Another record year in metals production
In 2017, Terrafame achieved annual all-time records in nickel and zinc production as well as several monthly and quarterly records. Altogether 20,864 tonnes of nickel and 47,205 tonnes of zinc were produced. Towards the end of the year, the first copper deliveries were also made.
The 2017 volumes of mining remained at the target level already reached in mid-2016. Ore containing 46,200 tonnes of nickel and 91,827 tonnes of zinc was mined and stacked to primary leaching. In late 2017 and early 2018, the southern end of the open pit was emptied of water, which in the future will offer better opportunities for extracting homogeneous ore and further improving cost-efficiency.
The mining equipment purchases made during the year correspond better to mining volumes. Another heavy wheel loader was introduced, and in transport, dumper trucks 11 and 12 were introduced in addition to the previous ten dumper trucks. The transport distance of waste rock was reduced significantly when a separate waste rock area was introduced closer to the pit. This will lower the internal transport costs of the mining site.
Cost-efficiency was improved in ore processing by developing magnetic removal of metal parts from the crushing circuit. Agglomeration of crushed ore was improved by more detailed quality control. This will also lay the ground for successful bioleaching.
A fourth surface miner was introduced to enhance operations in ore reclaiming in the primary leaching area. The utilisation rate of the conveyor line for transferring ore from the primary area to the secondary area was also significantly increased with new technical solutions.
Improvement in the cost-efficiency of the metals production
The primary leaching area was taken in full production use in May, when it was fully stacked with completely new ore. In the secondary leaching area, ore stacking progressed in the spring to block 3. During the year, aeration of primary leaching was also developed, which has a considerable impact on microbial activity and mineral oxidation, and thereby on the bioleaching recovery rate. On the whole, the leaching of metals at the heaps continued as expected.
During the year, cost-efficiency of Terrafame improved significantly, particularly with the growth in production at the metals production plant. The plant continued to use two production lines, which started during the previous year. The feeding of the process solution from bioleaching to the plant was developed so that metals could be recovered more efficiently than previously. A third pressure filter for zinc was also commissioned, which will enable a further increase in the production capacity of zinc. Additionally, feed equipment for sulphur dioxide was installed for the recovery of copper, and the first customer deliveries of copper were made towards the end of the year.
Altogether, Terrafame produced a record-breaking 20,864 tonnes of nickel and 47,205 tonnes of zinc during the year. Several quarterly and monthly production records were achieved in addition to the annual production records. A third hydrogen sulphide production line was also under construction at the industrial site which, once finished, will support increasing production and process reliability at the metals production plant.
Battery chemicals production planning started
The main product of Terrafame is nickel-cobalt sulphide precipitate. Its further processing possibilities have been under study at the company since the start of operations. During the year, two development alternatives were assessed, and in this work the production organisation also made its own contribution. The production possibilities of nickel and cobalt sulphates, used in the batteries of electric vehicles, were examined in addition to the production of metallic nickel-ferro alloy, suitable as a raw material feed for stainless steel.
Annual production records were achieved in both nickel and zinc.