| With the rapid development of industrialization and urbanization, the domestic mineral resources have been far from the yields to satisfy demand of social and economic development. China is a great nation of import and export minerals, whose mineral products have been mostly depended on imports. Because of the complexity of the regional distribution of mineral resources, it will be introduced the harmful elements. So it is very important to analyze the poisonous and harmful elements in minerals. Owing to the large species and quantities of mineral products, a rapid testing method must be established. Atomic fluorescence spectrometry is a simple and convenient testing method, it can directly determine22different kinds of elements, such as As, Sb, Bi, Hg, Sn, Se, Ge, Pb, Cd, Te, Zn, Ag, Au, Pd, Rh, Cu, Co and so on.This paper is divided into three parts:one is the determination of total antimony in fluorspar by atomic fluorescence spectrum; the second is the investigation of antimony speciation in the high fluoride system; and the last part is test of total antimony in phosphate ore.1. A new method is described for determination of total antimony content in fluorspar by Chemical Vapor Generation-Atomic Fluorescence Spectrometry. Fluorspar samples were dissolved in the system of mixed acids HNO3+HF+HC1O4. After removing residue acid and dissolving sample with dilute hydrochloric acid, L-Cysteine as pre-reduction agent was added to pre-reduce antimony from the pentavalent state to the trivalent state under60℃for30min. The results indicated that the ion of fluorine could not interfere the fluorescence signals of Sb(III), but it could interfere the fluorescence signals of Sb(V) and determination of total antimony. After addition of L-cysteine or thiourea-ascorbic acid, the interference of the ion of fluorine on determination of total antimony could not be eliminated. The conditions of the instrument and hydride generation were optimized. The concentration of KBH4was15g/L and the concentration of HCl in sample solution was5%(V/V). The proposed method was applied to analyze the concentrations of total antimony in six fluorspar samples with satisfactory results. The detection limit was0.024μg/L. The precisions were1.8%-7.6%and the recoveries were93.6%-106.4%. It is showed that the experiment results were accurate and reliable.2. The method of Sb (Ⅲ) and Sb (Ⅴ) content determination in high fluoride system and the influence of fluorine ion on fluorescence signal intensity of Sb (Ⅲ) and Sb (Ⅴ) were researched. In hydrochloric acid, the fluorescent signal of Sb (Ⅴ) was masked by fluorine ion, and also the test of Sb (Ⅲ) was interfered by fluorine ion. By adding different masking agents for anti-interference, the interference of fluorine ion for Sb (Ⅲ) was eliminated, and at the same time there was no effect on the masking of fluorine ion for Sb (V). In high fluoride system, the influence of acid concentration on the fluorescence signal of Sb was studied. The results show that10g/L trisodium citrate as a masking agent for anti-interference met the requirement of the test, and the concentration of masking agent had no effect on the experimental results. The proposed method was applied to analyze the concentrations of Sb(Ⅲ) in three fluorspar samples, and the content of Sb (Ⅴ) was figured out by subtraction method with satisfactory results. The detection limit was0.0059μg/L. The precisions were0.9%-2.5%and the recoveries were98%-108%. It is indicated that the experiment results were accurate and reliable.3. A new method is established for determination of total antimony content in phosphate ore by Chemical Vapor Generation-Atomic Fluorescence Spectrometry. The phosphate ore samples were digested by aqua regia, and the antimony was extracted by hydrochloric acid. To make sure the key factors of dissolving samples, like acid medium, heating temperature and time of electric hot plate, the influence of coexistent elements was concerned about and the conditions of the instrument and hydride generation were optimized. The concentration of KBH4was25g/L and the concentration of HC1in sample solution was5%(V/V). The experiment results show that aqua regia was the best acid of dissolving sample among six acid medium. The optimal conditions of dissolving samples were that:the sample was heated0.5h under150℃, and it was evaporated nearly1-2mL under200℃in order to ensure all samples dissolved and no loss of antimony.The detection limit was0.005μg/L. The precisions were2.1%-3.6%and the recoveries were89%-101%. It is declared that the experiment results were accurate and reliable. |
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