Study on the influence degree of variables of gangue entrainment in low-rank coal flotation

In high-ash low-rank coal flotation, often the entrainment of kaolinite (a gangue mineral) seriously affects the quality of the concentrate. Entrainment in flotation is a complex process. Literature suggests that operating conditions have a significant impact on the degree of entrainment. In this study, a factorial batch flotation experiment, using a mixture of low-rank coal and pure kaolinite, was performed to investigate the effects of each factor and the interaction between two factors of these variables (including air rate, impeller speed, pulp density and frother dosage) on the entrainment of gangue mineral. The results show that both the air rate and impeller speed highly significantly affect the gangue entrainment and water recovery. Pulp density interacted with both the impeller speed and frother dosage, having a statistically significant effect on the degree of entrainment. Moreover, the interaction between pulp density and frother dosage had a significant impact on gangue entrainment recovery. Besides, water recovery was significantly influenced by the interaction between the air rate and frother dosage.