Abstract
High-grade synthetic rutile has been produced in the laboratory from domestic ilmenite concentrates by a new carbonyl process. The ilmenite was first reduced to convert the iron oxides to metal and then treated at temperatures over 100 deg c in high-pressure carbon monoxide (co) to convert the iron to the pentacarbonyl. Rapid carbonylation was achieved in the presence of small quantities of selected promoters. Maximum iron removal occurred at temperatures between 110 deg and 130 deg c at CO pressures from 1,000 to 1,400 psig. Iron pentacarbonyl appeared as liquid and vapor in the reactor and could be removed by gravity flow and vapor transport. More than 90 pct of the iron was extracted in 2-hr experiments at pressures of 1,000 psig and above. The tio2 product is porous owing to the removal of the iron, has the rutile crystal structure, and is suitable for chlorination. Waste disposal problems associated with the process would be minimal because the iron pentacarbonyl can be decomposed to produce iron powder or pellets for sale and CO for recycling.
