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By D. Komljenovic, V. Kecojevic

Selection of the best possible truck type (model) is of crucial importance for the mine decision-makers. In this paper, authors contribute to the body of knowledge by developing a novel methodology for the selection of mining truck. Both the Coefficient of Technical Level (CTL) and Analytic Hierarchy Process (AHP) methods were used in this study. The CTL represents a mathematical function which takes into consideration the interrelations among the main technical parameters of mining trucks. The authors developed a hierarchical structure where both attribute categories and their importance, i.e. priority or weight in the selection process were determined. For each category, a number of sub-attributes and their priorities were assigned, and a pairwise comparison among them was performed using the AHP method. In the final part of the study, the CTL was integrated into the AHP and represents a holistic approach in the selection of mining trucks. A case study on 180 tonnes truck category offered by five manufacturers was carried out. A sensitivity study of obtained results was also performed indicating a very stable solution. The methodology presented in this paper may be used by mining operators to help in the selection of a specific type when acquiring a new truck. It may also be used by equipment manufacturers to help in analysis of potential benefits of envisaged modifications concerning an existing truck type and/or development of a new type.

Jan 1, 2007

By M. S. Klima, V. Choudhry

Coal gasification solid residue (slag) contains unconverted carbon (char) which is considered an impurity for utilization applications of slag. Under this study, table concentration was used to process approximately 24,000 pounds of a nominal -3.4 mm gasifier slag (~85% ash) to separate high (~100%) ash slag from low (~50%) ash char. The results indicated a nearly ideal separation of the slag from the char for sizes coarser than about 1 mm. An overall slag yield of 71% was obtained. The slag was sufficiently clean to be used as feed material for the production of expanded lightweight aggregate. The recovered char had an ash content of about 47% and was a nominal -1 mm in size.

Feb 24, 1997

By Jamal Rostami, Ataollah Rahbar, Jürgen Paulzen

"Uma Oya Multipurpose Development Project is located in South West Sri Lanka. This project, among many components, involves a 14 km headrace tunnel in very hard and abrasive igneous rocks. The tunnel is under construction by a 4.4 m diameter double shield TBM. The headrace tunnel has already reached 5km milestone and has passed through some reaches of tunnel in very strong intact rocks with no joints. Low penetration at high thrust load has caused frequent stoppages for cutter change leading to low utilization and advance rates due to low cutter life. The original machine was dressed with 27, each 432 mm (17 inch) diameter, 19 mm (3/4 inch) tipped disc cutters. However, various cutter diameters of 432-457 mm (17-18 inch) and cutter tip widths 13 to 19 mm (0.5-0.75 in), have been tried to see if cutter life and penetration rates could be increased. This paper will review the history of the project, the geology of the site, along with TBM performance and cutter life. It will focus on frequency of different cutter failures encountered in various ground conditions. Also, results of using variation of cutter diameter and tip width to cope with the hard rock conditions and their results in increasing machine productivity will be discussed. This allows for better understanding of parameters controlling disc wear/life and leads to better cutter management for more efficient operation of hard rock TBMs in similar conditions. INTRODUCTION The Uma Oya Multipurpose Development Project (UOMDP) lies in the south-eastern part of the central highland region of Sri Lanka. The Multi-Purpose Project Of Uma Oya is planned to convey water from Uma Oya to Kirindi Oya Basin for hydroelectric energy generation includes Puhulpola RCC Dam on the Uma Oya river, Dyraaba RCC Dam on the Mahatotilla Oya river, a conveyance tunnel from Uma Oya to Mahatotilla Oya (L=3750m), a long feeder tunnel from Mahatotilla Oya to Kirindi Oya river. The feeder (or power) tunnel Lot consists of a 15554 m long headrace tunnel (HRT), the surge shaft and tank on the upstream of the vertical shaft, a 650 m vertical shaft with steel lining, and an underground powerhouse and a 3650m tailrace tunnel (TRT)."

Jan 1, 2016

Gangue-cemented paste backfill (GCPB), is a well-established green mining technology and significantly improves the recovery rate of mineral resources, prevents mine dynamic disasters, reduces surface subsidence, and consumes a considerable amount of solid waste. The addition of an early strength agent as an additive in cement-based materials provides several security, technical, and economic advantages. In this study, the early strength agent on the early age (3, 7 and 28 days) strength of GCPB is evaluated experimentally. The GCPB specimens have an initial sodium sulfate early strength agent concentration of 0%, 1%, 2%, 3%, and 4%, and the obtained samples were analyzed by testing for uniaxial compressive strength (UCS) and scanning electron microscopy (SEM). The test results show that the UCS of the GCPB specimens with sodium sulfate is much higher than that of the blank specimens. When cured for 3 days and 7 days, the strength of GCPB with 2% sodium sulfate increased the most, by 131% and 116% respectively. When cured for 28 days, the strength of GCPB with 1% sodium sulfate increased by 135%. Scanning electron microscopy (SEM) results showed that the GCPB with 1% and 2% sodium sulfate had better internal structure compactness, thicker acicular crystals, and more flocs. As a kind of early strength agent, sodium sulfate can react with calcium hydroxide to generate calcium dihydrate sulfate and then react with calcium aluminate; the hydration product (C3A) quickly generates calcium sulfoaluminate hydrate (AFt) needle-shaped crystals, forming an early skeleton and improving the early strength.

Jan 7, 2020

By Steven G. Vick

Effects of the August 1995 failure of the Omai tailings dam in Guyana continue to be felt throughout the mining industry. This article is taken from the final report of the independent body of experts commissioned by the government of Guyana to establish the cause of the failure. It explains what happened, why and how to avoid it in the future. Despite environmental, health and safety effects that were negligible by any objective measure, the failure has received wide international attention. Coming on the heels of the shift in exploration targets and development opportunities to developing countries, it has intensified interest in tailings dam safety and environmental management issues. An informed understanding of the nature of the failure and its effects is key to responding to these concerns.

Jan 1, 1996

By J. Hunter, E. Jackson

This paper describes work done by Placer Dome Technical Services Limited, a subsidiary of Barrick Gold, and Nautilus Minerals Inc. in support of the conceptual design of a subsea mining system. It describes an overall concept design plus specific studies into mechanical excavation at depth. The concept design includes one or more subsea excavators connected to a suction riser, which transports the cut material to a shipboard dewatering and offloading system. A multi-phase investigation was performed into the mechanical excavation of seafloor massive sulphides at depths of around 1600m. Rock samples were recovered and tested for rock properties and cutting behaviour. A small pick drum cutter was procured and tested on a representative concrete slab in a lab and tested again while submerged in a test tank. Finally the cutter was tested on a massive sulphide ore body at 1600m depth. The cutting performance results, e.g. pick forces and specific energies, should provide valuable input to the design of future full scale subsea mining systems.

Jan 1, 2007

By Fred N. Kissell

INTRODUCTION During the last few years, several new ventilation developments have attracted the interest of mining engi¬neers. Some of these developments are applicable pri¬marily to hard-rock mining, while others are more applicable to coal mining. STOPPINGS Parachute Stopping The parachute stopping is a new type of quick-erect stopping that is intended for temporary use in hard-rock mines (Kissell, Thimons, and Vinson, 1975). As shown in Fig. 1, the stopping is shaped very much like an ordinary parachute, with a canopy of impermeable fabric that is sewn to regularly spaced straps running to a common point. To erect the stopping, the straps are attached to a fixed anchor point such as a roof bolt, and the edge of the canopy is lifted into the moving air¬stream. The airstream pops the parachute canopy into place, and the differential air pressure across the stop¬ping holds it in place, forcing the fabric against the walls, roof, and floor of the mine opening. The principal advantage of the parachute stopping is that it requires only a few minutes to install, making it a great time-saver for emergency use or for day-to¬day changes in ventilation during the production cycle. However, the parachute stopping does require some minimum air velocity to lift it and some minimum differential pressure to hold it in place. For a fabric weighing 0.27 kg/ m2 (8.0 oz per sq yd), the minimum air velocity is about 0.5 m/s (100 fpm), and the mini¬mum differential pressure is about 0.05 kPa [0.2 in. water gage (WG) ]. There is always some air leakage around the stop¬ping, mainly depending upon the extent to which pipes or other obstructions encumber the airway and prevent good sealing. Leakage of a few cubic meters per second (a few thousand cubic feet per minute) can be expected, unless foam is used to improve the seal at the edges of the canopy. Quick-Fix Blowout Stopping The quick-fix blowout stopping is a variation of the parachute stopping (Thimons and Kissell, 1976), and it is used in the proximity of blasting operations. This type of stopping is designed to be blown out easily by the blast forces, and it may be reinstalled quickly and easily. The long high-strength straps of the parachute stopping are replaced by groups of short straps that tear easily. These straps are attached at six equally spaced locations around the perimeter of the canopy. To erect the stopping, one strap of each of the six groups is fastened to the mine wall, roof, and floor by using spads, by setting pins with a powder-actuated gun, or by tying the straps to some firm anchor point. Once the straps have been attached, the differential air pressure across the stopping, which must be at least 0.025 kPa (0.1 in. WG), forces the stopping perimeter against the mine walls, thus creating the air seal. It is the self-sealing feature of this stopping that makes it a significant time-saver. Only a few attachment points are needed; in many cases, four attachment points are sufficient, since the stopping naturally tends to form a seal with the airway surfaces. When nearby produc¬tion blasting exerts excessive forces on the stopping, one or more of the straps tears away from its attachment point, protecting the stronger canopy from damage. Damage-Resistant Brattice The damage-resistant brattice is a stopping that is designed for use in mines such as salt and limestone mines where the differential pressures are low and the roof is relatively flat. As shown in Fig. 2, the damage-resistant brattice consists of a series of brattice panels that are hung vertically and joined by Velcro® connections. When the brattice is subjected to strong blast forces, the Velcro® connection peels apart and allows the panels to open without incurring damage. The Velcro® connections can be resealed by hand within a matter of minutes. Such damage-resistant brattices have withstood the blast effects of 318 kg (700 lb) of ammonium nitrate-fuel oil (ANFO) explosive detonated as close as 91 m (300 ft) from the brattice. Ordinary brattice cloth is used for the panels, with a 51-mm (2-in.) wide strip of Velcro® hooks sewn along one edge of the length, and a 51-mm (2-in.) wide strip of Velcro® pile sewn along the other edge. Both the hooks and the pile are sewn onto the same side of the brattice cloth. The resulting Velcro® seal formed be¬tween adjacent panels is perpendicular to the brattice itself, and the leading edge of the seal can be directed either toward or away from the blast forces; the brattice works equally well in either case. To hang the brattice, panels of brattice cloth about 0.9 m (3 ft) longer than the height of the airway are cut from a 1.8-m (6-ft) wide roll. The additional 0.9 m (3 ft) of brattice cloth allows 0.3 m (1 ft) for attachment to the roof by means of a board, with 0.6 m (2 ft) for forming a good air seal at the floor. Each brattice panel is wrapped once or twice around a 51 X 102 mm (2 X 4 in.) or 25 X 76 mm (1 X 3 in.) mounting board that is 254 to 305 mm (10 to 12 in.) shorter than the width of the panel. For convenience in

Jan 1, 1982

By S. Shi, J. Y. Hwang, B. Li

Silver, copper, and zinc are commonly known elements with antibacterial and antifungal capabilities. Attempts have been made to dope silver on minerals, glass, and ceramics and the resulting materials have been investigated for their antibacterial and antifungal properties. Since silver is expensive and very reactive, silver doped materials have been found inappropriate in some applications. Copper-vermiculite is investigated as an alternative. Vermiculite has high cation exchange capacity on the magnesium ion in the crystal structure. Copper ion may have a high tendency to replace magnesium because of similar charge interference and ionic radius. Copper-vermiculite is prepared by reacting vermiculite and copper chloride solution. By impregnating copper ions into the nanometer openings between the layers of vermiculite, it is possible to render the composite with antibacterial functions if the copper ions could be released gradually from the composite. The antibacterial efficiency of Cu-vermiculite against Escherichia coli was studied using the Halo method. The results show that Cu-vermiculite is effective for preventing the reproduction of the bacteria. Heat treatment of Cu-vermiculite at up to 400°C does not show significant changes in antibacterial activities.

Jan 1, 2002

By Umay Cinarli, Ahmet Turan

High-energy consumption in primary aluminum production (from bauxite ores) makes secondary aluminum production (from metallic raw materials such as scrap and dross) very critical. Aluminum dross, as a waste, arises in pyrometallurgical processes, and it is the mixture of metallic Al, Al2O3, other metal oxides, metal halides, and some other compounds like AlN. Aluminum dross has two subgroups (white and black) with respect to its metallic aluminum content. White dross is a secondary aluminum resource because of its high metallic aluminum content, whereas black dross, having low metallic aluminum content, is generally disposed in dumping areas. In the present study, it was aimed to develop a simple technique to valorize aluminum black dross in the form of alumina-based ceramic materials through pyrometallurgical (calcination) and hydrometallurgical (leaching) operations. Moreover, thermochemical simulations were conducted by using HSC Chemistry 6.12 software to simulate calcination conditions. After leaching experiments, an alumina-based ceramic containing approximately 36.8% Al2O3, 61.4% MgAl2O4 with 1.8% Na2FeO4, which might be available to use as a spinel refractory in steel smelting furnaces, was obtained in the experiment carried out in a solution containing 10 mLH2SO4 and 40 mL distilled water (3.5 M). Moreover, the sinterability of the alumina-based ceramic was investigated at the temperatures from 1350 to 1550 °C. In the sample which was sintered at 1550 °C, a density value of 3.15 g cm−3 and a hardness value of 69.58 HV were measured.

Oct 26, 2020

By Anna Sieminska-Lewandowska, Monika Mitew-Czajewska

"The construction of 6.3 km long central part of 2nd metro line in Warsaw was completed in September 2014 (7 stations - out of which three 25m deep stations - built using cut and cover method; two single-track tunnels constructed using four EPB TBMs as well as a short NATM section with soil freezing below the existing road tunnel). Central section of the 2nd metro line was opened to public after verification and testing in March 2015. Design and build tender for the extension of this line in East (three stations) and West direction (three stations) was announced with total length of running tunnels – approx. 5 km. Detailed description of a very complex geotechnical context, different construction methods, challenges encountered and solved during construction and finally lessons learnt on this interesting project are presented in the paper. DESCRITPTION OF THE PROJECT Introduction The very first concept plan of the metro system in Warsaw was designed several years after regaining independence by Poland in 1918. In 1929, following the geotechnical survey, design works begun, but the economic crisis of the 1930s stopped it. After a few years of break, in 1938 a coherent concept of the metro network was proposed to be implemented in phases over the next 35 years. In total, construction of 46 kilometers of metro, including 31 km of tunnels and 15 km on surface, was planned. Unfortunately, World War 2 made the implementation of those plans impossible. In the post-war period several metro designs were elaborated, but none except one was scheduled for implementation. Construction of the 1st, 23.1 km long, North-South line commenced in 1983 and finished in 2008 (Sieminska-Lewandowska et all. 2009). Nowadays, Warsaw covers the area of 517 km2 and, according to year 2014 statistical data, the city has much more than 1.7 million inhabitants. Only one operating metro line is not sufficient for such a populated city. Up-to-date metro plan, shown on Figure 1, includes also 30.5 km long 2nd metro line. It’s route is divided into four sections: Western Section with the length of approx. 9.2 km and 9 stations, Central Section with the length of 6.3 km and 7 stations, North-East Section with the length of 7.7 km and 6 stations, South-East Section with the length of 7.1 km and 6 stations. The construction of the central part of the 2nd metro line in Warsaw was completed in September 2014 and its operation started in March 2015. The paper focuses on challenges encountered and solved and lessons learnt during construction of the central part of the 2nd metro line in Warsaw."

Jan 1, 2016

By Benoit Gagnon

Mining of the Schefferville iron deposits began in 1954 on completion of the 574 km railway linking the mines and the St-Lawrence river port of Sept-Iles. Apart from crushing, no treatment of these ores was required before smelting. In the late 1950's, testwork began at Schefferville to develop a process for upgrading the extensive lower grade deposits containing 5l% iron with 15% silica (natural analysis). Engineering for 6.1 million tons per year Beneficiation Plant using cationic silica flotation and the A-C Grate kiln began in 1970 and the first pellets were produced in mid 1973. Production requirements and operating difficulties have restricted capacity to approximately 85% of design but ongoing improvements are being made continuously to attain design capacity.

Jan 1, 1980

By L. Mead

Dimension stone is a natural stone (granite, marble, limestone, sandstone and slate) that can be quarried, cut and shaped to conform to acceptable industry standards for size, consistency and durability. There are numerous outlets for the finished product in exterior and interior architectural and design applications. A continued growth market is with residential usage— particularly in new, upscale construction. This has become a competitive market between domestic producers and lower cost imported products. These imported products have become available at many of the building supply retail outlets and have increased the use of stone in residential construction and renovation. The traditional architectural application of dimension stone is tied to commercial and institutional building construction trends and market. There has been a noticeable increased usage of stone in the Sun Belt. This stone is usually supplied by local fabricating shops. It is used in the exterior and interior of shopping malls. This market generally uses local stone sources. It has increased the demand for sandstone, limestone and quartzite in this region of the country.

Jan 1, 2005

By P. Mills

The four top barite-producing countries in the world are China, India, Morocco and the United States. China is currently the largest exporter of barite followed by India. More than 95 percent of the barite mined today is used by the petroleum industry as driller’s mud. The rest is used in the industrial market and the medical field. Most of the barite mined in the United States is in Nevada. This year, mining activity has increased due to an increase in oil exploration/development. This was caused by an increase in the crude oil prices.

Jan 1, 2005

By Jon Y. Kaneshiro, Sean A. Menge, M. Luis Piek, Brian Barker

The Lake Hodges to Olivenhain Pipeline project is part of a 40-megawatt pumped storage project linking two reservoirs as part of the San Diego County Water Authority’s $939 million Emergency Storage Project. Seeking to expedite project completion, the project was advertised as Design-Build, a first for the owner. Awarded to Kiewit Pacific with Parsons as designer, the 1,750m (5,700ft) long, 4.25-m (14 ft) horseshoe tunnel was excavated with conventional drill-and-shoot technique. The mining method was well suited to deal with the shear zones, the very abrasive rock, and 13.3% and19.6% grades. At the apex of the alignment, a 60m (200ft) by 3.6m (12ft) diameter raisebore shaft with surge chamber to protect against pump malfunction was constructed. Upon completion of mining, the tunnel was lined with a 3m (10 ft) diameter high strength steel pipe. Scheduled to come on-line by January 1, 2008, the Lake Hodges to Olivenhain pumped storage project is valued at $108 million, delivering a reliable source of water in emergency situations and electricity-generating capability to meet the growing demands of the San Diego region.

Jan 1, 2007

By K. H. McDaniel, D. M. Loring

The underground ventilation system at the Waste Isolation Pilot Plant provides unparalleled ability to ensure safety of the workers, public and environment. Although small spatially, it can vary the airflow from 66,000 acfm to 460,000 acfm. It can automatically incorporate HEPA filtration in the event of radioactive contamination. Remote-capable regulators individually control the four main splits, and can be adjusted from the surface if necessary. A ventilation remote monitoring and control system provides real-time information. Future areas of concern include DPM compliance, system psychrometry, logic-based-real-time mine ventilation simulation and automation using PLC technology. This paper discusses the evolution of this system.

Jan 1, 2002

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

By Steve Kral

Most innovations in the mining and processing industries have come from the need to produce more for less. Extracting minerals from the ground is expensive. And it is a constant struggle for mine operators to maintain the line between profitability and loss. The same holds for equipment suppliers. To maintain competitiveness, mining equipment manufacturers are building their machines with an eye to what the customer needs. Equipment makers know that if they do not supply machines that are productive and cost efficient, their competitors will. The result has been that the mining industry can now produce more ore with fewer people and more productive equipment. But, for all of the advances made in equipment, mine operators still demand machines that produce even more, are safer for workers and the environment, require less maintenance and can do the job at lower costs. And equipment manufacturers keep responding with larger, smarter and more technologically advanced machines.

Jan 1, 2005

By J. Um, B. Morin, P. H. S. W. Kulatilake

Development of a three-dimensional mine visualization model for a section of the mine is addressed first. Discontinuity orientation and location information was taken from this visualization model for use in slope stability analyses. Estimated shear strength properties of discontinuities and mechanical properties of intact rock from the rock mass samples obtained from the mine are discussed next. The paper is then focused on the calculated maximum safe slope angles based on the performed kinematic and block theory analyses using the mapped discontinuities at the mine. Finally, the effects of water that exist in the rock mass, tension cracks, slope face inclination, overall wedge height and double benching on factor of safety of wedge stability are illustrated through limit equilibrium slope stability analyses.

Jan 1, 2002

By A. K. Majumder

Particle motion in fluids is a subject of considerable practical importance to engineers working in fields such as hydraulics, river mechanics, chemical engineering and mineral processing. Many mathematical models have been proposed to predict the terminal settling velocities of particles in a fluid medium. The selection of an appropriate mathematical model has, therefore, become a challenging task for practicing engineers. This paper reports on an attempt to identify some of the useful models found in the literature for predicting particle-settling velocities in a fluid under free- and hindered-settling conditions. From this study, it was concluded that there is no well-accepted model validated by experimental data available for predicting particle hindered-settling velocities in a suspension of polydisperse and polydens particles. Collective efforts should, therefore, be made towards developing a hindered-settling model, as this is an absolute prerequisite for many model structures in mineral processing and other engineering disciplines.

Jan 1, 2007

By Tom Ireland, Tony Rock

The proposed 1.83km long twin bore A3 Hindhead road tunnel planned for contruction in 2008 is being delivered under a Highways Agency Early Contractor Involvement (ECI) contract. The proposed construction methodology is progressive mechanical excavation of a horseshoe shaped tunnel with shotcrete installed close behind the face using robotic spraying equipment. The tunneling medium is a ‘soft rock’ sandstone for which there was little previous tunneling experience, requiring extensive geotechnical investigations and an innovative approach to lining design. A 240m long portal section though sandy material utilising a steel pipe umbrella is also required. This paper describes the development of the tunnel planning and design including the most recent developments in UK road tunnels, and the innovation included in the ‘permanent’ primary lining design.

Jan 1, 2007