Determination of Antimony Content in Antimony Ores by Inductively Coupled Plasma-Optical Emission Spectrometry
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ABSTRACT
BACKGROUNDChemical phase analysis of antimony ores involves three mineral phases:valentinite, stibnite and insoluble antimonate. Solvents used for extracting various antimony mineral phases are different. In addition, coexisting ions are complex and concentration gradients vary greatly. These factors affect the accurate determination of antimony chemical phases by inductively coupled plasma-optical emission spectrometry (ICP-OES).OBJECTIVESTo solve the problem during rapid and accurate measurement of chemical phases of antimony ore.METHODSThe effects of hydrochloric acid, nitric acid and potassium sulfate-nitric acid-sulfuric acid on the determination of antimony by ICP-OES were studied with valentinite, stibnite and antimonate as selective separation solvents.RESULTSThe same concentration of hydrochloric acid and nitric acid medium had no effect on the determination of antimony. The same standard solution series can be used to determine antimony in valentinite and stibnite. Hydrolysis of antimony can be avoided by using 15%-20% hydrochloric acid or nitric acid of. Mixed acid medium (4g/L potassium sulfate-15% nitric acid-3% sulfuric acid) had an effect on the determination of antimony. The matrix matching method can be used to solve the problem. In determining the amount of antimony in antimonate, the calibrated solution was formulated to add the same amount of mixed acid as the antimonate leaching agent. The detection limits of antimony in valentinite, stibnite and antimonate mineral phases by ICP-OES were 0.0006%, 0.0012% and 0.0021%, respectively, by choosing the 206.833nm line as the analytical line, under optimized analytical method flow and measurement parameters. The relative standard deviations (n=12) of the method were 0.16%-5.76%, and the absolute relative deviations of phase addition and total amount were 0.07%-7.38%.CONCLUSIONSThe precision and accuracy of the method meet the quality control requirements of antimony ore chemical phase analysis, and provide fast and accurate measurement of antimony ore chemical phase.
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