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By Michael Arriagada, Ivan Arriagada

"As mines return to shafts to economically exploit deeper reserves, two methods mine owners use to minimize short term costs are: sinking shafts in phases and refurbishing old, existing shafts. While there may appear to be benefits to utilizing existing infrastructure, often this is not the case, resulting in missed deadlines and added costs. Similarly, if proper long term planning is not executed when sinking a shaft in phases, additional costs and downtime will be accrued. This paper will take an in depth look at both of these options with an eye towards optimizing costs, minimizing downtime, and facilitating construction. INTRODUCTION With the onset of mechanized mining and large capacity trucks, many mines turned away from shafts and began to use ramps to haul ore to surface. However, continual exploitation of mineral reserves located closer to surface, combined with the subsequent unearthing of additional resources at greater depths, forced mines to go deeper and deeper to extend the life and keep the operation running. In shallow mines, hauling ore by truck was an economical option. However, as mines get deeper, driving ramps takes additional time, and hauling over longer and longer distances becomes less economic, both in terms of cost and time. For this reason Mexico, in particular, has seen a jump in the number of shafts which have been put into production, as well as having a number of shafts in different stages of development and still more in the conceptual stages. Many of the shaft projects in Mexico are being designed in phases, with the hoist and equipment purchased capable of reaching the ultimate planned depth of the shaft, but with sinking operations stopping short at an intermediate depth. A loading pocket is then installed to start exploiting mineral at this depth sooner, with subsequent phases planned for a later date using either a rock pentice or bulkhead to separate the sinking operations from the active shaft above. Currently, we are directly involved in two such projects which are actively being deepened, as well as having seen various others already reach completion. If done properly with the long-term plan in mind, sinking in phases can be a very viable option, allowing for faster production while fully utilizing the equipment at various depths. However, there are many issues which can arise when sinking a shaft in phases that if not properly examined and planned for from the outset, have the potential to eliminate the gains hoped for when it was decided to sink in this manner."

Jan 1, 2019

By K. Maruyama, T. Nagasaka, R. d. Chairaksa-Fujimoto, T. Miki

Electric arc furnace dust or EAF dust is considered as a hazardous waste but contains a significant amount of economically attractive non-ferrous metals especially zinc as zinc ferrite (ZnFe2O4) and zincite (ZnO). The hydrometallurgical process is one alternative choice because it has the advantage of low energy consumption. The leaching of ZnO from the dust is very easy. However, the complex major zinc compound in EAF dust is ZnFe2O4, which is very stable and insoluble in alkaline or acidic media under delicate conditions, and causes the low zinc recovery yield by hydrometallurgical process. Moreover, halogens and heavy metals in the dust are also problematic. In order to develop a new effective EAF dust treatment process, the authors have proposed "CaO addition process" as pre-dust treatment to transform all of ZnFe2O4 in the EAF dust to ZnO and Ca2Fe2O5. In this study, the selective zinc leaching from the CaO treated EAF dust with NaOH and NH4Cl solutions was carried out. The effect of temperature, reaction time and solute concentration were systematically investigated. All of zinc in CaO treated EAF dust was successfully leached into both solutions.

Jan 1, 2014

By V. Falmagne

The mining sequence at Noranda?s Bell-Allard mine calls for two mining fronts retreating toward a central pillar known as the Retreat Zone between pyramids A and C. It is clear from numerical modelling and rock mass characterization that the induced stress level in the pillar will exceed the rock mass capacity. A mining plan was developed including the re-dimensioning of stopes in the Retreat Zone, additional ground support and instrumentation in order to ensure the safety of the workforce and to maximize ore recovery while minimizing production delays. The mining strategy consists in allowing the rock mass to fracture and fail progressively while maintaining control of the existing openings with the appropriate support. A systematic analysis of rockbursting and caving hazards was conducted for all accesses and stopes in order to plan ground support and instrumentation needs.

Apr 1, 2004

By D. S. Salonine

Aluminum alloys are widely used in modern industry. Tubes and hollow shapes give great opportunities for structural purposes as well as fluid transport due to their stiffness and lightness, Extrusions on a mandrel or through a bridge die, that requires splitting of the billet with re-welding, produce hollow shapes with varied contours, fins and multiple cavities. Moving and stationary mandrels, mandrel lubrication, tooling for ribbed-tube heat exchangers, and for drilling pipes are considered. Bridge dies can be classified by the bridge position relative to the die face, by mandrel support structure, and by assembly type, The main parameters influencing the quality of the die-welded seams are considered, The difficulties of extruding various alloys through bridge dies are discussed in terms of metallurgical factors, Some approaches to the calculation of the stresses in a bridge are presented.

Jan 1, 2005

By K. Hambrice, E. Fauveau

"When it comes to measuring the level of bulk solids, liquids, and everything in between, guided-wave radar technology now offers more level-detection capabilities than ever before. For an ever-widening range of previously hard-tomeasure products such as molten sulphur, liquid ammonia and petrochemicals, guided-wave radar transmitters provide accurate level measurements even under harsh chemical environments, wide variations in operating temperatures and pressures, and low dielectric constants.Great strides have been achieved in making these units easier to configure to a variety of process applications coupled with the simplicity of integrating these devices with most digital communication protocols. These improvements come as welcome relief to process engineers within an expanded range of level applications across several different industries that seek solutions to measuring the contents of tanks, silos, hoppers, bins, mixing basins, and vessels.Because radar transmitters have no moving parts, radar has already established a dominant niche in level measuring that quickly distances itself from mechanical means, which do not hold up as well in dirty service. Radar achieves its nonmechanical level detection capability by measuring the time of flight of the transmitted signal.Known more accurately as time domain reflectometry (TDR), the process involves sending microwave energy down into a vessel. When the pulse of radar energy reaches the product (indicated by a change in impedance), part of the pulse is reflected back toward the transmitter.A receiver measures the exact duration of time between the transmitted and reflected signal — the “time of flight.” The device analyzes this time and ultimately displays the level of the product as a distance in feet, metres, or other engineering units."

Jan 1, 2003

By R R. Wainwright

Friction-type hoists have been in operation at Geco Mines Limited since Septtember, 1957. At the end of the year 1963, the skip hoist had handled nearly ~ million tons of ore and waste. In March, 1962, with the deepening of the shaft, the hoisting de11th was increased from 1,450 to 2,450 feet. Operating experience with the hoists, hoist and balance ropes, rope treads and other related equipment is presented. The paper is intended to supplement an earlier one -"Heavy-Duty Friction Hoisting at Geco Mines," by W. M. Harvey (C.I.M. Transactions, Volume LXIII, 1960, pp. 193 -197). General G ECO Mine Limited is located at Manitouwadge, Ontario, approximately 160 miles east of Port Arthur and 190 mile northwest of Sault Ste. Marie. The Company was formed to exploit a copper-zinc-silver orebody, with current ore reserve (1963) of approximately 21 million tons. The production plant was designed to mine and treat 1.25 million tons per annum. The production and service hoists are mounted at-the top of a reinforced concrete tower above the shaft.

Jan 1, 1965

By Raymond B. Hryciuk

Environmental auditing has evolved rapidly over the last decade — first in North America, then Europe, and most recently in Asia — into a widely practiced discipline designed to provide senior management with assurance that operations are being managed in compliance with established governmental standards, internal company policies, and good industry practices. This paper first examines the evolution of environmental auditing, focusing in particular on three interlocking driving forces: company initiatives, collaborative industry initiatives, and government initiatives. Characteristics of effective audit programs, those that have emerged among the leaders, are discussed, including: objectives, scope, coverage, approach, staffing, and organizational considerations. The author then addresses important future trends and developments for environmental audit program design, content, and coverage.

Jan 1, 1996

By A. Supomo, H. Resendiz, C. Burbidge

"Freeport-McMoRan Inc. (FMI) commissioned the expansion of the Morenci Metcalf concentrator in 2014. The concentrator included many design and equipment innovations, including the first-of-its-kind Metso Hydraulic Roll Crusher (HRC), variable speed ball mills and variable speed crushers. In addition to the innovative design, FMI commissioned the Metso APC team to design a realistic process simulator and the plant APC. The process simulator was utilized to train operators before commissioning, which led to a smoother plant start up. The plant APC utilized the concept of dynamic constraint control, which controls the feed to the primary ball mills by “pulling” the tons from crushed rock storage bins, which then automatically are filled by the upstream HRC and secondary crushing circuits. The primary ball-mill control also adjusts the water addition to the cyclone clusters to avoid overload and achieve sufficient grind size. The constraints include in-circuit constraints for feeder capacity, screen-deck capacity, ball mill power, cyclone mass flow, pump capacity and pump motor capacity. The APC system was implemented shortly after the start of commissioning and immediately demonstrated increased throughput and an ability to highlight and quantify process constraints and bottlenecks. The following paper outlines the control strategy, discusses system implementation, results and challenges.INTRODUCTION The FMI Metcalf Concentrator is located in Morenci Arizona on the site of the old original Concentrator. The new Metcalf concentrator started operation in May of 2014. This plant was designed for an average of 63,500 tpd (70,000 stpd), increasing the total Morenci concentrator complex production to a nominal 113,400 tpd (125,000 stpd). The process flow diagram is shown below in Figure 1.The process consists of primary crushing feeding a coarse ore stockpile followed by secondary crushing operating in closed circuit with vibrating screen decks. The screen undersize feeds the first of its kind Metso hydraulic roll crusher (HRC) operating in a closed circuit with vibrating screens. The primary crusher is a Metso 60x110 gyratory crusher. Secondary crushers are Metso MP1250 Crushers with variable speed drives. Secondary crusher discharge is recycled to the dry screen feed bin and screened with oversize returning to secondary crushing and undersize feeding the Metso HRC3000. The product from the 3.0 meter X 2.0 meter roll crusher is wet screened with the undersize feeding the grinding circuit, which is comprised of two each 24-foot diameter by 40- foot-long variable speed ball mills running in parallel with each in closed circuit with a cyclone bank of 12 cyclones. The wet screen oversize is recycled to the HRC feed bin."

Jan 1, 2019

By C. R. Tang

Due to the current lack of sufficient occupational hazards supervisory staff in China, an occupational hazards supervision regulatory framework is proposed, based on the cloud. Data on respirable dust, noise, heat, toxic and hazardous substances and protection facilities are uploaded to private cloud computing data and service centers to build an occupational hazards supervision system. This system promotes occupational hazards governance. Complex reports are generated. Through the establishment of an occupational hazard supervision data threshold, the dynamic regulation of occupational hazards is accomplished. The main characteristics of this approach are low cost, ease of expansion and maintenance, and strong performance.

Aug 1, 2013

By J. J. Crowder, A. L. Coulson

Ground support is a significant component of underground mining costs. The rehabilitation of failed support, however, is often much more expensive than the initial installation. This paper investigates whether the right type and length of support can be designed correctly the first time, through forward modelling of the support and the mining process. Back analyses demonstrate how high-quality instrumentation and monitoring can help with the estimation of the post-peak (post-failure) rock mass parameters required for a comprehensive analysis. A hybrid modelling approach combines a three-dimensional mine-wide boundary element model with a non-linear finite element model to allow for the failure process in the rock mass. The back analyses demonstrate that, for the case study site, the post-peak Generalized Hoek-Brown value of mr must be reduced significantly in order to properly simulate displacements observed in instrumentation data. High-quality instrumentation data is the key to post-peak rock mass parameter calibration. The procedures outlined in the paper highlight the need for a new hybrid numerical modelling package that can use the influence of three-dimensional mining-induced stresses to predict displacements in, and potential failure of, rock masses surrounding mining infrastructure in order to radically alter strategic and tactical mine design.

Jan 1, 2007

By M. Somppi, Z. Yamak

"Gold producers invest significant effort in mining, processing, and creating an intermediate gold doré product. Nonetheless, equal effort should be extended to the final handling and processing of the doré bar, and managing the high-purity gold produced at the fine-gold toll refiner. This detailed attention to bullion handling and refining provides rigor and confidence that the mine site is achieving, through fair and controlled methodology, the most appropriate value for the final product. With the above in mind, the following study explores the importance of preparing a set of site best-practices for bullion handling and specifically, detailing the peculiarities of sampling methodologies and the impact on assays.INTRODUCTION Gold and silver handling practices are common place at mine sites and refineries. The practices include but are not limited to smelting, ingot casting, weighing practices, and secure transportation. Proper handling and processing of the bullion material ensures that the mine site is achieving the true value of the final product. Various handling aspects can critically impact the perceived value of the bullion. A few of these particulars include weight tracking, scale recertification and calibration, refining and melting practices, melt temperature measurement, sampling, pouring, bar cleaning, furnace technology and crucible selection, and assaying. Nevertheless, this report discusses and focuses on the importance of proper sampling and molten-metal temperature measurement and their potential impact on the final doré bar value. Refining or re-melting operations achieve a proper measure of the precious metal content of its bullion when the sample accurately represents the whole bar. At first this task appears seemly straightforward, however, taking a representative sample can be challenging and is also one of the most important tasks for valuing gold during the settlement stage at the precious metal refinery. Various bullion sampling methodologies exist; including: dip sampling, granulation, drilling, cutting, and vacuum pin sampling. The Royal Canadian Mint (2009) indicated in their technical review of refinery operations that pin sampling is one of the best methods for cases where representative sampling and accuracy are required, e.g. to determine the payable metal content. Pin sampling consists of inserting a sealed glass vacuum tube (Figure 1) into the molten metal; when the molten metal contacts a purposely-designed weak portion of the glass, the seal breaks and the metal is suctioned into the hollow centre (Figure 2)."

Jan 1, 2018

By B. A. Monkman

"IntroductionONE OF :THE most effective methods by which the construction industry is combatting mounting building costs is by making increased use of lightweight materials, thus reducing the dead load to be carried •by structures. This applies to non-metallic materials as well as to metallic ones, and particular attention has been given to developing lightweight aggregates for use in concrete.The use of lightweight aggregates is not new and, in fact, dates back to the Roman Empire, when pumice was used in the walls and domes of the Roman buildings. More recently, and up to a decade or so ago, the demand for these aggregates was met from deposits of volcanic cinders, pumice, scoria, etc., and from the by-products of blast furnaces and coal burning boilers. However, these sources of supply are no longer sufficient to meet the demand, for transportation costs pretty well restrict the use of the natural lightweight aggregates to the western cordillera regions where the deposits of these materials occur, and the use of expanded slag aggregates to the areas neighbouring the plants where slags are produced. As for cinders, the supply has been greatly reduced by the conversion of industry to fuel oil, natural gas, and powdered coal, and the large stockpiles which existed previously have been pretty well exhausted.Industry's approach to the problem of a decreasing supply, in the face of an increasing demand, has been characteristically direct. The solution has been to construct plants whose sole .purpose is to produce economically an acceptable light-weight aggregate from materials close at hand."

Jan 1, 1955

By Zhang Junzhi

This paper relates cross-border mergers and acquisitions (M&A) risk management theory to actual coal enterprises in China. The 3 phases of M&A are preparation, implementation and integration. By using the Analytic Hierarchy Process and fuzzy evaluation methods, we will try to establish a model to assess risks of the cross-border M&A of China?s coal enterprises. We then apply this model to the case of Yankuang Group acquisition of the Felix Company and receive the assessment results. There are significant reasons for quantitative research on risks of cross-border M&A of China?s coal enterprises, such as effective prevention and risk-aversion, and facilitation of cross-border M&As.

Aug 1, 2013

By F. Habashi

"While bioleaching of pyrite concentrates has been successfully used in industry to liberate gold from the sulphide matrix for subsequent cyanidation, the same technology cannot be recommended for leaching chalcopyrite concentrates for copper recovery. It will be shown to be uneconomical and cannot compete with pressure leaching technology. Data on the pilot plants that were constructed for this purpose and were shut down will be given.INTRODUCTIONBacterial leaching has been successfully applied for heap leaching of low-grade copper ores (Habashi, 1978, 1999). One of the major operations is that at Bingham in Utah (Figure 1). The leach solution collected at the bottom of the heap is extracted by organic solvents and the strip solution is electrolyzed to get high purity copper. The process was extended to treat auriferous pyrite concentrates to liberate gold and render it amenable to cyanidation by a process known as BIOX (Marsden & House, 2006; Lunt & Briggs, 2005).BIOX plants currently or recently in operation are the following:??Ashanti Goldfields Company, Ghana. Designed with an initial capacity of treating 720 tonnes of concentrate per day, the Sansu plant has since been expanded and currently has four modules processing 960 tonnes per day in all. It is by far the largest biooxidation plant in the world. The capital cost of the plant totalled US $25 million (1994 terms) and the operating cost is currently US $17/tonne milled.??Fairview, South Africa. The plant at the Fairview mine in Barberton, which was the initial pilot plant, has been fully operational since 1986. It was originally designed to treat 10 tonnes/day of concentrate but with the success of the project this has been increased to 55 tonnes per day. With the purchase of Fairview by Avgold’s Eastern Transvaal Consolidated, Avgold concluded a licensing agreement with Gold Fields, formerly known as Gencor, entitling it to use the BIOX technology to treat itsconcentrate.??Saõ Bento, Brazil. A BIOX plant was recently in operation in Brazil at the Saõ Bento Mine where a pressure oxidation circuit is used to treat the refractory flotation concentrate. This plant has confirmed the viability of combining bio-oxidation with pressure oxidation as a cost-effective method ofincreasing capacity at an existing oxidation plant.??Wiluna, Australia. The plant at Wiluna Gold Mine, Western Australia, was commissioned in 1993. Although originally designed to treat 115 tonnes per day of concentrate this has subsequently been increased to 158.??Other plants at Tamboraque in Peru, Harbour Lights and at Youanami in Australia have been commissioned recently."

Jan 1, 2012

By T. Patching

"THE FOLLOWING notes on coal mining in the Edmonton city area are based, in the main, on scattered reports and accounts as little coal mining has been done in this area for about 20 years and few people are left who were involved in what was at one time an important industry of northern Alberta. Although coal mining is not likely to be permitted in the city area itself in the future, a record of this work is warranted to indicate the ·conditions and problems that may be encountered if underground mining again is proposed in the district in the same geological formations and in similar strata. Coal mining in the Edmonton area developed with the influx of settlers in the latter part of the nineteenth century and the first part of the present century. Probably local coal was used by the Fort's blacksmith as early as 1841, and the early settlers probably were 'gopherholing' into the outcrops along the river banks by the 1870s. The first report of commercial coal mining was in 1880 when a contract was let by the Hudson's Bay Company for the provision of 300 tons. As the population in the city and northern parts of the province grew, many new mines were opened along the river and in the district, and coal was even shipped by barge to points in Saskatchewan(1 ,2) By 1909 the Department of Public Works reported that 'Edmonton stands as the second largest domestic coal producing centre in the province'. It continued to hold this position until 1942. From about 1912 to 1951 annual production from mines in the city and surrounding district ranged between 0.38 and 0.65 million tons, depending on weather, wars and strikes. Production began to decline in 1951 because of the increasing availability and consumption of natural gas which was piped into the city and then provided to other towns and rural areas in the northern part of the province. Taylor noted that between 1880 and March 1970, when the last mine within the city area closed, the total of mines and prospects within the Edmonton city area rose to 153. Most of them were small; not more than 20 produced more than a quarter of a million tonnes during their entire life, and only three produced a million tonnes or more. As described by Taylor ""within the city district workings extend discontinuously from the apex of a narrow triangle near Groat Bridge to the base of the triangle in the Clover Bar area"". The larger mines were in this latter area. Approximate locations of the old mine workings in the city are shown in Taylor's atlas. A number of other coal mines were worked in the Rabbit Hill, Big Island, St. Albert, Namao, Cardiff and Morinville districts around the city."

Jan 1, 1985

By Matthew R. Ward

This paper aims to describe the reasons and methods to extend enterprise networks into underground mines. Currently mines use a number of communication networks for telephones, PLCs, two-way VHF radio and computer networking. Each system can have different wiring, protocols, converters and interfaces all which require expansion and maintenance. The convergence of voice, video and data using Ethernet and TCP/IP has the very real benefit of one ?wire? for underground networks. Now that the majority of underground equipment can communicate using TCP/IP, network convergence can offer reduced network expansion and maintenance costs. Cost savings are good, but the truly exciting aspect of network convergence using Ethernet is the low-cost, high speed wireless networking now available . These wireless networks offer an opportunity to facilitate mining automation even on a small budget. How would mine operators change they way they operate if they could gather vehicle location and data in real time? What about controlling equipment remotely? The list of applications is long and includes traffic control, dispatching, real-time ore blending, tele-operation, automated production reporting, vehicle health monitoring, elimination of paper forms and immediate network access for surveyors and geologists. An ideal converged network for underground mining would be robust, inexpensive, easy to expand, enable fast and secure connections while keeping voice communication performance equivalent or better than what is now provided by VHF radio

Apr 1, 2005

By A. Aubin, H. Yang, G. Zaluski

The Athabasca Basin of northern Saskatchewan and Alberta is an exceptionally rich metallogenic region, hosting more than 2.8 B lb U3O8, of which over 927 M lb U3O8 have been mined out since extraction first started in the late 1970’s. A detailed compilation of several empirical features of 85 deposits located within the basin was conducted in order to understand the distribution and variability of the geological characteristics of the mineralization and its associated alteration. A new empirical classification was devised based on four parameters: 1) geometry of the mineralization (dimensions and relation to the unconformity surface), 2) size, grade and metallurgical complexity of the mineralization, 3) lithostructural setting, and 4) extent and nature of associated alteration haloes. This compilation defines the footprint characteristics of the Athabasca Basin deposits, which guides decision-making processes from early exploration and discovery to resource expansion and extraction.

Jan 1, 2020

By Morgan Schauerte, Laura Raimondi, Mariel Palomeque

Executives in the mining industry are facing dramatically changing market expectations on reporting and transparency regarding the environmental and social impacts of projects, supply chains and products. Companies increasingly need to disclose the governance procedures they have in place to ensure communities, investors, employees, and Indigenous partners are effectively managing social and environmental risks. These disclosure requirements begin during exploration and carry through to all stages along the project life cycle. This type of environmental, social and governance (ESG) disclosure is referred to as ESG performance by the investment community. ESG is not a new concept, and it builds on and is intertwined with many concepts such as corporate sustainability, corporate social responsibility, eco-efficiency, triple bottom line thinking, life cycle management and many others. This paper will explore how mining companies can develop a credible ESG governance approach and strategy that will reduce risk, open opportunities, and create value. This paper will summarise ESG trends and drivers, discuss the economics and investors’ perspective towards ESG, and outline leading ESG standards and guidelines of interest to investors, regulators, communities and other stakeholders. Linkage of ESG to global sustainability efforts such the United Nations Sustainable Development Goals and Global Compact will also be addressed.

Jan 1, 2023

By Robert M. Vadas

Special considerations are described as they apply to the design of ring gears for high-power grinding mills. AGMA requirements, the importance of the supporting structure, material selection and related field experience are discussed, with special emphasis on available and developing manufacturing technologies.

Jan 1, 1978

By D. M. Morrison

"Microseismic systems at five mines in the Sudbury Basin provide the basic data for Falconbridge Limited's rockburst research. Daily and long-term analysis of this data as well as underground observations has confirmed the fault-slip mechanism of rock bursting at three mines. A detailed analysis of the complete history of Falconbridge Mine is being conducted and Distinct Element numerical models are being used to simulate both the stick-slip behaviour of faults and the dynamic effects of the induced vibrations on rock and backfill. University research includes acoustic tomographic imaging of the rock mass based on seismic wave propagation and collection of full micro seismic waveforms to allow application of advanced seismic and statistical analysis techniques. INTRODUCTIONFalconbridge Limited currently has five mines operating in the Sudbury Basin: East, Lockerby, Onaping, Fraser, and Strathcona Mines, which along with the Falconbridge open pit produced 2.8 million tonnes of ore in 1986. The underground mines range from about 600 m to 2000 m below surface and one of the consequences of mining at these depths is the occurrence of rockbursts.Research into rockburst phenomena at Falconbridge began over 25 years ago and research is continuing in an effort to avoid the problem by improved mine design, to protect mine openings from damage by design of effective support systems and to better understand the processes which precede a major fault slip rockburst. Since the early 1980s, significant progress has been made due principally to micro seismic monitoring and advances in microcomputer technology coupled with detailed underground investigations.It is now possible to identify the fault-slip mechanism as the cause of many of the rockbursts which occur at Falconbridge mines. By gaining an understanding of effect of mining-induced stresses on the pre-existing geological structures, areas which may experience rock bursting can be identified and can be protected against severe damage by appropriate support techniques."

Jan 1, 1989