Modified activated carbon for gold extraction and method for preparing the same

Abstract

The application discloses a modified activated carbon for gold extraction, and relates to the technical field of gold extraction, which comprises the following raw material components and weight parts: acid-washed wood charcoal powder 55-65 parts; waste plastic particles 15-25 parts; sulfonated asphalt 10-18 parts; sodium mercapto-modified humic acid 5-10 parts; sulfur-containing silane coupling agent 1-2 parts; nano alumina 1-3 parts; pore-forming agent 2-4 parts; and extrusion aid 0.5-1 part. Compared with traditional coconut shells, the modified activated carbon reduces the cost, realizes waste recycling, improves the gold adsorption capacity, greatly reduces the residual gold desorption, effectively improves the abrasion rate, and improves the copper interference resistance.

Description

Technical Field

[0001] This invention relates to the field of gold extraction technology, and in particular to a modified activated carbon for gold extraction and its preparation method. Background Technology

[0002] As a high-value precious metal, the development of gold extraction technology has always revolved around two core goals: improving efficiency and environmental friendliness. Traditional gold extraction methods, such as heap leaching and amalgamation, were once widely used, but they suffer from low efficiency and severe environmental pollution. For example, heap leaching requires storing low-grade ore in the open air and spraying it with cyanide, resulting in a gold dissolution rate of less than 60% and a high risk of cyanide leakage. Amalgamation, due to the highly toxic nature of mercury, causes irreversible harm to the health of operators and the ecological environment.

[0003] In the 1970s, the carbon-in-pulp (CIP) process, based on the principle of activated carbon adsorption, emerged, marking a revolutionary breakthrough in the gold extraction industry. This technology, building upon cyanide leaching, utilizes the porous structure and high adsorption selectivity of activated carbon (especially coconut shell activated carbon) to directly adsorb gold cyanide complex ions from the ore pulp, achieving highly efficient gold enrichment. Coconut shell activated carbon, made from coconut shells through high-temperature carbonization and activation, possesses a microporous structure (pore size 2-50 nm) providing a huge specific surface area (800-1500 m² / g), enabling selective adsorption of gold ions. It also maintains stable performance under strong acid, strong alkali, and high-temperature environments, with an adsorption capacity 30%–50% higher than traditional adsorbents.12

[0004] However, existing activated carbon is prone to pore structure wear during actual gold extraction, has a high cost, and is easily affected by copper ions.

[0005] Therefore, this invention is proposed to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a modified activated carbon for gold extraction, comprising the following raw material components and parts by weight:

[0007] 55-65 parts of acid-washed wood charcoal powder;

[0008] 15-25 parts of waste plastic granules;

[0009] 10-18 parts of sulfonated asphalt;

[0010] 5-10 parts of mercapto-modified sodium humate;

[0011] 1-2 parts of sulfur-containing silane coupling agent;

[0012] 1-3 parts of nano-alumina;

[0013] 2-4 parts of pore-forming agent;

[0014] Extrusion aid 0.5 to 1 part.

[0015] Preferably, the waste plastic particles are selected from PET or PP, with a particle size of 1-100 μm; the pore-forming agent is triethyl citrate, and the extrusion aid is lactic acid.

[0016] Preferably, the thiol-modified sodium humate is prepared by reacting sodium humate with 3-mercaptopropionic acid at a molar ratio of 1:(1.5-2.5) at 70-90°C, and the surface thiol density is ≥0.8mmol / g.

[0017] Preferably, the sulfur-containing silane coupling agent is 3-mercaptopropyltrimethoxysilane or bis-(γ-triethoxysilylpropyl)disulfide; the nano-alumina particle size is 50-100 nm.

[0018] Preferably, it has a core-shell structure:

[0019] The core layer is composed of acid-washed wood charcoal powder, pore-forming agent and extrusion aid, with micropores concentrated in the range of 1-2 nm.

[0020] The outer shell is composed of waste plastic granules, sulfonated asphalt, mercapto-modified sodium humate, sulfur-containing silane coupling agent, nano-alumina and extrusion aid;

[0021] Preferably, the acid-washed wood charcoal powder is ultrasonically treated with 10wt% hydrochloric acid solution, and the ash content is ≤3%; the sulfonated asphalt has a softening point ≥180℃ and a sulfur content ≥3wt%.

[0022] Preferably, its surface is loaded with cuprous ion active sites, the copper content is 0.5-1.5 wt%, and the cuprous ions are formed by the thermal decomposition and reduction of copper nitrate.

[0023] A method for preparing modified activated carbon includes the following steps:

[0024] (1) Modified waste plastic asphalt is prepared by melt-blending waste plastic particles with sulfonated asphalt;

[0025] (2) The wood charcoal powder is ultrasonically treated with hydrochloric acid solution and then washed with water until neutral to obtain acid-washed wood charcoal powder;

[0026] (3) The acid-washed wood charcoal powder, pore-forming agent and extrusion aid are mixed to form the core layer material;

[0027] (4) The modified waste plastic asphalt, mercapto-modified sodium humate, sulfur-containing silane coupling agent, nano alumina and extrusion aid are mixed to form the outer shell material;

[0028] (5) Core-shell co-extrusion molding was carried out using a twin-screw extruder;

[0029] (6) Gradient carbonization treatment: First carbonize at 400℃ under N2 protection, then switch to CO2 atmosphere and carbonize at 600℃;

[0030] (7) Microwave activation and surface modification: Activate by passing a mixture of water vapor and CO2 at 850℃, and spray with copper nitrate solution.

[0031] Preferably, in step (6), the carbonization is held at 400℃ for 0.5h and at 600℃ for 1h; the heating rate is 5-8℃ / min.

[0032] Preferably, in step (7), the volume ratio of mixed gas water vapor to CO2 is 1:2, the total flow rate is 5-8 mL / min·g carbon, the concentration of copper nitrate solution is 10 wt%, and the spraying amount is 5-8% of the carbon mass.

[0033] The beneficial effects of this invention are:

[0034] Compared with traditional coconut shells, the modified activated carbon of this invention reduces costs, achieves waste recycling, improves gold adsorption capacity, significantly reduces residual gold after desorption, effectively improves wear rate, and enhances resistance to copper interference. Attached Figure Description

[0035] Figure 1 The graphs show the gold adsorption rate of 1g activated carbon in 1L gold solution for Examples 3 and Comparative Example 1.

[0036] Figure 2 This is a SEM image of the modified activated carbon after gold adsorption in Example 3;

[0037] Figure 3 This is a SEM image of the coconut shell after carbon adsorption for gold. Detailed Implementation

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Example 1

[0040] A modified activated carbon was prepared using 65 parts of acid-washed wood charcoal powder and 25 parts of waste plastic granules.

[0041] 18 parts sulfonated asphalt, 10 parts mercapto-modified sodium humate, 2 parts sulfur-containing silane coupling agent, 3 parts nano alumina, 4 parts triethyl citrate, and 1 part lactic acid.

[0042] The specific steps are as follows:

[0043] (1) Modified waste plastic asphalt is prepared by melt-blending waste plastic particles with petroleum asphalt;

[0044] (2) The acid-washed wood charcoal powder is ultrasonically treated with hydrochloric acid solution and then washed with water until neutral to obtain acid-washed wood charcoal powder;

[0045] (3) Acid-washed wood charcoal powder, triethyl citrate and lactic acid are mixed to form the core layer material;

[0046] (4) The modified waste plastic asphalt, mercapto-modified sodium humate, sulfur-containing silane coupling agent, nano alumina and lactic acid are mixed to form the outer shell material.

[0047] (5) Core-shell co-extrusion molding was carried out using a twin-screw extruder;

[0048] (6) Gradient carbonization treatment: First carbonize at 400℃ under N2 protection, then switch to CO2 atmosphere and carbonize at 600℃. The carbonization at 400℃ is held for 0.5h, and the carbonization at 600℃ is held for 1h. The heating rate is 5-8℃ / min.

[0049] (7) Microwave activation and surface modification: Activate by passing a mixture of steam and CO2 at 850℃, spray copper nitrate solution, the volume ratio of steam to CO2 in the mixture is 1:2, the total flow rate is 5-8 mL / min·g carbon; the concentration of copper nitrate solution is 10wt%, and the spraying amount is 5-8% of the carbon mass.

[0050] Example 2

[0051] The preparation of a modified activated carbon uses 55 parts of acid-washed wood charcoal powder and 15 parts of waste plastic granules.

[0052] 10 parts sulfonated asphalt, 5 parts mercapto-modified sodium humate, and 1 part sulfur-containing silane coupling agent;

[0053] 1 part nano-alumina, 2 parts triethyl citrate, 0.5 parts lactic acid;

[0054] The specific steps are as follows:

[0055] (1) Modified waste plastic asphalt is prepared by melt-blending waste plastic particles with petroleum asphalt;

[0056] (2) The acid-washed wood charcoal powder is ultrasonically treated with hydrochloric acid solution and then washed with water until neutral to obtain acid-washed wood charcoal powder;

[0057] (3) Acid-washed wood charcoal powder, triethyl citrate and lactic acid are mixed to form the core layer material;

[0058] (4) The modified waste plastic asphalt, mercapto-modified sodium humate, sulfur-containing silane coupling agent, nano alumina and lactic acid are mixed to form the outer shell material.

[0059] (5) Core-shell co-extrusion molding was carried out using a twin-screw extruder;

[0060] (6) Gradient carbonization treatment: First carbonize at 400℃ under N2 protection, then switch to CO2 atmosphere and carbonize at 600℃. The carbonization at 400℃ is held for 0.5h, and the carbonization at 600℃ is held for 1h. The heating rate is 5-8℃ / min.

[0061] (7) Microwave activation and surface modification: Activate by passing a mixture of steam and CO2 at 850℃, spray copper nitrate solution, the volume ratio of steam to CO2 in the mixture is 1:2, the total flow rate is 5-8 mL / min·g carbon; the concentration of copper nitrate solution is 10wt%, and the spraying amount is 5-8% of the carbon mass.

[0062] Example 3

[0063] The preparation of a modified activated carbon involves using 60 parts of acid-washed wood charcoal powder and 20 parts of waste plastic granules.

[0064] 15 parts sulfonated asphalt, 5 parts mercapto-modified sodium humate, and 2 parts sulfur-containing silane coupling agent.

[0065] 2 parts nano-alumina, 3 parts triethyl citrate, 0.5 parts lactic acid;

[0066] The specific steps are as follows:

[0067] (1) Modified waste plastic asphalt is prepared by melt-blending waste plastic particles with petroleum asphalt;

[0068] (2) The acid-washed wood charcoal powder is ultrasonically treated with hydrochloric acid solution and then washed with water until neutral to obtain acid-washed wood charcoal powder;

[0069] (3) Acid-washed wood charcoal powder, triethyl citrate and lactic acid are mixed to form the core layer material;

[0070] (4) The modified waste plastic asphalt, mercapto-modified sodium humate, sulfur-containing silane coupling agent, nano alumina and lactic acid are mixed to form the outer shell material.

[0071] (5) Core-shell co-extrusion molding was carried out using a twin-screw extruder;

[0072] (6) Gradient carbonization treatment: First carbonize at 400℃ under N2 protection, then switch to CO2 atmosphere and carbonize at 600℃. The carbonization at 400℃ is held for 0.5h, and the carbonization at 600℃ is held for 1h. The heating rate is 5-8℃ / min.

[0073] (7) Microwave activation and surface modification: Activate by passing a mixture of steam and CO2 at 850℃, spray copper nitrate solution, the volume ratio of steam to CO2 in the mixture is 1:2, the total flow rate is 5-8 mL / min·g carbon; the concentration of copper nitrate solution is 10wt%, and the spraying amount is 5-8% of the carbon mass.

[0074] Comparative Example 1 is commercially available coconut shell charcoal (Mulinsen activated carbon).

[0075] The following table compares gold adsorption experiments:

[0076]

[0077] Compared with traditional coconut shell carbon, the modified activated carbon of this invention reduces costs and enables waste recycling. At the same time, it has a faster gold adsorption rate than coconut shell carbon, improves gold adsorption capacity, greatly reduces residual gold after desorption, effectively improves wear rate, and enhances resistance to copper interference.

[0078] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A modified activated carbon for gold extraction, characterized in that, Includes the following raw material components and parts by weight: 55-65 parts of acid-washed wood charcoal powder; 15-25 parts of waste plastic granules; 10-18 parts of sulfonated asphalt; 5-10 parts of mercapto-modified sodium humate; 1-2 parts of sulfur-containing silane coupling agent; 1-3 parts of nano-alumina; 2-4 parts of pore-forming agent; Extrusion aid 0.5-1 part; The thiol-modified sodium humate is prepared by reacting sodium humate with 3-mercaptopropionic acid at a molar ratio of 1:(1.5-2.5) at 70-90℃, and the surface thiol density is ≥0.8mmol / g; The sulfur-containing silane coupling agent is 3-mercaptopropyltrimethoxysilane or bis-(γ-triethoxysilylpropyl)disulfide; the nano-alumina particles have a diameter of 50-100 nm. The modified activated carbon has a core-shell structure: the core layer is formed by acid-washed wood charcoal powder, pore-forming agent and extrusion aid, with micropores concentrated in the range of 1-2 nm; the outer shell layer is formed by waste plastic particles, sulfonated asphalt, mercapto-modified sodium humate, sulfur-containing silane coupling agent, nano-alumina and extrusion aid. The modified activated carbon has cuprous ion active sites loaded on its surface, and the copper content is 0.5-1.5 wt%. The cuprous ions are formed by the thermal decomposition and reduction of copper nitrate. The method for preparing the modified activated carbon includes: core-shell co-extrusion molding of the core layer material and the outer shell material, gradient carbonization treatment, microwave activation, and surface modification with copper nitrate solution.

2. The modified activated carbon according to claim 1, characterized in that, The waste plastic particles are selected from PET or PP, with a particle size of 1-100μm; the pore-forming agent is triethyl citrate, and the extrusion aid is lactic acid.

3. The modified activated carbon according to claim 1, characterized in that, The acid-washed wood charcoal powder is ultrasonically treated with 10wt% hydrochloric acid solution, and the ash content is ≤3%; the sulfonated asphalt has a softening point ≥180℃ and a sulfur content ≥3wt%.

4. A method for preparing modified activated carbon as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Modified waste plastic asphalt is prepared by melt-blending waste plastic particles with sulfonated asphalt; (2) The wood charcoal powder is ultrasonically treated with hydrochloric acid solution and then washed with water until neutral to obtain acid-washed wood charcoal powder; (3) The acid-washed wood charcoal powder, pore-forming agent and extrusion aid are mixed to form the core layer material; (4) The modified waste plastic asphalt, mercapto-modified sodium humate, sulfur-containing silane coupling agent, nano alumina and extrusion aid are mixed to form the outer shell material; (5) Core-shell co-extrusion molding was carried out using a twin-screw extruder; (6) Gradient carbonization treatment: First carbonize at 400℃ under N2 protection, then switch to CO2 atmosphere and carbonize at 600℃; (7) Microwave activation and surface modification: Activate by passing a mixture of water vapor and CO2 at 850℃, and spray with copper nitrate solution.

5. The preparation method according to claim 4, characterized in that, In step (6), carbonization is carried out at 400℃ for 0.5h and carbonization is carried out at 600℃ for 1h; the heating rate is 5-8℃ / min.

6. The preparation method according to claim 4, characterized in that, In step (7), the volume ratio of water vapor to CO2 in the mixed gas is 1:2, the total flow rate is 5-8 mL / min·g carbon, the concentration of copper nitrate solution is 10 wt%, and the spray volume is 5-8% of the carbon mass.

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