Лако-красочные материалы — производство

Ilmenite is found worldwide in primary massive ore deposits or as secondary alluvial deposits (sands) that contain heavy minerals. In the massive ores, the ilmenite is frequently associated with intermediary intrusions (Tellnes in Norway and Lake Allard in Canada). The concentrates obtained from these massive ores often have high iron contents in the form of segregated hematite or magnetite in the ilmenite. These reduce the TiO2 content of the concentrates (Table 2.5). Direct use of these ilmenites has decreased owing to their high iron content.

The enrichment of ilmenite in beach sand in existing or fossil coastlines is impor­tant for TiO2 production. The action of surf, currents, and/or wind results in con­centration of the ilmenite and other heavy minerals such as rutile, zircon, monazite, and other silicates in the dunes or beaches. This concentration process frequently leads to layering of the minerals. Attack by seawater and air over geological periods of time leads to corrosion of the ilmenite. Iron is removed from the ilmenite lattice, resulting in enrichment of the TiO2 in the remaining material. The lattice is stable with TiO2 content up to ca. 65%, but further removal of iron leads to the forma­tion of a submicroscopic mixture of minerals, which may include anatase, rutile, and amorphous phases. Mixtures with TiO2 contents as high as 90% are referred to as leu- coxene. Leucoxene is present in corroded ilmenite and in some deposits is recovered and treated separately. However, the quantities produced are small in comparison to those of ilmenite.

The concentrates obtained from ilmenite sand, being depleted in iron, are generally richer in TiO2 than those from the massive deposits. Other elements in these concen­trates include magnesium, manganese, and vanadium (present in the ilmenite) and aluminum, calcium, chromium, and silicon that originate from mineral intrusions.

More than 70% of the known ilmenite reserves of about 350 x106 t that can be used economically are in Australia, South Africa, Norway, Canada and India. On the basis of current production capacities, these countries could supply all demand for ca. 150 years. The countries with the largest outputs are Australia (sands), Canada (massive ore), and the Republic of South Africa (sands). Other producers are the United States (sands, Florida), India (sands, Quilon), the former Soviet Union (sands, massive ore), Sri Lanka (sands), and Brazil (rutilo e ilmenita do Brasil). In 2000 the production of ilmenite was ca. 1.6 x106 t of contained TiO2 [2.4].