A multi-stage grinding and multi-stage flotation depth separation process and system for coking coal

Abstract

The present invention belongs to the technical field of coal processing, and relates to a multi-stage grinding and multi-stage flotation depth sorting process and system for coking medium coal, comprising the following steps: after the coking medium coal is crushed and processed, water is added to blend into ore pulp, and then input into a first-stage flotation device, the first-stage flotation device outputs clean coal products and tailings, the tailings of the first-stage flotation device enter the second-stage flotation device, and the second-stage flotation device outputs high-ash clean coal products and high-ash tailings; the high-ash clean coal product enters the second-stage fine grinding and dissociation section, and then water is added to blend into new ore pulp, and then through the roughing-cleaning-scavenging combined flotation process, the qualified clean coal product obtained is obtained together with the qualified clean coal product obtained by the first-stage flotation device through clean coal filter press to obtain the clean coal product; the scavenging concentrate is returned to the second-stage flotation device; the scavenging tailings and the high-ash tailings are combined and dehydrated to form the final flotation tailings. The present invention has simple process, mature technology, low investment, low operating cost, and significant economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of coal processing, and relates to a multi-stage grinding and multi-stage flotation depth separation process and system for coking coal. Background Art

[0002] At present, the medium coal products produced in the coking coal sorting process are basically sold as thermal coal products due to the lack of an effective dissociation and separation process, which is a huge waste of scarce coking coal resources. Although there are also related studies and patents that have announced the process of reselecting medium coal from coking coal to improve the recovery rate of coking coal clean coal, such as a method for sorting chemical coal from medium coal (invention patent CN201910036120.X) and a process for reselecting medium coal (invention patent CN201410613862.1), it is not difficult to find that most of the technologies disclosed in these patents are limited to recovering the clean coal lost in the coking medium coal during the sorting process, or are limited to recovering a part of the released clean coal under the condition of coarse dissociation particle size, and it is difficult to achieve the maximum recovery of the clean coal components contained in the coking medium coal. The patent of a coking coal medium coal multi-stage dissociation-column joint reselection process (application number 201910104428.3) discloses a method of dissociating medium coal with fine embedded particle size through a multi-stage grinding-classification circuit, and using graded flotation to effectively improve the recovery rate of coarse particles and the selectivity of fine particles, ensure the recovery rate of clean coal and the ash content of clean coal, and recover the clean coal in the coking coal medium coal to the greatest extent. However, the process uses a multi-stage screening circuit to control the grinding particle size and classification particle size, and the grinding dissociation and classification process are complicated, which invisibly increases the grinding cost and capital construction costs. Patent announcement number CN106669960A is a process for the separation and reselection of coking fine-grained coal. Taking into account the high content of clay minerals and intergrowths in the washed fine-grained coal, a pre-tailing-fast coal grinding separation process is adopted to reduce the clay mineral content after grinding. However, the flotation column is completely used in the separation stage, and the separation efficiency of the equipment is not considered. The recovery rate of low-ash coarse particles is low, which reduces the recovery rate of clean coal, and the process needs to be further optimized. Therefore, the development of deep coking and fat coal separation technology, through process innovation, to achieve effective separation and efficient separation of coking and fat coal, and to maximize the recovery of scarce coking and fat coal is the key to improving resource utilization and economic benefits of coal enterprises. Summary of the invention

[0003] The present invention overcomes the shortcomings of the prior art and provides a multi-stage grinding and multi-stage flotation deep sorting process and system for coking medium coal with simple process, high sorting accuracy and efficiency, so as to solve the technical problems of low sorting efficiency and low clean coal recovery rate in the existing medium coal re-selection system with scarce coking and fertilizer coal resources, and fundamentally improve the technical and economic efficiency of coking medium coal re-selection.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a multi-stage grinding and multi-stage flotation depth separation process for coking coal, comprising the following steps:

[0005] S1, crushing and processing the coking coal, adding water and mixing it into ore slurry;

[0006] S2, inputting the slurry into a first-stage flotation device, the first-stage flotation device outputs clean coal products and tailings, the tailings from the first-stage flotation device enters a second-stage flotation device, and the second-stage flotation device outputs high-ash clean coal products and high-ash tailings;

[0007] S3. The high-ash clean coal product enters the second-stage fine grinding and dissociation section, and then is mixed with water to form a new ore pulp and then passed through a roughing-cleaning-scavenging combined flotation process. The qualified clean coal product obtained is filtered together with the qualified clean coal product obtained from the first-stage flotation equipment; the scavenging concentrate returns to the second-stage flotation equipment, and after flotation concentration and tailings discarding, it enters the second-stage fine grinding and dissociation section together with the high-ash clean coal for re-grinding; the scavenging tailings are combined with the high-ash tailings output by the second-stage flotation equipment, concentrated by the concentrator, and dehydrated by the tailings filter press to obtain the final flotation tailings.

[0008] In step S2, if the clean coal product of the first stage flotation device does not meet the requirements of qualified clean coal products, the clean coal product of the first stage flotation device and the clean coal product of the second stage flotation device are combined and then enter the second stage fine grinding and dissociation section.

[0009] In the step S1, when the coking coal is coke-fertilizer coal, it is fed into a hammer crusher and a coarse grinding device in sequence to grind the particle size to less than 0.25 mm, or P 0.074 When the concentration is greater than 50%, water is added to adjust the slurry to a concentration of 100-200 g / L; wherein, P 0.074 Indicates the proportion of product particles with a particle size less than 0.074mm;

[0010] When the coking coal is low-ash flotation tailings slime of coke and fertilizer coal, it is fed into a hammer crusher and a high shear mixing equipment in sequence, and then dispersed and blended with water to a slurry concentration of 100-200 g / L.

[0011] The first stage coarse grinding equipment is a ball mill or a rod mill, and the equipment used in the second stage fine grinding and dissociation section is an ultrafine mill with a classification function.

[0012] In the second fine grinding and dissociation section of step S3, the grinding particle size is controlled to be less than 400 mesh, or P 0.045 Greater than 90%, then add water to make a new slurry with a concentration of 30-80 g / L, P 0.045 Indicates the proportion of product particles with a particle size less than 0.045mm.

[0013] The equipment used in the roughing-cleaning-scavenging combined flotation process is a microbubble flotation machine, wherein one microbubble flotation machine is used for roughing, cleaning and scavenging respectively.

[0014] The first stage flotation equipment and the second stage flotation equipment are mechanical stirring flotation machines with stepped sorting tanks.

[0015] In addition, the present invention also provides a multi-stage grinding and multi-stage flotation depth sorting system for coking coal, including: a crushing device, a first-stage flotation device, a second-stage flotation device, a second-stage grinding device, a roughing-cleaning-scavenging combined device, a clean coal filter press device, a concentrator, and a tail coal filter press device. The coking coal enters the feed inlet of the first-stage flotation device after being crushed and blended into a slurry. The tail coal outlet of the first-stage flotation device is connected to the feed inlet of the second-stage flotation device, the clean coal outlet of the second-stage flotation device is connected to the feed inlet of the second-stage grinding device, and the discharge port of the second-stage grinding device is connected to the feed port of the second-stage grinding device. The feed inlet of the roughing-cleaning-scavenging combination equipment is connected, the clean coal outlet of the roughing-cleaning-scavenging combination equipment and the clean coal outlet of the first-stage flotation equipment are connected to the clean coal filter press equipment, and the flotation clean coal is output through the clean coal filter press equipment; the tail coal outlet of the roughing-cleaning-scavenging combination equipment and the tail coal outlet of the second-stage flotation equipment are both connected to the tail coal filter press equipment through the concentrator, and the flotation tail coal is output through the tail coal filter press equipment, and the scavenging concentrate outlet of the roughing-cleaning-scavenging combination equipment is connected to the feed inlet of the second-stage flotation equipment.

[0016] When the coking medium coal is coking fertilizer coal medium coal, the crushing equipment includes a hammer crusher and a first-stage grinding equipment; when the coking medium coal is coking fertilizer coal low-ash flotation tailing slime, the crushing equipment includes a hammer crusher and a high-shear mixing equipment;

[0017] The first-stage grinding equipment is a ball mill or a rod mill; the second-stage grinding equipment is an ultrafine mill with a classification function.

[0018] The roughing-cleaning-scavenging combination equipment comprises a roughing microbubble flotation machine, a cleaning microbubble flotation machine and a scavenging microbubble flotation machine. The feed inlet of the roughing microbubble flotation machine is connected to the discharge port of the second-stage grinding equipment, and the clean coal outlet is connected to the feed inlet of the cleaning microbubble flotation machine; the clean coal outlet of the cleaning microbubble flotation machine is connected to the clean coal filter press equipment as the clean coal outlet of the roughing-cleaning-scavenging combination equipment, and the tail coal outlet of the cleaning microbubble flotation machine and the tail coal outlet of the roughing microbubble flotation machine are connected to the feed inlet of the scavenging microbubble flotation machine; the clean coal outlet of the scavenging microbubble flotation machine is connected to the feed inlet of the second-stage flotation equipment as the scavenging concentrate outlet of the roughing-cleaning-scavenging combination equipment, and the tail coal outlet of the scavenging microbubble flotation machine is connected to the concentrator as the tail coal outlet of the roughing-cleaning-scavenging combination equipment.

[0019] In the multi-stage grinding and multi-stage flotation depth sorting system for coking medium coal, if the clean coal product of the first-stage flotation equipment does not meet the requirements of qualified clean coal products, the clean coal of the first-stage flotation equipment and the clean coal of the second-stage flotation equipment are combined and enter the second-stage grinding equipment.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention provides a multi-stage grinding and multi-stage flotation deep sorting process and system for coking medium coal. Through the two-stage pre-selection and flotation process of coking medium coal coarse crushing and coarse grinding, it fully utilizes the advantage of mechanical stirring flotation machine for coarse particle flotation, realizes the rapid grinding and dissociation of large medium coal high ash gangue in coarser particle size and flotation tailings, and can simultaneously recover clean coal products with ash content reaching the requirements according to the dissociation of clean coal.

[0022] 2. The second-stage fine grinding and dissociation section of the present invention adopts an ultrafine mill with an internal classification function, which can achieve a closed-circuit grinding effect through open-circuit grinding, simplifying the fine grinding process and reducing the cost of the fine grinding link.

[0023] 3. The combined flotation process of roughing, concentrating and scavenging of finely ground products is completed by a single micro-bubble flotation machine, which gives full play to the advantage of the micro-bubble flotation machine in high precision sorting of fine particles.

[0024] 4. The roughing-cleaning-scavenging combined flotation process uses a scavenging micro-bubble flotation machine to discharge tailings directly and scavenging clean coal back into the two-stage pre-selection flotation process. After being enriched by the two-stage pre-selection flotation, it enters the fine grinding process equipment, which effectively improves the clean coal recovery rate.

[0025] 5. The separation process proposed by the present invention is simple, the technology is mature, the investment is small, the operating cost is low, and the economic benefits are remarkable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A process flow chart of a multi-stage grinding and multi-stage flotation depth separation process for coking coal provided in Example 1 of the present invention;

[0027] Figure 2 A process flow chart of a multi-stage grinding and multi-stage flotation depth separation process for coking coal provided in Example 2 of the present invention;

[0028] Figure 3 This is a schematic structural diagram of a multi-stage grinding and multi-stage flotation depth separation system for coking coal provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] Embodiment 1

[0031] like Figure 1 As shown, the first embodiment of the present invention provides a multi-stage grinding and multi-stage flotation depth separation process for coking coal, comprising the following steps:

[0032] S1. After crushing the coking coal, add water to mix it into ore slurry.

[0033] In this embodiment, the coking medium coal is coke and fertilizer medium coal, which is fed into a hammer crusher and a coarse grinding device in sequence to grind the particle size to less than 0.25 mm, or P 0.074 When the concentration is greater than 50%, water is added to adjust the slurry to a concentration of 100-200 g / L.

[0034] Among them, P 0.074 It indicates the proportion of product particles with a particle size less than 0.074mm.

[0035] S2, the slurry is sequentially passed through a first-stage flotation device, the first-stage flotation device outputs clean coal products and tailings, the tailings from the first-stage flotation device enters a second-stage flotation device, and the second-stage flotation device outputs high-ash clean coal products and high-ash tailings.

[0036] Specifically, in this embodiment, the first-stage flotation device and the second-stage flotation device are mechanically agitated flotation machines with stepped sorting tanks, and the tank combinations are 2+2 or 2+3, that is, the first-stage flotation device includes two tanks, the second-stage flotation device includes two tanks, and the two tanks of the first-stage flotation device and the two tanks of the second-stage flotation device are arranged with a height difference, or the first-stage flotation device includes two tanks, the second-stage flotation device includes three tanks, and the two tanks of the first-stage flotation device and the three tanks of the second-stage flotation device are arranged with a height difference.

[0037] S3. The high-ash clean coal product enters the second-stage fine grinding and dissociation section, and then is mixed with water to form a new ore pulp and then passed through a roughing-cleaning-scavenging combined flotation process. The qualified clean coal product obtained is filtered together with the qualified clean coal product obtained from the first-stage flotation equipment; the scavenging concentrate returns to the second-stage flotation equipment, and after flotation concentration and tailings discarding, it enters the second-stage fine grinding and dissociation section together with the high-ash clean coal for re-grinding; the scavenging tailings are combined with the tailings of the second-stage flotation equipment, concentrated by a concentrator, and dehydrated by a tailings filter press to obtain the final flotation tailings.

[0038] The equipment used in the roughing-cleaning-scavenging combined flotation process is a microbubble flotation machine, wherein one microbubble flotation machine is used for roughing, cleaning and scavenging respectively.

[0039] In the second fine grinding and dissociation section of step S3, the grinding particle size is controlled to be less than 400 mesh, or P 0.045 Greater than 90%, then add water to make a new slurry with a concentration of 30-80 g / L. 0.045 Indicates the proportion of product particles with a particle size less than 0.045mm.

[0040] Specifically, in this embodiment, the first stage coarse grinding equipment is a ball mill or a rod mill, and the second stage fine grinding and dissociation section adopts an ultrafine mill with a self-classifying function. The closed-circuit grinding effect can be achieved through open-circuit grinding, which simplifies the fine grinding process.

[0041] Embodiment 2

[0042] like Figure 2 As shown, the first embodiment of the present invention provides a multi-stage grinding and multi-stage flotation depth separation process for coking coal, comprising the following steps:

[0043] S1. After crushing the coking coal, add water to mix it into ore slurry.

[0044] Different from Example 1, in this example, when the coking coal is coke and fat coal low-ash flotation tailings slime, it is fed into a hammer crusher and a high shear mixing equipment in sequence, and then water is added to disperse and blend it into a slurry with a concentration of 100-200 g / L.

[0045] S2, the slurry is sequentially passed through a first-stage flotation device, the first-stage flotation device outputs clean coal products and tailings, the tailings from the first-stage flotation device enters a second-stage flotation device, and the second-stage flotation device outputs high-ash clean coal products and high-ash tailings.

[0046] Specifically, in this embodiment, the first-stage flotation equipment and the second-stage flotation equipment are mechanical stirring flotation machines with stepped sorting tanks.

[0047] S3. The high-ash clean coal product enters the second-stage fine grinding and dissociation section, and then is mixed with water to form a new ore pulp and then passed through a roughing-cleaning-scavenging combined flotation process. The qualified clean coal product obtained is filtered together with the qualified clean coal product obtained from the first-stage flotation equipment; the scavenging concentrate returns to the second-stage flotation equipment, and after flotation concentration and tailings discarding, it enters the second-stage fine grinding and dissociation section together with the high-ash clean coal for re-grinding; the scavenging tailings are combined with the tailings of the second-stage flotation equipment, concentrated by a concentrator, and dehydrated by a tailings filter press to obtain the final flotation tailings.

[0048] Specifically, Figure 2As shown, in step S2, if the clean coal product of the first flotation device does not meet the requirements of qualified clean coal products, the clean coal product of the first flotation device and the clean coal product of the second flotation device are combined and enter the second fine grinding and dissociation section.

[0049] In the second fine grinding and dissociation section of step S3, the grinding particle size is controlled to be less than 400 mesh, or P 0.045 Greater than 90%, and then add water to make a new slurry with a concentration of 30-80 g / L.

[0050] Specifically, in this embodiment, the first stage coarse grinding equipment is a ball mill or a rod mill, and the second stage fine grinding and dissociation section adopts an ultrafine mill with a self-classifying function. The closed-circuit grinding effect can be achieved through open-circuit grinding, which simplifies the fine grinding process.

[0051] Embodiment 3

[0052] The third embodiment of the present invention provides a multi-stage grinding and multi-stage flotation depth separation system for coking coal, such as Figure 3 As shown, it includes: crushing equipment, a first-stage flotation equipment, a second-stage flotation equipment, a second-stage grinding equipment, a roughing-cleaning-scavenging combined equipment, a clean coal filter press equipment, a concentrator, and a tail coal filter press equipment. The coking coal enters the feed inlet of the first-stage flotation equipment after being crushed and blended into ore pulp. The tail coal outlet of the first-stage flotation equipment is connected to the feed inlet of the second-stage flotation equipment. The clean coal outlet of the second-stage flotation equipment is connected to the feed inlet of the second-stage grinding equipment. The discharge port of the second-stage grinding equipment is connected to the roughing-cleaning-scavenging combined equipment. The feed inlet of the cleaning-cleaning-scavenging combination equipment is connected, the clean coal outlet of the roughing-cleaning-scavenging combination equipment and the clean coal outlet of the first-stage flotation equipment are connected to the clean coal filter press equipment, and the flotation clean coal is output through the clean coal filter press equipment; the tail coal outlet of the roughing-cleaning-scavenging combination equipment and the tail coal outlet of the second-stage flotation equipment are both connected to the tail coal filter press equipment through the concentrator, and the flotation tail coal is output through the tail coal filter press equipment, and the scavenging concentrate outlet of the roughing-cleaning-scavenging combination equipment is connected to the feed inlet of the second-stage flotation equipment.

[0053] Specifically, in this embodiment, when the coking medium coal is coking fat coal, the crushing equipment includes a hammer crusher and a coarse grinding equipment; when the coking medium coal is coking fat coal low-ash flotation tailing slime, the crushing equipment includes a hammer crusher and a high shear mixing equipment.

[0054] Specifically, in this embodiment, the first-stage grinding equipment is a ball mill or a rod mill; the second-stage grinding equipment is an ultrafine mill with a classification function.

[0055] Specifically, in this embodiment, the roughing-fine-scavenging combination equipment includes a roughing micro-bubble flotation machine, a fine micro-bubble flotation machine and a scavenging micro-bubble flotation machine. The feed port of the roughing micro-bubble flotation machine is connected to the discharge port of the second-stage grinding equipment, and the clean coal outlet is connected to the feed port of the fine micro-bubble flotation machine; the clean coal outlet of the fine micro-bubble flotation machine is connected to the clean coal filter press equipment as the clean coal outlet of the roughing-fine-scavenging combination equipment, and the tail coal outlet of the fine micro-bubble flotation machine and the tail coal outlet of the roughing micro-bubble flotation machine are connected to the feed port of the scavenging micro-bubble flotation machine; the clean coal outlet of the scavenging micro-bubble flotation machine is connected to the feed port of the second-stage flotation equipment as the scavenging concentrate outlet of the roughing-fine-scavenging combination equipment, and the tail coal outlet of the scavenging micro-bubble flotation machine is connected to the concentrator as the tail coal outlet of the roughing-fine-scavenging combination equipment. Specifically, in this embodiment, the tail coal of the roughing micro-bubble flotation machine, the cleaning micro-bubble flotation machine and the scavenging micro-bubble flotation machine can also be circulated back to their own feed ports for material circulation to increase the clean coal recovery rate.

[0056] Specifically, in this embodiment, if the clean coal product of the first-stage flotation equipment does not meet the requirements of qualified clean coal products, the clean coal of the first-stage flotation equipment and the clean coal of the second-stage flotation equipment are combined and enter the second-stage grinding equipment.

[0057] Specifically, in this embodiment, a circulating water pool is also included, the inlet of which is connected to the water outlet of the clean coal filter press equipment, the tail coal filter press equipment and the concentrator, and is used to supply water to the crushing equipment so that the coking coal can be crushed and blended into ore pulp. At the same time, it is also used to grind the secondary second-stage grinding equipment to obtain a particle size of less than 400 mesh, or P 0.045 More than 90% of the slurry is supplied with water, so that it is added with water to be adjusted into a new slurry with a concentration of 30-80 g / L.

[0058] In summary, the present invention provides a multi-stage grinding and multi-stage flotation deep sorting process and system for coking medium coal with simple process, high sorting accuracy and efficiency, which fully utilizes the advantages of mechanical stirring flotation machine for coarse particle flotation, realizes the rapid grinding and dissociation of large medium coal and high ash gangue in coarse particle size and flotation tailings, and can synchronously recover the clean coal product with ash content reaching the required level according to the clean coal dissociation situation. The two-stage fine grinding and dissociation section equipment of the present invention adopts an ultrafine mill with internal classification function, which can achieve closed-circuit grinding effect through open-circuit grinding, simplifies the fine grinding process, and reduces the cost of the fine grinding link. In the present invention, the roughing-cleaning-scavenging combined flotation process of the fine grinding product is completed by a single microbubble flotation machine, which gives full play to the advantages of the microbubble flotation machine for high precision in sorting fine particles. Moreover, it adopts the two-stage pre-selection flotation process of direct discharge of tailings of the scavenging microbubble flotation machine and return of scavenged clean coal, and enters the fine grinding process equipment after two-stage pre-selection flotation enrichment, which effectively improves the clean coal recovery rate. The separation process proposed by the invention is simple, technically mature, requires little investment, has low operating costs, and has significant economic benefits.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-stage grinding and multi-stage flotation depth separation process for coking coal, characterized in that: The following steps are involved: S1, crushing and processing the coking coal, adding water and mixing it into ore slurry; S2, inputting the slurry into a first-stage flotation device, the first-stage flotation device outputs clean coal products and tailings, the tailings from the first-stage flotation device enters a second-stage flotation device, and the second-stage flotation device outputs high-ash clean coal products and high-ash tailings; S3. The high-ash clean coal product enters the second-stage fine grinding and dissociation section, and then is mixed with water to form a new ore pulp and then passes through a roughing-cleaning-scavenging combined flotation process. In the roughing-cleaning-scavenging combined flotation process, the roughing product is refined as a qualified clean coal product and is filtered together with the qualified clean coal product obtained from the first-stage flotation equipment through a clean coal filter to obtain a clean coal product; after the roughing and concentrating tailings are scavenged, the scavenged concentrate is returned to the second-stage flotation equipment, and after flotation concentration and tailings discarding, it enters the second-stage fine grinding and dissociation section together with the high-ash clean coal for re-grinding; the scavenging tailings are combined with the high-ash tailings output from the second-stage flotation equipment, and after being concentrated by a concentrator, they are dehydrated by a tailings slurry filter press to obtain the final flotation tailings.

2. A multi-stage grinding and multi-stage flotation depth separation process for coking coal according to claim 1, characterized in that: In step S2, if the clean coal product of the first stage flotation device does not meet the requirements of qualified clean coal products, the clean coal product of the first stage flotation device and the clean coal product of the second stage flotation device are combined and then enter the second stage fine grinding and dissociation section.

3. The multi-stage grinding and multi-stage flotation depth separation process of coking coal according to claim 1, characterized in that: In the step S1, when the coking coal is coke-fertilizer coal, it is fed into a hammer crusher and a coarse grinding device in sequence to grind the particle size to less than 0.25 mm, or P 0.074 When the concentration is greater than 50%, water is added to adjust the slurry to a concentration of 100-200 g / L; 0.074 Indicates the proportion of product particles with a particle size less than 0.074mm; When the coking coal is low-ash flotation tailings slime of coke and fertilizer coal, it is fed into a hammer crusher and a high shear mixing equipment in sequence, and then dispersed and blended with water to a slurry concentration of 100-200 g / L.

4. A multi-stage grinding and multi-stage flotation depth separation process for coking coal according to claim 3, characterized in that: The first stage coarse grinding equipment is a ball mill or a rod mill, and the equipment used in the second stage fine grinding and dissociation section is an ultrafine mill with a classification function.

5. The multi-stage grinding and multi-stage flotation depth separation process of coking coal according to claim 1, characterized in that: In the second fine grinding and dissociation section of step S3, the grinding particle size is controlled to be less than 400 mesh, or P 0.045 Greater than 90%, then add water to make a new slurry with a concentration of 30-80 g / L, P 0.045 Indicates the proportion of product particles with a particle size less than 0.045mm.

6. The multi-stage grinding and multi-stage flotation depth separation process of coking coal according to claim 1, characterized in that: The equipment used in the roughing-cleaning-scavenging combined flotation process is a microbubble flotation machine, wherein one microbubble flotation machine is used for roughing, cleaning and scavenging respectively.

7. The multi-stage grinding and multi-stage flotation depth separation process of coking coal according to claim 1, characterized in that: The first stage flotation equipment and the second stage flotation equipment are mechanical stirring flotation machines with stepped sorting tanks.

8. A multi-stage grinding and multi-stage flotation depth sorting system for coking coal, characterized in that: include: Crushing equipment, first-stage flotation equipment, second-stage flotation equipment, second-stage grinding equipment, roughing-cleaning-scavenging combined equipment, clean coal filter press equipment, concentrator, tailing coal filter press equipment, the coking coal enters the feed inlet of the first-stage flotation equipment after being crushed and blended into ore pulp, the tail coal outlet of the first-stage flotation equipment is connected to the feed inlet of the second-stage flotation equipment, the clean coal outlet of the second-stage flotation equipment is connected to the feed inlet of the second-stage grinding equipment, and the discharge port of the second-stage grinding equipment is connected to the feed inlet of the roughing-cleaning-scavenging combined equipment The clean coal outlet of the roughing-cleaning-scavenging combination equipment and the clean coal outlet of the first-stage flotation equipment are connected to the clean coal filter press equipment together, and the flotation clean coal is output through the clean coal filter press equipment; the tail coal outlet of the roughing-cleaning-scavenging combination equipment and the tail coal outlet of the second-stage flotation equipment are both connected to the tail coal filter press equipment through the concentrator, and the flotation tail coal is output through the tail coal filter press equipment, and the scavenging concentrate outlet of the roughing-cleaning-scavenging combination equipment is connected to the feed port of the second-stage flotation equipment; The roughing-cleaning-scavenging combination equipment comprises a roughing microbubble flotation machine, a cleaning microbubble flotation machine and a scavenging microbubble flotation machine. The feed inlet of the roughing microbubble flotation machine is connected to the discharge port of the second-stage grinding equipment, and the clean coal outlet is connected to the feed inlet of the cleaning microbubble flotation machine; the clean coal outlet of the cleaning microbubble flotation machine is connected to the clean coal filter press equipment as the clean coal outlet of the roughing-cleaning-scavenging combination equipment, and the tail coal outlet of the cleaning microbubble flotation machine and the tail coal outlet of the roughing microbubble flotation machine are connected to the feed inlet of the scavenging microbubble flotation machine; the clean coal outlet of the scavenging microbubble flotation machine is connected to the feed inlet of the second-stage flotation equipment as the scavenging concentrate outlet of the roughing-cleaning-scavenging combination equipment, and the tail coal outlet of the scavenging microbubble flotation machine is connected to the concentrator as the tail coal outlet of the roughing-cleaning-scavenging combination equipment.

9. A multi-stage grinding and multi-stage flotation depth sorting system for coking coal according to claim 8, characterized in that: When the coking medium coal is coke-fertilizer medium coal, the crushing equipment includes a hammer crusher and a first-stage grinding equipment; When the coking coal is coke-fertilizer coal low-ash flotation tailing slime, the crushing equipment includes hammer crusher and high shear mixing equipment; The first-stage grinding equipment is a ball mill or a rod mill; the second-stage grinding equipment is an ultrafine mill with a classification function.

10. The multi-stage grinding and multi-stage flotation depth separation system for coking coal according to claim 8, characterized in that: If the clean coal product of the first-stage flotation equipment does not meet the requirements of qualified clean coal products, the clean coal of the first-stage flotation equipment and the clean coal of the second-stage flotation equipment will be combined and sent to the second-stage grinding equipment.

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