Fine Coal Cleaning

Application Description

The cleaning of ash from fine coal typically utilizes cyclones, spirals, and flotation as the major units in an operation. Flotation is ineffective when oxidized coal is encountered, leading to significant losses in fine coal. The Knelson Continuous Variable Discharge concentrator (CVD) is an enhanced gravity device where the separation mechanism is not affected by surface chemistry as in flotation. The CVD can potentially revolutionize fine coal washing circuits by eliminating the need for some or all of these unit operations.

Benefits

• The CVD can achieve effective ash and sulfur rejection in fine coal streams utilizing patented fluidized bed technology in an enhanced gravity centrifuge
• The CVD may replace cyclones, spirals, and flotation
• The CVD can increase fine coal yield and maintain coal specification in the fine fraction (-1mm)
• The CVD can handle high tonnage in a small footprint (up to 100 tonnes/hour in a single CVD)
• The CVD uses no reagents thereby minimizing environmental concerns
• The CVD can be accurately optimized to achieve desired separation results
• The CVD provides high operational availability at minimal cost

Application

Pilot scale lab testing was performed on a metallurgical coal by a third party laboratory. These results (above) are from a CVD operating on a minus 1 mm fine coal circuit feed. The results from this test program displayed high clean coal yields within the target ash range. Tests on minus 1 mm fine coal reduced the ash content from 20 to 12.6% with yields ranging from 70 - 86%. Production CVD's are expected to achieve superior results.