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By K. E. Waters, J. E. Nesset, F. Rosenblum, J. A. Finch, S. Moon

"Some materials when exposed to various conditions can exhibit a rise in temperature without requiring an external heat source. Generally referred to as pyrophoric or self-heating substances, they challenge the safety of materials handling, storage and transportation. Reliably assessing the self-heating potential of materials is thus essential. Over the years a number of test protocols have been developed. A widely accepted method is that recommended by the United Nations to certify the safety of shipping pyrophoric goods. Our test work on sulphide materials has shown that the U.N. test can give false negatives if the sample oxidation history is not considered. Depending on the degree of oxidation (“weathering”), the same sulphide material can exhibit self-heating ranging from safe to hazardous. For concentrates, oxidation can occur during storage and transport making the sample weathering history an important consideration in the test work. To make the U.N. test, and other single-stage self-heating procedures, more reliable in assessing self-heating potential when testing sulphide materials, it is suggested that a weathering step be incorporated in the test protocol. This test work for two sulphide samples, an ore and a concentrate, demonstrates the impact of incorporating a weathering stage in the test protocol. INTRODUCTIONSelf-heating occurs when exothermic reactions produce heat faster than can be dissipated to the surroundings. Numerous substances self-heat, ranging from wood chips and powdered milk to coal and sulphide minerals (Beever & Crowhurst, 1989; Hudak, 2002). Mixtures of sulphide minerals, most notably those containing the iron sulphide pyrrhotite (Fe(1-x)S), commonly encountered in the extraction of base metals (e.g., copper, zinc, lead, and nickel), are particularly prone to self-heating (Rosenblum, Nesset, & Spira, 2001; Payant, Rosenblum, Nesset, & Finch, 2012). In the mining and subsequent processing stages, the minerals are progressively liberated and finely ground, then separated, usually by flotation, with the resulting concentrates stored and transported to smelters for metal extraction. At most of these stages the sulphides are exposed to both moisture and oxygen, conditions that promote partial sulphide oxidation and the formation of elemental sulphur. Studies have shown that pyrrhotite, in particular, readily oxidizes to form elemental sulphur (Bernier & Li, 2003; Belzile, Chen, Cai, & Li, 2004; Somot & Finch, 2010). The elemental sulphur becomes fuel for further self-heating as the temperature of the mineral mixture increases above 100 oC (Rosenblum & Spira, 1995; Somot & Finch, 2010). It is believed the propensity of pyrrhotite to self-heat is a result of its iron-deficient, and hence somewhat unstable structure. It is worth noting that pure metal sulphides (with the exception of pyrrhotite) do not exhibit appreciable self-heating. A mixture of minerals sufficiently different in their electrochemical rest potential is required to initiate self-heating at ambient temperatures (Payant et al., 2012)."

Jan 1, 2016

By Ian S. Leslie

Seismic monitoring systems for mining operations are being utilized more than ever before in the characterization of rock mass response to underground and open pit mining. This paper provides a review of the use of microseismic monitoring for rock mechanics applications at mines throughout the world. Some practical considerations for the installation of these systems are presented along with techniques for optimizing seismic array coverage. Case studies and installation examples are also provided. Recent applications of advanced seismic analysis techniques are discussed including the determination of event mechanisms, mapping of maximum peak particle velocity (PPV) and seismic hazard fields, and the use of source parameter data for large event re-entry protocol.

Jun 1, 2012

By A. Zrimsek, G. Vingas, R. Wolke

IN 1952, prompted by the great demand of the Canadian drilling and foundry industries for sodium bentonite, the Geological Department of Magnet Cove Barium Corporation, Limited began an extensive search for bentonite deposits throughout western Canada. Their efforts were rewarded in 1958, when substantial deposits of high quality material were found approximately 100 miles southeast of Edmonton, Alberta. The bentonite material, a part of the Edmonton formation in the Upper Cretaceous, is located approximately nine miles south of the town of Rosalind. The land where the bentonite lies has in places .been eroded by stream and glacial action to form a wide gully, convenient for strip mining methods (see Figure 1). The bentonite bed is almost flat-lying, dipping to the southwest at approximately 12 feet per mile. The main bed is 8 to. 10 feet thick and is covered with 15 to 25 feet of overburden. Before stripping, the area is drilled and sampled to evaluate the quantity and quality of the bentonite.

Jan 1, 1962

By Jr. Jones

This paper is derived from a document that compiles autogenous and semi-autogenous mill installations worldwide, through the end of 2010. Updates have been solicited from all major mill manufacturers and most have responded. A review of AG/SAG mills sold to date and in the last five years indicates that the AG/SAG mill market is very healthy and the trend is larger diameter mills with high diameter-to-length ratios. Ring motors (gearless) are the preferred drives for large mills even though the power transmitted through a gear drive is expected to near 11,000 kW per pinion in the near future.

Jan 1, 2012

By Ian Holl, Adam Hempstock, Rickardo Welyhorsky, Niel Morrison

"The Victor Diamond Mine is located in the James Bay lowlands, 90 km west of the First Nations village of Attawapiskat. The project was the first of its kind in northern Ontario and was completed approximately 9 months ahead of schedule.The Victor Mine process plant flowsheet was designed to produce a 95 - 98% by weight diamond concentrate. Main processing steps include 3 stages of comminution, dense medium separation and proprietary x-ray technology for final recovery. Reagent consumption for this process is limited to flocculant, for thickening of fine processed kimberlite, and FeSi for the dense medium separation.The commissioning phase of the Victor Project was executed over a period of 6 months and commenced prior to substantial completion of construction. The approach used was to focus on and complete commissioning of the higher risk dense medium separation and recovery systems prior to construction completion of up stream systems.INTRODUCTIONThe development of the Victor Diamond Mine took place over a period of approximately 5 years and had a capital cost of CAD997 million. It was a greenfields project in an undeveloped region of northern Ontario, only accessible by winter road. Figure 1, below, displays the location of the project within Ontario.The main stages of the project included feasibility, environmental permitting, engineering, construction, and commissioning. At the onset of the engineering phase, the mine was scheduled to enter production in October 2008. Through a team effort between AMEC and DeBeers Canada, the schedule was advanced by 6 months towards the goal of project completion in April 2008. Production status was attained in January 2008, approximately 9 months ahead of the original schedule. This paper focuses on the commissioning aspects of the project and includes a less detailed discussion of the engineering stage."

Jan 1, 2010

By Eduardo A. Pérez, Alejandro R. Alonso, Rosa María Luna-Sánchez, Gretchen T. Lapidus

Rare earth elements have been widely used in various sectors, from the aerospace and steel industries, to electronic applications, particularly in displays and batteries for portable devices. The high demand for newer and better equipment, such as cell phones, tablets and lap tops, has increased the consumption of the rare earth elements and at the same time the need for its recovery from electronic wastes. For that reason, the recycling of batteries is important, principally the Ni-HM batteries, due to their elevated content of rare earths elements, in addition to the high concentrations of cobalt and nickel. The current processes are based on dissolution in strong acid solutions (sulfuric acid concentrations from 2 to 4 mol/L), and temperatures from 30 to 90°C. In the present work, electrodes from spent Ni-HM batteries were leached using 1 mol/L H2SO4, in the presence of ozone as the oxidant, where recoveries of 96% for La, Ce and Nd were obtained at room temperature. The separation of Ni and Co from the leach solutions was performed using an electrochemical reactor, after which rare earth elements were precipitated, obtaining a mixture of its hydroxides with impurities below 1%, according to EDS analysis.

Jan 1, 2014

By Euler De Souza, Kyle Penner

"Booster fans play an important role in assisting main fans by boosting the air pressure of the ventilation air passing through it. The correct placement of underground booster fans in a mine is a critical decision since it not only influences the mine’s operational capacity in terms of costs and efficiency, but also affects safety and environmental conditions. There are many booster fan installations around mines that are inappropriate, in some cases resulting in system failure (fan stall) or in a major negative impact on mine production. Inadequate booster fan placement has resulted, in some cases, in extensive air leakage which has compromised the economics of the operation and, in other cases, in recirculation of contaminants which has seriously compromised safety. This paper provides guidelines for proper design and siting of booster fans underground, to not only achieve an economic ventilation system but to create safe work conditions and efficient atmospheric conditions. Procedures for the planning, installation, operation and maintenance of booster fans are also presented. A case study illustrating the design and siting of a major booster fan installation in a potash mine, supported by computational fluid dynamics analysis, is presented.INTRODUCTIONIn large underground operations with complex ventilation networks offering high resistances, the never ending increased required quantities of air can almost only be supplied through use of high pressure main fan systems. These fans may, in effect, induce significant leakage losses in the system, having a negative impact on safety performance. In such cases, booster fans can be designed to decrease the main fan pressures and reduce the leakage flows, improve system efficiency and reduce costs. In well designed systems, booster fans can thus be used to redistribute the airflow and assist the main surface fans.When the pressure supplied by the main fans is insufficient to meet the ventilation circuit pressure requirements, booster fans are placed in strategic locations where pressure boosting is essential. Booster fans are typically sited in sections of the circuit offering high ventilation resistance and requiring this form of ventilating air motivation. Booster fans are thus required when the mine expands, and so the resistance of the ventilation network, and the primary fans no longer can supply the required pressure and flow."

Jan 1, 2019

By Z. Abbasloo, A. Masoomi, L. Ebrahimi, A. Mortazavi, A. Keshavarz

"Investigation and 3D analysis of Heap no. 2 of Meydook copper complex was the subject of this study. In this project all geological and geotechnical investigations conducted in the mine were evaluated aiming at determination of Heap no. 2 design parameters. The main objective of the project was to evaluate the potential for construction of Heap. No. 2 on a waste dump built in a valley in the north side of the pit.Considering the space limitation for dump location this was a viable alternative to reduce the costs associated with heap no. 2 construction. Moreover, it allowed for a significant reduction in overall mining costs. Considering the project condition, a 3D analysis of heap major structures including; valley rock foundation, waste dump, and low grade ore was carried out. Five sets of analyses were conducted and the displacement and stress fields were calculated within the heap no. 2 components. In all analyses conducted the subsident profile was determined for the valley base rock and heap foundation (waste dump). Moreover, the shear interaction between heap and waste dump was evaluated at the heap interface. The analyses results showed that the maximum settlement at the heap base is about 4-5 cm and the waste dump provides a safe and reliable base for heap construction. Moreover, the analysis results showed that the selected %5 grade for the heap interface is good and does not pose any risk in terms of heap Interface shear displacements. A sensitivity analysis of heap mechanical parameters was also conducted. The obtained results show that if the friction angle of heap material is reduced below 25 degree due to acid spraying process, the heap walls become unstable and the heap geometry must be redesigned."

Jan 1, 2015

By J. R. D. Gravel, D. A. Poland

"The induration of iron ore pellets has always utilized prefired pellets to protect the pallet cars from the environment of the induration furnace. This paper presents the process used to obtain superior upper sidewalls. These heat resistant castings are used on induration pallet cars, and their life improvements by as much as 400% is a significant step towards the reduction of the prefired (or hearth layer pellets.) The benefit to the industry in the removal of the hearth layer is improved overall productivity. IntroductionThe Iron Ore Company of Canada (IOC) operates with production facilities located in Labrador City, Newfoundland and Sept Iles, Quebec. It has recently been acquired by North Limited, an Australian based resource oriented company. Prior to its acquisition, IOC has examined several methods of operational cost reductions. One of these was an examination of indurrating pallets. Pallets are composed of numerous assemblies and sub-assemblies. The examination of the upper sidewalls began as an intent to increase the operational life of the component. The anticipated net effect was to be a reduction in the overall pallet maintenance cost. All of the components and assemblies have undergone a severe scrutiny. IOC has found that the success of the project has depended upon not only the technical competency of all parties involved, but also upon the ability to share risk, to be innovative, and to find a partner with whom the development can proceed without fear and yet with accountability. IOC has found in Cast Steel Products (CSP) such a partner in the field of pallet development. This paper will undertake to explore the progression into the arena of partnering between IOC and CSP. CSP and IOC met in the fall of 1994. The work of re-engineering the pallets began with an initial order for 36 pallets in March, 1995. The work on the upper sidewalls involved segregation of the effect of alloy development versus physical geometry development. The nature of partnering between the two companies allocated alloy development to IOC and physical geometry development to CSP, yet no advancements were made in either area without the close co-operation or the involvement of both partners."

Jan 1, 1999

"The measurement of error in assays collected as part of a mineral exploration program or mining operation historically has been undertaken in a variety of ways. Different parameters have been used to describe the magnitude of relative error, and each of these parameters is related to the standard measure of relative error, the coefficient of variation. Calculation of the coefficient of variation can be undertaken in a variety of ways; however, only one produces unbiased estimates of measurement error: the root mean square coefficient of variation calculated from the individual coefficients of variation.Thompson and Howarth’s error analysis approach has also been used to describe measurement error. However, because this approach utilizes a regression line to describe error, it provides a substantially different measure of error than the root mean square coefficient of variation. Furthermore, because regression is used, Thompson and Howarth’s results should only be used for estimating error in individual samples, and not for describing the average error in a data set. As a result, Thompson and Howarth’s results should not be used to determine the magnitudes of component errors introduced during geochemical sampling, preparation, and analysis.Finally, the standard error on the coefficient of variation is derived, and it is shown that very poor estimates of relative error are obtained from duplicate data. As a result, geoscientists seeking to determine the average relative error in a data set should use a very large number of duplicate samples to make this estimate, particularly if the average relative error is large."

Jan 1, 2007

By Bryn Harris, Liming Huang, Andre Laplante

"This paper reviews flowsheets generally used in gold rooms to upgrade primary gravity concentrates particularly those of Knelsons. It is concluded that even for small operations, which treat between 250 and lo00 kg of concentrates per day, there is a strong economic incentive to include in the flowsheet magnetic removal of tramp iron, at least two shaking tables, screening of either table feed or table tails at 150-212 um, and scavenging of table tails with a small centrifuge. Headroom, rather than floor space, is often inadequate in most gold room designs, and limits gravity flow and flowsheet flexibility. Experimental data are presented to demonstrate the effectiveness of a small Knelson Concentrator to scavenge significant amounts of gold (up to 91 %) from fine table tails.RésuméCet article examine les schémas d’évolution généralement utilisés pour traiter les concentres gravimétriques d‘or, en particulier ceux produits par concentrateur Knelson. Nous en venons à la conclusion que même pour un petit circuit d’une capacité de 250 A 1000 kg/jour pourrait bénéficier des opérations unitaires suivantes : concentrateur magnétique pour extraire la feraille, au moins deux tables A secousses, criblage de l’alimentation ou du rejet d’une ou des tables i une maille de 150-212 um, et épuisages des rejets fins de table avec un centrifuge de petite capacité. C’est l’espace vertical du lieu où se fait cette concentration qui représente la contrainte la plus importante, plutôt que sa surface, puisqu’il faut maximiser l’écoulement par gravite des pulpes et s’offrir une certaine flexibilité quant à l’agencement final des opérations unitaires. Nous présentons également des données expérimentales pour démontrer l’efficacit6 d‘un Knelson de laboratoire pour récupérer jusqu’ à 91 % de l’or contenu dans les rejets fins de table."

Jan 1, 1999

By Ernest A. Hodgson

A SERIOUS hazard which must be faced in some mines, though quite absent in others, is that of rockbursts. Bursts cannot be wholly avoided in such mines, but the hazard would largely disappear if they could be predicted. The problem of prediction resolves itself into that of measuring pressure in the mine and determining when that pressure nears a critical value. The geophysical approach to the problem lies in discovering some physical property of the rock, which varies with pressure, which can be measured for rock in place, and for which the indication of critical conditions is sufficiently definite and open scale. A physical property, suggested first in connection with earthquake pre-diction, is that of sub-audible snapping. It was argued that, as the pressure grows, the rock probably yields microscopically and that minute snapping occurs which is so faint as to be inaudible to the unaided ear. Experience has proved this to be the case. Following other earlier work begun early in 1939, experiments with this method were initiated at Lake Shore Mines in 1941, and equipment was slowly being developed in practice when, fortunately, it was found possible to by-pass this tedious development programme. Experiments with sub-audible snapping in mine rocks had been carried out by Dr. L. A. Obert of the U.S. Bureau of Mines and his associates over a period of about four years. An amplifier and a recorder were developed, each reasonably satisfactory in practice. Lake Shore Mines offers a tempting field for rockburst research. Dr. Obert was invited to test his equipment in this and other mines in Ontario and did so. As a result, he and the administrative personnel of the Bureau became interested in the Lake Shore experiments co the extent of most generously arranging for the manufacture of sets of their own designed equipment for use in this programme. The first three sets of recorders were ordered at once and were delivered in May, 1942. A second group of three sets, incorporating various improvements indicated by experience both in the United States and in Canada, reached Kirkland Lake in April, 1943. The pick-up devices, known as geophones, were made in the electronics laboratory at Lake Shore by Mr. Zack Gibbs, who has had charge of all the instrument development in this re-search.

Jan 1, 1943

By R. A. S Villegas

The Brazilian government announced in 2007 its plans to reactivate the nuclear program. As a result of this decision, a new nuclear power plant is already being built and there are studies dealing with, among other activities, the building of 4 to 8 new ones until the end of 2030. Such increase on the country?s uranium demand affects INB, the Brazilian state company that?s in charge of uranium supply. This paper describes scenarios predicted to the Brazilian nuclear industry for the next years and the INB plans to meet the country?s needs in terms of uranium exploration and production.

Aug 1, 2010

By J. Stiksma, K. Buban, J. Oftsie, R. Kalanchey, S. Sadykov, E. McConaghy

The Kazakhmys zinc refinery in Balkhash, Kazakhstan, which employs the Dynatec Zinc Pressure Leach Process, officially launched autoclave operations on December 27, 2003. The Kazakhmys plant is the world's first greenfields zinc refinery based on Dynatec's two-stage pressure leach technology. Production of zinc was realized on February 9, 2004, when the first cathode was stripped. Currently the plant start-up is ongoing, with progression to two-stage zinc pressure leach operation and ramp-up to full design capacity continuing through 2004.

Jan 1, 2004

By J. E. Nesset, W. Zhang, J. A. Finch

Frother influences water recovery through control of bubble size and a chemical effect. De-coupling the two is necessary to establish the extent of the chemistry effect. A setup is described to give steady state water overflow rate (Jwo) along with measurements of bubble size into and on top of the froth. Arguing neither bubble size correlates directly with water overflow, a frother mass balance is solved to estimate the bubble surface area flux in the overflow (Sb0 ). The solution required measurement of frother concentration using TOC analysis and frother adsorption density using surface tension data. The relationship between Jwo and Sbo reveals the frother chemistry effect, quantified for discussion purposes by an equivalent water layer thickness.

Jan 1, 2009

By S. Harshaw, C. Doyle, A. E. M. Warner, D. Stremlaw

"In the Utility Nickel furnaces, the hearth and sidewalls are lined with high-Al2O3 bricks. During charging and thermal cycling (more so as the linings on these reverberatory furnaces age), pieces of brick spall or abrade from the refractory and collect on the top of the bath. These pieces are removed using a non-corrosive slag toward the end of the heat when the bath temperature is ~1600°C.This benign liquid can be generated by two methods. First and most obvious, suitable ingredients can be pre-mixed so that the flux (flux A) is isochemical with the non-corrosive slag. All that is needed to produce this targetted slag is heat. Second, in other proportions (flux B), the pre-mixed ingredients generate a corrosive slag that melts completely at -1200 °C and corrodes some but not all of the brick particles on the bath surface. As the reaction progresses, the slag changes composition eventually attaining the targetted benign composition. Using this option, additions are monitored to avoid overfluxing. In both cases, the generated slag/brick mixture can then be rabbled from the furnace. This practice has been successfully used for over two years and has been a factor in extending Utility Nickel furnace life to its current levels (about25% increase)."

Jan 1, 1993

By A. P. Williams

"This paper presents an overview of plant electrical systems in general, a discussion of the problems that may occur due to plant growth, the maintenance required to maintain the reliability and safety of the electrical system, and the selectivity of the relay protection system. It is divided into two main areas: short circuit levels within the plant electrical system; and relay protection systems.This information is directed at maintenance supervisors, mine managers and electrical superintendents who have been away from detailed short circuit and relay coordination calculations for some time. It points out the potential problem areas within an operating plant electrical system. Short Circuit LevelsTheoryThe electrical equipment in a plant such as breakers, switches and starters has two short circuit ratings, the momentary rating and the interrupting rating. These ratings may be given in MVA or current (amperes) depending on the equipment and manufacturer's preference. Since for a three-phase system MVA and amperes are related by the formula"

Jan 1, 1987

By C. H. Knight

"THE OBSERVATIONS that follow are confined to simple wet cyclones such as the cylindro-conical unit developed by the Dutch States Mines and marketed in America under the trademark 'Dorr-Clone'. Energy to do the work comes from the inlet velocity of the feed slurry, which is usually pumped' to the unit by a centrifugal pump.Such cyclones are simply classifiers of enormous capacity and depend for their separating effect on differences in rates of particle settlement. These particle settling rates, of course, vary with particle size, particle density, particle shape, pulp viscosity, and pulp density.The dilution of the overflow product affects both pulp viscosity and pulp density. In most operations, the temperature and the composition of the liquid -hence its viscosity --are fixed, but both pulp viscosity and pulp density can be changed by changing pulp dilution.Since the separating effect depends on differences in rates of particle setting, a perfect split with 100 per cent of the particles coarser than a given size in the underflow and 100 per cent of the finer sizes in the overflow is not possible. Just how far the separation departs from this perfection can be calculated rather exactly from the following principles, which also apply to mechanical classifiers. In removing or settling out of the overflow product all particles up to a specified size, some of the finer particles must settle out simultaneously."

Jan 1, 1955

By Éric Poulin, Simon Gariépy, Mario Paredes Malca

"While the design of a control strategy depends on the available process knowledge, its implementation depends on the available process information. On-line chemical analyzers are today widely spread in the mineral processing industry. A real-time concentration measurement of chemical components is valuable information that could bring control strategies to whole new levels. However, the use of these measures rarely reaches anything more than process monitoring. The reason is simple: the on-line chemical measurements quality is most of the time insufficient to be directly included in control strategies. The choice is then made to let the critical eye of the engineer or the operator appreciates the measurements before making any decision based on it.Data reconciliation through mass balance is a technique today widely used in the mineral processing industry to increase the accuracy and the reliability of plant data, mainly for accounting and survey analysis purposes. Real-time data reconciliation of on-line measurements appears as a natural coupling of technologies that could bring new process optimization trends. Once overcome the technical difficulties, full valorization of the instrumentation investment could be reached.This paper presents the application of real-time data reconciliation for process control and performance monitoring. It proposes a general approach, discusses challenges and illustrates concepts with industry experiences."

Jan 1, 2006

By P. J. Routledge

THE purpose of this paper is to discuss the practical aspects of locating gravel deposits and of establishing efficient, portable concrete aggregate beneficiation plants for use on construction projects where limited amounts of high-quality gravel and sand are required. Certain projects are listed, in order to demonstrate the wide variety of problems encountered. Routledge Gravel Contractors Limited, North Vancouver, have supplied concrete aggregate for construction projects in British Colum-bia since 1957. In tl1at year, in sup-plying aggregate for a small project at a site on the northern coast of British Columbia, our quote was as follows: Concrete aggregate to specifications, f.o.b. scow, North Vancouver$ 1.75 per cu. yd. Scowing charges to site. $16.00 per cu. yd. At that time, our company realized that more attractive quotations could be submitted if local gravel was utilized where available. Port-able equipment was then acquired and a simple screening plant (Figures 1 and 1a) was at first used. This was later replaced by heavier, more versatile equipment. The use of suitable equipment, the keeping of cartage to a mini-

Jan 1, 1962