VANCOUVER (miningweekly.com) – Canadian miner Nevsun Resources has reported strong zinc output at its flagship Bisha mine, in Eritrea, hitting the top end of its 2017 guidance.

However, the news late on Wednesday was not enough to bolster investor sentiment on Thursday, as the company’s struggling copper output again disappointed the market with a miss on the lower end of the Vancouver-based company’s guidance. This sent the company’s TSX-listed stock down by as much as 5.34% to C$3.01 apiece.

During the past year, Nevsun produced 207.8-million pounds of zinc in zinc concentrate, coming in at the top end of its guidance of 190-million pounds to 210-million pounds of zinc. Copper production totalled 18-million pounds of red metal, compared with 2017 guidance of between 20-million to 30-million pounds.

For the three months ended December, Nevsun produced 55.1-million pounds of zinc, boosted by improving zinc recoveries during the second half of the year.

Nevsun advised that copper production in the fourth quarter was, as in the prior quarter, impacted by processing of stockpiled ore containing only zinc mineralisation, resulting in zero copper recoveries. The company processed the zinc-only boundary ore owing to a shortage of fresh primary ore in the Bisha Main pit during the second half of the year.

During the quarter, stripping levels increased to 5.3-million tonnes, from an average of 3.7-million tonnes a quarter over the previous three quarters. Waste stripping benefited from shorter haulage distances owing to in-pit waste dumping and from improved heavy mining equipment availability, because of employing an experienced third-party to overseeing fleet maintenance.

Mining benches, walls and faces in the Bisha main pit continued to be re-established to improve mining efficiency, with the goal accessing 100% fresh primary ore in 2018.

Meanwhile, the majority of new mining equipment bought during the fourth quarter will arrive on site during the first half of 2018. This equipment will replace ageing equipment on site to improve mechanical availabilities which, along with continued in-pit dumping of waste, will assist the mine in meeting its planned material movement for the upcoming year.

Nevsun expects to release its 2018 outlook and production guidance later in January.