Coal Preparation » Fine Coal
Froth flotation is widely used to recover fine coal in the industry. Diesel is commonly used to increase coal hydrophobicity for efficient coal flotation. However, the oil based collector does not self ionize and does not dissolve readily in water with some mixing required to disperse the oily collectors into small droplets in water and immediately deliver them to coal particles in the flotation feed streams. The outcomes of this project reports the outcomes of applying ultrasonic emulsification to mix diesel collectors to produce fine droplets for coal flotation by full scale trials at a coal preparation plant (CPP) in Queensland.
An ultrasonic probe from Hielscher Ultrasound Technology, Germany was purchased to build a full scale ultrasonic unit that satisfied Australian safety standards and met the technical requirements of the CPP. The unit also consisted of an inline mixer to enhance the mixing that could be run with either the ultrasonic probe being turned on or off. The test work on the unit indicated that the optimised amplitude of the unit operating under the conditions of the proposed CPP was 90%, which could produce suitable diesel inwater emulsions for coal flotation at noise levels acceptable at the CPP.
A series of full scale trials to assess the performance of the emulsifier device and the effect of diesel emulsification on the coal flotation circuit were completed. On test workdays, the circuit was run in two sequential phases: the emulsifier unit was turned OFF and the circuit operated in a normal mode, and then the emulsifier unit was turned ON and the flotation circuit operated in a trial mode.
The results of the full scale tests are described in the report.