Evaluation of Quartz Reduction by Coal Cleaning for Thermal Utilization of an Indian Coal

ABSTRACT

In Indian coals, quartz is abundantly found and its proportion usually varies from 5–20% by weight. Beneficiation of high-ash thermal coals of India has become the prerequisite for improving the overall economics and efficiency of power generation. A detailed survey of literature reveals that no systematic work has been done of beneficiated coal for Indian coals with respect to quartz, as also for correlation with abrasion. Therefore, to understand this effect different sizes of crushed coal were subjected to float-sink treatment at specific gravities in the range of 1.30– 1.80. This study highlights the systematic method of measuring crystalline silica (α-quartz) in bulk coal samples using NIST-SRM 1878a as a calibration standard with more accuracy by FT-IR as well as distribution of quartz in various screen sizes, float-and-sink fractions, for both the feed and clean coal. The results show that there is a linear relationship between ash % and quartz % with respect to specific gravity for all screen sizes. Characterization of the feed and clean coal with respect to quartz was also done using XRD, SEM, and XRF spectroscopic techniques to evaluate the reduction behavior of quartz during the coal-cleaning process.

KEYWORDS:

• Quartz
• coal cleaning
• float-sink
• abrasion index
• XRD-XRF-SEM IR techniques

Acknowledgments

The authors express their gratitude to the director, CSIR- CIMFR-Central Institute of Mining and Fuel Research, Dhanbad, for providing facilities required in the present study. They are grateful to Dr. P. S. M. Tripathy for valuable suggestions for improvement of this article.