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By I. E. Lewis, W. R. Hopkins

Flowsheet improvements, such as series/parallel SX plant configurations, discontinuation of plant sumps and improved filter pumping concepts, the use of in-settler baffle systems, and the Krebs and combined mixer-settler designs offer opportunities to reduce SX plant cost. Today's plants employ permanent cathodes and mechanical stripping, and the increased capital cost can be offset by labor savings and higher current densities. The wider use of HDPE and new cell construction materials also reduce capital cost. The "Portelex" type of relocatable design embodies such new, cost-saving measures in a simple basic plant. Organic inventory and losses are reduced by new, fast-settling, hybrid organic reagents with improved kinetics and selectivity.

Jan 1, 1991

By G. Frey, D. Scott, C. Pritchard

Controlled recirculation has been used in the metal/nonmetal mining industry for energy savings when heating and cooling air, in undersea mining and for increasing airflow to mining areas. For safe and effective use of controlled district recirculation, adequate airflow to dilute contaminants must exist prior to implementation, ventilation circuit parameters must be accurately quantified, ventilation network modeling must be up to date, emergency planning scenarios must be performed and effective monitoring and control systems must be installed and used. Safety and health issues that must be considered and may be improved through the use of controlled district recirculation include blasting fumes, dust, diesel emissions, radon and contaminants from mine fires. Controlled recirculation methods are expected to become more widely used as mines reach greater working depths, requiring that these health and safety issues be well understood. The U.S. National Institute for Occupational Safety and Health (NIOSH) conducted two controlled recirculation tests over three days at a Wyoming trona mine, utilizing an inline booster fan to improve airflow to a remote and difficult-to-ventilate development section. Test results were used to determine the effect that recirculation had on air qualities and quantities measured in that section and in other adjacent areas. Pre-test conditions, including ventilation quantities and pressures, were modeled using VnetPC. During each test, ventilation quantities and pressures were measured, as well as levels of total dust. Sulfur hexafluoride (SF6) tracer gas was used to simulate a mine contaminant to monitor recirculation wave cycles. Results showed good correlation between the model results and measured values for airflows, pressure differentials, tracer gas arrival times, mine gasses and dust levels.

Jan 1, 2013

By C. RAMADINI, F. NURJAMAN, A. SHOFI, B. SUHARNO

Nickel demand is increasing along with the rising need for stainless steel and other alloy steel/iron. The small addition of nickel in such materials can improve impact strength, ductility and corrosion resistance. Nickel is generally obtained from nickel sulfide ores (nickel associated with sulfur) and nickel laterite ores (nickel associated with iron and magnesium silicate). Almost 60 percent of nickel is now produced from sulfide ores, despite its existence in sulfide ores being less than in laterite ores. However, the depletion of sulfide ore reserves makes the mastery of nickel laterite ore processing of important and immediate concern. Selective reduction followed by magnetic separation has been in development in lateritic nickel ore processing to overcome the issues of high energy consumption and pollution associated with conventional pyrometallurgy methods such as blast furnace and rotary kiln electric arc furnace (RKEF).

By Taeyong Lee, Cole Bales, Matt Fowler, John Horne

Mitchell Point Tunnel near Hood River, Oregon is one of the more unique segments of the Historic Columbia River Highway and State Trail being constructed through the Columbia River Gorge. This 650-foot bike/pedestrian tunnel set to open in 2024 is being delivered by FHWA in partnership with Oregon DOT, Oregon State Parks, and the U.S. Forest Service. Primarily driven using drill & blast excavation methods through basalt, the shotcrete and dowel-supported tunnel features masonry portals and ve window adits that provide illumination and views of the river similar to the original highway tunnel of many vistas built in 1915 that was removed in 1966 to make way for Interstate 84. This paper summarizes the planning, design, and construction.

Jun 23, 2024

By I. Dunlop, A. Goulsbra, R. Dunne

Mineral liberation or more aptly the particle size at which cost effect liberation is attained is an important mineral processing parameter. This implies that not all the mineral is liberated as further size reduction is not economically warranted. For ores of low grade minimising both the comminution capital and operating costs are crucial aspect to ensure project visibility. As a consequence the focus of attention for the most part is direct­ed to 'coarsening the grind" ahead of any downstream process­ing treatment. In most cases, recovery will be sacrificed to pro­vide for 'more tonnes' of capacity and in general this is eco­nomically justifiable. Preferential liberation and its measurements is an aspect of mineral processing that has created much attention and contro­versy. It is not the purpose here to discuss this matter in depth other than to state in broad terms that if an ore from the same source is subjected to comminution by two different methods, such that the product particle size distribution is similar, and subsequent downstream treatment demonstrates substantial dif­ferences in recovery, then there is reason to believe that prefer­ential liberation has occurred. Comminution by high pressure grinding rolls (HPGR) is a relatively new technology claimed to have two major advan­tages over conventional comminution. Firstly and more impor­tantly is the ability to improve comminution power efficiency. Power reductions of 10 to 40 percent being claimed. (Pagett et al (1995), Sargent (1995)). A secondary benefit claimed is that preferential liberation can occur. Generally, for HPGR there is a natural tendency of the product to have a skewed particle size distribution to the finer size. This in its own right could manifest itself in improved leaching and preconcentration performance. The question remains that if in using another comminution device, other than a HPGR, to produce a similar product size distribution as the HPGR, will there be any difference in downstream between the products from this and a HPGR.

Jan 1, 1996

By I. W. Farmer, R. E. Finky

Design of structures in rock based on ultimate limit states or strength criteria is unrealistic. The fracture process which inevitably occurs in rock around an underground structure is an energy release phenomenon. The development of fractures and associated displacements around a structure may therefore be more logically described using strain energy concepts and design may sensibly be based on serviceability limit states.

Jan 1, 1986

By Yueyue Ding, Yuanhui Li, Zhengrong Li, Pengfei Yu, Kunmeng Li, Zhipeng Xiong

The overburden responses in gently inclined orebody mining are different from those in horizontal orebody affected by the orebody dip angle. In particular, the mining-induced stress presents asymmetrical distribution characteristics spatially, resulting in stress concentration and large-scale pressure relief phenomenon in the surrounding rock. As a result, frequent ground pressure disasters such as roof collapse and barrier splitting occur frequently. Moreover, the ground pressure evolution law and the interaction between stopes in multistope mining are complex. The effective ground pressure control measures cannot be taken due to unclear understanding of the evolution of stress and displacement fields, justifying the investigation of the distribution and evolution of underground pressure for safe and efficient mining.

Jun 1, 2023

By K. I. Cunningham, C. S. Spirakis

Two types of native sulfur deposits have been found in Lechuguilla Cave: thin late-stage crusts and massive early- formed deposits. Most, if not all, of the crusts appear to have formed by remobilization of native sulfur contained within gypsum and sulfur masses. The process is occurring today and is slowly converting the sulfur to gypsum. The absence of primary gypsum or reductants in the cave indicates that the early-formed massive sulfur deposits did not form by in-place reduction of sulfate, which is the process that formed the commercial sulfur deposits in the Delaware basin. Instead, it appears that H2S dissolved in basinal brines was oxidized by oxygen in near-surface ground waters in the cave. Fluid- inclusion data, which suggest the presence of both fresh water and saline water as the sulfur formed, support this interpretation. Although individual sulfur deposits in Lechuguilla Cave are no more than several tens of metric tons, the abundance of secondary gypsum (as much as 10 meters thick) indicates that native sulfur may once have been much more extensive.

Jan 1, 1992

By R. H. Kuhlman

The purpose of this paper is to describe the roles of cement and concrete in construction in general and, more specifically, as construction materials of the Southeast. For purpose of this discussion, the Southeast will include the geographic area composed. of the following 13 states: Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, Virginia and West Virginia. In one sense, cement by itself is not a construction material. It is a finely ground manufactured mineral product, usually gray in color. Cement is mixed with water and sand, gravel, crushed stone, or other aggregate to form concrete, the rock-like substance that is the most widely used construction material in the world. Because cement is seldom used by itself for construction but is usually a component of concrete, there is no such thing. as a "cement" sidewalk, a "cement" highway, or "cement" building. Neither is "portland" a brand name. It is a generic term used to describe any cement that hardens in the presence of water and is made to standard specifications .. For all practical construction purposes, therefore, all cement is "portland." The name "port-land" was selected by the English inventor of the product in 1824 because concrete made with his product resembled natural building stone quarried on Portland, an English island. Although portland cement is not the final material which finds its way into completed construction, as the principal component of the most widely used construction material in the world, the location and process of its manufacture warrant some discussion

Jan 1, 1977

By Jessica M. Wempen

"Differential Interferometric Synthetic Aperture Radar (DInSAR), a satellite-based remote sensing technique, has application for monitoring subsidence with high resolution over short periods. DInSAR uses radar images to measure centimeter-level surface displacements. In the images, ground resolution can be relatively high, with each data point (pixel) representing the average displacement over an area of several square meters. The image data are acquired regularly which allows subsidence to be monitored sequentially over short periods; imaging periods typically range from weeks to months.Monitoring subsidence over short periods with high spatial resolution has potential to provide insight into the dynamics of subsidence and into relationships between mine advance and subsidence. In this study, for three longwall mines in the western United States, initial subsidence occurring at the start of longwall advance is quantified over short periods (12 to 72 days). C-band interferometric wide swath Synthetic Aperture Radar (SAR) images from the Sentinel satellites are used to quantify the subsidence. Overall, the data show initial development of subsidence, expansion of the subsidence trough, and the advance of subsidence in the direction of mining.INTRODUCTIONApplied Differential Interferometric Synthetic Aperture Radar (DInSAR)Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote sensing technique that can be used to quantify small displacements of the Earth’s surface. Using data from the Seasat satellite, which was launched in 1978 (Jet Propulsion Laboratory, 2018), studies by Goldstein, Zebker, and Werner (1988) and by Gabriel, Goldstein, and Zebker (1989) applied Synthetic Aperture Radar (SAR) interferometry to topographic mapping and displacement monitoring. These studies established the potential for broader applications of radar interferometry. Studies by Foxall, Sweeney, and Walter (1998), Wright and Stow (1999), and Carnec and Delacourt (2000) represent some of the earliest evaluations of DInSAR for mine subsidence monitoring. All three of the studies demonstrated the application of DInSAR for quantifying mine subsidence. They also demonstrated difficulty accurately measuring subsidence over long periods due to data decorrelation. DInSAR continues to be evaluated as a tool to quantify surface deformation related to active and historic mining. For example, see Vervoort and Declercq (2018), Wempen and McCarter (2017a), Chen et al. (2013), and Liu et al. (2013). Technologies associated with SAR interferometry continue to develop. Recently launched satellites have relatively high spatial and temporal resolutions, and data processing methods and data accessibility are improving."

Jan 1, 2019

By R. J. Pruett, P. I. Prescott

Ground calcium carbonate (GCC) is used in the paper, plastics, paint, rubber and caulks and sealants industries. The favorable properties of GCC include high whiteness and brightness, low hardness and outstanding rheology in water systems. The quality of calcitic GCC ores, which includes chalk, limestone and marble, is dependent on calcite purity and the nature and quantity of the impurity minerals. Wet and dry grinding are used in the processing of GCC. Ore processed by optical sorting, flotation and/or particle-size classification has higher brightness and lower abrasion characteristics. GCC markets are a function of the product's properties, purity and cost.

Jan 1, 1997

By P. Whincup, T. Showell, B. Marchant, R. Dunne

An oversupply of copper on world markets in the early 90' s, coupled with a decrease in demand, resulted in a "tight" market for the sale of copper concentrate. In these conditions small producers of low grade copper concentrates found it difficult to sell their products. The situation was exacerbated for those producers also having reasonable quantities of penalty elements (e.g. As, Bi). The Telfer Gold Mine bulk copper gold concentrate, produced from treating underground sulphide ore, fell into this category (i.e. 16% to 20% copper, 30% to 35% sulphur and 3500ppm to 4500ppm arsenic). The concentrate sulphide minerals are predominately chalcocite and pyrite. Although a higher grade copper concentrate was attainable a substantial decrease in gold recovery ensued. Under the prevailing market conditions a decision was made to stockpile concentrates pending either an easing of market conditions or alternatively finding an on site method for treating the concentrate to recover both the contained gold and copper.

Jan 1, 1995

By Michael Robert Hodson

The views expressed in this paper are those of the author and do no necessarily reflect those of CRU. The Extent of Government Involvement In 1982 national governments in the Non-Socialist world owned at least some equity share in an estimated 49 percent of the bauxite mining capacity located in their own countries.* By comparison, as Figure 1 shows, in the same year governments owned at least part of an estimated 33 per cent of primary aluminium smelting capacity. In other industries, national, or state governments in 1982 held at least part ownership of mining capacity in 42 per cent in the copper industry, 34 per cent in the tin industry, 23 per cent of the zinc industry, 15 per cent of the lead industry and 11 per cent in the nickel industry. Thus while within the aluminium industry attention has focussed on the share of government ownership in the primary aluminium sector, national government involvement through ownership is larger in the bauxite sector. Moreover, ownership by government is more widespread in the mining of bauxite than in the mining of all other principal non-ferrous base metals. Yet while the equity participation of governments in the bauxite sector is widespread, it is but one of many forms of government involvement. In addition to direct ownership or equity participation domestic government involvement has taken the form of legislation to protect the environment, controls on the level of production, insistence on the export of ore, pressure to maintain levels of employment, controls on the type of fuel used, foreign exchange *Capacity which is owned in whole or in part is included within the state sector, but capacity in one country which is owned by a wholly or partly owned government company in another company is not included in the state sector; e.g. the capacity of the Trombetas mine is included in the state sector but the capacity of Delphi bauxite would not be included.

Jan 1, 1984

By L. Gutierrez, J. S. Castro S. Laskowski

Water is a medium in which flotation takes place, and flotation efficiency is highly dependent on water quality. Of the total water resources on Earth, less than 2.5 percent is fresh water. This water is used in agriculture, by households and by industry. Among the industrial users of fresh water, the mining industry occupies an important position. Furthermore, mining operations are often located in arid areas with very limited access to fresh water. The demand for and shortage of water in these parts of the world, such as the Atacama Desert in Chile, makes the use of seawater by the mining industry the only sustainable solution. 

By J. C. Monette

Stripping of gold and silver from carbon is effected by means of two main processes (AARL and ZADRA ). The main rate-enhancing parameter in the stripping of gold and silver is temperature. A secondary rate-enhancing parameter is ionic strength. (1) Stripping is usually conducted within a solution containing sodium cyanide (0.1 -0.5% ) and caustic ( 1 -3%). The development of a chemistry that increases the rate of gold and silver stripping from carbon in a manner proportional to its concentration is described. Its use in atmospheric and pressure strips is also outlined.

Jan 1, 1992

By J. D. Miller, J. Hupka

Environmental applications of the air-sparged hydrocyclone (ASH) technology are presented. The original ASH design used porous sintered steel or porous polyethylene tubes as spargers. To diminish/prevent plugging and to reduce pressure head loss in the gas path a wire screen sparger and new hydrocyclone design have been developed, which allows for wide application of the technology to solve environmental problems and to be used as a chemical reactor. Field and laboratory trials have shown that the ASH technology might be preferred for the stripping of volatile organic compounds WOC) from contaminated water. The ASH has also been developed for absorption of SO2, toluene vapors, and for the recovery of cyanide.

Jan 1, 2005

By Alec G. Richardson, S. H. Chiang, Ralph W. Lai, McMahan L. Gray

The potential of coal cleaning by selective agglomeration was examined for a Pittsburgh seam bituminous coal using isooctane as an agglomerating liquid. The effects of particle size, pH, degree of mixing, and dosage of isooctane on the pyrite and mineral matter removal from finely ground coals were investigated. The role of shear-enhanced-hydrophobic-association in the flocculation of fine particles was examined. The degree of liberation of pyrite from coal at different grinds was examined using an automated petrographic image analyzer. The effect of dispersant on slurry rheology during grinding was studied. The results indicate that over 95 percent of the pyritic sulfur can be removed from the coal. Final products containing less than 0.9 percent ash at a combustible recovery in excess of 90 percent have been obtained with multiple stages of cleaning.

Jan 1, 1989

By I. WILKOMIRSKY, J. BECKER, F. Parada

CORRECTION

Jan 18, 2023

By Jeff Fontana, Daniel Ebin, Eric Westergren, William Currier

The PMott MacDonaldlane Train Tunnel West Extension (PTTWE) Project at HartsfieldJackson Atlanta International Airport includes the extension of the existing automated people mover system and terminal renovations at the baggage claim station. To assist with design, pricing, and assessment of risk on this progressive design-build project, 3D design models were prepared to increase visibility into realities of construction. This paper will focus on the original intent of the models and explore the additional, unforeseen value they provided throughout the design and construction process.

Dec 1, 2022

"The mining industry suffers from a number of incorrect perceptions, one of which is that it is an outdated industry that has not changed for hundreds of years. But the truth of the matter is that mining is a vibrant, highly complex industry that not only employs highly skilled and educated professionals but is also often on the cutting edge of technology. It is an industry with projects that are ever-evolving and among the most challenging engineering feats in the world.Take for instance the U.S. 53 Highway Relocation project in Virginia, MN. While more of a civil engineering job than a traditional mining project, it is still a complex engineering challenge taking place in a mining environment that has called on the skills of eight state agencies, three federal agencies, a host of contractors and many consultants, including many from the local mining industry in the Iron Range of Minnesota.In 1960, the Minnesota Department of Transportation (MnDOT) constructed U.S, Highway 53 on a private easement owned by US Steel that cut across a massive taconite deposit. MnDOT constructed the highway with the agreement that if the highway needed to be moved to access the taconite deposit before 1987, US Steel would foot the bill. And if the move was required after 1987, the responsibility would fall to MnDOT. In 2010, MnDOT received the notice that the highway would have to move as property owner United Taconite planned to access the ore, setting in motion one of the greatest engineering challenges, and the highest risk project, in the history of the states’ transportation department.Pat Huston, U.S. Highway 53 Relocation project manager, opened the 90th SME Minnesota Section Conference in Duluth, MN on April 19 with a presentation about the project that includes 5 km (3.2 miles) of fourlane highway and a new 345-m (1,132-ft) bridge that will be the tallest in Minnesota when it is completed later this year.“This project was not business as usual,” Huston told the packed crowd. “Highway 53 connects Canada and the Iron Range to Duluth and Lake Superior. It is an important highway.”During his presentation he spoke about many topics that were familiar to the more than 1,100 mining professionals who attended the conference. In his keynote speech,"

Jan 6, 2017