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By William E. Bonini

Gravitational field anomalies have been observed over many igneous intrusives of medium (4000 km2) to small (100 km2) size in outcrop area. These studies give good results because the residual anomalies can be separated from larger scale crustal anomalies and density contrasts usually are present. Although unique solutions are not possible, the analysis of the gravity anomalies can put limits upon the geologic interpretation of such bodies. Three examples in Montana, U. S. A. are discussed: (1) the Boulder Batholith, a late Cretaceous quartz monzonite series of intrusives of 4000 km2 outcrop area; (2) the Little Rocky Mountains, an up-domed area, in which an Eocene porphyry (130 km2) has intruded the Precambrian crystallines and lower Cambrian sediments; and (3) the Crazy Mountains, an Eocene diorite (100 km2), which has intruded the Paleozoic and Mesozoic sediments. In both the Boulder Batholith and the Little Rocky Mountains, intrusive rocks are less dense than the surrounding rocks and negative anomalies are found (40 and 28 mgal, resp.). In the Crazy Mountains, the intrusive is more dense than the surrounding sediments and a sharp positive residual anomaly of 42 mgal is observed. The analyses of the gravity anomalies predict that: (1) the thickness of the Boulder Batholith is on the order of 10 to 15 kms and is concave upward; (2) the Little Rocky Mountain syenite is not a simple laccolith, but is T-shaped and extends in depth to about 16 kms; (3) the Crazy Mountain diorite is not a simple small scale series of stocks, but a large connected body extending in depth 5 kms to the basement (although nothing can be said of it within the basement because there is little density contrast). The analyses of the anomalies place important limits on both the areal and depth extent of the intrusive bodies. Of all possible geophysical techniques, gravity studies offer the most promise in the determination of the shape in depth of intrusive bodies.

Jan 1, 1969

By Rolf N. Schulz

The recently completed major modifications and additions to Reserve Mining Company's taconite concentrating process incorporate a totally new control system. Design of the new control scheme is centered on reliability, versatility, centralization, and optimization. The design objectives were achieved through a distributed control system based on a network of independent field located micro-processor based control systems connected to a central control room. Operation of each micro-processor can be interrogated and modified from the central control room by the operator or by either of two computer systems. The two computer systems handle logging, alarming, specialized sequenced controls, and complex process optimization routines.

Jan 1, 1980

By John P. Anderle

A tectonically disturbed sequence of Mississippian age evaporites expressing a 5 milligal negative gravity anomaly near Sussex in southeastern New Brunswick, Canada, was investigated by a program of drilling, geologic and geophysical work over the past 27 months. Seventeen of twenty-one drill holes have penetrated 10 to 140 feet of potash mineralization in a salt sequence underlying 2 000 to 3 000 feet of arenaceous, conformable red beds, also of Mississippian age. Bromine and borate studies, lithological characteristics and geophysics, have facilitated improved understanding of the salt structure. The salt sequence has been affected by f1owage which has resulted in both major and minor folding. In the more disturbed areas, the potash interval was extensively subterraneally eroded at the upper anhydrite-salt contact.

Jan 1, 1978

By Bruce A. McKinstry

Introduction For many major mining projects the time frame from initial planning to production can be measured in decades. Hecla's Silver Shaft project, scheduled to go into production by the end of this year, includes a complete surface facility, shaft with an ultimate depth of 2.4 km (7,700 ft), complete ore pass and loading pocket system, and 610 m (2,000 ft) of development drifting and stope preparation. The project was conceived in the fall of 1979, and the duration of a mere four years from conceptual engineering to production is testimony to what can be accomplished when a mining company and a contractor work as a team rather than developing into two warring camps, as often happens. Engineering In 1979, Hecla Mining Co. awarded a contract to J. S. Redpath Corp. to perform feasibility investigations and design engineering related to a proposed new shaft facility at the Lucky Friday Mine. The Lucky Friday, in Mullan, ID, is a major producer of silver, as well as significant quantities of lead and some zinc. In late 1979, stoping was in prog-

Jan 10, 1983

By Robert W. Roscoe

For over a century, St. Joe Minerals Corporation in Southeast Missouri has been sinking shafts for their lead mining operations. Upon discovery of the Viburnum Trend, or "New Lead Belt", St. Joe brought its experience and expertise in shaft sinking to the area. Eleven shafts were then sunk in an 18 year period, ending in 1972. In 1981, St. Joe began sinking a new shaft in the Trend with hand-picked employees from the four operating lead mines and service facilities. The paper describes the general history of St. Joe shaft sinking methods and equipment, focusing on the current development of the Viburnum No. 35 Shaft.

Jan 1, 1983

The next 13 years gave me an education that anyone, then or now, would well envy. W.T. Reid had founded Belmont School along the lines of Groton and, as at Groton, he sent many graduates to Harvard. He obtained excellent teachers and maintained as strict a discipline as the independent nature of the western students would stand. With a beautiful location in an unspoiled little valley in the foot- hills of the Coast Range there was every chance for walks and expeditions. The years at Belmont were good ones. My closest friends were Harold Jordan and Lewis Hackett. Lewis was son of the military director at the school. With half a dozen other very young inmates we early won the sobriquet of "The Dirty Dozen." Sliding down a steep muddy hill on barrel staves helped us earn the name. An inherited shyness exaggerated my sensitivity at being a "teacher's boy" and this prevented a close association with the wilder western boys who made up most of the schoolmates. Trapping wildcats and coyotes in the brush-covered hills and taking long walks gave me plenty to do. I had grown too fast and when I went to college was 6 ft 3 in. tall and weighed only 145 lb-hardly a respectable bean pole. I was only two months past 16 when I left for Harvard. The long summer vacations were happy ones. Most of them were spent in the high mountains, and even when I was ten years old I could keep up with anyone on long steep climbs. I learned to handle a rowboat during our stays at Lakeside, a rustic resort at the south- east corner of Lake Tahoe that could then be reached only by the steamer that made a dally trip around the Lake. Several of the teachers at Belmont remained good friends as long as we were on the same side of the continent. The finest was C.H. Rieber, who taught mathematics at Belmont for the first few years we

Jan 1, 1976

The U.S. National Institute for Occupational Safety and Health (NIOSH) conducted a study to determine the effectiveness of a filtered air delivery system to reduce respirable dust exposure of roof bolter operators in underground coal mines. When performing roof bolting operations, roof bolter operators may experience exposure to high levels of respirable dust during a working shift, especially when working downwind of the continuous mining machine. While drilling and installing roof bolts, this filtered air system supplies a clean curtain of air over the roof bolter operator by means of a plenum mounted beneath the canopy. This experimentally designed air curtain, adapted for roof bolting machines used in this study, is based upon previous design prototypes, computational fluid dynamics (CFD) simulations and trial-and-error testing. Both the prototype and final designs were tested in the full-scale mining galleries at the Office of Mine Safety and Health Research (OMSHR) in Pittsburgh, PA before being taken underground for field testing. Test results of the system in both laboratory and field studies show reductions in operator exposure to respirable dust when the operator is positioned directly under the protected zone of the canopy.

Jan 1, 2012

By Y. J. Son, S. S. Nageshwaraniyer, K. M. Kim

"This paper reports on the development of a simulation-based framework for obtaining optimal blast design parameters for a hard-rock mine. To do this, a conventional medium-sized hard-rock mine was taken as a case study. The mine has two pits containing hard and soft rock types. The proposed framework contains a combination of regression analysis using Excel software by Microsoft and discrete-event simulation using Arena software by Rockwell Automation, applied to construct a model of the material-handling network of the mine. Specifically, blasting parameters are estimated by Excel-based regression analysis, processes including blasting and haulage from pits to crushers are modeled by a Forward Blasting simulation submodel, and material-handling operations including crushing, storage in stockpile, and haulage via conveyors and into SAG and ball mills are modeled by a Crusher to Ball Mill simulation submodel. A Reverse Blasting submodel is then used to obtain the optimum blast design corresponding to a target P80 particle size. Using the proposed framework, an economic analysis was performed to demonstrate the cost savings that could be realized for each rock type as a function of specific explosive energy. IntroductionIn a modern hard-rock mine, various processes such as drilling, blasting, crushing, grinding and mineral liberation are optimized to increase productivity, a practice known as mine-to-mill (MTM) optimization. Blasting is important in MTM optimization as it is the first comminution process and has an impact on all downstream processes (Julius Kruttschnitt Mineral Research Centre, 1996; Nielsen and Lownds, 1997; Nielsen and Malvik, 1999; Chung and Katsabanis, 2000; Kim and Kemeny, 2011a; Kim and Kemeny, 2011b).Two main research topics have emerged in the area of blasting design: (1) identifying the optimal target blast fragmentation at each shot and (2) controlling the blast fragmentation for that target. As part of an MTM optimization study, Kim and Kemeny (2011a; 2011b) developed a site-specific blast fragmentation prediction model that can be used to identify the target blast fragmentation and can be incorporated into MTM optimization. They also reported methodology for assigning model parameters easily and with minimal human bias."

Jan 1, 2015

By Erik Marsh, Frederick C. Harris Jr., Javad Sattarvand, Joshua Dahl, Alireza Kamran Pishhesari

Based on the mine safety and health administration (MSHA)reports, mining truck accidents are among the significant causes of fatalities in the mining industry. The major causes of haulage accidents can be divided into non-driving and driving factors, such as truck-related sudden failures and operator performance. Numerous parameters affect trucks' safe operation, but situational awareness plays a significant role. Due to the distinct structure of mining trucks, making them efficient for mining purposes, the operator has a very limited field of view (FOV), making them prone to accidents resulting in losing lives. The cabin's position blocks the truck's right and rear sides, creating several blind points around it. Aiming to test/train the operator's awareness of the surrounding, a proximity detection system is developed through a multiplayer virtual reality (VR) application to investigate the human factor in equipment collisions. The operators were examined and monitored when asked to conduct what exactly happened in the Marigold mine truck accident without being aware of the scenario. After receiving sound, vibration, and visual alarm warnings, their reaction and performance were analyzed. The platform is developed using the Unity game engine for HTC VIVE virtual reality goggles. An Omni-direction treadmill and a motion simulator platform are utilized for the player and dump truck operators. Fifteen students were monitored when driving the dump truck receiving/not receiving proximity detection alarms. None of them repeated the accident when receiving proximity alarms. Also, they found the visual alarm the most comfortable while driving the truck.

Jun 25, 2023

By Mark A. Krall, Robert L. Geddes, James C. Frost

Introduction The Conda Partnership's Dry Valley phosphate mine is a thinly bedded, multiple seam open-pit mining operation where selective mining techniques are used to recover phosphatic shales. The mining methods used are truck/shovel and scraper/dozer operations. Ore is shipped 32 km (20 miles) by rail to a beneficiation facility. The ore is upgraded by washing and calcining. The mine and beneficiation complexes are owned by the Conda partnership. It is a joint venture between Beker Industries Corp., of Greenwich, CT, and Western Co-Operative Fertilizers (US) Inc., of Alberta, Canada. The Partnership operates as a separate entity of the two partners. The Dry Valley mine is located 48 km (30 miles) northeast of Soda Springs in Caribou County in southeastern Idaho. The mine is situated on the Caribou National Forest. Mining operations take place between 2 and 2.4 km (6400 and 7900 ft) in elevation. It is accessible partly by 32 km (20 miles) of paved roads and 16 km (10 miles) of dirt roads. The winters are long and severe, and the summers are short and mild. This article describes the history, geology, exploration, mining, and reclamation that makes this mine Idaho's largest producing mine and the western US' leading phosphate producer. History and production In the mid-1950s, Western Fertilizers of Salt Lake City, UT, drove an exploratory drift in Maybe Canyon. A large bulk sample of phosphatic shales was analyzed for phosphate content and processing characteristics. No large scale mining or processing operations were undertaken. In the late 1950s, the Dry Valley property was sold to Central Farmers of Chicago, IL. No major operations took place. In 1964, Central Farmers sold the property to El Paso Products Co. of Odessa, TX. El Paso Products supervised the mining operations of Wells Cargo Mining Co. from 1965 through 1967. During this time, El Paso Products built a beneficiation facility and a fertilizer complex in Conda. A 32-km (20-mile) railroad was also constructed from the mine to this facility. From 1968 through 1972, the mine was shut down due to a depressed fertilizer market. In 1972, El Paso products sold its ore reserves, beneficiation plant, and fertilizer complex to Beker Industries Corp. In 1979, Beker Industries sold 50% of its ore reserves and 50% of its beneficiation plant to Western Co-Operative Fertilizers (US) Inc., of Alberta Canada, forming the Conda Partnership. It has operated the mine and beneficiation plant since January 1979. From the mid-1950s to the mid-1960s, no substantial production took place. From 1965 to 1967, El Paso Products stripped 3 Mm3 (4 million cu yd) and mined 2.3 Mt (2.5 million st). From 1972 through 1983, 50 Mm3 (66 million cu yd) were stripped and 18 Mt (20 mil¬lion st) were mined. Geology The Wells Formation forms high ridges and hillsides in the Dry Valley area. It is best exposed along the west face of Dry Ridge. It forms the imposing wall on the east side of Dry Valley. The formation is divided into two members. The lower member, about 213 m (700 ft) thick, is dominantly thin to medium-bedded limestone and silty limestone. It contains nodules and stringers of chert and minor sandstone. The upper member is composed principally of thick-bedded to massive cross-bedded, light-gray to orange-yellow, fine grained sandstone. There is some interbedded brown to light-gray limestone. This member varies from 369 to 457 m (1300 to 1500 ft). Recent investigations indicate that the upper Wells is of Permian age. Under some conditions, the Wells may be water-bearing. Otherwise, it has no apparent economic significance. Grandeur Member (Park City Formation) Overlying the Wells Formation is a distinctive light-gray to white dolomitic fossiliferous limestone. This unit has been identified by the US Geological Survey (USGS) as the Grandeur Tongue Member of the Park City Formation. This member is sometimes absent due to its contact with the Meade Peak Member of the Phosphoria Formation. It is easily detectable by its color, hardness, and fetid odor. Phosphoria Formation The Phosphoria Formation of Permian age was named from Phosphoria Gulch, Bear Lake County. The formation has been studied extensively and developed for its economically valuable phosphate reserves.

Jan 11, 1985

By Robert E. Charles

Much has been said about digital computer control of metal and mineral ore dressing processes, but little has been done. This pa- per discusses what practical use can be made today of a digital computer in an ore concentrator and how such application can be made successfully. A hypothetical, but commercially common, grinding and flotation circuit is presented in terms of analog measurements which can and are being made in existing plants and a centralized computer control system which is reasonable in terms of today's technology. Dangers and possible disadvantages of such an approach are discussed as well as estimated benefits. Possible future benefits are presented in terms of improved control technology. Development of new measuring devices is not considered as a criterion for computer benefits. The control systems described have been utilized successfully in existing ore dressing operations. However, the degree of success or failure of analog systems is generally left to the interpretation of management rather than absolute analysis. Many factors affect the economic operation of a mineral recovery circuit such as size of facility, flow sheet design, number of operating personnel, percent of recoverable mineral in the ore body, loss to tails, and haulage rates. In existing mills where little or no instrumentation has been used, it is extremely difficult to prove or disprove the advantage of analog control systems on one mill line versus its sisters due to the lack of standards and the lack of ability to separate final products by ton.

Jan 1, 1969

By D. A. Baker, W. J. Mullin, T. P. Philip, P. A. Korpi

Some of you will recall from the last Randol conference held in Cairns, Australia in April 1991 that I shot my mouth off when I declared that I believe that these conferences are covering only a small slice of the overall mining industry pie because the major emphasis is on ore processing. The attendees at these conferences to date have been composed principally of metallurgists, which naturally leads to a preponderance of papers on this important feature, but it is only one of the areas of the mining business.

Jan 1, 1992

By O. F. Brown

Excavation and loading are primary operations in the surface mine production chain, constituting a significant component of production costs. This makes excavation and loading important cost centers that need to be improved to lower production costs. Optimizing the design and use of excavators will improve energy efficiency in earthmoving operations, and this requires a thorough understanding of the soil-tool interaction process. Modeling the interaction process accurately is the key to this optimization. Experimental and analytical methods have provided limited information on the behavior of soils during excavation. Finite element (Fe) analysis of soil-cutting blade interaction produces some advantages over experimental and analytical methods. However, the soil constitutive equations used in most of the available Fe analyses fail to adequately model the plastic behavior of the soil. This work uses Fe modeling to study the behavior of formation-cutting blade interactions in dozer excavation. The formation is modeled as a nonlinear elastoplastic material using the modified cam-clay (mCC) model. The model accounts for soil-tool interface friction, and progressive and continuous cutting at the blade tip. The results provide soil forces, a progressive developed failure zone and soil displacement fields. The sensitivity analysis of changes in blade angle on cutting force shows that the cutting force increases with increasing blade angle. The cutting depth of the blade had a similar effect on blade cutting force. Increasing the depth of cut increases the required cutting force. Increasing the coefficient of friction at the soil blade interface increases the blade cutting force. Reducing the coefficient of friction at the soil blade interface from 0.3 to 0.05 reduces the cutting force by 22.3%. The percentage represents the maximum potential savings in blade cutting force. This research initiative advances the frontiers of soil-tool interactions during excavations to expand the limited knowledge in this critical area.

Jan 1, 2012

Resolution Copper Mining LLC (RCML) is currently in a Pre-feasibility study evaluating a large and deep copper and molybdenum deposit in the historic mining district east of Superior, Arizona. Work scheduled for the next several years includes dewatering the existing shut-down mine (the Magma Mine) and sinking an exploratory shaft to 2,130 meters (7,000 feet) below the surface. To dewater the Magma Mine and sink the exploratory shaft, RCML must extract and manage about 2 billion gallons of accumulated mine water inventory, as well as about 300 million gallons per year of new inflow. In order to conserve a valuable water resource in a desert environment, RCML worked with the New Magma Irrigation and Drainage District (NMIDD) to provide treated mine water to blend with and supplement the NMIDD?s water supply to approximately 2,000 hectares (5,000 acres) of farmland located east of Phoenix. A 44 km (27-mile) pipeline was needed to convey the treated water. It was essential that a treatment system be used which could reliably meet irrigation water quality goals, produce a non-scaling effluent to maintain pipeline flow capacity, and generate a dense sludge minimizing disposal cost and volume. This paper describes the resulting mine water treatment and recovery system (MWTS) and how the system has performed against objectives.

Jan 1, 2011

By Taner Aydogmus

The A$29 billion Chevron-operated Wheatstone Project is one of Australia’s largest resource projects. Located at Ashburton North, 12 kilometers west of Onslow in Western Australia, the project will consist of two Liquefied Natural Gas (LNG) trains with a combined capacity of 8.9 million tons per annum and a domestic gas plant. The LNG Plant will serve the offshore gas fields, which are situated some 250 km off the coast of Onslow in Western Australia. Once operational and on-stream, the Wheatstone Project will contribute to Australia becoming the world’s second largest exporter of LNG. For crossing the environmentally sensitive shore area, a micro-tunnel with an internal diameter of 2 m and approx. 1,242 m in length has been constructed by means of the pipe-jacking method. The micro-tunnel will accommodate a 1.1 m diameter pipeline (trunkline) to deliver gas from the offshore fields LNG Plant. The Wheatstone shore crossing design involves a number of unique challenges owing to its coastal location, where the alignment crosses through a shore area and terminates in a marine environment. This paper provides an overview of the Wheatstone Shore Crossing Project, presents the key features, and discusses the main aspects of the micro-tunneling design.

Jun 13, 2021

By Richard Giffen, Michael Trabold, Pablo Lemus

"As part of the new 2nd Ave Subway Project, an existing tunnel constructed in the 1970’s will be connected to the new subway and used as new running tunnels. The existing tunnel had to be modified to comply with newer structural and fire life safety codes and to be connected to the new cut and cover station at 96th St. This paper will discuss the complexities of tying an existing tunnel constructed over 40 years ago into the new station and allowing for movements due to the unloading of the existing tunnel and the differential settlement of the two structures during both the construction and permanent condition. Topics that will be discussed include structural analysis, ground improvement techniques, selection of support of excavation walls, working in contaminated soil and instrumentation and monitoring of the structures. It will also cover retrofitting the tunnel to comply with updated Fire/Life/Safety requirements. PROJECT OVERVIEW The Second Avenue Subway (SAS) will be the first major expansion of New York’s subway system in over 50 years. To be constructed in four phases, it will run from 125th St. in Harlem to Hanover Square in the Financial District (see Figure 1). For most of its length, the alignment is directly under the Second Avenue roadway."

Jan 1, 2016

By Mark E. Gershon

Extensive efforts are under way to- ward applying computer techniques to mine production scheduling problems. These efforts are concentrated in four areas: optimization, computerization of traditional methods, heuristics and simulations. These areas complement each other rather than compete. Characteristics of each are discussed toward enabling the engineer to evaluate specific systems that may be encountered. Alternative approaches within each classification are described as well as the motivation for each.

Jan 1, 1985

By J. R. Patts, A. B. Cecala, E. J. Haas

Exposure to respirable crystalline silica (RCS) remains a serious health hazard to the U.S. mining workforce who are potentially exposed to RCS [1,2] as various ore bodies are drilled, blasted, hauled by truck, crushed, screened/sized and transported to their destinations. To examine a method for assessing RCS exposure using a NIOSH-developed video exposure monitoring (VEM) technology (referred to as Helmet-CAM), video and respirable dust concentration data were collected on 80 miners across seven unique mining sites. The data were then collated and partitioned using a thresholding scheme to determine exposures that were in excess of 10 times the mean exposure for that worker. Focusing on these short-duration, high-magnitude exposures can provide insight into implementing controls and interventions that can dramatically lower the employee’s overall average exposure. In 19 of the 80 cases analyzed, it was found that exposure could be significantly lowered by 20 percent or more by reducing exposures that occur during just 10 minutes of work per eight-hour shift. This approach provides a method to quickly analyze and determine which activities are creating the greatest health concerns. In most cases, once identified, focused control technologies or behavioral modifications can be applied to those tasks.

By K. Luxbacher, A. Haghighat, B. Lattimer

Mine face ignition due to high levels of methane is one of the most common fire incidents in underground coal mines. In continuous miner headings, depending on the magnitude of the ignition or resulting fire, auxiliary ventilation controls may be damaged or dislodged, affecting the ventilation into the area. A computational study was conducted to investigate the effects of different levels of damage to an exhausting ventilation curtain in a continuous miner heading, and the impact on ventilation to the face. The computational fluid dynamics software Fire Dynamics Simulator (FDS) Version 6.0 was used to predict the conditions that develop due to a 200-kW fire in the face following a methane ignition with different levels of assumed ventilation curtain damage. Smoke layer depth, temperature and mass flow inby the last open crosscut were used to evaluate the impact of no damage to the curtain, partially dislodged curtain, and fully removed curtain. As more of the ventilation curtain was damaged, smoke depth and temperature outby the fire increased. With the full removal of the curtain, the smoke accumulated from the last open crosscut to the face, with the ventilation completely bypassing the continuous miner region.

Jan 1, 2016

By Inoka E. Perera, Michael J. Sapko, Marcia L. Harris

Experiments conducted with limestone dusts and dolomitic marble dusts have indicated that when rock dust is wetted and subsequently dried, it becomes a solid, non-dispersible cake. However, in order to be effectively inert a coal dust explosion, rock dust must be able to disperse as individual particles to air. To counteract this, rock dust manufacturers created treated rock dusts that will resist caking after moisture exposure. National Institute for Occupational Safety and Health (NIOSH) researchers conducted a series of laboratory-scale experiments on four base rock dusts and their treated counterparts to assess the effectiveness of various anticaking additives after being exposed tomoisture and then dried. The dusts were exposed tomoisture using humidity cabinets having a high relative humidity (99% RH) and by also exposing the rock dust bed to water through bottom wicking. The dusts were then evaluated for dispersibility after drying using the NIOSH-designed dust dispersion chamber. The anti-caking additives were different concentrations of stearic acid, oleic acid, and xylene-based surfactants. All results were compared to a reference rock dust used to conduct large-scale experiments in the Lake Lynn Experimental Mine (LLEM), Fairchance, PA. When the untreated dusts were dried after exposure to moisture for 1 day, no dispersion was measured. However, rock dusts treated with anti-caking agents were readily dispersible even after exposure to moisture for 6 months. This report details the analysis and characterization of anticaking additives using the NIOSH-designed dispersion chamber and the 20-L explosion test chamber.

Apr 12, 2021