Magyar Aluminiumipari Troszt

Magyar Aluminiumipari Troeszt

Gyorgy Kaptay

Jozsef Matyasi

Laszlo Zsembery

Bela Kokeny

Gyula Horvath

Karoly Solymar

Jozsef T Toth

Zoltan Osvald

Gyorgy Dobos

Sandor Nemeth

Imre Penzes

Zoltan Felfoldi

Maria Toth Nee Homostrei

Process for the preparation of alkali-poor .alpha.-alumina for ceramic purposes. Technical grade aluminum hydroxide is activated and calcinated in the presence of a mineralizing mixture comprising halides and boron compounds. The process further comprises activating aluminum hydroxide at a temperature of 500-600 degrees C., washing the activated product with alkali-free water containing calcium ions and having a conductivity not exceeding 70 .mu.S/cm until the alkali content expressed in Na.sub.2 O becomes lower than 0.15% by weight, adding 0.4-0.7% by weight of a mineralizing mixture to the washed product, and calcinating the same at a temperature of 1200-1350 degrees C.

Process for the preparation of alkali-poor .alpha.-alumina for ceramic

The invention relates to a process for preparing alumina being suitable for layer chromatography. The alumina suitable for layer chromatography is prepared in accordance with the invention in such a manner that an aluminium trinydroxyde containing 34 to 37% by weight of bayerite, 3 to 5% by weight of pseudoboehmite and 60 to 62% by weight of amorphous aluminium trihydroxide is heated at 300.degree. C. to 400.degree. C. for 2 to 4 hours. The activated alumina thus produced is snow-white, has a large specific surface and its average grain size is within the range between 8 and 20 .mu.m. The product complies with the requirements of layer chromatographical technique.

Process for preparing alumina being suitable for layer chromatography

Disclosed is a method for the treatment of the red mud byproduct of the Bayer aluminum process, wherein limestone, hydrated lime or other CaO-containing material is added to the red mud in certain molar proportions to the ingredients of the red mud, then the mixture is further mixed with a reducing agent, and the entire mixture is subjected to a reducing heat treatment during the course of which the mix becomes softened or molten. The iron and the slag are separated from each other while the mix is still molten, or after it has been cooled, and then the Na and Al-content of the slag is extracted with a sodium carbonate solution containing a caustic, or with a sodium carbonate solution and a solution of a caustic in two steps.

Method for the treatment of red mud

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Almasfuzito-felso, Hungary

Gyorgy Kaptay