Plastic Pallet Manufacture – How Do You Store the Raw Material?
13 Apr 2015
Silos are a common sight on large farms or along docks and are used for storing grain. Quarries and cement works have refined the safe use of silos for their produce and raw materials. Now it’s the turn of plastics to be stored in towering silos.
Plastic raw materials are usually in the form of granules and powders. These could be polyethylene and polypropylene, which are used in the manufacture of plastic pallets. Other types of plastic granules include ethylene vinyl acetate (EVA), polyvinyl chloride (PVC) and polycarbonate resins.
Plastic Pallet Demand Grows
Demand for plastic raw materials has surged together with the demand for plastic pallets. Plastic is regarded as a stronger and more durable material for pallets than the traditional wood. It can be easily cleaned and does not harbour moulds, pests and pathogens in the same way as wood. Plastic pallets have become the shipment units of choice for the food, pharmaceutical and electronics industries, as they combine strength with durability and cleanliness.
Plastic pallet manufacturers have to design production plant to meet this surging demand. They also must ensure that they have a safe and cost-effective method of storing the raw materials prior to their use. The storage must fit in with their continuous production processes.
This is where the aluminium silos come in. At over 20 metres in height and weighing more than six tonnes, they are able to store up to 150 tonnes of plastic granules and powders. They can cost £350,000 each, but once transported to their final site, they can be erected within five days.
Building the silos is only part of the story for the pallet manufacturer. They have to be aware of the hazards posed by polyethylene and polypropylene granules once they are in storage. The hazards include filament streamers that are created when plastic pellets rub against each other. The streamers can block outlets, filters and feeders in the silos.
Any amount of particulate material will generate dust and more fine particles. If not controlled, these could grow into a dangerous dust cloud that could cause an explosion. The workforce is also in danger of developing breathing problems associated with escaped dust.
All of the plastic granules will also generate static electricity. Although the amount of electricity generated may be large, plastic has a high electrical resistivity and so acts to prevent a discharge. But if any metal element in and around the silo becomes charged from the static electricity stored in the plastic, a single spark could cause a major electrical discharge.
Loading and Unloading
Care has to be taken during loading and unloading as well as haulage of the raw materials. Employees should wear protective clothing, including safety shoes and eye goggles, when working with materials. The loading and container area should have a flat and level surface.
Only trained and experienced staff should be employed when moving loads. There should be an exclusion zone around the trucks and containers that are moving material into the silos.