Mineral Processing: Production of Calcium Oxide from Nkalagu Limestone, Effect of Particle Size and Temperature

Abstract

Nkalagu limestone is a commercial raw material for cement production in south eastern Nigeria. The limestone was evaluated for quicklime production using oxidation kiln. The response of particles size was evaluated using five (5) particle size variations of 180µm, 355µm, 710µm, 850µm and 1,400µm. at temperatures(T) such that 800≥T≤1200 and ΔT = 100⁰C. The composition of the limestone was evaluated using the Atomic Absorption Spectroscopy (AAS), Simple Electron Microscope (SEM) and Fourier Transform Infra-Red spectroscopy (FTIR).   Results obtained confirmed the importance of surface area as conversion was higher same as loss on ignition with smaller particle sizes. SEM analysis reveals the product above 950⁰C as cement clinker and not CaO. Higher temperatures cause the thermal interaction of associated metallic oxide impurities which normally act as fluxes, decomposing the CaO to cement clinker. Above 900⁰C, product obtained had a higher bulk density, lower apparent porosity, cake-like and dark. To obtain CaO from Nkalagu Limestone, temperature in excess of 950⁰C is not advised.