Sticky-coal problem at Hunter colliery solved with chute refurbishment that eliminates blockages

Wear plate being machined at T.W. Woods. The company provides wear plate kits for machinery and refurbishment services for coal chutes
Wear plate being machined at T.W. Woods. The company provides wear plate kits for machinery and refurbishment services for coal chutes.

A colliery in the Hunter Valley has successfully ironed out a sticking-point in its coal washery, thanks to a transfer chute refurbishment service provided by engineering company T.W. Woods Group.

The colliery had been attempting for some time to get a smooth flow of a type of clay-rich coal through its washery, but was foiled by earlier unsuccessful chute redesign efforts that left coal clogging up the chute that angles down from a feeder bin into another bin before the coal is washed.

"The coal wasn't getting through properly," said a maintenance spokesman for the colliery, which is an operation of one of NSW's underground coal producers. The washery is situated at the surface of the underground longwall coal mine.

"We'd had the chute taken out for refurbishment twice already, at a cost that makes me shudder. It still wasn't performing smoothly without the coal sticking.

"The transfer chute had gullies in it. T.W. Woods replaced all the working areas of the chute, remoulding and polishing them smooth for us. Now there are no hangs, no blockages. It's like a new pin and has been a big success from day one."

"This colliery handles two sorts of coal. One type is dry, the other is clay-like and sticky. The second type was causing all the trouble for us," explained the maintenance spokesman.

"T.W. Woods charged us just a fraction of our original major spend to solve the problem. The result is wonderful. I think we got the best deal on the planet.

"We've worked with T.W. Woods before, on jobs such as bin repairs. They're very professional and we have a close working relationship. Because they do such a good quality job, I would certainly recommend them to other companies like ours."

T.W. Woods' coal chute refurbishment and redesign service was introduced to help eliminate chronic problems in older chute types, including premature chute and conveyor belt wear, blocking and product spillage.

The service – which complements T.W. Woods' new smooth-flowing materials handling transfer chute business – applies to both underground and overland conveyor chutes used with mine and energy plant conveyors typically between 900-1200 mm with up to 1200 tph capacity. It also applies to chutes used by quarries.

Refurbishment componentry, including soft loading chutes in hood and spoon configurations, take advantage of advances in chute design over the past 10 years, as well as better and more robust materials, such as high-impact, extremely wear resistant chromium carbides, which make advanced hood and spoon designs possible.

"Many of the older plants around seem to be plodding on, unaware of the latest technologies and how they can help the flow of materials. The old chutes and conveyors are just patched up or repaired as they wear through," said T.W. Woods Director Mr Tom Woods.

"Such plants have a continuous problem with having to employ labour to clean the chutes out and to clean up the spillage they cause, costing time and money."

Faults in older chutes, mostly due to outdated design, include:

  • Blocking or hang-up due to fines, clay or sticky material being conveyed. This can be corrected with self-cleaning features.
  • High impacts at loading points on chutes, which wears holes because of the constant impact. T.W. Woods redesigns chutes to reduce the impact angle of the material. It also recommends chromium carbide material, which extends the life of the chute considerably.
  • Tight turns in the chutes that don't allow material to flow easily and not hang up. They also wear out the chutes.

"Some traditional mines baulk at the upfront cost of upgrading their chutes, but once a refurbished or replacement chute is installed, they usually go on to convert all their chutes over time. This has happened at quite a few mines in recent years," Mr Woods said.

T.W. Woods new and refurbished chutes have been employed by industry leaders in the Hunter Valley and nationally. The company's other products for mineshaft development include shaft liners, drilling tooling and wear plate materials, as well as custom-fabricated wear plate kits manufactured at the company's new plate processing facility for the maintenance of heavy machinery used in shaft development as well as bulldozers, trucks, graders and loaders.

The company's new technology includes low-height transfer chutes which feature a conical head developed by mining specialist designers to maintain high volume high flow rates (up to 2000 tons an hour) when conveyors change direction either underground or on the surface.