Published online as part of World Coal's Handling Week, Eric Yan, Eriez Flotation Division, and Jose Marin, Eriez Minerals and Materials Processing, USA, detail technology developments that can facilitate ways to
Today’s mining operators strive to get maximum return from existing mines. In this challenging environment, mine management must consider methods to improve efficiency, increase productivity and obtain more from existing mines. Building new mines is not an option in most locations across the globe. The following outlines three trends that provide opportunities to increase profits, improve quality and
Figure 1. Double Team: a suspended magnet and metal detector offer the highest level of protection to conveyor belts and crushing equipment.
Using suspended magnets and metal detection to remove damaging tramp metal
Mine operators find they can eliminate plant downtime by properly installing suspended magnets in combination with metal detection equipment for removal of tramp metal. It has been proven that the combination of suspended magnets and metal detectors outperform the use of magnets alone. The reason for this is that not all tramp metal is ferrous.
Pairing Eriez metal detectors with magnetic separators
Neither a metal detector nor a magnetic separator is 100% effective in removing tramp metal on its own. The Double Team combination results in as close to a perfect product protection as possible.
Working in conjunction, the magnet removes the ferrous materials, while the metal detector focuses on any ferrous missed by the magnet, as well as nonferrous metal, e.g.
Figure 2. A properly installed wet drum starts with a uniform feed across the width of the feed box.
To avoid expensive equipment damage and costly downtime, it is important for mining operations to detect and eliminate foreign objects. Available in models to handle a wide range of applications, mining metal detectors detect both ferrous and
From detecting medium and larger ferrous and nonferrous particles
The detection system operates by measuring the change in received electromagnetic signal of material being conveyed through the sensor area. Since the magnetic properties of a material are completely independent of conductivity, both magnetic and nonmagnetic tramp metals are consistently detected. The combination of suspended magnets along with a metal detector provide mine operators additional assurances that neither ferrous nor
Applications of suspended magnetic separators
When addressing the magnetic collection of tramp metal, the suspended electromagnet (SE) is the industry workhorse. The SE magnet, providing tramp metal collection of conveyed materials, is a widely used magnetic separator. The electromagnet is mounted or suspended over a conveyor belt (Figure 1) to remove relatively large pieces of tramp metal that represent a potential hazard to downstream crushers, mills,
Figure 3. A high-capacity flotation technology called StackCell® offers considerable savings for new installations and is ideal for expanding capacity in an existing plant.
Magnetic circuit design
There have been recent technological advancements in the design and
The SE magnet removes ferrous tramp metal from moving conveyors to protect downstream equipment, such as crushers, mills, shredders and presses. The largest market for SE magnets is in coal mining, hard rock mining and aggregate products, removing shovel teeth, cable, tools and bolting before crushing and grinding. A large piece of ferrous tramp metal, such as a shovel tooth or rail track, will not yield in a crusher and may damage the drive system. In the worst case, the crusher shaft is bent requiring complete replacement. Not only is this type of repair costly, it also results in significant downtime.
The foremost factor in SE magnet selection is the burden depth of the material on the conveyor belt (note that the belt speed, belt width, capacity and bulk density all are factors in the material burden depth on the conveyor belt). The burden depth determines the suspension height of the magnet and consequently the effective magnetic field strength at the belt surface. Conveyor belt idlers elevate the edges of the belt forming a trough. The effect of idlers must be accounted for in the burden depth, which determines the suspension height of the magnet and consequently the effective magnetic field strength at the belt surface. Conveyor belt idlers elevate the edge of the belt forming a trough.
SEs are available in manual cleaning styles and self-cleaning styles. Manual cleaning magnets are best suited to applications where only small amounts of occasional pieces of tramp metal are present. The manual cleaning magnet must be periodically turned off in order to remove tramp iron accumulation from the magnet face.
Self-cleaning magnets employ a cross-belt running around the magnet face to provide continuous removal of collected tramp. When tramp metal is attracted to the magnet face, the cross-belt intercepts it and discharges it to the side away from the conveyor belt. The self-cleaning magnet is best suited to applications where a high level of tramp iron or large pieces of tramp iron is anticipated. A ? in. thick cross-belt is standard. The cross-belt is continuously driven around the magnet on a system of four pulleys driven with a small gear motor. Optional cross-belts using thicker ply belts or
Optimising magnetite recovery in heavy media
The Eriez self-levelling wet drum magnetic separator represents the newest available technology. This separator combines the top engineering and operational features and provides excellent performance and easy operation,
The concurrent and the conventional counter-rotation tanks have a
The self-levelling wet drums feature ease of operation, as well as a 950
In the past year, the popularity of the self-levelling wet drums has produced such a great demand for replacement drums that Eriez now offers multiple units for expedited delivery. The most typical drums for this application are the 36 in. and 48 in. models.
This is an excerpt from an article that was first published in World Coal October 2016. To register and receive your free trial of the magazine, click here.
Read the article online at: https://www.worldcoal.com/handling/30032017/minimising-downtime-maximising-efficiency/
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