Although there are more than ten known chromium minerals, only one is a source of commercial importance. This mineral is known as chromite and has the theoretical composition FeCr2O4 containing 68 % of chromic oxide (Cr2O3), in which the proportions of Mg2+, Fe2+ and Cr3+, Al3+, Fe3+ may vary considerably.
The main product generated by chromite is ferrochrome, a major player in the steel industry. In particular the stainless steel industry uses more than 90 % of the world’s chromite output. The mining and steel industries must assess the quality of the chromite ore to optimize the grade of their stainless steel production. As a result, the chemical analyses of the chromite ore as well as its final and waste products are mandatory. Metal analysis traditionally uses AA or ICP-OES to measure the metal contents in the ores and industrial products. However, the traditional dissolution method for chromite and ferrochrome is a multi-step, multi-acid digestion which requires the use of HNO3, HF and HClO4 and can take between 1 to 3 hours.
Knowing the risks associated with the use of HF and HClO4, many laboratories look for alternative methods to obtain full dissolution of their samples while optimizing their uptime and productivity. As will be demonstrated, sodium peroxide fusions are a quick, safe and efficient alternative for the dissolution of these specific samples.