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Tangshan, China

Yang C.-S.,Tangshan Laboratory | Zhou J.-H.,Tangshan Laboratory | Kong X.-H.,Tangshan Laboratory | Sun J.,Laboratory of Tangshan Iron and Steel Group Ironworks
Yejin Fenxi/Metallurgical Analysis

The paper proposed an improved way of silicon-molybdenum blue spectrophotometric method which has been used in the determination of silica content within different ranges in fluorite and concentrate. Using sodium hydroxide as flux, the sample was melted in silver crucibles instead of expensive platinum crucible. The sample solution preparation process was optimized by using back-acidification method to improve the stability of the sample solution. Using aluminium trichloride to replace boric acid which has buffer effect to remove the interference of excessive fluorine with the solution, and the introduction of the silica in glassware was avoided during the whole operation. The way of acidification for the standard solution was changed. The calibration curve was linear in the range of 50-1000 μg, r≥0.9997. By analyzing and comparing the five fluorite standard samples with different content of SiO 2, the results of this method were consistent with the certified values of the standard samples and the found values of HF evaporation gravimetric method. All of the relative standard deviations were less than 0.5%. Through verification by the "t-Test", there was no significant difference between the results of this method and the certified values of the standard samples. This improved method has simple chromogenic system. It can be used for analyzing fluorite containing no more than 62.00% SiO 2. Source

Yang C.-S.,Tangshan Laboratory | Yu Y.-M.,Tangshan Laboratory | Qiu H.-X.,Tangshan Laboratory
Yejin Fenxi/Metallurgical Analysis

The analysis method of titanium dioxide content in oxidized and calcined vanadium-titanium pellet by hydrogen peroxide spectrometry after microwave alkali fusion at atmospheric pressure was established. The desktop microwave chemical experiment furnace was used as heat source, and the mixture of sodium peroxide and sodium hydroxide was used as the flux for fusion. The sample was fully decomposed after digestion for 14 min under microwave power of 480 W. The alkali fusion matters were acidified with sulfuric acid-phosphoric acid. Much iron matrix would be complexed with phosphoric acid, eliminating the interference. Partial sample solution was colored in sulfuric acid medium using hydrogen peroxide as coloring agent. The content of titanium dioxide in sample was obtained by standard curve method. The calibration curve of titanium dioxide in range of 0-40 μg/mL was established, and the linear correlation coefficient was no less than 0.999 8. The influence of coexisting vanadium and chromium could be eliminated by fluoride fading reference solution. The actual samples were also analyzed by X-ray fluorescence spectrometry (XRF) and titration method in various laboratories. The determination results of proposed method were consistent with those obtained by other methods, and the relative standard deviation (RSD) was between 0.22% and 0.82%.The results could meet the requirements of industrial production. ©, 2015, Central Iron and Steel Research Institute. All right reserved. Source

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