A kind of gold and silver extracting agent and preparation method thereof

Abstract

The present invention provides a gold and silver extractant and a preparation method thereof, and relates to the technical field of hydrometallurgy and mineral processing. The present invention mixes cyanate and ferrous salt to obtain a mixture, roasts the mixture to obtain a roasted synthetic agent; mixes the roasted synthetic agent with an iron salt to obtain a gold and silver extractant; the iron salt is one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide; the mass ratio of the roasted synthetic agent to the iron salt is 1:(0.002-0.1). The present invention can significantly shorten the leaching time and improve the leaching efficiency without affecting the gold and silver extraction effect by adding one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide to the synthesized gold and silver extractant.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy and mineral processing, and in particular to a gold and silver extractant and a preparation method thereof. Background Art

[0002] At present, cyanidation is still the mainstream method for extracting gold and silver. However, cyanide is highly toxic and poses a serious threat to the safety of the ecological environment. With the increasing global demand for ecological environmental protection, non-toxic or low-toxic, environmentally friendly non-cyanide gold and silver extractants have become the focus of more and more researchers and technicians at home and abroad. They are trying to develop new environmentally friendly and efficient extractants to replace cyanide to extract gold and silver.

[0003] The inventor previously disclosed a method for preparing a gold and silver extractant (authorization number ZL202110530006.X). This method uses cyanate and ferrous salt as raw materials, and synthesizes a low-toxic and environmentally friendly gold and silver extractant under the conditions of a mass ratio of cyanate to ferrous salt of 3:0.5 to 3:2, air atmosphere, heating rate of 5℃ / min to 20℃ / min, roasting temperature of 600℃ to 750℃, and insulation time of 0.5h to 2h. The raw materials for the synthesis of the extractant are low in price, the synthesis process is simple, and it has strong adaptability to ores. However, when the gold and silver extractant is actually leached from gold (silver) ore, the solution potential during the leaching process is only 190 to 220mV, the required leaching time is 24 to 36h, and the leaching efficiency is low. Summary of the invention

[0004] The object of the present invention is to provide a gold and silver extractant and a preparation method thereof, which can improve the solution potential of a leaching system and improve the leaching efficiency of the gold and silver extractant.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a gold and silver extractant, comprising the following steps:

[0007] Mixing cyanate and ferrous salt to obtain a mixture, and roasting the mixture to obtain a roasted synthetic agent;

[0008] The roasted synthetic agent is mixed with iron salt to obtain a gold and silver extractant;

[0009] The iron salt is one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide; the mass ratio of the roasting synthesis agent to the iron salt is 1:(0.002-0.1).

[0010] Preferably, the mass ratio of the roasting synthesis agent to the iron salt is 1:0.005, 1:0.01, 1:0.05, 1:0.1 or 1:0.006.

[0011] Preferably, the cyanate is sodium cyanate or potassium cyanate; the ferrous salt is sodium ferrocyanide, potassium ferrocyanide, ferrous chloride, ferrous nitrate or ferrous sulfate.

[0012] Preferably, the mass ratio of the cyanate to the ferrous salt is 3:(0.5-2).

[0013] Preferably, the mass ratio of the cyanate to the ferrous salt is 4:1.

[0014] Preferably, the calcination temperature is 600-750° C., and the holding time is 0.5-2 h; the calcination is carried out in an air atmosphere.

[0015] Preferably, the calcination temperature is 700° C. and the holding time is 1 hour.

[0016] Preferably, the heating rate to the calcination temperature is 5 to 20° C. / min.

[0017] Preferably, the heating rate to the calcination temperature is 15°C / min.

[0018] The present invention provides a gold and silver extractant prepared by the preparation method described in the above scheme.

[0019] The invention provides a preparation method of a gold and silver extractant, comprising the following steps: mixing cyanate and ferrous salt to obtain a mixture, and roasting the mixture to obtain a roasted synthetic agent; mixing the roasted synthetic agent with an iron salt to obtain the gold and silver extractant; the iron salt is one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide; and the mass ratio of the roasted synthetic agent to the iron salt is 1:(0.002-0.1).

[0020] Potassium / sodium ferrocyanide and potassium / sodium ferrocyanide are easily soluble in the alkaline leaching solution system and form a stable and reversible oxidation-reduction electrode Fe(CN)6 3- / Fe(CN)6 4- , significantly improving the solution potential, thereby acting as a catalytic oxidant to accelerate the oxidation and dissolution of gold and silver. In addition, compared with common oxidants such as hydrogen peroxide, sodium hypochlorite, ozone, etc., potassium / sodium ferrocyanide and potassium / sodium ferrocyanide are low in price, low in toxicity and environmentally friendly, have milder oxidizing properties, will not oxidize the roasting synthesis agent, and the two can coexist compatibly. The present invention can significantly shorten the leaching time and improve the leaching efficiency without affecting the gold and silver extraction effect by adding one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide to the synthesized gold and silver extractant. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a preparation flow chart of the gold and silver extractant of the present invention. DETAILED DESCRIPTION

[0022] The present invention provides a method for preparing a gold and silver extractant, comprising the following steps:

[0023] Mixing cyanate and ferrous salt to obtain a mixture, and roasting the mixture to obtain a roasted synthetic agent;

[0024] The roasted synthetic agent is mixed with iron salt to obtain a gold and silver extractant;

[0025] The iron salt is one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide; the mass ratio of the roasting synthesis agent to the iron salt is 1:(0.002-0.1).

[0026] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known in the art.

[0027] The invention mixes cyanate and ferrous salt to obtain a mixture, and roasts the mixture to obtain a roasted synthetic agent.

[0028] In the present invention, the cyanate is preferably sodium cyanate or potassium cyanate, more preferably sodium cyanate; the ferrous salt is preferably sodium ferrocyanide, potassium ferrocyanide, ferrous chloride, ferrous nitrate or ferrous sulfate, more preferably potassium ferrocyanide. In the present invention, the mass ratio of the cyanate to the ferrous salt is preferably 3:(0.5-2), more preferably 4:1.

[0029] The present invention has no special requirements for the mixing process, as long as the cyanate and the ferrous salt can be uniformly mixed. Before the mixing, the present invention preferably grinds the cyanate and the ferrous salt.

[0030] In the present invention, the calcination is preferably carried out in an air atmosphere; the calcination temperature is preferably 600-750°C, more preferably 650-720°C, and further preferably 700°C; the holding time is preferably 0.5-2h, and more preferably 1h. In the present invention, the heating rate to the calcination temperature is preferably 5-20°C / min, more preferably 10-15°C / min, and further preferably 15°C / min. In the calcination process of the present invention, cyanate and ferrous salt react chemically to generate a gold-silver leached phase.

[0031] After the calcination is completed, the method is preferably cooled naturally to room temperature, and the calcined product is ground into powder to obtain a calcined synthetic agent.

[0032] After obtaining the roasted synthetic agent, the present invention mixes the roasted synthetic agent with iron salt to obtain a gold and silver extractant.

[0033] In the present invention, the iron salt is one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide; when the iron salt includes multiple types of the above substances, the present invention has no special requirements on the ratio of each iron salt, and any ratio is acceptable. In an embodiment of the present invention, when multiple iron salts are included, the ratio of each iron salt is an equal mass ratio.

[0034] In the present invention, only potassium ferrocyanide or sodium ferrocyanide can be added. During the leaching process, potassium ferrocyanide or sodium ferrocyanide is easily oxidized by oxygen to form Fe(CN)6 3- / Fe(CN)6 4- Redox couple. Any of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide can produce Fe(CN)6 3- / Fe(CN)6 4- The redox couple significantly increases the potential of the solution, thus acting as a catalytic oxidant to accelerate the oxidation and dissolution of gold and silver. Compared with common oxidants such as hydrogen peroxide, sodium hypochlorite, and ozone, potassium / sodium ferrocyanide and potassium / sodium ferrocyanide are inexpensive, low-toxic and environmentally friendly, have milder oxidizing properties, and will not oxidize the roasting synthesis agent. The two can coexist compatibly.

[0035] In the present invention, the mass ratio of the calcined synthesis agent to the iron salt is 1:(0.002-0.1), preferably 1:0.005, 1:0.01, 1:0.05, 1:0.1, 1:0.006.

[0036] The present invention has no special requirements on the mixing process of the roasting synthesis agent and the iron salt, and a mixing process well known in the art can be adopted.

[0037] Figure 1 FIG. 5 is a flow chart of the preparation of the gold and silver extractant of the present invention. Figure 1 As shown, the present invention mixes cyanate and ferrous salt to obtain a mixture, roasts the mixture, cools it, crushes it and grinds it to obtain a roasted synthetic agent; and mixes the roasted synthetic agent with ferric salt to obtain a gold and silver extractant.

[0038] The present invention provides a gold and silver extractant prepared by the preparation method described in the above scheme. By adding one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide to the synthesized gold and silver extractant, the leaching time can be significantly shortened and the leaching efficiency can be improved without affecting the gold and silver extraction effect.

[0039] The gold and silver extractant and the preparation method thereof provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0040] The raw materials used in the following examples and comparative examples are all sulfide-type gold concentrates, and their chemical compositions (wt.%) are shown in Table 1.

[0041] Table 1 Chemical composition of sulfide gold concentrate (wt.%)

[0042]

[0043] *Unit: g / t

[0044] Note: Since the test methods for the content of each component are not exactly the same, the sum of the components of sulfide gold concentrate is greater than 100%.

[0045] The preparation method of the roasted synthetic agent used in the following examples and comparative examples is as follows: Sodium cyanate and potassium ferrocyanide are ground and mixed at a mass ratio of 4:1, and then placed in a high-temperature crucible for roasting. The roasting conditions are air atmosphere, a heating rate of 15°C / min, a roasting temperature of 700°C, and a heat preservation time of 1h. After the roasting is completed, the synthetic material is placed in the air to cool naturally, and ground into powder to obtain a roasted synthetic agent.

[0046] Comparative Example 1

[0047] The sulfide gold concentrate is finely ground to -74μm, accounting for 85%, and then mixed with water to form a slurry (the mass ratio of water to the finely ground gold concentrate is 2.5:1), and then a roasting synthesis agent accounting for 0.2wt.% of water is added to the slurry, and dilute sulfuric acid or sodium hydroxide is added to adjust the initial pH value to 11, and then leached for 24 hours under air atmosphere, temperature 25°C and stirring speed 350r / min. During the leaching process, the solution potential varies in the range of 190 to 220mV.

[0048] During the leaching process, the leaching solution was taken at regular intervals to test the gold concentration. The change of gold leaching rate over time is shown in Table 2.

[0049] Table 2 Changes of gold leaching rate over time in comparative example 1

[0050] Leaching time 4h 8h 12h 16h 18h 20h 22h 24h Gold leaching rate 53.6％ 72.1％ 84.5％ 89.2％ 93.1％ 95.4％ 96.2％ 98.4％

[0051] The results of multiple parallel experiments using the above steps are as follows: when the concentration of the roasting synthesis agent is 0.2wt.%, the gold leaching rate can reach 98.4% after leaching for 24 hours.

[0052] Example 1

[0053] (1) The mass ratio of the roasting synthesis agent and potassium ferrocyanide is 1:0.005, and the mixture is evenly mixed to prepare a gold and silver extraction agent;

[0054] (2) The sulfide gold concentrate was finely ground to -74 μm, accounting for 85%, and then mixed with water to form a slurry (the mass ratio of water to the finely ground gold concentrate was 2.5:1), and then a gold and silver extractant accounting for 0.2 wt.% of water was added to the slurry, and dilute sulfuric acid or sodium hydroxide was added to adjust the initial pH value to 11, and then leached for 24 hours under air atmosphere, temperature 25°C and stirring speed 350 r / min. During the leaching process, the solution potential varied in the range of 250 to 340 mV.

[0055] (3) During the leaching process, the leaching solution was taken at regular intervals to test the gold concentration. The change of gold leaching rate over time is shown in Table 3.

[0056] Table 3 Variation of gold leaching rate over time in Example 1

[0057] Leaching time 4h 8h 12h 16h 18h 20h 22h 24h Gold leaching rate 58.6％ 80.1％ 87.7％ 94.3％ 98.3％ 98.3％ 98.2％ 98.5％

[0058] According to the above steps, compared with comparative example 1, the overall potential of the leaching solution is increased by about 60 to 120 mV; the gold leaching rate can reach 98.3% after leaching for 18 hours. When the gold leaching rate is basically the same, the leaching time is shortened by 6 hours.

[0059] Example 2

[0060] (1) The roasting synthesis agent and potassium ferrocyanide are mixed in a mass ratio of 1:0.01 to prepare a gold and silver extraction agent;

[0061] (2) The sulfide gold concentrate was finely ground to -74 μm accounting for 85%, and then mixed with water to form a slurry (the mass ratio of water to the finely ground gold concentrate was 2.5:1), and then a gold and silver extractant accounting for 0.2 wt.% of water was added to the slurry and dilute sulfuric acid or sodium hydroxide was added to adjust the initial pH value to 11, and then leached for 24 hours under air atmosphere, temperature 25°C and stirring speed 350 r / min. During the leaching process, the solution potential varied in the range of 300 to 380 mV.

[0062] During the leaching process, the leaching solution was taken at regular intervals to test the gold concentration. The change of gold leaching rate over time is shown in Table 4.

[0063] Table 4 Changes of gold leaching rate over time in Example 2

[0064] Leaching time 4h 8h 12h 16h 18h 20h 22h 24h Gold leaching rate% 70.5 89.7 98.4 98.3 98.2 98.3 98.5 98.6

[0065] According to the above steps, compared with comparative example 1, the overall potential of the leaching solution increased by about 110-160 mV; after 12 hours of leaching, the gold leaching rate could reach 98.4%. When the gold leaching rate was basically the same, the leaching time was shortened by 12 hours.

[0066] Example 3

[0067] (1) The roasting synthesis agent and potassium ferrocyanide are mixed in a mass ratio of 1:0.05 to prepare a gold and silver extraction agent;

[0068] (2) The sulfide gold concentrate was finely ground to -74 μm, accounting for 85%, and then mixed with water to form a slurry (the mass ratio of water to the finely ground gold concentrate was 2.5:1), and then a gold and silver extractant accounting for 0.2 wt.% of water was added to the slurry and dilute sulfuric acid or sodium hydroxide was added to adjust the initial pH value to 11, and then leached for 24 hours under air atmosphere, temperature 25°C and stirring speed 350 r / min. During the leaching process, the solution potential varied in the range of 350 to 490 mV.

[0069] (3) During the leaching process, the leaching solution was taken at regular intervals to test the gold concentration. The change of gold leaching rate over time is shown in Table 5.

[0070] Table 5 Changes of gold leaching rate over time in Example 3

[0071] Leaching time 4h 6h 8h 12h 16h 18h 20h 22h 24h Gold leaching rate% 85.5 90.2 98.3 98.2 98.3 98.2 98.4 98.4 98.6

[0072] According to the above steps, compared with comparative example 1, the overall potential of the leaching solution increased by about 160-270 mV; the gold leaching rate could reach 98.3% after 8 hours of leaching. When the gold leaching rate was basically the same, the leaching time was shortened by 16 hours.

[0073] Example 4

[0074] (1) The roasting synthesis agent and potassium ferrocyanide are mixed in a mass ratio of 1:0.1 to prepare a gold and silver extraction agent;

[0075] (2) The sulfide gold concentrate was finely ground to -74 μm, accounting for 85%, and then mixed with water to form a slurry (the mass ratio of water to the finely ground gold concentrate was 2.5:1), and then a gold and silver extractant accounting for 0.2 wt.% of water was added to the slurry, and dilute sulfuric acid or sodium hydroxide was added to adjust the initial pH value to 11, and then leached for 24 hours under air atmosphere, temperature 25°C and stirring speed 350 r / min. During the leaching process, the solution potential varied in the range of 360 to 490 mV.

[0076] (3) During the leaching process, the leaching solution was taken at regular intervals to test the gold concentration. The change of gold leaching rate over time is shown in Table 6.

[0077] Table 6 Changes of gold leaching rate over time in Example 4

[0078] Leaching time 4h 6h 8h 12h 16h 18h 20h 22h 24h Gold leaching rate% 87.1 91.5 98.6 98.4 98.2 98.6 98.5 98.6 98.6

[0079] According to the above steps, compared with comparative example 1, the overall potential of the leaching solution is increased by about 170-270 mV; the gold leaching rate can reach 98.6% after leaching for 8 hours. When the gold leaching rate is basically the same, the leaching time is shortened by 16 hours.

[0080] Example 5

[0081] (1) roasting a synthetic agent, potassium ferrocyanide and potassium ferrocyanide in a mass ratio of 1:0.003:0.003, and mixing them uniformly to prepare a gold and silver extracting agent;

[0082] (2) The sulfide gold concentrate was finely ground to -74 μm, accounting for 85%, and then mixed with water to form a slurry (the mass ratio of water to the finely ground gold concentrate was 2.5:1), and then a gold and silver extractant accounting for 0.2 wt.% of water was added to the slurry, and dilute sulfuric acid or sodium hydroxide was added to adjust the initial pH value to 11, and then leached for 24 hours under air atmosphere, temperature 25°C and stirring speed 350 r / min. During the leaching process, the solution potential varied in the range of 240 to 310 mV.

[0083] (3) During the leaching process, the leaching solution was taken at regular intervals to test the gold concentration. The change of gold leaching rate over time is shown in Table 7.

[0084] Table 7 Changes of gold leaching rate over time in Example 5

[0085] Leaching time 4h 8h 12h 16h 18h 20h 22h 24h Gold leaching rate 57.2％ 76.8％ 86.9％ 89.1％ 94.3％ 98.4％ 98.2％ 98.7％

[0086] According to the above steps, compared with comparative example 1, the overall potential of the leaching solution increased by about 50-90 mV; after leaching for 20 hours, the gold leaching rate could reach 98.4%. When the gold leaching rate was basically the same, the leaching time was shortened by 4 hours.

[0087] Example 6

[0088] (1) roasting a synthetic agent, potassium ferrocyanide and potassium ferrocyanide in a mass ratio of 1:0.03:0.003, and mixing them uniformly to prepare a gold and silver extracting agent;

[0089] (3) The sulfide gold concentrate was finely ground to -74 μm, accounting for 85%, and then mixed with water to form a slurry (the mass ratio of water to the finely ground gold concentrate was 2.5:1), and then a gold and silver extractant accounting for 0.2 wt.% of water was added to the slurry, and dilute sulfuric acid or sodium hydroxide was added to adjust the initial pH value to 11, and then leached for 24 hours under air atmosphere, temperature 25°C and stirring speed 350 r / min. During the leaching process, the solution potential varied in the range of 370 to 460 mV.

[0090] (4) During the leaching process, the leaching solution was taken at regular intervals to test the gold concentration. The change of gold leaching rate over time is shown in Table 8.

[0091] Table 8 Changes of gold leaching rate over time in Example 6

[0092] Leaching time 2h 4h 6h 8h 10h 12h 20h 24h Gold leaching rate 60.2％ 89.3％ 98.1％ 98.3％ 98.2％ 98.0％ 98.6％ 98.5％

[0093] According to the above steps, compared with comparative example 1, the overall potential of the leaching solution increased by about 180-240 mV; the gold leaching rate reached 98.1% after 6 hours of leaching, and the leaching time was shortened by 18 hours when the gold leaching rate was basically the same. And the effect was better than that of using potassium ferrocyanide alone.

[0094] It can be seen from the above embodiments and comparative examples that the present invention can significantly shorten the leaching time and improve the leaching efficiency without affecting the gold and silver extraction effect by adding one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide to the synthesized gold and silver extractant.

[0095] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a gold and silver extractant, characterized in that: The following steps are involved: Mixing cyanate and ferrous salt to obtain a mixture, and roasting the mixture to obtain a roasted synthetic agent; The roasted synthetic agent is mixed with iron salt to obtain a gold and silver extractant; The iron salt is one or more of potassium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and sodium ferrocyanide; the mass ratio of the roasting synthesis agent to the iron salt is 1:(0.002-0.1).

2. The preparation method according to claim 1, characterized in that: The mass ratio of the calcined synthetic agent to the iron salt is 1:0.005, 1:0.01, 1:0.05, 1:0.1 or 1:0.

006.

3. The preparation method according to claim 1, characterized in that: The cyanate is sodium cyanate or potassium cyanate; the ferrous salt is sodium ferrocyanide, potassium ferrocyanide, ferrous chloride, ferrous nitrate or ferrous sulfate.

4. The preparation method according to claim 3, characterized in that: The mass ratio of the cyanate to the ferrous salt is 3:(0.5-2).

5. The preparation method according to claim 4, characterized in that: The mass ratio of the cyanate to the ferrous salt is 4:

1.

6. The preparation method according to claim 1, characterized in that: The calcination temperature is 600-750° C., and the heat preservation time is 0.5-2 hours; the calcination is carried out in an air atmosphere.

7. The preparation method according to claim 6, characterized in that: The calcination temperature is 700° C. and the heat preservation time is 1 hour.

8. The preparation method according to claim 6, characterized in that: The heating rate to the calcination temperature is 5 to 20°C / min.

9. The preparation method according to claim 8, characterized in that: The heating rate to the calcination temperature is 15°C / min.

10. The gold and silver extractant prepared by the preparation method according to any one of claims 1 to 9.

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