (1) Ultrafinely grind the cyanide slag from gold concentrate to P 80 = 20 μm, and ultrafinely grind the copper-bearing gold ore to P 80 = 74 μm; (2) Mix the ultrafinely ground cyanide slag from gold concentrate and the ultrafinely ground copper-bearing gold ore according to a mass ratio of 1:1. After mixing, the effective sulfur content is 22.21%; (3) Adjust the pulp concentration of the mixed product after mixing to 20%; (4) Pass oxygen into the pulp, control the dissolved oxygen concentration in the pulp to 10 mg / L; stir at high speed with a shear rate of 12 m / s; the reaction time is 12 h; (5) Adjust the pH value of the pretreated pulp to 11, add 28.76 kg / t of ammonium chloride (here, t refers to the total mass of the copper-bearing gold ore and the cyanide slag from gold concentrate), stir the pulp, control the reaction temperature at 80 °C, and the copper leaching time is 16 h; Calculation process for the addition amount of ammonium chloride: ; Substitute M (relative atomic mass of chlorine atom is 35.5), N (molar ratio of cation to anion in ammonium chloride is 1), P (mass ratio of copper-containing gold ore to gold concentrate cyanide residue is 1), β (copper grade in copper-containing gold ore is 8.6 kg / t), and K = 2.0 into the above formula, then Q = 28.76 kg / t. In this step, since both the reaction temperature and the leaching time are controlled near the middle values of their ranges, K takes the middle value of its range;

[0018] (6) Perform solid-liquid separation on the pulp after copper leaching. The liquid is processed by electrowinning to produce crude copper; after adjusting the pulp concentration of the solid to 40%, use lime to adjust the pH value to 11 ± 0.5, add sodium cyanide for gold leaching, and maintain the sodium cyanide concentration not less than 0.10% during the sodium cyanide gold leaching process, and the cyanidation gold leaching time is not less than 24 h.

[0019] The initial concentration of sodium cyanide is 1.00%, and the final concentration of sodium cyanide is 0.31%. Statistically analyze the sodium cyanide concentration before and after sodium cyanide gold leaching, and calculate the sodium cyanide consumption to be 10.35 kg / t.

[0020] Example 2 In step (2), the gold concentrate cyanide residue after ultrafine grinding and the copper-containing gold ore after fine grinding are proportioned according to a mass ratio of 1.4:1. After proportioning, the effective sulfur content is 18.51%.

[0021] In step (5), control the reaction temperature at 90 °C and the copper leaching time at 8 h. In this step, since the reaction temperature is controlled near the upper limit value of the range, but the leaching time is at the lower limit value of the range, K takes the middle value of its range, which is 2.0. In this example, since P = 0.71, the ammonium chloride addition amount Q = 33.63 kg / t.

[0022] Other steps are the same as those in Example 1.

[0023] The initial concentration of sodium cyanide is 1.00%, and the final concentration of sodium cyanide is 0.32%. Statistically analyze the sodium cyanide concentration before and after sodium cyanide gold leaching, and calculate the sodium cyanide consumption to be 10.20 kg / t.

[0024] Example 3 In step (2), the gold concentrate cyanide residue after ultrafine grinding and the copper-containing gold ore after fine grinding are proportioned according to a mass ratio of 0.8:1. After proportioning, the effective sulfur content is 24.39%.

[0025] In step (5), control the reaction temperature at 62 °C and the copper leaching time at 24 h. In this step, since the reaction temperature is controlled near the lower limit value of the range, but the leaching time is at the upper limit value of the range, K takes the middle value of its range, which is 2.0. In this example, since P = 1.25, the ammonium chloride addition amount Q = 25.56 kg / t.

[0026] Other steps are the same as those in Example 1.

[0027] The initial concentration of sodium cyanide is 1.00%, and the final concentration of sodium cyanide is 0.30%. The concentrations of sodium cyanide before and after gold leaching with sodium cyanide are statistically analyzed, and the consumption of sodium cyanide is calculated to be 10.50 kg / t.

[0028] Example 4 In step (5), 35.48 kg / t of ammonium sulfate is added instead of ammonium chloride.

[0029] According to the following formula: ; Substitute M = 32 + 16×4 = 96, N = 2, P = 1, β = 8.6, and K = 2.0 into the above formula, and Q = 35.48.

[0030] Other steps are the same as those in Example 1.

[0031] The initial concentration of sodium cyanide is 1.00%, and the final concentration of sodium cyanide is 0.32%. The concentrations of sodium cyanide before and after gold leaching with sodium cyanide are statistically analyzed, and the consumption of sodium cyanide is calculated to be 10.2 kg / t.

[0032] Example 5 In step (4), the dissolved oxygen concentration in the pulp is controlled at 9 mg / L.

[0033] Other steps are the same as those in Example 1.

[0034] The initial concentration of sodium cyanide is 1.00%, and the final concentration of sodium cyanide is 0.32%. The concentrations of sodium cyanide before and after gold leaching with sodium cyanide are statistically analyzed, and the consumption of sodium cyanide is calculated to be 10.2 kg / t.

[0035] Comparative Example 1 In step (4), the dissolved oxygen concentration in the pulp is controlled at 8 mg / L.

[0036] Other steps are the same as those in Example 1.

[0037] The initial concentration of sodium cyanide is 3.00%, and the final concentration of sodium cyanide is 0.32%. The concentrations of sodium cyanide before and after gold leaching with sodium cyanide are statistically analyzed, and the consumption of sodium cyanide is calculated to be 26.09 kg / t.

[0038] This comparative example shows that when the dissolved oxygen concentration in the pulp is lower than 8 mg / L, the object of the present invention cannot be achieved.

[0039] In Examples 1 to 5 and Comparative Example 1, the unit of t in the consumption of sodium cyanide represents the total mass of copper-containing gold ore and cyanide residue of gold concentrate.

[0040] Comparative Example 2 The copper-containing gold ore is finely ground to P 80 = 74 μm, and after adjusting the pulp concentration to 40%, gold leaching with sodium cyanide is carried out according to the same process as in step (6) of Example 1.

[0041] The initial concentration of sodium cyanide is 3.00%, and the final concentration of sodium cyanide is 0.20%. The sodium cyanide concentrations before and after gold leaching with sodium cyanide are statistically analyzed, and the consumption of sodium cyanide is calculated to be 42.0 kg / t. In this comparative example, the unit "t" in the sodium cyanide consumption represents the mass of copper-bearing gold ore.

[0042] When comparing Example 1, Example 2, Example 3, Example 4, and Example 5 with Comparative Example 2 respectively, the reduction rates of sodium cyanide consumption reach 75.36%, 75.71%, 75.00%, 75.71%, and 75.71% respectively.

[0043] Therefore, when processed according to the method of the present invention, the reduction rate of sodium cyanide consumption reaches more than 75%.

[0044] Comparative Example 3 In step (5), K is taken as 1.4, 20.13 kg / t of ammonium chloride is added, the reaction temperature is controlled at 95 °C, and the copper leaching time is 24 h.

[0045] Other conditions are the same as in Example 1.

[0046] The initial concentration of sodium cyanide is 2.00%, and the final concentration of sodium cyanide is 0.21%. The sodium cyanide concentrations before and after gold leaching with sodium cyanide are statistically analyzed, and the consumption of sodium cyanide is calculated to be 26.85 kg / t.

[0047] In this example, since the reaction temperature is controlled at the upper limit of the range and the leaching time is at the upper limit of the range, but the value of K is lower than 1.5, the volatilization of ammonium salt leads to insufficient dosage, and the purpose of the present invention cannot be achieved.

[0048] Comparative Example 4 The cyanide residue of gold concentrate is ultrafine ground to P 80 = 20 μm, and after adjusting the pulp concentration to 40%, sodium cyanide gold leaching is carried out according to the same process as in step (6) of Example 1.

[0049] The initial concentration of sodium cyanide is 1%, and the final concentration of sodium cyanide is 0.32%. The sodium cyanide concentrations before and after gold leaching with sodium cyanide are statistically analyzed, and the consumption of sodium cyanide is calculated to be 10.2 kg / t. In this comparative example, the unit "t" in the sodium cyanide consumption represents the mass of cyanide residue of gold concentrate.

[0050] This comparative example shows that: during the cyanidation leaching process of cyanide residue of gold concentrate, the consumption of sodium cyanide is relatively small, and the main mineral consuming sodium cyanide is copper-bearing gold ore. Therefore, pre-treating copper-bearing gold ore and separating copper from the ore in advance through acid leaching and ammonia leaching processes is an effective method to reduce the consumption of sodium cyanide.

[0051] Note: During the reaction process of step (5), there is a problem of ammonium salt volatilization. The degree of ammonium salt volatilization is positively correlated with both the reaction temperature and the leaching time. Therefore, in the present invention, the addition amount of ammonium salt is determined by adjusting the K value. If the K value is not adjusted, the addition amount of ammonium salt may be too low or too high due to the changes in temperature and time parameters. If it is too low, the object of the present invention cannot be achieved (such as Comparative Example 3), and if it is too high, it will cause waste of ammonium salt.

[0052] In actual operation, the influence of the reaction temperature and the leaching time should be comprehensively considered. If the values of both the reaction temperature and the leaching time are large, the K value is adjusted to a larger value within its range; if the values of both the reaction temperature and the leaching time are small, the K value is adjusted to a smaller value within its range; if the values of the reaction temperature and the leaching time are both in the middle within their respective ranges or one is large and the other is small, the K value is adjusted to the middle value within its range or made to approach the middle value.

Claims

1. A method for reducing the consumption of sodium cyanide in copper-gold ore, characterized in that: The process includes the following steps: (1) Grind the gold concentrate cyanide slag to P 80 ≤30μm, and grind the copper-gold ore to P 80 ≤100μm; (2) The ultra-finely ground gold concentrate cyanide residue and the finely ground copper-gold ore are blended in proportion, and the effective sulfur content after blending is 18% to 25%; (3) The mixed product after ore blending is prepared into a slurry with a concentration of 10% to 30%; (4) introducing oxygen into the slurry, controlling the dissolved oxygen concentration in the slurry within a range of 9 to 15 mg / L, and reacting for 8 to 15 hours under stirring; (5) Adjust the pH value of the slurry to 10.5-11.5, add ammonium sulfate or ammonium chloride as ammonium salt, and leaching copper for 8-24 hours under stirring; (6) The slurry after copper leaching is subjected to solid-liquid separation; the obtained liquid is used to produce crude copper; and the obtained solid is used to adjust the slurry concentration and then leached gold using sodium cyanide.

2. The method for reducing the consumption of sodium cyanide in copper-gold ore as claimed in claim 1, characterized in that: In step (1), the gold concentrate cyanide slag is ultrafinely ground to P 80 ≤20μm.

3. The method for reducing the consumption of sodium cyanide in copper-gold ore as claimed in claim 1, characterized in that: In step (2), the effective sulfur content after ore blending is 20%-23%.

4. The method for reducing the consumption of sodium cyanide in copper-gold ore as claimed in claim 1, characterized in that: In step (4), the stirring linear velocity is ≥12 m / s.

5. The method for reducing the consumption of sodium cyanide in copper-gold ore as claimed in claim 1, characterized in that: In step (5), the reaction temperature is controlled at 60-95°C.

6. The method for reducing the consumption of sodium cyanide in copper-gold ore as claimed in claim 1, characterized in that: The method for calculating the amount of ammonium salt added in step (5) is as follows: ； Where: Q represents the amount of ammonium salt added per ton of gold concentrate cyanide slag and copper-gold ore, unit: kg / t; K represents the adjustment coefficient of ammonium salt addition, which is 1.5-2.5; M represents the relative molecular mass or relative atomic mass of the anion in the ammonium salt; N represents the molar ratio of cations to anions in the ammonium salt; P represents the mass ratio of copper-gold ore to gold concentrate cyanide slag; β represents the copper grade in copper-gold ore, unit: kg / t.

7. The method for reducing the consumption of sodium cyanide in copper-gold ore as claimed in claim 1, characterized in that: The liquid obtained from the solid-liquid separation in step (6) is subjected to an electrowinning process to produce crude copper.

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