Ribbon-type mixers, one of the fixed-type mixers, havc been employed in various industrial processes, but few experimental studies are reported on them.
We studied the performances and the operational conditions of this type of a mixer, and, using the coefficient of mixing velocity φ, analyzed the results obtained.
The powders used were of two-component system, Na
2CO
3-sand, of four different particle sizes.
The degree of mixing was defined by means of the standard deviation σ.
The results obtained were summarized as follows.
(1) The mixing curvebtained of the ribbon-type mixer were similar to those of the rotational-type mixer, i.e.a twin-, a double-cone and a cubic-mixer, as shown in Fig. 3. Therefore, we might consider that the mixing processes were fundamentally similar with both the types of mixers, though in the case of the ribbon-type mixer, the first stage of mixing curves were different from that in the case of the rotational-type mixer, as shown in Fig. 3.
(2) In the ribbon-type mixer the influence of the rotational speed on the number of revolution required was smaller than in the case the rotational-type mixer.
(3) The optimum volme ratio of charged powder to inner volume of mixing vessel (
F/V)
op. was about 17.3%, as shown in Fig. 5 (a), (b) and (c), corresponding to about 40% of appearent volume ratio of the powder.
(4) As particle size increased, the velocity of mixing increased, with the degree of mixing, σ, becoming larger, as shown in Fig. 6 (a), (b) and (c).
(5) The influences of the rotational speed, charged volume ratio of powder and particle size on the coefficient of the mixing velocity might be expressed by an empirical equation (4).
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