Dundee smelter burns clean

Dundee Precious Metals boasts a truly unique speciality 1200 °C copper smelter in Tsumeb, a town that has been built on copper and where the 24 hour lights of the smelter constantly remind everyone of why it is called the ‘Copper Town’. Dundee has taken its environmental responsibilities seriously investing some N$5 billion into smelter upgrades by 2020. Included is the development of its dedicated sulphuric acid plant and improvements in deployed emission capture technology that now accounts for 95% of all emissions. More recently earth moving equipment worth N$25 million has been added to upgrade the fleet at the plant.

Last year the plant was able to achieve production throughput of 190 000 tonnes and to increase its secondary sulphuric acid supply business to other mines including Rössing Uranium. The large plant also works with arsenic and although it has been able to lower arsenic exposure to below Namibians limits since 2015, it was in 2021 that it was able to beat Dundee’s own limit through continuous improvements to arsenic storage and hazardous waste disposal sites. Its state of the art vitrification pilot plant has shown success in converting the arsenic into a usable material, namely glass.

Dundee reported at the end of July that at its smelter the company completed a planned Ausmelt furnace maintenance shutdown and resumed full operations at the beginning of July. The 45-day maintenance shutdown included additional maintenance to the off-gas and baghouse systems, which are expected to improve operating performance of the smelter moving forward, the company said.

Net earnings were impacted by Tsumeb restructuring costs related to a comprehensive initiative directed at optimizing the cost structure of the smelter. On the positive side higher estimated metal recoveries were recorded at Tsumeb. Dundee says lower volumes of complex concentrate smelted at Tsumeb were partially offset by higher realized metal and sulphuric acid prices and higher estimated metal recoveries.

Complex concentrate smelted at Tsumeb during the second quarter of 2022 of 21 054 tonnes was 65% lower than the corresponding period in 2021 due primarily to the planned Ausmelt furnace maintenance shutdown, which was completed during the second quarter of 2022. Complex concentrate smelted at Tsumeb during the first six months of 2022 of 68 297 tonnes was 17% lower than the corresponding period in 2021, due primarily to unplanned downtime as a result of maintenance to the off-gas and baghouse systems.

Revenue in the second quarter of 2022 of US$134.5 million was US$40.2 million lower than the corresponding period in 2021 due primarily to the planned Ausmelt furnace maintenance shutdown at Tsumeb and lower volumes of metals sold, partially offset by higher estimated metal recoveries at Tsumeb as a result of extensive clean-up and measurement activities during the shutdown, resulting in higher estimated levels of material-in-circuit.

Cash cost per tonne of complex concentrate smelted in the second quarter of 2022 of US$973 was US$573 higher than the corresponding period in 2021, reflecting the fixed cost nature of the facility and the impact of lower volumes of complex concentrate smelted resulting from the maintenance shutdown. Cash cost per tonne of complex concentrate smelted in the first six months of 2022 were partially offset by higher by-product credits reflecting higher sulphuric acid prices.