Canmet Mining

Pristine fractured surfaces of chalcopyrite (CuFeS2) have been studied using Synchrotron Radiation X-ray Photoelectron Spectroscopy and conventional X-ray Photoelectron Spectroscopy. These high-resolution spectra reveal for the first time three distinct contributions to the S 2p spectrum. The main symmetric peak is located at 161.33 eV and is likely derived from fully coordinated bulk S atoms. A core-level shifted peak was observed at 160.84 eV and is attributed to surface monomeric species (S2-). A second broad contribution at 161.88 eV likely represents surface polymeric species (Sn2-). The data suggest that surface polymers form where S-terminated surfaces such as the (1̅1̅1̅) plane are exposed during fracture.

Synchrotron-radiation X-ray Photoelectron Spectroscopy (SRXPS) and conventional X-ray Photoelectron Spectroscopy (XPS) have been used to study a pristine fracture-surface of bornite (Cu5FeS4). Comparisons of these high-resolution spectra reveal, for the fi rst time, four distinct contributions to the S 2p spectra. The main symmetric peak of the S 2p spectra for bornite is located at about 163.51 eV and is derived from bulk S atoms. The broad nature of the bulk contribution, in comparison to other 3d transition-metal sulfi des such as chalcopyrite, is consistent with the presence of eight crystallographically distinct S sites within the structure, these sites being energetically as well as structurally distinct. A second peak located at 160.1 eV is attributed to a surface monomeric species (S2–) of lower coordination. The presence of a second broad surface-contribution at 162.1 eV likely represents surface polymeric species (Sn2–). The presence of surface sulfur polymers indicates the stabilization of the bornite surface upon fracture through formation of S–S bonds. These data suggest that surface polymers form where polar surfaces are exposed during conchoidal fracture. A high binding-energy tail was observed at about 163 eV and extends to about 166 eV, the origin of which is uncertain. Conventional XPS Cu 2p and Fe 2p spectra collected from a pristine fracture-surface of bornite reveal a Cu1+ peak centered at about 932.2 eV and a high-spin Fe3+ peak centered at 708 eV.

To provide the mining and tunnelling industries with a rock reinforcement fixture that is better suited to mining with high stress conditions, Atlas Copco has developed a new rockbolt that can accommodate both very large displacements and high energy release in the rock mass. The design principles that guided the development of the rockbolt are presented and discussed. For one, the Roofex® was designed to offer accurate pre-set load-deformation behaviour. This first model or prototype is based on a 12.5 mm diameter steel bar because of borehole diameter limitations.

Arseniosiderite and yukonite are among the important arsenate minerals occurring as secondary alteration products in relation to the oxidation of arsenopyrite and arsenian pyrite and as discrete grains in some gold ores, mine tailings, and contaminated soils. Characteristics of these Ca-Fe arsenate species are not well known and our understanding of the conditions promoting their formation and dissolution is limited. Long- and short-range structural characteristics and thermodynamic properties of the Ca-Fe arsenates forming in the Ca-Fe(III)-As(V)-NO3 system were determined to better predict the mineralogical transformations taking place in neutralized sludge and tailings environments, and their influence on arsenic mobilization. Yukonite and arseniosiderite readily form from solutions with highly variable compositions at a wide pH range from slightly acidic to alkaline conditions. Calcium concentrations corresponding to molar Ca/(Ca+Fe+As) ratios as low as 0.1 appear to be adequate for their formation. Our experimental results confirm observations in natural settings and mine tailings where scorodite is progressively replaced by yukonite and arseniosiderite. The initial amorphous precipitates made of small oligomeric units of edge-sharing FeO6 octahedra with bridging arsenate evolve to yukonite through the establishment of corner linkages between the FeO6 chains. Yukonite represents a nanocrystalline precursor and Ca-deficient variety of arseniosiderite. Formation of arseniosiderite is kinetically controlled with faster development of crystallinity at neutral to slightly acidic pH and slower kinetics under alkaline conditions. Calorimetric measurements provided an enthalpy of formation value of -1950.3 ± 3.1 kJ/mol and standard entropy of 237.4 ± 4.4 J/(mol·K) for arseniosiderite [with composition Ca0.663Fe1.093(AsO4)(OH)1.605·0.827H2O], the corresponding Gibbs free energy of formation is -1733 ± 3.4 kJ/mol. A rough estimate of the thermodynamic properties of yukonite is also provided. Arseniosiderite is a stable arsenate between pH 3.5 and 7.5 in solutions saturated with respect to soluble Ca minerals such as calcite, gypsum, anorthite, or Ca-montmorillonite. Arsenic release from mine wastes and contaminated soils can be effectively controlled by arseniosiderite and the conditions promoting its formation such as lime-treatment leading to gypsum saturation in ferric arsenate solutions would prove to be desirable for stabilizing arsenic in the form of arseniosiderite in mine wastes.

A combination of techniques, including powder X-ray diffraction (XRD), electron microprobe analysis (EPMA), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAFS), is used to characterize the common ferric-arsenate-sulfate compounds, which could result from the pressure oxidation of refractory gold ores at elevated temperatures.

Ferrihydrite is the main form of ferric iron in surficial environments and a key reactive nanoparticle that regulates nutrient availability and the mobility of metal(loid) contaminants, yet its structure is not completely elucidated. Two models exist to date: the "f-phase" in which Fe is fully octahedral and the "akdalaite-model" possessing 20% of the Fe atoms in tetrahedral coordination. In this study, germanium was used as a structural probe to re-examine the validity of the latter model. Germaniumbearing ferrihydrites containing 0.2, 0.6, 1.4, 2.2, 2.9, 3.8, 12, and 15 wt% Ge were synthesized in the laboratory at 25 and 65 °C. X-ray diffraction analyses showed all the precipitates to be six-line ferrihydrite. Semi-quantitative energy-dispersive X-ray microanalyses (TEM) indicate that the precipitates made from solutions having Fe/Ge molar ratios of two and four have Fe/Ge atomic ratios of 3.8-3.9 and 4.4-5.1, respectively, which suggest a limit of Ge uptake in ferrihydrite of about 20 at% relative to total cations. Based on TEM examinations, these high Ge-bearing ferrihydrites are homogenous and consist of equant and plate-like crystallites about 5-6 nm in size. Furthermore, it appears that higher Ge concentrations in solution have no significant effect on the crystallite size, supporting the incorporation of Ge in the ferrihydrite structure. Extended X-ray absorption fine structure (EXAFS) spectroscopy indicated that the Fe atoms in both the low and high Ge-bearing ferrihydrites are in octahedral coordination and that Ge occurs in the ferrihydrite structure by filling the empty tetrahedral sites and coordinating to 4 edge-sharing FeO6 trimers through sharing a common oxygen (Ge-O-Fe linkage). Incorporation of the Ge tetrahedra in the ferrihydrite structure requires redistribution of Fe occupancy along the alternating O/OH layers while forming an ordered distribution of octahedral Fe and tetrahedral Ge. The local structure around Ge mimics a Keggin-like motif in two different, yet equivalent, orientations. It appears that the split diffraction peak at 1.46 and 1.51 Å is a characteristic feature of Ge-rich ferrihydrite and suggests that it is a fingerprint of increased order due to significant Ge incorporation in the tetrahedral sites. The findings can be rationalized in terms of the incorporation of Ge in the so-called "f-phase" of the classical ferrihydrite model, and demonstrate the flexibility of the model in terms of accommodating a Keggin-like cluster without the need of imposing unrealistic constraints as in the akdalaite model. Direct comparison of the imaginary parts of the Fourier transforms for ferrihydrite and maghemite further confirms the absence of tetrahedral Fe in ferrihydrite. The absence of tetrahedral Fe substantiates the use of goethite-like or akaganeite-like models to describe the polyhedral structure of ferrihydrite used in modeling sorption reactions at the ferrihydrite-water interface.

In order to determine the impact of immobilization on biocatalytic efficacy of sulfide oxidase, the kinetic and thermodynamic properties of native and DEAE-cellulose immobilized sulfide oxidase from Arthrobacter species FR-3 were evaluated. Immobilization increased the catalytic efficiency of sulfide oxidase by producing a lower Michaelis-Menten constant (Km) and a higher rate of catalysis (Vmax) at different temperatures. The first-order kinetic analysis of thermal denaturation demonstrated that the values of enthalpy (delta H*d) and entropy (delta S*d) of immobilized sulfide oxidase were lower than the native enzyme, confirming the thermal stabilization of sulfide oxidase by immobilization. The delta H*d and delta S*d of the immobilized enzyme at 35 degrees C were 138.07 kJ/mol and 122.04 J/K/mol, respectively. These results suggest that immobilization made the sulfide oxidase from Arthrobacter sp. FR-3 thermodynamically more efficient for catalysis of sulfide oxidation.

Base metal smelters may be a source of particulates containing metals of environmental concern released to the atmosphere. Knowledge of the quantitative chemical speciation of particulate releases from base metal smelters will be of value in smelter emission fingerprinting, site-specific risk assessments, predictions of the behaviour of smelter stack particulates released to the environment and in resolving liability issues related to current and historic releases. Accordingly, we have developed an innovative approach comprising bulk chemical analysis, a leaching procedure, X-ray diffraction analysis and scanning electron microscopy/electron probe microanalysis characterisation in a step-wise apportioning procedure to derive the quantitative speciation of particulate samples from the stacks of three copper smelters designated as A, B and C. For the A smelter stack particulates, the major calculated percentages were 29 CuSO(4), 20 ZnSO(4).H(2)O, 13 (Cu(0.94)Zn(0.06))(2)(AsO(4))(OH), 11 PbSO(4) and four As(2)O(3). For the B smelter stack particulates, the primary calculated percentages were 20 ZnSO(4).H(2)O, 20 PbSO(4), 12 CuSO(4) and nine As(2)O(3). Finally, we calculated that the C smelter stack particulates mostly comprised 34 ZnSO(4).H(2)O, 19 (Cu(0.84)Zn(0.16))(AsO(3)OH), 11 PbSO(4), 10 As(2)O(3) and nine Zn(3)(AsO(4))(2). Between 56% and 67% by weight of the smelter stack particulates, including the As, was soluble in water. For these and other operations, the data and approach may be useful in estimating metals partitioning among water, soil and sediment, as well as predictions of the effects of the stack particulates released to the environment.

Humidity increases the bioaccessibility of Pb and Zn in dust that collects in damp microenvironments (such as window troughs).

The high solubility of copper sulphide minerals is an issue in the cyanidation of gold ores. The objective of this study was to quantify the effect of individual copper sulphide minerals on the Hunt process, which showed advantages over cyanidation. High purity djurleite, bornite and chalcopyrite, with a P70 of 70–74 microns, were mixed with fine quartz and gold powder (3–8 micron) to obtain a copper concentration of 0.3%. The ammonia-cyanide leaching of slurry with djurleite proved to be more effective than cyanidation; producing comparable extraction of gold (99%), while reducing the cyanide consumption from 5.8 to 1.2 kg/t NaCN. Lead nitrate improved the Hunt leaching. The lower cyanide consumption is associated to a significant reduction of copper dissolved. XPS surface analysis of djurleite showed that lead nitrate favored the formation of Cu(OH)2 species. Lead was also detected on the surface (oxide or hydroxide). Sulphide and copper compounds (cyanide and sulphide) were reaction products responsible for inhibiting the dissolution of gold. Lead nitrate added in the Hunt leaching of bornite produced 99% gold extraction. Surface reaction products were similar to djurleite. The cyanide consumption (~4.4 kg/t NaCN) was not reduced by the addition of ammonia. Cyanidation of chalcopyrite showed a lower consumption of cyanide 0.33 kg/t NaCN compared to 0.21 kg/t NaCN for Hunt. No significant interferences were observed in gold leaching with a slurry containing chalcopyrite.

Mineralogical characterization applied to mineral processing is now widespread. The first step for a mineralogi- cal characterization study is usually size fractionation. Preparation of polished sections is done on size fractions to reduce complications in making representative cross sections of particles with large size differences. A sample is commonly fractionated into five or six size intervals. The drawback of this procedure is that it makes liberation studies more expensive, because one sample actually produces five or six sub-samples that need to be studied, i.e. one from each size interval. Thus to reduce cost of liberation studies, it would be desirable to study the un-sized sample. This paper provides a comparative liberation study of a set of samples both using size fractions and using the un-sized samples. The samples studied are the feed, the concentrate and the tails of a lead rougher flotation circuit. The results consistently show significant differences between the sized and the un-sized samples. Nevertheless, the results indicate that un-corrected liberation data from un-sized samples can be used for comparative studies that involve several related samples. Thus, it is possible to improve (or further understand) a concentrator circuit by using mineralogical data from un-sized samples around such circuit.

<div class="htmlview paragraph">The performance of two catalyst preparations, styled base and base/noble, were determined employing a simulated mining vehicle loading cycle. Such cycles are characterized by sufficiently high exhaust temperatures to cause auto-regeneration of the filter units when these catalyst preparations are employed. Such loading is exhibited in raining service by some moderate and most high production load-haul-dump vehicles plus some haulage trucks. These preparations were shown to be capable of depressing the nominal, ‘untreated’ steady-state minimum soot ignition temperature of approximately 500°C (932°F), to a range varying from 395°C to 424°C (743°F to 797°F).</div> <div class="htmlview paragraph">Results of gaseous constituent analyses, particulate determinations, polynuclear aromatic hydrocarbon sampling, catalytic sulphur conversion (SO<sub>2</sub> to H<sub>2</sub>SO<sub>4</sub>) and Ames testing are presented for the two catalyst preparations studied.</div> <div class="htmlview paragraph">In addition, because of concern for the environmental impact of manganese in fuel additives, results of detailed manganese trapping efficiency tests for ceramic diesel particulate filters, are also presented.</div>

Abstract A wide range of non-intrusive measurement techniques are available, each with strengths and weaknesses. It is important to analyze various techniques with respect to their accuracy, cost benefits, user-friendliness, remote monitoring, and limitations so that the results obtained can be effectively used in integrity management programs. This paper presents the results obtained from testing five (5) non-intrusive techniques (ultrasonic-handheld, ultrasonic-fixed, electrical probe, hydrogen permeation, and fibre-optic) by placing them individually on 6-foot long test pipes. Each pipe possessed artificially implanted 24 internal corrosion pits of different sizes and shapes; was attached with a non-intrusive monitoring technique on its external surface; was filled with brine, crude oil, and gas mixtures of H2S, CO2, and methane of various ratios; and was subjected to various temperature and pressure cycles over a period of twelve (12) years. Based on this investigation the reliability of non-intrusive monitoring techniques has been established. This paper deals exclusively with non-intrusive techniques and does not compare the non-intrusive techniques with other sensitive intrusive techniques.

As part of a broader programme to fully characterize the chromite ores discovered in the 'Ring of Fire' region of northern Ontario, NRCan and private research facilities in Canada have performed extensive test work over the past six years. The studies focused on developing alternative approaches for producing ferrochrome at lower temperatures and with fewer greenhouse gas emissions. The use of various fluxes or catalysts for accelerated direct reduction had yielded promising results, particularly with caustic soda (NaOH). Here, the initial work had been protected by a patent known as the 'KWG process'. The most recent work by NRCan has confirmed that the addition of NaOH to chromite ores in carefully controlled amounts leads to high degrees of metallization at much lower temperatures than would be achieved by conventional smelting technologies, at greatly accelerated reactions rates.

An Atkinson resistance is adopted to characterise the leakiness of joints between duct segments. Hence, network air flow solvers are used to establish leakage amounts for operating conditions in auxiliary ventilation systems. Quantifying leakage is important when undertaking field observations for the Atkinson friction factor, k; leakiness of duct joints is a plausible reason for the range of values for k reported. In this work, leaky systems correspond to those with relatively low duct joint resistance of 104 Ns2/m8 for each joint; non-leaky systems correspond to those with duct joint resistances of 107 Ns2/m8 per joint. Distinct differences exist in the evolution of fan electrical motor power as ducts are lengthened, depending on whether the duct has leaky joints between its segments or not. Useful indicators of installation leakage and hence quality are presented that will lead to auxiliary ventilation system designs that operate more effectively, with lower cost.

Typically, coarse dense mineral particles greater than 150 μm are difficult to float, and the recovery decreases progressively. Various physical parameters can be manipulated in an attempt to increase the recovery. These physical parameters are the following: liberation, turbulence in the flotation cell, pH, collector, frother type and dosage. The testwork discussed in this paper was performed for a copper-molybdenum operation that is experiencing coarse particle (>150 μm) losses in the tails. This operation uses Diesel No. 2 fuel and sodium ethyl xanthate for molybdenum and copper flotation, respectively and X-133 frother. In an attempt to increase coarse particle recovery, stronger collectors (potassium amyl xanthate, Aero 249 and Aero 3501) and frothers (FrothPro 618, FrothPro 630 and FrothPro 706) were used. The analysis was performed using the Analysis of Variance (ANOVA) approach. The conditions required by the ANOVA method were met. The results showed that the collector potassium amyl xanthate (PAX) with frothers X-133 and FrothPro 630 resulted in approximately 3% increase in copper rougher recovery relative to the baseline (sodium ethyl xanthate and X-133). The collectors and frothers did not have a significant effect on molybdenum recovery within the dosage limits investigated.

Abstract The effect of sulphate-reducing bacteria (SRB) and carbon dioxide (CO2) on the general and localized corrosion of carbon steel in synthetic produced water (SPW) was investigated. The synthetic produced water was saturated with various concentrations of CO2. Experiments were carried out in a rotating cage apparatus using a mixed culture of sulphate-reducing bacteria obtained from an oil field in Venezuela. During the experiments the pH, planktonic bacterial count, and concentrations of sulphide, sulphate, iron, calcium and magnesium ions in the solution were measured. After the experiment, the sessile bacteria count and mass loss of the carbon steel test coupons were determined, the corrosion products on the metal surface were identified using X-ray diffraction, and the corrosion morphology was determined using optical microscopy, scanning electron microscopy and laser profilometry. Both general and localized pitting corrosion rates of carbon steel were found to nearly double in solutions containing 10% CO2 and 10% SRB compared to solutions containing either CO2 or SRB alone (synergistic effect). Higher CO2 concentrations killed both sessile and planktonic SRB; under these conditions the general and localized corrosion rates were determined by CO2 concentration (sweet corrosion).

The CANMET Mining and Mineral Sciences Laboratories (CANMET-MMSL) of Natural Resources Canada, Ottawa, has established a consortium initiative entitled “Green Mines Green Energy”. The consortium is composed of representatives from mining, forestry, government, academia and the private sector. The goal is to expand the practice of mine reclamation by furthering the use of organic residuals for the rehabilitation of mine sites - to the extent that they can be used to establish feedstock for the production of biofuels. There is increasing pressure on industry and municipalities to divert clean organic waste materials from landfill and to establish productive uses for them. In many areas of Canada, these materials (particularly municipal SSO compost) are in reasonably close proximity to mines, and may offer a relatively stable, long term, beneficial disposal strategy. Laboratory studies are underway to investigate the potential impact of these materials on tailings oxidation and effluent chemistry, as well as the effect of biosolids/compost-derived dissolved organic carbon on effluent treatability and toxicity. The construction of several half-hectare field plots began on mine sites in 2008. This paper provides an overview of the Green Mines Green Energy initiative and a summary of laboratory and field testing undertaken to date. Overall, preliminary results from the column study suggest that sulphate reduction at the tailings – biosolids interface is occurring, and that steady state has not yet been reached after more than 1 year of testing. Furthermore, the addition DOC has had no significant effect on effluent treatability or toxicity.

A low cost wireless acquisition system for multi-channel vibration measurement is presented. An acquisition system based on National instrument NI-9234 boards and LabVIEW™ has been developed and successfully tested in underground mines for human vibration assessment. The acquisition system was built using two National Instrument NI-9234 USB boards, giving a total of 8 channels, an external LI-ION battery, one minicomputer with solid-state hard disk for added robustness, and a small waterproof Pelican case. The IEPE mode of the NI-9234 boards was used to supply electrical power to the accelerometers, requiring the use of AC coupling. Since the NE-9234 board has, in AC coupling, a roll-off of 3 dB at 0.5 Hz, a digital FIR filter was added to correct the low frequency response in whole-body vibration (WBV) measurement mode, in order to satisfy the newer standard ISO 8041 (2005).