Recovery of magnesia

Claim 1

A METHOD OF OBTAINING MAGNESIUM OXIDE FROM NATURAL ROCK CONTAINING AN INTIMATE MIXTURE OF MAGNESITE AND AT LEAST ONE OF THE COMMONLY ASSOCIATED IMPURITIES DOLOMITE, CALCIUM CARBONATE, SILICA AND SILICATES, WHICH COMPRISES CRUSHING THE ROCK UNTIL IT WILL SUBSTAN TIALLY ALL PASS A SCREEN OF FOUR MESHES TO THE LINEAR INCH BUT BE RETAINED ON A SCREEN OF 65 MESHES TO THE LINEAR INCH, SELECTIVELY CALCINING THE GRANULAR ROCK AT A TEMPERATURE EXCEEDING 1100* F. BUT NOT EXCEEDING 2000* F. TO EXPEL CARBON DIOXIDE FROM THE MAGNESIUM CARBONATE WITHOUT GREATLY CHANGING THE PHYSICAL CHARACTER OF SILICA AND SILICATES PRESENT, THEREBY PRODUCING LIGHT, FRIABLE MAGNESIA, THE WHILE MAINTAINING THE MATERIAL BEING CALCINED IN A NEAR-FLUID STATE BY PASSING GAS UPWARDLY BETWEEN ITS PARTICLES TO CAUSE ATTRITION AND SELECTIVELY REDUCE THE FRIABLE MAGNESIA TO A FINE, LIGHT POWER, AND THEREBY ALSO TO SELECTIVELY LIFT SAID FINE, LIGHT POWDER IN THE GAS STREAM AND CONVEY IT THEREIN TO A COLLECTOR, COLLECTING THE MAGNESIA SO CONVEYED AS A DUST SUBSTANTIALLY ALL FINER THAN 0.01 INCH, LEAVING BEHIND IN THE CALCINING ZONE THE COARSER AND HEAVIER IMPURITIES AND REMOVING THESE BY GRAVITY FROM THE CALCINING ZONE AS A SEPARATE PRODUCT.

Claim 2

A METHOD OF OBTAINING MAGNESIUM OXIDE FROM NATURAL ROCK CONTAINING AN INTIMATE MIXTURE OF MAGNESITE AND AT LEAST ONE OF THE COMMONLY ASSOCIATED IMPURITIES DOLOMITE, CALCIUM CARBONATE, SILICA AND SILICATES, WHICH COMPRISES CRUSHING THE ROCK UNTIL IT WILL SUBSTAN TIALLY ALL PASS A SCREEN OF FOUR MESHES TO THE LINEAR INCH BUT BE RETAINED ON A SCREEN OF 65 MESHES TO THE LINEAR INCH, SELECTIVELY CALCINING THE GRANULAR ROCK AT A TEMPERATURE EXCEEDING 1100* F. BUT NOT EXCEEDING 2000* F. TO EXPEL CARBON DIOXIDE FROM THE MAGNESIUM CARBONATE WITHOUT GREATLY CHANGING THE PHYSICAL CHARACTER OF SILICA AND SILICATES PRESENT, THEREBY PRODUCING LIGHT, FRIABLE MAGNESIA, THE WHILE MAINTAINING THE MATERIAL BEING CALCINED IN A NEAR-FLUID STATE BY PASSING GAS UPWARDLY BETWEEN ITS PARTICLES TO CAUSE ATTRITION AND SELECTIVELY REDUCE THE FRIABLE MAGNESIA TO A FINE, LIGHT POWER, AND THEREBY ALSO TO SELECTIVELY LIFT SAID FINE, LIGHT POWDER IN THE GAS STREAM AND CONVEY IT THEREIN TO A COLLECTOR, COLLECTING THE MAGNESIA SO CONVEYED AS A DUST SUBSTANTIALLY ALL FINER THAN 0.01 INCH, LEAVING BEHIND IN THE CALCINING ZONE THE COARSER AND HEAVIER IMPURITIES AND REMOVING THESE BY GRAVITY FROM THE CALCINING ZONE AS A SEPARATE PRODUCT.