Use of magnesite concrete in open-hearth furnaces

Conclusions Many years practical experience with the use of refractory magnesite concretes in open-hearth furnaces at the KMZ confirmed that it is rational to use them even for preparing concretes and blocks on the working sites of open-hearth shops, and it also confirmed the unacceptability of open-hearth furnace structures for placing the concretes.A project for a furnace framework should be developed bearing in mind the use of blocks of maximum sizes which will accelerate repairs.Simultaneously with the increase in the output of chrome-magnesite mixture for the production of concrete it is necessary to produce this mixture with greater fineness for the wash materials.Translated from Ogneupory, No. 6, pp.31–35, June, 1972.     

Carborundum refractories for iron scale reducing furnaces and natural gas converting furnaces

Conclusions The results of the laboratory tests have been confirmed by industrial conditions (2) and it has been found that the addition of clay to coarse grained mixtures reduces the oxidibility of carborundum parts during service at comparatively low temperatures, when the furnaces are fired with natural gas.The development and introduction of rational technology has sharply increased the resistance of carborundum refractories in furnaces used for the reduction of scale and the conversion of gas, when they are fired with natural gas.     

Determination of laminar burning velocities for natural gas

Spherically expanding flames of natural gas-air mixtures have been employed to measure the laminar flame speeds, at the equivalence ratios from 0.6 to 1.4, initial pressures of 0.05, 0.1 and 0.15 MPa, and preheat temperatures from 300 to 400 K. Following Markstein theory, one then obtains the corresponding unstretched laminar burning velocity after omitting the effect of stretch imposed at the flame front. Over the ranges studied, the burning velocities are fit by a functional form u_l=u_l0(T_u/T_u0)^α_T(P_u/P_u0)^β_P, and the dependencies of α_T and β_P upon the equivalence ratio of mixture are also given. The effects of dilute gas on burning velocities have been studied at the equivalence ratios from 0.7 to 1.2, and the explicit formula of laminar burning velocities for dilute mixtures is achieved.     

Spinel-bonded magnesite brick for high-tonnage electric arc furnaces

Conclusions The manufacture of an experimental batch of spalling resistant magnesite-chrome brick with a spinel binder has made it possible to improve the technological norms for the production of these parts and has shown the possibility of making them at the new shop at the Magnezit Plant.The parts produced show good characteristics: refractoriness-under-load of 2 kg/cm² — 1650–1720°; additional shrinkage during heating to 1650° with subsequent holding for three hours –0.1%; spalling resistance 7–13 water-heating-cooling cycles (heating to 1300°); apparent porosity 15–17%; compressive strength 620 kg/cm².To obtain parts with good physical-chemical properties it is essential to use MK magnesite powder; to add at least 6–8% industrial alumina to the charge (in terms of Al₂O₃); to make certain the magnesite-alumina mixture is highly dispersed so that it helps to complete the spinel formation reaction during the firing; to use a mixture of the following grain composition: not less than 20% fraction 3–1 mm; 55–60% finer than 0.5 mm, including 30–35% finer than 0.06 mm; to press the parts at 1200–1500 kg/cm²; to fire the parts at a temperature not less than 1600°, batching them far apart so as to avoid the formation of an uneven structure.The use of magnesite brick with a spinel binder for the walls of high-tonnage electric arc furnaces used to melt transformer steel ensures satisfactory strength of the walls in the slag belt and prevents the steel becoming contaminated with chromium.     

Operation of high-temperature shaft furnaces with layerwise firing

The thermal operation of high-temperature shaft furnaces with layerwise firing has been investigated. Fundamental drawbacks of this firing method are described, which prevent it from being recommended for industrial use, since it does not meet modern ecological and power-saving requirements. Translated from Ogneupory, No. 7, pp. 28–30, May, 1994.