PRODUCTION OF ACID SOLUBLE TITANIA

摘要

The specification discloses a method of making acid digestible titania. The method comprises the steps of: (1) adding a magnesium or manganese compound to a titaniferous mineral if the content of manganese and magnesium in the mineral is insufficient; (2) heating the mineral in the presence of a reductant for a sufficient length of time and at a sufficiently high temperature to permit the reduction of iron containing compounds to metallic iron and enable titania present to convert to an acid digestible form; (3) cooling the mineral; and (4) separating iron from the mineral by means of an aqueous aeration step. The titaniferous mineral contains insufficient magnesium and manganese if the following expression is not satisfied: 1.98a + 1.14b/d >/= 0.08 where a represents the percentage by weight of MgO contained in the mineral, (b) represents the percentage by weight fo MnO contained in the mineral; and (d) represents the percentage by weight of TiO2 contained in the mineral. The magnesium or manganese compound is either an oxide or a compound that is capable of converting to an oxide under reaction conditions. An aqueous aeration technique described in the specification involves the use of a sequesterant that is capable of sequestering iron from the mineral without significantly lowering the local pH while at the same time permitting the formation of an oxide of iron at a point away from the mineral. An example of such a sequesterant is citric acid.