Questions of the rational method of coversion of magnesite caustic dust and subsequent use of the fired product have been repeatedly considered in print [1][2][3][4][5][6][7]. One of the means of utilization of the dust is considered in the article of K. V. Simonov and K. K. Strelov
[8].Caustic magnesite dust is a dispersed product obtained in low-temperature (900-I000~ firing of natural magnestie or in recovery of the dust particles carried out from rotating kilns in high-temperature firing of magnesite.Caustic dust subjected to a second high-temperature firing in rotating kilns is covered to granular periclase powder:with a quite wide range of particle sizes (from 30-40 to less than 1 mm.)The fired product may be used for the production of magnesia parts, since it is characterized by a quite high magnesium oxide content 92-94% and sometimes more) and a comparatively low content of oxides of calcium, iron, and aluminum and of silicon dioxide.In addition, fired caustic magnesite has increased porosity.In high-temperature firing of caustic magnesite, significant differentiation of the chemical composition in relation to particle size, which occurs in firing natural magnesite, is not observed.This makes it possible to use any fraction of caustic magnesite for the production of parts.In connection with this, it is more desirable to not use high-temperature dust together with lump natural magnesite, but separately.Taking into consideration the high purity of fired caustic dust, it would be more desirable to use it primarily for the production of critical parts, using for this preferably dust from those kilns in which the purest varieties of magnesite are fired.A known obstacle in attaining this goal is the increased porosity of the fired powder obtained in firing, in rotary kilns, of caustic dust previously prepared using the dry method.The open porosity of the product of firing containing 91-94% MgO, 2-3% Si02, and up to 3% CaO varies primarily within limits of 25-35% and sometimes up to 40%, and only in the finest fractions, such as 3-1 mm, may it drop to 18-25%.In [6,7] it wash shown that the density of powder may be increased significantly by the addition of additions such as titanomagnetite concentrate, titanoalumina slag, etc., by additional pulverizing of the orignal caustic dust, or by thermal activiation of it.The most rational means of increasing the density of fired powder from caustic dust is briquetting of it before firing.Earlier [9], the technological parameters of briquetting were determined and attention was devoted to the effectiveness of additional pulverizing (dispersion) of the dust before briquetting.At present it appears most desirable to use caustic dust by briquetting it together with beneficiated low-silica concentrate of Don Beneficiating Plant, supplied to Magnesite Combine to Technical Specification 14-9-202--80.The concentrate contains not less than 57% Cr2Os and more more than 3% Si02, and consists primarily (85-90%) of particles of less than 0.5 mm. Such an unfavorable particle-size co...
