Separation method of bottom-reduced oil residues in direct coal liquefaction

Abstract

The invention provides a separation method of coal direct liquefaction reduced bottom oil residues, which comprises the following steps: (1) crushing the coal direct liquefaction reduced bottom oil residues, mixing the crushed oil residues with water, carrying out rod milling to obtain slurry, and carrying out ball milling treatment on the slurry to obtain superfine slurry; the ratio of solids with the particle size of less than 60 microns in the superfine slurry is more than 95 wt%; (2) adding an auxiliary agent into the superfine slurry, and carrying out flotation treatment to obtain flotation foam and fuel slurry; carrying out filter pressing on the flotation foam to obtain a filter cake containing asphalt, and carrying out filter pressing on the fuel slurry to obtain a filter cake containing fuel; wherein in the flotation treatment process, the diameter of bubbles in the superfine slurry ranges from 0.005 mm to 20 mm; and (3) drying the asphalt-containing filter cake to obtain an asphalt crude product, and carrying out magnetic separation and melting granulation on the asphalt crude product to obtain the asphalt. The coal liquefaction bottom-reduced oil residue separation method is operated at normal temperature, so that the energy consumption of the device is reduced, the coking of a heating furnace tube caused by temperature rise in the extraction separation process is avoided, and the investment of the device is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of producing oil products by direct coal liquefaction, and specifically relates to a method for separating unreacted coal powder, catalyst and inorganic substances from oil residue at the bottom of a vacuum tower of direct coal liquefaction. Background Art

[0002] Coal direct liquefaction is the process of converting coal powder into liquid fuel through high temperature and high pressure hydrocracking reaction under the action of hydrogen and catalyst. After the materials after hydrogenation reaction are separated and fractionated in normal pressure and vacuum towers, the bottom oil residue is obtained at the bottom of the vacuum tower, which accounts for about 30% of the total amount of coal powder as the raw material of the direct coal liquefaction reaction. The bottom oil residue of direct coal liquefaction is a kind of asphalt-like solid by-product with high solid content, which is mainly composed of heavy liquefied oil (n-hexane soluble matter), asphalt-like substances (n-hexane insoluble-tetrahydrofuran soluble matter), unconverted coal powder, catalyst, and inorganic matter; among them, unconverted coal powder, direct liquefaction catalyst, and inorganic matter account for about 47.6% of the total oil residue. This part of the material has a great influence on the quality of the asphalt product. Therefore, the high added value utilization of coal liquefaction oil residue can be achieved only after removing this part of the material. At the same time, the removed unconverted coal powder, catalyst, and inorganic matter have a high calorific value and can be used as fuel.

[0003] Since the reduced oil residue has a high bonding index and a low price, it is generally used as a coking coal additive. The asphalt product obtained after separation, if the solid content is low, can be mixed with petroleum asphalt as reformed asphalt or developed into downstream carbon material products. If the solid content is high, it can be used in waterproof materials. Compared with using it as a coking coal additive, its economic value is greatly improved.

[0004] At present, there is only one company in China that uses coal powder to produce oil products through the coal direct liquefaction process and produces reduced bottom oil residue. For the reduced bottom oil residue, the main method is to separate the unconverted coal powder, direct liquefaction catalyst and inorganic matter in it by extraction. The high-temperature liquid oil residue (above 300°C) of the coal direct liquefaction device is sent to the extraction tank for mixing with the high-temperature solvent; after the mixing, the material is cooled to an operating temperature suitable for centrifugal separation and then sent to a horizontal screw centrifuge for separation. After separation, the clear liquid is sent to a sedimentation tank for sedimentation. After a certain period of time, the light phase is heated in a heating furnace and sent to an atmospheric tower to remove part of the solvent. The material at the bottom of the atmospheric tower is heated again in a heating furnace and sent to a vacuum tower for vacuum distillation to further remove the solvent. The material at the bottom of the tower is granulated to obtain a superior grade asphalt; the heavy phase in the sedimentation tank is heated in a heating furnace and sent to an atmospheric tower to remove part of the solvent. The material at the bottom of the atmospheric tower is heated again in a heating furnace and sent to a vacuum tower for vacuum distillation to further remove the solvent. The material at the bottom of the tower is granulated to obtain a first-grade asphalt; the heavy phase obtained from the horizontal screw centrifuge has too high viscosity, so a solvent is added to dilute the mixture, and then heated in a heating furnace and sent to a granulation tower. The solvent is flashed in the granulation tower to remove the solvent. The solvent is recovered and reused after cooling. The granulation tower bottom obtains a raffinate with a high calorific value of coal powder, catalyst, and inorganic matter, which is used as fuel. The separation is carried out by extraction, and a single set of equipment needs to be heated by multiple heating furnaces, resulting in high comprehensive energy consumption; the process flow is long, the number of centrifugal equipment is large, and the reliability is poor; the bottom oil residue has high viscosity and high carbon content, the furnace tube is seriously coked, and the device stability is poor.

[0005] At present, the unconverted coal powder, catalyst and inorganic matter in the bottom oil residue are separated and treated by filtering. The bottom oil residue has high viscosity and high operating temperature, and the solid content accounts for 47.6%. The filtering method requires a large filtering area, a high pressure difference before and after, and a short filtering cycle, which is not suitable for large-scale production. Summary of the invention

[0006] In view of the problems existing in the separation of coal liquefaction bottom oil residue, the method of the present invention provides a new separation method of coal liquefaction bottom oil residue, which is to strip the unconverted coal powder, catalyst, inorganic matter and asphalt substances in the bottom oil residue by crushing, rod milling and ball milling, and separate them by flotation and other methods. The main process of the method of the present invention is operated at room temperature, which reduces the energy consumption of the device, avoids the coking of the heating furnace tube caused by the temperature rise during the extraction and separation process, and reduces the investment of the device.

[0007] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for separating bottom oil residue from direct coal liquefaction, comprising the following steps:

[0009] (1) crushing the bottom oil residue of coal direct liquefaction, mixing the crushed oil residue with water, and rod-milling to obtain slurry, and then ball-milling the slurry to obtain ultrafine slurry;

[0010] The proportion of solid particles with a particle size of less than 60 μm in the ultrafine slurry is more than 95 wt %. Preferably, the solid content of the ultrafine slurry is 5 to 50 wt %;

[0011] (2) adding an auxiliary agent to the ultrafine slurry for flotation treatment to obtain flotation foam and fuel slurry; the flotation foam is subjected to filter pressing to obtain a filter cake containing asphalt, and the fuel slurry is subjected to filter pressing to obtain a filter cake containing fuel;

[0012] Wherein, the diameter of bubbles generated in the ultrafine slurry during the flotation treatment is 0.005 to 20 mm, preferably 1 to 10 mm;

[0013] (3) The asphalt-containing filter cake is dried to obtain a crude asphalt product, and the crude asphalt product is further subjected to magnetic separation and melt granulation to obtain asphalt.

[0014] In a specific embodiment of the separation method provided by the present invention, the coal direct liquefaction minus bottom oil residue comes from the liquefaction residue produced in the process of direct liquefaction of coal powder by hydrogenation to prepare oil products, and the coal direct liquefaction minus bottom oil residue contains asphalt materials, unconverted coal powder, direct liquefaction catalyst and inorganic matter.

[0015] In some embodiments, the bottom oil residue from direct coal liquefaction is crushed to an average particle size of 1 to 100 mm, preferably an average particle size of 5 to 10 mm.

[0016] In some specific embodiments, the proportion of solid particles with a size of less than 200 μm in the slurry is more than 95 wt%, and the solid content is 5-50 wt%; preferably, the proportion of solid particles with a size of less than 120 μm in the slurry is more than 95 wt%.

[0017] In some embodiments, the proportion of solid particles with a particle size of 10 to 35 μm in the ultrafine slurry is greater than 95 wt %, and the solid content of the ultrafine slurry is 5 to 35 wt %.

[0018] In some embodiments, in step (2), a collector and a frother are added to the ultrafine slurry as the auxiliary agents for flotation treatment;

[0019] Preferably, the addition amount of the collector is 20-1500 g / t coal direct liquefaction reduced bottom oil residue, and the addition amount of the foaming agent is 20-2000 g / t coal direct liquefaction reduced bottom oil residue;

[0020] More preferably, the added amount of the collector is 20-200 g / t coal direct liquefaction reduced bottom oil residue, and the added amount of the foaming agent is 40-1000 g / t coal direct liquefaction reduced bottom oil residue.

[0021] In some embodiments, the solid content of the flotation foam is 20-40 wt %, and the solid content of the fuel slurry is 5-30 wt %.

[0022] In some embodiments, the flotation foam is filter-pressed and dehydrated at 1-2 MPaG to obtain a filter cake containing asphalt with a solid content of 60-75 wt%; preferably, the fuel slurry is filter-pressed and dehydrated at 1-2 MPaG to obtain a filter cake containing fuel with a solid content of 60-75 wt%.

[0023] In some embodiments, the asphalt-containing filter cake is dried with hot air until the moisture content is 2 to 15 wt % to obtain the crude asphalt product;

[0024] The hot air drying temperature is preferably 100 to 125°C, more preferably 110 to 125°C.

[0025] In some embodiments, after the magnetic material is removed from the crude asphalt by magnetic separation, the crude asphalt is melt-granulated at 200-350° C. to obtain asphalt.

[0026] The technical solution provided by the present invention has the following beneficial effects:

[0027] The method for separating bottom oil residue from direct coal liquefaction provided by the present invention adopts a physical method to separate asphalt and unconverted coal powder, catalyst and inorganic matter in the bottom oil residue from direct coal liquefaction. The separation method is simple, avoids the use of extraction agent, reduces the loss and energy consumption of extraction agent recovery; also avoids the use of heating furnace, and reduces the comprehensive energy consumption of the separation process.

[0028] The separation method of the invention avoids the use of centrifugal separation equipment and high-temperature filtering equipment, is not affected by scale enlargement, and has high equipment reliability. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0031] The present invention provides a method for separating bottom oil residue from direct coal liquefaction, comprising:

[0032] (1) crushing the bottom oil residue of coal direct liquefaction, mixing the crushed oil residue with water, and rod-milling to obtain slurry, and then ball-milling the slurry to obtain ultrafine slurry;

[0033] The proportion of solid particles with a particle size of less than 60 μm in the ultrafine slurry is more than 95 wt %. Preferably, the solid content of the ultrafine slurry is 5 to 50 wt %;

[0034] (2) adding an auxiliary agent to the ultrafine slurry for flotation treatment to obtain flotation foam and fuel slurry; the flotation foam is subjected to filter pressing to obtain a filter cake containing asphalt, and the fuel slurry is subjected to filter pressing to obtain a filter cake containing fuel;

[0035] Wherein, the diameter of bubbles generated in the ultrafine slurry during the flotation treatment is 0.005 to 20 mm, preferably 1 to 10 mm;

[0036] (3) The asphalt-containing filter cake is dried to obtain a crude asphalt product, and the crude asphalt product is further subjected to magnetic separation and melt granulation to obtain asphalt.

[0037] The separation method provided by the present invention uses physical separation to separate the residue in the bottom oil residue of coal direct liquefaction at room temperature, avoids the separation method of using an extractant for extraction, reduces the loss and energy consumption of the extractant recovery; avoids the use of a heating furnace, and reduces the comprehensive energy consumption of separation.

[0038] The coal direct liquefaction reduced bottom oil residue mentioned in the present invention comes from the liquefied residue produced in the process of preparing oil products by direct liquefaction of coal powder by hydrogenation, and includes asphalt materials, unconverted coal powder, direct liquefaction catalyst, inorganic substances and the like.

[0039] In some specific embodiments, the flaky coal direct liquefaction residue is crushed by a crusher, and the average particle size after crushing is 1 to 100 mm, for example, the average particle size is 20 mm, 30 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm; the preferred average particle size is 5 to 10 mm, for example, 6 mm, 8 mm.

[0040] In some embodiments, the crushed coal is directly liquefied, the bottom oil residue and water are sent to a rod mill for mixing and slurrying, and the proportion of solid particles with a size of less than 200 μm in the prepared slurry is more than 95wt%, for example, 96wt%, 98wt%; in some preferred embodiments, the proportion of solid particles with a size of less than 120 μm in the slurry is more than 95wt%, for example, 96wt%, 98wt%.

[0041] In some preferred embodiments, the rod-milled material is transported to a ball mill for ultrafine grinding and then slurried to obtain an ultrafine slurry, in which the solid matter with a particle size of 10 to 35 μm accounts for more than 95 wt %, and the solid content of the ultrafine slurry is 5 to 35 wt %.

[0042] In some embodiments, the ultrafine slurry obtained in the ball mill is mixed with a certain amount of collector and frother and sent to a flotation machine for flotation, wherein the collector is used in an amount of 20 to 1500 g / t of coal liquefaction oil residue, for example, 500 g of collector is used per ton of coal liquefaction oil residue, and 800 g of collector is used per ton of coal liquefaction oil residue; the frother is used in an amount of 20 to 2000 g / t of coal liquefaction oil residue, for example, 500 g of frother is used per ton of coal liquefaction oil residue, and 1000 g of frother is used per ton of coal liquefaction oil residue. Preferably, the collector is used in an amount of 20 to 200 g per ton of coal liquefaction oil residue, and the frother is used in an amount of 400 to 1000 g per ton of coal liquefaction oil residue.

[0043] In some embodiments, in step (1), an additive is added to the ultrafine slurry, and flotation is performed on a flotation machine, and froth is scraped from the upper surface of the flotation machine to obtain flotation foam and fuel slurry below the flotation foam; in some specific embodiments, the solid content of the flotation foam is 20-40wt%, such as 30wt%, 35wt%; the solid content of the fuel slurry is 5-30wt%, such as 10wt%, 15wt%. The flotation foam is collected and filtered to obtain a filter cake containing asphalt, and the fuel slurry is filtered to obtain a filter cake containing fuel.

[0044] In some specific embodiments, the flotation foam is filter pressed and dehydrated at 1-2 MPaG to obtain a filter cake containing asphalt with a solid content of 60-75 wt%; preferably, the fuel slurry is filter pressed and dehydrated at 1-2 MPaG to obtain a filter cake containing fuel with a solid content of 60-75 wt%.

[0045] In some specific embodiments, the flotation treatment of the separation method of the present invention is carried out in a flotation machine, and bubbles are blown into the ultrafine slurry by setting the aeration coefficient of the flotation machine to 20-60%, preferably 25-35%, to perform flotation treatment on the liquid therein.

[0046] In an embodiment of the separation method of the present invention, the asphalt-containing filter cake is hot-air dried to a moisture content of 2 to 15 wt% to obtain a crude asphalt product; the hot-air drying temperature is preferably 100 to 125°C, for example, 105°C, 115°C, 120°C; more preferably 110 to 125°C.

[0047] Specifically, after the magnetic matter is removed from the crude asphalt by magnetic separation, it is melted at 200-350°C and then cooled and granulated in a steel belt granulator to obtain asphalt.

[0048] The present invention is further described below by means of specific examples, but it should not be understood that the present invention is limited thereto.

[0049] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents used without specifying the manufacturer are all conventional reagents available in the art.

[0050] The bubble diameter of the slurry in the embodiment is measured by the following method: a high-speed camera is used to take a picture of the bubble at 4000 frames / second, and the bubble diameter is obtained by analysis using Proanalsy software;

[0051] Example 1

[0052] The coal direct liquefaction bottom oil residue used in this embodiment is selected from the liquefaction residue produced in the process of direct liquefaction of coal powder by hydrogenation to prepare oil products, including asphalt materials, unconverted coal powder, direct liquefaction catalyst, inorganic substances, etc.

[0053] Separation was performed as follows:

[0054] (1) conveying the flaky coal liquefaction residue to a crusher for crushing to an average particle size of 10 mm, and feeding the crushed material and water into a rod mill for slurrying, wherein the proportion of solid matter with a particle size of less than 100 μm in the slurry out of the rod mill is more than 95 wt %, and the solid content is 25 wt %;

[0055] The slurry from the rod mill enters the ball mill for further grinding to obtain ultrafine slurry, in which the particle size of solid materials in the ultrafine slurry is 10-35 μm, accounting for 95wt%, and the solid content is 25wt%.

[0056] (2) adding a prepared collector suspension to the ultrafine slurry at a ratio of 50 g / t of coal direct liquefaction minus bottom oil residue, and adding a frother to the ultrafine slurry at a ratio of 500 g / t of coal direct liquefaction minus bottom oil residue, mixing them and performing flotation treatment in a flotation machine, wherein the diameter of bubbles in the ultrafine slurry during the flotation treatment is 1 to 8 mm, and the aeration coefficient is 33%;

[0057] Scrape out to obtain flotation foam with a solid content of 37.2% and fuel slurry with a solid content of 21.4%; collect the upper flotation foam and send it to a plate and frame filter, filter under 1.5MPaG to obtain a filter cake containing asphalt with a solid content of 70wt%; the lower fuel slurry is filter-filtered under 1.5MPaG to obtain a filter cake containing fuel with a solid content of 70wt%.

[0058] The asphalt-containing filter cake was hot-air dried at 110°C to obtain asphalt with a moisture content of 5%. After further magnetic separation, it was sent to a melting kettle at a melting temperature of 300°C to obtain asphalt with a purity of 91% and an asphalt yield of 85%.

[0059] Example 2

[0060] The coal direct liquefaction bottom oil residue used in this embodiment is selected from the liquefied residue generated in the process of direct liquefaction of coal powder by hydrogenation to prepare oil products, including asphalt materials, unconverted coal powder, direct liquefaction catalyst, inorganic substances, etc.

[0061] Separation was performed as follows:

[0062] (1) conveying the flaky coal liquefaction residue to a crusher for crushing until the average particle size is 10 mm, and the crushed material and water are sent to a rod mill for slurrying, wherein the proportion of solid matter with a particle size of less than 100 μm in the slurry out of the rod mill is more than 95 wt %, and the solid content is 25 wt %;

[0063] The slurry from the rod mill enters the ball mill for further grinding. The particle size of solid materials in the ultrafine slurry is 10-35 μm, accounting for 95wt%, and the solid content is 25wt%.

[0064] (2) adding a prepared collector suspension to the ultrafine slurry at a ratio of 50 g / t of coal direct liquefaction minus bottom oil residue, and adding a frother to the ultrafine slurry at a ratio of 800 g / t of coal direct liquefaction minus bottom oil residue, mixing them and flotation treatment in a flotation machine, wherein the diameter of bubbles generated by the flotation treatment is 1 to 5 mm, and the inflation coefficient is 33%;

[0065] Scrape out to obtain flotation foam with a solid content of 39% and fuel slurry with a solid content of 20.9%; collect the upper flotation foam and send it to a plate and frame filter, filter under 1.5MPaG to obtain a filter cake containing asphalt with a solid content of 70wt%; the lower fuel slurry is filtered under 1.5MPaG to obtain a filter cake containing fuel with a solid content of 70wt%.

[0066] The asphalt-containing filter cake was hot-air dried at 110°C to obtain asphalt with a moisture content of 5%. After further magnetic separation, it was sent to a melting kettle at a melting temperature of 300°C to obtain asphalt with a purity of 93% and an asphalt yield of 89%.

[0067] Example 3

[0068] The coal direct liquefaction bottom oil residue used in this embodiment is selected from the liquefied residue generated in the process of direct liquefaction of coal powder by hydrogenation to prepare oil products, including asphalt materials, unconverted coal powder, direct liquefaction catalyst, inorganic substances, etc.

[0069] Separation was performed as follows:

[0070] (1) conveying the flaky coal liquefaction residue to a crusher for crushing until the average particle size is 10 mm, and the crushed material and water are sent to a rod mill for slurrying, wherein the proportion of solid matter with a particle size of less than 100 μm in the slurry out of the rod mill is more than 95 wt %, and the solid content is 25 wt %;

[0071] The slurry from the rod mill enters the ball mill for further grinding. The particle size of the solid material in the ultrafine slurry is 10-42 μm, accounting for 95wt%, and the solid content is 25wt%.

[0072] (2) adding a prepared collector suspension to the ultrafine slurry at a ratio of 50 g / t of coal direct liquefaction minus bottom oil residue, and adding a frother to the ultrafine slurry at a ratio of 500 g / t of coal direct liquefaction minus bottom oil residue, mixing them and flotation treatment in a flotation machine, wherein the diameter of bubbles generated by the flotation treatment is 1 to 10 mm, and the inflation coefficient is 33%;

[0073] Scrape out to obtain flotation foam with a solid content of 33% and fuel slurry with a solid content of 23%; collect the upper flotation foam and send it to a plate and frame filter, filter under 1.5MPaG to obtain a filter cake containing asphalt with a solid content of 71wt%; the lower fuel slurry is filtered under 1.5MPaG to obtain a filter cake containing fuel with a solid content of 71wt%.

[0074] The asphalt-containing filter cake was hot-air dried at 110°C to obtain asphalt with a moisture content of 5%. After further magnetic separation, it was sent to a melting kettle at a melting temperature of 300°C to obtain asphalt with a purity of 87% and an asphalt yield of 82%.

[0075] Example 4

[0076] The coal direct liquefaction bottom oil residue used in this embodiment is selected from the liquefied residue generated in the process of direct liquefaction of coal powder by hydrogenation to prepare oil products, including asphalt materials, unconverted coal powder, direct liquefaction catalyst, inorganic substances, etc.

[0077] Separation was performed as follows:

[0078] (1) conveying the flaky coal liquefaction residue to a crusher for crushing until the average particle size is 10 mm, and the crushed material and water are sent to a rod mill for slurrying, wherein the proportion of solid matter with a particle size of less than 100 μm in the slurry out of the rod mill is more than 95 wt %, and the solid content is 25 wt %;

[0079] The slurry from the rod mill enters the ball mill for further grinding. The particle size of the solid material in the ultrafine slurry is 10-35 μm, accounting for 95wt%, and the solid content is 25wt%.

[0080] (2) adding a prepared collector suspension to the ultrafine slurry at a ratio of 50 g / t of coal direct liquefaction minus bottom oil residue, and adding a frother to the ultrafine slurry at a ratio of 500 g / t of coal direct liquefaction minus bottom oil residue, mixing them and flotation treatment in a flotation machine, wherein the diameter of bubbles generated by the flotation treatment is 1 to 7 mm, and the inflation coefficient is 29%;

[0081] Scrape out to obtain flotation foam with a solid content of 38% and fuel slurry with a solid content of 21.2%; collect the upper flotation foam and send it to a plate and frame filter, filter under 1.5MPaG to obtain a filter cake containing asphalt with a solid content of 70wt%; the lower fuel slurry is filtered under 1.5MPaG to obtain a filter cake containing fuel with a solid content of 70wt%.

[0082] The asphalt-containing filter cake was hot-air dried at 110°C to obtain asphalt with a moisture content of 5%. After further magnetic separation, it was sent to a melting kettle at a melting temperature of 300°C to obtain asphalt with a purity of 92% and an asphalt yield of 86%.

[0083] Comparative Example 1

[0084] The coal direct liquefaction reduced bottom oil residue used in this comparative example is selected from the liquefied residue produced in the process of direct liquefaction of coal powder by hydrogenation to prepare oil products, including asphalt materials, unconverted coal powder, direct liquefaction catalyst, inorganic substances, etc.

[0085] Separation was performed as follows:

[0086] (1) The flaky coal liquefaction residue is conveyed to a crusher for crushing to an average particle size of 10 mm. The crushed material and water are sent to a rod mill for pulping. The proportion of solid particles with a particle size of less than 100 μm in the slurry from the rod mill is more than 95 wt %, and the solid content is 25 wt %.

[0087] (2) adding a prepared collector suspension to the ultrafine slurry at a ratio of 50 g / t of coal direct liquefaction minus bottom oil residue, and adding a frother to the ultrafine slurry at a ratio of 500 g / t of coal direct liquefaction minus bottom oil residue, mixing them and flotation treatment in a flotation machine, wherein the diameter of bubbles generated by the flotation treatment is 1 to 8 mm, and the inflation coefficient is 33%;

[0088] Scrape out to obtain flotation foam with a solid content of 28% and fuel slurry with a solid content of 26%; collect the upper flotation foam and send it to a plate and frame filter, filter under 1.5MPaG to obtain a filter cake containing asphalt with a solid content of 70wt%; the lower fuel slurry is filtered under 1.5MPaG to obtain a filter cake containing fuel with a solid content of 70wt%.

[0089] The asphalt-containing filter cake was hot-air dried at 110°C to obtain asphalt with a moisture content of 5%. After further magnetic separation, it was sent to a melting kettle at a melting temperature of 300°C to obtain asphalt with a purity of 70%, and the asphalt yield was 65%.

[0090] Comparative Example 2

[0091] The coal direct liquefaction reduced bottom oil residue used in this comparative example is selected from the liquefied residue produced in the process of direct liquefaction of coal powder by hydrogenation to prepare oil products, including asphalt materials, unconverted coal powder, direct liquefaction catalyst, inorganic substances, etc.

[0092] Separation was performed as follows:

[0093] (1) conveying the flaky coal liquefaction residue to a crusher for crushing until the average particle size is 10 mm, and the crushed material and water are sent to a rod mill for slurrying, wherein the proportion of solid matter with a particle size of less than 100 μm in the slurry out of the rod mill is more than 95 wt %, and the solid content is 25 wt %;

[0094] The slurry from the rod mill enters the ball mill for further grinding. The particle size of solid materials in the ultrafine slurry is less than 35 μm, accounting for 95wt%, and the solid content is 25wt%.

[0095] (2) adding the prepared collector suspension to the ultrafine slurry at a ratio of 50 g / t coal direct liquefaction minus bottom oil residue, mixing the mixture and flotation treatment in a flotation machine, wherein the diameter of bubbles generated by the flotation treatment is 1 to 40 mm, and the aeration coefficient is 33%;

[0096] Scrape out to obtain flotation foam with a solid content of 27% and fuel slurry with a solid content of 26.9%; collect the upper flotation foam and send it to a plate and frame filter, filter under 1.5MPaG to obtain a filter cake containing asphalt with a solid content of 70wt%; the lower fuel slurry is filtered under 1.5MPaG to obtain a filter cake containing fuel with a solid content of 70wt%.

[0097] The asphalt-containing filter cake was hot-air dried at 110°C to obtain asphalt with a moisture content of 5%. After further magnetic separation, it was sent to a melting kettle at a melting temperature of 300°C to obtain asphalt with a purity of 70%, and the asphalt yield was 56%.

Claims

1. A method for separating bottom oil residue from direct coal liquefaction, characterized in that: The following steps are involved: (1) crushing the bottom oil residue of coal direct liquefaction, mixing the crushed oil residue with water, and rod-milling to obtain slurry, and then ball-milling the slurry to obtain ultrafine slurry; The proportion of solid particles with a particle size of less than 60 μm in the ultrafine slurry is more than 95 wt %. Preferably, the solid content of the ultrafine slurry is 5 to 50 wt %; (2) adding an auxiliary agent to the ultrafine slurry for flotation treatment to obtain flotation foam and fuel slurry; the flotation foam is subjected to filter pressing to obtain a filter cake containing asphalt, and the fuel slurry is subjected to filter pressing to obtain a filter cake containing fuel; Wherein, the diameter of bubbles in the ultrafine slurry during the flotation treatment is 0.005 to 20 mm, preferably 1 to 10 mm; (3) The asphalt-containing filter cake is dried to obtain a crude asphalt product, and the crude asphalt product is further subjected to magnetic separation and melt granulation to obtain asphalt.

2. The separation method according to claim 1, characterized in that The coal direct liquefaction reduced bottom oil residue is derived from the liquefaction residue produced in the process of preparing oil products by direct liquefaction of coal powder by hydrogenation. The coal direct liquefaction reduced bottom oil residue contains asphalt materials, unconverted coal powder, direct liquefaction catalyst and inorganic substances.

3. The separation method according to claim 2, characterized in that In step (1), the coal direct liquefaction bottom oil residue is crushed to an average particle size of 1 to 100 mm, preferably 5 to 10 mm.

4. The separation method according to any one of claims 1 to 3, characterized in that The proportion of solid particles with a particle size of less than 200 μm in the slurry is more than 95 wt %, and the solid content is 5 to 50 wt %; Preferably, the proportion of solid matter with a particle size of less than 120 μm in the slurry is more than 95 wt %.

5. The separation method according to claim 4, characterized in that The solid particles in the ultrafine slurry with a particle size of 10 to 35 μm account for more than 95 wt %, and the solid content of the ultrafine slurry is 5 to 35 wt %.

6. The separation method according to any one of claims 1 to 5, characterized in that In step (2), a collector and a frother are added to the ultrafine slurry as the auxiliary agents for flotation treatment; Preferably, the addition amount of the collector is 20-1500 g / t coal direct liquefaction reduced bottom oil residue, and the addition amount of the foaming agent is 20-2000 g / t coal direct liquefaction reduced bottom oil residue; More preferably, the added amount of the collector is 20-200 g / t coal direct liquefaction reduced bottom oil residue, and the added amount of the foaming agent is 40-1000 g / t coal direct liquefaction reduced bottom oil residue.

7. The separation method according to claim 6, characterized in that The solid content of the flotation foam is 20-40wt%, and the solid content of the fuel slurry is 5-30%.

8. The separation method according to claim 7, characterized in that The flotation foam is subjected to filter pressing and dehydration at 1-2 MPaG to obtain a filter cake containing asphalt with a solid content of 60-75 wt%; Preferably, the fuel slurry is dehydrated by filter pressing at 1-2 MPaG to obtain a fuel-containing filter cake with a solid content of 60-75 wt%.

9. The separation method according to claim 8, characterized in that The asphalt-containing filter cake is subjected to hot air drying to obtain the asphalt crude product after the moisture content is 2 to 15 wt %; The hot air drying temperature is preferably 100 to 125°C, more preferably 110 to 125°C.

10. The separation method according to claim 9, characterized in that The crude asphalt is subjected to magnetic separation to remove magnetic substances, and then melt-granulated at 200-350° C. to obtain asphalt.