Emphasizing safety around the wash plant

Bennetts

Editor’s note: The magazine originally published this content in March 2020.

While the nature of wet processing equipment inherently presents hazards that aggregate producers should be aware of, upholding a safe workplace environment ultimately comes down to maintaining the right safety mindset.

“For those who have taken their safety program and integrated it with everything else, the program becomes seamless with operations and maintenance because it’s part of their everyday life,” says Alan Bennetts, global product manager at McLanahan Corp.

In some cases, integrating safety with wet processing equipment means having regular conversations around it.

“We took the term ‘safety first’ at one operation I worked at and turned that into every meeting starting with safety, because it was of the highest priority,” says Bennetts, who spent 13 years on the operations side of the industry before joining McLanahan. “Every meeting would start with your safety concerns.”

Regarding wet processing equipment such as log washers, hydrocyclones and dewatering screens, slips, trips and falls are obvious hazards producers should look for.

“Spillage is not necessarily a hazard, but it is part of slips, trips and falls,” Bennetts says. “If you’re getting a lot of spillage, you are creating the slips leading to the falls.”

Operators must take housekeeping around wet processing equipment very seriously.

“The wet equipment doesn’t specifically cause huge safety concerns, but it can create an unsafe environment because of housekeeping,” Bennetts says. “Say you have a housekeeping issue and it’s wet sand: how do you clean it up? A lot of sites will take a hose and wash it toward a sump. But if you leave the hose out there, then you’ve created a tripping hazard.”

Wet processing equipment can, however, present hazards to operators and maintenance personnel. Here are a few things to be on the lookout for and consider:

With log washers, paddles and flights should periodically be inspected for wear and possible replacement. Photo: McLanahan Corp.

Hazards to look for

1. Log washers. With log washers, blade mills, aggregate conditioners, coarse material washers and fine material washers, operators should seriously consider utilizing optional guards to prevent accidents. 

In some cases, guards can even be retrofitted if dangerous access points are present.

“Unfortunately, guarding is seen as a hindrance a lot of the time,” Bennetts says. “On a maintenance level, guarding can be a time-consuming event and it makes the job last longer. A lot of the time, it may seem as if guards aren’t needed; that I’m not going to run my hand across there just because it’s open.”

No one purposely puts a hand in an unsafe area. Accidents, of course, tend to happen when people aren’t fully attentive.

“Most guarding is not set for normal operations,” Bennetts says. “It’s set for events that happen when you’re distracted.”

Also with log washers, paddles and flights should periodically be inspected for wear and possible replacement. With metallic paddles or shoes, worn ends can become sharp enough that they cause serious injury if not handled properly. So maintenance personnel should plan accordingly.

“There are glove requirements on the maintenance side, but the biggest thing you have to hit, especially with rotating equipment that has sharp edges, is the lockout/tagout procedures,” Bennetts says. “Do the testing before it starts up and make sure it’s truly locked out.”

2. Pumps. Serious injury can result from a bad pump installation, one in which solids settle out and an explosion occurs.

“Think of a pressure cooker that isn’t properly sealed,” Bennetts says. “As gases get hot, they expand, and that causes pressure inside the pump. When you get a high enough pressure, it can cause an explosion.”

Operators should fully utilize flow meters to ensure flow through a pump. 

“If you see a flow going off you can interlock it,” Bennetts says. “The other side of it is all of this has to be interlocked. If you [use] a heat gun on the bearing as a preventative maintenance practice, check the heat on the pump.”

Delamination and wear are two failure modes operators should always be on the lookout for with hydrocyclones. Photo: McLanahan Corp.

3. Hydrocyclones. Although these have no moving parts, two failure modes – delamination and wear – can affect performance and, in turn, the safety of a machine.

“If the cyclone is plugged up, then you’re going to end up deadheading the pump,” Bennetts says. “That goes back to the possibility of damaging the pump.”

Operators should also keep an eye on liners, as their deterioration means metal will eventually wear away.

“Wear away the metal, and then you have a housekeeping issue with slurry spewing all over the place,” Bennetts says. “You never know where the slurry is going to go. Perhaps it hits a motor, then you have an electrical problem; perhaps it sprays a person and puts them in danger; or it creates a slipping hazard.”

4. Dewatering screens. Operators should not only be on the lookout for sideplate cracks, but also motor wiring draped over vibrating motors. This latter development creates an extremely dangerous situation, according to Bennetts.

“If you have too long of a wire and it starts rubbing against something, then you have electricity running through,” Bennetts says. “You have a lot of connections. Even though the screen is isolated with a rubber buffer, you have this capacitor of electricity. Walking up and touching the equipment is not the most hazardous thing, but if you become the conduit then it becomes dangerous. Or, if it is connected and you’re walking through water.”

Final thoughts

Operators and maintenance personnel should consider all of these hazards as they go about everyday tasks. 

But as Bennetts addressed from the outset, working around wet processing equipment truly requires everyone to bring the right attitude.

For Bennetts, the most effective safety programs require three essential ingredients: an active role in safety, buy-in and communication.

“Those three things are key to enforce a good safety program,” he says. “You don’t want safety to be thought of as an extra chore, but as a general everyday task.”