Krupp Polysius Ag

Magyar Aluminiumipari Troszt

Magyar Aluminiumipari Troeszt

Jozsef T Toth

Wolf Goldmann

Janos Steiner

Peter Tiggesbaumker

Jozsef Matyasi

Laszlo Zsembery

Gyorgy Kaptay

Gerhard Butschko

Bela Kokeny

Kalman Wenzly

Imre Penzes

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 method of burning, calcining or sintering fine-grain material in which the burnt material separated from the gas flow is supplied to a residence container from which a part of the material is returned to the burning zone and the remainder of the material is supplied to the cooling zone. Such a method is distinguished by a low heat and energy requirement and by a simple construction of the apparatus and permits ideal adaptation of the burning conditions to the particular material.

Method and apparatus for burning fine-grain material

Growing community of inventors

Almasfuzito, Hungary

Jozsef T Toth