METHOD TO UPGRADE TITANIA SLAG AND RESULTING PRODUCT

摘要

A method is disclosed including: (a) sizing a titania slag to a particle siz e range of from 75 microns to 850 microns; (b) oxidizing the sized titania sla g by contacting the sized titania slag with an oxygen containing gas at a temperature of at least 1000 ~C for a period of at least about 20 minutes su ch 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 ~C for a period of at least about 30 minutes such that the ferric state iron oxide is converted to a ferrous stat e; (d) leaching the reduced titania slag with mineral acid at a temperature of at least 125 ~C and under a pressure in excess of atmospheric pressure to yield an upgraded leached slag product and a leachate; and (e) washing and calcini ng the upgraded leached slag product by heating at a temperature in the range o f from 600 ~C to 800 ~C. The method provides advantages in that it can be used to produce a product with high TiO2 content that is suitable for the chlorid e process of TiO2 pigment production.