Briquetting

To be fed into QMAG’s vertical shaft kilns, the magnesia must next be transformed from loose powder into compressed briquettes.

Using high-pressure roller presses, we press finely ground magnesia into a compact shape that is suitable for high-temperature sintering (or deadburning). The inherent properties of caustic calcined magnesia means we can briquette the material without adding any additional chemicals or binders.

There are two roller presses used to service each of QMAG’s three high-temperature vertical shaft kilns. Each press has a unique purpose. The first press, referred to as the ‘pre-dense press’, builds or replenishes the magnesia aggregate. The second, or ‘final press’, presses a mixture of magnesia powder and crushed pre-dense aggregate to produce a high-quality dense briquette ready for the kiln.

How do we make briquettes from powder? The principle of operation is quite simple. A certain ratio of finely ground magnesia and aggregate is mixed and then fed it into a column above the press. A pre-compacting screw removes some of the trapped air and forces the mixture from the column in between two counter-rotating rollers. These rollers are furnished with matching moulds that define the briquette shape. One roller is fixed and the other floating, as hydraulic rams apply pressure. We can continuously adjust the hydraulics to optimise the final briquette shape and properties.