Cargotec has received an order for a Siwertell ship unloader type ST790-D from the Indian Farmers Fertilizer Cooperative Ltd (IFFCO), Paradeep Unit. The enclosed screw-type unloader will be used to discharge rock phosphate and sulfur at a rated capacity of 1,800 t/h. "IFFCO wanted a totally enclosed system for both environmental and safety reasons," said Anders Paulsson, Sales manager, Bulk handling. "The company specified a screw-type unloader for high efficiency and chose a Siwertell system from Cargotec because we have by far the most knowledge and experience of this technology - the first Siwertell system designated for sulphur was delivered in 1980. Of the four main types of continuous unloaders - screw, pneumatic, chain and bucket chain - only the Siwertell screw-type has been demonstrated to solve the three main problems caused by unloading sulphur: a high explosion risk, extreme corrosion, and stringent regulations for environmental protection."
Cargotec's Siwertell Sulphur Safety System (4S) was developed to minimise the risk of explosions and detect fires. The 4S is designed to prevent sulphur dust explosions in the conveying line and to evacuate explosion pressure in case a dust explosion does occur, without causing damage to equipment and endangering the safety of operators, personnel and other facilities. To prevent explosions and fires, the Siwertell unit is equipped with nozzles that spray water at the inlet feeder and in the conveyor transfer points. An automatic lubrication system lubricates and cools down end bearings and intermediate bearings.
"Even with preventative technology in place, there are rare occasions on which an explosion occurs or a fire starts, so Cargotec has designed a system that reacts immediately upon detection and extinguishes any fire," Mr Paulsson said. "Fire detectors along the conveying line automatically stop the conveyors and start spraying water from the fire extinguishing system. To manage an explosion, the conveyor's steel casings are reinforced with extra-thick steel, and explosion-venting valves fitted along the conveyors and dust collectors relieve pressure."
A specially designed conveying line with stainless steel components ensures that a Siwertell unit is protected from corrosion and it is also practically maintenance-free.