The mineralogy of pyrrhotite from Sudbury CCN and Phoenix nickel ores and its effect on flotation performance

Abstract

The non-stoichiometric sulfide pyrrhotite (Fe (1-x) S), common to many nickel ores, occurs in a variety of crystallographic forms and compositions. In order to manipulate its performance in nickel processing operations either to target the recovery or rejection or pyrrhotite, one needs an understanding of pyrrhotite mineralogy, reactivity and the effect this may have on its flotation performance. In this study, a non-magnetic Fe 9 S 10 pyrrhotite from Sudbury CCN in Canada and a magnetic Fe 7 S 8 pyrrhotite from Phoenix in Botswana were selected to explore the relationship between mineralogy, reactivity and microflotation. Non-magnetic Sudbury pyrrhotite was less reactive in terms of its oxygen uptake and showed the best collectorless flotation recovery. Magnetic Phoenix pyrrhotite was more reactive and showed poor collectorless flotation, which was significantly improved with the addition of xanthate and copper activation. These differences in reactivity and flotation performance are interpreted to 1 be a result of the pyrrhotite mineralogy, the implications of which may aid in the manipulation of flotation performance.Keywords: pyrrhotite, mineralogy, oxidation, reactivity and sulfide flotation 2 INTRODUCTIONPyrrhotite Fe (1-x) S is one of the most commonly occurring metal sulfide minerals and is recognised in a variety of ore deposits including nickel-copper, lead-zinc, and platinum group element. Since the principal nickel ore mineral, pentlandite, almost ubiquitously occurs coexisting with pyrrhotite, the understanding of the behaviour of pyrrhotite during flotation is of fundamental interest. For many nickel processing operations, pyrrhotite is rejected to the tailings in order to control circuit throughput and concentrate grade and thereby reduce excess sulfur dioxide smelter emissions, e.g. Sudbury [1]. However, for some nickel processing operations, pyrrhotite recovery is targeted due to the abundant fine grained pentlandite locked in pyrrhotite, e.g. Phoenix pyrrhotite at Tati Nickel Mine. Therefore, the ability to manipulate pyrrhotite performance in flotation is of great importance. It can be best achieved if the mineralogical characteristics of the pyrrhotite being processed can be measured and the relationship between mineralogy and flotation performance is understood.The pyrrhotite mineral group is non-stoichiometric and has the generic formula of Fe (1-x) S where 0 ≤ x < 0.125. Pyrrhotite is based on the nickeline (NiAs) structure and is comprised of several superstructures owing to the presence and ordering of vacancies within its structure.Numerous pyrrhotite superstructures have been recognised in the literature, but only three of them are naturally occurring at ambient conditions [2,3]. This includes the stoichiometric FeS known as troilite which is generally found in extraterrestrial localities, but on occasion, has also been recognised in some nickel deposits. The commonly occurring magnetic pyrrhotite is correctly known as 4C pyrrhotite, has an ideal composition Fe 7 S 8 and monoclinic cr...

Constraints on Ore Genesis from Trace Ore Mineralogy: A New Occurrence of Kupčíkite and Paděraite from the Zhibula Cu Skarn Deposit, Southern Tibet

“…Pyrrhotite contains measurable Ni (mean 0.83 wt.%) and Co (mean 0.14 wt.%) (Table S6). Pyrrhotite is non-stoichiometric and has a generic formula of Fe 1-x S (0 < x < 0.125; e.g., [26]). Galena contains significant concentrations of Ag (mean 1.14 wt.%) and Bi (mean 2.31 wt.%), as well as detectable Se (mean 0.20 wt.%), Cu (mean 0.25 wt.%), Te (mean 0.05 wt.%), and Cd (mean 0.05 wt.%) (Table S7).…”

Influence of Mineralogy and Mineralogy Approach to Optimize Processing: A Case Study of Tin–Copper Polymetallic Ore

“…The key point is that pyrrhotite has a different microstructure, and with changes in structure, the mineral properties will also change [12,13]. Therefore, when the content of pyrrhotite is high, it is likely to be an important factor affecting the results of processing and the key to improved processing [14][15][16]. As a typical non-stoichiometric mineral, the chemical formula of pyrrhotite can be written as Fe1-XS, where x varies from 0 (FeS) to 0.125 (Fe7S8).…”

Influence of Water Quality on Sulphide Ore Oxidation and Speciation of Sulphur Anions during Autogenous Milling

“…Sulphide minerals easily oxidises when in contact with oxygen and water [26]. For ores containing pyrrhotite, the rate of oxidation is higher, since pyrrhotite is highly reactive [7,8,[26][27][28][29]. The oxidation of sulphide minerals in tailings results in acid production, thereby lowering the pH [30].…”