阅读说明：本技术 一种采用曝气控制反应温度的连续酸浸系统及方法 (Continuous acid leaching system and method adopting aeration to control reaction temperature ) 是由 赵志安 闫修林 易飞鸿 关桦 朱振峰 杨徐烽 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种采用曝气控制反应温度的连续酸浸系统及方法,包括,浆料制作、一次酸浸、二次酸浸、高酸酸浸和压滤；其中,浆料为镍钴锰酸锂粉料、水与酸液混合料；所述一次酸浸在一次酸浸反应釜内进行,通过添加硫酸、双氧水,酸浸出镍钴锰锂；所述二次酸浸在二次酸浸反应釜进行,通过添加硫酸、双氧水,酸浸出镍钴锰锂。本发明提出的方法能在保证酸浸率的条件下显著提高产能,同时还降低了纯碱的使用量并减轻后续处理负担,在同等设备情况下,本发明连续酸浸的产量是间歇酸浸法的2.5倍以上；本发明连续酸浸出过程中的浸出效率为90％以上。(The invention discloses a continuous acid leaching system and a method for controlling reaction temperature by adopting aeration, which comprises slurry preparation, primary acid leaching, secondary acid leaching, high-acid leaching and filter pressing; wherein the slurry is a mixture of nickel cobalt lithium manganate powder, water and acid liquor; the primary acid leaching is carried out in a primary acid leaching reaction kettle, and the nickel, cobalt, manganese and lithium are leached by acid leaching by adding sulfuric acid and hydrogen peroxide; and soaking the secondary acid in a secondary acid leaching reaction kettle, and adding sulfuric acid and hydrogen peroxide to perform acid leaching on the nickel, cobalt, manganese and lithium. The method provided by the invention can obviously improve the productivity under the condition of ensuring the acid leaching rate, simultaneously reduces the usage amount of the soda ash and lightens the subsequent processing burden, and under the condition of the same equipment, the yield of continuous acid leaching is more than 2.5 times of that of an intermittent acid leaching method; the leaching efficiency in the continuous acid leaching process is more than 90%.)

1. A continuous acid leaching method adopting aeration to control reaction temperature is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

preparing slurry, primary acid leaching, secondary acid leaching, high-acid leaching and filter pressing; wherein the content of the first and second substances,

the slurry is a mixture of nickel cobalt lithium manganate powder, water and acid liquor;

the primary acid leaching is carried out in a primary acid leaching reaction kettle, and the nickel, cobalt, manganese and lithium are leached by acid leaching by adding sulfuric acid and hydrogen peroxide;

soaking the secondary acid in a secondary acid leaching reaction kettle, and leaching nickel, cobalt, manganese and lithium by adding sulfuric acid and hydrogen peroxide;

the primary acid leaching and the secondary acid leaching control the reaction temperature in the reaction kettle by an aeration method, and the primary acid leaching reaction kettle is communicated with the secondary acid leaching reaction kettle;

the primary acid leaching and the secondary acid leaching are continuous acid leaching, continuous feeding and continuous discharging.

2. The continuous acid leaching method using aeration to control the reaction temperature according to claim 1, wherein: the preparation of the slurry comprises the steps of fully stirring the high-acid leaching solution, the nickel cobalt lithium manganate powder and water to prepare a mixture, namely the slurry; wherein the pH value of the slurry is 2-2.5, and the specific gravity is 1.3-1.4.

3. The continuous acid leaching method using aeration to control the reaction temperature according to claim 1, wherein: the primary acid leaching comprises the steps of continuously adding hydrogen peroxide into a primary acid leaching reaction kettle, wherein the flow ratio of hydrogen peroxide to injected slurry is 45% of the theoretical calculated amount required by the complete leaching of the slurry, namely:

the flow rate of hydrogen peroxide is equal to the flow rate of the slurry multiplied by the theoretical amount of hydrogen peroxide needed when the slurry in unit volume is completely leached multiplied by 0.45;

the liquid in the primary acid leaching reaction kettle can be replaced every 4 hours by the flow rate of continuously injecting the slurry into the primary acid leaching reaction kettle.

4. The continuous acid leaching method using aeration to control the reaction temperature according to claim 1, wherein: the primary acid leaching comprises the steps of,

and continuously adding sulfuric acid into the primary acid leaching reaction kettle to realize that the pH value is controlled to be 1-1.5, preferably 1.25 after the slurry, the hydrogen peroxide and the sulfuric acid are mixed.

5. The continuous acid leaching method using aeration to control the reaction temperature according to claim 1, wherein: the secondary acid leaching comprises continuously adding hydrogen peroxide into a secondary acid leaching reaction kettle, wherein the flow of the hydrogen peroxide is the same as that of the primary acid leaching reaction; and the secondary acid leaching also comprises continuously adding sulfuric acid into the secondary reaction kettle, mixing hydrogen peroxide, sulfuric acid and slurry from the overflow port of the primary reaction kettle, and controlling the pH value to be 2-2.5, preferably 2.25.

6. The continuous acid leaching method using aeration to control the reaction temperature according to claim 5, wherein: the capacity of the reaction kettle is the same with that of the primary acid leaching and the secondary acid leaching, and the acid leaching residence time of the secondary acid leaching reaction slurry is 4 hours.

7. The continuous acid leaching method using aeration to control the reaction temperature according to any one of claims 1 to 6, wherein: the overflow outlet of the primary acid leaching reaction kettle is connected to the slurry injection port of the secondary acid leaching reaction kettle, the injection port of the primary acid leaching reaction kettle is a raw material slurry inlet, and the overflow outlet of the secondary acid leaching reaction kettle is a slurry outlet after acid leaching.

8. The continuous acid leaching method using aeration to control the reaction temperature according to claim 1, wherein: and after the secondary acid leaching, performing filter pressing, namely performing filter pressing on the slurry continuously flowing out of the overflow outlet of the secondary acid leaching reaction kettle, wherein the leaching residue after the filter pressing is used for the subsequent high-acid leaching process for treatment.

9. The continuous acid leaching method according to any one of claims 1, 2 and 8, wherein the reaction temperature is controlled by aeration, and the method comprises the steps of: the high-acid leaching comprises the following steps,

adding water with a liquid-solid ratio of 3: 1-5: 1 into the secondary acid leaching residue put into the reaction kettle, pulping, and continuously and uniformly adding sulfuric acid and hydrogen peroxide, wherein the dosage of the sulfuric acid is 300g/L within 6 hours, and the dosage of the hydrogen peroxide is 100% -120% of the theoretical amount;

and after the high-acid leaching is carried out for 6 hours, carrying out filter pressing on a high-acid leaching solution and leaching residues, wherein the leaching solution is the high-acid leaching solution and is used for preparing slurry, and the leaching residues are subjected to environment-friendly treatment.

10. A continuous acid leaching system applied to the continuous acid leaching method according to any one of claims 1 to 9, characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

the primary acid leaching reaction kettle (100) comprises a primary acid leaching reaction kettle body (101), a slurry feeding device (102), an induced draft device (103), a stirring motor (104), a sulfuric acid feeding device (105), a hydrogen peroxide feeding device (106), an aeration device (107) and a stirring paddle (108); wherein, the aeration device (107) is arranged at the bottom of the acid leaching reaction kettle body (101);

the secondary acid leaching reaction kettle (200) comprises a secondary acid leaching reaction kettle body (201), an air inducing device (202), a stirring motor (203), a sulfuric acid feeding device (204), a hydrogen peroxide feeding device (205), an aeration device (206) and a stirring paddle (207); wherein, the aeration device (206) is arranged at the bottom of the kettle body (201) of the acid leaching reaction kettle;

the reaction kettle communication device (300) is used for communicating the primary acid leaching reaction kettle (100) with the secondary acid leaching reaction kettle (200) through the reaction kettle communication device (300).

Technical Field

The invention belongs to the field of ternary lithium battery recycling, and particularly relates to a continuous acid leaching system and method for controlling reaction temperature by adopting aeration.

Background

With the development of electric automobiles, more and more scrapped ternary lithium batteries are used. The recycling process of the ternary positive electrode material separated from the scrapped batteries by harmless crushing and the waste material reporting from the ternary positive electrode material in the production process needs acid leaching and acid leaching of nickel, cobalt, manganese and lithium metal salt solution.

The nickel-cobalt-manganese salt is a main production raw material of the ternary precursor, and the ternary precursor is a main production raw material of the ternary lithium battery. The acid leaching of the nickel-cobalt-manganese-lithium is generally carried out by adopting a process of sulfuric acid and hydrogen peroxide. The main chemical component of the ternary positive electrode material waste is nickel cobalt lithium manganate LiNi_xCo_yMn_1-x-yO₂The compound contains high valence nickel cobalt manganese, and the high valence nickel cobalt manganese is reduced into bivalent nickel cobalt manganese by adding a reducing agent during acid leaching, wherein the reducing agent can be hydrogen peroxide, sodium sulfite, sulfur dioxide or the like. The reaction formula when hydrogen peroxide is used as a reducing agent for acid leaching is as follows:

2LiNi_xCo_yMn_1-x-yO₂+3H₂SO₄+H₂O₂＝2xNiSO₄+2y CoSO₄+2(1-x-y)MnSO₄+Li₂SO₄+4H₂O+O₂

the pickle liquor usually contains impurities such as aluminum, iron and the like, the pickle liquor needs to be neutralized by soda ash until the pH is equal to about 4, and nickel, cobalt, manganese and lithium salt are separated by extraction and impurity removal. Most of nickel, cobalt, manganese and lithium can be leached out by acid leaching, and the rest of leaching residue is leached by high-acid leaching. However, in the acid leaching production process, concentrated sulfuric acid generates heat when being diluted by being added into water, the reaction of acid and raw materials generates a large amount of heat, and the reaction of acid and impurities, particularly aluminum powder in the raw materials, also releases a large amount of heat. The temperature rise of the liquid causes the hydrogen peroxide to be decomposed, and the hydrogen peroxide is decomposed to release a large amount of heat, so that the chain reaction can cause the reaction kettle to overflow, the production is stopped, and even safety and environmental protection accidents occur.

Meanwhile, the acid leaching of the traditional ternary anode material generally adopts sulfuric acid and hydrogen peroxide solution, an intermittent reaction kettle is usually adopted in the process flow, a large amount of heat is released in the acid leaching process, the temperature is easily increased, the temperature of the liquid of the primary acid leaching of the intermittent acid leaching can reach over 90 ℃, the hydrogen peroxide solution is decomposed and wasted due to overhigh temperature, the next feeding can be carried out after the primary acid leaching of the previous feeding is finished and the liquid in the reaction kettle is pressurized, the interval time is long, and the production efficiency of equipment is low.

Disclosure of Invention

This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.

The present invention has been made keeping in mind the above and/or other problems occurring in the prior art.

Therefore, the present invention aims to overcome the defects of the prior art and provide a continuous acid leaching method which adopts aeration to control the reaction temperature.

In order to solve the technical problems, the invention provides the following technical scheme: a continuous acid leaching method adopting aeration to control reaction temperature comprises the following steps,

preparing slurry, primary acid leaching, secondary acid leaching, high-acid leaching and filter pressing; wherein the content of the first and second substances,

the slurry is a mixture of nickel cobalt lithium manganate powder, water and acid liquor;

the primary acid leaching is carried out in a primary acid leaching reaction kettle, and the nickel, cobalt, manganese and lithium are leached by acid leaching by adding sulfuric acid and hydrogen peroxide;

soaking the secondary acid in a secondary acid leaching reaction kettle, and leaching nickel, cobalt, manganese and lithium by adding sulfuric acid and hydrogen peroxide;

the primary acid leaching reaction kettle and the secondary acid leaching reaction kettle are communicated;

the primary acid leaching and the secondary acid leaching are continuous acid leaching, continuous feeding and continuous discharging.

As a preferable scheme of the continuous acid leaching method adopting aeration to control the reaction temperature, the method comprises the following steps: the preparation of the slurry comprises the steps of fully stirring the high-acid leaching solution, the nickel cobalt lithium manganate powder and water to prepare a mixture, namely the slurry; wherein the pH value of the slurry is 2-2.5, and the specific gravity is 1.3-1.4.

As a preferable scheme of the continuous acid leaching method adopting aeration to control the reaction temperature, the method comprises the following steps: the primary acid leaching comprises the steps of continuously adding hydrogen peroxide into a primary acid leaching reaction kettle, wherein the flow ratio of hydrogen peroxide to injected slurry is 45% of the theoretical calculated amount required by the complete leaching of the slurry, namely:

the flow rate of hydrogen peroxide is equal to the flow rate of the slurry multiplied by the theoretical amount of hydrogen peroxide needed when the slurry in unit volume is completely leached multiplied by 0.45;

the liquid in the primary acid leaching reaction kettle can be replaced every 4 hours by the flow rate of continuously injecting the slurry into the primary acid leaching reaction kettle.

As a preferable scheme of the continuous acid leaching method adopting aeration to control the reaction temperature, the method comprises the following steps: the primary acid leaching comprises the steps of,

and continuously adding sulfuric acid into the primary acid leaching reaction kettle to realize that the pH value is controlled to be 1-1.5, preferably 1.25 after the slurry, the hydrogen peroxide and the sulfuric acid are mixed.

As a preferable scheme of the continuous acid leaching method adopting aeration to control the reaction temperature, the method comprises the following steps: the secondary acid leaching comprises continuously adding hydrogen peroxide into a secondary acid leaching reaction kettle, wherein the flow of the hydrogen peroxide is the same as that of the primary acid leaching reaction; and the secondary acid leaching also comprises continuously adding sulfuric acid into the secondary reaction kettle, mixing hydrogen peroxide, sulfuric acid and slurry from the overflow port of the primary reaction kettle, and controlling the pH value to be 2-2.5, preferably 2.25.

As a preferable scheme of the continuous acid leaching method adopting aeration to control the reaction temperature, the method comprises the following steps: the primary acid leaching and the secondary acid leaching have the same reaction kettle capacity, and the acid leaching residence time of the secondary acid leaching reaction slurry is 4 hours;

as a preferable scheme of the continuous acid leaching method adopting aeration to control the reaction temperature, the method comprises the following steps: the overflow outlet of the primary acid leaching reaction kettle is connected to the slurry injection port of the secondary acid leaching reaction kettle, the injection port of the primary acid leaching reaction kettle is a raw material slurry inlet, and the overflow outlet of the secondary acid leaching reaction kettle is a slurry outlet after acid leaching.

As a preferable scheme of the continuous acid leaching method adopting aeration to control the reaction temperature, the method comprises the following steps: and after the secondary acid leaching, performing filter pressing, namely performing filter pressing on the slurry continuously flowing out of the overflow outlet of the secondary acid leaching reaction kettle, wherein the leaching residue after the filter pressing is used for the subsequent high-acid leaching process for treatment.

As a preferable scheme of the continuous acid leaching method adopting aeration to control the reaction temperature, the method comprises the following steps: the high-acid leaching comprises the following steps,

adding water with a liquid-solid ratio of 3: 1-5: 1 into the secondary acid leaching residue put into the reaction kettle, pulping, and continuously and uniformly adding sulfuric acid and hydrogen peroxide, wherein the dosage of the sulfuric acid is 300g/L within 6 hours, and the dosage of the hydrogen peroxide is 100% -120% of the theoretical amount;

and after the high-acid leaching is carried out for 6 hours, carrying out filter pressing on a high-acid leaching solution and leaching residues, wherein the leaching solution is the high-acid leaching solution and is used for preparing slurry, and the leaching residues are subjected to environment-friendly treatment.

It is a further object of the present invention to overcome the disadvantages of the prior art and to provide a continuous acid leaching system for use in the continuous acid leaching method according to any one of claims 1 to 9.

In order to solve the technical problems, the invention provides the following technical scheme: a continuous acid leaching system applied to the continuous acid leaching method according to any one of claims 1 to 9, comprising,

the primary acid leaching reaction kettle comprises a primary acid leaching reaction kettle body, a slurry feeding device, an induced draft device, a stirring motor, a sulfuric acid feeding device, a hydrogen peroxide feeding device, an aeration device and a stirring paddle; wherein the aeration device is arranged at the bottom of the kettle body of the acid leaching reaction kettle;

the secondary acid leaching reaction kettle comprises a primary acid leaching reaction kettle body, an air inducing device, a stirring motor, a sulfuric acid feeding device, a hydrogen peroxide feeding device, an aeration device and a stirring paddle; wherein the aeration device is arranged at the bottom of the kettle body of the acid leaching reaction kettle;

the reaction kettle is communicated with the device, and the primary acid leaching reaction kettle is communicated with the secondary acid leaching reaction kettle through the reaction kettle communication device.

The invention has the beneficial effects that:

(1) in the acid leaching process, the conventional acid leaching can only treat about 90% of acid leaching rate generally, and the remaining 10% of acid leaching rate needs high-acid leaching, so that the production efficiency and capacity of a primary acid leaching reaction kettle are the key points for improving the overall acid leaching efficiency and capacity.

(2) In the conventional acid leaching process, impurities need to be removed after the raw material is subjected to acid leaching, the pH value needs to be adjusted back to 4 in the impurity removal process, and the pH value of the slurry needs to be adjusted back to 4, so that a large amount of sodium carbonate needs to be used, the cost is increased, and the processing burden of subsequent links is increased; therefore, the invention provides a primary acid leaching process carried out in a single reaction kettle, which is decomposed into primary acid leaching and secondary acid leaching respectively carried out in two reaction kettles; the method disperses the same amount of acid liquor and hydrogen peroxide liquid in the two reaction kettles for sectional control, the pH value of the first reaction kettle is 1-1.5, the acid leaching efficiency is improved, the acid leaching time is shortened, and the productivity is ensured; the pH value of the second reaction kettle is set to be higher than 2-2.5, the acid leaching effect is guaranteed, the pH adjustment of a subsequent impurity removal link is considered, and about 98% of the amount of the calcined soda can be reduced in the impurity removal link; compared with the one-time acid leaching process of a single reaction kettle, the method provided by the invention can obviously improve the productivity under the condition of ensuring the acid leaching rate, simultaneously reduces the usage amount of soda ash and lightens the subsequent treatment burden, and under the condition of the same equipment, the yield of continuous acid leaching is more than 2.5 times of that of an intermittent acid leaching method; the leaching efficiency in the continuous acid leaching process is more than 90%, and compared with the batch acid leaching method, the method has the advantages that the productivity is greatly improved, and the leaching rate is ensured.

(3) The invention realizes the temperature control of the aeration cooling liquid and the continuous acid leaching production, thereby being convenient for realizing the automatic control of the production process; more importantly, the invention avoids the risk of trough overflow caused by temperature rise or manual misoperation in the batch production process of the reaction kettle.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:

FIG. 1 is a schematic view of a reaction kettle for primary acid leaching and secondary acid leaching in the embodiment of the invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, specific embodiments thereof are described in detail below with reference to examples of the specification.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

Example 1

(1) Pumping a high-acid leaching solution into a feeding kettle, then feeding 3-4 tons of raw materials (nickel cobalt lithium manganate powder) for pulping for 1 hour, adding water into the feeding kettle when the high-acid leaching solution fully reacts with the raw materials to consume residual acid, controlling the specific gravity of slurry in the feeding kettle to be 1.3-1.4, stopping adding water, pumping the slurry in the feeding kettle into a raw material transfer kettle through a pump, and emptying the slurry in the feeding kettle to obtain the next kettle for feeding;

(2) the slurry of the raw material transfer kettle is pumped by a pump at 5m³/h～6m³The flow of the reaction kettle is changed to a primary acid leaching reaction kettle; when slurry passes through the primary or secondary acid leaching reaction kettle, the corresponding sulfuric acid and hydrogen peroxide are kept in a continuous adding state, the adding amount of the sulfuric acid in the primary acid leaching reaction kettle is controlled to be 1-1.5 according to an online pH meter, and the adding amount of the hydrogen peroxide is 40-50% of the theoretical amount of the completely leached amount in the slurry; the adding amount of sulfuric acid in the secondary acid leaching reaction kettle is controlled to be 2-2.5 according to an online pH meter, and the adding amount of hydrogen peroxide is the same as the flow of the primary acid leaching reaction kettle;

further, the process is as follows:

the first acid leaching is carried out in a primary acid leaching reaction kettle, and nickel, cobalt, manganese and lithium are leached by acid leaching by adding sulfuric acid and hydrogen peroxide, wherein the hydrogen peroxide is continuously added into the primary acid leaching reaction kettle, the flow rate of the hydrogen peroxide is in proportion to the flow rate of injected slurry and is 45% of the theoretical calculation amount required by the complete leaching of the slurry, the sulfuric acid is continuously added into the primary acid leaching reaction kettle, and the pH value is controlled to be 1-1.5, preferably 1.25 after the slurry, the hydrogen peroxide and the sulfuric acid are mixed;

soaking the secondary acid in a secondary acid leaching reaction kettle, and leaching nickel, cobalt, manganese and lithium by adding sulfuric acid and hydrogen peroxide, wherein the hydrogen peroxide is continuously added into the secondary acid leaching reaction kettle, the flow rate of the hydrogen peroxide is the same as that of the primary acid leaching reaction, the sulfuric acid is continuously added into the secondary reaction kettle, the pH is controlled to be 2-2.5, preferably 2.25 after the hydrogen peroxide, the sulfuric acid and the slurry from the overflow port of the primary reaction kettle are mixed, the hydrogen peroxide promotes the acid leaching reaction of the nickel, cobalt, manganese and lithium, the acidity of the slurry is reduced and the pH is increased along with the consumption of the sulfuric acid, the pH of the secondary acid leaching is controlled to be about 2.25 only by reducing the flow rate of the sulfuric acid, and if the pH of the secondary acid leaching is too low, the consumption of sodium carbonate in the subsequent impurity removal stage is greatly increased; if the pH is too high to exceed 2.5, Fe is an impurity³⁺Will hydrolyze into Fe (OH)₃The iron is enriched in the pickle liquor and is difficult to filter press, and the utilization rate of hydrogen peroxide is reduced;

the reaction temperature in the reaction kettle is controlled by the aeration method in the first acid leaching and the second acid leaching, concentrated sulfuric acid releases heat when being added into water, the acid reacts with the raw materials to generate an exothermic reaction, a large amount of heat is generated when the acid reacts with impurities, particularly aluminum powder in the raw materials, hydrogen peroxide is decomposed when the temperature is high, a large amount of heat is also released in the hydrogen peroxide decomposition process, and finally, a trough is likely to be formed, so that the production is stopped, and safety and environmental protection accidents can occur when the temperature is serious;

controlling the liquid temperature of the reaction kettle by an aeration method in the primary and secondary acid leaching, wherein the liquid temperature of the reaction kettle is controlled by the aeration method, namely an aeration coil is arranged at the bottom in the reaction kettle, compressed air is blown into the liquid for heat exchange by selecting a matched Roots blower, and the compressed air is continuously sprayed from aeration holes at the bottom of the liquid of the reaction kettle and escapes from the top of the liquid to continuously take away the heat in the liquid; the upper part of the reaction kettle is connected with an air pipe and a fan, and the gas carrying heat is subjected to environment-friendly treatment by an alkaline water spray tower and then is discharged after reaching the standard; the flow rate of the gas is adjusted by the pressure of the compressed air, so that the temperature of the acid-leaching liquid in the reaction kettle is controlled; if the temperature of the liquid in the reaction kettle rises, the aeration air pressure is increased, so that the heat exchange air quantity is increased to reduce the temperature of the liquid; if the liquid temperature is lower, the aeration air pressure is reduced, so that the heat exchange air quantity is reduced to increase the liquid temperature. Controlling aeration pressure by using liquid temperature, so as to control the temperature of the liquid in the acid leaching reaction kettle within the range of 60-70 ℃;

the primary acid leaching reaction kettle is communicated with the secondary acid leaching reaction kettle, the primary acid leaching and the secondary acid leaching are continuous acid leaching, continuous feeding and continuous discharging processes, an overflow outlet of the primary acid leaching reaction kettle is connected to a slurry injection port of the secondary acid leaching reaction kettle, the injection port of the primary acid leaching reaction kettle is a raw slurry inlet, and an overflow outlet of the secondary acid leaching reaction kettle is a slurry outlet after acid leaching;

the primary acid leaching and the secondary acid leaching have the same reaction kettle capacity, and the acid leaching residence time of the primary acid leaching reaction slurry and the secondary acid leaching reaction slurry is about 4 hours.

(3) And (3) carrying out filter pressing on the secondary acid leaching product through an acid leaching transfer kettle, wherein the feed liquid is the raw material of the next impurity removal process, the specific gravity is 1.28-1.35, and after sampling and detecting nickel, cobalt, manganese and lithium in the secondary acid leaching residue, removing the high acid and leaching.

(4) Adding secondary acid leaching residues into a high-acid leaching kettle, adding water with a liquid-solid ratio of 3: 1-5: 1, pulping, continuously and uniformly adding sulfuric acid and hydrogen peroxide, wherein the adding time of the sulfuric acid is 5-7 hours, 300g/L of sulfuric acid is added totally, the adding flow rate of the hydrogen peroxide is proportional to the flow rate of the sulfuric acid, and is 100% -120% of the theoretical dosage of complete acid leaching, after the sulfuric acid and the hydrogen peroxide are synchronously added, performing pressure filtration to obtain high-acid leaching liquid and leaching residues, wherein the leaching liquid is the high-acid leaching liquid for preparing slurry, and the leaching residues are subjected to environment-friendly treatment.

Example 2

This embodiment provides a continuous acid leaching system applied to a continuous acid leaching method, which, as shown in fig. 1, mainly includes,

the primary acid leaching reaction kettle 100 comprises a primary acid leaching reaction kettle body 101, a slurry feeding device 102, an induced draft device 103, a stirring motor 104, a sulfuric acid feeding device 105, a hydrogen peroxide feeding device 106, an aeration device 107 and a stirring paddle 108; wherein, the aeration device 107 is arranged at the bottom of the kettle body 101 of the acid leaching reaction kettle;

the secondary acid leaching reaction kettle 200 comprises a secondary acid leaching reaction kettle body 201, an air inducing device 202, a stirring motor 203, a sulfuric acid feeding device 204, a hydrogen peroxide feeding device 205, an aeration device 206 and a stirring paddle 207; wherein, the aeration device 206 is arranged at the bottom of the kettle body 201 of the acid leaching reaction kettle;

the reaction kettle is communicated with a device 300, and the primary acid leaching reaction kettle 100 is communicated with the secondary acid leaching reaction kettle 200 through the reaction kettle communication device 300.

Specifically, the slurry in the raw material transfer kettle is pumped by a pump at 5m³/h～6m³The flow rate of the hydrogen peroxide/h is transferred into a primary acid leaching reaction kettle through a slurry feeding device 102, the corresponding sulfuric acid and hydrogen peroxide are kept in a continuous adding state, the adding amount of the sulfuric acid in the primary acid leaching reaction kettle is controlled to be 1-1.5 according to an online pH meter, and the adding amount of the hydrogen peroxide is 40% -50% of the total leaching amount of the theoretical amount in the slurry;

further, an aeration device 107 is arranged at the bottom of the primary acid leaching reaction kettle body 101, compressed air is blown into the liquid for heat exchange, and the compressed air is continuously sprayed from aeration holes at the bottom of the liquid of the reaction kettle and escapes from the top of the liquid to continuously take away heat in the liquid;

the upper part of the reaction kettle is provided with an air inducing device 103, and the gas carrying heat is subjected to environment-friendly treatment by an alkaline water spray tower and then is discharged after reaching the standard;

the flow rate of the gas is adjusted by adjusting the pressure of the compressed air through the aeration device 107, so that the temperature of the acid-immersed liquid in the reaction kettle is controlled; if the temperature of the liquid in the reaction kettle rises, the aeration air pressure is increased, so that the heat exchange air quantity is increased to reduce the temperature of the liquid; if the liquid temperature is lower, the aeration air pressure is reduced, so that the heat exchange air quantity is reduced to increase the liquid temperature; controlling aeration pressure by using liquid temperature, so as to control the temperature of the liquid in the acid leaching reaction kettle within the range of 60-70 ℃;

further, the stirring paddle 108 realizes stirring action through the action of the stirring motor 104, the acid leaching residence time of the primary acid leaching reaction slurry is 4 hours, and then the slurry after the primary acid leaching reaction enters the secondary acid leaching reaction kettle 200 through the reaction kettle communicating device 300;

specifically, after slurry after primary acid leaching reaction enters a secondary acid leaching reaction kettle 200 through a reaction kettle communication device 300, the addition of sulfuric acid in the secondary acid leaching reaction kettle is controlled to be 2-2.5 according to an online pH meter, the addition of hydrogen peroxide is the same as the flow of the primary acid leaching reaction kettle, an aeration device 206 is arranged at the bottom of a kettle body 201 of the secondary acid leaching reaction kettle, compressed air is blown into liquid for heat exchange, and the compressed air is continuously sprayed from aeration holes at the bottom of the liquid in the reaction kettle and escapes from the top of the liquid to continuously take away heat in the liquid;

the upper part of the reaction kettle is provided with an air inducing device 202, and the gas carrying heat is subjected to environment-friendly treatment by an alkaline water spray tower and then is discharged after reaching the standard;

the flow of the gas is adjusted by adjusting the pressure of the compressed air through the aeration device 206, so that the temperature of the acid-leaching liquid in the reaction kettle is controlled; if the temperature of the liquid in the reaction kettle rises, the aeration air pressure is increased, so that the heat exchange air quantity is increased to reduce the temperature of the liquid; if the liquid temperature is lower, the aeration air pressure is reduced, so that the heat exchange air quantity is reduced to increase the liquid temperature; and controlling the aeration pressure by using the liquid temperature, so that the temperature of the liquid in the acid leaching reaction kettle is controlled within the range of 60-70 ℃.

And (3) carrying out filter pressing on the secondary acid leaching product through an acid leaching transfer kettle, wherein the feed liquid is the raw material of the next impurity removal process, the specific gravity is 1.28-1.35, sampling secondary acid leaching residues, detecting nickel, cobalt, manganese and lithium in the secondary acid leaching residues, and removing high acid for acid leaching.

The leaching rate of the primary and secondary continuous acid leaching is about 90%, complete leaching can be ensured only by high-acid leaching, the leaching rate of the tertiary acid leaching is more than 99%, the typical content of nickel, cobalt, manganese and lithium in leaching residue after the primary acid leaching and the secondary acid leaching are carried out continuously, and the typical concentration of the nickel, cobalt, manganese and lithium in the leaching solution are shown in table 1.

TABLE 1

	Ni	Co	Mn	Li	Acidity of the solution
						Primary and secondary acid leaching residue	7.9％	3.1％	5％	1.1％	/
Primary and secondary filtrate	50g/L	20g/L	30g/L	11g/L	PH＝2.5
						High acid leaching residue	0.031％	0.04％	0.014％	0.014％	/
High acid filtrate	15g/L	6g/L	9g/L	1.9g/L	160g/L

The slurry is prepared by fully stirring leachate obtained by high-acid leaching, nickel cobalt lithium manganate powder and water, and the dosage of the leachate is mainly characterized in that the pH value of the slurry is controlled to be 2-2.5; the slurry is mainly characterized in that the liquid-solid ratio is 1.3-1.4, the leaching rate of the nickel cobalt lithium manganate is influenced when the liquid-solid ratio is too high, and the acid leaching capacity of a reaction kettle is influenced when the liquid-solid ratio is too low.

The primary acid leaching is a reaction kettle for leaching nickel, cobalt, manganese and lithium by adopting a sulfuric acid and hydrogen peroxide process, wherein the reaction kettle is used for continuously feeding and continuously discharging, continuously feeding slurry into the reaction kettle, and continuously injecting the slurry into the reaction kettle, wherein the flow rate of the slurry is equal to that of liquid in the reaction kettle which is completely replaced every 4 hours, and the slurry has acid leaching time of 4 hours in the reaction kettle; the key of continuous feeding is that uniform heating of acid leaching reaction is realized, concentrated sulfuric acid is exothermic when added into water, the acid and raw materials react to generate exothermic reaction, a large amount of heat is generated when the acid reacts with impurities, particularly aluminum powder in the raw materials, hydrogen peroxide is decomposed when the temperature is high, a large amount of heat is also generated in the hydrogen peroxide decomposition process, and finally, a trough is possibly generated, so that production is stopped, and safety and environmental protection accidents can occur when the temperature is serious; the continuous discharge means that the slurry in the reaction kettle automatically and continuously flows out, and the slurry in the primary acid leaching reaction kettle automatically flows out from the overflow outlet after being subjected to acid leaching for about 4 hours.

The primary acid leaching is an aeration method to control the liquid temperature of the reaction kettle, the aeration method to control the liquid temperature of the reaction kettle means that an aeration coil is arranged at the bottom in the reaction kettle, compressed air is blown into the liquid for heat exchange by selecting a matched Roots blower, the compressed air is continuously sprayed from an aeration hole at the bottom of the liquid of the reaction kettle and escapes from the top of the liquid, and the heat in the liquid is continuously taken away; the upper part of the reaction kettle is connected with an air pipe and a fan, and the gas carrying heat is subjected to environment-friendly treatment by an alkaline water spray tower and then is discharged after reaching the standard; the flow of the gas is adjusted by the pressure of the compressed air, so that the temperature of the acid-leaching liquid in the reaction kettle is controlled. If the temperature of the liquid in the reaction kettle rises, the aeration air pressure is increased, so that the heat exchange air quantity is increased to reduce the temperature of the liquid; if the liquid temperature is lower, the aeration air pressure is reduced so as to reduce the heat exchange air quantity to increase the liquid temperature, and the aeration air pressure is controlled by the liquid temperature so as to control the liquid temperature in the acid leaching reaction kettle within the range of 60-70 ℃.

The primary acid leaching is continuously added with sulfuric acid, and the continuous addition of the sulfuric acid is mainly characterized in that the pH value of the mixed slurry, hydrogen peroxide and sulfuric acid is obtained; controlling the pH value of the slurry, hydrogen peroxide and sulfuric acid within the range of 1-1.5 after mixing by adjusting the flow of the sulfuric acid, and typically maintaining the pH value at 1.25; the low pH value is beneficial to improving the acid leaching speed of the nickel, cobalt, manganese and lithium, but the tolerance of the detection equipment is influenced if the pH value is too low.

The secondary acid leaching is a reaction kettle for acid leaching of nickel, cobalt, manganese and lithium by adopting a sulfuric acid and hydrogen peroxide process, wherein the reaction kettle is used for continuously feeding and continuously discharging, and the continuous feeding is that slurry flowing out of an overflow port of a primary acid leaching reaction kettle is automatically and continuously injected into the reaction kettle; the flow rate of the slurry is equal to that of the liquid in the reaction kettle which is replaced once every 4 hours, so that the slurry has the acid leaching time of 4 hours in the reaction kettle, and the slurry in the secondary acid leaching reaction kettle automatically flows out from an overflow port after being subjected to acid leaching and staying for about 4 hours; the secondary acid leaching is mainly characterized in that sulfuric acid is continuously added, and the continuous addition of the sulfuric acid is mainly characterized in that the pH value of the slurry, hydrogen peroxide and sulfuric acid is obtained after mixing. The pH value of the mixed slurry from the primary acid leaching reaction kettle overflow outlet is controlled between 2 and 2.5, typically 2.25.

The secondary acid leaching mainly comprises the following pH control modes: the hydrogen peroxide promotes the acid leaching reaction of nickel, cobalt, manganese and lithium, the sulfuric acid is consumed in the acid leaching reaction, the acidity of the slurry is reduced, and the pH value is increased. The pH of the secondary acid leaching can be controlled to be about 2.25 only by reducing the flow of the sulfuric acid. If the pH of the secondary acid leaching is too low, the consumption of sodium carbonate in the subsequent impurity removal stage is greatly increased; if the pH is too high to exceed 2.5, Fe is an impurity³⁺Will hydrolyze into Fe (OH)₃The iron is enriched in the pickle liquor and is difficult to filter press, and the utilization rate of the hydrogen peroxide is reduced.

The invention provides a primary acid leaching process carried out in a single reaction kettle, which is decomposed into primary acid leaching and secondary acid leaching respectively carried out in two reaction kettles. Wherein the overflow outlet of the primary acid leaching reaction kettle is connected to the slurry filling port of the secondary acid leaching reaction kettle. And the slurry continuously injected from the injection port of the primary acid leaching reaction kettle sequentially passes through the acid leaching of the primary acid leaching reaction kettle and the secondary acid leaching of the secondary acid leaching reaction kettle, and finally flows out from the overflow port of the secondary acid leaching reaction kettle. The invention disperses the same amount of acid liquid and hydrogen peroxide liquid in two reaction kettles for sectional control. The pH value of the first reaction kettle is 1-1.5, and the key point is to improve the acid leaching efficiency, shorten the acid leaching time and ensure the productivity; the pH value of the second reaction kettle is set to be higher by 2-2.5, the acid leaching effect is guaranteed, the pH adjustment of a subsequent impurity removal link is also considered, and less soda amount can be used in the impurity removal link, so that the cost is reduced, and the burden of subsequent treatment is relieved.

Compared with the traditional method, the acid leaching is carried out in one reaction kettle for one time, the more acid solution is put, namely the pH value is low, the acid leaching speed is improved, the acid leaching time is shortened, and the acid leaching rate is high; however, the acid solution is more than needed and is not beneficial to the subsequent impurity removal process, because the impurity removal process requires a pH value of about 4, a large amount of soda ash needs to be added in order to adjust the pH value of the liquid back to 4, the usage amount of the soda ash is increased, the subsequent treatment burden is increased, and the cost is greatly increased. However, if the acid solution is fed in a small amount and the pH value is high, the acid leaching speed is greatly reduced, the acid leaching time is prolonged, and the acid leaching rate (a certain proportion of metal is changed into a salt solution) is reduced.

The invention disperses the same amount of acid liquid and hydrogen peroxide liquid in two reaction kettles for sectional control. The pH value of the first reaction kettle is 1-1.5, and the key point is to improve the acid leaching efficiency, shorten the acid leaching time and ensure the productivity; the pH value of the second reaction kettle is set to be higher by 2-2.5, the acid leaching effect is guaranteed, meanwhile, the pH adjustment of a subsequent impurity removal link is also considered, the amount of the calcined soda is greatly reduced in the impurity removal link, and therefore the cost is reduced and the burden of subsequent treatment is relieved.

In the conventional acid leaching process, impurities need to be removed after the raw material is subjected to acid leaching, the pH value needs to be adjusted back to 4 in the impurity removal process, and the pH value of the slurry needs to be adjusted back to 4, so that a large amount of sodium carbonate needs to be used, the cost is increased, and the processing burden of subsequent links is increased; therefore, the invention firstly provides a primary acid leaching process carried out in a single reaction kettle, and the primary acid leaching process and the secondary acid leaching process are decomposed into primary acid leaching and secondary acid leaching which are respectively carried out in two reaction kettles.

The method disperses the same amount of acid liquor and hydrogen peroxide liquid in the two reaction kettles for sectional control, the pH value of the first reaction kettle is 1-1.5, the acid leaching efficiency is improved, the acid leaching time is shortened, and the productivity is ensured; the pH value of the second reaction kettle is set to be higher than 2-2.5, the acid leaching effect is ensured, the pH adjustment of a subsequent impurity removal link is also considered, the consumption of soda can be reduced by about 98% in the impurity removal link, the cost is reduced, and the burden of subsequent treatment is reduced; compared with the one-time acid leaching process of a single reaction kettle, the method provided by the invention can obviously improve the productivity under the condition of ensuring the acid leaching rate, simultaneously reduces the usage amount of soda ash and lightens the subsequent treatment burden, and under the condition of the same equipment, the yield of continuous acid leaching is more than 2.5 times of that of an intermittent acid leaching method; the leaching efficiency in the continuous acid leaching process is more than 90%, and compared with the batch acid leaching method, the method has the advantages that the productivity is greatly improved, and the leaching rate is ensured.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.