Sulfate process, titanium dioxide pigment

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). 

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... 

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... 

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 ... 

Two major processes are used for producing raw titanium dioxide pigment (1) the sulfate process, a batch process accounting for over half of current production, introduced by European makers in die early 1930s and (2) the chloride process, a continuous process, introduced in the late 1950s and accounting for most of the new plant construction since the mid-1960s. The sulfate process can handle both rutile and anatase, but the chloride process is limited to rutile. 

Chloride One of the two process used today for making titanium dioxide pigment, (the other being Sulfate (1)). Mineral rutile, or another mineral rich in titanium, is chlorinated with coke to produce titanium tetrachloride ... 

Monk-Irwin An unsuccessful predecessor of the Sulfate process for making titanium dioxide pigment from ilmenite. Invented by C.R. Whittemore at McGill University, Montreal, in the early 1920s and subsequently developed by J. Irwin and R.H. Monk in Canada and B. Laporte Limited in Luton, UK. Ilmenite from the deposit at Ivry, Quebec was reduced by heating with coke, leached with ferric chloride solution, and then roasted with a mixture of sulfuric acid and sodium sulfate. The resulting cake, containing titanyl sulfate, was dissolved in water and hydrolyzed, and the titania hydrate calcined. Some of the product was extended with barium sulfate. The project was abandoned in 1928. 

There are two major processes for the manufacture of titanium dioxide pigments, namely (1) sulfate route and (2) chloride route. In the sulfate process, the ore limonite, Fe0Ti02, is dissolved in sulfuric acid and the resultant solution is hydrolyzed by boiling to produce a hydrated oxide, while the iron remains in solution. The precipitated titanium hydrate is washed and leached free of soluble impurities. Controlled calcinations at about 1000°C produce pigmentary titanium dioxide of the correct crystal size distribution this material is then subjected to a finishing coating treatment and milling. The process flow sheet is shown in Fig. 7.1 [4],... 

Ecological Aspects of Modern Production Processes. Sulfate Process. The conventional sulfate process is characterized by a linear flow of sulfuric acid through the process. Some H2SO4 ends up in the copperas by-product, but the main part remains separate from the pigment end product, as a used reagent with deteriorated quality in terms of concentration and purity. Formerly, this large stream was discarded as waste (see Fig. 80). Now, the spent acid is recovered, and complex acid concentration and filter salt treatment plants are added to recycle the acid entirely. Hence, the modern sulfate process plant for titanium dioxide pigment manufacture is characterized by a closed sulfuric acid cycle that completely withholds spent acid from the environment (see Fig. 81). 

These ores are the principal raw materials used in the manufacture of titanium dioxide pigment The first step to purify the ore is basically a refinement, using either sulfuric acid (sulfate process Gesenhues et al., 2003) or chlorine (chloride process) as an extraction agent... 

Titanium dioxide is manufactured by two processes, the sulfate process and the chloride process. In the sulfate process, ilmenite ore (FeTiOg) is dissolved in concentrated sulfuric acid and insoluble impurities are removed by clarification, flocculation, sedimentation and filtration. The resulting solution is further purified by crystallization to remove ferrous sulfate from titanyl sulfate solution. The titanyl sulfate solution is then hydrolyzed to give hydrated titanium dioxide, which is calcined at about 900 to 1100 °C to give the titanium dioxide pigment. Both anatase and rutile-type titanium dioxide pigments are produced using this method. 

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