Study On The Determination Of Micro Molybdenum In Ni-mo Ore By Spectophotometry

With the progress of modern science and technology and the development of theworld economy, the application of molybdenum is broadening. The content ofmolybdenum element in nickel molybdenum ore is an important index to show theirgrade height or not, also it is a rich resource in China. Therefore, accurate determinationand extraction of molybdenum in nickel molybdenum ore are important.Spectrophotometry is simple, rapid, sensitive, accurate, simple operation, lowrunning cost, and wide applied method. At present, classical spectrophotometry forassaying of low contents of molybdenum is use thiocyanate as chromogenic reagent todetermine molybdenum, but it has low sensitivity and the complex is not stable enough.This thesis chooses the ion association reagent and the excellent Fluorescent Ketonechromogenic agent. Through the optimization of study, this method has high accuracyand is easy to operate. Compared to similar analysis method, it has higher sensitivity.For provide research reference, molybdenum content determination of Nickelmolybdenum ore can be directly used in production practice. Main projects and resultsare as follow:1. Mo（Ⅵ） was reduced to Mo（Ⅴ） by ascorbic acid-sulfocarbamide with Fe（Ⅲ）catalyter in sulfuric acid solution, and the [MoO（SCN）5]2-complex anion was formed inan excess of thiocyanate, the alkaline cationic dye acridine red-[MoO（SCN）5]2-ion-association complex was generated in the presence of Arabic gum. This methodnew method has high sensitivity and good accuracy compared with national standardmethod, and was employed to test in real samples, and obtained satisfy results.Mo（Ⅵ）-Acridine red-Thiocyanate-Arabic gum ion-association complex hasmaximum absorbance against reagent blank at553nm, and its apparent molarabsorptivity is2.7×10⁵L·mol^-1·cm^-1. Beer’s law is obeyed at the range of0.0017～80μgMo（Ⅴ）·mL^-1, and the detection limit（3S/N） is0.0017μg·mL^-1.2. High performance chromogenic reagent Phenylfluorone and Mo（Ⅵ） formed redcomplex at room temparture in the presence of cetyltrimethyl ammoniumbromide（CPB）, and this red complex was established for determination micro Mo（Ⅵ）by spectrometry. This method has high sensitivity and higer selectivity, and obtainedstaisfied analysis results vs FAAS.Phenylfluorone-Mo（Ⅵ） red complexhas maximum absorption wavelength523nm,its apparent molar absorptivity is2.2×105L·mol^-1·cm^-1. the linear in obeyed in the rangeof0～28μg·mL^-1Mo（Ⅵ）.3. The extraction rate is greatly affected on different pretreatment for sample. Inthis reasearch, the Mo（Ⅵ） was leaching byroast-alkali melting Ni-Mo ore, and theextraction rate of Mo（Ⅵ） in Ni-Mo ore was measured by FAAS. The monofactorial andorthogonal test applied to optimize the conditions of extraction micro molybdenum from Ni-Mo ore. The optimization extraction conditions are flows: the Ni-Mo mineralsparticle size120mesh, temperature700℃, roast time30min, dosage of Na₂O₂over-dose3.0times in stoichiometric ratio.4. The analysis results of Molybdenum from Ni-Mo ore by Phenylfluorone-Mo（Ⅵ）red complex spectrophotometry were compared with FAAS, our results is basiclycoincident and satisfied, and this spectrophotometry is sensitive, simple, accurate,economical, wide applicability vs other method.