Plastics play a pivotal role in mining applications, particularly UHMW (ultra-high molecular weight polyethylene) which provides desirable attributes that contribute a wide range of oem and custom parts in mining machinery and equipment including guides, belt scrapers, chain wear plates, skirt boardos, belt rollers, scrapers & wipers, liners & plates, idlers & pulleys, loaders, conveyor parts, bucket liners, impact pads, beds & bumpers, sprockets, agitators, as well as shoes & tracks.
In both surface open pit and underground mining operations, UHMW has become ubiquitous for its ability to solve issues related to sticking, holdup, bridging, friction, and heat. UHMW’s lubricity ensures speedy bulk material flow and movement, helping to lower energy requirements, deaden noise, and to make mechanical operations quieter in applications subject to rubbing and impact.
For both underground and open pit mining, UHMW helps with the drills and essential blasting tools used for breaking down and fracturing rocks and other materials by using a calculated amount of explosive or another blasting method (e.g. compressed air) to loosen the desired material from waste material. This process can create massive amounts of dust, hazardous rocks and “media blast” that create a safety concern for both workers and machinery.
Heavy duty mining equipment manufacturers have lined their machinery with UHMW as it is virtually unaffected by dust and dirt buildup common to mining, especially underground; and coupled with the ability of UHMW to handle strong impacts, major players in the mining industry see the plastic as the perfect candidate for blasting tools and any mining equipment involving wear parts. UHMW is utilized within machines and on the exterior of machines to handle waste material as well as the desired media being extracted.
On the outside of blasting machines, UHMW plates protect expensive machinery from rocks and unintended shrapnel. Three times as resistant as nylon 6/6, and over five times as resistant to abrasion as HDPE (high-density polyethylene) plastic and steel, a one-inch thick slab of UHMW is able to stop a .45 caliber bullet from 25 feet away. This level of protection stops flying rocks in their tracks.
After blasting, earth movers (machines designed for excavation) are normally used for removing overburden or waste material, which enables the excavators to remove the material or mineral of interest. Bulldozers are used to move this overburden material around to create a working surface for other equipment such as haul trucks and excavators. Earth movers and bulldozers require materials that can take abuse and extend the longevity of the machine, something UHMW easily provides.
Ultra-high molecular weight polyethylene is used as a lining material all around these machines, found on skid plates, skid shoes, rock panels (side skirts), and to line earth mover buckets or bulldozer blades. One can also find UHMW many times lining the push frame, and even the cab enclosures and rippers. Other parts lined with UHMW include dragline buckets, shovels, hoppers, scrapers and loaders.
Ensinger’s Tecast® (cast nylon type 6) is another plastic used in the industry, which helps to allow a “bogey” or cart to move inside of tunnel boring equipment. This bogey moves on a track allowing components to push forward inside of this massive equipment.
After the desired media or material is extracted, it is generally put on dump trucks with a UHMW belly pad lining that sits between the box and the frame. The industry has started to phase out polyurethane and rubber from this application, where UHMW has shown much longer part life.
Dump trucks deliver the mined material to feeding and conveying equipment, necessary to move and control material flow within mining processing to facilitate efficient operation of equipment and determine operating rates and yields. In some instances secondary crushing is required prior to processing of the material. UHMW’s low friction properties greatly assist in keeping material flowing at a high feed rate, increasing productivity and ultimately greater revenue for mining companies.
Due to its low coefficient of friction, high tensile strength, great wear properties and strong impact strength, UHMW works exceptionally well for wear pads bolted on the tracks of excavators. Replacement is convenient with long part life, making UHMW wear pads suitable for pavers, milling machines and bitumen (asphalt) transportation trucks.
Federal agencies have placed strict restrictions on emissions for on-site mining processing, cutting back or even halting production if emissions are too high. Heavy duty mining equipment manufacturers have come to the rescue, utilizing UHMW as a key component in lowering emissions in screening plants, dust collecting machinery, conveyor transfer points, assay labs as well as primary, secondary and tertiary crushing equipment. Ultra-high molecular weight polyethylene can be seen on dust collector inlets, disposal pipelines, pipe & chute liners, impact beds, as well as conveyor rollers, idlers, belts and guide rails.
UHMW becomes especially useful in cold and wet weather where many materials would become frozen and stick to conveyor systems and belts, as well as any other processing equipment. UHMW is the perfect barrier between metal and nearly any mined material in commercial applications as it does not freeze-bond allowing for quick discharge times.
Many coal mining and ore mining operations have switched from using stainless steel for linings and hoppers, instead choosing UHMW as it greatly reduces heat buildup due to friction. Many coal and ore operations have reported increases of 10-15 times greater service life over metal.
Drag bucket liners easily release product and overburden in wet or freezing conditions; this results in higher bucket output and lower energy costs. Slurry pump parts and pipe liners made of UHMW reduce wear on parts and pipes, increase flow, and cut energy requirements.
Even under ideal conditions, metals many times lead to processing issues that can easily be solved with ultra-high molecular weight polyethylene.
One example we have seen is with diatomaceous (soft, siliceous sedimentary rock) processing plants that have experienced constant issues with their equipment’s metal vacuum lines. The lines would rip due to the abrasive nature of the minerals. This was extremely concerning as the vacuum recaptured hazardous powder during the bagging process. Human exposure to the powder is a great health risk and these metal elbows would only last one month before failing.
UHMW tubing was a perfect fit to replace the metal tube, and its extreme abrasion resistance helped part life, worker safety and production through greater up-time and lowered maintenance costs. After three months, the UHMW replacement was still fully operational showing little to no wear; three times longer than the time it would have taken to destroy a metal tube.
A leader in manufacturing of industrial air-operated double diaphragm (AODD) pumps, utilized UHMW for valve seats and ball stoppers in their pumps, which are extremely vulnerable to wear. UHMW provides the best mechanical strength and abrasion resistance for the job, helping AODD pumps handle flow made up of over 90% solids.
This piece only touches the surface of the potential that plastics (specifically UHMW) have for helping the mining industry reduce emissions, increase production, save money and keep workers safe.
The key to growth for mining operations comes in increased understanding of the capabilities of plastic materials to match specifications needed for mining industry applications. Understanding the benefits of plastics, many industries have proved that UHMW is a superior choice next to steel and other traditional materials. UHMW will soon be the standard for safe, cost-effective, and longer lasting solutions for many of the challenges faced by the mining industry.
Benefits of Plastics for Mining Applications
- Extremely impact and wear resistant
- Longer part life
- High corrosion resistance
- Direct replacement of OEM parts (identical part designs)
- Cost effective/reduced costs over stainless steel
- Lightweight (15% the weight of steel)
Popular Products for Mining Applications
- Power Transmission Components
- Conveyor Lining Material
- Blasting Equipment and Heavy Machinery Lining Material
- Conveyor Tracks & Chain Guides and Wear Strips for reduced damaged runs
