Search

• PGNAA and MR can be used simultaneously for bulk ore sorting of copper porphyries. • Integration is key for deposits with varying bornite and chalcopyrite ratio. • A greater increase in ore value is estimated when the sensors are used together. Bulk ore sorting is a preconcentration technique that may address the operational and environmental challenges of extracting low-grade ore deposits, such as copper porphyries. The technique allows for the early detection and diversion of sub-economic material by sensor-diverter systems before milling, thereby improving mill feed quality and reducing environmental impact. Grade heterogeneity in ore and sensor capability to measure grade accurately are prerequisites to applying bulk ore sorting. The technical synergy between the responses of multiple bulk ore sorting technologies can aid in taking full advantage of the grade heterogeneity existing in sorter feed while providing accurate and precise grade measurements. This study is aimed at quantitatively demonstrating the potential benefits of a conceptual strategy of integrating the responses from two sensor technologies for bulk ore sorting of copper porphyry deposits. Results show that a more significant enhancement in the Net Smelter Return (NSR) of the ore can be achieved by the simultaneous employment of the magnetic resonance (MR) and prompt gamma neutron activation analysis (PGNAA) sensors compared to the bulk ore sorting scenarios in which the sensor technologies are utilized separately. Results are encouraging and can prompt the collaboration of sensor manufacturers and mining companies to prove the actual value of the presented concept by performing on-site trials. [ABSTRACT FROM AUTHOR]

• Logistic regression and support vector machine modeling were developed for ore classification. • Principal component analysis combined with stepwise regression was used for processing XRF spectral data. • Logistic regression outperforms SVM with kernel functions especially on small sized data. The study is aimed at particle sorting at the Copper Mountain Mine using XRF. Possible applications include the rejection of barren material from mill feed, the rejection of pebbles in the SABC circuit or the recovery of valuable material from low grade stockpiles. It is recognized that XRF is a surface measurement that can detect copper but depending on several operational conditions, such as the orientation of the particle or mineral texture, the sensor spot may not see the copper. However, XRF also provides information about the concentrations of a range of elements in minerals that are associated with copper mineralization which can improve sorting. The study described herein is aimed at improving XRF sensor-based sorting by the introduction of logistics regression (LR)- and support vector machine (SVM)-based machine learning approaches. To solve the collinearity and dimensionality issues in the input variables, the authors propose a combined approach of principal component analysis (PCA) and stepwise regression to extract the significant features. The combined PCA and stepwise regression approach is novel and has shown to be very effective for dimensionality reduction of the XRF spectrum data. By applying the ROC and AUC), the LR and SVM models are compared. Results showed that the LR model with the AUC of 0.847 outperforms the SVM with kernel functions with respect to classification accuracy; especially for data sets with a small number of features. The improved classification accuracy should benefit the economic performance of the particle sorting system. [ABSTRACT FROM AUTHOR]

A method for determining the minimum practical energy for comminution was developed and is presented in this paper. An objective of the method was to determine experimentally the energy-breakage relationship for a wide size range in order to evaluate the energy performance of both crushing and grinding processes using one energy benchmarking value. Single-particle compression breakage, referred to in the field of comminution as one of the more efficient forms of mechanical comminution, was the basis for a test regimen to characterize the energy-breakage properties of ores. Existing models for impact breakage were found to be valid for single-particle compression breakage when used in a modified form. A key parameter of the adopted model, the threshold energy, was also investigated for three ore types and a range of particle sizes. The energy performance of comminution processes at a Canadian mining operation was determined by comparing the determined minimum practical energy, using the new method, with actual site specific energy requirements. In order to evaluate the energy performance of different crushing and grinding technologies, the proposed energy benchmarking method was used to compare the energy performance of alternative comminution flowsheets. [ABSTRACT FROM AUTHOR]

• Nine influential factors were integrated in a mathematical framework based on fractal modelling approach. • The influence of various factors on the ore sortability were investigated. • Factors of significant influence were identified. The uptake of bulk ore sorting technology is hindered by little knowledge in assessing its applicability for certain mine operation. The applicability of the bulk ore sorting technology, referred to as 'sortability', is a multi-folded concept and is influenced by many factors. Researchers have investigated the influence of some of the various factors, but few have done this in a holistic perspective and in a quantitative manner. In this research, nine influential factors of ore sortaibility were integrated in a mathematical framework based on fractal modelling approach. Box-Behnken design was applied and 130 block cave mine operations were hypothesized under different values of the factors. The influence of the factors on the ore sortability were investigated and factors of significant influence were identified. Results showed that ore property, sorting efficiency, metal price, processing cost and operation scale were the most significant factors in affecting the sortability for a mine operation. The research is intended to improve the understanding on the bulk ore sortability for mine productions under different conditions, and to provide a holistic perspective for applying the bulk ore sorting technology. [ABSTRACT FROM AUTHOR]

Highlights: [•] Stirred milling kinetics was studied on the siliceous goethitic nickel laterite. [•] The breakage behaviour was evaluated with respect to sample mass, element, and minerals. [•] The effect of selective grinding was evaluated by three methods. [•] The effect of grinding time, feed size, and product size on selective grinding was evaluated. [Copyright &y& Elsevier]

• The developed fractal model was validated on mine production data. • The multifractal model was proposed for bulk ore sortability assessment. • The multifractal model was more accurate in predicting the sorting results and assessing ore sortability. A previous study demonstrated the theoretical development of a model for assessing bulk ore sortability. However, the model has not been validated with many cases. In this study, the developed model was validated using the production data from 232 draw points in a block cave copper mine. For each draw point, sorting results and mine economics were predicted using fractal modelling and compared with results based on actual data analysis. The statistical error was measured for the fractal model predictions of feed grade, mass yield, pre-concentrate grade, metal recovery, and NSR with and without bulk ore sorting. An optimised approach was developed using multifractal modelling; two sets of fractal parameters were determined to characterise the metal distribution in high- and low-grade ranges. The results showed that the multifractal model was more accurate than the fractal model in predicting the sorting results and assessing ore sortability. [ABSTRACT FROM AUTHOR]

• The potential of bulk ore sorting application at a block cave mine was investigated. • The grade heterogeneity and sortability was evaluated for different mining zones. • The relationship between ore grade heterogeneity and sortability was discussed. A block cave mine operation was investigated in terms of ore grade heterogeneity and the potential of bulk ore sorting application. The grade heterogeneity within the caved material was measured for different draw points and mining zones, in terms of Distribution Heterogeneity and Fractal Dimension. The potential of bulk ore sorting was assessed by comparing the Net Smelter Return before and after a hypothetical bulk ore sorting system was implemented. Results showed that the potential of applying bulk ore sorting was influenced greatly by the heterogeneity within the mined material. A certain level of heterogeneity was necessary in considering the mine production as 'sortable'. The sortability would also vary for different mining areas depending on heterogeneity level of the production. Peripheral zones of the orebody were considered with the highest level of heterogeneity and the most significant potential of bulk ore sorting application. [ABSTRACT FROM AUTHOR]

• Error analysis was conducted on the XRF measurements of ore materials at lab-scale. • Three main types of errors were identified associated with XRF measurements. • The applicability of XRF in bulk ore sorting applications was discussed. X-Ray Fluorescence is one of the sensing technologies with potential in bulk ore sorting application. However, its reliability is often questioned since X-Ray Fluorescence does not sufficiently penetrate and errors are associated with surface measurements representing the volumetric grade. In this paper, error analysis was conducted on the XRF measurements on bulk ore materials at lab scale. Three main sources of the errors were identified, termed as instrumental error, heterogeneity error and the sampling error. Among the errors, the heterogeneity error was identified as the most significant due to its irrelevance with measuring the concentration and the unpredictability of that value. The influence of the errors on the conventional linear regression approach was investigated in terms of the sorting results and economics. Results showed that the linear regression approach was expected suitable for cases when sufficient analysis interval time could be ensured. It this was allowed for, the applicability of XRF in the bulk ore sorting was fundamentally justified. [ABSTRACT FROM AUTHOR]

• Receiver Operating Characteristic (ROC) was applied in ore classification for bulk ore sorting. • ROC approach was found to result in more accurate classification compared to SLR. • Economics performance was enhanced by ROC approach compared to that of SLR. As high grade deposits become depleted, the mining industry is challenged by mining lower grades that require the use of non-selective bulk mining methods. Bulk ore sorting can reduce the dilution of the mined ore thereby preventing costly processing of low grade waste while improving the quality of material reporting to the processing plant. X-Ray Fluorescence (XRF) is one of the sensing technologies used for bulk ore sorting. The grade of the bulk material is predicted based on XRF measurement that is correlated to a grade using a calibrated algorithm. The effectiveness of XRF bulk sorting depends on the accuracy of the grade classification of the scanned material. False classification is attributed to poor performance of the sorting algorithm to correlate the measurements with the assay grades. The paper presents an approach to analyze XRF measurements that reduce misclassification of material. Receiver Operating Characteristic (ROC) was applied as the tool in classification of bulk materials. The performance of this approach was compared to conventional sorting algorithm, namely, simple linear regression (SLR), where XRF responses was linearly correlated to the assay grades. The ROC approach was found to result in more accurate classification and enhanced economics performance of the bulk ore sorting system. [ABSTRACT FROM AUTHOR]

• A bulk ore sorting model was developed for sortability assessment. • Metal distribution within ore deposits was recognized as a fractal structure. • The optimum cut-off grade was determined based on model calculations. Bulk ore sorting (BOS) has the potential to reduce processing costs and improve mine economics. A factor that impedes its acceptance is the lack of a method to assess ore amenability to sorting. In this study, a fractal model of metal distribution was used to assess an ore's bulk sortability. A BOS model was developed where metal distribution properties were characterised, optimum cut-off grade for sorter operation was determined, and economic potential of BOS was evaluated. For the developed model, the metal distribution within the ore deposits was recognised as a fractal structure. Two parameters were introduced, namely the grade factor and fractal dimension, to quantitatively characterise ore properties in terms of grade magnitude and heterogeneity. The mass balance of the sorter operation was modelled as a function of the characterised ore properties and the optimum cut-off grade was determined based on model calculations. The economic potential of BOS was evaluated in terms of the net smelter return and compared with that when no BOS was implemented. Based on the developed model, the bulk ore sortability of different ore properties was assessed with a hypothetical underground copper mine. The developed BOS model provided a powerful tool for ore sortability assessment and is expected to encourage academic research and industrial practices of BOS. [ABSTRACT FROM AUTHOR]

[Display omitted] • 27 laboratory HIG5 grinding tests are performed for modelling the influence of operational variables. • Stress analysis is applied for understanding laboratory variables' correlation with their production level. • Correlation factors are determined based on empirical fitting with production data. • Laboratory models are calibrated for predicting and improving large-scale mill performance. As a fine and ultrafine grinding technology, the High Intensity Grinding (HIG) Mill is relatively new and there is opportunity to improve its performance by adjusting operational conditions. A laboratory HIG5 mill is commonly used for HIG mill sizing and scale up, however the clear correlation between the operational variables of laboratory mill to their production level is somewhat lacking. This paper presents a stress-based approach for predicting and improving large-scale HIG mill performance. A total of 27 experimental tests were performed with a HIG5 mill over a range of operational variable set points, including media density, media filling level, feed solid content, mill speed and flow rate. The influence of the variables on product size, mill operating power and specific grinding energy was characterized via multivariable linear regression modelling. Based on theoretical stress analysis and empirical calibration with available survey data, the model derived from laboratory testing was calibrated to predict the operation of the commercial HIG1600 mill. An approach was proposed for determining the effect of operational variables using a HIG5 that can be directly applied to reduce energy consumption at a given mill feed rate and product size target for the production scale mill. Results demonstrated that the stress-based approach integrated with laboratory testing can be used for predicting and improving large-scale HIG mill performance. [ABSTRACT FROM AUTHOR]

• Even with the ideal conditions, bulk ore sorting may not be applicable. • Metal losses limit the value associated with bulk ore sorting. • Good correlation between copper and gold is required for effective ore sorting. Bulk ore sorting may add significant value to block and panel cave mines where processing feed grades are constrained by limited grade selectivity. The Cadia East gold-copper mine is a panel caving operation utilizing two different on-belt bulk ore sensors to evaluate the potential benefits of the technology. To date, there is limited reported work addressing the applicability of bulk ore sorting systems at a caving mine, where two commodities drive the economics. This indicative study is aimed at investigating the importance of various key factors on the bulk ore sorting potentials of the active and future panel caves of the Cadia East mine. Results show that for only one active cave of the mine, bulk ore sorting may be applied in the ideal scenario where grades are not affected negatively by mixing and the sorting takes place at maximum efficiency. As a general trend for all the caves, when the sorting cut-off grade is increased beyond a certain threshold, a sharp decline is observed in the sorting potentials due to the significant amounts of gold and copper deporting to the sorter rejects. In the case of a significant drop in metal prices, bulk ore sorting may only provide an opportunity to improve cave economics marginally. Results obtained by investigating the spatial change in sorting potential show that the portions of the caves with low metal grades are favourable for bulk ore sorting. In the scenario where bulk ore sorting is focused on low-grade portions, it is demonstrated that improvements in the economics of the future caves may additionally be achieved. However, as the low-grade portions represent a very small volume in the orebody, applying ore sorting on the plant conveyor may not be viable. [ABSTRACT FROM AUTHOR]

• Conjugate Anvil Hammer Mill (CAHM) was studied using experimental piston-die testing. • The semi-confined and confined compression were compared. • Higher energy efficiency of CAHM compression breakage was found compared to HPGR. The Conjugate Anvil Hammer Mill (CAHM) was identified as a novel energy efficient technology by the Canadian Mining Innovation Council that has the potential to replace conventional crushers and Semi-Autogenous Grinding (SAG) mills. Discrete Element Method (DEM) modelling showed that the CAHM requires significantly less energy in comparison to existing comminution technologies including High Pressure Grinding Rolls (HPGR). However, experimental evidence was required to validate this potential and to address operational questions. In order to evaluate the CAHM, piston-die testing was conducted to represent the comminution conditions in the CAHM for comparison to the HPGR. Three piston-die conditions were tested including low pressure semi-confined compression as generated in the CAHM, low pressure confined compression, and high pressure confined compressions as generated in the HPGR. The particle breakage was investigated and compared in terms of applied force, energy consumption, product particle size reduction and particles' surface area generation. Results showed that the CAHM test apparatus required a much lower force and produced a finer product particle size distribution and higher surface area when compared to low pressure confined compression. When compared to high pressure confined compression (HPGR), up to 37% and 22% energy savings were achieved by the CAHM for a soft gold ore and a harder copper ore, respectively. The results demonstrated that the CAHM technology has potential to improve energy efficiency in the comminution process. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • With anionic or nononic polymer as primary flocculant, two-step flocculation was used for iron fine tailings treatment. • Better flocculation effect was achieved with the single nononic flocculant, but a higher water recovery rate was obtained with anionic primary flocculant. • Broken flocs produced by anionic flocculant had larger strength factors and a more significant reversibility with the appropriate amount of the cationic flocculant and they also achieved a higher total water recovery rate. • Flocs size distributions were measured and strength factor and recovery factor were calculated for mechanism study. • The flocculation mechanism involves polymer bridging and charge neutralisation. Abstract Dewatering of fine tailings is one of the major challenges faced by the mining and mineral processing industries worldwide. In order to facilitate the separation of released water and solid sediments, different kinds of polymeric flocculants and their combinations have been widely used. A two-step flocculation experiment using two separate primary flocculants in alkaline environment was carried out in this study. The underflow concentration of the two-step flocculation process was higher than that of any single flocculant. Compared to the widely-used flocculation process with a single polymer flocculant, this two-step process could not only significantly improve the total water recovery rate of the slurry, it could also produce a full re-growth of flocs. The first part of the study compared the effects of adding 2 different flocculants to the slurry under alkaline conditions: a non-ionic flocculant, and an anionic flocculant. Compared to the anionic flocculant, the addition of the non-ionic flocculant resulted in a more compact structure and a higher strength by bridging. Conversely, after shear disruption and the addition of the cationic flocculant to the slurry, the re-aggregating broken flocs produced by the anionic flocculant in the first step resulted in a higher reversibility, the formation of a closer and more complex floc structure, and consequently a higher total water recovery rate. This was achieved by drastically re-aggregating broken flocs through the addition of a cationic flocculant that neutralized the charge of the slurry, which in turn is an indication of significant reversibility of the floc break-up process. The dosage of the secondary flocculant had an optimal value to achieve the maximum total water recovery rate. If the dosage exceeded the optimal value, the interaction between the flocculant molecules adsorbed on the same floc occured, which hindered the re-aggregation of flocs and even reduced the secondary water recovery of the slurry. [ABSTRACT FROM AUTHOR]

Block and panel caving mines are increasingly being proposed for the excavation of massive ore-bodies located at depth. The lack of selectivity associated with the mining methods results in both ore and waste being caved and transported through material handling systems to the surface for processing and waste rock disposal. Sensor-based sorting systems provide an opportunity to automate the discrimination between ore grades and rock types, providing an enhanced level of selectivity for ore control and thereby improving mine productivity. To evaluate the potential to add value to a caving operation, a sensor-based ore sorting study, incorporating bulk and particle sorting systems, was carried out for the New Afton block cave mine. Results showed that rock from the copper-gold porphyry deposit is amenable to prompt gamma neutron activation analysis, and to X-ray fluorescence sensors. A conceptual flowsheet, where both technologies are used as separate unit operations, was evaluated. Test samples of varying copper head grades allowed an ore value calculation method to be developed based on the integration of continuous bulk sorting and particle sorting. The calculation method can be applied to block models of a future cave at New Afton and used to evaluate the change in the economic footprint. It was found that the concept demonstrated an improvement in the net smelter return of excavated material. [ABSTRACT FROM AUTHOR]

• Modified Hardgrove test to predict the Bond Ball Mill Work Index (BBMWI). • Predicts the BBMWI using 30 cm3 (∼40 to 60 g) of −3.35 + 0.600 mm samples. • Simpler execution, quick turn-around time, requiring less operator training. • The proposed test predicts the BBMWI with less than 4% prediction error. • A low cost option to geometallurgical studies and other which few mass is available. Grinding ores in conventional ball mills demands high energy consumption, resulting in relatively high operating costs in a typical mineral processing industrial plant. Whether in the initial stages of a mining project or during its operation, conducting tests to determine the processing circuit's energy consumption throughout the life of mine is necessary in order to reduce such high operating costs. Traditional tests used to determine the energy consumption in grinding, like the Bond Ball Mill test, are relatively time-consuming and require significant amounts of sample, e.g., 8–10 kg, which is not always available in the initial stages of a mineral project or geometallurgical studies. Several authors have developed simplified tests to predict ball mill's energy consumption, typically using the Bond Ball Mill Work Index (BBMWI) as a reference. One option requiring less mass is the Hardgrove mill, traditionally used in the laboratory to determine the energy required to grind coal in roller mills. This test requires 50 g of sample, and the result is based on the amount of fines at the end of grinding to a fixed time. The present study used a modified Hardgrove test to predict the BBMWI. This test involves the measurement of the torque, uses a fixed sample volume with different particle feed sizes from the Hardgrove standard, and determines the specific energy related to the percentage of product passing through the closing size screen of the Bond test, defined as the size specific energy. The results indicated that for a set of 13 samples with the 150 µm closing screen, the average error associated with the predicted BBMWI is within ±2.3%. Further results indicate an error of ±3.1% for 20 samples with the 106 µm closing screen. The correlations presented here are proposed to be validated and/or adjusted for different ores and mines. The proposed test is thus suitable for geometallurgical studies and other applications where relatively small samples are available. In addition, this is a low-cost test, has a quick turn-around time, it is simple to conduct and does not require the handling of heavy loads by operators. [ABSTRACT FROM AUTHOR]

Thickened tailings deposition technology can form a stack with a certain slope by depositing high-concentration tailings slurries to reduce the footprint of tailings storage facilities and water consumption. Thickened tailings slurries exhibit complex non-Newtonian behaviors. Predicting the beach profile evolution of thickened tailings is important for the tailings storage facility design and management. A novel governing differential equation (GDE) derived from the lubrication theory is proposed in this work to capture laws of beach profile formation. Experimental data from three-dimensional laboratory-scale flume tests are analyzed using the proposed GDE. The GDE avoids the discrepancy from an inappropriate coordinate system, which exists in some state-of-the-art models and exhibits higher accuracy when predicting the beach shape near the toe of a preexisted layer. Compared with the Herschel–Bulkley (H–B) model, the Zhang's equilibrium rheological model is preferred to determine the static yield stress, which leads to the accurate estimation of the stack profile in single- and multilayer thickened tailings depositions. The in-situ beach profile of thickened tailings is predicted using a numerical technique. A case study is included to demonstrate that the prediction based on the proposed GDE is consistent with the field measurement. The beach profile prediction of thickened tailings considering thixotropy is also discussed in this study. Results indicated that the decrease of yield stress along the flow path due to thixotropy leads to the concave beach shape of thickened tailings. • The governing differentiating equation to predict beach profile is proposed. • A modified method to predicting the field beach profile is established. • Thixotropy causes the concave beach shape for thickened tailings deposition. [ABSTRACT FROM AUTHOR]

• A small-scale locked-cycle piston press test to provide design information closed-circuit HPGR. • The test ware inspired by the Bond ball mill grindability test. • Piston Work Index describes the samples' resistance to HPGR comminution. • The test results were within ± 20% range of HPGR tests for a fine feed. The increased energy efficiency of HPGR-based circuits as an alternative to AG/SAG mill circuits has been well established. However, assessing the HPGR technology involves pilot-scale testing requiring large samples, which is expensive and may be prohibitive, particularly for early-stage projects. As a result, the uptake of HPGR technology has been slow, emphasizing the need for small-scale tests for sizing and selection. A reliable small-scale test for preliminary HPGR circuit design is essential in garnering the mining industry's interest in the broader adoption of HPGRs. Inspired by the Bond ball mill grindability test, a small-scale locked-cycle piston press test was developed to estimate the circulating load and circuit-specific energy consumption for closed-circuit HPGR operation. The test introduces the Piston Work Index, which describes the ore samples' resistance to HPGR comminution and can be subsequently used to estimate the HPGR circuit-specific energy consumption. The test results indicated that the circuit-specific energy and circulating load obtained from the small-scale piston press test were within the ± 20% range of the locked-cycle pilot scale HPGR tests for a fine feed representing quaternary stage HPGR application. [ABSTRACT FROM AUTHOR]

XRF bulk sorting is put forward as a credible intender for pre-concentration methods in mining. This paper presents a preliminary study employing a bench-scale approach to calibrate XRF surface sensing to a target concentration of interest related to its volume so as to assess the feasibility of a case barren copper ore “slots” to bulk sorting. Firstly, various top sizes, along with different operators and specimens’ weight/volumes, were examined to quantify the minimum readings needed (MRN) for XRF spot scanning at this scale. Multiple linear regression with a correlation coefficient of 0.921 was validated to be a reliable algorithm for calibrating XRF surface response to Cu volumetric concentration, owing to its consideration of elemental interacts. With the aid of graphical representations of calibrated data on recovery/grade curves, cut-off grade of 0.23% was chosen to enable 30% mass below the threshold to be discarded as waste and the remainder to go for further processing. [ABSTRACT FROM AUTHOR]

• Nickel recovery increases at higher magnetic field strengths. • Magnetic separation recovers over 90% of the magnetic nickel. • Nickel losses are associated with fine and very fine awaruite. In this work, a research study, focused on the recovery of awaruite, was conducted on a representative sample from the Baptiste deposit to evaluate magnetic separation over a range of magnetic field strengths. The Baptiste deposit is a unique nickel deposit containing awaruite, a high-density ferromagnetic nickel–iron alloy. The evaluation included semi-batch and continuous pilot scale tests, employing wet magnetic drums at two different grind sizes. The samples were characterized using techniques including chemical composition analysis, Davis tube testing, and automated mineral analysis. The results showed promising magnetic nickel recoveries, in the range of 92% to 96%. The development of the Baptiste deposit will benefit from a sound scientific understanding of the process solution. [ABSTRACT FROM AUTHOR]

• Awaruite has unique characteristics compared to other nickel minerals. • Awaruite has higher magnetic susceptibility than magnetite. • Magnetic and gravity separation are feasible methods of awaruite concentration. Nickel is an important component of stainless steel and a wide range of applications which are critical for the transition to clean energies including electric vehicle batteries. Awaruite is a native nickel–iron alloy that has gained interest as a possible new economic source of nickel. In the last decades, there have been discoveries of awaruite, mostly with more significant amounts of nickel sulphides, that have demonstrated the potential for awaruite to contribute to the economics of a deposit. This study is focused on the very large Baptiste deposit in central British Columbia, Canada where awaruite is the primary nickel mineral. Most of published data on awaruite are focused on geology, and important fundamental physiochemical properties have still not been determined. These properties are fundamental for the set-up of a flowsheet that will enable its large-scale processing. The limited information available of this nickel–iron alloy can be complemented with the available information of a synthetic alloy with the same elemental composition. The synthetic awaruite alloy has demonstrated remarkable magnetic properties, and based on those properties, it was named permalloy. In this study, physicochemical properties of native and synthetic awaruite were measured including chemical composition, crystallographic structure, and magnetic properties. The native awaruite composition from the Baptiste deposit averages 77.3 % nickel, 21.0 % iron, 1.1 % cobalt and 0.6 % copper. Natural and synthetic awaruite have the same crystallographic characteristics and similar ferromagnetic behaviour. The measured initial volumetric magnetic susceptibility for native awaruite was 14.4 and the saturation magnetization was 750 kA/m. Awaruite has the potential to be concentrated in a unique and valuable nickel concentrate of distinctive characteristics including its very high nickel content, which lowers both the downstream costs and the carbon intensity. Furthermore, the negligible content of sulphur and penalty trace elements, such as mercury, antimony, and arsenic in a potential awaruite concentrate, minimizes the costs of refining it. The physicochemical data in this study provides information to reliably set up a mineral processing flowsheet, which is discussed in this work. [ABSTRACT FROM AUTHOR]

[Display omitted] • Awaruite passivates in neutral and alkaline media. • Awaruite readily floats in acidic media with xanthate. • Xanthate chemisorbs and oxidizes at the awaruite surface in acidic media. Awaruite is a native nickel–iron alloy (Ni 3 Fe), found in serpentinized ultramafic rocks, that has gained interest as a possible source of nickel. FPX Nickel is advancing a very large awaruite deposit in central British Columbia, Canada, on which this work is based. To date there is limited information available regarding the flotation conditions to selectively concentrate awaruite from gangue minerals in serpentinite ores. The aim of this work was to investigate the floatability of awaruite in different solution conditions with a xanthate collector. Awaruite readily floated in acidic solution with a xanthate collector but not in neutral and alkaline solutions. Voltammograms on awaruite indicated that the alloy shows an active passive transition behaviour in acidic solution and passive behaviour in neutral and alkaline solutions. The passivation layer formed in neutral and alkaline solutions showed to inhibit the interaction between xanthate and awaruite surface. Infrared spectra on awaruite showed the presence of xanthate compounds attached to the surface in acidic condition at potentials higher than the reversible potential of xanthate/dixanthogen. Based on experimental results, it was postulated that xanthate chemisorbs on awaruite and then it oxidizes to form dixanthogen. Also, it was demonstrated that when passivated, awaruite quickly activates in acidic solution, good flotation performance was achieved with 10 min of conditioning, and similar performance was obtained after 30 min of conditioning. This work serves as a confirmation that is possible to float awaruite using xanthate, a well-known collector that offers selectivity over oxides and silicate minerals, which are the main gangue minerals in serpentinite ores. [ABSTRACT FROM AUTHOR]

• A novel zone settling velocity function was proposed. • Vesilind function underestimates the settling velocity at high solids concentrations. • The inverse problem by SBSC herein produces an excellent prediction of ZSV at high solids concentrations. • The concentration profile at infinite time was calculated. Relationship between solids zone settling velocity (ZSV) and concentration is of importance in solid-flux theory used in the design and operation of thickeners. A reliable characterization of relationship between ZSV and concentration relying on a single batch settling curve (SBSC) remains necessary and challenging. In this study, a novel ZSV function considering both maximum settling velocity and maximum packing fraction is proposed. The comparison between the novel function and some state-of-the-art ZSV functions indicates that the former shows preferable performances in predicting the batch settling phenomena. The inverse problem to determine ZSV function from SBSC is carried out and the obtained ZSV function performs well in simulating sedimentation without compression. Finally, sedimentation with compression is discussed based on the novel ZSV function. [ABSTRACT FROM AUTHOR]

Abstract: The paper reports the progress of a research project using rock samples from a large copper–gold mining project. The orebody contains a mixture of hard rock, softer material, and clays (sericite), in proportions that are expected to vary throughout the mine-life. The feasibility of a novel comminution circuit, using an autogenous (AG) mill/scrubber and parallel trains of cone crushers and high-pressure grinding rolls (HPGR) is being investigated. The process enables the application of energy-efficient HPGR to base and precious metal hard-ores containing clay, which are usually processed using SAG mill circuits. The work presented in this paper involved laboratory testwork including pilot HPGR testing, and modelling and simulation of both the HPGR-based circuit and an equivalent SAG-based circuit. The preliminary analysis reported herein includes a comparison of the energy consumption of both circuits; complete operating and capital cost comparisons will be reported in a future paper. [Copyright &y& Elsevier]

• Continuous physical, mineralogical, geochemical data recorded in waste-rock pile. • Multi-scale heterogeneities in alteration resembling hardpan formation in tailings. • Secondary mineral assemblages and weathering mechanisms in reactive and inert zones. • Mineralogical controls on leachate composition and metal mobility in waste-rock pile. Mine waste rock is typically stored on-site in large piles that are heterogeneous in terms of material composition and grain size. This leads to variable reactivity within the pile and makes prediction of drainage quality difficult. Here, we present data from two >100 m continuous boreholes through an operational waste-rock pile at the Antamina mine (Peru). Reactive zones with elevated sulfide and metal content exhibited increased temperatures, reduced oxygen content, as well as pervasive secondary mineral precipitation. Sharp contact between altered and unaltered layers at the meter to centimeter scale indicated strong variability in mineral reactivity. Unaltered waste rock persisted within high-sulfide zones due to low oxygen levels, and surface passivation and galvanic interactions between sulfide couples also limited alteration. Waste-rock layers with gradated alteration that resemble hardpans, as observed in tailings, were in direct contact with non-altered, less-permeable layers. Finally, leaching tests show that sulfate, Cu and Zn were efficiently leached from reactive and mineralogically altered zones, whereas As and Fe were retained through sorption, surface passivation, or secondary mineral formation. This study shows that, over and above bulk geochemical and lithological data, waste-rock reactivity may also be defined by mineralogical data and thereby contribute to improved drainage quality predictions. [ABSTRACT FROM AUTHOR]