Mining Slurry Density Meter Selection Guide

Steps

1. Grinding and classification (cyclone feed / overflow / underflow)

   The highest-leverage density point in a concentrator, because classification efficiency sets how much energy the mill wastes on recirculating load. Cyclone feed density shifts the cut point: drifting up coarsens the cut at constant pressure, drifting down sends fines to the underflow to be reground. Recommended: PS7000 on a vertical rising section of the feed line. Underflow is the harshest position in the plant — very high solids, coarse and abrasive — and is where instruments chosen on accuracy alone fail earliest. Where the grind varies substantially with ore blend, prefer an impedance-based method over an attenuation-based one, since the latter's calibration is tied to the particle size distribution it was made on.

2. Flotation circuits

   Feed density affects residence time, reagent dosing per tonne and froth stability. The complication is that flotation deliberately introduces air, so an instrument must be judged on behaviour with entrained gas rather than on degassed accuracy. Recommended: PS7000, whose gas index output lets an operator separate a genuine solids increase from an aeration change — a distinction that matters because both push a naive density reading the same way, and misreading one as the other leads to reagent dosing in the wrong direction. Mount on a pump discharge line with adequate straight run, not immediately at the pump flange.

3. Heavy media separation (coal washing, DMS)

   Magnetite or ferrosilicon suspension density is the process variable, controlled tightly because separation density determines product yield and ash. The medium is dense, magnetic and abrasive. Recommended: PS7000 on the medium circulation line. Two points specific to this duty: the suspension is deliberately held at a target density so short-term repeatability matters more than absolute accuracy, and medium densification from ultrafines means the correlation between measured density and true separating density drifts over a shift — so periodic verification against a sample is part of the control scheme, not an admission of instrument weakness.

4. Hydrometallurgical leach and electrolyte

   Leach circuits combine chemical aggression with solids, and downstream electrolyte lines are clean but corrosive. These are two different measurement problems on the same flowsheet. For slurry-bearing leach lines, PS7000 with wetted materials confirmed against the actual liquor chemistry. For clean electrolyte or raffinate where concentration rather than solids is the variable, a sound-speed instrument such as the PS7020 resolves binary solutions far more finely — provided the solution is bubble-free and the concentration curve is monotonic across the working range. Confirm both at enquiry rather than at commissioning.

5. Tailings line and tailings dam

   Density governs deposition behaviour, water recovery, and with thickened or paste tailings whether the deposited material behaves as designed. Lines are large, long and abrasive, and the measurement often also serves as an early indicator of an upset upstream. Recommended: PS7000, which covers DN50–DN1000 with the sensor face flush with the bore, so nothing protrudes into a stream carrying coarse material. Interlock the reading to a pump-running signal: a stopped tailings line settles, and the resulting steady climb in indicated density is a stagnation artefact rather than a process event — a distinction worth building into the DCS rather than explaining to operators repeatedly.