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By Rodrigo Jerez

Advances in inexpensive computer automation led to the development and use of a computerized ore control system at the Cyprus Copperstone Gold Mine near Parker, AZ. These new ore control practices improved accuracy, performance and productivity of the ore control effort. An automated system for data collection, including bar coding of blasthole samples, laboratory analysis, data management, grade estimation, cut delineation and ore zone stake out, plays a major role in ore control practices. This is of particular interest because of the large amount of blasthole information being processed, analyzed and reported daily. Copperstone Gold management has been progressive toward new, efficient methods regarding ore reserve estimation, long-term mine planning, short-term mine planning, ore control and surveying. Technological advances, including powerful personal computers, applicable mine planning software and surveying instrumentation, have become readily available and affordable. The computerized ore control procedures used at Copperstone include sample data collection, laboratory automation and computerized data management. These have reduced the time to complete ore control on a blast pattern by 50% to 75%. The final product - ore control - is generated in a more timely and accurate manner.

Jan 1, 1991

By A. K. Dikshit, H. R. Murty, S. K. Gupta

This paper deals with the development of environment performance indicators (EPIs) for the steel industry. Environmental performance has become one of the key measures of business success. Emergence of continuing pressure from customers, employees, government and NGOs for environmental performance evaluation (EPE) of industries has led to evolve a framework for the development of sector specific environmental performance indicators. EPIs can be used by steel industry for assessing the continual improvement in environmental perfromance, selecting various eco-friendly options, benchmarking, environmental reporting, technology assessment and dissemination, evaluating environmental impacts and building EPIs based environmental management systems. The objective of this paper is to develop EPIs for steel industry and provide framework for development of environmental performance indicators based environmental management system and its integration with the overall management system. An indepth discussion has been presented concerning identification of EPIs, eavaluation of significance of EPIs, their prioritization and its integration with Environmental Management Systems. A new methodology has been proposed for implementing EPIs based environmental management systems . The material presented is derived in part from PhD studies of Rajesh Kumar Singh.

Jan 1, 2005

By M. Sadegh Safarzadeh, Stanley M. Howard

The two-dimensional predominance area (Kellogg) diagram (PAD) surfaces bounding the three-dimensional Cu-As-S-O system were constructed at 900 K. The computations employed gases As4O6(g), O2(g), and SO2(g) as the independent coordinate species to generate diagrams of As4O6(g) − O2(g),O2(g) − SO2(g), and As4O6(g) − SO2(g), while the third gas (As4O6, O2, or SO2) was fixed. The results indicate that there is no shared boundary between enargite (Cu3AsS4) and copper sulfate (CuSO4); however, at PO2 < 10−6 atm, PAs4O6 < 10−10 atm, and PSO2 > 10−4 atm, CuSO4 is the stable phase at 900 K. The chemical driving force for oxidation of intermediate phases between enargite and copper sulfate is substantial except for basic sulfate (CuO · CuSO4).

By M. Sadegh Safarzadeh, Stanley M. Howard

The two-dimensional predominance area (Kellogg) diagram (PAD) surfaces bounding the three-dimensional Cu-As-S-O system were constructed at 900 K. The computations employed gases As4O6(g), O2(g), and SO2(g) as the independent coordinate species to generate diagrams of As4O6(g) − O2(g),O2(g) − SO2(g), and As4O6(g) − SO2(g), while the third gas (As4O6, O2, or SO2) was fixed. The results indicate that there is no shared boundary between enargite (Cu3AsS4) and copper sulfate (CuSO4); however, at PO2 < 10−6 atm, PAs4O6 < 10−10 atm, and PSO2 > 10−4 atm, CuSO4 is the stable phase at 900 K. The chemical driving force for oxidation of intermediate phases between enargite and copper sulfate is substantial except for basic sulfate (CuO · CuSO4).

The theme of the 2012 North American Tunneling conference (NAT) was ?Tunneling: Driving Value.? This theme best reflects where the tunneling and underground construction industry is to-day. Major advances that have been made in technologies have provided tremendous improvements in productivity, which, in turn, have allowed the industry to deliver more cost-effective and less disruptive solutions to the nation?s infrastructure needs. Despite a weak economy, domestically and globally, cities and states continue to spend billions on infrastructure improvements. For the underground construction industry, that means more transportation and water, wastewater, storm water projects and other underground structures. And, for each project completed, underground construction and tunneling technology grows. The NAT conference, put on by the Underground Construction Association (UCA) of SME, provides an outlet for technology transfers among professionals. This year?s conference, held in Indianapolis, IN June 24-27, attracted 918 attendees, up from 803 at the last NAT in 2010. The accompanying exhibit also featured 116 exhibitors occupying 140 booths. That was up from 108 booths in 2010. So, the meeting continues to grow as underground construction professionals throughout the world seek to learn from their peers.

Jan 1, 2012

By Paul S. Fisk, Arne Fareth, Julie Frietas, Francis Lo, Fidel L. Mallonga

INTRODUCTION This report describes the inspection of parts of the New Croton Aqueduct (NCA)undertaken for the New York City Department of Environmental Protection (NYCDEP)by Parsons Brinckerhoff Quade & Douglas, Inc., (PB) in association with Montgomery Watson Engineers of New York, P.C. (MWH). Support for the inspection was provided by AFC Enterprises, Inc., under Construction Contract CRO-333, “WM-11 New Croton Aqueduct Rehabilitation and Inspection Program.” The scope of the inspection work under CRO-333 included assessing the condition of the 10.3 km (6.4 mile) long, pressurized section of NCA and inspection of shafts, head houses and blow-off structures in both the pressurized and gravity sections. The CRO-333 inspection continued investigation work begun under ContractCRO-196, which ran from 1993 to 1997. The CRO-333 inspections were conducted from November 2004 to September 2005. Background The New Croton Aqueduct was put into service in 1891 to deliver water from the Croton River Watershed in Westchester County to consumers in New York City. Figure 1 shows the location plan of Croton Water Supply System. The design flow into Jerome Park Reservoir was 12.7 m3/s (290 mgd) and into the135th Street Gate House, further south, was 10.9 m3/s (250 mgd). The NCA has been operated as a gravity conduit from Croton Lake to Gate House No. 1, just north of Jerome Park Reservoir, since its original construction. The length from Gate House No. 1to 135th Street, which includes a major siphon under the Harlem River, has been operated under pressure. Croton Lake gate house, the north end of the alignment lies at Station 4+75; Shaft 33, the south end of the alignment lies at Station 1628+05. The diameter of the tunnel is 3.2 m (10.5 ft) in the siphon and 3.7 m (12.3 ft) in the Bronx and Manhattan sections. The pressurized sections, constructed in rock, consist of a brick lining surrounded by a mortared and grouted rubble backing. Figure 2depicts a typical tunnel cross section. The objective of the shaft and tunnel inspections was to locate and document defects, such as leaks, deterioration of lining material, cracks, spalls, delaminations,

Jan 1, 2007

By Vincent Tirolo

The proposed Second Avenue Subway is a new two-track subway line running from 125th Street and Park Avenue at the north, east along 125th Street to Second Avenue and south along Second Avenue to the Financial District in lower Manhattan, NY with 16 new stations and 13.6 km (8.5 miles) of track. The project has been broken into four construction phases. The initial Phase 1 operating segment includes three new stations (96th, 86th and 72nd Street stations) with a connection to the existing Broadway line at the 63rd Street Station at Lexington Avenue. Rehabilitation of the 63rd Street Station is also included in the scope of Phase 1. Subsequent phases extend service north and west to 125th Street (Phase 2), south to Houston Street (Phase 3) and finally to Hanover Square (Phase 4). The DMJM Harris/Arup Joint Venture (DHAJV) prepared the Contract Documents MTA for Phase 1. Parsons Brinckerhoff is providing the MTA with construction inspection services for Contract C-26002. In April 2007, NYCT awarded first Phase 1 for $337 million to S3 Tunnel Constructors, a tri-venture comprised of Skanska USA Civil, Schiavone and Shea. Contract C26002 is for the construction of the tunnel boring ma-chine (TBM) launch box and the mining of the TBM tunnels from 92nd Street to 63rd Street. The major part of the contract is to construct a shaft, commonly referred to as the launch box, from East 92nd Street to East 95th Street having dimensions of 244-m- (800-ft-) long by 18.9-m- (62-ft-) wide and a depth of 19.8 m (65 ft), including more than 91,000 m3 (119,000 cu yd) of soil and rock contained within its walls. The launch box will ultimately become the southern half of the 96th Street Station. The focus here is geological conditions at the launch box and existing structures along the launch box. These geologic conditions and existing structures had a major influence on the selection and design of the support of excavation system (SOE), the SOE bracing system, construction staging, the ground movements, dewatering and other challenges of constructing the launch box (Fig. 1).

Jan 1, 2013

By B. Slaker

The ability to detect and quantify ground movements in underground mine workings is of the utmost importance to the safety of miners and continuity of operations. Rib sloughage is one of the most common forms of underground deformations. Remote sensing techniques, such as laser scanning, can be used to quantify this rib sloughage, by recording precise, time-lapse point clouds of mine workings. In order to determine sloughage volumes and locations, a total of 11 laser scans were performed 41 days apart at a working section of an underground limestone mine. During this period, significant sloughing and scaling occurred, allowing for differentiation between the initial and final point clouds.

Feb 27, 2013

By Remo Grandori

The Umiray Angat 13,2 km long tunnel in Philippines have been bored through extremely variable and difficult ground conditions including a number of special events. In particular the following adverse conditions were found: faults in decomposed ground, high temperature rocks, extremely rapid and important convergence phenomena, water inflows up to 800 litres per second. The special El Nino climatic conditions caused a long dry season and lower the level of the lake that was granting the access by barge to the site under the minimum navigable level. Many equipment have had therefore to be transported to site by a 10 ton capacity helicopter, after having been partially dismounted. For the same reason most of the tunnel drive have been bored servicing the site by 1 ton capacity helicopters to transport materials, spares and personnel. In order to overcome the above geological and logistic problems several innovation were introduced and tested in this project. Despite all that difficulties the 13,2 km of tunnel were bored in about 24 months, with a global average of 500 m/month.

Jan 1, 2001

By Wern-ping Chen

To mitigate and control the combined sewer over-flows from 17 outfalls in Detroit, MI, three outfalls in Dearborn Heights, MI and eight outfalls in Redford Township MI, the Detroit Water and Sewerage Department (DWSD) completed the preliminary design of a storage tunnel in 2005. In 2006, a final design revised the alignments and the inside diameter (ID) of the tunnel. The revised tunnel system includes an 11.28-km (7-mile) 9.14-m (30-ft) ID tunnel, a 24.4-m (80-ft) ID pump station, two work shafts about 15.2-m (50-ft) ID each and 14 drop shafts with various IDs. A small portion of combined sanitary and storm sewers serve the majority of the Rouge Valley water-shed. This includes Detroit, MI and most of the western suburbs. The Northwest Interceptor (NWI), that extends between Eight Mile Road and Ford Road and roughly parallel to the Rouge River, intercepts sanitary sewage and some wet weather flows from trunk sewers in the tributary areas for transport to the wastewater treatment plant (WWTP) for treatment. During extreme storm events, when the capacity of the NWI is exceeded, the excess combined sewer and overflow (CSO) over-flows into the Rouge River through 17 outfalls to local rivers. The purpose of the Upper Rouge Tunnel system (URT) is to capture and significantly reduce the uncontrolled CSO from these 17 outfalls in Detroit, three outfalls in Dearborn Heights and eight outfalls in Redford Township. When implemented, the

Jan 1, 2007

By B. K. Blashich

In responding to mine fires and explosions, accurate and timely analysis of the mine atmosphere is critical in making decisions regarding firefighting, mine rescue and mine recovery operations. For many years instantaneous analyses were available to rescue workers using handheld or portable gas detection equipment, including infrared, electrochemical, or catalytic measuring devices for a limited number of specific gases such as oxygen, methane, carbon monoxide and carbon dioxide. Instantaneous sensing technology is not available for all gases, such as nitrogen and hydrocarbons, found in a mine fire atmosphere and cross-sensitivity can be a problem with this technology. For these reasons, air samples are collected for injection into a gas chromatograph for a complete and accurate analysis for all gases including oxygen, nitrogen, methane, carbon monoxide and carbon dioxide, as well as ?fire gases? such as hydrogen, ethylene, ethane, and acetylene. This method requires additional time for transporting the samples to the laboratory near the mine, as well as an instrument operator to inject the samples for analysis. The use of a portable micro gas chromatograph with a continuous and automatic injection system has been implemented by the Mine Safety and Health Administration (MSHA) during mine recovery operations. The device directly samples the mine atmosphere from an underground location every twelve minutes and automatically analyzes the samples for all of the mine fire gases. The portable unit utilizes micro technology and the operating software has been modified to perform the calculation of sample results in and Excel® spreadsheet without user interaction. This paper describes the micro gas chromatograph system and its use at a recent mine recovery operation. The automated remote operation of the micro gas chromatograph has been shown to be a good alternative to infrared and electrochemical sensors used for mine atmosphere analysis.

Jan 1, 2009

By D. W. Olson

Garnet has been used as a gemstone for centuries. However, garnet’s angular fractures, relatively high hardness and specific gravity, being chemically inert and non-toxic and free of crystalline silica, and its ability to be recycled make garnet ideal for many industrial applications. Garnet is the general name given to a group of

Jan 1, 2005

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

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

Jan 1, 2005

By F. D. Ayhan

The aim of this study was to investigate the effects of various water mediums on desulfurization and deashing of a coal sample using flotation. For this purpose, experimental studies were conducted on a coal sample containing high ash and sulfur contents. The effects of pH, solid concentration, collector amount and frother amount on the flotation were investigated separately in Mediterranean Sea water, Çermik thermal spring water, snow water and tap water. Flotation results indicated that, when comparing the various water mediums, the following order for the ash content was obtained: snow water < Çermik thermal spring water < tap water < the Mediterranean Sea water. For the reduction of total sulfur, the following order was obtained: snow water > Çermik thermal spring water > Mediterranean Sea water > tap water. When snow water was used as a flotation medium, it was found that a concentrate containing 3.01% total sulfur and 27.64% ash with a total sulfur reduction of 57.06% was obtained from a feed containing 7.01% total sulfur and 41.17% ash.

Jan 1, 2009

By Robin J. Batterham, Dave J. Robinson

The history of mineral processing in general and flotation in particular is long and has always been tied to mining methods of the day. Building on the ever-improving fundamental understanding of the underlying science, the most significant trend in flotation has been the putting into practice the learnings from trailblazers such as Professor Fuerstenau that has given the confidence that enabled an ever-increasing scale of operations. There is, however, doubt this ongoing trend is enough to maintain the economics against global trends such as that of falling grades, increasing mining costs, pressure on water supply and demand, rising energy demands needed for mineral processing, and a focus on whole of life value and mine legacy issues. In addition, we see that globally, the social license to operate for mining (and hence mineral processing) is far from secure and, at the very least, is under much more rigorous scrutiny. In this paper, we comment on the ramifications of broader uptake of more sustainable mining for mineral processing methods and address the specific question of whether recent progress in in-place recovery will lead to a timely breakthrough. The answer proposed is that this is possible in the next 10–20 years but in the meantime, the focus is just as likely to be on removal of waste (beneficiation) much earlier in circuits. Either way, mineral processing and flotation, as we know it, will change significantly.

Sequential and evolutionary changes through time are recognizable in many, perhaps most major families of ore deposits and their geological environments. These changes are additional useful indicators of the evolutionary history of the earth and its tectonic processes. They are important in mineral exploration because they involve consideration of time as a fourth dimension, thereby indicating the most favorable ages, rather than types of rock for investigation. Many of the changes are analogous to those recognized in faunal evolution. Some primitive, unspecialized types of ore deposits occur nearly unchanged through rocks of widely differing age. Others diversify into several, more specialized variants, whereas still others become extinct. The place of these is taken by new, younger types, some of which undergo sudden proliferations and later diversifications of their own. In Archean greenstone belts irrlportant iron, nickel, gold, and base metal deposits occur co-regionally, but in different stratigraphic positions in the same, thick volcano-sedimentary successions. Here their close temporal and spatial associations suggest common genetic exhalative hydrothermal processes. The massive base metal sulfide family of ore deposits provides an excellent example of evolutionary changes, exhibiting distinct variations through both time and space. Deposits belonging to this family span the entire range of time, occurring in rocks of ancient Archean to Recent age, and specific types within the family also span the entire range of spatial environments from ensimatic to ensialic. Moreover there are possible evolutionary metallogenic links between certain types of massive base metal sulfide deposits and other important base metal ores, noteably Mississippi Valley-type and porphyry copper deposits.

Jan 1, 2013

By C. Mark, D. M. Pappas

From 1999 through 2008, groundfall events resulted in 75 fatalities, 5,941 injuries and 13,774 noninjury roof falls in U.S. underground coal mines, according to the U.S. Mine Safety and Health Administration (MSHA). A comprehensive analysis of these events was conducted to better understand where and why these incidents occurred. The first segment of the study used the MSHA database to evaluate groundfall injury rate trends related to mining method, year, locality, seam thickness, mine size, coalbeds and seasonal effects. In the past decade, roof fall injury rates have dropped 50%, but rib fall injury rates have remained constant. Room-and-pillar mines had a roof fall injury rate that was nearly 2.5 times the longwall rate. High groundfall rates occurred in the Illinois Basin, a finding that correlates with other studies that have shown that roof rock in the Illinois Basin is weaker than that in the central Appalachian coalfields. Finally, noninjury roof fall rates in the eastern and central United States were found to be 50% higher from July through September, possibly because of the changes in humidity levels that may cause shale mine roofs to deteriorate. The second segment of the study evaluated the root causes of failure by reviewing all MSHA groundfall fatality reports for 1999-2008. Pillar recovery was the leading cause of groundfall fatalities (19%), followed by rib falls, roof skin falls and traveling under unsupported roof (16% each). Defining prominent ground control incident trends and hazards will identify areas where additional study is needed and where innovative solutions need to be developed to reduce these severe occupational hazards.

Jan 1, 2011

By D. Bessinger, J. M. A. Geldenhuis

High titania slag is produced from the smelting of ilmenite. These slags contain approximately 85 per cent TiO2 and consist mainly of a M3O5 solid-solution phase. During cooling the slag can decrepitate to a fine particulate material, which decreases the value of the product. Based on X-ray diffraction analyses of the decrepitated slag after cooling, it was found that the M3O5 phase had almost disappeared. The disappearance of the M3O5 phase was linked to oxidation of the slag. A M6O11 phase formed in the decrepitated slag. It is postulated that decrepitation of high titania slag is caused by volume changes due to the oxidation of the M3O5 phase in the slag.

Jan 1, 2005

By J. O. Marsden

Over the past eight years, Phelps Dodge (a subsidiary of Freeport-McMoRan Copper & Gold, Inc.) devoted a significant amount of effort to the development of a suite of processes for the effective hydrometallurgical treatment of copper sulfide concentrates. This effort resulted in the development of high-temperature (>200ºC) and medium-temperature (150° to 165ºC) pressure leaching processes. Specific configurations of both processes have been commercially demonstrated at Phelps Dodge?s facility in Bagdad, Arizona. This paper reviews in detail the chemistry of medium-temperature pressure leaching of copper concentrates and reports on the process development work conducted by Phelps Dodge and others for this technology. This paper is Part I of a four-part series on this technology. Part II covers the development of medium-temperature pressure leaching and direct electrowinning technology; Part III considers the large-scale demonstration of the MT-DEW-SX process at Bagdad, Arizona; and Part IV addresses the development and design of a full-scale commercial application at Morenci, Arizona.

Jan 1, 2007

By J. S. Young

During 1975, the Reclasource Corporation constructed and commissioned a plant for the recovery of mill scale, coke breeze, blast furnace dust, blast furnace sludge and basic oxygen furnace dust at the site of Crucible Alloy Division, Midland, Pennsylvania. The Reclaform Process was employed as the criteria for plant design. This Process takes the solid in-plant fines as listed above, commonly found in integrated steel mills, sizes and forms them through the use of a carbonaceous binder briquetting system and cures the binder through a final heat-treating step. 15,000 tons of Reclaform briquets have been tested in the Crucible blast furnace in several campaigns structured to assess material handling properties, burden feasibility and finally culminating in an iron and carbon assessment campaign. Data are presented from the records of the blast furnace operation and conclusions are drawn that both iron and carbon utilization have been demonstrated.

Jan 1, 1977