An improved method for the determination of chloride in iron ore, coal, coke, mill sludge, flue dust and sinter products by turbidimetry and validation of results obtained by indirect atomic absorption spectrophotometry

Chemistry Laboratory, Regional Center for Exploration and Research, Atomic Minerals Directorate, Eastern Region, AMD Complex, Khasmahal, Jamshedpur-831 002, Jharkhand, India E-mail : ptarafder@sify.com An improved and rapid procedure for the determination of chloride in iron ore, mill sludge, coal, coke, flue dust and sinter products etc. has been developed by turbidimetry, and the results obtained were validated by indirect atomic absorption spectrophotometry (AAS) method. Chloride in these samples were leached by 10% (v/v) nitric acid and then determined by the above two methods. A correlation curve was plotted between the results obtained by the two methods, representing the efficacy of the proposed method vis-à-vis the AAS method. The correlation coefficient of the linear regression was 0.98, demonstrating that both the methods are complementary to each other. The different experimental parameters such as choice of leaching agent, leaching time, effects of diverse ions, concentration of nitric acid etc. were studied in detail. The accuracy of the method was ascertained by estimating chloride content in some Certified Reference Materials (CRM) like Syenite sample (SY/3) and iron ore sample (BAM No. ECRM 687-1). The chloride values obtained for the CRMs were in excellent agreement with the recommended values, indicating that the method yielded fairly accurate results. The detection limit was found 0.05 µg/ml (based on mean plus 3 times standard deviation of blank, n = 5) while the RSD was found in the range 1-3% depending on the concentration of the analyte. The advantages of the proposed method are a spectrophotometer has been used for turbidity measurement in terms of absorbance in line with turbidimetric measurement of sulphate ion and HNO3 has been used for leaching of chloride in stead of hot water. &nbsp