1. A method for simplifying the production process of titanium dioxide is characterized by comprising the following steps:

1) wet grinding and sanding are carried out on the titanium dioxide to obtain a titanium dioxide powder sand abrasive;

2) adjusting the concentration and temperature of the titanium white powder sand abrasive, and then adding a flocculating agent;

3) adjusting the pH value of the slurry obtained in the step 2), and transferring the slurry to a three-washing procedure.

2. The simplified method for titanium dioxide production process according to claim 1, wherein a dispersant is added during wet grinding and sand grinding, and the dispersant is sodium silicate or sodium hydroxide.

3. The simplified method for titanium dioxide production process according to claim 1, wherein the concentration of titanium dioxide in the titanium white sand grinding material is 200-600g/L, and the temperature of the titanium white sand grinding material is 10-60 ℃.

4. The method for simplifying the production process of titanium dioxide according to claim 1, wherein the flocculant is at least one of polyacrylamide, aluminum sulfate, aluminum chloride, ferric sulfate, ferric chloride, alum, polyaluminum chloride, polyaluminum sulfate, polyferric chloride and polyferric sulfate.

5. The method for simplifying the production process of titanium dioxide according to claim 4, wherein the flocculating agent is aluminum sulfate.

6. The method for simplifying the production process of titanium dioxide according to claim 1, wherein the amount of the flocculating agent is 0.05-1% of the mass of titanium dioxide in the titanium white sand grinding material.

7. The simplified method for titanium dioxide production process according to claim 1, wherein in step 3), the pH value of the slurry is adjusted to the isoelectric point of the slurry ± 2.

8. The simplified method for titanium dioxide production process according to claim 1, wherein in step 3), the pH value is 3-7.

9. The simplified method for titanium dioxide production process according to claim 8, wherein in step 3), the pH value is 5-6.

Background

Titanium dioxide, the main component of which is titanium dioxide, is a white pigment and is widely applied to the industries of paint, plastics, paper making, printing ink and the like. Compared with other white pigments, the titanium dioxide has superior whiteness, tinting strength, covering power, weather resistance, heat resistance and chemical stability. The industrial production method of titanium dioxide is generally divided into a sulfuric acid method and a chlorination method. The sulfuric acid process is a common conventional production process, and generally comprises the following steps: carrying out acidolysis reaction on the titanium concentrate and concentrated sulfuric acid to produce titanyl sulfate, and generating metatitanic acid through sedimentation, crystallization and hydrolysis; metatitanic acid is subjected to primary washing, bleaching, secondary washing, salt treatment and calcination to obtain a rutile titanium dioxide crude product; wet grinding, sanding, coating, three-time washing, flash drying and air pulverizing the titanium dioxide crude product to obtain the titanium dioxide product.

In order to improve the weather resistance and chemical stability of titanium dioxide and improve the dispersibility of titanium dioxide in various media, titanium dioxide is usually subjected to surface treatment. The inorganic surface treatment is to form a layer of uniform inorganic oxide film on the surface of titanium dioxide particles to block the photoactivation points of the titanium dioxide and improve the weather resistance. The organic treatment is to coat a layer of organic oxide film or surfactant on the surface of the titanium dioxide, so that the titanium dioxide particles can keep a dispersed state and can be well compatible and uniformly dispersed in an organic medium. The titanium dioxide is subjected to surface treatment, generally inorganic surface treatment and then organic surface treatment.

Titanium dioxide has requirements on weather resistance in some downstream application fields, such as exterior wall coatings, inorganic coating needs to be carried out on the titanium dioxide to increase the weather resistance, and the coating application field is a water-based system, and the inorganic coating layer is a hydrophilic layer, so that adverse effects on the application performance of products cannot be generated. However, in some application fields, such as plastics and ink industries, the application systems are oil systems, and the hydrophilic inorganic coating layer of the titanium dioxide is incompatible with the oil systems, so that negative effects can be caused on downstream application. In addition, some application fields have no special requirements on the weather resistance of the titanium dioxide, and in order to reduce the production cost, inorganic coating of the titanium dioxide is not needed, and organic coating can be directly carried out.

At present, titanium dioxide products on the market are subjected to inorganic coating and then organic coating, and the basic reason is that in the production process of the titanium dioxide, titanium dioxide is calcined to form a large amount of agglomerates, wet grinding and sand grinding are firstly carried out to depolymerize titanium dioxide particles, and the process requires that the titanium dioxide has good dispersibility in slurry, so that a dispersing agent needs to be added to achieve a good depolymerization effect, and the luster of the finished titanium dioxide product meets the requirement. The depolymerized slurry has good dispersibility, and if the slurry is directly subjected to triple washing, the filter cloth is seriously penetrated and filtered in the washing process, and the slurry is easy to block the filter cloth, so that the slurry cannot be washed, and the industrial production cannot be realized.

Disclosure of Invention

Aiming at the situations in the prior art, the application aims to provide a method for simplifying the production process of titanium dioxide, which can adjust the dispersibility of sanding slurry in the industrial production of titanium dioxide and enable the sanding slurry to meet the washing requirement of the subsequent procedure; the inorganic coating is cancelled, and the applicability of the titanium dioxide under a specific oily application system is improved; the production cost is saved.

The invention provides a method for simplifying the production process of titanium dioxide, which comprises the following steps:

1) wet grinding and sanding are carried out on the titanium dioxide to obtain a titanium dioxide powder sand abrasive;

2) adjusting the concentration and temperature of the titanium white powder sand abrasive, and then adding a flocculating agent;

3) adjusting the pH value of the slurry obtained in the step 2), and transferring the slurry to a three-washing procedure.

According to the present invention, a suitable dispersant is added during wet milling and sanding, and any dispersant conventionally used in the art, for example, sodium silicate or sodium hydroxide, may be used as the dispersant.

Preferably, the concentration of the titanium dioxide in the titanium white sand grinding material is 200-600g/L, and the temperature of the titanium white sand grinding material is 10-60 ℃.

The pH value of the slurry is adjusted to be close to the isoelectric point of the slurry, such as the isoelectric point +/-2, so that the slurry is beneficial to preliminary flocculation and washing.

The pH value is determined according to a relation graph of Zeta potential and pH of the titanium dioxide water dispersion slurry without inorganic coating, and the Zeta potential value is positive, which indicates that the surface of the particles is positively charged; the Zeta potential value is negative, which indicates that the surface of the particle is negatively charged; the Zeta potential value is zero, which indicates that the surface of the particle is not charged, and the corresponding pH value is called isoelectric point.

The larger the absolute value of the Zeta potential value is, the larger the surface charge quantity of the titanium dioxide particles is, and the particles carry the same charges to generate mutual repulsion, so that the titanium dioxide particles can be well dispersed in the slurry. The smaller the absolute value of Zeta potential, the poorer the dispersibility of the slurry. For example, if the titanium dioxide slurry has an isoelectric point of about 5.8 under the condition of no coating. That is, the titanium dioxide slurry pH is adjusted to about 5.8 (e.g., 4, 5, 6, 7, etc.), which can reduce the dispersibility, achieve flocculation effect, and facilitate the subsequent washing process.

Experimental research shows that factors such as the type and the adding amount of the dispersing agent in the sand grinding material can influence the isoelectric point of the sand grinding material, so that the pH value of the isoelectric point is shifted. Therefore, the isoelectric point of the specific sand grinding material is obtained according to actual detection, and the pH value of the slurry is further adjusted.

In step 3) of the present invention, the pH may be 3 to 7. The pH can be adjusted by using a conventional acid-base solution such as a sulfuric acid solution or a sodium hydroxide solution as required.

Further preferably, the pH is 5-6.

In addition, experimental research simultaneously finds that the problem of penetration filtration exists although the titanium dioxide slurry can be washed by simply adjusting the pH value of the titanium dioxide slurry to about the isoelectric point, and more titanium dioxide particles pass through the filter cloth, so that material waste is caused. It shows that the flocculation requirement of the slurry cannot be met and the good washing effect cannot be achieved by only adjusting the pH value. Therefore, on the basis of adjusting the pH, a small amount of flocculating agent is added, so that the flocculation degree of the slurry can be further increased to meet the washing requirement

In the invention, the flocculant can be one or more of common flocculants, such as polyacrylamide, aluminum sulfate, aluminum chloride, ferric sulfate, ferric chloride, alum, polyaluminum chloride (PAC), polyaluminum sulfate (PAS), polyferric chloride (PFC), polyferric sulfate (PFS) and the like.

Preferably, the flocculant is aluminum sulfate. Because the aluminum source adopted by the traditional inorganic coating is aluminum sulfate or sodium metaaluminate, the flocculant has no negative effect on the subsequent production and is convenient for industrial conversion.

According to the invention, the dosage of the flocculating agent is 0.05-1% of the mass of the titanium dioxide in the titanium white sand grinding material.

The operating steps and parameters not defined in the present invention can be selected conventionally according to the prior art.

Compared with the prior art, the invention has the following beneficial effects:

1. the dispersibility of the sand grinding slurry is adjusted to enable the sand grinding slurry to be subjected to three-washing, so that the industrial production is realized;

2. the inorganic coating is cancelled, and the applicability of the titanium dioxide under a specific oily application system is improved;

3. the production cost is saved.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Example 1

Taking the intercar sand abrasive (the pH value is about 8-10), adjusting the concentration of titanium dioxide to 300g/L, firstly adding 0.1 percent (by mass of titanium dioxide) of flocculant aluminum sulfate, stirring for 10min, then adjusting the pH of the slurry to 5.8, stirring for 10min, and keeping the temperature at 40 ℃ in the process. After the treatment, the mixture is subjected to suction filtration and water washing.

Example 2

Taking the intercar sand abrasive (the pH value is about 8-10), adjusting the concentration of titanium dioxide to 300g/L, firstly adding 0.1 percent (by mass of titanium dioxide) of flocculant aluminum sulfate, stirring for 10min, then adjusting the pH of the slurry to 5.0, stirring for 10min, and keeping the temperature at 60 ℃ in the process. After the treatment, the mixture is subjected to suction filtration and water washing.

Example 3

Taking the intercar sand abrasive (the pH value is about 8-10), adjusting the concentration of titanium dioxide to 300g/L, firstly adding 0.05 percent (by mass of titanium dioxide) of flocculant aluminum sulfate, stirring for 10min, then adjusting the pH of the slurry to 4.0, stirring for 10min, and keeping the temperature at 60 ℃ in the process. After the treatment, the mixture is subjected to suction filtration and water washing.

Comparative example 1

Taking the intercar sand abrasive (the pH value is about 8-10 and the temperature is 40 ℃), adjusting the concentration of titanium dioxide to 300g/L, and directly carrying out suction filtration and washing.

Comparative example 2

Taking the intercar sand abrasive (the pH value is about 8-10), adjusting the concentration of titanium dioxide to 300g/L, adding dilute sulfuric acid solution, adjusting the pH value of the slurry to 5.8, stirring for 10min, and keeping the temperature at 40 ℃ in the process. After the treatment, the mixture is subjected to suction filtration and water washing.

The suction filtration and water washing of each example and comparative example are shown in Table 1.

TABLE 1

Numbering	Suction filtration time	Situation of percolation	Conductivity of filtrate	Solid content of filter cake
					Example 1	2h	Clear filtrate without percolation	20us	73％
Example 2	1.8h	Clear filtrate without percolation	18us	71％
					Example 3	1.5h	Clear filtrate without percolation	15us	71％
Comparative example 1	Difficult to pump and filter	Severe penetration and filtration	/	/
					Comparative example 2	4h	Obvious penetration and filtration	50us	61％

As can be seen from Table 1, the method of the present invention can make the titanium white grit abrasive material without inorganic coating meet the requirement of three-washing, and for titanium white which can meet the application condition without inorganic coating, the production can be simplified, the adverse effect caused by inorganic coating can be avoided, and the applicability of titanium white in a specific oily application system can be increased.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the illustrated embodiments.