Production of nesquehonite, a magnesia precursor, by carbonation of synthetic mine waste water

Abstract

Nesquehonite (MgCO3.3H2O) is the preferred precursor to the high value product magnesia (MgO). Magnesia is used extensively in the mining industry for the hydrometallurgical recovery of metals and is usually obtained from processing naturally occurring minerals, brines or sea water. The mining industry produces large volumes of mine-impacted water in the form of brines and other wastes that could be used as a low-cost resource for producing the magnesia precursor. This work aimed to optimise the first phase of a potentially low-cost MgO production process, by carbonation of a synthetic solution simulating a Mg-rich liquid mine-waste. A three-factor, two-response, Box-Behnken response surface methodology experimental design (RSM) was used to determine the optima for the process on a synthetic sample. The optimal factor settings were identified and the tests established that the target product, nesquehonite, was preferentially formed in the majority of the experiments.