The relation between the quality of product and the time-temperature characteristics of the material heated when limestones are calcined in shaft kilns is a subject of great importance, because of obtaining the proper conditions of kiln operation, and especially because of a first step to decide the reasonable design of lime shaft kiln.
In this paper were reported the effect of rate of heating upon the temperature distribution in and upon chemical and physical behaviors of the material being heated during the firing process, and especially the effect of heating-schedule upon the thermal expansion including thermal contraction near calcining temperature, when medium sized test pieces of rectangular form in 8×5×3.5 (cm) were fired in a furnace electrically heated.
The results obtained may be summerized as follows : (1) from the temperature distribution in the test pieces were demonstrated the effect of heating rate upon the temperature differences existing between the surface and core, (2) at higher rates of heating the core temperature remained constant within a definite period of time when the decomposition of limestone was in progress, on the other hand at lower rates of heating such a phenomenon did not presented it-self but the core rose at a certain rate in temperature, (3) temperature range in which the decomposition of limestone took place was observed between 880 and 930 (°C), and the higher decomposition temperatures were obtained at higher rates of firing within the range above mentioned, and (4) the relation between the thermal expansion and the heating rate was demonstrated by comparing the mean expansion between the room temperature and 1200 (°C) with the one suddenly raised up to the decomposition temperature.

抄録全体を表示

If a small amount of CaSO₄·1/2H₂O is added to a water, the latter become turbid, and will become clear owing to supersatulation, and agin the will gradualy become turbid owing to formation of CaSO₄·2H₂O. The concentration of a suspension can be measure in a way, -by measuring the amount of light transmitted, which can be done in a turbidimeter. In this way the diffuse density of CaSO₄ in determined, but we can only measured the condition of CaSO₄/H₂O <0.007 on that experiment.
At the conditions, which are moulded with water, we mesured the opposite phenomena concerned abve mentioned sentence;-at the intial set the Sample is not more passed by the light, but most passed at the final set, and then become to turbid with harding. The dried mold is not most passed by the light.

抄録全体を表示