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By Chuck Edwards

"Milling operations in northern Saskatchewan’s Athabasca Basin have produced uranium continuously since 1975. Over that period, the Athabasca Basin has been one of the world’s premier uranium camps, yielding more than 660 million lb of U3O8. In this paper, the author describes former and current milling operations and discusses why and how the milling process has changed and developed over the past 35 years. The author’s considerations for the future of uranium extraction in the Athabasca Basin close out the paper.INTRODUCTIONThe roughly oval Athabasca Basin in northern Saskatchewan occupies nearly one third of the surface area of the Saskatchewan Shield. Its sandstone-like deposits lie unconformably on the older basement. The basin hosts many high-grade unconformity-type uranium deposits(Saskatchewan Energy and Resources, 2010) for which the Athabasca Basin is world famous. Uranium production in the Athabasca Basin has come from four mills. In the order of startup these are Rabbit Lake, Cluff Lake, Key Lake and McClean Lake. General data (AREVA, 2010; Cameco, 2010; Denison 2010) for each mill are shown in Table 1."

Jan 1, 2011

By P Rubie, B Morgan, J Russell, C Stewart

The relationship between efficient liner exchange, concentrator availability and concentrator profitability is well documented. Russell Mineral Equipment’s (RME) relationship with OZ Minerals’ Prominent Hill site personnel enabled sound collaboration between the two parties. Both parties worked together to identify the sources of productivity and efficiency loss and developed solutions to reverse them.This paper chronicles the identification of production inefficiencies and the resulting removal of mill relining from the critical path through the materialisation of mill relining optimisation strategies. Furthermore, this paper outlines other recent mill relining optimisation strategies developed by RME and tested at Prominent Hill, to demonstrate and achieve further productivity, efficiency and safety improvements.CITATION:Rubie, P, Russell, J, Morgan, B and Stewart, C, 2017. Mill relining optimisation – a story of collaboration, in Proceedings MetPlant 2017, pp 335–345 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

In order to maintain a production rate of 6,000 tonnes per day from underground at the Williams Operating Corporation, two independent mining areas were required which created a long narrow sill pillar between them. During initial mining of the sill pillar there were a number of significant ground falls [LeBlanc and Murdoch, 2000] and in March 1999, with no active mining ongoing in the sill pillar area, a rockburst of magnitude 3.0 Nuttli occurred. Extensive ground support was designed and installed to withstand events of similar magnitude [Bawden and Jones, 2002]. A mine wide microseismic system was installed to monitor mine induced seismic behaviour over the entire mine. The area most directly affected by the 1999 rockburst was rehabilitated using a highly ductile support design. Along with microseismic instrumentation, the areas were instrumented using conventional SMART Cables and SMART MPBX?s. Subsequent to this, the area was impacted by a large number of high magnitude seismic events [magnitudes between 1.7 and 3.5 Nuttli]. The ground support performed very well during these events, providing confidence in the mine?s ability to control the ground under severe rockburst conditions. Analyses of microseismic and conventional instrumentation, combined with numerical analyses of sequence alternatives, were used to develop an optimal mining strategy for the sill pillar area. The selected strategy involved utilization of instrumentation data and calibrated model results to analyze yield zones in the sill. The analyzed ?yielded? zones were assessed to be low seismic risk. Initial mining in the sill was then concentrated in these low risk areas, with the objective of further concentrating stress into the remaining seismically active area, in order to induce ultimate failure of the sill. Continuing large magnitude seismicity and resulting damage in the remaining ?high seismic risk? area, led to abandoning a second portion of the footwall access and the strategic decision to extract a stope near the centre of this zone in order to force final failure of the sill pillar. During execution of this plan two large magnitude seismic events occurred resulting in destressing and final failure of the remaining sill pillar. The paper provides a detailed description of this ?strategic mine sequence driven self-destressing process? and the implications to final extraction planning in this area of the mine.

Apr 1, 2005

By D. E. Poole

Injury Prevention: Dependent, Independent and Interdependent In recent years, management-directed (dependent)safety programs have lost ground to the more successful self-directed (independent) programs, where employees take responsibility for their own safety. Today, with the growth of the team concept in industry, a mutual-caring (interdependent) approach to workplace safety is gaining wide acceptance. This presentation compares characteristics and results of the three progressive levels of safety responsibility and explains how to develop a successful interdependent program. The presentation will also detail the common principals that are necessary for safety excellence under any of the management styles.

Jan 1, 2000

By L. Li

The backfilling of underground stopes is a common practice throughout the mining industry. The stresses imposed by the backfill on the surrounding rock mass need to be assessed because of their influence on ground stability and on the hydro-geochemical response of the fill material. There is, however, a complex interaction between the relatively soft backfill and the much stiffer adjacent rock mass. In recent years, the authors have presented results from investigations conducted on stress distributions (obtained numerically and analytically) in and around backfilled stopes with (sub)vertical walls. In this paper, the influence of stope inclination and of backfill properties is evaluated. Results indicate that, in general, the vertical and horizontal stresses in inclined stopes are close to, but somewhat smaller than the stresses in vertical stopes. Nonetheless, significant differences can be observed in some cases, especially for the vertical stress along the inclined central line and along the hanging wall. It is further shown that neglecting deformability in limit equilibrium analyses is an acceptable assumption. However, Poisson?s ratio and the dilatancy angle, usually neglected in limit equilibrium analyses, may have significant effect on the stress distribution. Results also confirm that the backfill strength parameters (cohesion and friction angle) are critical factors required to properly evaluate the stress distribution, at least within a certain range of parameter values.

May 1, 2007

Researchers from the National Institute for Occupational Safety and Health (NIOSH) are developing a coal pillar rib rating (CPRR) technique to measure the integrity of coal ribs. The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs. The CPRR utilizes four parameters: rib homogeneity, bedding condition, face cleat orientation with respect to entry direction, and rib height. All these parameters are measurable in the field. A rib data collecting procedure and a simple sheet to calculate the CPRR were developed.

Jan 7, 2020

By John F. MacDonald

This paper describes the driving of a 400 m long by 25 m diameter highway tunnel through sensitive, overconsolidated silts and clays. The design concept requires the construction of the permanent support system, consisting of 24 concrete filled perimeter drifts, before excavating the mass core. General construction procedures used during the construction of the perimeter drifts are described.

Jan 1, 1985

By Dan A. Brown

The New Mississippi River Bridge (MRB) employed conventional design-bid-build procurement, but the bidding process included the opportunity for pre-qualified bidders to develop and propose confidential Alternative Technical Concepts (ATC?s) for evaluation and approval in advance of bidding. The ATC process provides a mechanism for value-engineering prior to bid, with incentives and opportunities for both the owner and the bidding contractor. The contract described in this paper is for the river bridge composed of a cable-stayed crossing with two pylons and the anchor piers on each side of the river. The Massman-Traylor-Alberici (MTA) team developed a re-designed foundation system for the main pylon and anchor foundations which utilizes their equipment and experience along with field load test measurements to optimize the foundations. The paper describes the experience with the use of the pre-bid ATC process on the project from the perspective of the bidder, and outlines some of the benefits and limitations of this concept with respect to foundation design and construction. Some keys for success are identified and impediments to the effective implementation of the process are described.

Jan 1, 2011

By Stuart Elliot

Brownfield project portfolios are notoriously hard to manage. Day to day there is a constant stream of changes and challenges within projects and across the whole program. When the budget year is over, we?re often left wondering: did the facilities get what they really needed? Did we get value for the capital that was spent? Did we get all the project control and process improvement that we paid for? Great work has been done over the years by the Project Management Institute, Construction Industry Institute and Independent Project Analysis to identify what leads to project success, develop project delivery systems and equip project leaders to perform better. But is attention to individual projects all we need when the job is to deliver a portfolio of many projects? Let?s work with an analogy for a moment, and say a project is like a car, and a project manager the driver. Why can?t all the projects in the portfolio get home in time for dinner? The answer, of course, is that the commute home is about traffic, not just about cars. The road, the signals and the actions of other drivers affect us in our individual cars. Optimizing traffic flow is not about managing individual cars, it is about creating the conditions that allow all traffic to move as smoothly as possible. When we?re stuck in traffic, it doesn?t really matter that we are skilled drivers who know our exact location and our engine?s vital signs. Success with a brownfield portfolio requires more than the equivalent of driver training and a good GPS in every vehicle. Managing the annual budget requires more than tight management of each project. This is not a suggestion to abandon project management in the brownfield multi-projects world; the idea is to find and apply the right tools for delivering a portfolio. Remember, we want confidence in 3 areas: 1. that the facility is getting what it really needs, when it needs it 2. that we are getting value for money invested in facility modifications and improvements, and 3. that our controls are adding value by guiding our improvement What are those portfolio tools? The job they have to do is distinct from project-level thinking: ? Create a clear and balanced business pull for project ideas ? Maintain a respectable plan for fiscal, resource and business control ? Organize the work into a steady flow ? Manage the nature and timing of value-driven project substitutions and priority changes ? Focus on overall business value added and best use of resources ? Repurpose the projects organization into being the way the facility gets improved

Nov 1, 2011

By D. J. Leidel

The offshore production of oil and gas resources has been active in the Gulf of Mexico since Kerr- McGee drilled the first commercial well out of the sight of land in 1947. Since then, approximately 60% of the offshore oil/gas production structures used globally have been erected in the GOM to support the production of energy resources’. The shallow, shelf and shelf edge waters of the Gulf of Mexico have reached or are rapidly approaching production maturity, requiring that the fixed structures used to support energy production be removed or otherwise disposed of by suitable means. The use of energetic materials has been determined to be a safe, efficient and cost effective technology to remove fixed offshore structures whose service life has been exceeded.

Jan 1, 2002

By N. McEwan

Keywords: refractories, chromite, Marico This paper examines the role of refractory-grade chromite in refractories. The chromite deposit at Verref?s Marico Chrome mine is described. The refractory properties of chromite and their role in basic refractories are described. The properties and metallurgical applications of chrome-containing refractories are described and finally environmental issues associated with chrome-containing refractories are discussed.

Jan 1, 2011

By Dale Dean, Bill Hancock, Raul Mondragon, Carlos Aguilar, Chris Martin

"In 1942, commercial mining operations began in what is now the Lucky Friday Ag/Pb/Zn mine in Idaho’s Silver Valley. Wholly owned since 1962 by Hecla Mining Company, the mine has produced more than 145 million ounces of silver and has been a mainstay producer in Idaho’s Silver Valley for over 70 years.However, by the early 21st century, the mill had fallen, technologically, seriously behind the rest of the industry. Accordingly, starting in 2005, the current mill management team set to revitalizing the milling operation. This paper will describe how the mill was systematically evaluated and the aging infrastructure replaced with more current technology. Driven by internal mill review studies supported by QEMSCAN mineralogical balancing, the mill has in recent years been through waves of upgrading – from the installation of new mechanical and column flotation equipment to the introduction of on-stream analysis, a technology well-accepted around most of the industry but alien to this technologically conservative mining district.The experience at Lucky Friday is a testament to the need for ongoing structured mill optimisation and technology upgrading in established mining operations. This paper will describe engineering experiences associated with upgrading equipment in an operating mill, contained in a confined building. Experiences in teaching the team new ways of operating a mill, and finally the metallurgical rewards that have been reaped will be described.INTRODUCTIONMining in Idaho’s Silver ValleyIdaho’s Silver Valley is a 64-km long valley flanked by the US Northern Rocky mountains, seldom more the 3-km wide, and stretching across much of Idaho’s northern panhandle, roughly 150 km south of the Canadian border. Mining has been continuously active in the area for more than 140 years, during which time, the Silver Valley has become one of the richest silver producing districts in the world, and as of 1985 had out-produced the 500 years of production from the famed Potosi district in Bolivia. Since 1885, almost 100 deposits have been discovered and worked in the district (Chapman, 2000)."

Jan 1, 2011

By B Hartmann

In 2003, Independence Group NL purchased the Long Shaft Nickel Mine complex (Long) in Kambalda, Western Australia. Lightning Nickel, the nickel operating arm of Independence Group, faced considerable challenges operating the mine, with the most significant challenge being able to prove that the remnant ore at Long and the associated orebodies could be mined safely and efficiently. Given the seismic history at Long, the magnitude of these challenges could not be underestimated. In an effort to achieve 100 per cent extraction of the flatter orebodies, traditional methods such as room and pillar were dismissed. A method consisting of transverse sills, butting into each other was proposed. To stop fill material from the first sill rilling into the adjoining sill, it was proposed to backfill the sills with pumped cement fill. The capital cost of the fill plant was estimated to be in excess of $1.5 million and the cost for cement alone was $1.0 million per annum. Shotcrete was already an extremely useful tool in dealing with the widely variable stress environment, but was to be used in an innovative manner that would enable the full extraction of a tabular section of the Victor South orebody. A layer of shotcrete, approximately 100 mm thick, was to be sprayed on the up dip wall of the initial development sill. The sill was to be backfilled with ænormalÆ development waste and ætoppedÆ with sand backfill. The next sill, ie slightly up dip and alongside, was to be mined along the shotcrete boundary wall. With respect to wall stability, the premise was that the shotcrete wall would stay in place and prevent the backfill (development waste and sand) from rilling into the adjoining development. It was also proposed that any breaches of the shotcrete wall would be repaired using shotcrete before substantial inflow of backfill into the ænewÆ development. This paper describes the development and implementation of this mining method, as well as some of the associated financial aspects.

Jan 1, 2008

By Paul Headland

The Washington Suburban Sanitary Commission (WSSC) has recently completed design for the Bi-County Water Tunnel Project. The project will include a 10-foot diameter, 5.3-mile long hard rock tunnel located within the Piedmont Physiographic Province in Montgomery County, Maryland. The rock formations present along the alignment are comprised of igneous and metamorphic lithologies. This paper presents the steps taken to characterize the complex geology along the tunnel alignment into a single ?Engineering Unit? based upon the intact rock and rock mass properties. The Rock Mass Rating (RMR) system is planned to be used as the basis for dividing the ground into three ?Excavation and Support? classes. This RMR approach was selected to establish contractual baselines as presented in the Geotechnical Baseline Report (GBR) and is intended to facilitate management of the ground support characterization during construction.

Jan 1, 2008

By K. Loutet, A. Guenkel, K. Nikolaisen

"The INCO SO2/air process was patented by INCO in 1985. Well over 80 mining operations worldwide are using this process to oxidize cyanides to cyanates in the tailings from gold, silver and copper mining operations. The sulphur dioxide (SO2) for this process can be supplied either as liquid SO2, SO2 gas or as a sulphite-based salt. The majority of SO2/air operations have used sulphite-based salts as the ‘SO2’ equivalent probably due to low capital cost. Liquid SO2 has also been used frequently, but due to concerns with safety and availability, this option is often not preferred. The solid salt sodium meta-bisulphite (SMBS) is commonly employed, but its cost is an order of magnitude higher than that of sulphur. Due to the high cost of SMBS, the increased capital cost for a sulphur-burning SO2 gas plant (green field or retrofit) usually has a pay-back of less than three years. In addition, a SO2 gas plant offers potential for significant heat recovery from the sulphur burning process. In terms of safety, the SO2 gas plant only requires the storage of relatively benign sulphur and the site inventory of SO2 will be limited to the plant gas volume. Therefore, a SO2 gas plant will not trigger the Canadian Environmental Protection Act (CEPA) E2 Regulations or the US Clean Air Act Section 112(r) accident prevention regulations, as may be the case for liquid SO2.Most existing mining operations using ‘SO2’ are gold operations, but in recent years there has been an increased interest in larger sulphur dioxide gas plants for hydrometallurgical facilities that employ leaching of cobalt/manganese minerals or precipitation of manganese/iron (e.g. Tenke Fungurume and El Boleo).This paper focuses on the production of sulphur dioxide gas generated on site and on demand for the use in hydrometallurgical processes. The capital and operational costs of a SO2 gas plant is compared to conventional process alternatives using sulphite-based salts or liquid SO2."

Jan 1, 2016

By K. Meyer

"INTRODUCTIONThe David Bell Mine Concentrator started production in April 1985. A staff of twenty-seven people operate and maintain the concentrator. The crew is grouped into the following main areas.16 Operators6 Assaying/Metallurgy/Refining/Clerical4 Maintenance people2 SupervisionOperating highlights of the following unit processes will be discussed in detail:Screening and ThickeningPre-aeration and CyanidationCarbon-In-Pulp Gold AdsorptionCarbon Handling andGold RecoveryFor a complete description of the concentrator, refer to the papers by: (1) C.V. Sibbald, Teck-Corona's Hemlo Mill, October 1984, (2) R.A. Ford, The David Bell Mine at Hemlo, From Exploration to Production, November 1987. For operating details of the grinding circuit and effluent treatment plant refer to papers by: (3) T.G. Smith, SAG Mill Experience at The David Bell Mine, October 1988, ( 4) AN. Veltmeyer, The Effluent Treatment Plant of The David Bell Mine, January 1989.TRASH AND CARBON SCREENSTrash ScreenThe vibrating trash screen is inclined at 5 degrees and is clad with a 28 mesh stainless steel cloth which is changed monthly during the SAG mill liner replacement/inspection shut down. Other screen openings and configurations have been tried and the screen has been by-passed to change the cloth ""on the fly"". These attempts resulted in fibres (usually wood) to report to #1 Carbon-In-Pulp (CIP) tank, where the fibres are trapped in the CIP launder screens, and downstream carbon handling screens causing serious blinding problems. The trash screen in a Carbon-In-Pulp (CIP) or Carbon-In-Leach (CIL) gold mill removes fibres before they:are reground in the ball millsaturate with gold bearing leach solutionplug launder screens in CIP or CIL tanksplug carbon circuit pipe screenstherefore the trash screen is best placed ahead of the thickener."

Jan 1, 1989

By Anne Kvithyld

Silicon solar cells, that convert the energy of sunlight into electric energy, are attractive sources of energy. In the production line wafers of solar cells are sliced from a multicrystaline ingot solidified unidirectionally. Recycling scrap from top and sides of such ingots is addressed. SiC and Si3N4 inclusions are a major problem. Scrap from Scan Wafer ASA is melted in a high vacuum furnace at around 1500ºC. The filters, from commercial producers, are C and SiC with 10, 20 and 30 ppi. Characterisation of inclusions before and after filtration, and in the filter itself, is performed by microscopy. Dissolution of silicon in acid and counting of the un-dissolved inclusions is also carried out. In the filter Si3N4 needles and SiC inclusions were identified. The amount of these inclusions in the filtered silicon is much less than in the input. In conclusion, filtration using SiC and C filters in vacuum system in argon atmosphere removes SiC and Si3N4 inclusions from solar cell scrap. Flow of metal through the filters is not a problem. These results are promising with scale-up to industrial application in mind.

Jan 1, 2006

By X Dahe

SLon vertical ring and pulsating high gradient magnetic separators (VPHGMS) possess the advantages of high efficiency and high reliability in beneficiating weakly magnetic minerals. In recent years, models SLon-2250, SLon-2500, SLon-3000 and SLon-4000 have been developed. This paper gives several examples of their applications in oxidised iron ore and ilmenite processing flow sheets to improve iron and ilmenite recoveries.CITATION:Dahe, X, 2017. Recent development and application of SLon vertical ring and pulsating high gradient magnetic separators in the iron ore and ilmenite processing industries, in Proceedings Iron Ore 2017, pp 461–466 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Khaled Morsy

In the past two decades, high horizontal stress has been attributed to many ground control failures. Most believe that entries parallel to the high horizontal stress is most stable and least stable when perpendicular to it. Entry stability decreases when the angle between entry and horizontal stress increases. The concept of 2-D stress shadow has been proposed for selection of proper panel orientation, often with mixed results. In this paper 3-D finite element modeling was used to analyze the stress distribution at the headgate of a longwall panel subject to high horizontal stress at various angles. It was found that the directions of induced principal stresses at the longwall face and headgate are independent of the panel orientation. The induced principal stresses concentrate or relief at headgate based on the panel orientation with respect to the directions of the induced principal stresses. Accordingly, only 3-D modeling can fully account for the effects of high horizontal stress on panel orientation. The paper illustrates in details the changes in orientation and magnitude of all three principal stresses around the longwall face and T-junction area as panel orientation changes.

Jan 1, 2006

By C. A. Brown

"Steady-state simulation has been used for over 20 years to optimise the operation of crushing and grinding circuits. Throughout that period continuing comminution research has been the basis for improving the models.Site surveys, ore characterisation, model development and investigation of different operating scenarios by simulation has proved to be a cost-effective method for improving plant performance. In this sense, this paper presents findings from experience with these valuable optimisation techniques with reference to specific case studies."

Sep 12, 2005