Tag Archives: cement

UPDATING TECHNOLOGY WITH PLANNED MAINTENANCE – AFRISAM

To stay at the cutting edge of cement production technology, construction materials leader AfriSam ensures that its maintenance programme is well planned with future production targets and energy efficiency goals in mind.

According to Hannes Meyer, executive – cementitious at AfriSam, the company’s maintenance standards are codified as part of its corporate ‘AfriSam Way’ programme, and comprise three areas: preventative maintenance, corrective maintenance and capitalised maintenance.

“Capitalised maintenance is vital to ensuring that you stay abreast of current technology and upgrade regularly in a way that improves the performance of equipment continuously,” says Meyer.

At its Ulco plant in the Northern Cape, for instance, the capitalised maintenance plan is allowing production to be raised from its original production capacity of 3,500 tonnes per day of clinker to a targeted output of 4,750 tonnes per day in the near future. The plant – built in 1984 – already runs comfortably at over 4,000 tonnes per day.

In addition to the production increases, the plant upgrades conducted as part of the maintenance schedule are also driven by the need to reduce energy costs and environmentally negative nitrous oxide (NOx) emissions. He highlights that energy has become one of the most costly components of cement production – comprising electricity costs and thermal energy mainly in the form of coal.

“Installing a high efficiency separator gave us an immediate reduction in energy consumption, while an upgraded clinker cooler also facilitated higher output at the same time as reducing energy costs,” he says. “The gearbox in the raw mill was also replaced with a view to reaching our 4,750 tonne target. We replaced the electrostatic filter with a bag filter, not only to comply with more stringent emission standards but also to cope with the added volumes of air through the kiln.”

Another imminent upgrade will be to raise the capacity of the pre-calciner, which will in turn increase the output of the kiln while reducing the energy it consumes.

“The new pre-calciner will also have a positive impact on our nitrous oxide (NOx) emissions, by ‘splitting’ the energy input between the firing end of the kiln and the pre‑calciner,” he says. “This reduces the temperatures or the energy load in the kiln, which cuts down NOx formation.”

In a further innovation, AfriSam is helping to address the environmental issue of old vehicle tyres by using them as an alternative fuel at its Dudfield cement plant; the project is also designed to be labour-intensive, creating local jobs as part of the company’s positive social impact in its areas of operation.

AFRISAM READYMIX FOR UNIQUE DYNAMIC’S DROOGHEUWEL RESERVOIR PROJECT

Gauteng continues to be an urban magnet drawing job seekers from far and wide, making the Droogheuwel municipal bulk water reservoir in Randfontein a vital piece of infrastructure to keep sufficient water flowing to the growing area of Randgate.

Hard at work on this 20 megalitre reservoir is the Stilfontein-based contractor Ultimate Dynamic, supported with concrete from construction materials leader AfriSam. The project is due for completion in March 2018.

According to Pieter van der Merwe, Ultimate Dynamic’s project manager, the 47,6 metre diameter structure, with a wall thickness of 500 mm, will require about 2,000 cubic metres of water-tight pump-mix concrete with a strength of 40 MPa.

“After the contract was awarded in December 2016, we started preparation on site in January and were ready for our first concrete pour in April,” says Van der Merwe. “We are now about a third of the way to completion, and are busy on the third lift (or level) of the reservoir wall, which will require eight lifts to take it to the required height of almost 13 metres.”

Readymix is being delivered from AfriSam’s Technikon plant in its six cubic metre capacity trucks, with each pour comprising about 60 cubic metres – or ten trucks of readymix. Concrete is raised and deposited into the formwork moulds by a truck-mounted boom pump with a reach of over 40 metres, according to AfriSam production team leader Mark Wernich.

“We currently deliver on average once every seven working days, and our plant is conveniently located less than 25 km from site,” says Wernich. “Our production capacity and specialised equipment will also allow a continuous pour of about 380 cubic metres for the roof of the reservoir, once the walls are completed toward the end of the year.”

Van der Merwe says the project covers the reinforced concrete construction of the reservoir walls and roof, as well as all pipes, valves, access manhole doors and step ladders. It also includes the inlet and outlet chambers for the reservoir, pump rooms and the access road from the existing tar road nearby.

“It has been a smooth operation working with AfriSam,” he says. “We place our site orders with Ultimate Dynamics head office, which contacts the AfriSam call centre. The concrete is then dispatched from the plant in Technikon in Roodepoort, and it has all proceeded like clockwork.”

He highlights the value of AfriSam’s quality control function, which includes taking their own concrete tests on site with every delivery, ensuring that the correct strength of concrete has found its way into the structure.

“It is vital that tests are conducted on every batch, and the results carefully recorded, so that our client can be assured of the integrity of the work,” says Van der Merwe. “With a major structure like this, holding such a large volume of water, there needs to be great attention to every detail.”

Wernich says that AfriSam’s quality systems are a key element of its offering to customers.

“Even when our customers do their own testing, we also test and keep records that they can refer back to if there is ever any query about any particular batch of readymix delivered,” he says. “AfriSam’s plant laboratories – based at our cement, aggregate and readymix operations – ensure ongoing process control testing on all our products.”

Once the Droogheuwel reservoir is complete, the pipeline to feed the new reservoir will be laid over a distance of about seven kilometres through the town of Randfontein, linking it to an inlet pump station on one of Rand Water’s main lines. Water from the reservoir will then be pumped from the outlet chamber on site to the pressure tower about two kilometres away, from where it can enter the reticulation system serving the surrounding area.