Estimation and Addition of MgO Dose for Upgrading the Refractory Characteristics of Magnesite Ore Mining Wastes/By-products

High quantities of mining wastes (considered by-products) are stock-pilled in mines, and since zero-waste production is examined, as an important management concept for industrial activities (and also mines), it is of particular importance to find solutions for further exploitation of these wastes. Aiming to attain these targets, the optimum MgO addition in solid wastes from a magnesite mine was calculated, following a mass balance procedure, in order to maximize the formation of desirable olivine, after the application of thermal treatment and subsequently, to upgrade the refractoriness of products. The effect of caustic calcined magnesia (MgO) at 5, 10 and 15 wt%, was investigated by applying thermal treatments at 1300 degrees C or 1600 degrees C for 120, 240 or 360 min. The major properties in refractory products measured, are firing shrinkage, water absorption, apparent porosity, bulk density, mechanical strength and mineralogical characterization (by XRD). MgO addition increased desired olivine and eliminated undesirable pyroxenes, also inducing the formation of magnesio-ferrite and periclase. Firing shrinkage (%) decreased with increasing of MgO wt% for both temperatures and increased with increasing of treatment time. Water absorption (%) and apparent porosity (%) generally increased, due to hydration of magnesia. Bulk density values showed a decreasing trend, with increasing of MgO addition at 1300 degrees C, but an increasing trend at 1600 degrees C. Mechanical strength at 1600 degrees C and 240 min showed the best value, due to sintering process under these conditions. These results indicate that MgO addition can be considered a suitable procedure for upgrading the refractoriness of mining wastes.

Automated summary

The addition of MgO in mining wastes can enhance the refractoriness, promote the formation of desirable olivine, and eliminate undesirable minerals.