Kinetic Study of Reaction between Dolomite Ore and Trioxonitrate (V) Acid (HNO3)

Abstract

The leaching of dolomite (carbonate mineral of calcium and magnesium) in mineral acid such as HNO3is environmentally friendly withlow energy demands,and it has high capacity of processing both in low and high grade ore. The study ofthe reaction kinetics and mechanism of reaction between dolomite and HNO3 was investigated. The energy-dispersive X-rayspectroscopy (EDS) result showedthatIkpeshidolomite ore consistsof calcium (20.09 %), magnesium (13.93 %) and oxygen (65.99 %). The effect of HNO3concentration between 0.5 and2.5 M on the fraction of dolomite was studied,while the reaction temperature was between30 and70 °C;the reaction time was20 to 60min. Theresults show the fraction of dolomite that reacted in HNO3 increased asthe temperature and concentration increased. Reacted fraction of 0.995was achieved at 50 minreaction time, acid concentration of 2.5M, 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= ktwith 0.915 reaction order ofhydrogen ion concentration and activation energy of 26.6 KJmol-1.