Environmentally friendly gold extraction agent, preparation method and application thereof

Abstract

The present invention discloses an environmentally friendly gold extraction agent and its preparation method and application, comprising the following steps: (1) selecting cyanate, humate, and cuprous salt as raw materials and thoroughly mixing them; (2) placing the mixed materials in a porcelain boat and roasting them in a muffle furnace; (3) after roasting, exposing the materials to air and naturally cooling them to room temperature; (4) after complete cooling, grinding the resultant into powder in a mortar to obtain the environmentally friendly gold extraction agent. The gold extraction agent synthesized by the present invention is low-toxic and environmentally friendly. No toxic gases or harmful waste residues are generated during the production process. The roasting time is short, which is conducive to energy conservation. The raw materials used are inexpensive, and the agent consumption is lower than that of sodium cyanide, which can improve the economic benefits of large-scale industrial production. In addition, the gold extraction agent can be applied to a variety of gold mines, and for some gold mines, its gold leaching rate is slightly higher than that of sodium cyanide.

Description

Technical Field

[0001] The invention belongs to the field of gold production and chemical industry, and particularly relates to an environmentally friendly gold extracting agent and a preparation method and application thereof. Background Art

[0002] Gold, a soft, golden, corrosion-resistant precious metal, plays a vital role in the jewelry, electronics, modern communications, aerospace, and other industries. While global demand for gold has been declining annually, China's demand for gold, particularly for gold jewelry, has not declined but has actually grown significantly. Currently, the most popular gold leaching process is cyanide leaching. Cyanide leaching offers advantages such as simplicity, low production costs, wide applicability to a wide range of gold deposits, and high leaching rates. However, cyanide is a highly toxic substance, posing significant risks to both the environment and human health. In recent years, my country has enacted relevant laws and regulations to restrict cyanide leaching, necessitating the development of non-toxic or low-toxic gold extraction agents.

[0003] For example, Chinese patent application number CN113337731B discloses a "method for preparing a gold and silver extractant." Cyanate and ferrous salt are first mixed and then calcined in a high-temperature crucible. The resulting molten mixture is poured from the crucible while still hot and allowed to cool naturally in air before being ground into powder to produce the gold and silver extractant. The main drawback of this method is that the ferrous salt used as a raw material is prohibitively expensive.

[0004] Chinese patent application CN109957664B discloses an "environmentally friendly gold extraction agent and its preparation method." The method involves uniformly mixing a certain amount of sodium humate, soda ash, and urea, placing the mixture in a reactor, and heating it to 650-750°C for 4-5 hours. After the reaction is complete, the mixture is cooled and a gold leaching activator is added to obtain the environmentally friendly gold extraction agent, wherein the gold leaching activator is a lead salt. However, the main drawback of this method is that the reaction time is too long, resulting in significant energy consumption.

[0005] Chinese patent publication number CN105671312A discloses an "environmentally friendly gold and silver leaching agent and its preparation method." The process involves adding sodium cyanate, sodium chloride, carbonamide, hematite, tetrasodium hexacyanoferrate, soda, and sodium thiosulfate in a blender according to proportion, stirring evenly, then placing the mixture in a stainless steel reactor for a high-temperature reaction. The mixture is then discharged, cooled, and crushed in a crusher. After passing product inspection, the finished product is weighed and packaged. The main drawbacks of this method are the excessive number of synthetic raw materials, which can lead to side reactions and difficulty in control. Summary of the Invention

[0006] The present invention addresses the above-mentioned technical problems and provides an environmentally friendly gold extraction agent, its preparation method, and its application. This gold extraction agent is low-toxic and environmentally friendly. The production process produces no toxic gases or hazardous waste residues, and the roasting time is short, which contributes to energy conservation. The raw materials used are inexpensive, and the agent consumption is lower than that of sodium cyanide, which can improve the economic benefits of large-scale industrial production. Furthermore, the gold extraction agent is applicable to a variety of gold mines, and for some gold mines, its gold leaching rate is slightly higher than that of sodium cyanide.

[0007] In order to achieve the above purpose, the technical solution of the present invention is:

[0008] An environmentally friendly gold extracting agent comprises raw materials including 70-80 parts of cyanate, 20-30 parts of humate and 5-10 parts of cuprous salt; the agent is prepared by a roasting synthesis process.

[0009] The cyanate includes at least one of sodium cyanate, potassium cyanate and ammonium cyanate; the humate includes at least one of sodium humate, potassium humate and calcium humate; and the cuprous salt includes at least one of cuprous chloride, cuprous bromide, cuprous nitrate and cuprous sulfate.

[0010] More preferably, the cyanate is 70 parts, the humate is 20 parts, and the cuprous salt is 10 parts. Even more preferably, the raw materials and weight parts are 70 parts of sodium cyanate, 20 parts of sodium humate, and 10 parts of cuprous chloride.

[0011] The roasting synthesis process conditions are: air atmosphere, roasting temperature of 500-700 DEG C, and roasting time of 10-60 minutes.

[0012] More preferably, in step (2), the calcination synthesis process is: air atmosphere, calcination temperature 600° C., and calcination time 20 min.

[0013] Finally, the calcined product is ground into powder.

[0014] The environmentally friendly gold extracting agent of the present invention is used for leaching gold ore.

[0015] Leaching conditions: liquid-solid ratio 2:1-5:1, gold extraction agent concentration 1-5 kg / t, pH 9-12, rotation speed 300-600 rpm, leaching time 12-48 h, leaching temperature 20℃-70℃.

[0016] Further preferred is a liquid-solid ratio of 3:1, a gold extraction agent concentration of 2 kg / t, a pH of 12, a rotation speed of 400 rpm, a leaching time of 24 h, and a leaching temperature of 25°C.

[0017] The raw materials of the environmentally friendly gold extraction agent prepared by the present invention are cyanate, humate, and cuprous salt. Cyanate provides a cyano group, and humate provides a long carbon chain. During the roasting process, the cyanate group is "grafted" onto the long carbon chain, making the cyano group more stable and less likely to dissociate into free cyanide ions. Cuprous salt promotes the polymerization of sodium cyanate and humate, and can make the bond between the cyano group and the carbon chain more firm, further suppressing the generation of free cyanide ions.

[0018] Advantages of the present invention include:

[0019] 1. The gold extraction agent provided by the present invention can form a complex with gold, accelerate the dissolution of gold, and improve the gold leaching rate.

[0020] 2. The production process of the gold extraction agent provided by the present invention is safe and environmentally friendly, and no toxic gases or harmful waste residues are generated.

[0021] 3. The gold extraction agent provided by the present invention has a short roasting time during the production process, which is beneficial to energy conservation.

[0022] 4. The raw materials used in the gold extraction agent provided by the present invention are low in price, and the agent consumption is lower than that of sodium cyanide, which can improve the economic benefits in large-scale industrial production.

[0023] 5. The gold extraction agent provided by the present invention is highly applicable to a variety of gold mines, and for some gold mines, the gold leaching rate is slightly higher than that of sodium cyanide. DETAILED DESCRIPTION

[0024] The following examples are intended to further illustrate the present invention, but are not intended to limit the present invention.

[0025] The gold leaching experiments in Examples 1 to 3 were all conducted using sulfide gold ore with a grade of 11.75 g / t.

[0026] Example 1: A gold extraction agent was prepared according to the raw material ratios in Table 1, and its leaching performance was tested. Calcination conditions were: air atmosphere, 600°C, and 20 min. Leaching conditions were: liquid-to-solid ratio of 3:1, gold extraction agent concentration of 2 kg / t, pH 12, rotation speed of 400 rpm, leaching temperature of 25°C, and leaching time of 24 h. The synthetic raw material ratios and gold leaching yields are shown in Table 1.

[0027] Table 1 Effect of raw material ratio on gold leaching with low-toxic and environmentally friendly gold extraction agent

[0028]

[0029] From the above results, it can be seen that when the content of sodium cyanate is 70 parts, sodium humate is 20 parts, and cuprous chloride is 10 parts, the gold leaching rate is the highest, reaching 94.01%.

[0030] Example 2: A gold extraction agent was prepared using 70 parts sodium cyanate, 20 parts sodium humate, and 10 parts cuprous chloride according to the roasting times listed in Table 2. The leaching effect was tested using an air atmosphere and a roasting temperature of 600°C. Leaching conditions included a liquid-to-solid ratio of 3:1, a gold extraction agent concentration of 2 kg / t, a pH of 12, a rotation speed of 400 rpm, a leaching temperature of 25°C, and a leaching time of 24 hours. The roasting times and gold leaching yields are shown in Table 2.

[0031] Table 2 Effect of roasting time on gold leaching with low-toxic and environmentally friendly gold extraction agent

[0032]

[0033] From the above results, it can be seen that when the roasting time is 20 minutes, the gold leaching rate is the largest, reaching 94.01%.

[0034] Example 3: A gold extraction agent was prepared using 70 parts sodium cyanate, 20 parts sodium humate, and 10 parts cuprous chloride according to the roasting temperatures listed in Table 3. The leaching effect was tested using air atmosphere and a roasting time of 20 minutes. Leaching conditions included a liquid-to-solid ratio of 3:1, a gold extraction agent concentration of 2 kg / t, a pH of 12, a rotation speed of 400 rpm, a leaching temperature of 25°C, and a leaching time of 24 hours. The roasting temperatures and gold leaching yields are shown in Table 3.

[0035] Table 3 Effect of roasting temperature on gold leaching with low-toxic and environmentally friendly gold extraction agent

[0036]

[0037] From the above results, it can be seen that when the roasting temperature is 600℃, the gold leaching rate is the highest, reaching 94.01%.

[0038] Example 4: 70 parts sodium cyanate, 20 parts sodium humate, and 10 parts cuprous chloride were mixed uniformly, placed in a porcelain boat, and calcined in a muffle furnace. After calcination, the mixture was allowed to cool naturally to room temperature in air and then ground into powder to produce an environmentally friendly gold extraction agent. The calcination process conditions were: air atmosphere, calcination temperature of 600°C, and holding time of 20 minutes. The environmentally friendly gold extraction agent prepared by calcination was used in leaching experiments with sodium cyanide on a sulfide gold ore with a grade of 11.75 g / t, an oxidized gold ore with a grade of 7.48 g / t, and a carbonaceous and arsenic-containing gold ore with a grade of 2.37 g / t. The leaching process conditions were: liquid-to-solid ratio of 2:1, gold extraction agent concentration of 2 kg / t, pH of 12, rotation speed of 400 rpm, leaching temperature of 25°C, and leaching time of 24 hours. The leaching results are shown in Table 4.

[0039] Table 4

[0040]

[0041] From the above results, it can be seen that for 11.75g / t sulfide gold ore, the gold leaching rate of the environmentally friendly gold extraction agent is slightly lower than that of sodium cyanide, but the agent consumption is much lower than that of sodium cyanide. For 7.48g / t oxidized gold ore and 2.37g / t carbonaceous and arsenic-containing gold ore, the gold leaching rate of the environmentally friendly gold extraction agent is slightly higher than that of sodium cyanide, and the agent consumption is much lower than that of sodium cyanide. In summary, the agent consumption of the environmentally friendly gold extraction agent is lower than that of sodium cyanide, which can improve the economic benefits of large-scale industrial production. In addition, the gold extraction agent can be applied to a variety of gold mines, and for some gold mines, its gold leaching rate is slightly higher than that of sodium cyanide.

Claims

1. An environmentally friendly gold extraction agent, characterized in that: The raw materials are: 70-80 parts of cyanate, 20-30 parts of humate, and 5-10 parts of cuprous salt; it is prepared by a roasting synthesis process; The cyanate is at least one of sodium cyanate, potassium cyanate and ammonium cyanate; the humate is at least one of sodium humate, potassium humate and calcium humate; the cuprous salt is at least one of cuprous chloride, cuprous bromide, cuprous nitrate and cuprous sulfate; The roasting synthesis process conditions are: air atmosphere, roasting temperature of 500-700° C., and roasting time of 10-60 minutes.

2. The environmentally friendly gold extracting agent according to claim 1, characterized in that The calcined product is ground into powder.

3. The preparation method of the environmentally friendly gold extracting agent according to claim 1 or 2, characterized in that: The raw materials are mixed and roasted; roasting conditions: roasting at 500-700°C in air atmosphere for 10-60 minutes.

4. The preparation method according to claim 3, characterized in that The calcined product is ground into powder.

5. The use of the environmentally friendly gold extracting agent according to claim 1 or 2, characterized in that: Used for gold leaching.

6. The use according to claim 5, characterized in that Leaching conditions: liquid-solid ratio 2:1~5:1, gold extraction agent concentration 1~5kg / t, pH 9~12, rotation speed 300~600rpm, leaching time 12~48h, leaching temperature 20℃~70℃.

7. The use according to claim 6, characterized in that Leaching conditions: liquid-solid ratio 3:1, gold extraction agent concentration 2kg / t, pH 12, rotation speed 400rpm, leaching time 24h, leaching temperature 25℃.

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