A Study on the Reaction between Chromium Ore and Alkali during Roasting in Rotary Kiln
Toyoshi ASANO
pp. 1157-1164
抄録
The reactions between Cr are and Na2CO3 during roasting were studied using a rotary kiln (10000mm in length and 700mm in diameter). The followings are results obtained.
Both of the optimum roasting temperature and the optimum basicity of the raw material were quitesimilar to those of the laboratory experiments. The conversion rate of Cr (III) to Cr (VI) was raisedby increasing revolving speed of the kiln. The best conversion of Cr (III) to Cr (VI) was obtained whenthe weight ratio of filler to Cr are being 4 to 1. Considerations on heat balance was made for producingone ton of Na2Cr2O7·2H20 by the rotary kiln.
Among the many items of heat output, it was recognized obviously that the loss of heat by radiationand convection from the surface of kiln depended largely upon the capacity.
The following equation represents the relation between the loss of heat per ton of Na2Cr2O7·2H20 by radiation or convention and dimensions of kiln.
where E: Loss of heat per ton of Na2Cr2O7·2H20 by radiation and convection from the surfaceof a kiln with inner diameter c2, and outer diameter d2.
E= {(c1/ d1)/(c2/ d2)} E0
E0: Loss of heat per ton of Na2Cr2O7·2H20 by radiation and convection from the surfaceof a kiln with inner diameter c1, and outer diameter d1.