GB530048A - Improvements in or relating to the manufacture of reactive magnesium oxide - Google Patents

Abstract

530.048. Magnesium oxide. ELKINGTON, F., and CHESNEY. H. H. May 31, 1939, No. 16068. [Class 1 (iii)] A process for the production of magnesium oxide in the form capable of re-acting to give a cement comprises treating an aqueous slurry of calcined and slaked dolomite with a dilute aqueous brine, removing the magnesium hydroxide and introducing it while wet into an internally fired rotary kiln and calcining it for 1-2 hours at 850-1000‹C. In a modification, the slurry of magnesium hydroxide may be dried, e.g. on a tray drier, and the lumps of dry hydroxide added to the kiln as above. In Fig. 1, the kiln 11 lined with refractory bricks 12 and supported on roller bearings 13, 14 has cutting blades 15 attached to its walls inclining at an angle of 16 degrees to the vertical. The broken up material then passes to lifting trays 16 adapted to lift and then allow the material to drop through the hot gases. The lower end of the kiln is flared at 17 so that the material traverses the hottest part of the kiln to the radially disposed exit holes 18 provided with flap valves 19. In Fig. 2 the lower end of the rotary kiln is connected to a stationary combustion furnace 24. A firing wall 26 having an opening 27 is placed opposite an oil, gas or pulverized coal burner 25. The furnace is maintained at a temperature of about 1400‹C. whilst the cool end is at about 200‹C. Specifications 482,339 and 483,096 are referred to.