Device and method for preparing high-purity ferric trichloride water purifying agent

Abstract

The invention belongs to the technical field of synthesis and purification of ferric trichloride, and particularly relates to a preparation method of a high-purity ferric trichloride water purifying agent, which comprises the following steps: S1, adding a titanium dioxide byproduct ferrous sulfate and desalted water into a reaction kettle to form a solution a; s2, stirring the solution a, dropwise adding hydrogen peroxide, and dropwise adding ammonia water after oxidation is completed to form a solution b; s3, discharging and filtering when the pH value of the solution b is smaller than 5, and obtaining a ferric hydroxide filter cake.. The high-purity ferric trichloride water purifying agent preparation device comprises a reaction kettle, an evaporator and a freezing crystallizer, the reaction kettle is used for preparing a ferric trichloride solution, the evaporator is used for evaporating and concentrating the ferric trichloride solution, and the freezing crystallizer is used for freezing the ferric trichloride solution. And adding the evaporated and concentrated ferric trichloride solution into a freezing crystallizer for recrystallization. And waste can be turned into wealth, so that the problem that the byproduct ferrous sulfate is discharged to rivers, lakes and seas to cause environmental pollution is solved, and raw materials are saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of ferric chloride synthesis and purification, and specifically relates to a device and method for preparing a high-purity ferric chloride water purifier. Background Art

[0002] Ferric chloride, also known as ferric chloride, is a covalent inorganic compound with the chemical formula FeCl3. It is a covalent compound. It is a black-brown crystal, and also in the form of flakes, with a melting point of 306°C and a boiling point of 316°C. It is easily soluble in water and has strong water absorption, and can absorb moisture in the air and deliquesce. When FeCl3 is precipitated from an aqueous solution with six crystal waters, it is FeCl3〃6H2O, and hexahydrated ferric chloride is an orange-yellow crystal. Ferric chloride is a very important iron salt. Ferric chloride is a flocculant widely used in water purification treatment. It separates and removes impurities in water by flocculating them, and is also used in the corrosion of circuit boards. The preparation of ferric chloride in the prior art is mostly prepared by the chlorination reaction of ferrous chloride and chlorine. Chlorine is a highly toxic and dangerous substance. If it leaks during the production process, it is harmful to the human body. Therefore, the sealing requirements of the production equipment are extremely high; secondly, the price of chlorine is relatively high, and the production cost is relatively large. Thirdly, the ferric chloride prepared by the prior art is mostly of relatively low purity and contains unacceptable impurities, and therefore can only be used for sewage purification, but cannot be used for the purification of drinking water such as tap water.

[0003] The invention patent with application number 200910184059.X discloses a method for preparing ferric chloride, which uses natural iron ore with a mesh size of 40 or more as the iron-containing raw material, and hydrochloric acid with a molar ratio of 10 wt% or more, and the hydrochloric acid is equivalent or slightly excessive according to the molar ratio of ferric chloride molecules, so that the reaction is carried out in the liquid phase. Compared with the prior art, the method has the following advantages: safe reaction, preparation and production, undemanding process conditions, low requirements on production equipment, easy availability of raw materials, low preparation cost, and the iron ore basically does not contain harmful impurities, impurities in the iron ore are easily separated by precipitation, and purification is simple. The obtained product fully meets the standard of drinking water treatment by water treatment agent ferric chloride, has a low heavy metal content, can be directly used for drinking water purification, and the obtained product can be used for drinking water purification.

[0004] The above technology uses iron ore as a reaction raw material for preparing ferric chloride. Although iron ore can be obtained through mining, its mining and smelting processes are relatively complicated. In addition, in the actual manufacturing process, many reactions generate by-products containing iron ions. If these by-products can be used as reaction raw materials, the loss of iron ore will be reduced.

[0005] The domestic production capacity of ferrous sulfate, a byproduct of titanium dioxide production, is huge, and the output ratio of titanium dioxide to ferrous sulfate is usually about 1:3. Therefore, sulfuric acid-based titanium dioxide production enterprises produce a large amount of byproduct ferrous sulfate heptahydrate, but due to the poor crystal form of ferrous sulfate, the purity of ferrous sulfate is generally less than 90%, and it contains many impurities, mainly Ti, Mn, Mg, Al, Si, etc., and cannot be sold directly as a commodity. Most of the byproduct ferrous sulfate is treated as waste and piled up for a long time or discharged into rivers, lakes and seas, which not only wastes resources but also causes great harm to the environment.

[0006] Ferrous sulfate produced as a byproduct of titanium dioxide contains abundant iron resources and has the advantages of being easily soluble and easy to handle. It can be used as a basic raw material for the production of high value-added products such as water treatment agents, iron oxide industrial pigments, iron oxide for soft ferrites, iron phosphate for batteries, and ferrous sulfate for feed after systematic purification. In the past 10 years, the resource utilization of ferrous sulfate produced as a byproduct of titanium dioxide has become a key research object. Now a technology is needed to produce ferric chloride water purifier based on ferrous sulfate produced as a byproduct of titanium dioxide as an iron source, so as to solve the problem of byproduct ferrous sulfate being discharged into rivers, lakes and seas, causing environmental pollution, and to achieve waste-to-treasure and save raw materials. Summary of the invention

[0007] The purpose of this scheme is to provide a high-purity ferric chloride water purifier preparation device and method to solve the problem of by-product ferrous sulfate being discharged into rivers, lakes and seas, causing environmental pollution.

[0008] In order to achieve the above object, the present invention provides a method for preparing a high-purity ferric chloride water purifier, comprising the following steps:

[0009] S1: Put the titanium dioxide by-product ferrous sulfate and desalted water into a reactor to form solution a;

[0010] S2: Stir solution a, add hydrogen peroxide, and then add ammonia water after oxidation to form solution b;

[0011] S3: When the pH value of solution b is less than 5, the material is filtered to obtain an iron hydroxide filter cake;

[0012] S4: adding the iron hydroxide filter cake in step S3 to a reaction kettle, and then adding industrial by-product hydrochloric acid, stirring, to obtain a ferric chloride solution;

[0013] S5: taking the ferric chloride solution and adding it into a forced evaporator device, and performing forced evaporation and concentration under negative pressure, and after the ferric chloride solution reaches saturation, entering into a freezing crystallizer for recrystallization;

[0014] S6: The recrystallized crystals are separated by filter pressing in a centrifugal separator to obtain primary recrystallized ferric chloride and primary recrystallization mother liquor, respectively.

[0015] Furthermore, in step S1, the weight ratio of desalted water to ferrous sulfate is in the range of 1:1 to 3:1, and the content of ferrous sulfate produced as a byproduct of titanium dioxide is in the range of 80 to 92%; in step S2, the molar ratio of hydrogen peroxide to iron ions is in the range of 0.5:1 to 0.65:1, and the molar ratio of ammonia water to iron ions is in the range of 3.0:1 to 3.3:1. The stirring speed of step S2 is in the range of 50 to 500 rpm, the temperature is in the range of 20 to 60°C, the reaction time is in the range of 1 to 5 hours, and the pH value adjusted at the endpoint is in the range of 2.0 to 5.0.

[0016] Further, in step S4, the molar ratio of hydrochloric acid to ferric hydroxide is in the range of 3:1 to 3.3:1, the concentration of hydrochloric acid is in the range of 15% to 32%, the speed is in the range of 50 to 500 rpm, the temperature is in the range of 20 to 60° C., and the reaction time is in the range of 1 to 5 hours;

[0017] Further, in step S5, the molar ratio of hydrochloric acid to ferric hydroxide is in the range of 3:1 to 3.3:1, the concentration of hydrochloric acid is in the range of 15% to 32%, the speed is in the range of 50 to 500 rpm, the temperature is in the range of 20 to 60° C., and the reaction time is in the range of 1 to 5 hours.

[0018] Furthermore, in steps S5 and S6, the distillation temperature ranges from 90 to 100° C., the rotation speed ranges from 50 to 500 rpm, the freezing temperature ranges from 0 to 15° C., and the freezing time ranges from 0.5 to 5 h.

[0019] Beneficial effects of this solution: In the present invention, extremely cheap titanium dioxide by-product ferrous sulfate is used as the iron source, and industrial by-product hydrochloric acid is effectively used as the chlorine source, making full use of two cheap by-products of the industrial system as the main reaction raw materials, greatly reducing the cost. At the same time, the use of vacuum distillation technology fully reduces energy consumption, and the use of secondary recrystallization technology greatly improves product purity. The whole process has low raw material cost, low energy consumption, and high product added value. It provides an important solution for the digestion and direction of titanium dioxide by-product ferrous sulfate and a large amount of by-product hydrochloric acid in my country's chemical production field, turning waste into treasure, which is of great significance.

[0020] Using ferrous sulfate, a byproduct of titanium dioxide enterprises, as an iron source and industrial byproduct hydrochloric acid as a chlorine source, we have achieved resource utilization of industrial byproducts, reduced waste emissions, and reduced environmental pollution. Using cheap industrial byproducts as raw materials has greatly reduced production costs. At the same time, because the raw materials are easily available, the sustainability of production is guaranteed. Through a series of process steps such as oxidation, pH adjustment, chlorination, forced evaporation concentration and freezing recrystallization, a high-purity ferric chloride water purifier is prepared to meet high standards of water quality treatment. The use of vacuum distillation technology reduces energy consumption in the production process and improves energy efficiency. The secondary recrystallization technology is used to further improve the product purity and ensure the high quality of the final product.

[0021] A high-purity ferric chloride water purifier preparation device comprises a reactor, an evaporator and a freezing crystallizer. The reactor is used to prepare a ferric chloride solution. The evaporator is used to evaporate and concentrate the ferric chloride solution. The evaporated and concentrated ferric chloride solution is added to the freezing crystallizer for recrystallization.

[0022] Furthermore, the freezing crystallizer includes a crystallization box, a discharge port is provided at the bottom of the crystallization box, a solenoid valve for controlling the opening and closing of the discharge port is installed at the discharge port, the bottom of the crystallization box is in a constricted shape, a first airbag is fixed on the side wall of the crystallization box at the constricted portion, the upper end of the first airbag is a platform, a plurality of evenly spaced second airbags are provided on the platform, the bottom of the second airbag is connected to the first airbag, the elastic modulus of the first airbag is lower than the elastic modulus of the second airbag, the first airbag is connected to an air pump, after the second airbag is inflated, it extends toward the top of the crystallization box, and after the first airbag is inflated, it extends vertically toward the axial direction of the crystallization box.

[0023] The basic principle and beneficial effects of this scheme: the saturated ferric chloride solution after evaporation and concentration is added to the crystallization box, and then the refrigerator is started to transfer the frozen water to the crystallization box, and the solution in the crystallization box is cooled to reach the temperature of freezing crystallization to complete the crystallization work; after adding the saturated ferric chloride solution to the crystallization box, the air pump is started to inflate the first airbag and the second airbag, the first airbag forms a platform, the second airbag extends upward in a columnar shape, and the second airbag stands in the solution. As the temperature decreases, crystallization begins to appear; the crystallization process includes nucleation and growth. Nucleation is the first stage of crystal formation, and a starting point or "fulcrum" is required to start the growth of crystals. In the solution, this "fulcrum" may be the wall of the container, suspended impurities or other solid surfaces. This scheme uses several second airbags as fulcrums for crystallization to provide a plane for crystallization to start growth. Once crystals begin to form, they will continue to grow until they reach equilibrium or the solute in the solution is exhausted.

[0024] Since the crystals grow by adhering to the second airbag, the probability of growing against the inner wall of the crystallization box is reduced, and the probability of cleaning the inner wall of the crystallization box in the later stage is reduced; at the same time, since multiple second airbags produce crystals at the same time, the crystallization rate is accelerated. After crystallization, the weight of the second airbag increases, and the center of gravity of the second airbag is unstable, and it swings, that is, the crystals on different second airbags are reduced to grow into a whole; the crystal block is prevented from being too large and blocking the discharge port. The air pressure in the first airbag can be adjusted to control the load-bearing capacity of the second airbag. The second airbag that reaches the upper limit of the load-bearing capacity will tilt toward the platform of the first airbag, so that other second airbags can crystallize faster; the weight control of each crystal block is completed. After the crystallization is completed, the first airbag and the second airbag are deflated, and the second airbag and the second airbag are reduced, that is, the airbag is separated from the inside of the crystal, so that the crystal becomes a free individual. The first airbag only releases part of the gas, and the remaining gas makes the first airbag form a smooth inclined surface, which is convenient for the crystal to slide out. When the discharge port is opened, the crystal is prevented from remaining at the bottom of the crystallization box.

[0025] Furthermore, a counterweight is arranged inside the top of the second airbag.

[0026] Beneficial effect: The setting of the counterweight block can make the top of the second airbag appear as a pit. During the crystallization process, the pit is filled with saturated ferric chloride solution, and the surface contacted by the ferric chloride solution in the pit is the inner wall of the pit, that is, there are more contact surfaces, which makes it easier to form crystal nuclei, and it is convenient for the crystal to grow from here. The counterweight block also plays a resetting role. During the process of deflating the airbag, since the elastic modulus of the first airbag is lower than that of the second airbag, that is, under the same air pressure, the first airbag will expand larger. In addition, the use of the counterweight block can make the expansion degree of the second airbag very small, that is, only a small convex point is formed on the first airbag, which can provide a buffering effect in the subsequent crystal sliding process to prevent the crystal from sliding too fast and causing violent collisions.

[0027] Furthermore, a filter tank is arranged at the lower end of the solenoid valve, a collecting tank is fixed below the filter tank, and a filter screen is fixed between the filter tank and the collecting tank.

[0028] Beneficial effect: The filter can intercept large crystals coming out of the discharge port, and some smaller crystals enter the centrifugal separator together with the filtrate for separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a flow chart of a method for preparing a high-purity ferric chloride water purifier;

[0030] Figure 2 It is a step diagram of recrystallization of high-purity ferric chloride;

[0031] Figure 3It is a schematic diagram of the device used for recrystallization of high-purity ferric chloride;

[0032] Figure 4 It is a structural schematic diagram of a freezing crystallizer (freezer omitted);

[0033] Figure 5 for Figure 4 The enlarged schematic diagram of point A in the middle;

[0034] Figure 6 for Figure 5 Another state diagram of .

[0035] The following is further described in detail through specific implementation methods:

[0036] The symbols in the drawings of the specification include: a crystallization box 1, a filter tank 2, a filter screen 3, a collection tank 4, a solenoid valve 5, a first air bag 6, a second air bag 7, and a counterweight 8. DETAILED DESCRIPTION

[0037] A method for preparing a high-purity ferric chloride water purifier, as shown in the following Figure 1 As shown, the following steps are included:

[0038] S1: adding titanium dioxide byproduct ferrous sulfate and desalted water into a reactor to form solution a; the weight ratio of desalted water to ferrous sulfate is in the range of 1:1 to 3:1, and the content of titanium dioxide byproduct ferrous sulfate is in the range of 80 to 92%; in step S2, the molar ratio of hydrogen peroxide to iron ions is in the range of 0.5:1 to 0.65:1, and the molar ratio of ammonia water to iron ions is in the range of 3.0:1 to 3.3:1. The stirring speed of step S2 is in the range of 50 to 500 rpm, the temperature is in the range of 20 to 60°C, the reaction time is in the range of 1 to 5 hours, and the pH value adjusted at the end point is in the range of 2.0 to 5.0.

[0039] S2: Stir solution a, add hydrogen peroxide, and then add ammonia water after oxidation to form solution b;

[0040] S3: When the pH value of solution b is less than 5, the material is filtered to obtain an iron hydroxide filter cake;

[0041] S4: adding the iron hydroxide filter cake in step S3 to a reaction kettle, and then adding industrial by-product hydrochloric acid, stirring, to obtain a ferric chloride solution; the molar ratio of hydrochloric acid to ferric hydroxide is in the range of 3:1 to 3.3:1, the concentration of hydrochloric acid is in the range of 15% to 32%, the speed is in the range of 50 to 500 rpm, the temperature is in the range of 20 to 60° C., and the reaction time is in the range of 1 to 5 hours;

[0042] S5: Take the ferric chloride solution and add it to the forced evaporator device, perform forced evaporation and concentration under negative pressure, and enter the freezing crystallizer for recrystallization after the ferric chloride solution reaches saturation; in step S5, the molar ratio of hydrochloric acid to ferric hydroxide is in the range of 3:1 to 3.3:1, the concentration of hydrochloric acid is in the range of 15% to 32%, the speed is in the range of 50 to 500 rpm, the temperature is in the range of 20 to 60°C, and the reaction time is in the range of 1 to 5h. The temperature range of the distillation is 90 to 100°C, the speed range is 50 to 500 rpm

[0043] S6: The recrystallized crystals are filtered and separated in a centrifugal separator to obtain primary recrystallized ferric chloride and primary recrystallized mother liquor, respectively. The freezing temperature range is 0 to 15°C, and the freezing time range is 0.5 to 5 hours.

[0044] A high-purity ferric chloride water purifier preparation device suitable for the above method: as shown in the attached Figure 2-3 As shown, it includes a reactor, an evaporator, and a freezing crystallizer. The reactor is used to prepare a ferric chloride solution. The evaporator is used to evaporate and concentrate the ferric chloride solution. The evaporated and concentrated ferric chloride solution is added to the freezing crystallizer for recrystallization. Figure 4-6 As shown, the freezing crystallizer includes a crystallization box 1, a discharge port is provided at the bottom of the crystallization box 1, a solenoid valve 5 for controlling the opening and closing of the discharge port is installed at the discharge port, the bottom of the crystallization box 1 is in a constricted shape, a first airbag 6 is fixed on the side wall of the crystallization box 1 at the constricted port, the upper end of the first airbag 6 is a platform, a number of evenly spaced second airbags 7 are arranged on the platform, the bottom of the second airbag 7 is connected to the first airbag 6, the elastic modulus of the first airbag 6 is lower than the elastic modulus of the second airbag 7, the first airbag 6 is connected to the air pump, the second airbag 7 expands and extends to the top of the crystallization box 1, and the first airbag 6 expands and extends vertically toward the axis direction of the crystallization box 1. A counterweight 8 is arranged inside the top of the second airbag 7. A filter tank 2 is arranged at the lower end of the solenoid valve 5, a collection tank 4 is fixed below the filter tank 2, and a filter screen 3 is fixed between the filter tank 2 and the collection tank 4.

[0045] The saturated ferric chloride solution after evaporation and concentration is added to the crystallization box 1, and then the refrigerator is started to transfer the frozen water to the crystallization box 1, and the solution in the crystallization box 1 is cooled to reach the temperature of freezing crystallization to complete the crystallization work; after adding the saturated ferric chloride solution to the crystallization box 1, the air pump is started to inflate the first airbag 6 and the second airbag 7, the first airbag 6 forms a platform, the second airbag 7 extends upward in a columnar shape, and the second airbag 7 stands in the solution. As the temperature decreases, crystallization begins to appear; the crystallization process includes nucleation and growth. Nucleation is the first stage of crystal formation, and a starting point or "fulcrum" is required to start the growth of crystals. In the solution, this "fulcrum" may be the wall of the container, suspended impurities or other solid surfaces. This scheme uses a number of second airbags 7 as the fulcrum of crystallization to provide a plane for crystallization to start growth. Once crystals begin to form, they will continue to grow until they reach equilibrium or the solute in the solution is exhausted.

[0046] Since the crystals grow by adhering to the second airbags 7, the probability of growing against the inner wall of the crystallization box 1 is reduced, that is, the probability of cleaning the inner wall of the crystallization box 1 in the later stage is reduced; at the same time, since multiple second airbags 7 produce crystals at the same time, the crystallization rate is accelerated. After crystallization, the weight of the second airbags 7 increases, and the center of gravity of the second airbags 7 becomes unstable and swings, that is, the crystals on different second airbags 7 are reduced from growing into a whole; to prevent the crystal block from being too large and blocking the discharge port, the air pressure in the first airbag 6 can be adjusted to control the second airbag 7. The second airbag 7 that reaches the upper limit of the load-bearing capacity will tilt toward the platform of the first airbag 6, so that the other second airbags 7 can crystallize faster; the weight control of each crystal block is completed. After the crystallization is completed, the first airbag 6 and the second airbag 7 are deflated, and the second airbag 7 and the second airbag 7 become smaller, that is, the airbags are separated from the inside of the crystal, so that the crystal becomes a free individual. The first airbag 6 only releases part of the gas, and the remaining gas makes the first airbag 6 form a smooth inclined surface, which is convenient for the crystal to slide out, and when the discharge port is opened, it prevents the crystal from remaining at the bottom of the crystallization box 1.

[0047] The setting of the counterweight 8 can make the top of the second airbag 7 appear as a pit. During the crystallization process, the pit is filled with saturated ferric chloride solution, and the surface contacted by the ferric chloride solution in the pit is the inner wall of the pit, that is, there are more contact surfaces, it is easier to form a crystal nucleus, and it is convenient for the crystal to grow from here, and the counterweight 8 also plays a resetting role. In the process of deflating the airbag, since the elastic modulus of the first airbag 6 is lower than the elastic modulus of the second airbag 7, that is, under the same air pressure, the first airbag 6 will expand larger, and the use of the counterweight 8 can make the expansion degree of the second airbag 7 very small, that is, only a small convex point is formed on the first airbag 6, which can provide a buffering effect in the subsequent crystal sliding process to prevent the crystal from sliding too fast, causing violent collisions, and breaking into too small fragments, and entering the centrifuge with the filtrate.

[0048] By the above method, the following embodiments are obtained:

[0049] Embodiment 1:

[0050] A high-purity ferric chloride water purifier preparation device and method, 204.18g titanium dioxide byproduct ferrous sulfate, 400.24g desalted water are added to a beaker, heated at 60°C to dissolve, 2g ammonium dihydrogen phosphate (mass fraction 99%) is added, stirred for reaction for 1h, after the reaction is completed, filtered to obtain a ferrous sulfate solution (pH=1.3, iron liquid 1.15mol / L). Take 150mL ferrous sulfate liquid and place it in a three-necked flask for hydrogen peroxide (30%) oxidation and adjust the solution pH to 3.2 by adding industrial ammonia (15%) and then filter, place the iron hydroxide colloid in a 105°C drying oven for 5h, collect 23.35g iron hydroxide, dissolve 119.65g industrial byproduct hydrochloric acid (20%) at room temperature for 2h to obtain ferric chloride liquid, distill the ferric chloride liquid at 60°C until the ferric chloride liquid is saturated, control the freezing crystallization at 15°C for 30min, after the recrystallization is completed, separate by filtration to obtain high-purity ferric chloride.

[0051] Table 1 shows the impurity content of each step in the preparation of high-purity ferric chloride according to GB / T 4482-2018 water treatment agent in Example 1.

[0052]

[0053] Embodiment 2:

[0054] A high-purity ferric chloride water purifier preparation device and method, 201.18g of titanium dioxide byproduct ferrous sulfate and 400.14g of desalted water are added to a beaker, heated at 60°C to dissolve, 2g of ammonium dihydrogen phosphate (mass fraction 99%) is added, stirred for reaction for 1h, and after the reaction is completed, ferrous sulfate solution (pH=1.3, iron liquid 1.15mol / L) is obtained by filtration. 150mL of ferrous sulfate solution is placed in a three-necked flask for oxidation with hydrogen peroxide (30%) and adjusted to solution pH=4.2 by adding industrial ammonia (15%), and then filtered, and ferric hydroxide colloid is placed in a 105°C drying oven for 5h to obtain 24.12g of ferric hydroxide, and 123.57g of industrial byproduct hydrochloric acid (20%) is dissolved at room temperature for 2h to obtain ferric chloride liquid, and the ferric chloride liquid is distilled at 60°C until the ferric chloride liquid is saturated, and frozen crystallization is controlled at 15°C for 30min. After recrystallization, it is separated by filtration to obtain high-purity ferric chloride.

[0055] Table 2 shows the impurity content in each step of preparing high-purity ferric chloride according to GB / T 4482-2018 water treatment agent in Example 2.

[0056]

[0057] Embodiment 3:

[0058] A high-purity ferric chloride water purifier preparation device and method, 204.18g of titanium dioxide byproduct ferrous sulfate and 400.24g of desalted water are added to a beaker, heated at 60°C to dissolve, 2g of ammonium dihydrogen phosphate (mass fraction 99%) is added, stirred for reaction for 1h, and after the reaction is completed, ferrous sulfate solution (pH=1.3, iron liquid 1.15mol / L) is obtained by filtration. 150mL of ferrous sulfate solution is placed in a three-necked flask for oxidation with hydrogen peroxide (30%) and adjusted to solution pH=5.2 by adding industrial ammonia (15%), and then filtered, and ferric hydroxide colloid is placed in a 105°C drying oven for 5h to obtain 25.04g of ferric hydroxide, and 128.28g of industrial byproduct hydrochloric acid (20%) is dissolved at room temperature for 2h to obtain ferric chloride liquid, and the ferric chloride liquid is distilled at 60°C until the ferric chloride liquid is saturated, and frozen crystallization is controlled at 15°C for 30min. After recrystallization, it is separated by filtration to obtain high-purity ferric chloride.

[0059] Table 3 shows the impurity content in each step of preparing high-purity ferric chloride according to GB / T 4482-2018 water treatment agent in Example 3.

[0060]

[0061]

[0062] Embodiment 4:

[0063] A high-purity ferric chloride water purifier preparation device and method, 204.18g titanium dioxide byproduct ferrous sulfate, 400.24g desalted water are added to a beaker, heated at 60°C to dissolve, 2g ammonium dihydrogen phosphate (mass fraction 99%) is added, stirred for reaction for 1h, after the reaction is completed, ferrous sulfate solution (pH=1.3, iron liquid 1.15mol / L) is obtained by filtration. 150mL ferrous sulfate solution is placed in a three-necked flask for oxidation with hydrogen peroxide (30%) and adjusted to solution pH=3.2 by adding industrial ammonia (15%), and then filtered, and ferric hydroxide colloid is placed in a 105°C drying oven for 5h to obtain 24.42g ferric hydroxide, and 125.10g industrial byproduct hydrochloric acid (20%) is dissolved at room temperature for 2h to obtain ferric chloride liquid, and the ferric chloride liquid is distilled at 60°C until the ferric chloride liquid is saturated, and frozen crystallization is controlled at 5°C for 30min. After recrystallization is completed, it is separated by filtration to obtain high-purity ferric chloride.

[0064] Table 4 shows the impurity content in each step of preparing high-purity ferric chloride according to GB / T 4482-2018 water treatment agent in Example 4.

[0065]

[0066]

[0067] Embodiment 5:

[0068] A high-purity ferric chloride water purifier preparation device and method, 204.18g titanium dioxide byproduct ferrous sulfate, 400.24g desalted water are added to a beaker, heated at 60°C to dissolve, 2g ammonium dihydrogen phosphate (mass fraction 99%) is added, stirred for reaction for 1h, after the reaction is completed, ferrous sulfate solution (pH=1.3, iron liquid 1.15mol / L) is obtained by filtration. 150mL ferrous sulfate solution is placed in a three-necked flask for oxidation with hydrogen peroxide (30%) and adjusted to solution pH=3.2 by adding industrial ammonia (15%), and then filtered, and ferric hydroxide colloid is placed in a 105°C drying oven for 5h to obtain 23.89g ferric hydroxide, and 122.39g industrial byproduct hydrochloric acid (20%) is dissolved at room temperature for 2h to obtain ferric chloride liquid, and the ferric chloride liquid is distilled at 60°C until the ferric chloride liquid is saturated, and frozen crystallization is controlled at 10°C for 30min. After recrystallization is completed, it is separated by filtration to obtain high-purity ferric chloride.

[0069] Table 5 shows the impurity content in each step of preparing high-purity ferric chloride according to GB / T 4482-2018 water treatment agent in Example 5.

[0070]

[0071] Embodiment 6:

[0072] A high-purity ferric chloride water purifier preparation device and method, 204.18g titanium dioxide byproduct ferrous sulfate, 400.24g desalted water are added to a beaker, heated at 60°C to dissolve, 2g ammonium dihydrogen phosphate (mass fraction 99%) is added, stirred for reaction for 1h, after the reaction is completed, ferrous sulfate solution (pH=1.3, iron liquid 1.15mol / L) is obtained by filtration. 150mL ferrous sulfate solution is placed in a three-necked flask for oxidation with hydrogen peroxide (30%) and adjusted to solution pH=4.2 by adding industrial ammonia (15%), and then filtered, and ferric hydroxide colloid is placed in a 105°C drying oven for 5h to obtain 25.14g ferric hydroxide, and 128.79g industrial byproduct hydrochloric acid (20%) is dissolved at room temperature for 2h to obtain ferric chloride liquid, and the ferric chloride liquid is distilled at 60°C until the ferric chloride liquid is saturated, and frozen crystallization is controlled at 5°C for 30min. After recrystallization is completed, it is separated by filtration to obtain high-purity ferric chloride.

[0073] Table 6 shows the impurity content in each step of preparing high-purity ferric chloride according to GB / T 4482-2018 water treatment agent in Example 6.

[0074]

[0075] Embodiment 7:

[0076] A high-purity ferric chloride water purifier preparation device and method, 204.18g of titanium dioxide byproduct ferrous sulfate and 400.24g of desalted water are added to a beaker, heated at 60°C to dissolve, 2g of ammonium dihydrogen phosphate (mass fraction 99%) is added, stirred for reaction for 1h, and after the reaction is completed, ferrous sulfate solution (pH=1.3, iron liquid 1.15mol / L) is obtained by filtration. 150mL of ferrous sulfate liquid is placed in a three-necked flask for oxidation with hydrogen peroxide (30%) and adjusted to solution pH=4.2 by adding industrial ammonia (15%), and then filtered, and ferric hydroxide colloid is placed in a 105°C drying oven for 5h to obtain 24.78g of ferric hydroxide, and 126.95g of industrial byproduct hydrochloric acid (20%) is dissolved at room temperature for 2h to obtain ferric chloride liquid, and the ferric chloride liquid is distilled at 60°C until the ferric chloride liquid is saturated, and frozen crystallization is controlled at 10°C for 30min. After recrystallization, it is separated by filtration to obtain high-purity ferric chloride.

[0077] Table 7 shows the impurity content in each step of preparing high-purity ferric chloride according to GB / T 4482-2018 water treatment agent in Example 7.

[0078]

[0079]

[0080] Embodiment 8:

[0081] A high-purity ferric chloride water purifier preparation device and method, 204.18g titanium dioxide byproduct ferrous sulfate, 400.24g desalted water are added to a beaker, heated at 60°C to dissolve, 2g ammonium dihydrogen phosphate (mass fraction 99%) is added, stirred for reaction for 1h, after the reaction is completed, ferrous sulfate solution (pH=1.3, iron liquid 1.15mol / L) is obtained by filtration. 150mL ferrous sulfate solution is placed in a three-necked flask for oxidation with hydrogen peroxide (30%) and adjusted to solution pH=5.2 by adding industrial ammonia (15%), and then filtered, and ferric hydroxide colloid is placed in a 105°C drying oven for 5h to obtain 25.98g ferric hydroxide, and 133.10g industrial byproduct hydrochloric acid (20%) is dissolved at room temperature for 2h to obtain ferric chloride liquid, and the ferric chloride liquid is distilled at 60°C until the ferric chloride liquid is saturated, and frozen crystallization is controlled at 5°C for 30 min. After recrystallization, it is separated by filtration to obtain high-purity ferric chloride.

[0082] Table 8 shows the impurity content in each step of preparing high-purity ferric chloride according to GB / T 4482-2018 water treatment agent in Example 8.

[0083]

[0084] Embodiment 9:

[0085] A high-purity ferric chloride water purifier preparation device and method, 204.18g of titanium dioxide byproduct ferrous sulfate and 400.24g of desalted water are added to a beaker, heated at 60°C to dissolve, 2g of ammonium dihydrogen phosphate (mass fraction 99%) is added, stirred for reaction for 1h, and after the reaction is completed, ferrous sulfate solution (pH=1.3, iron liquid 1.15mol / L) is obtained by filtration. 150 mL of ferrous sulfate solution is placed in a three-necked flask for oxidation with hydrogen peroxide (30%) and adjusted to a solution pH of 5.2 by adding industrial ammonia (15%), and then filtered, and the iron hydroxide colloid is placed in a 105°C drying oven for 5h to obtain 25.68g of iron hydroxide, which is dissolved at room temperature for 2h by 131.56g of industrial byproduct hydrochloric acid (20%) to obtain ferric chloride liquid, and the ferric chloride liquid is distilled at 60°C until the ferric chloride liquid is saturated, and frozen crystallized at 10°C for 30 min. After the recrystallization is completed, it is separated by filtration to obtain high-purity ferric chloride.

[0086] Table 9 shows the impurity content in each step of preparing high-purity ferric chloride according to GB / T 4482-2018 water treatment agent in Example 9.

[0087]

[0088] Table 10 compares the impurity content of high-purity ferric chloride prepared in 9 embodiments with the water treatment agent GB / T 4482-2018.

[0089]

[0090] According to Table 10, it can be known that: relative to the industry standard of high-purity ferric chloride water treatment agent GB / T 4482-2018, the high-purity ferric chloride product impurity content prepared in Examples 1-9 of the present application is within the scope of industry standards, and the arsenic, lead, mercury, and cadmium element contents in the raw material are removed during the preparation of the product. It can be known from the product impurity content in Examples 1-9 that the core factor affecting the impurity content of its product during the preparation of the high-purity ferric chloride product is the regulation of the pH of the ferric hydroxide colloid generation and the recrystallization temperature of the ferric chloride liquid, and the generated product impurity content increases with the increase of the synthesis pH of the ferric hydroxide colloid, and its core reason is that the increase of the synthesis pH of the ferric hydroxide will cause other elements to precipitate in this precipitation interval range, and the heavy metal elements in the free state will be adsorbed on the surface of the ferric hydroxide colloid. Meanwhile, the generated product impurity content will also increase as the recrystallization temperature decreases, and the reason is that the lower the recrystallization temperature, when the solution reaches saturation, more elements will be precipitated at low temperatures, and the heavy metal elements in the free state will be adsorbed on the surface of the ferric chloride crystal.

[0091] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a high-purity ferric chloride water purifier, characterized in that: The following steps are involved: S1: Put the titanium dioxide byproduct ferrous sulfate and desalted water into a reactor to form solution a; S2: Stir solution a, add hydrogen peroxide, and then add ammonia water after oxidation to form solution b; S3: When the pH value of solution b is less than 5, the material is filtered to obtain an iron hydroxide filter cake; S4: adding the iron hydroxide filter cake in step S3 to a reaction kettle, and then adding industrial by-product hydrochloric acid, stirring, to obtain a ferric chloride solution; S5: taking the ferric chloride solution and adding it into a forced evaporator device, and performing forced evaporation and concentration under negative pressure, and after the ferric chloride solution reaches saturation, entering into a freezing crystallizer for recrystallization; S6: The recrystallized crystals are separated by filter pressing in a centrifugal separator to obtain primary recrystallized ferric chloride and primary recrystallization mother liquor, respectively.

2. A method for preparing a high-purity ferric chloride water purifier according to claim 1, characterized in that: In step S1, the weight ratio of desalted water to ferrous sulfate is in the range of 1:1 to 3:1, and the content of ferrous sulfate as a byproduct of titanium dioxide is in the range of 80 to 92%; in step S2, the molar ratio of hydrogen peroxide to iron ions is in the range of 0.5:1 to 0.65:1, and the molar ratio of ammonia water to iron ions is in the range of 3.0:1 to 3.3:

1. The stirring speed of step S2 is in the range of 50 to 500 rpm, the temperature is in the range of 20 to 60°C, the reaction time is in the range of 1 to 5 hours, and the pH value adjusted at the endpoint is in the range of 2.0 to 5.

0.

3. A method for preparing a high-purity ferric chloride water purifier according to claim 1, characterized in that: In step S4, the molar ratio of hydrochloric acid to ferric hydroxide is in the range of 3:1 to 3.3:1, the concentration of hydrochloric acid is in the range of 15% to 32%, the speed is in the range of 50 to 500 rpm, the temperature is in the range of 20 to 60° C., and the reaction time is in the range of 1 to 5 hours; A method for preparing a high-purity ferric chloride water purifier according to claim 3, characterized in that: in step S5, the molar ratio of hydrochloric acid to ferric hydroxide is in the range of 3:1 to 3.3:1, the concentration of hydrochloric acid is in the range of 15% to 32%, the speed range is in the range of 50 to 500 rpm, the temperature range is in the range of 20 to 60°C, and the reaction time range is in the range of 1 to 5h.

4. A method for preparing a high-purity ferric chloride water purifier according to claim 4, characterized in that: In steps S5 and S6, the distillation temperature ranges from 90 to 100° C., the rotation speed ranges from 50 to 500 rpm, the freezing temperature ranges from 0 to 15° C., and the freezing time ranges from 0.5 to 5 h.

5. A high-purity ferric chloride water purifier preparation device, suitable for a high-purity ferric chloride water purifier preparation method according to any one of claims 1 to 5, characterized in that: The invention comprises a reaction kettle, an evaporator and a freezing crystallizer. The reaction kettle is used to prepare a ferric chloride solution. The evaporator is used to evaporate and concentrate the ferric chloride solution. The evaporated and concentrated ferric chloride solution is added into the freezing crystallizer for recrystallization.

6. A high-purity ferric chloride water purifier preparation device according to claim 6, characterized in that: The freezing crystallizer includes a crystallization box, a discharge port is provided at the bottom of the crystallization box, a solenoid valve for controlling the opening and closing of the discharge port is installed at the discharge port, the bottom of the crystallization box is in a constricted shape, a first airbag is fixed on the side wall of the crystallization box at the constricted portion, the upper end of the first airbag is a platform, a plurality of second airbags with even intervals are arranged on the platform, the bottom of the second airbag is connected to the first airbag, the elastic modulus of the first airbag is lower than the elastic modulus of the second airbag, the first airbag is connected to an air pump, after the second airbag is expanded, it extends toward the top of the crystallization box, and after the first airbag is expanded, it extends vertically toward the axis direction of the crystallization box.

7. A high-purity ferric chloride water purifier preparation device according to claim 7, characterized in that: A counterweight is arranged inside the top of the second airbag.

8. A high-purity ferric chloride water purifier preparation device and method according to claim 8, characterized in that: A filter tank is arranged at the lower end of the solenoid valve, a collecting tank is fixed below the filter tank, and a filter screen is fixed between the filter tank and the collecting tank.

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