Sintering powdered beneficiated magnesite

Conclusions

A study was made of the sintering of beneficiated Satkinsk magnesite using three production schemes, specifying in the first case fine grinding of the raw materials, in the second thermal activation of the material, and in the third additive incorporation. These production methods yield magnesia powders of varying density owing to the different nature of the periclase crystallization.

From the finely milled beneficiated concentrate at comparatively low firing temperatures for the pellets (1550°C) it is possible to make magnesite powders with an apparent porosity of 2–12%, with average periclase crystal sizes of 5–10μ. With additions to the finely milled or thermoactivated concentrate of small quantities of beneficiated chromite or zirconia, the crystallization of the periclase is sharply activated, especially at pellet-firing temperatures of 1650 and 1750°C. In this case we obtain powders with an apparent porosity of 0.2–3.0%, the average crystal sizes of the periclase being 30–40μ.

The technology specifying fine grinding of the raw materials, pelletizing, and burning the pellets at 1550–1600°C is the most economical of all the technological methods investigated. The use of the thermalactivation technique for the beneficiated magnesite and incorporating additives may be effective only for producing high-density magnesite powders designed for special types of refractory products.