The target level was reached as planned in production
Records were made in annual production levels for main products nickel and zinc. The production level set as a target at the time of launching the company in 2015 was achieved as planned in the third quarter. Cost-effectiveness continued to improve, especially through increased production.
Terrafame’s mining volumes have been at the target level since the summer of 2016. In the beginning, mining was mainly focused on the middle and north ends of the Kuusilampi open pit. At the beginning of 2018, the open pit’s south end was also taken into use after the area was emptied of the earlier extra waters. During the year, 46,334 tonnes of nickel and 97,663 tonnes of zinc were mined and transferred to bioleaching.
In the summer, the data on Terrafame’s mineral resources and ore reserves were updated in accordance with the JORC Code, which is the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves in the mining sector. According to an independent, external assessment, the mining concession’s measured, indicated and inferred mineral reserves amount to 1,525 million tonnes. This will enable the production and further processing of metals in Sotkamo for many decades.
Bioleaching functioned as expected
Terrafame’s production is based on a bioleaching technology in which metals are leached from ore using a microbial ore leaching process that takes several years. On the whole, the leaching of metals at the bioleaching heaps continued as expected.
Terrafame has been developing the bioleaching process with a long-term approach. In 2018, the aeration of primary bioleaching – which has a significant impact on mineral oxidation and thereby on the bioleaching recovery rate – was further developed. In the secondary area, the first full layer of ore was stacked for bioleaching in block 4 in early autumn.
The mining site’s rainwater and runoff waters are utilised in the production process. Over the course of the year, 2,9 million cubic metres of water were led to the bioleaching heaps to compensate for evaporation.
Third hydrogen sulphide line increases capacity of the metals production plant
Terrafame utilises hydrogen sulphide in the recovery of metals from the process solution. One major bottleneck in production was opened in the summer when the third hydrogen sulphide production line was completed and commissioned alongside two previous production lines. The new line will increase the metal production plant’s capacity and improve the operational reliability of its production process. The production capacity of all three lines is of similar magnitude.
The production volumes of the main products nickel and zinc increased significantly in 2018 compared to the previous year. In total, 27,377 tonnes of nickel (2017: 20,864) and 61,608 tonnes of zinc (2017: 47,205) were produced in 2018. The by-products – cobalt and copper – also continued to be produced throughout the year.
During the third quarter of 2018, production reached the level set at the time of beginning the company operations in 2015. This will enable achieving the annual production volumes of about 30,000 tonnes of nickel and about 64,000 tonnes of zinc.