The invention relates to a measurement method of the phosphorous content in an
iron ore, in particular to a method for measuring the phosphorous content by adopting a
bismuth phosphomolybdate blue-
sulfuric acid photometry. The method comprises the following steps of: weighing 0.25g of sample and putting into a
platinum crucible containing about 2g of mixed fusing agent, putting in a
muffle furnace with the temperature of 100 DEG C, fusing for 10min and taking out; cleaning the exterior of the
platinum crucible, then putting the
platinum crucible into a
beaker containing about 80ml of hot water, adding 320ml of concentrated HNO on an electric furnace, heating at low temperature and dissolving, leaching the crucible out, taking the
beaker out, cooling, then transferring into a 250ml
volumetric flask, diluting to a scale and shaking up for later use; sucking 25ml of mother solution of a fusing sample in the
platinum crucible, putting into a 50ml
volumetric flask, adding 2.5ml of
bismuth nitrate solution, 5ml of
ammonium molybdate solution, 3ml of 8mol / L
sulfuric acid solution and 5ml of
ascorbic acid solution (prepared when needed), shaking up, carrying out color comparison at 750nm
wavelength, measuring an
absorbance value, and carrying out result conversion by using a guide sample with similar ingredients. The invention effectively solves the problem of instable
absorbance value in a method for measuring the phosphorous content by adopting a traditional
molybdenum blue
spectrophotometry and ensures that the
absorbance remains unchanged within two hours.