E. P. Mezentsev

Drying magnesia refractories with the flue gas of the tunnel kiln

ConclusionsExperiments at the Magnezit Plant confirmed the feasibility of drying magnesia refractories with the flue gas in the first positions of a tunnel kiln. Drying the refractories in the section where the flue gas is tapped off does not result in more rejects or in degradation of the properties of the fired products.Compounding the processes of drying and firing magnesia refractories in a single unit, viz., the tunnel kiln, makes it possible to dispense with the driers the freed floorspace of which can be used for installing equipment for mechanizing the loading of the products on the kiln trucks.

Tests of refractories in argon-oxygen refining of metal

ConclusionsAs the result of comparative tests of refractories of different forms in the lining of the cylindrical portion of a 10-ton converter using argon-oxygen refining it was established that the most resistant of the tested materials is the periclase-spinellide refractory with the addition of chrome-alumina-spinellide. These parts may be recommended for lining the cylindrical portion of a pilot production argon-oxygen refining unit.

A modernized tunnel kiln for firing magnesia and magnesia-spinellide refractories at 1850°C

ConclusionsA low high-temperature tunnel kiln was rebuilt, including increasing the length of the firing zone, supplying hot air to the burners, supplying air to the cooling zone through the roof, and providing a system of aerodynamic sealing of the subhearth space of the kiln.Reconstruction of the kiln and the firing method developed made it possible to obtain a stable firing temperature of 1850°C and a hold of up to 6 h at a temperature above 1800°C, to decrease the temperature differential across the kiln channel cross section, to reduce scrap, to increase the quality of magnesia and magnesia-spinellide parts and the kiln productivity, and to improve the car serivce conditions and the working conditions of the operating personnel.

Operation of gas-burner devices with increased jet aperture angle for heating rotary furnaces

ConclusionsAn increase in the aperture angle of high-velocity gas jets intensifies the mixing of fuel with oxidizer in the accompanying flow as a result of the growth in the transverse pulsation constituent of the velocity and the surface of the flame front.Tests of the gas-burner device with an increase in the angle in a rotary kiln 50 m long firing raw magnesite showed that, as a result of the intensification of the fuel combustion using the new burner design, we can obtain an increase in the kiln output of 6.5%, with a simultaneous improvement in the quality of the powder being fired. To ensure the optimum working conditions in the kiln and get complete combustion of the natural gas, its pressure in front of the burner should be not less than 0.2 MPa.

Guniting of the monolithic lining of steel-teeming ladles

ConclusionsThe authors have developed the principles of guniting the monolithic lining of steel-teeming ladles with semidry masses. Determination of the wetting of a vitrified siliceous monolithic lining with aqueous solutions of additives and suspensions of these solutions, plasticizing additives, and refractory filler has shown that a coating can be deposited onto the surface of a monolithic lining. Formation of a ceramic bond between the coating and the vitrified surface of a monolithic lining takes place at high temperatures (900°C or above). Masses of siliceous, aluminosilicate, and periclase-chromite compositions have been developed for guniting the monolithic lining of steel-teeming ladles.A procedure for guniting the monolithic lining of 180- and 350-ton steel-teeming ladles has been developed and tested. The best results have been obtained with use of gunite masses of periclase-chromite composition.

Making and testing refractories from high-density, high-purity magnesite powder

ConclusionsTest results for the trial batch of refractories made of dense magnesite powder in the converter lining in the trunnion zone showed that they are promising for application compared with ordinary dolomite goods with a pitch bond. The average wear of the test refractory is not more than 1.0 mm/heat, while dolomite-pitch shows a wear of 1.5 mm/heat. The resistance of blocks of dense magnesite powder in the lining of steel discharge apertures of a converter also proved to be higher than periclase (83 heats against 69).

Change in the structure and properties of magnesia goods fired in industrial kilns

The p r o p e r t i e s of r e f r a c t o r i e s and the i r behavior in s e rv i ce a r e se r ious ly affected by the p r o c e s s e s that occur in f ir ing [1]. To d i scover means of improving the qual i t ies of magnes ia r e f r a c t o r i e s it i s impor tan t to know how the s t ruc tu re and p r o p e r t i e s a l t e r during heat t r ea tmen t in the va r ious zones of the industr ia l ki lns used to f i re them.

Tunnel kiln for firing refractories at 1850°c

ConclusionsThe refractories industry of the Soviet Union has designed and is now operating a tunnel kiln for firing refractories at 1850–1900°C. The kiln works with high cost-benefit indices and is used for firing high-grade magnesite-spinel goods on the basis of fused and sintered materials.

Pressing nozzles for high-speed steel teeming

ConclusionsThe Magnezit Combine has begun production of unfired pressed steel-teeming nozzles, with a channel diameter of 120 mm and height of 400 and 450 mm, made of magnesite paste.These nozzles have been put into service and adopted for high-speed top teeming of steel from a 330 ton ladle in the open-hearth shop of the KMW.

Furnace truck with channeled base

ConclusionsChanneled furnace truck linings have been devised and industrially tested; they greatly reduce the vertical temperature drop in the furnace channel and improve the annealing quality of the refractories.