Method for harmlessly treating coal gangue

Abstract

The invention relates to the technical field of resources and environment, in particular to a harmless treatment method for coal gangue. The harmless treatment method for the coal gangue comprises the following steps: preparing the coal gangue into coal gangue powder; adding the coal gangue powder and an additive into water to prepare a mixed material; introducing ozone mixed gas into the mixed material for oxidation, and then filtering to obtain desulfurized coal gangue powder; the additive is inorganic salt or acid; the inorganic salt is sodium sulfate, sodium bicarbonate, sodium carbonate, sodium chloride, magnesium sulfate, sodium persulfate, sodium nitrate, potassium permanganate or sodium silicate; the acid is hydrochloric acid, sulfuric acid or nitric acid. The method is green and environment-friendly in desulfurization process and high in economic benefit. The method has the advantages of low cost, short time and high desulfurization efficiency. By adopting the desulfurization process provided by the invention, under the condition of adding a small amount of additive (cocatalyst), the sulfur content in the coal gangue can be effectively reduced through simple one-time treatment.

Description

Technical Field

[0001] The invention relates to the technical field of resources and environment, and in particular to a method for harmless disposal of coal gangue. Background Art

[0002] At present, the methods for removing sulfur from coal gangue mainly include physical methods, chemical methods and microbial methods. Physical methods: mainly through physical coal preparation technology, such as jigging coal preparation, heavy medium coal preparation, chute coal preparation, shaking coal preparation, wind coal preparation, etc., to effectively remove inorganic sulfur (pyrite sulfur) from coal; this method is suitable for removing pyrite sulfur from coal, but the removal effect on organic sulfur is limited. Chemical methods: including alkaline treatment, oxidation method and solvent extraction; these methods can effectively desulfurize in the laboratory, but may face cost and technical difficulties in industrial applications. Microbial methods: using specific microorganisms, such as Thiobacillus, to remove sulfur from coal through chemical reactions in its metabolic process; this method is green and environmentally friendly, but there may be problems such as low desulfurization efficiency and long cycle.

[0003] Therefore, providing a method for efficiently removing sulfur from coal gangue with a simple process is what those skilled in the art have been working on. Summary of the invention

[0004] The purpose of the present invention is to provide a method for harmless disposal of coal gangue to solve the problems existing in the above-mentioned prior art. The method of the present invention has the advantages of simple process and high desulfurization rate.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for harmless disposal of coal gangue, comprising the following steps:

[0007] preparing the coal gangue into coal gangue powder;

[0008] Adding the coal gangue powder and additives into water to prepare a mixed material;

[0009] Passing ozone mixed gas into the mixed material for oxidation, and then filtering to obtain desulfurized coal gangue powder;

[0010] The additive is an inorganic salt or an acid;

[0011] The inorganic salt is sodium sulfate, sodium bicarbonate, sodium carbonate, sodium chloride, magnesium sulfate, sodium persulfate, sodium nitrate, potassium permanganate or sodium silicate;

[0012] The acid is hydrochloric acid, sulfuric acid or nitric acid.

[0013] In a preferred embodiment of the present invention, the gangue is prepared into gangue powder by mechanical crushing and screening; the particle size of the gangue powder is not greater than 3 mm.

[0014] In a preferred embodiment of the present invention, the liquid-to-solid ratio of the water to the coal gangue powder is 3:1 to 10:1.

[0015] In the present invention, the lower the liquid-to-solid ratio, the longer the oxidation time is required to achieve the same desulfurization effect; too high a liquid-to-solid ratio will increase the water consumption and water treatment costs, which is not conducive to large-scale utilization.

[0016] In a preferred embodiment of the present invention, when the additive is an inorganic salt, the addition amount of the inorganic salt is 0.05% to 2% of the mass of the coal gangue powder.

[0017] In a preferred embodiment of the present invention, when the additive is an acid, the amount of the acid added is such that the pH of the mixed material is 4-5.

[0018] In the present invention, if the proportion of the additive added is too high, a large amount of secondary salts will be formed during the oxidation process, which will hinder the contact between ozone and sulfide and affect the desulfurization efficiency. At the same time, adding additives will increase the cost of large-scale utilization. If the proportion of additives is too low, the desulfurization efficiency will be affected. Therefore, the present invention preferably limits the amount of additives to the above parameter range.

[0019] In a preferred embodiment of the present invention, the ozone mixed gas is a mixed gas of ozone and air.

[0020] In a preferred embodiment of the present invention, the volume concentration of ozone in the ozone mixed gas is 50% to 90%;

[0021] In the present invention, if the ozone volume concentration is too low, the oxidation time will be prolonged. The amount of ozone introduced is proportional to the desulfurization efficiency. However, if the amount introduced is too large, the residence time of ozone in the mixed material will be too long, and the ozone utilization rate will be low. If the amount introduced is too low, the diffusion of ozone in the mixed material will be affected.

[0022] In a preferred embodiment of the present invention, the oxidation time is 2 h to 6 h.

[0023] In the present invention, if the oxidation time is too short, the desulfurization effect of one oxidation is poor, and the number of desulfurization times will increase; if the oxidation time is too long, it is not conducive to the large-scale utilization of the method and will increase the cost of large-scale utilization. Therefore, the present invention preferably limits the oxidation time to the above parameter range.

[0024] The present invention also provides a method for improving the removal rate of sulfur in coal gangue. The sulfur in the coal gangue can be effectively removed by adopting the above-mentioned method for harmless disposal of coal gangue.

[0025] The present invention discloses the following technical effects:

[0026] The invention provides a method for harmless disposal of coal gangue, by which sulfur in the coal gangue can be effectively removed, and the desulfurization process of the method is green and environmentally friendly with high economic benefits.

[0027] The method of the present invention has the advantages of low cost, short time and high desulfurization efficiency. By adopting the desulfurization process of the present invention, under the condition of adding a small amount of additives (promoters), a simple one-time treatment can effectively reduce the sulfur content in the coal gangue by 50%-60%, and realize the harmless disposal of the coal gangue. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0031] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] The embodiment of the present invention provides a method for removing sulfur from coal gangue, comprising the following steps:

[0034] The gangue blocks are mechanically crushed to obtain gangue powder; then, the gangue powder is added to the clean water with a small amount of additives as the liquid phase, and then an ozone mixed gas is introduced into the mixed system to oxidize the sulfur in the gangue to form sulfate ions which are dissolved and transferred to the liquid phase for removal, and then filtered to obtain desulfurized gangue powder.

[0035] The mechanical crushing is to break the gangue into large particles and then use a crusher to crush them.

[0036] In the method of the present invention, the total sulfur in the coal gangue serves as a medium for the oxidation reaction.

[0037] The filtrate obtained after oxidation is filtered and recycled after being neutralized with acid or alkali to remove impurities.

[0038] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0039] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0040] Example 1: Coal gangue in a certain area (total sulfur content is 2.8%)

[0041] The gangue is mechanically crushed by a pulverizer so that it can all pass through a 3mm sieve to obtain gangue powder; then, the gangue powder is added to water at a liquid-solid ratio of 8:1 (mL / g) to prepare a mixture, and sodium persulfate accounting for 0.2% of the mass of the gangue powder is added to the mixture. After mixing evenly, 270g of the mixture is filled into a glass instrument; a mixed gas of ozone and air with a volume concentration of 70% is continuously introduced into the glass instrument for oxidation, the flow rate of the mixed gas is 2L / min, and the oxidation time is 5h; finally, the desulfurized gangue powder is obtained by filtration. The total sulfur content of the desulfurized gangue powder is 1.27%, and the desulfurization rate reaches 55%.

[0042] It has been proven that this method can remove both inorganic sulfur and organic sulfur in coal gangue.

[0043] Example 2: Coal gangue in a certain area (total sulfur content is 2.8%)

[0044] The gangue is mechanically crushed by a pulverizer so that it can all pass through a 3mm sieve to obtain gangue powder; then, the gangue powder is added to water at a liquid-solid ratio of 6:1 to prepare a mixed material, specifically: 14kg of the mixed material is loaded into a reactor, 84L of clean water is added to the material, and then sodium bicarbonate accounting for 0.2% of the mass of the gangue powder is added. After mixing evenly, a mixed gas of ozone and air with a volume concentration of 80% is continuously introduced into the reactor for oxidation, the flow rate of the mixed gas is 60L / min, and the oxidation time is 2h; finally, the desulfurized gangue powder is obtained by filtration. The total sulfur content of the desulfurized gangue powder is 1.9%, and the desulfurization rate reaches 32%.

[0045] It has been proven that this method can remove both inorganic sulfur and organic sulfur in coal gangue.

[0046] Example 3: Coal gangue in a certain area (total sulfur content is 2.8%)

[0047] The gangue is mechanically crushed by a pulverizer so that it can all pass through a 3mm sieve to obtain gangue powder; then, the gangue powder is added to water at a liquid-solid ratio of 10:1 to prepare a mixture, and 330g of the mixture is loaded into a glass instrument with a gas distributor; sodium bicarbonate accounting for 0.2% of the mass of the gangue powder is added to the mixture, and after mixing evenly, a mixed gas of ozone and air with a volume concentration of 80% is continuously introduced into the glass instrument for oxidation, the flow rate of the mixed gas is 2L / min, and the oxidation time is 5h; finally, the desulfurized gangue powder is obtained by filtration. The total sulfur content of the desulfurized gangue powder is 1.2%, and the desulfurization rate reaches 57%.

[0048] It has been proven that this method can remove both inorganic sulfur and organic sulfur in coal gangue.

[0049] Example 4: Coal gangue in a certain area (total sulfur content is 9.0%)

[0050] The gangue is mechanically crushed by a pulverizer so that it can all pass through a 3mm sieve to obtain gangue powder; then, the gangue powder is added to water at a liquid-solid ratio of 5:1 to prepare 180g of a mixture, dilute sulfuric acid is added to the mixture to make the pH of the system 4-5, and after uniform mixing, a mixture of ozone and air with a volume concentration of 70% is continuously introduced into a glass apparatus for oxidation, the flow rate of the mixture is 1.5L / min, and the oxidation time is 4h; finally, desulfurized gangue powder is obtained by filtration. The total sulfur content of the desulfurized gangue powder is 5.4%, and the desulfurization rate reaches 40%.

[0051] It has been proven that this method can remove both inorganic sulfur and organic sulfur in coal gangue.

[0052] Example 5: Coal gangue in a certain area (total sulfur content is 2.8%)

[0053] The gangue is mechanically crushed by a pulverizer so that it can all pass through a 3mm sieve to obtain gangue powder; then, the gangue powder is added to water at a liquid-solid ratio of 7:1 to prepare a 240g mixture, and sodium persulfate accounting for 0.2% of the mass of the gangue powder is added to the mixture. After mixing evenly, a mixed gas of ozone with a volume concentration of 80% and air is continuously introduced into a glass instrument for oxidation, the flow rate of the mixed gas is 2L / min, and the oxidation time is 5h; finally, the desulfurized gangue powder is obtained by filtration. The total sulfur content of the desulfurized gangue powder is 1.2%, and the desulfurization rate reaches 57%.

[0054] It has been proven that this method can remove both inorganic sulfur and organic sulfur in coal gangue.

[0055] Comparative Example 1: Coal gangue from a certain area (total sulfur content is 9.0%)

[0056] The gangue was mechanically crushed by a pulverizer so that it could all pass through a 200-mesh screen to obtain gangue powder; then, the gangue powder was added to clean water at a liquid-solid ratio of 4:1 to prepare 150g of a mixed material, and hydrogen peroxide accounting for 1% of the volume of the clean water was added to the mixed material, mixed evenly, and stirred for 5 hours; finally, desulfurized gangue powder was obtained by filtration. The total sulfur content of the desulfurized gangue powder was 8.62%, and the desulfurization rate was 4.2%.

[0057] On the basis of Comparative Example 1, the present invention also verifies the cases where the addition amount of hydrogen peroxide is 5% and 10% (that is, only the addition amount of hydrogen peroxide is adjusted, and the other steps and parameters are the same as those in Comparative Example 1; wherein the case where the addition amount of hydrogen peroxide is 10% is subjected to heating treatment during the stirring process), and the results show that the desulfurization effects are not good, and the desulfurization rates are 2% and 7%, respectively.

[0058] Even if sodium persulfate accounting for 0.2% of the coal gangue powder is added on the basis of Comparative Example 1, and the remaining steps and parameters are the same as those of Comparative Example 1, the desulfurization rate is only 4.5%, and the desulfurization effect is poor.

[0059] By comparing the embodiments and comparative examples, it can be seen that the effect of removing sulfur from coal gangue by hydrogen peroxide in comparative example 1 is not good. This may be because the simple oxidation performance cannot effectively remove the sulfur from coal gangue. For the removal of sulfur from coal gangue by ozone, in addition to utilizing the oxidation performance of ozone, there may be other unknown mechanisms, which need further study.

[0060] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for harmless disposal of coal gangue, characterized in that: The following steps are involved: preparing coal gangue into coal gangue powder; Adding the coal gangue powder and additives into water to prepare a mixed material; Passing ozone mixed gas into the mixed material for oxidation, and then filtering to obtain desulfurized coal gangue powder; The additive is an inorganic salt or an acid; The inorganic salt is sodium sulfate, sodium bicarbonate, sodium carbonate, sodium chloride, magnesium sulfate, sodium persulfate, sodium nitrate, potassium permanganate or sodium silicate; The acid is hydrochloric acid, sulfuric acid or nitric acid.

2. The method for harmless disposal of coal gangue according to claim 1, characterized in that: The gangue is prepared into gangue powder by mechanical crushing and screening; the particle size of the gangue powder is not greater than 3 mm.

3. The method for harmless disposal of coal gangue according to claim 1, characterized in that: The liquid-to-solid ratio of the water to the coal gangue powder is 3:1 to 10:

1.

4. The method for harmless disposal of coal gangue according to claim 1, characterized in that: When the additive is an inorganic salt, the added amount of the inorganic salt is 0.05% to 2% of the mass of the coal gangue powder.

5. The method for harmless disposal of coal gangue according to claim 1, characterized in that: When the additive is an acid, the amount of the acid added is such that the pH of the mixed material is 4-5.

6. The method for harmless disposal of coal gangue according to claim 1, characterized in that: The ozone mixed gas is a mixed gas of ozone and air.

7. The method for harmless disposal of coal gangue according to claim 1, characterized in that: The volume concentration of ozone in the ozone mixed gas is 50% to 90%.

8. The method for harmless disposal of coal gangue according to claim 1, characterized in that: The oxidation time is 2h to 6h.

9. A method for improving the removal rate of sulfur in coal gangue, characterized in that: A method for harmless disposal of coal gangue as described in any one of claims 1 to 8 is adopted.