9 July 2019: Australian ingenuity is being put to the test at one the world’s largest deposits of zinc, lead and silver.
Grade Engineering techniques is paying dividends for a South American mine, and its local workers. Once fully implemented is expected to generate an additional $451 million in profit for the mine and reduce its energy consumption.A successful full scale production trial of Australian-developed
Located in south-western Bolivian province of Nor Lípez, and owned by Sumitomo, Minera San Cristóbal (MSC) is the country’s largest mine. Operating since 2007, the mine produces around 1,500 metric tons of zinc-silver and lead-silver concentrates each day. To achieve this result MSC needs to move a daily average of 150,000 tons of rock – a mixture of some valuable minerals and a lot of costly waste.
An operation of this size generates a large amount of local employment and MSC states that its principal asset is its human resources. With a team of 1,400 workers the mine is a large and very important employer supporting the livelihoods of many people over the long term.
Searching for innovation
While the mining operation is vast, it in turn is part of something even bigger. MSC is a subsidiary of Sumitomo Corporation, one of Japan’s largest business consortiums, employing over 70,000 people and operating for more than 400 years.
While proud of their many years of history behind them, MSC and its parent company are at the forefront of technological adoption for their operations. Part of MSC’s vision is to ‘develop a model mining operation through safe operations, at low cost, with innovative technology...’
With this vision in mind they began searching for innovation that could unlock additional value at the Bolivian operation. For this innovation, and to help ensure continued employment for its valued workforce, Sumitomo and MSC looked to Australia for assistance.
Through its wholly-owned subsidiary Summit Mining International, Sumitomo is a participant of the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE). Based in Brisbane, Australia, CRC ORE works to minimise the impact of declining grades and radically improve the productivity, energy and water signatures of mining operations.
CRC ORE is jointly funded by Essential Participants - which include mining companies such as Sumitomo; Mining Equipment, Technology and Services (METS) companies; research organisations; and the Australian Government. The centre is a trusted, independent technology broker and facilitator, driving collaboration across all its activities.
One of CRC ORE’s key solutions developed for the mining industry is Grade Engineering. This solution deploys a range of waste rejection technologies that integrate with a suite of separation technologies relevant to ore specific characteristics. A deeper understanding of the orebody can be achieved, leading to the ability to exploit inherent ore deposit heterogeneity and variability.
For mining operations such as MSC, this is an innovative approach to the early separation of ore from waste material and minimises the impact of declining grades and productivity.
CRC ORE and MSC teams conducted site studies and analysis in 2017 to determine the level of opportunity available at the mine by deploying Grade Engineering, and a great deal of potential was evident.
Since late 2018 CRC ORE and Sumitomo have been working together on a full scale production trial of Grade Engineering using screening at MSC. A Metso Lokotrack ST2.8 mobile screening plant that can process up to 450 tons per hour was deployed on site to assist in providing a production scale testing capability.
The trial focused on upgrading mineralised waste from the pit to determine if Grade Engineering could efficiently produce a new economic stream of valuable material that could then be combined with Run of Mine feed through to the concentrator and produce a positive Net Smelter Return (NSR).
CRC ORE Chief Executive Officer Ben Adair said that that initial results of the trial are impressive and encouraging, with 66 percent of value now contained in just 25 percent of the Grade Engineered mass.
“So far, results show that by applying Grade Engineering to areas previously designated as ‘mineralised waste’, the value of Grade Engineered feed to the mill can be increased by over 2.5 times,” Dr Adair said.
“This has the potential to convert this waste material into high grade ore-feed with associated opportunity to increase metal production and reduce process power and water intensities.”
A 15-20 percent reduction in energy has been evident in the mine’s Semi-Autogenous Grinding (SAG) Mill when processing a combined Grade Engineered and direct Run-of-Mine (ROM) feed.
Long term benefits
The success of the Grade Engineering trial has led to consideration by Sumitomo to deploy Grade Engineering techniques to extend the life of the mine.
MSC Operations Director Dave King said the opportunity for MSC and the local community and principal asset of employees is huge.
“The big benefit of Grade Engineering is its potential ability to extend the life of the mine and add over $451 million in profit to its value,” Mr King said.
This means the mine can continue to generate work for its 1,400 employees.
CRC ORE participants and the wider mining industry are keenly watching how the MSC trial unfolds. To fulfil its goals of knowledge transfer and for its technology to directly benefit the local mining industry, CRC ORE has recently commenced similar production trials at Australian mining operations.