CN111908440A - A kind of resource integrated utilization method of fipronil waste salt and titanium dioxide by-product ferrous sulfate - Google Patents

Abstract

The invention discloses a resource integrated utilization method of fipronil waste salt and titanium dioxide by-product ferrous sulfate. For sodium sulfate, a sodium phosphate solution is obtained; the titanium dioxide by-product ferrous sulfate is prepared into an aqueous solution, and a ferric sulfate solution is obtained through chemical impurity removal, water impurity removal and oxidation treatment; the sodium phosphate solution is added dropwise to the iron sulfate solution. Iron phosphate is generated under acidic conditions, filtered to obtain iron phosphate filter cake, and desalted by ball milling in the presence of water to obtain iron phosphate for batteries. The invention applies two kinds of waste salts to the preparation of iron phosphate, turns waste into treasure, and opens up channels for comprehensive utilization of different waste salts between different industries. In the present invention, ball milling is used for desalination in the presence of water. The ball milling reduces the size of the solid particles of the filter cake, increases the external surface area of the particles, and at the same time makes the impurity ions contained in the solid filter cake easier to remove, thereby greatly reducing the water consumption.

Description

Resource integrated utilization of a kind of fipronil waste salt and titanium dioxide by-product ferrous sulfate method

technical field

The invention relates to a resource integrated utilization method of fipronil waste salt and titanium dioxide by-product ferrous sulfate, and relates to the field of resource utilization of chemical and pesticide waste salt.

Background technique

Fipronil is a widely used insecticide. The fipronil technical production workshop produces about 3.3 tons of waste salt every day. Fipronil waste salt is a mixed salt. There are many kinds of salts. Its main components are sodium sulfite, sodium phosphate, and a small amount of sodium bromide and sodium sulfate. , sodium trifluoromethane sulfinate, and some benzene-based organics. Due to the high toxicity of organic matter and difficult to remove, waste fipronil salt can only be treated as hazardous waste, which brings great economic pressure to enterprises.

Titanium dioxide is one of the important chemical raw materials, widely used in coatings, plastics, papermaking, printing ink, chemical fiber and other industries. The total annual output of titanium dioxide in the country is close to 3 million tons. There are two main production processes of titanium dioxide, namely sulfuric acid method and chlorination sulfuric acid method. The above two processes are adopted by most manufacturers because of their small investment, simple process and high output. However, a large amount of by-products of ferrous sulfate are produced in the production process, and about 1-1.5 tons of by-products of ferrous sulfate are produced for every 1 ton of titanium dioxide produced. limit.

Patent CN 105692986 A proposes a treatment method for comprehensive utilization of waste salt, and proposes a separation and purification method according to the main substances in waste salt and the comprehensive ways and requirements. Ion: The concentrated water of the nanofiltration membrane is mixed and concentrated with the de-hardening concentrate, and the water produced by the nanofiltration membrane is further concentrated by the reverse osmosis membrane, and then the organic matter is removed by advanced oxidation, and finally the exhaust gas is treated, so that the waste salt generated in the zero discharge of wastewater can be obtained. Comprehensive utilization. Granting patents to the greatest extent possible reduces the addition of new substances such as pharmaceuticals and avoids secondary pollution. However, the operation of this process is complicated, the cost of nanofiltration membrane and reverse osmosis membrane is high, and it is difficult to carry out industrialized treatment.

Patent application CN 110204123 A discloses a resource utilization method of waste salt produced by fipronil, which is obtained by converting sodium sulfite in waste fipronil salt into sodium sulfate, and then reacting ferric sulfate with sodium phosphate in waste salt. Ferric phosphate products with higher added value, but the ferric sulfate used in this method comes from reagents, and there is still room for improvement in terms of cost reduction.

Patent CN103145197A provides a method for purifying titanium dioxide by-product ferrous sulfate: using titanium dioxide by-product ferrous sulfate to prepare ferrous sulfate heptahydrate solution; adjusting the pH value of the solution to 1-2.5, and treating titanium dioxide by-product sulfuric acid The ferrous iron is subjected to the hydrolysis treatment of titanium; the Fe ³⁺ in the ferrous sulfate heptahydrate after the titanium hydrolysis treatment is reduced and the pH value of the solution is adjusted to 6.0-6.5, and the ferrous sulfate by-product of titanium dioxide is subjected to magnesium and manganese. , Precipitation treatment of zinc; add flocculant to the above solution, stir, settling and filter, the filtrate is the purified ferrous sulfate solution. However, this process only refines ferrous sulfate, a by-product of titanium dioxide, and the added value is not high, and it does not turn waste into treasure.

Patent CN1766005 A relates to a method for preparing high-purity iron oxide yellow and iron oxide red by ferrous sulfate by-product of titanium dioxide. Under the condition that the temperature is lower than 60 ℃, the ferrous sulfate solution of titanium dioxide by-product is purified and removed from impurities, In the presence of an oxidant, the pH value of the solution is adjusted to achieve the purpose of removing titanium by hydrolysis and co-precipitation to remove metal ions such as zinc and manganese. Under the same reaction conditions, iron oxide yellow or iron oxide red is obtained with a purity of 99.5%.

SUMMARY OF THE INVENTION

The purpose of the present invention is to use ferric sulfate reagent when preparing ferric phosphate from fipronil waste salt in the prior art, the cost is higher, and the titanium dioxide by-product ferrous sulfate is caused by various impurities such as magnesium, manganese, titanium, and aluminum. Due to the limited use and other problems, an integrated method for resource utilization of fipronil waste salt and titanium dioxide by-product ferrous sulfate is provided, which can minimize the production cost of iron phosphate. Fipronil waste salt contains sodium sulfite and sodium phosphate. Sodium phosphate can react with ferric sulfate under acidic conditions to prepare iron phosphate, a precursor of lithium battery materials. However, under acidic conditions, sodium sulfite is easily acidified and converted into sulfur dioxide, resulting in environmental pollution. . Therefore, in order to utilize the phosphate ions in the waste fipronil salt, gas-liquid catalytic oxidation is first used to convert the sodium sulfite in the waste fipronil salt into sodium sulfate, and then the sodium phosphate in the waste salt is used. The by-product of titanium dioxide, ferrous sulfate, is rich in iron and a small amount of other metal ions. The by-product of titanium dioxide, ferrous sulfate, can be used to prepare iron phosphate, the precursor of lithium battery materials, but the impurities in the by-product ferrous sulfate will affect the phosphoric acid. The properties of iron materials must be removed by impurity ions and oxidation treatment to convert the by-product ferrous sulfate into relatively pure iron sulfate. Under acidic conditions, the pretreated waste fipronil salt and the pretreated titanium dioxide by-product waste salt ferrous sulfate undergo metathesis reaction to form ferric phosphate precipitation, and then the impurity ions in the ferric phosphate are removed by ball milling desalination , to obtain iron phosphate products that meet industry standards.

The purpose of this invention is to realize through the following technical solutions:

A method for integrated resource utilization of fipronil waste salt and titanium dioxide by-product ferrous sulfate. The waste fipronil salt is prepared into an aqueous solution, and the sodium sulfite in the waste salt is converted into sodium sulfate through gas-liquid catalytic oxidation to obtain phosphoric acid. Sodium solution; the by-product ferrous sulfate of titanium dioxide is prepared into an aqueous solution, and the ferric sulfate solution is obtained by chemical impurity removal, water impurity removal and oxidation treatment; sodium phosphate solution is added dropwise to the ferric sulfate solution, and metathesis occurs under acidic conditions The reaction produces ferric phosphate precipitation, which is filtered to obtain ferric phosphate filter cake and sodium sulfate filtrate, which is desalted by ball milling in the presence of water to obtain iron phosphate for batteries that meets industry standards, and the sodium sulfate filtrate is evaporated to obtain sodium sulfate.

The specific reaction process is represented by the following reaction equation:

2Na ₂ SO ₃ +O ₂ →2Na ₂ SO ₄

2FeSO ₄ +H ₂ SO ₄ +H ₂ O ₂ →Fe ₂ (SO ₄ ) ₃ +2H ₂ O

2Na ₃ PO ₄ +Fe ₂ (SO ₄ ) ₃ →2FePO ₄ ↓+3Na ₂ SO ₄

The resource integrated utilization method of fipronil waste salt and titanium dioxide by-product ferrous sulfate according to the present invention comprises the following steps:

Step (1), the waste fipronil salt is prepared into an aqueous solution, and in the presence of a catalyst, air is introduced to carry out gas-liquid catalytic oxidation, and the sodium sulfite in the waste fipronil salt is converted into sodium sulfate, and the obtained pH is 11～ 12 of sodium phosphate solution;

In step (2), the titanium dioxide by-product ferrous sulfate is prepared into an aqueous solution with an anhydrous ferrous sulfate concentration of 10 to 20%, followed by chemical impurity removal and water impurity removal treatment to convert the impurity metal ions into precipitation, and filter to remove Precipitation; then add concentrated sulfuric acid, use hydrogen peroxide as an oxidant to carry out oxidation treatment, oxidize ferrous sulfate in the filtrate to ferric sulfate to obtain a ferric sulfate solution, and use concentrated sulfuric acid to adjust the pH of the ferric sulfate solution to 1 to 2;

Step (3), dropping the sodium phosphate solution obtained in step (1) into the ferric sulfate solution obtained in step (2), so that a metathesis reaction occurs between sodium phosphate and ferric sulfate to obtain a ferric phosphate suspension;

The iron phosphate suspension obtained in step (4) and step (3) is filtered to obtain iron phosphate filter cake and sodium sulfate filtrate; the iron phosphate filter cake is subjected to ball milling desalination in the presence of water to remove sodium in the iron phosphate filter cake The sulfate of ion and other impurity metal ions is dried to obtain iron phosphate dihydrate product for battery; the sodium sulfate filtrate is evaporated to obtain sodium sulfate by-product.

The fipronil waste salt contains sodium sulfite, sodium phosphate, sodium bromide, sodium sulfate, sodium trifluoromethanesulfinate and water; wherein, the mass fraction of sodium sulfite is 20-28%, and the mass fraction of sodium phosphate is is 25-30%, the mass fraction of sodium bromide is 0.1-0.3%, the mass fraction of sodium sulfate is 0.5-1%, the mass fraction of sodium trifluoromethanesulfinate is 0.1-0.5%, and the rest is water.

The mass fraction of ferrous sulfate heptahydrate in the by-product ferrous sulfate of the titanium dioxide is 90-99%, and the impurity metal ions and mass fractions contained are: 0.3-0.6% of magnesium ions, 0.1-0.3% of manganese ions, and 0.1-0.3% of titanium 0.2 to 0.5% of ions, 0.02 to 0.05% of aluminum ions, and 0.02 to 0.05% of zinc ions.

In the step (1), the gas-liquid catalytic oxidation is as follows: the waste fipronil salt and deionized water or condensed water are prepared into an aqueous solution according to a mass ratio of 1:1～1.5, and in the presence of a catalyst, 10～25L/ (h·kg aqueous solution) was introduced into air, and the sodium sulfite was oxidized to sodium sulfate at a temperature of 30 to 95° C. When the oxidation rate of the sodium sulfite reached more than 99.5%, the reaction was stopped. Wherein, the dosage of the catalyst is 0.05% to 5% of the quality of the aqueous solution; the catalyst is nickel sulfate, chromium sulfate, cobalt sulfate, manganese sulfate, nickel phosphate, chromium phosphate, cobalt phosphate, manganese phosphate, nickel monoxide , one of manganese dioxide or cobalt tetroxide catalysts.

In step (2), the titanium dioxide by-product ferrous sulfate is prepared into an aqueous solution using deionized water or condensed water.

The chemical impurity removal treatment is as follows: using sodium sulfide solution as impurity remover to remove magnesium ions, manganese ions and zinc ions, the concentration of sodium sulfide is 30～80g/L, and the consumption of sodium sulfide is 1～80g/L of ferrous sulfate. 7%; the reaction temperature is controlled at 20～40℃, the reaction time is 1～2h, after the reaction is finished, it is left to stand for 2～4h, and the precipitate is removed by filtration to obtain a chemical impurity removal filtrate. The content of magnesium ion, manganese ion and zinc ion in the filtrate All <0.01%.

The hydrolysis treatment is as follows: adjusting the pH value of the solution to be 2-4, hydrolyzing at a temperature of 75-95° C. for 3-5 hours, and under this condition, the titanium ions and aluminum ions in the solution are hydrolyzed into hydroxide precipitation, Filtration is carried out to obtain a filtrate for de-impurification by water, and the content of titanium ions and aluminum ions in the filtrate for de-impurification by water is both <0.01%.

The oxidation treatment is as follows: adding concentrated sulfuric acid to the solution according to the mole ratio of H ₂ SO ₄ and ferrous sulfate being 0.498-0502:1; Hydrogen peroxide is added at 50 DEG C, and the feeding time is 50-90 minutes; after the oxidation reaction is completed, the oxidation rate of ferrous sulfate is over 99.5%. Since ferric sulfate will be hydrolyzed in the aqueous solution, in order to ensure that the content of iron in the ferric phosphate meets the quality index of ferric phosphate for batteries, the method of adding excess ferric sulfate is usually used, but the addition of excess ferric sulfate will cause unreacted ferric sulfate. It is difficult to separate the sodium sulfate obtained from the reaction, which increases the difficulty of purifying the sodium sulfate. Therefore, the present invention suppresses the hydrolysis of ferric sulfate by adjusting the pH value of the ferric sulfate solution obtained in step (2) to 1-2 by concentrated sulfuric acid.

The mass fraction of the concentrated sulfuric acid is 98%.

In step (3), according to the molar ratio of ferric sulfate and sodium phosphate being 0.4-0.8:1, preferably 0.495-0.505:1, the sodium phosphate solution obtained in step (1) is added dropwise to step (2) to obtain In the ferric sulfate solution, the dropping time is controlled to be 1 to 2 h, and the metathesis reaction temperature is 35 to 55 °C. By controlling the dropping time and reaction temperature to obtain iron phosphate particles with small and uniform particle size, after the dropping is completed, the temperature is increased. To 70～95 ℃, continue to react for 1～2h to obtain ferric phosphate suspension, filter to obtain ferric phosphate filter cake and sodium sulfate filtrate.

The mass fraction of sodium sulfate in the sodium sulfate filtrate is 9-15%.

The sodium sulfate solution is subjected to atmospheric evaporation treatment in a scraper evaporator, the evaporation temperature is 120-200 DEG C, and the water content of the sodium sulfate by-product obtained after evaporation is less than 1%. Part of the condensed water obtained by evaporation is used to prepare fipronil waste salt solution and titanium dioxide by-product ferrous sulfate salt solution, and part of the condensed water is used for ball milling desalination.

The preparation water of fipronil waste salt solution and titanium dioxide by-product ferrous sulfate solution is deionized water for the first time, and the rest are the evaporation condensed water of sodium sulfate filtrate obtained by metathesis reaction.

In step (4), described ball milling desalination is: under the condition that water exists, planetary ball mill carries out multiple ball milling desalination to iron phosphate filter cake, and removes the sulfate of sodium ion and other impurity metal ions in the filter cake. , to obtain iron phosphate particles with a particle size of <6 μm; the number of times of ball milling desalination is 3 to 10 times, and the amount of water used for each ball milling desalination is 5 times the mass of the iron phosphate filter cake. The content of various elements in the iron phosphate obtained after desalination by ball milling meets the quality indicators of the technical requirements (HG/T 4701-2014) in the national industry standard of iron phosphate for batteries.

The water used in ball milling desalination is deionized water or condensed water.

The filtrate obtained by ball milling and desalting was combined with the sodium sulfate filtrate and evaporated.

Compared with the prior art, the beneficial effects of the present invention:

The method firstly converts the sodium sulfite in the waste fipronil salt into sodium sulfate, so that the waste fipronil salt can be used under strong acid conditions, and avoids secondary pollution to the environment caused by the generation of toxic gas sulfur dioxide due to heating or acidolysis of sulfite radicals pollution, expanding its scope of application. In the invention, the by-product ferrous sulfate of titanium dioxide is subjected to impurity removal and oxidation treatment to obtain sulfate of high-valent iron, which can be applied to prepare iron phosphate. The invention applies two kinds of waste salts belonging to fine chemical industry and pesticide industry to the preparation of high value-added iron phosphate, realizes turning waste into treasure, and opens up channels for comprehensive utilization of different waste salts between different industries.

The inventor found through experiments that, without ball milling, it is necessary to use 80 to 100 times the mass of water of the iron phosphate filter cake for desalination in order to make the content of various elements in the iron phosphate meet the technical requirements in the national industry standard of iron phosphate for batteries. (HG/T4701-2014) quality index. In the present invention, ball milling is used for desalination in the presence of water. The ball milling reduces the size of the solid particles of the filter cake, increases the external surface area of the particles, and at the same time makes the impurity ions contained in the solid filter cake easier to be removed, greatly reducing the water consumption. It also avoids the energy consumed by drying the filter cake first and then pulverizing it, which not only saves energy, but also reduces the preparation cost of iron phosphate.

Description of drawings

Fig. 1 is the process flow diagram of the resource integrated utilization method of fipronil waste salt and titanium dioxide by-product ferrous sulfate.

Specific implementation method

The technical solutions of the present invention will be further described below through specific embodiments.

Example 1

The mass fraction of sodium sulfite in the waste fipronil salt is 24.2%, the mass fraction of sodium phosphate is 25.7%, the mass fraction of sodium bromide is 0.15%, the mass fraction of sodium sulfate is 0.74%, and the mass fraction of sodium trifluoromethanesulfinate 0.3%, the rest is moisture.

Add 50kg of waste salt into the reactor, add deionized water or condensed water according to the mass ratio of waste salt to water 1:1.2, stir at room temperature until the waste salt is completely dissolved, add 0.5kg of nickel sulfate and 0.3kg of chromium sulfate into the reactor As a catalyst, air was introduced at a flow rate of 12.4 L/(h·kg aqueous solution), and the reaction was carried out at 50° C. for 4 hours. The oxidation rate of sodium sulfite reached 99.6%, and the reaction was stopped to obtain a sodium phosphate solution with a pH value of 11.3.

Using the sodium phosphate solution obtained through gas-liquid catalytic oxidation as the phosphorus source, using the ferric sulfate solution (concentration of 15%) prepared with ferric sulfate (analytical grade) as the iron source to prepare the ferric phosphate product, and using 98% concentrated sulfuric acid to adjust the ferric sulfate solution. The pH is 1.3. At a temperature of 45 °C, according to the molar ratio of iron sulfate to sodium phosphate of 0.5, the sodium phosphate solution was added dropwise to the iron sulfate solution for 1 h. After the addition, the temperature was raised to 90 °C and stirred for 1 h to obtain The iron phosphate suspension is filtered to obtain filter cake and filtrate; in the presence of deionized water or condensed water, the filter cake is subjected to 10 ball milling desalination with a planetary ball mill, and the amount of water used for each ball milling desalination is 5 times the mass of the filter cake. , after desalting by ball milling, the iron phosphate with particle diameter <4 μm is obtained, and the iron phosphate dihydrate product is obtained by drying, and the content of each element in the iron phosphate product (see Table 1) meets the quality index of iron phosphate for batteries.

The content of sodium sulfate in the filtrate is 12.2%, and the atmospheric pressure evaporation treatment is carried out in a scraper evaporator, and the evaporation temperature is 150 ° C. kg. The condensed water obtained by evaporation is used to prepare fipronil waste salt solution and ferric sulfate solution.

Example 2

The mass fraction of ferrous sulfate heptahydrate in the by-product ferrous sulfate of titanium dioxide is 92.8%, and the metal ions and mass fractions contained are: magnesium ions 0.43%, manganese ions 0.26%, titanium ions 0.37%, aluminum ions 0.024%, zinc ions Ionic 0.022%.

Get 40kg of titanium dioxide by-product ferrous sulfate, use deionized water or condensed water to prepare an aqueous solution with anhydrous ferrous sulfate concentration of 16%, according to the amount of sodium sulfide is 6% of the quality of ferrous sulfate, add 27.1L to the aqueous solution The sodium sulfide solution with a concentration of 45g/L was reacted at a temperature of 25 °C for 2 hours, and then stood for 3 hours. The magnesium, manganese and zinc ions in the solution were converted into sulfide precipitates, and the precipitates were removed by filtration. The mass fraction of magnesium in the filtrate was 0.0023 %, the mass fraction of manganese is 0.0011%, and the mass fraction of zinc is 0%; then add 98% concentrated sulfuric acid to adjust the pH value of the filtrate to 3, hydrolyze at 90 ° C for 3 hours, and the titanium ions and aluminum ions in the solution are converted into The hydroxide was precipitated, and the precipitate was removed by filtration. The mass fraction of titanium in the filtrate was 0.0062%, and the mass fraction of aluminum was 0.0004%. In the solution through impurity removal, add 6.54kg 98% vitriol oil, the mol ratio of sulfuric acid (in H ₂ SO , the same below) and ferrous _sulfate is 0.5:1, slowly add 9.1kg 30% hydrogen peroxide (hydrogen peroxide consumption is 120% of the theoretical amount), the reaction temperature is 40 ° C, the hydrogen peroxide feeding time is 60min, and the oxidation rate of ferrous sulfate reaches 99.7% to obtain a ferric sulfate solution, adding 98% concentrated sulfuric acid to adjust the pH value of the ferric sulfate solution is 1.3.

The ferric sulfate solution obtained by removing impurities and oxidizing the by-product of titanium dioxide, ferrous sulfate, was used as the iron source, and the solution prepared with sodium phosphate (analytical grade) was used as the phosphorus source. At a temperature of 45 °C, according to the molar ratio of iron sulfate to sodium phosphate of 0.5, the sodium phosphate solution was added dropwise to the iron sulfate solution. , obtain ferric phosphate suspension, filter to obtain filter cake and filtrate; in the presence of deionized water or condensed water, use a planetary ball mill to perform 10 ball milling desalination on the filter cake, and the amount of water used for each ball milling desalination is 10% of the quality of the filter cake. 5 times, after desalting by ball milling, ferric phosphate with particle size <4 μm is obtained, and drying obtains ferric phosphate dihydrate product, and the content of each element in the ferric phosphate product (see Table 2) meets the quality index of ferric phosphate for batteries.

The content of sodium sulfate in the filtrate is 12.2%, and the atmospheric pressure evaporation treatment is carried out in a scraper evaporator, the evaporation temperature is 145 ° C, the water content in the sodium sulfate by-product obtained after evaporation is 0.5%, and the quality of the by-product sodium sulfate is 51.2 kg. The condensed water obtained by evaporation is used to prepare ferrous sulfate solution and sodium phosphate solution as by-products of titanium dioxide.

Example 3

The mass fraction of sodium sulfite in the waste fipronil salt is 24.2%, the mass fraction of sodium phosphate is 25.7%, the mass fraction of sodium bromide is 0.15%, the mass fraction of sodium sulfate is 0.74%, and the mass fraction of sodium trifluoromethanesulfinate 0.3%, the rest is moisture.

The mass fraction of ferrous sulfate heptahydrate in the by-product ferrous sulfate of titanium dioxide is 92.8%, and the metal ions and mass fractions contained are: magnesium ions 0.43%, manganese ions 0.26%, titanium ions 0.37%, aluminum ions 0.024%, zinc ions Ionic 0.022%.

Add 84.4kg waste salt into the reactor, add deionized water or condensed water according to the mass ratio of waste salt and water 1:1.2, stir at room temperature until the waste salt is completely dissolved, add 0.5kg nickel sulfate and 0.3kg sulfuric acid to the reactor Chromium was used as a catalyst, and air was introduced at a flow rate of 20.2 L/(h·kg aqueous solution), and the reaction was carried out at 50° C. for 4 hours. The oxidation rate of sodium sulfite reached 99.6%, and the reaction was stopped to obtain a sodium phosphate solution with a pH value of 11.3.

Get 40kg of titanium dioxide by-product ferrous sulfate, prepare an aqueous solution with anhydrous ferrous sulfate concentration of 15% with deionized water or condensed water, and add 27.1 L of ferrous sulfate to the aqueous solution according to the amount of sodium sulfide that is 6% of the mass of ferrous sulfate. The sodium sulfide solution with a concentration of 45g/L was reacted at a temperature of 25 °C for 2 hours, and then stood for 3 hours. The magnesium, manganese and zinc ions in the solution were converted into sulfide precipitates, and the precipitates were removed by filtration. The mass fraction of magnesium in the filtrate was 0.0021 %, the mass fraction of manganese is 0.0013%, and the mass fraction of zinc is 0%; then add 98% concentrated sulfuric acid to adjust the pH value of the filtrate to 3, hydrolyze at 90 ° C for 3 hours, and the titanium ions and aluminum ions in the solution are converted into The hydroxide is precipitated, and the precipitate is removed by filtration. The mass fraction of titanium in the filtrate is 0.0055%, and the mass fraction of aluminum is 0%. In the solution through impurity removal, add 6.54kg 98% vitriol oil, the mol ratio of sulfuric acid and ferrous sulfate is 0.5:1, then slowly add 9.1kg 30% hydrogen peroxide (hydrogen peroxide consumption is 120% of theoretical consumption), reaction The temperature is 40° C., the hydrogen peroxide feeding time is 60 minutes, the oxidation rate of ferrous sulfate reaches 99.7%, and a ferric sulfate solution is obtained, and 98% concentrated sulfuric acid is added to adjust the pH value of the ferric sulfate solution to 1.3.

The sodium phosphate solution obtained by gas-liquid catalytic oxidation was used as the phosphorus source, and the iron sulfate solution obtained by the by-product ferrous sulfate of titanium dioxide after impurity removal and oxidation treatment was used as the iron source. The molar ratio of the feedstock is 0.5, the sodium phosphate solution is added dropwise to the iron sulfate solution, the dropwise addition time is 1h, after the dropwise addition, the temperature is raised to 90 ° C, and stirred for 1h to obtain the iron phosphate suspension, and filter to obtain a filter cake and the filtrate; in the presence of deionized water or condensed water, a planetary ball mill is used to carry out 10 ball milling desalination on the filter cake, and the water consumption for each ball milling desalination is 5 times the quality of the filter cake, and after the ball milling desalination, the particle size < The iron phosphate of 4 μm is dried to obtain the iron phosphate dihydrate product, and the content of each element in the iron phosphate product (see Table 1 and Table 2) meets the quality index of iron phosphate for batteries.

The content of sodium sulfate in the filtrate is 11.7%, and the atmospheric pressure evaporation treatment is carried out in a scraper evaporator, the evaporation temperature is 145 ° C, the water content in the sodium sulfate by-product obtained after evaporation is 0.5%, and the quality of the by-product sodium sulfate is 52.8 kg.

Table 1. Comparison of the quality indexes of the obtained iron phosphate products under two iron sources

Table 2. Comparison of the quality indexes of the obtained iron phosphate products under two phosphorus sources

Example 4

The mass fraction of sodium sulfite in the waste fipronil salt is 21.3%, the mass fraction of sodium phosphate is 25.3%, the mass fraction of sodium bromide is 0.25%, the mass fraction of sodium sulfate is 0.64%, and the mass fraction of sodium trifluoromethanesulfinate The mass fraction is 0.2%, and the rest is moisture.

The mass fraction of ferrous sulfate heptahydrate in the by-product of titanium dioxide ferrous sulfate is 96.8%, and the metal ions and mass fractions contained are: magnesium ions 0.33%, manganese ions 0.16%, titanium ions 0.35%, aluminum ions 0.022%, zinc ions ionic 0.027%.

Add 74.9kg of waste salt of fipronil into the reactor, add deionized water or condensed water according to the mass ratio of waste salt to water 1:1.5, stir at room temperature until the waste salt is completely dissolved, add 0.8kg of nickel monoxide into the reactor With 1.3kg of cobalt tetroxide as a catalyst, according to the flow rate of 19.3L/(h·kg aqueous solution), the air was fed, and the reaction was carried out at 80°C for 4 hours. The oxidation rate of sodium sulfite reached 99.9%, and the reaction was stopped to obtain a sodium phosphate solution with a pH value of 11.9.

Get 35.5kg of titanium dioxide by-product ferrous sulfate, use deionized water or condensed water to prepare an aqueous solution with anhydrous ferrous sulfate concentration of 12%, according to the sodium sulfide dosage is 7% of the quality of ferrous sulfate, add 38.7% to the aqueous solution L sodium sulfide solution with a concentration of 34g/L, react at 43°C for 1.5h, and then stand for 3h, the magnesium ions, manganese ions, and zinc ions in the solution are converted into sulfide precipitates, and the precipitates are removed by filtration. The mass fraction of magnesium ions in the filtrate is 0.0014%, the mass fraction of manganese ions is 0.0008%, and the mass fraction of zinc is 0%. Then add concentrated sulfuric acid to adjust the pH value of the filtrate to 4, hydrolyze at a temperature of 90 ° C for 3.5 hours, after the titanium ions and aluminum ions in the hydrolyzed solution are converted into hydroxide precipitates, the precipitates are removed by filtration, and the titanium ions in the impurity filtrate are removed by water. The mass fraction is 0.0031%, and the mass fraction of aluminum ions is 0%. Add 6.04kg 98% vitriol oil in the solution processed through impurity removal, the mol ratio of sulfuric acid and ferrous sulfate is 0.495:1, then slowly add 9.1kg30% hydrogen peroxide (the consumption of hydrogen peroxide is 130% of theoretical consumption), The reaction temperature is 48° C., the hydrogen peroxide feeding time is 75 minutes, the oxidation rate of ferrous sulfate reaches 99.8%, and a ferric sulfate solution is obtained. 98% concentrated sulfuric acid was added to adjust the pH of the ferric sulfate solution to 1.

The sodium phosphate solution obtained by gas-liquid catalytic oxidation is used as the phosphorus source, and the iron sulfate solution obtained by removing impurities and oxidizing the by-product of titanium dioxide ferrous sulfate is used as the iron source. At a temperature of 45 °C, according to the molar ratio of ferric sulfate and sodium phosphate being 0.5, the sodium phosphate solution was added dropwise to the ferric sulfate solution. , obtain ferric phosphate suspension, filter to obtain filter cake and filtrate; in the presence of deionized water or condensed water, use a planetary ball mill to perform ball milling desalination on the filter cake for 4 times, and the amount of water used for each ball milling desalination is 10% of the quality of the filter cake. 5 times, after desalting by ball milling, ferric phosphate with particle diameter <3 μm is obtained, and drying obtains ferric phosphate dihydrate product, and the content of each element in the ferric phosphate product meets the quality index of ferric phosphate for batteries (see Table 3).

The content of sodium sulfate in the filtrate is 9.8%, and the atmospheric pressure evaporation treatment is carried out in a scraper evaporator, and the evaporation temperature is 125 ° C. kg.

Example 5

The mass fraction of sodium sulfite in the waste fipronil salt is 27.6%, the mass fraction of sodium phosphate is 28.2%, the mass fraction of sodium bromide is 0.18%, the mass fraction of sodium sulfate is 0.77%, and the mass fraction of sodium trifluoromethanesulfinate is 0.23%, and the rest is moisture.

The mass fraction of ferrous sulfate heptahydrate in the by-product ferrous sulfate of titanium dioxide is 95.5%, and the impurity metal ions and mass fractions contained are: magnesium ions 0.51%, manganese ions 0.12%, titanium ions 0.27%, aluminum ions 0.046%, Zinc ions 0.033%.

Add 139.2kg of fipronil waste salt to the reactor, add deionized water or condensed water according to the mass ratio of waste salt to water 1:1, stir at room temperature until the waste salt is completely dissolved, add 0.9kg of manganese phosphate and 0.6kg manganese dioxide was used as a catalyst, and air was introduced into the air at a flow rate of 24.6L/(h·kg aqueous solution), and the reaction was conducted at 80°C for 4 hours. The oxidation rate of sodium sulfite reached 99.9%, and the reaction was stopped to obtain a sodium phosphate solution with a pH value of 11.7. .

Get 62.3kg of titanium dioxide by-product ferrous sulfate, use deionized water or condensed water to prepare an aqueous solution with anhydrous ferrous sulfate concentration of 19%, according to the amount of sodium sulfide to be 2.5% of the quality of ferrous sulfate, add 10.7 L sodium sulfide solution with a concentration of 77g/L, react at 25°C for 2h, and then stand for 2.5h, the magnesium ions, manganese ions, and zinc ions in the solution are converted into sulfide precipitates, and the precipitates are removed by filtration, and the magnesium ions in the filtrate are removed. The mass fraction of ions is 0.011%, the mass fraction of manganese ions is 0.0015%, and the mass fraction of zinc is 0.0002%. Then add 98% concentrated sulfuric acid to adjust the pH of the filtrate to 2, hydrolyze at 76 ° C for 5 hours, the titanium ions and aluminum ions in the hydrolyzed solution are converted into hydroxide precipitates, the precipitates are removed by filtration, and the titanium ions in the impurity filtrate are removed by water. The mass fraction is 0.0031%, and the mass fraction of aluminum ions is 0%. Add 10.44kg 98% vitriol oil to the solution through impurity removal treatment, the mol ratio of sulfuric acid and ferrous sulfate is 0.497:1, then slowly add 13.9kg 30% hydrogen peroxide (hydrogen peroxide consumption is 115% of theoretical consumption) , the reaction temperature is 25° C., the feeding time is 90 min, the oxidation rate of ferrous sulfate reaches 99.9%, and a ferric sulfate solution is obtained. 98% concentrated sulfuric acid was added to adjust the pH of the ferric sulfate solution to 2.

The sodium phosphate solution obtained by gas-liquid catalytic oxidation is used as the phosphorus source, and the iron sulfate solution obtained by removing impurities and oxidizing the by-product of titanium dioxide ferrous sulfate is used as the iron source. At a temperature of 39 °C, according to the molar ratio of iron sulfate to sodium phosphate of 0.5, the sodium phosphate solution was added dropwise to the iron sulfate solution, the dropwise addition time was 2h, and the temperature was raised to 88 °C after the dropwise addition, and stirred. 2h, the iron phosphate suspension was obtained, and the iron phosphate suspension was filtered to obtain a filter cake and a filtrate; in the presence of deionized water or condensed water, the filter cake was subjected to 10 ball milling desalination with a planetary ball mill, and the The amount of water was 5 times the mass of the filter cake. After desalination by ball milling, iron phosphate with particle size <5 μm was obtained. The content of each element in the iron phosphate product met the quality index of iron phosphate for batteries (see Table 3).

The content of sodium sulfate in the filtrate is 14.3%, and the atmospheric pressure evaporation treatment is carried out in a scraper evaporator, and the evaporation temperature is 200 ° C. The water content in the sodium sulfate by-product obtained after evaporation is 0%, and the quality of the by-product sodium sulfate is 83.5kg.

Example 6

The mass fraction of sodium sulfite in the waste fipronil salt is 26.4%, the mass fraction of sodium phosphate is 27.7%, the mass fraction of sodium bromide is 0.17%, the mass fraction of sodium sulfate is 0.84%, and the mass fraction of sodium trifluoromethanesulfinate is 0.29%, and the rest is moisture.

The mass fraction of ferrous sulfate heptahydrate in the by-product ferrous sulfate of titanium dioxide is 98.2%, and the impurity metal ions and mass fractions contained are: magnesium ions 0.34%, manganese ions 0.16%, titanium ions 0.21%, aluminum ions 0.028%, Zinc ions 0.024%.

Add 56.6kg of waste fipronil salt into the reactor, add deionized water or condensed water at a ratio of 1:1.6 by mass ratio of waste salt to water, stir at room temperature until the waste salt is completely dissolved, add 2.6kg of sulfuric acid to the reactor Chromium was used as a catalyst, and air was introduced at a flow rate of 14.2 L/(h·kg aqueous solution), and the reaction was carried out at 40° C. for 5 hours. The oxidation rate of sodium sulfite reached 99.6%, and the reaction was stopped to obtain a sodium phosphate solution with a pH value of 11.8.

Get 28.6kg of titanium dioxide by-product ferrous sulfate, use deionized water or condensed water to prepare an aqueous solution with anhydrous ferrous sulfate concentration of 18%, according to the amount of sodium sulfide to be 4% of the quality of ferrous sulfate, add 9.5% to the aqueous solution. L sodium sulfide solution with a concentration of 65g/L was reacted at 36°C for 2 hours, and then left standing for 3 hours. The magnesium ions, manganese ions, and zinc ions in the solution were converted into sulfide precipitates. The precipitates were removed by filtration, and the magnesium ions in the filtrate were removed. The mass fraction of ions is 0.0088%, the mass fraction of manganese ions is 0.0015%, and the mass fraction of zinc is 0.0002%. Then add concentrated sulfuric acid to adjust the pH value of the filtrate to 3, hydrolyze at a temperature of 92 ° C for 3.5 hours, the titanium ions and aluminum ions in the hydrolysis solution are converted into hydroxide precipitates, the precipitates are removed by filtration, and the mass of titanium ions in the filtrate is removed by water. The fraction is 0.0016%, and the mass fraction of aluminum ions is 0%. Add 5.05kg 98% vitriol oil to the solution through impurity removal treatment, the mol ratio of sulfuric acid and ferrous sulfate is 0.505:1, then slowly add the 30% hydrogen peroxide of 7.2kg (hydrogen peroxide consumption is 125% of theoretical consumption) , the reaction temperature is 38° C., the feeding time is 75 min, the oxidation rate of ferrous sulfate reaches 99.8%, and a ferric sulfate solution is obtained. Add 98% concentrated sulfuric acid to adjust the exothermic pH value of ferric sulfate solution to 1.3.

The sodium phosphate solution obtained by gas-liquid catalytic oxidation is used as the phosphorus source, and the iron sulfate solution obtained by removing impurities and oxidizing the by-product of titanium dioxide ferrous sulfate is used as the iron source. At a temperature of 50 °C, according to the molar ratio of ferric sulfate and sodium phosphate being 0.5, the sodium phosphate solution was added dropwise to the ferric sulfate solution. The dropping time was 1.5 h. 1.5h, the iron phosphate suspension was obtained, and the iron phosphate suspension was filtered to obtain filter cake and filtrate; in the presence of deionized water or condensed water, the filter cake was subjected to 7 times of ball milling and desalination with a planetary ball mill, and each ball milling desalination was performed. The water consumption is 5 times of the filter cake quality, after ball milling desalination, obtains the iron phosphate of particle diameter＜3μm, and drying obtains iron phosphate dihydrate product, and each element content in the iron phosphate product meets the quality index of iron phosphate for battery ( See Table 3).

The content of sodium sulfate in the filtrate is 12.8%, and the atmospheric pressure evaporation treatment is carried out in a scraper evaporator, the evaporation temperature is 165 ° C, the water content in the sodium sulfate by-product obtained after evaporation is 0.25%, and the quality of the by-product sodium sulfate is 38.9kg.

Table 3. Product Quality Index of Ferric Phosphate

Claims (10)

1. A method for resource integrated utilization of fipronil waste salt and ferrous sulfate as a titanium dioxide byproduct is characterized in that the fipronil waste salt is prepared into an aqueous solution, and sodium sulfite in the waste salt is converted into sodium sulfate through gas-liquid catalytic oxidation to obtain a sodium phosphate solution; preparing a titanium dioxide byproduct ferrous sulfate into an aqueous solution, and performing chemical impurity removal, hydrolytic impurity removal and oxidation treatment to obtain a ferric sulfate solution; dropwise adding a sodium phosphate solution into a ferric sulfate solution, carrying out double decomposition reaction under an acidic condition to generate ferric phosphate precipitate, filtering to obtain a ferric phosphate filter cake, carrying out ball milling desalination in the presence of water to obtain ferric phosphate for the battery, and evaporating the filtrate to obtain sodium sulfate.

2. The resource integrated utilization method of fipronil waste salt and titanium dioxide byproduct ferrous sulfate according to claim 1, characterized by comprising the following steps:

preparing a waste fipronil salt into an aqueous solution, introducing air to perform gas-liquid catalytic oxidation in the presence of a catalyst, and converting sodium sulfite in the waste fipronil salt into sodium sulfate to obtain a sodium phosphate solution with the pH value of 11-12;

preparing a titanium dioxide byproduct ferrous sulfate into an aqueous solution with ferrous sulfate concentration of 10-20%, sequentially performing chemical impurity removal and hydrolysis impurity removal to convert impurity metal ions into precipitates and separate out, and filtering to remove the precipitates; adding concentrated sulfuric acid, taking hydrogen peroxide as an oxidant for oxidation treatment, oxidizing ferrous sulfate in the filtrate into ferric sulfate to obtain a ferric sulfate solution, and adjusting the pH value of the ferric sulfate solution to 1-2 by using the concentrated sulfuric acid;

step (3), dropwise adding the sodium phosphate solution obtained in the step (1) into the ferric sulfate solution obtained in the step (2), so that double decomposition reaction is carried out between the sodium phosphate and the ferric sulfate, and a ferric phosphate suspension is obtained;

filtering the iron phosphate suspension obtained in the step (4) and the step (3) to obtain an iron phosphate filter cake and a sodium sulfate filtrate; carrying out ball milling desalination on the iron phosphate filter cake in the presence of water, and drying to obtain a dihydrate ferric phosphate product for the battery; the sodium sulfate filtrate is evaporated to give a sodium sulfate by-product.

3. The resource integrated utilization method of fipronil waste salt and titanium dioxide byproduct ferrous sulfate according to claim 1, characterized in that the fipronil waste salt contains sodium sulfite, sodium phosphate, sodium bromide, sodium sulfate, sodium trifluoromethanesulfonate and water; wherein the mass fraction of sodium sulfite is 20-28%, the content of sodium phosphate is 25-30%, the content of sodium bromide is 0.1-0.3%, the content of sodium sulfate is 0.5-1%, the content of sodium trifluoromethanesulfonate is 0.1-0.5%, and the balance is water.

4. The resource integrated utilization method of fipronil waste salt and titanium dioxide by-product ferrous sulfate according to claim 1, characterized in that the mass fraction of ferrous sulfate heptahydrate in the by-product ferrous sulfate in titanium dioxide production is 90-99%, and the impurity metal ions and mass fractions are as follows: 0.3-0.6% of magnesium ions, 0.1-0.3% of manganese ions, 0.2-0.5% of titanium ions, 0.02-0.05% of aluminum ions and 0.02-0.05% of zinc ions.

5. The resource integrated utilization method of fipronil waste salt and titanium dioxide byproduct ferrous sulfate according to claim 1, characterized in that the gas-liquid catalytic oxidation is: preparing an aqueous solution from waste fipronil salt and deionized water or condensed water according to a mass ratio of 1: 1-1.5, introducing air according to a ratio of 10-25L/(h.kg of aqueous solution) in the presence of a catalyst, oxidizing sodium sulfite into sodium sulfate at a temperature of 30-95 ℃, and stopping reaction when the oxidation rate of the sodium sulfite reaches more than 99.5%; wherein, the dosage of the catalyst is 0.05-5% of the mass of the aqueous solution; the catalyst is one of nickel sulfate, chromium sulfate, cobalt sulfate, manganese sulfate, nickel phosphate, chromium phosphate, cobalt phosphate, manganese phosphate, nickel monoxide, manganese dioxide or cobaltosic oxide.

6. The resource integrated utilization method of fipronil waste salt and titanium dioxide byproduct ferrous sulfate according to claim 1, characterized in that the chemical impurity removal treatment comprises: adopting a sodium sulfide solution as an impurity removing agent, wherein the concentration of sodium sulfide is 30-80 g/L, and the using amount of sodium sulfide is 1-7% of the mass of ferrous sulfate; controlling the reaction temperature at 20-40 ℃, controlling the reaction time at 1-2 h, standing for 2-4 h after the reaction is finished, filtering to remove precipitates, and obtaining chemical impurity removal filtrate, wherein the contents of magnesium ions, manganese ions and zinc ions in the filtrate are all less than 0.01%.

7. The resource integrated utilization method of fipronil waste salt and titanium dioxide byproduct ferrous sulfate according to claim 1, characterized in that the hydrolysis impurity removal treatment comprises: adjusting the pH value of the solution to 2-4, hydrolyzing for 3-5 h at the temperature of 75-95 ℃, and filtering to obtain hydrolysis impurity-removing filtrate, wherein the content of titanium ions and aluminum ions in the hydrolysis impurity-removing filtrate is less than 0.01%.

8. The resource integrated utilization method of fipronil waste salt and titanium dioxide byproduct ferrous sulfate according to claim 1, characterized in that the oxidation treatment is: firstly, adjusting the pH value of the hydrolysis impurity-removal filtrate to 1-2 by using concentrated sulfuric acid, and then adjusting the pH value to H₂SO₄The molar ratio of the iron sulfate to the iron sulfate is 0.498-05021, adding concentrated sulfuric acid into the solution; controlling the dosage of the hydrogen peroxide to be 110-130% of the theoretical dosage, and adding hydrogen peroxide at 25-50 ℃ for 50-90 min.

9. The resource integrated utilization method of fipronil waste salt and titanium dioxide byproduct ferrous sulfate according to claim 1, characterized in that according to the molar ratio of ferric sulfate to sodium phosphate of 0.4-0.8: 1, preferably 0.495-0.505: 1, a sodium phosphate solution is dripped into the ferric sulfate solution, the dripping time is controlled to be 1-2 h, and the metathesis reaction temperature is 35-55 ℃; and after the dropwise addition is finished, heating to 70-95 ℃, continuously reacting for 1-2 hours to obtain an iron phosphate suspension, and filtering to obtain an iron phosphate filter cake and a sodium sulfate filtrate.

10. The resource integrated utilization method of fipronil waste salt and titanium dioxide byproduct ferrous sulfate according to claim 1, characterized in that the ball milling desalination is as follows: under the condition of water, performing ball milling on the iron phosphate filter cake for multiple times by adopting a planetary ball mill to obtain iron phosphate particles with the particle size of less than 6 mu m; the ball milling desalting times are 3-10 times, and the water consumption of each ball milling desalting time is 5 times of the mass of the iron phosphate filter cake.

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