G. E. Karas

Silicon-carbide refractories for firing porcelain

ConclusionsWe have improved the technology for SiC refractories with a siliceous bond by altering the phase composition of the bond. By using reaction-sintering, as a result of including elemental silicon in the batch or a mixture of it with silica, we obtained a combined bond containing silicon nitride and oxynitride besides the silica.The articles obtained have an improved strength and thermal-shock resistance, corresponding to the properties of foreign specimens of the same type.

Effect of aegirite concentrate on the properties of firebrick

ConclusionsWe examined the possibility of obtaining a new refractory material based on chamotte containing additions of aegirite concentrate — a waste product from the processing of apatite-nepheline ores at the Apatit Production Association.Some physicochemical and strength properties of the new chamotte-aegirite refractories were investigated.The benefits and range of uses of these refractories can be finally determined after completion of large-scale industrial trials in various furnaces in the refractories industry.

Improving the firing of plates for steel-teeming ladle slide gates

The mathematical simulation of heat exchange during firing of refractories in tunnel kilns made it possible to develop technical measures to increase the productivity of the two-tunnel kilns by 33% and the annual production of the MKTsP-82 plates was 1500 tons. The improved firing conditions for plates in the tunnel kilns are characterized by an average rate of movement of the charge of 0.30 m/h and an interval between pushes of the cars of 20 min. During use of the improved firing method the operation of the basic production zones of the kiln was corrected. The increase obtained in tunnel kiln productivity and the reduction in specific fuel consumption was the result of this study of acceleration of the firing operation and economy in energy resources.

Refractory tubes for protection of metal jets issuing from a steel-pouring ladle during continuous casting

ConclusionsAt the continuous-casting line at NLMW we have tested pouring with a protected stream of metal from the steel-pouring ladle with the aid of quartz and graphite-chamotte tubes. It was established that the optimum design of the protective device consists of a refractory tube 750 mm long in conjunction with a stationary tube fixed on the lid of the intermediate ladle. At the point of junction between the two tubes, inert gas is injected to give additional protection. The structure of the device for bringing the tube up to the ladle should ensure tight joining of the tube with the collector nozzle and mobility of the tube during pouring.

Service of corundum plates in sliding gates during teeming of steel into ingot molds from 140-ton ladles

ConclusionsSpecial tests have been made on magnesia biceramic and corundum plates in sliding gates of steel teeming ladles. It is found that better teeming of steel from 140-ton ladles into ingot molds is obtained with corundum plates.There is hope of increasing the number of times which the corundum plates can be used.

The durability of acoustically tested SP-11-type mullite-corundum stoppers

ConclusionsAn investigation carried out at the Novolipetsk Metallurgical Plant of the performance of the SP-11-type mullite-corundum stoppers produced by the Semiluk Refractories Plant showed that the durability was highest in the case of stoppers with a resonance frequency of 10,000–12,000 Hz. The stoppers falling into that frequency range account for about 70% of the total output.Culling out the stoppers with resonance frequencies below 10,000 and above 12,000 Hz and the “deaf” stoppers by acoustic testing increases the performance reliability of the stoppers of pony ladles and lengthens their useful life by 0.25 melt.

Quartz-clay ramming compounds from the raw material of the Latnen deposits

ConclusionsIt was established that the materials from the Latnen deposits are suitable for the production of quartz—clay ramming compounds, which in the lining of steelcasting ladles are more durable than compounds prepared from loamy Chasov-Yar sand.A technology was developed for the production of quartz-clay compounds from the loamy sands of a subjacent layer (underlying the clay), and for the production of quartz-clay ramming compounds from overburden sand and the semiacid clay grades LT1PK, LT2PK, and LT3PK.The quality indices are optimal for compounds produced from sands with a low content of Al2O3 (0.7% or less), alkali (0.5% or less), and Fe2O3 (0.5% or less), and a semiacid clay in proportions which will give a total of 10–12% argillaceous component in the compound.

Rammed linings for 160-ton steelcasting ladles

ConclusionsThe production technology was developed for a silica ramming compound from fine-grained semialiphatic Chasov-Yar quartz sand. The production technology was adopted by the Semiluk Refractories Plant.A machine, viz. the Orbita-1, for ram-lining steelcasting ladles, was designed, constructed, and brought into service.A flow sheet was developed for the production and drying of rammed linings for steelcasting ladles. The rammed lining is as durable as a brick lining. The machine time for ramming the lining has now been reduced to 18–25 min.The cost of the materials is lower and labor productivity in the lining process higher when using ramming compounds for the lining of steelcasting ladles.

Vibration equipment for making refractories

ConclusionsA design was developed for an industrial vibroimpact installation for making refractories. The equipment has been introduced into production. A series of measures were studied and introduced, leading to increases in the working reliability of the vibration equipment, sharply reducing the noise level, increasing the effectiveness of densification, and reducing the transmission of oscillations from the foundation of the vibration equipment to the surrounding elements of the building.The production of various shapes and large silicon carbide products weighing up to 40 kg was developed in production conditions.

Industrial development of vibroimpact molding of silicon carbide refractories

ConclusionsA technology was developed for the vibrocompaction of silicon carbide refractories. The efficiency of the process was confirmed in industrial conditions.The properties achieved by vibrocompaction in silicon carbide refractories and their uniformity of distribution appreciably exceeds similar characteristics for tamped, and to some extent pressed, refractories.Vibromolding equipment is very simple in design, of low metal content, low power rating and cost, and can be used to obtain product qualities at pressures of 1–2 kg/cm2 that are achieved in pressing only by pressures of about 1500 kg/cm2.The use of vibrocompacted silicon carbide slabs in the porcelain industry as kiln furniture increased the inter-repair periods for shelf cars for firing pottery.