Assessment of a spodumene ore by advanced analytical and mass spectrometry techniques to determine its amenability to processing for the extraction of lithium

A combination of analytical microscopy and mass spectrometry techniques have been used to detect and characterise different lithium minerals in a LCT-Complex spodumene-type pegmatite from Pilgangoora located in the Pilbara region of Western Australia. Information collated by these techniques can be used to predict processing amenability. Samples were categorised into three subsamples (Pil1, Pil2, Pil3) based on colour and texture having different lithologies. The mineralogy and liberation characteristics of samples were characterised using automated mineralogy techniques and the Li content and elemental distribution within minerals defined using instrumentation with secondary mass spectrometry capabilities. The majority of lithium is associated with spodumene particles with minor amounts of lithium bearing micas and beryl in the Pil1 sample, whereas in Pil2 and Pil3 spodumene is largely the lithium source. In the Pil1 sample a proportion of spodumene particles have undergone alteration with spodumene being replaced by micaceous minerals of muscovite, lepidolite and trilithionite, as well as calcite. In Pil2 and Pil3 samples the spodumene particles are generally free of mineral impurities except minor intergrowths of quartz, feldspar and spodumene are evident in the coarser fractions. Based on mineralogical observations in the current study, the majority of the main gangue minerals quartz, K feldspar and albite can be rejected at a coarse grind size of −4 mm, to recover 90% of the spodumene with Li upgrade from 0.99–1.5 wt% Li to 3.0–3.5 wt% (6.5–7.5 wt% Li 2 O). The iron content (81–1475 ppm) in the spodumene is low and therefore make these spodumene concentrates suitable for use in ceramic and glass applications. Recovery of spodumene in the coarse fractions could be improved by further particle size reduction to liberate spodumene from micas and feldspars in the middling class, which account for between 15 and 49% of the sample. However, the requirement to remove mineral impurities in the spodumene in downstream processing will be dependent on the method of processing as the presence of Li bearing micas, calcite and feldspar can be beneficial or detrimental to lithium recovery. The high content of Rb (1 wt%) and the abundance of free grains makes K feldspar a source of rubidium, particularly in the Pil3 sample which has K feldspar in high abundance (21 wt%) and can potentially be recovered by reverse flotation technique. The low concentrations of the Ta, Nb and Sn minerals identified in samples were found to be fairly well liberated and could be recovered by conventional gravity separation techniques

A Pre-Landing Assessment of Regolith Properties at the InSight Landing Site

This article discusses relevant physical properties of the regolith at the Mars InSight landing site as understood prior to landing of the spacecraft. InSight will land in the northern lowland plains of Mars, close to the equator, where the regolith is estimated to be ≥3--5 m thick. These investigations of physical properties have relied on data collected from Mars orbital measurements, previously collected lander and rover data, results of studies of data and samples from Apollo lunar missions, laboratory measurements on regolith simulants, and theoretical studies. The investigations include changes in properties with depth and temperature. Mechanical properties investigated include density, grain-size distribution, cohesion, and angle of internal friction. Thermophysical properties include thermal inertia, surface emissivity and albedo, thermal conductivity and diffusivity, and specific heat. Regolith elastic properties not only include parameters that control seismic wave velocities in the immediate vicinity of the Insight lander but also coupling of the lander and other potential noise sources to the InSight broadband seismometer. The related properties include Poisson’s ratio, P- and S-wave velocities, Young’s modulus, and seismic attenuation. Finally, mass diffusivity was investigated to estimate gas movements in the regolith driven by atmospheric pressure changes. Physical properties presented here are all to some degree speculative. However, they form a basis for interpretation of the early data to be returned from the InSight mission.Additional co-authors: Nick Teanby and Sharon Keda

Alternative lixiviants to cyanide for leaching gold ores

Over 25 alternative lixiviant processes to cyanide have been tested in the laboratory; some of which have been successful for niche applications. The process conditions, applications and current status of the most attractive are reviewed in this chapter with an emphasis on publications since 1995. Most work has focused on thiosulfate, thiourea, and halide processes. Oxidative chloride-, sulfide-, and ammonia-leaching processes are generally more applicable for the extraction of gold or platinum group metals as a byproduct from base metal sulfide concentrates. Despite the research interest and pilot plant trials on many of the noncyanide gold lixiviants, the majority are still at the development stage. The most advanced alternative lixiviant is thiosulfate leaching of carbonaceous preg-robbing ores, which has been largely developed by Newmont Mining, Placer Dome, and Barrick Gold. More recent development of a thiosulfate-leaching plant at Barrick Gold's Goldstrike operation has alluded to the complex and unstable nature of this method of leaching gold and the significant process design difference of using thiosulfate over conventional cyanide. Further work by the industry and its stakeholders is required to continue developing robust overall process flow sheets incorporating gold recovery, reagent recycling, and impurity control for a wider range of ore applications using alternative lixiviants to cyanide. Some chemicals used such as ammonia or elements leached from ore, such as mercury, also pose health, safety, and environmental concerns. Consequently, proper disposal of wastes and sustainable development issues also have to be considered in process designs

Thiosulfate as an alternative lixiviant to cyanide for gold ores

Thiosulfate is generally considered to be an attractive alternative reagent to cyanide for processing gold. It is relatively inexpensive and nontoxic, forms strong gold and silver complexes, and readily leaches gold ores when catalyzed by Cu(II). Research over the past 30 years has focused mostly on the understanding and applying the copper-catalyzed ammoniacal thiosulfate system to carbonaceous ores and copper–gold ores where gold recovery is poor when using cyanide or where cyanide consumption is high. Researchers have also investigated ammonia-free and alternative oxidant systems to mitigate environmental issues associated with the use of ammonia. Barrick Gold Corporation developed and commercialized a copper-calcium thiosulfate process, which is currently in use at Goldstrike, Nevada, USA. This chapter reviews recent advances in understanding of the chemistry and mechanism of gold dissolution, influence of mineralogy, certain cations and anions, as well as gold recovery options. The speciation and stability of the thiosulfate system are considered under typical leaching conditions, together with examples of leaching various gold ores that have been reported in the literature. Further work by the industry is required to continue developing robust overall process flow sheets incorporating gold recovery, reagent recycling, and impurity control for a wider range of ore applications

AUTOMATED MINERALOGY

This landmark publication distills the body of knowledge that characterizes mineral processing and extractive metallurgy as disciplinary fields. It will inspire and inform current and future generations of minerals and metallurgy professionals. Mineral processing and extractive metallurgy are atypical disciplines, requiring a combination of knowledge, experience, and art. Investing in this trove of valuable information is a must for all those involved in the industry-students, engineers, mill managers, and operators. More than 192 internationally recognized experts have contributed to the handbook's 128 thought-provoking chapters that examine nearly every aspect of mineral processing and extractive metallurgy. This inclusive reference addresses the magnitude of traditional industry topics and also addresses the new technologies and important cultural and social issues that are important today

Distribution and agglomeration of gold in arsenopyrite and pyrite.

The form and location of gold in the structure of arsenopyrite and pyrite minerals, and the mechanisms for the mobility agglomeration of gold in arsenopyrite during thermal treatment, have been studied using a combination of Rietveld X-ray diffraction refinement, Convergent Beam Electron Diffraction (CBED) and Atomic Location by Channelling Enhanced Microanalysis. The basic structure of all the arsenopyrite compositions studies, has been shown to be monoclinic P2(subscript)1/c, regardless of the variation in stoichiometry. An increase in the arsenic to sulfur ratio in the natural arsenopyrites was found to be associated with an increase in unit cell dimensions accompanied by expansions within the iron-centred octahedra along the [101] direction of the monoclinic cell and concommitant contractions of the octahedra in the (101) plane. There was no obvious relationship between variation in stoichiometry and structure of arsenopyrite which could provide information as to possible substitution of gold in its structure. However, atomic displacements caused by twinning or disorder, may help to incorporate gold.The synthesis of auriferous arsenopyrites showed that gold has to be in an ionic form to be taken up in the structure. The form of the gold species affects the distribution of gold in the structure, being chemically zoned when derived from a dichloro complex and more evenly distributed when derived from a hydrosulfido complex. It is suggested that rapid crystallisation, with resultant displacement faults along the b-axis, may contribute to higher concentrations of gold in the natural arsenopyrite structure. Electron probe microanalysis showed a possible slight iron-deficiency in some of the auriferous arsenopyrite grains analysed. However, the errors in the analyses were too high to provide conclusive evidence of gold substitution in the iron sites, as has been proposed in the literature.Analyses of natural and synthetic pyrites showed no deviations in structural parameters which could indicate possible substitution of gold or other impurities within the structure.Electron channelling experiments showed that gold was located on the sulfur sites in pyrite. In arsenopyrite, there was some evidence for gold located on the iron sites, however, most gold was interstitial, probably situated between the octahedra. This location is probably facilitated by the presence of the displacement faults as observed by CBED in the synthetic auriferous arsenopyrite.Breakdown of arsenopyrite under thermal treatment was topotactic along its b-axis, which converts to the a-axis in the pyrrhotite structure, following a reconstruction mechanism based on the preferential removal of arsenic over sulfur. Gold was visually recorded exsolving from the arsenopyrite structure and agglomerating as liquid metal globules as the arsenopyrite was chemically altered during thermal treatment under the Transmission Electron Microscopy electron beam. Gold became mobile on the decomposition of arsenopyrite, but this was not observed until a temperature of approximately 470 degrees celsius was reached. Above the temperature both solid solution and particulate gold became mobile. The interaction of arsenic vapour and gold reduced the melting point of gold.The observations on the effects of arsenic residence time, and the relative mobility of solid solution and particulate gold during the thermal decomposition of auriferous arsenopyrite and pyrite, have significant implications for improved industrial extraction of gold from these minerals

Assessment of Li ore to determine its amenability to processing for the extraction of lithium

With the impetus for less reliance on fossil fuels and cleaner environments, the ability to be able to extract lithium used in rechargeable batteries for portable electronic devices from ores economically, is essential. However a comprehensive understanding of the deportment of lithium and associated minerals in some ore bodies is limited. To facilitate further process development, a comprehensive understanding of the deportment of lithium and associated minerals in ore bodies is essential to allow the industry to predict the response of ore reserves to metallurgical treatment options. To quantify the different lithium bearing minerals in the ore, the chemistry and structure characteristics of a suite of Li mineral phases were examined and defined prior to examining ore material. The mineralogy, mineral associations and liberation characteristics of both ore-bearing and gangue minerals were characterised using a Tescan integrated mineral analyser and X-ray powder diffraction studies. The Li content and distribution within minerals were defined in both ore and mineral standards using Laser-ablation ICP-MS and FESEM with ToF-SIMS capabilities. The Al:Si ratio, Mn, Na, Fe and F contents were used to classify and group the different Li mica minerals. Analysis of a micaceous pegmatite from Lepidolite Hill showed the ore is predominately lepidolite composite particles, with moderate to minor amounts of liberated trilithionite, albite, quartz, polylithionite and muscovite. Minor amounts of topaz, elbaite and beryl also occur. The lepidolite particles consists of fine textured intergrowths of Li muscovite- muscovite, lepidolite, polylithionite and trilithionite. A calculated theoretical grade-recovery for minerals lepidolite and combined trilithionite and polylithionite indicated that optimum lithium bearing mineral recovery occurs in the sieve fraction −355 to +180 μm with rejection of quartz and albite that make up ~ 20% of the sample. However, further grinding of concentrated lepidolite to particle size <90µm would be required to breakup, concentrate and expose fine grains of polylithionite, trilithionite and possibly reject some muscovite before further treatment to extract lithium. Assessment of a lithium ore to determine its amenability to processing for the extraction of lithium. Available from: https://www.researchgate.net/publication/319327770_Assessment_of_a_lithium_ore_to_determine_its_amenability_to_processing_for_the_extraction_of_lithium [accessed Oct 10 2017]

The mineralogy and processing potential of some ores from the Commonwealth propect in NSW, Australia

The Commonwealth Mine project area comprises the historical base metal-gold Commonwealth Mine, Commonwealth South gold deposit and more recently the Silica Hill deposit. They are located 100 km north of Orange in New South Wales, Australia. Impact Minerals Limited has discovered high grade mineralization of gold, silver, zinc, lead and copper which occurs in massive sulphides with extensive pyrite, veins of sulphide and quartz and disseminated sulphide in a variety of sedimentary and volcanic host rocks. The Inferred Resource has been defined comprising of 720,000 tonnes at 2.8 git gold, 48 git silver, 1.5% zinc, 0.6% lead and 0.1 % copper. The overall aim is to establish the metallurgical characteristics of these ores and development an appropriate flow sheet to allow future mining operations at this prospect. The mineralogy of a suite of representative samples of the various ore types were characterised using advanced analytical and mass spectrometry techniques available at the John de Laeter Centre at Curtin University to identify metal deportment, mineral associations and liberation characteristics of both ore-bearing and gangue minerals.• Diagnostic leaching tests were carried out to determine the reactivity of minerals and the availability of metals to extraction processes by both conventional cyanide leaching and Curtin University's patented glycine leach technologies. The benign nature of glycine and atmospheric leaching conditions make it a potential favourable leaching option in treating such ores,.particular in sensitive areas where cyanide usage is discouraged. This paper describes the findings of this study

The mineralogy and processing potential of the Commonwealth project in the Molong Volcanic Belt, central eastern New South Wales, Australia

The Commonwealth prospect area comprises the base metal-gold Commonwealth Mine, Commonwealth South gold deposit and the Silica Hill deposit located 100 km north of Orange in New South Wales, Australia. Impact Minerals Limited has discovered high grade mineralization of gold, silver, zinc, lead and copper which occurs in massive sulfides with extensive pyrite, veins of sulfide and quartz, and disseminated sulfide in a variety of sedimentary and volcanic host rocks. The Inferred Resource comprises 720,000 tonnes at 2.8 g/t gold, 48 g/t silver, 1.5% zinc, 0.6% lead and 0.1% copper. The overall aim was to establish the metallurgical characteristics of these ores and develop an appropriate flow sheet to allow future mining operations at this prospect. The mineralogy of a suite of samples representative of the various ore types were characterised using advanced analytical microscopy and mass spectrometry techniques to identify metal deportment, mineral associations and liberation characteristics of both ore-bearing and gangue minerals. Leaching tests were carried out to determine the reactivity of minerals and the availability of metals to extraction processes by both conventional cyanide leaching and Curtin University's patented glycine leach (GlyCat™) technologies. The benign nature of glycine and atmospheric leaching conditions make it a potential favourable leaching option in treating such ores, particularly in sensitive areas where cyanide usage is discouraged. The samples from three areas studied consisted of: (a) the massive sulfide deposit from Commonwealth Main with high gold (2.41–11.6 g/t), silver (545–1080 g/t), zinc (6.6–10 wt%) and lead (2.3–3.9 wt%) mineralisation associated with intergrowths of predominately pyrite with sphalerite, arsenopyrite and galena, barite and zincian siderite; (b) Commonwealth South porphyry rhyolite-rhyodacite with moderate gold (1.31, 10.9 g/t Au) and silver (29.4, 32.2 g/t Ag) grades consisting of a mixture of different mineral assemblages ranging from sulfide barren quartz and muscovite/sericite grains, to particles with enriched zones of sphalerite, pyrite and galena and a sulfide-rich sandstone-shale, which is predominately quartz with moderate amounts of pyrite, muscovite, baryte and quartz/mica mixture; (c) Silica Hill feldspar porphyry rhyolite-rhyodacite samples consist of low gold (0.58, 7.65 g/t Au) and medium silver (30.7, 172 g/t Ag) grades and made up of predominately siliceous intergrowths with disseminated pyrite and arsenopyrite as both coarse euhedral aggregates and fine discrete grains (10–200 µm). The massive sulfide samples were largely refractory to gold and silver extraction under all leach test conditions due to precious metals associated mainly with pyrite. With the exception of zincian siderite, the practical separation of finely disseminated sphalerite and galena for zinc and lead contents will be a challenge. Pressure oxidation or chloride based processes may be economical if further resources can be defined. Direct leaching for precious metal extraction by both cyanide and Glycat™ is possible for the porphyry rhyolite-rhyodacite and the sulfide-rich sandstone-shale samples where gold extraction ranged from 75% to 90%. Silver extraction ranged from 40 to 60% and is largely from leaching of fine grained electrum. Minor silver-bearing minerals, tetrahedrite, acanthite, pyrargyrite, and freibergite have limited solubility in cyanide extraction processes and will require more intensive conditions to leach. GlyCat™ show potential as a heap leach or tank leach process option where low cyanide additions can be managed and removed

A new kind of invisible gold in pyrite hosted in deformation-related dislocations

Mining of “invisible gold” associated with sulfides in gold ores represents a significant proportion of gold production worldwide. Gold hosted in sulfide minerals has been proposed to be structurally bound in the crystal lattice as a sulfide-gold alloy and/or to occur as discrete metallic nanoparticles. Using a combination of microstructural quantification and nanoscale geochemical analyses on a pyrite crystal from an orogenic gold deposit, we show that dislocations hosted in a deformation low-angle boundary can be enriched in Ni, Cu, As, Pb, Sb, Bi, and Au. The cumulative trace-element enrichment in the dislocations is 3.2 at% higher compared to the bulk crystal. We propose that trace elements were segregated during the migration of the dislocation following the dislocation-impurity pair model. The gold hosted in nanoscale dislocations represents a new style of invisible gold