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By M. Mathiba

High CO2 fluxes associated with reclaimed coal mine spoils pose an environmental hazard where such sites are used for building. CO2 concentrations in excess of 25% have been reported in homes constructed on or down gradient of such spoils. The objective of this study was to investigate the effect of a mitigation trench used at one mine site on CO2 fluxes across the trench using chamber?based trace gas measurement. LI8100 automated CO2 flux system was used to measure CO2 fluxes from 32 sample points located across a deep mitigation trench on June 8 and 9. The maximum recorded fluxes were 7.29 and 8.18 µmol/m2/s, with averages of 4.15 and 5.50 µmol/m2/s, up and down-dip respectively. These preliminary results show CO2 flux is higher up-hill than down-hill at 95% significant level. This work shows that flux measurement can be used to investigate CO2 migration on reclaimed mine land. Further work is necessary to allow geostatistical modeling of the spatial variability of CO2 fluxes over reclaimed coal mine spoils. Knowledge gained would assist mining practitioners and regulators in reclamation planning for envisaged post-mining land uses.

Jan 1, 2010

By D. A. Huggins

Column flotation is finding increasing use in the flotation of copper, molybdenum and other heavy metals and coal. Columns have proven operational, cost and metallurgical advantages which caused us to investigate their use in the proposed Escondida flowsheet. A comparative pilot plant test with 35 tons of ore showed that one column can replace three stages of cleaning and result in a significantly higher concentrate grade with no loss in recovery.

Jan 1, 1987

By R. J. Wesely, Corby G. Anderson, L. Ernest Krys, John B. Ackerman, A. D. Zunkel, Suzzann M. Nordwick

Processing of the refractory precious metal ore from the Sunshine Mine is done in a fully integrated hydrometallurgical facility. This operating philosophy began with the construction of an antimony plant during World War 11, and it continued with the construction of a silver-copper refinery in 1984. The antimony plant relies on an alkaline sulfide ambient pressure leach combined with antimony electrowinning and antimony compound production. This plant is the largest producer of antimony metal in the United States. The one-of-a-kind silver- copper refinery uses a nitrogen species catalyzed sulfuric acid pressure leach system. The plant contains innovative downstream silver recovery processes as well as copper solvent extraction and electrowinning. This paper presents the pertinent process chemistries and flow sheets for the two unique hydrometallurgical processing plants.

Jan 1, 1993

By A. C. Alexander

Chevron Resources Company owns and operates an open pit phosphate mine and mill 11 miles north of Vernal, Utah. The plant currently produces 500,000 tons per year of concentrate and has the capacity to produce 750,000 tons per year. The operation is currently being expanded to 1,300,000 tons per year of concen¬trate in order to supply a new fertilizer plant being constructed by Chevron Chemical Company in Rock Springs, Wyoming. A 10-inch, 96-mile pipeline is being built to transport the concentrate from Vernal to Rock Springs. The present and expanded operation will be discussed. HISTORY In 1915, Harry Ratliffe staked nearly 15,000 acres of low to medium grade phosphate rock along the southern flank of the Uintah Mountains. This deposit became the largest privately owned phosphate deposit containing approximately 700 million tons of reserves. Initial development of the deposit began in 1958 by San Francisco Chemical, a joint venture between Stauffer Chemical Company and Mountain Copper Limited. In 1968, Stauffer Chemical Company bought out Mountain Copper Limited and became sole owner and operator. In 1981, Chevron Resources Company bought the property from Stauffer and has operated the mining and milling operations since.

Jan 1, 1985

By Eugie Kabwe

The velocity of detonation (VOD) is a significant property considered when rating an explosive. It may be quantified as a confined or unconfined velocity. The confined velocity is the rate at which the detonation wave propagates through an explosive within a blast hole or any restrained space. The unconfined velocity emanates when an explosive is detonated in the open. However, the confined velocity is more significant as explosives are usually employed under a definite degree of confinement. This paper evaluates the increment of air deck volume and its effect on the VOD. The air gap (air deck) volume is increased stepwise from 10 to 30% of the total blast hole volume by reducing the stemming height in the collar zone. Thereafter, the VOD estimation in the 172-mm-diameter explosive column is conducted using the Dáutriche technique. It is observed that the VOD reduced with the increasing air deck volume and detonation failure is high when 30% of the blast hole volume is replaced with air deck. It is deduced that the increment of the air deck volume has an effect on the attenuation of the steady-state VOD.

By Boghani. A. B.

A computer program has been developed to simulate evacuation of a mine in various configurations. The simulation input variables include characteristics of the mine, expressed, in the form of a network of passages, properties of hoists and hoisting strategies, initial miner positions, ventilation and compressed air velocities, stench warning system and self rescuer capabilities. The simulation can be carried out for cases in which there is no fire, i. e. , fire drill simulation, or for cases in which there is a fire at any arbitrary location. The fire is assumed to generate gases which impede movement of miners in the gaseous region. However, the thermal effects of the fire are not considered. The simulation output include the evacuation time for each miner, movement of the hoists, propagation of smoke through the mine passages and smoke exposure of the miners. Several illustrative simulations have been carried out to verify validity of the program and to demonstrate its capabilities. The computer program has been able to predict evacuation time, within 5 percent, for an actual fire drill. It is believed that this program can be used to evaluate evacuation performance of a mine, identify problem areas and demonstrate improvements due to the recommended corrective actions.

Jan 1, 1977

By E. Karampinos, P. Morissette

"INTRODUCTION Ground support is a critical element in maintaining the stability of mining drives in deep and high stress mines. In challenging ground conditions, it is necessary to continuously explore ground support strategies that can control the resulting large deformations. It is an objective of mining operations to optimize the ground support by selecting both appropriate systems and the time of installation of each reinforcement element. A successful ground support strategy will result in the use of a system that ensures both the structural and operational integrity of the excavations and mitigates the need for rehabilitation. Preliminary ground support design is often based on empirical observations and methods. Once a design is implemented, field trials, observations and in situ pull tests are used to fine tune or improve the design. Although not often employed during this process, numerical modelling can provide helpful insights on the impact of different ground support strategies. In this respect, it is possible to explore the use of multiple options before selecting the most promising ground support system for implementation in field trials. The challenges associated with the numerical modelling of rock support for mines have been described by Lorig and Varona (2013) and Potvin (2017). The employed numerical models should capture all potential failure modes of reinforcement over the mining sequence of the excavation. In particular, it is important to emulate the observed in situ ground support performance, as well as the influence of the installation sequence of the support. However, the time and expertise required for this type of modelling of ground support is not often available at mine sites. Even when the expertise is available it requires a major time and commitment of resources to set up, run and calibrate the sophisticated models capable of explicitly capturing the behavior of ground support. Rock reinforcement is an integral part of all ground support systems used in underground mines. Long flexible tendons can reinforce the rock mass deeper into the walls and create a thicker reinforced shell around the underground excavation. This paper focuses on the optimization of the cable bolting strategy in squeezing conditions at the LaRonde Mine by integrating the 3D distinct element method (DEM) in the design process. A calibrated numerical model is used to investigate a series of cable bolt configurations and provide recommendations for the ground support design."

Jan 1, 2018

By Penglu Gan, Jinjie Zou, Chenglang Pan, Xiaowu Tang, Yu Zhao

"The north segment of the Zizhi Tunnel that consists of twin tunnels was excavated at a shallow depth in soft ground using the Shallow Tunneling Method. Based on continuous field measurements, the development histories of surface settlement were analyzed first. The observed development process could be roughly divided into three stages and the influence of river was evidenced. Transverse and longitudinal surface settlements above the twin tunnels were then fitted with empirical models. The obtained trough width parameters in transverse and longitudinal direction (it and il) and the volume loss (VLs) were presented and discussed. Additionally, surface settlement was compared with the crown settlement. The relationship between surface and crown settlement behaved in two different ways inside and outside the river-affected region. The findings in this project give references for predicting surface settlements in similar tunneling condition. INTRODUCTION Nowadays tunnel construction has become a major way of utilizing underground space in many large cities. The ground deformation will be inevitably induced in the tunneling process. Engineers should always be careful about excessive deformation that may damage adjacent structures. For shallow tunnels, controlling ground deformation turns to be more risky. Since soil arching is not completely formed in the shallow tunneling, settlements can easily develop from tunnel crown to ground surface.A conventional tunneling method named Shallow Tunneling Method (STM) has been developed and widely applied to constructed shallow tunnels in China. The major difference between this method and the New Austrian Tunneling Method (NATM) is whether considering self-supporting capacity of surrounding ground or not. In order to reduce the disturbance of surrounding soils, several guidelines are highlighted in this method, including advanced pipe forepoles, strict grouting, short excavation length, strong support, quick closure and frequent measurements (Fang 2012). Nevertheless, the ground deformation is still hard to control and becomes a concerned problem, mainly because ground settlement has some regional features and largely depends on the detailed excavation methods (bench cut method, multiple heading method, etc.) and ground condition (sand, clay, decomposed rock, etc.)."

Jan 1, 2016

By Don Opacic

The disposal of sludges and other similar industrial wastes is a major problem. Liquid wastes from industrial operations, when treated, produce significant volumes of sludge which are difficult to dispose of, because of the chemical and physical properties of the sludge. In the mining industry sludge is produced from various water treatment operations, in particular mine drainage neutralization. Waste water from coal preparation plants also produces a sludge however the sludge is in fact a slurry containing clays, coal fines and coal impurities. In many areas the disposal of these sludges is producing a serious problem. Mine drainage sludge consists of a variety of hydrous iron oxides, usually ferric oxides, contaminated with other neutralization products such as calcium sulfate. The volume of sludge from mine water or mine

Jan 1, 1973

By Robert E. Murray

It's indeed a pleasure for me to speak to you today about the development and operation of large-scale surface coal mining projects in the western United States. It is an exciting story about American business working to solve a critical national problem -- the energy shortage -- through research, new technologies, financial innovation, and imaginative management. The North American Coal Corporation -- the second largest independent mining company and ninth largest United States coal producer -- is proud to be a part of this story. Our operations in North Dakota reflect the coal industry's Western activities. So, today, I would like to focus on our planned involvement in that state. I'll briefly survey why North American is developing large- scale surface mining in North Dakota, and I will outline the many problems associated with this coal development and how we are working to solve them. Finally, I will look at the financial and management techniques we are using to make it all work. In short, I'm going to present a case study of Western coal mining. Let's begin by looking at the reasons we are in North Dakota. The United States Bureau of Mines estimates that 44 per cent of the nation's total recoverable coal deposits underlie the three Northern Great Plains States of North Dakota, Montana, and Wyoming. We estimate that North Dakota alone has about 25 billion economically surface-mineable tons of coal with today's technology. North Dakota has the energy that could keep our factories running and our homes lighted In the years ahead.

Jan 1, 1975

By R. E. J. Putman

The past ten years have witnessed substantial development of electronic equipment for execution of process control functions. The methodology of giving instructions to the data-handling system and the organization of the system, both the equipment and instruction coding taken together, have developed simultaneously. Examples of the technology specific to the mineral processing industry can be cited. Approaches to system design developed for the Pinto Valley concentrator incorporating slave and master data processing have been described by Arney, and his associates (1974). Madge (1970) has described the hierarchical systems employed at the operations of Cominco Ltd. The Kennecott Garfield smelter is controlled by a system of microprocessors linked to a general purpose data processor (Marchant, et al., 1977). These systems provide innovative approaches to couple advancing technical capability in electronic data processing to the objectives of process management. The current state of the art described in this chapter is certain to require updating in the 1980's with the advances in technology anticipated.

Jan 1, 1979

By S. K. Singh

"Feather edging"-a major source of injury and fatal accidents in Australia, South Africa and USA, refers to a phenomenon where the roof, at the goaf edge, falls as a thin wafer of rock often suddenly, over-riding conventional timber breakerlines. It may run down and affect adversely a working bord at distances of 15 metres or more from the goaf edge. Feather edging typically occurs in relatively massive, strong roof strata such as sandstone or conglomerate. This paper presents the results of a mine trial where a concentrated row of fully grouted bolts were able to resist the feather edging in the first comprehensive, monitored trial in an Australian pillar ('total') extraction coal mine.

Jan 1, 1999

By Howard G. Coopersmith

Kelsey Lake kimberlites are a cluster of eight diamondiferous pipes that occur in the northern State Line kimber lite district of the Colorado-Wyo¬ming diamond province (Coopersmith 1991, 1993) (Fig. 1). This is located at the southern margin of the Wyoming Archean province. Two relatively large pipes and a few smaller bodies define the cluster (Fig. 2). The Kelsey Lake kimberlite cluster has been developed as the first diamond mine in the United States. The cluster was discovered in 1987. Full-scale production began in the spring of 1996. Mining has produced gem-quality diamonds up to 28.3 carats in size. The 30 State Line kimberlites, intruded about 390 million years ago into Proterozoic crystalline rocks, were presumed to be underlain by Archean basement of the Wyoming Province. Nearly all the kimberlite pipes contain diamond but only the Kelsey Lake pipes are economic. The Kelsey Lake kimberlites contain predominately diatreme facies kimberlite, with minor hypabyssal and crater facies rocks locally occurring. Alteration and weathering of the kimberlites is extensive. Petrologic studies indicated an underlying lithosphere that has a largely Proterozoic signature and shows evidence of deep melt and metasomatic events. Current development has concentrated on the two largest pipes. These have been bulk-sampled after geological study (1987) identified the presence of small diamonds and mineral chemistry indicating favorable diamond conditions. A 10-t/hr (11-stph) rotary pan plant was established in 1992 to process thousands of tons of bulk-sample material. Grades and gem-quality diamonds to 14.2 carats in size were recovered. Early in 1995, it was decided to move from evaluation to commercial mining. Production began in early 1996. A 195-t/hr (215-stph) rotary pan plant was built. A water supply system and tailings disposal have also been incorporated. The project straddles the Colorado/Wyoming border. Existing mining permits were amended to incorporate the increased scale and new plant facility. The permits for this project included the following: Colorado mining permit, Wyoming dozing permit, Corps of Engineers Section 404, Colorado NPDES, Wyoming NPDES, Storm water Management Plan, Air Pollution Emission Notice, various Colorado and Wyoming State Engineer and well permits, Substitute Water Sup¬ply Plan, Larimer County Special Use Review, and US Forest Service road use permits. The temporary destruction of a wetlands area was a sensitive issue. It has been addressed through the Clean Water Act Section 404 permit administered by the US Corps of Engineers. This use will be mitigated by creating new, self-sustaining wetlands in the immediate drainage system. A comprehensive and bonded reclamation plan is incorporated in the permits. Diamond mining and ore processing is environmentally benign. No chemicals are used in processing the diamonds. The plant is a water wash facility. The kimberlite ore is inert, as is the granite wall rock. The exposure of the ore body and the subsequent ore processing and waste rock and tailings containments pose no threat of release, leaching or dispersion of any detrimental elements. There is no acid-forming waste. Even a prolonged acid rain environment will not produce a harmful leachate. Slimes containment and clarification ponds will prevent unacceptable levels of suspended solids in water discharge. The isolated, restricted access and nonvisible nature of the mine and processing has led to straightforward permitting. Geology The State Line district is located in the northern

Jan 1, 1997

By Frank F. Aplan

Froth flotation has been used to improve the recovery of fine coal, for minimizing the sulfur and ash content of clean coal and for the removal of fine coal from recycled or discharged backwater from coal preparation plants. Though froth flotation and allied processes for ores date from the turn of the century, with the first U.S. commercial application in 1911, coal flotation has been introduced into U.S. practice much more slowly. The first European coal flotation plant was started in 1920, and by 1933 Europe had 60 operating plants while the United States had only one plant, newly commissioned. Over the years there has been a steady increase in coal flotation so that today one-third of the 345 U.S. plants employ the process. This report traces U.S. coal flotation practice and technological improvements from early laboratory experiments in 1915 up to today's extensive use of the process.

Jan 1, 1999

By T. Ritzel

Predictive maintenance technologies including vibration analysis, tribology, infrared thermography, ultrasonic detection, and electrical measurements have been applied to large electric mining shovels at Cyprus Sierrita. The predictive program was initiated by Cyprus Sierrita and P&H Mining Equipment at the Cyprus Sierrita Mine in Tucson, Arizona during August of 1996 on the P&H model 2300 and 4100 electric shovels. The utilization of these technologies has shown the potential for improving electric mining shovel availability and minimizing maintenance costs. Predictive technologies provide the tools to assess machinery condition. Availability is enhanced by the condition based planning of component replacement. Maintenance costs are minimized by focusing resources through condition based prioritization.

Jan 1, 1997

By Kyle L. Brennan, Scott Maybrier, Gang Chen, Scott Huang

Data from about 3200 drill holes in the offshore area at Nome, Alaska was digitized and processed. Most drill hole files have associated lithology, gold value, and blow count descriptions for each drill hole. The gold intensity was used to present the potential gold resource in the study area on the world wide web. A web page was created that gives background information on the project, descriptions about the Nome area, maps of the claim blocks that include all the normalized slices of gold deposits, and links to other relevant sites on the web. The site is located at http://mineral.uafsme.alaska.edu/nomeproject/nomehome.htm.

Jan 1, 2002

By R. Q. Honaker, D. Tao, D. Taulbee, B. K. Parekh

A significant amount of energy exists in the waste generated by the coal and timber industries. In the coal industry, the energy loss is mainly due to the discharge of fine coal to the waste impoundment. Despite the fact that the fine coal has the greatest cleaning potential, dewatering, handling and transportation concerns prevent its use as product in many cases. Likewise, the sawdust generated from wood production has energy value and is used as industrial boiler fuel when the transportation distance is relative short. However, wood waste is often discarded into cumbersome landfills due to uneconomical transportation alternatives. Recent research found that these two waste materials can be combined to provide a high energy fuel of around 13000 btu/lb that can be easily handled and transported to end users.

Jan 1, 2004

By R. G. Graber

Field testing of GPS mining applications has confirmed the technical and operational viability of GPS for precise, centimeter-level positioning in harsh taconite environments. GPS hardware has provided consistent availability exceeding 90%, with precision in certain applications of ± 0.07 foot at 95% confidence levels. Despite these technical successes though, challenges persist in achieving effective GPS integration. These challenges include the acceptance of new job tasks by mine personnel, the capacity of typical mine data communications infrastructure and the need to design GPS interfaces for new mining equipment.

Jan 1, 1998

By Tsuneyoshi Funazaki, Takayoshi Nakamura, Keizo Miki, Takashi Imaishi

The underground portion (about 10 km) of Tokyo Wan Aqua-Line consists of eight shield tunnels connected with Kawasaki Man-Made Island in between, at four underground locations. The connection work had to fulfill strict precision and safety requirements in the ground about 60 m below soft seabed, but was completed successfully in May 1997. This report describes the connection work in detail, featuring the method of investigating shield machines’ relative positions, ground freezing method and connection mechanism and procedures. It also mentions the present state of Tokyo Wan Aqua-Line that was put in service on December 18, 1997.

Jan 1, 1999

By W. M. Hart

The remote face loading and entry convergence monitoring systems, employed at some of the Cyprus Amax's underground coal mines, have been able to continuously record changes in face shield resistance across and entry convergence ahead of the longwall face at any moment during longwall mining. The instrumental data obtained from these systems plus in-situ observations during the mining operation can help us better understand the mechanism of overburden strata movement above a longwall face and verify the effectiveness of the current face and entry supports. This paper describes the functions of both the face and entry monitoring systems, and discusses our findings and the issues related to successful ground control for longwall mining.

Jan 1, 1996