Applying the method of process dynamics, we proposed here a new method of analysis on open circuit ball milling.
We measured the delta responses of mixing of powders, using a pilot plant scale ball and a laboratory scale ball mill, changing factors of which were screen plate, ball size, ball fillingness, rate of feed and mill speed as shown in Table 1.
While grinding limestone, a small quantity of tracer (copper sulfate powder) was thrown instantaneously from the mill inlet and the tracer concentration in the product discharged from the mill outlet was measured.
The change of tracer concentration (delta response) was found to be represented well by logarithmic -normal distribution as follows:
And also, using a diffusion-type model, the following theoretical formula was derived.
By means of standard deviation δ and mixing coefficient E in the above formulas, the degree of mixing in mill is evaluated quantitatively, as shown in Tables 2, 3, 4 and 5.

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Experiments on sublimation of camphor packings into an air stream were carried out in four packed columns, 5, 7, 10 and 12.7cm in diameter.
Packings used were 15-mm spheres, 15-mm cylinders and 15-mm and 25-mm Raschig rings.
In order to represent the data for all packings by a single equation, various methods of correlation were examined and a plot of atHG/Sc²/³ vs. d_pG/μ(1-e) was found to correlate the data best. It was also found that the same data could be considerably well correlated by two types of correlation, atHG/eSc^2/3 vs. dp'G/μ(1-e) and atH_G/eSc^2/3 vs. d_pG/μe.

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Crystal integration rates on the face of a seed crystal placed parallel and rectangular to the direction of flow were studied and the rate of crystal growth in the stationary solution was also discussed.
Experiment was performed with the apparatus shown in Fig.(1). The rate of growth was measured by identifying the difference in color in the integrated part from the original seed crystal which had been previously colored with lactose.
The result and conclusion may be summarised below:
(1) For the saturated aqueous solution of ammonium chloride added with urea and/or lactose, its solubility, viscosity and density were measured and their graphical representation is shown in Figs.(2), (3) and (4). These are equivalent to Eqs.(1), (2) and (3).
(2) The rate of growth of ammonium chloride was confirmed to be diffusion-controlled for the Reynolds number of 70 to 500, at 30°C.
The rate of crystal growth on every face is formulated in terms of local mass transfer coefficient from a single sphere to multi-current liquid, and is expressed in Eqs.(5), (6) and (7) respectively. Concentration of urea in solutions used in these experiments were 0.153 and 0.312 [CO (NH₂) ₂/NH₄Cl].
(3) For the mass transfer to a crystal placed in the stationary solution, the effect of natural convection was found to be significant. Composition of additive substances in these stations were as below:
run 1 2 3 4
x [CO (NH₂) ₂/NH₄Cl] 0.153 0.312 0.331 0.328
C₁ [kg·Emol (lactose)/m³ (H₂O)] 0 0 0.24 0.48

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Mass transfer was investigated in bubble bed of 150mmφ, 280mmφ and 475mmφ in diameter under atmospheric pressure. Fixed sample of benzoic-acid-spherical, cylindrical and disk type (20-75mm in size)-was dissolved into distilled water which was agitated by air bubbles formed from perforated-plate gas-distributors. The bed temperatures, TL, were 12-40°, and the initial heights of liquid, H₀, were 100-500mm. Concentration of benzoic-acid solution was continuously measured by the electric-conductivity method.
The coefficient of mass transfer, k_L, of benzoic-acid into water is found to be almost constant at any point in the bed. It depends very much upon the flow rate of air, u_T, and the kind of perforated-plate gas-distributors. When the flow rate of air is small, the value of k_L increases approximately with 1/3-1/2 power of uT in any perforated-plate gas-distributors, and it becomes larger when perforated plate has smaller ratio of hole-area, R_A. When the flow rate of air increases extremely, k_L is independent of u_T and depends only upon R_A.

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Automatic control technique does not seem to be applied very much to the field of solid particle handlings, because no adequate device is available to measure and to manipulate the flow rate of solid particles.
According to previous report, the solid-gas mixture ratio can be calculated using the two pressure differences of a two phase flowmeter. In this paper, therefore, a specific servo-computer is employed “on line” for this purpose.
The mixture ratio is continuously measured within the accuracy of ±5% and successfully contr olled using an electromagnetic vibrating feeder as the manipulating device. In the mixture ratio control, an upside weir should be attached to the feeder trough to get wider manipulating range. The inverse response appears in the mixture ratio by the difference of dynamic characteristics between high and low pressure side s of a transmitter. Therefore, particular attention should be paid to select a transmitter in order t o get a quick and stable response.

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Further considerations upon “Adiabatic Characteristics of Reaction Operation Field” are presented here in this report. Firstly, characteristic critical temperature T_c generally exists when reaction operation field is a like that shown in Fig. 1. Secondly, P type area expands towards less conversion side according to movement of operation starting line towards higher conversion direction. Thirdly, adiabatic characteristics have close relation with optimization concerning space time yield.
In this paper, Denbigh, K. G.'s derivations concerning ideal reaction operation are discussed in some detail.

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