SU1271891A1 - Method of blowing metal with oxygen - Google Patents

Abstract

The invention relates to ferrous metallurgy, specifically to the smelting of steel for various purposes in arc furnaces using the oxidation of impurities with gaseous oxygen. The purpose of the invention is to reduce the time for purging the metal with oxygen and reducing the wear of the lining of the slopes and walls of the furnace. The metal is purged with oxygen through a vertical tuyere located at the rear wall of the furnace; moreover, during the first 30-50% of the time the metal is blown, the depth of the metal bath in the oxygen supply zone is increased and the slopes and walls are removed from the zone by successive inclination of the furnace towards the rear. walls at an angle of 4-20 from the vertical, then reduce the oxygen supply rate by 10i 25% from the initial one and return the furnace to its original position, and the subsequent (8-20% of the time spent purging is carried out when the furnace is tilted towards the front wall 3-7 at an angle from the vertical. The method allows to increase productivity, reduce costs, and the time of filling materials of the hot furnace downtime. Table 1.

Description

one

The invention relates to ferrous metallurgy, and more specifically to the smelting of steel j for various purposes in arc furnaces using the oxidation of impurities with gaseous oxygen.

The purpose of the invention is to reduce the time for purging metal with oxygen and to humiliate the lining of the slopes and walls of the furnace.

During the first 30-50% of the time the metal is purged with oxygen, the arc furnace is tilted towards the rear wall at an angle of 4-20 from the vertical, i.e. towards the zone of oxygen supply to the metal surface. This technique allows for the initial purge period, i.e. with high carbon content in the metal, significantly increase the intensity of the oxygen input and do it without damaging the back wall and furnace slopes, because when the furnace with a fixedly fixed tuyere is tilted, the depth of the liquid bath under the tuyere nozzle increases, the slopes are covered with a layer of liquid metal, and the flame goes from the slopes and the back wall to the center of the furnace.

The use of these techniques reduces the cutoff distance of the tuyere - the surface of the liquid metal and, thus, increases the gas-dynamic effect of the oxygen jet on the metal, to a greater extent cover the furnace slope opposite the oxygen inlet zone with liquid metal and remove the back wall of the furnace from the oxygen input zone as a result Which reduce the destruction of the furnace lining. 5 These techniques reduce the duration of metal decarburization of the metal with oxygen, the degree of saturation of the metal with nitrogen from the furnace, and the destruction and wear of the slopes and back, steel APIS furnace. In addition, it is possible to increase the oxygen consumption and, thus, reduce the time required to obtain a given carbon content.

. Based on the characteristics of arc furnaces of various capacities and the data obtained during pilot testing of the proposed method, it was found that when the metal is purged of oxygen with an average of 18 minutes, the optimum time of inclination of the furnace during blowdown is 5.49 minutes, which is 30- 50% of the total

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purge time. Reducing this time to less than 30% results in a limited effect on the consumption of refractories and 5 reducing the purge time, and increasing this time by more than 50% does not allow for an additional reduction in the metal purge time. Inclination of the furnace towards the rear wall

10 ki less than 4 does not lead to a significant reduction in the consumption of refractories for refueling the rear wall and slopes, since they are not much removed from the purge zone, and tilting (5 furnaces more than 20 in the direction of the rear wall make it impossible for the exhaust gases to catch suction and cleaning, which drastically degrades the ecology of the steel-smelting shop, and 20 when operating furnaces with water-cooled panels leads to metal contact with the rear panel of the furnace, which is prohibited due to safety considerations,

25 A decrease in the intensity of the introduction of oxygen by less than 10% leads to an increased inhibition of iron and the destruction of the slopes and walls in the region of the input of oxygen. A decrease in oxygen of more than 3Q by more than 25% from the original leads to a lengthening of the period of decarburization of the metal due to a decrease in the rate of decarburization.

In order to combine the operations of slag descent and metal purging with oxygen, it is recommended to tilt the furnace towards the front wall. When the furnace is tilted by less than 3, the time of descent is lengthened, and when the furnace is tilted more than 7 times from the vertical, the loss of metal descending along with the slag increases. The slag descent time, which is less than 8% of the total purge time, is insufficient for large slag multiplicity, and the descent time, more than 20% of the total purge time, leads to additional metal loss during the slag descent.

Claims (1)

Example. When smelting steel 35GS in a 100-ton arc furnace, steel is blown with oxygen by supplying gaseous oxygen through a vertical water-cooled lance installed at a distance of 600 mm from the rear wall of the furnace. The tuyere is attached to the portal of the furnace. It has the ability to move vertically. 3 Install a tuyere cut at a distance of 400 mm from the surface of the bath and supply oxygen to the fu, rm, with a flow rate of 1800. During the first 6 minutes, the furnace is tilted 12 ° from the vertical towards the rear wall by successively tilting the furnace at an angle of 4, 6, 8, 10 and 12 from the vertical, then reducing the oxygen supply rate by 20% from the initial one. at 360 m / h, setting the flow rate at 1440 m / h and for the next 6 minutes, the melt is blown at a flow rate of 1440 m / h and successively (at an angle of 12, 10, 8, 6, 4) return the furnace to its original state (vertical) . The duration of the metal purging with oxygen is reduced by 5.5 minutes, the specific consumption of magnesite powder for filling slopes by 1.7 kg / ton. Hot stoppage downtime due to refueling slopes is reduced by 4%. The table shows the comparative characteristics of the proposed and known methods. The proposed method of metal purging with oxygen in high-power arc furnaces leads to a reduction in the purge time 14, the consumption of refilling materials, and the stopping time of hot furnaces. The invention of the method of purging metal with oxygen in an electric arc furnace, comprising supplying gaseous oxygen through a vertical tuyere installed at the rear wall of the furnace, characterized in that, in order to reduce the time of purging metal with oxygen and reduce wear of the lining of the slopes and walls of the furnace, During the first 30-50% of the purging time, the depth of the metal bath in the supply zone of the horticom cyst increases and the slopes and walls are removed from the zone by successive inclination of the furnace towards the back wall at an angle of 4-20 from the vertical, after reducing the flow rate of oxygen at 10-25% of the initial furnace and returned to the original position, and the last 8-20% of the time the purge is performed at the furnace is tilted toward the front wall at an angle ° from the vertical. With metal purge no inclination of the furnace, O (by a known method) with a stove incline of 3 from the vertical with a stove incline of 22 from the vertical With metal blowing when the furnace is tilted from the vertical to 7,8 thirty 114 18 thirty 7.7 116 17 7.8 31 120 18 one tilting the furnace for first 9-29% of the time purge 20 min of the second half of the purge time tilting the furnace for ) Here and further according to the table, the inclination of the furnace is carried out at 13. Initial purge rate Table continuation and metal oxygen 1800.