Synthetic Rutiles

TSR (2) [Tiomin synthetic rutile] A process for removing much of the iron from ilmenite in order to make a feedstock for titanium pigment manufacture. Developed by Tiomin Resources, Canada, in the 1990s. 

Synthetic Rutile. In contrast to ilmenite, only a small number of rutile deposits can be mined economically, and the price of natural rutile is therefore high. Consequently, many different processes have been developed to remove the iron from ilmenite concentrates without changing the grain size of the mineral because this is highly suitable for the subsequent fluidized-bed chlorination process. All industrial processes involve reduction of Fe3+ with carbon or hydrogen, sometimes after preliminary activation of the ilmenite by oxidation. Depending on the reducing conditions, either Fe2 + is formed in an activated ilmenite lattice, or metallic iron is produced. 

The activated Fe2+-containing ilmenite can be treated with hydrochloric or dilute sulfuric add (preferably under pressure), and a synthetic rutile with a Ti02 content of 85-96% is obtained [2.15]. The solutions containing iron(II) salts are concentrated and then thermally decomposed to form iron oxide and the free acid, which can be used again in the digestion process [2.16]. 

Another possible method of increasing the TiOz content of ilmenite is by partial chlorination of the iron in the presence of carbon. This is operated on a large scale by several companies [2.24], [2.25], The most important companies which are producing synthetic rutile are located in Australia (Renison Goldfields Consolidated, Tiwest, Westralian Sands), United States (Kerr-McGee Synthetic Rutile), India (Ke-vala Minerals and Metals Ltd., DCW Ltd., Bene-Chlor Chemicals Ltd.), and Malaysia (Hitox). In 1994 production of synthetic rutile was about 0.6 x 106 t of contained TiOz. 

Titanium slag and synthetic rutile are also used as raw materials in the production of titanium whites. Titanium slag results from a metallurgical process during which iron (qv) is removed from ilmenite by reduction with coke in an electric arc furnace at 1200—1600°C. Under these conditions, iron oxide is reduced to metal, melts, and separates from the formed titanium slag. Titanium slag contains 70—75% Ti02 and only 5—8% iron. 

Synthetic rutile raw material is produced from ilmenite by reducing the iron oxides and leaching out the metallic iron with hydrochloric or sulfuric acids. In both processes, the objective is to increase the amount of Ti02 in the raw materials. 

The iron sulfate crystallizes out from the titanium persulfate solution and can be recycled to make more sulfuric acid. The sulfate process uses the ore ilmenite as a raw material, while the chloride process requires rutile. Ilmenite can be converted to synthetic rutile. 

Beach sand Slag Rutiles Synthetic rutiles... 

The resultant slag, a complex mixture of titanates, may contain 70—85% TiCL. The slag route is particularly useful when ilmenite is closely associated with haematite, from which it cannot economically be separated mechanically. Because the iron content of the slag is low, its use reduces the quantity of iron sulfate in the liquid effluent of sulfate process plants. Slag used as a feedstock for TiCl4 production must be low in magnesium and calcium. A variety of other ilmenite beneficiation or synthetic rutile processes have been pursued, primarily to provide alternative chloride process feedstocks. Low grade ilmenite... 

Manufacture. Titanium chloride is manufactured by the chlorination of titanium compounds (1,134—138). The feedstocks usually used are mineral or synthetic rutile, beneficiated ilmenite, and leucoxenes. Because these are all oxygen-containing, it is necessary to add carbon as well as coke from either coal or fuel oil during chlorination to act as a reducing agent. The reaction is normally carried out as a continuous process in a fluid-bed reactor (139). The bed consists of a mixture of the feedstock and coke. These are fluidized by a stream of chlorine introduced at the base (see Fluidization). The amount of heat generated in the Ti02 chlorination process depends on the relative proportions of C02 or CO that are formed (eqs. 1 and 2), and the mechanism that determines this ratio is not well understood. 

SREP [Synthetic Rutile Enhancement Process] An improved version of the Becher process for upgrading titanium ores. It is designed to reduce the level of radioactive contamination in the product. Developed in the early 1990s by Renison Goldfields, Australia, in collaboration with the CSIRO, Perth, and first operated in Narngulu in 1996. 

TSR (2) [Tiomin Synthetic Rutile] A process for removing much of the iron from ilmenite in order to make a feedstock for titanium pigment manufacture. The ore is successively oxidized and reduced in fluidized beds, and then leached with hydrochloric acid. The product contains approximately 95% of titanium dioxide. Developed by Tiomin Resources, Canada, in the 1990s. Planned to be tested on a large scale in Queensland, Australia. 

The starting materials for Ti02 production are ilmenite and titanium slag in the case of the sulfate process (see Section 5.9.2.2.3) and leucoxene, rutile, synthetic rutile, titanium slag and in the future possibly also anatase for the chloride process (see Section 5.9.2.2.3). 

Synthetic rutile. In recent years the prices for natural rutile have increased due to the increasing scarcity of economically exploitable deposits. Processes for removing iron from ilmenite ore have been developed, to provide a cheap raw material for the chloride process in which the particle form is retained, as this is particularly favorable for fluidized bed chlorination. 

Synthetic rutile has a Ti02-content of 85 to 90%. In all these processes iron is either removed in the form of a salt solution which has to be worked up or as valueless oxide. In the process for the production of titanium slag, on the other hand, metallic iron is obtained, which makes this process more interesting both ecologically and economically. As a result, a large proportion of the synthetic rutile manufacture plants has been closed down. 

In the chloride process natural rutile ore or synthetic rutile with a Ti02-content of up to 96% is chlorinated in a fluidized bed reactor with oil-coke and chlorine. The raw TiCl4 produced is mixed with reducing agents to convert impurities, such as vanadium oxychloride, to lower valency state vanadium compounds. The titanium tetrachloride formed is then distilled yielding titanium tetrachloride in... 

Figure 14. Raman spectra of Ti02 A, synthetic rutile single crystal cube B, powder sample, 99.34% rutile and...

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