Coating solutions partner for mining industry

Coating solutions partner for mining industry

According to Thermaspray managing director, Dr Jan Lourens, enhanced performance and durability along with extended equipment life span because of applying these protective coatings ultimately lead to increased uptime and boosted output for the mines.

“Furthermore, the use of coatings to refurbish components offers a much faster and more affordable solution compared to replacement with expensive new parts and there are no delays (downtime) because of having to wait for parts delivery.”

Mining has been the backbone of the South African economy for over 150 years. Producing coal, gold, diamonds, platinum, palladium, chromium and uranium, the country boasts one of the deepest mines in the world.

The industry has faced tremendous challenges with crippling strike actions particularly in the platinum mines in 2015. This has seen a dramatic decrease in mining production and negative growth and the protracted slump in mining production output continues. Mines are also forced to mine ever deeper to find higher quality ore putting even greater stress on mining machines.

But despite all the obstacles, the mining industry continues to make a valuable contribution to the country’s economy contributing 18% to GDP mostly through foreign exchange earnings and as an employer (mining and related industries employ over one million people).

However, looking ahead, there is no doubt that the mining industry must implement serious changes to ensure a sustainable future. Reducing expenditure and operational costs and improved output is the formula for successful growth. “Ensuring the longevity of machinery and equipment is an extremely effective way to keep costs down and productivity up,” states Dr Lourens. “This is where thermal spray coatings can play a pivotal role as a positive contributor to a mine’s bottom line, irrespective of the ore or mineral being produced.”

Surface and underground mining machinery and equipment such as scoop trams, drills loaders, excavators, crushers, mills and haul trucks are exposed so some of the harshest conditions and most stressful environments having to deal with heat, dust, mud and water.

Dr Lourens elaborates, “Component wear causes physical material removal and corrosion leading to chemical degradation and is the main surface degradation mechanism in the mining industry. The resulting corrosion, abrasion and excavation impact lead to premature component and equipment failure. Unsurprisingly, mining machines often reach their end-of-life prematurely. Alongside spiralling operational costs, unplanned stoppages due to critical failures have a massive negative impact on a mine’s production.”

A practical solution to mitigate the effects of these processes is the deposition of hard-faced thermal-sprayed coatings and steel metal matrix composites. “There is a great demand for thermal spray coatings in the mining industry,” continues Dr Lourens. “By protecting critical components, protective coatings extend machinery equipment life span and maximise machine up time. In fact, advanced abrasion resistant materials can cut scheduled downtime in half by doubling the life of wear components.”

According to Dr Lourens, thermal spray coatings are favoured over weld hard-facing because they permit greater flexibility of composition. “Sprayed parts are subjected to lower and more uniform heat input during processing resulting in less distortion and a shallower heat affected zone.”

Thermal spraying comprises of various processes such as HVOF (High Velocity Oxy-Fuel). Air Plasma Spraying, Flame- or Wire-Arc. In these processes a fine powder, usually metallic or non-metallic powders such as ceramics, is fed through a chamber by a gaseous carrier, which is then ignited. The powder is melted and is then deposited onto the surface of the component being coated.

Tungsten carbide (WC)-based cermet materials are used extensively to fabricate wear resistant coatings which are ideal for mining machinery. Usually deposited by HVOF spraying, the WC hard phase material provides resistance against abrasive and erosive wear and the cobalt (Co) and/or chromium (Cr) metal acts as a ductile matrix to provide support for the WC particles and increase the toughness of the overall coating. In the event of wear as a surface degradation process, in conjunction with corrosion, the use of a HVOF-sprayed WC-Ni-based coating is recommended.


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