CN-122012915-A - Lithium extraction method for lithium-containing waste material

CN122012915ACN 122012915 ACN122012915 ACN 122012915ACN-122012915-A

Abstract

The application is suitable for the technical field of lithium resource recovery, and provides a lithium extraction method of a lithium-containing waste material, which comprises the following steps of S1, crushing and grinding the waste material, mixing the waste material with concentrated sulfuric acid in proportion, pouring the mixture into a rotary kiln, and roasting at a high temperature, S2, controlling the rotating speed of the rotary kiln in the roasting process, specifically comprising S21, constructing a waste material state evaluation model according to the granularity of the waste material, the moisture content of the waste material, the acid-material ratio and the temperature uniformity of the mixed material, outputting a waste material state index, and S22, constructing a roasting state evaluation model according to the heating rate conformity, the roasting temperature stability and the kiln tail oxygen content stability, and outputting a roasting state index. The application solves the problem of insufficient cooperative sensing and comprehensive evaluation of multiple parameters in the traditional roasting process control by providing a specific roasting state evaluation model, and realizes quantification and fine management of the roasting process state.

Inventors

WANG RAN
CHEN XUEDONG
LI WEIGUANG

Assignees

新疆礼信新材料有限公司

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (8)

1. The lithium extraction method of the lithium-containing waste material is characterized by comprising the following steps of: S1, crushing and grinding waste materials, mixing the crushed waste materials with concentrated sulfuric acid in proportion, and pouring the mixture into a rotary kiln for high-temperature roasting; S2, controlling the rotation speed of the rotary kiln in the roasting process, and specifically comprising the following steps: s21, constructing a waste material state evaluation model according to the granularity of the waste material, the moisture content of the waste material, the acid-material ratio and the temperature uniformity of the mixed material, and outputting a waste material state index; S22, constructing a roasting state evaluation model according to the temperature rising rate conformity, the roasting temperature stability and the kiln tail oxygen content stability, and outputting a roasting state index; S23, constructing a roasting effect evaluation model according to the waste material state index, the roasting state index and the feeding rate stability, and outputting the roasting effect index; S24, constructing an intelligent control model of the rotary kiln rotating speed according to the current rotating speed of the rotary kiln, the roasting effect index, the real-time torque of a main kiln motor and the retention time of target materials, and outputting the target rotating speed of the rotary kiln so as to correct the current rotating speed of the rotary kiln; and S3, leaching the roasted clinker by water, and carrying out solid-liquid separation to obtain a leaching solution rich in lithium.
2. The method for extracting lithium from lithium-containing waste materials according to claim 1, wherein the waste material particle size, the waste material moisture content and the acid-material ratio are sequentially substituted into a maximum-minimum normalization formula for processing, and a waste material particle size index, a waste material moisture content index and an acid-material ratio index are sequentially generated, wherein a quotient is obtained by dividing a standard deviation of the material temperature in the kiln after mixing by a set maximum temperature range, and then the quotient is subtracted by 1, and a temperature uniformity index is obtained, wherein in the waste material state evaluation model: The deviation of the acid-material ratio index and the optimal acid-material ratio index is squared and multiplied by a set shape coefficient to obtain a result, and the acid-material ratio index obtained by subtracting the result from 1; And respectively giving corresponding set weight coefficients to the moisture index, the acid-material ratio index and the temperature uniformity index obtained after the treatment of the (1-moisture content index) of the waste material, and then carrying out weighted summation to obtain the waste material state index.
3. The method for extracting lithium from lithium-containing waste materials according to claim 1, wherein the deviation value of the actual heating rate and the set heating rate is taken as an absolute value, the absolute value is divided by the set heating rate to obtain a quotient value, the quotient value is subtracted by 1 to obtain heating rate conformity, the temperature stability is equal to the negative square power of a natural constant e, wherein the exponent part is obtained by dividing the quotient value of a temperature standard deviation by (the product of a target roasting temperature and an allowable fluctuation coefficient), and then squaring the quotient value, the deviation value of the actual kiln tail oxygen content and the set optimal kiln tail oxygen content is taken as an absolute value, the quotient value is obtained by dividing the absolute value by the set optimal kiln tail oxygen content, the quotient value is subtracted by 1 to obtain kiln tail oxygen content stability, and the roasting state evaluation model is as follows: The roasting state index is obtained by multiplying the following two parts: the first part is the geometric average value of the temperature rising rate conformity degree, the roasting temperature stability and the kiln tail oxygen content stability; the second part is an adjustment coefficient, the value of which is equal to 1 minus (the temperature rising rate accords with the third of the sum of squares of deviations of the temperature rising rate, the roasting temperature and the kiln tail oxygen content, which are respectively from an ideal value of 1).
4. The method for extracting lithium from lithium-containing waste materials according to claim 1, wherein in the roasting effect evaluation model: The firing effort index is derived from the product of the waste material state index, the firing state index, and the feed rate stability index divided by a term adjusted based on the deviation of the product from 1.
5. The method for extracting lithium from lithium-containing waste materials according to claim 4, wherein the feeding rate stability index is calculated by: The feed rate stability index is obtained by taking the natural constant e as a base and taking the index as negative (the ratio of the standard deviation of the feed rate to the target feed rate multiplied by a set coefficient of sensitivity).
6. The lithium extraction method of the lithium-containing waste material according to claim 1, wherein the deviation value of the real-time torque of the kiln main motor and the set optimal torque is divided by the set torque allowable range after taking the absolute value to obtain the torque deviation index, wherein the intelligent control model of the rotary kiln rotating speed comprises the following steps: The calculation of the target rotational speed is based on the product of the kiln effective length divided by the target residence time and the set rotational speed coefficient, multiplied by two correction factors: The first term is a forward correction factor reflecting the degree to which the firing effect index is higher or lower than the optimum firing index; The second term is a negative correction factor reflecting the magnitude of the torque deviation index.
7. The method for extracting lithium from lithium-containing waste materials according to claim 1, further comprising a step S25 of controlling the material retention time during the roasting process, specifically comprising: and constructing a roasting residence time dynamic setting model according to the waste material state index, the roasting effect index and the real-time temperature of the material before kiln discharge, outputting the corrected target material residence time, feeding the corrected target material residence time back to the rotary kiln rotating speed intelligent control model, and correcting in the next control period.
8. The method for extracting lithium from lithium-containing waste materials according to claim 7, wherein the roasting residence time is dynamically set in a model: The new target residence time is obtained by multiplying the basic residence time by an influence factor reflecting the deviation of the kiln outlet temperature index and the optimal kiln outlet temperature index and a forward influence factor reflecting the lower degree of the roasting effect index, and finally the new target residence time is limited between the set maximum residence time and the set minimum residence time.

Description

Lithium extraction method for lithium-containing waste material Technical Field The invention belongs to the technical field of lithium resource recovery, and particularly relates to a lithium extraction method for lithium-containing waste materials. Background In the current industrial practice, the sulfuric acid roasting process is widely adopted because of higher lithium conversion efficiency, and the process is characterized in that crushed and ground waste materials are mixed with concentrated sulfuric acid, high-temperature reaction is carried out in a rotary kiln, so that insoluble lithium compounds are converted into soluble lithium sulfate, and finally, lithium resources are obtained through water leaching and solid-liquid separation. However, this process exposes systematic drawbacks in large-scale applications: Firstly, the physical and chemical characteristics of lithium-containing waste materials are obviously uncertain, the particle size distribution range of waste materials in different batches is wide, the fluctuation of the moisture content is severe, the impurity components are complex and changeable, and the acid-material ratio is difficult to match accurately. In the prior art, a fixed proportioning scheme is adopted, random disturbance of material characteristics cannot be dynamically responded, so that a reaction system in a kiln is unbalanced, and an underburn phenomenon of insufficient reaction or an overdose state of excessive decomposition occurs in a local area, so that the leaching efficiency of lithium is directly weakened. Secondly, the roasting process of the rotary kiln involves deep coupling of thermodynamics, hydrodynamics and chemical reaction dynamics, and key parameters such as material residence time, kiln body rotating speed, temperature gradient distribution, kiln tail oxygen content and the like are mutually restricted. The traditional control strategy only focuses on the threshold adjustment of a single parameter, lacks comprehensive quantitative evaluation of the material state evolution process and the roasting atmosphere stability, and operators rely on subjective experience to perform rough intervention, so that the dynamic balance of a reaction system is difficult to maintain, and energy waste and product quality fluctuation are caused. The technical bottlenecks limit the stability and the economy of the lithium extraction process of the lithium-containing waste materials, and an innovative method system capable of intelligently sensing multidimensional state parameters, dynamically evaluating roasting effects and optimizing operation strategies in real time is needed to be constructed. In view of the above, there is a need in the art for improvements. Disclosure of Invention The embodiment of the invention aims to provide a lithium extraction method for lithium-containing waste materials, which aims to solve the problem that the traditional control strategy only focuses on threshold adjustment of a single parameter and lacks comprehensive quantitative evaluation on the material state evolution process and the roasting atmosphere stability. The invention is realized in such a way that a lithium extraction method of lithium-containing waste materials comprises the following steps: S1, crushing and grinding waste materials, mixing the crushed waste materials with concentrated sulfuric acid in proportion, and pouring the mixture into a rotary kiln for high-temperature roasting; S2, controlling the rotation speed of the rotary kiln in the roasting process, and specifically comprising the following steps: s21, constructing a waste material state evaluation model according to the granularity of the waste material, the moisture content of the waste material, the acid-material ratio and the temperature uniformity of the mixed material, and outputting a waste material state index; S22, constructing a roasting state evaluation model according to the temperature rising rate conformity, the roasting temperature stability and the kiln tail oxygen content stability, and outputting a roasting state index; S23, constructing a roasting effect evaluation model according to the waste material state index, the roasting state index and the feeding rate stability, and outputting the roasting effect index; S24, constructing an intelligent control model of the rotary kiln rotating speed according to the current rotating speed of the rotary kiln, the roasting effect index, the real-time torque of a main kiln motor and the retention time of target materials, and outputting the target rotating speed of the rotary kiln so as to correct the current rotating speed of the rotary kiln; and S3, leaching the roasted clinker by water, and carrying out solid-liquid separation to obtain a leaching solution rich in lithium. According to the further technical scheme, the granularity of the waste materials, the moisture content of the waste materials and the acid-material ratio are sequentially subst