Global mining operations can benefit from a range of high-density polyethylene (HDPE) rollers, which are available through Gauteng-based manufacturer and supplier of bulk materials handling conveyor equipment Melco, says Melco MD Gavin Hall.

“The company’s range of Supreme HDPE rollers serve as an ideal complement to steel rollers, particularly in highly abrasive and corrosive applications such as in the petrochemicals, mining, mineral processing and power generation sectors.

“HDPE is a polyethylene thermoplastic and offers good resistance to abrasion and corrosion.”

Further, Hall tells Mining Weekly that the hard-wearing Melco Supreme HDPE range of rollers can be used in any application where steel rollers are used.

“HDPE rollers generally have a longer life span than standard steel rollers because of a 12 mm external HDPE sleeve, which ensures overall cost savings with regard to maintenance and downtime,” he explains.

Hall adds that HDPE rollers are lighter than their steel counterparts, requiring less power at startup, and have excellent resistance to abrasion and corrosion.

The Melco range of Supreme HDPE rollers are also ultraviolet ray resistant, owing to its HDPE compound properties, making it less vulnerable to extreme weather such as the harsh African sun.

Hall highlights that HDPE rollers can be supplied with fire-retardant and antistatic properties. “HDPE rollers have the same load capacity as steel rollers of the same size; however, their superior abrasion resistance has resulted in the product being popular in platinum mines,” he states.

Further, Melco’s customers have reported less belt damage since switching to HDPE rollers, as platinum-bearing ores have a high specific gravity, which can cause damage to steel rollers.

Manufacturing Process

“During the assembly process of a steel roller, a steel tube and steel-pressed bearing housings are welded together,” Hall explains, adding that during the manufacturing of the HDPE roller, an inner steel tube is press-fitted into a castellated HDPE sleeve.

Additionally, he notes that the polypropylene bearing housing is interference-fitted into the steel sleeve and the HDPE sleeve, as no welding is involved.

Hall highlights that the entire assembly is held together by the interference and circlips.

“The inner steel tube ensures adequate mechanical strength and tube roundness, while a combination of the thicker HDPE sleeve and steel sleeve provides higher bending strength,” he adds.

He comments that the machined finish of the HDPE Supreme roller results in low total indicated run-out, which ultimately reduces vibration and noise levels.

“When using these rollers, hearing protection for employees is not often required, which proves to be advantageous in the health and safety arena. HDPE is fully recyclable and is, therefore, the most environment-friendly roller available on the local market.”

Dealing with Industry Challenges

“Melco is affected – as are all mining equipment manufacturers and suppliers – by global commodity cycles,” admits Hall.

“An established company, like Melco, understands that it has to be dynamic and flexible to survive the tough times. This is why we place strong emphasis on the parts replacement and project aspects of our operations,” he states.

Melco exports a significant amount of materials handling equipment to countries such as Peru, Zambia, Mozambique and Brazil for use in cement manufacturing and at iron-ore and copper mines.

He adds that the company diversifies its product and service offering according to the needs of its customers.

Moreover, he says that South Africa is still considered a low-cost country for manu- facturing and manufacturers, as prices are comparable to those of Chinese and Indian mining equipment manufacturers.

Hall stresses that South African mining equipment is known not only for its cost competitiveness but also for its quality, which stands the industry in good stead, he adds.

Skills Development

The Melco School of Belt Conveying, in Germiston, on the East Rand, assists clients in operating their conveyor systems safely and efficiently.

“This gives personnel the opportunity to learn about conveyor best practice and to discuss specific situations that they face,” Hall explains.

The company’s School of Belt Conveying trained 200 people last year, he points out.

Further, Hall says that the training can either be conducted at the Melco training centre, also in Germiston, which includes a tour of the Melco production facilities, or at the client’s facility.

“Where possible, the training includes specific observations from the client’s plant. Training can last from two hours to a day,” he notes.

The training courses cover topics that include safety around conveyors, the correct use of various components that comprise a conveyor system and solving common conveyor problems, such as belt alignment and spillage, as well as an overview of Melco products and product advancements.

Hall states that the training courses are specifically tailored, from operator level to engineer level.

He says many benefits result from training a company’s staff correctly, including improving site operational efficiencies and enhanced staff skills, which assist in bolstering overall safety standards on a site.

Melco is an ISO 9001:2008-accredited company that operates a highly specialised testing facility where products are tested under laboratory-controlled environments prior to field testing, full-scale manufacture and supply.

“This process ensures that Melco products are among the most advanced in the world. We also operate quality management systems, which control every aspect of the company. These systems are audited regularly to ensure compliance with the highest standards,” Hall concludes.