METHOD TO UPGRADE TITANIA SLAG AND RESULTING PRODUCT

摘要

A method is disclosed including: (a) sizing a titania slag to a particle size range of from 75 microns to 850 microns; (b) oxidizing the sized titania slag by contacting the sized titania slag with an oxygen containing gas at a temperature of at least 1000 DEG C for a period of at least about 20 minutes such that a substantial portion of the iron oxide is converted to a ferric state, such that the reduced titanium oxides are converted to a tetravalent state, and such that at least a major portion of the glassy silicate phase is decomposed; (c) reducing the oxidized titania slag in a reducing atmosphere at a temperature of at least about 700 DEG C for a period of at least about 30 minutes such that the ferric state iron oxide is converted to a ferrous state; (d) leaching the reduced titania slag with mineral acid at a temperature of at least 125 DEG C and under a pressure in excess of atmospheric pressure to yield an upgraded leached slag product and a leachate; and (e) washing and calcining the upgraded leached slag product by heating at a temperature in the range of from 600 DEG C to 800 DEG C. The method provides advantages in that it can be used to produce a product with high TiO2 content that is suitable for the chloride process of TiO2 pigment production.