Coke fired lime shaft kiln has been so far studied with little consideration of the flow of gases in the kiln. On the other hand it is strongly in evidence that the flow patterns of the gases have an intimate relation with the performance of this kiln. In this paper, how the streams of hot combustion gases in preheating and calcining zones, and of air for combustion in cooling zone were subdivided was treated, from a point of view regarding the mechanism of the flow of gases through the kiln stack.
The profiles obtained in temperature and in concentration of gases (the curves of temperature and concentration of gases at different levels in the kiln), being taken those after the test kiln was in steady state, indicated that a very large stagnant space for the flow of kiln gases which was beyond authors' expectations was formed in parallel to the kiln axis, and that this phenomenon was the very thing for lowering the kiln efficiencies.
Further, authors should like to add that “the combustion calculation” is one of the indispensale means for studying the mechanism in operation of the kiln.

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It is well known that on the hydration of anhydrite it has next two processes, i, e., the first process is solution through the boundary layer around the particles of anhydrite, the second is crystallization of dihydrate from bulk solution, and it's rate controlling step is solution process.
The reaction rate, hence, concerns with it's effective surface, solubility or origin.
In this paper, we conducted to study on some factors for the hydrating operation of natural anhydrite.

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It was reported that quick lime powder containing gypsumh ad a hardening property in mixing with water. Concerning to the hydrothermal reaction of lime and siliceous material, the study was carried that quick lime powder containg gypsum was used insted of ca (OH) ².
Mixtures in various proportions of quick lime powder, siliceous sand powder and gypsum powder were prepared by a V-type mixer. Pastes were made by mixing the mixtures with water (water/mixture=0.20-0.45). From the pastes following two sorts of test specimens were formed : Cylindrical specimens (∅ 30×30 mm) which were made by pressing at 13-100 kg/cm₂, specimens (20× 20×80 mm) which were made by molding. The specimens were cured in an autoclave in 181°C for 4 hours in order to being hardened and then dimensions and strengths of the resulting hardened bodies were measured.
Results are summerized as follows :
(1) Cylindrical specimens formed by pressing pastes without gypsum crumbled in 20 mintues to 3 hours after pressing because of expansion.
(2) Cylindrical specimens containing gypsum were stable without expansion in air and water, and had 40-50 kg/cm² compressive strengths without autoclave treatment.
(3) When cylindrical specimens containing gypsum were cured in an autoclave after being cured in air for a day, they expanded very much and rusulting hardened bodies had not so high strengths.
(4) When cylindrical specimens containing gypsum were cured in water before autoclave treatment, they became to very strong bodies (above 500 kg/cm² compressive strength) without expansion by autoclave treatment.
(5) The results obtained with molded specimens of 20×20×80 mm were very close to ones obtained with cylindrical specimens.

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