A method for reducing sodium cyanide consumption in copper-gold ore

Abstract

The present invention discloses a method for reducing the consumption of sodium cyanide in copper-containing gold ore, and belongs to the technical field of hydrometallurgy. The copper-containing gold ore and the gold concentrate cyanide slag are mixed in a certain proportion and then pretreated. The acid generated in the pretreatment process reacts with the carbonate in the copper mineral to expose the copper mineral. After the ammonium salt is added, the copper in the copper mineral is complexed with ammonia. By solid-liquid separation, copper no longer enters the cyanide leaching system, thereby achieving the purpose of reducing the consumption of sodium cyanide. The process flow of the present invention is simple, the production cost is low, and it can effectively solve the problem of high sodium cyanide consumption in the cyanide leaching process of copper-containing gold ore. After treatment with the method of the present invention, the sodium cyanide consumption is reduced by more than 75%.

Description

Technical Field

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

[0002] Copper-bearing gold ores are difficult to process. During the cyanide leaching process, copper and cyanide complexation consumes large amounts of sodium cyanide, significantly increasing costs. Furthermore, the resulting copper-cyanide complex not only affects the gold leaching rate but also consumes significant amounts of acid during the barren solution treatment process.

[0003] On the other hand, gold smelting produces a large amount of cyanide slag, which is a hazardous solid waste. The cyanide slag contains Au, Ag, As, Cu, Pb, Zn, CN - The long-term storage of highly mobile valuable metal elements and toxic elements 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 invention patent application with publication number CN113025821A discloses "a comprehensive treatment method for resource utilization of cyanide tailings". It combines gold and copper concentrate, cyanide tailings, quartz stone, coal and other ingredients, and then undergoes high-temperature smelting. The cyanide in the cyanide tailings is destroyed by pyrolysis to generate carbon dioxide and nitrogen oxides. Compared with other cyanide tailings disposal methods, this method can reduce the cost of cyanide tailings treatment to a certain extent and realize the recovery of valuable metals such as gold, silver, and copper in cyanide tailings. However, this method is a high-temperature treatment method, and the energy consumption of the treatment process is relatively high. In addition, there is still the problem of copper and cyanide complexing and consuming a large amount of sodium cyanide.

[0004] Chinese invention patent application publication number CN108018418A discloses a "wet pretreatment method for sulfide-encapsulated refractory gold ore." This method involves wet pretreatment of encapsulated refractory gold ore to remove the gold encapsulation, thereby increasing the gold leaching rate. During the pretreatment process, the acid generated is neutralized with lime. While this improves the pretreatment reaction rate, the copper in the copper-bearing gold ore still consumes a large amount of sodium cyanide during the cyanide leaching process after pretreatment. 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-gold ore, so as to achieve the purpose of effectively reducing the consumption of sodium cyanide in copper-gold ore under the premise of recycling cyanide slag.

[0006] The technical solutions of the present invention are as follows:

[0007] A method for reducing the consumption of sodium cyanide in copper-gold ore comprises the following steps performed in sequence:

[0008] (1) Ultrafine grinding of gold concentrate cyanide slag to P 80 ≤30μm, and grind the copper-gold ore to P 80 ≤100μm;

[0009] (2) The ultrafinely ground gold concentrate cyanide residue and the finely ground copper-bearing gold ore are blended in proportion, and the effective sulfur content after blending is 18% to 25%;

[0010] (3) The mixed product after ore blending is prepared into a slurry with a concentration of 10% to 30%;

[0011] (4) introducing oxygen into the slurry, controlling the dissolved oxygen concentration in the slurry within the range of 9 to 15 mg / L, and reacting for 8 to 15 hours under stirring;

[0012] (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;

[0013] (6) The slurry after copper leaching is subjected to solid-liquid separation; the obtained liquid is used to produce crude copper; the obtained solid is used to adjust the slurry concentration and then use sodium cyanide to leach gold.

[0014] Preferably, in step (1), the gold concentrate cyanide slag is ultrafinely ground to P 80 ≤20μm.

[0015] Preferably, in step (2), the effective sulfur content after ore blending is 20%-23%.

[0016] Preferably, the stirring linear velocity in step (4) is ≥12 m / s.

[0017] Preferably, in step (5), the reaction temperature is controlled at 60-95°C.

[0018] Preferably, the method for calculating the amount of ammonium salt added in step (5) is as follows:

[0019] ;

[0020] Where: Q represents the amount of ammonium salt added per ton of gold concentrate cyanide residue and copper-gold ore, unit: kg / t;

[0021] K represents the adjustment coefficient of ammonium salt addition, which is 1.5-2.5;

[0022] M represents the relative molecular mass or relative atomic mass of the anion in the ammonium salt;

[0023] N represents the molar ratio of cations to anions in the ammonium salt;

[0024] P represents the mass ratio of copper-gold ore to gold concentrate cyanide slag;

[0025] β represents the copper grade in copper-gold ore, unit: kg / t.

[0026] Preferably, the liquid obtained by solid-liquid separation in step (6) is used to produce crude copper using an electrowinning process.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] First, the present invention utilizes the acid generated during the oxidation of gold concentrate cyanide residue to pretreat the carbonates and copper minerals in the copper-containing gold ore. Ammonium salts are then added to complex the copper with ammonia. This, through solid-liquid separation, reduces the reaction between copper and sodium cyanide, thereby reducing the sodium cyanide consumption of the copper-containing gold ore. Furthermore, according to the present invention, the gold concentrate cyanide residue undergoes ultrafine grinding and oxidation under high dissolved oxygen and high shear conditions. The resulting acid reacts with the carbonates in the finely ground copper-containing gold ore, fully exposing the copper minerals. The copper minerals react with the ammonium salt to form copper-ammonia complex ions, which, after solid-liquid separation, avoid contact with cyanide, thereby reducing sodium cyanide consumption during the subsequent sodium cyanide gold leaching process. Experiments have shown that treatment with the present method reduces sodium cyanide consumption by over 75%.

[0029] Second, according to the method of the present invention, the amount of ammonium salt added is related to the molecular weight of the anions in the ammonium salt, the molar ratio of cations to anions in the ammonium salt, the mass ratio of the copper-gold ore to the gold concentrate cyanide residue, and the copper grade in the copper-bearing gold ore. Through repeated experiments and exploration, the present invention has developed a calculation formula for the amount of ammonium salt added. With the help of this formula, the amount of ammonium salt added that meets the requirements of the present invention for reducing the sodium cyanide consumption of copper-bearing gold ore can be accurately calculated. DETAILED DESCRIPTION

[0030] The present invention is further described below with reference to the embodiments, comparative examples and experimental data.

[0031] The copper content (i.e., copper grade) of the copper-bearing gold ore used in the embodiment of the present invention is 8.6 kg / t, and the effective sulfur content is 1.2%; the effective sulfur content of the gold concentrate cyanide slag used in the embodiment of the present invention is 43.22%.

[0032] Example 1

[0033] (1) Ultrafine grinding of gold concentrate cyanide slag to P 80 =20μm, finely grind copper-gold ore to P 80 =74μm;

[0034] (2) The ultrafinely ground gold concentrate cyanide residue and the finely ground copper-bearing gold ore were blended in a mass ratio of 1:1. The effective sulfur content after blending was 22.21%;

[0035] (3) Adjust the slurry concentration of the mixed product after ore blending to 20%;

[0036] (4) Introduce oxygen into the slurry to control the dissolved oxygen concentration in the slurry to 10 mg / L; high-speed shear stirring, stirring linear speed 12 m / s; reaction time 12 h;

[0037] (5) The pH value of the pretreated pulp was adjusted to 11, and 28.76 kg / t of ammonium chloride (t here refers to the total mass of the copper-gold ore and the gold concentrate cyanide slag) was added to stir the pulp. The reaction temperature was controlled at 80 °C and the copper leaching time was 16 h.

[0038] Calculation process of ammonium chloride addition:

[0039] ;

[0040] Substituting M (the relative atomic mass of chlorine atoms is 35.5), N (the molar ratio of cations to anions in ammonium chloride is 1), P (the mass ratio of copper-bearing gold ore to gold concentrate cyanide residue is 1), β (the copper grade in the copper-bearing gold ore is 8.6 kg / t), and K = 2.0 into the above formula, Q = 28.76 kg / t. In this step, since the reaction temperature and leaching time are controlled near the middle of the range, K is taken as the middle of the range.

[0041] (6) The slurry after copper leaching is subjected to solid-liquid separation, and the liquid is electrolytically processed to produce crude copper; after the solid slurry concentration is adjusted to 40%, the pH value is adjusted to 11±0.5 with lime, and sodium cyanide is added to leaching gold. During the sodium cyanide leaching process, the sodium cyanide concentration is maintained at not less than 0.10%, and the cyanide leaching time is not less than 24 hours.

[0042] The initial sodium cyanide concentration was 1.00%, and the final sodium cyanide concentration was 0.31%. The sodium cyanide concentrations before and after gold leaching were calculated, and the sodium cyanide consumption was calculated to be 10.35 kg / t.

[0043] Example 2

[0044] In step (2), the ultrafinely ground gold concentrate cyanide residue and the finely ground copper-containing gold ore are blended in a mass ratio of 1.4:1, and the effective sulfur content after blending is 18.51%.

[0045] In step (5), the reaction temperature was controlled at 90°C and the copper leaching time was 8 hours. In this step, since the reaction temperature was controlled near the upper limit of the range but the leaching time was at the lower limit of the range, K was taken as the middle value of 2.0. In this embodiment, since P = 0.71, the amount of ammonium chloride added Q = 33.63 kg / t.

[0046] The other steps are the same as those in Example 1.

[0047] The initial sodium cyanide concentration was 1.00%, and the final sodium cyanide concentration was 0.32%. The sodium cyanide concentrations before and after gold leaching were calculated, and the sodium cyanide consumption was calculated to be 10.20 kg / t.

[0048] Example 3

[0049] In step (2), the ultrafinely ground gold concentrate cyanide residue and the finely ground copper-gold ore are blended in a mass ratio of 0.8:1, and the effective sulfur content after blending is 24.39%.

[0050] In step (5), the reaction temperature was controlled at 62°C, and the copper leaching time was 24 hours. In this step, since the reaction temperature was controlled near the lower limit of the range, but the leaching time was at the upper limit of the range, K was taken as the middle value of 2.0. In this embodiment, since P = 1.25, the amount of ammonium chloride added Q = 25.56 kg / t.

[0051] The other steps are the same as those in Example 1.

[0052] The initial sodium cyanide concentration was 1.00%, and the final sodium cyanide concentration was 0.30%. The sodium cyanide concentrations before and after gold leaching were calculated, and the sodium cyanide consumption was calculated to be 10.50 kg / t.

[0053] Example 4

[0054] In step (5), 35.48 kg / t of ammonium sulfate was added instead of ammonium chloride.

[0055] According to the following formula:

[0056] ;

[0057] Substituting M=32+16×4=96, N=2, P=1, β=8.6, and K=2.0 into the above formula, Q=35.48.

[0058] The other steps are the same as those in Example 1.

[0059] The initial sodium cyanide concentration was 1.00%, and the final sodium cyanide concentration was 0.32%. The sodium cyanide concentrations before and after gold leaching were calculated, and the sodium cyanide consumption was calculated to be 10.2 kg / t.

[0060] Example 5

[0061] Step (4) controls the dissolved oxygen concentration in the slurry to 9 mg / L.

[0062] The other steps are the same as those in Example 1.

[0063] The initial sodium cyanide concentration was 1.00%, and the final sodium cyanide concentration was 0.32%. The sodium cyanide concentrations before and after gold leaching were calculated, and the sodium cyanide consumption was calculated to be 10.2 kg / t.

[0064] Comparative Example 1

[0065] Step (4) controls the dissolved oxygen concentration in the slurry to 8 mg / L.

[0066] The other steps are the same as those in Example 1.

[0067] The initial sodium cyanide concentration was 3.00%, and the final sodium cyanide concentration was 0.32%. The sodium cyanide concentrations before and after gold leaching were calculated, and the sodium cyanide consumption was calculated to be 26.09 kg / t.

[0068] This comparative example shows that when the dissolved oxygen concentration in the slurry is lower than 8 mg / L, the purpose of the present invention cannot be achieved.

[0069] In Examples 1 to 5 and Comparative Example 1, the unit t in the sodium cyanide consumption represents the total mass of the copper-gold ore and the gold concentrate cyanide residue.

[0070] Comparative Example 2

[0071] Fine grinding of copper-gold ore to P 80 =74 μm, and after adjusting the pulp concentration to 40%, sodium cyanide gold leaching was carried out according to the same process as step (6) of Example 1.

[0072] The initial sodium cyanide concentration was 3.00%, and the final sodium cyanide concentration was 0.20%. The sodium cyanide concentrations before and after gold leaching were calculated, and the sodium cyanide consumption was calculated to be 42.0 kg / t. In this comparative example, the unit "t" in sodium cyanide consumption represents the mass of the copper-gold ore.

[0073] Comparing Example 1, Example 2, Example 3, Example 4 and Example 5 with Comparative Example 2, respectively, the reduction rates of sodium cyanide consumption reached 75.36%, 75.71%, 75.00%, 75.71% and 75.71%, respectively.

[0074] Therefore, according to the method of the present invention, the consumption of sodium cyanide is reduced by more than 75%.

[0075] Comparative Example 3

[0076] 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.

[0077] Other aspects are the same as those of the first embodiment.

[0078] The initial sodium cyanide concentration was 2.00%, and the final sodium cyanide concentration was 0.21%. The sodium cyanide concentrations before and after gold leaching were calculated, and the sodium cyanide consumption was calculated to be 26.85 kg / t.

[0079] In this embodiment, 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 ammonium salt volatilizes and the dosage is insufficient, and the purpose of the present invention cannot be achieved.

[0080] Comparative Example 4

[0081] The gold concentrate cyanide slag is ultra-finely ground to P80 =20 μm, and after adjusting the pulp concentration to 40%, sodium cyanide gold leaching was carried out according to the same process as step (6) of Example 1.

[0082] The initial sodium cyanide concentration was 1%, and the final sodium cyanide concentration was 0.32%. The sodium cyanide concentrations before and after gold leaching were calculated, and the sodium cyanide consumption was calculated to be 10.2 kg / t. In this comparative example, the unit "t" in sodium cyanide consumption represents the mass of gold concentrate cyanide residue.

[0083] This comparative example demonstrates that sodium cyanide consumption is relatively low during the cyanide leaching of gold concentrate residue, with copper-bearing gold ore being the primary consumer. Therefore, pre-treating copper-bearing gold ore and separating copper from the ore through acid and ammonia leaching processes is an effective method for reducing sodium cyanide consumption.

[0084] Note: During the reaction of step (5), the ammonium salt volatilizes, and the degree of ammonium salt volatilization is positively correlated with both the reaction temperature and the leaching time. Therefore, the present invention determines the amount of ammonium salt added by adjusting the K value. If the K value is not adjusted, the amount of ammonium salt added may be too low or too high due to changes in temperature and time parameters. If the K value is too low, the purpose of the present invention cannot be achieved (such as in Comparative Example 3), while if the K value is too high, the ammonium salt will be wasted.

[0085] In actual operation, the effects of reaction temperature and leaching time should be comprehensively considered. If both the reaction temperature and leaching time are large, adjust the K value to the larger value within their ranges. If both the reaction temperature and leaching time are small, adjust the K value to the smaller value within their ranges. If both the reaction temperature and leaching time are in the middle of their respective ranges, or one is larger and the other is smaller, adjust the K value to the middle value within their ranges or close to 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) Ultrafine grinding of gold concentrate cyanide slag to P 80 ≤30μm, and grind the copper-gold ore to P 80 ≤100μm; (2) The ultrafinely ground gold concentrate cyanide residue and the finely ground copper-bearing 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 the 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; the obtained solid is used to adjust the slurry concentration and then leaching gold with sodium cyanide; The calculation method for 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 residue 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.

2. The method for reducing the consumption of sodium cyanide in copper-gold ore according to claim 1, wherein: 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 according to claim 1, wherein: 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, wherein: The stirring linear velocity in step (4) is ≥12 m / s.

5. The method for reducing the consumption of sodium cyanide in copper-gold ore according to claim 1, wherein: 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 according to claim 1, wherein: The liquid obtained from the solid-liquid separation in step (6) is subjected to an electrolytic deposition process to produce crude copper.

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