Agitation - Agitation

Japanese: 攪拌 - かくはん（英語表記）agitation

Stirring. A simple task that has long been used in cooking, but with the advancement of chemical engineering, it has recently become important as a unit operation. The purposes are very diverse, such as promoting dissolution, leaching, and chemical reactions, making temperature and concentration uniform, emulsifying insoluble materials, preventing sediment from solidifying, and aeration. There are many types of agitators and sizes of equipment, and they are selected according to the material to be treated. Small agitators often use a rotating propeller or blades, but large ones such as those used in mining, smelting, and sewage treatment are often equipped with long stirring arms and blade-shaped rakers. In addition to mechanical stirring, compressed air or high-pressure steam may be blown in, or mechanical stirring and air stirring may be used together. In sewage treatment, this is used to achieve the purpose of purification using aerobic bacteria. When stirring powdered solids, the purpose is often to pulverize them at the same time, and large agitators such as raikaiki are often used.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

かきまぜること。昔から料理などでよく行なった簡単な作業であるが，最近は化学工学の進歩とともに，単位操作として重要な意味をもってきた。目的は，溶解・浸出・化学反応の促進，温度・濃度の均一化，互いに不溶のものの混合乳化 (エマルジョン化) ，沈殿物の凝固防止，あるいは曝気 (ばっき) など，非常に多様で，攪拌機 agitatorの型式や装置の大小も種類が多く，処理材料によって選択する。小型ではプロペラや羽根の回転によるものが多いが，鉱業・製錬・下水処理などの大型では，長い攪拌腕に羽根型のかき歯をつけたものが多い。また機械的攪拌だけでなく，圧縮空気や高圧水蒸気を吹込む場合や，機械攪拌と空気攪拌を併用することもある。下水処理ではこれにより好気性菌による浄化の目的を達する。粉状固形物の攪拌では，同時に微粉化を目的とすることが多く，擂潰機 (らいかいき) のような形式の大型のものがよく使われる。

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