The sound of a single toggle jaw crusher mounted high on a hillside on a cloudy day can be heard from an extremely long distance.
While this may be music to the ears of a die-hard quarry professional, it can be the start of a lawsuit from those not so appreciative of quarrying and its value to the community.
Quarrying is one of the oldest industries in the world, a significant employer, and without it modern society would not exist.
{{image2-a:r-w:300}}It is a tough profession requiring professionals who are tenacious, innovative and run a tight ship. Whether corporate or private enterprise, the same problems exist, as they have in years past.
Conveyors are the main means of moving product in the crushing and screening process, and minimising damage to these belts has been the focus of managers and maintenance staff at all levels of the industry.
The key points of conveyors are belt type and construction, belt speeds, belt width, product size and specification, and conveying angle.
In addition, how the belt is loaded plays possibly the most important part in minimising belt damage. The primary crusher and how it is placed on the primary belt is perhaps the key to the rest of the conveying system.
{{image3-a:r-w:300}}It is not unusual to find crushers installed with insufficient distance between the jaw discharge and the conveyor belt. Several design faults may exist, such as the conveyor belt being too narrow, or rock boxes incorrectly positioned. The result may create bridging, blockages, spillage and no doubt damage to the conveyor belt.
Good crusher installation designs often use fines or small product (scalping) to place a layer of protective material on the belt prior to the primary discharge.
In some cases this is not possible, and therefore the dissipation of kinetic energy at the load zone is desirable for optimal belt protection (see Figure 1).
There are common causes of damage to belts, rollers and supporting structures:
1. Belt damage, eg:
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Wet, sharp-edged material cutting the conveyor belt cover.
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High freefall of material bruising and/or cutting belt cover and perhaps cords.
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Material not loading in centre on belt, causing high wear and belt tracking off.
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Poor wear plate and skirt design, causing belt edge damage.
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Material spearing holes in belt between rollers.
2. Roller damage, eg:
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Failing due to high impact.
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Rollers jumping out of frames.
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Premature bearing failure.
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Roller frames bending due to high impact.
3. Supporting structure damage, eg:
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Cracking under constant high impact.
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Distortion of support structure.
Resolving a problem
Contacted by an overseas customer seeking to resolve major belt, impact roller and structural damage, Leverlink was charged with the engineering and design task to resolve the problem.
{{image4-a:r-w:300}}The functional specifications were for a belt width of 2400mm, a trough angle of 45 degrees, a belt speed 4.5m per second, an output of 10,000 tonnes per hour, a material size of minus 250mm and a free fall height of 6000mm. The load zone was 2400mm in length.
Leverlink designed a multi-trough system (see Figure 2), according to the function specifications supplied. The design has a 10-year service life with replacement of slide media every 27 months.
The client was 100 per cent satisfied with the project, and is now seeking additional installations in its plant.
Over the years, Leverlink has enjoyed success designing and engineering solutions to particular problems, which has resulted in other benefits and cost savings. Just because something has traditionally been done a certain way, doesn’t mean there aren’t other innovative solutions.
A deflector plate is initially placed to profile material correctly on a belt. Leverlink succeeded in this task. Additional benefits were the wear plates almost doubling their service life compared with static units. In addition, solid borne noise was reduced.
The head chute is another location where wear and noise can be reduced (Figure 3). It may be impact or stream energy. Imagine if your motor car had no suspension. How long would it last? Is it worth considering?
Source: Leverlink Australia