Determination of molybdenum in molybdenum concentrate and molybdenum calcine by sodium peroxide fusion-ammonium thiocyanate differential spectrophotometry

In a high-alumina crucible,sample was fused at 700 ℃ with sodium peroxide for 5-10 minutes,then the content of molybdenum in molybdenum concentrate and molybdenum calcine was determined by ammonium thiocyanate differential spectrophotometry.The conditions for sample fusion,sample solution preparation and determination were optimized.The interference of MnO2-_4 was eliminated by addition of absolute ethyl alcohol,and the impact of tungsten(VI),chromium(Ⅵ),vanadium(Ⅴ) and other coexisting ions was eliminated by precipitation adsorption with ferric trichloride solution and sodium tartrate masking.The results showed that at the absorption wavelength of 480 nm,the mass concentration of molybdenum conformed to Beer's law within the range of 14.0 to 26.0 μg/mL,and the detection limit was 4.2×10-2 μg/mL.This method has been used for the determination of molybdenum in molybdenum concentrate run samples GKY-01,the production samples of molybdenum concentrate and molybdenum calcine.It was found that the results were in accordance with the reference values or those obtained by gravimetric method,and the relative standard deviations(RSDs,n=11) were 0.10 %-0.14%.