阅读说明：本技术 一种硫酸法钛白电解三价钛的电解装置 (Electrolysis device for electrolyzing trivalent titanium from titanium white by sulfuric acid process ) 是由 黄宝荣 田少囡 于 2021-09-16 设计创作，主要内容包括：本发明涉及一种钛白粉酸解后硫酸钛溶液中三价铁的电解装置,所述装置由单元反应器重叠并加压密封组合,第一级和最后一级单元反应器外侧设置有封头,单元反应器分为阳极和阴极两种,每一单元反应器均由网状电极和板框组成,网状电极置于板框的纵向中点,电解液从中流过,阴极反应器和阳极反应器交替密封组合,阴极反应器和阳极反应器之间设置离子膜,所述单元反应器的重叠组数≥10；所述电极为钛镀钽电极。本发明的电解装置大大降低了现有硫酸法钛白粉工艺的成本,并提高了产品的纯度以及工艺的环保性。(The invention relates to an electrolysis device for ferric iron in titanium sulfate solution after titanium dioxide acidolysis, which is formed by overlapping, pressurizing and sealing combination of unit reactors, wherein end sockets are arranged at the outer sides of a first-stage unit reactor and a last-stage unit reactor, the unit reactors are divided into an anode and a cathode, each unit reactor consists of a mesh electrode and a plate frame, the mesh electrode is arranged at the longitudinal midpoint of the plate frame, electrolyte flows through the mesh electrode, the cathode reactor and the anode reactor are alternately sealed and combined, an ionic membrane is arranged between the cathode reactor and the anode reactor, and the overlapping group number of the unit reactors is more than or equal to 10; the electrode is a titanium tantalum-plated electrode. The electrolysis device greatly reduces the cost of the existing sulfuric acid method titanium dioxide process, and improves the purity of the product and the environmental protection of the process.)

1. An electrolysis device for electrolyzing trivalent titanium from titanium white by a sulfuric acid method,

the device is combined by overlapping and pressurizing the unit reactors,

the outer sides of the first-stage unit reactor and the last-stage unit reactor are provided with end sockets,

the unit reactors are divided into an anode and a cathode, each unit reactor consists of a mesh electrode and a plate frame, the mesh electrode is arranged at the longitudinal midpoint of the plate frame, the electrolyte flows through the mesh electrode,

the cathode reactor and the anode reactor are alternately sealed and combined,

an ionic membrane is arranged between the cathode reactor and the anode reactor,

the number of the overlapping groups of the unit reactors is more than or equal to 10; the electrode is a titanium tantalum-plated electrode.

2. A process for electrolyzing trivalent titanium from sulfate process titanium dioxide by using the electrolysis apparatus of claim 1.

Technical Field

The invention belongs to the field of chemical industry, and particularly relates to an electrolysis device adopted in a reduction process of ferric iron in a titanium sulfate solution after acidolysis of titanium dioxide by a sulfuric acid method.

Background

The sulfuric acid method and the chlorination method are main processes for producing the titanium dioxide, and the sulfuric acid method has the advantages of low raw material price, low product cost, low investment and simple equipment. The quality of sulfuric acid process products has been greatly improved over decades of improvement. The first step of the process is to mix ilmenite and sulfuric acid for acidolysis reaction, i.e. ilmenite and sulfuric acid react to convert titanium in minerals into soluble sulfate, so that the soluble sulfate is separated from other impurities. The chemical reaction principle of the process is as follows:

TiO₂+H₂SO₄＝TiOSO₄+H₂O

FeO+H₂SO₄＝FeSO₄+H₂O

Fe₂O₃+3H₂SO₄＝Fe₂(SO₄)₃+3H₂O

the solid generated by the reaction is washed by water and becomes titanium oxysulfate, ferrous sulfate and a large amount of Fe³⁺And (3) solution of impurities, namely acidolysis titanium solution. During the production process, a certain amount of iron must be added to reduce ferric iron into ferrous iron, and then the ferrous iron is separated and removed. If the hydrolysis reaction is directly carried out without removing the ferric impurities, the titanium dioxide product with good quality can not be obtained.

The reduction process of ferric iron in titanium sulfate solution after acidolysis includes adding reduced iron powder into titanium sulfate solution and adding Fe into the solution³⁺Reduction to Fe²⁺While reducing a small amount of (1-3g/L) TI⁴⁺Meets the process requirements of the post-procedure. Whether iron sheet, iron filings or iron powder, the quality of the finished titanium dioxide product is influenced finally due to the impurities, oil stains and nonferrous metal impurities contained in the iron sheet, the iron filings or the iron powder. In addition, the Fe powder is adopted for reduction, the reaction is violent, the temperature rise is rapid, the hydrolysis reaction of the salt can be advanced due to the characteristic of the titanium sulfate solution, particularly, the local overhigh temperature can cause the hydrolysis reaction of the salt to occur, partial titanium sulfate hydrolysate is formed in the titanium sulfate solution, most of the partial hydrolysate is removed by the subsequent impurity removal procedures such as filtration and the like to cause the loss of titanium, and a small part of hydrolysate which cannot be removed can enter the key process of titanium white in the sulfuric acid method for hydrolysis, and the hydrolysis is carried out before the ordered guide hydrolysis beginsThe hydrolysis product may cause undesirable crystalline centers during the hydrolysis process, which ultimately affects the particle size distribution of the product and thus the optical properties. Therefore, the reduction with iron requires strict control of temperature rise conditions, and the process conditions are severe. Reducing by adopting reduced iron powder, adding iron powder and sulfuric acid into the materials additionally, dissolving the ferrous sulfate obtained by reaction in a titanium sulfate mother solution, wherein the concentration of the ferrous sulfate in the mother solution is greatly higher than the requirement of a subsequent hydrolysis process, and additionally cooling and crystallizing to remove the redundant ferrous sulfate in the mother solution. In addition, Fe is generally used³⁺Under the condition of ore sources with the content of 10 percent, the cost of the reduced iron powder required to be consumed in the reduction process of the titanium sulfate solution after acidolysis is 200 yuan/ton of titanium white, and the reduction cost is higher.

Trivalent titanium by electrolysis has attracted attention of those skilled in the art because it does not add iron element, and is an effective alternative to the iron powder reduction process. The process only utilizes the electrolysis of mother liquor to generate reduction, can reduce the generation of ferrous sulfate byproducts caused by the addition of reduced iron powder, saves iron resources, adopts the current electrolysis method to directly electrolyze ferric iron solution, also adopts titanium sulfate solution prepared by electrolysis to electrolyze, but usually adopts a single-stage electrolytic chamber provided with an ion diaphragm to electrolyze, has poor operation stability and high operation cost, can only be applied to a small electrolytic cell reaction chamber with laboratory conditions at present, can not obtain required electrolyte by direct amplification, can greatly increase application cost, and exceeds the reduction process of directly adding iron powder, so that the process can not be put into industrial production at all.

Disclosure of Invention

The invention aims to solve the problems that in the prior art, the iron reducing agent adopted in the production process of titanium dioxide by a sulfuric acid method has high impurity content and high cost, and the quality is influenced by local overheating of a titanium sulfate solution caused by reaction heat in the reduction process. By additionally arranging the electrolysis device in the process, the trivalent titanium electrolysis process which does not introduce impurities, has low cost and simple process and can be directly applied to the actual production process and the electrolysis device adopted by the process are further provided.

The invention provides an electrolysis device for a process for electrolyzing trivalent titanium by sulfate process titanium dioxide, which is formed by overlapping and pressurizing sealing combination of unit reactors, wherein end sockets are arranged at the outer sides of a first-stage unit reactor and a last-stage unit reactor, the unit reactors are divided into an anode and a cathode, each unit reactor consists of a mesh electrode and a plate frame, the cathode reactors and the anode reactors are alternately sealed and combined, an ionic membrane is arranged between the cathode reactors and the anode reactors, the mesh electrode is arranged at the longitudinal midpoint of the plate frames, electrolyte flows through the mesh electrode, and the overlapping group number of the unit reactors is more than or equal to 10; preferably 12-16 stages; the electrode is a titanium tantalum-plated electrode. This reactor is by the inside polar plate that adds of monolithic sheet frame, increases ionic membrane's structure between two sheet frames, and the structure promptly is: the structure of the end socket I (cathode plate frame I) ion film I (anode plate frame I ion film I … … I (cathode plate frame I ion film I) ion film I (anode plate frame I ion film I) end socket is disclosed. Different with the structure of traditional plate and frame electrochemical reactor, traditional plate and frame structure: an end socket I plate I anode I ion film I cathode I plate I … I end socket.

The process for electrolyzing trivalent titanium by sulfate process titanium dioxide comprises the following steps:

(1) carrying out acidolysis on the titanium concentrate/titanium slag and sulfuric acid in an acidolysis reaction tank to obtain acidolysis titanium liquid;

(2) the titanium acidolysis solution flows into a reduction tank, and trivalent titanium solution obtained by electrolyzing the titanium acidolysis solution is added into the reduction tank;

(3) part of the titanium liquid flowing out of the reduction tank enters a cathode chamber of the multi-stage electrolytic tank, and part of the titanium liquid enters a hydrolysis reaction tank after being concentrated; the titanium solution entering the multi-stage electrolytic cell contains Ti in terms of titanium dioxide⁴⁺The concentration of (b) is 140-170 g/L;

(4) returning the trivalent titanium solution generated after the electrolysis in the multistage electrolytic cell to a reduction cell to reduce the titanium acidolysis solution; in the multi-stage electrolytic reaction, dilute sulfuric acid is added into an anode; the current density is 200-400A/m²And the operation is carried out for 48 to 72 hours, and the electrolytic stage number is more than or equal to 10.

Preferably, the titanium liquid flowing out of the reduction tank is subjected to sedimentation and heat filtration for crystallization and separation to remove ferrous sulfate, and part of the titanium liquid after fine filtration enters the electrolytic tank.

Preferably, the trivalent titanium solution in the step (2) is calculated by titanium dioxide, Ti³⁺The concentration is 130-150 g/L;

in the electrolysis process, dilute sulfuric acid is used as anolyte, clarified titanium liquid is used as catholyte, a titanium tantalum-plating electrode is used, two mediums are isolated by an ionic membrane, and tetravalent titanium in the titanium liquid is reduced. Dilute sulfuric acid is a strong electrolyte and is readily soluble in water, ionized in aqueous solution to produce H⁺And HSO^4－And also a small amount of OH^-Ions. In the clear titanium solution, TiO is mainly used²⁺And SO₄ ^2-. Before electrifying, various ions move freely in water; after the power is switched on, the freely moving ions are changed into directional movement under the action of an electric field. Positively charged TiO in solution²⁺Moving to the cathode, the negatively charged OH^-The ions move towards the anode. At the cathode, the tetravalent titanium ions obtain electrons and are reduced into trivalent titanium ions; at the anode, the hydroxide ions lose electrons and are oxidized to oxygen, and are discharged from the anode.

The main reaction equation:

anode main reaction: 4OH^--4e＝＝O₂↑+2H₂O

And (3) cathode main reaction: TiO 2²⁺+2H⁺+e＝＝Ti³⁺+H₂O

And (3) total electrolytic reaction: 4TiO 2²⁺+4OH^-+8H⁺＝＝4Ti³⁺+O₂↑+6H₂O

The invention also claims the titanium dioxide prepared by the method.

The invention has the following beneficial effects:

(1) the invention does not need to add iron powder (scrap iron, iron sheet and the like) and sulfuric acid in the reduction process, thereby saving the cost of the reduction reaction. The cost of consuming reduced iron powder is 200 yuan/ton titanium white, and the comprehensive cost of the process for electrolyzing the trivalent titanium is 95 yuan/ton titanium white. The invention uses the electrolytic method to directly produce the trivalent titanium without adding other reducing agents, thereby avoiding the influence of impurities in the reduced iron powder on the quality of the titanium dioxide. The electrolysis process avoids the influence of local overheating of the titanium sulfate solution caused by reaction heat in the iron powder reduction process on the quality of the titanium dioxide finished product.

(2) The applicant researches and develops a multi-stage electrolytic structure special for reduction reaction through years of research and experiments, the structure adopts specific electrode materials, the number of electrode layers is strictly set, the structure of the device is simple, trivalent titanium liquid generated by electrolysis can be directly returned to an acidolysis tank for reduction reaction, the cost of the whole process is greatly reduced, the process flow is simplified, and the quality of titanium dioxide is improved.

(3) The enterprises of the sulfate process titanium dioxide strive to improve the product quality and the environmental protection of the process. By adopting the process of the invention, high-quality titanium dioxide can be obtained only by adding a pipeline to the existing sulfuric acid method titanium dioxide production process and arranging a corresponding electrolysis device without greatly changing the existing equipment, thereby greatly improving the market competitiveness of the sulfuric acid method titanium dioxide production.

Drawings

FIG. 1 is a process flow diagram employed in the present invention;

FIG. 2 is a schematic diagram of an electrolytic apparatus used in the present invention.

Detailed Description

The following examples are given to further illustrate embodiments of the present invention:

example 1

The preparation method of the titanium dioxide comprises the following steps:

(1) carrying out acidolysis on titanium slag serving as a raw material and sulfuric acid in an acidolysis reaction tank to obtain acidolysis titanium liquid;

(2) the titanium acidolysis solution flows into a reduction tank, and trivalent titanium solution obtained by electrolyzing the titanium acidolysis solution is added into the reduction tank;

(3) the titanium liquid flowing out of the reduction tank is further subjected to sedimentation and heat filtration for crystallization and separation to remove ferrous sulfate, the titanium liquid is subjected to fine filtration and then enters a cathode chamber of a multi-stage electrolytic tank, and part of the titanium liquid enters a hydrolysis reaction tank after being concentrated; the titanium solution entering the multi-stage electrolytic cell contains Ti in terms of titanium dioxide⁴⁺The concentration of (A) is 170 g/L;

(4) trivalent titanium solution generated after electrolysis in multi-stage electrolytic cellReturning to the reduction tank, and reducing the titanium acidolysis solution; in the multistage electrolytic reaction, a titanium-plated tantalum electrode is adopted as an electrode, and dilute sulfuric acid is added into an anode; the current density is 400A/m²When the reactor runs for 48 hours, the number of the electrolytic unit reactors is 12;

(5) the titanium dioxide with qualified quality is finally obtained by the prior process of concentration hydrolysis, calcination, ball milling and post-treatment.

Example 2

The preparation method of the titanium dioxide comprises the following steps:

(1) carrying out acidolysis on titanium slag serving as a raw material and sulfuric acid in an acidolysis reaction tank to obtain acidolysis titanium liquid;

(2) the titanium acidolysis solution flows into a reduction tank, and trivalent titanium solution obtained by electrolyzing the titanium acidolysis solution is added into the reduction tank;

(3) the titanium liquid flowing out of the reduction tank is further subjected to sedimentation and heat filtration for crystallization and separation to remove ferrous sulfate, the titanium liquid is subjected to fine filtration and then enters a cathode chamber of a multi-stage electrolytic tank, and part of the titanium liquid enters a hydrolysis reaction tank after being concentrated; the titanium solution entering the multi-stage electrolytic cell contains Ti in terms of titanium dioxide⁴⁺The concentration of (A) is 150 g/L;

(4) returning the trivalent titanium solution generated after the electrolysis in the multistage electrolytic cell to a reduction cell to reduce the titanium acidolysis solution; in the multistage electrolytic reaction, a titanium-plated tantalum electrode is adopted as an electrode, and dilute sulfuric acid is added into an anode; the current density is 200A/m²When the reactor runs for 60 hours, the number of the electrolytic unit reactors is 16;

(5) the titanium dioxide with qualified quality is finally obtained by the prior process of concentration hydrolysis, calcination, ball milling and post-treatment.

Example 3

The preparation method of the titanium dioxide comprises the following steps:

(1) carrying out acidolysis on titanium slag serving as a raw material and sulfuric acid in an acidolysis reaction tank to obtain acidolysis titanium liquid;

(2) the titanium acidolysis solution flows into a reduction tank, and trivalent titanium solution obtained by electrolyzing the titanium acidolysis solution is added into the reduction tank;

(3) the titanium liquid flowing out of the reduction tank is further subjected to sedimentation, heat filtration, crystallization, separation and ferrous sulfate removal, and fine filtrationThe rear part enters a cathode chamber of a multistage electrolytic cell, and part of the titanium liquid enters a hydrolysis reaction tank after being concentrated; the titanium solution entering the multi-stage electrolytic cell contains Ti in terms of titanium dioxide⁴⁺The concentration of (A) is 170 g/L;

(4) returning the trivalent titanium solution generated after the electrolysis in the multistage electrolytic cell to a reduction cell to reduce the titanium acidolysis solution; in the multistage electrolytic reaction, a titanium-plated tantalum electrode is adopted as an electrode, and dilute sulfuric acid is added into an anode; the current density is 300A/m²The operation lasts for 72 hours, and the number of the electrolytic unit reactor is 10;

(5) the titanium dioxide with qualified quality is finally obtained by the prior process of concentration hydrolysis, calcination, ball milling and post-treatment.

Comparative example 1

The preparation method of the titanium dioxide comprises the following steps:

(1) carrying out acidolysis on titanium slag serving as a raw material and sulfuric acid in an acidolysis reaction tank to obtain acidolysis titanium liquid;

(2) the titanium acidolysis solution flows into a reduction tank, and trivalent titanium solution obtained by electrolyzing the titanium acidolysis solution is added into the reduction tank;

(3) the titanium liquid flowing out of the reduction tank is further subjected to sedimentation and heat filtration for crystallization and separation to remove ferrous sulfate, the titanium liquid is subjected to fine filtration and then enters a cathode chamber of a multi-stage electrolytic tank, and part of the titanium liquid enters a hydrolysis reaction tank after being concentrated; the titanium solution entering the multi-stage electrolytic cell contains Ti in terms of titanium dioxide⁴⁺The concentration of (A) is 170 g/L;

(4) returning the trivalent titanium solution generated after the electrolysis in the multistage electrolytic cell to a reduction cell to reduce the titanium acidolysis solution; in the multi-stage electrolytic reaction, a graphite electrode is adopted as an electrode, and dilute sulfuric acid is added into an anode; the current density is 300A/m²The operation lasts for 72 hours, and the number of the electrolytic unit reactor is 10;

(5) the titanium dioxide with qualified quality is finally obtained by the prior process of concentration hydrolysis, calcination, ball milling and post-treatment.

Comparative example 2

The preparation method of the titanium dioxide comprises the following steps:

(1) carrying out acidolysis on titanium slag serving as a raw material and sulfuric acid in an acidolysis reaction tank to obtain acidolysis titanium liquid;

(2) the titanium acidolysis solution flows into a reduction tank, and trivalent titanium solution obtained by electrolyzing the titanium acidolysis solution is added into the reduction tank;

(3) the titanium liquid flowing out of the reduction tank is further subjected to sedimentation and heat filtration for crystallization and separation to remove ferrous sulfate, the titanium liquid is subjected to fine filtration and then enters a cathode chamber of a multi-stage electrolytic tank, and part of the titanium liquid enters a hydrolysis reaction tank after being concentrated; the titanium solution entering the multi-stage electrolytic cell contains Ti in terms of titanium dioxide⁴⁺The concentration of (A) is 170 g/L;

(4) returning the trivalent titanium solution generated after the electrolysis in the multistage electrolytic cell to a reduction cell to reduce the titanium acidolysis solution; in the multi-stage electrolytic reaction, a DSA titanium electrode is adopted as an anode, an activated carbon electrode is adopted as a cathode, and dilute sulfuric acid is added into the anode; the current density is 300A/m²The operation lasts for 72 hours, and the number of the electrolytic unit reactor is 10;

(5) the titanium dioxide with qualified quality is finally obtained by the prior process of concentration hydrolysis, calcination, ball milling and post-treatment.

Comparative example 3 is a commercial titanium dioxide product without special treatment.

The results of comparing the resistivity of the titanium dioxide of the present invention with the resistivity of the comparative water extract are as follows.

TABLE 1

The improvement point of the invention lies in the improvement of the electrolysis process and device and the whole process for preparing the titanium dioxide by the sulfuric acid method, and the process steps and the structure which are well known in the field are not repeated. The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed. Therefore, the scope of the invention should not be limited by the description of the embodiments, but should be determined by the following claims.