Torajiro Honma

Grinding of mixtures of coal and iron ore in order to prepare material for coal liquefaction

Abstract Ball mill tests on the laboratory scale were carried out in order to prepare materials for coal liquefaction. The samples used were coal, iron ore and mixtures of these materials. The reason why an iron ore was selected as a component of the binary mixture is that, sometimes, some kinds of iron ore have been used as a disposable catalyst in a reaction of coal liquefaction and its mechanical properties and grindability are not similar to those of coal. In a simultaneous grinding of a mixture of these materials, iron ore had the effect of fine grinding of the coal. It was found that simultaneous grinding was a feasible method of preparation of feed material for coal liquefaction.

Effect of mill diameter on the rate of initial grinding in vibration ball mills

Abstract Vibration ball milling was carried out using three kinds of mills with the same internal volume but different diameters. The variations of specific surface area produced with time were investigated at a constant vibration intensity using feldspar with an initial size range of 74 – 149 μm. As a result, it was found that the specific surface area of product was markedly influenced by the difference in mill diameter even at the same vibrating conditions. According to an empirical equation proposed in a previous paper, the rate of initial grinding was also found to vary by a factor of 1.4 to 2.0, depending upon the mill used. The dependence of the rate of grinding on mill diameter can be explained by considering an effective area of mill shell capable of colliding with balls and a motion of balls in each mill. An available suggestion for designing a mill pot was obtained from this work.

Trial production and ability of a single rod mill.

For economizing in grinding process, a new type mill, a single rod mill, developed from a roller mill and rod mill was produced as an experiment. The ability of the single rod mill was investigated by various grinding experiments. Samples used were quartz with five kinds of size ranges. As a result, it was found that feed size for this mill was far larger than that for conventional ball mills, and that product with uniform particle size was obtained relatively. The grinding mechanism in this mill was found to be compressive grinding by the load of a rod.The mill with construction such as a single rod mill in this work is usefull enough as a fine grinding machine.

Vibration milling using rod media.

粉砕媒体として, 種々の長さのロッド (棒鋼) を用いて振動粉砕を行い, 粉砕速度および砕製物の粒度分布を検討した.また, ボール媒体に関してすでに得られている粉砕速度式を適用して, それぞれのロッドにおける最適充填率を求めた.その結果, 各ロッドの最適充填率の条件下では, 径と同程度の長さを有する形状のロッドを用いた場合が, 最も粉砕性が良好であり, しかもこのロッドと同質量のボール媒体を用いた場合よりも効果的であることがわかった.ボールとロッドの粉砕性の相違は, 媒体形状に起因するものと考えられる.本研究により, 試料の粉砕能を考慮した適当な媒体形状の選択によって, 粉砕性はさらに改善されることが示唆された.