JOHANNESBURG (miningweekly.com) – Base-metals-miner Metorex has completed a plant shutdown at its Ruashi copper mine in the Democratic Republic of Congo, where a transformer electrical fault cut output from a solvent extraction-electrowinning (SX-EW) plant, in May.

On May 8, the transformer fault caused an internally generated voltage spike, which tripped both rectifiers in the copper tank house. Output from the plant was cut to 70% of capacity and a decision was later taken to replace the defective transformer.

Mining at Ruashi had continued unaffected during the six-day shutdown, which was completed on June 4.

Simultaneously, Metorex, which is led by CEO Terence Goodlace, had also replaced a semiautogenous grinding mill reline, which had previously been scheduled for July.

Full processing rates at the plant had now resumed, with the SX-EW plant tenors and electrowinning rates expected to reach the “desired levels” within six days.

However, the running of the plant at 70% of capacity and the shutdown would impact on its output in June.

The plant was expected to produce about 1 800 t of copper and 200 t of cobalt in June, compared with the 2 357 t of copper and 300 t of cobalt produced in May.

The plant had produced 3 100 t of copper and 262 t of cobalt in April.

Metorex noted that it had now implemented protection measures against the reoccurrence of such transformer faults.

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