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By Colin Connors

Cemented rockfill is a key component in the success of underground mining at the Jerritt Canyon Joint Venture. The Murray and SSX mines are characterized by relatively poor rock mass quality, and the goal of complete mining recovery makes maintaining a high quality backfill product vital to the safety and efficiency of the mining operations. A large portion of the ore production from the Murray mine originates from drifting under backfill. Modelling studies performed to investigate induced loading of the backfill were used to develop engineering specifications for the backfill material. Operations history has shown an almost 100 percent stability of the backfill when mining is carried out beneath it. The volume of backfill required each year (approximately 300,000 tons) and the required cement content have a significant impact on the total mining costs. The potential for cost savings associated with higher replacement of cement with Type "C" fly ash and the implementation of a backfill strength management strategy were therefore evaluated.

Jan 1, 2001

By R. P. King

The MODSIM mineral processing plant simulator is used to find optimal combinations of target separation specific gravities in a typical modem coal washing plant. A plant that is set up with these optimal targets can deliver up to 10% more yield at the same ash content as the same plant set up with separation targets chosen by conventional methods. MODSIM is the only simulator currently available that can simulate the liberation of pyrite and other mineral matter during open-and closed-circuit grinding operations. The simulator can therefore be used to assess the benefits of grinding operations in the flowsheet.

Jan 1, 1997

By Paul B. Queneau

Formulation and commercial utilization of solid-waste incinerator slag by-product is the focus of this paper. Particular attention is given to iron aluminosilicate melts having compositions similar to that of nature's basalt The earth?s crust can be viewed as an environmental laboratory for predicting stability of various silicates; small-scale laboratory experiments are necessary to confirm findings there from. An ideal slag consumes flux additives at acceptable cost, is compatible with furnace refractory, flows readily from the furnace, and has physical properties suitable for its commercial utilization -all within the critical constraint that the slag is environmentally stable. Examples of successful solid waste slagging practice, including tonnage, utilization and pricing, are provided from metallurgical and waste treatment operations of North America. Western Europe and Japan.

Jan 1, 1991

By C. Garcia, J. J. Opazo, A. Potulsha, T. Comi

"Sierra Gorda SCM is a joint venture partnership of KGHM International (owned by KGHM SA, Poland), Sumitomo Metal Mining and Sumitomo Corp. (Japan) operating in northern Chile. The Sierra Gorda openpit mine and coppermolybdenum processing plant will become one of the largest mines in the world. The need for optimum production efficiency and sustainability has driven the creation of the most modern, wellinstrumented mine in Chile. This article contains a general review of the project including geology and history.This was a fast-track project going from greenfield site acquisition to mill startup in 10 years. Highly experienced and motivated engineers and technical staff have overcome many significant challenges resulting in a rapid ramp-up of production capacity. A potential expansion to double the production rate in the fourth year of operation has also been intensely studied.The Sierra Gorda property is located in the Atacama Desert of northern Chile, in the District of Sierra Gorda, Region II of Antofagasta, Chile (Fig. 1). There is almost no precipitation in this area. The mine site is generally flat with some rolling hills. The project is located about 5 km (3 miles) from the village of Sierra Gorda at an elevation of approximately 1,700 m (5,600 ft) above mean sea level. The village is near a highway and railway line. The city of Calama, home of the famous Chuquicamata Mine, is located about 60 km (37 miles) northeast of Sierra Gorda. In addition, the SG mine is in the midst of numerous other mines including Spence, Esperanza, Mantos Blancos, El Tesoro, Lomas Bayas, Gabriela Mistral, El Abra, Radomiro Tomic and Escondida, to name a few.The primary organizational value at Sierra Gorda is "Zero Harm." This includes employees, contractors, the environment, the community, plant facilities and mine equipment. A cornerstone of this program is called 5X5S (five by five S), which combines the lean principles of 5S with the safety model of taking five steps back and thinking about the task at hand for five seconds, five minutes, the time it takes to assess and manage the risk. "People caring about people" promotes proactive engagement in the safety of coworkers and others at work and at home."

Jan 1, 2014

Powder River Basin (PRB) mines were originally built to serve power plants designed specifically for their coal. Sulfur was the major concern, with BTU and sodium limiting the market for some. The Clean Air Act has extended the PRB market into plants converting from other coals. These new customers are more sensitive to constituents affecting boiler and precipitator performance. At the same time, the prospect of deregulation is forcing power companies to control cost more stringently than ever. Jacobs Ranch Mine has responded to the changing marketplace with an expanded coal quality and customer service program.

Jan 1, 1998

By S. A. McGhee

Introduction ASARCO's Ray Operations include an open-pit copper mine in the Mineral Creek Mining District of Pinel County. The district is located in east central Arizona, 132 km (82 miles) southeast of Phoenix, AZ, and 126 km (78 miles) north of Tucson, AZ. The mine lies 8 km (5 miles) north of the Gila River in Mineral Creek Valley, between the Tortilla Mountains to the west and the Dripping Springs Range to the east. The rich copper deposits of the Mineral Creek mining district were first noted by a US Army Officer in 1847. The Ray Copper Company was the first major operation in the area. The company was named after the Ray mining claim, which was one of the earliest recorded claims. After decades of sporadic and unsuccessful mining ventures, the Ray Consolidated Mining Company was formed in 1910. The company introduced one of the first successful block caving operations in the world. In 1933, the Kennecott Copper Corporation acquired the Ray Consolidated Mining Company and continued operation of the mine under the same name until 1943, when the property was renamed the Ray Mines Division of Kennecott. Underground mining continued until 1955, when the mine was converted to an open pit operation. In November 1986, ASARCO Inc. purchased the Ray Mines Division and related facilities from Kennecott. The purchase also included the Hayden concentrator and the Ray Smelter, located approximately 32 km (20 miles) from the Ray Mine. This paper summarizes the 54,400 tpd (60,000 stpd) in-pit crusher and overland-conveying system and the 24,200 tpd (30.000 stpd) copper SAG concentrator and tailings disposal system constructed at ASARCO's Ray Complex - Ray Operations. General description of facilities The Ray concentrator includes a sulfide SAG concentrator, a "relocatable" in-pit primary-crushing plant and overland-conveyor system, a concentrator tailings-disposal system and plant ancillary facilities, The major elements of the project include: • A relocatable Fuller-Traylor in-pit 1524-mm (60-in) x 2261-mm (89-in) primary gyratory crusher at the 442 m (1450 ft) mine elevation. The crushing plant has a nominal capacity of 54,400 tpd (60,000 stpd) of sulfide ore. • A 1524-mm (60-in) wide x 1253-m (4110-ft) long overland belt conveyor, which runs from the in-pit crushing facility to a transfer station serving both the Ray Concentrator and the existing Hayden concentrator railroad load-out facility. • A 1524-mm (60-in) wide x 152-m (500-ft) long stackerbelt conveyor, which delivers a nominal 27,200 tpd (30,000 stpd) of ore from the transfer station to a 23,600 t (26,000 st) live-capacity coarse-ore stockpile serving the Ray Concentrator. • A nominal 27,200-tpd (30,000-stpd) concentrator, including semiautogenous grinding, flotation, copper concentrate filtration and associated plant ancillary facilities. • A tailings disposal system. Flotation tailings are pumped from the Ray Concentrator to a 122-m (400-ft) diam. thickener, located 4.8 km (3 miles) southeast of the Ray Concentrator site. The thickener overflow is pumped to two 76.2-m (250-ft.) diam. concrete process-water reservoirs. The thickener underflow, at 45% solids, is pumped to a new tailings disposal site located at Elder Gulch. • An HDPE-lined temporary-containment area to collect material from Ray Concentrator plant upsets and local storm-water run-off from a 100-year, 24-hour rain event. •A reclaim-water system from the Elder Gulch tailing pond area to the Ray Concentrator. • A 610-mm (24-in.) diam. x 31.9-km (19.2 mile) long fresh-water pipeline from the Hayden fresh-water-well field system to the Ray Concentrator. The overall process design criteria for the new Ray Concentrator is based on a nominal throughput of 27,200 tpd (30,000 stpd) of ore at 90% plant availability. However, based on the maximum performance capacity of the installed grinding equipment, it may be possible to achieve a sustained operating level in excess of 36,300 tpd (40,000 stpd) when processing soft ores. The balance of this paper will cover the major process systems including:

Jan 1, 1995

By T. Owen

Not since 1917 has a foreign company developed a standalone, grass roots gold mine in Russia. With. Russia's political changes of the late 1980s, development of mineral prospects once again beckons foreign investors. In 1990, Cyprus Amax began aggressively searching for such an opportunity. Early in 1997, production will commence at the Kubaka gold project located in the Russian Far East, near the Arctic Circle. The Kubaka project is a 1,750-tonne per day open-pit operation that will produce more than 300,000 ounces of gold per year. This paper discusses the challenges of locating such a prospect, doing business in Russia, developing supply lines, identifying work force capabilities, gaining government approvals, securing financing, arranging for gold sales and ultimately building a facility in this arctic region.

Jan 1, 1997

By Naomi H. Harley, Daryl E. Bohning, Isabel M. Fisenne

INTRODUCTION Underground mines in many parts of the world have elevated levels of short-lived 222Rn daughters. Lung cancer implicating exposure to short-lived daughters is documented in the U.S., Czechoslovakia, Canada, Sweden, the U.K., France and Newfoundland. An elevated lung cancer mortality (in excess of that expected) has been observed when cumulative exposure to alpha emitting short-lived 222Rn daughters (218Po, 214pb 214Bi 214Po) is greater than about 60 working level months (WLM) [1]/ (Hewett, D. 1979). This is equal to an absorbed alpha dose of about 30 rads to shallow basal cells in bronchial epithelium. Long-lived alpha emitters are also present in underground mines, and especially uranium mines because of airborne particulates containing uranium. The 238U parent of this primordial series supports other long-lived emitters 234U 230Th, 226Ra, Pb(210Po) which are in some degree of radioactive equilibrium with the parent 238U. Airborne particulates can be present due to drilling on the face of the ore body as well as in all parts of the mine through resuspension from the mine floor. Particles from 1 µm to about 5 µm penetrate the nose with reasonable efficiency and deposit primarily in the tracheobronchial tree. They are removed by ciliary motion (the bronchial escalator) but deliver an alpha dose to basal cells in bronchial epithelium during clearance in the same manner as short-lived 222Rn daughters. It is the purpose of this work to indicate the alpha dose to basal cells in bronchial epithelium delivered by the long-lived emitters 234, 238U. The dose calculations reported here based upon a few measured values of these isotopes in air in uranium mines in New Mexico and Colorado. MEASURED 234, 238U IN URANIUM MINE ATMOSPHERES In 1979, the U.S. Bureau of Mines undertook a study to evaluate personal monitors to be worn by miners to measure short-lived 222Rn daughters. One of these devices sampled air at 100 cm3/min through a 13 mm glass fiber filter, with a small pump worn on the belt. Alpha particles emitted by 222Rn daughters on the filter were measured continuously by a thermoluminescent dosimeter (TLD) chip. Each monitor was worn by a miner for a 170 hour working month and approximately one cubic meter of air was sampled during this period. Six different mines were selected for the test in New Mexico and Colorado. The mines used either wet or dry drilling methods. Miners in each location were equipped with the personal monitors. Subsequent to their use in evaluating the shortlived daughters, Dr. Robert Droullard of the Bureau generously gave us these filter samples along with a few blank glass fiber filters from the same box of filters used in the study so that long-lived emitters present in these mine atmospheres could be determined radiochemically. Four of the samples have been run for 234, 238U. The radiochemical procedure for uranium is adapted from USDOE, Environmental Measurements Laboratory Manual (Harley, J.H., 1976). Briefly, the samples were placed in platinum crucibles, spiked with 232U tracer and pretreated with nitric and hydrofluoric acid. The residue was fused with potassium fluoride to transpose to pyrosulfate. The fused cake was dissolved in 7 [N] hydrochloric acid and the solution passed through an anion exchange column to isolate uranium. Iron was removed using mercury cathode electrolysis. Uranium was electrodeposited onto platinum dies and counted using solid-state alpha spectrometry. The samples from each type of mine (wet and dry) were analyzed. The samples in the "wet" mine in New Mexico were selected on the basis of the original TLD measurement because they were near the maximum occupational standard for radon daughters. These samples should also represent upper limits to longlived activity encountered, since they were obtained at drilling operations on the face of the ore body. Samples collected in the "dry" mine in Colorado were pot associated with a particular location in the mine and should be representative of a month long overall exposure in many locations and operations. The values are shown in Table 1. The two uranium isotopes are in equilibrium and their alpha activity

Jan 1, 1981

By L. J. Hoover

The objective of this study was to assess the health and environmental impacts of fluidized-bed combustion (FBC) of coal, specifically as applied to baseload generation of electrical energy by utilities. The study* was a short-term effort that based its analyses on information derived from the experience of the group or quickly obtained from the literature. The approach was to compare Atmospheric Fluidized-Bed Combustion (AFBC) and Pressurized Fluidized-Bed Combustion (PFBC) with two current technologies: low-sulfur coal combustion (LSC) and flue gas desulfurization (FGD) used with high-sulfur coals. A wet-limestone process was selected as the FGD technology. The impacts compared involved not only health and environment but also sociology, resource use, and dollar cost. Conditions for comparison were centered around a nominal date of 1988, when initial operation of commercial AFBC plants may occur. The PFBC has a later introductory date, a nominal 1995 (its impacts relative to other competitive technologies now in the R&D stages were not compared.)

Jan 1, 1978

By T. BoBo

"In the 1990’s metal prices were trending in a long term decline and the usual cost cutting exercises were adopted. Cuts to research and development made innovation difficult and the outlook was grim. But necessity is a strong motivator, and these conditions spurred the Mine-to-Mill movement which optimised across organisational “silos” and utilising new technology tools, innovative software and increased computing power. Many applications of Mine-to-Mill exploited the fact that comminution is usually the site processing bottleneck, and that blasting is more efficient at breaking rock than grinding. This approach sought to: • Understand and characterise rock breakage from mining to the mill • Develop models and simulators for blast design, fragmentation, crusher and mill circuits • Develop tools to measure in real time the particle size distribution of rocks on conveyors and Run of Mine (ROM) muckpiles • Ensure effective communication across the silos between geologists, blast design engineers, mining engineers and metallurgists These methods and the technology tools available in the 1990s were widely adopted at numerous sites around the world with significant benefits. SAG mill throughput increases of 10-20% were common. This was the advance the industry desperately needed. It was low capital cost; it was obvious. It was here to stay. Except, in too many cases, it didn’t. In the minerals price boom of the 2000’s Mine-to-Mill was no longer necessary to “survive”, even though it was still good business. Some operations, including some of the early success stories, slipped back to old habits of optimising within organisation silos instead of across them. Fortunately, other operators still embraced Mine-to-Mill and developed new techniques. Mine to Mill was still successful, but it not as widely adopted as we had expected it to be.Now the boom has ended and operations are again under cost pressure. Since these are the same circumstances that created Mine-to-Mill, it seems time to achieve the wider adoption. Since the 1990s many new or advanced technology tools are available for Mine-to-Mill projects: blast-hole sensors, new explosives formulations, new blasting techniques and modelling, ore tracking devices, improved image analysis to determine size, texture and colour of coarse ore, grade sensors, whole-stream simulation tools, even more powerful computing hardware and data analysis software. If we could achieve so much in the 1990’s, how much more can we achieve today when we have the same imperative, the same potential and a larger number of high technology tools?"

Jan 1, 2017

By E. H. Bentzen

The purpose of this paper is to explain the production of sand for glass manufacturing and the reasoning behind the sand specifications set by the glass industry. In order to discuss the production of glass sand, there is a need to understand what glass is and how it is made. Therefore this paper discusses glass, as well as sand beneficiation.

Jan 1, 1977

By J. L. Coburn

The Huari-Huari ore body is located in Southern Bolivia, at an elevation of approximately 3,800 meters above sea level. The ore is a complex massive sulfide, slightly marmatitic sphalerite, in a fault fissure filled hypo- thermal vein in Paleozoic shales and quartzite-altered sandstone. The sphalerite has common associations with pyrite and quartz and is frequently intricately intergrown with stannite, chalcopyrite, and pyrrhotite. The sphalerite also contains numerous inclusions of pyrite, marcasite, galena, boulangerite, jamesonite, quartz, arsenopyrite, and cassiterite. A research program was undertaken to develop a flowsheet for the recovery of separate silver, zinc, and tin concentrates by selective flotation. Based on this experimental work and subsequent flowsheet development, engineering and construction of a 500 metric ton per day concentrator was undertaken. This paper describes the process that was developed for the Huari-Huari ore and the unique aspects of the Huari-Huari concentrator.

Jan 1, 1977

By R. C. Gilmore

Computational fluid dynamics (CFD) has been used to model gas compositions in underground longwall coal mine gobs to study oxygen ingress and the development of potentially explosive methane-air mixtures that may form in the gob. The scenarios studied involve various headgate and tailgate ventilation and inertization schemes and controls. In a project sponsored by the National Institute for Occupational Safety and Health (NIOSH), researchers at Colorado School of Mines have used an innovative meshing approach, allowing easy adaptation of the CFD model to adjust to a variety of bleeder and bleederless mining geometries, with gob porosity and permeability scalable over a wide range. This paper presents the methodology of the meshing and scaling approach along with recommendations for using CFD modeling in longwall gob ventilation applications. The new meshing technique was utilized to evaluate the function of a back return in a progressively sealed gob. The back return was successful in maintaining sufficient oxygen concentrations in the tailgate corner of the longwall face.

Feb 23, 2014

By Jurgen H. Kleinau

This paper details Keeler/ Dorr-Oliver's experience with the application of fluid bed combustion technology to the burning of coal-mining waste. The designs of two stage fluid bed combustors/dryers are demonstrated as useful in the drying of coal, slag and coke, using coal and coal refuse (gob) as fuel. Anthracite mining refuse (culm) is more than abundant in Northeastern Pennsylvania. After demonstration at Shamokin, Pennsylvania, a full commercial-sized fluid bed boiler using culm is used for district heating in Wilkes-Barre, Pennsylvania. Limited research work has shown the utility of using fine coal as filter aid in sludge in¬cineration. With the rising avenues of the suitability of coal as auxiliary fuel in fluid bed sludge incineration, an expansion of these concepts combines the use of coal or coal refuse as filter aid and auxiliary fuel. Lime¬stone addition controls SO2 emission.

Jan 1, 1985

By R. F. Hadley

Alluvial valley floors constitute a valuable land resource and have been important to ranching operations in semiarid western United States. This resource may be in jeopardy locally if the alluvial deposits are disturbed by surface mining of coal deposits. Erosion problems caused by poor land-use practices can cause trenching of the unconsolidated alluvium with a consequent lowering of the water table and depletion of soil moisture needed to support vegetation. Historical evidence of this sequence of events is abundant in geologic literature and serves as the basis for assessing potential impacts of surface mining. The potential geomorphic impacts of surface mining on alluvial valley floors with regard to fluvial processes are: (1) disruption of the longitudinal profile followed by valley trenching and high sediment yields downstream and (2) replacement of the excavated alluvium with unconsolidated material that does not have similar physical characteristics and may be susceptible to erosion. Mining may disrupt the existing hydrologic framework affecting streamflow, ground-water levels and water quality of both surface water and ground water. Although functional hydrologic and geomorphic processes are similar, each valley represents a complex environment that does not submit to broad generalizations.

Jan 1, 1978

By L. Patts, J. Hummer

The use of diesel-powered equipment in underground coal mines has increased substantially during the last ten years in an effort to enhance mine safety and productivity. Pennsylvania and West Virginia are two of a number of states with regulations governing the use of such equipment. These states both developed and promulgated regulations before permitting diesel equipment in their underground coal mines because of concern for miners’ safety and health, especially with regard to the contamination of mine ventilation air with diesel exhaust emissions. The major components of diesel exhaust emissions are combustion gases and diesel particulate matter. The gaseous emissions consist of carbon monoxide, carbon dioxide, oxides of nitrogen, sulfur oxides and unburned hydrocarbons. The diesel particulate matter (DPM) is comprised of solid carbon particles, liquid and solid hydrocarbons, sulfates and moisture. The Federal Mine Safety and Health Administration (MSHA) also promulgated regulations in an effort to control diesel emissions in underground coal mines. MSHA has adopted threshold limit values (TLVs) for all gaseous components of diesel exhaust, which were established by the American Conference of Governmental Industrial Hygienists (ACGIH). MSHA (30 CFR Part 72 Subpart D) has established a tailpipe DPM emissions limit of 2.5 g/hr for diesel engines used in permissible equipment, heavy-duty non-permissible equipment, generators and compressors used in underground coal mines. A tailpipe DPM limit of 5.0 g/hr has been established for light-duty outby diesel-powered equipment. The rationale for the tailpipe emissions limit was that an ambient measurement of DPM in a coal mine was not feasible because there is no established sampling method able to distinguish between coal mine dust and DPM. The stringent tailpipe emissions limit mandates the use of exhaust aftertreatment devices for most diesel engines used in underground coal mines today. One method by which tailpipe DPM can be reduced to MSHA limits involves using an exhaust cooling device in conjunction with a high-temperature, disposable diesel particulate filter.

Jan 1, 2011

By Irene Bendanillo, Canon Cheung, Justin Lianides, Derek Penrice

The SLAC National Accelerator Laboratory’s two-mile-long particle accelerator generates the world’s brightest X-rays from its Linac Coherent Light Source (LCLS) freeelectron laser. This facility has driven groundbreaking discoveries in medicine and industry. The LCLS-II-HE project will provide a significant increase in laser energy, allowing cutting-edge research in fields including biology and environmental science. A key project component is the Low Emittance Injector Tunnel (LEIT), a 240-foot-long tunnel to be built alongside the existing accelerator and connected to it via a 30-footlong Transfer Tunnel. This paper discusses site and scientific constraints that led to the selection of the LEIT configuration: tunnels to be constructed using the sequential excavation method in mixed-face conditions comprising native rock and placed backfill, and critical design considerations including protection of overlying and adjacent historic structures and structural accommodation of near-fault seismic loading.

Jun 13, 2023

With mine activity dating back to 1792, the Lehigh Valley, about 80 km (50 miles) northeast of the historic Allentown/Bethlehem steel mills and about 160 km (100 miles) northeast of Philadelphia, PA, defined early-day coal mining. Coal mining began just nine years after the end of America?s Revolutionary War. The high-carbon, clean-burning anthracite coal that was hand-dug from the Pennsylvania hills fueled the steam engines that powered the Industrial Revolution, helping build early steam ships and even the first automobiles. Around 1910, at the peak of the U.S.?s early mining effort, there were more than 250,000 men working underground ? 10,000 of them in the Lehigh Valley.

Jan 1, 2012

By G. P. Hand

The purpose of this paper is to bring to your attention the various kinds of high performance graphites available today, their characteristics and possible applications. These materials are products of a proprietary high temperature technology developed by Superior Graphite Company. We feel we have only begun to tap the potential of this technology and the utilization of the resulting products. During the course of the paper, we shall investigate high purity, high performance graphites made from raw materials such as mined natural graphites, synthetic graphites and petroleum derivatives. We shall define their characteristics and resulting benefits to current applications, along with applications currently under development. It is our desire to stimulate speculation and development of current high performance graphites and their applications as well as ideas for new high performance products and applications. First, a little background about the process. The technology was developed through a concentrated R&D effort which culminated in 1976 in the construction of a unique furnace capable of continuously processing tonnage quantities of granular carbons at temperatures in excess of 2,500 degrees C. This process is capable of refining various carbonaceous raw materials, including natural graphites, to levels of purity and consistency that were previously unattainable in commercial quantities. Carbon contents in excess of 99.9% are currently being produced on a continuous flow-through basis. Since beginning operation in 1977, this plant, located in Hopkinsville, KY, has been expanded in stages to its present capacity of producing over 45,000 tons of purified graphites and graphitic carbons per year. In addition to the purification process, the technology used allows the introduction of selected elements into the carbon/graphite structure to provide additional benefits. Elements of interest include boron, silicon, copper, iron and rare earths. The characteristics of and applications for some of these products will be discussed later.

Jan 1, 1990

By S. A. McGhee

ASARCO Incorporated embarked on a modernization and expansion program to improve overall operating efficiencies and to more effectively develop the large mineral reserve at the Ray Complex Open-Pit Mining operation located near Kearny, Arizona. Major elements of this Ray Modernization and Concentrator Expansion Project included engineering and construction of a 54,400 MTPD (60,000 STPD) In-Pit Crusher and Overland Conveying System. and a 24,200 MTPD (30,000 STPD) Copper SAG Concentrator and Tailings Disposal System. Detailed engineering, procurement, and construction management were initiated in November 1989 under contract with Bechtel Corporation. Field construction commenced in May 1990 leading to mechanical completion and start-up during February 1992.

Jan 1, 1993