Description

Tin ore (Cassiterite) is the second –easiest ore to mine. It is mined from tin veins. Cassiterite is a tin oxide mineral, SnO2. It is generally opaque but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem. Cassiterite has been the chief tin ore throughout ancient history and remains the most important source of tin today.

Most sources of cassiterite today are found in alluvial or placer deposits containing the resistant weathered grains.

Tin mineralisation in Nigeria is within the Younger Granites of Jos Plateau. They are two types: primary deposits found as disseminations in the biotite granite and pegmatities and placer deposits found among gravel pockets in both ancient and modern stream channels.

Most of the tin today is recovered from the placer formations by stripping and open pit mining. Ore grade is high (about 1.5 kgm-3) and beneficiation is by gravity or magnetic floatation or a combination of the two.

Associated gangue minerals include magnetite (Fe3O4), ilmenite (FeTiO3), Zircon (ZrSiO4), thorite (ThSiO4) and monazite (Le, La, Y, Th(PO4)). Gem quality beryl and semi-precious gem quality topaz are also associated with the cassiterite.

Tin metal is recovered from tin ore cassiterite (SnO2). Tin is one metal resource for which Nigeria ranks very high in supply to the world. Other notable producers of tin ore for world market are Malaya, Indonesia, Bolivia, Zaire (Democratic Republic of the Congo) and Thailand.

Before the oil boom, tin constituted the major mineral resource and important foreign exchange earner for the country. Cassiterite production in Nigeria remained at about 10,000 tonnes annually for several years from a reserve estimated at 250,000 tonnes. A production peak was attained during World War II when lots of tin, with accompanying tantalum and niobium were used by the colonial masters towards their war effort.

Production declined in the 70s to about 3,800 tonnes in 1979, less than 3,200 tonnes in 1981 and to an “all time” low of 1,700 tonnes in 1983. From 1988, the production level became even more “sorry”. Only 208 and 203 tonnes of this important commodity was produced in 1994 and 1995 respectively.

The market for tin ore especially the overseas market in China is large, expanding and sustainable because of the numerous uses of tin ore. Buyers usually would like to secure steady source of supply of these products.

The return on investment on the export of tin ore is estimated between 10%- 20%.