CN112777580B - Industrial method for treating substance containing lithium iron phosphate - Google Patents

Industrial method for treating substance containing lithium iron phosphate Download PDF

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Publication number
CN112777580B
CN112777580B CN201911058063.1A CN201911058063A CN112777580B CN 112777580 B CN112777580 B CN 112777580B CN 201911058063 A CN201911058063 A CN 201911058063A CN 112777580 B CN112777580 B CN 112777580B
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leaching
countercurrent
liquid
lithium
precipitation
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CN112777580A (en
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徐伟
缪仁群
江小鹏
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Yichun Yecheng Technology Co ltd
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Yichun Yecheng Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/37—Phosphates of heavy metals
    • C01B25/375—Phosphates of heavy metals of iron
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/30—Alkali metal phosphates
    • C01B25/308—Methods for converting an alkali metal orthophosphate into another one; Purification; Decolorasing; Dehydrating; Drying
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D15/00—Lithium compounds
    • C01D15/08—Carbonates; Bicarbonates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/04—Chlorides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/02—Oxides or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/18—Carbonates
    • C01F11/181—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10—Obtaining alkali metals
    • C22B26/12—Obtaining lithium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/006—Wet processes
    • C22B7/007—Wet processes by acid leaching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/54—Reclaiming serviceable parts of waste accumulators
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/84—Recycling of batteries or fuel cells

Abstract

The present application provides an industrial process for treating a solid substance containing lithium iron phosphate, comprising the steps of: (1) The solid matter is contacted with acid to carry out primary leaching reaction, so as to obtain primary leaching liquid and primary leaching solid; (2) And (3) contacting the primary leaching solution with an oxidant to perform a primary precipitation reaction to obtain primary precipitation solids and primary precipitation liquid, wherein the primary precipitation solids are solids containing ferric phosphate, and the primary precipitation liquid is solution containing lithium ions, and the ratio of the weight of solid substances to the total weight of liquid substances entering the primary leaching reaction is 1:3-1:5. The method is suitable for large-scale production and recovery of the lithium iron phosphate battery anode waste. The method is particularly suitable for industrial application, the solid-liquid ratio in the primary leaching reaction is controlled in a proper range, the best industrial recovery efficiency can be obtained, the least waste liquid is generated, and almost all solid products are recovered.

Description

Industrial method for treating substance containing lithium iron phosphate
Technical Field
The invention relates to the technical field of recycling of lithium iron phosphate battery anode materials, in particular to an industrial method for treating solid matters containing lithium iron phosphate and equipment for realizing the method.
Background
Lithium iron phosphate battery materials have been widely used in various fields, and automobile power batteries and the like. The lithium iron phosphate battery has huge market capacity, the lithium iron phosphate battery which is put on the market at present starts to enter a recovery period, the lithium iron phosphate battery has the largest production amount and the highest value in the recovery process, namely lithium iron phosphate positive electrode materials, meanwhile, scrapped lithium iron phosphate positive electrode sheets and positive electrode powder are also produced in the production process of the lithium iron phosphate battery, and the recovery materials are collectively called as the lithium iron phosphate battery recovery positive electrode materials, so that the quantity of the lithium iron phosphate positive electrode materials is huge. The treatment of the recycled positive electrode materials of the lithium iron phosphate batteries in the current market only stays on the level of recycling lithium metal, the efficiency is extremely low (the recycling part is less than 5% by weight), and a large amount of solid slag is produced and is difficult to use. Specifically, the lithium iron phosphate material contains a large amount of carbon powder, phosphate radical, iron and lithium, but the common recovery method only recovers 3-5wt% of lithium element, so that a large amount of mixed waste containing carbon powder, phosphate radical and iron element is generated, and the mixed waste is difficult to recycle. In addition, lithium iron phosphate waste is also produced in the process of producing lithium iron phosphate batteries, such as lithium iron phosphate positive electrode powder waste and lithium iron phosphate positive electrode sheet waste.
If lithium, phosphorus, iron and the like in the lithium iron phosphate waste can be effectively recycled, not only can lithium resources with very low proportion of waste be recycled, but also resources with very large proportion of iron, phosphorus and the like can be simultaneously recycled, thereby improving the environment and creating great economic benefits. Due to the large output of lithium iron phosphate waste, there is a strong need for an industrial recovery process that is directly efficient and environmentally friendly.
Disclosure of Invention
The present application relates to an industrial process for treating solid substances containing lithium iron phosphate and to a device for carrying out the process, which better solves at least one of the problems mentioned in the background art.
The invention includes the following embodiments:
embodiment 1, an industrial method for treating a solid substance containing lithium iron phosphate, includes the steps of:
(1) The solid matter is contacted with acid to carry out primary leaching reaction, so as to obtain primary leaching liquid and primary leaching solid;
(2) The first-stage leaching solution is contacted with an oxidant to carry out a first-stage precipitation reaction to obtain first-stage precipitation solid and first-stage precipitation liquid, wherein the first-stage precipitation solid is solid containing ferric phosphate, the first-stage precipitation liquid is solution containing lithium ions,
Wherein the weight of the solid material to the total weight of liquid material entering the primary leaching reaction is from 1:3 to 1:5 (e.g. 1:3.5;1:4; 1:4.5), the liquid material added to the reaction comprising the acid.
Embodiment 2, the method according to embodiment 1, wherein,
the molar ratio of the hydrogen ions which can react in the acid to the ferrous iron in the substance containing lithium iron phosphate is (1.1-1.3): 1, or
The molar ratio of the hydrogen ions which can react in the acid to lithium in the substance containing lithium iron phosphate is 1.1-1.3.
Embodiment 3, the method of embodiment 1, further comprising:
and carrying out multistage countercurrent leaching treatment (such as secondary countercurrent treatment) on the primary leached solids by adopting a first washing liquid to obtain countercurrent leaching liquid and countercurrent leached solids, returning the countercurrent leaching liquid to the primary leaching reaction, and the liquid substances entering the primary leaching reaction also comprise the first washing liquid.
Embodiment 4, the method according to embodiment 1 or 3, further comprising:
and carrying out multistage countercurrent precipitation treatment (for example, secondary countercurrent treatment) on the first-stage precipitated solid by adopting a second washing liquid to obtain countercurrent precipitation liquid and countercurrent precipitation solid, returning the countercurrent precipitation liquid into the first-stage leaching reaction and/or the multistage countercurrent leaching treatment, wherein the liquid substance entering the first-stage leaching reaction also comprises the second washing liquid.
Embodiment 5, the method of embodiment 1, further comprising:
and (3) enabling the primary effluent to be in contact with alkali to obtain solid impurities and a lithium precipitation solution.
Embodiment 6, the method of embodiment 5, further comprising:
and (3) contacting the lithium precipitation solution with sodium carbonate to obtain lithium carbonate precipitation and lithium-containing tail liquid.
Embodiment 7, the method of embodiment 3, further comprising:
in the multistage countercurrent leaching process, acid is added.
Embodiment 8, the method of embodiment 4, further comprising:
in the multistage countercurrent precipitation process, an oxidizing agent is added.
Embodiment 9, the method of embodiment 1, wherein the lithium iron phosphate-containing substance comprises at least one selected from the group consisting of: lithium iron phosphate positive electrode powder waste, lithium iron phosphate positive electrode sheet waste, lithium iron phosphate battery positive electrode waste, wherein the lithium content is 2.5-5wt%, for example 3 to 4.5wt%.
Embodiment 10, the method according to embodiment 1, wherein the reaction time of the primary leaching reaction is 0.1 to 3 hours, and the reaction time of the primary precipitation reaction is 1 to 3 hours.
Embodiment 11, the method according to embodiment 2, wherein the reaction time of each stage in the multistage countercurrent leaching treatment is 0 to 1 hour.
Embodiment 12 is the method according to embodiment 4, wherein the reaction time of each stage in the multistage countercurrent chromatography is 0 to 1 hour.
Embodiment 13 is the method according to embodiment 1, wherein the oxidizing agent is hydrogen peroxide, the molar ratio of hydrogen peroxide to lithium ions in the reaction solution is (0.55 to 0.65): 1, and the molar ratio of hydrogen peroxide to ferrous iron in the lithium iron phosphate-containing material is (0.55 to 0.65): 1.
Embodiment 14, the method of embodiment 1, wherein the primary leaching reaction is at a pH of 0 to 2, and the primary precipitation reaction is at a pH ranging from 0-2 at the beginning to 2.5 to 3.5 at the end.
Embodiment 15, the method of embodiment 4, wherein "contacting the primary effluent with a base" comprises contacting the primary effluent with sodium hydroxide at a pH greater than 10, and adding sodium carbonate in an amount of 1 to 2 times the molar number of calcium ions in the primary effluent.
Embodiment 16, the method according to embodiment 5, wherein the molar ratio of the amount of sodium carbonate used in the "contacting the lithium precipitation solution with sodium carbonate" step to lithium ions in the lithium precipitation solution is (0.5 to 0.55): 1.
Embodiment 17, the method of embodiment 5, wherein the step of "contacting the lithium precipitation solution with sodium carbonate" is performed at a temperature of 55 to 95 degrees celsius for 1 to 4 hours.
Embodiment 18, the method of embodiment 5, further comprising adding trisodium phosphate to the lithium-containing tail solution or adding sodium carbonate after evaporation concentration to obtain lithium phosphate solids or lithium carbonate and brine wastewater.
Embodiment 19 is an iron phosphate containing 0.1% or more of lithium, 0.01% or less of calcium, 0.01% or less of magnesium, 0.01% or less of copper, and 0.01% or less of aluminum. In some embodiments, the iron phosphate contains less than or equal to 0.4% lithium, such as less than or equal to 0.3% lithium, such as less than or equal to 0.2% lithium.
Embodiment 20, the iron phosphate of embodiment 19, comprising 0.15% or greater or 0.20% lithium.
Embodiment 21, the iron phosphate of embodiment 19, comprising 0.005% or less or 0.0035% calcium.
Embodiment 22, the iron phosphate of embodiment 19, comprising 0.005% or less, or 0.003% or 0.0012% magnesium.
Embodiment 23, the iron phosphate of embodiment 19, comprising 0.001% or less, or 0.0005% or 0.0001% copper.
Embodiment 24, the iron phosphate of embodiment 19, comprising 0.005% or less, or 0.003% or 0.0016% aluminum.
Embodiment 25, the iron phosphate of embodiment 19, which is iron phosphate dihydrate, contains 28% to 31% iron, or 29% to 30% iron.
Embodiment 26, the iron phosphate of embodiment 19, produced by the method of any one of embodiments 1-18.
Embodiment 27, a method of treating a solution containing lithium ions having a pH of less than 4, comprising:
contacting the solution containing lithium ions with a first base to raise the pH value to a first pH value and maintaining the pH value for a first time to obtain a first precipitate and a first lithium purification solution;
contacting the first lithium purified solution with a second base to raise the pH to a second pH and for a second time to obtain a second precipitate and a second lithium purified solution;
and (3) contacting the second lithium purified solution with a third base to raise the pH value to a third pH value and maintaining the pH value for a third time to obtain a third precipitate and a third lithium purified solution.
Embodiment 28, the method of embodiment 27, further comprising: and contacting the third lithium purified solution with ion exchange resin to obtain a fourth lithium purified solution.
Embodiment 29, the method of embodiment 28, further comprising: and reacting the fourth lithium purified solution with sodium carbonate to obtain lithium carbonate precipitate.
Embodiment 30, the method of embodiment 27, wherein the first pH is a number from 4 to less than 6 and the first time is 30 minutes or more.
Embodiment 31, the method of embodiment 27 or 30, wherein the second pH is a number from 6 to less than 8 and the second time is 30 minutes or more.
The method of embodiment 32, or embodiment 27 or 30, wherein the third pH is a number of 11 or more and the third time is 30 minutes or more.
Embodiment 33, the method of embodiment 28, wherein the ion exchange resin is a yin-yang mixed resin.
Embodiment 34, the method of embodiment 27, wherein the first base comprises at least one selected from the group consisting of lithium carbonate, lithium hydroxide, and sodium hydroxide.
Embodiment 35, the method of embodiment 27, wherein the second base comprises at least one selected from sodium hydroxide and lithium hydroxide.
Embodiment 36, the method of embodiment 27, wherein the third base comprises: at least one selected from sodium hydroxide and lithium hydroxide, and at least one selected from sodium carbonate and lithium carbonate.
Embodiment 37, the method of embodiment 27, wherein the lithium ion-containing solution is obtained by contacting a lithium battery recycle with an acid.
Embodiment 38, a reaction device, wherein the reaction device comprises a primary leaching solid-liquid reactor, a primary effluent liquid reactor, and a multi-stage countercurrent precipitation system;
the primary leaching solid-liquid reactor comprises a primary leaching solid-liquid contact device and a primary leaching solid-liquid separation device,
the primary leaching solid-liquid contact equipment is provided with a primary leaching solid-liquid contact equipment feed inlet and a primary leaching solid-liquid contact equipment discharge outlet, the primary leaching solid-liquid separation equipment is provided with a primary leaching solid-liquid separation equipment feed inlet, a primary leaching solid-liquid separation equipment liquid discharge outlet and a primary leaching solid-liquid separation equipment solid discharge outlet,
the discharge port of the primary leaching solid-liquid contact equipment is connected with the feed port of the primary leaching solid-liquid separation equipment,
the primary effluent liquid-liquid reactor comprises a primary effluent liquid-liquid contact device and a primary effluent solid-liquid separation device,
The primary separation solid-liquid separation equipment is provided with a primary separation solid-liquid separation equipment feed inlet, a primary separation solid-liquid separation equipment liquid discharge outlet and a primary separation solid-liquid separation equipment solid discharge outlet,
the discharge port of the primary precipitation liquid-liquid contact equipment is connected with the feed port of the primary precipitation solid-liquid separation equipment,
the liquid outlet of the primary leaching solid-liquid separation device is connected with the feed inlet of the primary leaching liquid-liquid contact device;
the multistage countercurrent precipitation system comprises N countercurrent precipitation units, wherein an ith countercurrent precipitation unit comprises: countercurrent precipitation contact equipment and countercurrent precipitation separation equipment, wherein N is an integer greater than or equal to 2, i is an integer from 1 to N,
wherein the countercurrent precipitation contact equipment is provided with a countercurrent precipitation contact equipment feed inlet and a countercurrent precipitation contact equipment discharge outlet, the countercurrent precipitation separation equipment is provided with a countercurrent precipitation separation equipment feed inlet, a countercurrent precipitation separation equipment liquid discharge outlet and a countercurrent precipitation separation equipment solid discharge outlet,
the discharge port of the countercurrent precipitation contact device is connected with the feed port of the countercurrent precipitation separation device,
Wherein, for the ith countercurrent precipitation unit,
when N > i >1 (i and N are integers, and N is an integer greater than or equal to 2), the feed inlet of the countercurrent precipitation contact device is connected with the liquid discharge outlet of the countercurrent precipitation separation device of the (i+1) th countercurrent precipitation unit and is connected with the solid discharge outlet of the countercurrent precipitation separation device of the (i-1) th countercurrent precipitation unit;
when i=n, the countercurrent precipitation contact device feed inlet is connected with the countercurrent precipitation separation device solid discharge outlet of the i-1 st countercurrent precipitation unit and with the external feed device of the second wash liquor;
when i=1, the feed inlet of the countercurrent precipitation contact device is connected with the liquid discharge outlet of the countercurrent precipitation separation device of the 2 nd countercurrent precipitation unit and is connected with the solid discharge outlet of the primary precipitation solid-liquid separation device. And the liquid discharge port of the countercurrent precipitation separation device is connected with the primary leaching solid-liquid contact device.
Embodiment 39, the reaction apparatus of embodiment 38, further comprising a multi-stage countercurrent leaching system comprising N countercurrent leaching units, wherein the ith countercurrent leaching unit comprises: countercurrent leaching contact equipment and countercurrent leaching separation equipment, wherein N is an integer greater than or equal to 2, i is an integer from 1 to N,
Wherein the countercurrent leaching contact equipment is provided with a countercurrent leaching contact equipment feed inlet and a countercurrent leaching contact equipment discharge outlet, the countercurrent leaching separation equipment is provided with a countercurrent leaching separation equipment feed inlet, a countercurrent leaching separation equipment liquid discharge outlet and a countercurrent leaching separation equipment solid discharge outlet,
the discharge port of the countercurrent leaching contact device is connected with the feed port of the countercurrent leaching separation device,
wherein, for the ith countercurrent leaching unit,
when N > i >1, the feed inlet of the countercurrent leaching contact device is connected with the liquid discharge outlet of the countercurrent leaching separation device of the (i+1) th countercurrent leaching unit and is connected with the solid discharge outlet of the countercurrent leaching separation device of the (i-1) th countercurrent leaching unit;
when i=n, the countercurrent leaching contact device feed inlet is connected with the countercurrent leaching separation device solid discharge port of the i-1 st countercurrent leaching unit and with the external feed device of the first washing liquid;
when i=1, the countercurrent leaching contact device feed inlet is connected with the countercurrent leaching separation device liquid discharge outlet of the (i+1) th countercurrent leaching unit and is connected with the primary leaching solid-liquid separation device solid discharge outlet. And a liquid discharge port of the countercurrent leaching separation device is connected with the primary leaching solid-liquid contact device.
Embodiment 40, the reaction device of embodiment 39, wherein when i < N, the countercurrent leaching unit further comprises an acid feed.
Embodiment 41, the reaction apparatus according to embodiment 39, characterized in that the countercurrent precipitation separation device liquid discharge port of the 1 st countercurrent precipitation unit of the multistage countercurrent leaching system is connected to the countercurrent leaching contact device of the 1 st countercurrent leaching unit of the multistage countercurrent leaching system, thereby being connected to the one-stage leaching solid-liquid contact device in this way.
Compared with the recovery method in the prior art, the method can not only efficiently recover lithium metal, but also effectively recover iron phosphate (one of main raw materials of the lithium iron phosphate battery) with the largest weight ratio, the recovery and utilization ratio is more than 90 percent by weight, the recovered residual solid slag is mainly carbon powder, the recovered solid slag can be directly used as industrial fuel or further deeply processed into carbon products, three products are produced by one method, the recovered positive electrode material of the lithium iron phosphate battery is recovered as much as possible, the economic benefit and the social benefit are huge, the method is particularly suitable for industrial application while the technical effects are obtained, the solid-liquid ratio in the primary leaching reaction is controlled in a proper range, the optimal industrial recovery efficiency can be obtained, the minimum waste liquid is produced, and almost all solid products are recovered. The acid content in the primary leaching reaction is controlled within a proper range, so that the pH value automatically rises to the precipitation point of the ferric phosphate in the primary precipitation reaction process, and the pH value in the primary precipitation reaction does not need to be regulated. The countercurrent precipitation liquid is returned to the primary leaching reaction and/or the multistage countercurrent leaching treatment, so that the liquid amount in the primary leaching reaction can be fully increased, the reaction sufficiency is increased, and the recovery efficiency is improved. The ferric phosphate prepared by the method contains a small amount of lithium ions and very few impurities, and is very favorable for being used for producing lithium iron phosphate batteries again. The device is specially used for the method of the invention, and can achieve corresponding technical effects.
In a method for treating a solution containing lithium ions having a pH of less than 4, three steps are employed to raise the pH, and a fourth step employs ion exchange resin to separate trace amounts of impurity ions, ultimately obtaining a highly pure lithium precipitating solution and three different precipitates. The multi-step method for improving the pH value and removing impurities not only can lead the purity of the impurity precipitation to be higher and obtain various different impurity precipitation with commercial utilization value, but also can prevent amphoteric metals such as aluminum and the like from becoming metaaluminate under the condition of directly improving the pH value to be higher so as to pollute the subsequent lithium carbonate products.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following brief description of the drawings of the embodiments will make it apparent that the drawings in the following description relate only to some embodiments of the present disclosure, not to limit the present disclosure.
FIG. 1 shows a flow chart of an industrial process for treating a solid material containing lithium iron phosphate according to the present application;
FIG. 2 shows a flow chart of a method of treating the lithium ion containing solution according to the present application;
FIG. 3 shows a schematic of a primary leach solid-liquid reactor;
FIG. 4 shows a schematic of a primary effluent liquid reactor;
Figure 5 shows a schematic diagram of a countercurrent leaching unit;
FIG. 6 shows a schematic diagram of a countercurrent precipitation unit;
reference numerals:
100-primary leaching solid-liquid reactor; 101-a first liquid feed inlet of a first-stage leaching solid-liquid contact device; 102-a solid feed inlet of a primary leaching solid-liquid contact device; 103-primary leaching reaction kettle; 104-a primary leaching stirring device; 105-a discharge port of the primary leaching solid-liquid contact equipment; 106-primary leaching plate-and-frame filter press; 107-primary leaching of the second stirring device; 108-primary leaching slurrying kettle; 109-a liquid discharge port of the primary leaching solid-liquid separation equipment; 110-a first-stage leaching slurrying kettle discharge port; 111-a feed inlet of a primary leaching solid-liquid separation device; 112-a second liquid feed inlet of the primary leaching solid-liquid contact equipment; 113-first-stage leaching solid-liquid separation equipment solid discharge port
200-a primary effluent liquid reactor; 201-a first-stage effluent liquid contacting device first liquid feed inlet; 202-a first-stage effluent liquid contacts a second liquid feed inlet of the device; 203-first-stage precipitation reaction kettle; 204-a primary precipitation stirring device; 205-a first-stage effluent liquid contacts a discharge port of the equipment; 206-first-stage precipitation plate-and-frame filter press; 207-first-stage precipitation of a second stirring device; 208-first-stage separation of a slurrying kettle; 209-a liquid discharge port of the first-stage precipitation solid-liquid separation equipment; 210-a first-stage precipitation slurrying kettle discharge port; 211-a feed inlet of a first-stage precipitation solid-liquid separation device; 213-first-stage precipitation solid-liquid separation equipment solid discharge port
300-countercurrent leaching unit; 301-countercurrent leaching contact apparatus first liquid feed inlet; 302-countercurrent leaching contact device second liquid feed inlet; 303-countercurrent leaching reaction kettle; 304-a countercurrent leaching stirring device; 305-countercurrent leaching contact equipment discharge port; 306-countercurrent leaching plate-and-frame filter press; 307-countercurrent leaching of the second stirring device; 308-countercurrent leaching of the slurrying kettle; 309-a liquid discharge port of the countercurrent leaching separation device; 310-countercurrent leaching pulper discharge port; 311-a feed inlet of a countercurrent leaching separation device; 312-countercurrent leaching contact equipment solid feed inlet; 313-countercurrent leaching separation equipment solid discharge port
400-countercurrent precipitation unit; 401-countercurrent precipitation contact apparatus first liquid feed inlet; 403-countercurrent precipitation reaction kettle; 404-countercurrent precipitation stirring device; 405-countercurrent precipitation contact equipment discharge port; 406-countercurrent precipitation of a plate-and-frame filter press; 407-countercurrent precipitation of a second stirring device; 408-separating out the slurrying kettle in a countercurrent way; 409-liquid discharge port of countercurrent precipitation separation equipment; 410-countercurrent precipitation of a discharge port of the slurrying kettle; 411-countercurrent precipitation separation device feed inlet; 412-countercurrent precipitation contact apparatus solids feed inlet; 413-countercurrent precipitation separation equipment solid discharge port
Detailed Description
Terms in this application have meanings commonly understood by those skilled in the art unless explicitly stated to the contrary or contradicted by context. The term "substance containing lithium iron phosphate" or "substance containing lithium iron phosphate" in the present application
"solid matter containing lithium iron phosphate" is used interchangeably and has the meaning commonly understood by those skilled in the art, and in particular refers to lithium iron phosphate battery positive electrode material waste materials from a variety of sources, such as waste materials generated during the production of lithium iron phosphate batteries, e.g., lithium iron phosphate positive electrode powder waste materials and lithium iron phosphate positive electrode sheet waste materials, and lithium iron phosphate battery positive electrode waste materials produced by recycling after disposal of lithium iron phosphate batteries, these particular sources of lithium iron phosphate being collectively referred to herein as lithium iron phosphate battery recycled positive electrode materials. In actual use, the specific form of the "lithium iron phosphate-containing substance" or "lithium iron phosphate-containing solid substance" described herein is not limited, and may be other forms such as a slurried liquid for convenience of transportation.
In one aspect, the present application provides a method of treating a substance containing lithium iron phosphate, comprising the steps of: (1) Contacting the substance containing lithium iron phosphate with acid to perform a primary leaching reaction to obtain primary leaching liquid and primary leaching solid; (2) And (3) contacting the primary leaching solution with an oxidant to perform primary precipitation reaction to obtain primary precipitation solids and primary precipitation liquid, wherein the primary precipitation solids are solids containing ferric phosphate, and the primary precipitation liquid is a solution containing lithium ions. The terms primary, secondary, etc. are used herein for descriptive convenience only and are not intended to identify primary and secondary relationships for distinguishing between various reaction sites. The primary effluent may be used for recovering lithium, and the method for recovering lithium is not particularly limited, and may be performed according to the composition of the primary effluent actually obtained by a method known to those skilled in the art.
In general, the material containing lithium iron phosphate is a solid material, and may be a waste positive electrode powder obtained by disassembling and pulverizing a positive electrode from a waste lithium iron phosphate battery by a battery disassembling enterprise, for example, a waste positive electrode powder, a waste positive electrode sheet, and a waste positive electrode material of a lithium iron phosphate battery. The invention also provides an industrial method for treating a solid substance containing lithium iron phosphate, comprising the following steps:
(1) The solid matter is contacted with acid to carry out primary leaching reaction, so as to obtain primary leaching liquid and primary leaching solid;
(2) The first-stage leaching solution is contacted with an oxidant to carry out a first-stage precipitation reaction to obtain first-stage precipitation solid and first-stage precipitation liquid, wherein the first-stage precipitation solid is solid containing ferric phosphate, the first-stage precipitation liquid is solution containing lithium ions,
wherein the weight of the solid material to the total weight of the liquid material entering the primary leaching reaction is from 1:3 to 1:5 ((e.g. from 1:3.5 to 1:4.5, for example 1:4)), the liquid material added to the reaction comprising the acid. The solid-liquid ratio in the primary leaching reaction is controlled in a proper range, so that the optimal industrial recovery efficiency can be obtained, the least waste liquid is generated, and almost all solid products are recovered, thus the method is particularly suitable for industrial application. In some embodiments, the molar ratio of the hydrogen ions available for reaction in the acid to the iron in the lithium iron phosphate-containing material is (1.1-1.3) 1, or the molar ratio of the hydrogen ions available for reaction in the acid to the lithium in the lithium iron phosphate-containing material is (1.1-1.3) 1. The ranges "(1.1 to 1.3): 1" and the like in this application have meanings commonly understood by those skilled in the art, and refer to ranges from the lower limit of 1.1:1 to the upper limit of 1.3:1, inclusive. The industrial process described herein means that the reactants employed can be added in an amount of 1 ton or more. In particular, the industrial process described herein refers to a process capable of handling tons of solid matter containing lithium iron phosphate.
The invention also provides an industrial method for treating a solid substance containing lithium iron phosphate, comprising the following steps:
(1) The solid matter is contacted with acid to carry out primary leaching reaction, so as to obtain primary leaching liquid and primary leaching solid;
(2) The first-stage leaching solution is contacted with an oxidant to carry out a first-stage precipitation reaction to obtain first-stage precipitation solid and first-stage precipitation liquid, wherein the first-stage precipitation solid is solid containing ferric phosphate, the first-stage precipitation liquid is solution containing lithium ions,
wherein the molar ratio of the hydrogen ions which can react in the acid to the iron in the substance containing lithium iron phosphate is (1.1 to 1.3) 1, or the molar ratio of the hydrogen ions which can react in the acid to the lithium in the substance containing lithium iron phosphate is (1.1 to 1.3) 1.
The proper acid addition amount is controlled in the primary leaching reaction, so that the pH value automatically rises to the precipitation point of the ferric phosphate in the primary precipitation reaction process, and the pH value in the primary precipitation reaction does not need to be regulated. Generally, the amount of acid added is consumed during the oxidation reaction, which corresponds to the amount of ferrous ions, and a slight excess is required, so that during the oxidation reaction, iron phosphate is formed while the pH rises to around 3, so that iron phosphate naturally precipitates out, while other metals remain in solution, so that high purity iron phosphate can be obtained while iron is sufficiently separated from other metal ions such as lithium ions. In some embodiments, since the number of moles of ferrous ions in a general lithium iron phosphate battery is approximately equal to the number of moles of lithium ions, the industrial method of solid matter containing lithium iron phosphate also contains approximately equal numbers of moles of lithium and ferrous ions, and therefore, in this case, the addition of acid may be performed in accordance with the molar amount of lithium.
The primary leaching reaction described herein is not a term commonly used in the art and refers in this application to the reaction that occurs by contacting the lithium iron phosphate-containing material with an acid. The essence of this reaction is generally that the lithium iron phosphate is dissolved in an acid and the chemical reaction takes place as follows:
LiFePO 4 ↓+2H + ＝Li + +Fe 2+ +H 2 PO 4 -
the primary leach reaction described herein is not a term commonly used in the art and in this application refers to a reaction that occurs when the primary leach solution is contacted with an oxidizing agent. The essential content of the reaction is that ferrous ions are oxidized to be ferric ions to form ferric phosphate precipitates, and the chemical reaction is as follows (taking hydrogen peroxide as an oxidant for example):
H 2 O 2 +2Fe 2+ +2H 2 PO 4 - ＝2H 2 O+2H + +2FePO 4 ↓
in one embodiment, the method further comprises: and carrying out multistage countercurrent leaching treatment (such as secondary countercurrent treatment) on the primary leached solids by adopting a first washing liquid to obtain countercurrent leaching liquid and countercurrent leached solids, and returning the countercurrent leaching liquid to the primary leaching reaction. Thus, the liquid material entering the primary leaching reaction also includes the first wash liquor. The first washing liquid is not particularly limited as long as a good leaching effect can be produced, and in general, an aqueous liquid or an aqueous liquid such as water can be used. The primary leaching solid is a product obtained after the primary leaching reaction of the substance containing the lithium iron phosphate, and is usually mainly composed of carbon powder, and a small amount of lithium iron phosphate which does not completely participate in the primary leaching reaction is subjected to multi-stage countercurrent leaching, so that the recovery rate of phosphorus, iron and lithium can be improved, and meanwhile, the purity of the countercurrent leaching solid is improved. As used herein, the term "multistage countercurrent leaching process" refers to countercurrent treatment of primary leached solids after a primary leaching reaction, wherein the reaction does not necessarily occur as well as the primary leaching reaction.
In some embodiments, the method further comprises: and carrying out multistage countercurrent precipitation treatment on the first-stage precipitated solids by adopting a second washing liquid to obtain countercurrent precipitation liquid and countercurrent precipitation solids, and returning the countercurrent precipitation liquid to the first-stage leaching reaction and/or the multistage countercurrent leaching treatment. When the secondary countercurrent precipitation treatment is adopted, the primary reverse precipitation liquid and the secondary reverse precipitation solid are obtained after the multistage countercurrent precipitation. When three or more stages of countercurrent precipitation treatment are adopted, more lithium elements can be recovered, and meanwhile, the purity of the ferric phosphate is improved. The term "multistage countercurrent precipitation treatment" as used herein refers to countercurrent treatment of a primary precipitated solid after a primary precipitation reaction, wherein the reaction does not necessarily occur as the primary precipitation reaction. In the application, the countercurrent precipitation liquid is returned to the primary leaching reaction and/or the multistage countercurrent leaching treatment, so that the amount of liquid in the primary leaching reaction can be fully increased, the sufficiency of the reaction is increased, and the recovery efficiency is improved.
In some embodiments, the method further comprises: and (3) enabling the primary effluent to be in contact with alkali to obtain solid impurities and a lithium precipitation solution. The base described herein is not particularly limited as long as the reaction objective can be achieved. Typically the base may include sodium hydroxide and sodium carbonate. In practice, caustic soda flakes and small amounts of soda ash are often used. Without limiting the present application, for ease of understanding, in general, the chemical reactions that occur may be represented as follows:
Removing impurities: fe (Fe) 3+ +3OH - ＝Fe(OH) 3 ↓
Ni 2+ +2OH - ＝Ni(OH) 2 ↓
Mg 2+ +2OH - ＝Mg(OH) 2 ↓
Cu 2+ +2OH - ＝Cu(OH) 2 ↓
Al 3+ +3OH - ＝Al(OH) 3 ↓
Ca 2+ +CO 3 2- ＝CaCO 3 ↓
In some embodiments, the method further comprises: and (3) contacting the lithium precipitation solution with sodium carbonate to obtain lithium carbonate precipitation and lithium-containing tail liquid. The specific chemical reaction equation of this reaction can be expressed as follows:
precipitating lithium: 2Li + +CO 3 2- ＝Li 2 CO 3 ↓
In some embodiments, phosphate-containing substances can be optionally added to the lithium-containing tail solution after the lithium precipitation reaction, and lithium can be further recovered, and the chemical reaction can be represented as follows:
and (3) recycling: PO (Positive oxide) 4 3- +3Li + ＝Li 3 PO 4 ↓
In some embodiments, the method further comprises: in the multistage countercurrent leaching process, acid is added. In the multistage countercurrent leaching treatment, in order to leach the lithium iron phosphate more completely, acid can be added to adjust the pH value, so that the leaching reaction is more complete, the yield is improved, and the efficiency of the countercurrent leaching reaction is improved. Generally, only two-step reverse leaching reaction is needed to complete the reverse leaching reaction more completely. After the reverse leaching step is adopted, the lithium iron phosphate which is not completely leached in the first-stage leaching reaction can be submitted to the reverse leaching step to be completed, so that the reaction time of the first-stage leaching reaction is shortened, the reaction efficiency of the first-stage leaching reaction is improved, and the reaction efficiency of the whole reaction is improved.
In some embodiments, the method further comprises: in the multistage countercurrent precipitation process, an oxidizing agent is added. In the multistage countercurrent precipitation process, an oxidizing agent may be added to more completely convert ferrous ions that may be present in the primary precipitated solids into ferric ions, improving the yield, and improving the efficiency of the reverse precipitation reaction. Generally, only two-step reverse reaction is required to more completely complete the reverse reaction. After the reverse precipitation step is adopted, the ferrous iron which is not completely converted in the first-stage precipitation reaction can be submitted to the reverse precipitation step to be completed, so that the purity of the ferric phosphate is further improved, the reaction time of the first-stage precipitation reaction is shortened, the reaction efficiency of the first-stage precipitation reaction is improved, and the reaction efficiency of the whole reaction is improved.
In some embodiments, the lithium iron phosphate-containing substance comprises at least one selected from the group consisting of: lithium iron phosphate positive electrode powder waste, lithium iron phosphate positive electrode sheet waste and lithium iron phosphate battery positive electrode waste. As described herein, the feedstock employed in the process of the present application is primarily of the above sources, and these sources are particularly suitable for the process of the present application.
In the present application, the specific reaction time of the primary leaching reaction and the primary precipitation reaction is not limited as long as the reaction purpose is achieved. In general, in order to balance the efficiency and reaction completeness, in some embodiments, the reaction time of the primary leaching reaction is 0.1 to 3 hours (e.g., 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, etc., each of the above time points may be freely combined to form an individual range independently), and the reaction time of the primary leaching reaction is 1 to 3 hours (e.g., 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 2.8 hours, 2.9 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.3 hours, 2.6 hours, 2.8 hours, 2.3 hours, 2.6 hours, 2.3 hours, 2.6 hours, etc., each of the individual ranges may be formed independently.
In the present application, the reaction time of each stage in the multistage countercurrent leaching treatment is not limited as long as the reaction purpose can be achieved and the reaction can be performed in combination with the whole reaction. In some embodiments, the reaction time of each stage in the multistage countercurrent leaching process is 0 to 1 hour, for example, 0.1 hour, 0.2 hour, 0.3 hour, 0.4 hour, 0.5 hour, 0.6 hour, 0.7 hour, 0.8 hour, 0.9 hour 0, etc., and each of the above-described time points can be freely combined independently to form a separate range.
In the present application, the reaction time of each stage in the multistage countercurrent precipitation treatment is not limited as long as the reaction objective can be achieved and the reaction can be performed in combination with the whole reaction. In some embodiments, the reaction time of each stage in the multistage countercurrent chromatography is 0 to 1 hour, for example, 0.1 hour, 0.2 hour, 0.3 hour, 0.4 hour, 0.5 hour, 0.6 hour, 0.7 hour, 0.8 hour, 0.9 hour 0, etc., and the above-described respective time points may be freely combined to form a separate range independently.
In the present application, the type and amount of the oxidizing agent to be used are not particularly limited as long as the object of the present application can be achieved. In some embodiments, the molar equivalent of the oxidizing agent is equivalent to the amount of acid employed in the primary leach solution, e.g., the oxidizing agent is hydrogen peroxide, the molar ratio of hydrogen peroxide to lithium ions in the reaction solution is (0.55-0.65): 1, or the molar ratio of hydrogen peroxide to ferrous ions in the reaction solution is (0.55-0.65): 1. That is, the molar ratio of the oxidation equivalent of the oxidizing agent to the ferrous iron in the reaction solution is (1.1 to 1.3): 1. Such an amount of the oxidizing agent matches the amount of the acid to be used and is appropriately excessive with respect to the divalent iron so that the oxidation reaction can be sufficiently performed.
In some embodiments, the primary leaching reaction is at a pH of 0 to 2 (e.g., 1 to 2), and the primary precipitation reaction is at a pH ranging from a first 0-2 to a final 2.5 to 3.5. The amount of the reactants in the reaction is controlled within a proper range, so that the pH control effect can be achieved, and as much ferric phosphate as possible can be naturally precipitated in the oxidation process, thereby being fully separated.
In the present application, the reaction conditions for carrying out the primary leaching reaction and the primary precipitation are not particularly limited as long as the reaction purpose can be achieved. In some embodiments, the primary leaching reaction is at a pH of 0 to 2 (e.g., 0.5 or 1) and the primary precipitation reaction is at a pH of 0 to 3 (e.g., 0.5, 1, 1.5 or 2). The pH value of the primary leaching reaction is in the range, so that the lithium iron phosphate can be fully dissolved to be in an ionic state, and carbon powder and lithium iron phosphate are separated; in a preferred embodiment, the pH is 1 or less and the lithium iron phosphate is capable of almost complete dissolution. The pH value of the primary precipitation reaction is in the range, and the iron ions can be well oxidized to form ferric phosphate precipitates so as to be separated from the lithium ion solution; in a preferred embodiment, the pH is in the range of 1 to 3, the iron 2 is sufficiently oxidized to ferric iron and forms ferric phosphate precipitates, too low a pH results in partial dissolution of ferric phosphate, which affects recovery of ferric ions, and too high a pH results in precipitation of ferrous iron, which cannot be oxidized to ferric iron, and lithium iron phosphate precipitates, which affect recovery of lithium ions.
In some embodiments, "contacting the primary effluent with a base" includes contacting the primary effluent with sodium hydroxide at a pH greater than 10 (e.g., greater than 11, greater than 12, greater than 13, or greater than 14), and adding sodium carbonate in an amount of 1 to 2 times (e.g., 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times) the moles of calcium ions in the primary effluent. The various numerical values set forth above, as well as those set forth elsewhere in this application, when used in describing the same descriptive object, may each independently be freely combined to form a single range.
In the lithium precipitation reaction, the amount of sodium carbonate to be used is not limited as long as the reaction object of the present application can be achieved. In some embodiments, the molar ratio of the amount of sodium carbonate used in the "contacting the lithium precipitating solution with soda" step to the lithium ions in the lithium precipitating solution is (0.5 to 0.55): 1, for example 0.51:1,0.52:1,0.53:1,0.54:1, each of the values mentioned above being independently free to be combined to form a separate range.
In the present application, the specific conditions for the lithium precipitation reaction are not limited, and those skilled in the art can adjust according to the specific reactants used and the reaction purpose to be achieved. In a particularly advantageous embodiment, the step of "contacting the lithium precipitation solution with sodium carbonate" is carried out at a temperature of 55-95 degrees celsius for 1-4 hours.
In some embodiments, the method further comprises adding trisodium phosphate to the lithium-containing tail solution or adding sodium carbonate after evaporation concentration to obtain lithium phosphate solids or lithium carbonate and brine wastewater.
The method of the present invention can produce a particularly advantageous iron phosphate product for a battery, and thus, another aspect of the present invention also provides an iron phosphate containing 0.05% or more of lithium, 0.01% or less of calcium, 0.01% or less of magnesium, 0.01% or less of copper, and 0.01% or less of aluminum. The iron phosphate precipitate prepared by the method of the present invention contains a small amount of lithium ions because of the high content of lithium ions in the prepared environment, and these lithium ions do not have any adverse effect in the process of using iron phosphate for preparing a lithium iron phosphate battery, but conversely, the quality of the lithium iron phosphate battery can also be improved.
In some embodiments, the iron phosphate contains greater than or equal to 0.10%, greater than or equal to 0.15%, or 0.20% lithium. Since the presence of lithium does not reduce the quality of iron phosphate, but rather increases the quality of lithium phosphate for batteries, it is a preferred product even if the iron phosphate contains a certain amount of lithium.
In some embodiments, the iron phosphate contains 0.005% or less or 0.0035% or less of calcium. The iron phosphate produced by the method of the present invention contains little calcium because calcium ions do not precipitate out in the environment in which the iron phosphate is precipitated.
In some embodiments, the iron phosphate contains less than or equal to 0.005%, or less than or equal to 0.003%, or less than or equal to 0.0012% magnesium. The iron phosphate prepared by the method of the present invention contains little magnesium because magnesium ions do not precipitate out in the environment where the iron phosphate is precipitated.
In some embodiments, the iron phosphate contains less than or equal to 0.001%, or less than or equal to 0.0005%, or less than or equal to 0.0001% copper. The iron phosphate prepared by the method of the present invention contains little copper because copper ions do not precipitate out in the environment where the iron phosphate is precipitated.
In some embodiments, the iron phosphate contains less than or equal to 0.005%, or less than or equal to 0.003%, or less than or equal to 0.0016% aluminum. The iron phosphate produced by the method of the present invention contains little aluminum because aluminum does not precipitate in the environment in which the iron phosphate is precipitated.
In some embodiments, the iron phosphate is iron phosphate dihydrate, containing 28% to 31% iron, or 29% to 30% iron. The iron element content range of the ferric phosphate dihydrate with higher purity is within the above range.
In some embodiments, the iron phosphate is prepared by an industrial process as described in any one of the present applications.
In some embodiments, the iron phosphate contains less than or equal to 1% lithium ions, such as less than or equal to 0.5% lithium ions, such as less than or equal to 0.4% lithium ions, such as less than or equal to 0.3% lithium ions. The content of lithium ions in the iron phosphate prepared by the method of the present invention is far lower than the initial content thereof because lithium ions are not easily precipitated in the environment where iron phosphate is precipitated. The more lithium present therein is mainly the iron phosphate which is entrained by the solution.
In the art, solutions containing lithium ions often contain various impurities such as iron entrained from lithium iron phosphate, aluminum and copper entrained from battery waste, calcium and magnesium entrained from tap water, and the like. Therefore, a step of removing impurities is often performed before lithium precipitation. However, the different impurity ions are not easily completely removed in the same impurity removal step, and if the products obtained by the impurity removal in the same step are mixtures, the value is extremely low and even a large amount of solid waste disposal costs are required. Accordingly, the present application provides a multi-step process for removing impurities.
In particular, another aspect of the present invention provides a method of treating a solution containing lithium ions having a pH of less than 4, comprising:
contacting the solution containing lithium ions with a first base to raise the pH value to a first pH value and maintaining the pH value for a first time to obtain a first precipitate and a first lithium purification solution;
contacting the first lithium purified solution with a second base to raise the pH to a second pH and for a second time to obtain a second precipitate and a second lithium purified solution;
and (3) contacting the second lithium purified solution with a third base to raise the pH value to a third pH value and maintaining the pH value for a third time to obtain a third precipitate and a third lithium purified solution.
In one embodiment, the method further comprises: and contacting the third lithium purified solution with ion exchange resin to obtain a fourth lithium purified solution.
In one embodiment, the method further comprises: and reacting the fourth lithium purified solution with sodium carbonate to obtain lithium carbonate precipitate.
In one embodiment, the first pH is a number from 4 to less than 6 and the first time is 30 minutes or more. The lithium ion-containing solutions obtained from leaching and precipitation reactions of solid materials containing lithium iron phosphate tend to contain a high proportion of iron ions, which precipitate almost completely at pH values of 4 to 6, while other ions do not precipitate at such low pH values. Thus, in this step, the pH is first raised to a value of 4 or more and less than 6, and the first precipitate obtained contains more than 90% of iron phosphate which, although not reaching battery grade, is still commercially valuable as technical grade iron phosphate. The iron phosphate precipitate generally contains iron hydroxide, magnesium hydroxide, copper hydroxide, aluminum hydroxide, and the like.
In one embodiment, the second pH is a number from 6 to 8, and the second time is 30 minutes or more. At this pH, calcium ions from components such as tap water can usually be precipitated, in which case the main component is calcium hydroxide precipitate. The calcium hydroxide precipitate generally contains iron hydroxide, magnesium hydroxide, copper hydroxide, aluminum hydroxide, and the like.
In one embodiment, the third pH is a number of 11 or greater and the third time is 30 minutes or greater. Sodium hydroxide is usually used to raise the pH to 11, and small amounts of sodium carbonate may be added. At this pH, calcium ions precipitate out as calcium carbonate, which is the main ingredient, containing small amounts of calcium hydroxide impurities.
In some embodiments, the ion exchange resin in the method is a cation-anion mixed resin. The yin-yang blend resins are commercially available, for example, from Jiangsu Su Qing, german Bayer, american Dow, and the like. The cation-anion mixed resin can also adopt a resin barrel (column) which is formed by connecting a cation resin and an anion resin in series.
In some embodiments, the first base in the method comprises at least one selected from the group consisting of lithium carbonate, lithium hydroxide, and sodium hydroxide.
In some embodiments, the second base in the method comprises at least one selected from sodium hydroxide and lithium hydroxide.
In some embodiments, the third base in the method comprises: at least one selected from sodium hydroxide and lithium hydroxide, and at least one selected from sodium carbonate and lithium carbonate.
In some embodiments, the lithium ion-containing solution in the method is obtained by contacting a lithium battery recycle with an acid.
The application also provides a reaction device which is characterized by comprising a primary leaching solid-liquid reactor, a primary leaching liquid-liquid reactor and a multi-stage countercurrent precipitation system;
the primary leaching solid-liquid reactor comprises a primary leaching solid-liquid contact device and a primary leaching solid-liquid separation device,
the primary leaching solid-liquid contact equipment is provided with a primary leaching solid-liquid contact equipment feed inlet and a primary leaching solid-liquid contact equipment discharge outlet, the primary leaching solid-liquid separation equipment is provided with a primary leaching solid-liquid separation equipment feed inlet, a primary leaching solid-liquid separation equipment liquid discharge outlet and a primary leaching solid-liquid separation equipment solid discharge outlet,
The discharge port of the primary leaching solid-liquid contact equipment is connected with the feed port of the primary leaching solid-liquid separation equipment,
the primary effluent liquid-liquid reactor comprises a primary effluent liquid-liquid contact device and a primary effluent solid-liquid separation device,
the primary separation solid-liquid separation equipment is provided with a primary separation solid-liquid separation equipment feed inlet, a primary separation solid-liquid separation equipment liquid discharge outlet and a primary separation solid-liquid separation equipment solid discharge outlet,
the discharge port of the primary precipitation liquid-liquid contact equipment is connected with the feed port of the primary precipitation solid-liquid separation equipment,
the liquid outlet of the primary leaching solid-liquid separation device is connected with the feed inlet of the primary leaching liquid-liquid contact device;
the multistage countercurrent precipitation system comprises N countercurrent precipitation units, wherein an ith countercurrent precipitation unit comprises: countercurrent precipitation contact equipment and countercurrent precipitation separation equipment, wherein N is an integer greater than or equal to 2, i is an integer from 1 to N,
wherein the countercurrent precipitation contact equipment is provided with a countercurrent precipitation contact equipment feed inlet and a countercurrent precipitation contact equipment discharge outlet, the countercurrent precipitation separation equipment is provided with a countercurrent precipitation separation equipment feed inlet, a countercurrent precipitation separation equipment liquid discharge outlet and a countercurrent precipitation separation equipment solid discharge outlet,
The discharge port of the countercurrent precipitation contact device is connected with the feed port of the countercurrent precipitation separation device,
wherein, for the ith countercurrent precipitation unit,
when N > i >1 (i and N are integers, and N is an integer greater than or equal to 2), the feed inlet of the countercurrent precipitation contact device is connected with the liquid discharge outlet of the countercurrent precipitation separation device of the (i+1) th countercurrent precipitation unit and is connected with the solid discharge outlet of the countercurrent precipitation separation device of the (i-1) th countercurrent precipitation unit;
when i=n, the countercurrent precipitation contact device feed inlet is connected with the countercurrent precipitation separation device solid discharge outlet of the i-1 st countercurrent precipitation unit and with the external feed device of the second wash liquor;
when i=1, the feed inlet of the countercurrent precipitation contact device is connected with the liquid discharge outlet of the countercurrent precipitation separation device of the 2 nd countercurrent precipitation unit and is connected with the solid discharge outlet of the primary precipitation solid-liquid separation device. And the liquid discharge port of the countercurrent precipitation separation device is connected with the primary leaching solid-liquid contact device.
In some embodiments, the reaction apparatus further comprises a multi-stage countercurrent leaching system comprising N countercurrent leaching units, wherein the ith countercurrent leaching unit comprises: countercurrent leaching contact equipment and countercurrent leaching separation equipment, wherein N is an integer greater than or equal to 2, i is an integer from 1 to N,
Wherein the countercurrent leaching contact equipment is provided with a countercurrent leaching contact equipment feed inlet and a countercurrent leaching contact equipment discharge outlet, the countercurrent leaching separation equipment is provided with a countercurrent leaching separation equipment feed inlet, a countercurrent leaching separation equipment liquid discharge outlet and a countercurrent leaching separation equipment solid discharge outlet,
the discharge port of the countercurrent leaching contact device is connected with the feed port of the countercurrent leaching separation device,
wherein, for the ith countercurrent leaching unit,
when N > i >1, the feed inlet of the countercurrent leaching contact device is connected with the liquid discharge outlet of the countercurrent leaching separation device of the (i+1) th countercurrent leaching unit and is connected with the solid discharge outlet of the countercurrent leaching separation device of the (i-1) th countercurrent leaching unit;
when i=n, the countercurrent leaching contact device feed inlet is connected with the countercurrent leaching separation device solid discharge port of the i-1 st countercurrent leaching unit and with the external feed device of the first washing liquid;
when i=1, the countercurrent leaching contact device feed inlet is connected with the countercurrent leaching separation device liquid discharge outlet of the (i+1) th countercurrent leaching unit and is connected with the primary leaching solid-liquid separation device solid discharge outlet. The liquid outlet of the countercurrent leaching separation device is connected with the primary leaching solid-liquid contact device.
In some embodiments, in the reaction apparatus, when i < N, the countercurrent leaching unit further comprises an acid feed port.
In some embodiments, in the reaction apparatus, the countercurrent precipitation separation device liquid discharge port of the 1 st countercurrent precipitation unit of the multistage countercurrent precipitation system is in countercurrent leaching with the multistageThe countercurrent leaching contact apparatus of the 1 st countercurrent leaching unit of the outlet system is connected to be connected to the primary leaching in this waySolid-liquid contactAn apparatus.
The invention will be further understood by the following examples.
Examples
Example 1
The embodiment firstly provides a reaction device which comprises a primary leaching solid-liquid reactor (100), a primary leaching liquid-liquid reactor (200), a multi-stage countercurrent leaching system and a multi-stage countercurrent precipitation system;
as shown in fig. 3, the primary leaching solid-liquid reactor (100) comprises a left primary leaching solid-liquid contact device and a right primary leaching solid-liquid separation device,
the primary leaching solid-liquid contact equipment comprises a primary leaching reaction kettle (103), the primary leaching reaction kettle (103) is connected with a primary leaching solid-liquid contact equipment first liquid feed inlet (101) (used for adding primary reverse leaching liquid), a primary leaching solid-liquid contact equipment second liquid feed inlet (112) (used for adding acid), a primary leaching solid-liquid contact equipment solid feed inlet (102) (used for adding substances containing lithium iron phosphate) and a primary leaching solid-liquid contact equipment discharge outlet (105), and the primary leaching reaction kettle (103) is also provided with a primary leaching stirring device (104);
The primary leaching solid-liquid separation equipment comprises a primary leaching plate-and-frame filter press (106) and a primary leaching slurrying kettle (108), wherein the primary leaching plate-and-frame filter press (106) is connected with a primary leaching solid-liquid separation equipment feed inlet (111), a primary leaching solid-liquid separation equipment solid discharge outlet (113) and a primary leaching solid-liquid separation equipment liquid discharge outlet (109), the primary leaching solid-liquid separation equipment solid discharge outlet (113) is connected with the primary leaching slurrying kettle (108), the primary leaching slurrying kettle (108) is provided with a primary leaching second stirring device (107), and the primary leaching slurrying kettle (108) is provided with a primary leaching slurrying kettle discharge outlet (110);
the discharge port (105) of the primary leaching solid-liquid contact equipment is connected with the feed port (111) of the primary leaching solid-liquid separation equipment.
As shown in fig. 4, the primary effluent liquid reactor (200) comprises a primary effluent liquid contacting device on the left side and a primary effluent solid-liquid separating device on the right side,
the primary precipitation liquid-liquid contact equipment comprises a primary precipitation reaction kettle (203), the primary precipitation reaction kettle (203) is connected with a primary precipitation liquid-liquid contact equipment first liquid feed inlet (201) (used for adding primary leaching liquid), a primary precipitation liquid-liquid contact equipment second liquid feed inlet (202) (used for adding oxidant) and a primary precipitation liquid-liquid contact equipment discharge outlet (205), and the primary precipitation reaction kettle (203) is also provided with a primary precipitation stirring device (204);
The first liquid feed inlet (201) of the first-stage leaching liquid-liquid contact device is connected with the liquid discharge outlet (109) of the first-stage leaching solid-liquid separation device.
The primary precipitation solid-liquid separation equipment comprises a primary precipitation plate-and-frame filter press (206) and a primary precipitation slurrying kettle (208), the primary precipitation plate-and-frame filter press (206) is connected with a primary precipitation solid-liquid separation equipment feed inlet (211), a primary precipitation solid-liquid separation equipment solid discharge outlet (213) and a primary precipitation solid-liquid separation equipment liquid discharge outlet (209), the primary precipitation solid-liquid separation equipment solid discharge outlet (213) is connected with the primary precipitation slurrying kettle (208), the primary precipitation slurrying kettle (208) is connected with a primary precipitation second stirring device (207), and the primary precipitation slurrying kettle (208) is provided with a primary precipitation slurrying kettle discharge outlet (210);
the discharge port (205) of the primary precipitation liquid-liquid contact equipment is connected with the feed port (211) of the primary precipitation solid-liquid separation equipment.
The liquid outlet (109) of the primary leaching solid-liquid separation device is connected with the first liquid inlet (201) of the primary leaching liquid-liquid contact device.
The multi-stage countercurrent leaching system comprises two stages of countercurrent leaching units, namely two countercurrent leaching units (300);
as shown in fig. 5, the countercurrent leaching unit (300) includes a countercurrent leaching contact apparatus on the left side and a countercurrent leaching separation apparatus on the right side;
The countercurrent leaching contact device comprises a countercurrent leaching reaction kettle (303), the countercurrent leaching reaction kettle (303) is connected with a countercurrent leaching contact device first liquid feed inlet (301), a countercurrent leaching contact device second liquid feed inlet (302), a countercurrent leaching contact device solid feed inlet (312) (for receiving leached solids) and a countercurrent leaching contact device discharge outlet (305), and the reaction kettle (303) is also provided with a stirring device (304);
the countercurrent leaching separation device comprises a countercurrent leaching plate-and-frame filter press (306) and a countercurrent leaching slurrying kettle (308), wherein the countercurrent leaching plate-and-frame filter press (306) is connected with a countercurrent leaching separation device feed inlet (311), a countercurrent leaching separation device solid discharge outlet (313) and a countercurrent leaching separation device liquid discharge outlet (309), the countercurrent leaching separation device solid discharge outlet (313) is connected with the countercurrent leaching slurrying kettle (308), the countercurrent leaching slurrying kettle (308) is provided with a countercurrent leaching second stirring device (307), and the countercurrent leaching slurrying kettle (308) is provided with a countercurrent leaching slurrying kettle discharge outlet (310); the discharge port (305) of the countercurrent leaching contact device is connected with the feed port (311) of the countercurrent leaching separation device;
for the first stage countercurrent leaching unit (300), a solid feed port (312) of the countercurrent leaching contact equipment is connected with a slurrying kettle discharge port (110) of the first stage leaching solid-liquid contact equipment, and a liquid discharge port (309) of the countercurrent leaching separation equipment is connected with a first liquid feed port (101) of the first stage leaching solid-liquid contact equipment; the countercurrent leaching slurrying kettle discharge port (310) is connected with the solid feed port (312) of the second-stage countercurrent leaching contact equipment, and the first liquid feed port (301) of the countercurrent leaching contact equipment is connected with the liquid discharge port (309) of the second-stage countercurrent leaching separation equipment;
For the second stage countercurrent leaching unit (300), a countercurrent leaching contact device solid feed port (312) is connected with a first stage slurrying kettle discharge port (310), and a countercurrent leaching separation device liquid discharge port (309) is connected with a first stage countercurrent leaching contact device first liquid feed port (301). The second stage countercurrent leaching unit (300) can be directly used as a product after the solid discharged by the countercurrent leaching plate-and-frame filter press (306) without arranging a countercurrent leaching slurrying kettle.
The multi-stage countercurrent precipitation system comprises two-stage countercurrent precipitation units, namely two countercurrent precipitation units (400);
as shown in fig. 6, the countercurrent precipitation unit (400) includes a countercurrent precipitation contact apparatus on the left side and a countercurrent precipitation separation apparatus on the right side;
the countercurrent precipitation contact equipment comprises a countercurrent precipitation reaction kettle (403), wherein the countercurrent precipitation reaction kettle (403) is connected with a countercurrent precipitation contact equipment first liquid feed inlet (401), a countercurrent precipitation contact equipment solid feed inlet (412) and a countercurrent precipitation contact equipment discharge outlet (405), and the countercurrent precipitation reaction kettle (403) is also provided with a countercurrent precipitation stirring device (404);
the countercurrent precipitation separation equipment comprises a plate countercurrent precipitation frame filter press (406) and a countercurrent precipitation slurrying kettle (408), wherein the countercurrent precipitation plate frame filter press (406) is connected with a countercurrent precipitation separation equipment feed inlet (411), a countercurrent precipitation separation equipment solid discharge outlet (413) and a countercurrent precipitation separation equipment liquid discharge outlet (409), the countercurrent precipitation separation equipment solid discharge outlet (413) is connected with the countercurrent precipitation slurrying kettle (408), the countercurrent precipitation slurrying kettle (408) is provided with a countercurrent precipitation second stirring device (407), and the countercurrent precipitation slurrying kettle (408) is provided with a countercurrent precipitation slurrying kettle discharge outlet (410);
The discharge hole (405) of the countercurrent precipitation contact device is connected with the feed hole (411) of the countercurrent precipitation separation device;
for the first stage countercurrent precipitation unit (400), a solid feed port (412) of the countercurrent precipitation contact device is connected with a slurrying kettle discharge port (210) of the first stage precipitation solid-liquid separation device, and a liquid discharge port (409) of the countercurrent precipitation separation device is connected with the countercurrent leaching contact device (or with the first stage leaching solid-liquid contact device) of the first stage countercurrent leaching unit; a discharge hole (410) of the countercurrent precipitation slurrying kettle is connected with a solid feed hole (412) of a second-stage countercurrent precipitation contact device, and a first liquid feed hole (401) of the countercurrent precipitation contact device is connected with a liquid discharge hole (409) of a second-stage countercurrent precipitation separation device;
for the second-stage countercurrent precipitation unit (400), a countercurrent precipitation contact device solid feed port (412) is connected with a countercurrent precipitation slurrying kettle discharge port (410) of the first-stage countercurrent precipitation unit (400), and a countercurrent precipitation separation device liquid discharge port (409) is connected with a countercurrent precipitation contact device first liquid feed port (401) of the first-stage countercurrent precipitation unit (400). The second stage countercurrent precipitation unit (400) can be directly used as a product after discharging solids of the countercurrent precipitation plate-and-frame filter press (306) without arranging a countercurrent leaching slurrying kettle.
As shown in fig. 1, the present embodiment provides a method for treating a substance containing lithium iron phosphate (the method generally including a leaching process, a process of precipitating iron phosphate, and a process of recovering lithium) by means of the above-described reaction apparatus, comprising the steps of:
(1) And adding lithium iron phosphate waste into the primary leaching solid-liquid reactor (100) through a solid feed inlet (102) of the primary leaching solid-liquid contact equipment, wherein the lithium iron phosphate waste comprises lithium iron phosphate positive electrode powder waste, lithium iron phosphate positive electrode plate waste and lithium iron phosphate battery positive electrode waste. The metal content in the lithium iron phosphate waste (lithium iron powder) used in particular is as follows:
adding an acidic solution with a certain concentration into a primary leaching solid-liquid reactor (100) through a second liquid feed inlet (112) of a primary leaching solid-liquid contact device, and uniformly stirring to obtain a reaction solution with a pH value of less than 2, wherein the acid is sulfuric acid or hydrochloric acid, the molar ratio of the reactive hydrogen ions in the acid to lithium in the lithium iron phosphate-containing substance is (1-1.5): 1, and the leaching reaction time is 1-3 hours, so as to obtain primary leaching liquid and primary leaching solid.
The chemical reactions that occur are as follows:
LiFePO 4 ↓+2H + ＝Li + +Fe 2+ +H 2 PO 4 -
the primary leachate contains Li generated after the reaction + 、Fe 2+ 、H 2 PO 4 - Ions, the primary leached solids including unreacted lithium iron phosphate and other impurities.
(2) Adding the primary leaching solution into a primary leaching solution reactor (200) through a first liquid feed inlet (201) of the primary leaching solution contact equipment, adding an oxidant through a second liquid feed inlet (202) of the primary leaching solution contact equipment, and carrying out primary precipitation reaction by contacting the primary leaching solution with the oxidant to obtain primary precipitated solid and primary leaching solution, wherein the oxidant can be hydrogen peroxide, and the molar ratio of the hydrogen peroxide to lithium ions in the reaction solution is (0.5-0.75): 1; the first-order precipitated solid is a solid (first product) containing ferric phosphate, and the first-order precipitated liquid is a solution containing lithium ions. The reaction time of the primary precipitation reaction is 1-3 hours.
The chemical reactions that occur are as follows:
H 2 O 2 +2Fe 2+ +2H 2 PO 4 - ＝2H 2 O+2H + +2FePO 4 ↓
the purpose of this step is mainly to retrieve the ferric phosphate solid, and further promoted the purity of lithium ion in the solution, be favorable to the recycle of lithium.
(3) And (3) adopting a multistage countercurrent leaching system, carrying out multistage countercurrent leaching treatment (in the embodiment, secondary countercurrent leaching treatment) on the primary leached solids by using water as a first washing liquid, wherein the treatment time of each stage is 0-1 hour, obtaining countercurrent leaching liquid (namely primary countercurrent leaching liquid) and countercurrent leached solids (namely secondary countercurrent leaching solids), and introducing the countercurrent leaching liquid into the primary leaching solid-liquid reactor. And the countercurrent leaching solids are unreacted solid residues, and the unreacted solid residues are collected by a container to obtain carbon powder which is a first solid product.
The purpose of this step is to fully react the unreacted lithium iron phosphate solids in the primary leach solids. In order to make the reaction more complete and further improve the reaction efficiency and yield, an appropriate amount of acid solution can be added in each stage of countercurrent leaching treatment equipment through a countercurrent leaching contact equipment second liquid feed inlet (302).
The chemical reaction occurring in this step is the same as that of step (1), namely:
LiFePO 4 ↓+2H + ＝Li + +Fe 2+ +H 2 PO 4 -
through multistage countercurrent leaching reaction, lithium iron phosphate in lithium iron phosphate waste can be fully reacted, the yield is improved, and meanwhile, the efficiency of the primary leaching reaction can be improved, because the multistage countercurrent leaching reaction is adopted, the primary leaching reaction can be completed by transferring the later stage of the reaction with lower reaction efficiency to the multistage countercurrent leaching reaction.
(4) And (3) adopting a multistage countercurrent precipitation system, carrying out multistage countercurrent precipitation treatment (in the embodiment, secondary countercurrent precipitation treatment) on the primary precipitated solid by using water as a second washing liquid, wherein the treatment time of each stage is 0-1 hour, obtaining countercurrent precipitation liquid (namely primary reverse precipitation liquid) and countercurrent precipitated solid (namely secondary reverse precipitation solid), and introducing the countercurrent precipitation liquid into a primary countercurrent leaching contact device, and finally entering the primary leaching solid-liquid contact device. The main component of the countercurrent precipitation solid is ferric phosphate, which is collected as a second product. Wherein, the content of various ions in the ferric phosphate is as follows:
The purpose of this step is to allow the unreacted solution entrained in the primary precipitated solids to react well and then return to the primary leaching reaction.
(5) And subjecting the primary effluent to a multi-step impurity removal process to obtain solid impurities and a lithium precipitation solution.
In this example, as shown in fig. 2, three steps are employed to raise the pH, and a fourth step employs an ion exchange resin to separate trace amounts of impurity ions, ultimately obtaining a highly pure lithium precipitation solution and three different precipitations. The multi-step method for improving the pH value and removing impurities not only can lead the purity of the impurity precipitation to be higher and obtain various different impurity precipitation with commercial utilization value, but also can prevent amphoteric metals such as aluminum and the like from becoming metaaluminate under the condition of directly improving the pH value to be higher so as to pollute the subsequent lithium carbonate products.
In this embodiment, the first-stage effluent is a solution containing lithium ions, and the impurity removal treatment includes:
contacting the solution containing lithium ions with a first base to raise the pH to a first pH to obtain a first precipitate and a first lithium purification liquid (or primary lithium purification liquid); the first base includes at least one selected from lithium carbonate and sodium carbonate. The lithium carbonate comes from lithium-containing mother solution obtained after lithium precipitation and washing, so that loss of lithium ions can be reduced, the lithium ions can be recovered to the greatest extent, and the recovery rate of the lithium ions is improved.
Contacting the first lithium purified solution with a second base to raise the pH to a second pH to obtain a second precipitate and a second lithium purified solution (or referred to as a secondary lithium purified solution); the second base is sodium hydroxide.
The second lithium purification liquid is contacted with a third base, which is a combination of sodium hydroxide and sodium carbonate, to raise the pH to a third pH to obtain a third precipitate and a third lithium purification liquid (or referred to as a tertiary lithium purification liquid).
Further comprises: contacting the third lithium purification liquid with ion exchange resin to obtain a fourth lithium purification liquid, namely a precipitated lithium solution, which can also be called as a resin purified lithium purification liquid,
wherein the first pH value is 5. The first precipitate obtained contains greater than 90% of iron phosphate which, although not as grade, is still commercially valuable as technical grade iron phosphate. The iron phosphate precipitate further contains iron hydroxide, magnesium hydroxide, copper hydroxide, aluminum hydroxide, and the like.
Wherein the second pH value is 7. The obtained precipitate contains calcium hydroxide as main component, wherein the content of calcium hydroxide is more than 90%. The calcium hydroxide precipitate further contains iron hydroxide, magnesium hydroxide, copper hydroxide, aluminum hydroxide, and the like.
Wherein the third pH value is 12. The alkali used is sodium hydroxide, and a small amount of sodium carbonate can be added. The obtained precipitate contains calcium carbonate with a content of more than 90% and contains a small amount of calcium hydroxide impurities.
Wherein the ion exchange resin is a commercial anion-cation mixed resin. The yin-yang blend resins are commercially available, for example, from Jiangsu Su Qing, german Bayer, american Dow, and the like.
The pH and metal ion content of the solution during the removal of the impurities are shown in the following table:
(6) And (3) contacting the lithium precipitation solution with sodium carbonate, and reacting for 1-4 hours at 55-95 ℃ to obtain lithium carbonate precipitation (third product) and lithium-containing tail liquid (or lithium-containing mother liquid). The molar ratio of the sodium carbonate to the lithium ions in the lithium precipitation solution is (0.5-0.55): 1. the third product may be further purified by washing with pure water.
The chemical reactions that occur are as follows:
2Li + +CO 3 2- ＝Li 2 CO 3 ↓
(7) And adding sodium carbonate into the lithium-containing tail liquid, evaporating and concentrating to obtain lithium carbonate and salt-containing wastewater, wherein the aim of the step is to further recover lithium ions in the solution.
The chemical reactions that occur are as follows:
2Li + +CO 3 2- ＝Li 2 CO 3 ↓
PO 4 3- +3Li + ＝Li 3 PO 4 ↓
the method of the present invention can be operated on an industrial scale, and in this example, the amount of lithium iron phosphate waste treated per day by the method of this example can be up to 20 tons, the yield of lithium carbonate for batteries is 4 tons, the yield of iron phosphate for batteries is 15 tons, and the yield of industrial grade iron phosphate (first precipitate obtained by primary impurity removal, which can be used in the ceramic industry) is 3 tons, depending on the capacity of the reaction apparatus.
The invention comprises the following technical scheme:
technical scheme 1, an industrial method for treating solid matters containing lithium iron phosphate, comprising the following steps:
(1) The solid matter is contacted with acid to carry out primary leaching reaction, so as to obtain primary leaching liquid and primary leaching solid;
(2) The first-stage leaching solution is contacted with an oxidant to carry out a first-stage precipitation reaction to obtain first-stage precipitation solid and first-stage precipitation liquid, wherein the first-stage precipitation solid is solid containing ferric phosphate, the first-stage precipitation liquid is solution containing lithium ions,
wherein the ratio of the weight of the solid material to the total weight of liquid material entering the primary leaching reaction is from 1:3 to 1:5 (e.g. from 1:3.5 to 1:4.5, for example 1:4), the liquid material added to the reaction comprising the acid.
Claim 2, the method according to claim 1, wherein,
the molar ratio of the hydrogen ions which can react in the acid to the ferrous iron in the substance containing lithium iron phosphate is (1.1-1.3): 1, or
The molar ratio of the hydrogen ions which can react in the acid to lithium in the substance containing lithium iron phosphate is 1.1-1.3.
The method according to claim 3, the method according to claim 1, further comprising:
And carrying out multistage countercurrent leaching treatment (such as secondary countercurrent treatment) on the primary leached solids by adopting a first washing liquid to obtain countercurrent leaching liquid and countercurrent leached solids, returning the countercurrent leaching liquid to the primary leaching reaction, and the liquid substances entering the primary leaching reaction also comprise the first washing liquid.
The method according to claim 4, the method according to claim 1 or 3, further comprising:
and carrying out multistage countercurrent precipitation treatment (for example, secondary countercurrent treatment) on the first-stage precipitated solid by adopting a second washing liquid to obtain countercurrent precipitation liquid and countercurrent precipitation solid, returning the countercurrent precipitation liquid into the first-stage leaching reaction and/or the multistage countercurrent leaching treatment, wherein the liquid substance entering the first-stage leaching reaction also comprises the second washing liquid.
The method according to claim 5, wherein the lithium iron phosphate-containing substance comprises at least one selected from the group consisting of: and the lithium iron phosphate anode powder waste, the lithium iron phosphate anode sheet waste and the lithium iron phosphate battery anode waste, wherein the lithium content is 2.5-4.5wt%.
According to the technical scheme 6 and the method according to the technical scheme 1, the reaction time of the primary leaching reaction is 0.1-3 hours, and the reaction time of the primary precipitation reaction is 1-3 hours.
The process according to claim 7, wherein the reaction time of each stage in the multistage countercurrent leaching treatment is 0 to 1 hour.
The method according to claim 8, wherein the reaction time of each stage in the multistage countercurrent chromatography is 0 to 1 hour.
According to the technical scheme 9 and the method according to the technical scheme 1, wherein the oxidant is hydrogen peroxide, the molar ratio of the hydrogen peroxide to lithium ions in the reaction solution is (0.55-0.65): 1, or the molar ratio of the hydrogen peroxide to ferrous iron in the lithium iron phosphate-containing substance is (0.55-0.65): 1.
The method according to claim 10, wherein the pH at which the primary leaching reaction is carried out is 0 to 2, and the pH in the primary precipitation reaction is changed from 0 to 2 at the beginning to 2.5 to 3.5 at the end.
Technical solution 11, the method according to claim 1, further comprising:
contacting the solution containing lithium ions with a first base to raise the pH value to a first pH value and maintaining the pH value for a first time to obtain a first precipitate and a first lithium purification solution;
contacting the first lithium purified solution with a second base to raise the pH to a second pH and for a second time to obtain a second precipitate and a second lithium purified solution;
And (3) contacting the second lithium purified solution with a third base to raise the pH value to a third pH value and maintaining the pH value for a third time to obtain a third precipitate and a third lithium purified solution.
The method according to claim 12, the method according to claim 11, further comprising: and contacting the third lithium purified solution with ion exchange resin to obtain a fourth lithium purified solution.
Claim 13, the method according to claim 12, further comprising: and reacting the fourth lithium purified solution with sodium carbonate to obtain lithium carbonate precipitate.
The method according to claim 14, wherein the first pH is a number from 4 to less than 6, and the first time is 30 minutes or more.
The method according to claim 15, wherein the second pH is a number of 6 or more and 8 or less, and the second time is 30 minutes or more.
The method according to claim 16, wherein the third pH is 11 or more and the third time is 30 minutes or more.
The method according to claim 17, according to claim 12, wherein the ion exchange resin is a mixed anion and cation resin.
The method according to claim 18, wherein the first base comprises at least one selected from the group consisting of lithium carbonate, lithium hydroxide, and sodium hydroxide.
The method according to claim 19, wherein the second base comprises at least one selected from the group consisting of sodium hydroxide and lithium hydroxide.
The method according to claim 20, wherein the third base comprises: at least one selected from sodium hydroxide and lithium hydroxide, and at least one selected from sodium carbonate and lithium carbonate.
According to claim 21, an iron phosphate contains 0.05% or more of lithium, 0.01% or less of calcium, 0.01% or less of magnesium, 0.01% or less of copper, and 0.01% or less of aluminum.
The iron phosphate according to claim 22, which contains 0.10% or more, 0.15% or more, or 0.20% or more of lithium.
The iron phosphate according to claim 23, which contains 0.005% or less or 0.0035% of calcium.
The iron phosphate according to claim 24, which contains 0.005% or less, or 0.003% or 0.0012% of magnesium.
The iron phosphate according to claim 25, which contains 0.001% or less, or 0.0005% or 0.0001% copper.
The iron phosphate according to claim 26, which contains 0.005% or 0.003% or 0.0016% or less of aluminum.
The iron phosphate according to claim 27, which is iron phosphate dihydrate, comprising 28% to 31% iron, or 29% to 30% iron.
Technical solution 28 the iron phosphate according to claim 21, which is produced by the method according to any one of claims 1 to 20, to obtain a primary precipitated solid or a countercurrent precipitated solid.
The iron phosphate according to claim 29, which contains 0.4% or less of lithium, for example 0.3% or less of lithium, for example 0.2% or less of lithium.
The foregoing is merely exemplary embodiments of the present disclosure and is not intended to limit the scope of the disclosure, which is defined by the appended claims.

Claims (11)

1. An industrial process for treating a solid substance containing lithium iron phosphate, comprising the steps of:
(1) The solid substances are contacted with liquid substances to carry out primary leaching reaction, so as to obtain primary leaching liquid and primary leaching solid;
(2) The first-stage leaching solution is contacted with an oxidant to carry out a first-stage precipitation reaction to obtain first-stage precipitation solid and first-stage precipitation liquid, wherein the first-stage precipitation solid is solid containing ferric phosphate, the first-stage precipitation liquid is solution containing lithium ions,
Wherein the ratio of the weight of the solid material to the total weight of the liquid material entering the primary leaching reaction, including acid,
the method further comprises the steps of:
carrying out multistage countercurrent leaching treatment on the first-stage leached solids by adopting a first washing solution to obtain countercurrent leaching solution and countercurrent leached solids, returning the countercurrent leaching solution to the first-stage leaching reaction, wherein the liquid substances entering the first-stage leaching reaction also comprise the first washing solution;
carrying out multistage countercurrent precipitation treatment on the first-stage precipitated solid by adopting a second washing liquid to obtain countercurrent precipitation liquid and countercurrent precipitation solid, returning the countercurrent precipitation liquid to the first-stage leaching reaction and/or the multistage countercurrent leaching treatment, wherein the liquid substance entering the first-stage leaching reaction also comprises the second washing liquid,
wherein the pH value of the primary leaching reaction is 0-2, and the pH value in the primary leaching reaction is changed from 0-2 at the beginning to 2.5-3.5 at the end.
2. The method of claim 1, wherein,
the molar ratio of the hydrogen ions which can react in the acid to the ferrous iron in the solid substance containing lithium iron phosphate is (1.1-1.3): 1, or
The molar ratio of the hydrogen ions which can react in the acid to lithium in the solid substance containing lithium iron phosphate is 1.1-1.3.
3. The method according to claim 1, wherein:
the multi-stage countercurrent precipitation treatment is a secondary countercurrent leaching treatment, and the multi-stage countercurrent leaching treatment is a secondary countercurrent leaching treatment.
4. The method according to claim 1, wherein the oxidant is hydrogen peroxide, the molar ratio of hydrogen peroxide to lithium ions in the reaction solution is (0.55-0.65): 1, or the molar ratio of hydrogen peroxide to ferrous iron in the solid matter containing lithium iron phosphate is (0.55-0.65): 1.
5. The method of claim 1, further comprising:
contacting the solution containing lithium ions with a first base to raise the pH value to a first pH value and maintaining the pH value for a first time to obtain a first precipitate and a first lithium purification solution;
contacting the first lithium purified solution with a second base to raise the pH to a second pH and for a second time to obtain a second precipitate and a second lithium purified solution;
and (3) contacting the second lithium purified solution with a third base to raise the pH value to a third pH value and maintaining the pH value for a third time to obtain a third precipitate and a third lithium purified solution.
6. The method of claim 5, wherein the first pH is a number of 4 or more and less than 6, and the first time is 30 minutes or more;
The second pH value is a number greater than or equal to 6 and less than 8, and the second time is greater than or equal to 30 minutes;
the third pH value is a number greater than or equal to 11, and the third time is greater than or equal to 30 minutes.
7. The method of claim 5, wherein the first base comprises at least one selected from the group consisting of lithium carbonate, lithium hydroxide, and sodium hydroxide;
the second base contains at least one selected from sodium hydroxide and lithium hydroxide; and
the third base comprises: at least one selected from sodium hydroxide and lithium hydroxide, and at least one selected from sodium carbonate and lithium carbonate.
8. The method of claim 1, wherein the ratio of the weight of the solid material to the total weight of liquid material entering the primary leaching reaction is from 1:3.5 to 1:4.5.
9. An iron phosphate containing 0.05% or more lithium, 0.0035% or less calcium, 0.005% or less magnesium, 0.001% or less copper, and 0.005% or less aluminum, which is produced by the process of any one of claims 1 to 8.
10. The iron phosphate according to claim 9, which contains 0.10% or more of lithium;
0.0035% or less of calcium;
Less than or equal to 0.003% magnesium;
less than or equal to 0.0005% copper; and
0.003% or less of aluminum.
11. The iron phosphate according to claim 9, which contains 0.20% or more of lithium;
0.0035% or less of calcium;
less than or equal to 0.0012% magnesium;
less than or equal to 0.0001% copper; and
less than or equal to 0.0016% of aluminum.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108899601A (en) * 2018-06-11 2018-11-27 衢州华友钴新材料有限公司 A method of recycling lithium from LiFePO4
CN208493380U (en) * 2018-05-17 2019-02-15 江西迈特循环科技有限公司 A kind of multistage countercurrent solid-liquid contact arrangement

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN208493380U (en) * 2018-05-17 2019-02-15 江西迈特循环科技有限公司 A kind of multistage countercurrent solid-liquid contact arrangement
CN108899601A (en) * 2018-06-11 2018-11-27 衢州华友钴新材料有限公司 A method of recycling lithium from LiFePO4

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