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Simulation of mineral processing systems

By simulation of the whole or part of processes it is possible to make qualified estimates of the influence of different alterations in a concentration process. Often it is different what-if scenarios that come into question, and where it is costly to do time consuming tests on pilot or full scale. One simply wants to know the approx. influence a certain change will have. It may also be to do a cost-benefit analysis, where the proposed changes are ordered after their assumed influence and the cost for doing them.

Treaceability of raw materials in process streams

Traceability, defined as the ability to preserve and access the identity and attributes of a physical supply chain’s objects, gives the advantage to have a better control over the material through a process and allows for necessary adjustments. It can show “the current” values of different parameters and how much adjustment is needed to achieve the goals. The ability to trace a product backward throughout the process to locate the cause of a defect is therefore a vital ability for any industry. Traceability is much easier to use in batch processes than in continues processes. In food and pharmacy industries it is very common to use different traceability tools but within the mining industry, which usually operates continuous processes, traceability is an untouched area. In November 2006 LKAB started the new pelletization plant at Malmberget (MK3). The raw material is a mix from Kiruna and Malmberget ores, i.e. different ores having different Fe-content and levels of contaminants are treated in one process. Therefore traceability of the material throughout the process is one of the crucial factors for future product development and quality insurance.

Recycling of process water and influence of its chemistry on sulphide flotation

Recycling of flotation effluents through the ore processing plant is one of the ways of reducing both plant operating costs and industrial impact onto the local ecosystem. Such waters, named acid mine drainage (AMD), if discharged from sulfide flotation are highly saturated with calcium and sulfate species and have a high salinity. As minor species, they commonly contain reduced sulfur compounds (RSC) (sulfooxyanions with sulfur in the oxidation state below VI) which arise due to the use of sodium bisulfite as a flotation depressant, cations of ferrous and non-ferrous metals, frothing molecules, residual chemical reagents and products of their degradation. The key step towards developing scientific approaches of recycling of the tailing waters is elucidation of how, in what extent, and why the AMD components, taken signly or together, influence flotation of sulfides. The influence of these species at concentrations typical for tailing ponds on the adsorption-oxidation-desorption reactions of the collectors with the sulfides is being investigated in the project. The knowledge generated will assist to selectively regulate surface properties of sulfides in flotation

Flow and treatment of thick pulps

There is a global demand for effective use of energy and water in the mining industry, for example in the pumping of particle-water mixtures (slurries) in pipeline systems. When a low consumption of water per tonne of dry solids is reached, the energy requirement to overcome frictional resistance becomes sensitive to rheology related ("ketchup-like") properties and particle-particle interactions.

Wet low-intensity magnetic separators

A wet low-intensity magnetic separator consists of a drum, which in itself is not possible to magnetise (often made from stainless steel or reinforced plastics). The drum rotates fairly slowly, sunken into a tray, where a pulp with magnetic particles is pumped up from below. Inside the drum there is an adjustable array of permanent magnets.

Fine screening with electrically heated screen decks

Financed by LKAB/Minelco, Mineral Processing at LTU built a test station for a screen with heated decks. Screening of moist material <1 mm normally leads to a coating of fine material on the screen decks resulting in blinding. One way to counter-act the problem is to heat the decks by electricity. By heating the screen decks, the build-up of a wet surface coating on the metal wires is avoided. It is this wet covering that traps the fine material.

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Charge dynamics of autogenous mills

A mill is autogenous when the grinding media is part of the feed (i.e. lumps of the material to be comminuted are used). Some advantages with this setup are a large size reduction, a final product that will be free of contamination (no influence of foreign matter from grinding media) and only liner wear costs. The feed to a mill varies over time and the performance of an autogenous mill will to a large extent be dependent on the feed material properties, due to the use of the ore itself as grinding media. How an autogenous mill is affected by changes in feed material, mill speed or degree of filling is to be investigated in the project.