Preparation of potassium dichromate crystals from the chromite concentrate by microwave assisted leaching

Abstract

In the present investigation, the oxidizing roasting process of chromite with sodium carbonate to prepare potassium dichromate crystals was studied in the microwave field with air, by heating the chromite and sodium carbonate. The chromite and sodium carbonate heated separately at 1000 °C in the microwave oven (frequency: 2.45 GHz, power 1.5 kW) in order to study the microwave absorption properties. The dielectric constant and dielectric loss factor of the chromite and sodium carbonate examined. Then, chromite with sodium carbonate taken in (1:2) ratio and heated at 750 °C. Thus obtained samples were characterized using various techniques includes Powder-XRD (XRD), Scanning Electron Microscopy (SEM), and X-ray fluorescence (XRF). The XRD pattern reveals the existence of Fe3O4,Fe2O3,NaAlO2,and Na2CrO4. The iron and aluminum were leached out as Fe2O3 and Al(OH)3 respectively. The resulting sample treated with the KCl to prepare potassium dichromate crystals. Finally, potassium dichromate crystals formed.