An arsenic fixation composition for coal washing and beneficiation process and its application method

Abstract

This disclosure relates to an arsenic fixation composition and its application method in a coal washing process. The arsenic fixation composition exhibits a good synergistic effect among dolomite powder, auxiliary absorbent, and catalyst, enabling the adsorption of arsenic from the coal washing process products after conversion. This reduces the arsenic content in the coal washing process products and improves arsenic removal efficiency. Using inexpensive, low-cost, and widely available dolomite powder as the main adsorbent reduces environmental pollution problems associated with traditional coal washing processes and improves their environmental performance. The use of a composition of petroleum sulfide and Fe-Mn composite oxides as the auxiliary absorbent allows for several advantages. First, the sulfur in petroleum sulfide converts trivalent arsenic in coal into pentavalent arsenic, facilitating absorption by the absorbent. Second, the Fe and Mn in the Fe-Mn composite oxides react with sulfur to form iron sulfide and manganese sulfide, preventing sulfur from entering the washing water and causing environmental pollution.

Description

Technical Field

[0001] This disclosure relates to the field of coal arsenic fixation, specifically to an arsenic fixation composition for coal washing and beneficiation processes and its method of use. Background Technology

[0002] Coal is the primary energy source for my country's power development. Currently, coal-fired power plants account for as much as 70% of the total installed capacity, and coal used for thermal power generation accounts for more than 60% of the country's total coal sales, making thermal power plants the largest user of coal. Arsenic in coal is one of the most significant polluting elements in the environment; therefore, arsenic pollution has attracted increasing attention.

[0003] Arsenic is a poison that seriously endangers human health. In the human body, it can bind to the sulfhydryl groups of intracellular enzymes and proteins, rendering them inactive, thereby affecting the metabolism of human tissues, causing cell death, and also disrupting the metabolism of nerve cells, leading to nervous system disorders. Although my country has clear regulations on the mass fraction of arsenic in coal, the arsenic produced from the combustion of high-arsenic coal is released into the atmosphere, accumulating in fly ash, food, and other substances, thus causing significant environmental problems and endangering human health.

[0004] Currently, a very effective method to reduce the numerous environmental problems caused by arsenic during coal utilization is to wash raw coal. However, during the washing process, a small portion of the arsenic in the coal is released into the washing water, while the majority is distributed into various washing products, such as clean coal, middlings, fine coal, coal slime, and coal gangue. This poses a great threat to the human living environment. Summary of the Invention

[0005] The purpose of this disclosure is to provide an arsenic-fixing composition for coal washing and its application method, in order to solve the problems of high arsenic content in coal obtained by existing washing processes and environmental pollution caused by arsenic in wastewater generated by washing processes.

[0006] To achieve the above objectives, this disclosure provides an arsenic fixation composition for coal washing and beneficiation processes, the arsenic fixation composition comprising dolomite powder, surfactant, auxiliary absorbent, catalyst, and dispersant;

[0007] The auxiliary absorbent comprises a composition of petroleum sulfide and Fe-Mn composite oxide;

[0008] Based on the total weight of the arsenic-fixing composition, the content of the dolomite powder is 40-70% by weight, the content of the surfactant is 1-10% by weight, the content of the auxiliary absorbent is 10-30% by weight, the content of the catalyst is 10-30% by weight, and the content of the dispersant is 1-10% by weight.

[0009] Optionally, based on the total weight of the arsenic-fixing composition, the content of dolomite powder is 50-60% by weight, the content of surfactant is 4-7% by weight, the content of auxiliary absorbent is 20-28% by weight, the content of catalyst is 20-25% by weight, and the content of dispersant is 3-7% by weight.

[0010] Optionally, the dolomite powder has a particle size of less than 100 mesh;

[0011] The sulfur content in the petroleum sulfide is 5.0~10.0 ppm;

[0012] The Fe-Mn composite oxide contains iron oxides including one or more of Fe2O3, FeO, and Fe3O4, and manganese oxides including MnO.

[0013] Optionally, the surfactant includes copolymers of polysiloxane and acrylic acid and / or copolymers of polysiloxane and acrylate; the molecular weight of the copolymer in the surfactant is 300-400.

[0014] Optionally, the surfactant includes polydimethylsiloxane-b-polymethacrylic acid and polydimethylsiloxane-b-polymethyl methacrylate;

[0015] Based on the total weight of the surfactant, the content of polydimethylsiloxane-b-polymethacrylic acid is 50-60% by weight, and the content of polydimethylsiloxane-b-polymethacrylic acid methyl ester is 40-50% by weight.

[0016] Optionally, the weight ratio of the petroleum sulfide to the Fe-Mn composite oxide is (1.5~4.0):1.

[0017] Optionally, the catalyst comprises slaked lime.

[0018] Optionally, the dispersant is selected from phosphate ester type polymers; the phosphate ester type polymers include compositions of aryl phosphate ester polymers, fatty alcohol polyoxyethylene ether phosphate ester polymers, and alkyl alcohol amide phosphate ester polymers.

[0019] Based on the total weight of the phosphate ester type polymer, the content of the aryl phosphate ester polymer is 40-70% by weight, the content of the fatty alcohol polyoxyethylene ether phosphate polymer is 15-25% by weight, and the content of the alkyl alcohol amide phosphate polymer composition is 15-25% by weight.

[0020] Optionally, the weight ratio of the dolomite powder to the auxiliary absorbent is (1.5~3.5):1.

[0021] The second aspect of this disclosure provides a method of using the arsenic-fixing composition described in the first aspect, the method comprising feeding the arsenic-fixing composition and coal into a coal washing device for coal washing treatment; wherein the weight ratio of the arsenic-fixing composition to the coal is (0.2~0.3):1.

[0022] Through the above technical solution, the dolomite powder, auxiliary absorbent, and catalyst in the disclosed arsenic fixation composition exhibit a good synergistic effect, enabling the adsorption of arsenic in the coal washing process products after conversion, thereby reducing the arsenic content in the coal washing process products and improving the arsenic removal efficiency. Using inexpensive, low-cost, and widely available dolomite powder as the main adsorbent can reduce environmental pollution problems in traditional coal washing processes and improve the environmental performance of coal washing processes. Using a composition of petroleum sulfide and Fe-Mn composite oxide as the auxiliary absorbent allows the sulfur in petroleum sulfide to convert trivalent arsenic in coal into pentavalent arsenic, facilitating absorption by the absorbent; furthermore, the Fe and Mn in the Fe-Mn composite oxide can form iron sulfide and manganese sulfide with sulfur, preventing sulfur from entering the washing water and causing environmental pollution. Adding a catalyst to the arsenic fixation composition can promote the arsenic conversion treatment effect and further improve the arsenic removal efficiency.

[0023] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0024] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0025] This disclosure provides an arsenic fixation composition for a coal washing process, the arsenic fixation composition comprising dolomite powder, surfactant, auxiliary absorbent, catalyst and dispersant;

[0026] The auxiliary absorbent comprises a composition of petroleum sulfide and Fe-Mn composite oxide;

[0027] Based on the total weight of the arsenic-fixing composition, the content of the dolomite powder is 40-70% by weight, the content of the surfactant is 1-10% by weight, the content of the auxiliary absorbent is 10-30% by weight, the content of the catalyst is 10-30% by weight, and the content of the dispersant is 1-10% by weight.

[0028] Through the above technical solution, the dolomite powder, auxiliary absorbent, and catalyst in the disclosed arsenic fixation composition exhibit a good synergistic effect, enabling the adsorption of arsenic in the coal washing process products after conversion, thereby reducing the arsenic content in the coal washing process products and improving the arsenic removal efficiency. Using inexpensive, low-cost, and widely available dolomite powder as the main adsorbent can reduce environmental pollution problems in traditional coal washing processes and improve the environmental performance of coal washing processes. Using a composition of petroleum sulfide and Fe-Mn composite oxide as the auxiliary absorbent allows the sulfur in petroleum sulfide to convert trivalent arsenic in coal into pentavalent arsenic, facilitating absorption by the absorbent; furthermore, the Fe and Mn in the Fe-Mn composite oxide can form iron sulfide and manganese sulfide with sulfur, preventing sulfur from entering the washing water and causing environmental pollution. Adding a catalyst to the arsenic fixation composition can promote the arsenic conversion treatment effect and further improve the arsenic removal efficiency.

[0029] In one embodiment, the dolomite powder described in this disclosure refers to dolomite obtained through crushing. In this embodiment, dolomite is a sedimentary carbonate rock, mainly composed of dolomite, quartz, feldspar, calcite, and clay minerals. It is generally grayish-white, brittle, and hard, easily scratched with iron tools. It slowly effervesces or does not effervesce when exposed to dilute hydrochloric acid, and its appearance is very similar to limestone.

[0030] In one embodiment, the dolomite powder has a particle size of less than 100 mesh.

[0031] In one embodiment, the porosity of the dolomite powder is 30-50%.

[0032] In this embodiment, the crushing method for dolomite powder is a conventional choice in the art, and this application does not impose special requirements. For example, after crushing with a crushing device, the powder can be separated using a 100-mesh sieve. The material below the sieve is the dolomite powder, and the material on the sieve is returned to the crushing device for further crushing and sieving. When the porosity of the dolomite powder is within suitable parameters, it can adsorb more arsenic while ensuring the strength of the dolomite powder.

[0033] In one embodiment, the surfactants described in this disclosure include copolymers of polysiloxane and acrylic acid and / or copolymers of polysiloxane and acrylate.

[0034] In a preferred embodiment, the surfactant includes polydimethylsiloxane-b-polymethacrylic acid and polydimethylsiloxane-b-polymethyl methacrylate.

[0035] In a further preferred embodiment, the content of polydimethylsiloxane-b-polymethacrylic acid is 50-60% by weight, and the content of polydimethylsiloxane-b-polymethacrylate is 40-50% by weight. In this embodiment, the ratio between the components in the surfactant can be flexibly adjusted according to actual needs. For example, the content of polydimethylsiloxane-b-polymethacrylic acid in the surfactant can be one or any two of 50% by weight, 51% by weight, 52% by weight, 53% by weight, 54% by weight, 55% by weight, 56% by weight, 57% by weight, 58% by weight, 59% by weight, and 60% by weight; the content of polydimethylsiloxane-b-polymethacrylate in the surfactant can be one or any two of 40% by weight, 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, 49% by weight, and 50% by weight.

[0036] In one embodiment, the copolymer in the surfactant has a molecular weight of 300-400. In this embodiment, the surfactant used in this disclosure has a hydrophilic end and a hydrophobic end, respectively. The hydrophilic end extends into the aqueous solution, and the hydrophobic end is connected to the agglomerating agent molecule. Using two copolymers with different hydrophobic ends allows them to bind to different substances in the formed network structure macromolecule, further improving the surface activity of the formed network structure macromolecule. The molecular weight of the copolymer in the surfactant can be flexibly set according to the properties of the formed network structure macromolecule. For example, the molecular weight of the copolymer in the surfactant is one of 310, 330, 350, and 380, or any combination thereof.

[0037] In one embodiment, the petroleum sulfide described in this disclosure is a conventional choice in the art, and this application does not make any special requirements. For example, the source of petroleum sulfide can be generated by a gasoline catalytic distillation unit, a polyphenylene sulfide production unit, or a gasoline etherification unit.

[0038] In one embodiment, the sulfur content in the petroleum sulfide is 5.0~10.0 ppm.

[0039] In a preferred embodiment, the sulfur content in the petroleum sulfide can be flexibly adjusted according to the source of the coal. For example, the sulfur content in the petroleum sulfide can be one or any two of 5.0 ppm, 6.0 ppm, 8.0 ppm, 9.0 ppm and 10.0 ppm.

[0040] In this embodiment, the sulfur in petroleum sulfide mainly includes elemental sulfur, organic sulfur, and inorganic sulfur. Among them, organic sulfur includes one or more of sulfides, thiols, and thiophenols, and inorganic sulfur includes one or more of hydrogen sulfide and sodium sulfide.

[0041] In this embodiment, during the coal washing process, the sulfur in petroleum sulfide reacts with the washing water and the trivalent arsenic inside the coal to convert the trivalent arsenic into pentavalent arsenic, which is easily adsorbed by the adsorbent and can improve the arsenic removal rate.

[0042] In one embodiment, the Fe-Mn composite oxide of this disclosure includes one or more of Fe2O3, FeO and Fe3O4 as the iron oxide, and MnO and / or MnO2 as the manganese oxide.

[0043] In a preferred embodiment, the Fe-Mn composite oxide of this disclosure is composed of ferric oxide and manganese oxide. In this embodiment, based on the total weight of the Fe-Mn composite oxide, the content of ferric oxide is 35-55% by weight, preferably 40-45% by weight; and the content of manganese oxide is 45-65% by weight, preferably 55-60% by weight.

[0044] In this embodiment, the sulfur formed by the reaction of sulfur in petroleum sulfide with arsenic can react with the Fe and Mn elements in Fe-Mn composite oxides to form compounds such as iron sulfide, ferrous sulfide, and manganese sulfide, thus preventing sulfur from entering the washing water and causing environmental pollution.

[0045] In one embodiment, the method for preparing the Fe-Mn composite oxide described in this disclosure is a conventional choice in the art, and this application does not have any special requirements.

[0046] In one embodiment, the method for preparing the Fe-Mn composite oxide includes: taking Fe... 3+ Solution and Mn 2+ A stabilizer and a weak alkali, ammonia, are added to the solution mixture to adjust the pH to 7.5-8.0. Finally, the solution is drained and calcined to obtain the final product.

[0047] In another embodiment, the method for preparing the Fe-Mn composite oxide includes:

[0048] Add an appropriate amount of NaOH solution to the KMnO4 solution to make the solution alkaline throughout the reaction process; add FeSO4 to the above KMnO4 solution under stirring conditions, and then stir, drain and calcine in sequence to obtain the Fe-Mn composite oxide.

[0049] In one embodiment, the catalyst comprises hydrated lime and / or quicklime, preferably hydrated lime. In this embodiment, adding a catalyst to the arsenic-fixing composition can promote the effect of arsenic conversion treatment and further improve the arsenic removal efficiency.

[0050] In one embodiment, the dispersant comprises a phosphate ester type polymer; the polymer comprises one or more of aryl phosphate ester polymers, fatty alcohol polyoxyethylene ether phosphate ester polymers, and alkyl alcohol amide phosphate ester polymers.

[0051] In a preferred embodiment, the phosphate ester type polymer comprises a composition of aryl phosphate ester polymers, fatty alcohol polyoxyethylene ether phosphate ester polymers, and alkyl alcohol amide phosphate ester polymers.

[0052] In a further preferred embodiment, the aryl phosphate salt polymer comprises docosylamide dimethyl hydroxypropyl ammonium chloride; the fatty alcohol polyoxyethylene ether phosphate salt polymer comprises fatty alcohol polyoxyethylene ether phosphate potassium salt; and the alkylolamide phosphate salt polymer comprises alkylolamide phosphate potassium salt.

[0053] In this embodiment, the potassium salt of fatty alcohol polyoxyethylene ether phosphate is obtained by sequentially esterifying, hydrolyzing, and neutralizing fatty alcohol polyoxyethylene ether AEO-3. The potassium salt of alkyl alcohol amide phosphate is made from alkyl alcohol amide phosphate.

[0054] In one embodiment, based on the total weight of the phosphate ester type polymer, the content of the aryl phosphate ester polymer is 40-70% by weight, the content of the fatty alcohol polyoxyethylene ether phosphate polymer is 15-25% by weight, and the content of the alkyl alcohol amide phosphate polymer composition is 15-25% by weight.

[0055] In a preferred embodiment, based on the total weight of the phosphate ester type polymer, the content of the aryl phosphate ester polymer is 45-60% by weight, the content of the fatty alcohol polyoxyethylene ether phosphate ester polymer is 20-23% by weight, and the content of the alkyl alcohol amide phosphate ester polymer composition is 20-22% by weight.

[0056] In this embodiment, adding a dispersant to the arsenic-fixing composition enables the arsenic-fixing composition to be uniformly dispersed in the washing water, thereby improving the dispersion efficiency and the arsenic removal efficiency. Using a composition of phosphate ester type polymers, including aryl phosphate ester polymers, fatty alcohol polyoxyethylene ether phosphate ester polymers, and alkyl alcohol amide phosphate ester polymers, as a dispersant can further improve the dispersion efficiency, and thus further improve the arsenic removal efficiency.

[0057] In the above embodiments, the mixture of surfactant, modified dolomite powder, auxiliary absorbent, catalyst, and dispersant is fully compatible in water, and the aqueous solution of the mixture is a homogeneous system. During thorough mixing, as the mixture of surfactant, modified dolomite powder, auxiliary absorbent, catalyst, and dispersant becomes fully miscible in water, it initially separates into two layers: one layer mainly containing surfactant, and the other mainly containing the mixture of modified dolomite powder, auxiliary absorbent, catalyst, and dispersant. Due to the repulsion of like charges, the diffused electric double layer between the surfactant and the composite mixture maintains a mutually repulsive region, resulting in a thermodynamically stable solution. During thorough mixing, due to the compression of the electric double layer, the surfactants move closer together, the electric double layers overlap, and the polymer coils tend to coil up. The intermolecular repulsion region between the surfactant and the composite mixture decreases, and a dense two-dimensional separation trend begins to emerge; and when the electrolyte concentration increases to a certain value, the separation into two distinct phases occurs.

[0058] In a preferred embodiment, based on the total weight of the arsenic-fixing composition, the content of dolomite powder is 50-60% by weight, the content of surfactant is 4-7% by weight, the content of auxiliary absorbent is 20-28% by weight, the content of catalyst is 20-25% by weight, and the content of dispersant is 3-7% by weight.

[0059] In this embodiment, when the content of each component in the arsenic-fixing composition is at a very suitable level, it can exhibit a good synergistic effect, so that the arsenic in the product of the coal washing process is adsorbed after conversion, which can further reduce the arsenic content in the product of the coal washing process and improve the arsenic removal efficiency.

[0060] In one embodiment, the weight ratio of the petroleum sulfide to the Fe-Mn composite oxide is (1.5~4.0):1.

[0061] In a preferred embodiment, the weight ratio of the petroleum sulfide to the Fe-Mn composite oxide is (2.0~3.0):1.

[0062] In this embodiment, by using an appropriate weight ratio of petroleum sulfide and the Fe-Mn composite oxide, not only can the sulfur element after the reaction be completely absorbed by the Fe-Mn composite oxide, but the sulfur element in the washing water can also be completely absorbed by the Fe-Mn composite oxide, thereby further reducing the sulfur content in the coal washing process products and reducing sulfur pollution to the environment.

[0063] In one embodiment, the weight ratio of the dolomite powder to the auxiliary absorbent is (1.5~3.5):1.

[0064] In a preferred embodiment, the weight ratio of the dolomite powder to the auxiliary absorbent can be any one or any two of 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2 and 3.4.

[0065] The second aspect of this disclosure provides a method of using the arsenic-fixing composition described in the first aspect, the method comprising feeding the arsenic-fixing composition and coal into a coal washing device for coal washing treatment; wherein the weight ratio of the arsenic-fixing composition to the coal is (0.2~0.3):1.

[0066] In this embodiment, the arsenic-fixing composition is added to the washing water. The dispersant can promote the dispersion of each component to various locations, reduce the arsenic content in the products of the coal washing process, and improve the arsenic removal efficiency.

[0067] In one embodiment, the coal described in this disclosure is obtained from the Qipanjing coalfield in Wuhai, Inner Mongolia. In this embodiment, the arsenic content in the coal is 20-100 ug / g.

[0068] The present disclosure is further illustrated by the following examples, but the disclosure is not limited thereto. Unless otherwise stated, the chemicals used in the following examples and comparative examples are commercially available products with a purity of 99% by weight or higher. These chemicals include polydimethylsiloxane-b-polymethacrylic acid, polydimethylsiloxane-b-polymethyl methacrylate, and alkanolamide polyoxyethylene ether. The petroleum sulfide described in this disclosure is oil obtained from a gasoline etherification unit; the coal described in this disclosure is coal obtained from the Qipanjing coalfield in Wuhai, Inner Mongolia, and the arsenic content in the coal is 65 μg / g.

[0069] Preparation Example

[0070] Methods for preparing Fe-Mn composite oxides include:

[0071] Add an appropriate amount of NaOH solution to the KMnO4 solution to make the pH value of the solution 12 throughout the reaction process;

[0072] Under stirring conditions, FeSO4 solution was added to the above KMnO4 solution at a Fe / Mn molar ratio of 3:1, and then stirring was continued for 60 min. Finally, the Fe-Mn composite oxide was obtained by draining and calcining.

[0073] Example 1

[0074] The method for preparing the arsenic-fixing composition S1 includes:

[0075] 50g of dolomite powder, 5g of polydimethylsiloxane-b-polymethacrylic acid (molecular weight 306), 15g of petroleum sulfide with a sulfur content of 5.0ppm and 5g of Fe-Mn composite oxide, 20g of quicklime and 5g of alkylolamide phosphate potassium salt were mixed evenly to obtain arsenic-fixing composition S1.

[0076] Based on the total weight of the arsenic-fixing composition, the content of dolomite powder is 50% by weight, the content of surfactant is 5% by weight, the content of auxiliary absorbent is 20% by weight, the content of catalyst is 20% by weight, and the content of dispersant is 5% by weight.

[0077] Example 2

[0078] The method for preparing the arsenic-fixing composition S2 includes:

[0079] The composition of 60g dolomite powder, 5.5g polydimethylsiloxane-b-polymethacrylic acid (molecular weight 306), 10g petroleum sulfide with a sulfur content of 5.0ppm and 4.5g Fe-Mn composite oxide, 15g quicklime and 5g alkylolamide phosphate potassium salt were mixed evenly to obtain arsenic-fixing composition S2.

[0080] Based on the total weight of the arsenic-fixing composition, the content of dolomite powder is 60% by weight, the content of surfactant is 5.5% by weight, the content of auxiliary absorbent is 14.5% by weight, the content of catalyst is 15% by weight, and the content of dispersant is 5% by weight.

[0081] Example 3

[0082] The method for preparing the arsenic-fixing composition S3 includes:

[0083] 53g of dolomite powder, 7g of polydimethylsiloxane-b-polymethacrylic acid (molecular weight 306), 18g of petroleum sulfide with a sulfur content of 5.0ppm and 7g of Fe-Mn composite oxide, 10g of quicklime and 5g of alkylolamide phosphate potassium salt were mixed evenly to obtain arsenic-fixing composition S3.

[0084] Based on the total weight of the arsenic-fixing composition, the content of dolomite powder is 53% by weight, the content of surfactant is 7% by weight, the content of auxiliary absorbent is 25% by weight, the content of catalyst is 10% by weight, and the content of dispersant is 5% by weight.

[0085] Example 4

[0086] The method for preparing the arsenic-fixing composition S4 includes:

[0087] 55g of dolomite powder, 10g of polydimethylsiloxane-b-polymethacrylic acid (molecular weight 306), 10g of petroleum sulfide with a sulfur content of 5.0ppm and 5g of Fe-Mn composite oxide, 10g of quicklime and 10g of alkylolamide phosphate potassium salt were mixed evenly to obtain arsenic-fixing composition S4.

[0088] Based on the total weight of the arsenic-fixing composition, the content of dolomite powder is 55% by weight, the content of surfactant is 10% by weight, the content of auxiliary absorbent is 15% by weight, the content of catalyst is 10% by weight, and the content of dispersant is 10% by weight.

[0089] Example 5

[0090] The method for preparing the arsenic-fixing composition S5 includes:

[0091] A composition consisting of 70g of dolomite powder, 5g of polydimethylsiloxane-b-polymethacrylic acid (molecular weight 306), 7g of petroleum sulfide with a sulfur content of 5.0ppm and 3g of Fe-Mn composite oxide, 10g of quicklime and 5g of alkylolamide phosphate potassium salt were mixed evenly to obtain arsenic-fixing composition S5.

[0092] Based on the total weight of the arsenic-fixing composition, the content of dolomite powder is 70% by weight, the content of surfactant is 5% by weight, the content of auxiliary absorbent is 10% by weight, the content of catalyst is 10% by weight, and the content of dispersant is 5% by weight.

[0093] Example 6

[0094] The method for preparing the arsenic-fixing composition S6 is the same as in Example 1, except that the weight ratio of the petroleum sulfide and the Fe-Mn composite oxide is 1:1.

[0095] Example 7

[0096] The method for preparing the arsenic-fixing composition S7 is the same as in Example 1, except that the weight ratio of the dolomite powder to the auxiliary absorbent is 1.33:1.

[0097] Example 8

[0098] The method for preparing the arsenic-fixing composition S8 is the same as in Example 1, except that the particle size of the dolomite powder is 100-110 mesh.

[0099] Example 9

[0100] The method for preparing the arsenic-fixing composition S9 is the same as in Example 1, except that the sulfur content in the petroleum sulfide is 4.0 ppm.

[0101] Example 10

[0102] The method for preparing the arsenic-fixing composition S10 is the same as in Example 1, except that the surfactant is composed of 55% by weight of polydimethylsiloxane-b-polymethacrylic acid (molecular weight 306) and 45% by weight of polydimethylsiloxane-b-polymethyl methacrylate (molecular weight 306).

[0103] Example 11

[0104] The method for preparing the arsenic-fixing composition S11 is the same as in Example 1, except that the dispersant is composed of 50% by weight of docosylamide dimethyl hydroxypropyl ammonium chloride, 25% by weight of fatty alcohol polyoxyethylene ether phosphate potassium salt, and 25% by weight of alkylolamide phosphate potassium salt.

[0105] Comparative Example 1

[0106] The method for preparing the arsenic-fixing composition D1 is the same as in Example 1, except that the auxiliary absorbent is replaced by an equal weight of dolomite powder.

[0107] Comparative Example 2

[0108] The method for preparing the arsenic-fixing composition D2 is the same as in Example 1, except that the auxiliary absorbent consists only of petroleum sulfide with a sulfur content of 5.0 ppm.

[0109] Comparative Example 3

[0110] Methods for preparing arsenic-fixing composition D3 include:

[0111] A composition consisting of 75g of dolomite powder, 5g of polydimethylsiloxane-b-polymethacrylic acid (molecular weight 306), 3.75g of petroleum sulfide (sulfur content 8.0ppm), and 1.25g of Fe-Mn composite oxide, 8g of quicklime, and 7g of alkylolamide phosphate potassium salt was mixed evenly to obtain arsenic-fixing composition S1.

[0112] Based on the total weight of the arsenic-fixing composition, the content of dolomite powder is 75% by weight, the content of surfactant is 5% by weight, the content of auxiliary absorbent is 5% by weight, the content of catalyst is 8% by weight, and the content of dispersant is 7% by weight.

[0113] Test case

[0114] Test Example 1

[0115] The arsenic-fixing composition at a flow rate of 25 g / min was fed into a coal washing and beneficiation unit with coal at a flow rate of 100 g / min for coal washing and beneficiation treatment. The arsenic-fixing composition was S1-S11 obtained in Examples 1-11, D1-D3 obtained in Comparative Examples 1-3, and the arsenic-fixing agent in the prior art. The arsenic-fixing agent in the prior art was purchased from Dow Chemical Company and its main components included: 50-60% by weight of diatomaceous earth, 20-30% by weight of dispersant, and 20-30% by weight of surfactant.

[0116] The arsenic content in coal before and after arsenic fixation was determined using GB / T 3058 "Determination of Arsenic in Coal" and / or GB / T 20475.3 "Classification of Hazardous Elements in Coal - Part 3: Arsenic". The specific data are shown in Table 1 below.

[0117] Test Example 2

[0118] The coal washing and beneficiation method is the same as in Test Example 1, except that 15 g / min of the arsenic-fixing composition S1 and 100 g / min of coal are fed into the coal washing and beneficiation unit for coal washing and beneficiation. Specific data are shown in Table 2 below.

[0119] Table 1. Test data from the examples and comparative examples.

[0120]

[0121] Table 2 Test data from test cases

[0122]

[0123] Arsenic removal efficiency = [(Arsenic content of original coal sample - Arsenic content after arsenic fixation) / Arsenic content of original coal sample] × 100%.

[0124] As shown in Table 1, a comparison of the data from Examples 1-11 and Comparative Examples 1-4 reveals that the dolomite powder, auxiliary absorbent, and catalyst in the arsenic fixation composition of this disclosure exhibit a good synergistic effect, enabling the adsorption of arsenic from the coal washing process products after conversion, thereby reducing the arsenic content in the coal washing process products and improving the arsenic removal efficiency. Furthermore, using inexpensive, low-cost, and widely available dolomite powder as the main adsorbent not only reduces environmental pollution problems in traditional coal washing processes and improves the environmental performance of coal washing processes but also enhances the economic benefits of the arsenic fixation composition. A comparison of the data from Examples 1 and 6 shows that a weight ratio of petroleum sulfide to Fe-Mn composite oxide of (1.5-4.0):1 improves the arsenic removal efficiency. A comparison of the data from Examples 1 and 7 shows that a weight ratio of dolomite powder to auxiliary absorbent of (1.5-3.5):1 improves the arsenic removal efficiency. A comparison of the data from Examples 1 and 8 shows that when the dolomite powder has a particle size of less than 100 mesh, the arsenic removal efficiency can be improved. A comparison of the data from Examples 1 and 9 shows that when the sulfur content in the petroleum sulfide is 5.0~10.0 ppm, the arsenic removal efficiency can be improved. A comparison of the data from Examples 1 and 10 shows that when the composition and content of the surfactant are appropriate, the arsenic removal efficiency can be improved. A comparison of the data from Examples 1 and 11 shows that when the composition and content of the dispersant are appropriate, the arsenic removal efficiency can be improved. As shown in Table 2, a comparison of the data from Test Examples 1 and 2 shows that when the weight ratio of the arsenic-fixing composition to the coal is (0.2~0.3):1, the arsenic removal efficiency can be improved.

[0125] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0126] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0127] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A solid arsenic composition in a coal washing process, characterized in that, The arsenic fixation composition comprises dolomite powder, a surfactant, an auxiliary absorbent, a catalyst, and a dispersant; The auxiliary absorbent comprises a combination of petroleum sulfide and Fe-Mn composite oxide; The surfactant comprises a copolymer of polysiloxane and acrylic acid and / or a copolymer of polysiloxane and acrylate; the molecular weight of the copolymer in the surfactant is 300-400; The catalyst comprises slaked lime; The dispersant is selected from a phosphate ester salt type high polymer; the phosphate ester salt type high polymer comprises a combination of aryl phosphate ester salt high polymer, fatty alcohol polyoxyethylene ether phosphate ester salt high polymer, and alkyl alcohol amide phosphate ester salt high polymer; The content of the dolomite powder is 40-70% by weight, the content of the surfactant is 1-10% by weight, the content of the auxiliary absorbent is 10-30% by weight, the content of the catalyst is 10-30% by weight, and the content of the dispersant is 1-10% by weight, based on the total weight of the arsenic fixation composition.

2. The arsenic fixation composition of claim 1, wherein, The content of the dolomite powder is 50-60% by weight, the content of the surfactant is 4-7% by weight, the content of the auxiliary absorbent is 20-28% by weight, the content of the catalyst is 20-25% by weight, and the content of the dispersant is 3-7% by weight, based on the total weight of the arsenic fixation composition.

3. The arsenic fixation composition of claim 1, wherein, The particle size of the dolomite powder is 100 mesh or less; The content of sulfur in the petroleum sulfide is 5.0-10.0 ppm; The iron oxide in the Fe-Mn composite oxide comprises one or more of Fe2O3, FeO, and Fe3O4, and the manganese oxide comprises MnO.

4. The arsenic fixation composition of claim 1, wherein, The surfactant comprises polydimethylsiloxane-b-poly(methacrylic acid) and polydimethylsiloxane-b-poly(methyl methacrylate); The content of the polydimethylsiloxane-b-poly(methacrylic acid) is 50-60% by weight, and the content of the polydimethylsiloxane-b-poly(methyl methacrylate) is 40-50% by weight, based on the total weight of the surfactant.

5. The arsenic fixation composition of claim 1, wherein, The weight ratio of the petroleum sulfide to the Fe-Mn composite oxide is (1.5-4.0):

1.

6. The arsenic fixation composition of claim 1, wherein, The content of the aryl phosphate ester salt high polymer is 40-70% by weight, the content of the fatty alcohol polyoxyethylene ether phosphate ester salt high polymer is 15-25% by weight, and the content of the alkyl alcohol amide phosphate ester salt high polymer is 15-25% by weight, based on the total weight of the phosphate ester salt type high polymer.

7. The arsenic fixation composition of claim 1, wherein, The weight ratio of the dolomite powder to the auxiliary absorbent is (1.5-3.5):

1.

8. A method of using the arsenic immobilization composition of any one of claims 1 to 7, wherein the method comprises: (a) providing a soil or water containing arsenic; and (b) adding the arsenic immobilization composition to the soil or water to immobilize the arsenic. The use method comprises putting the arsenic fixation composition and coal into a coal washing device for coal washing treatment; the weight ratio of the arsenic fixation composition to the coal is (0.2-0.3):1.

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