CN110882850A

CN110882850A - Mineral separation system and mineral separation method for protecting graphite flakes

Info

Publication number: CN110882850A
Application number: CN201911267953.3A
Authority: CN
Inventors: 彭伟军; 曹亦俊; 李超
Original assignee: Zhengzhou University
Current assignee: Zhengzhou University
Priority date: 2019-12-11
Filing date: 2019-12-11
Publication date: 2020-03-17
Anticipated expiration: 2039-12-11
Also published as: CN110882850B

Abstract

The invention relates to a mineral separation system and a mineral separation method for protecting graphite flakes, belongs to the technical field of mineral flotation, and solves the problems of long process flow, high cost and low yield of large graphite flakes in the prior art. The ore dressing system is provided with a high-pressure roller mill, a stirring barrel, coarse particle sorting equipment, an ore mill and a flotation machine along an ore dressing pipeline; the coarse particle sorting equipment comprises a first cylinder, a second cylinder and a gas-water mixing input device, the first cylinder and the second cylinder are both cylindrical structures, the second cylinder is nested outside the upper end of the first cylinder, the upper end face of the second cylinder is higher than that of the first cylinder, an ore discharge port is formed in the side face of the second cylinder, and materials in the first cylinder can overflow to flow into the second cylinder and are discharged through the ore discharge port; the number of the ore mills and the flotation machines is multiple. The beneficiation method comprises the following steps: size mixing, sorting by coarse particle sorting equipment, first regrinding and recleaning, second regrinding and recleaning and third regrinding. The invention realizes the protection of graphite large flakes.

Description

Mineral separation system and mineral separation method for protecting graphite flakes

Technical Field

The invention relates to the technical field of mineral flotation, in particular to a mineral separation system and a mineral separation method for protecting graphite flakes.

Background

Graphite is a crystalline mineral of carbon element, the component of which is carbon, and diamond, carbon nanotube, carbon 60, etc. are allotropes of carbon, and the element is called "black gold". Graphite has excellent physical and chemical properties such as high temperature resistance, heat conduction, electric conduction, chemical stability, lubricity, plasticity and the like, is widely applied to the departments of metallurgy, electricity, light industry, machinery, textile, national defense and the like, and is an important and widely-used non-metallic mineral material and raw material. With the development of high and new technology industry and the development and utilization of graphite and the progress of deep processing technology thereof, novel graphite materials such as graphene and composites thereof, spherical graphite as a lithium ion battery negative electrode material, expanded graphite, nano graphite, graphite fluoride and the like are generated, and the application range of graphite is continuously expanded.

The natural graphite mainly comprises two types of crystalline graphite and aphanitic graphite. Crystalline graphite comprises crystalline flake graphite and dense crystalline blocky graphite, and cryptocrystalline graphite is also called amorphous carbon. The crystal graphite has good crystallization, the grain diameter of the crystal is larger than 1 μm, generally 0.05-1.5mm, the size can reach 5-10mm, and the crystal is more aggregated. The crystalline graphite (flake-shaped) has larger application, the larger the flake is, the better the performance is, the higher the economic value is, and the price of the 0.150mm large flake graphite is 2-4 times of that of the fine flake graphite (the crystal grain diameter is less than 0.150 mm). Therefore, the purity of the crystalline graphite is improved and the large scale of the graphite is protected in the ore dressing process.

At present, most of domestic graphite flake mineral separation methods are stage grinding stage selection, which generally comprises the following steps: rough grinding once, rough concentration once, scavenging once, regrinding rough concentrate for many times and then concentrating. After the graphite ore is subjected to multiple grinding and multi-stage flotation, the purity of the graphite ore concentrate can reach more than 95%. However, the large scale is cracked and broken by high-hardness gangue mineral particles such as quartz and the like by multiple grinding, and the large scale is seriously damaged. At present, a fan and the like are added on the basis of the existing mineral separation system, large scale graphite is separated from crushed mineral powder in a dry state and directly enters a flotation tank for flotation, so that the large scale is prevented from being abraded and damaged by other process steps, the yield of the large scale is improved, the dissociation degree of the graphite in the crushing process is low, and the yield of the large scale graphite is improved to a limited extent. The current common process also comprises roughing, fine concentration and quality grading, and then the graphite concentrate products with different scales and different purities are obtained by respectively grinding and re-selecting, although the large crystalline graphite scales can be protected, the process flow is complex and the investment is large. The prior process generally has the problems of long process flow and relative complexity.

Disclosure of Invention

In view of the above analysis, the present invention aims to provide a beneficiation system and a beneficiation method for protecting graphite flakes, which can solve at least one of the following technical problems: (1) the existing process has long flow; (2) the cost is high and the energy consumption is high; (3) the yield of large graphite flakes is low.

The purpose of the invention is mainly realized by the following technical scheme:

on one hand, the invention provides a mineral processing system for protecting graphite flakes, wherein a high-pressure roller mill, a stirring barrel, coarse particle sorting equipment, an ore grinding machine and a flotation machine are arranged along a mineral processing pipeline; the coarse particle sorting equipment comprises a first cylinder, a second cylinder and a gas-water mixing input device, the first cylinder and the second cylinder are both cylindrical structures, the second cylinder is nested outside the upper end of the first cylinder, the upper end face of the second cylinder is higher than that of the first cylinder, an ore discharge port is formed in the side face of the second cylinder, and materials in the first cylinder can overflow to flow into the second cylinder and are discharged through the ore discharge port; the number of the ore mills and the flotation machines is multiple.

Furthermore, the bottom end surface of the second column body is an inclined surface, and the included angle between the bottom end surface of the second column body and the central axis of the first column body is 20-40 degrees.

Furthermore, the upper end of the first cylinder is open, the second cylinder is nested and assembled outside the open end of the first cylinder, after the first cylinder and the second cylinder are nested and assembled, the bottom end face of the second cylinder is sealed with the outer surface of the first cylinder, the first cylinder and the second cylinder can be nested and assembled coaxially, and materials in the first cylinder can overflow the upper end opening and overflow into the second cylinder in a nesting space between the first cylinder and the second cylinder.

Furthermore, a cover plate is arranged on the upper portion of the second cylinder, a feeding distributor is arranged in the center of the cover plate of the second cylinder, and materials can be input into the first cylinder from the feeding distributor.

Furthermore, a conical structure is arranged at the lower part of the first column body, a bottom flow port is arranged at the bottom of the conical structure, and the bottom flow port is used for discharging tailings; an input port is arranged on the side edge of the upper part of the conical structure, the gas-water mixing input device comprises a gas-water mixing input pipe, the gas-water mixing input pipe is connected with a bubble ejector arranged in the first column body through the input port, a gas inlet pipe and a water inlet pipe are sequentially arranged on the gas-water mixing input pipe along the direction far away from the input port, and a bubble generator is arranged at the joint of the gas inlet pipe and the gas-water mixing input pipe; the water inlet pipe is connected with the water inlet pump, and the air inlet pipe is connected with the air pump.

When mineral separation is carried out, the water inlet pump injects water into the first column body, the air pump injects gas into the first column body, and the water and the gas are uniformly mixed into water and bubble mixed liquid through the gas-water mixing input pipe after passing through the bubble generator; when the water and bubble mixed liquid passes through the bubble ejector, the area is suddenly reduced, the flow rate is suddenly increased, the pressure in the liquid is suddenly reduced, the gas dissolved in the water is separated out to generate a large amount of micro bubbles, and meanwhile, upward water flow with a certain driving force is formed; and after the water and bubble mixed liquid in the first column stably overflows into the second column, the feeding distributor is opened after the water and bubble mixed liquid is discharged from the ore discharge port, and the uniformly mixed ore pulp enters the first column from the feeding distributor for separation.

On the other hand, the invention also provides a mineral separation method for protecting graphite flakes, which comprises the following steps:

step S1: crushing graphite raw ore, guiding the crushed graphite raw ore into a stirring barrel, and performing size mixing in the stirring barrel to obtain ore pulp;

step S2: introducing the ore pulp in the stirring barrel into a first column of coarse particle separation equipment for separation, discharging first concentrate from an ore discharge port after separation, and discharging first tailings from a underflow port;

step S3: concentrating the first concentrate, and then performing first regrinding and recleaning to obtain a second concentrate and a first middling;

step S4: grading the second concentrate by adopting a 100-mesh standard sieve to obtain medium-carbon positive concentrate and medium-carbon negative concentrate;

step S5: and carrying out second regrinding and recleaning on the first middling to obtain third concentrate and second tailings, and combining the third concentrate with the medium-carbon negative concentrate to carry out third regrinding and recleaning to obtain high-carbon negative concentrate and third tailings.

Further, step S1 includes the following steps:

s11, crushing the raw ore by using a high-pressure roller mill, and screening by using a vibrating screen, wherein the graphite ore particles reaching the target size fraction are directly introduced into a stirring barrel, and the graphite ore particles not reaching the target size fraction are returned to the high-pressure roller mill;

and S12, sequentially adding water, a regulator, a collector and a foaming agent into the stirring barrel to carry out size mixing to obtain ore pulp.

Further, the regulator in S12 is quicklime, the using amount of the regulator is 1000-1100 g/t, the collecting agent is kerosene, the using amount of the collecting agent is 60-90 g/t, and the foaming agent is No. 2 oil, and the using amount of the foaming agent is 25-40 g/t.

Further, step S2 includes the following steps:

step S21: the water inlet pump is opened to inject water into the first column body, the air pump is used for injecting air into the first column body, and the water and the air are uniformly mixed into water and bubble mixed liquid through the air-water mixing input pipe after passing through the bubble generator;

step S22: and after the water and bubble mixed liquor in the first cylinder stably overflows into the second cylinder, the feeding distributor is opened after the water and bubble mixed liquor is discharged from the ore discharge port, the evenly mixed ore pulp is fed from the feeding distributor to the first cylinder for separation, wherein the separated first concentrate is discharged from the ore discharge port, and the separated first tailings are discharged from the underflow port.

Further, the first regrinding and recleaning in step S3 includes 2 regrinding and 3 flotation.

Further, in step S5, the second regrinding recleaning includes 1 regrinding and 1 scavenging, and the third regrinding recleaning includes 3 regrinding and 4 flotation.

Compared with the prior art, the invention has at least one of the following beneficial effects:

a) according to the ore dressing system for protecting the graphite flakes, the high-pressure roller mill is adopted to crush the raw ore, so that the graphite flakes are protected in the primary grinding process; most gangue minerals can be abandoned in advance by arranging the coarse particle sorting equipment, the cutting and splitting effects of the gangue mineral particles with higher hardness on the graphite large scale in the subsequent regrinding process can be effectively reduced, the graphite large scale is protected, the operation flow can be shortened, and the system processing capacity is improved.

b) According to the ore dressing method for protecting graphite flakes, gangue mineral particles are discharged in advance, so that the operation flow is shortened, and the system processing capacity is improved; the cracking and splitting effects of gangue mineral particles with higher hardness on the graphite large scale in the subsequent regrinding process are effectively reduced, and the graphite large scale is protected; and then, medium-carbon graphite is graded, medium-carbon + 100-mesh concentrate is directly used as one product, medium-carbon-100-mesh product is reground and recleaning to obtain high-carbon-100-mesh graphite concentrate as another final product, so that graphite with different embedding characteristics in the crystalline graphite ore is subjected to different sorting processes to obtain different products, and the value maximization of the graphite ore is realized, for example, the recovery rate of medium-carbon normal-mesh concentrate is improved by 65-73%, the total recovery rate is improved by 8-9.5%, the dosage of the medicament is reduced by 33-34.5%, and the total time is reduced by 24-27.5%.

c) According to the ore dressing method for protecting graphite flakes, provided by the invention, a coarse particle sorting device is adopted to directly sort a product with a certain size fraction, which is subjected to ultrafine grinding by a high-pressure roller mill, so that coarse-particle gangue minerals in the product are effectively directly discarded, and the subsequent re-grinding and re-sorting operation load is reduced, thereby reducing the energy consumption of an ore mill, reducing the abrasion and improving the treatment capacity. In addition, the discarded coarse-grained gangue minerals are easy to dehydrate and can be directly used as building material sandstone aggregates, so that the economic benefit of enterprises is improved.

In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.

Fig. 1 is a partial structural schematic view of a mineral processing system for protecting graphite flakes in example 1;

FIG. 2 is a block diagram of the process flow of the beneficiation method of example 2;

fig. 3 is a partial structural schematic diagram of a mineral separation system for protecting graphite flakes, which is provided with a nanobubble generation device in example 1.

Reference numerals:

1-water pump, 2-second liquid flowmeter, 3-bubble generator, 4-gas flowmeter, 5-bubble injector, 6-first cylinder, 7-second cylinder, 8-feeding distributor, 9-ore discharge port, 10-underflow port, 11-stirring barrel, 12-air compressor, 13-slurry pump, 14-slurry feed port, 15-stirrer, 16-compressed air inlet valve, 17-air release valve, 18-pressure gauge, 19-pressure dissolved air tank and 20-pressure release valve.

Detailed Description

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.

The screening plates are arranged in some existing coarse particle sorting equipment, and the screening plates can block ore pulp from moving upwards in the sorting process, so that the sorting time can be greatly prolonged, the sorting quality is greatly reduced, and the sorting flow is increased; in some coarse particle sorting methods, a mode of combining top water injection and bottom water injection is adopted, and the applicant finds that the top water injection is not beneficial to floating of coarse particles in ore pulp in a large amount of practical processes, so that incomplete sorting is caused; therefore, the invention provides coarse particle sorting equipment with a simple structure through creative research, and can realize sorting of coarse-particle gangue minerals by only one-time sorting through accurately controlling parameters in the sorting process, effectively reduce the cutting and splitting effects of the gangue mineral particles with higher hardness on graphite large scales in the subsequent regrinding process, protect the graphite large scales, shorten the operation flow and improve the system processing capacity.

Example 1

One embodiment of the invention, as shown in fig. 1 and 3, discloses a mineral separation system for protecting graphite flakes, which is provided with a high-pressure roller mill, a stirring barrel 11, coarse particle separation equipment, an ore mill and a flotation machine along a mineral separation pipeline; coarse grain sorting facilities includes first cylinder 6, second cylinder 7 and gas-water mixing input device, and first cylinder 6 and second cylinder 7 are cylindric structure, and second cylinder 7 nests in the upper end outside of first cylinder 6, and the up end of second cylinder 7 is higher than the up end of first cylinder 6, and the side of second cylinder 7 is equipped with ore discharge port 9, and the material in the first cylinder 6 can overflow and flow into in the second cylinder 7, discharges through ore discharge port 9.

Compared with the prior art, the mineral processing system for protecting graphite flakes provided by the embodiment adopts the high-pressure roller mill to crush raw ores, so that the graphite flakes are protected in the primary grinding process; most gangue minerals can be abandoned in advance by arranging the coarse particle sorting equipment, the cutting and splitting effects of the gangue mineral particles with higher hardness on the graphite large scale in the subsequent regrinding process can be effectively reduced, the graphite large scale is protected, the operation flow can be shortened, and the system processing capacity is improved.

Specifically, the second cylinder 7 is nested at the outer end of the first cylinder 6, and the specific nesting is as follows: the upper part of the first cylinder 6 penetrates through the bottom end surface of the second cylinder 7 and is arranged on the second cylinder 7 in a sealing and nesting way.

Specifically, the upper end surface of the first cylinder 6 is opened, so that the material in the first cylinder 6 can overflow into the second cylinder 7.

Considering that the material which is prevented from overflowing and flowing into the second cylinder 7 flows back to the first cylinder 6, the bottom end face of the second cylinder 7 is an inclined plane, the included angle between the bottom end face of the second cylinder 7 and the central axis of the first cylinder 6 is 20-40 degrees, the bottom end face of the second cylinder 7 is an inclined plane with a certain inclination angle, the sorted particles can be discharged quickly, the sorted particles in the second cylinder 7 are prevented from being accumulated to cause blockage, and the working stability of the coarse particle sorting equipment is ensured. Preferably, the bottom end face of the second cylinder 7 forms an angle of 30 ° with the longitudinal centre line of the first cylinder 3.

In order to prevent the overflow of the floated ore pulp, the upper part of the second column body 7 is provided with a cover plate, so that the overflow of the ore pulp/foam can be prevented, and the working stability of the coarse particle sorting equipment is ensured. A feeding distributor 8 is arranged at the center of the cover plate of the second cylinder 7, the length of the feeding distributor 8 can be adjusted, and materials can be input into the first cylinder 6 from the feeding distributor 8; the feeding distributor 8 is provided with a first liquid flow meter which is used for adjusting the flow of the feeding material.

In order to ensure that the volume in the second cylinder 7 is large enough and overflow materials can be discharged in time, the inner diameter R2 of the second cylinder 7 is larger than the outer diameter R1 of the first cylinder 6, the volume in the second cylinder 7 is small and the materials are easy to overflow due to the fact that the difference between R2 and R1 is too small, and the occupied area of coarse particle sorting equipment is large and the requirements on the strength and other performances of the equipment are high due to the fact that the difference between R2 and R1 is too large; therefore, the difference between R2 and R1 is controlled to be 100-150 mm.

The lower part of the first column 6 is provided with a conical structure, the bottom of the conical structure is provided with a bottom flow port 10, and the bottom flow port 10 is used for discharging tailings; an input port is arranged on the side edge of the upper part of the conical structure, the gas-water mixing input device comprises a gas-water mixing input pipe, the gas-water mixing input pipe is connected with a bubble ejector 5 arranged in a first cylinder 6 through the input port, a gas inlet pipe and a water inlet pipe are sequentially arranged on the gas-water mixing input pipe along the direction far away from the input port, a gas flowmeter 4 is arranged on the gas inlet pipe, a second liquid flowmeter 2 is arranged on the water inlet pipe, the inflow flow rate is adjusted through the second liquid flowmeter 2, the inflow flow rate is adjusted through the gas flowmeter 4, and a bubble generator 3 is arranged at the joint of the gas inlet pipe and the gas-water mixing input; the water inlet pipe is connected with the water inlet pump 1, and the air inlet pipe is connected with the air pump.

Specifically, the connection between the gas-water mixing input pipe and the bubble jet 5 is conical.

It should be noted that, the conical structure at the lower part of the first cylinder 6 can concentrate underflow ore pulp to play a certain dewatering role, when in implementation, the ore pulp is fed into the coarse particle sorting equipment from the top and is sorted in ascending water flow clamped in bubbles, gangue mineral particles have high density and poor surface hydrophobicity and are not collided and adhered with the bubbles, and further the gangue mineral particles cannot float upwards to overflow under the action of the ascending water flow mixed with the bubbles, and only can sink into the conical structure at the lower part of the first cylinder 6 as underflow, and the ore pulp at the upper part of the conical structure continuously extrudes the ore pulp at the bottom of the cone under the action of gravity along with the falling and deposition of the ore pulp; the cross section area is gradually reduced from top to bottom by the design of the conical structure, so that the pressure of the pulp extruded from top to bottom is gradually increased, the moisture in the gaps among particles is reduced, and a certain concentration effect is realized on the underflow.

Specifically, the bubble ejector 5 is a perforated plate (e.g., a circular perforated plate) whose holes are distributed in a radial and concentric circular shape with a center hole, or in a radial and concentric circular shape without a center hole; the perforated plate has a certain thickness and the hole channel has a certain length, so that a certain time is provided for cavitation and precipitation of gas dissolved in water; when the device is implemented, the gas-water mixture flows through the gas-water mixing input pipe, meets the orifice plate, the area of the channel is suddenly reduced, the flow speed is suddenly increased, the pressure in the fluid is suddenly reduced, the gas dissolved in the water is separated out to generate a large amount of micro bubbles, and meanwhile, the upward water flow with a certain driving force is formed.

In order to provide the maximum degree of air bubbles and water flow, the height H of the air bubble injector 5 from the underflow port₁Too large results in too small rising path of the bubbles from the bubble ejector 5, reduced collision probability of the bubbles and coarse particles in the ore pulp, and reduced separation effect; h₁When the size of the ore pulp is too small, the high-concentration ore pulp at the bottom of the conical structure can block rising water flow and bubbles, so that the pressure loss is increased, and the separation effect is reduced; therefore, the height H of the bubble jet 5 from the underflow port is controlled₁1/4-1/3 of the total height H of the first column 6, preferably H₁1/4H.

Preferably, the bubble jet ejector 5 is a circular porous plate, considering that the diameter of the bubble jet ejector 5 is too long, for example, when the diameter D1 of the bubble jet ejector 5 is equal to the inner diameter D2 of the first column 6, a part of coarse tailings particles are trapped at the contact edge of the column and the bubble jet ejector, which is not favorable for the discharge of the tailings and the normal operation of the equipment; when the diameter D1 of the bubble ejector 5 is too small, the bubbles are unevenly distributed on the cross section of the first cylinder 6, so that the particles falling from the edge of the first cylinder 6 cannot collide with the bubbles to be adhered, and the mineralization degree and the sorting effect are reduced; accordingly, the diameter D1 of bubble jet 5 is controlled to be smaller than the inner diameter D2 of first cylinder 6, preferably D1 is 5/6D 2.

In order to ensure that the air bubbles generated by the air bubble ejector 5 can sort coarse-grained gangue minerals, the small holes on the air bubble ejector 5 are cylindrical holes, the hole diameter is 0.5-2 mm, the depth of the small holes is 2mm, the distance between every two adjacent small holes is 2mm, and preferably, the hole diameter of each small hole is 1 mm. In order to be able to sort minerals of different particle sizes, the bubble jet 5 is of a detachable construction, and orifice plates of different pore sizes can be replaced as required.

Alternatively, in order to spray the gas-water mixture in a jet form, the small hole of the bubble jet 5 is a conical hole, the diameter of the conical hole on the surface close to the underflow port 10 is 0.5mm, the diameter of the conical hole on the surface far from the underflow port 10 is 1mm, and the depth of the small hole is 2 mm.

In addition, the inside of first cylinder 6 is equipped with pressure sensor, and pressure sensor links to each other with the pressure control case, and the height of bed is selected separately in the numerical control first cylinder 6 of pressure control case through pressure sensor, and then the regulation and control is selected separately the effect.

Specifically, the number of the ore mill and the flotation machine is plural.

Specifically, a vibrating screen is arranged between the high-pressure roller mill and the stirring barrel 11, so that the high-pressure roller mill and the vibrating screen form a closed-circuit superfine crushing system, products meeting the requirement of the granularity enter the stirring barrel 11, and products not meeting the requirement of the granularity return to the high-pressure roller mill.

In practice, the coarse particle sorting equipment is used by the following steps:

the method comprises the following steps: the water inlet pump 1 is opened to inject water into the first column body 6, the second liquid flow meter 2 is adjusted, gas is injected into the first column body 6 through the gas pump 4, and the water and the gas are uniformly mixed through the gas-water mixing input pipe after passing through the bubble generator 3; when the mixed gas-water mixture passes through the bubble ejector 5, the area is suddenly reduced, the flow rate is sharply increased, the pressure in the fluid is suddenly reduced according to the Bernoulli principle, the gas dissolved in the water is separated out to generate a large number of micro bubbles, and meanwhile, upward water flow with a certain driving force is formed;

step two: after the water and bubble mixed liquor in the first cylinder 6 stably overflows to the second cylinder 7 and is discharged through the ore discharge port 9, the feeding distributor 8 is opened, the evenly mixed ore pulp is discharged from the feeding distributor 8 to the first cylinder 6 for separation, wherein the separated first concentrate is discharged through the ore discharge port 9, and the separated first tailings are discharged through the underflow port 10.

In one possible design, a nano-bubble generating device is arranged between the stirring barrel 11 and the feeding distributor 8, and comprises an air compressor 12 and a pressure dissolved air tank 19; the pressure dissolved air tank 19 is of a cylindrical structure, and a first pipeline, a second pipeline and a third pipeline are arranged at the top of the pressure dissolved air tank 19; the first pipeline is connected with the stirring barrel 11 and used for conveying ore pulp, and a slurry pump 13 and an ore pulp feed inlet 14 are arranged on the first pipeline; the second pipeline is connected with the air compressor 12 and used for conveying compressed air, and a compressed air inlet valve 16 is arranged on the second pipeline; the third pipeline is communicated with the atmosphere; the ore pulp and the compressed gas are mixed in a pressure dissolved air tank 19; in order to monitor the pressure in the pressure dissolved air tank 19 and prevent the pressure in the pressure dissolved air tank 19 from being too high or too low, a pressure gauge 18 is arranged on the side surface of the pressure dissolved air tank 19, and a vent valve 17 is arranged on a third pipeline; a fourth pipeline is arranged at the bottom of the pressure dissolved air tank 19 and is connected with the pipeline of the feeding distributor 8, and a pressure reducing valve 20 is arranged at the joint of the fourth pipeline and the pipeline of the feeding distributor 8; the diameter of the pipeline of the feeding distributor 8 is larger than that of the fourth pipeline, and specifically, the diameter of the pipeline of the feeding distributor 8 is 1.5-2.5 times of that of the fourth pipeline.

In order to ensure that the mixed slurry is kept in a suspended state without causing the deposition of the ore particles, an agitator 15 is provided above the pressure gas tank 19.

In practice, when the mixture of compressed gas and ore pulp enters the pipeline of the feeding distributor 8 through the pressure reducing valve 20, the pressure of the compressed gas entering the large pipeline from the small pipeline is suddenly reduced, and the dissolved high-pressure gas is changed into nano bubbles and attached to the surfaces of hydrophobic mineral particles to form a nano bubble-mineral particle complex; after entering the first cylinder 6, the nano bubble-mineral particle complex is more likely to collide and adhere with rising bubbles to form a larger bubble-particle complex, and then moves upwards to the surface of the ore pulp solution under the action of the buoyancy force and the supporting force of rising water flow, overflows to the second cylinder 7, and is discharged through the ore discharge port 9.

The nanobubble-mineral particle complex generated by the nanobubble generating device is combined with the rising bubbles in the first cylinder 6 to form larger bubbles, so that mineral particles with larger particle size can be sorted, and the applicability is wider; and the nano bubbles can be used as a secondary collector, so that the using amount of the collector can be reduced; in addition, the nano-bubble generation mechanism is unique, and the consumption of the foaming agent is reduced by more than 20% compared with the conventional bubble; and as the nano bubbles stably grow on the surfaces of the mineral particles with good hydrophobicity in advance and collide and adhere with the rising microbubbles in the first column 6 under the action of the bridging force of the nano bubbles, the adhesion probability and stability of the useful mineral particles and the microbubbles can be obviously improved, and the separation recovery rate of the useful mineral coarse particles is increased.

In the following examples and comparative examples, +100 mesh means a particle size of 100 mesh or more and-100 mesh means a particle size of less than 100 mesh; similarly, +0.15mm means a particle size of greater than or equal to 0.15 mm.

Example 2

A specific embodiment of the present invention, as shown in fig. 2, discloses a beneficiation method for protecting graphite flakes, which employs the beneficiation system for protecting graphite flakes provided in embodiment 1, and the beneficiation method includes the following steps:

step S1: crushing graphite raw ore, guiding the crushed graphite raw ore into a stirring barrel 11, and performing size mixing in the stirring barrel 11 to obtain ore pulp;

step S2: introducing ore pulp in the stirring barrel 11 into a first cylinder 6 of coarse particle separation equipment for separation, discharging first concentrate from an ore discharge port 9 after separation, and discharging first tailings from a underflow port 10;

step S4: classifying the second concentrate by a 100-mesh standard sieve to obtain medium-carbon normal-mesh concentrate (the particle size of the normal mesh is larger than or equal to 100 meshes, and the particle size of the 100 meshes is 0.15mm) and medium-carbon negative-mesh concentrate (the particle size of the negative mesh is smaller than 100 meshes);

Specifically, step S1 includes the following steps:

s11, crushing the raw ore by using a high-pressure roller mill, and screening by using a vibrating screen, wherein the graphite ore particles reaching the target size fraction are directly introduced into the stirring barrel 11, and the graphite ore particles not reaching the target size fraction are returned to the high-pressure roller mill; in the step, a high-pressure roller mill is adopted to crush the graphite raw ore, so that the graphite flakes are protected in the primary grinding process;

s12, sequentially adding water, a regulator, a collector and a foaming agent into the stirring barrel 11 for size mixing to obtain ore pulp.

Specifically, the adding sequence of water, the regulator, the collector and the foaming agent cannot be changed, because water is added to form a mineral slurry solution, then the collector is added to be selectively adsorbed on the surface of mineral particles to make the mineral particles hydrophobic, and then the foaming agent is added to facilitate the adhesion of the hydrophobic mineral particles and bubbles; and adding each material of water, the regulator, the collecting agent and the foaming agent, then stirring for 3-5 min, namely adding water, then stirring for 3-5 min, then adding the regulator, then stirring for 3-5 min, then adding the collecting agent, stirring for 3-5 min, finally adding the foaming agent, and stirring for 3-5 min to obtain the ore pulp. Can make each component misce bene of ore pulp through the stirring, at the sorting process in later stage, it is better to select separately the effect.

Considering that the concentration of the ore pulp is too low, the treatment capacity is too low, the consumption of the medicament is large, and the production cost is high; the ore pulp concentration is too high, the resistance among particles is increased, the separation is not facilitated, and the high-density gangue minerals are easy to be mixed into the low-density concentrate, so that the separation effect is deteriorated. Therefore, the slurry concentration in S12 was controlled to 50% to 75%.

Preferably, the collector in S12 is one or a combination of kerosene, diesel oil, or other collectors for coal separation, and the collector can improve the difference in hydrophobicity between the concentrate and the gangue minerals in the graphite ore particles, and is adsorbed on the surface of the concentrate to improve the hydrophobicity of the surface of the concentrate, so that bubbles are easily adsorbed on the surface of the concentrate with good hydrophobicity, thereby providing a precondition for separation.

Preferably, the regulator in S12 is quicklime with the use amount of 1000-1100 g/t, the collector is kerosene with the use amount of 60-90 g/t, and the foaming agent is No. 2 oil with the use amount of 25-40 g/t.

Specifically, step S2 includes the following steps:

step S21: the water inlet pump 1 is opened to inject water into the first column body 6, the air pump 4 is used to inject air into the first column body 6, and the water and the air are uniformly mixed through the air-water mixing input pipe after passing through the bubble generator 3; when the mixed gas-water mixture passes through the bubble ejector 5, the area is suddenly reduced, the flow rate is sharply increased, the pressure in the fluid is suddenly reduced according to the Bernoulli principle, the gas dissolved in the water is separated out to generate a large number of micro bubbles, and meanwhile, upward water flow with a certain driving force is formed;

step S22: after the water and bubble mixed liquor in the first cylinder 6 stably overflows to the second cylinder 7 and is discharged through the ore discharge port 9, the feeding distributor 8 is opened, the ore pulp uniformly mixed in the stirring barrel 11 is fed from the feeding distributor 8 to the first cylinder 6 for separation, wherein the separated first concentrate is discharged through the ore discharge port 9, and the separated first tailings are discharged through the underflow port 10.

In step S21, the rising force of the water in the first column 6 can be adjusted by adjusting the second liquid flow meter 2 to control the flow rate of the inlet water, the amount of bubbles in the first column 6 can be controlled by adjusting the gas flow meter 4, and the size of the bubbles can be controlled by adjusting the size of the hole of the bubble ejector 5.

In step S22, since the graphite surface is hydrophobic, the gangue mineral surface is hydrophilic, and the specific gravity of graphite is lower than that of the gangue mineral. Thus during the sorting process: on one hand, the surfaces of completely dissociated and partially dissociated graphite mineral particles have hydrophobic regions, and are easy to collide and adhere with rising bubbles after the surfaces of the graphite mineral particles react with a collecting agent to form a bubble-particle complex, and then the bubble-particle complex moves upwards to the surface of an ore pulp solution under the action of an upward buoyancy and a rising water flow supporting force, overflows into a second column body 7, and is discharged through an ore discharge port 9 to form first concentrate; on the other hand, the gangue mineral particles have hydrophilic surfaces, are not adhered to bubbles, have specific gravity higher than that of graphite, and easily sink to the bottom of the first column 6 under the action of self gravity, and are discharged from the underflow port 10 to form first tailings.

In a possible design, in step S22, the slurry uniformly mixed in the stirring barrel 11 passes through the nanobubble generating device before entering the feeding distributor 8 and then enters the feeding distributor 8, and the nanobubble-mineral particle complex generated after passing through the nanobubble generating device is combined with the rising bubbles in the first cylinder 6 to form larger bubbles, so that mineral particles with larger particle size (for example, mineral particles with particle size of 4-5 mm) can be sorted, and the applicability is wider; and because the nano bubbles can be used as a secondary collector, the using amount of the collector can be reduced by 15-25%; in addition, the nano-bubble generation mechanism is unique, and the consumption of the foaming agent is reduced by more than 20% compared with the conventional bubble; and as the nano bubbles stably grow on the surfaces of the mineral particles with good hydrophobicity in advance and collide and adhere with the rising microbubbles in the first column 6 under the action of the bridging force of the nano bubbles, the adhesion probability and stability of the useful mineral particles and the microbubbles can be obviously improved, and the separation recovery rate of the useful mineral coarse particles is increased.

Because the main component in the first tailings is coarse-grained gangue minerals, the first tailings have low graphite content, do not have sorting value, and reach the discharge standard, so the first tailings are directly discharged without flotation. The coarse-grained gangue minerals are easy to dehydrate, so that the first tailings can be directly used as building material sandstone aggregates after dehydration, and the economic benefit of enterprises is improved.

Specifically, the first regrinding and recleaning in step S3 includes 2 regrinding (grinding using a stirred mill) and 3 flotation, for example, the first regrinding and recleaning includes one regrinding (regrinding i), one concentration (concentration i), two regrinding (regrinding ii), two concentration (concentration ii), and three concentration (concentration iii) in this order.

Specifically, the collecting agent in the primary fine selection in the step S3 is kerosene with the use amount of 100-110 g/t, and the foaming agent is No. 2 oil with the use amount of 25-40 g/t.

Considering that the larger the scale, the better the performance and the higher the economic value, and the better the performance of the large scale graphite with the diameter of more than 0.150mm, the medium carbon normal mesh concentrate in the step S4 can be used as a final product.

In the above step S5, the second regrinding recleaning includes 1 regrinding and 1 sweep, for example, the second regrinding recleaning includes three regrinding (regrinding iii) and sweep performed in this order.

Specifically, the collecting agent in the sweeping process in the step S5 is kerosene with the dosage of 100g/t, and the foaming agent is No. 2 oil with the dosage of 40 g/t.

In the above step S5, the third regrinding includes 3 regrinding and 4 flotation, for example, the third regrinding includes four regrinding (regrinding iv), four concentration (concentration iv), five regrinding (regrinding v), five concentration (concentration v), six regrinding (regrinding vi), six concentration (concentration vi), and seven concentration (concentration vii) in this order.

Specifically, in the step S5, the collecting agent in the fourth-time concentration (concentration IV) is kerosene with the dosage of 40g/t, and the foaming agent is No. 2 oil with the dosage of 20-25 g/t; the collecting agent in the six-time concentration (concentration VI) is kerosene with the dosage of 40g/t, and the foaming agent is No. 2 oil with the dosage of 20 g/t.

Specifically, in step S5, in the third regrinding and recleaning process, the middlings after each concentration need to be returned to the last regrinding or concentration process for regrinding or flotation (for example, the second middlings generated by concentration iv are returned to regrinding iii, the third middlings generated by concentration v are returned to concentration iv, the fourth middlings generated by concentration vi are returned to concentration v, and the fifth middlings generated by concentration vii are returned to concentration vi), so that a closed cycle of the whole process is realized, and the yield is further improved.

In the step S5, the second tailings and the third tailings are directly discarded.

In step S5, the high-carbon negative concentrate can be used as another final product.

Comparative example 1

In this comparative example, the same raw ore as that of example 3 was used. The product under the sieve of-2.00 is subjected to primary coarse grinding by a rod mill (the grinding fineness is-0.150 mm and the fraction accounts for 72.14%), then primary rough concentration, primary scavenging and secondary regrinding of coarse concentrate are carried out for three times of fine concentration, the produced concentrate is subjected to 100-mesh classification, the fixed carbon content of the medium carbon and 100-mesh concentrate is 91.24%, the recovery rate is 21.45%, the medium carbon and 100-mesh concentrate and middling are combined and reground concentrate are combined together and then reground for three times of fine concentration, the fixed carbon content of the high carbon-100 concentrate is 96.17%, and the recovery rate is 61.22%.

The regrinding equipment is a stirring mill, only adjusting agent quicklime is added in a rough selection mode, the using amount is 1500g/t, the collecting agent is kerosene, the total using amount is 540g/t, the foaming agent is No. 2 oil, the total using amount is 250g/t, and the total time is 80 min.

Example 3

In a specific embodiment of the present invention, the beneficiation method provided in embodiment 2 is adopted, and the adopted raw ore is crystalline graphite ore in a certain place of Heilongjiang, the fixed carbon content of the raw ore is 5.4%, and the gangue minerals mainly comprise quartz (mineral content 40%), muscovite + biotite (mineral content 28%), diopside (mineral content 10%), calcite (mineral content 4%), pyrite (mineral content 4%), tremolite (mineral content 4%) and a small amount of opals, chlorite, apatite and limonite. The mineral graphite in the crystal graphite ore has thicker embedded granularity, most of the particles are between 0.150 and 2.00mm, and when the grinding fineness is-0.074 mm, the graphite monomer is dissociated to 90 to 96 percent. The high-pressure roller mill is adopted for closed-loop crushing, the size of a sieve hole of the vibrating sieve is controlled to be 2.00mm, and the granularity and the fixed carbon content of the product below the sieve are shown in table 1.

As can be seen from Table 1, the yield of +0.150mm fraction was 73.65% and the fixed carbon distribution was 81.21% in the product under the sieve of the vibrating screen.

TABLE 12.00 mm undersize product particle size distribution and fixed carbon content distribution

Grade/mm	Yield/%)	Negative cumulative/%)	Fixed carbon/%)	Distribution ratio/%
					+2.00	3.21	100.00	7.29	4.31
-2.00+1.00	16.23	96.79	7.07	21.13
					-1.00+0.600	12.33	80.56	6.31	14.33
-0.600+0.300	11.74	68.23	5.97	12.91
					-0.300+0.150	30.14	56.49	5.14	28.53
-0.150+0.074	14.21	26.35	4.36	11.41
					-0.074+0.045	6.70	12.14	3.66	4.51
-0.045	5.44	5.44	2.87	2.87
					Total up to	100.00	0	5.43	100.00

The beneficiation method comprises the following steps (specific process parameters are shown in the following table 2):

the method comprises the following steps: directly introducing minus 2.00mm undersize products into a stirring barrel, controlling the concentration of ore pulp to be 50%, and sequentially adding 1000g/t of quicklime, 60g/t of kerosene and 25g/t of No. 2 oil at intervals of 3min for size mixing;

step two: the water inlet pump 1 is opened to inject water into the first column body 6, the air pump 4 is used to inject air into the first column body 6, and the water and the air are uniformly mixed through the air-water mixing input pipe after passing through the bubble generator 3; when the mixed gas-water mixture passes through the bubble ejector 5, the area is suddenly reduced, the flow rate is sharply increased, the pressure in the fluid is suddenly reduced according to the Bernoulli principle, the gas dissolved in the water is separated out to generate a large number of micro bubbles, and meanwhile, upward water flow with a certain driving force is formed;

step three: after the water and bubble mixed liquid in the first column 6 stably overflows into the second column 7 and is discharged through the ore discharge port 9, the feeding distributor 8 is opened, the uniformly mixed ore pulp is discharged from the feeding distributor 8 into the first column 6 for separation, and the flow rate of the ore pulp is controlled by adjusting the first liquid flow meter; controlling the concentration of the ore pulp in the first cylinder 6 to be 35%, and sorting the ore pulp in the first cylinder 6, wherein first concentrate is discharged from an ore discharge port 9, first tailings are discharged from a bottom flow port 10, and the first concentrate is concentrated and then subjected to first regrinding and recleaning to obtain second concentrate and first middling; the first tailings are directly used as building material sandstone aggregate after dehydration.

Specifically, the fixed carbon content in the first tailings is 0.64%, and the yield of the first tailings is 31.05%.

Step four: grading the second concentrate by adopting a 100-mesh standard sieve to obtain medium-carbon positive concentrate and medium-carbon negative concentrate;

specifically, the fixed carbon content of the medium-carbon normal mesh concentrate is 92.07%, the recovery rate is 35.41%, and the medium-carbon normal mesh concentrate is directly used as a final product.

Step five: and after the first middling is concentrated, carrying out second regrinding and recleaning to obtain third concentrate and second tailings, combining the third concentrate with the medium-carbon negative concentrate, and carrying out third regrinding and recleaning to obtain high-carbon negative concentrate and third tailings.

In the fifth step, the second tailings and the third tailings are directly discarded.

In the fifth step, the fixed carbon content of the high-carbon negative concentrate is 96.58%, the recovery rate is 54.11%, and the high-carbon negative concentrate is used as another final product.

Specifically, the regrinding equipment is a stirring mill, the regulator is quicklime, the using amount is 1000g/t, the collector is kerosene, the total using amount is 350g/t, the foaming agent is No. 2 oil, and the total using amount is 150 g/t.

Compared with the comparative example 1, the recovery rate of the medium-carbon normal mesh concentrate is improved by about 65%, the total recovery rate is improved by about 8%, the dosage of the medicament is reduced by 33%, the total time is 58min, the total time is reduced by about 27.5% compared with the comparative example 1(80min), and the efficiency is obviously improved; and the first tailings can be used as building material sandstone aggregate to increase the economic benefit of enterprises.

Table 2 process parameters for example 3

Example 4

In a specific embodiment of the present invention, the beneficiation method provided in example 2 is used, the used raw ore is the same as that in example 3, and specific process parameters are shown in table 3 below.

The beneficiation method comprises the following steps:

the method comprises the following steps: directly introducing minus 2.00mm undersize products into a stirring barrel, controlling the concentration of ore pulp to be 75%, and sequentially adding 1000g/t of quicklime, 90g/t of kerosene and No. 2 oil (40g/t) at intervals of 3min for size mixing;

step three: after the water and bubble mixed liquid in the first column 6 stably overflows into the second column 7 and is discharged through the ore discharge port 9, the feeding distributor 8 is opened, the uniformly mixed ore pulp is discharged from the feeding distributor 8 into the first column 6 for separation, and the flow rate of the ore pulp is controlled by adjusting the first liquid flow meter; controlling the concentration of the pulp in the first cylinder 6 to be 60%, and sorting the pulp in the first cylinder 6, wherein first concentrate is discharged from a discharge port 9, first tailings are discharged from a bottom flow port 10, and the first concentrate is concentrated and then subjected to first regrinding and recleaning (the first regrinding and recleaning comprises 2 times of stirring and grinding and 3 times of fine concentration) to obtain second concentrate and first middling; the first tailings are directly used as building material sandstone aggregate after dehydration;

Specifically, the first regrinding and recleaning includes 2 times of stirring and grinding and 3 times of flotation.

Specifically, the fixed carbon content in the first tailings is 0.71%, and the yield of the first tailings is 29.63%.

Specifically, the fixed carbon content of the medium-carbon normal mesh concentrate is 91.27%, the recovery rate is 37.11%, and the medium-carbon normal mesh concentrate is directly used as a final product.

In the fifth step, the fixed carbon content of the high-carbon negative concentrate is 95.67%, the recovery rate is 53.44%, and the high-carbon negative concentrate is used as another final product.

Specifically, the regrinding equipment is a stirring mill, the regulator is quicklime, the using amount is 1000g/t, the collector is kerosene, the total using amount is 370g/t, the foaming agent is No. 2 oil, and the total using amount is 160 g/t.

Compared with the comparative example 1, the recovery rate of the medium-carbon normal-mesh concentrate is improved by about 73 percent, the total recovery rate is improved by about 9.5 percent, the dosage of the medicament is reduced by about 34.5 percent, the total time is 61min, the total time is reduced by about 24 percent compared with the comparative example 1(80min), and the efficiency is obviously improved; the first tailings can be used as building material sandstone aggregate to increase the economic benefit of enterprises.

Table 3 process parameters for example 4

As can be seen from the comparison of examples 3-4 and comparative example 1, the mineral separation method of the present application realizes the protection of graphite flakes during the primary grinding process by crushing the raw ore with the high-pressure roller mill; by arranging the coarse particle sorting equipment, most of gangue minerals can be discarded in advance, the cutting and chopping effects of gangue mineral particles with higher hardness on large graphite scales in the subsequent regrinding process can be effectively reduced, the large graphite scales are protected, the operation flow can be shortened, and the system processing capacity is improved; the first tailings serving as building material sandstone aggregate can increase the economic benefit of enterprises; the first concentrate can be accurately sorted and recovered by combining a regrinding and in-situ separation process, so that the sorting and recovery of the whole grain fraction of the graphite raw ore from coarse to fine are realized; meanwhile, the transportation path of the ore pulp particles in the system can be reduced, and the mutual abrasion of the ore pulp particles with the pipeline wall and the ore pulp particles in the transportation process is reduced; the beneficiation method for protecting the graphite flakes realizes the protection of the graphite flakes, improves the yield of the graphite flakes, and has the advantages of simple process, low cost, low energy consumption and no harm to the environment.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. A mineral processing system for protecting graphite flakes is characterized in that a high-pressure roller mill, a stirring barrel (11), coarse particle sorting equipment, a mineral grinding machine and a flotation machine are arranged along a mineral processing pipeline; the coarse particle sorting equipment comprises a first cylinder (6), a second cylinder (7) and an air-water mixing input device, wherein the first cylinder (6) and the second cylinder (7) are both of cylindrical structures, the second cylinder (7) is nested outside the upper end of the first cylinder (6), the upper end face of the second cylinder (7) is higher than the upper end face of the first cylinder (6), an ore discharge port (9) is formed in the side face of the second cylinder (7), and materials in the first cylinder (6) can overflow into the second cylinder (7) and are discharged through the ore discharge port (9); the number of the ore mills and the flotation machines is multiple.

2. The mineral processing system for protecting graphite flakes according to claim 1, wherein the bottom end surface of the second cylinder (7) is an inclined surface, and the included angle between the bottom end surface of the second cylinder (7) and the central axis of the first cylinder (6) is 20-40 °.

3. The mineral processing system for protecting graphite flakes according to claim 1, wherein a cover plate is arranged at the upper part of the second cylinder (7), a feed distributor (8) is arranged at the center of the cover plate of the second cylinder (7), and materials are input into the first cylinder (6) from the feed distributor (8).

4. The mineral processing system for protecting graphite flakes according to claim 3, wherein a conical structure is arranged at the lower part of the first cylinder (6), a bottom flow port (10) is arranged at the bottom of the conical structure, and the bottom flow port (10) is used for discharging tailings; an input port is arranged on the side edge of the upper part of the conical structure, the gas-water mixing input device comprises a gas-water mixing input pipe, the gas-water mixing input pipe is connected with a bubble ejector (5) arranged in a first cylinder (6) through the input port, a gas inlet pipe and a water inlet pipe are sequentially arranged on the gas-water mixing input pipe along the direction far away from the input port, and a bubble generator (3) is arranged at the joint of the gas inlet pipe and the gas-water mixing input pipe; the water inlet pipe is connected with the water inlet pump (1), and the air inlet pipe is connected with the air pump.

5. A beneficiation method for protecting graphite flakes is characterized in that the beneficiation system for protecting graphite flakes disclosed by claims 1-4 is adopted, and the beneficiation method comprises the following steps:

6. The beneficiation method for protecting graphite flakes according to claim 5, wherein the step S1 includes the steps of:

7. The mineral separation method for protecting graphite flakes according to claim 6, wherein the regulator in S12 is quicklime, the use amount of the regulator is 1000-1100 g/t, the use amount of the collector is kerosene, the use amount of the collector is 60-90 g/t, and the use amount of the foaming agent is No. 2 oil, and the use amount of the foaming agent is 25-40 g/t.

8. The beneficiation method for protecting graphite flakes according to claim 5, wherein the step S2 includes the steps of:

9. The beneficiation method for protecting graphite flakes according to claim 5, wherein the first regrinding and recleaning in the step S3 includes 2 regrinding and 3 flotation.

10. The mineral processing method for protecting graphite flakes according to claim 5, wherein in step S5, the second regrinding and recleaning includes 1 regrinding and 1 scavenging, and the third regrinding and recleaning includes 3 regrinding and 4 flotation.