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By Xinzhi (Thomas) Du

"A longwall mining method is a productive mining method of coal extraction that involves the complete removal of large, rectangular panels of coal. Since this method causes deformations through the overlying strata to the ground surface, the surface- and ground-water regime above the longwall panels may be adversely affected and drained into the lower strata. The purpose of this study is to determine the effects of longwall mining subsidence on surface- and ground-water systems.This study is a site-specific hydrogeologic analysis conducted before, during, and after panel retreat at a site located over two selected longwall panels in the Pittsburgh coal seam in Greene County of Pennsylvania. Mine subsidence causes fractures in the overlying strata and enlarges bedding plane separations, increasing the effective porosity and storativity of the overlying strata. Generally, the water in deeper aquifers located in the lower fractured zone drains into the mine void due to the vertical fractures. Moreover, the water level does not recover after longwall mining (but may recover when the mine is flooded). The upper aquifers over the thick aquitard layers may maintain the water level or drop slightly during longwall mining and recover very quickly. The reason is that the underlying aquiclude layer has less change in porosity and permeability after longwall mining (Carver, 1994).A groundwater flow model-MODFLOW was used to predict the water table contours for the periods of pre- and post-mining conditions. The hydraulic gradients of post-subsidence became larger outside the panels and smaller inside the panels than that of the pre-subsidence. The groundwater hydraulic heads above the longwall panel dropped a maximum 50 ft in the study panels. The shallows monitoring wells that were less than 50 ft deep from the surface were deeply affected by longwall mining subsidence. For the intermediate wells that were more than 85 ft deep from the surface, where strata movement acted as a unit during longwall mining subsidence, there were little impacts of longwall mining on the intermediate wells in the study area. For the deep wells that were located below the Waynesburg sandstone, the water was drained to the underlying strata or even into the mine gob."

Jan 1, 2019

By Rolf S. Paine

The Bureau of Mines studied the presplitting technique used for control-ling overbreakage in the walls of a vertical shaft at the U.S. Army Corps of Engineers Littleville Dam project near Huntington, Mass. The periphery of the shaft, the dimensions of which were 16-1/2 feet wide by 21 feet long and 52 feet deep, was presplit (cracked) in the solid to a depth of 48 feet prior to full-depth sinking. Presplitting prevented overbreak in a fairly soft schist and provided sound self-supporting walls which required very little scaling.

Jan 1, 1965

By Rolf S. Paine

The Bureau of Mines studied the presplitting technique used for control-ling overbreakage in the walls of a vertical shaft at the U.S. Army Corps of Engineers Littleville Dam project near Huntington, Mass. The periphery of the shaft, the dimensions of which were 16-1/2 feet wide by 21 feet long and 52 feet deep, was presplit (cracked) in the solid to a depth of 48 feet prior to full-depth sinking. Presplitting prevented overbreak in a fairly soft schist and provided sound self-supporting walls which required very little scaling.

Jan 1, 1965

By L Chaffey, M Buckland

The minerals industry has enormous potential to positively contribute to sustainable development and many leading companies have concluded that their long-term success is directly linked to their ability to leave a lasting positive legacy. While there are many examples of success, there have been failures as well and much work has been done in recent years to define the role of the minerals industry in sustainable development and identify the key elements for success. In the past, our sector could point to the taxes and royalties it paid, the exports it generated and employment it created and felt confident that its contribution would be recognised and duly acknowledged. This is no longer the case. Critics of the industry have highlighted resource-rich countries that have failed to capitalise on their resource wealth and have arguably lower standards of living than their resource-poor peers û the æresource curseÆ hypothesis. Recent research has done much to clarify the factors that contribute to a countryÆs success or failure and all stakeholders in the industry now need to include these learnings in their approaches going forward. We know that our long-term success relies on embedding a company- wide approach to sustainable development into all aspects of our business operations. In this paper we highlight BHP BillitonÆs experience in the development and implementation of policies and systems designed to enhance our contribution to sustainable development. We detail the business drivers for excellence in this area and the key external codes and initiatives that have shaped our approach. The values-based BHP Billiton Charter, Sustainable Development Policy and associated Health, Safety, Environment and Community (HSEC) Management Standards are central to our approach. Implementation is reviewed through our HSEC audit program. One area in which we have placed particular emphasis is our approach to community development. BHP Billiton has a corporate target to contribute one per cent of its pre-tax profit on a three year rolling average to voluntary community programs. As our profit stream has increased with the minerals boom this is approaching an A$100 million commitment. In our paper we detail how we are working to ensure we maximise the value of this contribution for our communities and our shareholders.

Jan 1, 2006

By Michael J. Fiannaca

Disseminated epithermal gold metallization occurs within a breccia unit interpreted to be a submarine debris flow. Cold is associated with oxidized pyrite, fluorite, and jasperoidal silica. A minimum of 9 million tons of open-pittable mining reserves will be cyanide heap leached as run-of-mine ore at a rate of 1.0 million tons per year. Careful evaluation of the combined results of successive sampling projects has established the pit plan, mineable reserves, and process metallurgy of the operation. The sampling procedure utilized for a given test depended upon geological interpretation as well as the procedures, successes, and failures of previous tests. This paper summarizes the sampling and testing procedures of the development effort in light of the project goals and attendant problems in achieving them.

Jan 1, 1984

By M J. Thomson, P T. Burgin

The economic growth of Hong Kong and adjacent territories in Southern China is, to a considerable extent, dependant on air transportation, but the present Kai Tak Airport is incapable of expansion to meet future needs. After years of study, agreement was reached to build a new airport on the island of Chek Lap Kok, some 34 km remote from Hong Kong, with an ultimate capacity of 87M passengers and 8.9 Ml of cargo per annum. Apart from the building of the airport and its associated infrastructure (including a new town), other similar massive construction works have been necessary in the form of land reclamation from the sea and existing outer lying islands. The construction of bridges, tunnels, railways and highways are also an integral part of the project. The paper provides a broad overview of the concepts of the scheme (called The Airport Core Programme) and highlights some of the major operations and equipment being used in the projects, whose cost at 1992 prices was reckoned to he Hong Kong (HR)$l63hn.

Jan 7, 1997

By Milan Yekich, Emanuele Cauda, Justin Patts, Cody Wolfe

A worker’s personal exposure to respirable dust in occupational environments has traditionally been monitored using established methodologies which entail the collection of an 8-hour representative sample that is sent away for laboratory analysis. While these methods are very accurate, they only provide information on the average exposure during a specific time period, generally a worker’s shift. The availability of relatively inexpensive aerosol sensors can allow researchers and practitioners to generate real-time data with unprecedented spatial and temporal granularity. Low-cost dust monitors (LCDM) were developed and marketed for air pollution monitoring and are mostly being used to help communities understand their local and even hyper-local air quality. Most of these integrated sensing packages cost less than $300 per unit, in contrast to wearable or area dust monitors specifically built for mining applications which have been around for decades but still average around $5,000 each. At the National Institute for Occupational Safety and Health (NIOSH), we are leveraging the power of high-volume data collection from networks of LCDM to establish baseline respirable hazard levels and to monitor for changes on a seasonal basis as well as following any application of control technologies. We have seen the effective use and advantages of monitoring live data before, during, and after events like shift changes, operational changes, ventilation upgrades, adverse weather events, and machine maintenance. However, many factors have prevented a systematic adoption of LCDMs for exposure monitoring: concern for their analytical performance, the complexity of use, and lack of understanding of their value are some factors. This contribution outlines a one-year case study at a mine in Wisconsin USA, covering the installation, maintenance, data visualizations, and collaboration between NIOSH researchers and the industrial hygiene professionals at the mine.

Feb 1, 2024

By A. Deneys

This paper reviews industrial gases used in primary copper production. Copper smelting industrial gas demand has steadily increased since the first commercial oxygenconcentrate smelting in 1952 [1]. In copper production oxygen for smelting is the dominant industrial gas use followed by oxygen for converting. Nitrogen is finding increased use in copper smelters. Nitrogen is used for porous plugs for copper converting and anode refining [2-5]. Nitrogen can be used for concentrate drying [6,7] and is also used in some Ni-Cu smelters as a coolant in Peirce-Smith converting [8,9]. Industrial gas supply options of cryogenic or adsorbent based on-site plant or cryogenic liquid delivery are detailed.

Jan 1, 2007

By C. A. Geffen-Fowler

This report, sponsored by the Bureau of Mines, presents the results of an examination of the safety of the Blind Shaft Borer (BSB) shaft sinking system and an alternative modified BSB design concept in comparison to conventional shaft sinking technology. Detailed study of the two systems was also performed to identify and recommend design changes for optimum safety conditions. A comparison of the BSB systems with conventional shaft sinking was made on the basis of relative risk levels. Risk incorporates both the frequency and the potential consequence of accidents. A safety evaluation of the component operations of the two BSB systems was performed using a Failure Modes and Effects Analysis (FMEA) methodology. The results of this analysis show generally that both BSS systems are safer than conventional shaft sinking. The potential risk of conventional shaft sinking operations could be reduced by over 30%, on the average, with the use of the original BSB system, and by an average of about 10% with the modified BSB. Design change recommendations to further improve the safety of these systems include a better fire suppression system, improved man haulage systems and more compact hydraulics. An operational safety manual was also developed for the modified BSB system.

Jan 1, 1981

Jan 1, 1994

By Donald A. Ranta

Every mineral project or mine is based on a geologic entity-an ore (mineral) deposit. A well-defined mineral deposit and its associated geologic characteristics are the only aspects of a project that cannot be altered. Mine plans can be modified to exploit the deposit using alternative approaches and yielding similar results. A variety of processing methods also are often available producing generally comparable results. Major modifications can be made to other aspects of the project without substantially changing project economics. However, all engineering and metallurgical aspects of a mine must be accommodated to the spe¬cific location and geologic characteristics of the deposit. Geologic data and interpretations form the foundation for both mine evaluation and mine production by providing esti¬mates of reserves and essential information for mine planning and process design or control. Proper geologic work requires a keen awareness of and an ability to anticipate the technical requirements of geotechnical engineers, hydrologists, mining engineers, metallurgists, and other specialists. Geologists are inte-

Jan 1, 2008

By H. Sevim

Placement of coal combustion byproducts into abandoned sections of underground coal mines for the purpose of subsidence mitigation has been investigated in Illinois. Several handling and transportation systems have been examined. Prototype pneumatic and hydraulic placement systems have been developed and demonstrated. The demonstration site, Peabody No. 10 mine in Pawnee Illinois, is selected as a case study. It is found that, for a project of 5 years, transporting 150,000 tons of byproduct annually from a power plant located 32 km (20 miles) to the mine would cost $1.80 per ton and placement into underground would cost $3.07 per ton.

Jan 1, 1998

By D. McConchie

BauxsolTM, prepared by treating bauxite refinery residues with Mg2+ and Ca2+, has an excellent ability to remove arsenic from acidic waters. The addition of BauxsolTM to sulphidic waste rock at the Gilt Edge Mine, South Dakota, reduced As concentrations in leachate water from 35 mg/L to < 0.005 mg/L; the concentrations have remained below 0.005 mg/L for the five years since the treatment was initiated. However, ordinary BauxsolTM does not effectively remove As from near-neutral water and it needs to be acid-treated or blended with small amounts of reagents, such as jarosite or ferrous sulphate, to increase the proportion of positively charged binding sites on the particles. The use of a jarosite/BauxsolTM blend can effectively treat ponded water, and As(V) concentrations can easily be reduced from over 1 mg/L to < 0.001 mg/L; As(III) has to be oxidised to As(V) for effective removal. Metal contaminants in the jarosite are trapped by the BauxsolTM and only very small amounts of the As, or other elements bound during treatment, are liberated using a TCLP leaching test. The exhausted treatment reagents meet the criteria for classification as an inert solid and do not need to be disposed of in a secure repository.

Jan 1, 2006

Thirty mixed cultures of microorganisms from soil, water and mineral samples from the Groote Eylandt Mining Company mine site were approximately three times more effective in biodegrading manganese dioxide (34&#177; 18 mg Mn++/1/day) than sixteen purified strains (11 &#177; 10 mg Mn++/1/day) isolated from the primary enrichment cultures. Two pure bacterial genera identified as a Pseudomonad and a Bacillus, with an excess MnOz and nutrient, were able to dissolve 106 mg Mn++/litre/day in mixed culture compared with 29 mg Mn++/litre/day when grown separately.

Jan 1, 1983

By Camilo A. Alvarez, Stephen K. Harris, Brian R. Zuckerman, Philip J. Meymand, Danielle M. Steinmetz

"The sleek new air traffic control tower at the San Francisco International Airport stands at 221 feet tall and is set to replace the existing air traffic control tower by 2016. This aluminum-clad, torch-like structure and three-story Integrated Facilities Building at the base are situated between Terminal 1 and Terminal 2 adjacent to the tarmac. Berkel & Company Contractors, Inc. and Simpson Gumpertz & Heger Inc. worked in conjunction with structural engineers from Walter P. Moore Engineers and Consultants, geotechnical engineers from URS Corporation, architects from Fentress Architects, and general contractors from Hensel Phelps Construction Company on the performance-based design of a foundation to support this critical facility, which is located in a high seismic zone and situated on the very soft soil of the San Francisco Bay margin. With the loading demands and performance criteria established and Young Bay Mud thicknesses ranging from 44 to 47 feet thick across the site, the design team employed a total of 214 24-inch diameter Auger Pressure Grouted piles, which were drilled into the underlying Franciscan Formation as deep as 148 feet below existing grade. Pile reinforcement included full-length confined cages.The piles were designed to resist Maximum Considered Earthquake axial demands as high as 1,400 kips in compression and 700 kips in tension. The performance-based pile design included verification of shear capacity under double-plastic-hinge flexural mechanisms, verification of pile ductility via non-linear moment-curvature analyses, and consideration of curvatures due to kinematic as well as inertial loading.The team implemented an extensive pile load test program including a full-scale static compressive load test on a sacrificial test pile and five non-destructive high-strain dynamic load tests, four of which were performed on indicator piles that were later used as part of the foundation system. These piles were monitored with extensive embedded instrumentation throughout their length, including strain gauges and accelerometers."

Jan 1, 2017

By Chris Carr

This paper describes the process employed and the work undertaken to enable the surrender of the mine permit relating to the two tailings deposits at the abandoned Red Mountain Mine site near Rossland, BC. The first phase of the work undertaken was to provide urgent remedial work for protection of the environment, primarily through rehabilitation or replacement of surface water drainage systems. The second phase was to up-grade the water management systems to the appropriate level given their consequences of failure. The final phase of work is to ensure long term geotechnical stability of the facilities to the same level of risk. Establishment of a sustaining fund will facilitate long term monitoring and maintenance of the facilities.

May 1, 2002

By A Innis, A Bye, B McCarthy, S Glover

Technology adoption in the mining industry has been steadily increasing over the past decade, driven by the need to improve operational efficiency, safety, sustainability, and profitability. As mining companies wish to implement solutions to improve mining safety and productivity, various technologies are being integrated into mining operations to enhance processes, reduce risks, and optimise resource utilisation. Adoption of new technologies such as autonomous trucks requires a strong focus on foundational operational technology (OT) and a systems-thinking approach. OT support is critical however, OT is traditionally not considered or integrated into standard maintenance activities. Consequently, sourcing and applying service support to OT systems in real-time has posed significant challenges to date. Neglecting the monitoring and upkeep of these operational technologies and equipment can lead to a host of adverse consequences. Operating instability becomes more prevalent, necessitating reactive measures, and the vulnerability to cybersecurity threats increases significantly. To address OT monitoring and maintenance challenges, a systems wide mindset and remote support discipline must be utilised. Remote operations support refers to real-time, 24/7 monitoring, control and support of site OT: network, production systems, maintenance systems, enterprise systems and mobile and fixed plant through a single interface remote from site. The presence of a disciplined team, grounded in a systems-oriented approach, is of the utmost importance to remote monitoring, given the intricate interdependencies of OT systems. The ability to understand the relationships among multiple systems, coupled with the capacity to distinguish between symptoms and root causes, assumes a pivotal role in operations. Through diligent monitoring and the astute understanding of system thresholds, remote operations support can actively identify and alleviate constraints, in turn, serving as the enabler for transformative advancements in technology output.

Sep 1, 2024

By Chandrasegaran, Tamilmani

"This paper describes a case study of a retaining wall structure using a diaphragm wall to construct a stilling basin at Tanjung Bin T4 power plant in Johor Bahru, Malaysia. The stilling basin is part of the Phase IV (T4) 1x1000MW power plant’s offshore cooling water discharge culverts. The site is located close to the sea with 5m of fill on top of very soft sediments of marine origin up to 20m thick underlain by fluvial clay and metasedimentary rock. Stringent wall deflection criteria and construction program dictated adopting an efficient solution with 800mm thick diaphragm wall supported by permanent top support as the temporary prop and improved horizontal restraint provided by deep mix piles acting as a slab (ground improvement layer) below the final excavation level. The depth of excavation is about 10.12m from the existing ground level. The proposed solution kept the wall deflection below the limit of 0.7% of the depth of bulk excavation and avoided additional props leading to faster completion of the structure. With unsymmetrical loading behind the retaining walls, 2D finite element analysis was carried out to assess the wall deflection and stresses in the wall and the grout layer below. The diaphragm wall is instrumented to monitor the behavior and the findings are discussed in the paper.INTRODUCTIONConstruction in soft marine clay has always been a challenge to the engineer because of its very low shear strength and its sensitivity to disturbance. In the case of excavation projects the problem becomes even more complicated with development of excess pore pressure during excavation. Marine clay with its low shear strength and lesser passive resistance, generally leads to large wall movements and settlement behind the wall. Increased passive resistance coming from increased number of props is useful but has its limits and it is no longer the most effective way in containing or reducing the wall movements or forces in the wall. One of the solutions to these problems is to improve the soil shear strength by means of ground improvement infront of the wall at an elevation most appropriate to maximize wall performance. There are several methods adopted in improving a soil layer including mixing additives to the ground to improve the shear strength to partially replacing the weak soil while others are fully replacing the weak soil. This paper discusses the case study of approximately 10m of excavation in soft marine clay using 800mm thick diaphragm wall supported by Deep Mix Piles (DMP) being used to improve soft marine deposit to form a slab just below the formation level and thus improving passive resistance significantly. The ground improvement layer helped to reduce the wall forces and deflections making it possible to remove the need for additional temporary props leading to significant savings is time and productivity. The paper presents the various options explored before this method is adopted, the design approach, instrumentation data and the monitored results."

Jan 1, 2015

By R. Washnock, P. James

"INTRODUCTION Abstract Tankhouse iron control through application of new treatment technology to mitigate conventional bleeding losses is considered. Implementation is discussed and the treatment economics explored. A representative case is assessed. Treatment benefits and application drivers for specific scenarios are noted. Background Hydrometallurgical ore processing has become a significant metal extraction/production avenue in recent decades. In copper mining; the focus for this examination, around 25% of global primary copper production and nearly 50% of US production result from various hydrothermal leaching extraction approaches coupled to Solvent Extraction/Electrowinning (SX/EW) metal production. Generally such processing is favored over pyrometallurgical processes for lower ore grades and as such is finding growing use and is expected to remain a key processing route looking forward with average world-wide ore grades falling as known ore reserves become exhausted. Target Problem And Motivation In hydrometallurgical processing the production circuit may be thought of as a chain of interlocked recirculation loops (Figure 1). Leaching dissolves the target metal from the ore along with other ore components which contaminate the Pregnant Leach Solution (PLS). Iron is a common component in copper ores and, as a result, occurs fairly ubiquitously in copper Pregnant Leach Solutions (PLS) generated by leaching. Leached components migrate through the production circuit from left to right (Figure 1) through a net combination of chemical and mechanical transport mechanisms. Selectivity at the recirculation loop interfaces tends to retard rejected component migration through the production process. As a result, overall relative contaminant migration fluxes are slower than the target metal (copper) and the contaminants tend to build up relative to copper in the more upstream portions of the processing circuit over time with iron often being a significant contaminant. Further, while copper is continuously removed from the system in appreciable amounts, little contaminant exit occurs and the absolute contaminant amounts and concentrations also increase throughout the EW circuit over time."

Jan 1, 2018

By L Alem

In the field of mineral extraction, complex technologies are being introduced in mines, operators/technicians rely on assistance from an expert (or more) in order to keep their machines functioning. Personnel with such expertise, however, are not always physically on-site. There is a growing need for innovative technological solutions to support effective delivery, just in time, of remote guidance between an offsite expert and an on-site maintenance operator. To meet this need, we have, as part of our Human System Integration project within the CSIRO’s Minerals Down Under (MDU), Transforming the Future Mine theme, explored the usefulness of a number of emerging technologies including: augmented reality, wearable systems and touch table interfaces. This paper presents ReMoTe, an augmented realty system for remote guiding using a touch table interface for the expert station and a combination of augmented reality and a wearable system at the operator end. In designing this system we were interested in exploring the extent to which it can increase the productivity and safety of maintenance personnel. This paper also presents Mobile ReMote, our recent development of a fully mobile remote guiding system. In Mobile ReMote, both the expert and the operator are using a near eye display and wearing a light computer in a back pack. The expert is able to guide the operator using his/her hands on the virtual display, while the operator is able to see the instructions on the rear eye display. Workers in the mining industry are highly mobile, a mobile expert and operator station will meet this need.

Nov 22, 2011