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By B. Burger, T. Bester, S. Deonarain, L. S. Schultz

"This paper details the process followed to raise drill and equip a 6.1 metre diameter vertical service shaft at Glencore’s Mindola Deeps project in Kitwe, Copperbelt Province, Zambia. The project scope comprises a shaft collar, bulk air intake, a pre-sink to -90 metres and raise drilling the shaft from surface to a final depth of 1,892 metres underground, in four separate lifts of approximately 475 metres each. Equipping of the shaft steelwork, headframe erection and commissioning the shaft for hoisting. In addition, the scope included the development of a decline down from 5430’ level underground to the new shaft position on 6205’ level. This paper will provide some insight into the successes and challenges encountered during execution of the shaft works to date and provide some learnings for future projects of a similar nature. INTRODUCTION The Mindola Mine is situated to the west of the city of Kitwe in the Copperbelt Province of the Republic of Zambia (Figure 1). The mine is owned and operated by Mopani Copper Mines Plc (MCM), whose shareholders are Glencore AG (73.1%), First Quantum (17.9%) and ZCCM Holdings Plc (10%).Productivity at the Mindola mine has been adversely affected because of significant ventilation and ore re-handling challenges, which are caused by the dilapidated infrastructure, and design of the existing vertical and sub vertical shaft system. In the circumstances, it was apparent that it was necessary to sink a new vertical shaft that would increase the volume of fresh air down the mine, improving the underground working environment and the current hoisting restrictions, resulting in an increase in productivity and efficiency. Because there were two existing levels ideally situated and perpendicular to one another and because a third level was in close proximity to that perpendicular and because the mine required a ramp down to shaft bottom in any event, consideration was given to raise drilling the shaft as opposed to using conventional blind sinking methodologies."

Jan 1, 2019

By A. G. Beer

The evolution of microstructure is examined during the annealing of hot worked magnesium alloy AZ31. The influences of deformation and annealing conditions on the developed microstructures are assessed. It is found that annealing at a low temperature (300 °C), after deformation at a low temperature and strain rate (300 °C and 0.001 5-1 respectively), results in the development of abnormally large grains. With increasing values of Z (lower temperatures, higher strain rates), static recrystallization of the dynamically recrystallised structure takes place; smaller annealed grain sizes are attained and the time at which coarsening begins is reduced. Whilst both the deformation and annealing conditions influence the time it takes to reach a stable annealed microstructure, the grain size attained is governed solely by the prior deformation conditions employed.

Jan 1, 2006

Microseismic (MS) methods offer one of the few ways to monitor a 3D volume of rock and essentially see into the rockmass and the regions of real time rock fracture. This is a critical component when considering workplace safety as well as the economic viability of a mining operation. New Gold Inc. New Afton Mine, an intermediate copper-gold mining company located 350km northeast of Vancouver in the south-central interior of British Columbia, Canada, has recently installed a MS system to help understand the block caving process in space and time. For a block cave mining operation is it important to utilize the MS events to map out the seismogenic zone related to the regions of stress concentration and fracturing mechanisms which lead to caving. The geological setting within the local array is complex, consisting of several distinct lithologies with unique material properties that each affect the microseismic signal differently. The block cave consists of a muck filled void, also affecting the seismic waveform path. This paper compares the use of a single velocity model to a variable velocity model which accounts for the differing lithologies and cave. The variable velocity method determined 3D raypaths for all source to receiver possibilities through five irregular shaped geological domains and the estimated cave. For calibration blast data, the variable velocity model is found to successfully decrease the error for event location from an average of 38m to 20m (47% improvement), and its importance to location accuracy is expected to increase as the cave develops in size.

Aug 1, 2013

By Kurt Tischler

This paper presents the field experience of Siemens with regard to Gearless Drives in the mining industry ? We consider the elapsed production hours of Siemens Gearless Drives to be extensive enough to provide a reliable estimation of availability calculated on the basis of data representing repair time, downtime, and operating time. The users of Siemens Gearless Drives confirm an availability of more than 98% after exclusion of some major issues. The paper addresses all of these major issues of Siemens Gearless Drives, describes successfully applied corrective measures, explains the influences on the design of the drives, and lists the downtimes associated with each of these issues.

Jan 1, 2012

By J. Janeson

Wall control at the Pipe Open Pit is of primary importance in ensuring the long-term stability of the operation, while keeping costs to a minimum. Blasting techniques have been adapted to the variations in competence and structure of the wall rocks. A portion of the perimeter wall is being developed in incompetent peridotite . A recent change in pit slope design provides a wide safety berm on alternate benches. A support program which consists of pinning the crests of wide berms with vertical reinforced concrete dowels and horizontal bolting of walls shows evidence of increasing the stability of the pit walls. This paper describes the blasting and support techniques which are contributing to successful wall control in the Pipe operation.

Jan 1, 1979

By M. H. Allan

"This paper presents the geographic and geological setting of Saskatchewan Power Corporation's Poplar River Mine in south-central Saskatchewan, about 8 miles from the U.S. border. Generally the mine, which is being expanded to four million tons per year, is in an extremely disturbed geological area with severe dewatering problems. The lignite coal, which is strip mined, is supplied directly to an electric power generating station by means of a 7-mile unit-train private railroad.A number of unique reclamation and socio-economic problems were encountered because of the proximity to the U.S. border and because of the lack of experience of the regulatory authorities in projects of this kind. These are described in some detail, as well as the performance of one of the largest draglines in Canada. IntroductionThe Saskatchewan Power Corporation is a publicly owned utility which has the franchise to supply electricity and natural gas to all customers within the boundaries of Saskatchewan.Saskatchewan is a province which can almost be divided in two: the populated southern portion, principally devoted to farming, and the northern portion which is mostly on the Precambrian Shield and consists of lakes, rocks and muskeg. This portion is largely uninhabited except for a number of small villages. However, in the last few years there has been considerable mineral exploration and development, notably for uranium. This has helped considerably in the diversification of the basic agricultural economy of the province.Saskatchewan consists of 251,700 square miles, 761 miles north to south and an average of 335 miles east to west. It has a population of approximately 960,000, giving a population density of four persons per square mile. The Saskatchewan Power Corporation supplies 357,249 electrical arid 221,378 natural gas customers."

Jan 1, 1982

By J. Ran

"Hangingwall sloughing is the major cause of unplanned stope dilution in open stope mining. Understanding the hangingwall sloughing mechanism can guide the stope design in minimizing the unplanned dilution and improving muck size and therefore mining efficiency. Though the modified stability graph method may be adopted to assess the hangingwall stability, for mines where the hangingwall is inaccessible, the required parameters are difficult to define and some of the simple influential factors cannot be easily identified in this method to provide guidelines for stope design.This paper identifies the main modes of hangingwall sloughing in open stope mining based on detailed data collected from mined-out stopes and site observations, applies the voussoir beam notation to analysis of the hangingwall sloughing mechanism, compares the model analysis results with the collected stope data, and provides guidelines for stope design and model application. Finally, examples are given to demonstrate the time and support effects on hangingwall sloughing and stope dilution."

Jan 1, 2002

By T. Xue, A. Singhal, D. Wrana, I. Mihaylov

"At Vale's Thompson Nickel Refinery, the copper and arsenic in the nickel electrolyte are removed by precipitation using H2S, generating a sulphide precipitate containing about 40% Cu, 8% Ni, 2 to 4% As and 30% S. This residue has been typically stored in impoundment ponds within the plant site. Various options for reprocessing it have been investigated over the years. One of the options involved oxidative pressure acid leach, whereby over 95% Cu, Ni and As were extracted. More recently, an atmospheric alkaline sulphide leaching process for selective removal of 70 to 90% As was developed and mini-plant tested. After alkaline sulphide leaching, the dissolved arsenic is precipitated as stable basic ferric arsenate (BFA) with the addition of ferric sulfate, while the low-arsenic Cu/Ni sulfide is suitable for processing in Vale's operations elsewhere in Canada.INTRODUCTIONVale’s Thompson Nickel Refinery was commissioned in 1961 and currently it has the capacity to produce about 56,700 tonnes per year of electrolytic nickel as cathode slab and rounds products. A sulphate and chloride mixed electrolyte is used in the Thompson refining process and it typically contains 75 to 85 g/L Ni, 50 to 60 g/L Cl, 90 to 120 g/L SO4 2-, 25 to 30 g/L Na and 8 to 9 g/L boric acid. The main impurities in the Thompson anolyte are copper, cobalt, arsenic, iron and lead.The simplified Thompson electrolyte purification flowsheet is shown in Figure 1 (Oliver & Wrana, 2009, Goble & Chapman, 1986); it consists of precipitation of copper, arsenic and lead with H2S, followed by nickel replenishment with ground matte and acid and removal of cobalt and iron with Cl2 and NiCO3."

Jan 1, 2012

By R. Hamilton

"Louvicourt mine began operation in 1994. It is located in northwestern Quebec, 20 km east of Val d’Or. The mine is owned by Aur Resources (30%), which operates the mine, Teck/Cominco (25%) and Novicourt (45%). By the end of 2002 there were approximately 280 employees working on the site, including contractors. Production averages 4300 tons per day, working a massive sulphide body located between 415 m and 920 m underground.Maintenance expenses represent 27% to 29% of the operating costs, and the maintenance personnel represents 34% of the total workforce (including electrical, mechanical and concentrator maintenance staff). Considering these figures, in addition to capital costs and indirect costs, such as energy (electricity, fuel, gas, etc.), it is worthwhile to pay attention to how things are done in order to protect such investment. Every task performed to help understand the impact of Louvicourt’s practices must to be seen as an investment in the reliability of its operation."

Jan 1, 2003

By C. Ayora

The Iberian Pyrite Belt (SW Spain and Portugal) contains one of the largest reserves of pyrite in the world with mining activities dating back to prehistoric times. About one hundred abandoned mine wastes and galleries release a huge acidity and metal load to the Tinto and Odiel rivers. Once the mining activity is over, polluting discharges can persists for decades or even centuries with no specific responsible entity. In-situ passive remediation technologies are especially suitable for these orphan sites. The concept is to insert a reactive porous material in the natural flow path of contaminated surface and ground waters, and it is implemented through infiltration ponds and reactive barriers, respectively. Calcium carbonate pea-size gravel is the common alkalinity supplier to neutralize acidity and precipitate metals. These remediation systems have been traditionally implemented in coal mines. However, the acid drainages from the Iberian Pyrite Belt contain metal concentrations one to two orders of magnitude higher than those from coal mines and require special designs to avoid quick clogging or passivation (coating) of the grains of reactive material. To overcome these problems, a Dispersed Alkaline Substrate (DAS) mixed from fine-grained limestone sand and a coarse inert matrix (e.g. wood chips) was developed. The small grains provide a large reactive surface and dissolve almost completely before the growing layer of precipitates passivates the substrate. The high porosity and the dispersion of nuclei for precipitation on the inert surfaces retard clogging. However, limestone dissolution only raises pH to values around 6.5, which is sufficient to precipitate the hydroxides of trivalent metals (Al, Fe), but it is not alkaline enough to remove divalent metals. Magnesium oxide, which hydrates to Mg hydroxide upon contact with water, buffers the solution pH between 8.5 and 10. A DAS system replacing limestone with caustic magnesium oxide has been tested to be very efficient to remove divalent metals (Zn, Cd, Mn, Cu, Co, Ni, Pb) from drainage previously treated with limestone.

Aug 1, 2013

By S. Lun Sin

In this study, the effect of silicon on the microstructure, mechanical properties and hot tearing susceptibility of permanent mould cast AZ91E magnesium alloy was investigated. Varying amounts of silicon (0.5, 1.0 and 1.5 wt.%) were added to AZ91E in the form of an Al-53 wt.% Si master alloy. The phase formation, grain size and solidification behavior of each alloy were characterized and related to their tensile properties and hot tearing susceptibility. The results showed that the addition of silicon resulted in the formation of Mg2Si particles. The presence of these particles led to an increase of the hardness, but was detrimental to the tensile strength and elongation of AZ91E. However, silicon significantly reduced the hot tearing susceptibility of AZ91E. This was attributed to the reduction of the grain size and the decreased freezing range of AZ91E, which contributed to improve the interdendritic feeding during the last stage of solidification.

Jan 1, 2011

By J. Awmack, M. A. Tomlinson, P. J. Lind

"Peñasquito is a complex polymetallic deposit containing gold, silver, lead, zinc, and copper and is one of the largest producers of gold in Mexico. Mining activity is currently transitioning to a second open pit, Chile Colorado, which will be mined concurrently with the existing open pit, Peñasco. The ore bodies are located within diatreme pipes and into the surrounding sediment formation. In the coming years, mining will be carried out in more sedimentary zones, which are significantly higher in organic carbon content. Organic carbon in the feed influences both flotation and leaching operations. Several changes are being implemented to the Peñasquito flowsheet to mitigate the effects of increased organic carbon in the plant feed. These include the use of alternate reagent schemes, construction of a carbon pre-flotation circuit, implementation of a pre-leach flotation circuit ahead of pyrite leach, and evaluation of a tertiary process for separation of carbon and precious metal minerals.INTRODUCTION Goldcorp’s Peñasquito operation is located in the Mexican state of Zacatecas, approximately 200 km from the city of Zacatecas in the Mazapil municipality (Figure 1). Peñasquito has been in operation since 2009, with mining carried out by open-pit methods. Oxide ore has been processed in a heap leach facility and sulfide ore is treated in the sulfide processing plant. The processing capacity of the sulfide plant is 130,000 tonnes of ore per day and in 2016 production amounted to 465,000 ounces of gold, 17.6 million ounces of silver, 109 million lb of contained lead in lead concentrate, and 263 million lb of contained zinc in zinc concentrate (Goldcorp Inc., 2017). To recover more of the contained gold and silver and to mitigate the impact of increasing organic carbon content in the ore, a number of significant changes are being made to the operation."

Jan 1, 2018

By J. F. Wright

Introduction Previous to 1924 the mining fields of Manitoba and adjoining territory had not been prospected in detail, and the reports of the exploration of the mineral discoveries to that date had been discouraging. As a result of the apparent failure of all the mining operations, some considered that geological conditions in the country westward from lake Superior extending across western Ontario, eastern and northern Manitoba, and northern Saskatchewan, were different from those in the northeastern part of Ontario, where large gold mines had been developed. Discoveries of importance thus were necessary to renew interest in the mining possibilities of this part of the Canadian Shield, and the successful operations at Flin Flon and Howey in large part were responsible for the beginning of the present activity in what may be described as the part of the pre-Cambrian Shield within central Canada. In Manitoba, the more important developments at present are in the Central Manitoba, Gods Lake, and Knee Lake fields. The large area from west of Flin Flon east to Herb Lake, also, is being explored carefully for gold deposits of merit. A number of properties in Red Lake, Woman Lake, and Pickle Crow areas are being drilled and explored underground. Many of the mines of the Lake of the Woods area, that were producing gold 30 years ago, are re-opened, and new prospects in this field and in the country to the east are being explored. The recent development of Little Long Lac mine in an area near the railway, and considered by some to have been thoroughly prospected years ago, has stimulated interest in the areas formerly prospected. In the autumn of 1934, the belts of greenstone and sediments in the country east of lake Nipigon were staked, and deposits in these fields will be explored in detail this year. This paper is presented to discuss the general features of the geology and gold deposits of the various prospecting fields in Manitoba and adjoining territory. Details of a number of the areas and mines will be presented at this meeting in papers by Barton on Little Long Lac, Tanton on Sturgeon River, Baker on Gods Lake, and Brownell and Kinkel on Flin Flon. Although mining was not active in most of this territory previous to 1930, geologists of the various government departments continued field studies and interesting reports were issued.

Jan 1, 1935

By Michael J. Beus

The National Institute of Occupational Safety and Health-Spokane Research Laboratory (NIOSH-SRL) have developed a Shaft Conveyance Monitoring System (SCMS). Assessment of current hoisting technology has shown that monitoring wire rope tension and conveyance position and load directly from the skip or cage top offers several significant safety, production, and maintenance advantages. The SCMS consists of conveyance position and guide displacement sensors, a battery power supply and charging system, and a new sensor to measure hoist rope tension. This device provides a warning of the occurrence of ?slack rope? a particularly dangerous condition. A 2.4 GHz radio link transmits data to the hoistroom. A reduced scale hoisting test facility has been constructed to test these components prior to field trials. The advantages of monitoring wire rope tension and conveyance position and load directly from a skip or cage top will be discussed. Field tests are underway in full-size shafts to refine the concept and evaluate long-term reliability and maintenance requirements. Application of this technology may result in decreased maintenance costs as well as safer, more productive hoisting operations.

May 1, 2001

By P. Pal Roy, R. B. Singh

"This paper focuses on a number of interesting results to establish the theory and principle of air-deck blasting. It also gives the mechanism of breakage that takes place in air-deck blasting under varying charge load conditions. With these aspects in mind, the mine management can implement this up-coming technology to enhance safety and higher productivity. IntroductionThe method of air-decking has become an increasingly popular technique in production and presplit blasting. In the blasthole, an explosive column is combined with an airchamber. The main aim of the technique is to control breakage through effective distribution of explosive energy and thereby enhance uniform rock fragmentation. An air column lowers the initial pressure of the explosive products and simultaneously increases the time of interaction for the detonation front with the surrounding rock, which enhances rock breakage.To study air-deck blasting, CMRI initially conducted experiments using indigenously developed, low-cost wooden spacers of different sizes and strengths. Air-deck blasting was first tried using these spacers in 1993 at Jambad OCP, ECL and Chasnalla OCP, IISCO. The experiments were extended in 1994 at Bermo Mine, DVC. The results were subsequently published by Pal Roy et al., in 1995. It is worth mentioning that the performance of air-deck blasting during this period was only compared with conventional blasting practices without going into detail of the theory behind the process."

Jan 1, 2001

By R Zavadil, S Kuyucak, F Fazeli

Proton exchange membrane (PEM) fuel cells generate electricity by reacting hydrogen and oxygen. A thin, bipolar electrode material provides a medium for electron exchange with the electrolyte, alternately serving as anode at the hydrogen-rich side and cathode at the oxygen-rich side. Stainless steels have sufficient corrosion resistance to qualify as bipolar plate materials. However, the protective chromite layer increases the contact resistance, the battery’s internal resistance; and thus, decreases the electrical efficiency of the fuel cell. A heat-treatment is proposed and investigated via simulation by ThermoCalc / Dictra and experimentally, to generate a sufficient quantity of conducting surface carbides that breach the protective layer. Once carbide growth is arrested, a subsequent heat-treatment is also needed at a higher temperature to restore the corrosion resistance by filling-in the Cr-depleted layer (sensitization) around the carbide particles.

Jan 1, 2014

By R. H. Beaton

"About 1905, a plant was constructed at C1ayburn, in the Lower Fraser valley, 4'5 miles east of Vancouver, to process shales from Sumas mountain into heavy clay products. In time, mining operations were found to be more favourable on the opposite side of the mountain, and by 1913 a plant, which soon became the centre of activities, was completed at Kilgard. Destroyed by fire in 1949, the plant was rebuilt on modern lines, and a second plant was established at Abbotsford, six miles to the west. The Company, from its beginning, has grown with development of the Province. In recent years, operations have kept abreast of latest developments, particularly in materials handling. Latest innovation has been the complete conversion of fuel from Bunker C oil to natural gas. In 1957 the Company became associated with Harbison Walker Refractories, Limited, a leader in its field in the United States, and its title was changed from Clayburn Company, Limited, to Clayburn-Harbison, Limited. Currently, the Kilgard plant produces sewer pipe, agricultural tile, and flue liner; the Abbotsford plant, refractories and facebrick. Improvement of products and development of new ones are tasks of a recently-completed testing and research laboratory.Almost all ware produced is marketed in Western Canada or Washing-ton State. The Vancouver area absorbs the bulk of structural clay products."

Jan 1, 1959

By L. Shang

In conventional continuous hot rolling processes, metals are usually reheated to a temperature such that the workpiece will maintain appropriate hot working characteristics as it proceeds through the rolling mill, assuming that the temperature is continually decreasing. Metallurgically, reheating will reduce micro-segregation in the as-cast material, may increase the as-cast grain size and will affect any second phase particles present in the as-cast structure. All these changes can affect the hot working characteristics, and the final as-hot rolled microstructure. In order to study the effect of reheating on AZ31 magnesium alloy, a plate sample was cast in a water cooled copper mould and a series of compression tests was performed at a temperature of 350 °C, strain rate 0.01 5-1, and strains from 0.2 to 1.0, after different reheating schedules. It was found that there is no significant difference in flow behavior between the as-cast sample and all but one of the reheated ones. The reheat treatment of the 'anomalous' sample was a two stage heat treatment; it was first reheated to 450 °C, cooled to room temperature, then reheated to 350 °C. The effect on the flow curve was to increase the flow stress. This result may be related to changes in second phase particle characteristics.

Jan 1, 2006

By Yan Yang

The Jinfeng gold mine is one of the three gold mines that Eldorado Gold has in China and it is the second largest gold mine in China. The mine is located in a relatively remote and mountainous area in the southwestern Guizhou province. The orebody is similar to the Carlin type deposit in Nevada. The mill throughput was designed to treat 3,600 tones per day. The ore comes from open pit mining and underground mining, and is fed to one-stage jaw crushing. The crushed ore is stockpiled, reclaimed and then fed to the SABC grinding circuit. After classification with hydrocylones, the ore is floated, and the resultant concentrate is oxidized biologically in a process known as BIOX®. The oxidized concentrate is then washed in a CCD circuit and finally leached with cyanide in a CIL circuit for gold extraction. Jinfeng produces about 180,000 oz of gold per year. This paper introduces operations and modifications of SABC circuit over the past three years, and then describes some technical characteristic of the SAG mill and other circuits in the processing plant. Major modifications and improvements on the SABC circuit are described in the paper, including: 1. Impacts of grinding ball and mill liner with respect to material selection, quality, hardness, manufacturing methods, and interactions between mill liner and grinding ball. 2. Effect of milling operation parameters on milling efficiency. 3. Impacts of SAG mill scats and modifications of grate size to improve mill throughput. 4. Design and construction of a pebble crushing system, and recycle the crushed scats to the SAG mill to improve mill throughput. With the above-mentioned modifications, 20% increase over the design in mill throughput has been realized over the past three years, and operating cost has been significantly reduced. However, some issues still remain, and thus process modifications and technical innovations are still needed.

Jan 1, 2012

By Shuan-cheng Gu

Roof bed separation often occurred due to the deformation incoordination of surrounding rock following the excavation of mine roadway. Bed separation has effect on the bolts, and the estimation of the influence will directly affect the safety of support systems. In this paper, the hyperbolic function model to analyze the load transfer mechanism on the bolts was simplified as the exponential function form for easy calculation. An elastic-plastic analysis model of the bolt loading occurred by the bed separation was established. And the development low that the bed separation affected to the bolt loading was discussed. According to the parameters analysis of different separation values and locations, the influence law of the bolt loading caused by roof bed separation was summarized. Finally, the effects of bed separation were considered for the bolting design, it was able to provide a reference to the anchorage design of stratified rock.

Aug 1, 2013