Determination of calcium in ores and industrial products by X-ray fluorescence

X-Ray fluorescence method was applied to the determination of calcium in ores and industrial products, and the calibration curve method with cobalt as an internal standard was found to be satisfactory. The procedure is as follows: One hundred milligrams of cobaltic oxide is added to 400 mg of the sample, and the mixture is fused with 5 g of disodium hydrogen phosphate and 5 g of sodium fluoride as flux. The fused matter is crashed to fine powders, and the intensities of CaKα-1 and CoKα-2 of the powdered sample thus prepared are measured. From the ratio of the two intensities the content of calcium in the sample is determined using a calibration curve obtained by treating calcium carbonate in the same manner. Interferences from the other elements were not observed, and satisfactory results were obtained for four kinds of samples; phosphate rock, gypsum, cement and glass. The contents of calcium in eight samples of fluorspar were also determined by the X-ray method, and the fluorine contents calculated from the calcium contents were nearly identical with those by a colorimetric method.