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By Jan W. Merks

"The settlements between mines and smelters are based on the mass of metal contained in concentrate lots. The mass of contained metal is a function of the wet mass of a lot, and its moisture content and metal grade while the variance of the mass of contained metal is a function of the same variables and their variances. Uncertainties in the measurement procedure applied to estimate each variable are quantified in terms of precision and bias. The absence of bias and an acceptable degree of precision are the keys to effective risk analysis and loss control.ISO Technical Committee 183-Copper, Lead and Zinc Sulfide Concentrates, has developed standard methods for sampling and weighing, estimating precision and testing for bias, the determination of mass loss on drying, the calculation of the mass of contained metal and its variance, and various analytical methods for major and minor metals. The variance for wet mass is calculated from the precision of the scale while the total variances of moisture and grade are estimated from pairs of interpenetrating primary samples. The variance of contained metal can be calculated either from mine data or from smelter data but the risk associated with the settlement is largely determined by the absence or presence of bias and the variance of differences between exchange assays.ISO/TC 183 does not deal with precision and bias for exchange assays but is developing guidelines to determine realistic splitting limits. Given that the exchange of assays between mines and smelters accounts for a large part of the risk associated with the settlement, precision and bias for exchange assays should be measured and monitored. The need for umpire services can be reduced by applying statistical quality control (SQC).Calibrating static scales, moisture balances and analytical balances, bias testing of sampling methods and sample preparation procedures, estimating the variance of a single variable or the variance of a function that a set of variables defines, and monitoring precision and bias for exchange assays, are the quintessence of metrology, the science of measurement, when applied in mining and metallurgy."

Jan 1, 1995

By Tim Brick, Peter Jewell, Stephen Thompson, Simon Morgan

The $980m (€750m) Dublin Port Tunnel, Europe’s biggest urban highway tunnel project, was opened in December 2006. The culmination of this immense scheme is set to transform the environment, mobility and road safety of Ireland’s capital city. This paper summarizes the key aspects of a project linking both sequential and parallel construction of individual tunnels and describes various approaches to bored, mined and pre-support cut-and-cover tunneling in a wide variety of ground types and depth of cover. Examples of innovative approaches to deal with structural and geotechnical problems while maintaining full operation of both road and rail traffic and the integrity of properties in a dense urban corridor are described.

Jan 1, 2007

By Richard F. Sliwoski

The Virginia State Capitol was designed by Thomas Jefferson and constructed in 1785. The Capitol is of great historic and architectural significance to not only the Commonwealth of Virginia but to the nation. It is the oldest operating Capitol in the U.S. and required a total restoration/renovation as well as an expansion to continue to remain functional. Site conditions dictated that the expansion (a new visitor center) be placed underground on the south side of the Capitol building, requiring a 40-foot deep excavation approximately 5 feet from the Building. Because of its historic significance, every measure had to be taken to ensure the safety and function of the Capitol during construction. The construction techniques that were used to make the deep excavation and protect the historic Capitol included a tied back concrete slurry wall, jet grouting, compensation grouting, and instrumentation monitoring. This paper describes the history of the Capitol building, the techniques that were employed for construction of the deep excavation, results of the latest movement monitoring, and factors contributing to meeting the restrictive movement goals.

Jan 1, 2006

By Lisa M. Splitter

Drilled displacement piles were constructed as the foundation for a proposed 10-story building in San Francisco, California. At the study location, the stratigraphy consists of 14 to 21 feet of fill and 13 to 23 feet of weak, compressible clay (?Bay Mud?), underlain by dense sand, stiff clay, and bedrock. A sensitive critical public utility is located within approximately 20 feet of the constructed piles along one side of the building. The utility pipeline is entirely within the Bay Mud where it is adjacent to the project site. The San Francisco Public Utilities Commission (SFPUC) developed limits on the allowable total and differential movement of the utility pipeline. As requested by the SFPUC, inclinometers and piezometers were installed to monitor the soil movement and pore pressure increases in the Bay Mud caused by the installation of drilled displacement piles. Action levels were set such that if displacement and/or pore pressures reached an action level, the installation methodology would be reevaluated and additional measures to reduce these effects would be implemented. This paper will present the sequence of pile installation near the pipeline and monitoring points, and the data collected from inclinometers and piezometers at variable depths and distances from the piles. The data will highlight the build-up and dissipation of pore pressures over time and the displacement of Bay Mud caused by the pile installation. The conclusions of the study are useful in determining sequencing, spacing, predrilling, and other measures that can be implemented to decrease the displacement potential and pore pressure build-up in soft clays.

Jan 1, 2009

Reasons are given for the seemingly excessive public concern with taxation of the mineral industry. Optimality of mineral extraction is a concept that requires careful definition in terms of one or more objectives. Once defined, the impact of taxation upon optimal mineral extraction may be studied; findings from earlier work on this topic are presented for two basically different cases. In conclusion it is observed that the pursuit of optimality requires the availability of highly skilled engineers; in the event of a large-scale mineral development it is this resource that is probably scarcest of all.

Jan 1, 1983

By Andrew Finney

INTRODUCTION The Sacramento Regional County Sanitation District (SRCSD) serves unincorporated areas of Sacramento County, parts of the cities of Sacramento and Folsom, and the cities of Citrus Heights, West Sacramento, Rancho Cordova, and Elk Grove. SRCSD maintains 145 kilometers (km) (90 miles) of interceptors that convey a combined total of 0.6 million meters3 per day (160 million gallons per day) or more of waste-water, with additional miles of sewer interceptors that are scheduled to be built by 2020. Wastewater is conveyed to the Sacramento Regional Wastewater Treatment Plant in the southwestern portion of the County, also managed and operated by SRCSD, in interceptors with diameters as large as 3.0 m (120 inches.) As part of its overall expansion program, SRCSD has constructed a number of major interceptors over the last few years with tunneling methods due to concerns associated with either the impacts of open cut construction in an urban environment (traffic, safety, noise, environmental concerns) or the need to achieve a crossing of a stream, river, or transportation corridor. This paper focuses on a specific issue that affected construction of the Upper Northwest Interceptor (UNWI) Sections 3&4 project, located at the northern limit of the SRCSD service boundary and within the limits of the City of Sacramento. This project involved the construction of 3.2 km (2 miles) of 2.1-meter (84-inch) and 2.4 km (1.5 miles) of 1.7-meter (66-inch) diameter reinforced concrete pipe (RCP) using MTBM, EPBM, and 3.3-meter (130-inch) two-pass TBM methods. The owner elected to install the RCP using tunneling for a number of reasons including a desire to avoid traffic impacts in a dense urban corridor, to minimize disturbance to the neighborhood, and to avoid potential dewatering-induced settlement issues along the western one-third of the project. For the western portion of the alignment the 2.1-meter (84-inch) reinforced concrete interceptor pipe was to be installed using a 2.7-meter (105-inch) earth pressure balance machine (EPBM). No external dewatering of shafts or tunnels was permitted for reasons of concern about settlement, discussed previously. At the intersection of Elkhorn Boulevard and Natomas Boulevard (at the extreme northwest corner of the project) the 2.7-meter (105-inch) EPBM tunneled past a recently constructed 11-million liter (3-million gallon) water storage reservoir, passing within 3 meters (10 feet) of the tank?s shallow foundation while tunneling through clean sands with a shallow groundwater table. The paper will discuss the implemented solution to mitigate additional settlement risk that was developed as a joint collaboration between the owner, CM, designer, and contractor.

By Zachary Mayer

Agenda ? Kidd Mine ? Background ? Problem & Opportunity ? Challenges associated to depth - Production Rates - Productive Work Time - Operational Delays - Transfer Levels - Mucking Time - Impact on Hoist ? LHD Automation ? Sandvik AutoMine Lite ? Expected Benefits Kidd Mine - Background ? Located in Northern Ontario, Canada ? Underground base metal mine operating since 1966 ? Total 148 Mt mined (2.31% Cu, 6.08% Zn, 75 gpt Ag) ? 2.35 Mt/Y from stopes as deep as 9500 ft (2.9km) below surface ? Mining method: blasthole open stoping ? Mine/Mill: 1263 employees and contractors ? 2012 National John T. Ryan Safety Award

Aug 1, 2013

By Adam Wright

"Les Mines Selbaie have been producing copper and zinc concentrates from the A-1 ore zone since 1986. This paper reviews major developments in flotation practice over that period. Firstly, ore blending strategies for Selbaie's non-homogeneous polymetallic ore are discussed. The evolution of reagent use is then reviewed, focussing on copper collector trials. A description of Selbaie's flotation columns follows. Finally, past and future developments for process control are outlined.Depuis 1986, Les Mines Selbaie produisent du concentré de cuivre et de zinc provenant de la zone A-1. Cette conférence présente !es développements majeurs en flottation qui ont eu lieu depuis ce temps. Premièrement, la stratégie du mélange de minerai non homogène polymétallique est présentée. L'évolution des réactifs utilises est démontrée, particulièrement !es collecteurs de cuivre. Par la suite !es colonnes de flottation sont presénteés et finalement !es développements futurs ainsi que ceux qui ont eu lieu dans le contrille de procédé sont expliqués.1.0 INTRODUCTIONLes Mines Selbaie, wholly owned by Billiton Metals Canada Inc., is currently mining and processing ore from a polymetallic surface deposit located 288 km northwest of Val D'or, Quebec (fig. 1). The mine produces copper concentrates containing gold and silver as well as zinc concentrates containing silver. 8000 dmt/day of ore is crushed and ground to 80% passing 49 µm, prior to processing by conventional copper/zinc differential flotation. The flotation circuits consist of both conventional and column cells (fig. 2). Detailed descriptions of the mill are available elsewhere in the literature (8,9)."

Jan 1, 1995

By Sergio N. Monteiro

Polymeric matrix composites with dispersed hard particles are being as wear resistant tools in industrial polishing operations. In the present work, the microstructure of epoxy composites with different amounts of embedded diamond particles, up to 30 wt.%, was investigated for the effect on fracture characteristics. It was found that the introduction of diamond particles promoted an increase the porosity of the epoxy matrix. Moreover, the particle morphology associated with a non-uniform distribution within the matrix was responsible for the nucleation of cracks that caused rupture of the composites.

Jan 1, 2006

By N. Hanief

This research involves the investigation of phase transformations in the platinum-chromium coated system. Single-layer 0.1 µm platinum coatings were deposited via electron beam deposition on 99.98 percent pure chromium substrates. Specimens were subjected to systematic heat treatment in a vacuum furnace at 900°C for up to 20 hours. Phase formation and the changes in surface morphology were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Both CrPt and Cr3Pt phases are formed during heat treatment for different times at 900°C. Significant changes in the morphology of this coated system were detected after heat treatment at 900°C for 20 hours.

Jan 1, 2012

By H. F. Coward, G. W. Jones

"IntroductionIn the course of an investigation on the influence of black damp (a mix of nitrogen and carbon dioxide) on the limits of inflammability of fire damp (methane) in air, some new information was obtained concerning the factors that determine whether or not a gas mixture is capable of self-propagation of flame. Volume for volume, carbon dioxide exceeds nitrogen in its extinctive action on flame, an effect which is generally attributed to the higher molecular heat capacity of the former. Argon, a as of lesser heat capacity than either, proved to Lave less extinctive notion. If, as seemed likely, the extinctive action of a chemically inert gas could be attributed entirely to its heat capacity, then helium should behave like argon; equal volumes of these two oases should exhibit equal extinctive action, for their molecular heat capacities are nearly identical at laboratory temperatures and, in all probability, remain constant up to and beyond flame temperatures. The experiments reported here show, however, that helium has proved to be more extinctive of methane flames than argon.Method Used in ExperimentsThe limits of inflammability of methane, in various ""atmospheres"" composed of mixture of air with one or other of the diluent were determined in a vertical glass tube, 6 feet long and 2 inches in diameter. The lower end of the tube was opened by sliding away a ground-glass joint and the flame of a small spirit lamp was immediately passed across the aperture. The tube was sufficiently long to enable observers to judge whether a flame was self-propagation for if a mixture were incapable of continued self-propagation pf flame, the lamp of flame formel above the source of ignition was extinguished within feet of its passage up the tube."

Jun 1, 1926

By S. Haggarty

"Wholly owned by Corona Corporation, the Nickel Plate Mine is an open pit, gold mining operation located near Hedley, 50 km west of Penticton, in Southern British Columbia.Milling capacity is 3,400 SDT /Day with an average feed grade of 0.080 Oz Au/Ton. Gold processing involves three stage grinding including tertiary pebble milling, two stage cyanide leaching and filtering and Merrill-Crowe zinc precipitation.A summary of process improvements required to increase milling capacity above the initial design tonnage of 2, 700 SDT /Day are described -Installation of a 42"" x 65"" Allis Chalmers Gyratory crusher replacing a 42"" x 48"" Traylor jaw crusher.Installation of polyurethane screen panels replacing woven wire cloths on an 8' x 20 ft triple deck screen.Installation of a hopper clarifier to reduce filtrate turbidity.Automated control of solution balancing and effluent treatment circuits.INTRODUCTIONThis paper describes mining and milling practices at the Nickel Plate Mine and details post start-up process modifications which were required to attain design tonnage.Wholly owned by Corona Corporation, the Nickel Plate Mine is an open pit, gold mining operation located near Hedley, 50 km west of Penticton, in Southern British Columbia.Mining capacity from the open pit is approximately 32,000 TPD with an average waste/ore ratio of 8.4:1.Milling capacity is 3,400 SOT/Day, above initial design tonnage of 2,700 SOT/Day. Feed grade averages 0.08 Oz Au per ton yielding 85,000 troy ounces of gold per year."

Jan 1, 1991

By Brendan Henry

The Canada Line is a 19km long automated light rapid transit system with 16 stations in Vancouver, BC, Canada. The Concession was awarded to InTransitBC to design, build, partially finance, operate, and maintain the system for 35 years. The project must be complete by November 2009 to be ready for the 2010 Winter Olympics to be held in Vancouver and Whistler, BC. The bored tunnel section consists of 2.45 km of twin bored tunnel and 3 stations. The station work is limited to the excavations and temporary support necessary to facilitate the bored tunnel works. A joint venture between SNC-Lavalin Constructors Pacific and SELI (SSJV) has recently completed the design and construction of this section. Work for the bored tunnel commenced in November 2005 with shoring and excavation works for the tunnelling operations pit that will become Olympic Village Station and will be completed in the spring of 2008. The tunnels were driven with a 6m diameter Earth Pressure Balance Tunnel Boring Machine (EPBM) and lined with 250mm thick, 5.3m diameter precast concrete segments. Seven hundred and fifty meters of each tunnel were driven through glacial and interglacial deposits of sand, silt, and clay with granitic boulders. The paper discusses the challenges faced in negotiating these soils which contained unforeseen geological conditions. These conditions were overcome by developing a systematic approach to Risk Management that included thorough risk assessments, regular risk management meetings with the participation of two of the world?s leading EPBM experts, Professor Eisenstein and Professor Kovári, and by the ability of the construction team to effectively analyze and mitigate problems.

Jan 1, 2008

By Hakan Gurgenli

Many coal seams have weak shale immediate roofs that cause ground control problems. Therefore, it is important to know the properties of these shales so that preventive measures can be developed in advance. However, it is sometimes hard to understand this rock type due to its unpredictable behavior. A good example of this situation is found in two shale coal mine roofs located in the Illinois coal basin (Herrin No. 6 seam). Although, these mines are located very close to each other, one of them has many roof falls, whereas the other has no measurable ground control problems. The aim of this paper is to explain why and how one shale roof behaves worse than the other. Laboratory tests, including point load strength index, slake durability index, moisture activity index, weatherability index, water content determination, swelling strain and x-ray diffraction tests were performed to analyze the shale properties. According to these analyses, some useful correlations were found between the engineering properties, moisture-sensitivity indices, and weathering properties. Finally, mine and support design considerations based on the test results were discussed and recommendations to prevent ground control problems were given.

Jan 1, 2006

By Manqiu Xu

"Ore grades are decreasing and ore deposits are becoming more complex. In order to make a sound economical decision about a mining project, metallurgical testwork must be carried out. A few large “representative” samples cannot represent the metallurgy of a large ore body and a large number of samples reflecting variation in ore head grades and in mineralization types must be obtained for proper metallurgical studies, including flowsheet development for a greenfield project. A relationship can be established between the recovery of valuable minerals and ore grade for each mineralization type. This relationship can be used to establish a correlation between values recoverable and values contained in the ore body that can include multiple pay metals. With this information, a sound economical decision can be made about the viability of a large mining development project.INTRODUCTIONThe demand for minerals today is historically high as many countries are being rapidly industrialized. The supply for these minerals is not necessarily running short. However, it is widely accepted that the world today is running short of the easy to mine and easy to process ore deposits. As ore grade is decreasing and ore mineralogy is becoming more complex, metallurgical testing must be fully conducted in order to make a sound economical decision about a mining project. For a high-grade and high-quality deposit, it is hard not to make a good profit even with low metal prices. For a low-grade and hard to process deposit, the profit margin is much lower and is dependent on the throughput and the recovery of valuable minerals. The recovery of valuable minerals is a function of ore grade and mineralogy and it must be experimentally determined for a given processing option.At Vale Base Metals Technology Development, metallurgical testing for an existing operation or brownfield project is termed as Ore Evaluation, while metallurgical testing for a greenfield project is termed as Flowsheet Development (Xu, 2011). In the past, metallurgical testing involved a few large composite samples for lab and pilot plant testwork. As ore deposit becomes less homogeneous and more variable, a few large composite samples cannot represent the metallurgy of a large ore body. In addition, useful information about the deposit such as zones of “impurities” or floatable rock minerals would not be obtained. Different processing strategies could have been developed if the locations and sizes of these zones were known in advance. For proper metallurgical studies, a large number of samples reflecting variation in ore head grades and in ore mineralization types must be used. A relationship can be established between the recovery of valuable minerals and ore grade for each mineralization type. This relationship can be used to estimate values recoverable in the ore body that can include multiple pay metals. Ultimately, the recovery verses ore grade relationship will be used in business decision-making."

Jan 1, 2013

By David J. Hatem

Tunnels and underground projects are inherently more risky than vertical projects, which typically utilize more conventional design and construction approaches and are undertaken in the context of relatively ascertained and defined conditions. On tunnel and under-ground projects, there are a host of special risk factors, including unknowns and uncertainties as to the physical and behavioral characteristics of the ground, the inextricable interdependence and necessary interaction of design decisions and construction means and methods with those ground conditions as well as the manner in which risks are allocated among project participants for un-anticipated subsurface conditions. Public-private partnerships (PPP) projects, in their own respects (and independent of any major subsurface component), pose significant risk for all private sector participants. The main driver of owners to procure projects using PPP is financial, as often all, or substantially all, of the design and construction risk are transferred to the private sector consortium, including the design-build (D-B) team. For a concerning number of those public owners, that risk transfer regime includes rather onerous and aggressive contractual terms that allocate to the private sector participants substantially all risks associated with the encountering of unanticipated subsurface conditions. These aggressive risk allocation provisions, while directly impacting project participants upstream of the consulting engineer, have an indirect and corresponding risk intensifying effect upon consulting engineer professional liability exposure. There are many factors that result in increased professional liability exposure for consulting engineers involved in PPP projects. The more prominent and prevalent of those factors fall into the following categories:

By Charles H. Rich

This Bureau of Mines report is an expansion and update of Information Circular 8719 and comprises maps and tables listing the name, location, and other pertinent data concerning certain fuel-related projects. The maps show the locations of the planned or proposed facilities. The tables include information on projects involving the proposed or planned development of fuel resources, as well as the development of storage, transportation, and conversion facilities. The report covers the 24 States west of the Mississippi River including Alaska and Hawaii. Of the 808 projects for which information is provided, 219 concern coal mines, 246 concern electric generating plants, and 115 concern uranium mines; Energy Supply and Environmental Coordination Act coal conversion notices are also included. Because of the dynamic nature of the energy industry, many uncertainties exist and some of the listed projects may never become realities. Also, no attempt has been made to determine the degree of certainty or viability of each project.

Jan 1, 1978

By S. Banisi, H. R. Iran-Manesh, M. R. Shayestefar, H. Shekarchyan

"Flotation circuit of the Sarcheshmeh copper mine processes 41,000 t/d of ore at 0.9% Cu. Chalcopyrite and chalcocite are the main copper bearing minerals which are concentrated in three stages of roughing, cleaning and recleaning. Due to major changes in the reagent addition regime, make-up balls combination, and throughput to the primary mills an increase of 2.6% (from 87.2% to 89.8%) in the sulfide copper recovery was obtained during a period of six years. In order to investigate a rather large variation of monthly recovery (i.e., from 89.0 to 91.2%) of the plant after implementation of the changes, a study was undertaken to trace mineralogically possible causes of such a behavior. During a five-month period, monthly composite samples of feed and tailings of the flotation circuit were taken. At the first stage, the polished sample preparation method and the mineral counting procedure were optimized through a detailed study. Liberation degrees and types of locking of valuable minerals in both streams were determined in three size intervals of +75, +38 and –38 microns. It was found that for both recovery levels (i.e., 89% and 91.2%), there was no significant difference in the liberation degrees of valuable minerals in the flotation feed; the average liberation degree was 57.1% with a standard deviation of 3.1%. On the other hand, in the case of high recovery level (i.e., 91.2%) there was a reduction of 15% in the amount of free valuable minerals in the tailings stream. The highest reduction was found for the -38 micron size range in particular for chalcocite. It was concluded that compared to the grinding circuit the change in the flotation circuit had the significant effect on the plant recovery increase.INTRODUCTIONThe Sarcheshmeh copper ore body contains 1 billion tonnes averaging 0.90 % copper and 0.03 % molybdenum. It is located southeast of Iran and currently processes 41,000 t/d of ore. The concentrator has been in operation since 1982. Last year, the concentrator produced 130,000 tonnes of copper and 4,000 tonnes of molybednite concentrate. An expansion to the plant which will increase the throughput by 50% is under construction and will be effective in 2003.After three stages of crushing, the ore with a F80 of 12.7 mm is fed to 8 parallel ball mills in closed circuit with cyclones to produce a product 70% finer than 75 microns. The concentrate of the first stage of flotation is reground and the tailings constitute the main component of the plant final tailings. A concentrate with an average grade of 30.5% Cu is obtained after cleaning and re-cleaning stages. At the present time, the average sulfide copper recovery of the plant is 89.8% which varies depending on the operating conditions and ore type."

Jan 1, 2003

By K. Boakye

This paper presents the results of a review of historic blast design practices at the Dragon Products Company, LLC (Dragon) Quarry Operation, along with the results of two different blast design vibration monitoring programs. A blast pattern design modification was initiated to determine if production volume per shot could be increased and highwall instability could be decreased. A vibration monitoring program was undertaken to investigate peak particle velocity (PPV) and relate the data to the blastability of the jointed onsite rock mass, utilizing the relationship between PPV and dynamic stress and strain. The Dragon Quarry Operation has historically used a 6-in. diameter, 14-ft by 14-ft production blast pattern, with blast holes loaded manually using cartridge style explosive products. In 2011, Quarry Operations introduced a 6-in diameter, 16-ft by 16-ft production blasting pattern, using pre-mixed, truck-loaded, bulk emulsion/ammonium nitrate/fuel oil (ANFO) blends. This paper summarizes the results of the blast design modifications, the results of the vibration monitoring data, and describes how production blasting and excavation at the Dragon Quarry has benefited from such modifications.

Feb 27, 2013

By Charlie Brumbaugh

Antarctica with its diverse conditions such as severe cold, high winds, rock and ice structure and limited explosives available posed many obstacles. This paper will give an overall view of the methods used to overcome these obstacles on a daily basis on the highest, driest, coldest continent on earth.

Jan 1, 2000