From our Ore to Your Door - Episode 16: Briquetting

To be fed into QMAG’s vertical shaft kilns, the magnesia must 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 ‘predense 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.

Making briquettes from powder is a fairly simple operation. We mix a ratio of finely ground magnesia and aggregate, and feed 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.