Safety practices to follow around washing, classifying equipment

Every wash plant should have clear safety guidelines that include best practices for the entire plant. Safety, after all, requires a proactive role to prevent workplace accidents.

Make sure you and your operators are trained in proper safety and maintenance procedures of your site, including washing equipment.

The number one priority with any maintenance task is safety. Review the conditions surrounding the tasks: What tools are required to complete this?

Which employees and how many are needed? Are they properly trained on these procedures? What communication is needed with other employees and contractors that may be on your site? Conditions such as time of day, weather and area around the equipment can all affect a maintenance task and, in turn, everyone’s safety.

Keeping equipment and operators safe

As part of routine maintenance, check safety guards and warning decals.

Guards can sometimes be seen as inconvenient and are removed from the machine to allow easier access to some components. These guards may not be put back on because operators lose the bolts and don’t bother to replace them.

Guards are intended to keep operators safe. If they need to be removed for maintenance, they should be put back before startup.

Warning decals are also put in place to keep operators safe, so be sure to keep warning decals clean and intact. Should an equipment warning decal become damaged, contact the manufacturer immediately for a replacement.

Always be sure to check the integrity of all safety items before use. Tips to keeping a safe site are:
1. Walk your site daily
2. Ensure training on proper lockout/tagout procedures
3. Check guarding around equipment
4. Keep the site clean

Some equipment, especially vibratory, requires re-torquing of bolts. A review of the manufacturer’s manual for this data is recommended. If missed, it can cause damage to equipment and possibly a loss of warranty.

A torque-multiplier may be needed if torque specs are higher than available tooling. Check if lubricated or dry threads are used prior to this procedure.

While lubrication schedules vary, check the quantity and type of grease or oil that’s required. Also, be aware of the recommended frequency for lubrication.

Is lubricant replacement needed after a fixed time following startup? Is that timeframe based on environmental conditions? Keep your grease fittings clean. This step should be obvious, but is not always followed. Grease fittings should be cleaned before engaging the gun to lubricate your equipment.

Additionally, keep dirt and other foreign material cleaned out from around oil-filling points, and be sure to inspect old lubricants for contamination. In some cases, a lubrication analysis should be made for tracing contaminants associated with some failures, which can lead to potentially unsafe washing equipment.

Don’t allow yourself to turn a blind eye to a hazard or an unsafe situation. Don’t allow yourself to say: “It’s not my job,” “I’m not the one who left it there” or “someone else will fix it.”

When doing inspection or maintenance, every worker involved should lockout. Never remove a lock until positive identification verifies all personnel are out of the area.

Every incident, accident or event should be investigated. Through investigations, recommendations can be made to improve safety and to prevent the event, incident or accident from happening again. It is vital these recommendations be implemented, otherwise sites are destined to repeat mistakes of the past.

Keeping washing equipment safe

Scrubbers/trommels. In addition to proper lubrication, mounting alignment is critical to prevent damage to tires and drives. Check liners and screen media condition for wear. Inspecting internal lifters and advancing/retarding paddles are just as important for production, because if their height is below a certain critical point, material will not rotate and interact effectively.

Allowing these paddles to wear away and not replacing them may save a few dollars upfront, but this may also result in unclean material. By taking these steps to maintain your scrubber or trommel, you are complying with safety regulations and ensuring a safe machine to operate.

Log washers, blade-mills, aggregate conditioners, coarse material washers and fine material washers. Order equipment with optional guards to prevent accidents, and add guards if there are dangerous access points.

The rear bearing assembly designs vary by manufacturer. Some are complex and feature a “submerged” bearing, while others are a simple outboard pillow-block with a rubber boot seal assembly. Each claim different advantages, but they all require lubrication.

Paddles and flights need periodic inspection for wear and possible replacement. With metallic paddles or shoes, it’s important to be aware that worn ends become razor sharp and can cause serious injury if not handled properly. It’s important to check wear on these items and fasteners, as the latter secure the wear parts to the shaft.

Occasionally check the shaft for run-out, as a bent shaft can cause premature failure of support bearings and even the shaft. Personnel should carry out shaft straightening, but only after consulting the manufacturer’s manual.
To assure proper lubrication of bearings, many manufacturers offer optional automatic lubrication systems, which are often inexpensive. These can assure more regular, periodic lubrication and minimize operator personnel exposure to a plant-operating environment.

Slurry pumps. These are the heart of a wet process. However, serious injury can result from a bad installation where solids settle out and an explosion can occur, so be sure to always consult the manufacturer when reinstalling or modifying an installation. The correct selection of construction materials is critical to long-term, cost-effective service life and safe operation.

There are three key areas in any pump: wet end, gland and bearings. It is important, particularly with open vane-style impellers, to check the clearance between the impeller and the suction side liner. Too wide a gap leads to bypass inefficiency and, in slurry pumps, accelerated wear.

Impeller wear should be monitored, as reduction in performance is most likely due to this factor. Do not apply heat to any area of the pump’s impeller if trying to loosen it during maintenance, as serious injury or death can and has occurred.

Hydrocyclones. While hydrocyclones have no moving parts, there are two failure modes – delamination and wear – that affect performance and could affect the safety of your machine.

Liners that become loose due to wear or adhesion cause disruption of flow inside the unit. This ultimately causes poor performance with misplaced particles.

Checking the internal lining of a cyclone should be done at least seasonally. This is particularly important when dealing with siphon (vacuum)-assisted cyclones/separators. The apex (spigot) is the fastest wearing component.

These are sized based on mass-flow. That way, as they wear, the underflow becomes more dilute and more fines will bypass into that stream, affecting the removal of deleterious fines.

Also, check the apex if your product is getting dirtier. Worn vortex finders can allow coarse fractions to short-circuit to the overflow and fill the ponds or contaminate the next stage of production. Worst case is wear can cause the pipe to detach from the plate, causing significant damage to your equipment and possibly injuring nearby personnel.

Dewatering screens. Safer working conditions result from the use of dewatering screens as they discharge a drier sand, resulting in less carryback and less spillage to clean up around conveyors.

While they typically have a lengthy service life, there are still some areas to watch to keep your machine running safely and effectively. For example, notice if cracks occur in the side plate. Trace the crack to its end with dye penetrant and drill a 1/8-in. to 3/16-in. hole. This most often takes care of the problem, and the side plate will last the life of the screen.

Cracks in cross members should be referred to the manufacturer immediately, as should any bolt breakage. Often, the problem with cracking in dewatering screens is the support structure rather than machine integrity.

Lubrication is a general maintenance activity, but take extra care because some vibrator motor manufacturers use special grease that, if not used, may void the warranty. Motor wiring that gets draped across a vibrating motor to the side of the screen and vibrates against adjacent surfaces is a very dangerous condition. Visually check this and replace the wiring as needed. Also, always check the direction of motor rotation on restarting after electrical work to keep your equipment running properly.

Final thoughts

It is important to make your washing site as safe, clean and productive as possible. By keeping your site clean and training operators on safety procedures, you are taking the steps to keep your site and operators safe while they perform their job.

Keeping your washing equipment well-maintained will keep your equipment running longer, and promoting cleanliness and safety everywhere in your plant helps send your employees home safe.

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Information for this article courtesy of McLanahan Corp.