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By T. C. Eisele

The use of column flotation was considered for the ?reverse flotation? of iron ore, where the gangue (quartz) was recovered in the froth product. This use of the froth for carrying the gangue mineral rather than carrying the valuable concentrate significantly changes the operational requirements of the column. The objective of this work was to determine which of several column flotation technologies would be most suitable for this type of flotation operation. Studies were carried out using both the Jameson column and the Deister column. Comparative results are presented that show the capabilities of both column types in this application relative to conventional Wemco flotation cells. Columns were demonstrated to have grade-recovery performance superior to what could be achieved with conventional cells. Two-stage flotation with the columns could produce a concentrate that was up to 70.2% Fe at 87.5% iron recovery, compared to 70.4% Fe at only 77.7% iron recovery for four stages of flotation in conventional cells. It was shown to be particularly important to operate the columns to recover a maximum of the quartz gangue into the froth. It was noted that there are often problems in scale-up of laboratory columns to plant scale, because the increase in height and the decrease in the ratio of height to diameter at the larger scale allows more axial mixing and bubble coalescence, both of which degrade the column performance. Horizontal baffling was shown to improve column performance by reducing axial mixing and breaking up large bubbles, and so the use of such baffles in the reverse flotation application was investigated.

Jan 1, 2007

By William R. Yernberg

The “China & East Asia Mineral and Energy Re-sources Symposium — CEAR 2000” was held Jan. 23-26, 2000 in Denver, CO. Conference sponsors included Resources and Technology Symposia of Colorado and the Asian Journal of Mining. The meeting was attended by representatives from China, Japan, Mongolia, Korea, eastern Russia (Siberia) and the United States. The US attendees consisted of interested parties from mining and energy companies, financial institutions, consultants and government agencies. In his opening statements, L. Maness, Jr., president of Resources and Technology Symposia of Colorado, said that the “goal of the conference was to make jobs and friendships and to introduce people to each other.” The conference provided an opportunity for Western mining interests, including mining companies and investors, to meet with government agencies from both sides of the Pacific.

Jan 1, 2000

By M. D. Khattar

Problems discussed concern encountering of high temperatures [up to 66°C] and heavy flow of water [150 L.P.S] during the construction of the 10.15 MØH.R.T. for the 2500 MW Nathpa Jhakri Hydro Power Project in the Himalayas(India). Over a length of 2500 M progress of work got seriously affected resulting in excessive time for completion - two years [max. monthly progress achieved was 178 M [Heading]. Many innovative and simple steps were taken to complete the work in these inhospitable environs affecting working of both men and machines. Also it meant a review of the design of concrete lining. Other geological conditions affecting the progress are also described.

Jan 1, 1999

By Hyung-woo Kim, Sup Hong, Sung-Soo Kim, Chang-Ho Lee

A deep-seabed integrated mining system, which consists of four subsystems such as riser pipe, buffer, flexible riser, and tracked vehicles, is presented in Figure 1. In order to collect more manganese nodules, multiple tracked vehicle systems should be used in a deep-seabed integrated mining system.

Sep 1, 2014

By David M. Jurich, Randy J. Essex, Alex de Aboitiz

An Automated People Mover (APM) transit system is planned for the growing Phoenix Sky Harbor International Airport. The APM will improve passenger movements between the terminals, and provide a link to parking facilities, a new rental car facility, and the planned metro Light Rail. The underground works will include shallow twin bored tunnels, taxiway crossings, and underground stations constructed beneath critical airport facilities. Challenging soft ground conditions will require extensive underpinning and ground improvements. Design is underway, and construction is scheduled to begin in 2007 with project completion in 2015. The owner’s planned delivery method for the APM Project will be Construction Manager at Risk (CMAR) with a Guaranteed Maximum Price.

Jan 1, 2005

By C. A. Young, J. D. Miller

The surface chemistry of the calcite/oleate flotation system was examined by in-situ FT-NIR/IRS. Spectra of combination and overtone bands of aliphatic stretching vibrations revealed gauche/trans conformational changes that occurred solely as a function of temperature. The conformational changes were attributed to the simple "melting" behavior associated with phase transitions. It was concluded that chemisorbed oleate at calcite surfaces is gel-like at temperatures below 22oC, resembles a coagel between 22oC and 31oC, and becomes micelle-like at temperatures above 31oC. By comparison, chemisorbed oleate at fluorite surfaces also undergoes these phase transitions but is additionally dependent on adsorption density. The conformational changes were observed at high chemisorption densities (> 2.0x10-10 mol/cm2) and attributed to molecular forces, primarily van der Waal's interactive forces, among neighboring chemisorbed oleate molecules. Similar analysis of in-situ FT-NIR/IRS spectra of surface-precipitated calcium dioleate at calcite surfaces did not exhibit this behavior thereby confirming that surface-precipitated calcium dioleate remains in an all-trans conformation. The results help explain why surface polymerization is not observed at calcite surfaces but is observed at fluorite surfaces.

Jan 1, 2002

By Michael Lenz

Predictive maintenance technologies including vibration analysis, tribology, infrared thermography, ultrasonic detection, and electrical measurements have been applied to large electric mining shovels. The predictive program was initiated on the P&H Model 2300 and 4100 electric shovels. The utilization of these technologies has shown the potential for improving electric mining shovel availability and minimizing maintenance costs. Predictive technologies provide the tools to assess machinery condition. Availability is enhanced by the condition based planning of component replacement. Maintenance costs are minimized by focusing resources through condition based prioritization.

Feb 24, 1997

By A. Broussaud, J. D. McKay

Benefits analysis of adaptive Expert control systems operating at plants in Africa and the United States are presented. Proper statistical tools and techniques are discussed. Technical and practical pitfalls of strategy comparison are also presented and illustrated with from published data. Advantages and disadvantages of a “Pay for Performance” approach to a project are reviewed.

Jan 1, 2001

By Vojtech Gall

Pre-support measures for urban tunneling have seen a substantial development in the recent past. Ground improvement techniques, pipe-arch and spiling methods now allow for non-disruptive tunneling at very shallow depths under sensitive structures, rail tracks and roadways. The paper presents experience gained on national and international projects built over the past decade that represent case histories and therefore may be used as guidance for the development of similar solutions for future tunneling projects at shallow depths. Reference projects include tunnels for the Washington, DC Metro, London Underground, Dulles Inter-national Airport, Busway tunnels in Boston and the Ft. Canning Tunnel in Singapore.

Jan 1, 2008

By Anna Sukhanova, Svetlana Babaeva, Sergey Andreev, Victor Beltenev

"The Zenith-Victoria /1/ and Jubileynoye /2/ hydrothermal fields have symmetrical structural position on the Mid Atlantic Ridge (Fig. 1). In order to compare the evolution of hydrothermal systems, we conducted mineralogical and geochemical studies of SMS from both sites.Radiochemical and geochemical investigations of massive sulfides of the Zenith-Victoria field distinguishes three major stages of evolution: initial, interim and final represented by Fe-S, Cu-Fe and Zn-Fe types of SMS respectively /3/. In this talk, we describe the results of geochemical analysis of massive sulfides from the Zenith-Victoria field. Geochemical varieties of SMS are considered to be indicators of the evolutionary stages of the hydrothermal system."

Sep 1, 2014

By Desiree Willis

Disc cutters have determined excavation rates of rock tunneling projects for more than 50 years. First developed in 1956 by James S. Robbins, disc cutters (then 279 mm or 11 in. in diameter) were used to bore limestone of 190 MPa (27,500 psi) unconfined compressive strength (UCS) and were loaded with 7.12 t (15,700 lbs) each. Modern cutters have reached up to 508 mm (20 in.) in diameter and are typically loaded with up to 31.7 t (70,000 lb) to economically bore through the hardest of rock up to plus 400 MPa (60,000 psi) UCS. New developments, such as larger cutter diameters, are geared to increasing the bearing capacity and wear life of the cutting structure. This, in turn, increases cutter life, cutter load and cutter penetration. Disc cutters have also been re-designed on a small scale for use in hard-rock utility installations. Additional variables also affect the three factors, including cutter spacing on the cutterhead, cutterhead diameter and cutter materials.

Jan 1, 2007

By J. D. Miller, C. L. Lin

In the processing industries, it is well known that particle shape is an important factor which determines the behavior of particulate systems. For example, system properties of technological significance including rheology, suspension stability, agglomeration, packing, permeability…etc, are affected by particle shape. In this regard, characterization and analysis of particle shape is essential for more detailed understanding and improved development of particulate processes. In general, it is clear that the behavior of these systems depends on the statistical characteristics of particle shape. Remarkably few techniques exist to predict the mechanical and hydrodynamic behavior of an irregularly shaped particle or a population of irregularly shaped particles for that matter. The lack of models and correlations can be attributed to the wide variety and complexity of particle shapes, the difficulty of defining shape descriptors suitable for modeling, the limitations of measuring shape, and the lack of classifying techniques to characterize particle shape. In this paper, we present information on how 3D particle shape can be measured, characterized, and analyzed using cone-beam X-ray microtomography (XMT).

Jan 1, 2005

The La Colosa, Colombia porphyry gold deposit is currently in the pre-feasibility stage. This large deposit has many types of gold mineralization: native gold, electrum, and tellurides. These variations in the gold mineralization lead to variability in the gold recovery. The final process flowsheet may include gravity concentration with cyanide leaching. Metallurgical testwork is utilized to identify the zones of ore that may be problematic to recover. To help select the samples that represent the fluctuating variability zones, geometallurgical models are constructed using mineralogy and geology data. These zones are then wireframed and compared to the geological and structural models for spatial correlation. Samples for the variability testwork will be selected from these different zones to identify and analyse the effect the different gold mineralization types have on the recovery. By using geometallurgy to aid in the sample selection for metallurgical testwork, the variability in the ore body can be understood and constrained to aid in process optimization.

Feb 27, 2013

Accurately estimating load distributions and ground responses around underground openings play a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the loads that will be carried by them, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses to be used in pillar design. The empirical methods are based on equations derived from large databases of various case studies. They are implemented in government-approved design tools and are widely used. There are also analytical and numerical techniques used for more detailed analysis of the induced loads. In this study, two different longwall mines with different panel width-to-depth ratios are analyzed using different methods. The empirical method used in the analysis is the square decay stress function that uses the abutment angle concept, implemented in pillar design software developed by the National Institute for Occupational Safety and Health (NIOSH). The first numerical method used in the analysis is a displacement-discontinuity (DD) variation of the boundaryelement method, LaModel, which utilizes the laminated overburden model (Heasley, 1998).

Jan 7, 2020

By Michael S. Kucker, Stuart Warren, Robert A. Robinson, Michael J. Lehnen, David McAllister

Geotechnical conditions exposed by the phased exploration programs have had a major impact on the selection of excavation and support methods, dewatering requirements, size of openings, vertical alignment, and estimated cost of construction for the Beacon Hill Tunnel and Station section of the “Link” Light Rail. Beacon Hill is comprised of a very complex glacial geology, including numerous slickensided fractures, injected sand dikes, and multiple perched groundwater levels as revealed by a phased boring program and exposed in a test shaft. The Geotechnical Baseline Report (GBR) presents this complex geology along with a “tool box” of alternative additional support systems to accommodate the varying ground conditions during construction of the station excavation. Additional explorations will also be accomplished during construction to further refine the geotechnical interpretations and provide an opportunity to use pro-active ground improvement techniques to optimize the station excavation and support requirements.

Jan 1, 2005

By A. A. El-Midany

Traditionally, the choice amongst different upgrading techniques or in finding the optimum operating conditions for a given upgrading technology depends on whether one is looking at the grade or the recovery of the valuable mineral in the concentrate. In fact, the conclusions are not usually the same. This is because the best technique or optimum operating conditions for the highest grade are not the same as the conditions to achieve the maxi-mum recovery. Therefore, a unique measure that takes into consideration both grade and recovery is urgently needed. Finding such a measure is the objective of this paper. A proposed measure provides a selectivity index in the range of 0 to 1, where 0 is no selectivity and 1 is ideal selectivity. The index can be obtained by plotting the so-called Fuerstenau upgrading curve, which relates the recoveries of the components in products of separation and a running regression applying a one-parameter equation. The measure was applied to assess the selectivity of selective flocculation under different operating conditions when used as a sensitive upgrading technique for ultrafine ground ores. After applying the proposed selectivity measure in the case of the selective flocculation of ultrafine Egyptian iron ore without the addition of cations, it was found that the optimum conditions are pH 11, 1 kg/t sodium silicate and 0.4 kg/t potato starch with a selectivity index of 0.55. With the addition of cations, the optimum conditions were found to be pH 11, 1 kg/t sodium silicate and 2 kg/t potato starch with a selectivity index of 0.65. It should be noted that determining these optimum conditions using the traditional grade or recovery measures was highly ambiguous.

Jan 1, 2008

By A. A. El-Midany, R. M. Farag, A. M. Salem, S. E. El-Mofty

Bentonite represents one of the main players in the stability of the drilling mud. Its particle size and particle size distribution affect the physical properties of the drilling mud especially the rheological properties. Therefore, a specific particle size distribution was recommended by American Petroleum Institute (API) for use in drilling mud. To clarify the effect of individual size and size distribution, in this study, the bentonite sample was classified into different size fractions. Each size fraction was tested separately in terms of controlling properties such as filtration loss, plastic viscosity, gel strength, cake thickness, and packing density. The effect of each size fraction on the rheological properties of the suspension was correlated to the behavior of the whole particle size distribution in the bentonite sample. The results indicate that the coarser the particles, the higher the rheological properties; in this case, the API mixture is the highest. The filtration loss and cake thickness for the API mixture are lower than that of the individual size fractions due to its wider size distribution due to the filling of voids between larger particles with smaller ones, which lead to bed compaction and consequently lower fluid loss and cake thickness.

By Joseph J. Feiler

Fires in underground coal mines are persistent problems anywhere in the world that coal is mined. Coal fires pose safety and health hazards in the form of mine subsidence, loss of energy reserves, destruction of property and surface improvements, and air pollution. In 1995, the US Bureau of Mines (US-BM), in cooperation with the Colorado Division of Minerals and Geology (CDMG),entered into a contract with Goodson & Associates Inc. (GAI) to design and field test the effectiveness of a new foamed grout technology called ThermoCell. GAI is a Lakewood, CO geotechnical and mining reclamation engineering firm. The company developed ThermoCell to control and extinguish underground coal fires. The viability of the special grout and the technology of application were established during a full-scale field demonstration at the abandoned IHI Coal Mine fire, near Rifle, CO. Following acquisition of additional funding by CDMG in 1999, Goodson returned to the site in April to continue the grouting to fully extinguish the IHI fire.

Jan 1, 2000

By Colin Rawlings, Simon Pepper, Maria Karakitsiou, John Mathews, Peter Townsend, Russell Bowler, David Keeble, Christopher Darton, Scott Sadler

National Grid needs to maintain a connection between two existing electricity sub-stations (Beddington & Rowdown) in the Croydon (south London) area, and allow the replacement of two 275 kV cable circuits that are buried under roads. This is to be achieved using a single 400 kV cable circuit within a 10 km (6.25 mile) long, 3 m (9.8 ft) diameter high voltage cable tunnel which is being driven through water bearing Chalk, at depths ranging from 5 m (15 ft) to 80 m (262 ft), with four access shafts(12.5 m (41 ft) in diameter) ranging in depth from 10 m (31 ft) to 40 m (131 ft). The Chalk in this area acts as a source of public drinking water supply (PWS) and is protected by areas designated Groundwater Source Protection Zones. To minimise the groundwater risk the design and construction of the cable tunnel and shafts has paid particular attention to the construction materials used, including testing of these construction materials prior to use, developing construction methods (including the design of the Earth Pressure Balance TBM) and maintaining a groundwater monitoring & testing programme prior to and during construction to ensure the integrity of the Chalk aquifer is maintained as a drinking water source. This paper describes the tunnel &shaft design and construction in relation to these particular groundwater environmental issues which set new precedents for tunnel assessment, design and construction requirements in the United Kingdom.

Jan 1, 2007

By I. Tsolas

This paper presents the use of non-parametric approach (i.e., data envelopment analysis, DEA) for the development of environmental sustainability indicators in mineral processing using environmental, economic and/or integrated indicators (i.e., indicators that interrelate two dimensions of sustainability). A case study based on real publicly available data is presented to illustrate how the proposed approach can be implemented in practice. The merit of this approach, which is based on the productive efficiency framework, is that it provides environmental sustainability indicators that can be used internally for benchmarking purposes and externally for sustainability reporting.

Jan 1, 2008