Research work supports the efficient utilisation of ore
In research and development work, the focus was on production ramp-up and stabilisation. At the same time, studies were conducted into how metals from ore can increasingly be utilized. At the same time, exploring possibilities for further processing nickel-cobalt were continued.
Terrafame continued the development of bioleaching technology based on natural microbial activity in the ore. The company has unique expertise in the bioleaching of ores that contain pyrrhotite and know-how is further enhanced through a global collaboration network.
The ore material plays a major role for the leaching yield. During the year, ore and mineral models were utilised for developing the consistency of the feed used for bioleaching. In future, the modelling information will be utilised in operating the bioleaching process.
Increasingly efficient work in bioleaching and recovery
Bioleaching was studied on a laboratory and production scale, both with Terrafame’s own resources and with the help of partners. In the column leaching pilot, primary leaching was simulated and the bioleaching phenomena, such as microbial activity, were addressed. Furthermore, samples were drawn from the primary and secondary leaching areas through rotary drilling for specific laboratory examinations. Based on analysis results, a high volume of information was obtained for the development of bioleaching technology.
At the metals production plant, production-scale trial commenced in the summer to improve the precipitation properties of copper, and the first customer deliveries of copper were made during the year. Several different ways of enhancing the precipitations were also tested at the plant, with the aim of further improving the efficiency of nickel, cobalt and zinc recovery.
Targeting further processing of nickel-cobalt
The further processing of the current main product, nickel-cobalt sulphide, has been under examination at Terrafame since the start of the company’s operations. As part of this work, the pyrometallurgical alternative had already been identified as feasible, but the hydrometallurgical alternative turned out to be even more interesting.
In the pyrometallurgical alternative, the added value of the product would be increased in the roasting-smelting process, rendering the current nickel sulphide product a metallic nickel-ferro alloy suitable for stainless steel production. Plant-scale trial runs with partners were also successfully completed during the year.
In the hydrometallurgical alternative, nickel-cobalt sulphide would be further processed into chemicals used in the batteries of electric vehicles. During the year, the feasibility studies of battery chemicals production were continued.
In 2017, the company decided to focus on planning the production of battery grade chemicals.
The extraction process offers new opportunities for metals recovery
There is a nearly completed, solvent extraction technology-based uranium recovery plant at Terrafame’s industrial site. On top of uranium recovery, this plant could possibly be utilised in the recovery of rare earth elements (REE) from the main process solution. Based on this, a pilot-scale study was prepared, which received a permit from the Radiation and Nuclear Safety Authority in December.
The target of this study is to obtain information for the extraction process optimisation well before the possible commissioning of the plant. Additionally the plan is to identify recovery possibilities for rare earth elements.
Environmental R&D focus on landscaping
Terrafame managed to leave one third of its annual sulphate quota unused in 2017. In sulphate control, the smooth operation of the production process is of utmost importance, as well as the ability to precipitate sulphate to the bioleaching heaps. In 2017, the nano-filtering technique was tested for sulphate control in addition to the reverse osmosis technique currently in use.
Landscaping studies have been conducted at the secondary leaching area and at the gypsum ponds. In these studies, the aim is to identify environmentally-safe ways of shutting down areas of mining operations, as well as utilising local sealing materials for cover structures, where possible.
In the secondary leaching area, safe cover structures and landscaping have been studied and monitored for several years, and the work continues. The first phase of the studies at the gypsum pond area, which started with a trial operations permit in 2016, was finalised in autumn 2017. Further research plans will be specified based on the results obtained thus far.
Research activities into waste rock, not classified as ore, commenced in autumn 2017. The aim is to collect data for the development and inspection of base structures in waste rock areas and to investigate the possibilities of utilising the small concentrations of valuable substances in waste rock.
EU funding for further development of sulphate management
In 2017, Terrafame Group Ltd continued the implementation of the final stages of the Ariel project, focused on the development of water treatment technology, the construction of a longer-term research portfolio, and the monitoring and support of a number of Terrafame Ltd’s projects. The key results of Ariel were published at a water seminar organised by the University of Oulu in January 2018.
The project resulted in three conceptual options for further development of sulphate management at Terrafame’s mine. The solutions are based on 1) optimising the current process, 2) sulphate recycling, and 3) sulphate recovery as a new saleable product.
In 2017, Terrafame Group Ltd also acquired new research funding from the European Commission to develop the technologies conceptualised in Ariel into production scale.