A magnetic separator can help mine operators identify and remove tramp metal in the early stages of a project
Tramp metal exists in all mining and quarrying operations and the problematic contamination is difficult to avoid. The nature of mining and quarrying – extracting ore and aggregate using large heavy equipment – results in a wide variety of tramp metal contaminating the mined material. Such metal needs identifying and removing before potentially causing costly damage to processing equipment (such as crushers, screens, and conveyors). Additionally, for many mining operations there is a maximum metal contamination content in the mined ore specified by the end-customer (especially in coal supplied for power stations).
Origin of tramp metal
Understanding the source and nature of the tramp metal is the first stage in the process of effective removal. The definition of ‘tramp metal’ is any item of rogue metal not naturally present in the mined ore or quarried aggregate. Such contamination includes digger teeth, pit props, blasting caps, nuts and bolts, and metal originating from the wear and tear at the process plant.
Stopping tramp metal damage
The nature of the rock, the process, and the tramp metal dictates the optimum metal contamination solution. The two technologies commonly used in mining and quarrying operations to prevent processing plant damage from tramp metal contamination are magnetic separators and metal detectors.
Magnetic separators
Magnetic separators parse magnetically-susceptible tramp metal (e.g., steel and iron), automatically removing the problematic contamination from the rock. Selection of the optimum magnetic separator design for any given application is determined by the process and material specifications.
Metal Detectors
Whereas magnetic separators find and remove tramp iron, metal detectors focus on identifying all metal contamination. The detection of metal occurs through the disturbance of a magnetic field produced by a metal detector’s coil. Detection of the presence of tramp metal sends a signal to the remotely located control. On receiving the signal, the control either stops the conveyor and initiates an alarm; sets off a diverter gate to reject a batch of material; or turns on the following overband or suspension magnet.
In many large volume mining operations, stopping the conveyor is not an option. In such installations, a section of metal-contaminated ore diverts into a collection area, where the rock is either manually checked for metal or sent through a separate secondary system for tramp metal location and removal.
Bespoke Engineered Solutions
The removal of tramp metal is often critical since damage to crushers, screens and conveyors disrupts and even stops production, at a huge repair and downtime cost. Failure to meet end-customer specifications for tramp metal content, especially in coal-fired power stations, may result in costly financial damages or even the rejection of shiploads of material.
For more information visit: www.buntingmagnetics.com
