Coal desulfurization method

Abstract

The invention relates to the field of coal desulfurization, in particular to a coal desulfurization method. The coal desulfurization method comprises the following steps: step 1, crushing coal; step 2, biological pretreatment: placing the crushed coal in a reaction liquid for reaction, and carrying out solid-liquid separation to obtain a wet coal cake and biological residual liquid; and 3, chemical desulfurization: placing the wet coal cake in a chemical desulfurization reagent for reaction, and carrying out solid-liquid separation to obtain clean coal and chemical residual liquid. Biological pretreatment'activates' sulfur (especially organic sulfur), the subsequent chemical desulfurization efficiency and depth are remarkably improved, and the total desulfurization rate (especially the organic sulfur removal rate) is far higher than that of a single biological method or a traditional chemical method. The method provided by the invention can effectively treat coal with different sulfur contents and different sulfur forms, especially coal with high organic sulfur content, and has wide applicability.

Description

Technical Field

[0001] This invention relates to the field of coal desulfurization, and in particular to a coal desulfurization method. Background Technology

[0002] Coal is an important basic energy source, widely used in chemical, mining, and energy fields. The sulfur oxides released by its combustion are one of the main pollutants causing environmental problems such as acid rain and smog. Traditional desulfurization methods are generally divided into physical, chemical, and biological single desulfurization technologies, but they have the following shortcomings: (1) Physical desulfurization mainly removes inorganic sulfur and pyrite sulfur, and has limited effect on removing fine-particle-size, complex-distributed sulfur and organic sulfur, and generates a large amount of coal slurry water that needs to be treated. (2) Chemical desulfurization equipment suffers from severe corrosion and high cost, and may damage coal quality and generate secondary pollution. (3) Biological desulfurization has a long desulfurization cycle and relatively low efficiency.

[0003] Therefore, it is necessary to propose an efficient, economical, and environmentally friendly method for removing inorganic and organic sulfur from coal. Summary of the Invention

[0004] Based on the above, the present invention provides a method for coal desulfurization.

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

[0006] This invention provides a coal desulfurization method, comprising the following steps:

[0007] Step 1, coal crushing;

[0008] Step 2, biological pretreatment: The crushed coal is placed in a reaction solution for reaction, and solid-liquid separation is performed to obtain wet coal cake and biological residue;

[0009] Step 3, chemical desulfurization: The wet coal cake is placed in a chemical desulfurization reagent for reaction, and solid-liquid separation is performed to obtain clean coal and chemical residue.

[0010] In a preferred embodiment of the present invention, in step 1, the coal is crushed to a particle size of no more than 0.5 mm.

[0011] In a preferred embodiment of the present invention, in step 2, the reaction solution includes a culture medium and bacteria; the culture medium is 9K medium or Starkey medium; the bacteria are at least one of ferrooxidizobacillus, halophyte Rhodococcus, polymyxa, and Bacillus subtilis.

[0012] In a preferred embodiment of the present invention, the concentration of bacteria in the reaction solution is (1.5–2.5) × 10⁻⁶. 8 CFU / mL; pH of the reaction solution is 1.8–2.0.

[0013] In a preferred embodiment of the present invention, the reaction solution further includes trace elements or yeast extract; wherein the trace elements include MgNO3·6H2O, ZnSO4·7H2O, CuSO4·5H2O, MnSO4·H2O, CoCl2·6H2O, Na2MoO4·2H2O, H3BO3, and CaCl2·2H2O; the concentration of MgNO3·6H2O in the reaction solution is 50.0 g / L, and the concentration of ZnSO4·7H2O in the reaction solution is 2.2 g / L. The concentrations of CuSO4·5H2O, MnSO4·H2O, CoCl2·6H2O, Na2MoO4·2H2O, H3BO3, and CaCl2·2H2O in the reaction solution were 0.6 g / L, 1.8 g / L, 0.2 g / L, 0.2 g / L, 0.1 g / L, 0.1 g / L, and 0.1 g / L, respectively. The concentration of yeast extract in the reaction solution was 0.1 g / L.

[0014] In a preferred embodiment of the present invention, in step 2, the reaction conditions are set as follows: temperature 29-35°C, pH 1.8-2.0, aeration rate 0.6-0.8 vvm, stirring speed 120-150 rpm, and reaction time 48-72 h.

[0015] In a preferred embodiment of the present invention, in step 3, the chemical desulfurization reagent is a peracetic acid solution or a mixed solution; the mixed solution includes ferric nitrate and hydrogen peroxide; the mass concentration of the peracetic acid solution is 15%; the mass concentration of ferric nitrate in the mixed solution is 5%, and the mass concentration of hydrogen peroxide is 8%.

[0016] In a preferred embodiment of the present invention, in step 3, the reaction conditions are set as follows: temperature 50-60°C, solid-liquid ratio 1g:5-6mL, rotation speed 200rpm, and reaction time 90-120min.

[0017] In a preferred embodiment of the present invention, step 2 further includes adding an alkaline substance to the biological residue to precipitate iron ions and sulfate ions; step 3 further includes distilling, neutralizing or concentrating and crystallizing the chemical residue.

[0018] The present invention also provides a system for the above-mentioned coal desulfurization method, comprising a pretreatment unit 1, a biological oxidation unit 2, a primary solid-liquid separation unit 3, a biological residual liquid treatment unit 4, a secondary chemical desulfurization unit 5, a secondary solid-liquid separation unit 6, a clean coal treatment unit 7, a chemical residual liquid treatment unit 8, and an intelligent control system 9.

[0019] The present invention discloses the following technical effects:

[0020] 1. Biological pretreatment "activates" sulfur (especially organic sulfur), significantly improving the efficiency and depth of subsequent chemical desulfurization. The total desulfurization rate (especially the organic sulfur removal rate) is much higher than that of single biological methods or traditional chemical methods.

[0021] 2. Thanks to biological pretreatment, the chemical desulfurization stage can use milder conditions, such as low temperature, short time, low concentration, and mild reagents, which greatly reduces energy consumption, equipment corrosion risk, and operational hazards.

[0022] 3. Compared to the time required for pure biological desulfurization (several weeks) to achieve the same desulfurization depth, the biological pretreatment time of this invention is significantly shortened (1-4 days). Combined with efficient chemical deep desulfurization, the overall desulfurization cycle is significantly shortened.

[0023] 4. Mild chemical conditions reduce energy consumption and equipment maintenance costs; biological pretreatment utilizes microorganisms, resulting in low raw material costs; and the resource utilization of residual liquid can generate certain economic benefits, partially offsetting treatment costs.

[0024] 5. The biological pretreatment and chemical desulfurization processes are not simply connected in series. Instead, biological "activation" reduces the difficulty of chemical treatment, while chemical "depth" makes up for the shortcomings of biological treatment.

[0025] 6. It can effectively process coals with different sulfur contents and sulfur forms, especially those with high organic sulfur content, and has wide applicability. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the system for coal desulfurization according to the present invention. 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] Unless otherwise specified, the "%" mentioned in this invention refers to a percentage by mass.

[0034] This invention innovatively proposes a multi-stage coupled bio-chemical synergistic method and system for deep coal desulfurization, aiming to solve the problems of long cycles and low efficiency in existing biological desulfurization methods, and harsh conditions, high costs, and significant pollution in chemical desulfurization methods. It achieves efficient, deep, economical, and environmentally friendly removal of inorganic and organic sulfur from coal. Its core idea can be summarized as utilizing the mildness and selectivity of biological methods for organic sulfur "pretreatment" and "activation," disrupting the sulfur structure and improving the efficiency of subsequent chemical desulfurization; then, an optimized chemical method is used for "deep desulfurization"; and through ingenious material recycling, energy utilization, and reaction processes, efficient coupling and synergy of two-stage or multi-stage processes are achieved.

[0035] The coal desulfurization method of the present invention is as follows:

[0036] (1) Crush and grind the raw coal to a suitable particle size (e.g., <0.5mm) to increase the reaction contact area. Preliminary physical separation (e.g., flotation) can be carried out to remove some of the easily desorbable inorganic sulfur.

[0037] (2) The pretreated coal powder is mixed with a bioreactor containing specific desulfurization microorganisms (e.g., *Thiobacillus ferrooxidans* for oxidizing pyrite sulfur + specific organic sulfur-degrading bacteria) to form a coal slurry. Under mild conditions, a bio-oxidation reaction is carried out in a specially designed bioreactor (e.g., a stirred tank reactor or airlift reactor with aeration device to ensure good mass transfer and oxygen supply). The main purpose is to partially oxidize and decompose pyrite sulfur and initially attack and "activate" the organic sulfur bonds (e.g., CS bonds) in the macromolecular structure of coal, making them more susceptible to subsequent chemical reagents. Part of the liquid after the reaction can be recycled to replenish fresh culture medium and microorganisms and maintain the activity of the reaction system.

[0038] (3) The reacted coal slurry undergoes solid-liquid separation to obtain pre-treated coal powder (wet coal cake) and a biological residue rich in sulfate, iron ions, and microorganisms. The biological residue enters a neutralization sedimentation tank, where alkaline substances (such as lime milk Ca(OH)2) are added to neutralize the acidity and precipitate iron ions (forming Fe(OH)3) and some sulfate ions (forming CaSO4). The precipitate can be used as iron concentrate or building materials. Part of the supernatant can be returned to the bioreactor for recycling (to adjust pH and replenish ions), while part meets discharge standards, thus preventing secondary pollution of the acidic wastewater generated in this process.

[0039] (4) The wet coal cake is mixed with the optimized chemical desulfurization reagent in a closed reactor equipped with stirring and heating to oxidize and decompose the residual inorganic sulfur and activated organic sulfur after biological pretreatment, generating soluble sulfate or elemental sulfur. The mixture after the reaction is subjected to solid-liquid separation to obtain deeply desulfurized clean coal and chemical residue, which enters the processing unit. If elemental sulfur is generated, it can be recovered. Residual acid / alkali can be neutralized. The sulfate solution can be concentrated and crystallized for recovery (e.g., Na2SO4) or subjected to other harmless treatment.

[0040] (5) Wash and dry the desulfurized coal to obtain the final low-sulfur clean coal product.

[0041] In this invention, the following method is employed: Figure 1 The system shown is for coal desulfurization. The system includes a pretreatment unit 1, a biological oxidation unit 2 (for biological pretreatment), a primary solid-liquid separation unit 3, a biological residual liquid treatment unit 4, a secondary chemical desulfurization unit 5 (for chemical desulfurization), a secondary solid-liquid separation unit 6, a clean coal treatment unit 7, a chemical residual liquid treatment unit 8, and an intelligent control system 9. Specifically, each unit can be:

[0042] 1. Pre-processing unit: crusher, grinder;

[0043] 2. Primary biological oxidation unit: bioreactor (with stirring, aeration / ventilation, temperature control, and pH monitoring and adjustment devices), and biological reaction solution preparation and storage tank;

[0044] 3. Primary solid-liquid separation unit: filter or centrifuge;

[0045] 4. Biological residual liquid treatment unit: neutralization sedimentation tank, solid-liquid separation equipment (such as filter press), residual liquid circulation pipeline;

[0046] 5. Secondary chemical desulfurization unit: chemical desulfurization reactor (with stirring, heating, and sealing devices), chemical reagent storage and metering addition device;

[0047] 6. Secondary solid-liquid separation unit: filter or centrifuge;

[0048] 7. Coal processing unit: washing tank, dryer;

[0049] 8. Chemical residue treatment unit: sulfur recovery device, neutralization tank, evaporation crystallization equipment or other wastewater treatment facilities;

[0050] 9. Intelligent control system: temperature sensor, pH sensor, controller, etc.

[0051] This invention designs a two-stage residual liquid treatment unit, which effectively solves the problem of secondary pollution of waste liquid and realizes partial resource recovery; the two-stage residual liquid treatment ensures environmental protection and forms an efficient and synergistic overall process.

[0052] 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.

[0053] The *Acidithiobacillus ferrooxidans* used in this invention were purchased from Qingdao Haibo Biotechnology Co., Ltd.; the organosulfur-specific degrading bacteria were *Rhodococcus erythropolis*, from the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC 1.1525; *Bacillus subtilis*, from the China Industrial Microbiological Culture Collection Center (CICC10001); and *Paenibacillus polymyxa*, from the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC 1.2233. The modified Starkey medium was purchased from Sinopharm Chemical Reagent Co., Ltd., modified by the addition of 0.1 g / L yeast extract. All chemical reagents used were of analytical grade.

[0054] 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.

[0055] Example 1

[0056] Step 1, Crushing: Bituminous coal from Shanxi, with a sulfur content of 3.2% and organic sulfur accounting for 40%, is crushed to a particle size of ≤0.45mm.

[0057] Step 2, Biological Pretreatment: The crushed bituminous coal from Step 1 is placed in a reaction solution for biological pretreatment. The reaction solution uses 9K medium + trace elements (pH = 2.0). The trace elements are 50.0 g / L MgNO3·6H2O, 2.2 g / L ZnSO4·7H2O, 0.6 g / L CuSO4·5H2O, 1.8 g / L MnSO4·H2O, 0.2 g / L CoCl2·6H2O, 0.2 g / L Na2MoO4·2H2O, 0.1 g / L H3BO3, and 2.0 g / L CaCl2·2H2O. The concentration of trace elements in the reaction solution is 1 × 10⁻⁶. 8 CFU / mL of *Acidithiobacillus ferrooxidans* and a concentration of 5×10 7 CFU / mL of salt-tolerant Rhodococcus; biological pretreatment was carried out in a 50L airlift bioreactor with a height-to-diameter ratio of 4:1 and made of 316L stainless steel with an anti-corrosion coating, using a 10μm microporous titanium alloy diffuser. The biological pretreatment was conducted for 48 hours at a temperature of 30±1℃, pH=2.0, an aeration rate of 0.8vvm, and a rotation speed of 150rpm. After biological pretreatment, solid-liquid separation was performed to obtain wet coal cake and biological residue. The biological residue entered a neutralization sedimentation tank, where alkaline substances (lime milk Ca(OH)2) were added to adjust the pH to 8.5 to neutralize the acidity and precipitate iron ions (forming Fe(OH)3) and some sulfate ions (forming CaSO4). The precipitate can be used as iron concentrate or building materials. Part of the supernatant can be returned to the bioreactor for recycling (to adjust pH and replenish ions), and part is discharged after meeting standards, thus preventing secondary pollution of the acidic wastewater generated in this process.

[0058] Step 3, Chemical Desulfurization: In the chemical desulfurization stage, a design pressure of 0.8 MPa and a stirring power of 5.5 kW / m are selected. 3An anchor-type agitator and a sealed stirred tank with a polytetrafluoroethylene liner and a rotation speed of 0-200 rpm were used. The wet coal cake obtained in step 2 was placed in the sealed stirred tank, and a 15% peracetic acid solution (distilled water as solvent) was added. The reaction was carried out at 60℃, a solid-liquid ratio of 1:5 (g / mL), and a rotation speed of 200 rpm for 90 min. Afterward, solid and liquid separation was performed, and the obtained solid was washed and dried to obtain deeply desulfurized clean coal and chemical residue. The chemical residue was distilled to recover elemental sulfur. After chemical desulfurization, the desulfurization efficiency of inorganic sulfur was 92%, the desulfurization efficiency of organic sulfur was 85%, the final sulfur content of the clean coal was 0.3454%, and the desulfurization rate was 89.2%.

[0059] Comparative Example 1 (Single Biological Method)

[0060] The only difference from Example 1 is that the biological pretreatment reaction time in step 2 was extended from 48 hours to 21 days (504 hours) to simulate the cycle required to achieve the theoretical maximum desulfurization efficiency of a single biological method, and step 3 was omitted. After the reaction, the coal slurry was subjected to solid-liquid separation to obtain desulfurized coal and biological residue. The desulfurized coal was washed and dried to obtain the final product, which had a sulfur content of 1.57%.

[0061] Comparative Example 1, using a single biological method, achieved a total desulfurization rate of 51% and an organic sulfur removal rate of 38%.

[0062] Comparative Example 2 (Traditional Chemical Method)

[0063] The only difference from Example 1 is that step 2 is omitted, and step 3 uses a traditional high-strength chemical desulfurization reagent, namely a strong acid oxidation system consisting of a 30% (v / v) hydrogen peroxide (H₂O₂) solution and a 2M sulfuric acid (H₂SO₄) solution mixed in a 1:1 volume ratio. The coal powder obtained in step 1 is placed in a sealed stirred tank with a polytetrafluoroethylene liner, similar to that in Example 1. The aforementioned high-strength chemical desulfurization reagent is added, and the experimental conditions are maintained the same as in Example 1. After the reaction is complete, solid-liquid separation is performed to obtain desulfurized coal and chemical residue. The desulfurized coal is washed and dried to obtain the final product, and its sulfur content is determined to be 0.77%.

[0064] Comparative Example 2 used a traditional chemical method (H2O2 / H2SO4) with a total removal rate of 76% and an organic sulfur removal rate of 65%.

[0065] Example 2

[0066] Step 1, Crushing: The lignite from Xinjiang has a sulfur content of 2.5%, of which organic sulfur accounts for 85%, mainly thiophenes and sulfides, and is crushed to ≤0.3mm.

[0067] Step 2, Biological Pretreatment: The crushed lignite from Step 1 is placed in a reaction solution for biological pretreatment. The reaction solution uses modified Starkey medium (pH = 1.8, containing 0.1 g / L yeast extract) and contains 1 × 10⁻⁶ g / L of yeast extract. 8 CFU / mL of *Acidithiobacillus ferrooxidans* and a concentration of 8 × 10⁻⁶ 7 CFU / mL of Bacillus polymyxa and a concentration of 5×10 7 Bacillus subtilis at CFU / mL was used for biological pretreatment in a 100L mechanically stirred tank bioreactor made of 316L stainless steel. The pretreatment was carried out at 35℃, pH 1.8, aeration rate of 0.6 vvm, and stirring speed of 120 rpm for 72 hours. After pretreatment, solid-liquid separation was performed to obtain wet coal cake and biological residue. The biological residue entered a neutralization sedimentation tank, where alkaline substances (lime milk Ca(OH)2) were added to adjust the pH to 8.0 to neutralize the acidity and precipitate iron ions (forming Fe(OH)3) and some sulfate ions (forming CaSO4). The precipitate can be used as iron concentrate or building material. Part of the supernatant can be returned to the bioreactor for recycling (to adjust pH and replenish ions), while the remainder meets discharge standards, thus preventing secondary pollution of the acidic wastewater generated in this process.

[0068] Step 3, Chemical Desulfurization: In the chemical desulfurization stage, an enamel-lined closed reactor (acid-resistant pressure vessel) with a double-layer turbine propeller and a rotation speed of 0-200 rpm is selected. The wet coal cake obtained in Step 2 is placed in this closed reactor, and a solution containing 5% ferric nitrate (Fe(NO3)3) and 8% hydrogen peroxide (H2O2) (solvent is distilled water) is added. The reaction is carried out at a temperature of 50℃, a solid-liquid ratio of 1:6 (g / mL), and a rotation speed of 200 rpm for 120 min. Afterward, solid and liquid are separated, and the obtained solid is washed and dried to obtain deeply desulfurized clean coal and chemical residue. The chemical residue is then subjected to vacuum distillation and crystallization to recover elemental sulfur. After chemical desulfurization, the desulfurization efficiency of inorganic sulfur is 95%, the desulfurization efficiency of organic sulfur is 89%, the final sulfur content of the clean coal is 0.2525%, and the desulfurization rate is 89.9%.

[0069] Comparative Example 3 (Single Biological Method)

[0070] Step 1, Crushing: The lignite from Xinjiang has a sulfur content of 2.5%, of which organic sulfur accounts for 85%, mainly thiophenes and sulfides, and is crushed to ≤0.3mm.

[0071] Step 2: The crushed lignite from Step 1 is placed in a reaction solution for biological single-mode desulfurization. The reaction solution uses modified Starkey medium (pH = 1.8, containing 0.1 g / L yeast extract) and contains 1 × 10⁻⁶ g / L of yeast extract. 8 CFU / mL of *Acidithiobacillus ferrooxidans* and a concentration of 8 × 10⁻⁶ 7CFU / mL of Bacillus polymyxa and a concentration of 5×10 7 CFU / mL Bacillus subtilis was used in a 100L mechanically stirred tank bioreactor made of 316L stainless steel. The reaction was carried out at 35℃, pH=1.8, aeration rate of 0.6vvm, and stirring speed of 120rpm for 168h. After 168h of enhanced biological treatment, solid-liquid separation was performed, and the clean coal was washed, dried, and tested. The final sulfur content of the clean coal was 1.43%.

[0072] In Comparative Example 3, the organic sulfur desulfurization efficiency using a single biological method was 43%.

[0073] Comparative Example 4 (Traditional H2O2 Oxidation Method)

[0074] Step 1, Crushing: The lignite from Xinjiang has a sulfur content of 2.5%, of which organic sulfur accounts for 85%, mainly thiophenes and sulfides, and is crushed to ≤0.3mm.

[0075] Step 2: Select an enamel-lined sealed reactor (acid-resistant pressure vessel) with a double-layer turbine propeller and a rotation speed of 0-200 rpm. Place the crushed lignite from Step 1 into this sealed reactor, add a small amount of distilled water to wet the coal powder, and then adjust the initial pH of the reaction system to 2.0–2.5 with dilute nitric acid (HNO3). Subsequently, add an 8% (w / w) aqueous solution of hydrogen peroxide (H2O2) to achieve a solid-liquid ratio of 1:6 (g / mL). React for 180 min at a temperature of 50℃ and a rotation speed of 200 rpm. After the reaction, perform solid-liquid separation, thoroughly wash, dry, and test the clean coal. The final sulfur content of the clean coal is 0.71%.

[0076] In Comparative Example 4, the organic sulfur desulfurization efficiency using the traditional H2O2 oxidation method was 71.6%.

[0077] Comparative Example 5

[0078] The only difference from Example 2 is that Bacillus subtilis in step 2 is replaced with an equal amount of Bacillus polymyxa.

[0079] The desulfurization efficiency of organic sulfur in Comparative Example 5 was 80.0%.

[0080] Comparative Example 6

[0081] The only difference from Example 2 is that the Bacillus polymyxa in step 2 is replaced with an equal amount of Bacillus subtilis.

[0082] The desulfurization efficiency of organic sulfur in Comparative Example 6 was 83.5%.

[0083] 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 desulfurizing coal, characterized in that, Includes the following steps: Step 1, coal crushing; Step 2, biological pretreatment: The crushed coal is placed in a reaction solution for reaction, and solid-liquid separation is performed to obtain wet coal cake and biological residue; Step 3, chemical desulfurization: The wet coal cake is placed in a chemical desulfurization reagent for reaction, and solid-liquid separation is performed to obtain clean coal and chemical residue.

2. The coal desulfurization method according to claim 1, characterized in that, In step 1, the coal is crushed to a particle size of no more than 0.5 mm.

3. The coal desulfurization method according to claim 1, characterized in that, In step 2, the reaction solution includes a culture medium and bacteria; the culture medium is 9K medium or Starkey medium; the bacteria are at least one of ferrooxidizobacillus, halophyte Rhodococcus, polymyxa, and Bacillus subtilis.

4. The coal desulfurization method according to claim 3, characterized in that, The concentration of bacteria in the reaction solution was (1.5–2.5) × 10⁻⁶. 8 CFU / mL; pH of the reaction solution is 1.8–2.

0.

5. The coal desulfurization method according to claim 3, characterized in that, The reaction solution also includes trace elements or yeast extract; the trace elements include MgNO3·6H2O, ZnSO4·7H2O, CuSO4·5H2O, MnSO4·H2O, CoCl2·6H2O, Na2MoO4·2H2O, H3BO3, and CaCl2·2H2O; the concentration of MgNO3·6H2O in the reaction solution is 50.0 g / L, the concentration of ZnSO4·7H2O in the reaction solution is 2.2 g / L, and the concentration of CuSO4·6H2O is 2.2 g / L. The concentrations of ·5H2O, MnSO4·H2O, CoCl2·6H2O, Na2MoO4·2H2O, H3BO3, and CaCl2·2H2O in the reaction solution were 0.6 g / L, 1.8 g / L, 0.2 g / L, 0.2 g / L, 0.1 g / L, 0.1 g / L, and 0.0 g / L, respectively. The concentration of yeast extract in the reaction solution was 0.1 g / L.

6. The coal desulfurization method according to claim 1, characterized in that, In step 2, the reaction conditions are set as follows: temperature 29-35℃, pH 1.8-2.0, aeration rate 0.6-0.8 vvm, stirring speed 120-150 rpm, and reaction time 48-72 h.

7. The coal desulfurization method according to claim 1, characterized in that, In step 3, the chemical desulfurization reagent is a peracetic acid solution or a mixed solution; the mixed solution includes ferric nitrate and hydrogen peroxide; the mass concentration of the peracetic acid solution is 15%; the mass concentration of ferric nitrate in the mixed solution is 5%, and the mass concentration of hydrogen peroxide is 8%.

8. The coal desulfurization method according to claim 1, characterized in that, In step 3, the reaction conditions are set as follows: temperature 50-60℃, solid-liquid ratio of 1g:5-6mL, and rotation speed of 200rpm for 90-120min.

9. The coal desulfurization method according to claim 1, characterized in that, Step 2 also includes adding an alkaline substance to the biological residue to precipitate iron ions and sulfate ions; Step 3 also includes distilling, neutralizing or concentrating and crystallizing the chemical residue.

10. A system for use in the coal desulfurization method according to any one of claims 1 to 8, characterized in that, It includes a pretreatment unit (1), a biological oxidation unit (2), a primary solid-liquid separation unit (3), a biological residual liquid treatment unit (4), a secondary chemical desulfurization unit (5), a secondary solid-liquid separation unit (6), a clean coal treatment unit (7), a chemical residual liquid treatment unit (8), and an intelligent control system (9).

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