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By Wiliam Reisz

As we approach the peak season for thunderstorm activity it’s important to keep in mind that lightning still poses a serious threat to drilling and blasting operations. Lightning remains the number one cause of accidental detonation of explosives.

Jan 1, 2008

By Jun Lu

There are many factors affecting the strength of pillar, including width-to-height (W/H) ratio, mechanical properties of coal and surrounding rocks, property of partings in the coal, and the interface property between coal seam and the roof/floor. In this paper, the effect of varying pillar?s width-to-height ratio (W/H=3, 5, 7, and 10) and coal/rock interface cohesion (Cj =50 psi, 150 psi, and 300 psi) on pillar strength has been studied. The confinement effect of W/H ratio and interface shear strength is investigated by studying their effects on the average minimum principal stress developed in the pillar. The deformation behavior of the coal pillar is investigated. It is found that the pillar?s transition from strain softening to strain hardening behavior depends on its W/H ratio and the interface shear strength.

Jan 1, 2008

By I. Stavrakas

This work studies the variations of the electric current caused by the application of an electric field on marble samples when they are subjected to continuously increasing mechanical stress at a constant rate up to fracture. The external electric field is applied in a direction perpendicular to the applied mechanical stress. An increase of the level of the electric current was observed when micro-damages started to occur in the samples. The increase of the electric current was approximately 14%. Consequently, the current started to decay abruptly and the sample failed. This electric current recording is compared with the corresponding electric recording without applying the external electric field (Pressure Stimulated Current technique). Both recordings show similar qualitative characteristics. The most obvious of these characteristics are that the electric current starts to develop when microcrack structures start to form due to the externally applied stress. Both recordings show a maximum in the vicinity of fracture.

Jan 1, 2008

Underground mining has the potential to be one of the more dangerous industries in the United States and the world. Following recent disasters in Sago, WV; Darby, KY, and Crandall Canyon, UT, the mining industry was reminded of the need for a system to allow trapped miners awaiting rescue to survive following a disaster. To address this need, Battelle has developed a Mine Barrier Survival System (MBSS) that surpasses all current technologies and sets a new standard for keeping miners alive in the event of a fire, flood, explosion or collapse. The MBSS creates a temporary refuge for miners who cannot escape by using inflatable barriers and a post-fire atmosphere scrubbing system to define the ?safe haven? and remove CO2 and CO while replacing oxygen and providing heat. Current personal-protective systems in use are designed to provide breathing air for only a few hours when, realistically, it may take days for rescue teams to reach trapped miners. Battelle?s MBSS is designed to aid up to 15 miners for four days.

Jan 1, 2008

By W. Morgan NeSmith

A drilled displacement pile program was utilized for the expansion of an existing power plant in Cohasset MN adjacent to the Mississippi River. The drilled displacement (DD) pile is an innovative foundation type that provides exceptional value in some geologies. In the U.S., DD piles have typically been used in coarse-grained soils due to the large friction capacities that can be generated by the piles in these conditions. This project was the first large scale experience for the project team where it was anticipated that significant portions of the DD pile capacity would be developed in primarily fine-grained soils. The project site consisted primarily of variable amounts of fill overlying predominantly low plasticity alluvial silts. In some cases, alluvial silty sand layers were encountered within the expected pile installation depths. Alluvial sands were typically encountered below the silts, in some cases within the expected pile installation depths. The project team developed a probe and pile load test program to address the variable subsurface conditions across the site. The program included monitoring various parameters (including applied torque and tool penetration rate) during the drilling portion of the pile installation using recently developed data acquisition techniques. This data was used to estimate the rig energy, or Installation Effort (IE), required for pile installation. IE profiles from the test and indicator piles were compared with subsurface data available from a number of previous site characterizations. Additionally, Cumulative IE values were compared to an in-house database of IE vs. DD Pile Capacity. Final production pile toe levels were based primarily on IE values selected from this comparison. The IE data collected during production was also used to address large variations in pile-cutoff elevation (relative to a fairly uniform ground surface elevation).

Jan 1, 2008

By Jennifer Peirce Brandt

Project documents and the United States Army Corps of Engineers? permit for construction of the Stemmers Run Relief Wastewater Force Main across the Back River in Baltimore County, Maryland specified a minimal width, steel sheet pile cofferdam and a 12 feet wide, pile supported, timber decked, causeway trestle ? both approximately 1700 feet in length. Due to the impractical width of the causeway, the contractor desired to combine the cofferdam and the causeway structures in order to minimize wetland disturbance and maximize access for construction equipment. The resulting support structure was a steel sheet pile cofferdam, approximately 17 feet wide, internally braced, and capped with transverse timber deck mats to serve as the access and work trestle for the trench excavation, pipe bent construction, and trench backfill. Construction of this cofferdam/causeway progressed from the north shoreline toward the middle of the river. Then, working back toward the north shoreline, the contractor excavated, installed the 54 inch diameter pipe and H-pile support bents, and backfilled the trench in increments of approximately 60 linear feet. Excavation spoils from one section were used to backfill the preceding section. As the pipe installation progressed toward the north shore, the steel sheet piling and timber deck were removed. As sufficient sheet piling and deck mats were removed, the contractor began the process anew from the opposite shoreline using the reclaimed materials. The project was complicated by the presence of deep, very soft, weight of hammer, silts and organic clays and an unbalanced, hydrostatic head of 20.5 feet. In addition, concurrent pile driving, excavating, and backfilling in successive cofferdam sections required the use of heavy, long reach, hydraulic backhoes, and a 200 ton capacity crawler crane which controlled the design of the timber causeway deck and its supporting sheet piles.

Jan 1, 2008

Jan 1, 2008

By M. Potesser

After the primary or secondary lead production the bullion lead is remelted and charged into a vessel with following refining process. The removing of arsenic, antimony and tin takes place by salt slags or oxidizing gases like air or pure oxygen. Due to the increasing lead price, Messer Austria GmbH in cooperation with the institute of Nonferrous Metallurgy at the University of Leoben have developed a new process named OXIPOT for the refining of tin, arsenic and antimony. The OXIPOT process is in principle based on purging technology with a ceramic or steel purging device. This leads to an increased retention time of the refining products due to the deeper bath level and an optimized specific reaction volume concerning the bubble size. This paper describes the process, pilot plant, and thermodynamic calculations for the optimization concerning the selectivity of element removal.

Jan 1, 2008

By Liuhuai Ding

Background of Ocean Mining Research Inspired by the 1970?s deep seabed mining activities of other nations, China started ocean mining research work within the framework of the International Law of the Sea Treaty (UNCLOS) and the subsequent establishment of the International Seabed Authority in the 1990?s. This work has been carried out mainly with the cooperation of the Changsha Research Institute of Mining And Metallurgy. We have been committed to this work to fulfill our responsibilities and obligations as a Pioneer investor under UNCLOS and also to support the much needed development of deep-sea technology in China. Exciting recent advances by Nautilus Minerals in the development of seafloor massive sulfide deposit exploitation has led us to a new perspective of ocean mining and some re-evaluation of ocean mining economics. This has provided us with an opportunity to support more efforts in ocean mining research. We will not delay the development of our ocean mining system and corresponding technology, although commercial mining in the deep-sea area may not occur for many years.

Jan 1, 2008

By Yong Hwan, Wang Jian-Jun, Cai Jiu-Ju, Chen Chun-Xia

"The quantity of residual-heat and its recovery in some Chinese sinter plants are investigated. The main factors affecting energy consumption are analyzed using exergy analysis combining energy level analysis. It is indicated that the “gradation recovery and cascade utilize” of discharged gas and sinter residual heat in different temperature is the direction and the available approach to reduce energy consumption of the sinter process. Taking an iron& steel enterprise as an example, the three-ranked scheme of residual-heat recovery is put forward: ?Part of the sinter gas is used for warm-up and dryness; ?The high-temperature part of the cooler and exhaust-heat boiler are actualized as a closed-circuit, which can produce high-quality steam to generate electricity. ?The waste air in low-temperature part is introduced to sintering machine to support combustion. According to the CDQ which can recover the coal heat, the assumption of pot-recovery is put forward to replace the belt cooler. The two equipments of residual-heat recovery are analyzed in the aspect of energy consumption and CO2 reduction.1. IntroductionEnergy consumption in sintering is only inferior to iron-making in iron& steel enterprises, accounting for 10%~20% of the total energy consumption. A lot of residual heat is produced during sintering, and mostly from the sinter ore and waste gas. Sensible heat of hot sinter ore and discharged gas have accounted for 60%[1] (equals to 40 kgce/t-ore), which are the key point of sintering waste heat recovery. Discharge gas of sintering is mostly composed of flue gas deriving from sinter bed’s combustion, and the content distribution of H2O and O2 and the temperature of the gas along the length of belt-type sintering are shown in Figure1[2,3]. Currently, the sensible heat of hot sinter ore is mainly recovered by circular cooler and cooled by blasting air: the temperature of cooled discharge gas brings down from 350? to about 100? along with the decrease of sinter ore temperature. It is significant to recovery and reuse the waste heat as 4000~6000m3 discharge gas per ton of ore can be produced"

Jan 1, 2008

By Michael J. Garlich

Steel sheet piling has a long history of use in a variety of permanent and temporary structures. Current engineering practice uses numerous publications and standards for design guidance. U.S. design guidance is fragmented, with numerous inconsistencies between design guides. To improve current U.S. design practice, the North American Steel Sheet Piling Association has initiated a project to produce a design standard that will unify design procedures and provide specification guidance for engineers and users of steel sheet piling. The wide range of uses for sheet pile structures presents a challenge in developing such a standard. Load factors or allowable stresses acceptable for a temporary retaining wall in soil may reasonably vary from those for a river cofferdam or a dockwall located in sea water. However, it is still possible to provide consistent and rational guidance for such varying uses. The standard also can address sheet pile design aspects often neglected in U.S. publications, such as vertical load capacity and resistance to loads applied parallel to the sheeting.

Jan 1, 2008

By Guozhu Ye, Eric’ Burstrom

"Despite of numerous solutions for recovery of zinc from EAF dust have been suggested and tested in laboratory scale over the last three decades, Waelz kiln process is still the most dominating process for treatment of EAF dust. Few of the proposed alternative methods have gone beyond the laboratory tests. This paper will give you insights to some of the concepts that have been pilot tested at MEFOS. The innovative aspects of these concepts will be shown and the major results will be highlighted. These include the following concepts: - Production of a crude zinc oxide product with low halide content for zinc electrowinning using a DC furnace with hollow electrode- Production of a bypass filter dust containing more than 50%ZnO by injection of EAF dust to the electric arc furnace during refining combined with a bypass filter system- Elimination of zinc ferrite by CaO treatment for electrowinning with EZINEX process - Selective reduction of iron oxide in zinc ferrite for simultaneous recovery of ZnO andmetallic ironIntroductionRecovery of zinc from EAF dust is dominated by the Waelz process since EAF dust has been classified as hazardous waste by EPA in the early 1980´s. A large number of alternative processes have been suggested and tested without commercial success due to two major reasons [1]:- High content of chlorine and fluorine for the pyrometallurgical alternatives- High content of ZnOFe2O3 for the hydrometallurgical processesMany innovative concepts for treatment of EAF dust for zinc recovery have been pilot tested at MEFOS in the past 20 years. This paper will review some of the concepts focusing on the two problems mentioned above."

Jan 1, 2008

By P M. Larionov, V I. Zaikovskii

Transmission and scanning electron microscopy together with X-ray spectral microprobe analysis were used to investigate the structure and chemical composition of pathological calcified formations on the bioprostheses of heart valves. Controllable synthesis was carried out under the conditions (T = 37¦C, pH = 7.4) when the ion composition of the main elements (Ca, P, Mg and NaCl) is close to their concentrations in blood plasma. It is proposed on the basis of the obtained results that the formation of the hydroxyapatite of calcific inclusions on bioprostheses occurs as a result of spontaneous precipitation in the blood plasma. One of the factors determining the formation of massive calcified bodies on the bioprostheses of heart valves can be decreased magnesium concentration in blood.

Jan 1, 2008

By W. J. Birch, R. Farnfield, L. Bermingham

Whilst a significant body of research has been carried into air overpressure levels that arise as a result of the use of explosives, few published studies have actually tried to relate the movement of a quarry face to the resulting air overpressure produced. The aim of this preliminary investigation was to monitor a number of quarry blasts at two different limestone quarries. The first using multiple separately initiated deck charges in a multi borehole blast, the second using single column charges in a multi borehole blast.

Jan 1, 2008

By Bernd Kopacek

"Nowadays more and more consumers substitute their conventional TV-sets and computer monitors by LCD panels. In the near future huge amounts of LCDs will start coming back to recycling. As LCDs with hazardous mercury backlight lamps are used an appropriate recycling technology has to be implemented.IntroductionLiquid Crystal Displays (LCDs) are widely used in notebooks, organizers, mobile phones, pocket calculators, measuring and control instruments, electronic games, hand-held miniature TVs, audio-video equipment, large signboards, automotive displays and more and more also for PC monitors and TVs.According to a study from Stanford Resources (San Jose, California) the annual value of LCDproducts reached 35 billion EUR in 2002, about 30% of this within the European Union, representing a total area of 2,1 million m2 Liquid Crystal Displays. An annual increase rate of about 15% is estimated for the next years (up to 4,1 million m2 in 2005).As LCDs are already on the market for several years, larger quantities of the more than 2,5 billion LCDs are coming into their End-of-Life stage for treatment. In 2005 this figure will become even more dramatic - 40.000 tons of LCD-modules contained in 2 million tons of waste electrical and electronic equipment (WEEE) or about 30% of total WEEE within EU. An amount which is representing 400 million EUR costs for incineration.Currently the only method used to deal with redundant LCD units is incineration or landfill. Both are expensive and causes emissions into the atmosphere (global warming) respectively water contamination (Class II) and difficulties in biodegradation. Up to now there is no recycling solution for LC-Displays available.As a consequence European Commission requests the disassembly of LCDs with an area bigger than 100 cm2 in the Directive 2002/96/EC of the European Parliament and of the Council on Waste Electrical and Electronic Equipment (WEEE Directive) of February 13, 2003."

Jan 1, 2008

By P Collins, C Sheriff

The Sand Queen gold mine is a typical Archaean narrow, high-grade gold quartz lode deposit within a shear hosted system. Initial mining during 1904 - 1948 produced 181 659 ounces of gold from 248 564 tonnes of ore milled at an average production grade of 22.7 g/t Au, which equates to a minimum of 750 ounces per vertical metre. The current mining operation is using the old Sand Queen main shaft to access the Sand George deposit, which is a narrow quartz lode system discovered in the same shear structure along strike to the south of the Sand Queen mine workings. Current underground resources contain 360 200 tonnes at a grade of 11.8 g/t Au for 136 500 ounces. Mining is scheduled to produce 20 000 ounces of gold annually. Re-opening of the Sand Queen mine and underground development of the Sand George lodes has revived several grade control issues relevant to a narrow, ænuggettyÆ gold lode mining environment. These include the dependence of assay grade of individual samples upon a number of factors, including how and where a sample is collected, how and where it is analysed, and how grade data is used to estimate an æaverageÆ grade. Ideally, the only way to achieve an acceptable estimate of ætrue gradeÆ is to mine and mill a large parcel of ore (eg >100 tonnes) from each lode or ore type. In a mining operation producing relatively small tonnages from a number of separate ænuggettyÆ gold lodes, availability of resources and operational constraints may preclude intensive sampling for predictive grade control. At the Sand Queen mine, one of the key issues has been to establish a reliable system for estimation of gold grade with which to reconcile milling data. Extensive use has been made of detailed geological data to understand the grade distribution within individual lodes and between lodes, so as not to rely solely on assay results.

Jan 1, 2008

By J St George

Much of AucklandÆs transport infrastructure has been developed on surface with little or no consideration of underground options. Current and planned transportation routes are now facing high costs due to land values and increasing environmental resistance to surface development. The option of utilising underground space becomes a feasible investment decision for these links as well as being the only option to develop the rail network within the inner city area. Transportation tunnels offer a quieter, more energy efficient means of getting around with minimal impacts on the surface environment. One of the major impediments to tunnelling is the high construction cost, which is partly related to the risks of encountering unexpected ground conditions and/or the possibility of causing surface ground deformations which could damage structures. The geology of Auckland has had substantial investigation through various studies and projects. The sediments of the East Coast Bays Formation (ECBF) underlie most of the Auckland urban area. It is classified as a soft rock and is a suitable material to tunnel through using either a tunnel boring machine or a roadheader. This paper reviews the limited amount of tunnelling completed in the urban Auckland area, together with the international advancements that have been made in the tunnelling industry. From the known features of the local geology and the problems encountered historically, the likely risks of tunnelling in Auckland are presented and ways in which those risks could be reduced and managed, are discussed. In addition, contractual arrangements between client and contractor are assessed with respect to complicated projects (such as tunnelling), so that the risks can be managed to create efficient infrastructure routes with reduced costs.

Jan 1, 2008

By David Van Horsen

Operation and maintenance of California?s water tunnels is an important factor and vital link in California?s infrastructure. These tunnels are owned and operated by a variety of large and small private and public water and power utility companies, municipal agencies, and irrigation districts. Visionary pioneers such as Michael O?Shaughnessy (San Francisco Hetch Hetchy Water Supply System), William Mulholland (Los Angeles Department of Water and Power and Metropolitan Water District of Southern California?s Colorado River Aqueduct), and John Eastwood (Southern California Edison Big Creek Hydroelectric Project) built large and small water supply, irrigation and hydroelectric tunnels, which have supplied environmentally friendly-water supply, renewable electricity, and uninterrupted service to a burgeoning population and economy. This paper introduces these pioneers and describes several case histories and lessons learned during condition assessment and rehabilitation of tunnels providing enlightenment of California?s vital water projects.

Jan 1, 2008

By A M. L Smith, W E. Dubbin, K A. Hudson-Edwards

Jarosites (KFe3(SO4)2(OH)6) are examples of minerals that are highly effective scavengers of toxic elements, and are abundant in acid rock drainage systems, acid sulfate soils, metallurgical wastes and other contaminated sites. The K, Fe and S sites can be filled by toxic elements such as Cd, Cu and Zn, but the mechanisms of this incorporation are not well understood.We have used atomistic simulation methods to model the jarosite (102) surface and its interactions with Cd, Zn and Cu, in order to understand the mechanisms by which these potentially toxic elements are incorporated into the K-jarosite structure. Our results suggest that incorporation via a defect complex consisting of an impurity cation at the K site charge balanced by a K vacancy stabilises the (102) surface in the order Cu>Zn>Cd.

Jan 1, 2008

By Brian Fulcher

The Arrowhead Tunnels Project represents the final portion of a 70 km (44-mile) long water conveyance facility that will bring up to 28 m3/sec (1,000 ft 3/sec) of water into Southern California. The 13 km (8-mile) tunnelling project is well underway and consists of two, 5.8 m (19-ft) diameter TBM bores through extremely variable geological conditions. An extensive and essential pre-excavation drilling and grouting program was performed in all reaches of the Arrowhead Tunnels Project, located north of San Bernardino, CA. This program supported the advance of two hybrid hard rock TBMs though extremely challenging ground conditions under substantial ground cover and up to 27 bar (900 ft) of ground water pressure. The well known San Andreas Fault lies nearby and has greatly influenced the local geological conditions. This paper will describe the means, methods and materials used throughout the numerous phases of the pre-excavation grouting program. It will also describe many versatile, flexible and innovative drilling and grouting methods and equipment systems utilized to improve performance, save time and costs in constantly changing geological conditions. Considerable lessons learned have been learned while overcoming some extremely formidable ground conditions and safely advancing the tunnels.

Jan 1, 2008