Effect of Ultrasonic Pre-treatment Time on Coal Flotation

ABSTRACT

Coating of fine particles by slime particles is inevitable in mechanized mining and transportation. These slime particles reduce the floatability and increase the ash content of clean coal. Ultrasonic pre-treatment method is used as a pre-treatment method to enhance the selectivity as well as kinetics of many minerals such as magnesite, complex sulphide ore, silica, coal, galena and zinc. However, the effect of ultrasonic pre-treatment time was not explored in literature and important for an energy intensive process. In the present investigation, ultrasonic pre-treatment time as well as reagent (collector and frother) dosages were optimized to achieve maximum clean coal yield. With ultrasonic pre-treatment, the clean coal yield increased for all the reagent dosages. Moreover, the clean coal yield obtained through ultrasonic pre-treatment is very close to the theoretical yield calculated from the release analysis. In the selectivity study, 8 unit increments in clean coal yield is observed with ultrasonic pre-treatment compared to the case without pre-treatment. Kinetic studies revealed that flotation rate increased from 0.026 to 0.049 s⁻¹ with ultrasonic pre-treatment. Improvement in clean coal yield with ultrasonic pre-treatment is validated with the characterization studies such as XRD, zeta potential, petrographic and FTIR analysis.

KEYWORDS:

• Coal
• ultrasonic pre-treatment
• XRD
• zeta potential
• FTIR
• petrographic analysis

Acknowledgments

Authors are thankful to Dr. Sanjay Chandra, Chief R&D and SS, Tata Steel Ltd for his support and valuable suggestions during this research work. Authors are also thankful to Dr. Rashmi Singh and S. N. Guru Lakshmi for providing petrographic and XRD analysis of coal samples respectively.