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From Sept. 22-24, the Las Vegas Convention Center will be home to MinExpo 2008, the world?s largest mining equipment show that comes along once every four years. Sponsored by the National Mining Association (NMA), this year?s show is on pace to be the largest ever. Nearly 1,300 exhibitors have purchased nearly 55,700 hm2 (600,000 sq ft) of booth space. At the center of it all will be some of the most impressive mining equipment that the industry has to offer. And in the shadows of the massive haul trucks, drill rigs and bulldozers, attendees will be able to see the latest and greatest products including hand tools; the latest in automation and robotics; safety and communications equipment; longwall mining equipment; engines and parts; materials handling and processing equipment and services; pollution control equipment; reclamation equipment and services; computer applications; consulting and financial services and more. While many companies will be on hand to display the tried and true, there will also be plenty of new things to see. ?We anticipate that a whole range of new products will be introduced at the show,? the NMA said of the show that has been called the world?s richest deposit of mining technology, services and products. In addition to the show that will take place in Center Hall and North Hall of the Las Vegas Convention Center, MinExpo 2008 includes a conference program with 20 educational sessions that will tackle the most timely and pressing issues affecting the mining industry. Many of the industry?s top professionals will lead the discussions.

Jan 1, 2008

By L. Xinghua

Limonite is a general term for a group of amorphous iron oxide and iron hydroxide materials. It is considered as one of the very refractory iron ore types due to its wide variation in chemical composition, iron content, moisture content and easily sliming in the course of comminution. Iron grade of test sample is 25.48%, the iron minerals are mainly limonite; and the gangue minerals consist of quartz and feldspar in majority, secondarily silicate minerals. In this test work, high intensity magnetic separation (HIMS)-cationic reverse flotation and magnetic roasting-low intensity magnetic separation (LIMS) tests were conducted on limonite ore. The test results show that the concentrate with iron grade of 50.97% and recovery of 68.50% can be obtained by HIMS-cationic reverse flotation technique; while using magnetic roasting-LIMS technique, the better concentrate indexes of iron grade of 60.36% and recovery of 89.71% are achieved, and the iron grade of tailing is only 4.42%. Therefore, the magnetic roasting-LIMS technique is a better suitable method for beneficiation of low-grade limonite ore. Keywords: Low-grade limonite; Mineralogy; HIMS; Cationic reverse flotation; Magnetic roasting; LIMS

Feb 27, 2013

By Sohta Takatsu, Hachiroh Mizubata, Shigeki Kudoh, Kazuya Takekuni, Yoshinori Yamada

A special type of shotcrete is used to improve the performance of open-type TBM in difficult situations. The Hakamagoshi and Johana tunnels are expressway evacuation tunnels of 3.2 km and 5.1 km in length, respectively (total 9.1 km) that were excavated by one open-type TBM. The geological conditions at the sites were estimated to be good before excavation. However, 95% of the rock turned out to be two ranking orders worse than the estimated classes. Therefore, we used a special shotcrete for bad rock conditions, and succeeded in excavating the tunnel at an average rate of 270 m/month.

Jan 1, 2001

By P. A. Plunkert, D. E. Morse, L. McCartan, J. F. Papp

The mineral sector is a fundamental part of the U.S. economy. It contributes to the real gross domestic product (GDP) at several stages —basic (mining), intermediate processing, manufacturing of finished goods and construction. The real GDP increased by 3.5 percent from 2004 to 2005. The nominal GDP was $12.5 trillion at the end of 2005. Housing starts were up by more than 5 percent for the year, and the unemployment rate decreased to 5.1 percent in 2005 from 5.5 percent in 2004. The prime interest rate increased from 5.25 percent at the beginning of the year to 7.25 percent at the end of the year. The value of minerals mined in the United States in 2005 rose significantly because of increased unit prices for some metals —particularly molybdenum — and significantly increased production for some industrial minerals, mainly cement, construction sand and gravel, and crushed stone.

Jan 1, 2006

In February 2001, Kalgoorlie Consolidated Gold Mines (KCGM) commissioned its first full-scale ultra fine grinding (UFG) plant to supplement existing roaster concentrate treatment capacity. This process involves the fine grinding of refractory pyritic concentrate to 10µm, followed by direct cyanide leaching for the recovery of gold. By this means gold is economically extracted from the concentrate without the need to first oxidise the host pyrite. This paper details the history of the project from initial laboratory testwork comparing possible treatment options, to current performance of the 12 tph plant. This includes the cost comparison of the major treatment options, the laboratory and pilot scale UFG performance, the UFG mill selection, cyanide leaching of UFG product, commissioning and plant performance to date.

Jan 1, 2002

By B. Anderson, P. Churak, S. Dewar, A. Johnson, P. Eger

Although vegetation can be successfully established on fine taconite tailings, innovative approaches are needed to reclaim the coarse tailings used for dam construction. Through a series of cooperative projects with various government agencies and industries, EVTAC has been able to develop a unique closure plan. This plan will not only meet current reclamation standards, but also provide mitigation for a disturbed wetland and possibly create a tree plantation in the interior of the basin. By using waste products and exchanging materials, reclamation of the entire basin will be accomplised in a cost effective manner.

Jan 1, 2002

By John A. Breslin

The year 2010 will mark the 100th anniversary of the beginning of the research efforts by the U.S. government to improve the health and safety of miners working in the United States. This research began in 1910 with the establishment of the U.S. Bureau of Mines (the Bureau) and it has continued during the past 10 decades, even after the closure of the Bureau in 1996. The research on safer mining technology, formerly done by the Bureau, has now been combined with National Institute for Occupational Safety and Health (NIOSH) studies of miners? health to form a unified federal research program to improve the health and safety of miners. This article describes this research and places some of the accomplishments into perspective with other activities in the U.S. Mine Safety and Health Time Line (insert).

Jan 1, 2010

By Joachim Klein, Frank Reimann

Nodular-graphite cast iron (GGG) is a material similar to steel, and one which exhibits excellent properties, in particular for components exposed to pressure. GGG cast iron has been used in many cases when sinking mine shafts with conventional tubbing. With linings made of cast iron tubbings (the backfill concrete is not integrated into the calculations, and merely serves as bedding) the properties of the cast iron can be made full use of, provided the tubbing is made to the appropriate cross-section. Calculations have shown that better static values can be arrived at when using cross-sections other than those of tubbings made to conventional German standard. The cross-sectional design of the new types of shaft lining made from GGG is to be developed on these lines irrespective of the cast iron structure being only stressed component or its restistance function being combined with the one of concrete. GGG 50 is used for the first time to make the reinforcing inner liner of a main shaft currently sunk in Germany. The physical properties of nodular-graphite cast iron, strength and deformability, suggest that, in the future, its application will not be restricted to shaft support but also in tunneling. New moulding techniques with better three-dimensional modelling resulted in new tubbing designs as installed e.g. for the Hannover underground at present. Shield-driven tunnels have to withstand earth and water pressure, apart from axial machine loads. In this field time is money as well. Therefore easy handling and quick installation are necessary for successful, use. Last but not least, safety is of first-order importance for work in shaft sinking and tunneling. Cast iron lining systems, accordingly, are adequate systems, in particular for excavations underneath water for transport systems and for goods and passengers.

Jan 1, 1987

By L. J. Moore

Introduction Hydrometallurgical solvent extraction (SX) processes – featuring large quantities of combustible or flammable organic solvents - are common in the mining industry for recovering non-ferrous metals such as copper, nickel, cobalt, uranium, tungsten, iodine and lithium. Recent fire loss incidents and the widespread use of sub-grade tank farms and piping trenches, plastic piping, poor drainage, and closely spaced buildings demonstrate opportunities to improve the use of Inherent Safety (IS) in this industry. The mining industry has designed and constructed facilities with an emphasis on personnel safety, production efficiency and cost effectiveness. The use of IS to eliminate or minimize property fire exposures has not seen widespread practice. Lessons learned from the mainstream CPI have not been communicated or applied. As an example, copper SX plants have consistently used design of gravity flow as a cost and production-effective solution for transferring liquids and minerals through the process. In fact, Jergensen1 recommends to “utilize gravity to the fullest extent possible” in design of SX plants. This philosophy has been achieved by laying out SX plants with process equipment at different grade levels so that solutions can flow “downhill”. Because of the use of large quantities of flammable liquids and the potential for these liquids - if released – to flow unimpeded into other areas – gravity SX processes represent severe inherent fire consequences unless costly barriers, drainage and channeling are also provided. It appears that little thought has been given to the fire protection consequences and challenges of this design feature during the evolution of SX plants and most copper SX plants constructed today use some form of a sub-grade processing area (tank farm) and one-way gravity flow. While this layout is used to assure a cost effective operation it has resulted in significant exposures to high value production. The use of sub-grade production units is an inherently unsafe layout where flammable liquids are used and is a layout that would rarely if ever be used today by the mainstream CPI. Gravity-assist layout is only one example where copper SX plants have been designed and constructed without IS in mind. The use of combustible and frangible corrosion-resistant materials – such as glass, wood and plastic - for flammable liquid storage, processing and piping systems has significantly increased the hazards of these facilities. These materials of construction are not rigorous and allow for rapid failure and release of flammable contents during fire exposure. The use of combustible or frangible systems to handle or transport flammable liquids is not a practice seen today in the CPI.

Jan 1, 2006

By D. Kruse

Top down constructed large diameter (up to 90 m [300 ft]) shaft design and constructability issues present an interesting suite of challenges and opportunities highlighted in this paper. The study covers 2D and 3D finite element models used to: analyze various failure modes, evaluate the shaft liner and internal structures? response to seismic loading, assist in segment design, and assess final structural design tradeoffs. Efforts to achieve economic advantage over conventional heavy civil practices have prompted innovative solutions for ring and segment design, ring build assembly, and annulus backfill grouting. Intended for soft ground conditions, relationships between soil parameters and structure design are also explored.

Jan 1, 2011

By T. Burchett, F. Stanley, K. McGough, G. Luttrell

The vast majority of U.S. coal preparation plants utilize screen-bowl centrifuges to dewater their fine clean coal products. In light of this popularity, researchers at Virginia Tech have engaged in a variety of laboratory and industrial field test programs to develop technological enhancements that have the potential to further improve the performance of this important solid-liquid separation process. These enhancements, which include simple design modifications and new reagent packages, have been shown to significantly improve solids recovery and reduce product moisture in several experimental trials.

Jan 1, 2006

By Aram Grigoryan

This paper addresses the challenges of designing the underpinning of major sub-way station with 4 operating tracks. No. 7 subway extension crosses under the existing 42nd street subway station on the 8th Avenue line. Understanding the history of the original construction, of the current structures and their condition were instrumental in developing a feasible underpinning design that is integrated with the design of the new tunnels. The existing 8th Avenue subway station has a lower abandoned level. Several alignments and corresponding underpinning schemes were studied. The design allows new tunnel construction under the station without interruption of station operations.

Collaboration between education providers is the key to long-term sustainability and improved quality in mining education. The mining industry is now, more than ever, an industry doing business on a global basis. Staff are recruited by global mining companies in many different countries and can find themselves deployed anywhere in the world. The mining engineer of tomorrow must be willing to take on this international challenge, and must be educated to a level where he or she has a comprehensive grounding in technical aspects of mining engineering, but also a well-founded appreciation of management, social, environmental and cultural issues that may be encountered around the world. In order to deliver such an education, academic providers must collaborate at both a national and international level. This paper provides an overview of progress that has been made in Australia through the national joint venture ? Min¬ing Education Australia (MEA). Supported by the mining industry in Australia, through the Minerals Council of Australia (MCA), MEA has been operational since 2007 and is seeing the development of a range of innovative courses and delivery methods, together with a high level of staff cooperation across the country. MEA has also commenced some international teaching initiatives that are seen as a catalyst for a far greater degree of international collaboration in the future. Such activity is not only to the benefit of the students who are taught by experts from around the world, but it also ensures that individual univer¬sity programs remain viable in terms of staffing numbers and financial performance. The paper also presents some statistics on recent upward trends in mining engineering student numbers from around the world, in response to the global shortage of mining engineers.

Jan 2, 2010

By R. Benito

This paper describes the application of modern data-analysis tools, such as data mining, to determine a representative cost driver for haulage activity. This cost driver was subsequently used to trace incurred haul costs by bench for openpit optimization. For this purpose, large amount of previously unused cost and production data from an open pit mine was extracted, loaded, transformed and integrated into a data warehouse. Predictive modeling was performed using Microsoft Decision Trees algorithm to compute expected unit haul costs by bench for future mine expansions. Finally, a sensitivity analysis was carried out to determine the effect of two cost drivers (if any) for incremental haul costs in the final pit outline process.

Jan 1, 2008

The recovery of coarse particles has been widely recognized as being limited by the froth in mineral flotation. In response to this, FLSmidth has developed the Selective Froth Recovery (SFR) System. The SFR System is an extraction system that vacuums material from select locations within the froth and separates the recovered solids into coarse and fine fractions with a hydrocyclone. The SFR is supported and located by an actuator connected to the cell?s level control so that the suction heads are maintained at an offset distance from the slurry level. This can increase the recovery of coarse material by selectively recovering the material close to the bottom of the froth where drop-back of coarse particles typically takes place. The SFR System has been tested at two separate mine sites, and has been proven to increase the copper recovery in both trials. TEST RESULTS The SFR prototype was installed in a copper recovery circuit, on a rougher scavenger 160-m3 flotation cell. Figure 1, shows the SFR System, which consists of four conical skimmer heads that are plumbed together and share a common actuator. The SFR System, raised out of the froth prior to a test, can be seen in Figure 2. The SFR prototype was able to maintain a variety of set points using the level control to determine the slurry height.

Feb 27, 2013

By Steve Kral

MINExpo INTERNATIONL 2000 was a good place for companies to introduce new products, technologies and services to the mining industry. Caterpillar took that a step further. The company hosted a one-day preview of its mining products at its Tinaja Hills Training and Demonstration Center near Tucson, AZ. About 30 members of the trade press spent the day at Tinaja Hills before heading on to Las Vegas for MINExpo INTERNATIONAL 2000. Dozens of Caterpillar professionals provided the editors with a first-hand look at Caterpillar’s mining trucks, loaders, excavators, road graders, water trucks and engines. In addition, these Cat experts explained the intricacies of each piece of equipment, the latest technology that led their improvement and their value to the company’s mining customers.

Jan 1, 2000

By A. R. Biggart, A. Walters, G. J. E. Kramer

The Owner Procurement Process or OPP is a proven, viable alternative contract delivery method that is potentially applicable to many tunnel projects. Using the OPP, the owner specifies and procures major tunnel construction items such as tunnel boring machines and tunnel linings and provides them to a tunnel excavation contractor in order to manage risk and accelerate project schedule. However, due to industry perceptions regarding potential owner risk, it is seldom considered or is rejected out of hand. In fact, past performance demonstrates that the process significantly minimizes owner, contractor and over-all project risk and mitigates the impact of any claims and differing site conditions. The paper outlines how the process should be structured to achieve schedule, cost, quality and risk management benefits. Potential and perceived disadvantages are discussed and how the process can be structured to mitigate or avoid them. The planned implementation of this process on the tunnels for the Silicon Valley Rapid Transit Project in San Jose, California is discussed.

Jan 1, 2005

By R. E. Chaves

San Martin Mine is an open pit, gold heap leach operation located approximately 70 kilometers from the Honduran capital of Tegucigalpa. Mining operations commenced in 2000 and were completed late in 2007, while heap leaching operations continue. Reclamation was executed concurrently with operations to the extent practical. The area has distinct rainy and dry seasons and closure objectives include: prevention and mitigation of acid rock drainage, sediment and erosion control, and mitigation of visual impacts. Final closure is well underway at San Martin and this paper describes the closure processes conducted to date, problems encountered, and the subsequent lessons learned.

Jan 1, 2009

By P. L. M. Wong, N. W. Johnson

Surface analysis by X-Ray Photoelectron Spectroscopy (XPS) of samples taken from the galena flotation section of the Hilton Concentrator of Mount Isa Mines Limited are presented. Flotation rate and pulp chemical data taken during the sampling period are also presented and discussed. Surface analysis suggested that, under normal operating conditions, an overlayer of precipitated calcium sulfate existed at the surface of the sulfide minerals. In particular, there was a decrease in the surface concentration of calcium sulfate for the concentrate samples relative to that occurring on the tailing samples. This suggests that the flotation process was selective against minerals which have calcium sulfate predominating at the surface. Heterocoagulation of hydrophilic calcium sulfate on to the galena surface considerably reduced galena flotation rate. Methods to control calcium sulfate precipitation, which include sodium carbonate treatment of the pulp, are also discussed. Sur- face analysis results of samples taken from the Hilton Concentrator during sodium carbonate addition to the grinding circuit are also presented. This shows clear evidence for the removal of calcium sulfate from the mineral surfaces without concomitant surface precipitation of calcium carbonate. Reasons for the apparent dispersion of precipitated calcium carbonate are discussed. Galena flotation rate was increased by the addition of sodium carbonate apparently due to the removal of interfering calcium sulfate.

Jan 1, 1995

By K. A. Lapakko, D. A. Antonson

Fourteen samples of pyrite-bearing Archean greenstone rock (d < 6.35 mm, 0.04% < St < 1.22%) were characterized (particle size, chemistry, mineralogy) and subjected to laboratory dissolution testing. The only sulfide and carbonate minerals identified were pyrite and siderite, respectively. Quartz, chlorite and sericite typically comprised 90 to 98 percent of the mineral content. For the first 60 weeks, seven samples with sulfur contents less than or equal to 0.16% produced drainage pH values exceeding 6.0. Over this period, six of the seven samples with sulfur contents greater than or equal to 0.20% produced drainage pH below 6.0, with minimum values ranging from 3.2 to 4.7. The seventh sample (0.72% S) had a siderite content of 18%. Small amounts of magnesium and, to a lesser degree, calcium carbonates present in the siderite apparently dissolved to neutralize acid and maintain drainage pH above 6.0. Sulfate release rates generally increased as sulfur content increased, and the rates of pyrite oxidation estimated for individual samples were roughly half to five times that reported in the literature for the abiotic oxidation of pyrite by oxygen. Observed neutralization potentials ranged from 0.2 to 2.0 g CaCO3/g rock.

Jan 1, 2002