| 摘要 |
<p>1298976 Alumina DORR-OLIVER Inc 16 Sept 1970 [17 Sept 1969] 44134/70 Heading C1A Alumina is produced from bauxite by digesting the bauxite with NaOH to give a hot, rather unstable solution of AlNaO 2 containing red mud impurities in suspension, separating the sodium aluminate solution from the red mud in a special settling tank, decomposing the aluminate to give aluminium hydroxide and calcing the hydroxide to give alumina. The tank contains a rotary rake structure with linear rake arms 32 hinged at V to the lower end of the shaft D enabling movement about a vertical axis. Drive arms 33 are fixed to the upper end part of the shaft and are connected to the rake arms by draft cables 34. The drive arms operate above the level of the sludge zone. These tanks may also be used for washing the red mud after separation of the aluminate.</p> |
