A novel application of waste cement clinker dust in the extraction of potash from mica scraps

Abstract

The prospect of using cement clinker dust (CKD) as an additive in recovering potash values from an Indian mica scrap sample, containing 7.64% potash, is explored. It is found that the clinker dust, mostly treated as solid waste in the cement industry, can act as the calcium source in the chloridizing roasting of mica. The experiments have been carried out as per the central composite design. Factors such as the dosage of mica, clinker dust, NaCl along with roasting parameters such as temperature and time have been optimized. At a roasting temperature of 950 °C, time of 40 min, and the dosages of clinker dust and NaCl to the tune of 70–75% of the mica weight, the process is found to recover 99% of the potash values. With lowered process conditions such as a temperature of 900 °C and time of 10 min, it is possible to recover 89% of the potash values with clinker dust and NaCl each at a dosage of 50% of the weight of mica. Characterization studies like X-ray diffraction and field-emission scanning electron microscopy coupled with energy dispersive spectroscopy have been carried out to identify the different phases of the feed and processed products, and thereby propose the reaction sequence.