Method and apparatus for processing high-ash coal slurries by flotation, particularly for processing gas coal and open-burning coal which are difficult to float

The method of processing high-ash coal slurry by flotation of the slurry in flotation cells, comprising the steps of:

• preconditioning the slurry in a preconditioning tank with floatation agents and air injection, applying motion to the slurry, under pressure, for the disaggregation of the solids or floculent conglomerates due to floculent in the wash water, including agitating the slurry prior to feeding the same to the flotation cells;
• flowing the slurry through a plurality of cells in parallel of a flotation apparatus to separate the same into froth and tails;
• and
• controlling the dwell time of the slurry as it traverses the cells.

Apparatus for processing high-ash coal slurry, comprising:

• a preconditioning container including an agitator for agitating the slurry;
• control means connected to said container for introducing compressed air therein;
• said container being an autoclave-like pressure container and including level detection;
• means connected to said level detection means operable in response to the sensed level to control the additional flotation agents into said container;
• at least two rows of flotation cells for material separation arranged with said rows operating in parallel, each of said rows adapted to receive, as input material, a respective portion of the slurry;
• and
• each of said rows including an adjustable level control device for controlling dwell time of the slurry.