A DSP-IO0 electric arc furnace was placed in service in Orsk-Khalilova Metallurgical Combine in 1981. In accordance with the design the arched roof of the furnace is laid dry with PKhSE-3 and PKhSE-5 refractories.In the first campaigns the life of the roof was low (43 heats), which was the reason for conducting investigations on improving the lining.The work was done in two directions, by selection of the composition of mortar for the lining and by changing the method of lining and design of the roof.Four variations of the mortar composition were tested.All of the mixtures of powders were mixed with an aqueous solution of magnesium sulfate with a density of 1.25 g/cm s ~Table i).The introduction of even the first three variations of the mortar (series of campaigns No. 2-4) made it possible to increase the average life of the roof by i0 heats.The mortar with a filler of a mixture of magnesite powder and SMZh provided a further increase in life to an average of 84 heats.An increase in the rise of the roof from 920 to 1020 mm and laying the lining by the ring method made it possible to not only significantly reduce the bricklaying labor but also to increase the life of the roof to 103 heats per campaign.Ring lining of the roof was done in the following manner.Fourteen rings or parts placed on edge were laid and then two rings laid flat, after which the templates were placed in the electrode holes and two rows of parts were laid on edge around them.The laying was done using amortar of a mixture of magnesite powder and SMZh and the thickness of the joints was 3-5 mm. Between the second and third and the third and fourth rings joints 1-2 mm thick of roofing felt were laid.In 7 out of 55 cases there were failure of the roof support rings and flooding of the roof lining with water and, as the result, early failure of the roof.Therefore at present work is being done on selection of the optimum number of expansion joints and the points of their location.It should be noted that the new roof design operates under more severe conditions in relation to the period compared in connection with the introduction of vacuum treatment of the metal and the 20-25~ increase in the temperature of the steel before tapping.The wall lining was laid in two layers.The reinforcing layer was laid with KhM-I (GOST 5381-72) parts and the working layer with PKhS-23 and PKhS-17 (GOST 10888-76) parts 460 and 380 n~ thick, respectively.The wall life in the initial period was an average of 56 heats.To increase the wall life PKhP-80 (fused periclase--chromite) and KhPT-23 (heat resistant chromite-periclase) parts were used in nine campaigns for lining the working layer, which made it possible to increase the service life of the walls to 65-73 heats (Table 2).Orsk-Khalilova Metallurgical Combine.

When steel casting by means of sliding gates in an open-hearth furnace was introduced at the OrskoZtmlilovsk Metallurgical Combine, the resistance of the chamotte lining of the 230-250-ton steel-casting buckets was reduced. The reasons for the reduction in the resistance of the lining are the increased time spent by the metal in the bucket and the shorter idling time of the bucket between successive fills; this causes increased wear of the lining under the mechanical and chemical action of the molten metal and slag [1, 2].On the basis of a simulation of the destruction of a refractory lining as a result of temperature and ferrodynamic effects when the liquid metal flows into the bucket, we have now determined the effect of the initial temperature of the lining on the destructive processes. The temperature of the lining was measured using Chromel-Alurnel therrnocouples. The thermocouple junction was embedded in the wall of the bucket to a depth of 35 mm from the internal surface. The thermocouple was mounted at a distance of 1300 mm above the :hearth corresponding to average working conditions of the lining.The temperature was measured during the first fill, the casting, and the cooling of the bucket in air over 2 h 45 rain at 1-5-min intervals. The next series of measurements were made during the third working cycle (filling-casting-cooling) over 3 h 15 min with similar measurement intervals.The temperature of the metalin the initial fill of the bucket was 1600-1615~The statistical data indicated that the average wear on the lining per cast was _< 10-12 ram; the test results showed that the deformation temperature of the brick under a load of 0.2 MPa was 1377~On the basis of the experimental data, we derived the empirical dependence for calculating the temperature of the surface layers of the lining during the heating and cooling process.The cooling of the surface layers of the lining of thickness 15-30 mm after the completion of the steel casting is described by the exponential dependencewhere t is the temperature of the body at the measurement point at a moment of time; to, initial temperaktre of the body; T, cooling time in air; and K, an empirical coefficient (K= 0.0052).However, heating of the lining is a transient process due to gradual damage of the surface layers at the contact with the metal and to the decrease in the liquid metal temperature; approximation of heating of the ladle lining by Eq. (1) therefore leads to high errors. Figure 1 shows graphs of the change in the lining temperature at the site of the thermocouple during the first and third cycles of the ladle operation, and their derivatives with respect to time. Inertia of the heating processes is noted, i.e., the increase in temperature at the measurement point is not observed immediately after the rise of the metal level to 1300 ram, but after a certain delay A~d, which is 5 rain for the first cycle and 3 min for the third, and (other conditions being equal) is determined by the distance from the measurement point to the inner surface of the ...

Monolithic lining of 250-ton steel-teeming ladles was introduced in Orsk-Khalilovka Metallurgical Combine in 1981. The share of steel-teeming ladles with a monolithic lining is 15-20% of the total number of ladles in service.The lining work is done with mechanized equipment by casting of a fluid self-hardening mixture. The composition of the mixture is 97.5-98.5 wt. % ground quartzite and 1.8-2.5 wt. % ferrochrome slag. The density of the waterglass is 1.08-1.15 g/cm 3. The outer dimensions and profile of the pattern provide a thickness of the cast layer in the lower portion of 190 and in the upper of 150 mm. The pouring time is 30-40 min and the length of hold with the pattern 2.5-3.0 h. The reinforcing lining and the working lining of the upper four rows are made of refractory brick [i].