Refractive index: When light is incident from one medium to another, it sometimes changes direction due to changes in speed. This phenomenon is called refraction. When light is refracted from a vacuum into a medium, the angle of incidence The ratio of the sine of the angle of refraction is called the refractive index, and the refractive index is also called the optical index.
Whiteness: Whiteness is the ratio of the absorption and reflection of a substance to visible light. Relative whiteness is a function of wavelength and particle size. Whiteness combines the two optical effects of brightness and hue of white pigments.
Opacity: Opacity refers to the ability of a pigment in a coating to cover the surface of the surface of the object being coated, so that the background color can no longer be transmitted through the coating. Pigment quality (g) hiding power = pigment mass (g) / surface area of ​​coated object (cm 2 ) The greater the hiding power of the pigment, the smaller the value. The hiding power can also be expressed in terms of the surface area of ​​the coated object per gram of pigment, which is the reciprocal of the previous representation. The greater the hiding power of the pigment represented by this method, the larger the value, the thinner the coating film, and the smaller the amount of coating required.
Achromatic power: The decolorizing power of a pigment is the ability of a pigment to be mixed with a pigment of another color to give the resulting mixture its own pigment. In the case of a white pigment, when it is mixed with a dark pigment, the lighter the color of the mixture, the stronger its color reduction.
Oil absorption: The oil absorption of the pigment refers to the minimum mass of oil required per 100g of pigment when it is completely wet. The oil absorption is usually expressed as a percentage.
Effective acid: the acid product solution resulting titanium leach liquid, sulfuric acid is present mainly in three different forms: (1) in combination with the titanium sulphate; (2) in combination with other metal (mainly iron) of sulfuric acid; ( 3) Unbound, excess free acid. Since the acid and free acid bound to titanium cannot be separately determined, the sum of the two can only be determined, so the sum of the two is called an effective acid. Effective Acid = Acid + Free Acid Ratio in Combination with Titanium: The ratio of the effective acid to the total titanium content in the titanium solution is called the acid ratio. The acid ratio, also known as the acidity coefficient, is usually expressed in terms of F.
The stability of titanium liquid: stability, also known as stability, is the tendency of the titanium liquid to precipitate early white colloidal particles in the case of titanium dioxide production. The degree of this tendency is called titanium. The stability of the liquid. The characteristic indicating the strength of this tendency is called the stability of the titanium liquid.
Early hydrolysis of titanium liquid: Generally, the titanium liquid should not contain two kinds of colloidal particles of metatitanic acid and orthotitanic acid from acid hydrolysis to post-hydrolysis, but sometimes it is leached and reduced in titanium liquid. During the transportation and storage process, the above two kinds of white colloidal substances appear in the titanium liquid due to improper operation or changing conditions, which is called early hydrolysis of the titanium liquid.
Acidolysis rate: total soluble titanium salt solution (in terms of TiO 2) accounting for the total amount of titanium contained in the ilmenite administered (in terms TiO 2) percentages, referred to acid hydrolysis rate. Acid solution rate (%) of total titanium content in solution = (total titanium content in solution / total titanium content in ore powder) *100
Residue of Titanium Solution: After decomposing ilmenite with sulfuric acid, the solution obtained by leaching is a complicated system with turbidity. This solution has both the properties of a true solution and the nature of a colloidal solution. It contains both soluble sulfates based on titanium and iron, as well as insoluble, larger particles of suspended mechanical impurities and smaller particles. Higher stability colloidal impurities. The latter two insoluble solid impurities are referred to as the residue of the titanium liquid.
Iron-to-titanium ratio: The ratio of total iron content to total TiO 2 content in titanium solution is called iron-titanium ratio. The formula is as follows: Total Fe content (g/l) iron-titanium ratio = total Fe content (g/l) / total TiO 2 The content (g/l) ratio of iron to titanium has a certain influence on the particle size and structure of the metatitanic acid of the hydrolyzate. Therefore, in the production of titanium dioxide, especially in the production of titanium dioxide powder, it must be controlled within a certain range of iron to titanium.
Concentration of titanium liquid: The water in the titanium liquid is a solvent and is volatile, and the titanium oxysulfate, titanium sulfate and ferrous sulfate in the titanium liquid are solute and are non-volatile. By the action of heating, the solvent (water) in the titanium liquid is gradually vaporized and volatilized to be removed, and the concentration of the solute is gradually increased. This process is called concentration.
The quality requirements of titanium dioxide for coatings: A, good whiteness; B, good wettability; C, good weatherability; D, good chemical stability; E, small particle size, large hiding power, high achromatic power, no Transparency and gloss are good.
Hydrolysis rate: The hydrolysis rate is a value reflecting the degree of completion of hydrolysis. That is, the percentage of liquid phase TiO 2 converted to solid phase TiO 2 . High or low rate of hydrolysis, respectively TiO 2 in the titanium was converted into a solid phase high and low TiO 2 conversion.
Settlement rate: The rate of sedimentation of the metatitanic acid particles in the slurry after hydrolysis is called the sedimentation rate. It is a value that reflects the quality of the hydrolysis and the size of the metatitanic acid particles. The sedimentation rate is high, and the metatitanic acid particles are fine; the sedimentation rate is low, and the metatitanic acid particles are coarse. [next]
Salt treatment: The process of adding a small amount of chemical additives to the modification of metatitanic acid before calcination is called salt treatment, also known as pretreatment.
Post-treatment of titanium dioxide: Post-treatment of titanium dioxide is a process in which the granulated titanium dioxide particles are subjected to particle size fractionation and then subjected to surface modification treatment of the desired particles.
Powdering, aging, weather resistance: for outdoor paints, after the sun and rain, the paint film is gradually destroyed, the surface layer gradually loses its luster, and the pigment particles are separated and become a layer of loose powder that can be wiped off. This phenomenon is called pulverization. At the same time of pulverization, the white paint will yellow and the paint will fade. This phenomenon is called aging of the paint film. The degree to which the paint film can withstand this aging is called weather resistance.
Dispersibility: The manufacture of the coating is actually by finely dispersing the pigment in the adhesive liquid of various base materials by grinding or stirring. The degree of easy dispersion of the pigment in the medium and the dispersion stability in the dispersion are referred to as dispersibility.
The method for decomposing ilmenite by sulfuric acid: According to the concentration of sulfuric acid participating in the reaction and the state of the final reaction product, the acid hydrolysis method of ilmenite is divided into three types, namely, liquid phase method, two-phase method and solid phase method.
Solid phase acidolysis: 80% or more of sulfuric acid is used, the reaction is intense and rapid, and it is completed within 5~30min, and the highest reaction temperature is 250 °C.
The purpose of ripening: the acidification reaction should be matured, the purpose of which is to gradually cool the solid phase. During this cooling process, a part of the unacidified mineral powder continues to interact with the free acid present to improve the acid hydrolysis rate. .
Reduction of titanium liquid: The leached titanium solution contains both ferrous sulfate (FeSO 4 ) and high-iron sulfate Fe 2 (SO 4 ) 3 . The ferrous sulfate is stable in acidic solution, only at a pH greater than 5 The hydrolysis is started only when the high-iron sulfate is in an acidic solution having a pH of 2.5, and hydrolysis starts to form a precipitate of high-iron hydroxide. In the case of titanic acid washing, when the pH reaches 2.5, a hydroxide precipitate is formed and mixed in the metatitanic acid, and the ferric oxide which becomes reddish brown when calcined is mixed in the product, which affects the whiteness of the titanium dioxide. Therefore, the presence of ferric iron is not allowed in the titanium liquid, and the ferric iron must be reduced to divalent iron.
The purpose of the frozen crystallization of titanium liquid is to contain a large amount of ferrous sulfate from the titanium liquid obtained by acid hydrolysis of ilmenite and then water leaching. The purpose of the freeze crystallization is mainly to cause the ferrous sulfate to crystallize and then filter to separate the ferrous sulfate from the titanium liquid.
Purification of titanium liquid: The titanium liquid after removing most of the residue by sedimentation and removing the ferrous sulfate crystal by freeze crystallization still contains some fine solid phase particles with incomplete sedimentation. These solid phase materials are extremely fine and may have a certain charge on the surface. They are a kind of colloidal substance. Due to the small particle size, when the ferrous sulfate crystal is coarsely filtered, it can be filtered and left in the filtrate. In addition, the titanium solution also has titanium removal. Other soluble impurities, harmful impurities must be removed. Filtration of the titanium liquid is a means of removing the solid phase and purifying the titanium liquid.
The purpose of liquid concentration: the particles of metatitanic acid prepared by the titanium liquid having a low concentration are coarse, and the pigment of the obtained titanium white powder is inferior. In order to obtain a fine and uniform metatitanic acid by hydrolysis of the titanium liquid, thereby obtaining a titanium white powder having excellent pigment properties, it is necessary to concentrate the titanium liquid having a relatively low concentration by crystal filtration.
The role of hydrolysis prior to seeding Because seed crystals are the key to determining the shape, size and end product properties of the hydrolysate particles, they are the guide to the induction of thermal hydrolysis. Adding seed crystals has two functions. One is to ensure that the prepared particles are appropriately and uniformly sized, and that there is a certain structure of hydrated titanium dioxide; the second is to accelerate the hydrolysis rate, to make the hydrolysis more complete, and to obtain higher hydrolysis. Rate and titanium dioxide for excellent pigment properties.
Purpose of hydrolysis of titanium liquid: Hydrolysis of titanium liquid is a metatitanic acid in which a titanium dioxide component is converted from a liquid titanium liquid to a solid phase to be separated from soluble impurities in the mother liquid to extract pure titanium dioxide.
The purpose of water washing with metatitanic acid: the purpose of water washing is to use liquid-insoluble separation of water insoluble of metatitanic acid and water solubility of impurity ions to remove a large amount of iron, sulfuric acid and other soluble impurities in the mother liquor absorbed by metatitanic acid. Make it more pure metatitanic acid.
Vacuum filtration washing method: The filtrate is sucked through the filter medium by a pressure difference caused by vacuuming, and the solid is adsorbed on the surface of the filter medium. The water is continuously removed from the dissolved impurity ions with a filter layer during washing.
The working principle of the leaf filter machine: using a material with a plurality of capillary pores as a medium, under the action of vacuum, the solution is passed through the small hole, and the solid is intercepted, thereby achieving the purpose of solid-liquid separation and solid water washing.
The purpose of bleaching: bleaching with trivalent titanium solution, removing high-iron hydroxide, after calcination, it will not produce Fe 2 O 3 with the isomorphous structure of rutile titanium dioxide, so the whiteness and achromatic power of titanium dioxide are not Will fall.
The purpose of calcination: dehydration and desulfurization of metatitanic acid at a high temperature, and formation of titanium dioxide having a certain crystal form and reaching a certain quality index.
The purpose of pulverizing titanium dioxide: The calcined titanium dioxide is mostly agglomerates of particles, which need to be pulverized to achieve the particle size requirements, thereby obtaining the highest possible opacity and other pigment properties.
The role of titanium dioxide coating: the coating is also called surface treatment, which is to coat a special film on the surface of titanium dioxide particles, so that the titanium dioxide particles themselves are separated from the outer medium (air or oil), thus preventing titanium dioxide The photochemical activity affects the stability of the oil and avoids the direct irradiation of ultraviolet light in the sunlight, thereby improving the weather resistance of the titanium dioxide, making it more suitable for outdoor use.
Inorganic coating: an inorganic treating agent is added to the titanium dioxide slurry, and metal ions are deposited on the surface of the titanium dioxide particles in the form of oxides or hydroxides to reduce photochemical activity and improve weather resistance.
Organic coating: organic treatment agent is added to the titanium dioxide slurry to adsorb on the surface of titanium dioxide particles in physical adsorption and chemical adsorption, and the surface properties of titanium dioxide are changed to improve the dispersion of titanium dioxide in different media.
Opacity: refers to the extent to which light does not pass through the pigment particles. The size of the opacity depends first on the refractive index and particle size of the pigment, and of course on the secondary characteristics such as the pigment volume concentration and the oil absorption.
Gloss: A measure of the ability of a substance to reflect a projected light. The stronger the reflection, the greater the gloss.
Hue: It is the color sensation that pigments give people.
Coloring the bottom phase: The colored bottom phase, also known as the gray paint hue, is significantly affected by the average particle size of the pigment and its scattering power.
Tinting strength: Tinting strength refers to the ability of a pigment to give another pigment after it is mixed with another pigment.
Model distinction of titanium dioxide: Titanium dioxide for coating is divided into two types: rutile and anatase. According to international conventions, the rutile type is represented by the first letter R of its English Rutile, which is called R type; the anatase type is represented by the first letter A of its English Anatase, which is called type A. The rutile and anatase types which are not post-treated are referred to as R1 and A1, respectively; the post-treated rutile and anatase types are referred to as R2, R3 and A2, respectively. In China, anatase titanium dioxide for plastics is also referred to as AP type; anatase titanium dioxide for chemical fibers is referred to as AH type.
Quality requirements for enamel titanium dioxide: 1. High purity; 2 less impurities (if containing Fe 2 O 3 or Cr 2 O 3 , the product will produce yellow shade); 3 particles are small and uniform (making it easy to fuse with other materials) Mixing to make it easy to control during melting during melting); 4 has a strong refractive index and high achromatic power, as an opacifier in enamel, with strong opacity and opacity, The coating is thin, smooth and resistant to acid after coating.
The quality requirements of titanium dioxide for welding electrodes: (1) The content of impurities is small, the content of sulfur and phosphorus should not exceed 0.05%, because sulfur and phosphorus are not volatilized during welding and transferred to the weld metal, and sulfur can produce welds. Bubbles and thermal cracks (hot brittleness), phosphorus can produce cold cracks (cold brittleness); (2) small and uniform particles, 0.5% less in 45μm mesh sieve; (3) apparent specific volume in 0.8~0.9g/ Between ml, if it is too small, the viscosity is poor, and the amount of water glass is increased in the formulation, which affects the ignition of the welding operation.
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