The electro-static electrification and flowing characteristics of metal powder particles which had fallen through inclined friction pipes made of various materials were studied by the use of a Faraday's cage.
Using pipes having a constant inside diameters under different inclined angles of friction, 100g of 8 kinds of metal powders were examined and converted to values per unit Kg of weight.
The results obtained in this research are summarized as follows:
1) Measuring the time required for those metal powders to flow-out through the pipes, tin powder was found to be shorter than that of any other powder. Depending on the sort of metal powders, the selection of materials of friction pipes has a considerable effect on the flow-out time of powder particles.
2) When friction pipes were inclined at large angles, the lowest values of flow-out time and the highest ones of electrification were obtained under the condition of sliding and rolling motion of metal powder particles.
3) Electro-static electrification values of metal powder particles depend on the electrical characteristics of the materials used as friction pipes. The values obtained between non-metallic pipes and metal powder particles were larger than those obtained between metallic pipes and metal powder particles. It was impossible to measure those values between Al powder particles and non-metallic pipes because of excess electrification.
4) Polarities of metal powder particles electrified under frictional conditions did not have any constant tendencies.

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The fuel change from oil to coal in industry has made coal combustion fly ash pollution and handling one of the most urgent problems requiring solution. In this paper which concerns coal combustion fly ash pollution, the problem of the design of electrostatic precipitators and bag filters is fundamentally and systematically discussed. Wherein, in order to fill the gap between powder properties under consideration and the design of electrostatic precipitators and bag filters, a new concept of the compression operating line is introduced and applied in combination with the statistical powder yield model presented by the authors, which has been experimentally checked using about 30 kinds of industrial powders.
The new estimation method for the powder yield locus of the deposited dust layer in electrostatic precipitators and bag filters is illustrated by example to the design of these units. The features of this design problem are considered to be similar to that of other chemical engineering plants such as distillation and absorption towers.

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The pore structure of silica gels surface-treated with phenyl trichlorosilane, pheneylmethyldichlorosilane, diphenylmethylchlorosilane and trimethylchlorosilane, was investigated through 77°K Ar adsorption isotherms over these silica gels treated thermally at 130°, 250°, 350° and 450°C, respectively. The relationship of the apparent surface area B′σ to the micropore volume N₀ and the surface area Bσ of the plane surface in macropores and the relationship of the apparent BET constant C′ against the micropore volume N₀, were determined through the use of the B′ and C′-value obtained by applying the composite adsorption isotherm composed of the isotherm for the micropore, and that for the macropore, to the BET equation. The values of B and N₀ obtained by applying the BET apparent surface area B′σ and apparent BET constant C′ for Ar adsorption isotherms over surface-treated silica gels to these relationships agreed with those obtained by the α_s-plot for the respective isotherms. Accordingly, these Ar adsorption isotherms were ascertained to be composite isotherms. It is possible to detect these Ar isotherms by the α_s-plot method. Although the numbers of surface groups were unchanged by heating these surface-treated silica gels at 130°, 250°, 350° and 450°C, the adsorbed amount on each sample increaed throughont the whole pressure range, increasing the temperaure of thermal treatment. The surface area of the plane surface for the macropore was unchanged, while the micropore volume increased. The volume of the micropore increased in proportion to the amount of dehydration due to thermal treatment.

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