Consumers typically believe that a white clay tile is better than a red one, which may contain around 3% ferrous materials. Though this perception is based only on color and not on technical properties, tile manufacturers must achieve the color specification in order to compete effectively. To that end, one large tile clay manufacturer in Spain imported white clays from other countries (since Spanish clays are red), a practice that increased the cost of its materials.

To avoid having to raise its prices accordingly or accept a reduced profit, the manufacturer recently decided to try reducing the ferrous content of its clay slurry in order to limit the amount of white clay it would need to import. Industrial magnet supplier Master Magnets suggested its high-intensity magnetic filter (HIF) unit to remove as much of the ferrous material as possible from the mineralogical structure (from 3 to below 1.5%).

Filter Operation

The filter unit consists of a canister containing a stainless steel matrix, which is energized using a variable-intensity electro-magnetic coil around the outside. The matrix amplifies the magnetic field to produce points of very high magnetic intensity and gradient.

The slurry is fed into the bottom of the unit and passes up through the energized matrix, where contaminants are captured by the matrix and cleaned product passes out of the top of the separator to the next stage. When the matrix is saturated with magnetic particles, the inlet and outlet valves are closed, the electro-magnet switched off, and the matrix is flushed clean using the auto back-flush sequence, which allows the process to restart.

Testing and Production

To prove the efficiency and cost viability of the system, Master Magnets supplied a small demonstration unit that enabled the manufacturer to test the filter’s effectiveness. It allowed the manufacturer to experiment with different matrices, flow cycles and intensities to achieve the optimum separation figures.

After much testing, the go-ahead was given to purchase a production unit that fit the manufacturer’s application. Now operational in the Spanish manufacturer’s facility, the HIF unit improves the “whiteness” quality of the local red clays, thus allowing the manufacturer to add value while reducing costs and increasing the competitiveness of its products. 

For more information regarding magnetic filter units, contact Master Magnets Ltd. at (44) 1527-65858, fax (44) 1527-65868, e-mail info@mastermagnets.co.uk, or visit www.mastermagnets.com.