The Effects of Power Level on the Microwave Heating of Selected Chemicals and Minerals

Abstract

ABSTRACTThe effect of power level on the microwave heating characteristics of a variety of reagent-grade chemicals and minerals has been determined in a Bureau of Mines study. Heating rates of the powdered samples are presented for incident power ranging from 500 to 2,000 W at 2.45 GHz. The apparatus consisted of a WR 975 waveguide-applicator mounted to WR 284 waveguide sections and connected to a 3-kW power source. Tests were conducted in an alumina crucible enclosed in a fused-quartz beaker that was fitted with a Teflon lid to allow for a controlled inert atmosphere and thermocouple insertion. In general, heating rates increased as input power increased. Exceptions to this were some very high-lossy (microwave receptive) and very low-lossy materials that showed negligible changes with increased power. Microwave data collected should provide insight as to possible chemical and mineral processing applications as well as to assist in predictions of processing parameters.