COMMODITY: DIAMONDS A world-class operation Every now and again, you come across a real gem of a mine that isn’t just about the commodity, but rather the entire mine, and the manner in which it is managed and operated. Petra’s Finsch diamond mine is such a mine. BY TONY STONE HE FINSCH DIAMOND mine resource, with 51.3 Mcts, including 28.0 is pure synergy, a team effort Mcts in reserves and 2.0 Mcts in tailings. between the mine, Sandvik – Its innovative infrastructure, modern its primary mechanisation and plant, and quality management process automationT provider – and other state- provide the framework for its excellent, of-the-art technology service providers multi-award winning safety and envi- – such as Schneider Electric and Bentley ronmental record, as well as its strong – in an integrated system that literally social responsibility programme. runs like clockwork. The mine’s ‘block cave’ and ‘sub lev- Located 165 km northwest of Kimber- el cave’ mining methods achieved a ley, in the Northern Province, the mine high-volume, low-cost 2014 production is South Africa’s second largest diamond of 1.89 Mctpa, with a revenue stream of mine by production, after De Beers’ US$183.7 million. Expansion plans will Venetia diamond mine. With mine safe- see a run-of-mine production increase to ABOVE The Finsch diamond mine ty as the number one priority, Pieter 2.0 Mctpa, from the 2018 fiscal year. BELOW Deon Stander, safety manger and Boshoff, technical services manager at the Finsch diamond mine, demonstrating Petra Diamonds, is a stickler for safe- Surface to underground the Res-q-pack ty. Looking at Finsch’s safety record, Mining at Finsch began on a small it’s quite impressive. ISO14001:2004 scale, after Allister Fincham and Wil- open pit operation. This went on until and OHSAS 18001:2007 accredited, its liam Schwabel, two prospectors look- September 1990, when this mining meth- trophy cabinet is testimony to this, as ing for asbestos, stumbled upon the od was terminated, at which point the pit is its November 2014 Northern Cape find in 1960. When De Beers took over, had a surface area of 55 ha and a depth Mine Managers Association award for in October 1964, they mined the 118 of 423 m. From then onwards, the underground safety. Finsch is a major million year old volcanic pipe as an mine’s operations moved underground. INSIDE MINING 06 | 2015 17 COMMODITY: DIAMONDS FIGURE 1 A cross-cut of the mine superior connectivity, Schneider’s Ci- tectSCADA’s easy configuration tools and user-friendly screens were select- ed, and they were implemented without incurring delays. For example, the ad- vanced technology, especially in the use of ‘blown fibre’ – ultra-lightweight sin- gle bundle optic fibres passed through preinstalled tubes using only airflow – exemplifies the sophistication of this installation. In addition, this particular type of fibre optics allows expansion without disrupting operations. And, of key importance, CitectSCADA’s built-in redundancy and system stability were key factors in the purchase decision. Ensuring safety and reliability for the mine’s operations, the CitectSCADA system has dual redundant server pairs. This is where things get interesting. Two each with unique characteristics and The system is used to monitor and con- methods of underground mining are be- different grades. Of these, two facies trol processes throughout the mining ing used at Finsch today – block caving (F1 and F8) make up the majority of the operation, including rock breaking, ore and sub level caving, in a mechanised main pipe. Grade quality increases with management, access control, production and automated operation. depth, with a concomitant decrease in control, dispatch, and CCTV, to deliver a waste dilution. total, low-risk solution that dramatically Geology minimises downtime, lowers life-cycle To contextualise these mining methods, Operations centre costs, and provides crucial information an understanding of Finsch’s geology is In moving underground, with the initial in real time. A high capacity (1 GB/sec- necessary. A classic diamondiferous kim- development of Block 4 as a mechanised ond) Ethernet LAN handles the vast flow berlite pipe, it is hosted by banded iron- and automated mining operation, and of data within the operations. stones at the surface and, beneath that, to maximise production efficiencies, the Four 62-inch plasma screens provide dolomites and limestones of the Gri- creation of a purpose-built operations an overview of the production status qualand West Sequence of the Transvaal centre was necessary. Also, and not for- and progress. Two are used for the au- Supergroup. The pipe, originally 17.9 getting that Finsch’s objective was to tonomous operation, while the other ha on the surface, is a group II kimber- develop a state-of-the-art mining oper- two are used for the other mine op- lite intrusion, consisting of weathered ation, an intuitive operator interface, erations. A fifth screen provides re- kimberlite (yellow ground) to a depth of with simplified configuration for ease al-time coverage of the autonomous around 100 m with unweathered materi- of maintenance and operation, was an operations underground. al (blue ground) beneath that. absolute must. After a careful selection In planning the centre, one of the pri- The main pipe tapers to 3.7ha, and the process to identify a SCADA solution mary risks identified was the possibil- precursor to 1.5ha, at 880m. There are a that would provide the necessary high ity of production downtime. This was, total of eight different kimberlite facies, operability and scalability, as well as and is, avoided with the support of a professional team of service experts. ABOVE Finsch’s state-of-the-art control room It’s their number one priority. For the mine, reliability and performance are non-negotiable. Geospatial data system Bentley Systems were contracted to de- velop an integrated geospatial data man- agement system to better enable Finsch to manage their geospatial data, which is stored in multiple databases across the five departments, previously function- ing in isolation. Data redundancy is now a thing of the past. On top of this, the mine also co-manag- es the mining town of Lime Acres, for which the GIS-based system captures data and bills residents for water and electricity usage. Survey and plan data 18 INSIDE MINING 06 | 2015 COMMODITY: DIAMONDS FIGURE 1 The geological model of designed pre-construction process. where LHDs collect the ore, taking same the Finsch pipe First, access and ventilation shafts must to load points where the ore is trans- be sunk to a level below the ore. In this ferred to fully automated (driverless) instance, Finsch’s main shaft is down to dump trucks that take the ore to the its current depth of 825 m. After this, underground gyratory crusher. As the two rim tunnels circling the pipe are de- funnels empty, the ‘roof’ above the un- veloped; the top rim tunnel is used for dercut, now without support, collapses the ‘undercut’ layer, and the bottom for and drops away, feeding more material the ‘production’ layer. into the funnels. This process progresses Finsch was quite smart in its design, until the ore body is exhausted. and developed a service tunnel, connect- On occasion, a funnel will become ed to the spiral decline tunnel, with oil blocked by a large boulder; secondary bays, stores, service bays, wash bays, and blasting is used to remove the problem. offices off to the one side of the haulage The pattern of blasting and ore removal rim tunnel. The service tunnel is linked, is carefully managed by the control room via connecting tun- to ensure that the ‘roof’ collapses in a nels, to the rim tunnel. level, or balanced, manner. RIGHT Pieter Boshoff, technical services A series of horizon- Finsch’s objective in mining this way is manager at Petra Diamonds tal tunnels, known as to extend its life-of-mine to sustain its haulage tunnels, from current production profile and increase are captured and digitised. The mapping one side of the pro- run-of-mine throughput to 3.5 Mtpa. feature digitally represents the mining duction rim tunnel to Production is currently taking place lifecycle, town, and residential layout. the other, are dug using the traditional in Block 4, at 630 m, while the devel- The publishing feature makes the geo- drill and blasted method. Between, and opment of the sub level caving mining spatial mining and town information ac- connecting, the haulage tunnels, a series (SLC) method is taking place between cessible to the whole mining group. For of ‘raise’ tunnels are dug in an angular, 700 m and 780 m. billings, the database interrogates the almost roundish shape, to accommodate A dedicated conveyor for ore-han- human resources system and automati- the LHDs (load, haul, dump), each with dling – to transfer SLC ore to existing cally sends invoices to residents. a slight rise in the middle to prevent infrastructure at 650m – will be ready water accumulation. in the 2016 fiscal year. Once the Block Block caving The small quantities of water runoff 4 has been fully mined, it will be de- Moving underground, block caving is into the haulage tunnels are handled by commissioned. First production from a hard rock mining method that un- due processes. Within each raise tunnel, Block 5’s SLC will take place later this dermines an ore body, allowing it to a funnel-like cavity is drilled and blast- year, with production ramping up to 3.5 progressively collapse under its own ed upward, beneath the undercut level. Mtpa by 2018. weight. As a mining method, it is a safe The mouths of these funnels abut one and proven method, which provides ac- another, forming a continuous plane Sub level caving cess to higher volumes of ore than other of funnel mouths where they contact t Tunnels, or drifts, up to 130 m long, are methods.