Moisture measurement- the key to product reconciliation

MA-500 installed on conveyor
MA-500 installed on conveyor

It is difficult to accurately reconcile tonnages without knowing the moisture content of the product and most mining operations battle with the mismatch of tonnes of coal dispatched compared to what has been delivered.

In most cases people tend to blame either belt scale inaccuracies or variations in product moisture. Callidan Instruments spokesman Rob Crutcher said typically belt scales are very accurate when maintained correctly.

“Accuracies of better than 0.25% in total weight are often quoted, however this measured mass is not a “dry tonnes” figure as it includes the moisture content of the product. Adverse environmental conditions such as extreme dry, humidity, or rainfall can significantly affect tonnage calculations.”

Mr Crutcher said many operations attempt to overcome these problems by using an extremely labour intensive process of sampling and laboratory analysis; however this is often impractical due to tonnage rates, top size of material, or cost.

Instead, many operations are beginning to use Callidan Instrument’s on-line microwave moisture analyser (MOISTSCAN) for the purpose of product reconciliation. MoistScan has been installed in coal, iron ore, nickel, alumina, fertiliser, copper, and other minerals industries throughout the world.

Callidan has designed and manufactured a reliable, low maintenance, on-line microwave moisture analyser, which provides rapid real-time results with user selectable time averages. The on-belt frame construction means the analyser is situated where it’s needed most, installation is easy and inexpensive.  Robust construction means low maintenance compared to other technologies.

Using a non-contact measurement technique avoids disrupting the production process. Once calibrated, operation is completely automatic so there is no costly sampling program and no operator intervention required. Callidan’s technology measures more than 80 per cent of the product on the conveyor belt.

The ready availability of moisture information allows proactive process control actions including:
• Metallurgical/process accounting,
• Diverting excessively moist material away from vulnerable downstream processes.
• Feedback control to a dryer circuit.
• Feed forward/back control to spray bars for dust control.
• Product net weight monitoring for quality control.
• Product moisture/dry mass contract compliance and
• Product reconciliation

The application of the MoistScan microwave technology has expanded significantly. As well as being useful for coal and other minerals it can also be applied to low density non-mineral products such as grain, pasta, wood chips and fertiliser.

Callidan recently received the Queensland Regional Export Award in the Information Communication Technology category. MoistScan analysers are installed in a diverse range of major mining and manufacturing operations in Australia, Korea, Brazil, China, USA, India, South Africa and New Caledonia.