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By Laura McNally

In 2006, McNally International Inc., in a joint venture partner-ship with Aecon Constructors, was the successful bidder on two York Region Tunnel Projects: the Bathurst Collector/Langstaff Trunk Sewers and the York Durham Sewer System (YDSS) Interceptor Sewer 19th Avenue, both in the Toronto area. These projects comprised a total of 13 km (8 miles) of 2.74 m (9 ft) finished diameter tunnels and are both part of the YDSS. Both contracts required the use of earth pressure balance (EPB) tunnel boring machines (TBM) with a precast concrete segmental liner.

Jan 1, 2008

By H. Tudeshki, A. Tayebi

"The large extent of global production and consumption of aggregates from quarries, grabs one´s attention and makes its substantial and essential standpoint in the world today pretty clear. A great amount of aggregates is utilized in civil engineering applications such as road construction, railway industry, concrete production, etc. Considering this fact that igneous rocks display a higher strength and abrasion resistance, this type of rock is preferred in the field of civil engineering. For all these applications, rock quality assurance is a key factor and certainly unavoidable, and it has great influence on the quality of constructions in civil engineering. One of the major problems encountered by both the producers and users of igneous rock is the fact that, with the passage of time, some specific rocks lose their strength, up to a complete loss of structure or in other words, their disintegration and degradation. In the last decades, different methods and procedures such as Glycol test, methylene blue dye test, as well as the Los Angeles test have been introduced to distinguish these rock properties, and to identify these problems. However, as these methods are time consuming, hard to perform, only to be applied to hand-piece samples, requiring special laboratory equipments, and only possible to be accomplished under laboratory conditions, their application has always been limited to some specific cases, and they are neither recommendable nor advantageous. In addition, these methods provide partially different results for the same rock. To address this widespread quality management problem of the quarry industry, a relatively quick, easy and user-friendly approach is necessary. It calls for a systematic solution with a device that can simply be used day to day in a mine for quality control of the quarry´s daily production. This scientific research is concentrated on developing a systematic method for early recognition and diagnosis of rock quality, in order to control and manage the quality of the quarry production in advance. This method was developed, based on the procedure of the magnetic susceptibility measurement. The obtained values can lead to valuable information regarding the quality of the rock and allows the quality control process to be accomplished and performed at the borehole location. This approach has been assessed through extensive field and laboratory studies. A detailed and comprehensive discussion will be made on the results of the experiments. The advantages and impacts of the application of this method, on increasing the reserves and environmental protection are also discussed."

Jan 1, 2011

By D. A. Fenton

Two large 34 ½ foot diameter mills have seen seven years of continuous operation before massive fracturing occurred on one of the trunnion cones. These fractures were discovered when liner changes were made. Four modes of failure were identified, three of the modes combining to cause a large circumferential tear in the 4-inch cone plate. A theoretical account is made of the modes of fracture and comparison made with field results. New material was used to repair the fractured cone, and the complete repair took ten weeks. The repair was monitored and lasted twenty-six weeks before the newly designed structure was available.

Jan 1, 1982

By J. R. Evans

Mining claims must have a discovery of a valuable mineral deposit to be valid. When required, a Federal government mineral examiner makes a determination of validity and recommendations thereof to authorized management officials. The examiner should show whether or not an existing mining operation, or a proposed operation have economic viability. This is accomplished through an analysis of legal entities, land status and use, geologic and mineralogic relationships, and mining, milling and processing techniques considered in an appropriate economic evaluation framework. A framework involves market and market entry studies, reserve analyses, all costs analysis, royalty buyouts, tax structure, discount rate of return, and escalation and risk factors. An income approach to value is then used by means of a simple or complex discounted cash flow (DCF) analysis to certify validity. Whether one claim is owned by a single miner, or hundreds of claims are owned by a large corporation, thorough, fair, consistent, and appropriate economic concepts should be applied by the mineral examiner.

Jan 1, 1993

By K. Severin, B. Flanigan, P. Marion

“Plutonic-related” gold deposits in Interior and SW Alaska (Tintina Gold Belt) vary significantly in size, grade, vein/deposit morphology, depth of emplacement, distance from causative pluton and metal association. Metal associations such as Au-Bi and Au-As-(Sb-Hg) are a good empirical indicator of depth of emplacement and distance from causative pluton and have been used successfully in exploration. Results from a variety of analytical techniques also suggest a phenomenological cause for these metal associations, e.g. gold and bismuth have linked metallogenesis at high temperatures and thus are best correlated at deposits that are deep and/or close to causative intrusions.

Jan 1, 2000

By S. R. Titley

Carbonate-hosted massive sulfide (60%) ores of the western Cordillera compose a distinct class of deposits although they vary widely in detail and perhaps genesis. They have been important sources of lead, zinc, copper, silver, gold, and more rarely, molybdenum, tin, and tungsten in complex mineral assemblages usually dominated by pyrite. They occur as concordant stratiform bodies, as discordant mantos, and as chimneys crossing tens of meters of section; many are associated with faults and breccia bodies. Environments of formation of carbonate hosts range from craton basin to shelf with ages from Proterozoic to Cretaceous; in many instances, dating has shown mineralization to be significantly younger than hosts. Temperatures of formation determined for many deposits are high (200°-400°) and many districts are centers of igneous activity manifested by dikes, sills, and stocks. However, direct cause and effect relationships have been difficult to establish. Many important problems attend the renewed interest and study of these deposits and include questions of metal-sulfur sources, metallization processes and histories, geological controls at all scales, and relationships to broader patterns of metallogeny.

Jan 1, 1985

By James J. Fallon

The industrial minerals industry is defined loosely and a specific list is presented. Criteria by which to judge prospects and examples are provided. General trends of the industry are observed.

Jan 1, 1984

By F. G. Heivilin

We are no longer short of viable Rare Earth deposits. As little as 2 years ago China mined and produced 97% ofthe world?s rare earths. Only a few deposits were in an advanced stage of exploration and development. Now Technical Metals Research (TMR) Gareth Hatch *5 reports that 347 deposits are being developed by 265 companies down from 440 on July 6th. Their Index of Advanced projects lists 45 projects in 14 countries. They will sustain the world for centuries to come and many good deposits are yet to be found. The problem is mining 14 elements in balance. Each of the deposits listing production in the chart has a unique set of minerals which they think will give them a cost advantage. Which of these will make it to production is a question. Most of the Advanced won?t be mined soon, but which ones? China is still in the driver?s seat in Light Rare Earth production (LREO) with one deposit with 35 million ton Baiyunebo deposit in Inner Mongolia which is part of a working iron ore deposit. The number of HREE deposits have been reduced and they attempting to eliminate unpermitted mines. This report will tell you what a Rare Earth is, how rare they are, why they are important, and where they are being developed which includes Australia, the United States, Africa, Greenland, Brazil and Canada.

Feb 27, 2013

By K. P. Black, G. W. Sevick, D. E. Hockley, K. S. Sexsmith, J. T. Chapman

Mineralogical analyses of carbonates in depyritized tailings and pyrite concentrate (from depyritization of the tailings) were completed as part of the tailings characterization for the Crandon Project, a massive sulfide deposit in northeastern Wisconsin. The mineralogical study was designed to determine the proportion of calcium and magnesium carbonates, and therefore the effective buffering capacity of carbonates in the tailings. The depyritized tailings are net acid consuming and will be stored in a surface tailings management area. The pyrite concentrate is net acid generating and will be used as backfill in the underground mine workings. The majority of carbonates in the depyritized tailings were ferroan dolomite containing 10 to 15% iron (by weight) and lesser amounts of siderite and magnesian siderite. The proportion of calcium and magnesium-rich carbonates corresponds to several independent tests of carbonate neutralization potential (CO3-NP) availability. The pyrite concentrate had less CO3-NP, indicating segregation of the carbonates during pyrite flotation. These carbonates reported higher iron contents, consistent with the relatively lower availability of CO3-NP in the pyrite concentrate.

Jan 1, 2002

By Paul R. Smith

The Colorado School of Mines Research Institute (CSMRI) was founded in 1949 to fill mining industry and government needs for minerals research and development. The operations of scores of mines, mills, and plants around the world are based on the results of work done by the Research Institute. Among other things, the Research Institute conducts studies in geology, mine planning, mineralogy, size reduction, minerals processing, and hydrometallurgical techniques in extractive metallurgy. Many CSMRI projects also involve energy and environmental considerations. What follows is a summary of some of the studies in which the Research Institute has been and is currently involved, as well as some comments on trends and developments in the industry.

Jan 2, 1982

By E. Sun

Tailings disposal is a significant consideration for the mining industry, with the majority of the ore processed in most mining operations ending up as tailings. Several tailings dam failure accidents have occurred during the past few years and mine tailings dam failures are occurring at relatively high rates. Tailings dam failure is disastrous with the serious damage and the loss of lives. To increase the tailings dam safety, a tailings dam monitoring and pre-alarm system (TDMPAS) based on the internet of things and cloud computing platform has been accomplished with the abilities of real-time monitoring of the saturated line, impounded water level, rain fall and the dam deformations etc. The TDMPAS has been applied in several mines in China and helped the mine engineers monitor the tailings dam safety and get warning information automatically and remotely in any kind of weather conditions. This work has been demonstrated the tailings dam monitoring and pre-alarm system (TDMPAS) is meaningful to monitor the tailings dam physical safety condition. The TDMPAS could be applied to monitor all the national tailings dams online in the future.

Jan 1, 2012

By B. V. Clingan

A practical application of recent design concepts makes it possible to design a column cell to fit a specific set of conditions. The design and operating parameters Of a column cell installation that replaced a conventional two stage copper flotation cleaning circuit at MAGMA COPPER COMPANY, SAN MANUEL, ARIZONA using these design concepts is described. A survey of other mineral processors using column cell technology was conducted. The results of this survey will also be discussed.

Jan 1, 1987

By M. A. Reyes, L. Yan

Heat and humidity buildup within refuge alternatives (RAs) may expose occupants to physiological hazards such as heat stress. The Mine Safety and Health Administration (MSHA) regulations require RAs in underground coal mines to provide a life-sustaining environment for miners trapped underground when escape is impossible. RAs are required to sustain life for 96 h while maintaining an apparent temperature (AT) below 95 °F (35 °C). The National Institute for Occupational Safety and Health (NIOSH) tested a 10-person tent-type RA, a 23-person tent-type RA, and a 6-person metal-type RA in its underground coal mine facilities to investigate the thermal environment over a 96-h period. The test results showed that mine air and mine strata temperatures surrounding an RA occupied by simulated miners (SMs) increased over the 96-h test period. The test results suggest that RA manufacturers should consider this increase in temperatures when calculating and evaluating RA components during surface and laboratory tests. The findings can equip stakeholders with additional considerations for calculating the interior heat and humidity temperature profiles for occupied RAs not tested in situ

Nov 22, 2019

By Donald E. Ranta

An ore zoning technique developed by Climax geologists during the past forty years has been used to contour drill-hole assay values on cross-sections for fourteen porphyry molybdenum deposits in western North America, including the Climax and Henderson orebodies. Detailed geological studies of these large, complex deposits are essential in determining ore controls, which are the factors most critical to the zoning of MoS2 assays and to conceptualizing geologic models. The technique provides a detailed representation of the size, shape, grade distribution, and geologic continuity of the individual deposits. It demands a disciplined approach and adheres to rigorous rules while maintaining flexibility for adaptation to widely varying geologic conditions. By defining the limits that guide and control manual, computer-assisted conventional, and geostatistical reserve estimates, it exerts a strong geologic influence on the estimation process. A combination of ore zoning and geostatistical analysis of molybdenum deposits produces a significantly more accurate, precise, and defendable geologic reserve estimate than other methods.

Jan 1, 1983

By Bruno Bussière, Michel Aubertin, Anne-Marie Dagenais, Johanne Cyr

A five steps remediation program was commissioned in 1998 for the acid generating Lorraine mine site, located in the Témiscamingue region, Quebec, Canada. It included, as the main expenditure, a cover with capillary barrier effects (CCBE) used to limit oxygen migration. After construction of the cover, instruments were installed on site to monitor the CCBE performance. Modified oxygen consumption tests were also done to measure the oxygen flux through the cover. Results from water content and suction data, measured from 1999 to 2003, show that the capillary barriers effects are effective and that the water retention layer stays near saturation throughout the years. Oxygen fluxes estimated from monthly water content measures are generally below 10 g/m2/year. Results from modified oxygen consumption tests made on the site give almost similar oxygen fluxes. A two dimension numerical model of the Lorraine mine site was also constructed to verify that mathematical models could predict realistically the in situ conditions on such a large scale site. Numerical results obtained for three years show a good concordance between measured and calculated values. The results obtained form these different evaluation methods for the performance of a CCBE concur and confirm the efficiency of this cover in limiting acid mine generation.

Jan 1, 2005

By Faruk Oksuz

The owners of large infrastructure projects are challenged on how to implement sound engineering and construction contracting strategies that address their prime expectations: a quality job, on time and within budget. With the increasing number of large engineering and construction projects worldwide, owners continue to search for alternative contracting strategies to address their risk, quality, sustainability (operability and performance), schedule, and budget concerns. Coupled with the shortage of resources, delays, political pressures, and other obstacles in procurement and negotiation processes, engineers and contractors are also looking for creative ways to optimize contract packaging strategies for efficient and successful project delivery. This paper compiles an array of decision making criteria and suggests a balanced evaluation, ranking and selection strategy in procurement of both engineering and construction services for large tunneling and other infrastructure projects. A number of owners? general preferences and viewpoints are discussed on large tunnel programs encompassing water and wastewater conveyance systems, pump stations and treatment facility upgrades. Contract packaging strategies and project phasing and segmenting alternatives for preliminary engineering, final design, construction management, and actual construction of facilities are featured for several large water and wastewater infrastructure projects. While the selection (and the relevant selection process and criteria) and performance of service providers, whether for engineering or construction, have profound effects on the outcome of any given project, this paper only examines strategies for con-tract packaging. More specifically, the authors evaluated case studies and developed a range of recommendations for packaging of large water and wastewater infrastructure projects with multiple components.

Jan 1, 2008

By Peter N. Calder

There is little doubt that the stability of both highwalls and spoil piles is essential to efficient strip mining. Accurate determination of the appropriate geotechnical parameters will pay dividends during mining, but only if the mine operation closely follows the engineering plans which have incorporated These factors. Productivity is invariably higher in mines where failure of highwalls and spoil piles does not occur. This is the result of the reduced rehandle and better working conditions found in stable mines. Control of the waste piles and highwalls also leads to better coal recover since failures can result in the burial of uncovered coal, which is then lost to mining. Safety is an important consideration. The importance of providing a safe working place for employees and of protecting costly mining equipment is hard to overemphasize. For miners, working in areas where instability exists, the degree of hazard involved in their occupation is increased particularly where night operations are involved. It is true, too, that there have been many cases where loading equipment has been buried and severely damaged by failures.

Jan 1, 1980

By J. B. Hadaway

The current limit to power transmission for grinding mills through one mill pinion is approximately 7,500kW. Above this power rating either twin pinion arrangements or Gearless drives are required. The SMTP concept was developed to overcome this limitation by using two pinions with a single large drive motor. The SMTP mill drive offers major advantages in capital cost and greatly simplifies plant layouts, while using an innovative adaptation of industry-proven single helical gearing. Through the use of a single motor, provision of variable speed drive is greatly simplified. The SMTP can also be used for significant power upgrades on existing mills.

Jan 1, 2001

By A. L. Mular

Si define la simulación digital y las técnicas de simulación son revisadas. La metodologia tipica conlleva la selección de modelos, el ajuste o reajuste de los datos primarios, la selección de una estrategia de acoplamiento, la valoración de la precisión del modelo en un sentido estadistico, y el desarrollo de estructura de simulación ejecutiva. La simulación sirve de ayuda para los ingenieros de procesos para evaluar la viabilidad de un esquema de flujo propuesto y el efecto de la modificación de un flujograma ya existente. Por otro lado, la simulación juega un papel importante en la optimación "off-line" y en la evaluación de estrategias de control de circuitos alternativos. Son presentados varios ejemplos para ilustrar estas utilizaciones para la simulación, incluyendo aplicaciones en los circuitos de trituración, circuitos de molienda y circuitos de flotación. Es de opinión de los autores que, dentro de la próxima década, las plantas de proceso de minerales serán estudiadas rutinariamente a través de una simulación digital durante las etapas preliminares de diseño. La simulación constituirá un importante componente en la toma de decisiones de un proceso.

Jan 1, 1982

By Stavros H. Constantopoulos

Mediterranean regions such as Greece, Turkey, Cyprus, Corsica and New Caledonia have experienced epidemics of malignant mesothelioma as a result of non-occupational, ??domestic?? exposure to tremolite asbestos and fibrous erionite. This exposure to tremolite asbestos and fibrous erionite is typified ??domestic?? due to its prevalence in regions with natural deposits of tremolite asbestos (or fibrous erionite) where the material from tremolite asbestos or fibrous erionite is used for domestic applications such as whitewashing. However, these exposures may be useful in examining the potential consequences of even small amounts of amphibole asbestos fibers in the ambient air. It can also elucidate the effects of fibers that behave like amphibole asbestos. However, this type of exposure is not useful for studying the potential effects of small amounts of asbestos in the ambient air of big cities due to the differing nature of the fiber types and modes of exposure between the regions. © 2008 Published by Elsevier Inc. Keywords: Tremolite asbestos; Erionite; Domestic; Environmental; Exposure

Jan 1, 2007