Low flow meter for nickel processing

Paul Boughton

Flowmeter specialist Litre Meter has shipped four customised LF15 VFF positive displacement flowmeters to New Caledonia, a French territory in the South Pacific off Australia, for use in process applications at a large nickel mining operation in the region.

The rotary piston flowmeters are used to measure the flow of chemicals for three discrete applications - sodium hypochlorite based biocide, a polyacrylamide dispersant and a corrosion inhibitor comprising a mix of zinc sulphate with maleic acid copolymer. The meters are pressure rated to 20bar. Unusually, two of them are constructed from titanium for the hypochlorite measurement.

The VFF meters are fitted to pump systems at the Koniambo nickel mining operation in New Caledonia.

The chemicals are injected into pipelines via the skid installed at the mine head to prevent the build-up of sludge and corrosion in the equipment which delivers the leaching fluids that extract the ore.

Measurement of the chemical injection rate is critical because blockages caused by a build up of oxidised material, scale or emulsified sludge can result in a shutdown and unintended personal and environmental safety issues, including the risk of pollution and explosion.

Blocked pipes may have to be taken offline to remove the blockage, causing costly loss of production. Litre Meter meters assist in maintaining operational assurance and reducing production costs by measuring the flow of chemicals needed to prevent corrosion and sludge formation. Chemicals are expensive which means that their use needs to be carefully monitored.

Accurate chemical injection monitoring is provided by the LF15 Litre Meter flow meters via a central control room.

The VFF LF15 flowmeter is suitable for measuring liquids at pressure ratings up to 4,000 bar (15,000 psi) and flow rates of 0 to 45 l/hr. It covers a viscosity range from under 0.8 to above 100,000 centistokes (cSt).

As standard, the meters are constructed of 316 stainless steel with titanium rotors. Two of the meters supplied to Koniambo were customised using titanium bodies in order to deal with the aggressive nature of the chemicals being used. The low flow capability of the meters has been improved by coating the pressure balance chambers and titanium rotors using physical vapour deposition (PVD) to reduce friction. The additional hardness provided by the PVD coating also improves wear resistance.

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