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TECHNOLOGIES, EQUIPMENT AND AUTOMATIC
CONTROL SYSTEMS FOR THE PROCESSES OF STEELMAKING
TECHNOLOGIES AND EQUIPMENT FOR SLAG CUT-OFF DURING THE PROCESS
OF STEEL TAPPING FROM THE MELTING UNITS.
The cut-off of the final technological slag during the process of steel tapping from the melting units is a topical problem, taking into account the wide use of the metal working techniques on the "furnace-ladle" plants. The success of the indicated problem's solution depends on the technical potentialities of the enginery, ensuring slag-free steel tapping into the steel-teeming ladle.
Within the framework of scientific and technical collaboration with Donetsk National Technical University (DonNTU) and the JSC "Novokramatorsk Engineering Works", the RPC "Donix" works out, produces and introduces into operation high-performance devices for the slag cut-off during the process of steel tapping from basic oxygen converter furnaces, open-hearth and arc steel-making furnaces.
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For the conditions of converter steelmaking two methods were worked out to prevent the ingress of the large quantity of slag melt into the steel-teeming ladle.
According to the first method a slide gate, which overlaps the outlet port at the moment of the slag appearance in the metal flow, is installed on the basic oxygen converter furnace body.
Unlike the popular foreign analogue - the water seal, used on the basic oxygen converter furnaces of "Salzgitter AG", - the offered slide gate is equipped with the electromechanical drive. The design of the drive and of other gate elements makes the unit simple to produce, ensures its low cost and error-free performance under the conditions of dust loading, high temperatures and mechanical loads.
The present system for slag cut-off is recommended for the use on the furnaces with the ratio of the height to the diameter within 1,6 - 1,8.
The second method is based on the use of special cut-off devices made of refractory in the form of floats, immersed into the melt bath by means of the manipulators of original design.
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The system of the slide furnace gate, the design of which has a few fundamental differences when compared with its foreign analogues, was worked out to ensure a more effective slag cut-off during the use of electric arc furnaces.
The designed gate was equipped with a more reliable double-plunger drive hydraulic cylinder (instead of a piston one) and balancing clamping elements for the movable yoke with the roller bearings. This design ensures controlled bottom steel tapping without the furnace body rotation, error-free performance of the gate even if the refractories wedging exists, as well as allows to reduce rubbing surfaces deterioration and to diminish drive load.
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To optimize the slag-free steel tapping from the open-hearth furnaces we offer to use special spouts with partitions, which ensure effective hold-back of the slag and its removal into the tank placed near the steel-teeming ladle.
The suggested design of the spout ensures a high degree of the slag cut-off, irrespective of the condition of the metal notch of the open-hearth furnace. The levels of slag raising in the receiving part of the spout and at the bottom of the lip, through which the slag is coming to the bowl, are controlled by means of changing the position angle of the spout gate according to the mass flow of the metal which runs out of the furnace.
The described systems and equipment can be efficiently used at the steel-making plants of the metallurgical and engineering works.
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