Effects of Roasting on Some Properties of Titanium Concentrate from Iron Placers

Abstract

The purpose of this research is to concentrate titanium by magnetic separation of hematite from the low grade titanium concentrate making use of the relations between the magnetic properties and magnetizing or oxidizing roasting, and to study the reactivities of these high grade titanium concentrates with sulphuric acid in order to use them as raw materials in the pigment industry.
Following results were obtained.
1) Hematite mixed in the low grade concentrate was easily converted to magnetite by gas reduction. The optimum condition was to reduce it with less than 10% CO gas at 600°-700°C. After reduction titanium was enriched from 32% to 39% TiO₂in the non-magnetic portion by magnetic separation. The titanium recovery was 88% and the iron removal was 42-45%. The same results were obtained by fluiding reduction.
2) Ilmenite could become ferromagnetic substance by oxidizing roasting at 700°-750°C for half an hour and was concentrated in the magnetic portion. Titanium could be enriched to about the same content as in magnetizing roasting, but the titanium recovery and the iron removal were less than that.
3) On the contrary to the high reactivities of the titanium concentrate by magnetizing roasting with both 70% and 93% H₂SO₄, the reactivities of the one by oxidizing roasting were very low with both acids due to the convertion from ilmenite to Fe₂O₃·TiO₂ and rutile. From the iron separation and the reactivity with sulphuric acid, magnetizing roasting seems to be superior to oxidizing roasting.