Tangshan, China
Tangshan, China

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Li H.,Tangshan Laboratory | Yang C.-S.,Tangshan Laboratory | Yu Y.-M.,Tangshan Laboratory | Qiu H.-X.,Tangshan Laboratory
Yejin Fenxi/Metallurgical Analysis | Year: 2017

Sulfosalicylic acid spectrophotometry is a classical method for the determination of iron. For phosphate ore, however, the solution is easily spattered in sample dissolution process in open PTFE beaker on electric hot plate. Moreover, PO4 3- can react with Ca2+ and Mg2+ in phosphate ore to form precipitates during coloring at pH 8-11, which influences on the determination of iron. The Mn2+ in phosphate ore containing high content manganese also has interference. The phosphate ore samples were rapidly dissolved in closed high-pressure microwave digestion system using HNO3-HF-SSA (sulfosalicylic acid) mixture. The content of iron (in Fe2O3) in phosphate ore was determined in hexamethylenetetramine medium by sulfosalicylic acid spectrophotometry. The microwave digestion conditions were obtained as below: the power was 400 W, the pressure was 0.5 MPa, and the digestion time was 10 min. The optimized dosage of acid mixture was 2 mL HNO3-5 mL HF-2 mL 200 g/L SSA solution. The certified reference material and actual sample of phosphate ore were analyzed according to the experimental method. The found results were consistent with those obtained by national standard method (GB/T 1871.2-1995) and inductively coupled plasma atomic emission spectrometry (ICP-AES) as well as certified values. The relative standard deviations (RSD, n=5) were less than 2%, which could meet the determination requirements of Fe2O3 (0.05%-10%) in phosphate ore. © 2017, CISRI Boyuan Publishing Co., Ltd. All right reserved.

Yang C.-S.,Tangshan Laboratory | Yu Y.-M.,Tangshan Laboratory | Qiu H.-X.,Tangshan Laboratory
Yejin Fenxi/Metallurgical Analysis | Year: 2015

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.

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 | Year: 2012

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.

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