Characterisation of particulate matter emissions from the Zimbabwe Mining and Smelting Company (ZIMASCO) Kwekwe Division (Zimbabwe): a ferrochrome smelter.

Abstract

Particulate matter emissions from stack number 2 of a major ferrochrome smelter, Zimbabwe Mining and Smelting Company (ZIMASCO) were characterized and the rates at which the elements Cr, Fe, Cu and Zn and total ferrochrome dust are emitted into the atmosphere were determined. The extent of soil contamination by the dust deposited around the smelter in the generally prevailing southeasterly wind direction around the smelter was carried out. The highest concentrations of Cr and Fe occurred in the fine particulates of sizes less than 59 microm whilst that of Cu and Zn occurred in the coarse particulates of size range 70-100 microm. The emission rates from stack 2 were; total ferrochrome particulates 62.17 kg h(-1), Cr 6.217 kg h(-1), Fe 2.423 kg h(-1), Zn 42 mg h(-1) and 6 mg h(-1) for Cu. Particulate matter was emitted at a rate of 289 mg m(-3) from stack number 2. This value exceeds the legal limit of 200 mg m(-3). Chromium and iron are the metals in the largest amounts. The particles that constitute the largest proportion of the dust were in the range of 58-107.5 microm. This is a characteristic feature of the particulate matter emissions from ZIMASCO. Soils in the downwind direction from the smelter were polluted with Cr up to a distance of about 700 m outward from the perimeter of the boundary of the smelter.