Innovative Method of Material Treatmentby Microwave Energy

Abstract

In the submitted paper, the attention was devoted to the application of microwave energy in the treatment of various raw materials. The influence of microwave heating on the melting of andesite rocks is described. It was confirmed that the heating rate was fast. The melting of andesite samples after 10minutes of microwave heating at frequency of 2.45GHz and output900W was observed. The achieved temperature of melt was above 1200°C. The rate and selectivity of microwave heating are the most important advantages of microwave energy utilization in various processes, not only in mineral processing. Microwave energy has been applied also in many waste treatment processes. In this paper, microwave vitrification was used for the stabilisation of nickel leaching residue (NLR), which was used as model carriers of heavy metals (Cd, Pb) from wastewater treatment. The mixture of waste in different ratio (from 30-50% of NLR) with raw materials (andesite, dolomite, glass sand) was melted in a microwave furnace with frequency of 2.45GHz and output 1000W during 45minutes. After melting, the vitrified samples were similar to glass-ceramics. The TCLP test was carried out for testing chemical durability and a Vicker's indentation methodshowed the micro-hardness. The TCLP results showed good chemical durability of glass-ceramics. The measured values were underlimit. The micro-hardness was measured in two different zones (matrix and white zones), which were identifiedwith light microscopy. The results of the experiments proved that it is possible to stabilize the waste with content up to 50% NLR in short time by microwave energy.