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Freezing on demand: A new concept for mine safety and energy savings in wet underground mines

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International Journal of mining Science and Technology 2019年第4期29卷 621-627页

作者： Mahmoud A.Alzoubi Ahmad Zueter Aurelien Nie-Rouquette Agus P.Sasmito Department of Mining and Materials Engineering McGill University

The artificial ground freezing(AGF)systems are designed to operate continuously for an extended period of time to control the groundwater seepage and to strengthen the groundwater structure surrounding excavation areas.This mode of operation requires a massive amount of energy to sustain the thickness of the frozen body.Therefore,it is of great interest to propose new concepts to reduce energy consumption while providing sufficient structural stability and safe operation.This paper discusses the principle of the freezing on demand(FoD)by means of experiment and mathematical model.A lab-scale rig that mimics the AGF process is conceived and developed.The setup is equipped with more than 80 thermocouples,flow-meters,and advanced instrumentation system to analyze the performance of the AGF process under the FoD concept.A mathematical model has been derived,validated,and utilized to simulate the transient FoD concept.The results suggest that the overall energy saving notably depends on the coolant’s temperature;the energy saving increases while decreasing the coolant inlet temperature.Moreover,applying the FoD concept in an AGF system leads to a significant drop in energy consumption.

关键词： Artificial ground freezing Freezing on demand Energy saving Conjugate heat transfer Porous media

New approaches to cognitive work analysis through latent variable modeling in mining operations

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International Journal of mining Science and Technology 2019年第4期29卷 549-556页

作者： S.Li Y.A.Sari M.Kumral Department of Mining and Materials Engineering McGill University

This paper discusses the utilization of latent variable modeling related to occupational health and safety in the mining industry.Latent variable modeling,which is a statistical model that relates observable and latent variables,could be used to facilitate researchers’understandings of the underlying constructs or hypothetical factors and their magnitude of effect that constitute a complex system.This enhanced understanding,in turn,can help emphasize the important factors to improve mine safety.The most commonly used techniques include the exploratory factor analysis(EFA),the confirmatory factor analysis(CFA)and the structural equation model with latent variables(SEM).A critical comparison of the three techniques regarding mine safety is provided.Possible applications of latent variable modeling in mining engineering are explored.In this scope,relevant research papers were reviewed.They suggest that the application of such methods could prove useful in mine accident and safety research.Application of latent variables analysis in cognitive work analysis was proposed to improve the understanding of human-work relationships in mining operations.

关键词： Latent variables Exploratory factor analysis Confirmatory factor analysis Structural equation modeling Occupational health and safety Mine safety

Probabilistic approach for open pit bench slope stability analysis——A mine case study

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International Journal of mining Science and Technology 2019年第4期29卷 629-640页

作者： Christian Obregon Hani Mitri Department of Mining and Materials Engineering McGill University

The geotechnical slope design of an open pit wall starts at the bench scale configuration.At this scale,the rock slope stability is governed primarily by the geological discontinuities within the rock mass and as a result,structurally-controlled failures(e.***.planar,wedge or toppling)are most likely to occur.The probabilistic approach offers a major advantage over the traditional deterministic method in that it accounts for the different degrees of variability and uncertainty often encountered in rock properties.This paper presents a bench slope stability assessment for an open pit mine in Peru using a probabilistic-based approach by coupling a kinematic analysis based on stereographic projection techniques followed by a kinetic analysis by means of the limit equilibrium method.Finally,these two probabilities are combined to provide an overall measure of the probability of failure(PoF)of the bench slope system.The case study is characterized by significant scatter in the geometrical and mechanical properties of the joints.Extensive surface mapping was conducted at 36 different sites following the ISRM suggested procedures.Several direct shear tests were carried out.It is shown that by combining field and laboratory measurements and engineering judgment,the probability density functions(PDF)of the discontinuity parameters can be obtained.These are then used in a Monte Carlo simulation process to compute both kinematic and kinetic probabilities of failure.The overall probability of failure aims to provide the design engineer with a tool to critically evaluate the bench performance from a geotechnical risk perspective and to provide a basis for future bench design optimization.

关键词： Mine safety Rock slope stability Kinematic analysis Probability of failure Limit equilibrium analysis Case study

Volumetric analysis of rock mass instability around haulage drifts in underground mines

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Journal of Rock Mechanics and Geotechnical engineering 2018年第1期10卷 60-71页

作者： Shahé Shnorhokian Bryce MacNeil Hani S.Mitri Department of Mining and Materials Engineering McGill University

Haulage networks are vital to underground mining operations as they constitute the arteries through which blasted ore is transported to surface. In the sublevel stoping method and its variations, haulage drifts are excavated in advance near the ore block that will be mined out. Numerical modeling is a technique that is frequently employed to assess the redistribution of mining-induced stresses, and to compare the impact of different stope sequence scenarios on haulage network stability. In this study,typical geological settings in the Canadian Shield were replicated in a numerical model with a steeplydipping tabular orebody striking EW. All other formations trended in the same direction except for two dykes on either side of the orebody with a WNW-ESE strike. Rock mass properties and in situ stress measurements from a case study mine were used to calibrate the model. Drifts and crosscuts were excavated in the footwall and two stope sequence scenarios-a diminishing pillar and a center-out one-were implemented in 24 mining stages. A combined volumetric-numerical analysis was conducted for two active levels by comparing the extent of unstable rock mass at each stage using shear,compressive, and tensile instability criteria. Comparisons were made between the orebody and the host rock, between the footwall and hanging wall, and between the two stope sequence scenarios. It was determined that in general, the center-out option provided a larger volume of instability with the shear criterion when compared to the diminishing pillar one(625,477 m~3 compared to 586,774 m~3 in the orebody; 588 m~3 compared to 403 m~3 in the host rock). However, the reverse was true for tensile(134,298 m~3 compared to 128,834 m~3 in the orebody; 91,347 m~3 compared to 67,655 m~3 in the host rock)instability where the diminishing pillar option had the more voluminous share.

关键词： Haulage drifts Rock mass instability Volumetric analysis Stope sequences Numerical modeling

Flotation behavior and electronic simulations of rare earth minerals in the presence of dolomite supernatant using sodium oleate collector

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Journal of Rare Earths 2019年第1期37卷 101-112,M0005页

作者： E.R.L.Espiritu G.R.da Silva D.Azizi F.Larachi K.E.Waters Department of Mining and Materials Engineering McGill University department of Chemical engineering Université Laval

Common rare earth (RE) minerals, such as bastnasite and monazite, may be formed in deposits associated with carbonate gangue, such as calcite and dolomite. Sodium oleate is a widely used collector for the flotation of both RE and gangue minerals, which might, therefore, be an inefficient process due to the lack of selectivity of this collector. Since these minerals are also sparingly soluble in solution, they could release their constituent ions into the solution, which could affect the floatability of other minerals. In this study, the interactions of sodium oleate with bastn(a|¨)site and monazite in the presence of dissolved dolomite species have been investigated. Micro flotation tests were carried out to explore the effects of these dissolved species on the floatability of the RE minerals. Zeta potential measurements and XPS characterization were carried out to understand how the species affect the collector adsorption. To complement these characterizations, density functional theory (DFT) simulations were conducted to investigate the collector-mineral and collector-adsorbed species (on the mineral surface) interactions.The results show that collector-dolomite interaction energy is greater than that of collector-adsorbed species, but lower than collector-monazite interaction energy, explaining the decrease in the minerals’recovery upon exposure to the dissolved mineral species. It is also shown that oleate ions (OI^-) have the strongest interaction with the minerals compared to other oleate species such as acid soap (HOI_2^-) and oleate dimer (Ol_2^(2-)). The behavior (strength and selectivity) of sodium oleate towards RE minerals and dolomite, as compared to other RE mineral collectors (such as aromatic hydroxamate), is attributed mainly to the collector's and the minerals'structure. The long hydrocarbon chain of sodium oleate which imparts hydrophobic characteristic to the minerals, makes it stronger collector than benzohydroxamate.Moreover, sodium oleate (with linear structure), unlike the aromatic hydroxa

关键词： Rare earth minerals Bastnasite Monazite Dolomite Sodium oleate DFT simulation

Experimental investigation on the effects of microwave irradiation on kimberlite and granite rocks

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Journal of Rock Mechanics and Geotechnical engineering 2021年第2期13卷 267-274页

作者： Samir M.Deyab Hamed Rafezi Ferri Hassani Mehrdad Kermani Agus P.Sasmito Department of Mining and Materials Engineering McGill UniversityMontrealCanada

This study is a part of an overall research project on the effects of microwave(MW)irradiation on rocks for assisted rock breaking systems as well as mineral processing at McGill University.For the first time,this paper highlights a comprehensive investigation on the effects of microwave irradiation on Canadian kimberlites.Potential contribution to the continuous rock excavation and rock weakening effect prior to implementation of mechanical techniques was explored.Two different kimberlite rocks,i.***.volcaniclastic kimberlite(VK)and hypabyssal kimberlite(HK),and granite samples were studied.Some important physical properties of the rock samples were measured including rock quality designation(RQD),specific gravity,porosity,and specific heat capacity.Rock samples were treated for various exposure times using a multi-mode MWunit at different power levels ranging from 2 kW to 15 kW.The effect of MW irradiation on rock samples was investigated.The results indicate that the mechanical properties including unconfined compressive strength(UCS)and Brazilian tensile strength(BTS)were significantly dropped as a result of MWirradiation.Finally,the effect on rock abrasivity using the Cerchar abrasivity index(CAI)has also been discussed.

关键词： Microwave irradiation Kimberlite Rock excavation Rock strength Abrasivity

Physicochemical aspects of allanite flotation

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Journal of Rare Earths 2014年第5期32卷 476-486页

作者： Adam Jordens Chris Marion Olga Kuzmina Kristian E.Waters Department of Mining and Materials Engineering McGill University

This paper investigated the physicochemical properties of allanite, a RE-silicate, by measuring zeta potential in the absence and presence of three different flotation collectors （benzohydroxamic acid, sodium oleate and dodecylamine）. This data was then verified by microflotation experiments and with bubble-particle attachment pictures. The investigated properties of allanite were com- pared to those of quartz, a common gangue mineral in many RE deposits. The results of this work indicated that only dodecylamine was able to achieve a selective separation of allanite and quartz. This was accomplished by lowering the dodecylamine dosage so that only quartz was recovered by microflotation.

关键词： allanite flotation surface chemistry zeta potential bubble-particle attachment rare earths

Prediction of air flow, methane, and coal dust dispersion in a room and pillar mining face

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International Journal of mining Science and Technology 2017年第4期27卷 657-662页

作者： Lu Yueze Akhtar Saad Sasmito Agus P. Kurnia Jundika C. Department of Mining and Materials Engineering McGill University department of Mechanical engineering Universiti Teknologi PETRONAS

In underground coal mines, uncontrolled accumulation of methane and fine coal dust often leads to serious incidents such as explosion. Therefore, methane and dust dispersion in underground mines is closely monitored and strictly regulated. Accordingly, significant efforts have been devoted to study methane and dust dispersion in underground mines. In this study, methane emission and dust concentration are numerically investigated using a computational fluid dynamics(CFD) approach. Various possible scenarios of underground mine configurations are evaluated. The results indicate that the presence of continuous miner adversely affects the air flow and leads to increased methane and dust concentrations.Nevertheless, it is found that such negative effect can be minimized or even neutralized by operating the scrubber fan in suction mode. In addition, it was found that the combination of scrubber fan in suction mode and brattice results in the best performance in terms of methane and dust removal from the mining face.

关键词： Dust Methane Mine ventilation mining machine

采用人工神经网络基因复合算法预测氧化铜矿柱浸工艺铜浸出率（英文）

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Transactions of Nonferrous Metals Society of China 2017年第3期27卷 686-693页

作者： Fatemeh Sadat HOSEINIAN Aliakbar ABDOLLAHZADE Saeed Soltani MOHAMADI Mohsen HASHEMZADEH department of mining & Metallurgical engineering Amirkabir University of Technology department of mining engineering University of Kashan department of Chemical and materials engineering University of Alberta Edmonton

采用人工神经网络(ANN)以及人工神经网络和基因复合(GANN)算法来优化氧化铜矿柱浸工艺参数。采用三种高度的浸矿柱(2,4,6 m)和尺寸为<25.4 mm和<50.8 mm的两种矿物来进行浸出实验。在台架实验规模下,对浸矿柱高度、矿粒尺寸、硫酸流速... 详细信息

采用人工神经网络(ANN)以及人工神经网络和基因复合(GANN)算法来优化氧化铜矿柱浸工艺参数。采用三种高度的浸矿柱(2,4,6 m)和尺寸为<25.4 mm和<50.8 mm的两种矿物来进行浸出实验。在台架实验规模下,对浸矿柱高度、矿粒尺寸、硫酸流速、浸出时间等工艺参数对铜浸出率的影响进行研究,对浸出条件进行优化以得到最大的浸出率。研究结果表明,铜的浸出率随硫酸流速和浸出时间的增加而增加,随矿粒尺寸和浸矿柱高度的减小而增加。对人工神经网络(ANN)、人工神经网络和基因复合(GANN)算法的效率进行了比较,结果表明,人工神经网络和基因复合(GANN)算法比人工神经网络(ANN)算法更有效。采用新提出的算法模型来预测铜的浸出率误差更低。

关键词：浸出氧化铜矿浸出率人工神经网络基因算法