An assessment of the calcination characteristics of the mfamosing limestone for quality commercial lime production.

Abstract

High quality lime is an essential raw material for many industries (such as steel, chemical, sugar etc) all over the world. In Nigeria most of the demand for this chemical product is met through importation. The Cretaceous Albian carbonate of the Calabar Flank - the Mfamosing limestone is hereby assessed for production of quality lime. The limestone is fine-grained, fossiliferous and composed dominantly of algal boundstone and lenses of oolitic wackestone and packstone. X-ray fluorescence (XRF) and X-ray diffraction (XRD) were employed in its chemical and mineralogical investigations. The suitability of the limestone for commercial lime production depends on its chemical purity (66.69% CaCO3) and calcination process. Consequently the limestone was calcined through a range of temperature (9500C, 10000C, 10500C and 11000C) for varied retention times (60, 90, 120 minutes) and the burning characteristics were determined. Thus technological tests such as loss on ignition of lime, decrepitation, mechanical strength, and reactivity with water (slaking test) were carried out. The 10500C/90 minutes calcine yielded best quality product - a compact, soft burned, porous and highly reactive lime (>400C rise) desired by lime manufacturers. The Mfamosing limestone is highly recommended for commercial lime production.

KEY WORDS: Lime, calcinations, soft-burned, purity, commercial