The planning assumptions at a project to re-mine the stockpiles at a large iron ore mine were discovered to have been too optimistic, but Pilot Crushtec said it was able to deploy new equipment and adapt to the site and material conditions to improve its production.
The initial plan was to feed natural fines under 8mm in size from run-of-mine (ROM) stockpiles to the smelter. Later in the process, a mobile jaw crusher would be used, then mobile cone crushers with a sizing screen. However, the portion of fines in the stockpile was found to be much less than originally estimated, which reportedly put the whole project in jeopardy.
To rectify this error, the project needed to get a fully mobile three-stage crushing and screening plant as quickly as possible to meet the required tonnages. Pilot Crushtec, which is the local distributor of Metso Outotec equipment, was able to deploy the new equipment on site within a few weeks. This included a Metso Outotec Lokotrack LT106 mobile jaw crusher, two mobile cone crushers - a Metso Outotec Lokotrack LT200HP standard and a LT200HP short head - along with a Metso Outotec Lokotrack ST4.8 triple-deck mobile screen.
Another challenge at the project soon became apparent; the concentration of iron in the stockpiles turned out to be lower than anticipated. The natural fines were richer than originally estimated, however, which presented the opportunity of blending them with the lower-grade ore once it had been crushed. According to Pilot Crushtec, the Metso Outotec Lokotrack ST4.8 triple-deck mobile screen was key in this process, as its two-way split was able to provide a consistent supply of the iron-rich natural fines where required to be blended with the stockpiles.
The site was achieving 150t/h of the minus 8mm material, and Pilot Crushtec implemented steps to increase production further, targeting an improvement of 10-15%. Its strategy involved using Metso Outotec's Bruno simulation software along with some complex ‘tweaks' such as an optimised liner profile, a change in screening media and apertures, and splitting the process train.
Pilot Crushtec said these steps allowed the production target to be delivered, applying improved continuity to the process as well as making sure that the first two crushing stages were not inhibited by bottlenecks at the tertiary crushing and screening stage. Fuel and wear costs were also reduced, as the equipment in the first half of the process could produce the same amount of material in a shorter timeframe.
