Determination of Symbiotic and Associated Elements in Tin Ore by ICP-MS Combined with Pressurized Acid Digestion and Detinning Process

Abstract

BACKGROUND Tin ore is a hard-to-decompose mineral. The main form is cassiterite (SnO2), and there are many symbiotic and associated elements. The commonly used acid-digestion method can barely dissolve SnO2, making it difficult for accurate measurement of symbiotic and associated elements in tin ore. OBJECTIVES To decompose the tin ore completely, and accurately determine the symbiotic and associated trace elements in ore. METHODS Hydrogen iodide can be produced in a non-aqueous state during the melting of ammonium iodide at a lower temperature, and the acidity of hydrogen iodide and the reductive decomposition of SnO2 by ammonia, and Sn separation by the sublimation of SnI4 which is the basis of the study. Under the catalysis of a high purity platinum, ammonium iodide was used to decompose cassiterite for 30 minutes in a Maffer furnace at 450℃. Tin was removed in the form of SnI4 with a removal rate of 98%. The residue was dissolved by 2 mL HF and 1 mL HNO3 using pressurized acid digestion. Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) was used to accurately determine 24 elements in tin ore. RESULTS The element detection limits are from 0.001 to 2.9 μg/g, and more than 90% of the elements have a relative standard deviation (RSD) of less than 5%. The relative error is less than 10%. CONCLUSIONS The method solves the problem of tin ore being difficult to decompose, can measure the coexisting metal elements, and is also suitable for determining trace and ultra-trace elements in tin ore with Sn contents between 1.27% and 62.49% and trace elements in tin concentrate.

Keywords

• tin ore
• metallic element
• the removal rate of tin
• ammonium iodide
• inductively coupled plasma-mass spectrometry