Flexco: From rip to repair

Mechanical belt fasteners offer a quick and easy fix for damaged conveyor belts but it is important to ensure they are matched with the correct belt cleaner selection. Australian Mining writes.

Longitudinal conveyor belt tears and damage can cause significant downtime issues for mining operations.

Whether caused by foreign materials such as sharp ore, general wear, or issues with the construction of the conveyor itself (such as belt mistracking), a ripped belt results in costs for repair or replacement, as well as lost revenue from associated down time.

Site personnel traditionally repair rips in one of two ways: vulcanisation, a process where rubber is applied to the splice under high heat and pressure to form a strong and seamless join; and mechanical belt fastening, where fixed or hinged fasteners are used to close up the rip in a stitch-like fashion.

Both methods have advantages and disadvantages. Vulcanisation tends to produce a stronger and longer lasting repair but requires much more downtime to implement. Mechanical belt fastening is a much quicker fix that can be completed in house and will provide an equally strong join — however, this join will need to be replaced more often.

An additional benefit of mechanical fastening is that minimal tools or training is required to apply the repair, whereas vulcanisation may require specialised staff and an expensive vulcanising press.

In fact, mechanical belt fasteners are considered so easy to install that they find application not just for repairs but belt installations as well, especially in underground longwall mining where belts are often extended or retracted as per user requirements.

“To put clips in is quick,” explains Flexco territory manager Phil Dreghorn, who has been with the company for 15 years overseeing operations in Queensland, the Northern Territory and Papua New Guinea.

“It saves time, and the less time you take and less labour you use the more savings you get. Vulcanisation could take 12 hours whereas a clip could take two hours.”

Fasteners are generally hinged or solid in nature, with the former more commonly used for belt repair in the quarry and aggregate fields, which see a higher proliferation of material sifting.

Flexco provides a range of hinged and solid mechanical belt fasteners as part of its range, which includes wire hook fasteners, staple fasteners, rivet-hinged fasteners, solid plate rivet fasteners and bolt fasteners (among others), with each type suited to belts with particular ranges of thickness and pulley diameters.

“We have manual tools and automated tools for fastener installation, so they can be installed through hydraulics or pneumatics”, says Dreghorn.

“If you don’t have access to the automated tools then we can still install the fasteners manually with a hammer or applicator. We do carbon steel through to stainless steel and have a wide range of clips across industries such as quarries, food grade, aggregate mining and heavy mining industry. There’s a fastener for every application.”

According to Dreghorn, mechanical belt fastening is the preferred option for operations where continual throughput is the top priority.

However, mechanical belt fasteners can clash with tungsten tip (V-tip) belt cleaners when the belt is in motion. This interface can cause damage to both the tungsten tip and fasteners.

To counteract this potential damage, the tips of the belt cleaner can be retrofitted with polyurethane blades, and the top belt cover removed or skived to lower the profile of the fastener.

“The other option is to replace the tungsten tips with C-tips (a softer tungsten encrusted in tool steel). V-tips are noted for their long wear life, and C-tips are not as prone to shattering when the interface with the clips. The C-tips are more commonly used on secondary belt cleaners.

Polyurethane tips can be supplied in fire-resistant, anti-static (FRAS) for underground coal mining and other potential combustible environments. Natural polyurethane is commonly used for surface mining.

A belt cleaner’s primary role is to remove carryback from the conveyor belt. If this carryback is not removed, it can lead to loss of product, roller failure and belt misalignment. This exposes the site personnel to unnecessary and unplanned maintenance and potential safety incidents.

Product falling on the ground also takes time to clean, and can lead to not just lost material but housekeeping and environmental problems as well.

A combination of the right fastener with the right cleaner can massively reduce these issues.

“Primarily we would use tungsten tips, but when a fastener is introduced to the belt we use polyurethane,” says Dreghorn.

“We also have one-piece poly blades and segmented blades — segmented blades tension individually, allowing blades to conform to belt profiles and keep constant tip-to-belt contact across the entire width of the belt.”

This article appears in the February 2019 issue of Australian Mining.

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