阅读说明：本技术 一种制备锂离子电池负极材料的无烟煤基微晶石墨提纯方法 (Purification method of smokeless coal-based microcrystalline graphite for preparing lithium ion battery negative electrode material ) 是由 杨森 孙凯 董伟 夏英凯 于 2019-12-04 设计创作，主要内容包括：本发明公开了一种制备锂离子电池负极材料的无烟煤基微晶石墨提纯方法,包括：无烟煤基微晶石墨经过两段颚式破碎、一段反击式锤破、卧式搅拌磨-干法旋风分级制备粒度小于10μm的超细粉体,同时采用两种抑制剂、自制乳化煤油捕收剂和2#油起泡剂,进行一次粗选和五次精选,以收集固定碳含量不低于90.0％的精矿作为浮选矿；在60～90℃的恒温水浴锅中,将浮选矿放入一种或多种酸的混合溶液中,搅拌,超声30～60min,混合物水洗至pH＝7,再抽滤,110℃烘干2～5h,提纯后微晶石墨固定碳含量不低于99.0％。本发明制备的无烟煤基微晶石墨作为锂离子电池负极材料,首次可逆容量不低于400mAh/g,高于石墨的理论容量,循环100次后,可逆容量保持率不低于90.0％,电性能比提纯前微晶石墨显著提高。(The invention discloses a purification method of smokeless coal-based microcrystalline graphite for preparing a lithium ion battery cathode material, which comprises the following steps: the method comprises the following steps of preparing ultrafine powder with the granularity of less than 10 mu m by two-section jaw crushing, one-section impact hammer crushing, horizontal stirring mill-dry cyclone classification, and simultaneously performing primary roughing and five-time fine separation by adopting two inhibitors, a self-made emulsified kerosene collecting agent and a 2# oil foaming agent to collect concentrate with the fixed carbon content of not less than 90.0% as flotation separation; putting the flotation ore into a mixed solution of one or more acids in a constant-temperature water bath kettle at the temperature of 60-90 ℃, stirring, carrying out ultrasonic treatment for 30-60 min, washing the mixture until the pH value is 7, carrying out suction filtration, drying at the temperature of 110 ℃ for 2-5 h, and purifying to obtain the microcrystalline graphite with the fixed carbon content of not less than 99.0%. The prepared smokeless coal-based microcrystalline graphite is used as a lithium ion battery cathode material, the first reversible capacity is not lower than 400mAh/g and is higher than the theoretical capacity of graphite, after 100 times of circulation, the reversible capacity retention rate is not lower than 90.0%, and the electrical property is obviously improved compared with that of microcrystalline graphite before purification.)

1. A purification method of smokeless coal-based microcrystalline graphite for preparing a lithium ion battery negative electrode material is characterized by comprising the following steps:

(1) taking natural smokeless coal-based microcrystalline graphite as a raw material, sequentially crushing by a jaw crusher of 50mm and a jaw crusher of 10mm, hammering by a counterattack hammer crusher of 1mm, crushing the microcrystalline graphite of less than 1mm by a dry method by using alumina balls of a horizontal stirring mill, performing cyclone classification, performing ball milling on the material with the particle size of more than 10 mu m again, and taking the material with the particle size of less than 10 mu m as a flotation feed;

(2) firstly adding 400-600 g/t of two inhibitor sodium silicate and 100-300 g/t of sodium carboxymethylcellulose, stirring for 3-5 min, mixing an emulsifier MOA-3B and kerosene at a mass ratio of 1: 9-2: 8, mixing for 3-5 min at a high speed of 800-1000 r/min in a high-speed stirrer to serve as a collecting agent, wherein the adding amount of the collecting agent is 1000-3000 g/t, stirring for 1-2 min, adding 200-400 g/t of foaming agent 2 oil, stirring for 1min, aerating, blowing at an air flow rate of 150-250L/h, scraping for 5min, collecting concentrate, drying at 60 ℃ for 6-8 h, adding the concentrate into a flotation tank, adding water, performing 1 st concentration, scraping for collecting concentrate, repeating the 1 st concentration process for the 2 nd concentration, supplementing 100-200 g/t of inhibitor sodium silicate, 50-100 g/t of sodium carboxymethylcellulose, 500-1000 g/t of collector emulsified kerosene and 100-200 g/t of foaming agent 2# oil during the 3 rd concentration, repeating the 2 nd concentration process for the 4 th and 5 th concentrations, and finally collecting concentrate with the fixed carbon content not lower than 90.0% as flotation separation;

(3) placing the flotation ore into HF, HCl and H in a constant-temperature water bath kettle at the temperature of 60-90 DEG C₂SiF₆、HNO₃In the mixed solution of one or more acids, the mass ratio of the mixed acid volume to the microcrystalline graphite is 2: 1-4: 1, and the HF volume accounts forStirring for 3-5 h when the volume percentage of the mixed acid is 50% and the volume percentages of other acids are equal, then performing ultrasonic treatment for 30-60 min at room temperature, washing the mixture until the pH value is 7, performing suction filtration, drying for 2-5 h in a forced air drying oven at 110 ℃, and purifying to obtain the high-purity smokeless coal-based microcrystalline graphite with the fixed carbon content of not less than 99.0%.

2. The purification method of the smokeless coal-based microcrystalline graphite for preparing the lithium ion battery negative electrode material according to claim 1, wherein the prepared smokeless coal-based microcrystalline graphite is applied to the lithium ion battery negative electrode material.

Technical Field

The invention belongs to a purification technology of high-purity smokeless coal-based microcrystalline graphite, and the purified microcrystalline graphite is applied to a lithium ion battery cathode material, in particular to a mechanical crushing, emulsified kerosene flotation and acid washing process and application of the material in new energy materials, which are cross technologies in the fields of physics, chemistry and chemical power supplies.

Background

The smokeless coal-based microcrystalline graphite is low in crystallinity and high in ore grade, ultrafine powder prepared by two sections of jaws, one section of counterattack hammer breakage and horizontal stirring mill-dry cyclone classification is isotropic, microcrystalline graphite grains are fine and serve as a lithium ion battery cathode material, the theoretical specific capacity is higher than that of crystalline flake graphite, but the impurity content of natural microcrystalline graphite is high, so that the structural stability and the electrical property of the lithium ion battery are reduced, the purity of the lithium ion battery is improved through deep processing of the microcrystalline graphite, and the problem that the structure of the lithium ion battery is urgently required to be solved is solved.

The purification process of the microcrystalline graphite mainly comprises five processes, namely the recovery rate of the graphite by a chloride roasting method is highest, but the operation controllability is poor, chlorine is toxic, the purity of the graphite by a high-temperature method is highest, but the requirement on raw materials is high, equipment is expensive, the investment is huge, the purity of the graphite by an alkaline-acid method is higher, but the equipment is seriously corroded, part of impurities in a flotation method are impregnated in the graphite in an extremely fine particle shape and cannot be completely dissociated by monomers, so that the purity of the obtained graphite is not high, the purification effect of the hydrofluoric acid method is better, but the impurities are easily combined with oxide impurities in the graphite to generate fluoride precipitates, and the fixed.

Disclosure of Invention

The invention aims to provide a low-cost and high-efficiency purification method of smokeless coal-based microcrystalline graphite for preparing a lithium ion battery cathode material by an emulsified kerosene flotation-mixed acid method, and the smokeless coal-based microcrystalline graphite which is subjected to ultrafine grinding and purification is applied to the lithium ion battery cathode material.

In order to achieve the purpose, the invention is realized by the following technical scheme: a purification method of smokeless coal-based microcrystalline graphite for preparing a lithium ion battery negative electrode material comprises the following steps:

(1) taking natural smokeless coal-based microcrystalline graphite as a raw material, sequentially crushing by a jaw crusher of 50mm and a jaw crusher of 10mm, hammering by a counterattack hammer crusher of 1mm, crushing the microcrystalline graphite of less than 1mm by a dry method by using alumina balls of a horizontal stirring mill, performing cyclone classification, performing ball milling on the material with the particle size of more than 10 mu m again, and taking the material with the particle size of less than 10 mu m as a flotation feed;

(2) firstly adding 400-600 g/t of two inhibitor sodium silicate and 100-300 g/t of sodium carboxymethylcellulose, stirring for 3-5 min, mixing an emulsifier MOA-3B and kerosene at a mass ratio of 1: 9-2: 8, mixing for 3-5 min at a high speed of 800-1000 r/min in a high-speed stirrer to serve as a collecting agent, wherein the adding amount of the collecting agent is 1000-3000 g/t, stirring for 1-2 min, adding 200-400 g/t of foaming agent 2 oil, stirring for 1min, aerating, blowing at an air flow rate of 150-250L/h, scraping for 5min, collecting concentrate, drying at 60 ℃ for 6-8 h, adding the concentrate into a flotation tank, adding water, performing 1 st concentration, scraping for collecting concentrate, repeating the 1 st concentration process for the 2 nd concentration, supplementing 100-200 g/t of inhibitor sodium silicate, 50-100 g/t of sodium carboxymethylcellulose, 500-1000 g/t of collector emulsified kerosene and 100-200 g/t of foaming agent 2# oil during the 3 rd concentration, repeating the 2 nd concentration process for the 4 th and 5 th concentrations, and finally collecting the concentrate with the fixed carbon content not lower than 90.0% as flotation;

(3) placing the flotation ore into HF, HCl and H in a constant-temperature water bath kettle at the temperature of 60-90 DEG C₂SiF₆、HNO₃In the mixed solution of one or more acids, the mass ratio of the volume of the mixed acid to the microcrystalline graphite is 2: 1-4: 1, the volume of HF accounts for 50% of the volume of the mixed acid, the volume fractions of other acids are equal, stirring is carried out for 3-5 h, then ultrasonic treatment is carried out for 30-60 min at room temperature, the mixture is washed until the pH value is 7, then suction filtration is carried out, a forced air drying oven is carried out at 110 ℃ for drying for 2-5 h, and the fixed carbon content of the purified high-purity smokeless coal-based microcrystalline graphite is not lower than 99.9%.

Compared with the prior art, the invention has the following technical advantages:

the natural smokeless coal-based microcrystalline graphite ore has high grade and low crystallinity, ultrafine powder with the granularity less than 10 mu m is prepared by an ultrafine grinding process and is used as a flotation feed material, the flotation feed material is more fully combined with mixed acid, the purification effect of the microcrystalline graphite is improved, the natural smokeless coal-based microcrystalline graphite ore is applied to a lithium ion battery cathode material, and as the grains are fine and isotropic, lithium ion diffusion channels are increased, and the reversible lithium storage capacity is higher than that of crystalline flake graphite.

After the smokeless coal-based microcrystalline graphite is subjected to ultrafine grinding, a flotation process is utilized to remove part of impurities, two inhibitors, namely sodium silicate and sodium carboxymethylcellulose are adopted at the same time, the effect is more ideal than that of one inhibitor, and the floating of impurity minerals can be effectively prevented; under the action of an emulsifier, the kerosene is self-prepared into emulsion, the stabilization time is longer, the dynamic viscosity is obviously reduced, the dispersion performance of kerosene drops in a water phase is improved, microcrystalline graphite can be more effectively collected, and the condition that the gangue such as kaolinite group minerals or micro-fine particle quartz on the surfaces of mineral particles are adsorbed together is prevented.

After flotation, the microcrystalline graphite is subjected to first-step impurity removal by using strong acid HF, but HF and oxides of calcium, magnesium, iron and the like undergo chemical reaction to generate fluoride precipitate, and the fluoride precipitate is mixed in the microcrystalline graphite, so that HCl and H are added₂SiF₆、HNO₃The one or more acids react with the fluoride precipitates to generate soluble salt compounds, and the effect of preparing the high-purity smokeless coal-based microcrystalline graphite is achieved through water washing and suction filtration.

The prepared smokeless coal-based microcrystalline graphite is used as a lithium ion battery cathode material, the first reversible capacity is not lower than 400mAh/g and is higher than the theoretical capacity of graphite, after 100 times of circulation, the reversible capacity retention rate is not lower than 90.0%, and the electrical property is obviously improved compared with that of microcrystalline graphite before purification. The invention not only improves the purity of the smokeless coal-based natural microcrystalline graphite, but also uses the mineral material as the negative electrode material of the new energy lithium ion battery, increases the functionality of the material and improves the application potential of the material.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly described below.

FIG. 1 is a flow chart of the present invention using mechanical crushing and emulsified kerosene flotation process;

FIG. 2 is a flow chart of the mixed acid purification process of the present invention.

Detailed Description

Other aspects, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which form a part of this specification, and which illustrate, by way of example, the principles of the invention.