A method for source inhibition of mine acid waste generation

Abstract

The application discloses a method for inhibiting generation of mine acid wastewater from a source, and the method comprises the following steps: adding a substance containing monovalent cations into waste rock of a mine, and controlling the pH of the reaction to be 1-2.5 by using a pH regulator. In the reaction pH range of 1-2.5, the monovalent cations are used to react with high-iron ions and sulfate ions generated by oxidation of pyrite in the waste rock to generate jarosite precipitates. The generated jarosite precipitates are adsorbed to the surface of the oxidized pyrite and the unoxidized pyrite, a dense protective film is formed, the further oxidation of the pyrite is inhibited, and the purpose of inhibiting generation of the acid wastewater from the source is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of mine wastewater treatment, and in particular to a method for suppressing the generation of mine acid wastewater at the source. Background Art

[0002] Currently, acid mine drainage is recognized as the primary environmental issue in the mining industry. Due to its low pH and high concentration of heavy metal ions, acid mine drainage seriously pollutes water and land resources, harming the ecological environment and endangering human health.

[0003] The source of acid mine drainage (AMD) is pyrite oxidation. During the mining and utilization of mineral resources, pyrite associated with the target mineral is exposed to air or water. Through a series of biochemical oxidation reactions, it produces high iron ions and sulfuric acid, which further dissolve coexisting acid-soluble metal minerals, contaminating groundwater or surface water to form AMD with a low pH and containing Fe and various heavy metal ions. Therefore, inhibiting pyrite oxidation can control the generation of AMD at the source.

[0004] At present, the treatment methods of acid mine wastewater are mainly divided into end-of-pipe treatment and source treatment. End-of-pipe treatment mainly includes neutralization method, sulfide precipitation, biological reduction method, etc., and source treatment mainly includes fungicide method and covering method.

[0005] CN102689935A discloses a method for terminal treatment of acid mine wastewater, which uses adsorbents to treat acid mine wastewater, but the adsorbent saturated with adsorption needs to be subsequently treated. CN101628773A discloses a process for treating acid mine wastewater containing high concentrations of copper and iron, which treats acid mine wastewater through neutralization and iron removal, biological sulfidation and biological purification, and is suitable for treating acid mine wastewater containing high concentrations of copper and iron generated in the production process of copper sulfide mines. CN110407414A discloses a method for treating acid mine wastewater, which treats acid mine wastewater through oxidation precipitation and neutralization treatment. The method completes Fe removal before neutralization. 2+ Oxidation improves the Fe extraction rate and ensures effective treatment of acid mine drainage. No acid treatment plant is required, and routine maintenance is simple: only regular addition of oxygen to slowly release the reagent and regular discharge of sludge are required. This method offers low operating costs, safe operation, and widespread practicality within this technical field.

[0006] CN111252873A discloses a method for suppressing the source of acid mine wastewater, which involves adding fluorine-containing substances to waste rocks. By utilizing the synergistic effect of fluorine-containing substances in dissolving fluorine ions in biological and chemical aspects, the amount of fluorine-containing substances added and the particle size are reasonably controlled to release fluorine ions in the water body. By controlling the activity of microorganisms and suppressing the potential of the system solution, the purpose of low cost, long-term effect, and source-control of acidic wastewater generation is achieved. However, the neutralization method has the problem of a large amount of neutralized slag, the sulfide precipitation method has the safety and environmental problems of H2S generation, and the biological reduction method has the problems of a long treatment cycle and a small treatment volume. The bactericide method has the problems of self-decomposition of the bactericide, the short-term antibacterial effect, and high environmental protection requirements. The previous covering method has the problems of large investment and limited sources of covering materials. All of the above defects have greatly limited the practical application of these methods. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the present invention aims to provide a method for inhibiting the generation of acid mine wastewater at the source.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for suppressing the generation of acid mine drainage at the source comprises adding a substance containing monovalent cations to waste rock in the mine, controlling the reaction pH to 1-2.5 using a pH regulator, causing the monovalent cations to react with ferric ions and sulfate ions produced by oxidation of pyrite in the waste rock to form an ferroalloy precipitate. The generated ferroalloy precipitate is adsorbed onto the surfaces of oxidized and unoxidized pyrite to form a dense protective film, thereby suppressing further oxidation of the pyrite.

[0010] The monovalent cations include K + 、Na + NH4 + Any one or more of the following;

[0011] The amount of the substance containing monovalent cations added is such that the molar ratio of the dissolved monovalent cations to the oxidized pyrite in the waste rock is greater than 1:3;

[0012] The oxidation rate of pyrite in waste rock is ≥0.1%.

[0013] When the monovalent cation is K + The pH range of the reaction is 1-2.5. When the monovalent cation is Na + When the pH of the reaction is 1.5-2.5, when the monovalent cation is NH4 + When the reaction pH is 1.8-2.5.

[0014] Furthermore, the substance containing monovalent cations includes one or a combination of two or more of sodium chloride, potassium chloride, ammonium chloride, sodium sulfate, potassium sulfate, ammonium sulfate, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium bicarbonate, sodium hydroxide, potassium hydroxide, ammonia water, sodium fluoride, potassium fluoride, ammonium fluoride, and minerals containing monovalent cations.

[0015] Furthermore, the mineral containing monovalent cations includes one or a combination of two or more of sylvite, carnallite, sylvite magnesium sulfate, anhydrous potassium sulfate, potassium sulfate, soft potassium sulfate, polyhalite, alunite, potassium feldspar, biotite, phlogopite, muscovite, lepidolite, potassium feldspar, plagioclase, microcline, illite, vermiculite, montmorillonite, albite, table salt, saltpeter, soda ash, ammonium-containing illite, ammonium-containing vermiculite, ammonium-containing montmorillonite, and ammonium-containing kaolinite.

[0016] Furthermore, the pH regulator includes one or a combination of two or more of calcium oxide, calcium carbonate, calcium hydroxide, sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, ammonium carbonate, ammonium bicarbonate and ammonia water.

[0017] Furthermore, the monovalent cation-containing substance and pH regulator include artificial synthetic substances and / or natural minerals.

[0018] Furthermore, the monovalent cation-containing substance and pH regulator are added in the form of solid and / or liquid.

[0019] Furthermore, the monovalent cation-containing substance and pH regulator are added in one or more ways, including directly mixing with the waste rock, directly placing on the surface of the waste rock, spraying or dripping onto the waste rock in the form of a spray liquid.

[0020] Furthermore, the waste rock includes ore with a grade below the threshold that is stripped during mining, ore with a grade below the threshold that is eliminated during mining and dressing, unused ore exposed in mining pits, and leaching residue after leaching the target mineral.

[0021] The beneficial effect of the present invention is that: within the reaction pH range of 1-2.5, the present invention utilizes monovalent cations to react with ferric ions and sulfate ions generated by oxidation of pyrite in waste rock to generate ferrocyanide precipitates, and the generated ferrocyanide precipitates are adsorbed onto the surfaces of oxidized pyrite and unoxidized pyrite to form a dense protective film, which can inhibit further oxidation of pyrite and achieve the purpose of inhibiting the generation of acidic wastewater from the source. DETAILED DESCRIPTION

[0022] The present invention will be further described below. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0023] Example 1

[0024] This embodiment provides a method for suppressing the generation of acid mine drainage at the source, by adding a substance containing monovalent cations and a pH regulator to waste rock. The waste rock is low-grade chalcopyrite ore with a pyrite mass content of 5.1% and a pyrite oxidation rate of 0.1%. The substance containing monovalent cations is sodium sulfate, and the amount of sodium sulfate added satisfies the molar ratio of sodium ions to oxidized pyrite in the waste rock of 1.0:3. The pH regulator is sodium hydroxide, which regulates the pH of the reaction to 1.5. Sodium sulfate is added by dissolving it in a spray liquid, which is an acidic leachate with a pH of 0.8. The spraying method is cyclic dripping. After 7 days of testing, the pyrite oxidation rate was 6.2%.

[0025] Example 2

[0026] This example provides a method for suppressing the generation of acid mine drainage at the source. A substance containing monovalent cations and a pH regulator are added to waste rock. The waste rock is low-grade chalcopyrite ore with a pyrite mass content of 5.1% and a pyrite oxidation rate of 0.1%. The substance containing monovalent cations is potassium sulfate, added in an amount that achieves a molar ratio of potassium ions to oxidized pyrite in the waste rock of 1:3. The pH regulator is sodium hydroxide, which regulates the reaction pH to 1.0. Potassium sulfate is added by dissolving it in a spray solution, which is an acidic leachate with a pH of 0.8. The spraying method is a cyclic drip method. After 7 days of testing, the pyrite oxidation rate was 4.1%.

[0027] Example 3

[0028] This embodiment provides a method for suppressing the generation of acid mine drainage at the source, which includes adding a substance containing monovalent cations and a pH regulator to waste rock.

[0029] The waste rock was low-grade chalcopyrite, with a pyrite mass content of 5.1% and a pyrite oxidation rate of 0.1%. The monovalent cation-containing substance was ammonium sulfate, added in an amount that maintained a molar ratio of ammonium ions to oxidized pyrite in the waste rock of 1:3. Sodium hydroxide was used as a pH regulator, adjusting the reaction pH to 1.8. The ammonium sulfate was added by dissolving it into the spray solution, which was an acidic leachate with a pH of 0.8. The spraying method was a cyclic drip method. After seven days of testing, the pyrite oxidation rate was 5.3%.

[0030] Example 4

[0031] The only difference between this example and Example 1 is that the pH of the reaction is controlled to 2.0. After 7 days of testing, the pyrite oxidation rate is 5.5%.

[0032] Example 5

[0033] The only difference between this embodiment and embodiment 1 is that the pH of the reaction is controlled to 2.5. After 7 days of testing, the pyrite oxidation rate is 4.8%.

[0034] Example 6

[0035] The only difference between this embodiment and embodiment 1 is that the molar ratio of the added sodium ions to the oxidized pyrite in the waste rock is 1.5:3. After 7 days of testing, the pyrite oxidation rate is 5.3%.

[0036] Example 7

[0037] The only difference between this example and Example 1 is that the pH of the reaction is controlled to 2.0 and the molar ratio of the added sodium ions to the oxidized pyrite in the waste rock is 1.5:3. After 7 days of testing, the pyrite oxidation rate is 3.9%.

[0038] Example 8

[0039] The only difference between this embodiment and embodiment 1 is that the pH control agent is calcium oxide. After 7 days of testing, the pyrite oxidation rate is 6.3%.

[0040] Example 9

[0041] The only difference between this embodiment and embodiment 1 is that sodium sulfate is added by directly mixing it into the waste rock. After 7 days of testing, the pyrite oxidation rate is 6.1%.

[0042] Comparative Example 1

[0043] The difference from Example 1-9 is that no monovalent cation-containing substance and pH regulator were added. After 7 days of testing, the pyrite oxidation rate was 15.5%.

[0044] The results of the above examples and comparative examples show that the methods of Examples 1-9 add monovalent cations (K + 、Na + NH 4+ ) substances and pH regulators are used to control the reaction pH range within 1-2.5, and monovalent cations are used to react with ferric ions and sulfate ions produced by the oxidation of pyrite in the waste rock to form ferroalloy precipitates. The generated ferroalloy precipitates are adsorbed onto the surfaces of oxidized pyrite and unoxidized pyrite to form a dense protective film, which can inhibit the further oxidation of pyrite and achieve the purpose of inhibiting the generation of acidic wastewater from the source.

[0045] Those skilled in the art can make various corresponding changes and modifications based on the above technical solutions and concepts, and all of these changes and modifications should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for suppressing the generation of acid mine drainage at the source, characterized in that: Adding substances containing monovalent cations to the waste rock of the mine, and using a pH regulator to control the reaction pH to 1-2.5, the monovalent cations react with the ferric ions and sulfate ions produced by the oxidation of pyrite in the waste rock to form a ferroalloy precipitate. The generated ferroalloy precipitate is adsorbed onto the surface of oxidized and unoxidized pyrite, forming a dense protective film that inhibits further oxidation of the pyrite. The monovalent cations include K + 、Na + NH4 + Any one or more of the following; The amount of the substance containing monovalent cations added is such that the molar ratio of the dissolved monovalent cations to the oxidized pyrite in the waste rock is greater than 1:3; The oxidation rate of pyrite in waste rock is ≥0.1%; When the monovalent cation is K + The pH range of the reaction is 1-2.

5. When the monovalent cation is Na + When the pH of the reaction is 1.5-2.5, when the monovalent cation is NH4 + When the reaction pH is 1.8-2.5; The monovalent cation-containing substance and pH regulator are added by dripping onto the waste rock in a circulating dripping manner.

2. The method according to claim 1, characterized in that The substance containing monovalent cations includes one or a combination of two or more of sodium chloride, potassium chloride, ammonium chloride, sodium sulfate, potassium sulfate, ammonium sulfate, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium bicarbonate, sodium hydroxide, potassium hydroxide, ammonia water, sodium fluoride, potassium fluoride, ammonium fluoride, and minerals containing monovalent cations.

3. The method according to claim 2, characterized in that The mineral containing monovalent cations includes one or a combination of two or more of sylvite, carnallite, kainite, anhydrous kainite, kainite, soft kainite, polyhalite, alunite, biotite, phlogopite, muscovite, lepidolite, potassium feldspar, microcline, illite, albite, table salt, saltpeter, soda ash, ammonium-containing illite, ammonium-containing vermiculite, ammonium-containing montmorillonite, and ammonium-containing kaolinite.

4. The method according to claim 1, wherein The pH regulator includes one or a combination of two or more of calcium oxide, calcium carbonate, calcium hydroxide, sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, ammonium carbonate, ammonium bicarbonate and ammonia water.

5. The method according to claim 1, wherein The monovalent cation-containing substance and pH regulator include artificial synthetic substances and / or natural minerals.

6. The method according to claim 1, characterized in that The waste rock includes ore with a grade below the threshold that is stripped during mining, ore with a grade below the threshold that is eliminated during mining and dressing, unused ore exposed in mining pits, and leaching residue after leaching the target mineral.