26.06.2008 | Editor: Marcel Dröttboom
Flexible bulk material containers are more in demand than ever as transport and storage containers, because containers like big bags have numerous practical advantages over packaging such as sacks, drums and metal containers, not only in terms of environment friendliness, functionality and price. But emptying big bags does not always prove easy.
Transporting, emptying and disposing of the containers is not always straightforward, and not always as successful as hoped with improvised solutions.
More than 2.4 billion tonnes of cement are produced per year. About 35% to 40% of this total is filled into bags, about 10% to 20% into big bags with a capacity of 1 t to 1.5 t. Before they can be processed on the building site, these diverse containers have to be discharged into the storage or working silos near the cement mixing plant – eliminating dust as far as possible. Since the big bags are too heavy to be emptied manually, an automatic big bags emptying plant is used.
The rate of big bag emptying and opening relates to the handling process on site. “We generally find it takes about three minutes to handle a big bag, i.e. to transport it to the emptying point, open it, empty it and dispose of the empty big bag”, says Horst Telschig, Managing Director of Telschig Verfahrenstechnik GmbH. So it is possible to empty about 20 or even 25 big bags an hour per station. With a capacity of one to one and a half tonnes, this makes a total throughput of 20 t/h to 30 t/h.
The big bags are transported to the emptying station using a forklift truck or crane to lift the big bags onto the discharge hopper. There is a big bag centring device mounted on the top to fix it to the discharge position. The big bag is then lowered onto the slitting blade under its own weight, and its bottom is slit open automatically. The opening diameter is 650 mm.
The big bag is gradually raised with slight vibration to empty it, then lifted off with a forklift or crane, and set aside. The effective discharge time of three minutes per big bag depends on local handling systems and the flow characteristics and quality of the product contained in the big bag.
The big bag emptying units comprise a lump breaker and a pneumatic conveyor to convey the discharged product straight to storage or working silos. The big bag emptying unit can be mobile or stationary. A third version omits the pneumatic conveyor. Bulk transport vehicles are filled with a fitted screw conveyor.
A special feature of Telschig plant and machinery systems is their multi-functionality. For example the various parts and components can also be used for all the other mineral raw materials that arise in the construction industry, such as lime, gypsum, fly ash, bentonite, micro silica, pozzolanic material, etc. It is also highly beneficial that all plant and machinery units are installed on the level (±0), which makes for rapid installation. Service and maintenance are also performed at ground level.
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