Chemical and mineralogical analyses of Cement-Kiln- Dust (CKD) and its potential impact on the environment
Rotimi O. Oduola
Cement-kiln-dust (CKD), a by-product of cement production, is generated and disposed off in piles at different cement factory sites in Nigeria, raising environmental concerns. About 25% of every tonne of raw materials fed into the kiln during cement production results in CKD waste. Dust recycling has been employed in the past by many cement plants in the country to curtail their environmental effects but despite this, large quantities of CKD are still being produced. The wastes are suspended in air as particulates during dry weather causing air pollution, or deposited on plants and roofs of buildings. The dusts are also washed into surface and groundwater during rains thereby polluting the water sources particularly around the factories. An intensive study is currently being conducted to find a productive use for this waste in civil engineering construction and this paper presents the results of chemical and mineralogical analyses of CKD with a view of determining their impact on the environment. Tests conducted on CKD samples collected from Lafarge Cement Plant Shagamu, Nigeria were chemical analysis using X-ray Flourescence (XRF), microstructural analysis using Scanning Electron Microscopy (SEM) and mineralogical analysis using X-ray Diffraction (XRD). From these analyses, results showed that the CKD contained lime, CaO, as the predominating elemental oxide among the major oxides present with a value of 68.44% while silica oxide, aluminium oxide and ferric oxide were 12.80%, 5.90% and 4.01% respectively. The SEM analysis showed the presence of fine and dense crystalline microstructure of mineral particles. XRD results showed that minerals present were antigorite, mordenite, chrysolite, sanidine, etc. The high lime content indicate that soil, surface and groundwater sources will have a high pH values and which may have both short-term and long-term implications on both plants and animals in the affected areas, however, further studies shall reveal the implications of these on the environment.
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