70 results about "Phosphate product" patented technology

The invention discloses a method for preparing battery-grade iron phosphate by utilizing phosphated residues. The method comprises the following steps: pre-treating the phosphated residues; alkaline leaching is conducted on the phosphated residues, wherein the phosphated residues are placed in a sodium hydroxide solution with the mass fraction being 30%; decoloring is performed; acid treatment: adding hydrochloric acid into the filtrate to adjust the pH value, adding a solution composed of urotropin, thiourea, tetraethylammonium oxalate, hydrogen peroxide and polydodecyl acrylamide acrylic acid, and stirring; extracting: adding an extracting agent and an organic solution, and extracting under a stirring condition; precipitating: heating the raffinate, adding hexadecyl trimethyl ammonium chloride, and stirring; then adding a ferric nitrate solution to carry out precipitation reaction; the method for preparing the battery material ferric phosphate product by taking phosphated residue solid wastes generated in the steel metal product process as raw materials through the steps of pretreatment, alkaline leaching, decoloration, acid treatment, extraction, precipitation reaction and the like has the advantages of simple process, high product quality, low production cost, high recovery efficiency of phosphorus resources in the waste residues and the like.

The invention provides a method for efficiently recovering low-concentration copper ions in wastewater based on phosphoric acid gradient regulation and seed crystal induction, which comprises the following steps: firstly, removing impurities such as Fe < 3 + >, Al < 3 + > and the like by using an acid-resistant flocculant under an acidic condition, and carrying out solid-liquid separation; adding nano hydroxyl copper phosphate seed crystals and a phosphoric acid solution into the supernate, inducing to generate high-purity copper phosphate crystals through stepped stirring under a neutral condition, and synchronously strengthening solid-liquid separation; the separated precipitate part is subjected to low-temperature calcination to be regenerated into active seed crystals for cyclic utilization, and the rest part is subjected to washing and vacuum drying to prepare a high-purity copper phosphate product. According to the method, gradient pH regulation and control, seed crystal induced crystallization and closed-loop regeneration technologies are innovatively combined, the copper ion recovery rate is larger than 95%, the product can be directly used for production of catalysts or battery materials, meanwhile, the agent consumption is reduced by 40% or above, the sludge amount is reduced by 50%, and high efficiency, economical efficiency and environmental protection value are achieved.

The invention relates to a phosphorite wet processing method, and belongs to the technical field of chemical engineering. The phosphorite wet processing method comprises the following steps: A, phosphorite acid leaching: carrying out acidolysis leaching on a phosphorite raw material, and carrying out solid-liquid separation to obtain wet-process phosphoric acid; b, removing metal ions from wet-process phosphoric acid; and C, wet-process phosphoric acid defluorination: extracting fluosilicic acid in wet-process phosphoric acid at 10-70 DEG C by adopting a wet-process phosphoric acid defluorination extraction agent, and carrying out phase splitting to obtain defluorinated purified phosphoric acid and an organic phase loaded with fluosilicate. According to the invention, high-value utilization of low-grade phosphorite resources is realized. According to the method, impurities can be fully removed, the loss rate of phosphoric acid is low, the purity of the finally obtained phosphate product reaches 97% or above, the product quality is high, and the requirements of different fields for high-quality phosphate can be met. The method is simple in process, low in energy consumption and low in cost.

The invention relates to the technical field of phosphorus chemical industry, in particular to a method for preparing monoammonium phosphate from raffinate acid, which comprises the following steps: S1) uniformly mixing the raffinate acid with concentrated sulfuric acid, concentrating, and performing solid-liquid separation to obtain a concentrated solution; s2) dropwise adding a solvent into the concentrated solution for primary solvent purification; the solvent components are limited; s3) standing and splitting the light and heavy mixed phase obtained by purifying the primary solvent to obtain an acid-containing solvent phase; s4) mixing the acid-containing solvent phase with barium fluoride, carrying out a reaction, and carrying out solid-liquid separation to obtain a secondary purified acid-containing solvent and purified slag; s5) carrying out vacuum distillation on the secondary purified acid-containing solvent, and recovering the solvent to obtain a distillation kettle residual liquid which is purified acid; and S6) diluting the purified acid, then mixing the diluted purified acid with an ammonia-containing alkaline substance, carrying out a neutralization reaction, filtering after the reaction, and drying and granulating a filter cake to obtain the fire-fighting grade monoammonium phosphate product. The method provided by the invention has the advantages of high impurity removal rate, high phosphorus yield and high added value of the product, and can be used for preparing fire-fighting grade monoammonium phosphate.

The invention belongs to the technical field of chemical product preparation, and provides a production method of instant expanded monopotassium phosphate. The method comprises the following steps: (1) neutralization: neutralizing a potassium hydroxide solution and a phosphoric acid solution to prepare monopotassium phosphate slurry; (2) spray drying: performing sectional drying on the monopotassium phosphate slurry in a vertical high-tower spray drying tower, wherein the vertical high-tower spray drying tower is set into a top high-temperature section, a middle shaping section and a bottom cooling section according to the length ratio from top to bottom, and high-temperature hot air is arranged at an inlet of the top high-temperature section; low-temperature hot air is supplemented into the joint of the middle shaping section and the top high-temperature section; separating, dedusting and recycling at an outlet of the bottom cooling section to obtain monopotassium phosphate primary product particles; and (3) cooling and screening to obtain a finished product. According to the production method, low-energy-consumption and high-efficiency production is realized through sectional type high tower spray drying, and the instant puffed monopotassium phosphate product with high puffing rate and high stability can be obtained.

The invention discloses a method for producing monopotassium phosphate by organic extraction of crude phosphoric acid, which comprises the following steps: carrying out desulfurization and defluorination on wet-process crude phosphoric acid, then removing heavy metals, adding the heavy metal removed crude phosphoric acid and extract liquor into a crude phosphoric acid extraction clarification tank, carrying out crude phosphoric acid extraction reaction, and carrying out phase separation to obtain an extraction phase and raffinate acid; washing the extract phase with purified phosphoric acid, feeding into a homogeneous pre-reaction tank, adding a potassium chloride solution, fully and uniformly mixing, feeding into a hydrochloric acid extraction reaction clarification tank for phase separation to obtain monopotassium phosphate slurry and a hydrochloric acid-containing extract phase, and performing solid-liquid separation on the monopotassium phosphate slurry to obtain monopotassium phosphate clear liquid; concentrating and crystallizing the monopotassium phosphate clear liquid to obtain a monopotassium phosphate product; the extract liquor is an alkylamine type extractant added with a diluent. The method is high in comprehensive economic value, the used extraction agent is excellent in comprehensive performance, and the prepared monopotassium phosphate product is good in quality.

The present invention relates to the technical field of corn soaking water recycling and treatment, and in particular to a process method for preparing potassium dihydrogen phosphate and magnesium hydrogen phosphate using corn soaking water, comprising the following steps: (1) the supernatant after the corn soaking water is settled is fed into a cationic resin column, and the collected effluent is used for standby; (2) the cationic resin column is rinsed in reverse flow with purified water, and then the cationic resin column is rinsed in forward flow with phosphoric acid, and the collected effluent is used for standby; (3) the standby effluent in step (2) is taken, concentrated, pH adjusted, heated, and after white solid suspension is precipitated, the mixture is kept warm and stirred for a period of time, then cooled, filtered, and the filtrate and precipitate are collected respectively; (4) the filtrate in step (3) is taken, phosphoric acid is added to adjust the pH, vacuum concentrated and crystallized, cooled, centrifuged, and the collected filter cake is rinsed and dried to obtain a potassium dihydrogen phosphate product. Potassium dihydrogen phosphate and magnesium hydrogen phosphate products can be obtained by the above process method.

The present invention provides a method for highly efficient recovery of low-concentration copper ions in wastewater based on phosphoric acid gradient regulation and seed induction. First, under acidic conditions, acid-resistant flocculants are used to remove impurities such as Fe<supgt;3+< / supgt> and Al<supgt;3+< / supgt>, followed by solid-liquid separation; subsequently, nano-hydroxy copper phosphate seeds and phosphoric acid solution are added to the supernatant, and high-purity copper phosphate crystals are induced to form through stepwise stirring under neutral conditions, while simultaneously strengthening solid-liquid separation; a part of the separated precipitate is regenerated into active seeds by low-temperature calcination for recycling, and the remaining part is washed and vacuum dried to obtain high-purity copper phosphate products. The present invention innovatively combines gradient pH regulation, seed-induced crystallization, and closed-loop regeneration technology, achieving a copper ion recovery rate > 95%. The product can be directly used in the production of catalysts or battery materials, while reducing the consumption of chemicals by more than 40% and reducing the sludge volume by 50%, combining high efficiency, economy, and environmental protection value.

The invention relates to a washing method of an iron phosphate product, and belongs to the technical field of iron phosphate product preparation, and the washing method comprises the following steps: S1, primary combined washing: putting an iron phosphate material to be treated into water, carrying out heat preservation washing at 80-99 DEG C for a first time, cooling to a second temperature, adding hydrochloric acid, controlling the pH to be 1-2, and carrying out primary combined washing; washing for a second time at a second temperature, and carrying out solid-liquid separation to obtain primary combined washed iron phosphate; s2, phosphoric acid washing: washing the primary combined washing iron phosphate with a phosphoric acid washing solution with a pH value of 0-2 for a third time at a third washing temperature, and carrying out solid-liquid separation to obtain phosphoric acid-washed iron phosphate, the pH value of the phosphoric acid washing solution being lower than the pH value of the primary combined washing; and S3, water washing: washing the phosphoric acid to wash the iron phosphate, and carrying out solid-liquid separation to obtain purified iron phosphate. The treatment method provided by the invention can simply and effectively remove constant amount of impurities in the iron phosphate-containing product and optimize the purity of the iron phosphate product.

The invention discloses phosphate as well as a preparation method and application thereof, and belongs to the technical field of chemical processes. The preparation method comprises the following steps: (1) esterification reaction: carrying out esterification reaction on an organic alcohol compound and phosphorus pentoxide to obtain a phosphate intermediate; and (2) alcoholysis reaction: adding C1-C8 monohydric alcohol into the phosphate intermediate, and performing alcoholysis on the polyphosphate in the phosphate intermediate to obtain the phosphate. According to the phosphate prepared by the method, a phosphate product with low free phosphoric acid content can be obtained without purification, the process stability is good, and the product can be used as an additive in the battery industry and the like and has a wide application prospect.

The invention relates to a method for preparing ferromanganese phosphate and a product, and the method comprises the following steps: adding ozone into a solution containing iron ions, divalent manganese ions and phosphoric acid to form a ferromanganese phosphate precipitate; according to the preparation method of the ferromanganese phosphate, provided by the invention, a battery-grade ferromanganese phosphate product can be stably obtained, and the proportion of Mn to Fe in the ferromanganese phosphate can be adjusted as required.

The present invention discloses a production method of highly soluble sodium-potassium cross-linked modified phosphate. One or several of sodium phosphate salts such as acid sodium pyrophosphate and sodium pyrophosphate, and one or several of potassium phosphate salts such as potassium pyrophosphate and acid potassium pyrophosphate are used as raw materials. Through scientific proportioning, homogeneous emulsification, static mixing, boiling drying, and high-efficiency polymerization, a highly soluble sodium-potassium cross-linked modified phosphate product is produced. This production method has the characteristics of strong product adjustability, good product solubility, and low energy consumption.

Improved partitioning compositions for froth flotation of mineral ores, and improved methods of froth flotation using the partitioning compositions have been developed. The partitioning compositions are suitably added to a mineral ore slurry in a single addition to provide a sparge composition that is ready for sparging. The use of the partitioning compositions obviates the need to adjust the pH of the ore slurry before or after the addition, and further avoids the use of compounds having a flashpoint of 60 °C or less. Meanwhile, the partitioning compositions obtain improved grade and recovery of phosphate product (P2O5) in froth flotation of phosphate ores, when compared to conventional chemistry and methods used for froth flotation of a phosphate ores.

This invention provides a method for preparing ferromanganese phosphate. Using manganese, iron (containing ferric phosphate and / or ferric phosphate dihydrate), and phosphorus as raw materials, a seed induction solution is prepared. The solution is heated to generate NH4Fe(HPO4)2. This new biophase reduces the (Mn+Fe) / P ratio of the product during subsequent recrystallization of ferromanganese phosphate. After aging and recrystallization with ammonium ferromanganese phosphate slurry, a suitable (Mn+Fe) / P ratio of ferromanganese phosphate can be obtained through post-treatment. The preparation method of this invention can control the amount of new phase generated by controlling the amount of ferric phosphate and ferric phosphate dihydrate in the raw materials, thereby controlling the (Mn+Fe) / P ratio in the final product, ferromanganese phosphate. This preparation method is simple to operate, easy to implement, has good process stability, requires no additional surfactant, and offers high controllability of the (Mn+Fe) / P ratio in the product, which can be adjusted according to requirements. The prepared ferromanganese phosphate product has a controllable (Mn+Fe) / P ratio and low impurity content.

The invention relates to a continuous preparation method and system for iron phosphate white materials. The continuous operation of iron source pretreatment, yellow material generation, homogenizing batching, multi-stage preheating, tubular crystal transformation, aging reaction, post-treatment and the like is covered. Through segmented burdening, temperature control, pH adjustment, in-tube continuous oxidation-precipitation, in-tube continuous crystal transformation and membrane washing, uniform and stable reaction and efficient removal of impurities are effectively realized, and the purity and electrochemical performance of the product are remarkably improved. According to the process, reaction parameters are optimized, uniform material mixing, crystal growth control and effective impurity removal are realized, and experimental data shows that the anhydrous ferric phosphate product prepared by the process is superior to a traditional batch method in the aspects of particle size distribution, product purity and battery electrical performance of lithium iron phosphate synthesized by using the anhydrous ferric phosphate product as a precursor; the method has the advantages of high efficiency, energy conservation, high automation degree and the like, and is more suitable for large-scale industrial production of the lithium iron phosphate battery positive electrode material precursor.

The invention discloses a method for producing monopotassium phosphate from tricalcium phosphate, and relates to the technical field of production of monopotassium phosphate, a wet tricalcium phosphate product reacts with concentrated sulfuric acid, then a neutralizer is added, a sulfur removal agent and activated carbon are added into the obtained neutralized liquid, the mixture is refined and concentrated, then centrifugation is performed to obtain a wet monopotassium phosphate product, and the wet monopotassium phosphate product is dried until the water content is less than or equal to 0.5%, and obtaining a monopotassium phosphate finished product. The purity and the yield of the product are improved, and the production cost is reduced.

The utility model discloses a device that improves food -grade phosphate product packing efficiency, aims at solving the problem of " bin explosion " and unqualified product processing when automatic packing line breaks down. The device is connected with automatic packing hopper and screw conveyer through guide pipe, and the material is conveyed to artificial packing hopper through scraper machine; guide pipe is equipped with switch structure, and the switch structure is driven by electric push rod to control the conduction of piston structure (including plugging ball), and the plugging ball top accommodating groove can reduce abrasion and guarantee sealing; control module adopts time relay and relay module, and realizes the timing extension and contraction of electric push rod. When automatic line breaks down, the device can quickly transfer material, avoid " bin explosion " and unqualified product, and reduce production interruption; when unqualified product is found, the device can be transferred into artificial bin for processing in time. Its simple and reliable structure, controllable cost, not only improves packing efficiency, but also guarantees the continuity of food additive packing link, and is favorable for enterprise benefit improvement.

The invention relates to a method for treating ferrophosphorus waste, which comprises the following steps: carrying out alkaline leaching on the ferrophosphorus waste to be treated, and carrying out solid-liquid separation to obtain a leaching solution and leaching residues; after the pH value of the leachate is adjusted to 6.5-8.0, standing is conducted, solid-liquid separation is conducted, and a solution A rich in phosphate radicals and a slag phase A are obtained; after the leaching residues react with inorganic acid, solid-liquid separation is conducted, and a solution B and a residue phase B are obtained; mixing the solution A and the solution B, and after the reaction is finished, carrying out solid-liquid separation to obtain iron phosphate dihydrate and residual liquid; and subsequently purifying and dehydrating the iron phosphate dihydrate to obtain a high-purity iron phosphate product. According to the method, through comprehensive impurity removal under common conditions of acid, alkali, neutrality and the like, effective removal of various impurity elements is finally achieved, a pure iron source and a pure phosphorus source can be stably obtained, then the iron phosphate dihydrate or iron phosphate product with uniform and stable properties is prepared, the process is simple and efficient, the applicability to raw materials is wide, and the method has good industrial application prospects.

The invention discloses a production method and a co-production method of a monoammonium phosphate production device, the production device comprises a first device and a second device, and the co-production method is characterized in that the first device and the second device are partially connected, so that the effect that the two devices are simultaneously matched for production is achieved. The method provided by the invention can break through the limitation of the processing capacity of the existing production equipment. The first device and the second device can separately produce monoammonium phosphate, after the first device and the second device are linked for production, part of slurry can be introduced into the second device for drying and other links, and the pressure of the first device is relieved, so that the production load is increased, and the yield is increased. Meanwhile, indexes such as the moisture content of the monoammonium phosphate can be optimized, the moisture of the monoammonium phosphate product is further reduced and is more stable through reasonable treatment of a drying link of the second device, and the stability and consistency of the quality of the monoammonium phosphate are improved.

The method for producing powdery high-concentration monoammonium phosphate by two-stage neutralization of high-impurity raffinate acid is as follows: the by-product raffinate acid generated in the production process of wet purified phosphoric acid is preheated to 65-75 DEG C, ammonia gas is first introduced to perform a first-stage neutralization reaction, the pre-stable impurity neutralization slurry is obtained after constant temperature ripening, ammonia gas is introduced to perform a second-stage neutralization reaction on the pre-stable impurity neutralization slurry, the qualified monoammonium phosphate slurry is obtained after constant temperature ripening, the qualified monoammonium phosphate slurry is continuously subjected to grading concentration, drying is performed after the slurry solid content is concentrated to 70-75%, and the powdery high-concentration monoammonium phosphate product is prepared. The present application takes the by-product high-impurity raffinate acid generated in the production process of wet purified phosphoric acid as the only phosphorus source, realizes full-value utilization of the raffinate acid, the process is green and environmentally friendly, and is suitable for industrialized continuous production.

The invention relates to a method for preparing ferromanganese phosphate from potassium permanganate, which comprises the following steps: adding an oxidizing agent into a solution containing iron ions, divalent manganese ions and phosphoric acid to form ferromanganese phosphate precipitate, and the oxidizing agent is selected from manganic acid, alkali metal salt of manganic acid, permanganate, alkali metal salt of permanganate or ferric permanganate, preferably potassium permanganate or ferric permanganate. According to the preparation method of the ferromanganese phosphate, the ferromanganese phosphate product can be stably obtained, and the proportion of Mn to Fe in the ferromanganese phosphate can be adjusted according to needs.

The utility model relates to the technical field of inositol production, in particular to a production system for preparing magnesium dihydrogen phosphate by utilizing inositol hydrolysis residues, which comprises a hydrolysis residue storage tank, a discharge port of the hydrolysis residue storage tank is communicated with a smashing device, a discharge port of the smashing device is communicated with a reaction kettle, and a discharge port of the reaction kettle is communicated with a filtering device. A liquid outlet of the filtering device is communicated with a first buffer kettle, a discharge port of the first buffer kettle is communicated with a decolorizing kettle, a decolorizing liquid outlet of the decolorizing kettle is communicated with a second buffer kettle, a discharge port of the second buffer kettle is communicated with a crystallization kettle, a crystal outlet of the crystallization kettle is communicated with a drying device, and a discharge port of the drying device is communicated with a product storage tank. According to the production system with the structure, continuous operation can be realized, phosphate in the inositol hydrolysis residues can be recycled, resource waste is avoided, and a high-yield, high-yield and high-purity monopotassium phosphate product can be obtained.

A composite lithium iron phosphate positive electrode material, a preparation method therefor, and the use thereof. The preparation method comprises the following steps: (1) mixing an iron source and a phosphorus source with a solvent to obtain a mixed solution, adjusting the pH value of the mixed solution to a first pH value and carrying out a first reaction, and then adjusting the pH value to a second pH value and carrying out a second reaction, so as to obtain composite iron phosphate containing ferric hydroxide; (2) sintering the composite iron phosphate, mixing same with a lithium source, and calcining same to obtain modified lithium iron phosphate; and (3) mixing the modified lithium iron phosphate with a silver salt solution, and carrying out a replacement reaction, so as to obtain the composite lithium iron phosphate positive electrode material. The method fully uses ferric hydroxide generated during the precipitation process of iron phosphate, so that no impurity removal step is required, and silver can be uniformly distributed in the ferric phosphate product, so as to form a uniformly dispersed conductive network, thus solving the problems of agglomeration and non-uniform dispersion.

The present application relates to waste resource utilization technical field, specifically to a method for preparing aluminum dihydrogen phosphate from municipal sludge gasification slag, wherein the gasification slag is first crushed and then subjected to acid leaching treatment, so that the phosphorus and aluminum in the gasification slag are partially in the form of ions into the solution, the obtained acid leaching solution is removed from Fe 3+ and other impurity ions through an activated carbon adsorption column, then the aluminum and phosphorus in the solution are precipitated and separated in the form of aluminum phosphate by adjusting the pH value, and finally the obtained aluminum phosphate precipitate is mixed with phosphoric acid at a certain ratio to synthesize aluminum dihydrogen phosphate under heating conditions. The method has simple process and mild conditions, effectively solves the disposal problem of municipal sludge gasification slag, realizes the high-value recovery of phosphorus and aluminum resources, and the prepared aluminum dihydrogen phosphate product has high purity, which has significant environmental and economic benefits.

The invention relates to the technical field of inositol, and provides a method for producing inositol and co-producing monopotassium phosphate by using a corn soak solution, and the method comprises the following steps: S1, extracting phytic acid from the corn soak solution; s2, converting into a potassium phytate solution through a potassium hydroxide solution; s3, carrying out enzymolysis to obtain a mixed solution of inositol and monopotassium phosphate; s4, separating the mixed solution by adopting a multi-stage charge membrane to respectively obtain an inositol solution and a monopotassium phosphate solution; s5, performing concentration, crystallization, centrifugal separation, drying and screening on the inositol solution to obtain an inositol product; and S6, after the pH of the monopotassium phosphate solution is adjusted to be acidic, a monopotassium phosphate product is obtained through crystallization, centrifugal separation, drying and screening, and in the step S6, a crystallizing agent adopted for crystallization is composed of ethyl alcohol and acetonitrile. According to the technical scheme, the problems of low purity of inositol and monopotassium phosphate and complex process in the method for producing inositol and co-producing monopotassium phosphate by using the corn soaking solution in the related technology are solved.

Oxygen encapsulating agents, used to fight class A forest fires and rubber products (tires) that extinguish the fire by immediately cooling the materials, preventing their reignition and reducing toxic fumes from burning the treated materials, using phosphate products, particularly phosphate monoethanolamine, with the use of phosphoric ester additives, particularly the phosphoric ester of isotridecyl alcohol 6EO, resulting in a synergistic effect on fire suppression.

The invention provides a method for preparing lithium ferromanganese phosphate from ferrous phosphate composite ferromanganese phosphate. The method comprises the following steps: stirring and mixing an iron source, a manganese source, phosphoric acid, and an inorganic carbon source, and then adding an antioxidant and a phosphorus source to obtain a mixed solution; dripping an ammonia solution into the mixed solution, washing with water, filtering, and co-precipitating to obtain a ferromanganese phosphate precursor; crushing the ferromanganese phosphate precursor, adding it into a reactor and heating it, then adding a phosphoric acid solution, a lithium source, a phosphorus source, and an alkaline solution, reacting, filtering, and washing to obtain a filter cake; adding the filter cake, an antioxidant, a ferrous sulfate solution, phosphoric acid, an ammonium dihydrogen phosphate solution, and ammonia water into the reactor to form a mixed slurry; washing and filtering the mixed slurry with water to form a ferrous phosphate composite ferromanganese phosphate precursor; mixing the ferrous phosphate composite ferromanganese phosphate precursor with nano-sized lithium phosphate, an organic carbon source, an additive, and deionized water to form a mixture, and performing ball milling, drying, sintering, screening, batching, packaging, and other processes to obtain a finished lithium ferromanganese phosphate product.

This invention provides a method for preparing lithium iron phosphate from hydroxyferric phosphate and lithium iron phosphate electrode material. Ferrous sulfate is purified to form a ferrous sulfate solution. Hydrogen peroxide, phosphoric acid, ammonium dihydrogen phosphate solution, and ammonia are added to the ferrous sulfate solution to form a mixed slurry. The mixed slurry is kept at room temperature for a period of time, then washed with water and filtered to form hydroxyferric phosphate precursors with different iron-phosphorus ratios. These precursors are then flash-dried and sintered at high temperature to obtain hydroxyferric phosphate precursors with different iron-phosphorus ratios and specific surface areas. The hydroxyferric phosphate precursors are pulverized and mixed to obtain the finished hydroxyferric phosphate product. High-iron-phosphorus ratio hydroxyferric phosphate and low-iron-phosphorus ratio hydroxyferric phosphate are mixed in a certain proportion and then formulated with lithium phosphate, lithium iron phosphate, and electrode material in a specific ratio, with the addition of a carbon source and additives to form a mixture. The mixture is then subjected to ball milling, sand milling, spray drying, sintering, pulverizing, sieving, batching, and packaging processes to obtain the finished lithium iron phosphate product.

The invention discloses a gas chromatography method for detecting the content of trioctyl phosphate products and impurities, and belongs to the technical field of organic chemical detection. The core of the method is that (trimethylsilyl) diazomethane (TMSCH2N2) is adopted as a derivatization reagent, and dioctyl phosphate (P204) in a sample is subjected to rapid and safe derivatization at room temperature; an optimized dichloromethane-hexane mixed solvent system is adopted for dilution, so that the solubility is remarkably improved, and the toxicity is reduced; a first-order heating rapid screening method (17min) is suitable for industrial quality control, a multi-order heating accurate quantification method (29min) is suitable for small-scale test process research and development, and trioctyl phosphate (TOP), P204, isooctyl alcohol, isooctyl ether and chloro-isooctane can be accurately quantified at the same time. The method solves the problems of high toxicity, low efficiency, narrow detection range, single mode and the like in the prior art, and has the remarkable advantages of safety, high efficiency, accuracy, environmental protection and wide adaptability.

The application provides a method for preparing lithium iron phosphate from iron hydroxyl phosphate and ferrous oxalate. The ferrous sulfate is purified to form a ferrous sulfate solution. Hydrogen peroxide, phosphoric acid, ammonium dihydrogen phosphate solution and ammonia water are sequentially added to the solution to form a mixed slurry. The mixed slurry is heated and kept warm, and then washed with water and filtered under pressure to form an iron hydroxyl phosphate precursor with different iron and phosphorus ratios. The iron hydroxyl phosphate precursor is dried by flash evaporation and sintered at high temperature and then crushed to obtain an iron hydroxyl phosphate precursor with different iron and phosphorus ratios and different specific surface areas. The iron hydroxyl phosphate precursor is crushed and mixed to obtain an iron hydroxyl phosphate product. The high-iron and low-iron ratio iron hydroxyl phosphate is mixed with ferrous oxalate, lithium phosphate, lithium carbonate and ammonium dihydrogen phosphate in a certain proportion, and a carbon source and an additive are added to form a mixture. The mixture is subjected to a series of processes such as ball milling, sand milling, spray drying, sintering, crushing, screening, batching and packaging to obtain a lithium iron phosphate product.