Resource utilization method for extraction residue from coal liquefaction solid residue

Abstract

A resource utilization method for extraction residue from coal liquefaction solid residue. The method comprises the following steps: 1) fully mixing extraction residue from coal liquefaction solid residue with a solvent to prepare a solid-containing slurry, and grinding the solid material in the solid-containing slurry until the granularity D50 of said material is 5 nm or less; 2) using a magnetic separation device to perform magnetic separation on the solid-containing slurry obtained in step 1) so as to obtain a concentrate A1 enriched with an iron catalyst, and remaining tailings B2; and 3) washing the concentrate A1 off from the magnetic separation device by using a solvent to obtain a slurry containing the concentrate A1, and drying the slurry containing the concentrate A1 to obtain a dry powder material A2, which is used as a catalyst in a direct coal liquefaction reaction. The iron catalyst recovered by means of the resource utilization method for extraction residue from coal liquefaction solid residue has relatively high purity; and when the iron catalyst is used in a direct liquefaction reaction, only a small amount of the catalyst is needed, and few inert components are carried, thereby effectively improving the volume utilization rate of a reactor.

Description

Resource utilization method of coal liquefaction solid slag residue

[0001] This application is based on the Chinese application with CN application number 2024103358267 and application date March 22, 2024, and claims its priority. The disclosed content of the CN application is again introduced as a whole into this application. Technical Field

[0002] The present invention belongs to the technical field of direct coal liquefaction. Specifically, it relates to a method for resource utilization of coal liquefaction solid slag residue. After the iron catalyst phase is fully separated from other substances by solvent extraction and wet ultrafine grinding, the enriched active iron catalyst is obtained by wet magnetic separation. The recovered catalyst is then used in the direct liquefaction reaction, and the reaction effect is good. Background Art

[0003] During the coal liquefaction production process, liquefied oil residue accounting for about 30% of the raw coal will be produced. After the coal liquefaction oil residue is subjected to solvent oil extraction, heavy oil and asphalt can be obtained, and this part of the material can be further processed and utilized. The remaining heavy phase is recovered after the solvent is recovered to obtain coal liquefaction solid residue extract powder particles, which have a particle size of micron level. It is a high-carbon, high-ash, high-sulfur and complex composition mixture, mainly composed of unconverted coal, heavy asphalt, and inorganic ash. Due to its high calorific value, it is currently mainly used for gasification, combustion, pyrolysis, etc. These methods cannot maximize the utilization of carbon-based components and inorganic ash (minerals in raw coal + iron-based catalysts, etc.) in coal liquefaction solid residue, and the iron therein is easy to agglomerate and aggregate at high temperatures, which has the risk of slag blocking, and greatly affects the effect of gasification or combustion.

[0004] The iron content in coal liquefaction residues is approximately 5-8% by weight. The iron distribution and composition of the iron in the coal liquefaction residues after direct liquefaction are unclear, but it may exist in various oxide and sulfide forms. It is generally believed that the iron in the coal liquefaction residues is poisoned or deactivated, and no longer has catalytic activity.

[0005] Due to the industrialization of coal liquefaction, the amount of coal liquefaction solid slag extract residue is very huge. How to utilize coal liquefaction solid slag extract residue as a resource and realize high value of waste has great economic significance. Summary of the Invention

[0006] The present invention aims to provide a method for resource utilization of coal liquefaction solid slag residue to fully tap the value of the industrial chain.

[0007] In order to fully develop the maximum value of coal liquefaction solid residue, the inventors of the present invention conducted a thorough study on the coal liquefaction solid residue and found that the iron in the coal liquefaction solid residue is in the form of pyrrhotite Fe 1-xIt exists in the form of S compounds and is adhered and wrapped by heavy asphalt.

[0008] Based on the above findings, the present invention is proposed.

[0009] The present invention provides a method for resource utilization of coal liquefaction solid slag residue, which comprises the following steps:

[0010] 1) The coal liquefaction solid residue extract is fully mixed with a solvent to prepare a solid slurry, and the solid material in the solid slurry is ground to a material particle size D50 of less than 5 μm;

[0011] 2) Using magnetic separation equipment to magnetically separate the solid-containing slurry obtained in step 1) to obtain the iron catalyst-enriched concentrate A1 and the remaining tailings B2;

[0012] 3) The concentrate A1 is washed from the magnetic separation device with a solvent to obtain a slurry containing the concentrate A1, and the slurry containing the concentrate A1 is dried to obtain a dry powder material A2, which is used as a catalyst for the direct coal liquefaction reaction.

[0013] In a preferred embodiment, the particle size D50 of the dry powder material A2 is less than 100 μm, preferably less than 60 μm.

[0014] When the particle size D50 of the dry powder material A2 is within the above range, the reduction in the particle size of the catalyst helps to improve the dispersibility in the reaction system and enhance its catalytic performance.

[0015] In a preferred embodiment, the iron content in the dry powder material A2 is 9 wt.% to 25 wt.%, preferably 11 wt.% to 25 wt.%, based on 100 wt.% of the total weight of the dry powder material A2.

[0016] When the iron content of the dry powder material A2 is within the above range, it is beneficial to control the content of the active components of the catalyst.

[0017] In a preferred embodiment, tailings B2 are treated by spray drying to recover the solvent, and then blended into the gasification feedstock coal as a feedstock for gasification hydrogen production. The remaining tailings B2, a non-magnetic material containing the solvent after magnetic separation, can provide the hydrogen required for the direct coal liquefaction production unit, achieving a circular economy effect.

[0018] In a preferred embodiment, in step 1), the solid content of the solid-containing slurry is 10 wt.% to 40 wt.%, preferably 20 wt.% to 35 wt.%.

[0019] When the solid content of the solid-containing slurry is controlled within the above range, it is beneficial to separate the catalyst from the coal liquefaction solid slag residue.

[0020] In a preferred embodiment, the solvents in step 1) and step 3) are water or an organic solvent, respectively, and the organic solvent is selected from one or more of n-hexane, toluene, xylene, carbon disulfide, dichloromethane, carbon tetrachloride, washing oil, pyridine, tetrahydrofuran and quinoline.

[0021] In a preferred embodiment, in step 1), the solid material in the solid-containing slurry is ground until the particle size D50 of the solid material in the slurry is 3 μm or less, preferably 2 μm or less, and more preferably 1 μm or less. By grinding the solid material to the micrometer or nanometer scale, the iron catalyst and the organic matter are fully separated.

[0022] In a preferred embodiment, in step 1), grinding is performed using a ball mill, rod mill, or sand mill. More preferably, grinding is performed using one or more selected from a stirred ball mill, a nano sand mill, and a planetary grinder. A single mill or multiple mills connected in series may be used. The inner lining and grinding media of the grinding apparatus are made of non-magnetic materials, such as ceramic, polyurethane, carbon nanotubes, etc.

[0023] In a preferred embodiment, in step 2), the magnetic separation equipment is a high gradient magnetic separator selected from electromagnetic, permanent magnetic or combined types, preferably a high gradient magnetic separator with an external uniform magnetic field and a superimposed magnetic field of a magnetic medium (such as steel wool, steel rods, steel balls, steel plates, etc.).

[0024] Figure 1 shows a schematic diagram of the high-gradient magnetic field formation process. The magnetic lines of force of a uniform magnetic field are uniform from the north pole to the south pole. When a magnetic metal wire is added, it is magnetized and also excites its own magnetic field. The total effect is the superposition of (a) and (b), which weakens the magnetic field near the upper and lower surfaces of the metal wire, while greatly strengthening the magnetic field near the two poles of the external magnetic field, forming a high-gradient magnetic field region (c) near the surface of the metal wire that varies with distance.

[0025] The periodic pulsating high-gradient magnetic separator is one of the many high-gradient magnetic separators designed using this principle. The device structure is shown in Figure 2. It primarily consists of a feed chamber 1, a magnetic pole head 2, an iron yoke 3, an excitation coil 4, a magnetic concentrator 5, a pulsating bucket 6, a pulsating mechanism 7, and a regulating valve 8. The iron yoke 3 is the ferromagnetic portion without a coil wound around it, connecting the upper and lower magnetic heads to form a closed circuit. During operation, the pulsating mechanism 7 is activated, the flow rate is adjusted, and direct current is passed through the excitation coil 4. The excitation current is adjusted to the desired background magnetic induction intensity. The magnetic concentrator 5 is magnetized in the magnetic field, forming a high-gradient magnetic field on its surface. A well-stirred, loose solid-containing slurry is fed from the feed chamber 1 and flows through the holes in the upper magnetic pole head 2 into the separation chamber. Magnetic particles in the slurry are attracted to the surface of the magnetic medium. Non-magnetic particles flow through the holes in the lower magnetic pole head and are discharged into the pulsating bucket 6. After each feeding cycle is completed, water or an organic solvent is added to rinse the concentrate. The excitation power supply is then disconnected and the magnetic material is flushed out with water or an organic solvent, completing a beneficiation cycle. Within the uniform magnetic field generated by the excitation coil 4, a magnetic concentrator 5, such as a steel plate or rod, is placed. This magnetization produces a highly non-uniform, high-gradient magnetization field on its radial surface. Paramagnetic materials in this field experience a magnetic attraction proportional to the product of the applied magnetic field and the magnetic field gradient. This high-gradient, non-uniform magnetic field separates weakly magnetic, fine-grained materials that are difficult to separate with conventional magnetic separators. Furthermore, a pulsating mechanism 7 drives the magnetic concentrator 5 in an up-and-down reciprocating motion within the material pile. The pulsating fluid force keeps the solid particles loose, effectively eliminating mechanical inclusions of non-magnetic particles and significantly improving the grade of the magnetic concentrate.

[0026] In a preferred embodiment, in step 2), when an organic solvent is used as a medium to prepare the slurry, since the solid slag residue contains organic matter such as residual extraction solvent and heavy asphalt, according to the type of organic solvent selected and the principle of like dissolves like, the organic solvent can dissolve and wash part of the organic matter, which is beneficial to separate the iron catalyst adhered to and wrapped by the heavy asphalt. Therefore, the magnetic field strength acting on the coal liquefaction solid slag residue slurry is 2000~5000Gs, preferably, the magnetic field strength acting on the solid-containing slurry is 3000~4000Gs; when water is used as a medium to prepare the slurry, compared with using an organic solvent, the dilution and stripping effects are weaker, but the cost is lower and the dosage selection space is larger. Therefore, it is necessary to increase the magnetic field strength acting on the solid-containing slurry to achieve a better enrichment effect, generally 5000~13000Gs, preferably, the magnetic field strength acting on the solid-containing slurry is 7000~9000Gs.

[0027] In a preferred embodiment, in step 3), a solvent is used to flush the concentrate A1 adsorbed on the magnetic medium to obtain a slurry containing the concentrate A1. Therefore, in step 3), the slurry containing the concentrate A1 is dried and / or the solvent is recovered by vacuum drying, nitrogen drying, distillation, or spray drying; preferably, spray drying is used for drying and / or solvent recovery.

[0028] In a preferred embodiment, the method for resource utilization of coal liquefaction solid slag residue further comprises the following steps:

[0029] 4) The dry powder material A2 obtained in step 3) is used as a coal direct liquefaction catalyst for a coal direct liquefaction reaction.

[0030] Preferably, the amount of dry powder material A2 added is such that the mass ratio of Fe in A2 to dry coal is 0.5wt.% to 10wt.%, preferably 0.5wt.% to 5wt.%, and further more preferably 1wt.% to 3wt.%.

[0031] When the addition amount is within the above range, the coal conversion rate and oil yield both reach the optimal value. Continuing to add will increase the ash content in the system; if the addition amount is too low, the coal conversion rate and oil yield will not reach the optimal value.

[0032] Preferably, the reaction conditions are:

[0033] The reaction temperature is 400-470°C, preferably 430-465°C;

[0034] The reaction pressure is 10-20 MPa, preferably 13-20 MPa;

[0035] The reaction residence time is 0.5 to 2 hours.

[0036] In the present invention, an organic solvent is used to extract the solid residue residue of direct coal liquefaction, and an ultrafine grinder is used to grind it. The iron catalyst adhered to and wrapped by heavy asphalt is fully stripped off, and the iron catalyst is recovered by wet magnetic separation. The enriched iron-containing catalyst is used for direct liquefaction reaction. The magnetic field intensity required for wet recovery according to the method of the present invention is low, the enrichment degree of the recovered iron catalyst is high, the iron purity is greatly improved, and the direct liquefaction reaction performance is excellent. The method according to the present invention not only alleviates the supply problem of the catalyst iron source, but also reduces the discharge of direct coal liquefaction solid residue, and effectively improves the overall economic benefit of direct liquefaction technology while realizing the hierarchical clean utilization of solid waste.

[0037] The present invention has at least three advantages:

[0038] (1) It effectively solves the problem of difficulty in recovering and separating the solid residue due to the complex components and the nano-scale iron catalyst being wrapped and adhered therein;

[0039] (2) The solvent used can be recovered by distillation or spray drying and recycled, saving production costs;

[0040] (3) The extracted and recovered iron catalyst has a high purity and is used in small amounts for direct liquefaction reaction. It carries less inert components and effectively improves the volume utilization of the reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG1 is a schematic diagram showing the principle of the high gradient magnetic field formation process.

[0042] Figure 2 is a schematic diagram of a periodic pulsating high gradient magnetic separator.

[0043] FIG3 is an XRD spectrum of the coal liquefaction solid slag residue.

[0044] FIG4 is an XRD spectrum of the dry powder particles after wet magnetic separation and drying to recover the solvent in Example 1.

[0045] Reference numerals 1-feeding chamber; 2-pole head; 3-iron yoke; 4-excitation coil; 5-magnetic concentrating medium; 6-pulsating bucket; 7-pulsating mechanism; 8-regulating valve. DETAILED DESCRIPTION

[0046] The present invention will be described in detail below with reference to examples. It should be understood that the examples are only used to further illustrate the present invention, rather than to limit the scope of the present invention.

[0047] raw material

[0048] Coal liquefaction solid residue extraction (Ordos 350,000 tons / year coal liquefaction oil residue extraction, China Shenhua Coal to Liquids Chemical Co., Ltd. Ordos Branch);

[0049] The industrial analysis and elemental analysis of the coal liquefaction solid residue are shown in the following table:

[0050] Table 1: Properties of coal liquefaction solid residue

[0051] Mad refers to the water content on an air-dry basis; Ad refers to the ash content on a dry basis; Vdaf refers to the volatile matter on a dry ash-free basis; C, H, O, N, and S refer to the content of each element respectively.

[0052] The ash chemical composition and content of the coal liquefaction solid slag residue were analyzed. The ash chemical composition of the coal liquefaction solid slag residue is shown in Table 2:

[0053] Table 2: Ash chemical composition of coal liquefaction solid residue

[0054] The content of Fe2O3 in the coal liquefaction solid slag extract was calculated from the ash content in the coal liquefaction solid slag extract and the weight proportion of Fe2O3 in the ash. The iron content in the coal liquefaction solid slag extract was further calculated from the molecular formula to be 5.96wt.%.

[0055] The XRD crystal form analysis results of coal liquefaction solid residue are shown in Figure 3. The XRD peaks are mainly inorganic substances with obvious crystal forms in the ash. The organic substances in coal liquefaction solid residue generally have no crystal forms and therefore do not produce peaks. As shown in Figure 3, the inorganic substances in coal liquefaction solid residue mainly include CaCO3, Fe 1-x S, CaSO4 and SiO2, among which the iron-containing species is still mainly pyrrhotite Fe 1-x The catalyst active state of S exists. Pyrrhotite itself is a paramagnetic substance with certain magnetic properties. Based on this, the inventors of the present invention proposed the resource utilization method of coal liquefaction solid slag residue.

[0056] Example 1

[0057] The coal liquefaction solid residue extract was fully mixed with quinoline to prepare a solid-containing slurry with a concentration of 25 wt.%, and the material was ground using a nano-sand mill until the material particle size D50 was 0.7 μm; the solid-containing slurry was magnetically separated using a high gradient magnetic separator (Ganzhou Jinhuan Magnetic Separation Technology Equipment Co., Ltd., SLon-100 periodic pulsating high gradient magnetic separator), and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 3500 Gs to obtain a concentrate enriched in iron catalyst, and the concentrate was washed from the high gradient magnetic separator with quinoline to obtain a slurry containing the concentrate; the quinoline in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, and the yield (dry powder particles / solid residue mass ratio) was 19.87 wt.%; the particle size D50 was measured to be 15.6 μm, and the iron content was 22.8 wt.%. After the solvent is recovered from the tailings, it is mixed with raw coal for co-gasification to produce hydrogen.

[0058] FIG4 is an XRD spectrum of the dry powder particles after wet magnetic separation and drying to recover the solvent in Example 1. As shown in FIG4, compared with the XRD spectrum of the solid slag residue from coal liquefaction (FIG3), the types of inorganic crystals corresponding to the peak positions are completely consistent, indicating that the use of physical magnetic separation does not substantially change the occurrence state of the species, especially the existence form of the iron catalyst, and the iron still exists in the form of Fe 1-x S active state exists.

[0059] Example 2

[0060] The coal liquefaction solid residue extract was fully mixed with tetrahydrofuran to prepare a solid-containing slurry with a concentration of 15 wt.%, and the material was ground using a nano sand mill to a particle size D50 of 0.8 μm. The solid-containing slurry was magnetically separated using a high gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 4000 Gs to obtain a concentrate enriched in iron catalyst. The concentrate was washed from the high gradient magnetic separator with tetrahydrofuran to obtain a slurry containing the concentrate. The tetrahydrofuran in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 17.24 wt.%. The particle size D50 was measured to be 18.6 μm, and the iron content was 20.8 wt.%.

[0061] Example 3

[0062] The coal liquefaction solid residue extract was fully mixed with carbon tetrachloride to prepare a solid-containing slurry with a concentration of 25wt.%, and the material was ground using a nano sand mill to a particle size D50 of 0.9μm; the solid-containing slurry was magnetically separated using a high gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 4500Gs to obtain a concentrate enriched in iron catalyst, and the concentrate was washed from the high gradient magnetic separator with carbon tetrachloride to obtain a slurry containing the concentrate; the carbon tetrachloride in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 14.29wt.%; the particle size D50 was measured to be 24.9μm, and the iron content was 18.1wt.%.

[0063] Example 4

[0064] The coal liquefaction solid residue extract was fully mixed with carbon disulfide to prepare a solid-containing slurry with a concentration of 25wt.%, and the material was ground by a planetary ball mill to a particle size D50 of 1.5μm; the solid-containing slurry was magnetically separated by a wet permanent magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 3000Gs to obtain a concentrate enriched in iron catalyst, and the concentrate was washed from the high gradient magnetic separator with carbon disulfide to obtain a slurry containing the concentrate; the carbon disulfide in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 13.65wt.%; the particle size D50 was measured to be 38.7μm, and the iron content was 17.3wt.%.

[0065] Example 5

[0066] The coal liquefaction solid residue extract was fully mixed with xylene to prepare a solid-containing slurry with a concentration of 33wt%, and the material was ground by a stirred ball mill to a particle size D50 of 3μm; the solid-containing slurry was magnetically separated by a wet electromagnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 2500Gs to obtain a concentrate enriched in iron catalyst, and the concentrate was washed from the high gradient magnetic separator with xylene to obtain a slurry containing the concentrate; the xylene in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 13.91wt.%; the particle size D50 was measured to be 56.4μm, and the iron content was 15.9wt.%.

[0067] Example 6

[0068] The coal liquefaction solid residue extract was fully mixed with n-hexane to prepare a solid-containing slurry with a concentration of 25wt.%, and the material was ground using a nano sand mill to a particle size D50 of 2μm; the above-mentioned solid-containing slurry was magnetically separated using a high gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 3500Gs to obtain a concentrate enriched in iron catalyst, and the concentrate was washed from the high gradient magnetic separator with n-hexane to obtain a slurry containing the concentrate; the n-hexane in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 12.47wt.%; the particle size D50 was measured to be 63.5μm, and the iron content was 14.5wt.%.

[0069] Example 7

[0070] The coal liquefaction solid residue extract was fully mixed with deionized water to prepare a solid-containing slurry with a concentration of 25wt.%, and the material was ground using a nano sand mill to a particle size D50 of 0.8μm. The solid-containing slurry was magnetically separated using a high gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 8000Gs to obtain a concentrate enriched in iron catalyst. The concentrate was washed from the high gradient magnetic separator with deionized water to obtain a slurry containing the concentrate. The slurry containing the concentrate was dried by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 10.82wt.%. The particle size D50 was measured to be 88.2μm, and the iron content was 11.4wt.%.

[0071] Example 8

[0072] The coal liquefaction solid residue extract was fully mixed with quinoline to prepare a solid-containing slurry with a concentration of 25wt.%, and the material was ground using a nano sand mill to a particle size D50 of 0.7μm. The solid-containing slurry was magnetically separated using a high gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 3500Gs to obtain a concentrate enriched in iron catalyst. The concentrate was washed from the high gradient magnetic separator with quinoline to obtain a slurry containing the concentrate. The slurry containing the concentrate was dried by vacuum drying to obtain dry powder particles with a particle size of micron level, with a yield of 14.33wt.%. The particle size D50 was measured to be 123.9μm, and the iron content was 19.7wt.%.

[0073] Example 9

[0074] The coal liquefaction solid residue extract was fully mixed with quinoline to prepare a solid-containing slurry with a concentration of 25wt.%, and the material was ground using a nano sand mill to a particle size D50 of 0.7μm. The solid-containing slurry was magnetically separated using a high gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 4500Gs to obtain a concentrate enriched in iron catalyst. The concentrate was washed from the high gradient magnetic separator with quinoline to obtain a slurry containing the concentrate. The quinoline in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 20.05wt.%. The particle size D50 was measured to be 15.3μm, and the iron content was 21.7wt.%.

[0075] Example 10

[0076] The coal liquefaction solid residue extract was fully mixed with quinoline to prepare a solid-containing slurry with a concentration of 25wt.%, and the material was ground using a nano sand mill to a particle size D50 of 0.7μm. The solid-containing slurry was magnetically separated using a high gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 2000Gs to obtain a concentrate enriched in iron catalyst. The concentrate was washed from the high gradient magnetic separator with quinoline to obtain a slurry containing the concentrate. The quinoline in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 14.05wt.%. The particle size D50 was measured to be 12.3μm, and the iron content was 16.7wt.%.

[0077] Example 11

[0078] The coal liquefaction solid residue extract was fully mixed with quinoline to prepare a solid-containing slurry with a concentration of 25 wt.%, and the material was ground using a nano sand mill to a particle size D50 of 0.7 μm. The solid-containing slurry was magnetically separated using a high gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 5000 Gs to obtain a concentrate enriched in iron catalyst. The concentrate was washed from the high gradient magnetic separator with quinoline to obtain a slurry containing the concentrate. The quinoline in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 21.31 wt.%. The particle size D50 was measured to be 15.9 μm, and the iron content was 19.7 wt.%.

[0079] Example 12

[0080] The coal liquefaction solid residue extract was fully mixed with quinoline to prepare a solid-containing slurry with a concentration of 25 wt.%, and the material was ground using a nano sand mill to a particle size D50 of 0.7 μm. The solid-containing slurry was magnetically separated using a high gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 6000 Gs to obtain a concentrate enriched in iron catalyst. The concentrate was washed from the high gradient magnetic separator with quinoline to obtain a slurry containing the concentrate. The quinoline in the concentrate-containing slurry was recovered by spray drying to obtain dry powder particles with a particle size of micron level, with a yield of 25.47 wt.%. The particle size D50 was measured to be 26.8 μm, and the iron content was 12.3 wt.%.

[0081] Comparative Example 1

[0082] The coal liquefaction solid residue extract was fully mixed with quinoline to prepare a solid-containing slurry with a concentration of 25wt.%, and the material was ground using a rod sand mill until the material particle size D50 was 8μm; the above-mentioned solid-containing slurry was magnetically separated using a high-gradient magnetic separator, and the magnetic field strength acting on the coal liquefaction solid residue extract slurry medium was about 3500Gs to obtain a concentrate enriched in iron catalyst, and the concentrate was washed from the high-gradient magnetic separator with quinoline to obtain a slurry containing the concentrate; the quinoline in the concentrate-containing slurry was recovered by distillation recovery to obtain dry powder particles with a particle size of micron level, with a yield of 9.76wt.%; the particle size D50 was measured to be 152.8μm, the iron content was 10.2wt.%, and it was further ground to obtain dry powder particles with a D50 of 58.3μm.

[0083] Comparative Example 2

[0084] The coal liquefaction solid residue extract was fully mixed with quinoline to prepare a solid-containing slurry with a concentration of 25wt.%, and the material was ground using a rod sand mill to a particle size D50 of 8μm; the solid-containing slurry was magnetically separated using a wet electromagnetic separator, and the magnetic field strength acting on the solid residue extract slurry medium was about 2500Gs to obtain a concentrate enriched in iron catalyst, and the concentrate was washed from the high gradient magnetic separator with quinoline to obtain a slurry containing the concentrate; the concentrate-containing slurry was dried in an oven without solvent recovery to obtain dry powder particles with a particle size of micron level, with a yield of 7.19wt.%; the particle size D50 was measured to be 219.5μm, and the iron content was 6.6wt.%.

[0085] Comparative Example 3

[0086] The fresh FeOOH catalyst precursor prepared according to the method of application CN03153377.9 has an iron content of 5.99% and a catalyst particle size D50 of 74 μm. During the catalytic reaction, active Fe 1-x S, acts on the direct coal liquefaction reaction.

[0087] Test Examples

[0088] The catalysts prepared in the examples and comparative examples were used in coal liquefaction reaction under the following reaction conditions:

[0089] The dry powder particles obtained in the Examples and Comparative Examples were used as catalysts for the direct liquefaction of Shendong coal. The addition ratio of Fe (as elemental Fe) to dry coal was 1 wt.%. The direct liquefaction reaction conditions were a reaction temperature of 455°C, a reaction pressure of 19 MPa, and a reaction residence time of 1 hour. The reaction results are shown in Table 3.

[0090] Table 3: Performance evaluation results of the catalysts used in the examples and comparative examples for direct coal liquefaction

Claims

1. A method for resource utilization of coal liquefaction solid slag residue, comprising the following steps: 1) Fully mixing the coal liquefaction solid residue extract with a solvent to prepare a solid-containing slurry, and grinding the solid material in the solid-containing slurry to a material particle size D50 of less than 5 μm; 2) using magnetic separation equipment to magnetically separate the solid-containing slurry obtained in step 1) to obtain the iron catalyst-enriched concentrate A1 and the remaining tailings B2; and 3) The concentrate A1 is washed from the magnetic separation device with a solvent to obtain a slurry containing the concentrate A1, and the slurry containing the concentrate A1 is dried to obtain a dry powder material A2, which is used as a catalyst for the direct coal liquefaction reaction.

2. The method for resource utilization of coal liquefaction solid slag residue according to claim 1, wherein: The particle size D50 of the dry powder material A2 is less than 100 μm, preferably less than 60 μm; and / or, The solid content of the solid-containing slurry in step 1) is 10 wt.% to 40 wt.%, preferably 20 wt.% to 35 wt.%; and / or, Based on 100 wt.% of the total weight of the dry powder material A2, the iron content in the dry powder material A2 is 9 wt.% to 25 wt.%, preferably 11 wt.% to 25 wt.%.

3. The method for resource utilization of coal liquefaction solid slag residue according to claim 1 or 2, wherein: The solvents in step 1) and step 3) are the same or different, and are respectively water or an organic solvent, wherein the organic solvent is selected from one or more of n-hexane, toluene, xylene, carbon disulfide, dichloromethane, carbon tetrachloride, washing oil, pyridine, tetrahydrofuran and quinoline.

4. The method for resource utilization of coal liquefaction solid residue according to any one of claims 1 to 3, wherein: In step 1), the solid material in the solid-containing slurry is ground until the particle size D50 of the solid material is less than 3 μm, preferably less than 2 μm.

5. The method for resource utilization of coal liquefaction solid residue according to any one of claims 1 to 4, wherein: In step 1), grinding is performed by ball milling, rod milling or sand milling. Preferably, grinding is performed using one or more selected from the group consisting of a stirred ball mill, a nano sand mill and a planetary mill.

6. The method for resource utilization of coal liquefaction solid residue according to any one of claims 1 to 5, wherein: The inner lining and grinding media of the grinding device used for grinding are made of non-magnetic materials.

7. The method for resource utilization of coal liquefaction solid residue according to any one of claims 1 to 6, wherein: In step 2), the magnetic separation equipment is a high gradient magnetic separator selected from electromagnetic, permanent magnetic or combined types, preferably a high gradient magnetic separator with an external uniform magnetic field and a superimposed magnetic field of a magnetic concentrating medium.

8. The method for resource utilization of coal liquefaction solid residue according to any one of claims 1 to 7, wherein: In step 2), when an organic solvent is used to prepare the solid-containing slurry, the magnetic field strength acting on the solid-containing slurry is 2000-5000Gs, preferably, the magnetic field strength acting on the solid-containing slurry is 3000-4000Gs; when water is used to prepare the slurry, the magnetic field strength acting on the solid-containing slurry is 5000-13000Gs, preferably, the magnetic field strength acting on the solid-containing slurry is 7000-9000Gs.

9. The method for resource utilization of coal liquefaction solid residue according to any one of claims 1 to 8, wherein: In step 3), the slurry containing the concentrate A1 is dried and the solvent is recovered by vacuum drying, nitrogen drying, distillation or spray drying. Preferably, spray drying is used for drying and / or solvent recovery.

10. The method for resource utilization of coal liquefaction solid residue according to any one of claims 1 to 9, wherein: The method for resource utilization of coal liquefaction solid slag residue further comprises the following steps: 4) using the dry powder material A2 obtained in step 3) as a coal direct liquefaction catalyst for a coal direct liquefaction reaction; Preferably, the added amount is such that the mass ratio of Fe in the dry powder material A2 to the dry coal is 0.5 wt.% to 10 wt.%, preferably 0.5 wt.% to 5 wt.%, and further more preferably 1 wt.% to 3 wt.%; Preferably, the reaction conditions are: The reaction temperature is 400-470°C, preferably 430-465°C; The reaction pressure is 10-20 MPa, preferably 13-20 MPa; The reaction residence time is 0.5 to 2 hours.

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