A method for preparing a gold extraction agent

Abstract

This invention belongs to the field of gold extraction agent technology, specifically relating to a method for preparing a gold extraction agent. The invention provides a method for preparing a gold extraction agent, comprising the following steps: mixing sodium cyanate and iron powder, and carrying out a melt catalytic reaction to obtain the gold extraction agent. This invention uses iron powder as a catalyst, which can effectively promote the polymerization reaction of sodium cyanate. During the catalytic polymerization process, iron atoms can break the carbon-nitrogen triple bond in sodium cyanate into a carbon-nitrogen double bond, with one end of the carbon-nitrogen double bond linked to a sodium atom. The obtained gold extraction agent does not contain free cyanide ions and is therefore non-toxic. In application, the sodium in the obtained gold extraction agent can displace gold in gold ore, thus playing a role in gold refining. Test results from the embodiments show that the gold extraction efficiency of the gold extraction agent provided by this invention is comparable to that of sodium cyanide, and it is safe, environmentally friendly, and non-toxic.

Description

Technical Field

[0001] This invention belongs to the field of gold extraction agent technology, and specifically relates to a method for preparing a gold extraction agent. Background Technology

[0002] Gold is a rare and precious metal, an important strategic resource, and a currency reserve. At the same time, gold is an important industrial raw material with significant applications in the jewelry, medical, electronics, modern communications, and aerospace industries.

[0003] Currently, gold production in my country mainly relies on the cyanidation process. The cyanidation process utilizes an aqueous solution of cyanide, under conditions of dissolved oxygen in the solution or oxygen bubbled in, to dissolve gold in the mineral. This process is mature, simple, low-cost, adaptable, and has a high recovery rate, making it suitable for large-scale industrial production.

[0004] However, the cyanide extraction process suffers from problems such as high pollution, long leaching time, poor selectivity for metal ions, and susceptibility to interference from impurity ions. Furthermore, cyanide is a highly toxic substance that severely pollutes water and soil, harming the environment and human health. Therefore, there is an urgent need to research novel environmentally friendly non-cyanide gold extraction agents to replace sodium cyanide in industrial production. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a gold extraction agent. The gold extraction agent obtained by the method provided by this invention is free of cyanide ions, is safe and environmentally friendly, and has a high gold extraction rate.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing a gold extraction agent, comprising the following steps:

[0008] Sodium cyanate and iron powder are mixed and subjected to a melt catalytic reaction to obtain the gold extraction agent.

[0009] Preferably, the iron powder has a particle size of 60-100 mesh.

[0010] Preferably, the mass of the iron powder is 0.8 to 1.2% of the mass of the sodium cyanate.

[0011] Preferably, the temperature of the melt catalytic reaction is 800–850°C, and the holding time is 4–6 h.

[0012] Preferably, the heating rate to the melting catalytic reaction temperature is 2–4 °C / min.

[0013] Preferably, after the melt catalytic reaction, the product is further subjected to sequential cooling, casting, and crushing.

[0014] The cooling temperature is 700–750°C.

[0015] This invention provides a method for preparing a gold extraction agent, comprising the following steps: mixing sodium cyanate and iron powder, and carrying out a melt catalytic reaction to obtain the gold extraction agent. This invention uses iron powder as a catalyst, which can effectively promote the polymerization reaction of sodium cyanate. Sodium cyanate has the molecular formula NaOCN and its molecular structure is Na-OC≡N, where the carbon-nitrogen triple bond is a cyanide ion. During the catalytic polymerization process, iron atoms can break the carbon-nitrogen triple bond in sodium cyanate into a carbon-nitrogen double bond, with a sodium atom attached to one end of the double bond. After the reaction is complete, there are no free cyanide ions in the product, therefore the product is non-toxic; in the application of the obtained gold extraction agent, sodium can replace gold in gold ore, playing a role in gold refining. Test results from the examples show that the gold extraction efficiency of the gold extraction agent provided by this invention is comparable to that of sodium cyanide, and it is safe, environmentally friendly, and non-toxic. Detailed Implementation

[0016] This invention provides a method for preparing a gold extraction agent, comprising the following steps:

[0017] Sodium cyanate and iron powder are mixed and subjected to a melt catalytic reaction to obtain the gold extraction agent.

[0018] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0019] In this invention, the particle size of the iron powder is preferably 60-100 mesh, more preferably 70-90 mesh, and even more preferably 80 mesh.

[0020] In this invention, the mass of the iron powder is preferably 0.8 to 1.2% of the mass of the sodium cyanate, more preferably 0.9 to 1.1%, and even more preferably 1.0%.

[0021] The present invention does not impose any special limitations on the mixing process; the two can be mixed evenly using methods well known to those skilled in the art.

[0022] In this invention, the temperature of the melt catalytic reaction is preferably 800-850°C, more preferably 810-840°C, and even more preferably 820-830°C; the heating rate to the melt catalytic reaction temperature is preferably 2-4°C / min; and the holding time is 4-6 hours, more preferably 5 hours.

[0023] In this invention, the amount of sodium cyanate loaded in the reaction vessel is preferably 1 / 4 to 1 / 3 of the mass of the fully loaded sodium cyanate melt in the reaction vessel.

[0024] Following the melt catalytic reaction, the present invention preferably further includes sequentially cooling, casting, and pulverizing the obtained product. In this invention, the cooling temperature is preferably 700–750°C. In this invention, the casting is preferably carried out in a cooling tank; the material of the cooling tank is preferably ordinary low-carbon steel, cast iron, or stainless steel; the size of the cooling tank is preferably 2m*3m. In a specific embodiment of the present invention, the crushing process preferably includes: using an impact drill to break the plate-shaped solid obtained from the casting into small blocks of solid, and using a Raymond mill to crush the small blocks of solid into powder.

[0025] In this invention, the particle size of the gold extraction agent is preferably 100-300 mesh.

[0026] In this invention, the molten catalytic reaction is preferably carried out in a reactor; the reactor is preferably made of 316L stainless steel or ordinary low-carbon steel plate; the reactor has an inner diameter of 0.5-1m, a height of 1.1-1.7m, and a wall thickness of 10-20mm; the reactor cover is preferably provided with an exhaust port and a temperature measuring port; the diameter of the exhaust port is preferably 150mm; a thermocouple is preferably inserted into the temperature measuring port for temperature monitoring; the diameter of the temperature measuring port is preferably 20mm.

[0027] To further illustrate the present invention, the following detailed description of a method for preparing a gold extraction agent provided by the present invention is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0028] Example 1

[0029] The reactor used in this embodiment has an inner diameter of 1 meter, a height of 1.7 meters, a wall thickness of 20 mm, and is made of 316L stainless steel. A 316L stainless steel cover is used to cover the reactor. The cover has a 150 mm diameter vent hole and a 20 mm diameter temperature measuring hole for inserting thermocouples for temperature monitoring.

[0030] 750 kg of powdered solid sodium cyanate and 7.5 kg of iron powder were mixed evenly and added to a reaction vessel. The mass of the iron powder was 1% of the mass of the sodium cyanate, and the particle size of the iron powder was 80 mesh.

[0031] The temperature of the reactor was increased from room temperature to 850℃ at a heating rate of 3℃ / min for a catalytic melting reaction, and the reaction was maintained at this temperature for 5 hours. After the reaction was completed, the temperature was lowered to 720℃, and the cooled molten liquid was poured into a cooling tank (the cooling tank material was 304 stainless steel, and the size was 2×3m) for molding. After cooling, a plate-shaped solid with a thickness of about 53mm was obtained. The plate-shaped solid was broken into small pieces using an impact drill, and the small pieces of solid were crushed into powder using a Raymond mill to obtain the gold extraction agent with a particle size of 100-300 mesh.

[0032] Example 2

[0033] The reactor used in this embodiment has an inner diameter of 1 meter, a height of 1.7 meters, and a wall thickness of 20 mm. The reactor material is A3 steel plate. The reactor is covered with an A3 steel plate. The cover plate has a 150 mm diameter vent hole and a 20 mm diameter temperature measuring hole for inserting thermocouples for temperature monitoring.

[0034] 600 kg of powdered solid sodium cyanate was mixed evenly with 4.8 kg of iron powder and added to a reaction vessel. The mass of the iron powder was 0.8% of the mass of the sodium cyanate, and the particle size of the iron powder was 100 mesh.

[0035] The temperature of the reactor was increased from room temperature to 850℃ at a heating rate of 3℃ / min for a catalytic melting reaction, and the reaction was maintained at this temperature for 5 hours. After the reaction was completed, the temperature was lowered to 750℃, and the cooled molten liquid was poured into a cooling tank (the cooling tank material was A3 steel plate, with a size of 2×3m) for molding. After cooling, a plate-shaped solid with a thickness of about 43mm was obtained. The plate-shaped solid was broken into small pieces using an impact drill, and the small pieces of solid were crushed into powder using a Raymond mill to obtain the gold extraction agent with a particle size of 100-300 mesh.

[0036] Example 3

[0037] The reactor used in this embodiment has an inner diameter of 1 meter, a height of 1.7 meters, a wall thickness of 20 mm, and is made of 316L stainless steel. A 316L stainless steel cover is used to cover the reactor. The cover has a 150 mm diameter vent hole and a 20 mm diameter temperature measuring hole for inserting thermocouples for temperature monitoring.

[0038] 700 kg of powdered solid sodium cyanate and 8.4 kg of iron powder were mixed evenly and added to a reaction vessel. The mass of the iron powder was 1.2% of the mass of the sodium cyanate, and the particle size of the iron powder was 60 mesh.

[0039] The temperature of the reactor was increased from room temperature to 800℃ at a rate of 3℃ / min for a catalytic melting reaction, and the reaction was maintained at this temperature for 6 hours. After the reaction was completed, the temperature was lowered to 750℃, and the cooled molten liquid was poured into a cooling tank (made of 304 stainless steel, with dimensions of 2×3m) for molding. After cooling, a plate-shaped solid with a thickness of about 50mm was obtained. The plate-shaped solid was broken into small pieces using an impact drill, and the small pieces were crushed into powder using a Raymond mill to obtain the gold extraction agent with a particle size of 100-300 mesh.

[0040] Example 4

[0041] The reactor used in this embodiment has an inner diameter of 1 meter, a height of 1.7 meters, a wall thickness of 20 mm, and is made of 316L stainless steel. A 316L stainless steel cover is used to cover the reactor. The cover has a 150 mm diameter vent hole and a 20 mm diameter temperature measuring hole for inserting thermocouples for temperature monitoring.

[0042] 600 kg of powdered solid sodium cyanate and 6.0 kg of iron powder were mixed evenly and added to a reaction vessel. The mass of the iron powder was 1% of the mass of the sodium cyanate, and the particle size of the iron powder was 100 mesh.

[0043] The temperature of the reactor was increased from room temperature to 850℃ at a heating rate of 3℃ / min for a catalytic melting reaction, and the reaction was maintained at this temperature for 6 hours. After the reaction was completed, the temperature was lowered to 700℃, and the cooled molten liquid was poured into a cooling tank (the cooling tank material was 304 stainless steel, and the size was 2×3m) for molding. After cooling, a plate-shaped solid with a thickness of about 43mm was obtained. The plate-shaped solid was broken into small pieces using an impact drill, and the small pieces of solid were crushed into powder using a Raymond mill to obtain the gold extraction agent with a particle size of 100-300 mesh.

[0044] Example 5

[0045] The reactor used in this embodiment has an inner diameter of 0.5 meters, a height of 1.1 meters, and a wall thickness of 10 mm. The reactor material is A3 steel plate. The A3 steel plate is used as a cover to cover the reactor. The cover has a 150 mm diameter vent hole and a 20 mm diameter temperature measuring hole for inserting thermocouples for temperature monitoring.

[0046] 750 kg of powdered solid sodium cyanate and 7.5 kg of iron powder were mixed evenly and added to a reaction vessel. The mass of the iron powder was 1.0% of the mass of the sodium cyanate, and the particle size of the iron powder was 100 mesh.

[0047] The temperature of the reactor was increased from room temperature to 850℃ at a heating rate of 3℃ / min for a catalytic melting reaction, and the reaction was maintained at this temperature for 4 hours. After the reaction was completed, the temperature was lowered to 700℃, and the cooled molten liquid was poured into a cooling tank (the cooling tank material was A3 steel plate, with a size of 2×3m) for molding. After cooling, a plate-shaped solid with a thickness of about 32mm was obtained. The plate-shaped solid was broken into small pieces using an impact drill, and the small pieces of solid were crushed into powder using a Raymond mill to obtain the gold extraction agent with a particle size of 100-300 mesh.

[0048] Performance testing

[0049] Test Example 1

[0050] The grade of the gold extraction agents obtained in Examples 1-5 was tested;

[0051] The testing method is as follows:

[0052] Prepare silver nitrate standard solution: Weigh 1.7039g of silver nitrate solid with a purity of 99.7%, dissolve it completely in 100mL of distilled water, transfer the solution to a 1000mL brown standard volumetric flask, add distilled water to make up to 1000mL, shake well, seal and store for later use.

[0053] Prepare the sample solution to be tested: Weigh m (m = 2~10) g of sample into a 250 mL Erlenmeyer flask, add about 150 mL of distilled water, stir until completely dissolved, transfer to a 1000 mL volumetric flask, wash three times, transfer the washing solution together, add distilled water to make up to 1000 mL, and obtain the sample solution to be tested.

[0054] Prepare the test silver indicator solution: Weigh 0.15g test silver (para-dimethylaminobenzylrhodane), dissolve it completely in 100mL acetone, and then transfer it to a 100mL brown dropper bottle and store it in a sealed container for later use.

[0055] Titration reaction: Take 5.0 mL of the sample solution to be tested and place it in a 100 mL Erlenmeyer flask. Add 10 mL of distilled water and 5 drops of silver nitrate indicator solution. Titrate with silver nitrate standard solution until the solution changes from yellow to orange-red. Record the volume V of silver nitrate standard solution consumed.

[0056] Calculate grade:

[0057]

[0058] The quality test results of the gold extraction agents obtained in Examples 1-5 are shown in Table 1:

[0059] Table 1 shows the gold extraction grades obtained in Examples 1-5.

[0060] Example 1 Example 2 Example 3 Example 4 Example 5 grade 43.65 42.66 42.18 44.5 44.14

[0061] Detection of free cyanide ions in the test sample solution: According to the method described in the "National Environmental Protection Standard of the People's Republic of China" (HJ484-2009), the concentration of free cyanide ions in the test sample solution was directly detected by ion chromatography. The test results were all below 5 ppm, indicating that there were almost no free cyanide ions in the test sample solution.

[0062] The gold extraction agent provided by this invention has extremely low toxicity. Acute oral toxicity tests on mice showed that the acute oral LD50 of the gold extraction agent... 50 >2000mg / kg.

[0063] Test Example 2

[0064] The gold extraction effect of the gold extraction agents obtained in Examples 1-5 was tested;

[0065] Gold ore powder with a grade of 3.52 (i.e., 3.52 grams of gold per ton of gold ore) and a particle size of 200 mesh or less was placed in a reaction tank. Water was added to a return water tank to adjust the pH to 11±0.5. The gold extraction agent was poured into the return water tank and stirred gently until it was completely dissolved. Then, the aqueous solution from the return water tank was poured into the reaction tank to completely submerge the gold ore. After impregnation, the aqueous solution containing dissolved gold was released. Activated carbon was used to adsorb the solution to obtain gold-loaded carbon. The gold-loaded carbon was then desorbed using a high-temperature, high-pressure, cyanide-free desorption method. The mass of gold was weighed, and the gold extraction rate was calculated. Sodium cyanide was used as a comparative example.

[0066] The specific conditions, parameters, and test results are shown in Table 2:

[0067] Table 2 shows the gold extraction rates of the gold extraction agents obtained in Examples 1-5.

[0068]

[0069]

[0070] As shown in Table 2, the gold extraction agent obtained by this invention has a gold extraction rate comparable to that of sodium cyanide, reaching over 91%. This novel environmentally friendly gold extraction agent solves the problem of significant pollution associated with the current use of sodium cyanide as a gold extraction agent in gold and silver mines both domestically and internationally, demonstrating a significant environmental protection effect.

[0071] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a gold extraction agent, characterized in that, Includes the following steps: Sodium cyanate and iron powder are mixed and subjected to a melt catalytic reaction to obtain the gold extraction agent; The mass of the iron powder is 0.8 to 1.2% of the mass of the sodium cyanate; The temperature of the molten catalytic reaction is 800–850°C, and the holding time is 4–6 h.

2. The preparation method according to claim 1, characterized in that, The iron powder has a particle size of 60-100 mesh.

3. The preparation method according to claim 1, characterized in that, The heating rate to the melting catalytic reaction temperature is 2–4 °C / min.

4. The preparation method according to claim 1, characterized in that, After the melt catalytic reaction, the process further includes sequentially cooling, casting, and crushing the resulting product. The cooling temperature is 700–750°C.

Images