1. The short-process preparation method of the high-purity spherical graphite is characterized by comprising the following steps of: the method comprises the following steps:

s1, carrying out crushing, ore grinding and flotation process flow on the graphite raw ore, wherein the number of the fine selection stages of the flotation is not more than three, and preparing graphite rough concentrate with the fixed carbon content of 70-85%;

s2, preparing a spherical graphite semi-finished product by using the rough graphite concentrate obtained in the S1;

and S3, putting the graphite semi-finished product obtained in the step S2 into an environment with the temperature of 2800-3000 ℃, and preserving the heat for 1-5 hours to obtain the spherical graphite with the fixed carbon content of not less than 99.9%.

2. The short-run process for preparing highly pure spherical graphite according to claim 1, wherein: in said S1, the equipment for crushing is a jaw crusher and a pair of roll crushers.

3. The short-run process for preparing highly pure spherical graphite according to claim 1, wherein: and in the S1, crushing the ore particles with the granularity of more than 2mm again until the granularity of the ore particles is not more than 2 mm.

4. The short-run process for preparing highly pure spherical graphite according to claim 1, wherein: and in the S1, the crushed ore particles with the granularity not more than 2mm enter an ore grinding process.

5. The short-run process for preparing highly pure spherical graphite according to claim 1, wherein: in the S1, after the ore grinding process, ore grains which account for 65-90% of all the ore grains and have the grain size not larger than 0.074mm are prepared.

6. The short-run process for preparing highly pure spherical graphite according to claim 1, wherein: in S2, the device for processing the rough graphite concentrate into spherical graphite semi-finished products is a mechanical impact crusher.

7. The short-run process for preparing highly pure spherical graphite according to claim 1, wherein: in the step S2, the process of processing the rough graphite concentrate into the spherical graphite semi-finished product comprises crushing and shaping, wherein the crushing times are not less than 6, and the shaping times are not less than 10.

Background

Graphite is a special non-metallic material, but has the excellent properties of metal, such as high temperature resistance, corrosion resistance, acid and alkali resistance, plasticity, lubricity, electric conduction and heat conduction, and the like, and is widely applied to departments of national defense, metallurgy, electricity, light industry, machinery and the like. China is a large natural graphite resource country, reserves, yield and exports all reside in the first place of the world, but the graphite industry in China is still at the international middle level as a whole.

The spherical graphite is a graphite product which is produced by taking high-quality high-carbon natural crystalline flake graphite as a raw material and modifying the surface of the graphite by adopting an advanced processing technology and has different fineness and is shaped like an ellipsoid. The high-purity spherical graphite has certain requirements on the appearance of a graphite product and the fixed carbon content of the graphite product, and the appearance and the purity of the product have certain influences on the performance of the product.

At present, the processing technology of high-purity spherical graphite commonly used at home and abroad is mostly as follows: graphite beneficiation enrichment, purification and spheroidization. The graphite beneficiation and enrichment method mainly comprises the steps of flotation, regrinding and recleaning, scrubbing, flotation, roasting and flotation to obtain graphite concentrate with the fixed carbon content of 90-95%, the most common beneficiation and enrichment method is the flotation, regrinding and recleaning method, but the process basically needs 5-7 stages of regrinding and recleaning to achieve the fixed carbon content of 90-95%, and the process is high in multiple times of ore grinding cost, long in flow and complex. Graphite purification mostly uses graphite concentrate with the fixed carbon content of more than 90 percent as a raw material, the purification method is mainly divided into a physical purification method and a chemical purification method, the physical purification method is mainly a high-temperature method, and the chemical purification method comprises an alkali-acid method, a hydrofluoric acid method and a chlorination roasting method. The process of sphericization is mostly through the processes of crushing, shaping and the like. In the conventional preparation method of high-purity spherical graphite at home and abroad, graphite concentrate with fixed carbon content of more than 90% is obtained by flotation, regrinding and recleaning, then the graphite concentrate is purified and finally spheroidization is carried out to obtain the high-purity spherical graphite, but the method has long and complicated mineral separation process, and the process of purifying and spheroidizing firstly is easy to cause waste of the purified graphite due to non-spheroidization, so that the method is not beneficial to energy conservation and consumption reduction, and therefore, a short-process preparation method of the high-purity spherical graphite is urgently needed.

Chinese invention patent "method and apparatus for preparing spherical graphite for power battery" (201811009725.1) discloses a method and apparatus for preparing spherical graphite for power battery, which uses natural crystalline flake graphite and earthy graphite with fixed carbon content above 90% as raw materials, and obtains high-purity graphite through ultramicro fine grinding and purification, but the method and apparatus have 2 defects: firstly, the requirement on the fixed carbon content of the graphite raw material is high, and the complexity of the mineral separation process flow and the mineral separation cost are increased; ② the purification method is acid purification, which not only easily generates toxic substances in the purification process, but also has high disposal cost of the final waste liquid, and is not beneficial to saving the environmental protection cost.

The Chinese invention patent 'a method and device for purifying graphite' (201210250373.5) discloses a method and device for purifying graphite, which selects graphite concentrate with carbon content more than or equal to 90% as raw material, and can obtain high-purity graphite under the condition that the purification temperature is as high as 4000-8500 ℃, although the method can obtain high-purity graphite, the requirement for the fixed carbon content of the raw material is high, and the complexity of the earlier-stage mineral separation process and the mineral separation cost are increased;

the invention patent of China (CN 108069422A) discloses a method for purifying graphite, which adopts graphite with the fixed carbon content of 95-96% as a raw material, continuously scans a graphite powder layer through a laser, and performs irradiation heating to gasify impurities in the graphite powder raw material, thereby finally obtaining high-purity graphite.

The invention patent of China (a purification method of microcrystalline graphite) (201610568679.3) discloses a purification method of microcrystalline graphite, which adopts microcrystalline graphite with carbon content of 70% -90% as raw material, and comprises the steps of placing the microcrystalline graphite in a high-pressure reactor, fully stirring, sealing, adjusting temperature and pressure to enable purified gas to enter a supercritical state, soaking in the reactor for 20-90 min, cooling to room temperature, relieving pressure to atmospheric pressure, separating microcrystalline graphite from waste liquid, washing with water, and drying to obtain high-purity microcrystalline graphite.

The Chinese patent 'a microcrystalline graphite purification preparation process' (201710293860.2) discloses a microcrystalline graphite purification preparation process, which adopts natural microcrystalline graphite with 80-90% of carbon content as a raw material, and can obtain high-purity graphite after strong acid heating purification, but the strong acid used in the method is hydrochloric acid, phosphoric acid, sulfuric acid, hydrofluoric acid and nitric acid, toxic substances are easily generated in the purification process, the waste liquid treatment cost is high, and the environment-friendly cost is not favorably saved.

Disclosure of Invention

The invention aims to provide a short-process preparation method of high-purity spherical graphite, which is used for solving the technical problems of high fixed carbon content of raw materials, complex process flow, high preparation cost and no environmental pollution in the prior art for preparing the high-purity spherical graphite.

In order to achieve the purpose, the invention adopts the following technical scheme:

the short-process preparation method of the high-purity spherical graphite is characterized by comprising the following steps of: the method comprises the following steps:

s1, carrying out crushing, ore grinding and flotation process flow on the graphite raw ore, wherein the number of the fine selection stages of the flotation is not more than three, and preparing graphite rough concentrate with the fixed carbon content of 70-85%;

s2, preparing a spherical graphite semi-finished product by using the rough graphite concentrate obtained in the S1;

and S3, putting the graphite semi-finished product obtained in the step S2 into an environment with the temperature of 2800-3000 ℃, and preserving the heat for 1-5 hours to obtain the spherical graphite with the fixed carbon content of not less than 99.9%.

Has the advantages that:

1. in the flotation process, the number of the fine selection sections is 0-3, the fixed carbon content of the graphite rough concentrate is not required to reach more than 90%, the fixed carbon content is only required to reach 70-85%, the mineral separation flow is shortened, the efficiency is higher, and therefore the mineral separation cost is saved.

2. Firstly, spheroidizing the graphite, and then purifying, wherein the spheroidizing rate of the graphite semi-finished product is 40-60%, the waste caused by non-spheroidizing of the graphite is avoided, the fixed carbon content of the finally obtained spherical graphite is not less than 99.9%, and the purity of the spherical graphite is high, so that the yield of the preparation method is high.

3. Compared with a chemical purification mode, the high-temperature purification mode has the advantages that the process is short, the requirement on the fixed carbon content of the graphite raw material is low, the ore dressing cost is low, harmful substances are not easily generated, the waste liquid treatment cost is not required to be paid out, the environmental protection cost is saved, and the environment protection is facilitated.

4. In the whole processing process, the limitation of production conditions is less, and the high requirements such as a supercritical state and the like do not need to be met, so that the cost of utilized equipment is low, and the equipment investment is low.

Further, in said S1, the equipment for crushing is a jaw crusher and a pair of roll crushers. Simple structure, easy manufacture and low equipment cost.

Further, in the step S1, the crushed ore with the particle size larger than 2mm is crushed again until the particle size of the ore is not larger than 2 mm. The crushing material mainly depends on extrusion or impact force, and the crushing energy utilization rate is higher than the grinding energy utilization rate, so that the energy utilization rate is high and the cost is reduced by adopting a method of more crushing and less grinding. In addition, in the crushing process, the large-granularity material generates more cracks, and the efficiency of the subsequent ore grinding process is improved.

Further, in the step S1, the crushed ore particles with the particle size not larger than 2mm enter an ore grinding process. The granularity of ore particles is suitable for entering an ore grinding process, the fault rate of ore grinding equipment is reduced, and the ore grinding efficiency is improved.

Further, in the step S1, after an ore grinding process, ore grains which account for 65-90% of all the ore grains and have a grain size of not more than 0.074mm are prepared. After the ore grinding process, the grinding fineness reaches-0.074 mm and accounts for 65-90%, and graphite ores in different ore regions reach the standard after grinding, so that the graphite ores have high fixed carbon content and recovery rate.

Further, in the step S1, a 0-3-stage short-flow flotation test is carried out on ore particles with the grinding fineness of-0.074 mm accounting for 65-90%, so that graphite rough concentrate with the fixed carbon content of 70-85% can be obtained, the ore dressing flow is shortened, the efficiency is higher, and the ore dressing cost is saved.

Further, in S2, the device for processing the rough graphite concentrate into spherical graphite semi-finished products is a mechanical impact crusher. Convenient ultramicro crushing, simple equipment and low equipment cost.

Further, in S2, the processing of the rough graphite concentrate into spherical graphite semi-finished product includes crushing and shaping, where the crushing time is not less than 6 times, and the shaping time is not less than 10 times. Crushing, shaping, crushing again according to the condition of the spherical graphite semi-finished product, and finally shaping to obtain the qualified spherical graphite semi-finished product, wherein the total times of crushing are more than 6 times, and the total times of shaping are more than 10 times. The balling rate of the graphite semi-finished product is improved, the yield of the spherical graphite is further improved, and the fixed carbon content, the sphericization degree and the tap density of the product are ensured to meet the requirement of making a lithium ion battery cathode material subsequently.

Drawings

FIG. 1 is a schematic diagram of a process for preparing high purity spheroidal graphite;

FIG. 2 is a flow chart for preparing high purity spheroidal graphite;

FIG. 3 is a SEM topography of medium carbon graphite rough concentrate;

FIG. 4 is an enlarged view of a portion of FIG. 3;

FIG. 5 is SEM topography of high purity spherical graphite.

In the figure: 1-jaw crusher, 2-double roll crusher, 3-feed hopper, 4-grader I, 5-grader II, 6-dust collector and 7-induced draft fan.

Detailed Description

As shown in fig. 1 to 5, the short-process preparation method of high-purity spherical graphite of the present invention comprises the following steps:

step one, crushing, screening and grinding. The mineral raw material is put into a jaw crusher 1 for coarse crushing, and the coarse crushed ore particles enter a double-roller crusher 2 for fine crushing, so that the structure is simple, the manufacture is easy, and the equipment cost is low. And in the screening process, the ore particles with the granularity of not more than 2mm enter the ore grinding flow, and the ore particles with the granularity of more than 2mm enter the double-roller crusher 2 again for fine crushing until the granularity of the ore particles is not more than 2 mm. Because the crushing materials mainly depend on extrusion or impact force, the crushing energy utilization rate is higher than the grinding energy utilization rate, the method of 'crushing more and grinding less' is adopted, the energy utilization rate is high, the cost is reduced, in addition, in the crushing process, the large-granularity materials generate more cracks, the efficiency of the subsequent ore grinding process is favorably improved, the ore grain granularity is suitable to enter the ore grinding process, the fault rate of ore grinding equipment is reduced, and the preparation efficiency is improved.

The ore particles with the particle size of not more than 0.074mm account for 65-90% of all the ore particles after grinding, and the graphite ore reaches the standard after grinding in different ore areas, so that the graphite ore has high fixed carbon content and recovery rate. Meanwhile, the prepared ore particles have small particle size, so that the time length of a flotation process and the number of fine selection stages can be shortened, and the ore dressing time and cost are saved.

And step two, flotation. And the flotation comprises roughing and concentration, wherein the ore particles after grinding are subjected to first-stage roughing, tailings are separated, the number of stages of concentration is selected according to the ore particles after roughing, the number of stages of concentration is not more than three, and finally, graphite rough concentrate with the fixed carbon content of 70-85% is obtained, wherein after grinding and roughing of raw ores, the rough concentrate enters the next process for regrinding and concentrating test, the middling returns to the previous process, and after two-stage regrinding and concentrating process, qualified medium-carbon graphite rough concentrate can be obtained. After flotation, the fixed carbon content of the graphite rough concentrate is not required to reach more than 90%, and only the fixed carbon content is required to reach 70-85%, so that the beneficiation flow is shortened, the efficiency is higher, and the beneficiation cost is saved.

And step three, spheroidizing. The graphite rough concentrate is put into a mechanical impact type crusher for spheroidization processing, so that superfine crushing is facilitated, the equipment is simple, and the equipment cost is low. Mechanical impact rubbing crusher is high-speed mechanical impact rubbing crusher, high-speed mechanical impact rubbing crusher still includes feeder hopper 3, the grader, dust arrester 6 and draught fan 7, the grader includes grader one 4 and grader two 5, feeder hopper 3, grader one 4, grader two 5, dust arrester 6 and draught fan 7 link to each other in proper order, output in the first 4 of the hierarchical flow of spherical graphite semi-manufactured goods, output in the second 5 of the grader is followed through hierarchical two flows to fine powder behind the whirlwind, output in the fine powder is followed from dust arrester 6 through collection dirt flow behind the collection dirt. The spheroidization processing flow comprises the steps of crushing and shaping, wherein crushing is carried out firstly, shaping is carried out again, crushing is carried out again according to the condition of a spheroidized graphite semi-finished product, and finally shaping is finished to obtain a qualified spheroidized graphite semi-finished product, the total times of crushing are more than 6 times, the total times of shaping are more than 10 times, the spheroidization rate of the graphite semi-finished product is high, the spheroidization rate is 40-60%, so that the yield of the spheroidized graphite is improved, and the fixed carbon content, the spheroidization degree and the tap density of the product meet the requirements of making a lithium ion battery cathode material subsequently.

And step four, purifying. And (3) purifying the spherical graphite semi-finished product in a high-temperature furnace by adopting a high-temperature purification mode, wherein the purification temperature is 2800-3000 ℃, and the maintaining time is more than 1 hour and less than 5 hours. Compared with a chemical purification mode, the high-temperature purification mode has the advantages that the process is short, the requirement on the fixed carbon content of the graphite raw material is low, the ore dressing cost is low, harmful substances are not easily generated, the waste liquid treatment cost is not required to be paid out, the environmental protection cost is saved, and the environment protection is facilitated.

And step five, discharging. Finally obtaining the high-purity spherical graphite product from the high-temperature furnace, wherein the fixed carbon content of the spherical graphite is not less than 99.9%.

Firstly, spheroidizing the graphite, and then purifying, wherein the spheroidizing rate of the graphite semi-finished product is 40-60%, the waste caused by non-spheroidizing of the graphite is avoided, the fixed carbon content of the finally obtained spherical graphite is not less than 99.9%, and the purity of the spherical graphite is high, so that the yield of the preparation method is high. In addition, in the whole processing process, the limitation of production conditions is less, and the high requirements such as a supercritical state and the like do not need to be met, so that the cost of utilized equipment is low, and the equipment investment is low.

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.

The chemical composition of the graphite raw ore used in the examples is shown in table 1.

Table 1 chemical composition analysis table of raw graphite ore in example

Element classes	Fixed carbon	MnO	Na2O	P2O5	MnO	Na2O
							Content/%	8.95	0.35	1.57	0.21	0.35	1.57
Element classes	Na2O	MnO	P2O5	TiO2	SiO2	P2O5
							Content/%	1.57	0.35	0.21	0.98	59.22	0.21

Experimental example 1

Crushing and grinding graphite raw ore until ore particles with the diameter not larger than 0.074mm account for 85%, and preparing graphite rough concentrate by adopting a flotation process of primary roughing and secondary concentration, wherein the fixed carbon content of the graphite rough concentrate is 80.32%; crushing the graphite rough concentrate for 6 times and shaping for 10 times by using a mechanical impact crusher to obtain two specifications of large balls (16-18 mu m) and small balls (8-11 mu m), wherein the balling rate of the spherical graphite product is 60.00%; and adding the obtained spherical graphite semi-finished product into a high-temperature furnace, setting the temperature at 2800 ℃, and maintaining for 3 hours to finally obtain the spherical graphite with the fixed carbon content of 99.96 percent.

Experimental example 2

Crushing and grinding graphite raw ore until ore particles with the diameter of not more than 0.074mm account for 65%, and preparing graphite rough concentrate by adopting a flotation process of one-stage roughing and three-stage concentration, wherein the fixed carbon content of the graphite rough concentrate is 70.19%; crushing the graphite rough concentrate for 8 times and shaping for 10 times by using a mechanical impact crusher to obtain two specifications of large balls (16-18 mu m) and small balls (8-11 mu m), wherein the balling rate of the spherical graphite product is 48.64%; and adding the obtained spherical graphite semi-finished product into a high-temperature furnace, setting the temperature at 3000 ℃, and maintaining for 3 hours to finally obtain the spherical graphite with the fixed carbon content of 99.91 percent.

Experimental example 3

Crushing and grinding graphite raw ore until ore particles with the diameter not larger than 0.074mm account for 80%, and preparing graphite rough concentrate by adopting a flotation process of only one-stage roughing, wherein the fixed carbon content of the graphite rough concentrate is 70%; crushing the rough graphite concentrate for 10 times and shaping for 13 times by using a mechanical impact crusher to obtain two specifications of large balls (16-18 mu m) and small balls (8-11 mu m), wherein the balling rate of the spherical graphite product is 40.00%; and adding the obtained spherical graphite semi-finished product into a high-temperature furnace, setting the temperature at 3000 ℃, and maintaining for 3 hours to finally obtain the spherical graphite with the fixed carbon content of 99.93 percent.

Experimental example 4

Crushing and grinding graphite raw ore until ore particles with the diameter not larger than 0.074mm account for 90%, and preparing graphite rough concentrate by adopting a flotation process of one-stage roughing and three-stage concentration, wherein the fixed carbon content of the graphite rough concentrate is 85%; crushing the graphite rough concentrate for 6 times and shaping for 10 times by using a mechanical impact crusher to obtain two specifications of large balls (16-18 mu m) and small balls (8-11 mu m), wherein the balling rate of the spherical graphite product is 60.00%; and adding the obtained spherical graphite semi-finished product into a high-temperature furnace, setting the temperature at 3000 ℃, and maintaining for 3 hours to finally obtain the spherical graphite with the fixed carbon content of 99.99 percent.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.