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Coal potential of Zimbabwe is not widely known but the country has proved and inferred reserves of around 30,000,000,000 metric tons and intends to become an exporter by 1985.

At present there is only one operating coal company in Zimbabwe, the Wankie Colliery Company Limited, but the interest in other coalfields is intensifying. Coal is seen as one of the country's resources with the greatest potential for production increases. The plan is to export 5,000,000 tons per year by 1985, increasing to 10,000,000 tons by 1990. Current exports are insignificant. Current production, from Wankie, is around 3,000,000 tons per year but, with the construction of a new power station, this is to be increased to 7,000,000 tons. Wankie currently operates two underground and three open pit mines.

Coal occurs in two distinct areas, in the Zambezi River basin in the northwest and the Sabi-Limpopo basins of the southeast. Both are Karoo sedimentary basins, the coal being of Permian and Triassic age. The potential of the Zambezi basin coal deposits is by far the greater of the two. Reserves in this area are in excess of 20,000,000,000 tons, and it is here that the bulk of the exploration activity is concentrated.

The Wankie coal concession area covers 110 square kilometers (68 square miles) and contains reserves in excess of 1,000,000,000 tons. The main seam averages 9 meters (30 feet) in thickness. The lower portion of this seam has excellent coking properties with an ash content as low as 5 to 7 percent. In 1978, reserves of coking coal were given as 478,000,000 tons with a further 700,000,000 tons of thermal coal in the upper part of the seam. Wankie's main seam extends eastwards at depth into the Wankie Western area. In 1960, reserves of 330,000,000 tons of in-situ reserves were estimated, containing 41,000,000 tons of extract-able coking coal. Investigations currently in progress indicate that the actual reserves may be significantly larger. In the same area, the Entuba field also shows an extension of the Wankie main seam. Here the seam is 11 meters (36 feet) thick and contains reserves of 50,000,000 tons, some of which could be mined as an open pit.

The Lubimbi area is subdivided into three coalfields, but the overall reserves, to a depth of 500 meters (1,640 feet), are estimated to be approximately 20,000,000,000 tons. At Lubimbi itself, potential open pit reserves amount to about 300,000,000 tons with a further 152,000,000 tons at Hankano.

Around Dahlia, the potential open pit reserves are 231,000,000 tons. Of the total coal, some 140,000,000 tons would float on a heavy medium with a specific gravity of 1.4. It has an ash content of 10 to 12 percent and could be classified as blend coking coal.

The Lubimbi area has the greatest immediate potential, being relatively close to the established infrastructure of Wankie and has, in fact, been earmarked as one of two areas that will be developed to produced 5,000,000 tons of export coal per year.

The other area earmarked for development for export coal, with the same , annual output as Lubimbi, is Lusulu, 80 kilometers (50 miles) to the northeast of Lubimbi. The coal here is highly volatile steam coal, covering an area of 770 square kilometers (297 square miles). Some 3,000,000,000 tons could be extracted by open pit methods, and almost half of this has an ash content of less than 40 percent.

The Sengwa coalfield, further to the northeast, has been under examination for some time by Rio Tinto Mining Zimbabwe Limited. The average seam thickness is 12 meters (39 feet) containing 200,000,000 tons that are suitable for open pit operations with an equal amount suitable for underground extraction. The coal is of metallurgical and steaming grades. If this coalfield were to be developed as a raw material source for ferrochrome smelting, an ammonia plant, and a methanol production plant, it could be an economic prospect. Such a project would cost in the region of $1,280,000,000 to set up. The cost would be high because, like most of the country's coal deposits, Sengwa is an isolated area and would require construction of the complete infrastructure necessary to industrialize the area.

The other fields of this area have, so far, received only cursory attention and the full potential of the northwest coalfields can therefore only be guessed at. At Lubu, Sebungu, and Marowa, for instance, the only exploration undertaken so far has been in the early part of this century when combined reserves, of high ash coal, were estimated to be almost 100,000,000 tons,. The seams of the Nebiri and Bari fields are known to be thin with high ash content.

Towards the center of the country, the Sessami and Kaonga coalfields have indicated reserves of approximately 1,000,000,000 tons of non-coking bituminous coal. The seam averages 4.9 meters (16 feet) thick with an ash content of 16 percent. However, it is not economic at present because the coal is more than 200 meters (656 feet) below the surface, overlain by weak rocks in an area with a strong influx of artesian water.

In the south, the Singwesi and Messabi areas, known collectively as the Tuli coalfield, contain very narrow seams with high ash contents. The seams are also very irregular, having been affected by faulting and dolerite intrusions, and are probably below current economic mining depth. The marginal part of the Massabi area could produce about 13,000,000 tons of good quality, low sulphur coking coal. The coal of the Bubye field is similarly irregular, with possible reserves of 24,000,000 tons of salable coking coal.

The three main areas that have been examined in the Sabi River valley are at Bendezi, Malilongwe, and Mkushwe. At the first, very thin lenticular deposits of highly volatile coal may have some potential. At Malilongwe there are two horizons, each varying from 1 to 3.5 meters (3.3 to 11.5 feet) in thickness, of bituminous high ash coal.

Total reserves have been estimated to be about 220,000,000 tons. The Mkushwe field is the largest in area but constitutes non-coking coal with a high ash content that is not amenable to beneficiation. Total reserves to the west of the Sabi River, in five blocks at depths less than 175 meters (575 feet) were computed at 308, 000, 000 tons. More recent investigations have confirmed Bendezi's potential and shown a sizable tonnage of very high grade coking coal.

Mining companies seek coal

A number of the country's established mining companies, notably some of the metal miners, have taken out Exclusive Prospecting Orders (EPOs) for coal. M.T.D. Mangula Management Services Limited has a large area in the De Noons field and two smaller areas to the southwest. Gold Fields Prospecting Limited has an area around the Bubye field in the south, while Union Carbide Management Services (Pvt.) Limited has an EPO for an area in each of the two coal basins, one near the Lusulu field and one west of Sabi. Other companies with EPOs in the west Sabi area include Southern Sphere Holdings Limited and Attica Mines (Pvt.) Limited, part of the Lonrho Investment Company Limited group. Prospecting Ventures Limited has a coal EPO for an area near the Lubimbi field. This particular EPO is for coal and uranium as are the M.T.D. and Southern Sphere EPO's.

Much coal exploration remains to be carried out, but the potential is certainly there. There is a desperate shortage of skilled personnel for exploration, mine development, and mine operation.

There is also a severe shortage of transport to move the coal from the mines. Exploration for both coking and thermal coals should show a marked increase over the next few years as holders of EPOs and special grants resume their investigations. Production for export and the manufacture of synthetic fuels is certain to develop during this decade but major development of infrastructure, the existing rail network, and the Mozambique ports will be required. ?

References:

Harrison, N. M., The Coal Resources of Zimbabwe, Geological Survey Department Report.

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