Dust collection in cement and aggregates

Capture in cement and aggregates concentrates on the points where material is stored, transferred and dispatched. Silo venting is the most characteristic: every time a tanker truck unloads pneumatically, the displaced air must leave filtered, and that unit is mounted on the silo itself. Added to this are bulk loading through telescopic chutes, bagging and palletizing, transfers between belts, screws and elevators, and ready-mix concrete plants, where filling the weigh batcher displaces cement-laden air. At the quarry face —crushing, screening and transport— the capture logic is that of any mineral operation, and is developed in the dust collection in mining article.

This is the central difference from any other sector. When cement dust takes up moisture, the cleaning pulse stops working: the material hardens on the filter medium and saturates it irreversibly, and in the hopper it forms bridges that block discharge even when the unit is capturing well. This is why the design defends against moisture on several fronts at once: filter media with a hydrophobic treatment or membrane, steep-walled hoppers with fluidizers or vibrators so the material does not bridge, and insulation or heat tracing to keep the unit above the dew point. Moisture is not an operational detail: it is the design variable.

Unlike grain, wood or fine metal dusts, cement and aggregate dust is not combustible: it needs no deflagration venting or explosion isolation in the ducts, measures that are mandatory in other sectors and are explained in the FAQ on whether a dust collector can explode. That does not make it harmless. Aggregates contain crystalline silica, whose respirable fraction causes silicosis with prolonged exposure, and cement is strongly alkaline and irritating to the airways, skin and eyes. The order of control is the usual one: capture at the source as the engineering control, and personal protection as the last barrier.

A cement extraction system can be correctly sized in airflow and in filtration area and still fail, if it did not account for the fact that the dust it captures sets. Moisture is the variable that defines the success of the installation: it defines the filter medium, the geometry of the hopper, the need for insulation and even the startup procedure. Defining it from the design stage is what keeps the collector from turning into a block of hardened material a few months into operation.