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By N. A. Beier, R. Amos, Smith. L., C. Atherton, D. R. Barsi, D. Blowes, D. C. Sego

"Waste rock is one of the most abundant materials at mine sites and must be properly characterized and managed to limit acid rock drainage and other harmful byproducts. An experimental waste rock pile—part of the test piles research program—located at the Diavik diamond mine (Northwest Territories, Canada) was deconstructed and sampled to study the spatial variability of material properties. Bulk samples were classified based on the amount of material finer than 4.75 mm. Hydraulic properties of each sample were estimated and particle size distribution analysis was completed. These datasets and classification methods might be used to improve the understanding of hydraulic and geochemical behaviour of the material and to study waste rock at other sites. ¦ KEYWORDS Acid rock drainage (ARD), Material classification, Particle size distribution (PSD), Waste rock RÉSUMÉ Les stériles font partie des matériaux les plus abondants sur les sites miniers et, en tant que tels, doivent être correctement caractérisés et gérés afin de limiter le drainage rocheux acide (DRA) et la pré¬sence d’autres sous-produits nocifs. Dans le cadre du programme Test Piles Research Program, un amas de roches stériles expérimental situé à la mine de diamant Diavik (Territoires du Nord-Ouest, Canada) a été décomposé et mis à l’essai afin d’étudier la variabilité spatiale des propriétés des matériaux. Les échan¬tillons en vrac ont été classés en fonction de la quantité de matériaux plus fins que 4,75 mm. Les propriétés hydrauliques de chaque échantillon ont été estimées et l’analyse de la composition granulométrique effectuée. Ces ensembles de données et méthodes de classement serviront à mieux comprendre le com¬portement hydraulique et géochimique du matériau et à étudier les stériles sur d’autres sites. ¦ MOTS CLÉS classement des matériaux, composition granulométrique, drainage rocheux acide (DRA), stérilesINTRODUCTION Statement of problem The characterization of mine waste rock remains a challenge in active mining sites. The large volume of material and the large size of particles make it difficult to collect representative samples. Sampling techniques are often dis-ruptive to mining operations because they alter the structure of the waste rock pile or interfere with mine traffic. The convention at most mine sites to collect little to no information on waste rock material means that models and predictions of how waste material will behave and interact with the surrounding environment are based on general information that might not be site specific. This could lead to environmental damage or higher costs if environmental effects are underestimated during the construction of waste rock structures."

Jan 1, 2019

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 C. S. Simons, D. A. Dahlstrom

"Growing interest in the developing technique of improving the dewatering of filter cakes by the direct application of steam has been apparent during the past year. A number of applications to iron and base-metal concentrates are under study, and intensive work continues on applications to coal cleaning.This paper presents and discusses the data presently available. The effects of material characteristics and operating variables on final cake moisture are examined. Although it is not yet possible to answer all questions regarding the applicability of the technique to specific problems from general data correlations, it is found that the use of these in con-junction with empirical data derived from properly conducted laboratory tests does yield reliable conclusions.Emphasis is placed on the basic economics of the process, and on de-sign criteria for ""steam drying"" filter stations, as applied particularly to metallurgical concentrates. Examples of the use of laboratory tests to solve application problems are given."

Jan 1, 1966

By Horatio Sam-Aggrey, Margot Hurlbert

Small Modular Reactors (SMRs) have been touted as having the potential to spearhead a nuclear renaissance. Proponents of this view cite the relative advantages of SMRs over larger nuclear plants as reason for their optimism. Some of these merits include potential economies of mass production deriving from modular factory production, enhanced safety features, the ability to locate reactors in remote areas, and reduced requirements for technical workforces to install and maintain SMRs. Despite the optimism surrounding SMRs, nuclear power is still a contentious issue for many Canadians. The growth of nuclear power remains adversely affected by concerns over issues such as: the health and safety consequences of nuclear power generation, environmental impacts, proliferation of nuclear materials, terrorism, and radioactive waste disposal (Organisation for Economic Co-operation and Development (OECD) and Nuclear Energy Agency (NEA), 2010). Personal values, past nuclear accidents, and lack of trust in the industry are other factors influencing attitudes toward nuclear energy (IAEA, 2005). In Canada, three main areas where SMRs could be used have been identified. These include: a. Traditional, on-grid power generation, especially in provinces looking for zero-emissions replacements for CO2-emitting coal plants. B. Remote off grid communities that currently rely on diesel or fuel oil power generation. There are 279 off-grid communities in Canada, many of them being Aboriginal communities (NRCan, ND). Notably, all communities in each of Canada’s three territories qualify as remote. C. Resource extraction sites, such as mining and oil and gas extraction sites. Many of Canada’s principal producing mines and active mineral exploration projects are located within close proximity of Aboriginal communities. Any proposed implementation of small nuclear plants would, require the support of the local population, which is largely Indigenous in the northern regions. The possible deployment of SMRs raises important issue relating to consultation and accommodation of Aboriginal concerns regarding potential SMR deployment. This is especially pertinent given Canada’s pending implementation of the provisions of UNDRIP. One of the provisions of UNDRIP that has attracted a lot of attention is the one on Free Prior and Informed Consent (FPIC). Drawing on previously published information, this paper discusses some of the challenges posed by FPIC for the deployment of SMRs. The next section outlines the provisions of FPIC and its implementation in the Canadian context. Section 3, details some of the challenges posed by FPIC to the deployment of SMRs, while Section 4 provides some concluding comments.

Jan 1, 2020

By The Staff

THE gold mining industry in Canada is today the most important stabilizing influence in the country. This factor was brought out particularly during the 'depression' years, when steady employment was given to men in that industry and the monies spent in supplies and power in turn benefited the country to a great extent. At the same time, a commodity was produced which was saleable in any market of the world, thus maintaining Canada's credit in foreign markets and keeping her trade balances equalized. We have a vast area known as the Precambrian Shield. The agricultural possibilities of this area are practically negligible and it will depend entirely upon the mineral and forest resources to make this district an economic factor in the life of Canada. To date, from the mineral point of view, we have been highly successful. There are, however, still vast areas to be explored. It is tedious and laborious work, entailing great individual hard-ships and the expenditure of much energy and money. During my thirty years' experience in the search for, and operating of, gold mines, I have come to the conclusion that although individuals may give all their time, energy, and money, Governmental assistance is absolutely necessary in the development of hydro-electric power sites and roads. The Governments, to date, have given splendid co-operation along these lines, but in order that this great industry may go ahead they should continue their good work and, if possible, give greater relief from taxation to mines situated at a considerable distance from the railway.

Jan 1, 1938

By L. M. Southwick

"The history of extractive metallurgy is replete with examples of commercializing new processing technologies. The successes are widely reported, but failures seldom are. This is unfortunate, for usually we can learn more specifics on how to succeed in technology development by studying and thoroughly understanding their failures. Frequently one encounters a red herring that caused the whole effort to fail. A thorough and objective due diligence up front would have identified those red herrings and prevented the pursuit of a bad idea and the resulting destruction of capital. Due diligent analyzes performed before construction of three such bad ideas will be discussed. One is an EAF dust process, which pursued the red herrings of a poor understanding of the business, a naïve view of past experience, and false confidence in the technology. Another will examine the effort to commercialize a new pressure copper leach process that followed the red herrings of inadequate testing of the raw material, application of processing conditions that were inherently unsafe, and an improper assessment of the inherent advantages of past developments. The last is an alternative iron-making process, where the red herrings were incomplete and superficial assessment of prior pilot plant and demonstration plant tests, an assumption that the commercialization model of “build it and we will make it run” was viable, and a technology whose technical fatal flaws had already been identified. Unfortunately, capital destruction often also closes the window to more intelligent pursuit of technology development. TECHNOLOGY COMMERCIALIZATIONThe development and commercialization of new technology is a vital part of keeping industry profitable, able to deal with new sorts of feed stocks and current with economic, product, operational and environmental requirements. This is a difficult task in the best of times, and can be compounded when the developers become enamored of a particularly favorable characteristic of the project or of the product. These “red herrings” divert project focus away from the arduous path to success and, in the end, result in project failure."

Jan 1, 2012

By Meimei Zhang

In the overall open pit mine planning process, mining phase design is a strategic driver in guiding and constructing the block extraction sequence and determining the annual net cash flow distribution. Mining phase design should obey some practical constraints, such as ?minimum mining width? and ?flat mining phase bottom?, to allow space for haul road development and truck and shovel access on each bench. However, these practical mining phase design requirements are not taken into account in all first-cut mining phase design methods and post-processing is always required to convert an impractical design to a practical one, resulting in a potentially significant loss of Net Present Value (NPV) relative to the first-cut impractical designs. In this paper, we present a method using a meta-heuristic algorithm ? Simulated Annealing ? to enforce those practical constraints in determining a mineable phase design whilst ensuring minimum NPV loss.

Oct 1, 2009

By W. E. Segsworth

Introduction By far the largest part of the money raised for mining is raised by honest and legitimate means; but a not inconsiderable amount is raised by fraudulent sales methods. It will be conceded without argument that the greatest menace to the mining business is the fraudulent promoter. The sale of worthless mining stocks to the public by high-pressure. salesmen, house to house canvassers, telephone campaigns, fraudulent use of the mails, fraudulent statements, and reloading, has seriously prejudiced the public against even legitimate mining. A very small percentage of the funds raised by such fraudulent means is ever spent on the property, but instead is absorbed by the promoter in illegitimate' profits, enormous commissions, high office rents, and other expenditures, and is just so much subtracted from the fund which the legitimate developer needs to bring new mines to the point of production. The mining fraternity has been at fault in that, while they recognized this situation, they made no adequate attempt to rectify it. They knew that these fraudulent practises were conducted by parasites who attached themselves to the mining business in boom times and claimed to be part and parcel of it, but who were merely professional salesmen and promoters who, when there was not a mining boom, were selling sky-line real-estate, worthless oil stocks, or fraudulent securities which happened to be popular with the public. While mining people had this distinction well in mind, the public did not differentiate between the crooked promoter temporarily selling fraudulent mining stock and the honest promoter who made mining finance his life work; and we did little to make this distinction clear to the public or to sweep these money grabbers out of our house. The historic boom of 1927-8 and '29 brought with it the usual crop of crooked mining promoters, and the scandals resulting from their operations forced the Governments into the enactment of laws to attempt to protect the gullible public against the operations of these meanest of thieves and to appease public clamour.

Jan 1, 1934

By M. Jayaraman

With the ever increasing demand for commodities, due to changes in lifestyle and increase in population, people are striving to find ways to keep up. Mining is one essential element in the solution. Though being a powerful boost to a country?s economy, mining can have disastrous effects in the absence of waste management practice and technologies; because of the harmful heavy metals and toxic chemical waste that is generated as a by-product in mining operations. It is an established and documented fact that pollution is a major concern for communities having to live with it. Disproportionate water consumption significantly impacts local rivers and ponds thereby reducing freshwater availability and have given rise to social conflict. In light of these misgivings, management and treatment of mine water and waste has gained considerable attention recently. In this paper, we summarize some of the treatment methods that can be adopted by mining companies to reduce their environmental footprint. Appropriate treatment solutions depend on various factors including available space and capital cost for treatment solutions, type of mining waste generated, current state of the mining plant, geographical location, and other location specific issues. Incorporating waste and water management solutions as a priority within mining operations is critical for addressing increasing regulatory requirements and a starting point for initiating other Corporate Social Responsibility (CSR) programs. Collaboration among mining companies, NGOs, local community, and government facilitates successful projects which build trust leading to long term relationships. In this paper we also talk about the benefits of implementing a CSR project that captures the focus of local communities and allows the mining company to focus on operations. Implementing a sustainable business model that incorporates the broader community impacted by projects will continue to benefit even after the mining company ceases operation in that location. The challenges involved with implementing effective CSR projects, which require measuring and reporting effectiveness to create a positive social, economic, and environmental impact is also presented in this paper.

Aug 1, 2013

By B. W. Clyburn

"Coals from the Corporation's Lingan and No. 26 mines are classified as high-volatile A bituminous, with a very low inherent ash and containing a/l essential properties to provide metallurgical coal, with the exception of a high sulphur content. Only through proper cleaning at low specific gravity can the pyritic sulphur fraction of the coal be liberated to an extent where final sulphur meets coking standards. This first section of the paper deals with the operation of a Dutch State Mines heavy-media cyclone circuit to achieve an actual separation in the region of 1.30 specific gravity. A discussion of the parameter of control which must be applied along with an appraisal of the results obtained is included in the paper.IntroductionVery high fluidity and unusually low ash are the outstanding characteristics of coal from Devco's mines in the Harbour seam of the Sydney coal field.However, sulphur content, mainly pyritic, ranges from 1 to 2.5070. To obtain the low and consistent sulphur level required in metallurgical coking coals, preparation at low specific gravity is required .Metallurgical coke is used as the fuel in an iron blast furnace. Its sulphur content largely determines the quantity of slag required to remove it and therefore influences furnace productivity and unit costs.Typical data on the various coal properties of importance in the production of coke are included in Table I. Necessity of Low-Gravity SeparationThe design of any coal preparation plant requires the study of washability properties of the coal to be treated to determine the quantity and quality of coal produced at a given specific gravity along with the difficulty in accomplishing that separation.Their low ash content allows the important washability aspects of Harbour seam coals to be represented by sulphur! specific gravity curves (Fig. I). This particular example indicates that a yield of 54.5% is attained, at a sulphur content of 1.20%, for a perfect separating device operating with a 1.29 S.G. cut point.Material rejected from this separation still contains usable coal, which is recovered as middlings by separating at a higher gravity."

Jan 1, 1980

By E. E. Mason

THE Myrtle group of mining claims is situated on Barkerville mountain in the Cariboo mining district of British Columbia, west of the old mining town of Barkerville. An 1,800-foot adit, known as the Shamrock tunnel, was driven in 1935-36 from the Barkerville road and in the general direction of the Myrtle group. It was proposed to enlarge this adit to more convenient section, extend it 2,500 feet int0 Myrtle ground, and from there drive a main entry 3,000 feet along the length of the group. Several laterals were also to be driven off this main entry as part of the tunnel schedule. It was thus originally proposed to drive 5,500 feet of new adit and 1,800 feet of laterals, a total of 7,300 feet of new work. Work was commenced with a bulldozer on April 21st, 1941, cutting a bench on the hillside for a plant site. The power plant was ready for operation on August 8th. Slashing and re-timbering of the old adit rook longer than was expected. It was found that 57 per cent of the length required timbering, chiefly by fore-poling, and there was also trouble in several sections with swelling ground. First round in the new face was taken on September 17th, when a 2-shift daily schedule was commenced. Due to delays in delivery of electrical equipment, it was not possible to add the third shift until November 14th. From then on, a 3-shift daily schedule was maintained with the exception of holidays and fortnightly change Sundays until August 1st, 1942, when shortage of labour caused the dropping of a shift. All work was suspended on August 14th. The ground through which the tunnel passed was such that the driving was often interrupted by the need of protective timber at the face. Further, crews were continuously employed timbering behind the face, and in maintenance of timbered sections in swelling ground. Roughly 980 feet of the new workings are now timbered, about 21 per cent of the total.

Jan 1, 1942

By Charles T. Harper

The uranium deposits discovered by Amok (Canada) Ltd. in the Cluff Lake area of north western Saskatchewan occur at or near the southern edge of the uplifted basement core of the Carswell circular structure. Two types of mineralization, distinguishable, by their geological and structural setting and mineral paragenesis, have been recognized. The N-Claude type is characterized by a relatively simple mineral assemblage, consisting of uraninite or pitchblende with coffinite, and is accompanied by variable amounts of graphite and organic matter, and Fe, Cu, Pb and Mo sulphides. Both N and Claude orebodies occur within quartzofeldspathic gneisses of the basement core. On the other hand, the D-type ore has a complex mineral assemblage consisting of: uraninite, pitchblende, thucholite and coffinite, along with native gold and selenium; gold tellurides, and selenides of Pb, Bi, Ni and Co; sulphides of Fe, Cu and Pb; and organic matter. The D orebody occurs within carbonaceous shales at the base of the Athabasca Formation as well as in fault zones in regolithic quartzo feldspathic gneisses above the inverted unconformity. An age of 1050 m.y., which is consistent with a period (circa 1200-1000 m.y.) of widespread hydrothermal activity and uranium mineralization or reworking within and adjacent to the Athabasca Basin, has been obtained from uranium mineralization from the D orebody. Later reworking (circa470 m.y.) of the mineralization occurred at the intersection of older mineralized shear zones with radial faults produced during meteorite impact.

Jan 1, 1978

By M. A. Perras, M. S. Diederichs

"The Niagara Tunnel Project (NTP) is a 10.1 km long water-diversion tunnel in Niagara Falls, Ontario, which was excavated by a 14.4 m diameter tunnel boring machine. The excavated rock types included limestone, sandstone, siltstone, shale and mudstone. Based on observations and measurements the overbreak was divided into four zones. Approximately half the tunnel length was excavated through the Queenston Formation, which locally is a shale to mudstone. Three of the four overbreak zones were within the Queenston. Zone 1 includes the formations above the Queenston Formation, Zones 2 and 4 are border regimes with little or no influence from St. Davids Buried Gorge and Zone 3 is the area influenced by the gorge. Zones 2 through 4 can be generally summarized as having overbreak as the result of stress induced spalling. Zone 2 marks the transition from slabbing at the Whirlpool contact in the stress shadow to spalling towards Zone 3. The behaviour of Zone 3 is interrupted from the typical high stress behaviour due to the presence of St. Davids Buried Gorge. As the tunnel passed from the gorge the high regional stresses induce spalling, which creates the typical notch shaped overbreak geometry of Zone 4.Three modelling approaches were used to back analyze the brittle failure process at the NTP: damage initiation and spalling limit, laminated anisotropy modelling, and ubiquitous joint approaches. Analyses were conducted for three tunnel chainages: 3+000, 3+250, and 3+500 m because the overbreak depth increased from 2 to 4 m. All approaches produced similar overbreak geometries to those measured. The laminated anisotropy modelling approach was able to produce overbreak depths and chord closures closest to those measured, using a joint normal to shear stiffness ratio between 1 and 2. The back analysis results were able to produce sets of stress and strength inputs for different sections of the tunnel at the transition from overbreak Zone 3 to 4. The back analysis procedure demonstrates the importance of including the anisotropic stiffness in the numerical modelling approach to correctly capture the overbreak geometry and deformations around underground excavations."

Jan 1, 2015

By X. (Mike) Yao

Rock mechanics engineers must provide ground support designs that ensure a safe underground working environment. Unexpected falls of ground are unacceptable while ground support systems must be adequate. Ground support must be economic for the area supported and the time frame the opening is in use. While numerical modeling can be used for ground support design, empirical models are still the common useful design tools. Empirical models are best developed and improved from local experiences although some models, such as Stability Graph (Potvin et al, 1992), are in extensive use by the Canadian mining industry. To determine the adequacy of ground support practices at HBMS, a database of 50 fall of ground case histories between 1985 and 2001 was compiled. For each failure, the recorded data included: location, rock type, rock mass conditions, opening and failure geometry, installed ground support and failure mechanism. An analysis of the database was done to obtain an understanding of failure frequency association with rock types, stope geometry and installed ground support, and to assess what support design changes were necessary. The paper describes changes made to ground support and mining practices during the last five years, and the formation of new ground support standards and practices which have been successful in reducing ground falls while providing improved, efficient and economical ground support.

May 1, 2002

By J. -F. Blais, M. -O. Simonnot, J. Mocellin, G. Mercier, J. -L. Morel

Large quantities of ferromanganese sludge are generated as waste material by blast furnace during the manufacturing of ferromanganese. These slags are very rich in manganese, zinc and lead (5 to 40 %). These residues have been deposited in a pond in periphery of the steel industry. Considering the market value of the metals, these brownfield sites can now be considered as secondary resources. We have developed a hydrometallurgical process for selectively leaching Zn, Mn and Pb in order to produce compounds of Mn and Zn pure enough to be economically recoverable and a residue rich in Pb. Batch laboratory experiments were carried out to determine appropriate leaching conditions to maximize zinc extraction (100 %) and manganese extraction (90.0 %) with sulfuric acid and to generate a residue containing 15 to 30% of lead. This Pb residue is recyclable by another process.

Jan 1, 2015

By C. A. Jeffrey, K. Pearson

Abstract - The Croft diorite in central England belongs to a suite of Caledonian igneous rocks collectively known as the South Leicestershire diorite complex. Although the intrusions occupy separate outcrops, they are linked at depth to form a single pluton, buried beneath a cover of Triassic sediments (Le Bas, 1972; 1982, Allsop and Arthur, 1983). Both the Caledonian diorites and the overlying sub-Triassic unconformity have been affected by a complex history of alteration and mineralization which can be subdivided into four stages: (1) deuteric effects, caused by the release of volatiles during magmatic cooling; (2) albitization through sodic enrichment; (3) formation of lowtemperature laumontite, analcime and calcite veins with associated wall-rock alteration to prehnite and pumpellyite; and (4) sub-Triassic unconformity-hosted base metal, manganese and palygorskite mineralization. Zeolite mineralization occured some 200 Ma later than the intrusion itself, during post-Triassic times, as indicated by the presence of a single vein of laumontite and microcrystalline calcite which cross-cuts the sub-Triassic unconformity surface and enters the overlying Triassic sediments. Evidence from fluid inclusion work indicates that two fluids were involved in the deposition of the zeolite veins. One fluid was initially of relatively high temperature (~100°C to 320°C) and low salinity (~0.2 to 5.9 wt% NaCl equiv.), and was probably meteoric in origin, whereas the other was of relatively low temperature (~41°C to 165°C) and high salinity (~0.4 to 16.72 wt% NaCl equiv.), and is interpreted to represent a basinal brine. During Triassic rifting, thinning and fracturing of the crust, with the possible rise of associated magmas (Halliday and Mitchell, 1984), could have increased permeability and heat flow, initiating the circulation of hydrothermal fluids. Triassic unconformity-hosted base-metal mineralization in Central England is similar to other Triassic-Jurassic mineralization in Europe (Mitchell and Halliday, 1976).

Jan 1, 1997

By Z. D. Hora

Sand and gravel resources of the southern coastal region of British Columbia may be linked to various episodes of Wisconsin glaciation. During Wisconsin and probably earlier times, the Fraser Lowland and coastal areas were subjected to repeated glaciations separated by non-glacial intervals. Each major glaciation was accompanied by isostatic and eustatic changes in sea level up to 200 m or more. As a result, the Lowland was covered by the sea during much of Quaternary time. Because the Fraser Lowland is surrounded on two sides by high mountain ranges, glaciers terminated in the sea during their maximum advance. Therefore, meltwaters released during deglaciation, together wit h retreating glacier ice, could produce widespread and extensive sand and gravel deposits both along the coast and throughout the Fraser Lowland and adjacent areas.

Jan 1, 1984

By H. Harzer

Statistics Canada record s indicate that in recent years 70 to 80% of the entire Canadian coal production originated from Western Canadian mines, in which about 55 to 65% of the coals are bituminous. Until recently, less than 20% of the latter were extracted by underground methods , the remainder being surface-mined. However, it is estimated that within the foreseeable future up to 80 or 90% will have to be gained by underground techniques. Although Western Canadian coal resources are considerable, they are unfortunately locked in severely distorted, steeply pitching and faulted seams of variable thickness. Consequently, their economic extraction poses serious engineering problems. One possible solution to the problems is to apply hydromechanical methods to underground mining. This is a well-proven method shown to be economically viable under Western Canadian conditions. This paper endeavours to widen the scope of published data on hydraulic coal mining and is based on practical engineering and cost data gathered through contacts with West German designers and operators of hydraulic mines.

Jan 1, 1978

By A. Broussaud

The paper describes the advanced grinding control system implemented at Newmont Ahafo gold mine, Ghana in 2009 and 2010. It shows how the different components of the Advanced Process Control (APC) system cooperate for increasing plant performance. The SABC circuit processes hard rock from different pits mixed with a variable proportion of oxides. The control strategy is designed to address specific disturbances, including start/stops of pebble crushers, unavailability of oxides, changes in rock size distribution resulting from segregation in the stockpile, and changes in ore type and hardness. The system consists of an expert system per se with extensive use of fuzzy logic, supplemented by an online dynamic model of the process used as a soft sensor, a VisioRock? rock size measurement system over SAG mill feed before addition of recycled pebbles, and an AudioMill? system to analyze the SAG mill sound and detect impacts on liners. All these components are embedded in the same OCS© software platform, which, among other benefits, makes it easy to support the entire system remotely. The paper details the physical constraints and the variables that are manipulated. It describes the control strategy and the contribution of each component of the system. It also describes the project implementation and the performance of the system. In addition to a strong involvement and support of management, the very good acceptance of the operators has been facilitated by the remote access system that made it possible to immediately modify the system each time it was needed during the baby sitting phase. The system made it possible to increase gold production significantly through increases in tonnage and recovery thanks to a better control of the grind size through a stabilization of the secondary ball milling circuit and an improvement of the operating conditions of the classifying cyclones.

Jan 1, 2012

By B. K. Ayres

Modern management of uranium mine or mill waste storage facilities (WSFs) often requires that they be remediated or decommissioned with a cover system. In addition to creating a self-sustaining landscape that supports the end land use, cover systems are intended to reduce long-term risks to human and ecological receptors from the stored waste to acceptable levels. The performance and longevity of a cover system will be strongly influenced by the features or shapes of the WSF final landform. Hence, cover systems and landforms must be thought of as an integrated design. Based on the author’s experience, the most important elements of the design process for maximizing the potential of WSF final landforms / cover systems being sustainable over the long term are noted in this manuscript. Several key items that must be considered and addressed during the planning phase of constructing a WSF final landform are also described. Various methods for monitoring performance of a WSF final landform are also reviewed. Key aspects associated with decommissioning a tailings WSF and waste rock pile at the former Cluff Lake uranium mine in northern Saskatchewan are included to illustrate many of the practical insights provided in this paper.

Jan 1, 2020