A beneficiation method and system for coal gasification slag

Abstract

The present application relates to a beneficiation method and system for coal gasification slag, belonging to the technical field of resource recovery and utilization; the method comprises: performing gravity separation on the coal gasification slag to obtain gravity separation tailings and gravity separation concentrate; performing a first-stage concentration on the gravity separation concentrate, followed by a first-stage grinding and a first-stage classification to obtain a first fine-grained material that meets a first set grinding fineness; performing flotation on the fine-grained material that meets the set grinding fineness to obtain a carbon concentrate and a material to be recycled; performing a second-stage concentration on the material to be recycled, followed by a second-stage grinding and a second-stage classification to obtain a second fine-grained material that meets a second set grinding fineness; performing scavenging on the second fine-grained material that meets the second set grinding fineness to obtain scavenging foam and flotation tailings; recycling the scavenging foam to the flotation; improving the carbon recovery rate, effectively improving the comprehensive utilization rate of coal, and reducing the stockpile volume of coal gasification slag, thereby reducing environmental risks.

Description

Technical Field

[0001] The present application relates to the field of resource recycling and utilization, and in particular to a method and system for beneficiating coal gasification slag. Background Art

[0002] The rapid development of coal chemical technology in my country has led to a sharp increase in the emission of coal gasification slag. At present, the annual emission of coal gasification slag in my country has exceeded 100 million tons, and most of this type of coal gasification slag with high carbon content has not been effectively utilized. It is mainly treated by stockpiling, which occupies a large amount of land and also poses great risks to the environment.

[0003] At present, the utilization of coal gasification slag is mainly used in the fields of building materials, sewage treatment, boiler co-firing, etc., followed by sintering ceramics as an adsorbent to treat waste gas and wastewater. The comprehensive utilization rate of coal gasification slag is relatively low. Summary of the Invention

[0004] The present application provides a method and system for beneficiating coal gasification slag to solve the current problem of low comprehensive utilization rate of coal gasification slag.

[0005] In a first aspect, the present application provides a method for beneficiating coal gasification slag.

[0006] Specifically, the method includes:

[0007] Gravity separation is performed on the coal gasification furnace slag to obtain gravity separation tailings and gravity separation concentrate;

[0008] The gravity separation concentrate is subjected to a first concentration step, followed by a first grinding step and a first classification step to obtain a first fine-grained material meeting a first set grinding fineness;

[0009] The fine-grained materials that meet the set grinding fineness are floated to obtain carbon concentrate and materials to be recycled;

[0010] The material to be recycled is subjected to a second-stage concentration, followed by a second-stage grinding and a second-stage classification to obtain a second fine-grained material that meets a second set grinding fineness;

[0011] The second fine-grained material meeting the second set grinding fineness is scavenged to obtain scavenging foam and flotation tailings; and the scavenging foam is recycled to the flotation.

[0012] As an optional embodiment, the first condition for setting the grinding fineness includes that the mass proportion of materials with a particle size of -0.074 mm is 70%-95%.

[0013] As an optional embodiment, the second condition for setting the grinding fineness includes that the mass proportion of materials with a particle size of -0.074 mm is 60%-85%.

[0014] As an optional embodiment, the flotation of the fine-grained material that meets the set grinding fineness to obtain carbon concentrate and the material to be recycled specifically includes:

[0015] The fine-grained materials that meet the set grinding fineness are roughly selected to obtain materials to be cleaned and materials to be recycled;

[0016] The material to be concentrated is concentrated to obtain carbon concentrate.

[0017] As an optional implementation, the selection includes at least one selection.

[0018] As an optional embodiment, the flotation equipment includes a transmission-free flotation cell.

[0019] As an optional embodiment, the re-selection equipment includes at least one of a shaking table, a cyclone and a centrifuge.

[0020] As an optional embodiment, the first stage concentration equipment includes at least one of a vibrating dewatering screen and a sedimentation tank; and / or

[0021] The equipment for the second-stage concentration includes at least one of a vibrating dewatering screen and a sedimentation tank.

[0022] As an optional embodiment, the gravity separation tailings include at least one of quartz, calcite, anhydrite and coarse slag with low carbon content caused by severe coking.

[0023] In a second aspect, the present application provides a coal gasification slag beneficiation system for implementing the steps of the coal gasification slag beneficiation method described in any embodiment of the first aspect.

[0024] Specifically, the system includes:

[0025] Gravity separation unit, used to re-separate coal gasification slag to obtain gravity separation tailings and gravity separation concentrate;

[0026] a first screening unit for performing a first concentration, a first grinding, and a first classification on the gravity-separated concentrate to obtain a first fine-grained material meeting a first set grinding fineness, wherein the first screening unit comprises a first concentration unit, a first grinding unit, and a first classification unit connected in series, and the first concentration unit is connected to the gravity-separation unit to receive the gravity-separated concentrate;

[0027] a flotation unit for flotating fine-grained materials meeting a set grinding fineness to obtain carbon concentrate and materials to be recycled, the flotation unit being connected to the first classification unit for receiving the first fine-grained materials;

[0028] a second screening unit for performing a second-stage concentration on the material to be recycled, followed by a second-stage grinding and a second-stage classification to obtain a second fine-grained material meeting a second set grinding fineness, wherein the second screening unit comprises a second concentration unit, a second grinding unit, and a second classification unit connected in series, and the second concentration unit is connected to the flotation unit to receive the material to be recycled; and

[0029] The scavenging unit is used to scavenge the second fine-grained material that meets the second set grinding fineness to obtain scavenging foam and flotation tailings; the scavenging unit is connected to the second classification unit to receive the second fine-grained material, and the scavenging unit is connected to the flotation unit to reuse the scavenging foam for the flotation.

[0030] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0031] The method provided in the embodiment of the present application adopts a combined process flow of "gravity separation-concentration-flotation-two-stage grinding". According to the characteristics of the coal gasification slag, the gravity separation method is first used to pre-discard the tailings to avoid grinding and flotation of all components, reduce grinding energy consumption, increase the concentration of residual carbon in the flotation process, and reduce the amount of reagents used. Moreover, particles with high residual carbon content have a relatively low relative density and are easy to float on the slurry during the grinding process, resulting in insufficient dissociation of some particles, which is not conducive to the enrichment of fine carbon. By adjusting the grinding process flow and adding two-stage grinding, the selective grinding of the coal gasification slag is enhanced, the carbon recovery rate is improved, the comprehensive utilization rate of coal is effectively improved, and the stockpile of the coal gasification slag can be reduced, reducing environmental risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1 A flowchart of the method provided in an embodiment of the present application;

[0035] Figure 2 A simplified process diagram provided for an embodiment of the present application. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0038] During the invention process, the applicant discovered that the mineralogical composition of coal gasification slag includes glass, carbon residue, and mineral crystals, with the glass and carbon residue being predominant, while the mineral crystals primarily consist of various types of quartz, mullite, anorthite, ferrous sulfide, and gypsum. Coal gasification slag is a solid waste residue produced by the fluidized bed gasification process of coal. The carbon residue content of a coal gasification plant is approximately 20%-40%. Currently, this slag has not been effectively utilized and is mostly disposed of by stacking or landfill. This not only causes environmental problems such as land occupation, dust pollution, and water and soil contamination, but also incurs significant disposal costs.

[0039] According to the applicant's analysis, the physical properties that limit the resource utilization of coal gasification furnace slag mainly include: (1) high moisture content: most of the moisture is mainly present in the highly developed void structure of the slag particles, which makes drying difficult and costly; (2) high residual carbon content: the overall fine slag is higher than the coarse slag. The main reason is that the coarse slag is formed by the molten slag in the furnace flowing down along the furnace wall into the gasification furnace quenching chamber, and is quenched and solidified in the water bath. It has a long residence time, high stability, and more complete reaction. The fine slag is unburned carbon particles and fine mineral particles discharged from the outlet under the entrainment of synthesis gas. It has a shorter residence time in the furnace than the coarse slag and is incompletely reacted; (3) unstable properties: the properties of the slag are related to factors such as the properties of the raw coal, the type and process of the gasification furnace, the operating conditions, the composition and amount of additives, and are also affected by the degree of reaction and residence time. Any change in conditions will cause changes in the composition and structure of the gasification furnace slag, resulting in unstable properties and increasing the difficulty of its utilization. Therefore, the utilization field of coal gasification furnace slag is narrow, the added value is low, and the addition amount is small.

[0040] like Figure 1 As shown, the embodiment of the present application provides a method for beneficiating coal gasification furnace slag, the method comprising:

[0041] S1. The coal gasification slag is re-selected to obtain re-selection tailings and re-selection concentrates. Generally speaking, the re-selection tailings include quartz, calcite, anhydrite and coarse slag with low carbon content caused by severe coking.

[0042] In some embodiments, the reselection equipment includes at least one of a shaker, a cyclone, and a centrifuge.

[0043] According to the characteristics of coal gasification slag, the gravity separation method is first used to pre-discard the tailings. Specifically, the gravity separation method is used to separate out some quartz, calcite, anhydrite and coarse slag with low carbon content caused by severe coking. This part of the material is heavy material and is used as gravity separation tailings, and the remaining light material is used as gravity separation concentrate.

[0044] S2. The gravity concentrate is concentrated, then subjected to a grinding and classification step to obtain a first fine-grained material that meets the first set grinding fineness;

[0045] In some embodiments, the equipment for the first stage concentration includes at least one of a vibrating dewatering screen and a settling tank.

[0046] In some embodiments, the first set grinding fineness condition includes that the mass proportion of the material with a particle size of -0.074 mm is 70%-95%.

[0047] The applicant found that the mineral dissociation degree is better within this grinding fineness range. If the grinding fineness is further increased, it is easy to cause over-grinding, resulting in mineral muddling, affecting the mineral processing indicators and increasing the grinding cost; if the grinding fineness is reduced, the mineral dissociation degree is poor, resulting in poor mineral processing separation and reduced carbon recovery rate.

[0048] Specifically, the light material enters the first grinding mill after being concentrated and dehydrated, and the grinding fineness is -0.074mm, accounting for 70%-95%.

[0049] S3. Flotation of fine-grained materials that meet the set grinding fineness to obtain carbon concentrate and materials to be recycled;

[0050] In some embodiments, the flotation apparatus comprises a driveless flotation cell.

[0051] The flotation operation is carried out using a transmission-free flotation cell, which improves the flotation efficiency compared to the traditional flotation machine operation.

[0052] In some embodiments, flotation is performed on fine-grained materials that meet the set grinding fineness to obtain carbon concentrate and materials to be recycled, specifically including:

[0053] S3.1. Roughly select the fine-grained material that meets the set grinding fineness to obtain the material to be refined and the material to be recycled;

[0054] S3.2. The material to be concentrated is concentrated to obtain carbon concentrate.

[0055] The following is a specific explanation using secondary concentration as an example. The grinding products react with flotation agents and enter the transmissionless flotation tank for flotation operation. The foam from the roughing operation enters the first selection operation, and the foam from the first selection operation enters the second selection operation. The foam from the second selection operation is the final carbon concentrate. The selected underflow is returned to the previous operation in turn for re-selection.

[0056] S4. The material to be reused is concentrated in two stages, and then subjected to two stages of grinding and two stages of classification to obtain a second fine-grained material that meets the second set grinding fineness;

[0057] In some embodiments, the secondary concentration equipment includes at least one of a vibrating dewatering screen and a sedimentation tank.

[0058] In some embodiments, the second setting condition for grinding fineness includes that the mass proportion of materials with a particle size of -0.074 mm is 60%-85%.

[0059] The applicant found that within this grinding fineness range, the minerals to be recycled can be dissociated. If the grinding fineness is ≤60%, the minerals are not fully dissociated; if the grinding fineness is ≥85%, over-grinding is likely to occur, and the grinding cost is increased.

[0060] Specifically, the bottom flow of the roughing operation enters the second-stage grinding mill after concentration and dehydration, and the grinding fineness of -0.074mm accounts for 60%-85%.

[0061] S5. Scavenging the second fine-grained material that meets the second set grinding fineness to obtain scavenging foam and flotation tailings; and recycling the scavenging foam to the flotation.

[0062] Specifically, the secondary grinding products enter the scavenging operation, the scavenging foam returns to the roughing operation for recycling, the scavenging underflow serves as flotation tailings, and the flotation tailings and gravity separation tailings are combined into the final total tailings.

[0063] Particles with high residual carbon content have a relatively low density and are prone to float on the slurry during the grinding process, resulting in insufficient dissociation of some particles, which is not conducive to the enrichment of fine carbon. By adjusting the grinding process, strengthening the selective grinding of coal gasification furnace slag, and adding secondary grinding, the carbon recovery rate can be improved.

[0064] The above grinding scheme can prevent the over-grinding of residual carbon in the slag, which will cause excessive coal slime, increase the dosage of reagents, and affect the flotation index, and can also fully dissociate the residual carbon in the coarse slag particles, making it easier for flotation recovery.

[0065] With the above design, some quartz, calcite, anhydrite and coarse slag with low carbon content caused by severe coking are first separated by gravity separation. Compared with the full-component grinding and flotation process, this can reduce grinding energy consumption, increase the concentration of residual carbon in the flotation process, and reduce the amount of reagents used. The flotation operation is carried out using a transmission-free flotation cell, which improves the flotation efficiency compared with the traditional flotation machine operation. In order to overcome the low dissociation degree of carbon particles caused by coking, the underflow after roughing separation is subjected to secondary grinding to improve the dissociation degree and the recovery rate of residual carbon.

[0066] Based on a general inventive concept, an embodiment of the present application further provides a beneficiation system for coal gasification slag, the system comprising: a gravity separation unit, a first screening unit, a flotation unit, a second screening unit and a scavenging unit.

[0067] Gravity separation unit, used to re-separate coal gasification slag to obtain gravity separation tailings and gravity separation concentrate;

[0068] a first screening unit for performing a first concentration, a first grinding, and a first classification on the gravity-separated concentrate to obtain a first fine-grained material meeting a first set grinding fineness, wherein the first screening unit comprises a first concentration unit, a first grinding unit, and a first classification unit connected in series, and the first concentration unit is connected to the gravity-separation unit to receive the gravity-separated concentrate;

[0069] a flotation unit for flotating fine-grained materials meeting a set grinding fineness to obtain carbon concentrate and materials to be recycled, the flotation unit being connected to the first classification unit for receiving the first fine-grained materials;

[0070] a second screening unit for performing a second-stage concentration on the material to be recycled, followed by a second-stage grinding and a second-stage classification to obtain a second fine-grained material meeting a second set grinding fineness, wherein the second screening unit comprises a second concentration unit, a second grinding unit, and a second classification unit connected in series, and the second concentration unit is connected to the flotation unit to receive the material to be recycled; and

[0071] The scavenging unit is used to scavenge the second fine-grained material that meets the second set grinding fineness to obtain scavenging foam and flotation tailings; the scavenging unit is connected to the second classification unit to receive the second fine-grained material, and the scavenging unit is connected to the flotation unit to reuse the scavenging foam for the flotation.

[0072] The coal gasification slag beneficiation system is implemented based on the above-mentioned coal gasification slag beneficiation method. The specific steps of the coal gasification slag beneficiation method can refer to the above-mentioned embodiment. Since the coal gasification slag beneficiation system adopts part or all of the technical solutions of the above-mentioned embodiment, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here.

[0073] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0074] Example 1

[0075] A method for beneficiating coal gasification slag, comprising:

[0076] The residual carbon content in the coal gasification furnace slag is 27%. The equipment in the gravity separation process uses a shaking table to separate out some quartz, calcite, anhydrite and coarse slag with serious low carbon content from coking. This part of the material is heavy material and is used as gravity separation tailings, and the remaining light material is used as gravity separation concentrate; the light material is concentrated and dehydrated in the sedimentation tank and then undergoes a closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 95%. After the slurry material reacts with the flotation agent, it enters the non-transmission flotation tank for flotation operation. The flotation process adopts one roughing operation, two fine selection operations and one scavenging operation. The foam of the roughing operation reacts with the flotation agent to perform a fine selection operation to obtain The obtained foam from the first selection reacts with the flotation agent to carry out the second selection operation, and the obtained foam from the second selection operation is the final carbon concentrate; the underflow of the first selection operation returns to the roughing operation, and the underflow of the second selection operation returns to the first selection operation; the underflow of the roughing operation is concentrated and dehydrated in the sedimentation tank and then subjected to two-stage closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 85%, which is reacted with the flotation agent for a scavenging operation, and the scavenging foam returns to the roughing operation. The scavenging underflow is the flotation tailings, and the flotation tailings and the shaking table tailings are combined into the final total tailings. The obtained carbon concentrate yield is 31%, and the loss on ignition is 85%.

[0077] Example 2

[0078] A method for beneficiating coal gasification slag, comprising:

[0079] The residual carbon content in the coal gasification furnace slag is 27%. The gravity separation process equipment uses a cyclone to separate out some quartz, calcite, anhydrite and coarse slag with severe low carbon content from coking. This part of the material is heavy material and is used as gravity separation tailings, and the remaining light material is used as gravity separation concentrate; the light material is concentrated and dehydrated by a vibrating dewatering screen and then undergoes a closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 80%. After the slurry reacts with flotation reagents, it enters the non-transmission flotation tank for flotation operation. The flotation process adopts one roughing operation, two concentrating operations, and one scavenging operation. The foam of the roughing operation reacts with the flotation reagents for the concentrating operation. The obtained foam from the first selection reacts with the flotation agent to carry out the second selection operation, and the obtained foam from the second selection operation is the final carbon concentrate; the underflow of the first selection operation returns to the roughing operation, and the underflow of the second selection operation returns to the first selection operation; the underflow of the roughing operation is concentrated and dehydrated by the vibrating dewatering screen and then subjected to two-stage closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 70%, which is reacted with the flotation agent for a scavenging operation, and the scavenging foam returns to the roughing operation. The scavenging underflow is the flotation tailings, and the flotation tailings and the shaking table tailings are combined into the final total tailings. The obtained carbon concentrate yield is 27%, and the loss on ignition is 87%.

[0080] Example 3

[0081] A method for beneficiating coal gasification slag, comprising:

[0082] The residual carbon content in the coal gasification furnace slag is 27%. The gravity separation method uses a centrifuge to separate out some quartz, calcite, anhydrite and coarse slag with serious low carbon content from coking. This part of the material is heavy material and is used as gravity separation tailings, and the remaining light material is used as gravity separation concentrate; the light material is concentrated and dehydrated by a vibrating dewatering screen and then undergoes a closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 70%. After the slurry material reacts with flotation reagents, it enters the non-transmission flotation tank for flotation operation. The flotation process adopts one roughing operation, two fine selection operations, and one scavenging operation. The foam of the roughing operation reacts with the flotation reagents to perform a fine selection operation. The obtained foam from the first selection reacts with the flotation agent to carry out the second selection operation, and the obtained foam from the second selection operation is the final carbon concentrate; the underflow of the first selection operation returns to the roughing operation, and the underflow of the second selection operation returns to the first selection operation; the underflow of the roughing operation is concentrated and dehydrated by the vibrating dewatering screen and then subjected to two-stage closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 60%, which is reacted with the flotation agent for a scavenging operation, and the scavenging foam returns to the roughing operation. The scavenging underflow is the flotation tailings, and the flotation tailings and the shaking table tailings are combined into the final total tailings. The obtained carbon concentrate yield is 24%, and the loss on ignition is 88%.

[0083] Example 4

[0084] A method for beneficiating coal gasification slag, comprising:

[0085] The residual carbon content in the coal gasification furnace slag is 27%. The gravity separation method uses a shaking table to separate out some quartz, calcite, anhydrite and coarse slag with serious low carbon content from coking. This part of the material is heavy material and is used as gravity separation tailings, and the remaining light material is used as gravity separation concentrate; the light material is concentrated and dehydrated by a vibrating dewatering screen and then undergoes a closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 90%. After the slurry material reacts with flotation reagents, it enters the non-transmission flotation tank for flotation operation. The flotation process adopts one roughing operation, two concentrating operations, and one scavenging operation. The foam of the roughing operation reacts with the flotation reagents to perform a concentrating operation to obtain The foam from the first selection reacts with the flotation agent to carry out the second selection operation, and the obtained foam from the second selection operation is the final carbon concentrate; the underflow of the first selection operation returns to the roughing operation, and the underflow of the second selection operation returns to the first selection operation; the underflow of the roughing operation is concentrated and dehydrated by the vibrating dewatering screen and then subjected to two-stage closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 80%, which is reacted with the flotation agent for a scavenging operation, and the scavenging foam returns to the roughing operation. The scavenging underflow is the flotation tailings, and the flotation tailings and the shaking table tailings are combined into the final total tailings. The obtained carbon concentrate yield is 29%, and the loss on ignition is 86%.

[0086] Example 5

[0087] A method for beneficiating coal gasification slag, comprising:

[0088] The residual carbon content in the coal gasification furnace slag is 27%. The gravity separation method uses a centrifuge to separate out some quartz, calcite, anhydrite and coarse slag with serious low carbon content from coking. This part of the material is heavy material and is used as gravity separation tailings, and the remaining light material is used as gravity separation concentrate; the light material is concentrated and dehydrated in the sedimentation tank and then undergoes a closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 85%. After the slurry material reacts with the flotation agent, it enters the non-transmission flotation tank for flotation operation. The flotation process adopts one roughing operation, two concentrating operations, and one scavenging operation. The foam of the roughing operation reacts with the flotation agent to perform a concentrating operation to obtain The foam from the first selection reacts with the flotation agent to carry out the second selection operation, and the obtained foam from the second selection operation is the final carbon concentrate; the underflow of the first selection operation returns to the roughing operation, and the underflow of the second selection operation returns to the first selection operation; the underflow of the roughing operation is concentrated and dehydrated by the vibrating dewatering screen and then subjected to two-stage closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 70%, which is reacted with the flotation agent for a scavenging operation, and the scavenging foam returns to the roughing operation. The scavenging underflow is the flotation tailings, and the flotation tailings and the shaking table tailings are combined into the final total tailings. The obtained carbon concentrate yield is 28%, and the loss on ignition is 87%.

[0089] Comparative Example 1

[0090] A method for beneficiating coal gasification slag, comprising:

[0091] The residual carbon content in the coal gasification furnace slag is 27%. No gravity separation method is used. All materials are subjected to a closed-circuit grinding to obtain a pulp material with a particle size of -0.074mm accounting for 95%. After the pulp material reacts with the flotation reagent, it enters the non-transmission flotation tank for flotation operation. The flotation process adopts one roughing operation, two fine selections, and one scavenging operation. The foam of the roughing operation reacts with the flotation reagent to perform the first fine selection operation. The obtained fine selection foam reacts with the flotation reagent to perform the second fine selection operation. The obtained fine selection foam is the final carbon concentrate. The bottom flow of the first selection operation is returned to the roughing operation, and the bottom flow of the second selection operation is returned to the first selection operation; the bottom flow of the roughing operation is concentrated and dehydrated by the vibrating dewatering screen and then subjected to two-stage closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 60%. The slurry material is reacted with flotation reagents and then subjected to scavenging operation. The scavenging foam is returned to the roughing operation. The scavenging bottom flow is the flotation tailings. The flotation tailings and the shaking table tailings are combined into the final total tailings. The obtained carbon concentrate yield is 16%, and the loss on ignition is 66%.

[0092] Comparative Example 2

[0093] A method for beneficiating coal gasification slag, comprising:

[0094] The residual carbon content in the gasification furnace slag is 27%. Gravity separation is not used. All materials are subjected to a closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 95%. After the slurry material reacts with the flotation agent, it enters the non-transmission flotation tank for flotation operation. The flotation process adopts one roughing operation, two fine selections and one scavenging operation. The foam of the roughing operation reacts with the flotation agent to perform the first fine selection operation. The obtained first fine selection foam reacts with the flotation agent to perform the second fine selection operation. The obtained second fine selection foam is the final carbon concentrate; the underflow of the first fine selection operation returns to the roughing operation, and the underflow of the second fine selection operation returns to the first fine selection operation; the underflow of the roughing operation does not undergo the second-stage grinding, but directly undergoes the scavenging operation. The scavenging foam returns to the roughing operation. The obtained scavenging underflow is the final tailings. The obtained carbon concentrate yield is 10% and the loss on ignition is 53%.

[0095] Comparative Example 3

[0096] A method for beneficiating coal gasification slag, comprising:

[0097] The residual carbon content in the coal gasification furnace slag is 27%. The gravity separation method uses a centrifuge to separate out some quartz, calcite, anhydrite and coarse slag with serious low carbon content from coking. This part of the material is heavy material and is used as gravity separation tailings, and the remaining light material is used as gravity separation concentrate; the light material is concentrated and dehydrated in the sedimentation tank and then undergoes a closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 60%. After the slurry material reacts with the flotation agent, it enters the non-transmission flotation tank for flotation operation. The flotation process adopts one roughing operation, two fine selection operations, and one scavenging operation. The foam of the roughing operation reacts with the flotation agent to perform a fine selection operation to obtain The foam from the first selection reacts with the flotation agent to carry out the second selection operation, and the obtained foam from the second selection operation is the final carbon concentrate; the underflow of the first selection operation returns to the roughing operation, and the underflow of the second selection operation returns to the first selection operation; the underflow of the roughing operation is concentrated and dehydrated by the vibrating dewatering screen and then subjected to two-stage closed-circuit grinding to obtain a slurry material with a particle size of -0.074mm accounting for 50%, which is reacted with the flotation agent for a scavenging operation, and the scavenging foam returns to the roughing operation. The scavenging underflow is the flotation tailings, and the flotation tailings and the shaking table tailings are combined into the final total tailings. The obtained carbon concentrate yield is 17%, and the loss on ignition is 70%.

[0098] The beneficiation results of each embodiment and comparative example are shown in the following table:

[0099] Carbon concentrate yield Loss on ignition Example 1 31％ 85％ Example 2 27％ 87％ Example 3 24％ 88％ Example 4 29％ 86％ Example 5 28％ 87％ Comparative Example 1 16％ 66％ Comparative Example 2 10％ 53％ Comparative Example 3 17％ 70％

[0100] As can be seen from the above table, the method provided in the embodiments of the present application can effectively recover the residual carbon in the coal gasification furnace slag, enrich the carbon in the recovered slag, and effectively improve the comprehensive utilization rate of coal.

[0101] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0102] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0103] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for beneficiating coal gasification slag, characterized in that: The method comprises: The coal gasification slag is subjected to gravity separation to obtain gravity separation tailings and gravity separation concentrate. The residual carbon content in the coal gasification slag is 27%; The gravity separation concentrate is subjected to a first concentration step, followed by a first grinding step and a first classification step to obtain a first fine-grained material meeting a first set grinding fineness; flotation is performed on the first fine-grained material that meets the first set grinding fineness to obtain carbon concentrate and material to be recycled; The material to be recycled is subjected to a second-stage concentration, followed by a second-stage grinding and a second-stage classification to obtain a second fine-grained material that meets a second set grinding fineness; scavenging the second fine-grained material that meets the second set grinding fineness to obtain scavenging foam and flotation tailings; recycling the scavenging foam to the flotation, and combining the flotation tailings and the gravity separation tailings into a final total tailings; The first condition for setting the grinding fineness includes that the mass proportion of the material with a particle size of -0.074 mm is 70%-95%; The second condition for setting the grinding fineness includes that the mass proportion of the material with a particle size of -0.074 mm is 60%-85%; The reselection equipment includes at least one of a shaking table, a cyclone and a centrifuge; The gravity separation tailings include at least one of quartz, calcite, anhydrite and coarse slag with low carbon content caused by severe coking; The flotation process adopts one roughing and two cleaning operations. The foam from the roughing operation enters the cleaning operation one, and the foam from the cleaning operation one enters the cleaning operation two. The foam from the cleaning operation two is the final carbon concentrate. The cleaning bottom flow is returned to the previous operation in turn for re-selection.

2. The method for beneficiating coal gasification slag according to claim 1, characterized in that: The flotation equipment includes a transmission-free flotation cell.

3. The method for beneficiating coal gasification slag according to claim 1, characterized in that: The equipment for the first stage concentration includes at least one of a vibrating dewatering screen and a sedimentation tank; and / or The equipment for the second stage concentration includes at least one of a vibrating dewatering screen and a sedimentation tank.

4. A beneficiation system for the beneficiation method of coal gasification furnace slag according to any one of claims 1 to 3, characterized in that: The system comprises: Gravity separation unit, used to re-separate coal gasification slag to obtain gravity separation tailings and gravity separation concentrate; a first screening unit for performing a first concentration, a first grinding, and a first classification on the gravity-separated concentrate to obtain a first fine-grained material meeting a first set grinding fineness, wherein the first screening unit comprises a first concentration unit, a first grinding unit, and a first classification unit connected in series, and the first concentration unit is connected to the gravity-separation unit to receive the gravity-separated concentrate; a flotation unit for flotating fine-grained materials meeting a set grinding fineness to obtain carbon concentrate and materials to be recycled, the flotation unit being connected to the first classification unit for receiving the first fine-grained materials; a second screening unit for performing a second-stage concentration on the material to be recycled, followed by a second-stage grinding and a second-stage classification to obtain a second fine-grained material meeting a second set grinding fineness, wherein the second screening unit comprises a second concentration unit, a second grinding unit, and a second classification unit connected in series, and the second concentration unit is connected to the flotation unit to receive the material to be recycled; and The scavenging unit is used to scavenge the second fine-grained material that meets the second set grinding fineness to obtain scavenging foam and flotation tailings; the scavenging unit is connected to the second classification unit to receive the second fine-grained material, and the scavenging unit is connected to the flotation unit to reuse the scavenging foam for the flotation.

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