Showa Denko K.k.

Hitachi, Ltd.

Showa Denko Kabushiki Kaisha

Hitachi Engineering Co., Ltd.

Yoshiyuki Takenaka

Makoto Saito

Isao Ishikawa

Kenji Uchida

Masakatsu Sakamoto

Yasuo Kawai

Yasutoku Yamada

Yasunori Yamada

Chosei Sato

A process in which alumina is extracted from bauxite with an aqueous alkali solution, and a desilication product is precipitated such that the product is not contained in a bauxite residue and does not form a complex. The desilication product is mixed with a calcium compound, and the mixture is calcined, to thereby solubilize and recover an alkali component of the product. In addition, an alkali component is removed from a residue (a solid product), and the residue is effectively used as a resource.

Process for treating bauxite in which a desilication product and an insoluble residure are separately precipitated

In the manufacture of alumina by the Bayer process, a method comprising the steps of bringing the overflow from a multistage red mud thickener into counterflow contact with the steam generated in consequence of the flashing of bauxite-dissolved slurry so as to effect exchange of heat therebetween, separating and removing sand from the slurry by regulating the rate at which the slurry is discharged from the bottom of the column, and circulating the heated overflow and using it as the wash water in the former stage of the said thickener, all the said operations performed in one and the same column; and a device provided with inlet and outlet pipes for the overflow, an overflow type condenser, inlet and outlet pipes for the slurry, and a pipe for the removal of sand so as to effect the operations of the said method wholly in one and the same column.

Device for waste heat recovery and sand removal in the Bayer process

There is disclosed a horizontal type hydrohoist, in which slurry is forced to feed under lower pressure into feed pipes which are connected to a transport pipeline at their one ends and to a high pressure clear water pump at the others, said pump being adapted to deliver clear water under a high pressure, after which clear water is transferred under a high pressure through said feed pipe from said high pressure clear water pump, thereby transferring said slurry. This hydrohoist system presents the provision of means for preventing mixing and its spreading at the boundary portion between slurry and water within the feed pipes. More particularly, a separator which is designed not to rotate during the transfer is inserted in the aforesaid boundary portion in a manner that the separator may be transferred together with fluid, thus preventing the mixing of water with slurry as well as the resultant spreading thereof. According to a further aspect of the invention, at the completion of the slurry transfer under a high pressure, the separator is caused to be gradually slowed down to stop for the purpose of obviating a water hammer phenomenon within the pipings. In addition, after the removal of the slurry remaining around the separator by using a high pressure water, the feeding of the high pressure water is interrupted, thereby preventing mixing and its spreading at the boundary portion of water with slurry at the time of the subsequent introduction of slurry under lower pressure.

Horizontal type hydrohoist

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Kamakura, Japan

Yoshiyuki Takenaka