M. Ya. Medzhibozhskii

Separation of the refractory powder in the flame-guniting of converters

ConclusionsAn analysis of the deposition of the refractory particles on the converter lining in cyclonic-flame guniting revealed the presence of a conspicuous maximum deposition which coincided with the site of the peak depositions in a “hot” converter model and in a real 130-ton converter.Erosion of the converter lining is uneven and the local burns can be effectively repaired by depositing a maximum of gunite in the zone where the residual thickness of the lining is at minimum.

Sintering of periclase during flame guncreting

ConclusionsThe flame guncreting of basic refractories was studied on a rig, the base part of which was a model of a standard 130 ton oxygen converter. The highly refractory constituent of the guncrete body consisted of industrial magnesite powder obtained by fine grinding. The fuel was natural gas. A guncrete coating up to 100 mm thick was applied to the lining of the model.Specimens of guncrete coating consist of dense material having a finely crystalline structure (porosity up to 3%). The density of the guncrete coating depends mainly on the guncreting temperature.The existence of direct bonds between the grains of periclase is typical for the structure of guncrete coatings. Additions of iron oxides increase the number of grains coming into contact by means of a direct bond, while additions of calcium and silicon oxides reduce it.

Life of refractory structures during intensive oxygen blow of the open hearth bath

ConclusionsWhen the oxygen blow intensity in a bath of a 250-ton open-hearth furnace was increased (13–15 m3/h·ton) the rate of wear of the roof brick and the irregularity of the erosion of the main roof were greater, the resistance of the roof lower, and the specific consumption of brick for building it greater, than when the oxygen was fed to the flame.The resistance of the remaining elements of the structure does not limit the duration of the campaign with increased oxygen blow intensity in the bath, and the specific consumption of refractories on building it is lower than when the oxygen is fed to the flame.The total specific consumption of refractories is reduced during the conversion from feeding oxygen to the flame to moderate blowing the bath with oxygen (7 m3/h·ton), and with an increase in it to 15 m3/h ·ton.Ageing of the furnace during intense oxygen blow in the bath is no faster than when the oxygen is fed to the flame.The specific consumption of refractories with increased oxygen blow intensity in the bath may be cut still further by improving the quality of the refractories, the design of various elements, and boosting the draft in the furnace.

Ways to effect a steep rise in open hearth production

Conclusions1.A drastic increase in furnace throughput and an improvement in the production costs picture in the performance of open hearth furnaces can be achieved most effectively by using oxygen predominantly in a stream blown directly into the bath at high intensity, combined with a high rate of charge for the entire furnace burden.2.As a result of instituting a high rate of charge of the entire furnace burden (250 to 300 tons/h) and high blowing intensity in the oxygen blow of the bath (15 to 17 m3/h ton) at the 250-ton open hearth furnace No. 1 of the Makeev metallurgical plant in 1966, furnace productivity increased 2.5 times in 1966 over the level achieved when oxygen is supplied to the process only through roof lancing, the fuel rate was cut to one-third, the total refractories required was cut 1.5 times, the net costs of the steel made was dropped 0.88 ruble/ton, and annual savings from the introduction of this high-productivity technology were 453,000 rubles.3.Widespread use of this method for intensifying the open hearth production process will require improving the preparation of iron scrap feed, bringing the bulk density of the scrap up to the 2.5 to 3.0 ton/m3 range, as well as increasing the output of tonnage oxygen plants at metallurgical plants, equipping the furnaces with flue scrubbers, expanding auxiliary sections of the shops, and solving the problem of how to optimize the number of furnaces operating at higher productivity levels in a given shop.