Nickel Ore and Metals Analysis

Abstract

This article examines contemporary routine and umpire quality methods for the analysis of nickel ores, nickel metal and nickel alloys. Sample preparation and sampling are also discussed, but the emphasis is on sample preparation and analysis, since sampling is all too often done by people not part of the analytical laboratory. In order to analyze fully these materials, a laboratory must have at its disposal a wide range of instruments and methods, from the classical to the most modern, and frequently combinations of both. In keeping with the theme of this Encyclopedia, detailed methods are not given, and the reader should consult the references. The references themselves cover the period from roughly 1972 through 1997 but are not to be considered a definitive list. Unfortunately, most of the modern methods of analysis developed by chemists in nickel producers' laboratories have not been published, except as international or national standards. As an aid to the reader, a summary of International Organization for Standardization (ISO) and national standards is given immediately before the References. The author apologizes for any errors or omissions. The section on nickel ores is divided into two broad classifications: sulfide and lateritic ores. Greater emphasis is given to the sample preparation of laterites since they are more difficult to handle and many laboratories do not have as much experience working with them as with sulfides. Each broad classification is broken down into the analysis of “pay metals”, which are the reason the ore is mined, elements of environmental concern and other elements which are required for the metallurgical processing of the ore. Products from refineries fall into three broad categories: nickel metal in various forms, nickel oxides and ferronickel. For nickel metal, the emphasis is on trace‐element determinations; for nickel oxides and ferronickel, methods for the determination of nickel are also discussed. Nickel alloys cover a wide range of materials, from stainless steels to high‐nickel “superalloys”. For these samples the analytical requirements range from the major components of the alloy to minor alloying constituents to trace‐element determinations. As an aid to the analytical chemist in the laboratory, tables are presented summarizing recommended methods of analysis, and in most instances an alternative method, in case the laboratory does not have the equipment necessary to select the first choice. These methods have proven themselves in the laboratories of nickel producers and commercial laboratories familiar with the analysis of nickel‐bearing samples.