CN108706561B - Method for preparing high-purity iron phosphate by using pyrite cinder - Google Patents
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- CN108706561B CN108706561B CN201810922413.3A CN201810922413A CN108706561B CN 108706561 B CN108706561 B CN 108706561B CN 201810922413 A CN201810922413 A CN 201810922413A CN 108706561 B CN108706561 B CN 108706561B
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- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
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- C01B25/37—Phosphates of heavy metals
- C01B25/375—Phosphates of heavy metals of iron
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Abstract
The invention discloses a method for preparing high-purity iron phosphate by using pyrite cinder, which comprises the following steps: cleaning, drying and crushing the pyrite cinder to form pyrite cinder powder, and then mixing the pyrite cinder powder with an acid solution to form a mixture; heating the mixture to 60-120 ℃ to perform hydrothermal reaction for 6-12 h, then separating solid from liquid and collecting reaction liquid; adjusting the temperature of the reaction solution to 60-100 ℃, adjusting the pH value to 1.0-1.5, stirring and purifying to obtain ferric hydroxide colloid; dissolving the ferric hydroxide colloid in a phosphoric acid solution, heating to 80-160 ℃ for hydrothermal reaction for 6-12 h, separating solid from liquid, and collecting a solid product; and washing, drying and calcining the solid product to obtain a high-purity iron phosphate product. The method for preparing the high-purity iron phosphate by using the pyrite cinder provided by the invention has the advantages of simple process and mild conditions, and improves the conversion utilization rate of iron elements in the pyrite cinder and the product purity of the prepared iron phosphate.
Description
Technical Field
The invention relates to the technical field of comprehensive utilization of pyrite cinder in the sulfuric acid industry, in particular to a method for preparing high-purity iron phosphate by using pyrite cinder.
Background
The pyrite cinder is the residue discharged after the pyrite is roasted to extract sulfur. Iron and other elements in the pyrite remain in the clinker, except for the use of sulfur. A large amount of pyrite cinder is generated in China every year because pyrite is used for producing sulfuric acid. If the waste is not used, not only a large amount of storage yards are occupied, but also the water, the atmosphere and the soil are seriously polluted. Therefore, the research on the technology for changing the pyrite cinder into valuable has important significance for improving the resource utilization rate and reducing the pollution.
Iron phosphate (FePO)4) Is a monoclinic crystal of white or grey white powder, is widely applied in the fields of agriculture, ceramic glass, steel, surface passivation and the like at first, and then research finds that FePO4The catalyst also has application in the fields of oxidative dehydrogenation catalysis, ion exchange, electrochemical performance and the like, and in the field of electrochemistry, FePO4Can be used for preparing LiFePO of lithium ion battery4And the framework material of the positive electrode material.
The mass of the iron element occupies a great proportion in the pyrite cinder, and the total iron content can reach more than 60 percent after the pyrite cinder is simply treated. If iron can be extracted from the pyrite cinder and used as a raw material for producing the iron phosphate, not only can harmless treatment of hazardous wastes be realized, and pollution to the environment be reduced, but also resource recycling can be realized, and the method has important economic and environmental significance. However, the existing method for preparing iron phosphate by taking pyrite cinder as a raw material is not mature, and has the defects of low conversion utilization rate of iron elements in the pyrite cinder and low purity of iron phosphate products.
Disclosure of Invention
The invention mainly aims to provide a method for preparing high-purity iron phosphate by using pyrite cinder, aiming at improving the conversion utilization rate of iron elements and the product purity of the iron phosphate when the iron phosphate is prepared from the pyrite cinder.
In order to achieve the aim, the invention provides a method for preparing high-purity iron phosphate by using pyrite cinder, which comprises the following steps:
cleaning, drying and crushing the pyrite cinder to form pyrite cinder powder, and then mixing the pyrite cinder powder with an acid solution to form a mixture;
heating the mixture to 60-120 ℃ for hydrothermal reaction for 6-12 h, then separating solid from liquid and collecting reaction liquid;
adjusting the temperature of the reaction solution to 60-100 ℃, adjusting the pH value to 1.0-1.5, stirring and purifying to obtain ferric hydroxide colloid;
dissolving the ferric hydroxide colloid in a phosphoric acid solution, heating to 80-160 ℃ for hydrothermal reaction for 6-12 h, separating solid from liquid, and collecting a solid product;
and washing, drying and calcining the solid product to obtain a high-purity iron phosphate product.
Preferably, the composition of the pyrite cinder comprises ferroferric oxide, ferric oxide, calcium oxide, magnesium oxide, silicon oxide and sulfur.
Preferably, in the step of washing, drying and crushing the pyrite cinder to form the pyrite cinder powder, and then mixing the pyrite cinder powder with the acid solution to form the mixture:
the particle size of the pyrite cinder powder is 100-500 meshes.
Preferably, in the step of washing, drying and crushing the pyrite cinder to form the pyrite cinder powder, and then mixing the pyrite cinder powder with the acid solution to form the mixture:
and the solid-to-liquid ratio of the pyrite cinder powder to the acid solution is 50-250 g/L when the pyrite cinder powder and the acid solution are mixed.
Preferably, in the step of washing, drying and crushing the pyrite cinder to form the pyrite cinder powder, and then mixing the pyrite cinder powder with the acid solution to form the mixture:
the acid solution is at least one of a sulfuric acid solution and a hydrochloric acid solution, wherein the concentration of the sulfuric acid solution is 40-60%, and the concentration of the hydrochloric acid solution is 20-37%.
Preferably, the temperature of the reaction solution is adjusted to 60-100 ℃, the pH value is adjusted to 1.0-1.5, and the reaction solution is stirred and then purified to obtain the ferric hydroxide colloid, wherein the step of:
the method for adjusting the pH value of the reaction solution to 1.0-1.5 comprises the following steps: and adding ammonia water or urea into the reaction liquid.
Preferably, the temperature of the reaction solution is adjusted to 60-100 ℃, the pH value is adjusted to 1.0-1.5, and the reaction solution is stirred and then purified to obtain the ferric hydroxide colloid, which specifically comprises the following steps:
and adjusting the temperature of the reaction liquid to 60-100 ℃, adjusting the pH value to 1.0-1.5, stirring for 0.5-2 h, and then putting the reaction liquid into a dialysis bag for purification for 6-12 h to obtain the ferric hydroxide colloid.
Preferably, the temperature of the reaction solution is adjusted to 60-100 ℃, the pH value is adjusted to 1.0-1.5, the reaction solution is stirred for 0.5-2 hours, and then the reaction solution is put into a dialysis bag for purification for 6-12 hours, so that the ferric hydroxide colloid is obtained:
and (3) putting the reaction solution into a dialysis bag for purification for 6-12 h, and further comprising the following steps: shaking the dialysis bag filled with the reaction solution every 1-3 hours for 10-30 min.
Preferably, the ferric hydroxide colloid is dissolved in a phosphoric acid solution, then the solution is heated to 80-160 ℃ for hydrothermal reaction for 6-12 h, solid-liquid separation is carried out, and then a solid product is collected:
the atomic number of the iron element and the phosphorus element when the ferric hydroxide colloid is dissolved in the phosphoric acid solution is 1 (1-1.2).
Preferably, the ferric hydroxide colloid is dissolved in a phosphoric acid solution, then the solution is heated to 80-160 ℃ for hydrothermal reaction for 6-12 h, solid-liquid separation is carried out, and then a solid product is collected:
the concentration of the phosphoric acid solution is 20-40%.
According to the technical scheme provided by the invention, pyrite cinder powder is mixed with an acid solution, the mixture is heated to 60-120 ℃ for hydrothermal reaction for 6-12 h, then reaction liquid is separated out, the temperature of the reaction liquid is adjusted to 60-90 ℃, the pH value is adjusted to 1.8-2.0, then the mixture is stirred and purified to obtain iron hydroxide colloid, the iron hydroxide colloid is mixed with phosphoric acid and then heated to 80-160 ℃ for hydrothermal reaction for 6-12 h, after the reaction is completed, a generated solid product is separated out, and then the solid product is washed, dried and calcined to obtain a high-purity iron phosphate product.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other related drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of an embodiment of the method for preparing high-purity iron phosphate from pyrite cinder according to the present invention;
fig. 2 is an SEM image of iron phosphate prepared in example 1 of the present invention;
fig. 3 is an XRD pattern of iron phosphate prepared in example 1 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
At present, the method for preparing the iron phosphate by taking the pyrite cinder as the raw material is not mature, and has the defects of low conversion utilization rate of iron elements in the pyrite cinder and low purity of iron phosphate products. In order to solve the above problems, the present invention provides a method for preparing high-purity iron phosphate from pyrite cinder, and fig. 1 shows an embodiment of the method for preparing high-purity iron phosphate from pyrite cinder provided in the present invention. Referring to fig. 1, in this embodiment, the method for preparing high-purity iron phosphate from pyrite cinder includes the following steps:
step S10, cleaning, drying and crushing the pyrite cinder to form pyrite cinder powder, and mixing the pyrite cinder powder with an acid solution to form a mixture;
the pyrite cinder is the residue discharged after roasting and extracting sulfur from the pyrite, the pyrite contains a plurality of noble metal elements besides the sulfur, particularly the mass of the iron element occupies a large proportion in the pyrite cinder, and the total iron content can reach more than 60 percent after the pyrite cinder is simply treated. If iron can be extracted from the pyrite cinder and used as a raw material for producing the iron phosphate, not only can harmless treatment of hazardous wastes be realized, and pollution to the environment be reduced, but also resource recycling can be realized, and the method has important economic and environmental significance. The method for preparing the high-purity iron phosphate by using the pyrite cinder as the raw material comprises the processes of strong acid treatment of the pyrite cinder, preparation and purification of ferric hydroxide colloid, conversion of the ferric hydroxide colloid into the high-purity iron phosphate and the like, so that the pyrite cinder is effectively reused, and the product prepared by the method is only phosphate through selection of the raw material and design of process flow and conditions.
In this embodiment, the pyrite cinder selected is preferably pyrite cinder whose components include ferroferric oxide, ferric oxide, calcium oxide, magnesium oxide, silicon oxide and sulfur, and more preferably, the mass percentages of the ferroferric oxide, the ferric oxide, the calcium oxide, the magnesium oxide, the silicon oxide and the sulfur in the pyrite cinder are 43.31%, 8.13%, 1.63%, 0.46%, 35.73% and 0.16%. Of course, in other embodiments of the present invention, the pyrite cinder may also be selected from pyrite cinder containing other components besides the above components, for example, part of the pyrite cinder may also contain copper oxide, zinc oxide, or platinum, silver, etc.
In the implementation of this example, the pyrite cinder is first washed sufficiently to remove impurities such as floating ash on the surface, then the washed pyrite cinder is dried to remove water therein, and finally the pyrite cinder is pulverized into pyrite cinder powder. In this embodiment, the particle size of the pyrite cinder powder is 100 to 500 meshes, and after the pyrite cinder powder is crushed by a conventional crushing device such as a high-speed crusher, the crushed material is sieved by a 100 to 500 mesh sieve, so as to obtain the pyrite cinder powder with the particle size of 100 meshes.
When the pyrite cinder powder and the acid solution are mixed to form the mixture, the solid-to-liquid ratio of the pyrite cinder powder to the acid solution is 50-250 g/L, namely 1L of the acid solution is correspondingly added into every 50-250 g of the pyrite cinder powder, so that the added acid solution can completely immerse the pyrite cinder powder, the pyrite cinder powder is completely in an acid environment, and the acidity condition required by the subsequent hydrothermal reaction is achieved.
Further, the acid solution is at least one of a sulfuric acid solution and a hydrochloric acid solution, and may be any one of a sulfuric acid solution or a hydrochloric acid solution, or may be a mixed solution of a sulfuric acid solution and a hydrochloric acid solution, wherein the concentration of the sulfuric acid solution is 40-60%, and the concentration of the hydrochloric acid solution is 20-37%. Therefore, the acidity value required by the first hydrothermal reaction of the mixture can be met, and the adverse effect on reaction products or reaction containers caused by corrosion due to heating in the hydrothermal reaction of the mixture can be avoided.
Step S20, heating the mixture to 60-120 ℃ for hydrothermal reaction for 6-12 h, then separating solid from liquid and collecting reaction liquid;
the hydrothermal reaction may be carried out in a reaction vessel commonly used in the art, for example, a reaction vessel, or may be replaced with a three-necked flask or the like in a laboratory test, and after completion of the reaction, the reaction solution may be separated by a conventional means for separating solid and liquid, such as filtration or centrifugation, and the hydrothermal reaction may be carried out in a reaction vessel, and after completion of the reaction, the solid and liquid may be separated by filtration, for example. In the present embodiment, step S20 may be performed as follows: mixing the pyrite cinder powder with the acid solution to form the mixture, transferring the mixture into a reaction kettle, heating to 60-120 ℃, and carrying out hydrothermal reaction for 6-12 h, wherein in the hydrothermal reaction process in the step S20, the following reactions occur:
Fe2O3+6H+→2Fe3++3H2O
Fe3O4+8H+→2Fe3++4H2O+Fe2+
after the hydrothermal reaction is finished, filtering the mixture after the reaction, and separating out filter residue and reaction liquid, wherein the filter residue mainly comprises insoluble substances such as silicon oxide, calcium sulfate and the like, and the reaction liquid contains Fe3+、Fe2+、Ca2+、Mg2+And (5) inorganic ions are used, filter residues are discarded, and reaction liquid is collected and used as a raw material for next treatment.
S30, adjusting the temperature of the reaction solution to 60-100 ℃, adjusting the pH value to 1.0-1.5, and purifying after stirring to obtain ferric hydroxide colloid;
the pH of the reaction solution may be adjusted to 1.0 to 1.5 by adding an alkaline substance, such as sodium hydroxide or potassium hydroxide, to the reaction solution, but since the reaction solution formed by the hydrothermal reaction is strongly acidic, the pH is less than 1.0, and the pH is adjusted to 1.0 to 1.5, only a small adjustment is needed, in this embodiment, the method for adjusting the pH of the reaction solution to 1.8 to 2.0 is preferably: the ammonia water or urea added into the reaction liquid has weaker alkalinity after being dissolved in water compared with strong sodium oxide or potassium hydroxide, and is suitable for slightly adjusting the pH value of the reaction liquid, so that the pH value of the reaction liquid is prevented from being adjusted to be more than 1.5 due to too strong alkalinity of the added alkaline substances.
In step S30, after adjusting the temperature and pH of the reaction solution to preset conditions, Fe in the reaction solution is allowed to remain under stirring3+And Fe2+The following reaction takes place to produce iron hydroxide colloid:
Fe3++3OH-→Fe(OH)3(colloid)
Fe2++2OH-→Fe(OH)2
4Fe(OH)2+O2+2H2O→4Fe(OH)3(colloid)
Stirring continuously to complete the reaction so as to ensure that the Fe in the reaction liquid3+And Fe2+Reacting sufficiently to form ferric hydroxide colloid, and purifying to remove residual inorganic ions such as Ca in the reaction solution2+And Mg2+Thereby obtaining a purified ferric hydroxide colloid. In the present embodiment, step S30 may be performed in the following manner: adding ammonia water or urea into the reaction liquid to adjust the pH value to 1.0-1.5, heating the reaction liquid to 60-100 ℃, stirring for 0.5-2 h to form a mixed liquid with ferric hydroxide colloid, and then putting the mixed liquid into a dialysis bag to purify for 6-12 h, wherein the dialysis bag is a semi-permeable membrane bag, the materials of the dialysis bag comprise cellulose acetate membranes, aromatic polyamide membranes, porous glass membranes and the like, the aperture of the mixed liquid is about 10-100 nm generally, and in the purification process of the mixed liquid in the dialysis bag, inorganic ions and small molecular impurities in the mixed liquid permeate the dialysis bag to move to the outside of the dialysis bag, so that the ferric hydroxide colloid is separated from other inorganic ions and small molecular impurities to obtain the purified ferric hydroxide colloid.
Preferably, in the purification process using dialysis bag, further comprising: shaking the dialysis bag filled with the reaction liquid every 1-3 hours for 10-30 min, wherein the shaking can be performed by placing the dialysis bag loaded with the reaction liquid into an ultrasonic oscillator for shaking or placing the dialysis bag loaded with the reaction liquid on a shaking table for shaking, in this embodiment, shaking table shaking is taken as an example for explanation, and the rotating speed of the shaking table for shaking the shaking table can be set to be 50-150 rpm. Shaking the dialysis bag loaded with the reaction liquid every 1-3 hours for 10-30 min, so that the speed of the ions in the reaction liquid migrating from the inside of the dialysis bag to the outside is accelerated, and the efficiency of purifying the ferric hydroxide colloid is improved. It should be noted that, during the specific implementation of shaking for 10-30 min every 1-3 h, if the time from the final completion of the purification time is less than 1-3 h, the purification is continued in the dialysis bag without shaking after the last shaking.
S40, dissolving the ferric hydroxide colloid in a phosphoric acid solution, heating to 80-160 ℃ for hydrothermal reaction for 6-12 h, separating solid from liquid, and collecting a solid product;
mixing the ferric hydroxide colloid with a phosphoric acid solution, stirring until the ferric hydroxide colloid is dissolved, transferring the mixed solution into a hydrothermal reaction kettle, heating to 80-160 ℃, carrying out hydrothermal reaction for 6-12 h, and carrying out the following reaction in the hydrothermal reaction process of step S40:
Fe(OH)3+H3PO4→FePO4↓+3H2O
and after the reaction is finished, filtering the solution after the reaction and collecting a solid product, wherein the solid product is a crude product of the iron phosphate. Wherein the atomic number of the iron element and the phosphorus element when the ferric hydroxide colloid is dissolved in the phosphoric acid solution is 1 (1-1.2), and the ferric phosphate (FePO) is used4) The atomic number ratio of the iron element to the phosphorus element is 1:1, so that the atomic number of the phosphorus element is at least not less than that of the iron element, and if the phosphorus element is slightly excessive, the iron element can be effectively promoted to completely participate in the reaction to generate phosphorus as far as possibleAnd the iron is beneficial to improving the recovery rate of the iron element in the pyrite cinder.
Further, in the embodiment, the concentration of the selected phosphoric acid solution is 20-40% to avoid the adverse effect on the preparation process caused by the corrosivity generated when the high-concentration phosphoric acid solution is heated.
And step S50, washing, drying and calcining the solid product to obtain a high-purity iron phosphate product.
The solid product is a crude product of iron phosphate, the solid product is washed with water to remove a reaction solvent remaining on the surface of the solid product, then the solid product is dried to remove moisture in the solid product, and finally organic matters or hydrochloride and other components in the crude product are removed through calcination, so that a high-purity iron phosphate product can be obtained, wherein the iron phosphate obtained through calcination can be obtained through a conventional method in the field, and details are not repeated herein.
In the technical scheme provided by the invention, pyrite cinder powder is mixed with an acid solution, the mixture is heated to 60-120 ℃ for hydrothermal reaction for 6-12 h, then reaction liquid is separated out, the temperature of the reaction liquid is adjusted to 60-90 ℃, the pH value is adjusted to 1.8-2.0, then the mixture is stirred and purified to obtain ferric hydroxide colloid, the ferric hydroxide colloid is mixed with phosphoric acid and then heated to 80-160 ℃ for hydrothermal reaction for 6-12 h, after the reaction is completed, a generated solid product is separated out, then the solid product is washed, dried and calcined to obtain a high-purity ferric phosphate product, the method not only can realize the resource reutilization of pyrite cinder, reduce the environmental pollution, but also has the advantages of simple process, mild conditions and less secondary pollution, improves the conversion utilization rate of iron elements in pyrite cinder and the purity of the prepared ferric phosphate product, and the prepared ferric phosphate product has multiple purposes, the method can be used for manufacturing lithium iron phosphate battery materials, catalysts and ceramics, improves the added value of products for preparing the iron phosphate by using the pyrite cinder, and generates certain economic benefit by recycling the pyrite cinder.
The technical solutions of the present invention are further described in detail below with reference to specific examples and drawings, it should be understood that the following examples are merely illustrative of the present invention and are not intended to limit the present invention.
Example 1
(1) Washing pyrite cinder (comprising 43.31 percent of ferroferric oxide, 8.13 percent of ferric oxide, 1.63 percent of calcium oxide, 0.46 percent of magnesium oxide, 35.73 percent of silicon oxide and 0.16 percent of sulfur by mass percentage), drying, crushing by using a high-speed crusher, sieving by using a 200-mesh sieve to prepare pyrite cinder powder with the particle size of 200 meshes, adding 50 percent sulfuric acid solution into the pyrite cinder powder according to the solid-to-liquid ratio of 150g/L, and stirring until the mixture is uniformly mixed to form a mixture;
(2) transferring the mixture into a hydrothermal reaction kettle, heating to 80 ℃, carrying out hydrothermal reaction for 8 hours, filtering the reacted mixture, and collecting filtrate to obtain reaction liquid;
(3) adding ammonia water into the reaction solution until the pH value is 1.5, then heating to 100 ℃, stirring for 0.5h, transferring into a dialysis bag for purification for 12h, placing the dialysis bag loaded with the mixture on a shaking table with the rotating speed of 100rpm every 1.5h during purification, shaking for 10min, and obtaining ferric hydroxide colloid after purification;
(4) mixing an iron hydroxide colloid with a phosphoric acid solution with the concentration of 25% according to the iron-phosphorus atomic number ratio of 1:1, stirring until the iron hydroxide colloid is completely dissolved, transferring into a hydrothermal reaction kettle, heating to 120 ℃ for hydrothermal reaction for 8 hours, filtering the mixed solution after reaction, and collecting a solid product;
(5) and washing, drying and calcining the solid product to obtain the iron phosphate product.
Wherein the recovery rate of iron in the pyrite cinder is 90.3%, the purity of the prepared iron phosphate product is 99.0%, and the iron-phosphorus atomic number ratio in the prepared iron phosphate product is 1: 0.96.
Example 2
(1) Washing pyrite cinder (comprising 43.31 percent of ferroferric oxide, 8.13 percent of ferric oxide, 1.63 percent of calcium oxide, 0.46 percent of magnesium oxide, 35.73 percent of silicon oxide and 0.16 percent of sulfur by mass percentage), drying, crushing by using a high-speed crusher, sieving by using a 100-mesh sieve to prepare pyrite cinder powder with the particle size of 100 meshes, adding 40 percent sulfuric acid solution into the pyrite cinder powder according to the solid-to-liquid ratio of 100g/L, and stirring until the mixture is uniformly mixed to form a mixture;
(2) transferring the mixture into a hydrothermal reaction kettle, heating to 120 ℃, carrying out hydrothermal reaction for 6 hours, filtering the reacted mixture, and collecting filtrate to obtain reaction liquid;
(3) adding ammonia water into the reaction solution until the pH value is 1.0, then heating to 80 ℃, stirring for 1h, transferring into a dialysis bag for purification for 18h, placing the dialysis bag loaded with the mixture on a shaking table with the rotating speed of 100rpm every 2h during purification, shaking for 20min, and obtaining ferric hydroxide colloid after purification is finished;
(4) mixing iron hydroxide colloid with a phosphoric acid solution with the concentration of 35% according to the iron-phosphorus atomic number ratio of 1:1.2, stirring until the iron hydroxide colloid is completely dissolved, transferring into a hydrothermal reaction kettle, heating to 90 ℃, carrying out hydrothermal reaction for 12 hours, filtering the mixed solution after reaction, and collecting a solid product;
(5) and washing, drying and calcining the solid product to obtain the iron phosphate product.
Wherein the recovery rate of iron in the pyrite cinder is 92.5%, the purity of the prepared iron phosphate product is 98.9%, and the iron-phosphorus atomic number ratio in the prepared iron phosphate product is 1: 1.12.
Example 3
(1) Washing pyrite cinder (comprising 43.31 percent of ferroferric oxide, 8.13 percent of ferric oxide, 1.63 percent of calcium oxide, 0.46 percent of magnesium oxide, 35.73 percent of silicon oxide and 0.16 percent of sulfur by mass percentage), drying, crushing by using a high-speed crusher, sieving by using a 500-mesh sieve to prepare pyrite cinder powder with the particle size of 500 meshes, adding 37 percent hydrochloric acid solution into the pyrite cinder powder according to the solid-to-liquid ratio of 250g/L, and stirring until the mixture is uniformly mixed to form a mixture;
(2) transferring the mixture into a hydrothermal reaction kettle, heating to 60 ℃, carrying out hydrothermal reaction for 12h, filtering the reacted mixture, and collecting filtrate to obtain reaction liquid;
(3) adding urea into the reaction solution until the pH value is 1.5, then heating to 100 ℃, stirring for 0.5h, transferring into a dialysis bag for purification for 18h, placing the dialysis bag loaded with the mixture on a shaking table with the rotating speed of 100rpm every 1h during purification, shaking for 30min, and obtaining ferric hydroxide colloid after purification is finished;
(4) mixing ferric hydroxide colloid with a phosphoric acid solution with the concentration of 40% according to the iron-phosphorus atomic number ratio of 1:1.1, stirring until the ferric hydroxide colloid is completely dissolved, transferring into a hydrothermal reaction kettle, heating to 100 ℃, carrying out hydrothermal reaction for 12 hours, filtering the mixed solution after reaction, and collecting a solid product;
(5) and washing, drying and calcining the solid product to obtain the iron phosphate product.
Wherein the recovery rate of iron in the pyrite cinder is 91.6%, the purity of the prepared iron phosphate product is 99.2%, and the iron-phosphorus atomic number ratio in the prepared iron phosphate product is 1: 1.03.
Example 4
(1) Washing pyrite cinder (containing the following components, by mass, 43.31% of ferroferric oxide, 8.13% of ferric oxide, 1.63% of calcium oxide, 0.46% of magnesium oxide, 35.73% of silicon oxide and 0.16% of sulfur), drying, crushing by using a high-speed crusher, sieving by using a 300-mesh sieve to obtain pyrite cinder powder with the particle size of 300 meshes, adding an acid solution (the volume ratio of 50% hydrochloric acid to 30% sulfuric acid solution is 1:1) into the pyrite cinder powder according to a solid-to-liquid ratio of 50g/L, and stirring until the mixture is uniformly mixed to form a mixture;
(2) transferring the mixture into a hydrothermal reaction kettle, heating to 100 ℃, carrying out hydrothermal reaction for 9 hours, filtering the reacted mixture, and collecting filtrate to obtain reaction liquid;
(3) adding urea into the reaction solution until the pH value is 1.2, then heating to 90 ℃, stirring for 2h, transferring into a dialysis bag for purification for 20h, placing the dialysis bag loaded with the mixture on a shaking table with the rotating speed of 100rpm every 3h during purification, shaking for 15min, and obtaining ferric hydroxide colloid after purification is finished;
(4) mixing iron hydroxide colloid with a phosphoric acid solution with the concentration of 20% according to the iron-phosphorus atomic number ratio of 1:1.2, stirring until the iron hydroxide colloid is completely dissolved, transferring into a hydrothermal reaction kettle, heating to 80 ℃, carrying out hydrothermal reaction for 10 hours, filtering the mixed solution after reaction, and collecting a solid product;
(5) and washing, drying and calcining the solid product to obtain the iron phosphate product.
Wherein the recovery rate of iron in the pyrite cinder is 91.2%, the purity of the prepared iron phosphate product is 99.3%, and the iron-phosphorus atomic number ratio in the prepared iron phosphate product is 1: 1.1.
Example 5
(1) Washing pyrite cinder (comprising 43.31 percent of ferroferric oxide, 8.13 percent of ferric oxide, 1.63 percent of calcium oxide, 0.46 percent of magnesium oxide, 35.73 percent of silicon oxide and 0.16 percent of sulfur by mass percentage), drying, crushing by using a high-speed crusher, sieving by using a 400-mesh sieve to prepare pyrite cinder powder with the particle size of 400 meshes, adding 60 percent sulfuric acid solution into the pyrite cinder powder according to the solid-to-liquid ratio of 200g/L, and stirring until the mixture is uniformly mixed to form a mixture;
(2) transferring the mixture into a hydrothermal reaction kettle, heating to 90 ℃, carrying out hydrothermal reaction for 10 hours, filtering the reacted mixture, and collecting filtrate to obtain reaction liquid;
(3) adding ammonia water into the reaction solution until the pH value is 1.3, then heating to 60 ℃, stirring for 1.5h, transferring into a dialysis bag for purification for 24h, placing the dialysis bag loaded with the mixture on a shaking table with the rotating speed of 100rpm every 2h during purification, shaking for 20min, and obtaining ferric hydroxide colloid after purification is finished;
(4) mixing ferric hydroxide colloid with phosphoric acid solution with the concentration of 25% according to the iron-phosphorus atomic number ratio of 1:1.2, stirring until the ferric hydroxide colloid is completely dissolved, transferring into a hydrothermal reaction kettle, heating to 160 ℃, carrying out hydrothermal reaction for 6 hours, filtering the mixed solution after reaction, and collecting a solid product;
(5) and washing, drying and calcining the solid product to obtain the iron phosphate product.
Wherein the recovery rate of iron in the pyrite cinder is 92.1%, the purity of the prepared iron phosphate product is 99.0%, and the iron-phosphorus atomic number ratio in the prepared iron phosphate product is 1: 1.05.
Taking the above example 1 as an example, the microstructure of the iron phosphate product prepared by the method is tested, and fig. 2 and 3 show an SEM image (surface microstructure photographed by a scanning electron microscope) and an XRD image (X-ray diffraction pattern) of the iron phosphate product prepared in example 1, respectively.
As can be seen from FIG. 2, FePO obtained in example 14The product is formed by the agglomeration of a plurality of micro nano particles, and the surface is rough and snowflake-shaped. FePO of this structure4The material has larger specific surface area, and has higher application value both when being used as a raw material for preparing lithium iron phosphate and used as a carrier of a catalyst.
As can be seen from FIG. 3, FePO obtained in example 14The samples showed [100 ] appearance of hexagonal iron phosphate at 20o, 25o, 42o, 58o, etc]、[102]、[201]、[211]The characteristic diffraction peak of the isomorphic surface is narrow, sharp and has no impurity peak. Shows that the prepared product is pure phase FePO4Belonging to the hexagonal system, space group P3121(152), and the unit cell parameter is
In conclusion, the method for preparing high-purity iron phosphate by using the pyrite cinder provided by the embodiment of the invention can realize the resource reutilization of the pyrite cinder, reduces the environmental pollution, has the advantages of simple process, mild conditions and less secondary pollution, and improves the conversion utilization rate of iron elements in the pyrite cinder and the product purity of the prepared iron phosphate, wherein the recovery rate of iron in the pyrite cinder can reach 90.3-92.5%, the purity of the iron phosphate product can reach 98.9-99.3%, the prepared high-purity iron phosphate has a large specific surface area, can be used as a raw material for preparing lithium iron phosphate or a catalyst carrier and the like, has a high application value, and improves the additional value of the product for preparing the iron phosphate by using the pyrite cinder.
The above is only a preferred embodiment of the present invention, and it is not intended to limit the scope of the invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall be included in the scope of the present invention.
Claims (8)
1. The method for preparing high-purity iron phosphate by using pyrite cinder is characterized by comprising the following steps of:
cleaning, drying and crushing the pyrite cinder to form pyrite cinder powder, and then mixing the pyrite cinder powder with an acid solution to form a mixture;
heating the mixture to 60-120 ℃ to perform hydrothermal reaction for 6-12 h, then separating solid from liquid and collecting reaction liquid;
adjusting the temperature of the reaction solution to 60-100 ℃, adjusting the pH value to 1.0-1.5, stirring and purifying to obtain ferric hydroxide colloid;
dissolving the ferric hydroxide colloid in a phosphoric acid solution, heating to 80-160 ℃ for hydrothermal reaction for 6-12 h, separating solid from liquid, and collecting a solid product;
washing, drying and calcining the solid product to obtain a high-purity iron phosphate product;
adjusting the temperature of the reaction solution to 60-100 ℃, adjusting the pH value of the reaction solution to 1.0-1.5, and purifying after stirring to obtain the ferric hydroxide colloid, which specifically comprises the following steps:
adjusting the temperature of the reaction solution to 60-100 ℃, adjusting the pH value to 1.0-1.5, stirring for 0.5-2 h, and then putting the reaction solution into a dialysis bag for purification for 6-12 h to obtain ferric hydroxide colloid;
the pyrite cinder comprises 43.31% of ferroferric oxide, 8.13% of ferroferric oxide, 1.63% of calcium oxide, 35.75% of magnesium oxide, 0.46% of silicon oxide and 0.16% of sulfur by mass.
2. The method for preparing high-purity iron phosphate from pyrite cinder as claimed in claim 1, wherein the step of washing, drying and crushing the pyrite cinder to form pyrite cinder powder, and then mixing with the acid solution to form the mixture, comprises:
the particle size of the pyrite cinder powder is 100-500 meshes.
3. The method for preparing high-purity iron phosphate from pyrite cinder as claimed in claim 1, wherein the step of washing, drying and crushing the pyrite cinder to form pyrite cinder powder, and then mixing with the acid solution to form the mixture, comprises:
and the solid-to-liquid ratio of the pyrite cinder powder to the acid solution is 50-250 g/L when the pyrite cinder powder and the acid solution are mixed.
4. The method for preparing high-purity iron phosphate from pyrite cinder as claimed in claim 1, wherein the step of washing, drying and crushing the pyrite cinder to form pyrite cinder powder, and then mixing with the acid solution to form the mixture, comprises:
the acid solution is at least one of a sulfuric acid solution and a hydrochloric acid solution, wherein the concentration of the sulfuric acid solution is 40-60%, and the concentration of the hydrochloric acid solution is 20-37%.
5. The method for preparing high-purity iron phosphate from pyrite cinder as claimed in claim 1, wherein the step of adjusting the temperature of the reaction solution to 60-100 ℃ and the pH value to 1.0-1.5, stirring and purifying to obtain iron hydroxide colloid comprises:
the method for adjusting the pH value of the reaction solution to 1.0-1.5 comprises the following steps: and adding ammonia water or urea into the reaction liquid.
6. The method for preparing high-purity iron phosphate by using pyrite cinder as claimed in claim 1, wherein the temperature of the reaction solution is adjusted to 60-100 ℃, the pH value is adjusted to 1.0-1.5, the reaction solution is stirred for 0.5-2 h, and then the reaction solution is put into a dialysis bag for purification for 6-12 h, so as to obtain iron hydroxide colloid, wherein the step comprises:
and (3) putting the reaction solution into a dialysis bag for purification for 6-12 h, and further comprising the following steps: shaking the dialysis bag filled with the reaction solution every 1-3 hours for 10-30 min.
7. The method for preparing high-purity iron phosphate from pyrite cinder as claimed in claim 1, wherein said ferric hydroxide colloid is dissolved in phosphoric acid solution, then heated to 80-160 ℃ for hydrothermal reaction for 6-12 h to separate solid from liquid, and then solid product is collected:
the atomic number of the iron element and the phosphorus element when the ferric hydroxide colloid is dissolved in the phosphoric acid solution is 1 (1-1.2).
8. The method for preparing high-purity iron phosphate from pyrite cinder as claimed in claim 1, wherein said ferric hydroxide colloid is dissolved in phosphoric acid solution, then heated to 80-160 ℃ for hydrothermal reaction for 6-12 h to separate solid from liquid, and then solid product is collected:
the concentration of the phosphoric acid solution is 20-40%.
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| CN114014294B (en) * | 2021-12-08 | 2023-08-22 | 高点(深圳)科技有限公司 | Method for preparing lithium iron phosphate by using pyrite and lithium iron phosphate material |
| CN114394581B (en) * | 2022-01-21 | 2023-01-31 | 雅安天蓝新材料科技有限公司 | Ferric phosphate dihydrate, preparation method thereof, ferric phosphate, lithium iron phosphate and lithium ion battery |
| CN114477121A (en) * | 2022-02-25 | 2022-05-13 | 湖南长宏新能源材料有限责任公司 | Production of battery-grade iron phosphate from iron-containing waste residues |
| CN114684801B (en) * | 2022-03-08 | 2023-09-01 | 四川大学 | Method for preparing high-purity ferric phosphate by using pyrite cinder |
| CN114604837B (en) * | 2022-03-30 | 2022-10-21 | 湖北宇浩高科新材料有限公司 | Preparation method of iron phosphate and preparation method of lithium iron phosphate |
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