Every iron ore producer in the world has been under pressure over the past several years, with the benchmark price having dropped as low as US$37/ton in late 2015 after reaching an all-time high of just over US$190/ton in February 2011. South Africa’s leading producer, Kumba, has responded by introducing a series of state-of-the-art – but proven – technologies which have boosted productivity and driven down operating costs, as Modern Mining’s Arthur Tassell was able to see on a recent visit (as part of a media group) to Kumba’s flagship operation, Sishen, in the Northern Cape.

The impact of the new technologies (as well as a relatively modest revival in the iron ore price) resulted in Kumba being able to post exceptional results for its 2017 financial year, as its CEO, Themba Mkhwanazi, pointed out to journalists during the media visit. He said Kumba had been in survival mode two years ago but had rebounded to the extent that its shares ranked as the best performing stock on the JSE in 2017.

Shishen Plant

A view of the plant complex at Kumba's Sishen mine (photo: Arthur Tassell).

Mkhwanazi attributed the turnaround at Kumba to a new operating model and a restructuring which involved “doing the right work at the right time in the right way” and said the company – which also maintained a highly impressive safety record during 2017 – was now able to operate profitably “even when the commodity cycle turns against us.” He added that “the Kumba you will see in three to five years’ time will be a very different Kumba than the one you see today.”

Sishen, of course, is one of the largest open-pit operations in the world, moving well over 200 Mt of material a year. The mine was commissioned in 1953 and the single pit from which the ore is extracted is now – after decades of mining – 14 km long from north to south, with an average width of 2,5 km and a maximum width of 5 km. The current depth is 275 m but it will go down to 400 m by the end of the mine’s life. So vast, in fact, is the pit that it has been divided into two separate operations, the North and South mines, each with its own manager.

The single biggest activity at Sishen – which, in 2017, produced 31 Mt of iron ore for export through Saldanha Bay – is the loading and hauling of the waste and ore. Briefing the media party visiting the mine on the scale of this operation, Sishen’s GM, Mapikwa Mobwano, said it accounted for around 65 % of costs and required a huge mining fleet. This consists of 13 primary shovels, the biggest being three 109‑tonne P&H 4100 XPCs (each capable of picking up 109 tonnes in a single scoop), and 98 trucks, 36 of them 327-tonne capacity Komatsu 960Es and the balance Komatsu 860Es, each with a payload of 254 tonnes.

The trucking fleet is smaller than it was at the end of 2015, when it numbered 136 units. As Mobwano explained, a programme of load and haul efficiency improvements – involving, among other things, a redesign of the pit, a revamped shift system and improved blasting – has seen a 62 % improvement in productivity, allowing the smaller number of machines on site to handle more material. Detailing the gains, he said the P&H 4100 shovels were handling twice as much material per day per shovel while the Komatsu 960Es were transporting 1,6 times as much material per day per truck. Shift change duration had been reduced by 88 % while the DOH (Direct Operating Hours) of the trucks had increased by five hours per day.

Reviewing the processing operation, Mobwano said Sishen operated three plants: the DMS plant, commissioned in 1975, which treats the mine’s high Fe content ore; the jig plant, which came on line in 2007 and is designed to process lower grade reserves; and the modular plant, constructed in 2014, which processes the jig discard. Typically, the DMS plant, which has a yield of between 78 and 86 %, accounts for 18 to 18,5 Mt/a of Sishen’s final product while the jig and modular plants – delivering yields of between 55 and 65 % – are responsible for a further 11 to 11,5 Mt/a. A second modular plant involving a capex of R360 million is currently under construction and will be commissioned in the fourth quarter of this year.

The modular plants are based on Ultra High Density Media Separation (UHDMS) technology, which Kumba and Exxaro (one of Kumba’s shareholders) have played an important role in pioneering. Kumba believes that full implementation of UHDMS – which allows low grade material to be economically beneficiated – has the potential to increase Sishen’s saleable production by up to 2 Mt/a. One of the resources that could be exploited is the stockpiles of marginal material that have been built up at Sishen over the years.

Kumba is currently busy with a Bankable Feasibility Study (BFS) on an upgrade of the current DMS plant to UHDMS technology to allow it to process both high and low grade ore simultaneously, which would involve the DMS components of the plant being converted to UHDMS processes and the installation of an additional primary crusher. The study is due for completion in the second half of next year. Should it be positive, it is envisaged that construction of the upgrade could start in 2020 with full production being achieved in 2023.

While Mobwano gave an overview of operations at Sishen and of the impact of new methodologies and technologies, Glen McGavigan, Kumba’s Executive Head of Technology & Projects, spelled out Kumba’s technology roadmap in some detail to the media group. He said Kumba had started its technology journey in 2014, with its immediate focus being on what Kumba terms ‘Horizon 1’ – essentially the introduction of new but largely proven and immediately available technologies. These, he explained, had been implemented between 2014 and 2017 and had involved an investment of R749 million.

McGavigan said technology projects completed during this period at Sishen – and its sister mine Kolomela, near Postmasburg in the Northern Cape – had included an upgrade of the fleet management system to optimise load and haul cycles to maximise productivity and efficiencies. This had resulted in the average queuing time for the 960E haul trucks being reduced from 5,7 minutes in August 2015 to 4,9 minutes in September 2017 and the average speed of the trucks increasing from 21,2 to 29 km/h. The project, he said, had included the installation of a high-precision GPS shovel guidance system.

Automated or autonomous drilling – in which drill rigs are controlled from a ‘Drilling Command Centre’ – had also been introduced, McGavigan told the media group, with Kolomela being the first to move over to the new technology with Sishen now following with two of its Atlas Copco Pit Viper blasthole rigs having already been converted. Kumba is the first iron ore miner in Africa to switch over to autonomous drilling and one of the pioneers worldwide, with only BHP Billiton in Australia using similar technology.

Based on Kolomela’s experience, the benefits of autonomous drilling are considerable. They include improved safety and drill hole quality and increased direct operating hours (from 17,3 to 18,6 hours per day on average). The levelling time for each drill has been reduced from 1,3 minutes to 0,4 minutes and tramming time has improved from 2,4 minutes to 0,9 minutes.

Other successful technological initiatives at Sishen and Kolomela since 2014 have included the upgrading of information systems, the use of a geo-spatial data capturing tool, the introduction of Mine Information Systems and the installation of Advanced Process Control (APC). The APC technology, which allows improved measurements and control of the processing plants through automation, has already been rolled out at Kolomela and is now being applied at Sishen. The benefits already delivered by APC at Kolomela are impressive, with an 83 % improvement in plant stability, a 6,5 % increase in plant throughput and a 1 % improvement in the lump to fine ratio having been achieved.

Drones support much of the technology, particularly the Mine Information Systems, which enable the concept of the ‘connected mine’ to be realised by providing central data warehousing, reporting and analytics tools to integrate all the data generated at Sishen and Kolomela. There are now ten drones in operation, four at Kolomela – where the first one was introduced in December 2015 – and the remaining six at Sishen. Both fixed wing and quadcopter units are used and are controlled by Kumba employees who have been specially trained and who are licensed by the SA Civil Aviation Authority.

Concluding his talk, McGavigan said Kumba had completed a review of its technology strategy, in the process revising its three-horizon roadmap. Horizon 1, he said, which plotted the way ahead till 2022, would see digital integrated solutions being implemented at its mines while Horizon 2, covering the period from 2023 to 2026, would emphasise what he called ‘seamless remote mining’. Horizon 3, for the period beyond 2026, would involve the introduction of future ‘smart mining technologies’.

The media’s visit to Sishen was not just about technology and concluded with a visit to Siyathemba, a new town established by Kumba to replace Dingleton, a town established in the 1950s to cater for Sishen employees. As George Maluleke, Kumba’s GM for Projects, explained, Dingleton’s residents have had to be relocated to allow expansion of the Sishen pit to the south-west of the mine. The decision to go ahead with the Siyathemba development was taken in late 2013 and the project was completed by mid-2017.

In all, 468 households have been moved and the media group was able to view the new homes and community facilities. There are a small number of residents still living in Dingleton and negotiations are ongoing with them but, in essence, the message from Maluleke was that the resettlement project has been a big success and has opened the way for additional reserves to be brought into the Sishen mine plan.

Finally, what of the future for Sishen? The mine’s remaining life is 13 years based on its ore reserves of 500,8 Mt at 58 % Fe. There is confidence, however, among Kumba’s executives that this can be extended through the use of the UHDMS technology already referred to and Kumba’s ongoing exploration programme, which is mainly focused close to – and between – the existing operations. In the meantime, the mine’s vision is, as Mobwano emphasised, to be the benchmark in Anglo American within three years and best in class in the next five years. Based on what the media saw during its visit, these objectives seem well within Sishen’s grasp.

Photos courtesy of Kumba (unless otherwise acknowledged).

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Arthur Tassell
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