リン鉱石の比表面積とX線回折による観察

抄録

In view of the fact that the specific surface area of phosphate rock and its crystallite size are important factors that impart such physical properties as will affect its chemical reactivity with sulfuric acid to produce calcium superphosphate, its specific surface area and crystallite size were respectively measured. The specific surface area of various phosphate rocks which are found deposited throughout the world was determined by the method of liquid adsorption with stearic acid in benzene solution, and the method of gas adsorption with ethylether, respectively.
The results were as follows.
The specific surface area measured by gas adsorption showed larger value than that by the method of liquid adsorption, but both the values showed the same tendency. The specific surface area measured by the method of liquid adsorption ranged from 3 to 8m²/g and that by the method of gas adsorption ranged from 8 to 20m²/g. The specific surface area of Gf (Gafsa), Ko (Kosseir) etc. were larger than those of F (Florida), Ma (Makatea) etc.
The difference between these specific surface area values is attributed to a lesspenetration of stearic acid into the internal surface of phosphate rocks. In general, the specific surface area of phosphate rock increases with increasing the content of carbonate in the phosphate rock.
Determination of the crystallite size was made from half value breadth of the X-ray diffraction pattern. The crystallite sizes of F68 and F66 rocks were larger than those of Gf, Ko, and An rocks, etc. Carbonation seems to reduce the crystallite size of the phosphate rock and thereby increase the specific surface area of the phosphate rock.
The reactivity of phosphate rock with sulfuric acid was deduced by measuring CaO/P₂O₅ ratio and carbonate content, the specific surface area by the convenient method of adsorption of stearic acid, and crystallite size etc.