Zimbabwe’s Circle Cement Limited is scaling up its investment at its Mbubu limestone quarry about 200km east of Harare to improve cement quality and expand its base for limestone reserves.
Circle Cement managing director Mr Isiah Bingwa told local press that his company had so far invested US$420,000 for road construction and US$540,000 on a diamond drilling survey to find the extent of the limestone reserves at the quarry in the Uzumba-Maramba-Pfungwe district.
"We have constructed a gravel road to the site. We are also drilling holes to establish the extent of the (limestone) deposit," he said during a ceremony to launch Green Ribbon environmental week at the Manresa cement plant.
"Preliminary results show that there are reasonable amounts of limestone at the Mbubu quarry in UMP. Indications, yes, point to good limestone reserves at the site."
Mr Bingwa said the Mbubu quarry will become an important source of high-grade limestone which will be blended with limestone from one of the country’s oldest limestone quarry – Sternblick – to make high-grade cement.
Sternblick pit was opened in 1954 and its limestone ore concentration is falling.
"The reserve here is tending to be low in terms of limestone concentration. We will need the Mbubu reserves to balance the chemical composition of the clinker," Mr Bingwa said.
"We need high iron, silica and alumina content to produce high-quality cement."
Circle Cement bought Mbubu limestone deposits from Anglo-American Corporation for an undisclosed amount around 2004.
A preliminary survey done by Anglo-American Corporation estimated the deposits at between 40Mt and 50Mt.
Full-scale exploration is underway at the Mbubu site. Mr Bingwa said even if abundant deposits were found, Circle Cement would most probably exploit only 20 per cent of the limestone ore which would be processed at the Manresa plant.
Circle Cement is now operating at full capacity from a low of 60 per cent in 2002.
The Manresa plant produces about 450 000t of cement a year and when output from other two plants is added, Circle Cement has the capacity to produce between 1.3Mt and 1.4Mta of cement.
The company has three cement plants in the country. It runs several subsidiaries which manufacture painting and construction materials.
Circle Cement exports clinker worth US$6m a year to Malawi.
Mozambique and South Africa have made enquiries. Domestic demand for cement is depressed and is currently estimated at 50 per cent.
Larfage has a 76 per cent controlling stake while the remainder is held by individuals.