How to make your wash plant safer

By |  February 20, 2018

With dewatering screens, be sure to look out for cracks in the side plate. Photo courtesy of McLanahan Corp.

Every wash plant should have clear safety guidelines that include best practices for the entire plant.

Safety requires a proactive approach 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 top priority in any maintenance task is safety. Review the conditions surrounding the maintenance tasks: What tools are required to complete this? Which employees are needed, and how many are required to do the job?

Are they properly trained on these procedures? What communication is needed with other operators? Conditions such as time of day, weather and area around the piece of equipment can all affect a maintenance task and affect everyone’s safety.

Keep your operators safe

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

Guards can sometimes be seen as inconvenient and are removed from a 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 guards need to be removed for maintenance, they should be put back in place before startup.

Warning decals are also put in place to keep operators safe. Keep warning decals clean and intact. Should an equipment warning decal become damaged, contact the manufacturer immediately for a replacement. Also, always be sure to check the integrity of all safety items before use.

Some tips to keep a safe site: walk your site daily, ensure training on proper lockout/tagout procedures, check guarding around equipment, and keep the site clean.

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

Keep in mind, too, that a torque multiplier may be needed if torque specs are higher than available tooling. Prior to such a procedure, check if lubricated or dry threads are used.

While lubrication schedules vary, check the quantity and type of grease or oil that is required. Also, be aware of the recommended frequency for lubrication. Is a replacement of lubricant needed after a fixed time following startup? Is that time frame based on environmental conditions?

Keep your grease fittings clean, too. This step should be obvious, but it is not always followed. Grease fittings should be cleaned before engaging the gun to lubricate your equipment.

Keep dirt and other foreign material away from oil-filling points, and be sure to inspect old lubricants for contamination. In some cases, a lubrication analysis should be made to trace contaminants associated with some failures leading to potentially unsafe washing equipment.

Keep your equipment safe

Be sure to watch for these things at your aggregate operation:

Scrubbers/trommels. In addition to proper lubrication, mounting alignment is very important to prevent permanent damage to tires and drives. Routine screen media condition checks for wear are also important.

The task of inspecting internal lifters and advancing/retarding paddles are just as important for production. 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 will be costly in your loss of production.

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

Screw and log shaft equipment have a common weakness: the lower bearing. Most manufacturers have different designs. Some are complex and feature a “submerged” bearing, and some 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 is important to be aware that worn ends become razor sharp. These ends can cause serious injury if not handled properly. Wear on these items and fasteners are important to check.

Occasionally, check the shaft for runout, as a bent shaft can cause premature failure of support bearings and even the shaft.

Pumps. These are at the heart of a wet process. Serious injury can result from a bad installation where solids settle out and an explosion can occur. Always consult the manufacturer when reinstalling or modifying an installation.

The correct selection of construction materials is critical to a 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 impeller wear.

Do not apply heat to any area of the pump’s impeller if trying to loosen it during maintenance. Serious injury or death can occur.

Hydrocyclones. While these 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 come loose due to wear or adhesion can 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, or spigot, is the fastest-wearing component. They 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 washout of deleterious fines.

Dewatering screens. Safer working conditions result from the use of dewatering screens with less carryback and spillage to clean up around conveyors. While they typically have a very long service life, there are still some areas to watch to keep your machine running safely and effectively.

Notice if cracks in the side plate occur. 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 as some vibrator motor manufacturers use special grease that, if not used, may void the warranty.

Final thoughts

It is important to make your washing site as safe 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 jobs.

Maintaining your washing equipment will keep it running longer. Ultimately, this will make your washing equipment safe to operate and be around.


Information for this article courtesy of McLanahan Corp.

Kevin Yanik

About the Author:

Kevin Yanik is the editor-in-chief of Pit & Quarry magazine. Yanik can be reached at 216-706-3724 or kyanik@northcoastmedia.net.

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