Located in the state of Para in Northern Brazil, is Vale’s Salobo copper mine, which went into production in mid-2012. This was the second greenfield copper project developed by the global miner in Brazil and has an estimated production of 518,000 metric tons of copper concentrate annually with the deposit itself estimated at over 1.18 billion tons. One key focus in the development of the Salobo mine was that of sustainable development. Nearly 98% of the water used at the mine site is slated for reuse and considerable investment was made in local infrastructure, health and education prior to the start of production. These investments were made with a view to the long term sustainable use of the mine, where production was scheduled to double in the coming years.
Challenge: Poor mine access roads increased tire failure and created bottlenecks
The Salobo mine operations span the production at the open pit mine face as well as the actual processing of the mined copper. The process setup involves raw ore passing through crushers, a roller press, grinding mills, cyclones and finally through flotation and filtration areas, where a final concentrate containing between 36% to 40 % of copper is produced. The copper concentrate is then transported by truck via a road from the mine site to Vale’s existing railroad terminal in Parauapebas, at which point it is transported by rail to the Ponta da Madeira Maritime Terminal in Maranhão.
The challenge facing Salobo revolved around the transportation of material through the mine access road. The poor condition of the road was causing tires on the large transport trucks to degrade quickly, leading to frequent and expensive tire changes. Regularly maintaining the tires on its fleet of transport trucks had begun to add up quickly in terms of unplanned costs and also slowed production down significantly.
Partnering with Metso: A rental agreement for mobile crushers
Metso was called in to look at possible solutions. With its knowledge of both mining and aggregates, Metso proposed the rental of mobile crushing plants (Metso’s wheel-mounted crusher models NW96 and NW200HPS, and a track-mounted Lokotrack® LT116™ jaw crushing plant) and feeders to produce the right grade of gravel to improve the condition of the 30 km internal road for heavy duty trucks. The key to the proposal was that not only would Metso provide the equipment to crush the gravel but that under a Life Cycle Services (LCS) agreement, Metso would maintain the supplied equipment and measure its success versus key performance indicators (KPI’s). This ensured that the proposed crusher solution was performing at optimal levels and delivering on its promised savings. The final signed agreement covered a two year period and went through a number of modifications in the early months, as gravel production increased from levels of 80,000 tons per month to well over 280,000 tons per month at Vale’s request. Metso placed a total of 50 experts on site to operate and maintain the mobile crushers which helped to keep the rented equipment producing a continuous stream of fresh high grade gravel to maintain the quality of the constructed access roads and unloading areas.
Side benefits: Reducing waste and increasing throughput
In addition, Salobo mine found a side benefit to having the high crushing capacity available on-site. The mine was able to use a portion of the crusher’s available capacity to test some excess waste materials that had accumulated at the site and separate out fines below 50mm. Once the smaller fines were removed, the left over 50mm and larger material was found to be of high enough grade to be rerouted through their process setup, giving a boost to production levels and reducing the levels of waste that needed to be disposed.
Increased productivity for trucks using the access road
With the contract in place since November 2013, the access road conditions leading out of the mine site have considerably improved. Tire life for the Vale big trucks has increased by over 50%, leading to significant savings on spare tires, and considerably less hours lost to maintenance. With fewer trucks stuck in service for required tire changes, production at the site has continued to grow. One main benefit of the Metso LCS contract with the mine was that the rental agreement allowed Vale Salobo to avoid making large capital expenditures to acquire its own crushing equipment. The rented Metso mobile crushers were flexible enough to meet the high and varying demand for gravel that was required. The rented equipment was backed by an LCS maintenance agreement, carried out by trained Metso service staff, which allowed the crushers to perform at their highest levels with little downtime. With Metso taking care of the operation and service of the mobile gravel crushers over the life of the contract, the mine was able to focus on its core business of producing copper.
*Metso Outotec was formed July 1, 2020 when Metso and Outotec merged into one company. This case study has been written prior to the merger under the old company name.