CN113184821B - Method for preparing ferric phosphate from iron-containing slag - Google Patents
Method for preparing ferric phosphate from iron-containing slag Download PDFInfo
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- CN113184821B CN113184821B CN202110513422.9A CN202110513422A CN113184821B CN 113184821 B CN113184821 B CN 113184821B CN 202110513422 A CN202110513422 A CN 202110513422A CN 113184821 B CN113184821 B CN 113184821B
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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
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- 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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
- C22B1/06—Sulfating roasting
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- 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
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- 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
Abstract
The invention provides a method for preparing ferric phosphate by utilizing iron-containing slag. The method comprises the following steps: step S1, pickling iron-containing slag to obtain pickled iron slag and pickling solution; s2, mixing and granulating the iron slag after pickling with acid and phosphate to obtain mixed particles; step S3, roasting the mixed particles to obtain a roasted product; s4, heating and slurrying the roasted material under the condition that the pH value is 0.8-1.8 to obtain ferric phosphate slurry; and S5, carrying out solid-liquid separation on the ferric phosphate slurry to obtain a ferric phosphate crude product and a valuable metal solution. The crude iron phosphate product obtained by the method can be used as a raw material of an iron phosphate battery, the metal recovery rate in valuable metal solution can be up to more than 98.5%, the whole effective utilization of iron slag waste is realized, the process is simple and feasible, the additive is low in cost, the cost of iron phosphate synthesis can be optimally reduced, and the slag-free comprehensive recovery and utilization of the iron slag are realized.
Description
Technical Field
The invention relates to the technical field of waste residue treatment, in particular to a method for preparing ferric phosphate by utilizing iron-containing slag.
Background
A common phenomenon in the wet smelting industry is that hazardous waste solid slag is difficult to treat, wherein more common iron slag comprises sodium iron vitriol slag, goethite slag, hematite slag, ferric phosphate slag, lithium iron phosphate slag and the like. The iron-vanadium slag and the iron slag are generally recycled by adopting processes of brickmaking, organized special landfill, roasting electrolysis and the like as raw materials of building materials, and slag materials are treated to a certain extent by the method, but the recovery rate of valuable metals is not high enough, and the effective utilization of various components of all slag materials cannot be realized.
The phosphate has low ferroelectric conductivity and can be used as an intercalation electrode of a lithium ion battery. However, as material engineers overcome conductivity problems, their use as electrode materials has become more and more popular in recent years. Due to FePO 4 Is stable to heat and is generally easy to recycle, so that the material is an ideal electrode material of the battery of the electric automobile. If the waste slag of the iron-containing materials can be fully utilized, the phosphoric acid is preparedThe iron precursor battery material not only solves the environmental protection problem, but also realizes the full closed-circuit circulation of various materials.
From the perspective of the current prior art, the existing iron slag treatment and recovery process can recover a part of valuable metals, but the recovery rate of the valuable metals is not high enough, and the effective utilization of various components of various iron-containing slag materials cannot be realized.
Disclosure of Invention
The invention mainly aims to provide a method for preparing ferric phosphate by utilizing iron-containing slag, which aims to solve the problem that iron and valuable metals in the iron-containing slag cannot be effectively recovered in the prior art.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method for preparing iron phosphate using iron-containing slag, the method comprising: step S1, pickling iron-containing slag to obtain pickled iron slag and pickling solution; s2, mixing and granulating the iron slag after pickling with acid and phosphate to obtain mixed particles; step S3, roasting the mixed particles to obtain a roasted product; s4, heating and slurrying the roasted material under the condition that the pH value is 0.8-1.8 to obtain ferric phosphate slurry; and S5, carrying out solid-liquid separation on the ferric phosphate slurry to obtain a ferric phosphate crude product and a valuable metal solution.
Further, in the step S1, sulfuric acid is used for acid washing, preferably H in sulfuric acid 2 SO 4 The molar amount of the iron is 0.5% -2%, preferably 1.0% -1.5%, of the total molar amount of iron in the iron-containing slag, preferably the volume of sulfuric acid is 1-5 times, preferably 2-3 times, of the volume of the iron-containing slag, preferably the iron-containing slag is selected from one or a mixture of more of yellow sodium iron vitriol slag, goethite slag, hematite slag, ferric phosphate slag and lithium iron phosphate slag, and the grain size of the iron-containing slag is preferably less than 50 mu m.
Further, in the step S2, H is used + The molar amount of the acid is 2.0-2.2 times of the molar amount of iron in the iron slag after acid washing, preferably the molar amount of the phosphate is 1.0-1.05 times of the molar amount of theoretical phosphate in terms of phosphorus element, preferably the acid is sulfuric acid, and preferably the phosphate is any one or more of sodium dihydrogen phosphate, sodium hydrogen phosphate, potassium hydrogen phosphate, sodium phosphate and potassium phosphate.
Further, the particle diameter of the mixed particles is 0.5 to 8cm.
Further, the baking temperature in the step S3 is 120-300 ℃, the baking time is 1-10 hours, the baking is preferably performed in air, and the air flow is 1-20L/min, preferably 10-15L/min.
Further, in the step S4, the temperature of the heating and slurrying is 70-95 ℃ and the time is 10-30 hours, and the calcined product is preferably stirred during the heating and slurrying, and the stirring speed is 1000-2000 rpm.
Further, the step S4 includes: mixing the roasting material with water and a surfactant to obtain mixed slurry, wherein the preferable surfactant is sodium dodecyl sulfate and sodium hexadecyl sulfate, the preferable volume ratio of the surfactant to the roasting material is 0.05-0.2:1, and the preferable volume ratio of the roasting material to the water is 1:5-7; and heating the mixed slurry, and maintaining the pH value of the mixed slurry to be 0.8-1.8 in the heating process to obtain the ferric phosphate slurry.
Further, before the step S4, the calcined product is pulverized to a particle size of 0.1 to 50. Mu.m.
Further, the step S5 includes: filtering the ferric phosphate slurry to obtain a filter cake and filtrate; and (3) carrying out acid leaching on the filter cake to obtain crude ferric phosphate, and preferably carrying out acid leaching by adopting sulfuric acid with the mass concentration of 0.5-2%.
Further, the method further comprises the step of wet recycling valuable metals in the filtrate obtained in the step S5 and the pickling solution obtained in the step S1.
By applying the technical scheme of the invention, most of impurity metal ions such as nickel, cobalt, copper and lithium in the iron-containing slag are washed out by acid washing, and most of soluble salts are washed out, so that iron remains in the iron slag after acid washing; then mixing and granulating the iron slag after pickling, acid and phosphate, and roasting, wherein ferric oxide in the iron slag after pickling reacts with the acid under the roasting condition to form ferric salt; after roasting, the iron phosphate slurry is obtained through heating and slurrying, and then solid-liquid separation is carried out to obtain an iron phosphate crude product and a valuable metal solution, wherein the obtained iron phosphate crude product can be used as a raw material of an iron phosphate battery, and the metal recovery rate in the valuable metal solution can be up to more than 98.5%, so that the whole effective utilization of iron slag waste is realized, the process is simple and easy, the additive is low in cost, the cost of iron phosphate synthesis can be optimally reduced, and the slag-free comprehensive recycling of the iron slag is realized.
Detailed Description
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present invention will be described in detail with reference to examples.
As analyzed in the background of the application, the recovery of valuable metals in the prior art slag is insufficient, resulting in a significant loss of valuable metals. To solve this problem, the present application provides a method for preparing iron phosphate using iron-containing slag, the method comprising: step S1, pickling iron-containing slag to obtain pickled iron slag and pickling solution; s2, mixing and granulating the iron slag after pickling with acid and phosphate to obtain mixed particles; step S3, roasting the mixed particles to obtain a roasted product; s4, heating and slurrying the roasted material under the condition that the pH value is 0.8-1.8 to obtain ferric phosphate slurry; and S5, carrying out solid-liquid separation on the ferric phosphate slurry to obtain a ferric phosphate crude product and a valuable metal solution.
The method comprises the steps of firstly washing out most of impurity metal ions such as nickel, cobalt, copper and lithium in the iron-containing slag by acid washing, and washing out most of soluble salts at the same time, wherein iron is remained in the iron slag after acid washing; then mixing and granulating the iron slag after pickling, acid and phosphate, and roasting, wherein ferric oxide in the iron slag after pickling reacts with the acid under the roasting condition to form ferric salt; after roasting, the iron phosphate slurry is obtained through heating and slurrying, and then solid-liquid separation is carried out to obtain an iron phosphate crude product and a valuable metal solution, wherein the obtained iron phosphate crude product can be used as a raw material of an iron phosphate battery, and the metal recovery rate in the valuable metal solution can be up to more than 98.5%, so that the whole effective utilization of iron slag waste is realized, the process is simple and easy, the additive is low in cost, the cost of iron phosphate synthesis can be optimally reduced, and the slag-free comprehensive recycling of the iron slag is realized.
The pickling process of the step S1 may refer to a conventional pickling method of iron-containing slag in the prior art, and in order to avoid volatilization of acidic substances during the pickling process, it is preferable that the step S1 uses sulfuric acid for pickling. In order to achieve a sufficient washing out of the valuable metals in the iron-containing slag, H in sulfuric acid is preferred 2 SO 4 The molar quantity of the catalyst is 0.5-2% of the total molar quantity of iron in the iron-containing slag, and the volume of sulfuric acid is 1-5 times of the volume of the iron-containing slag. The above method of the present application can be applied to various iron-containing slag, preferably a mixture of any one or more selected from the group consisting of pyrite slag, goethite slag, hematite slag, iron phosphate slag and lithium iron phosphate slag, each of which has a different composition and a different physical property, but has a commonality when acid washing is employed, i.e., dissolution of valuable metals therein is similar. The particle size of the iron-containing slag is preferably less than 50 μm. When a mixture of various kinds of slag is used as the iron-containing slag, the iron-containing slag is crushed to have a particle diameter of less than 50 μm by a ball milling process, and since the hardness of the various kinds of slag is different, the materials are mixed with each other at the time of ball milling to have a ball milling crushing gain effect. The ball milling process can be dry ball milling and can be wet ball milling.
In order to achieve a sufficient conversion of the iron oxide in the iron slag after pickling, it is preferred to use H in step S2 + The molar amount of the acid is 2.0-2.2 times of the molar amount of iron in the iron slag after acid washing, preferably the molar amount of the phosphate is 1.0-1.05 times of the molar amount of theoretical phosphate in terms of phosphorus element, preferably the acid is sulfuric acid, and preferably the phosphate is any one or more of sodium dihydrogen phosphate, sodium hydrogen phosphate, potassium hydrogen phosphate, sodium phosphate and potassium phosphate.
In the roasting, the reaction between the acid and the iron slag after acid washing is a solid phase reaction, and in order to increase the diffusion contact speed of the reactants in the mixed particles and further increase the reaction efficiency, the particle size of the mixed particles is preferably controlled to be 0.5-8 cm.
In some embodiments, the temperature of the calcination in step S3 is controlled to be 120 to 300 ℃, preferably 150 to 250 ℃, and the calcination time is controlled to be 1 to 10 hours, in which temperature range the reactivity of the reactants is improved. In order to convert ferrous ions in the iron slag after pickling, the roasting is preferably performed in air, and the flow rate of the air is 1-20L/min, preferably 10-15L/min.
In the present application, the conversion of the calcined product into iron phosphate can be achieved by the above-mentioned heat pulping, and in order to enhance the effect of converting iron phosphate, it is preferable that the temperature of the heat pulping in the above-mentioned step S4 is 70 to 95 ℃ for 10 to 30 hours, and it is preferable that the temperature of the heat pulping is 80 to 90 ℃ for 15 to 24 hours. In some embodiments, the calcine is stirred during the heating and slurrying process at a rotational speed of 1000-2000 rpm, thereby further improving the uniformity of the slurrying reaction.
In some embodiments, the step S4 includes: mixing the roasting matter with water and a surfactant to obtain mixed slurry; and heating the mixed slurry, and maintaining the pH value of the mixed slurry to be 0.8-1.8 in the heating process to obtain the ferric phosphate slurry. The particle size of the obtained iron phosphate is effectively controlled by adding the surfactant. And in the pulping process, the pH value is controlled between 0.8 and 1.8, so that the basic ferric phosphate generated by ferric salt and phosphate is converted into ferric phosphate, thereby improving the purity of the ferric phosphate and enabling the ratio of the ferric phosphate to be closer to 1:1. In some embodiments, the preferred surfactant is sodium dodecyl sulfate, sodium cetyl sulfate, preferably the volume ratio of the surfactant to the calcine is 0.05 to 0.2:1, preferably the volume ratio of the calcine to water is 1:5 to 7.
Similarly, in order to improve the pulping efficiency, the calcined product is pulverized to a particle size of 0.1 to 50 μm before step S4 is performed. The above-mentioned pulverization may be ball milling pulverization.
In some embodiments of the present application, the step S5 includes: filtering the ferric phosphate slurry to obtain a filter cake and filtrate; and (3) carrying out acid leaching on the filter cake to obtain crude ferric phosphate, and preferably carrying out acid leaching by adopting sulfuric acid with the mass concentration of 0.5-2%. Further purifying the ferric phosphate by means of filtration and acid leaching, and recovering valuable metal impurities on the ferric phosphate.
The filtrate and the pickling solution obtained in the application contain valuable metals, and a person skilled in the art can recover the valuable metals in a conventional valuable metal manner, and in some embodiments, the method further comprises wet recovering the valuable metals in the filtrate obtained in the step S5 and the pickling solution obtained in the step S1. For example, extraction, etc., reference may be made to the prior art for specific operations, which are not described herein.
The advantageous effects of the present application will be further described below in conjunction with examples and comparative examples.
Example 1
Ball milling and crushing: adding water into the random mixture of 4 iron slag sodium iron vitriol slag, goethite slag, hematite slag and ferric phosphate slag, dispersing for ball milling for 30min, and reducing the granularity of the system to micro-nano level, namely below 50 mu m, to be used as iron slag for pickling.
Acid washing and filtering: the weight content of iron, phosphorus and valuable metals (nickel, cobalt, manganese, lithium and copper) in the ball-milled sample was analyzed by sampling ICP and iron ion titration, and recorded in Table 1, and then H was added in an amount of 1 mol% based on the total iron content by using a sulfuric acid solution having twice the volume 2 SO 4 The iron slag after pickling and the pickling solution were obtained, and the content of each element in the iron slag after pickling was analyzed and also recorded in table 1.
TABLE 1
Acid adding and mixing: sulfuric acid with the total molar weight of iron being 1.05 times is added into the iron slag after pickling, then sodium dihydrogen phosphate is weighed, the dosage of the sodium dihydrogen phosphate is 1.01 of the theoretical dosage, and the mixture is obtained after 30 minutes of mixing.
Granulating: the mixture was granulated to 0.5 to 3cm and air-dried for 0.5 hours to obtain mixed granules.
Oxidizing and roasting: the mixed particles were placed in a 50L box furnace, and 10L/min of air was introduced and baked at 200℃for 2 hours to obtain a baked product.
Ball milling and crushing: cooling the roasted material, taking out, putting into a ball mill for ball milling for 30min, and crushing to obtain the particle size of 0.1-50 mu m.
Slurrying and synthesizing: adding 6 times of pure water and 0.05 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 90 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to about 0.8, and continuously stirring at a rotating speed of 1500rpm for reaction for 24 hours to obtain ferric phosphate slurry.
And (3) filtering and washing: and filtering and dehydrating the generated ferric phosphate slurry, adding a proper amount of 2% sulfuric acid aqueous solution for leaching, collecting all filtrate and leaching liquid to obtain D50=2μm ferric phosphate particles, and calculating the yield of the ferric phosphate to 96.5%, wherein the ratio of the phosphorus to the iron is 1:0.995.
Recovery of valuable metals: the total yield of valuable metals is 98.5%, and the valuable metals in the pickling solution, the filtrate and the pickling solution enter a wet recovery system for separation and recovery.
Example 2
Ball milling and crushing: adding water into the random mixture of 4 iron slag sodium iron vitriol slag, goethite slag, hematite slag and lithium iron phosphate waste slag for dispersing, ball milling for 45min, and reducing the granularity of the system to micro-nano level, namely below 50 mu m.
Acid washing and filtering: the weight content of iron, phosphorus and valuable metals (nickel, cobalt, manganese, copper and lithium) in the ball-milled sample is analyzed by sampling ICP and matching with an iron ion titration method, and is recorded in a table 2, and then three times of volume of sulfuric acid solution is adopted and H is added according to the molar quantity of 2% of the total iron content 2 SO 4 And (5) pickling to obtain pickled iron slag and pickling solution.
TABLE 2
Acid adding and mixing: adding sulfuric acid with the total molar weight of iron being 1.03 times into the acid washing filter residues, then weighing sodium dihydrogen phosphate, wherein the dosage of the sodium dihydrogen phosphate is 1.00 of the theoretical dosage, and mixing for 60 minutes to obtain a mixture.
Granulating: granulating the mixture obtained in the steps to prepare small particles with the length of 2 cm-5 cm, and air-drying to obtain mixed particles.
Oxidizing and roasting: putting the mixed particles into a 50L box-type furnace, introducing 15L/min of air, and baking at 250 ℃ for 1 hour to obtain a baked product;
ball milling and crushing: cooling the roasted material, taking out, putting into a ball mill for ball milling for 15min, and crushing to obtain the particle size of 0.1-50 mu m.
Slurrying and synthesizing: adding 5 times of pure water and 0.08 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 80 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to be about 1.0, and continuously stirring at a high speed at a rotating speed of 2000rpm for reaction for 15 hours to obtain ferric phosphate slurry.
And (3) filtering and washing: the resulting ferric phosphate slurry was dehydrated by filtration and rinsed with an appropriate amount of 5% aqueous sulfuric acid. D50=1.5 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 97.8% with a ratio of 1:0.991.
Recovery of valuable metals: the total yield of valuable metals is 98.9%, and the valuable metals in the pickling solution, the filtrate and the pickling solution enter a wet recovery system for separation and recovery.
Example 3
Ball milling and crushing: adding water into the random mixture of 4 iron slag sodium iron vitriol slag, iron needle slag, ferric phosphate and lithium iron phosphate waste slag, dispersing for ball milling for 60min, and reducing the granularity of the system to micro-nano level, namely below 50 mu m.
Acid washing and filtering: sample analysis of the weight content of iron, phosphorus, and valuable metals (nickel, cobalt, manganese, lithium, copper) in the ball-milled sample, recorded in Table 3, was then added H using twice the volume of sulfuric acid solution and at a molar amount of 1.5% based on the total iron content 2 SO 4 And (5) pickling to obtain pickled iron slag and pickling solution.
TABLE 3 Table 3
Acid adding and mixing: adding sulfuric acid with the total molar weight of iron being 1.08 times into the acid washing filter residues, then weighing sodium dihydrogen phosphate, wherein the dosage of the sodium dihydrogen phosphate is 1.02 of the theoretical dosage, and mixing for 60 minutes to obtain a mixture.
Granulating: granulating the mixture obtained in the steps to obtain small particles with the length of 4 cm-7 cm, and air-drying to obtain mixed particles.
Oxidizing and roasting: the pellets were placed in a 50L box oven and baked at 150℃for 3 hours with 10L/min of air.
Ball milling and crushing: and cooling the baked material, taking out, putting into a ball mill for ball milling for 60min, wherein the particle size after crushing is 0.1-50 mu m.
Slurrying and synthesizing: adding 7 times of pure water and 0.1 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 85 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to be about 1.2, and continuously stirring at a rotating speed of 1000rpm for reaction for 20 hours at a high speed to obtain ferric phosphate slurry.
And (3) filtering and washing: the resulting ferric phosphate slurry was dehydrated by filtration and rinsed with an appropriate amount of 2% aqueous sulfuric acid. D50=2 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 97.9% with a ratio of 1:0.987.
Recovery of valuable metals: the total yield of valuable metals is 98.6%, and the valuable metals in the pickling solution, the filtrate and the pickling solution enter a wet recovery system for separation and recovery.
Example 4
Ball milling and crushing: adding water into the random mixture of 4 iron slag sodium iron vitriol slag, goethite slag, hematite slag and ferric phosphate slag, dispersing for ball milling for 30min, and reducing the granularity of the system to micro-nano level, namely below 50 mu m, to be used as iron slag for pickling.
Acid washing and filtering: the weight content of iron, phosphorus and valuable metals (nickel, cobalt, manganese, copper and lithium) in the ball-milled sample was analyzed by sampling ICP and ferric ion titration, and recorded in Table 4, and then five-fold volume of sulfuric acid solution was used and H was added in an amount of 0.5 mol% based on the total iron content 2 SO 4 And (5) pickling to obtain pickled iron slag and pickling solution.
TABLE 4 Table 4
Example 5
The difference from example 1 is in the acid addition compounding process, specifically: adding sulfuric acid with the total molar weight of iron being 1.1 times to the iron slag after pickling, then weighing sodium dihydrogen phosphate, wherein the dosage of the sodium dihydrogen phosphate is 1.01 of the theoretical dosage, and mixing for 30min to obtain a mixture.
After filtration and washing, d50=2.1 μm iron phosphate particles were obtained, wherein the ratio of phosphorus to iron was 1:0.99, and the recovery rate of iron phosphate was calculated to be 96.8%.
Example 6
The difference from example 1 is in the step of granulation, and the particle diameter of the mixed particles after granulation is 9 to 12cm particles.
After filtration and washing, d50=1.9 μm iron phosphate particles were obtained, with a ratio of 1:0.995, and the recovery rate of iron phosphate was calculated to be 97.2%.
Example 7
The difference from example 1 is the slurried synthesis step, in particular: adding 5 times of pure water and 0.05 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 80 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to be about 1.0, and continuously stirring at a high speed at a rotating speed of 2000rpm for reaction for 15 hours to obtain ferric phosphate slurry.
After filtration and washing, d50=2.2 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 96.3% with a ratio of phosphorus to iron of 1:0.995.
Example 8
The difference from example 1 is the slurried synthesis step, in particular: adding 5 times of pure water and 0.1 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 80 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to be about 1.0, and continuously stirring at a high speed at a rotating speed of 2000rpm for reaction for 15 hours to obtain ferric phosphate slurry.
After filtration and washing, d50=1.4 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 96.6% with a ratio of phosphorus to iron of 1:0.995.
Example 9
The difference from example 1 is the slurried synthesis step, in particular: adding 5 times of pure water and 0.2 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 80 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to be about 1.0, and continuously stirring at a high speed at a rotating speed of 2000rpm for reaction for 15 hours to obtain ferric phosphate slurry.
After filtration and washing, d50=1.1 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 96.7% with a ratio of phosphorus to iron of 1:0.996.
Example 10
The difference from example 1 is the step of oxidative calcination, specifically: the mixed particles were placed in a 50L box furnace, and 10L/min of air was introduced and baked at 120℃for 10 hours to obtain a baked product.
After filtration and washing, d50=2 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 96.2%, wherein the ratio of phosphorus to iron was 1:0.994.
Example 11
The difference from example 1 is the step of oxidative calcination, specifically: the mixed particles were placed in a 50L box furnace, and 10L/min of air was introduced and baked at 300℃for 1 hour to obtain a baked product.
After filtration and washing, d50=2 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 95.3%, wherein the ratio of phosphorus to iron was 1:0.991.
Example 12
The difference from example 1 is the slurried synthesis step, in particular: adding 6 times of pure water and 0.05 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 70 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to about 0.8, and continuously stirring at a rotating speed of 1500rpm for reaction for 24 hours to obtain ferric phosphate slurry.
After filtration and washing, d50=2 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 92.1% with a ratio of phosphorus to iron of 1:0.988.
Example 13
The difference from example 1 is the slurried synthesis step, in particular: adding 6 times of pure water and 0.05 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 95 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to about 0.8, and continuously stirring at a rotating speed of 1500rpm for reaction for 24 hours to obtain ferric phosphate slurry.
After filtration and washing, d50=2 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 98.5%, wherein the ratio of phosphorus to iron was 1:0.990.
Example 14
The difference from example 1 is the slurried synthesis step, in particular: adding 6 times of pure water and 0.05 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 90 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to about 0.8, and continuously stirring at a rotating speed of 1500rpm for reaction for 30 hours to obtain ferric phosphate slurry.
After filtration and washing, d50=1.9 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 96.6% with a ratio of phosphorus to iron of 1:0.995.
Example 15
The difference from example 1 is the slurried synthesis step, in particular: adding 6 times of pure water and 0.05 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 90 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to about 0.8, and continuously stirring at a rotating speed of 1500rpm for reaction for 10 hours to obtain ferric phosphate slurry.
After filtration and washing, d50=2.3 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 94.7% with a ratio of phosphorus to iron of 1:0.984.
Example 16
The difference from example 1 is the slurried synthesis step, in particular: adding 6 times of pure water and 0.05 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 60 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to about 0.8, and continuously stirring at a rotating speed of 1500rpm for reaction for 36 hours to obtain ferric phosphate slurry.
After filtration and washing, d50=1.8 μm iron phosphate particles were obtained, and the yield of iron phosphate was calculated to be 90.8%, wherein the ratio of phosphorus to iron was 1:0.992.
Comparative example 1
The difference from example 1 is the slurried synthesis step, in particular: adding 6 times of pure water and 0.05 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 90 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to be about 2.2, and continuously stirring at a rotating speed of 1500rpm for reaction for 24 hours at a high speed to obtain ferric phosphate slurry. The recovery rate of the obtained iron phosphate was calculated to be 98.9% by filtration washing treatment, d50=1.9 μm. But the valuable metal copper part enters into the ferric phosphate product to affect the product quality
Comparative example 2
The difference from example 1 is the slurried synthesis step, in particular: adding 6 times of pure water and 0.05 times of sodium dodecyl sulfate into the ball-milled roasted material; stirring and heating to 90 ℃; and adding a proper amount of ammonia water to regulate the pH of the system to about 0.5, and continuously stirring at a rotating speed of 1500rpm for reaction for 24 hours to obtain ferric phosphate slurry. After filtration and washing treatment, d50=2.5 μm of iron phosphate was obtained, and the recovery rate of iron was 55%.
From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:
the method comprises the steps of firstly washing out most of impurity metal ions such as nickel, cobalt, copper and lithium in the iron-containing slag by acid washing, and washing out most of soluble salts at the same time, wherein iron is remained in the iron slag after acid washing; then mixing and granulating the iron slag after pickling, acid and phosphate, and roasting, wherein ferric oxide in the iron slag after pickling reacts with the acid under the roasting condition to form ferric salt; after roasting, the iron phosphate slurry is obtained through heating and slurrying, and then solid-liquid separation is carried out to obtain an iron phosphate crude product and a valuable metal solution, wherein the obtained iron phosphate crude product can be used as a raw material of an iron phosphate battery, and the metal recovery rate in the valuable metal solution can be up to more than 98.5%, so that the whole effective utilization of iron slag waste is realized, the process is simple and easy, the additive is low in cost, the cost of iron phosphate synthesis can be optimally reduced, and the slag-free comprehensive recycling of the iron slag is realized.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (20)
1. A method for preparing iron phosphate from iron-containing slag, the method comprising:
step S1, pickling iron-containing slag to obtain pickled iron slag and pickling solution; the iron-containing slag is selected from any one or a mixture of more of sodium iron vitriol slag, goethite slag, hematite slag, ferric phosphate waste slag and lithium iron phosphate slag;
s2, mixing and granulating the iron slag after pickling with acid and phosphate to obtain mixed particles;
step S3, roasting the mixed particles to obtain a roasted product; the roasting is carried out in air;
step S4, heating and slurrying the roasted material under the condition that the pH value is 0.8-1.8 to obtain ferric phosphate slurry;
s5, carrying out solid-liquid separation on the ferric phosphate slurry to obtain a ferric phosphate crude product and a valuable metal solution;
wherein the roasting temperature in the step S3 is 120-300 ℃, the roasting time is 1-10 h, and the air flow is 1-20L/min; in the step S4, the temperature of the heating and slurrying is 70-95 ℃ and the time is 10-30 hours, and the roasted material is stirred in the heating and slurrying process, wherein the stirring speed is 1000-2000 rpm.
2. The method according to claim 1, wherein step S1 is performed with sulfuric acid.
3. The method of claim 2, wherein H in the sulfuric acid 2 SO 4 The molar quantity of the iron is 0.5% -2% of the total molar quantity of iron in the iron-containing slag.
4. The method according to claim 2, characterized in thatCharacterized in that H in the sulfuric acid 2 SO 4 The molar quantity of the iron is 1.0-1.5% of the total molar quantity of iron in the iron-containing slag.
5. The method of claim 2, wherein the volume of sulfuric acid is 1-5 times the volume of the iron-containing slag.
6. The method of claim 2, wherein the volume of sulfuric acid is 2-3 times the volume of the iron-containing slag.
7. The method of claim 1, wherein the iron-containing slag has a particle size of less than 50 μm.
8. The method according to claim 1, wherein in step S2, H is used as + And counting the molar quantity of the acid to be 2.0-2.2 times of the molar quantity of iron in the iron slag after pickling.
9. The method according to claim 1, wherein the molar amount of phosphate is 1.0 to 1.05 times the theoretical molar amount of phosphate in terms of phosphorus element.
10. The method of claim 9, wherein the acid is sulfuric acid and the phosphate is any one or more of sodium dihydrogen phosphate, sodium hydrogen phosphate, potassium hydrogen phosphate, sodium phosphate, and potassium phosphate.
11. The method of claim 1, wherein the mixed particles have a particle size of 0.5-8 cm.
12. The method according to claim 1, wherein the air flow in the step S3 is 10-15L/min.
13. The method according to claim 1, wherein the step S4 comprises:
mixing the roasting material with water and a surfactant to obtain mixed slurry;
and heating the mixed slurry, and maintaining the pH value of the mixed slurry to be 0.8-1.8 in the heating process to obtain the ferric phosphate slurry.
14. The method of claim 13, wherein the surfactant is sodium dodecyl sulfate, sodium cetyl sulfate.
15. The method of claim 13, wherein the volume ratio of the surfactant to the baked product is 0.05-0.2:1.
16. The method of claim 13, wherein the volume ratio of the calcine to the water is 1:5-7.
17. The method according to claim 1, wherein the calcined product is pulverized to a particle size of 0.1 to 50 μm before the step S4 is performed.
18. The method according to claim 1, wherein the step S5 comprises:
filtering the ferric phosphate slurry to obtain a filter cake and filtrate;
and (3) carrying out acid leaching on the filter cake to obtain crude ferric phosphate.
19. The method according to claim 18, wherein the acid leaching is performed with sulfuric acid having a mass concentration of 0.5-2%.
20. The method of claim 18, further comprising wet recovering valuable metals from the filtrate obtained in step S5 and the pickling solution obtained in step S1.
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