Ilmenite leaching

Synthetic mtile 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. 

A number of high temperature processes for the production of titanium carbide from ores have been reported (28,29). The aim is to manufacture a titanium carbide that can subsequently be chlorinated to yield titanium tetrachloride. In one process, a titanium-bearing ore is mixed with an alkah-metal chloride and carbonaceous material and heated to 2000°C to yield, ultimately, a highly pure TiC (28). Production of titanium carbide from ores, eg, ilmenite [12168-52-4], EeTiO, and perovskite [12194-71 -7], CaTiO, has been described (30). A mixture of perovskite and carbon was heated in an arc furnace at ca 2100°C, ground, and then leached with water to decompose the calcium carbide to acetjdene. The TiC was then separated from the aqueous slurry by elutriation. Approximately 72% of the titanium was recovered as the purified product. In the case of ilmenite, it was necessary to reduce the ilmenite carbothermaHy in the presence of lime at ca 1260°C. Molten iron was separated and the remaining CaTiO was then processed as perovskite. 

Musro [Murphy ores, CSIRO] Also written Murso. A process for beneficiating ilmenite by a combination of oxidation, reduction, and pressure leaching with hydrochloric acid. Invented in Australia in 1967 and developed jointly by Murphyores Pty and the Commonwealth Scientific and Industrial Research Organization, but not commercialized then. Further developed in 1992 by Pivot Mining NL, Queensland. 

Most halloysite appears to be the result of supergene processes and, as noted by Ross and Kerr (1934), leaching by sulphuric acid, produced by the alteration of pyrite, appears to be one of the more common weathering processes. Alunite is commonly associated with halloysite (Ross and Kerr, 1934 Swineford et al., 1954). Sulphuric acid is commonly used to dissolve ilmenite in the manufacture of Ti02 (Willets and Marchett), 1958). It is possible that in nature it serves the same purpose. In the alteration of granitic rocks and pegmatites, feldspar is more likely to alter to halloysite... 

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. 

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. 

In a reducing atmosphere, some of the metallic compounds are reduced to metals and others to the lower oxides. Since subsequent leaching is an oxidation step, the dissolution medium reacts more rapidly with the reduced metal than with the lower oxides, thus giving a certain degree of selectivity. The 100,000-ton/year ilmenite beneficiation plant of Benilite Corporation of America (Cl5) for the production of a feed for chloride-process titanium dioxide plants employs a partial reduction of iron oxides prior to leaching with hydrochloric acid. 

Zircon is usually accompanied by quartz, ilmenite and rutile, and in lesser amounts by garnets, kyanite and monazite, The treatment processes utilize the differences in density ilmenite and rutile are extracted by magnetic and electrostatic separation respectively. These processes provide technical-grade zircon purer zircon is produced by acid leaching. The product usually contains particles mainly 75 — 150 im. 

The alteration of all but the most resistant primary minerals occurs in the mid- to upper saprolite zones in addition, less stable secondary minerals such as smectite are also destroyed. Serpentine, magnetite, ilmenite and chlorite are progressively weathered through the zone. Ferromagnesian minerals are the principal hosts for transition metals such as Ni, Co, Cu and Zn in mafic and ultramafic rocks they become leached from the upper horizons and reprecipitate with secondary Fe-Mn oxides in the mid- to lower-saprolite. 

The chemical enrichment of titanium dioxide in several oxide minerals. This is particularly important for ilmenite, from which iron is leached during weathering. Other titanium-oxide minerals may be leached of other ions for instance, perovskite may be leached of calcium to form microcrystalline anatase. 

In a process variant (Enhanced Acid Regeneration System EARS process), the ilmenite is roasted to convert the titanium component into the insoluble rutile form and to condition the iron component for leaching. The product is then rapidly leached at atmospheric pressure in hydrochloric acid to remove the iron, leaving rutile crystals in the former ilmenite grain. This synthetic rutile (typically 96-98% Ti02) is then washed, filtered, and calcined. The iron chloride leach liquors are processed to regenerate the acid, and the iron oxide pellets can be sold for use by the steel or cement industries. 

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