IMPROVEMENT TO THE BAYER PROCESS FOR THE PRODUCTIO

专利名称：IMPROVEMENT TO THE BAYER PROCESS

FOR THE PRODUCTION OF ALUMINATRIHYDRATE BY MEANS OF ALKALINELEACHING OF BAUXITE, SAID METHODCOMPRISING A PREDESILICIFICATION STEP

发明人：TIZON, ERIC,FRYNS, CLOTILDE申请号：EP05771007.1申请日：20050511公开号：EP1751059A1公开日：20070214

摘要：The invention relates to the Bayer process which comprises the grinding (L, B)and the subsequent leaching (N2, A) of a bauxite by bringing same into contact with asodium aluminate liquor (20b, 120b). The aforementioned leaching results in theformation of a suspension (3a, 103) which is treated in order to separate the insolubleresidues (5a, 105a) from the sodium aluminate liquor. Next, the liquor is decomposed (D)and, subsequently, recycled as a leach liquor (20, 120) after being (i) separated from thealumina trihydrate (11, 111) precipitated during the decomposition step and (ii)concentrated by means of evaporation (E). The inventive method comprises apredesilicification treatment (P) during which the ground bauxite, prior to leaching, isbrought into contact with an aqueous sodium solution. The invention is characterised inthat the predesilicification treatment comprises the use of an aqueous sodium solution(30, 130) having a concentration of carbonates, sulphates and, optionally, chlorides, whichis expressed as a percentage in relation to the caustic soda concentration and which is

less than half of the concentration of the corresponding impurities of the decomposedliquor (8, 108).

申请人：ALUMINIUM PECHINEY

地址：725, Rue Aristide Bergès 38340 Voreppe FR

国籍：FR

代理机构：Fénot, Dominique

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