Mineral exploration and development company Cornish Metals – focused on its South Crofty tin project in Cornwall, the UK – has commenced wet commissioning of its newly constructed mine water treatment plat (MWTP) at South Crofty.

The MWTP is designed to treat 25 000 m³/d of water pumped directly from South Crofty mine, and uses the proven high-density sludge (HDS) process technology to treat raw mine water and meet the company’s permitted standards for discharge into the nearby Red river.

The Cornish Metals project delivery team is being supported by the plant designer, equipment suppliers and contractors to fully test and commission every aspect of the process before commencing discharge to the Red river.

Commissioning and building of the high-density sludge bed is expected to take up to three weeks, with full dewatering of the mine anticipated to commence in October.

“The commencement of wet commissioning at the South Crofty MWTP is another exciting step towards the dewatering of South Crofty mine. Our project team, supported by a small army of dedicated local contractors, has worked extremely hard over the last 12 months to take the MWTP from a conceptual flowsheet design through to a fully constructed plant,” enthuses Cornish Metals CEO and director Richard Williams.

The MWTP uses the proven HDS water treatment technology to remove metals and other contaminants from the mine water.

The plant commissioning process takes place in several stages, the first of which is to fill all the reaction tanks with water and check for leaks.

The second stage is to electrically test each of the motor and control circuits, commission the reagent addition modules, supplied as package plants from third-party suppliers, and receive first fills of all reagents.

The last stage requires beginning running the plant and treating the water to allow a bed of thickened (high density) sludge to build up within the plant.

This sludge-building step is an essential part of the HDS process and is required to achieve the permitted water quality standards for discharge, states Cornish Metals.

During the sludge building process, the raw water from the mine is treated through the plant and then re-circulated back into the mine. Not until the plant is fully operational and performing to the required standards will any treated water be discharged to the Red River, adds Cornish Metals.