Abstract: 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.

Abstract: To recycle a residue after treatment of bauxite completely and effectively. To recover alkali which is used for the treatment. When alumina is extracted from bauxite with an alkali aqueous solution, 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.

Abstract: The present invention provides a process for treating sodium aluminosilicate which includes adding a calcium compound to sodium aluminosilicate; thermally treating the mixture of the sodium aluminosilicate and the calcium compound; and eluting the thermally-treated product with water or an aqueous solution to thereby solubilize a sodium component of the sodium aluminosilicate, recover sodium, and obtain a useful product containing sodium in very small amounts. The elution percentage of sodium can be increased by optimizing heating and elution conditions.

Abstract: 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.

Abstract: 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.