Mitsuru Yamamoto

An analysis of disc vibration grinding.

The mill concerned consists of a shallow cylindrical container vibrating in a horizontal circular path and a disc-shaped grinding body whose thickness is slightly smaller than the depth of the container. In this mill the breakage of material is carried out mainly by compressive stresses caused through the friction between the grinding body and the wall of the container. In certain vibrating and frictional conditions the grinding body moves rotating along the wall of the container in the opposite to the driving direction. The product of the frictional force between the grinding body and the wall of the container and the relative displacement of the grinding body is considered to contribute to the grinding efficiency. That is, the work performed through the movement of the disc should be proportional to the product of the angular velocity of the disc and the third power of the disc radius. The authors introduced an expression to calculate the angular velocity of the disc as a function of vibrating and frictional conditions as well as the mill dimensions to be used. An optimum disc radius with regard to the best grinding efficiency has been also discussed but the slippage degree of the disc has been assumed to be independent on the disc radius.A series of grinding tests with reference to the performance of grinding body has been undertaken using four discs with different radii, the driving unit and the container of a laboratory type disc-ring-vibration mill.The results of the grinding tests on quartz as grinding material have verified essentially our view on the performance of grinding body, but some disagreement has been found at the largest size of the grinding body. And the cause of this disagreement has been also discussed.

Agglomeration of Solid Waste with the Use of Thermoplastic Binder

各種 のスラッジ,ダ ス ト,ガ ラス屑等の産業廃棄物の 処理法 としては,焼 却,埋 立て,海 洋投 棄などが あるが 原料 の一部 として回収再利用 した り,別 の用途 に有効利 用す る資源化が可能 であれば,望 ま しい ことは云 うまで もない。近年,廃 棄物 の再生利用 に対す る認識 は,オ イ ル ショックを機に高 ま りを見せ,各 方面で このための試 みがなされてい る。上記 固形廃棄物を熱可塑性 プ ラスチ ックを結合剤 として固化,造 粒 して建材や路材,魚 礁, 農業材料等 に利用 しよ うとい う企て は,昨 今 の原油価格 の高騰 により経済的 メ リッ トを失 いつゝ あ る。プ ラスチ ック廃棄物の処理が問題 とな った のは丁度一昔前 のこと であ り,当 時筆者 らは粉砕処理 の問題に取 り組 んで いた。 熱可塑性プ ラスチ ックは粉砕時 に多量の発熱を伴 うた め,一 度破壊 されて も再 固結す る傾向があ り,常 温で粉 砕するのは極めて困難である。 しか し硅石やス ラグ等の 脆性固形物質 と混合粉砕する とある程度 まで微細物 とす ることがで きる。 この混合 粉砕産物を当該プ ラスチ ック の融点以上の温度下で圧縮 する ことにより,条 件によっ ては,可 成 りの強度を有す る造 粒体が得 られ ることが見 出された1)。 この造粒体の用途につ いて は各種の特性値 の測定をまたねば明確 には述べ られないが,廃 プ ラスチ ックとス ラグ等 の固形廃棄物か ら経済的 に実用に耐 え得 る材料が得 られ るな らば,公 害防止 と相俟 って一石二鳥 のことといえる。 当面プ ラスチ ックの含有量,或 いは混

Fluidity of Ultra-fine Palverized Coal

The internal friction of ultraifine coal was measured, and then the flow curve, the apparent viscosity and the yield value were measured too for both the fixed bed of ultra-fine coal and the fluidized bed.The coefficient of internal friction and the cohesive force were from 0.6 to 0.7 and from 70 to 80 g/cm2 respectively for the ultra-fine coal. These values were smaller than that of the wheat sold in the markets and larger than that of the standard sand. In case the ultra-fine coal becomes small in its size range, the internal friction of it decreases and the cohesive force of it increases.The flow curve is obtained from the shearing stress and the shearing rate, and it was considered that the fixed bed of urtra-fine coal shows the dilatant flow curve and would be the rheological pseudoplastic.The apparent viscosity for the ultra-fine coal increases in the case of increasing of the external force, and this becomes constant value in case of the external forcebe comes over the constant value. The fluidized bed shows the Newtonian flow because the viscosity of it is similar to that of water under the condition of the gas velocity of from 1 to 2 cm/sec.The yield value of fixed bed is very large in comparison with the other fluid, and this value increases in case of the large size range. The yield value decreases remarkably for the fluidized bed, and this value becomes about zero under the condition of the gas velocity of some 0.3cm/sec.