MechChem Africa January-February 2023

⎪ Minerals processing and materials handling ⎪

Casting innovation for Weir Minerals’ Isando plant

Weir Minerals Africa has reduced turnaround times and further improved quality levels with the recent opening of its Replicast Plant at its foundry in Isando. Plant manager, Umar Smith says there are also sustainability benefits from the new technology. Developed with local expertise, the innovative facility is a testament to the skills and resourcefulness within the local business. W eir Minerals Africa’s exciting new Replicast Plant in Isan do, Gauteng, is driving down component turnaround time

while improving quality and reducing waste. Umar Smith, plant manager at Weir Minerals Africa’s Isando facility, explains that the innovative development enables the company to produce more components at a time – and more quickly. This will assist inmeeting growing customer demand, while reducing rework and wastage. “As part of our Project Vuka, the new plant allows us to cast multiple small com ponents per batch rather than just one at a time,” says Smith. “We can also reduce our knock-out times from days to just a couple of hours.” The state-of-the-art facilities enable Weir Minerals Africa to cast high chrome parts weighing up to 250 kg. There are two phases to the new process, he explains, which uses polystyrene to create the moulds. The first phase is the polystyrene mould ing process, which occurs after the poly styrene beads have been expanded. The second phase is where the ramming, pouring and demoulding takes place. In contrast to the traditional moulding line – where resin and catalyst are used to bind sand – the Replicast Plant uses silica sand of 30-35 AFS grade together with the polystyrene mould, he says. The system involves a vacuum bin, fromwhich all the air is removed to compress the sand. “The absence of resin and catalyst – as well as having no clamping process – results in less scrap being produced, and therefore brings operational savings,” he says. “The quality of castings is also raised, with a bet ter surface finish and fewer defects.” He notes that the geometrical stability of components is improved, as there is less fettling of the finished product thereby reducing dimensional variation between the components. This in turn contributes to the reliability of the equipment using those components. He says the foundry will also realise significant environmental benefits as a result of using no chemicals in the sand. “This new plant aligns well with our cor porate sustainability goals, ensuring that

The new Replicast Plant was opened in May 2022 by Weir Minerals President, Ricardo Garib and Vice President of Operations, Richard Hinsley.

Weir Minerals is now using AFS grade 30-35 silica sand, which is more environmentally friendly.

our processes are compliant, and continu ously reduce our environmental impact,” says Smith. “Our new moulding systems ensure that fewer gases are emitted dur ing the casting process, and there are zero emissions of harmful substances such as benzene.” The new technology is also leading to less frequent disposal of silica sand and the sand itself is more environmentally friendly as it contains no resin or acid. “A remarkable aspect of developing this

new plant was the fact that it was done with our local skills and largely during the Covid-19 lockdowns,” he says. “Despite the novelty of this technology, and the logisti cal challenges created by the pandemic, it was successfully implemented on time and within budget.” The new Replicast Plant includes more than 16 000 individual components, and uses over 1 900mof cabling, 300mof water piping and 55 tons of steel. www.minerals.weir

January-February 2023 • MechChem Africa ¦ 21