Inorganic material for controlling oxidation acid production and iron ion release of high-sulfur and high-iron coal gangue and preparation method thereof

Abstract

The invention belongs to but not limited to the technical field of mine pollution treatment, and discloses an inorganic material for controlling oxidation acid production and iron ion release of high-sulfur and high-iron coal gangue and a preparation method of the inorganic material. The method comprises the following steps: uniformly mixing high-sulfur high-iron coal gangue with a certain particle size, a passivation material A and a passivation material B according to a certain mass ratio, wherein the high-sulfur high-iron coal gangue is easy to oxidize to produce acid, can release high-concentration ferrous ions or iron ions and has a certain particle size; and adding a proper amount of water into the mixed coal gangue to keep a certain humidity, and passivating for a period of time under the condition of normal temperature to obtain stabilized coal gangue. The method can effectively stabilize and control the pH environment of coal gangue initial oxidation acid production, inhibit the oxidation activity of oxidizing microorganisms such as sulfur bacteria and iron bacteria, and increase the inhibition of oxidation products on oxidation reaction; and the oxidized and dissolved-out released iron and manganese metal ions in the coal gangue can continuously and stably form a compound with a very low solubility product for in-situ passivation, so that the content of heavy metals such as Fe and Mn in the leachate is effectively reduced.

Description

Technical Field

[0001] The present invention belongs to, but is not limited to, the technical field of mine pollution control, and particularly relates to an inorganic material for controlling the oxidation of high-sulfur and high-iron coal gangue to produce acid and release iron ions, and a preparation method thereof. Background Art

[0002] Coal gangue is an industrial solid waste generated during coal mining, accounting for 15% - 20% of the total coal production. The large-scale exploitation and utilization of mineral resources have brought huge economic benefits while also having a serious impact on the ecological environment. Coal gangue mountains not only occupy a large amount of land, but the sulfur-containing gases and dust generated by their long-term accumulation will pollute the atmosphere. Even under the action of rain leaching, they will produce heavy metal pollutants rich in Fe, Mn, Cu, Zn, etc., polluting the surrounding water bodies and soil, resulting in soil degradation, a decrease in water acidity, and the death of aquatic animals and plants in the areas around coal mines. As one of the bulk solid wastes, strengthening the comprehensive treatment and resource utilization efficiency of coal gangue is of great significance for improving the effectiveness of mine ecological environment restoration and governance and alleviating the contradiction between mineral resource development and the ecological environment.

[0003] Traditional coal gangue treatment mainly involves the comprehensive treatment of coal gangue through engineering measures such as site clearing, retaining dams, leachate collection and storage systems, rain and sewage diversion and flood control systems, and rolling and covering with soil. Although the process technology is relatively mature and the technical difficulty is not high, the project volume is large, the construction requires a certain amount of time, and it only physically blocks the pollution of coal gangue, without achieving in-situ control of coal gangue pollutants and cannot fundamentally improve the ecological environment of the storage yard.

[0004] Therefore, a preparation method of an inorganic material for controlling the oxidation of high-sulfur and high-iron coal gangue to produce acid and release iron ions is needed. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides an inorganic material for controlling the oxidation of high-sulfur and high-iron coal gangue to produce acid and release iron ions, and a preparation method thereof.

[0006] The present invention is implemented as follows. A preparation method of an inorganic material for controlling the oxidation of high-sulfur and high-iron coal gangue to produce acid and release iron ions includes the following steps:

[0007] Step 1: Uniformly mix high-sulfur and high-iron coal gangue with a certain particle size that is easy to oxidize and produce acid and can release a relatively high concentration of ferrous ions or iron ions, passivation material A, and passivation material B in a certain mass ratio in sequence.

[0008] Step 2: Add an appropriate amount of water to the mixed coal gangue to maintain a certain humidity, and passivate for a period of time at normal temperature to obtain stabilized coal gangue.

[0009] Further, the coal gangue with a certain particle size is appropriately crushed by a machine so that its particle size range is 2 mm to 1 cm.

[0010] Further, the passivation material A is limestone, in which the content of CaCO3 is 85% to 95%, and after being crushed by a machine, it is sieved through a 10-25 mesh sieve.

[0011] Further, the addition amount of the passivation material A is 3% to 4% (w / w) of the dry weight of the coal gangue.

[0012] Further, the passivation material B is phosphogypsum, in which the content of CaSO4 is 70% to 80%, and after being crushed by a machine, it is sieved through a 10-25 mesh sieve.

[0013] Further, the addition amount of the passivation material B is 1% to 2% (w / w) of the dry weight of the coal gangue.

[0014] Further, an appropriate amount of water is added to the mixed coal gangue, and the addition amount of deionized water is 55% to 75% (v / w) of the dry weight of the coal gangue, and the moisture is replenished regularly to maintain this humidity.

[0015] Further, it is passivated for a period of time under normal temperature conditions, the temperature condition is 20-25 °C, and the passivation time is 5-30 d.

[0016] Another object of the present invention is to provide an inorganic material for controlling the oxidation and acid production and iron ion release of high-sulfur and high-iron coal gangue prepared by the preparation method of an inorganic material for controlling the oxidation and acid production and iron ion release of high-sulfur and high-iron coal gangue.

[0017] Combined with the above technical solutions and the solved technical problems, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0018] First, the present invention provides an inorganic material and method for controlling the oxidation and acid production and iron ion release of high-sulfur and high-iron coal gangue. The passivation materials limestone and phosphogypsum used in this method are both inorganic calcium-rich materials. The effective component CaCO3 in limestone can significantly increase the pH of coal gangue, effectively neutralize the acid generated by the oxidation of sulfide minerals in weathered coal gangue, inhibit the oxidation activity of oxidizing microorganisms such as sulfur bacteria and iron bacteria, and improve the redox environment of coal gangue. The effective component SO4 in phosphogypsum 2- can increase the inhibition of the oxidation reaction by the oxidation product (SO4 2- ). The combined application of limestone and phosphogypsum introduces a large amount of Ca 2+ which can adsorb and precipitate with SO4 2- to inhibit SO4 2-The release, while a large amount of oxidizing ions precipitate, and the formed Fe colloid system can adsorb metal ions such as Fe, Mn, Cu, Zn, etc., inhibiting the release and migration of metals, effectively increasing the acidity of the leaching solution of high-sulfur and high-iron coal gangue, and significantly reducing the content of heavy metals such as Fe and Mn in the leaching solution. The reasonable combination of the above components can give full play to various functions, thus quickly passivating high-sulfur and high-iron coal gangue and effectively controlling the release of pollutants in the coal gangue.

[0019] The present invention can effectively stabilize and control the pH environment of the initial acid production of coal gangue, inhibit the oxidation activity of oxidizing microorganisms such as sulfur bacteria and iron bacteria, increase the inhibition of the oxidation reaction by the oxidation product (SO4 2- ) and can continuously and stably form compounds with very low solubility products from the iron and manganese metal ions that have been oxidized and dissolved and released in the coal gangue for in-situ passivation, thereby effectively reducing the acidity and the content of heavy metals such as Fe and Mn in the leaching solution of high-sulfur and high-iron coal gangue, and laying a good foundation for the subsequent vegetation restoration and ecological treatment of the coal gangue yard. The raw materials used in the present invention are natural minerals and bulk industrial solid wastes, and the advantages are that the related materials are cheap and easily available, the sources are extensive, and the construction process is simple, the effect is remarkable, and the operability is strong.

[0020] Second, compared with other repair means, the technical solution of the present invention has a lower repair cost. The inorganic materials used are not only cheap and easily available, but also the construction process is simple and convenient for large-scale application. Especially by using phosphogypsum, a bulk solid waste, its resource utilization can be realized, thereby effectively reducing the cost of solid waste treatment and enhancing the economic benefits and commercial value of the overall project.

[0021] The present invention breaks through the technical prejudice of the traditional repair concept and realizes the soil-free repair of the coal gangue yard. It can be repaired without covering soil, which not only saves a large amount of precious soil and the time, energy and cost of related stripping, loading, unloading, transportation, laying, etc., but also greatly shortens the repair cycle, and can ensure the seed germination of the plants and the normal growth and development of the plants planted subsequently due to the lack of toxic effects caused by the introduction of toxic and harmful chemical passivators, providing a reliable guarantee for the in-situ control of pollution release and soil-free rapid ecological restoration of the coal gangue yard. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the preparation method of the inorganic material for controlling the acid production and iron ion release of high-sulfur and high-iron coal gangue provided by the embodiment of the present invention;

[0023] Figure 2 is a bar chart of the pH change of coal gangue after adding the passivation material provided by the embodiment of the present invention;

[0024] Figure 3 is a bar chart of the Eh change of coal gangue after adding the passivation material provided by the embodiment of the present invention;

[0025] Figure 4 It is a diagram showing the change in the occurrence form of Fe in coal gangue after adding a passivation material provided by an embodiment of the present invention;

[0026] Figure 5 It is a diagram showing the change in the occurrence form of Mn in coal gangue after adding a passivation material provided by an embodiment of the present invention;

[0027] Figure 6 It is a diagram showing the change in the occurrence form of Cr in coal gangue after adding a passivation material provided by an embodiment of the present invention;

[0028] Figure 7 It is a diagram showing the change in the occurrence form of Cu in coal gangue after adding a passivation material provided by an embodiment of the present invention;

[0029] Figure 8 It is a broken line diagram showing the change in Fe in the leachate of coal gangue after adding a passivation material provided by an embodiment of the present invention;

[0030] Figure 9 It is a broken line diagram showing the change in Mn in the leachate of coal gangue after adding a passivation material provided by an embodiment of the present invention;

[0031] Figure 10 It is a broken line diagram showing the change in Zn in the leachate of coal gangue after adding a passivation material provided by an embodiment of the present invention;

[0032] Figure 11 It is a broken line diagram showing the change in Cu in the leachate of coal gangue after adding a passivation material provided by an embodiment of the present invention;

[0033] Figure 12 It is a diagram of the plant growth of coal gangue after adding a passivation material in an application example of the present invention;

[0034] Figure 13 It is an effect diagram of the color improvement of the leachate of coal gangue after adding a passivation material in an application example of the present invention. Detailed implementation manners

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] As Figure 1 shown, an embodiment of the present invention provides a preparation method of an inorganic material for controlling the oxidation of high-sulfur and high-iron coal gangue to produce acid and release iron ions, including the following steps:

[0037] S1, uniformly mix high-sulfur and high-iron coal gangue with a certain particle size that is easy to oxidize and produce acid and can release a relatively high concentration of ferrous ions or iron ions with passivation material A and passivation material B in a certain mass ratio in sequence;

[0038] S2. Add an appropriate amount of water to the mixed coal gangue to maintain a certain humidity, and passivate it for a period of time under normal temperature conditions to obtain stabilized coal gangue.

[0039] High-sulfur and high-iron coal gangue contains relatively high contents of pyrite (FeS2) and other sulfide minerals. After exposure to air and moisture, it is prone to oxidation reactions, forming complex characteristic pollutants with strong acidity, high toxicity, and rich in heavy metals, and diffusing and migrating to the surrounding environment along with water bodies, etc. This process is usually catalyzed and accelerated by microorganisms (such as sulfur-oxidizing bacteria and iron-oxidizing bacteria), and under the coupled action of biogeochemistry, typical acid mine drainage (AMD) is formed, while triggering the secondary release of heavy metals in the surrounding water bodies and soil ecosystems and aggravating the environmental pollution load.

[0040] Passivation material A is usually an inorganic substance with alkalinity or reducibility, and its action principles include:

[0041] Acid-base neutralization to keep the coal gangue environment in the neutral or weakly alkaline range, thereby reducing the formation of acid mine drainage (AMD);

[0042] Through complexation or precipitation, the oxidized and dissolved and released Fe 2+ or Fe 3+ is separated from the aqueous solution in the form of poorly soluble compounds (such as iron hydroxide, iron phosphate, etc.), thereby reducing the mobility and bioavailability of iron ions;

[0043] The formed coating or covering layer can significantly reduce the penetration of oxygen and moisture, and reduce the oxidation rate of pyrite in the coal gangue.

[0044] Passivation material B is mainly used to inhibit the release of heavy metals such as iron ions during the oxidation process of coal gangue, and its main functions include:

[0045] Form a slightly soluble Ca and SO4 2- complex - gypsum precipitation, effectively reducing the dissolution of SO4 2- in the coal gangue, and at the same time precipitating a large number of oxidizing ions, changing the original redox system and inhibiting the dissolution of pollution components;

[0046] By changing the redox conditions on the mineral surface, reducing the activities of sulfur-oxidizing bacteria and iron-oxidizing bacteria, thereby inhibiting the biocatalyzed oxidation reaction;

[0047] Provide a buffering effect, stabilize the pH of the coal gangue, and inhibit the acidification reaction and the further progress of the catalytic oxidation of Fe 3+ under low pH conditions.

[0048] After mixing and adjusting the humidity, the coal gangue is in a suitable reaction environment. Passivation materials A and B gradually undergo physical and chemical reactions at room temperature, inhibiting the acidification process inside the coal gangue and reducing the release rate of iron ions. After a period of stabilization treatment, the oxidation reaction of the coal gangue tends to balance, and finally a stable passivation structure is formed, so that the coal gangue will not cause environmental pollution during subsequent landfill or resource utilization processes.

[0049] Further, the coal gangue with a certain particle size is appropriately crushed by a machine so that its particle size range is 2 mm to 1 cm.

[0050] Further, the passivation material A is limestone, in which the content of CaCO3 is 85% - 95%, and after being crushed by a machine, it is sieved through a 10 - 25 mesh sieve.

[0051] Further, the addition amount of the passivation material A is 3% - 4% (w / w) of the dry weight of the coal gangue.

[0052] Further, the passivation material B is phosphogypsum, in which the content of CaSO4 is 70% - 80%, and after being crushed by a machine, it is sieved through a 10 - 25 mesh sieve.

[0053] Further, the addition amount of the passivation material B is 1% - 2% (w / w) of the dry weight of the coal gangue.

[0054] Further, an appropriate amount of water is added to the mixed coal gangue, and the addition amount of deionized water is 55% - 75% (v / w) of the dry weight of the coal gangue, and the moisture is replenished regularly to maintain this humidity.

[0055] Further, it is passivated for a period of time under room temperature conditions, the temperature condition is 20 - 25 °C, and the passivation time is 5 - 30 d.

[0056] In the present invention, the coal gangue needs to be appropriately crushed before use to ensure that its particle size range is controlled within 2 mm to 1 cm to optimize the subsequent passivation reaction effect. A reasonable particle size distribution can provide a larger specific surface area, improve the contact efficiency of the passivation material, and enhance the ability to fix pollutants. At the same time, the crushed coal gangue can form a uniform pore structure, providing good conditions for the penetration and reaction of the passivation material.

[0057] The passivation material A uses limestone with a high CaCO3 content (85% - 95%), which is crushed and then screened through a 10 - 25 mesh sieve to achieve an appropriate particle size and improve its dispersibility in coal gangue. Its addition amount is set at 3% - 4% (w / w) of the dry weight of coal gangue, which can effectively neutralize the acidic environment, reduce the activity of heavy metals, and improve the passivation stability. The passivation material B is phosphogypsum (CaSO4 content 70% - 80%), which is also crushed and then screened through a 10 - 25 mesh sieve to enhance its solubility and passivation effect. Its addition amount is controlled at 1% - 2% (w / w) of the dry weight of coal gangue, which can stabilize the pH value and promote the precipitation and transformation of heavy metals to form insoluble minerals and improve the long - term stability.

[0058] To promote the full reaction between coal gangue and the passivation material, deionized water is added to the mixed coal gangue system. The addition amount of water is controlled at 55% - 75% (v / w) of the dry weight of coal gangue. The appropriate humidity can maintain the uniformity of the reaction medium and ensure the continuous progress of ion diffusion and chemical reactions. To avoid the influence of water loss in the system on the passivation effect, water needs to be replenished regularly during the experiment to ensure that the humidity is maintained within the set range and promote the stability and persistence of the passivation reaction.

[0059] The entire passivation process is carried out under normal temperature conditions (20 - 25°C) to ensure the controllability and stability of the reaction. The passivation time is set at 5 - 30 days, and this range can meet the different requirements of coal gangue compositions and pollutant contents. During this time, the passivation material fully reacts with the pollutants in the coal gangue, promoting heavy metal solidification, acid neutralization, and mineral transformation, improving the environmental safety of coal gangue, and finally forming a more stable passivation product, which is suitable for subsequent resource utilization or safe landfill.

[0060] Example 1:

[0061] The surface coal gangue from the coal gangue yard is collected and brought back to the laboratory. After removing plant residues and soil particles, it is naturally air - dried and screened through a 6 mm sieve for standby. Take 100 g of coal gangue and put it into a 250 mL beaker, add 3% (w / w) of limestone and 2% (w / w) of phosphogypsum and mix evenly, then add 60% deionized water (v / w) to keep the coal gangue at this humidity. After stabilizing for 5, 10, 15, and 30 d respectively in a (25 ± 1)°C constant temperature incubator, samples are taken for analysis. The samples are naturally air - dried, ground, and screened.

[0062] Example 2:

[0063] Collect the surface coal gangue from the coal gangue yard and bring it back to the laboratory. After removing plant residues and soil particles, air-dry it naturally and sieve it through a 6-mm sieve for standby. Take 100 g of coal gangue and put it into a 250-mL beaker. Add 3.5% (w / w) limestone and 1.5% (w / w) phosphogypsum and mix evenly. Add 60% deionized water (v / w) to keep the coal gangue at this humidity. After stabilizing for 5, 10, 15, and 30 d respectively in a constant temperature incubator at (25 ± 1) °C, take samples for analysis. Air-dry the samples naturally and grind and sieve them.

[0064] Example 3:

[0065] Collect the surface coal gangue from the coal gangue yard and bring it back to the laboratory. After removing plant residues and soil particles, air-dry it naturally and sieve it through a 6-mm sieve for standby. Take 100 g of coal gangue and put it into a 250-mL beaker. Add 4% (w / w) limestone and 1% (w / w) phosphogypsum and mix evenly. Add 60% deionized water (v / w) to keep the coal gangue at this humidity. After stabilizing for 5, 10, 15, and 30 d respectively in a constant temperature incubator at (25 ± 1) °C, take samples for analysis. Air-dry the samples naturally and grind and sieve them.

[0066] Figures 2 - 3 It shows that after adding the passivation material, the pH of the coal gangue increased significantly and the Eh decreased significantly. Compared with the control, after 30 d of passivation, the pH increased from 3.93 to 6.65, 6.80, and 6.95 respectively, with a maximum increase of 76.85%, and the Eh decreased from 204.4 mV to -22.6 mV, -19.2 mV, and -31.7 mV respectively, with a maximum decrease of 115.5%. Figures 3 - 6 F1, F2, F3, and F4 in it are acid-exchangeable state, reducible state, oxidizable state, and residual state respectively. It can be seen from the figure that after adding the passivation material, the acid-exchangeable state, reducible state, and oxidizable state of heavy metals Fe, Mn, Cr, and Cu in the coal gangue are transformed into the residual state, realizing the in-situ passivation of heavy metals. After 30 d of passivation, the residual states of Fe, Mn, Cr, and Cu in the coal gangue increased to 21.78% - 97.24%, 31.87% - 75.83%, 9.81% - 13.46%, and more than 100% of the control respectively.

[0067] Figures 7 - 10 It shows that the experimental results show that after passivation treatment, the heavy metal content in the leachate of coal gangue decreased significantly. Especially after 30 d of passivation, the release of metals such as Fe, Mn, Zn, and Cu was effectively inhibited, and the overall reduction was significant. At the same time, the acidity of the leachate was improved, and the migration ability of heavy metals decreased significantly, indicating that the present invention can stably solidify heavy metal pollutants in coal gangue, reduce its environmental risk, and achieve a long-term and effective passivation effect.

[0068] Application Example 1: Passivating high-sulfur and high-iron coal gangue with the passivation material of the present invention

[0069] (1) Experimental conditions and materials

[0070] Source of coal gangue: Collected from the waste yard of a coal mine, with a sulfur content of 3.8%, an iron content of 12.5%, and a pH of 2.5.

[0071] Passivation materials: 3% (w / w) limestone, 2% (w / w) phosphogypsum.

[0072] (2) Operating steps

[0073] 1. Crushing pretreatment: Crush the top 30 cm of the coal gangue to a particle size within 60 mm to improve the reaction rate of the materials.

[0074] 2. Uniform mixing: Mix uniformly according to a mass ratio of 100:5 (coal gangue: passivation material).

[0075] 3. Moisture regulation: Add an appropriate amount of water to maintain a moisture content of 60% to promote chemical and biological reactions.

[0076] 4. Stable cultivation: Stack for 30 days under normal temperature conditions and turn over once every 5 days to allow full reaction.

[0077] (3) Experimental results

[0078] After 30 days, the pH of the coal gangue increased from 2.5 to 6.8, and the acidity decreased significantly.

[0079] The contents of Fe, Mn, Zn, and Cu in the leachate decreased by >90%.

[0080] Miscanthus sinensis was planted in the test, and the emergence rate was >85% within 50 days, and the growth was good.

[0081] Application Example 2: Passivating high-sulfur and high-iron coal gangue using the passivation material of the present invention

[0082] (1) Experimental conditions and materials

[0083] Source of coal gangue: Collected from the waste yard of a coal mine, with a sulfur content of 3.8%, an iron content of 12.5%, and a pH of 2.5.

[0084] Passivation materials: 3.5% (w / w) limestone, 1.5% (w / w) phosphogypsum.

[0085] (2) Operating steps

[0086] 1. Crushing pretreatment: Crush the top 30 cm of the coal gangue to a particle size within 60 mm to improve the reaction rate of the materials.

[0087] 2. Uniform mixing: Mix uniformly according to a mass ratio of 100:5 (coal gangue: passivation material).

[0088] 3. Moisture regulation: Add an appropriate amount of water to maintain a moisture content of 60% to promote chemical and biological reactions.

[0089] 4. Stable cultivation: Stack for 30 days at room temperature and turn over once every 5 days to allow sufficient reaction.

[0090] (3) Experimental results

[0091] After 30 days, the pH of the coal gangue increased from 2.5 to 7.1, and the acidity decreased significantly.

[0092] The contents of Fe, Mn, Zn, and Cu in the leachate decreased by >90%.

[0093] Miscanthus was experimentally planted, and the germination rate was >90% within 50 days, and the growth was good.

[0094] Application Example 3: Passivating high-sulfur and high-iron coal gangue using the passivation material of the present invention

[0095] (1) Experimental conditions and materials

[0096] Source of coal gangue: Collected from the waste yard of a certain coal mine, with a sulfur content of 3.8%, an iron content of 12.5%, and a pH of 2.5.

[0097] Passivation material: 4% (w / w) limestone, 1% (w / w) phosphogypsum.

[0098] (2) Operating steps

[0099] 1. Crushing pretreatment: Crush the top 30 cm of the coal gangue to a particle size within 60 mm to improve the reaction rate of the material.

[0100] 2. Uniform mixing: Mix uniformly according to a mass ratio of 100:5 (coal gangue: passivation material).

[0101] 3. Moisture regulation: Add an appropriate amount of water to maintain a moisture content of 60% to promote chemical and biological reactions.

[0102] 4. Stable cultivation: Stack for 30 days at room temperature and turn over once every 5 days to allow sufficient reaction.

[0103] (3) Experimental results

[0104] After 30 days, the pH of the coal gangue increased from 2.5 to 7.0, and the acidity decreased significantly.

[0105] The contents of Fe, Mn, Zn, and Cu in the leachate decreased by >90%.

[0106] Miscanthus was experimentally planted, and the germination rate was >90% within 50 days, and the growth was good.

[0107] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be covered by the protection scope of the present invention.

Claims

1. A method for preparing an inorganic material for controlling oxidation of high-sulfur and high-iron coal gangue to generate acid and release iron ions, characterized in that: The following steps are involved: Step 1, high-sulfur and high-iron coal gangue with a certain particle size that is easily oxidized to produce acid and can release a high concentration of ferrous ions or ferric ions is uniformly mixed with passivation material A and passivation material B in a certain mass ratio; Step 2: Add a proper amount of water to the mixed coal gangue to maintain a certain humidity, and then passivate the mixture for a period of time at room temperature to obtain stabilized coal gangue.

2. The method for preparing an inorganic material for controlling oxidation of high-sulfur and high-iron coal gangue to generate acid and release iron ions as claimed in claim 1, characterized in that: The coal gangue with a certain particle size is appropriately crushed by a machine so that its particle size ranges from 2 mm to 1 cm.

3. The method for preparing an inorganic material for controlling oxidation of high-sulfur and high-iron coal gangue to generate acid and release iron ions as claimed in claim 1, characterized in that: The passivation material A is limestone, wherein the content of CaCO3 is 85% to 95%, and is crushed by a machine and passed through a 10 to 25 mesh sieve.

4. The method for preparing an inorganic material for controlling oxidation of high-sulfur and high-iron coal gangue to generate acid and release iron ions as claimed in claim 3, characterized in that: The addition amount of the passivation material A is 3% to 4% of the dry weight of the coal gangue.

5. The method for preparing an inorganic material for controlling oxidation of high-sulfur and high-iron coal gangue to generate acid and release iron ions as claimed in claim 1, characterized in that: The passivation material B is phosphogypsum, wherein the content of CaSO4 is 70% to 80%, and is crushed by a machine and then passed through a 10 to 25 mesh sieve.

6. The method for preparing an inorganic material for controlling oxidation of high-sulfur and high-iron coal gangue to generate acid and release iron ions as claimed in claim 5, characterized in that: The addition amount of the passivation material B is 1% to 2% of the dry weight of the coal gangue.

7. The method for preparing an inorganic material for controlling oxidation of high-sulfur and high-iron coal gangue to generate acid and release iron ions as claimed in claim 1, characterized in that: The mixed coal gangue is added with a proper amount of water, wherein the amount of deionized water added is 55% to 75% of the dry weight of the coal gangue, and water is regularly added to maintain the humidity.

8. The method for preparing an inorganic material for controlling oxidation of high-sulfur and high-iron coal gangue to generate acid and release iron ions as claimed in claim 1, characterized in that: The passivation is carried out for a period of time under the normal temperature conditions, the temperature condition is 20-25° C., and the passivation time is 5-30 days.

9. An inorganic material for controlling the oxidation of high-sulfur and high-iron coal gangue to produce acid and release iron ions, prepared by the method for preparing an inorganic material for controlling the oxidation of high-sulfur and high-iron coal gangue to produce acid and release iron ions as described in any one of claims 1 to 8.

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