A concrete ready-mix facility in the United States Pacific Northwest is using a McLanahan Fine Material Screw Washer for recycling concrete washout for reuse in its batch plant.
The producer wanted a more sustainable solution for managing its concrete washout and was looking for a way to recover the aggregate and water from the slurry instead of disposing of it in a landfill.
“Our goal was to reap the rewards of the sand and gravel and the water out of it,” said the superintendent of the ready-mix facility. “We figured it would be better to recycle that back into the production of concrete than it is to stick it in the landfill.”
Solution
The ready-mix facility team researched the equipment options that would allow them to best meet their site’s sustainability goals.
“McLanahan has a reputation in the industry,” the superintendent said. “We all decided as a group that this is going to be the best unit for us, then we reached out and McLanahan has been very on board with what we’re trying to do.”
The facility installed a McLanahan 36” Double Fine Material Screw Washer for separating out the sand and gravel for further processing.
“It’s a team effort where you look for a machine that is employee friendly, user friendly, driver friendly, environmentally friendly, maintenance friendly and on the bottom end of it, you get a quality product out of it,” he said. “The McLanahan hits all those marks.”
When trucks return with leftover concrete, or when they are being washed out at the end of a shift, they empty the material into a trough that feeds the McLanahan Fine Material Screw Washer. Sand and gravel settle out of the water in the washout and are conveyed up the spiral screw flights to be discharged onto a conveyor to take it to the next stage of the process. The subsequent stages of the process separate the sand and gravel and wash it ahead of stockpiling. All the water is processed through liquid solid-separation equipment to further remove fine solids so that the water can be reused on site.
Results
With the McLanahan Fine Material Screw Washer as part of its concrete washout recycling system, the ready-mix facility is recovering an average of 2,500 – 4,500 tons of sand and gravel a month.
“That’s 4,500 tons of material that’s not going into a landfill,” said the superintendent.
Besides the environmental benefit of diverting waste destined for the landfill, recovering the aggregate from the concrete washout has additional benefits to the company. The facility is able to reuse the recovered sand and gravel in its ready-mix product. Additionally, the facility is also able to reuse the water recovered from the process for truck washout, batching, concrete, etc.
“You want to utilize all the material that you’ve mined out, and if you have an opportunity to recycle that back, it just benefits everybody involved,” the superintendent explained.
Recycling the aggregate also extends the life of the company’s sand and gravel pits.
“I’m not putting burden on my pits to supply me an extra 6,000 tons a month, which in the aspect of reserves, it just stretches a pit out, and permits for pits are hard to come by,” the superintendent shared.
The superintendent said the McLanahan Fine Material Screw Washer is a “tremendous benefit” to their operation.
“I’m getting the maximum amount of material off of it that we’re putting into it,” he said. “The recycled sand has a tendency to be super coarse, but the McLanahan Fine Material Screw Washer really takes the bottom end and keeps it in the material, which is a major benefit to us.”
In addition to recovering the maximum amount of material, the McLanahan Fine Material Screw Washer provides a quality product.
“The sand and gravel come off the screw very clean,” the superintendent said. “Then we double wash the sand, and we wash the gravel, so the material that’s coming off it is quality material that we have the opportunity to blend back in with our daily production without jeopardizing gradation, quality, strength -- any of the importance of concrete production.”
In operation since 2021, the superintendent said the McLanahan Fine Material Screw Washer is “super-efficient” and “self-sufficient”.
“It’s super maintenance free. It’s employee friendly. I don’t have a lot of man hours in regard to cleaning it, to maintaining it,” he said. “It does everything we ask it to do, and it does it very well.”