A Hunter Valley based ­company, TUNRA Clean Coal, has developed a new online device that measures the resid­ual frothing propensity of a feed stream.
The Residual Frothing Propensity Detector has been developed to be installed on the clarified water system of a pro­cessing plant and convey to the opera­tors the level of frother contamination within that water system.
When there is residual frother in the clarified water the pro­pensity for bub­bles to form increases.
The major problems occur within the feed sumps to the dense medium cyclones, which require high vertical velocities to keep the coal from floating.
When residual frother is present it gen­erates froth within the feed sumps which can cause the feed pumps to the dense medium cyclones to cavitate causing the plant to froth out and be shut down.
The RFPD works by maintaining a set of fixed conditions while measuring the airflow and vacuum.
The RFPD is then able to measure the propensity for bubbles to form at these set conditions for clean water. The device is then calibrated to the specific frother being used in the coal or minerals processing plant.
The changes recorded by the RFPD in the vacuum and airflow, are then directly related to the concentration of frother within the feed source.
The RFPD is able to then transmit this data to the plants communication system and provide real time informa­tion to an operator indicating the con­centration of residual frother in the clar­ified water being monitored.
The RFPD is calibrated to frother, how­ever measuring the propensity to form bub­bles also takes into account effects caused by salt, which when in higher amounts can also cause a plant to froth out.
The plant operator will benefit by being able to dose the frother at an opti­mum level, increasing yields in the fine coal circuit.
Presently much flotation is done at relatively low levels of frother, meaning a loss of saleable coal.  

Geoff Curnow
TUNRA Clean Coal
02 6574 7081
tunracleancoal@harboursat.com.au