A method for harmless disposal of coal gangue

Abstract

The present application relates to the technical field of resources and environment, and particularly relates to a harmless treatment method of coal gangue. The harmless treatment method of coal gangue comprises the following steps: preparing coal gangue into coal gangue powder; adding the coal gangue powder and an additive into water to prepare a mixture; introducing ozone mixed gas into the mixture to perform 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. The method is green and environmentally friendly in the desulfurization process, and has high economic benefits. The method has the advantages of low cost, short time and high desulfurization efficiency. By using the desulfurization process of the present application, the sulfur content in the coal gangue can be effectively reduced by simple one-time treatment under the condition of adding a small amount of additive (catalyst).

Description

Technical Field

[0001] This invention relates to the field of resources and environmental technology, and in particular to a method for the harmless disposal of coal gangue. Background Technology

[0002] Currently, methods for sulfur removal from coal gangue mainly include physical, chemical, and microbiological methods. Physical methods primarily utilize physical coal preparation technologies, such as jigging, heavy media preparation, inclined chute preparation, shaking table preparation, and pneumatic preparation, to effectively remove inorganic sulfur (pyrite sulfur) from coal. This method is suitable for removing pyrite sulfur from coal, but its effectiveness in removing organic sulfur is limited. Chemical methods include alkali treatment, oxidation, and solvent extraction. These methods can effectively remove sulfur in the laboratory, but industrial applications may face cost and technical challenges. Microbiological methods utilize specific microorganisms, such as Thiobacillus, to remove sulfur from coal through chemical reactions during their metabolic processes. This method is environmentally friendly, but may suffer from low desulfurization efficiency and long cycles.

[0003] Therefore, providing a simple and efficient method for removing sulfur from coal gangue is a problem that those skilled in the art have been working to solve. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the harmless disposal of coal gangue, thereby solving the problems existing in the prior art. The method of this invention has the advantages of simple process and high desulfurization rate.

[0005] To achieve the above objectives, the present invention provides the following solution:

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

[0007] Coal gangue is prepared into coal gangue powder;

[0008] The coal gangue powder and additives are added to water to prepare a mixture;

[0009] Ozone gas is introduced into the mixture for oxidation, followed by filtration to obtain desulfurized coal gangue powder.

[0010] The additive is an inorganic salt or 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, coal gangue is prepared into coal gangue powder by mechanical crushing and sieving; the particle size of the coal gangue powder is not greater than 3 mm.

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

[0015] In this invention, the lower the liquid-to-solid ratio, the longer the oxidation time is required to achieve the same desulfurization effect; an excessively high liquid-to-solid ratio will result in increased water consumption, increased water treatment costs, and is not conducive to large-scale utilization.

[0016] In a preferred embodiment of the present invention, when the additive is an inorganic salt, the amount of the inorganic salt added 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 acid added is sufficient to make the pH of the mixture 4 to 5.

[0018] In this invention, if the proportion of additives is too high, a large amount of by-salts will be formed during the oxidation process, which will hinder the contact between ozone and sulfides, affecting desulfurization efficiency. Furthermore, increasing the proportion of additives will increase the cost of large-scale utilization. If the proportion of additives is too low, desulfurization efficiency will also be affected. Therefore, this invention preferably limits the amount of additives to the range of parameters mentioned above.

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

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

[0021] In this invention, if the ozone volume concentration is too low, the oxidation time will be prolonged. The amount of ozone introduced is directly proportional to the desulfurization efficiency. However, if the amount introduced is too high, the ozone residence time in the mixture will be too long, resulting in low ozone utilization. If the amount introduced is too low, it will affect the diffusion of ozone in the mixture.

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

[0023] In this invention, if the oxidation time is too short, the desulfurization effect of a single oxidation process will be poor, increasing the number of desulfurization cycles; if the oxidation time is too long, it will hinder the large-scale application of the method and increase the cost of large-scale application. Therefore, the preferred oxidation time in this invention is within the range of the parameters mentioned above.

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

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

[0026] This invention provides a method for the harmless disposal of coal gangue, which can effectively remove sulfur from coal gangue. The desulfurization process of this method is green and environmentally friendly, and has high economic benefits.

[0027] The method of this invention has the advantages of low cost, short time, and high desulfurization efficiency. Using the desulfurization process of this invention, with the addition of a small amount of additives (co-catalysts), a simple one-time treatment can effectively reduce the sulfur content in coal gangue by 50%-60%, achieving the harmless disposal of coal gangue. Detailed Implementation

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

[0029] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0031] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

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

[0033] This invention provides a method for removing sulfur from coal gangue, comprising the following steps:

[0034] The lumpy coal gangue is mechanically crushed to obtain coal gangue powder. Then, using water as the liquid phase, the coal gangue powder is added to the water along with a small amount of additives. Ozone gas mixture is then introduced into the mixture to oxidize the sulfur in the coal gangue, forming sulfate ions that dissolve and transfer to the liquid phase for removal. After filtration, desulfurized coal gangue powder is obtained.

[0035] The mechanical crushing refers to breaking the coal gangue into large particles and then crushing it using a crusher.

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

[0037] The filtrate obtained after oxidation and filtration is neutralized with acid and alkali to remove impurities and then recycled.

[0038] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

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

[0040] Example 1: Coal gangue from a certain region (total sulfur content 2.8%)

[0041] Coal gangue was mechanically crushed using a pulverizer to ensure it could all pass through a 3mm sieve, yielding coal gangue powder. Then, the coal gangue powder was mixed with water at a liquid-to-solid ratio of 8:1 (mL / g) to prepare a mixture. Sodium persulfate (0.2% by weight of the coal gangue powder) was added to the mixture, and after thorough mixing, 270g of the mixture was packed into a glass apparatus. An ozone mixture with an ozone volume concentration of 70% was continuously passed through the glass apparatus for oxidation at a flow rate of 2L / min for 5 hours. Finally, the mixture was filtered to obtain desulfurized coal gangue powder. The total sulfur content in the desulfurized coal gangue powder was 1.27%, and the desulfurization rate reached 55%.

[0042] The method has been verified to remove both inorganic and organic sulfur from coal gangue.

[0043] Example 2: Coal gangue from a certain region (total sulfur content 2.8%)

[0044] Coal gangue was mechanically crushed using a pulverizer to ensure it could all pass through a 3mm sieve, yielding coal gangue powder. Then, the coal gangue powder was mixed with water at a liquid-to-solid ratio of 6:1 to prepare a mixture. Specifically, 14kg of the mixture was loaded into a reactor, 84L of clean water was added, and then sodium bicarbonate (0.2% of the coal gangue powder's mass) was added. After thorough mixing, a mixture of ozone (80% ozone volume concentration) and air was continuously introduced into the reactor for oxidation at a flow rate of 60L / min for 2 hours. Finally, the mixture was filtered to obtain desulfurized coal gangue powder. The total sulfur content in the desulfurized coal gangue powder was 1.9%, and the desulfurization rate reached 32%.

[0045] The method has been verified to remove both inorganic and organic sulfur from coal gangue.

[0046] Example 3: Coal gangue from a certain region (total sulfur content 2.8%)

[0047] Coal gangue was mechanically crushed using a pulverizer to ensure it could all pass through a 3mm sieve, yielding coal gangue powder. Then, the coal gangue powder was mixed with water at a liquid-to-solid ratio of 10:1 to form a mixture. 330g of this mixture was placed in a glass apparatus equipped with a gas distributor. Sodium bicarbonate (0.2% by weight of the coal gangue powder) was added to the mixture, and after thorough mixing, a mixture of ozone (80% ozone volume concentration) and air was continuously passed through the glass apparatus for oxidation at a flow rate of 2L / min for 5 hours. Finally, the mixture was filtered to obtain desulfurized coal gangue powder. The total sulfur content in the desulfurized coal gangue powder was 1.2%, and the desulfurization rate reached 57%.

[0048] The method has been verified to remove both inorganic and organic sulfur from coal gangue.

[0049] Example 4: Coal gangue from a certain region (total sulfur content 9.0%)

[0050] Coal gangue was mechanically crushed using a pulverizer to ensure it could all pass through a 3mm sieve, yielding coal gangue powder. Then, the coal gangue powder was mixed with water at a liquid-to-solid ratio of 5:1 to prepare a mixture of 180g and 180g. Dilute sulfuric acid was added to the mixture to adjust the pH to 4-5. After thorough mixing, a mixture of ozone (70% ozone volume concentration) and air was continuously passed through a glass apparatus for oxidation at a flow rate of 1.5L / min for 4 hours. Finally, the mixture was filtered to obtain desulfurized coal gangue powder. The total sulfur content in the desulfurized coal gangue powder was 5.4%, and the desulfurization rate reached 40%.

[0051] The method has been verified to remove both inorganic and organic sulfur from coal gangue.

[0052] Example 5: Coal gangue from a certain region (total sulfur content 2.8%)

[0053] Coal gangue was mechanically crushed using a pulverizer to ensure it could all pass through a 3mm sieve, yielding coal gangue powder. Then, the coal gangue powder was mixed with water at a liquid-to-solid ratio of 7:1 to prepare a 240g mixture. Sodium persulfate (0.2% by weight of the coal gangue powder) was added to the mixture, and after thorough mixing, a mixture of ozone (80% ozone volume concentration) and air was continuously passed through a glass apparatus for oxidation at a flow rate of 2L / min for 5 hours. Finally, the mixture was filtered to obtain desulfurized coal gangue powder. The total sulfur content in the desulfurized coal gangue powder was 1.2%, and the desulfurization rate reached 57%.

[0054] The method has been verified to remove both inorganic and organic sulfur from coal gangue.

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

[0056] Coal gangue was mechanically crushed using a pulverizer until it could all pass through a 200-mesh sieve to obtain coal gangue powder. Then, the coal gangue powder was added to clean water at a liquid-to-solid ratio of 4:1 to prepare a 150g mixture. Hydrogen peroxide, accounting for 1% of the water volume, was added to the mixture, and after thorough mixing, it was stirred for 5 hours. Finally, the mixture was filtered to obtain desulfurized coal gangue powder. The total sulfur content of the desulfurized coal gangue powder was 8.62%, and the desulfurization rate was 4.2%.

[0057] Based on Comparative Example 1, this invention also verified the cases where the amount of hydrogen peroxide added was 5% and 10% (i.e., only the amount of hydrogen peroxide added was adjusted, and the other steps and parameters were the same as those in Comparative Example 1; in the case where the amount of hydrogen peroxide added was 10%, heating treatment was carried out during the stirring process). The results showed that the desulfurization effect was not good, and the desulfurization rates were 2% and 7%, respectively.

[0058] Even with the addition of sodium persulfate at 0.2% of the coal gangue powder to Comparative Example 1, and with all other steps and parameters remaining the same as Comparative Example 1, the desulfurization rate was only 4.5%, indicating a poor desulfurization effect.

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

[0060] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for improving the sulfur removal rate from coal gangue, characterized in that, The steps are as follows: Coal gangue is prepared into coal gangue powder; The coal gangue powder and additives are added to water to prepare a mixture; Ozone gas is introduced into the mixture for oxidation, followed by filtration to obtain desulfurized coal gangue powder. The additive is sodium bicarbonate; the amount of sodium bicarbonate added is 0.05% to 2% of the mass of coal gangue powder. The liquid-solid ratio of the water to the coal gangue powder is 3:1 to 10:1; The ozone mixture is a mixture of ozone and air; the volume concentration of ozone in the ozone mixture is 50% to 90%. Coal gangue is prepared into coal gangue powder by mechanical crushing and sieving; the particle size of the coal gangue powder is not greater than 3 mm; The oxidation time is 2h to 6h.