Method for measuring phosphorous content by adopting bismuth phosphomolybdate blue-sulfuric acid photometry

Abstract

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.

Description

technical field [0001] The invention relates to a method for determining the phosphorus content of iron ore, in particular to a method for determining the phosphorus content by bismuth phosphomolybdenum blue-sulfuric acid photometry. Background technique [0002] The traditional determination method of phosphorus content in iron ore adopts molybdenum blue spectrophotometry (GB / T6730.18-2006), using ammonium molybdate to generate phosphomolybdenum yellow, which is reduced to phosphomolybdenum blue with ascorbic acid, thereby colorimetric. [0003] However, ascorbic acid has a short shelf life and is extremely unstable. It will also form a blue color that interferes with the measurement. During the colorimetric process, the absorbance fluctuates, and the readings will change like a stopwatch. It is even more unstable in spring, summer, and autumn. , in severe cases, the absorbance is "∞", resulting in the failure of the assay. Even adding the stabilizer thiourea has no effect...

AI Technical Summary

Problems solved by technology

[0004] The present invention aims at the above-mentioned deficiencies in the traditional iron ore phosphorus content determination method, and provides a bismuth phosphomolybdenum blue-sulfuric acid photometric method for determining phosphorus by adjusting the acidity of the mother liquor, effectively solving the problem of unstable extinction value drift, and keeping the luminosity basically unchanged. Quantitative method