Consistent use of silo cleaning equipment can turn into an economic benefit for an operation – an investment rather than an expense.
Most cement plants have a bank of storage silos to hold finished cement in inventory until required for packaging or bulk shipping. Storage silos allow cement plants to stockpile inventory until needed.
Buildups on the vessel walls can rob plants of the storage system in which they have already invested. These buildups slow material flow and decrease the “live” capacity of the vessel. Overcoming these flow problems and recovering storage capacity may require silo cleaning.
Safety first and always
Cleaning a vessel from below should never be attempted. Poking from the bottom up inside the silo with a pole or pipe is dangerous. The safe way to clean out a storage vessel is to work down from the access opening on top of the structure. This does not mean lowering a worker into the silo – a violation of confined space entry rules, and a significant safety hazard.
It’s desirable to have a cleaning method that works inside the vessel, but is controlled by personnel on the outside of the vessel. There are several types of silo cleaning equipment that can be used for this purpose – our favorite is the Pneumatic Bin Whip Silo Cleaner.
A pneumatic bin whip silo cleaner is a portable, remote-controlled tool that can be lowered into storage containers through a manhole opening. Powered by compressed air, a patented pneumatic motor uses a variety of whips and cutting edges to knock down even the toughest materials without damaging the walls of the storage bin.
Strategy and tactics
Before any using silo cleaning equipment, it’s important to ensure there is a path for loosened material to leave the vessel through. The discharge opening must be clear and there should be a takeaway mechanism at the bottom (a conveyor, truck, end loader, etc.) so large quantities of material are removed from the walls and the fallout does not build up below the discharge to the point where it blocks the opening.
When cleaning from the top of a vessel, start at the bottom of the buildup and work upwards. The wall accumulation is undercut until it falls by its own weight. This undercutting technique risks the occasional submerging of the silo cleaning equipment whip head in removed material. Generally, the falling material will push the suspended cleaning head out of its way. If the cleaning head does become buried, wait for the material to feed itself out of the vessel, uncovering the whip head from the bottom.
If the material is hung up or bridged to a “no flow” condition, a special power lance drill can be used to open a hole through the material. This becomes a channel for the loosened material to flow through. The pneumatic bin whip can then be used to finish the cleaning.
Benefits of silo cleaning
The cleanout of finished cement storage can bring several benefits to a cement plant, including the recovery of material and storage capacity. At one cement plant, the cleaning crew was able to remove enough “lost” material that the value of the recovered material paid the cost of the cleaning. In fact, the cement company made money on the sale of recovered material in addition to the benefit of regaining its storage capacity.
Hung up, clogged, or slow running silos are a problem that interfere with efficiency and profitability of a plant. It’s possible to keep materials flowing freely by removing buildups from silo walls with safe, effective, and regular silo cleaning.
We often tell our customers the best way to prevent a major problem is to address a minor one. A consistently scheduled bin cleaning program is the best defense against major, costly problems. It’s equally important that silo cleaning equipment operators are properly trained, and experienced, with the skills to use the equipment properly.
Article adapted from “Removing Material Buildups from Finished Cement Storage Silos” by Andy Marti.
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