Modern Quarrying January-February 2015

AT THE QUARRY FACE

The houses, which have been upgraded over the years, still incorporate the solid thick walls, foundations and fireplaces built so long ago. The gardens and facilities are beautiful and MQ was impressed by the well-kept facilities, green lawns, fauna and flora. The village includes a well- equipped recreation facility, with a large swimming pool, and of course, a nine-hole golf course. PPC’s cement plant at De Hoek has been using Adroit’s SCADA system for many years, and is a major user of this technologically-advanced open automation Adroit Supervisory Control and Data Acquisition package. Engineering manager Steven Strauss says the whole plant is monitored by Adroit. “Each section has its own Adroit installation where the operators are able to visually see what is happening through- out the plant. It will indicate all your running condi- tions at that stage, and it is also possible to draw statistics from the past if you do fault finding for example, together with weights, temperature pres- sures, etc. There are a lot of decisions made via the information stored on the Adroit SCADA system.” Taken on a drive through the quarry, Diergaardt explains that the 760 ha property was purchased from the nearby farmers, and the same farmers rent it back from PPC for agricultural purposes.“We are only mining a small area, the rest of which they use for wheat planting and for their animals.” En route to the Zoutkloof pit, we passed the primary crusher which feeds via a belt to the sec- ondary. The back area at Zoutkloof which is filled with water is the final 180 m depth of mining. Here the limestone deposit sits at 55°, and on the side- wall, one can see the phyllite which is screened out to the waste dump in order to enhance its quality. The area at the back of the pit is overburden from Vondeling, which has been backfilled into the pit. The new Vondeling pit, which commenced mining in 2007, is at a current depth of 50 m. One could see the sump established at the back, and the next cut will be into the limestone.“In the short to medium term, our plan is to extend the front area, because of the shallow limestone deposit,” Diergaardt says. The ramp is being shortened to enable more efficient hauling. In the front one could see the overburden and a small amount of limestone in the corners, with the majority of the limestone being on the lower level. “In terms of the whole pit, the wall will need to be shifted towards the east as the limestone is getting deeper and deeper. At the moment we are moving 2-2,5-million t of overburden annually and we have a 2:5 stripping ratio.”Blasting is carried out by PPC De Hoek one to two times a week, with BME supplying the explosives. We drove to the stacking area of the mine, where, Diergaardt explains, is where his

responsibilities end, with factory production start- ing its process. There were three limestone piles, one full, one being reclaimed and one being stacked at 18 000 t each. The shale stockpile was about 5 000 t at the time of MQ ’s visit. In summary, the reclaiming of materials includes: • Raw materials which are mined on site: 90% limestone and 3,5% shale. • External supply: 4,0% sand; 6-10 t/hour coal; and 2,5% FDG.

The primary crusher is a semi- mobile unit, which is moved to the service area every three to four years for maintenance purposes (courtesy PPC De Hoek).

Graduate bites the De Hoek bullet

MQ had the privilege of a brief chat with Wits graduate Matty Mukwevho, who is on the graduate programme. She is currently com- pleting her Blasting Ticket, and says it is going extremely well. Asked how she copes in what is traditionally a male-dominated environment, she says in the beginning she battled a little, but she focused on what she wanted in life. “It is not about where I am but rather about what I want to achieve at the end of the day – and that is what my focus is.” Mukwevho was approached at Wits to join the PPC graduate programme. She went for the interview and the rest is history. Holding a BSc (Eng) Mining Engineering, she is in her second year of the grad- uation programme. She has completed 54 blasting shifts, with another six to go before she is assessed for her Blasting Ticket. She says she is well accepted by her peers and colleagues at PPC, and is very excited about her future career. Diergaardt explains that Matty has a programme layout with about 10 modules she has to complete during the course of the year. She moves from department to department. “She started in drilling, blasting, primary crusher, environmental, water management, etc, so she constantly working on those, while attending all her blasting shifts. Matty now has her driver’s licence and from the end of February, will start supervising some of the shifts.”

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MODERN QUARRYING

January - February 2015