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By Stan Tang, Yiming Sun, S. Amir Reza Beyabanaki, N. Sathi Sathialingam

The Kurve mixed-use development project including a 22-story tower at 2801 Sunset Place was constructed on a site consisting of a roughly rectangular-shaped lot at the intersection of Wilshire Boulevard and Hoover Street in Los Angeles. Two Metro Red Line tunnels, with depths of approximately 30 feet and 58 feet, respectively, cross below the building at distances of approximately 1 foot to over 63 feet from the site. This paper presents numerical modeling performed to evaluate the ground and tunnel behavior in response to building construction. Results of geotechnical instrumentation and monitoring undertaken during the building construction are also discussed.

Jun 13, 2023

By J. Duran

Mining at Phoenix is currently done by surface operation in the Fortitude and Bonanza Pits, at a combined rate of approximately 110,000 tons per day. A portion of the ore bodies targeted by these pits was mined previously by underground mining methods, dating back to the mid to late 1800?s. Most of the underground workings (voids) are located in the west central area of the Bonanza Pit. The surface operation requires excavation through voids, and there is a risk of pit floor subsidence that has to be addressed. This paper presents a review of the risk mitigation measures that were implemented to reduce risks to people and equipment working in the area.

Feb 23, 2014

By James T. Curry

The steady growth of the Northwest portion of the United States over the past two decades, and the very rapid development of Northern California, Western Nevada, and Oregon in particular, led the Calaveras Cement Company people to Shasta County, California in 1957. The presence of a large deposit of high calcium carbonate limestone had been recognized for many years, but it required the momentum of an expanding economy to make these long known reserves valuable. This, plus the availability of a reliable supply of fuel in the form of natural gas, and the ready means of shipping the product to the consumer both by highway and railroad, seemed to offer the proper combination to launch a successful venture. The Calaveras Cement Company had been manufacturing cement by the wet process since 1925 at their plant at San Andreas, California. Starting with two small kilns, the plant in Calaveras County started an expansion program in 1945 that ultimately resulted in the plant as it exists today, consisting of five kilns with a combined production of 4.5 million barrels annually.

Jan 1, 1967

By Tuncel M. Yegulalp

This article summarizes some of the results of the continuing research activity at the Henry Krumb School of Mines, Columbia University, directed towards a better understanding of the stochastic behavior of slurry flows in underground coal-slurry pipeline systems. The slurry system under consideration here replaces all conventional haulage systems between the coal face and the coal preparation plant on the surface. At the beginning of the pipeline system, flow rate and frequency of coal slurry is very closely related to the activities of production equipment at the coal face. Due to several scheduled and unscheduled interruptions in continuous miner's coal mining activity, resulting slurry flows possess stochastic characteristics. Proper understanding of these characteristics is believed to lead to a more realissic and economic design of slurry handling equipment. Fundamental ideas supported by field observations are presented and a Semi-Markov model of the slurry flows is developed. As a result of this formulation, behavior of combined slurry flows from N independent coal faces can be expressed in analytical form. The contents of a slurry surge tank receiving slurry flows with certain stochastic characteristics is investigated as a function of discharge pump characteristics and time.

Jan 1, 1981

By G. R. Burman

Gilsonite is a brittle, natural solid bituminous resin, classified as an asphaltite. It is found in near-vertical veins in the Uintah Basin of Eastern Utah. Discovered well over 100 years ago by Samuel Gilson, this unique material has, since its finding, enjoyed a variety of commercial and industrial applications. Early uses for the product included black automotive paint and beer vat linings. Among its many important uses today are additives for oil well drilling fluids and cements, additives for sand castings for the foundry industry, reinforcing agent for asphalt pavements, and dispersing agent for black inks. Gilsonite is mined and processed in Bonanza, Utah, by two companies, American Gilsonite Company (AGC), an operating division of Chevron Resources, and Ziegler Chemical, a privately held company headquartered in New York.

Jan 1, 1990

By A. Torrance, M. G. Seo

Velocity of detonation (VOD) is an important variable when evaluating the performance of mine blasts. Typically, for a VOD measurement, individual probes have to be loaded into each blast hole that requires a measurement, which increases the loading time and is not representative of the whole blast. Experimental studies of electromagnetic pulse (EMP) from the detonation of explosive charges show that electric and magnetic field signals are observed when chemical explosions occur in the air, at the ground surface, and in the underground. EMP has the potential to evaluate VOD of the whole blast without impeding the loading process. Due to a variety of physical causes which make the electromagnetic effects complex, measuring EMP of the detonation of explosive charges has not been fully studied yet. Five different antennae were tested with explosives, which are commonly used in mining industry. Among the five antennae, aluminum and copper tape, and wire were successful to detect the EMP. INTRODUCTION The measurement of the velocity of detonation (VOD) helps in evaluating and comparing relative performance of explosives in mine blasts. A VOD of an explosive is usually predicted by empirical mathematical equations or measured in-hole by VOD meters. However, conventional methods to measure a VOD have constraints: only a limited number of holes can be measured because cost of consumables for such systems is very high, and systems only allow a certain number of holes to be measured. The measurement cables have to be placed into the holes prior to loading with explosives which means that preparing to take the measurement is time consuming and has to be well coordinated with the mine. In order to evaluate VOD for a whole blast, there is a possibility of using electromagnetic pulse (EMP) from the detonation of the explosives. As there are many parameters that affect the generated EMP from explosive charges, measuring EMP of the detonation of explosive charges has not been fully studied yet. Most studies conducted relate to military related explosives, not the ones frequently used in mining industry. This research has been performed to have a better understanding of EMP from the types of explosives which are commonly used in the mining industry. To discover a way to detect EMP efficiently, five different types of antennae have been studied in the air and in the underground blasting conditions: coil, monopole rod, log periodic, wire, and aluminum and copper tape. LITERATURE REVIEW Conventional methods of measuring VOD Over the years, demands for more accurate theoretical predictions and physical measurements of the effects of the explosives have increased. Especially when both demand and commodity price decline, mining companies are keen to understand the effectiveness of explosives since it has a direct relationship with fragmentation, which influences their production rate. Since the 1940s, various methods have been devised to determine VOD of explosives.

Jan 1, 2019

By R. T. Hukki

The paper describes a two-stage industrial hydraulic classification system including hydrocyclones for primary classification and newly developed cone classifiers for secondary classification. Performance data based on large scale grinding and classification tests are presented.

Jan 1, 1981

By John W. Leonard

The typical tunnel boring machine in use on today's tunnel project uses 15'2-inch diameter cutters at a nominal load of 45 kips per cutter. The cutterhead rotates at a speed of 120 over D revolutions per minute where D is the cutterhead diameter in feet. The typical machine operates about 50 percent of the time. Delivery of a new machine takes 12 to 15 months. The TBM is a specialized tool and not applicable to all jobs. There is a range of job conditions that limit the economic use of a TBM. The machine should provide a thrust per cutter at least twice the compressive strength of rock in psi and up to three times the rock strength is required if in "granitic rocks." The rock strength in psi must be at least three times the cover above the tunnel in feet or the machine may stick. For example, 2,500 feet of cover requires at least 7,500 psi rock to avoid problems. When the RQD's over a significant distance of the project are less than 50, the TBM becomes support-bound. When a large percentage of the time is spent waiting while the ground is supported, the TBM cannot perform well (See Figure 1). This problem increased inversely with tunnel diameter. We are finding that increasing the RPM's does not significantly increase progress. The increased RPM results in a substantial decrease in cutter penetration. The explanation for this decrease appears to be vibration, cutterhead drag, or lack of stiffness in the cutterhead (See Figure 2).

Jan 1, 1981

By J. W. MacDonald

PROPERTY AND PRODUCTION: Around 100 Million Tons of Recoverable Coal are available from the approximate 10,000 acres allocated to the mine. Over 1300 acres of surface land holdings extend well beyond the limits required for plant site, storage tracks, water supply reservoir, settling ponds and waste disposal. COAL: Extensive core drilled testing confirmed the early indicated high quality of the #6 Seam Washability data show less than four percent of the' coal seam required removal to provide a superior product for the available market. PREPARATION PANT DESIGN: The limited needs enabled Preparation Plant Design to meet the requirements without inclusion of novel equipment. The simplified needs afforded ample opportunity for considering increased automation where advantage or economy was antioipated. Plant design included protection of opportunity for pre-drying in advance of air cleaning the fine coal and accommodations for addition of Dense Media separating equipment in event warranted or required by future market changes. Protection is also afforded for addition of Raw Coal Storage accommodations in event warranted. Figure I shows the Preparation Plant Flow Sheet.

Jan 1, 1961

Despite two large projects represented in the keynote docket, the mood of the 2011 SME Arizona Conference was summed up best by Ferol Baker, general manager of New Mexico Copper Corp. (a wholly owned subsidiary of Themac Resources Group), ?In the past, it seemed like you couldn?t go to a conference like this without hearing about one big new greenfield project after another. Now what you see is companies doing internal expansion or small-scale brownfield development.? Overall, the tone of this year?s meeting, held at the J.W. Marriott Resort at Starr Pass in Tucson, AZ, was upbeat, yet practical. From the keynote and luncheon addresses to the six panels of sessions, the projects described were positive about the future, yet focused on the details required to make those projects come to fruition.

Jan 1, 2012

By Mitchell Gordon

Two mineral processing facilities in North America required near terminal density slurries to perform de-bottle necking in their circuits. The installation at Barrick Goldstrike to ensure efficient oxidation conditions and throughputs in the refractory ore treating autoclaves. The Kidd Metallurgical Division unit to provide a steeper tailings slope to extend the life of the existing tailings dam. To achieve these goals, both operations selected a Supaflo "High Compression" Thickener following on site pilot plant evaluation. Commissioning and the first year of operation is reviewed. Operating data is compared with the pilot plant data. In particular, unusual doughnut formation at Goldstrike and the effect of temperature on the terminal density at Kidd Metallurgical Division are discussed.

Jan 1, 1997

By H. V. Scotland III

Lafarge Corporation's Texas Quarry, in Baltimore MD, achieved a substantial expansion of pit reserves by removing an inactive underground mine. The day lighting program, designed, and completed in 1997, open pit mined more than 400 meters of room and pillar workings which were originally developed to recover high brightness Calcium Carbonate. The project proved to be a challenge throughout its course as the pit plan was modified and successful daylighting techniques were developed to remove the mine without adversely affecting the safety of the operation, quality of the stone recovered, or negatively impacting the surrounding community. The design parameters and techniques developed and implemented at Texas may prove of interest to other operators as they are faced with daylighting opportunities. This article will detail the challenges we faced and the solutions which made the project a success.

Jan 1, 1999

By R. C. Emmett

The industrial practice of concentration of solids and production of clear solution by gravity sedimentation is an old technology. Through the years, many devices have been designed and built to aid this process. One of the more significant developments was a revolving rake mechanism to convey settled material to a central discharge point of a circular tank, patented in 1907(1). In recent years, clarification systems employing parallel inclined plates have appeared on the market; the original device utilizing this principle was patented in 1886(2). Numerous other methods have been invented, tested, discarded and sometimes re-invented, all with the specific intention of improving the capacity of a particular settling area. Sedimentation theory, as expressed in Stokes' Law, shows that the rate of settling of a particle is directly proportional to the difference in density between the particle and the surrounding liquid and, more significantly, proportional to the square of the particle diameter. Anything that can increase the latter will greatly assist sedimentation and, as a result, flocculation always has been an integral part of sedimentation. Most materials suspended in aqueous media are naturally flocculent to some degree and, hence, are readily concentrated by sedimentation, although sometimes very slowly.

Jan 1, 1978

By D. A. Swanson

Predicting when and at what rate seepage will occur from waste-rock facilities is becoming an integral part of permitting and closure at mines situated in dry climates. Such predictions require development of a conceptual framework that accurately describes how water will percolate through a waste-rock facility. Also needed is a detailed hydrological characterization of the waste-rock facility, including measurement of the hydraulic properties of the waste rock and any potential cover materials. This paper presents a conceptual framework describing unsaturated water flow in a waste-rock facility and describes methods for characterizing the hydrology of a waste-rock facility in a dry climate. The methods are designed to collect site-specific data to support accurate and defensible predictions of long-term seepage rates.

Jan 1, 1998

By J. García, B. Arango, F. Calderón, O. J. Restrepo-Baena, A. Carreno, L. Rojas-Mendoza, J. Pérez, E. Bedoya

"Tungsten extraction is a subject of global interest due to is properties. These properties, such as its high melting point, have contributed to the development of metallurgical extraction processes that can be adapted to the particular chemical composition and mineralogy of the ore. In Colombia there is a research deficit in tungsten related areas, and especially with regard to its extractive metallurgy. In this study the physical, chemical and mineralogical characterization of a sample were performed. Subsequently, crushing and grinding were employed to reduce the material to a more convenient size, making it suitable for further concentration and metallurgical processes. Through physical concentration techniques it was obtained a concentrated ranging between 60 -70 % of WO3 content.INTRODUCTION Tungsten is a metal of great economic importance due to its excellent properties such as high density and extraordinary melting point 3422°C), which is indeed the highest of all the elements. Tungsten is primarily used in metal alloys, manufacture of special steels, coatings and catalysts; products of interest to both international and national industry. However; given that the use and economic value is determined by the percentage of tungsten in the mineral, particle size and chemical associations, it becomes essential to properly characterize the mineral to further define possible metallurgical extraction routes. The metallurgical processes for minerals enriched in tungsten may vary depending on location and the genesis of the ore body, which means that for each ore a particular set of operating conditions must be determined. This is important since process standardization can lead to misuse of the mineral resource. However, in Colombia there is a research deficit as it relates to minerals enriched in tungsten and to its extractive metallurgy. Then, there is a need to conduct studies that can lead to a better understanding of the ore, and to develop extraction processes for the metal of interest. EXPERIMENTAL A state of the art review was made in order to gain insights of the tungsten metallurgical process. Comminution was necessary with the aim to reduce the sample size; therefore the sample was taken into crushing and grinding stages. Concentration techniques such as magnetic separation, gravity and / or electrostatic were also applied. Physical, chemical and mineralogical characterization were performed by using polished sections, grain size determination, X-Ray Fluorescence (XRF) and X-ray diffraction (XRD) techniques."

Jan 1, 2015

By Ashis Bhattacherjee, Rahul Upadhyay, Nearkasen Chau, Aditya Kumar Patra, Dhanjee Kumar Chaudhary

Heavy earth-moving machineries used in openpit mines intensively expose drill operators to whole-body vibration and shocks, and thus to musculoskeletal disorders. The roles of individual, machine and rock-related factors in their exposure remain poorly understood. This cross-sectional study investigated their roles in 39 drill operators from Indian iron ore mines. It shows that 70 percent of the operators were exposed to high levels of vibration, above the limit values recommended by ISO 2631-1 (1997). Multiple linear regression models showed that the whole-body vibration and shock exposures were strongly associated with operator’s age, drill-machine model and rock hardness, uniaxial compressive strength and density. The role of body mass index was close to significance (p = 0.08). Univariate analyses found the drill’s age, seat-pad thickness and seat backrest height were also strong predictors. These results help in identifying risky operators, materials and occupational situations, and in implementing appropriate prevention and intervention strategies to reduce and monitor the exposures and health risk. In addition, during the planning stage of acquisition of new equipment, anthropometric data of the operators should be considered for the ergonomic design of the seat.

By T. Stack, C. Roos, M. Drake, P. Conrad

"This paper presents the evaluation Montana Tech completed for the Western Energy Company Rosebud Mine relating to the benefits of survey data collected using novel technologies over traditional methods for topographic surveys. These technologies include Unmanned Aircraft Systems (UAS), photogrammetry, and laser scanning/LIDAR. Utilizing these technologies, large areas such as reclamation areas and cast blasts can be surveyed in a timely manner for use by the mining operation. The areas that were evaluated were the improvements in the safety of employees and the time required to collect data. In addition, there is also a potential cost savings for the operation, all while not affecting the accuracy of the data that is collected. PROJECT BACKGROUND Accurate topographic survey data is critical to successful surface mining operations. It is used for mine planning and design as well as permit compliance. Currently, employees typically collect survey data using GPS equipment or total stations. These methods can be dangerous, as they require employees to work near large operating mobile equipment, edge of high walls, and on piles of stacked steep-sloped loose material. Aerial and satellite photographs, performed by a contractor, can be used to obtain some of this information, but it is expensive and may not be attainable during overcast conditions. Montana Tech, along with the Rosebud Mine, conducted research on the accuracy, cost, and other benefits of survey data collected using novel technologies. Some of the methods studied include, but are not limited to, Unmanned Aerial Systems (UAS) or Vehicles (UAV), photogrammetry, and laser scanning. These methods were evaluated to determine if these technologies provide mining companies with a safer, cost effective, and accurate method to collect data for surface mining operations. The project scope was to evaluate various surveying techniques to determine which techniques would be applicable for the Rosebud Mine and complete a trade-off study comparing the new techniques with currently used methods. The trade-off study included an analysis of the technological differences between the methods, safety and legal considerations for the new techniques, operational limits, and the costs associated with each technique. Working with the Rosebud Mine team, techniques were selected for field trial and accuracy comparison. This paper presents a literature review of applicable technical papers and a summary of the Federal Aviation Administration regulations for UAS, followed by a study comparing conventional GPS topographic surveys with UAS based systems and laser scanning systems. The comparison of the various methods was broken into the following four categories: operator safety analysis, time comparison, survey accuracy, and cost analysis. After all of these portions of comparison were completed a recommendation was provided based on the evaluation that was performed."

Jan 1, 2017

By R. Gray

"Experience from Australia has identified what is referred to as non-conventional surface subsidence behaviour. This occurs under irregular surface topography, resulting in valley closure, valley floor uplift or “upsidence”, and far-field horizontal movements – even occurring beyond conventional “angle of draw” limits. This paper discusses such behaviour recently observed in Pennsylvania and focuses on the 2005 case of Duke Lake Dam in Ryerson Station State Park. In July 2005, there was a significant increase in water leakage through a number of growing cracks in the dam leading to the dam being breached to avoid an uncontrolled failure. An underground longwall mine was located approximately 900ft to the north, mining at depths of 330 – 720ft. Investigations (including a subsequent ground movement monitoring program) found a range of evidence in the vicinity suggesting that valley closure and far-field horizontal movements may have occurred resulting from the adjacent mining. The paper discusses the phenomenon of non-conventional subsidence behaviour and the Ryerson State Park case study, including an assessment of mining, geology and subsidence impacts and suggested ground behavioural mechanisms. INTRODUCTION Non-Conventional Subsidence The conventional understanding of coal mine subsidence on which most current subsidence understanding and prediction techniques are based, includes the concept of angle of draw which effectively limits the lateral extent of subsidence effects and impacts. Within this zone – above and marginally beyond the boundary of mining – downward vertical subsidence is the dominant component, together with localised horizontal movements towards the mined region, with related tilts and strains. However, more recent experience from Australia over the last two or three decades has identified what is referred to as non-conventional surface subsidence behaviour. This is found to occur in areas of irregular surface topography or variable terrain, and is characterised by phenomena such as valley closure, valley floor uplift or upsidence, and far-field horizontal movements, all of which can occur beyond the conventional angle of draw limits. NSW Department of Planning (2008) defined the conditions for both conventional and non-conventional subsidence behaviour as follows: “The conventional or general model of surface subsidence, which finds worldwide acceptance, is based on assuming the following site conditions:"

Jan 1, 2015

By John Hickey

Management teams at mining companies begin to ask themselves whether to take a company public and, if so, how to do it as they approach the normal threshold for going public in terms of revenue and operating performance. Today, the expense of going public generally suggests the company has at least $20 million in annual revenue and at least $2 million in cash. The revenue number can be lower for mining companies with large reserves. In order to properly attract the investing public, the company must also be operationally strong with robust prospects. The company should have a strong management team and a consistent history of double-digit growth that will continue into the foreseeable future. Assuming the thresholds are met, a company?s management needs to weigh the pros and cons of going public.

Jan 1, 2012

By Thomas B. Faddies

The Trixie mine is located in the East Mining District. Since production began in 1970 over 450 000 tonnes of ore grading 239 grams of silver, 6.9 grams of gold, and 1.2% Cu have been mined from veins in Cambrian Tintic Quartzite. Detailed geologic mapping and extensive sampling are essential for compiling the data base required for efficiently developing and mining known reserves as well as planning exploration and development work. Although the basic techniques used by the geology group at the Trixie were developed many years ago, the reduced activity in underground precious metal mining in the U.S. have made these techniques less familiar to many presently active geologists. The increased activity in precious metals search and exploration again offer cause for the application of these techniques as a prerequisite to efficient exploration, development and production.

Jan 1, 1983