Titanium dioxide sulfate process

A typical plant production of titanium dioxide (sulfate process) is shown in the process diagram (Figure 22.16). 

Sulfate-resisting cement, 5 498 Sulfate surfactants, 24 145 Sulfate titanium dioxide production process, 29 388-391 Sulfathiazole, 28 684 Sulfation, 23 513, 514, 536-538 higher aliphatic alcohols, 2 4 in higher olefins, 27 713 Sulfation operations, industrial changes affecting, 23 515-516 Sulfation processes, general overviews of, 23 555... 

Figure 8.13 Two commercial processes used to manufacture titanium dioxide Sulfate prooess produces titanium dioxide from the mineral ilmenite Chloride process manufactures titanium dioxide from the mineral rutile...

The main impurity of the filtrate is the iron(II) sulfate which can be crystallized as the heptahydrate, FeS04-7H2 O, by cooling the solution to a temperature below 15°C. This process is most often carried out in vacuum crystallizers. The crystals of iron sulfate are separated by centrifugation or filtration (qv). To prevent premature hydrolysis of titanium dioxide, the temperature of the above processes should not exceed 70°C. 

Paints. Paints account for perhaps 3% of sulfur consumption (see Paint). The main sulfur use is for the production of titanium dioxide pigment by the sulfate process. Sulfuric acid reacts with ilmenite or titanium slag and the sulfur remains as a ferrous sulfate waste product. Difficulties with this process have led to the development of the chloride process (see Pigments, inorganic Titanium compounds). 

Precipitation of a hydrated titanium oxide by mixing aqueous solutions of titanium chloride with alkaU forms the precipitation seeds, which are used to initiate precipitation in the Mecklenburg (50) variant of the sulfate process for the production of pigmentary titanium dioxide. Hydrolysis of aqueous solutions of titanium chloride is also used for the preparation of high purity (>99.999%) titanium dioxide for electroceramic appHcations (see Ceramics). In addition, hydrated titanium dioxide is used as a pure starting material for the manufacture of other titanium compounds. 

Two pigment production routes ate in commercial use. In the sulfate process, the ore is dissolved in sulfuric acid, the solution is hydrolyzed to precipitate a microcrystalline titanium dioxide, which in turn is grown by a process of calcination at temperatures of ca 900—1000°C. In the chloride process, titanium tetrachloride, formed by chlorinating the ore, is purified by distillation and is then oxidized at ca 1400—1600°C to form crystals of the required size. In both cases, the taw products are finished by coating with a layer of hydrous oxides, typically a mixture of siUca, alumina, etc. 

Titanium dioxide (E171, Cl white 6) is a white, opaque mineral occurring naturally in three main forms rutile, anatase, and brookite. More than 4 million tons of titanium dioxide are produced per year and it is widely used for industrial applications (paints, inks, plastics, textiles) and in small amounts as a food colorant. ° "° Production and properties — Titanium oxide is mainly produced from ilmenite, a titaniferous ore (FeTiOj). Rutile and anatase are relatively pure titanium dioxide (Ti02) forms. Titanium oxide pigment is produced via chloride or sulfate processes via the treatment of the titanium oxide ore with chlorine gas or sulfuric acid, followed by a series of purification steps. High-purity anatase is preferred for utilization in the food industry. It may be coated with small amounts of alumina or silica to improve technological properties. 

Two processes are used in the manufacture of titanium dioxide pigments the sulfate process and the chloride process. The chemistry of the sulfate process, the longer established of the two methods, is illustrated schematically in Scheme 9.1. In this process, crude ilmenite ore, which contains titanium dioxide together with substantial quantities of oxides of iron, is digested with concentrated sulfuric acid, giving a solution containing the sulfates of Ti(iv), Fe(m) and Fe(n). Treatment of this... 

Production of titanium dioxide in the industry can be achieved through two different processes— the sulfate and chloride processes. 

Summary of Raw Waste Loading Found in Screening and Verification Sampling of Titanium Dioxide (the Sulfate Process)... 

Common pollutants in a titanium dioxide plant include heavy metals, titanium dioxide, sulfur trioxide, sulfur dioxide, sodium sulfate, sulfuric acid, and unreacted iron. Most of the metals are removed by alkaline precipitation as metallic hydroxides, carbonates, and sulfides. The resulting solution is subjected to flotation, settling, filtration, and centrifugation to treat the wastewater to acceptable standards. In the sulfate process, the wastewater is sent to the treatment pond, where most of the heavy metals are precipitated. The precipitate is washed and filtered to produce pure gypsum crystals. All other streams of wastewater are treated in similar ponds with calcium sulfate before being neutralized with calcium carbonate in a reactor. The effluent from the reactor is sent to clarifiers and the solid in the underflow is filtered and concentrated. The clarifier overflow is mixed with other process wastewaters and is then neutralized before discharge. 

A typical wastewater treatment process diagram in a titanium dioxide (the sulfate process) plant is shown in Figure 22.18. 

Blumenfeld An early version of the Sulfate process for making titanium dioxide pigment, in which the nucleation of the precipitation of titania hydrate is accomplished by dilution under controlled conditions. Invented by J. Blumenfeld, a Russian working in London in the... 

The process was developed by Du Pont in the 1940s and its first plant started operating in 1958. It has progressively replaced the older Sulfate Process because it produces less effluent in 1998, 56 percent of the world capacity for titanium dioxide production used the Chloride Process. See also ICON. 

Modop [Mobil Oil Direct Oxidation Process] A process for removing residual sulfur-containing gases from the tail gas from the Claus process. The catalyst is titanium dioxide pelletized with calcium sulfate. Developed in the 1980s by Rhone-Poulenc, Procatalyse, and Mobil Oil. Three plants were operating in Germany in 1995 and one in the United States. European Patents 60,742 78,690. 

Sulfate (1) A process for making titanium dioxide pigment from ilmenite. The ilmenite is digested with sulfuric acid, yielding a solution of litany 1 and ferrous sulfates ... 

Titanium dioxide, in the form of either rutile or anatase, can also be obtained from ilmenite by treatment with sulfuric acid (the sulfate process), followed by hydrolysis and then thermal dehydration of the resulting TiO(OH)2. The chloride process, however, is now more widely used than... 

Sulfate process -for pulps [PULP] (Vol 20) -for titanium dioxide piTANIUM COMPOUNDS - INORGANIC] (Vol24) -for titanium pigments [PIGMENTS - INORGANIC] (Voll9)... 

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