Aluminum Leaching from Calcined Coal Waste Using Hydrochloric Acid Solution

Abstract

Coal waste is the largest industrial solid waste generated from coal preparation plants during the processing and cleaning of coal for electric power generation. Aluminum oxide (Al₂O₃, 16–36%), silicon dioxide (SiO₂, 45–58%), and carbon (4–25%) account for more than 90% of the coal waste. In this paper the results of aluminum leaching from calcined coal waste are reported. Techniques including XRD, SEM, and FTIR were used to characterize the coal waste before and after calcination. Three additives were evaluated during the calcination process to improve the extraction of Al₂O₃ by hydrochloric acid dissolution. The results from the leaching experiments show that coal waste is activated after calcination at a temperature between 650°C and 750°C. With addition of sodium fluoride effective aluminum dissolution of 90% was achieved under certain conditions. The extent of leaching was found to be 20% higher than that achieved without sodium fluoride addition.

Keywords:

• aluminum oxide
• calcined activation
• coal gangue
• sodium fluoride

ACKNOWLEDGMENTS

The financial support from the National High Technology Research Development Program of China (863 Program, 2011AA06A103) is greatly appreciated. The authors also thank the Luan Coal Mining Group Corporation Ltd for supplying the material. Thanks are extended to Tsinghua University for helping with the analyses.

Notes

S = 0.21947 Press = *.

R-Sq = 99.96% R-Sq(pred) = *% R-Sq(adj) = 99.88%.