APPLICATION REPORT | METALS
to steelworks. Barges on the waterway now have a capacity of up to 2,000 tons of scrap; to increase speed of loading them the company uses an LH 120 C Litronic machine with a 15m industrial-type angled boom, a 12m stick and a 2.5 cubic metre capacity grapple. A large, square- design crawler undercarriage allows a 7 ton load at the machine’s maximum radius of 25 metres. Once the scrap arrives at the foundry,
the next stage is moving it to the furnace. Konecranes agree with Liebherr on the joys, or reverse, of handling the material: “Scrap is difficult to handle. It has no defined shape for a hook or tong to fit onto, and it is often mixed, so it requires sorting. A scrapyard crane has to fit the size of the vehicles that deliver the scrap and must be able to access the right materials quickly from all parts of the storage area.” A speciality of theirs is overhead gantry cranes for the
purpose, installed at the foundry: “They are heavy-duty, high-speed cranes that can handle scrap in the yard and load it into buckets or ladles for transport to the melt shop. These cranes are equipped with lifting magnets, a hydraulic grab or both together to move a load of scrap weighing up to 40 tons.” We are now in the region of heat, dust and molten metal, and of cranes that can cope with those conditions. The scrap coming from the scrapyard is loaded in the furnace with an overhead charging crane. Its main hoisting machinery lifts the bucket to the furnace for melting, and an auxiliary hoist on the crane opens and closes the bucket during loading.
In most mills the scrap is added to iron
ore already in the furnace; from the initial furnace blast a teeming crane helps mix the molten metal in the right proportions. Once the mix and temperature are right
the liquid steel is poured into giant ladles carried by tundish cranes which carry them to the casting moulds when the molten metal is poured out to cool and solidify. The charging crane, ladle crane,
teeming crane, and tundish crane are all quite similar, say Konecranes, - usually overhead traveling cranes that are fitted with special attachments to lift the giant ladles - and can be defined by their location and function in the plant rather than by differences in design. They often perform more than one function and are used as backup for each other. Increased working coefficients, a differential gear reducer, redundancy in all critical systems, a backup brake on the rope drum, and motion limiters are just some of the technologies that are fitted. Overload protection, an ‘emergency
stop’ system bypassed from the normal control system, derailment supports, and end limit switches are standard features.
JASO THREE-GIRDER CHARGING CRANE FOR ARCELORMITTAL FRANCE
ArcelorMittal is the world’s leading steel and mining company, producing 71.5 million metric ton of steel a year. Recently ArcelorMittal France commissioned Spanish cranemakers Jaso to manufacture a scrap loading crane for its plant in Dunkerque. The crane, which is currently nearing commissioning, will transport the scrap and charge the converter with it. Its maximum load capacity is 300 tons with a span of 24.4 metres. It has a special and unusual an end carriage; the design provides the in the hot and rigorous environment of the converter. regenerative variators that allow the energy released during lowering of the load or returned to the grid. To protect the electrical equipment from electrically insulated and insulated also from heat; the enclosure is equipped with industrial air conditioning with redundancy.
The air system also pressurizes the inside of the enclosure to prevent the entry of steel dust through leaks or when it is accessed. In terms of safety, the crane will meet all the requirements of the Performance level D standard. It will have a ‘degraded’ or ‘emergency operation mode’ so that in case of failure of some of the equipment, the lifting and translation motions can continue to operate The latest data processing technology
conditioning, insulation for steel mill conditions and an electrically operated front glass protection system that comes loaded to avoid the impact of hot or hard access to all areas and equipment for maintenance while complying at all times with the customer’s safety regulations in terms of crane entry permits and the movement of people. commissioning in 2022.
www.hoistmagazine.com | October 2022 | 37
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