In the underground or open pit ore extraction environment drills break, bolts get discarded and loader teeth shear off. In most cases these pieces of tramp metal end up with the ore in the tipping trucks and on the conveyor belts. If not removed, tramp metal could cause enormous damage to downstream processing equipment such as crushers. In the case of secondary and tertiary crushers, normally with a smaller aperture, tramp metal may even jam the crusher, bringing it to a halt. When this happens the crusher has to be stripped down in order to remove the offending piece of tramp metal, seriously impacting productivity.
The two primary methods of ensuring that tramp metal is removed from ore are either by means of a magnet or by means of a metal detector. More often that not, the two methods are employed in conjunction with each other. Magnets are highly successful in removing a large amount of tramp metal but cannot pick up non-magnetic metals such as stainless steel or pieces of metal that are, for instance, firmly wedged under a large piece of ore. In such cases metal detectors are employed to identify the tramp metal not removed, mark the ore and stop the belt to allow for the removal of the tramp metal by the operator.
SCUA holds regional agencies for Metal Detectors and Magnets and has substantial practical experience in deploying these technologies in the mining environment.
SCUA can source a variety of high quality, robust Metal Detectors that have been used successfully in mining, minerals and food processing industries for many years. With the new, advanced microprocessor-based control, Metal Detectors can be set up to ignore most ore types and only respond to the actual tramp metal. The detectors even work with steel core belts and with the optional clip detector installed the system will ignore metal splices and repair clips on conveyor belts.
Metal Detectors can be interlocked with the client PLC in order to stop the conveyor belt when tramp metal has been detected, allowing the operator to remove the offending material before any damage is caused. There are two types of position markers available to indicate the actual location of the tramp metal on the belt. A spray system will release a blast of coloured spray onto the ore and, for cases where spray would not function, a flag dropper can be utilised.
Suspended permanent or electromagnets can remove most tramp metal from flows of various materials like coal, other ores and almost any conveyed non–ferrous material. With more than 20 standard magnet sizes and hundreds of special designs available, there is a magnet for virtually any application.
The high quality and performance magnets are extremely robust and manufactured with a durable Manganese bottom plate. In simple installations with low tramp metal volumes a manual–cleaning magnet can be installed. Self–cleaning units provide for continuous tramp metal removal in high volume applications. Where required, heavy duty, high temperature resistant belts can be specified for self cleaning installations, typically near furnaces or where hot, sharp tramp metal is present.
SCUA Metal Detection and Magnetic Tramp Metal Removal Systems can be interfaced with the client PLC systems. Typically the PLC would stop the conveyor belts when tramp metal has been picked up by the metal detector, allowing safe removal by the operator.