Abstract
The leaching of dolomite (carbonate mineral of calcium and magnesium) in mineral acid such as HNO3 is environmentally friendly with low energy demands, and it has high capacity of processing both in low and high grade ore. The study of the reaction kinetics and mechanism of reaction between dolomite and HNO3 was investigated. The energy-dispersive X-ray spectroscopy (EDS) result showed that Ikpeshi dolomite ore consists of calcium (20.09 %), magnesium (13.93 %) and oxygen (65.99 %). The effect of HNO3 concentration between 0.5 and 2.5 M on the fraction of dolomite was studied, while the reaction temperature was between 30 and 70 °C; the reaction time was 20 to 60 min. The results show the fraction of dolomite that reacted in HNO3 increased as the temperature and concentration increased. Reacted fraction of 0.995 was achieved at 50 min reaction time, acid concentration of 2.5 M, agitation speed of 250 revolution per minutes (rpm) and reaction temperature of 55 °C. The reaction mechanism followed product layer diffusion control of 1+2(1–x) – 3(1–x)2/3 = kt with 0.915 reaction order of hydrogen ion concentration and activation energy of 26.6 KJmol-1. Keywords: Activation energy; Product layer diffusion control; Reacted fraction; Reaction kinetic. DOI 10.35180/gse-2021-0048
Highlights
Extractive metallurgy often employs the leaching technics in the recovery of valuable components from solid mineral ores in aqueous solutions. This method is applied in hydrometallurgical processes due to its low negative environmental impact, low energy consumption, and its efficient recovery of low grade ore [1,2,3]
The energy-dispersive X-ray spectroscopy (EDS) results show that Ikpeshi dolomite ore consists of calcium (20.09 %), magnesium (13.93 %) and oxygen (65.99 %)
The reaction between dolomite and HNO3 shows that the temperature and concentration have positive effect on the fractions of dolomite that reacted
Summary
Extractive metallurgy often employs the leaching technics in the recovery of valuable components from solid mineral ores in aqueous solutions. This method is applied in hydrometallurgical processes due to its low negative environmental impact, low energy consumption, and its efficient recovery of low grade ore [1,2,3]. Pink dolomite sample was collected for this study from Ikpeshi mines in Edo State. Dolomite is one of the major sources of magnesium oxide (MgO) which is currently in high demand [9,10]. In order to understand the reaction mechanism between dolomite and mineral acids, such as hydrochloric acid (HCl), tetraoxosulphate (VI) acid (H2SO4) and trioxonitrate (V) acid (HNO3), the study of dissolution kinetics was considered
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