Direct Carbothermic Reduction of Weathered Ilmenite for Efficient Removal of Iron by Leaching
- PDF / 4,865,806 Bytes
- 13 Pages / 593.972 x 792 pts Page_size
- 84 Downloads / 282 Views
ILMENITE (FeTiO3) is a titanium-containing mineral abundantly available worldwide, predominantly found in beach sand and placer minerals. The synthetic rutile (TiO2) is an intermediate chemical derived from ilmenite while producing pure TiO2.[1,2] The other phase of titanium oxide corresponds to anatase and brookite, generally found as intermediate products. The pure form of TiO2 is typically used in the manufacture of paints, pigments, ceramics, and welding rod coating and for the production of titanium metal.[3] There are several commercialized processes to manufacture pigment grade synthetic rutile.[4–6] The most adopted industrial processes are the sulfate (Becher) process and the chloride (Benelite) process. In recent times, stringent
NAVNEET SINGH RANDHAWA and SANJAY PRASAD are with the Metal Extraction and Recycling Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007, India. Contact email: [email protected] Manuscript submitted June 5, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS B
environmental norms have endorsed the chloride process over the sulfate process as the latter has larger waste management issues. However, the chloride process requires a high grade of ilmenite and higher capital costs for equipment and construction, which subsequently require high operation and maintenance skill.[5] Hence, the usefulness of ilmenite determines the yield and quality of the product toward better economics of the process. Ilmenite often undergoes weathering in natural conditions. This weathering leads to altered mineralogy to obtain the predetermined quality. The altered ilmenite fraction in the beach sand minerals has not been estimated so far. The total quantities of altered minerals are different in different countries; however, reports on their separation studies are not available. All titanium values are calculated collectively for the whole mineral deposit. Nevertheless, the degree of weathering or alteration is an indicator of the ilmenite’s economic value.[7] The altered or oxidized ores respond differently in the conventional processes compared to the fresh/ unaltered ore.[1,8–10] For instance, the variation in the degree of leaching of ilmenite depends on the extent of alteration. The high ferric iron content of the altered
ilmenite warrants a reduction process rather than a sulfate process for TiO2 production.[11] Additionally, an increase in the degree of weathering has been found to decrease the rate of iron reduction.[12] The stoichiometric ilmenite reduces faster than the pseudorutile (Fe2Ti3O9) phase, which is a product of weathering. The reduction of ilmenite with an excess of carbon (30 wt pct) results in the product rich in suboxide of titanium.[13] Hydrogen has also been used to reduce the iron oxide present in the ilmenite phase.[14] Yet, the significant chemical alteration due to weathering requires significant changes in the processing steps participating in the reduction and in the subsequent leaching processes. Therefore, necessary improvement in the reduction process is
Data Loading...
