Pretoria-based Multotec Wear Linings is one of the country’s leading suppliers of high alumina ceramic wear linings and associated products such as basalt linings and epoxies. “Through a natural evolution, the company’s product range has developed into a range of total wear solutions which incorporate the design of chutes and transfer points for efficient bulk materials handling as well as the capability to provide fit for purpose wear lining solutions,” Taylor says.

Superior lining materials
“Product development has seen some specialised wear resistance lining innovations being introduced to industry in recent years. Two of these are the composite liner and the wafer liner,” Taylor says. The Multotec composite wear plate has been successfully used in iron ore, manganese, kimberlite, platinum and gold applications.

The ceramic impact panel comprises engineered ceramic tiles embedded in an epoxy-based resilient bed. Composite wear plates are custom made for specific application requirements to ensure an optimum wear solution. “Although there are restrictions on optimal panel sizes, they can be made up in almost any shape,” Taylor says.

“Both the composite liner and wafer liner are designed for high impact applications whereby the polyurethane provides energy absorption to protect the ceramic and the wafer liner uses Hardox plates to absorb the impact. The ceramic in turn provides the wear resistance,” Taylor says. By using these composite designs Multotec has been able to extend the use of ceramic products for coarse materials and large drop height applications.

At the opposite end of the wear lining spectrum are the Multotec Rubber products which provide wear resistance through their high resilience and ability to absorb energy. A major benefit of using rubber wear linings is the significant noise reduction achieved as well as the reduction in energy transfer into steel structures.

“Rubber offers the ability to line chutes and transfer points which handle extremely large particles,” Taylor says. “By increasing the thickness of the rubber itself these liners are able to absorb the impact from extremely large rocks.” An important aspect to consider when using rubber liners is that the angle of impact must be correct and this again relates to the chute or transfer point design.

When the angle is not correct, and it is not possible to modify the chute, Multotec Rubber is still able to supply an appropriate solution with its RubCer® composite liner. This composite liner utilises the properties of both ceramic and rubber, with the ceramic resisting the cutting action and the rubber providing energy absorption and protecting the ceramic against breakage.

Traditionally this product was supplied in the form of Cylpebs (cylindrical pebbles), but it is now available in ceramic blocks as well as hexagonal tiles.

Research and development is a cornerstone within the Multotec Group, and Multotec Rubber is currently busy with the development of a loose liner which will offer greater flexibility and impact absorption. “Even more importantly, the system is of a modular design and will facilitate very easy replacement of small sections. The product is due to go into field trials shortly and will be introduced to the market later in the year,” Taylor says.

A multitude of screening media
Although Multotec does not manufacture vibrating screens, Multotec Manufacturing’s primary business is the supply of a wide range of screening media to mines and quarries as well as for all the OEM screen suppliers. “Multotec was a pioneer in the field of polyurethane screening media in southern Africa and has focused on introducing polyurethane screening panels to the South African industry,” Taylor says.

With its focus on injection moulding, the industry benefits through access to a wide range of screen panel designs and aperture sizes as well as quicker lead times. “Injection moulding of screen panels facilitates greater repeatability and consistency, all adding up to providing greater screening efficiency,” he says.

Multotec has a number of patented screen panels including Vibroplast and Hi-Flow. The Vibroplast panel has excellent non-blinding characteristics, enabling the end user to handle difficult screening applications efficiently. The Multotec Hi-Flow screening system offers the maximum available screen surface area for apertures resulting in a high open area which leads to a high throughput and efficiency.

A major differentiator for Multotec is that the injection moulding range is complemented by its ability through its casting shop to be able to produce heavy duty modular panels as well as a complete range of alternative panels such as large bolt-down and tensioned panels. This allows the company to custom make screen panels to fit existing screen frames which have not been converted to a modular system.

The Saddle Top is a polyurethane component, which is fixed to a vertical laser cut flat bar runner. This rail system replaces the top section of the conventional angled runners on a vibrating screen frame. Its major advantage is that once the fastening holes become worn only the Saddle Top, and not the complete runner system need to be replaced, in a process which can be accomplished with semi-skilled labour.

“The excellent wear characteristics of the system result in improved life as well as reduced maintenance and downtime,” Taylor says. The engineering design of the Saddle Top supports the internal frame of the screen panel, substantially improving panel stability and life. It is secured in place using nylon pins that ensure uncompromising fastening but are still easy to remove when the Saddle Tops need replacing.

The Saddle Top can be used on all modular polyurethane screen panel systems and can be readily retrofitted to the existing screen frames. It is suitable for use on conventional Multodeck, Hi-Flow, Clip-in Polywedge and Polypunch modular panels without compromising the open screening area.

“Use of the correct combination of the Multotec Saddle Top and T-Bar Rail System will substantially reduce maintenance downtime on a vibrating screen, improve availability and reduce costs,” Taylor says.

Combinations of the Multotec Saddle Top and T-Bar runner system can be used, with the latter being installed at the feed end of the screen where impact resistance is important, and the Multotec Saddle Top where abrasion resistance is the priority.

Taylor says that recent developments have included pinless screening. “To address high impact areas on a vibrating screen, Multotec Manufacturing developed the T-Bar runner system with a laser cut flat bar runner with a weld-on profiled ‘T’ section. The ‘T’ section can be manufactured from mild steel for standard applications, 3CR12 for corrosive environments and VRN 500 for abrasive applications.

In addition to the screen panels, Multotec offers a range of screening accessories such as feed impact liners, sideliners and spray nozzles.

Multotec Rubber has a complementary range of modular and bolt-down screen panels suitable for heavy duty and difficult screening applications where the natural resilience and energy absorption properties of rubber will overcome these problems.

Multotec Process Equipment has a range of sampling products including the Multotec Hammer cross-belt sampler designed to effectively sample from a moving conveyor belt.

Cross-belt hammer samplers have direct drives capable of sampling up to 7 000 tph of material or more from belt conveyors running at up to 5,5 m/s. Mechanical reliability is outstanding and availability of these units is consistently better than cross-stream samplers in general, due to their rotating action as opposed to back and forth cutter travel between proximity sensors.

Many new improvements have been introduced recently to overcome spillage and improve sample integrity further with large housing designs, skew cutters and better control of potentially misplaced material to sample.

Critical maintenance
Multotec has implemented maintenance contracts for a number of its customers in order to mitigate against the loss of skills in the mining and quarrying sectors as well allow the mines and quarries to concentrate on their core business.

By maintaining customer screens on a regular basis it is possible to make sure screens operate in accordance with performance specifications and this not only improves screen availability but also translates into greater plant productivity as well as screening efficiency ensuring optimum product throughput.

The Multotec Group’s maintenance and service contracts offer users of its screening media a new add-on in the form of the Hawkeye Monitoring Programme. Developed in-house, the programme effectively monitors screen maintenance processes, giving customers peace of mind and guaranteed efficiency.

Hawkeye is a web based application, accessible anywhere in the world, which offers the user an easy-to-use interface to allow accurate and efficient recording of maintenance activities. These entries are stored in a database, and can be called up as required in a number of ways in order to zero in on what is actually happening on the screen.

Hawkeye uses a graphical representation to identify underlying screen components in a grid reference format. Based on the data recorded, a process change or product improvement process can be initiated, or an alternative product can be suggested, to optimise wear performance.

“Another critical benefit is that screen panel life expectancy can be determined. Essentially Hawkeye allows our customers to optimise the screening surface of their plant,” Taylor says.
 

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