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By L. O. Thomas

THE Alaska Highway, in its course through British Columbia, traverses parts of two great physiographic divisions of Canada which are also distinctive geologically-the Cordillera in the western section and the Interior Plains in the eastern. The Cordilleran region in the portion of the Province with which this paper deals can be divided into four major northwest systems, known respectively from west to east as Coastal, Plateau, Cassiar-Omineca, and Rocky Mountains. The Coastal system consists solely of the Coast range except in the extreme northwest, where a part of the St. Elias range is included. The Coast range, characterized by mountains of great ruggedness,. is made up of an igneous complex of granitic rocks intruded chiefly as a great batholith. In places, spurs of these rocks extend into the Plateau heft, a partly mountainous tract largely occupied by quartzites, quartzose mica schists and their gneissic phases, and crystalline limestone with interbands and broad areas of chlorite, _hornblende, and sericite schists and bodies of intrusive granite gneiss-an assemblage of rocks known as the Yukon group. The Cassiar-Omineca system marks the divide between the Pacific and Arctic drainages. Its eastern boundary is well defined in the south by the Rocky Mountain Trench (see p. 229). The rocks of the system are, miainly, highly altered Palaeozoic sediments, but there are also Precambrian and Mesozoic rocks, the latter largely volcanic. The core of the system is granitic and there is evidence (see p. 221) to support the belief that it is of such a length as to constitute a batholith comparable to that of the Coastal system.

Jan 1, 1944

"Ore deposits containing rare earth elements normally contain small amounts of the radioactive elements thorium (Th) and/or uranium (U). These are the naturally-occurring isotopes U238, U235, and Th232 (and associated decay-series daughter products) that are ubiquitous in nature, and that contribute a small percentage of the natural background radiation exposure encountered by humans. The presence of these radioactive materials in the ore deposit creates potential hazards to human health and the environment that must be dealt with properly in the mining, processing, and refining of the ores, as well as management of waste streams and residues. This paper presents an overview of the environmental and safety issues associated with U and Th, with particular emphasis on rare earth mining, processing, and refining projects; the regulatory approaches followed to ensure that rare earth deposits are developed, operated, closed, and decommissioned safely; and the development of information during the project predevelopment work and permitting processes that feed into the design, operation, and closure of tailings impoundments and milling/separation/refining facilities. Case studies will be presented subject to the availability of relevant public information. INTRODUCTIONNearly all ore deposits containing economically-recoverable rare earth minerals also contain small amounts of the radioactive isotopes for the elements thorium (Th) and/or uranium (U) and their associated radioactive decay products. Therefore, the handling and management of these materials in mining and mineral processing operations must be performed so that workers and the environment are protected from harm from Th and/or U (and their radioactive decay products), just as they must be protected from any other potentially harmful constituents present in the ore or introduced in processing. Examples of these might include ores with high sulfide content, which may pose a risk of acid rock drainage, or chemicals used in ore processing and metals production.The purpose of this paper is to present information on how rare earth mining and processing projects with ores containing Th and/or U can be developed, operated, and decommissioned safely according to applicable regulations intended to protect worker health & safety and the environment.It should be noted that some countries are considering developing Th as a feedstock for producing nuclear energy, which could have some effect on future development of rare earth ore deposits. To avoid confusion, that issue is not discussed in this paper."

Jan 1, 2012

By Lin-fang Shen, Shao-jun Li, Zhi-liang Wang

"The meso-structure of real soil consists of numerous particles with different sizes, while the traditional reconstruction method of quartet structure generation set (QSGS) produce relatively uniform soil particles resulting in significant discrepancy between the actual structure and reconfiguration model. In order to remedy the deficiency, the QSGS is improved by considering the influence of porosity and autocorrelative function of soil, which make the models closer to the real soil. Based on the reconfiguration model, Lattice Boltzmann method is combined in the algorithm to conduct further simulation of fluid flow in soil pores. The D2Q9 model is applied to construct the two dimensional model for simulating mesoscopic seepage field of saturated soil by setting the non-equilibrium extrapolation scheme at the inlet and outlet boundary, and the bounce-back scheme at the soil particles boundary as well as the left and right boundary. According to the case study, the proposed program is realized to simulate mesoscopic seepage field of reconstructed soil with constant inlet seepage velocity. The results show that the seepage direction of soil is along the passage with good connectivity, therefore the permeability is controlled by these passages. The seepage velocity in such channels is faster than in bad connectivity channels. Even if the channel has larger pores, the seepage velocity is still small. INTRODUCTIONUnderstanding the seepage mechanism in porous materials is significant in both theoretical and engineering problems. As a typical porous media, soil consists of solid particles and voids, which form connected channels allowing water to flow through. Such seepage in soil exists widely among geotechnical project of slope, foundation pit, and tunnel, etc. Meanwhile, a number of engineering accidents are caused by limited knowledge of seepage characters in soil (Huang, 2006; Liu, 2013). The conventional method in describing seepage features mostly based on the parameter of permeability, which is a macro statistic mean evaluating the whole connectivity of soil. Obviously, this parameter cannot exactly reflect the details of how water flows through the inner soil structure, especially the flow velocity in local mesoscopic area, hence is unable to represent the actual seepage properties. Therefore, it is necessary to develop mesoscopic approaches to fully study the seepage mechanisms."

Jan 1, 2015

The Shortage of Mining and Metallurgical Engineers I N many parts of the Western World attention has recently been drawn to the acute shortage of mining and metallurgical engineers produced by the universities. Naturally, the reasons for this shortage have been discussed, and various remedies for it have been proposed. In this paper, I want to examine some of them. It is now fairly generally ac-cepted among mining men that the easy attractions of modern urban life have left the career of mining in the metaphorical as well as in the literal backwoods. The industry finds it increasingly difficult to recruit adventurous and intelligent young men; for such men now seek their intellectual, if not physical, adventure in more glamorous occupations from a safe social base in suburbia. The salaries, opportunities and security offered by the mining industry do not complete effectively with the rewards offered by other industries and by commerce, taking into account the social disadvantages of a mining life. The excitement and other non-material attractions of mining

Jan 1, 1965

By P. C. Parsons, G. C. Milligan

"IN FIELD WORK in the Cape Breton Highlands, which are heavily covered with vegetation, it is necessary to run traverses along the valleys of small brooks. We encountered difficulty in closing such traverses, and the following technique was developed to solve this problem. It has been tested in the field for four seasons by several people, and found to be simple, efficient and more accurate than any other compass-and-pace system of which we are aware. So far as we can find, the technique has not been described previously. It may be of use to others.The Cape Breton Highlands of Nova Scotia consist of hills of old intrusive and metamorphosed sedimentary rocks protruding up to 1,000 feet above the general level of the younger sediments which underlie the valleys. The flat hill-tops are the remnants of a plateau; drainage off the edge of this plateau has produced many small steep brooks. They occupy valleys which are up to 800 feet deep, and V-shaped in cross section, with steep sides covered by mixed conifers and hardwoods. The stream at the bottom is rarely more than a few feet wide, with a negligible meander belt, but with many bends, rapids and falls. Visibility along the stream, in consequence, is rarely more than a few hundred feet, and in many places much less.It was found impractical to map the streams by the method of meander lines, as described in many standard surveying texts and hand-books. The limited visibility, and the numerous bends of the brooks, necessitated many corners. Every corner introduces errors. To 'close' a survey with 40 or 50 such corners proved either very time-consuming or impossible. In most cases, however, the general direction of a valley may be obtained from an aerial photograph, or by direct observation, and this became the basis of the method adopted."

Jan 1, 1971

By L. Dorador

"In block caving projects, the rock mass fragmentation process plays a controlling role in the design and success of the operation. Poorly understood, however, is the secondary fragmentation that occurs as blocks of caved ore move through the draw column and interact with one another. The initial size of these blocks can be considerable, as can their strength and stiffness as the presence of non-persistent joints and veining will be variable. Intuitively, more planes of weakness within the blocks should facilitate early fragmentation, but this assumption could depend on additional factors such as contact type between adjacent blocks and loads imposed through varying heights of the draw column. This paper reports the findings from a laboratory investigation examining the role of block strength and planes of weakness on secondary fragmentation. Testing was carried out on small-scale concrete cubes of uniform size, with and without embedded planes of weakness. The results obtained demonstrate the significance of veining and other planes of weakness on secondary fragmentation under one-dimensional compression, and allow for the development and constraint of empirical guidelines.INTRODUCTIONThe fragmentation process during block caving involves the initial (primary) fragmentation of rock in the cave back through stress-induced fracturing, release and fall of individual blocks onto the broken ore muck pile. This is followed by secondary fragmentation involving splitting and rounding of blocks as they move downwards through the draw column towards the draw point. The degree of secondary fragmentation achieved involves many variables related to the mechanical properties of the rock blocks as well as different operational factors. With respect to the block properties, the presence of planes of weakness in the form of veining and non-persistent joints is a topic of special interest given the significant influence it potentially has on the overall fragmentation process. However, the inherent heterogeneity and variable size of individual blocks generated from the cave back makes it difficult to develop any empirical relationships relating secondary fragmentation to compressive loading based on insitu observations and mine data. More preferable would be to keep constant block parameters, such as shape (aspect ratio and angularity) and size, through controlled laboratory testing. This work presents an efficient technique to fabricate concrete cubes in order to keep constant different block properties. These are then tested under one-dimensional compressive loading. The objective of these tests is to emulate a tight packing condition of single blocks such as that which would occur when the air gap between the cave back and broken ore in the draw column is small. When the air gap is small, detached blocks are unable to fall and rotate but instead maintain a very tidy arrangement with minimal voids left between adjacent blocks."

Jan 1, 2015

By Douglas Brand

"The data that many mineral processing plants make use of, is provided by samples taken from sampling systems which are inadequately designed or improperly maintained, and therefore cause detrimental effects to plant operations, production planning and metallurgical accounting! Poorly designed or maintained sampling systems will likely produce low probability samples which give the operator a false sense of security of the product and the process. If data is the basis for action (Flintoff, 1992, p.2), then using the resulting suspect or bad assays by operators, control systems, or metallurgist and administration personnel will act and make decisions which may adversely affect the profitability of a processing plant. Here we will discuss some of the fundamental sampling problems, propagation of errors and a method to estimate what impact this has on an operations Net Smelter Return.INTRODUCTIONIn order to control a mineral processing plant at its best potential, it is necessary to obtain the best possible measurement results of the metal or mineral in question. The sample which is delivered to a measuring instrument, or lab, needs to be of the highest probability to be able to achieve this. This paper will discuss the effects of sampling errors on grade / recovery and grade / Net Smelter Return (NSR) and provide a method to estimate the monetary advantages of using probabilistic sampling in a processing plant.REVIEW OF SAMPLINGSampling, by definition, is the removal of a small representative portion from a total consignment, or flow, for the purpose of accounting or process control.• A sample can only be considered representative, if each and every increment collected, in each of the sampling stages, is representative.• Each particle of the sampling lot must have the same probability of being included in the final sample.• If both of the above conditions are met, then the final sample will be representative of the complete sampling lot.It is commonly known that in order to take truly representative and probabilistic sample, best practices indicate that:• The total stream should be sampled.• The sample cutter should intersect the sample at right angles to the flow.• The sample cutter should travel through the stream at a linear and constant speed and the speed deviations should be less than 5%."

Jan 1, 2016

By H. R. Hammond, E. Sadar

Cominco is making substantial savings in secondary breaking by replacing dynamite with a new nitrate-based explosive. Compareo with dynamite. the new explosive, known locally as "Fine NCN," is significantly cheaper, more effective and safer to use. It also works better than prilled NCN, which is unsatisfactory for secondary blasting because of inadequate sensitivity, low strength and awkward handling properties. A simple apparatus has been devised for pulverizing prilled NCN to a fineness practical for effective secondary breaking. Blasting systems using cheap detonating cord for initiation have been developed.

Jan 1, 1966

By E. Peek, L. Becze, K. Reading

"Gallium oxide is an important semiconductor material used in optoelectronic devices (flat panel and solar cell) catalysts and sensors. One of the methods to produce ?-Ga2O3 is the so-called hydrothermal route. It is practiced by Neo Gallium Compounds and comprises of two steps: (1) the production of mainly gallium-oxy-hydroxide in a pressure vessel by reacting metallic gallium with water at 200-220 ºC and (2) the calcination of gallium-oxy-hydroxide at 700-750 ºC to convert it into ?-Ga2O3. This paper describes this pressure hydrometallurgy process supported with relevant thermodynamic data and presents the characteristics of the ?-Ga2O3 powder produced for commercial purposes. INTRODUCTIONGallium is a relatively new metal, having been predicted by D. Mendeleev in 1871, discovered by P.E. Lecoq de Boisbaudran in 1875, and first commercially produced in the USA in 1943. Gallium is not rare, being more abundant in the earth crust than antimony, bismuth, molybdenum, silver and tungsten. However, few gallium minerals exist in nature, and the dispersion of gallium within other minerals add to the complexity of its recovery. In practice, gallium is found in dispersed state primarily in bauxites and in some sphalerites, and, to a much smaller extent, in some coals. At present, a very large proportion of the primary gallium in the world is recovered as a by-product of aluminum plants, mostly Bayer plants, where gallium is extracted from a bleed of the Bayer liquor (Roskill, 2011). In 2011, world production of primary gallium was estimated at 200 metric tonnes. In addition, there is a significant contribution of recycling to the overall yearly availability of the metal.Gallium exhibits fairly remarkable properties: it is liquid above 29.76 ºC, can be supercooled, and with its high boiling point (2204 ºC), is the metal with the widest liquid range. Gallium is magnetic, and is an excellent conductor of both heat and electricity. Gallium also displays a marked anisotropic electrical conductivity (Roskill, 2011). All these properties render gallium almost irreplaceable in the semiconductors (GaAs, GaN, GaSb, GaP wafers) and the optoelectronics industry (flat panel, solar cell)."

Jan 1, 2012

By I. Farr, M. R. Mock, J. C. Robison

"HPAL and POX autoclave vapor-space gasses are vented through an autoclave PCV (Pressure Control Valve). The downstream steam-born mist of liquid droplets and solid particles travels in excess of 1000 m/s with megawatts of kinetic power at temperatures up to 160 C. The characteristics of downstream states often result in problems with corrosion, erosion, noise and vibration. Comprehension of those and related characteristics aids in improved pressure control, overpressure control and autoclave level control. We introduce compressible multiphase flow concepts and constructs germane to such flow including choked flow, continuous phase change, shock waves and supersonic flow plumes. Flow modeling based on first principles quantitatively predicts such flows providing a tool for component sizing and a method to estimate effects of water injection on flow. Insight deduced from modeling aids in mitigation of afore mentioned problems of which we share some from-site examples.INTRODUCTION First principles related to fluid thermodynamics and compressible flow have been employed akin to their application in the rocket industry. We will present the results of the application of those principles conceptually and authentically without mathematical rigour while using language of the pertinent disciplines. The autoclave (AC) vapor space over the slurry of a POX (Pressure Oxidation) or HPAL (High-Pressure Acid Leach) system (depicted in Figure 1) is vented via a PCV (pressure control valve) followed by certain ducting, and perhaps a nozzle, before exiting at atmospheric (typically) pressure. As indicated by its name the PCV controls the AC pressure as the flow control component of a pressure control loop."

Jan 1, 2017

By M. Hamamoto, M. Furuta, S. Tanaka

The Tamano smelter and refinery has expanded its production from 228kt/y to 260kt/y since 2006. It was not a big jump, but efficient and economical improvements were executed. These were not only de-bottlenecking and modernization of the smelting plant, including the acid plant, but also additional processes were commissioned, e.g. slag cleaning furnace and steam dryer. On the other hand, a conversion to permanent cathode process in the #2 tank house made the biggest impact on production efficiency for the refinery plant. In order to overcome the drastic change of copper business, although each scale is not so big, continuous improvements are very important to survive. This paper mainly describes the recent improvements of the smelting plant.

Jan 1, 2007

By Afshin Sadri, Wai Lai Ying, Brycklin Wilson, Zoe Coull

"Although there have been great steps forward to integrate corrosion engineering into operations, there is still an underlying tendency for maintenance tasks to be performed in a reactive manner. This is especially true when strategies focus on lagging indicators such as visual inspections, RCA (root-cause analysis), and FMECA (failure mode, effects and criticality analysis). This trend to “reactive maintenance” can be avoided by utilizing more inspection and monitoring methods to identify leading indicators of failures. Prevention is generally less costly than repairs; moreover, when paired with appropriate monitoring techniques, intervention of corrosion protection can be more effectively timed and based on more accurate data. Hatch asset reliability studies show nearly 80% of defects are introduced through operations and maintenance. Therefore, proactive corrosion management can provide the necessary feedback to optimize operations and maintenance strategies preventing costly corrosion losses. Understanding corrosion risks gives a clear picture of the benefits of a proactive approach to asset performance. Monitoring techniques (Non-Destructive Testing, field testing, sampling, etc.) by nature are a more effective means of improving maintenance efforts and preventing corrosion losses than other methods (RCA, FMECA). This paper will outline the importance of proactive corrosion management and demonstrate its benefits through industry examples.INTRODUCTION Over the past few decades, with the growth of technology and awareness of sustainable development many studies have shown the benefits of a proactive approach to maintenance strategies. However, in practice there is still an underlying tendency for maintenance tasks to be performed in a “reactive manner”. This is especially true when strategies focus on lagging indicators such as visual inspections, RCA (root-cause analysis), and FMECA (failure mode, effects and criticality analysis). This trend to “reactive maintenance” can be avoided by utilizing more inspection and monitoring methods to identify defects and leading indicators to failures."

Jan 1, 2017

By V. Polotski

Initiated and financed by the Canadian Space Agency, Micro-Rover Platform with Tooling Arm (MRPTA) project has targeted the development of a robotic system with remote control and autonomous navigation capabilities for testing a large variety of analogous planetary missions. Although developed for planetary exploration, the navigation system is highly suitable to such areas of application as construction and in mining. Autonomous navigation system is capable of moving the platform to predefined position(s)/orientation(s) while continuously mapping the terrain, assessing its traversability and choosing most appropriate path to follow. Designed according to the JAUS (Joint Architecture for Unmanned Systems) framework, the system consists of several interconnected components. Following components are of particular importance: Pose Estimator (PE), Terrain Evaluator (TE), Map Manager (MP), and Path Planner (PP). The PE uses a minimal sensor configuration consisting of an azimuth gyroscope, inclinometer and wheel odometry. The PE provides reliable pose estimates in spite of pronounced slippage by employing extensive use of fused data. The TE uses a nodding laser scanner which continuously sweeps the area in front of the platform and constructs a ?traversability grid? (TG) of the surrounding area. Multiple TGs are constantly constructed along the platform motion path are combined into a terrain map maintained by the MP. The PP uses this map to compute a motion path Obtained path is executed by the motion controller and remains current until it is contradicted by the most recent map ? at which point it is re-planned. This paper addresses integration issues, lessons learned and also outlines the possible applications for construction and mining.

Aug 1, 2013

By Graham Farquharson, Jame Marshall

"Mining towns have always been an important part of Canadian geography. Many Canadians grew up in them. The frontiers of northern Canada would be a lot closer to the United States border but for the pioneering of new mines, new towns, and new transportation routes. Names such as Labrador City, Chibougamau, Val d’Or, Rouyn-Noranda, Kirkland Lake, Timmins, Sudbury, Red Lake, Thompson, Flin Flon, Yellowknife, Whitehorse,Trail and Kimberley are some of the better known larger communities that have grown to become major commercial and government centres, but which started as the base for a mining development.Many other smaller towns never grew beyond being small communities, dependent upon the local mine and many of these are still alive, but perhaps not quite what they used to be. In this list would be Buchans, Schefferville, Chapais, Cadillac, Virginia town, Lynn Lake, Uranium City, Pine Point, and Keno Hill.Nevertheless, all these towns and dozens more like them were residential communities where people lived and raised families and were quite accustomed to being days from the major centres of Montreal, Toronto, Edmonton and Vancouver, and not just hours away as wet end to measure travelling time today."

Jan 1, 1996

By J. Olson

"A model was developed to use near-infrared (NIR) analysis of pulverized ore samples to estimate the recoverable gold content for ores from the Barrick Cortez Hills underground mine. Current routing practices use a ratio of the cyanide soluble gold content and fire assayed gold (CN/FA) to classify ores as oxide or refractory. Prediction accuracy of the NIR model was equivalent to the CN/FA ratio. Prediction accuracy was improved by combining the CN/FA ratio and the NIR spectra. Bootstrap validation estimates the root-mean-square error to be 9.92% with an estimated r-squared value of 0.893. This model will allow more accurate estimates of the variability in recoverable gold content throughout this mine. These data will aid in building an improved geo-metallurgical model or in making better informed routing decisions during the production cycle.INTRODUCTION The contained gold of an ore available for cyanidation is often related to subtle variations in the mineralogy. It is difficult and expensive to collect enough mineralogical information in order to predict how the variable mineralogy will impact the metallurgical results and project economics throughout the life of the mine or mill. Near-infrared spectroscopy may be an effective tool to rapidly and inexpensively collect discrete, quantitative mineralogical data for minerals that contain transition metal oxides, metal sulfides with semi-conduction properties, rare earth metals, and some chemical groups having di-pole covalent bonds such as carbonates, sulfates, and various types of clays (Hunt, 1977). Near-infrared spectroscopy can be a powerful tool for geo-metallurgical characterization of deposits where the presence of these minerals has direct or indirect relationships to metallurgical results such as grindability, regent consumption, or recovery. Near infrared spectroscopy is a rapid analysis that measures the intensity of reflected light in the near-infrared spectrum. The ranges for the ASD-Panalytical units used in this study extend through the visible spectrum and into part of the UV spectrum, reporting reflection by wavelength from between 350 nm to 2500 nm. Absorption peaks visible in this range are a result of interactions with outer valence elections or chemical bonds. The location and intensity of the peaks vary depending on the chemical composition and crystal structure of a solid indicating the presence and abundance certain minerals (Hunt, 1977; Clark, 1984)."

Jan 1, 2017

By F. Henríquez, V. Iriarte, L. Vinnett, J. Yianatos, F. Díaz

Metallurgical characterizations of the collective (Cu/Mo) and selective flotation plants were carried out in Minera Los Pelambres, Chile. The selective plant allows the valuable minerals of Cu and Mo to be separated. The evaluation involved two surveys consisting of metallurgical sampling as well as residence time distribution (RTD) measurements to determine load distribution. The RTD data were obtained in real-time by means of the radioactive tracer technique. In addition, metallurgical data was reconciled and supported by effective residence times. In the collective plant, a performance comparison of parallel rougher circuits was carried out, which included a bank of six mechanical cells of 250 m3 and banks of nine mechanical cells of 130 m3. In the selective plant, the Cu and Mo evolution along the plant was evaluated. The results in the selective plant allowed for performance evaluation of mechanical and pneumatic cells in primary flotation. In both plants, mineral losses were evaluated and their relationship with circuit configuration (cell types and circuit layout) was determined. The metallurgical characterization was a powerful tool to evaluate circuit performance and to detect improvement opportunities at industrial scale.

Jan 1, 2015

By Claude Bourgoin

"The Copra massive sulphide deposit occurs as a continuous slab of ore dipping at approximately 40 degrees within a sericite schist formation. The orebody has been delineated over a distance of more than 5,000 feet down dip. This paper is mainly concerned with the mining procedure, and particular reference will be made to the use of steel mill holes and hydraulic roof supports. The gravel backfill line, which is operated both by gravity and hydraulically, is described. The paper mentions some of the operational problems, discusses the feasibility of longwall mining and presents the information obtained from stope testing."

Jan 1, 1966

By John Kostuik

"This paper discusses the outlook for uranium resources, and comments briefly on the measures needed to meet market objectives. Areas of recent exploration interest are also discussed.THE PREVIOUS SPEAKER has capably described the truly phenomenal growth in demand for energy from all sources. The basic factors -population growth and industrial development -which will create energy demand are so fundamental to national economies that the ascending energy demand curve will be little affected by short-term factors.Because of the economic and practical advantages of nuclear power and the degree of present acceptance by electric utilities, there is no doubt that uranium will be a principal source of primary energy in industrial countries -and this will happen within a decade. Indeed, during this period it will be the fastest growing source of energy, capturing, for example, more than half of the electric utilities' expansion in the United States by 1980. The ready availability of energy sources from domestic and foreign resources is so essential to industrial nations that the long-range outlook for their adequacy is of prime importance. There has been international concern about the availability of uranium resources at reasonable cost to adequately support and foster the development of the nuclear power industry. Canada, fortunate in having established reserves and a potential in excess of any forseeable domestic demand, can confidently look forward to being a principal supplier to the industry."

Jan 1, 1969

By Gurupraveen Ramanathan

Shallow-dipping orebodies (45°–60° dip) present significant challenges for underground longhole stoping, particularly due to limited gravity flow, drill misalignment near the footwall, increased potential for dilution from hanging wall overbreak, and deviation from drill string sagging at shallow angles. These geometrical and operational constraints often lead to unblasted ore wedges and excessive overbreak when standard practices are applied. This study develops a structured, data-driven framework to optimize longhole stoping in such conditions by integrating five key focus areas: (1) mining method selection, (2) stope and drift design, (3) drill and blast optimization, (4) equipment selection, and (5) performance evaluation. The suitability of longitudinal longhole stoping was validated for narrow vein geometries using orebody analytics and prior case studies. Geometric modeling was employed to determine optimal stope height (15–20 m) and stope width (1.5–2.5 m), with drift widths adjusted based on orebody dip to maintain drill access and minimize unbroken ore. Drill and blast design emphasized sequential blasting over multi-ring methods to improve void control, reduce wall damage, and enhance fragmentation. Specific burden and spacing guidelines (e.g., 1.8–2.3 m burden; 2.5–3.0 m spacing) were applied based on stope width and dip angle, and patterns were selected based on geometry—dice-5 for narrow stopes, and 3-hole rows for wider stopes. Drill rigs—including top hammer and ITH models from Sandvik, Epiroc, Boart Longyear and CMAC-Thyssen—were evaluated for compatibility with drift dimensions and alignment accuracy. Equipment was matched based on dip, drift width, and the ability to access the footwall at shallow angles. Sensitivity analysis quantified how changes in geometry, drilling accuracy, and blast design affect ore recovery, dilution, and operating cash flow. Results show that tailored drift and stope geometries, combined with proper blasting and rig selection, can boost ore recovery to over 95% and reduce dilution to below 5% in optimal conditions. This methodology offers a practical and economically optimized solution for shallow-dip mining scenarios.

May 4, 2025

By K. R. Barnard, K. D. Marte, T. V. Gamarano

"The first commercial scale application of CSIRO’s direct solvent extraction (DSX) technology has been in operation at the Boleo project in Mexico since December, 2015. In this application, DSX is a synergistic solvent extraction system consisting of the extractants LIX 63 and Versatic 10 for recovery of cobalt and zinc from a solution background of manganese, magnesium, and calcium. Key operating parameters such as metal extraction, phase disengagement and extractant stability are summarized and discussed in this paper.INTRODUCTION Commissioning of the Boleo processing plant, located on Mexico’s Baja peninsula, began with the copper circuit starting in late 2014, with first copper cathode production achieved in January, 2015. The cobalt and zinc circuits began commissioning in December, 2015 with first zinc sulphate monohydrate (ZSM) and cobalt cathode production achieved in February and April, 2016 respectively. The Boleo project flow sheet and development has been described in detail in previous publications (Dreisinger, et al. 2005; Dreisinger, Baxter, & Molnar, 2006; Dreisinger, et al. 2008; Dreisinger, et al. 2009) and is summarized schematically in Figure 1. Boleo is a mixed oxide/sulphide Cu-Co-Zn-Mn high clay deposit that is processed in a whole ore, atmospheric, oxidative and reductive, sulphuric acid/seawater leach. Copper is recovered as cathode by conventional solvent extraction and electrowinning. Cobalt and zinc are recovered, from a solution background of manganese, magnesium, and calcium, by CSIRO’s synergistic solvent extraction technology Direct Solvent Extraction (DSX). Cobalt and zinc are bulk stripped from the DSX circuit and then further purified by phosphinic acid solvent extraction to produce zinc sulphate monohydrate granules via spray dried granulation and cobalt cathode rounds via divided cell electrowinning."

Jan 1, 2017