Quartz sand Drying: Equipment Selection

Quartz sand is one of the most forgiving materials there is: sharp grained, hard, non hygroscopic and chemically stable, so there is a lot of freedom in the choice of machine. Large lines use a rotary drum, while small batches can run on flash or even batch equipment. Only three variables really matter: particle size distribution, moisture and energy cost per tonne of water. The size distribution decides two things. First abrasiveness: sand wears the flights and the drum wall far more than powder does, so the plate thickness has to follow the abrasion rating and wear liners may be needed. Second classification: coarse and fine sand travel differently through the same machine, so if the output has to be graded, screening has to be added at the tail end.

Quartz sand is one of the most forgiving materials there is: sharp grained, hard, non hygroscopic and chemically stable, so there is a lot of freedom in the choice of machine. Large lines use a rotary drum, while small batches can run on flash or even batch equipment. Only three variables really matter: particle size distribution, moisture and energy cost per tonne of water. The size distribution decides two things. First abrasiveness: sand wears the flights and the drum wall far more than powder does, so the plate thickness has to follow the abrasion rating and wear liners may be needed. Second classification: coarse and fine sand travel differently through the same machine, so if the output has to be graded, screening has to be added at the tail end, otherwise the fines come out first and the grades get mixed up. On moisture, quartz sand does not absorb water, but sand that has been stockpiled picks up clay and organics, so a pre-dewatering step before the heat is more economical than going straight to hot air. Sand has a high bulk density, so drum fill can be set higher than for powder and the throughput ceiling rises with it.

Does drying quartz sand grind it finer?
It does, and abrasion is the first thing to think about with sand. Sand wears the flights and the drum wall far more than powder does, so the plate thickness has to follow the abrasion rating and wear liners may be needed. Without that, throughput declines quietly as the wall thins.

Does quartz sand need screening after drying?
If the output has to be graded, yes. Coarse and fine sand travel differently through the same machine, and without screening the fines come out first and the grades get mixed up. The grading requirement has to be raised at selection so that screening can be added at the tail end.

Why pre-dewater sand when its moisture is not high?
Because stockpiled sand picks up clay and organics, and that water is not the sand's own. Putting it straight into a hot dryer means paying to dry the clay, expensively and without getting it fully dry. A pre-dewatering step before the heat makes the whole process cheaper.