Method for strengthening biological leaching of arsenic-containing gold ore by adopting iron-containing waste residues

Abstract

The invention relates to a method for strengthening biological leaching of arsenic-containing gold ore by adopting iron-containing waste residues, which comprises the following specific steps: uniformly mixing the iron-containing waste residues with reducing coal powder, and carrying out magnetizing roasting under controlled conditions to obtain magnetic waste residues; inoculating the bacterial liquid into a 9K culture medium, adjusting the pH value, and culturing in a constant-temperature shaking table to obtain a cultured bacterial liquid; grinding the arsenic-containing gold ore and the magnetic waste residue powder, adding the ground arsenic-containing gold ore and the ground magnetic waste residue powder into the culture bacteria solution to prepare ore pulp, and carrying out constant-temperature biological leaching by controlling conditions; and after biological leaching is finished, magnetic attraction separation is conducted on the magnetic waste residues from a leaching system through a magnet, the magnetic waste residues are recycled after being washed and dried, and cyanidation gold extraction is conducted on the biological leaching residues. The method solves the existing process problems of long biological leaching period, low leaching rate and the like of the arsenic-containing ore, has the advantages of simple flow, low medicament consumption, low production cost, resource utilization of the iron-containing waste residue and the like, and has remarkable economic, social and environmental benefits.

Description

Technical Field

[0001] The invention relates to the field of biometallurgy, and in particular to a method for enhancing bioleaching of arsenic-containing gold ore by using iron-containing waste slag. Background Art

[0002] With the continuous consumption of easily-processed gold ore resources, nearly 2 / 3 of the world's gold ore resources are refractory gold ore, and about 1 / 3 of gold production comes from the development of refractory gold ore. Refractory gold ore resources have become an important source of gold extraction. The gold in refractory gold ore is usually embedded in the mineral lattice in the form of fine particles. It is difficult to dissociate its monomers through methods such as ultrafine grinding, and the direct cyanide leaching rate is generally less than 80%. In order to recover the gold in refractory gold ore, it is necessary to use appropriate pretreatment technology to destroy the outer inclusions of the gold ore, expose the gold particles, and improve the reaction efficiency of the cyanide solution and the gold particles. At the same time, it is necessary to remove harmful substances such as arsenic, sulfur and carbon in the ore to eliminate their negative impact on subsequent cyanide gold extraction.

[0003] At present, refractory gold ores can be pretreated by ultrafine grinding, pressure oxidation, roasting oxidation, chemical oxidation and biological oxidation. Compared with other processes, biological oxidation pretreatment can oxidize and decompose gold-bearing minerals by microorganisms at room temperature and pressure, dissociate the encapsulated gold particles, and create favorable conditions for the subsequent cyanide gold extraction. More than 50% of my country's refractory gold ore resources are suitable for extraction by biological oxidation pretreatment. However, the microbial oxidation process has problems such as long oxidation cycle, low slurry concentration, and harsh raw material requirements. In particular, when treating gold ores such as arsenopyrite, which are arsenic-containing gold-bearing minerals, the gold recovery rate is often very low, resulting in serious waste of resources. This is mainly because arsenic-containing gold ores will produce a large amount of arsenic during the microbial oxidation process. High concentrations of arsenic have a significant inhibitory effect on the growth of microbial communities, hindering their catalytic oxidation of arsenopyrite, and thus affecting the recovery of gold in the subsequent cyanide leaching process. Therefore, how to reduce the toxicity of arsenic to microorganisms and accelerate the bioleaching rate of arsenic-containing gold ores is the key to promoting the advancement of microbial preoxidation technology for refractory gold ores. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art and solve the problem of long biological leaching cycle and low leaching rate of microorganisms for arsenic-containing gold ore, the purpose of the present invention is to provide a method for strengthening the biological leaching of arsenic-containing gold ore using iron-containing waste slag. The iron-containing waste slag is first magnetized and modified, and then the modified iron-containing waste slag is added to the biological leaching system of arsenic-containing gold ore, thereby achieving the effect of improving biological oxidation of arsenic. The specific technical scheme is: a method for strengthening the biological leaching of arsenic-containing gold ore using iron-containing waste slag, characterized in that the method comprises the following steps:

[0005] S1. Magnetization of waste slag: Mix the iron-containing waste slag and reduced coal powder evenly, and carry out magnetization roasting under controlled conditions to obtain magnetic waste slag.

[0006] S2. Bacterial culture: inoculate the bacterial solution into 9K culture medium, adjust the pH value and culture in a constant temperature shaker to obtain the culture solution.

[0007] S3. Enhanced leaching: Grind the arsenic-containing gold ore and magnetic waste slag powder and add them to the culture solution to make slurry, and control the conditions for constant temperature biological leaching.

[0008] S4. Material separation: After the bioleaching is completed, the magnetic waste residue is first separated from the leaching system by magnets, and the magnetic waste residue is recycled after washing and drying. The arsenic content in the bioleaching solution of arsenic-containing gold ore is tested and the arsenic removal rate is calculated, and the bioleaching residue is subjected to cyanide gold extraction.

[0009] The iron-containing waste slag described in step S1 is one of iron-containing sulfuric acid slag, iron-containing cyanide tailings, zinc leaching slag, and iron alum slag.

[0010] The magnetization roasting conditions described in step S1 are: coal powder dosage 1-25%, roasting temperature 550-850° C., roasting time 0.5-3 h, and roasting atmosphere is inert gas nitrogen.

[0011] The magnetic waste slag described in step S1 contains residual carbon or residual sulfur, and the mass fraction of the residual carbon or residual sulfur is 0.1% to 5%.

[0012] The bacteria contained in the bacterial solution described in step S2 are one or more of Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans, Acidithiobacillus sulfooxidans, Thermosiderosinophilic Bacillus, Acidithiobacillus sulfooxidans and Thermoacidophilic Archaea.

[0013] The composition of the 9K medium in step S2 is: (NH 4 ) 2 SO 4 3g / L, K 2 HPO 4 0.5g / L, MgSO 4 7H 2 O0.5g / L, Ca(NO 3 ) 2 0.01g / L, KCl 0.1g / L, FeSO 4 7H 2 O 44.2g / L.

[0014] The inoculation volume in step S2 is 1:(10-20) according to the volume ratio of bacterial solution to 9K medium, and the bacterial concentration in the initial bacterial solution is 2.0×10 8 / ml~8.0×10 8 Pieces / mL.

[0015] The shaking incubation conditions described in step S2 are: pH value 1.0-2.0, temperature 40-60° C., rotation speed 120-350 rpm, and incubation time 1-10 days.

[0016] The mass ratio of the arsenic-containing gold ore and the magnetic waste slag powder in step S3 is 1:(0.01-1), the size of the ground arsenic-containing gold ore and magnetic waste slag powder is that the part with a particle size of ≤38μm accounts for 60-90% of the total mass of the powder, and the mass concentration of the slurry is 1-20%.

[0017] The bioleaching conditions in step S3 are pH 1.0-2.0, temperature 35-55° C., and leaching time 2-15 days.

[0018] The present invention uses magnetized iron-containing waste slag as an enhanced leaching additive for a biological leaching system. The magnetized waste slag contains magnetite, and forms a new system different from arsenic biological leaching with residual carbon or residual sulfur, which buffers the toxic effect of arsenic on organisms and can strengthen the oxidation leaching of arsenic-containing ores under the action of the primary battery. The double system can effectively improve the arsenic removal rate. Compared with the case where no iron-containing waste slag is added, the arsenic removal rate is increased by 11% to 52%, solving the bottleneck problems of long biological leaching cycle and low leaching rate of arsenic-containing ores. The iron-containing waste slag of the present invention can be separated by magnetic separation and recycled, has a simple process flow, low reagent consumption, low production cost, and provides a new way to fully utilize the iron-containing waste slag, with significant economic, social and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the product of the present invention, the following is a brief introduction to the drawings of the present invention. The drawings and the following specific embodiments are used to explain the present invention, but do not constitute a limitation of the present invention.

[0020] Figure 1 XRD spectrum of the magnetic waste slag of Example 1. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0023] The strains selected by the present invention, Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans, Acidithiobacillus sulfooxidans, Thermophilic iron-oxidizing bacteria, Acidithiobacillus acidophilus and Thermophilic acidophilic archaea, are all purchased from China Center for Type Culture Collection.

[0024] The constant temperature oscillator selected in the embodiment of the present invention is a HZQ-QG type constant temperature oscillating incubator.

[0025] The concentrations of the components in the 9K medium used in the present invention are (NH 4 ) 2 SO 4 3g / L, K 2 HPO 4 0.5g / L, MgSO 4 7H 2 O 0.5g / L, Ca(NO 3 ) 2 0.01g / L, KCl 0.1g / L, FeSO 4 7H 2 O 44.2g / L.

[0026] The arsenic-containing gold ore used in the embodiment of the present invention has the following element composition: Au 40.19 g / t, Ag 19.21 g / t, Cu 0.5%, Fe 28.51%, S1 9.24%, As 8.23%, Sb 0.72%, C 2.13%, Ca 3.28%, Mg 1.25%, A1 8.26%, Si 26.17%, and other components 1.68%. The arsenic-containing gold ore used is only used as an example, and does not limit the content of each component of the arsenic-containing gold ore.

[0027] Example 1

[0028] (1) The ferrocyanide tailings were mixed evenly with the reduced coal powder, the amount of coal powder was controlled to 25%, the roasting temperature was 850°C, and the roasting time was 0.5 h under nitrogen atmosphere to obtain magnetic waste residue containing 5% residual carbon; (2) The bacterial solution containing iron-oxidizing Leptospirillum was inoculated into 9K culture medium, the volume ratio of the bacterial solution to the 9K culture medium was 1:10, and the bacterial concentration in the initial bacterial solution was 2.0×10 8 / ml, adjust the pH value to 1.0 and place it in a constant temperature shaker for culture, control the temperature at 40 ° C, the speed at 120 rpm, and the culture time for 10 days; (3) the arsenic gold ore and the magnetic waste residue obtained in step (1) are mixed in a mass ratio of 1:1, and after grinding, the powder with a particle size of ≤38 μm is screened out, which accounts for 90% of the total mass of the powder, and the powder is added to the culture solution to prepare a slurry, the slurry mass concentration is 20%, the pH value is adjusted to 2.0, the temperature is 35 ° C, and the leaching time is 15 days. After the biological leaching is completed, the magnetic waste residue is first magnetically separated from the leaching system with a magnet, and the magnetic waste residue is recycled after washing and drying, and the biological leaching residue is subjected to cyanide gold extraction. Comparative Example 1 completes step (2) and step (3) without adding magnetic waste residue, and other conditions are the same as Example 1. The experimental results show that the arsenic removal rate of Example 1 can be increased by 16%, and the gold recovery rate is increased by 23%. After the magnetic waste residue was recycled for 5 times, the arsenic removal rate and gold recovery rate only decreased by 0.64% and 0.25%, respectively.

[0029] Example 2

[0030] (1) The iron-containing sulfuric acid slag and the reduced coal powder were mixed evenly, the coal powder dosage was controlled to be 1%, the roasting temperature was 550°C, and the roasting time was 3 hours under nitrogen atmosphere to obtain magnetic waste slag containing 0.1% residual carbon; (2) The bacterial solution containing thermophilic iron bacteria was inoculated into 9K culture medium, the volume ratio of the bacterial solution to the 9K culture medium was 1:20, and the bacterial concentration in the initial bacterial solution was 8.0×10 8 / ml, adjust the pH value to 2.0 and place it in a constant temperature shaker for culture, control the temperature to 60 ° C, the speed to 350 rpm, and the culture time to 1 day; (3) the arsenic gold ore and the magnetic waste residue obtained in step (1) are mixed in a mass ratio of 1:0.01, and after grinding, the powder with a particle size of ≤38 μm is screened out, accounting for 60% of the total mass of the powder, and the powder is added to the culture solution to prepare a slurry, the slurry mass concentration is 1%, the pH value is adjusted to 1.0, the temperature is 55 ° C, and the leaching time is 2 days. After the biological leaching is completed, the magnetic waste residue is first magnetically separated from the leaching system by a magnet, and the magnetic waste residue is recycled after washing and drying, and the biological leaching residue is subjected to cyanide gold extraction. Comparative Example 2 completes step (2) and step (3) without adding magnetic waste residue, and other conditions are the same as Example 2. The experimental results show that the arsenic removal rate of Example 2 can be increased by 22%, and the gold recovery rate is increased by 26%. After the magnetic waste residue was recycled for 5 times, the arsenic removal rate and gold recovery rate only decreased by 0.23% and 0.11%, respectively.

[0031] Example 3

[0032] (1) The zinc leaching residue was mixed with the reduced coal powder, the amount of coal powder was controlled to be 11%, the roasting temperature was 595°C, and the roasting time was 2.5 h under nitrogen atmosphere to obtain magnetic waste residue containing 0.15% residual sulfur; (2) The bacterial solution containing ferrooxidans, thermosiderophilic iron bacteria and acidosulfobacillus was inoculated into 9K culture medium, the volume ratio of the bacterial solution to the 9K culture medium was 1:16, and the bacterial concentration in the initial bacterial solution was 3.2×10 8 / ml, adjust the pH value to 1.5 and place it in a constant temperature shaker for culture, control the temperature to 49 ° C, the speed to 155 rpm, and the culture time to 5.5 days; (3) the arsenic gold ore and the magnetic waste residue obtained in step (1) are mixed at a mass ratio of 1:0.26, and the powder with a particle size of ≤38 μm is screened out after grinding, accounting for 77% of the total mass of the powder, and the powder is added to the culture solution to prepare a slurry, the slurry mass concentration is 3.9%, the pH value is adjusted to 1.3, the temperature is 46 ° C, and the leaching time is 6.5 days. After the biological leaching is completed, the magnetic waste residue is first magnetically separated from the leaching system by a magnet, and the magnetic waste residue is recycled after washing and drying, and the biological leaching residue is subjected to cyanide gold extraction. Comparative Example 3 completes step (2) and step (3) without adding magnetic waste residue, and other conditions are the same as Example 3. The experimental results show that the arsenic removal rate of Example 3 can be increased by 18%, and the gold recovery rate is increased by 16%. After the magnetic waste residue was recycled for 5 times, the arsenic removal rate and gold recovery rate only decreased by 0.39% and 0.43%, respectively.

[0033] Example 4

[0034] (1) The iron alum slag and the reduced coal powder were mixed evenly, the coal powder dosage was controlled to 19%, the roasting temperature was 823°C, and the roasting time was 1.5 h under nitrogen atmosphere to obtain magnetic waste slag containing 4.7% residual sulfur; (2) The bacterial solution containing the thermoacidophilic archaea was inoculated into the 9K culture medium, the volume ratio of the bacterial solution to the 9K culture medium was 1:18, and the bacterial concentration in the initial bacterial solution was 7.8×10 8 / ml, adjust the pH value to 1.7 and place it in a constant temperature shaker for culture, control the temperature to 52 ° C, the speed to 234 rpm, and the culture time to 8 days; (3) the arsenic gold ore and the magnetic waste residue obtained in step (1) are mixed in a mass ratio of 1:0.75, and after grinding, the powder with a particle size of ≤38 μm is screened out, accounting for 69% of the total mass of the powder, and the powder is added to the culture solution to prepare a slurry, the slurry mass concentration is 11%, the pH value is adjusted to 1.8, the temperature is 45 ° C, and the leaching time is 10 days. After the biological leaching is completed, the magnetic waste residue is first magnetically separated from the leaching system by a magnet, and the magnetic waste residue is recycled after washing and drying, and the biological leaching residue is subjected to cyanide gold extraction. Comparative Example 4 completes step (2) and step (3) without adding magnetic waste residue, and the other conditions are the same as those of Example 4. After the magnetic waste residue is recycled for 5 times, the arsenic removal rate and gold recovery rate only decrease by 0.16% and 0.09%, respectively.

[0035] According to the experimental results of the embodiment, the method can significantly improve the arsenic removal rate and gold leaching rate of arsenic-containing gold ore, and can turn waste into treasure and make full use of iron-containing waste residue. The modified waste residue can be reused, the economic cost is low, and it has significant economic, social and environmental benefits. Figure 1 As shown, it can be seen from the XRD data that the modified iron-containing waste slag has successfully achieved mineral phase transformation and formed ferromagnetic iron oxide.

[0036] Finally, it should be noted that the above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any person skilled in the art can use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste residue, characterized in that: The method comprises the following steps: S1. Magnetization of waste slag: Mix the iron-containing waste slag and reduced coal powder evenly, and carry out magnetization roasting under controlled conditions to obtain magnetic waste slag. S2. Bacterial culture: inoculate the bacterial solution into 9K culture medium, adjust the pH value and culture in a constant temperature shaker to obtain the culture solution. S3. Enhanced leaching: Grind the arsenic-containing gold ore and magnetic waste slag powder and add them to the culture solution to make slurry, and control the conditions for constant temperature biological leaching. S4. Material separation: After the bioleaching is completed, the magnetic waste residue is first separated from the leaching system by magnets, and the magnetic waste residue is recycled after washing and drying. The arsenic content in the bioleaching solution of arsenic-containing gold ore is tested and the arsenic removal rate is calculated, and the bioleaching residue is subjected to cyanide gold extraction.

2. The method of enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste slag as claimed in claim 1, characterized in that: The iron-containing waste slag described in step S1 is one of iron-containing sulfuric acid slag, iron-containing cyanide tailings, zinc leaching slag, and iron alum slag.

3. The method of enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste slag as claimed in claim 1, characterized in that: The magnetization roasting conditions described in step S1 are: coal powder dosage 1-25%, roasting temperature 550-850° C., roasting time 0.5-3 h, and roasting atmosphere is nitrogen.

4. A method for enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste slag as claimed in claim 1, characterized in that: The magnetic waste slag described in step S1 contains residual carbon or residual sulfur, and the mass fraction of the residual carbon or residual sulfur is 0.1% to 5%.

5. The method of enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste slag as claimed in claim 1, characterized in that: The bacteria contained in the bacterial solution described in step S2 are one or more of Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans, Acidithiobacillus sulfooxidans, Thermosiderosinophilic Bacillus, Acidithiobacillus sulfooxidans and Thermoacidophilic Archaea.

6. The method of enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste slag as claimed in claim 1, characterized in that: The composition of the 9K culture medium described in step S2 is: (NH4)2SO4 3g / L, K2HPO4 0.5g / L, MgSO4·7H2O 0.5g / L, Ca(NO3)2 0.01g / L, KCl 0.1g / L, FeSO4·7H2O 44.2g / L.

7. The method of enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste slag as claimed in claim 1, characterized in that: The inoculation volume in step S2 is 1:(10-20) according to the volume ratio of bacterial solution to 9K medium, and the bacterial concentration in the initial bacterial solution is 2.0×10 8 / ml~8.0×10 8 Pieces / mL.

8. The method of enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste slag as claimed in claim 1, characterized in that: The shaking incubation conditions described in step S2 are: pH value 1.0-2.0, temperature 40-60° C., rotation speed 120-350 rpm, and incubation time 1-10 days.

9. The method of enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste slag as claimed in claim 1, characterized in that: The mass ratio of the arsenic-containing gold ore and the magnetic waste slag powder in step S3 is 1:(0.01-1), the size of the ground arsenic-containing gold ore and magnetic waste slag powder is that the part with a particle size of ≤38μm accounts for 60-90% of the total mass of the powder, and the mass concentration of the slurry is 1-20%.

10. The method of enhancing the bioleaching of arsenic-containing gold ore using iron-containing waste slag as claimed in claim 1, characterized in that: The bioleaching conditions in step S3 are pH 1.0-2.0, temperature 35-55° C., and leaching time 2-15 days.

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