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By W. M. Houston

Pebble phosphate deposits of Florida have been established from south of Hardee County to north of the Georgia state line or a distance of over 200 miles and mining has been carried out in an ever-increasing scale since 1885. Deposits that can be mined on the economical standards of today, however, are confined in a roughly circular area about 30 miles in diameter, generally within Polk and Hillsborough Counties, in the central part of the State. The phosphate deposit, which is in the Bone Valley formation of the Pliocene age, is covered by Pleistocene terrace deposits of unconsolidated quartz sand. The matrix is composed of approximately 1/3 clay slimes, 1/3 silica sand and 1/3 phosphate pebbles. The phosphate occurs usually as rounded pebbles, ranging in size from about 1 inch down to approximately 400 mesh. The phosphate may vary from well- defined hard pebbles to soft weathered rock. The color and character of the phosphate will range from smooth buff pebbles to black and white or "salt and pepper rock." The screen size distribution varies considerably between locations and the recoverable phosphate varies may extend down to the 400 mesh size in some areas, while in others the phosphate may cut off sharply at about 35 mesh.

Jan 1, 1962

By James P. Bowersox

Modem mineral processing plants handle large amounts of ore and produce large tailing streams. Plant performance can be optimized when the water is quickly recovered with a thickener. The caisson thickener was developed to overcome process and mechanical problems with the conventional traction and center column units. The caisson is a hollow center column that serves as a pump house. The rake arm structure is supported by a hydrostatic bearing which sits on top of the caisson. The caisson thickener with a hydrostatic bearing has operated for many years in several mineral processing applications.

Jan 1, 1981

By Gregory M. Rumbaugh, Todd R. Kostecki, Christopher Mark

The paper examines five massive pillar collapses in underground stone mines in the eastern United States from 2015 to 2021. These collapses caused significant airblasts, surface subsidence, and damage to mine infrastructure. The study identifies factors contributing to pillar collapses, such as slender pillars with width-to-height ratios of 0.8 or less, and proposes a framework for evaluating and mitigating collapse risks.

Nov 1, 2023

By W. O. Kerr

As in other industries, companies engaged in mining and extraction use and develop intellectual property (?IP?) in the form of new technologies or production processes. The development of IP assets in mining may occur as a byproduct of ongoing operations, or result from investment in dedicated R&D efforts. New technology may lower costs, increase quality of output, and/or increase operational efficiency or safety. Key business questions with respect to any new technology are how best to use IP assets, how to protect them and how to derive value from them. IP assets can provide a competitive advantage to a developing firm that uses the technology to improve its operating results. The developing firm can preclude others from using the technology if it believes that is the best way to exploit the technology?s value. Or, it can be shared with others taking care to ensure rights are maintained, thereby generating royalty income or strategic value through cross licensing or other business relationships. Either way, in order to fully realize the maximum economic benefit, innovators must protect the IP assets and control their dissemination.

Jan 1, 2012

By D. Kruse

Top-down constructed large-diameter (up to 90 m or 300 ft) shaft design and constructability issues present an interesting suite of challenges and opportunities highlighted in this paper. The study covers 2D and 3D finite element models used to analyze various failure modes, evaluate the shaft liner and internal structures' response to seismic loading, assist in segment design and assess final structural design tradeoffs. Efforts to achieve economic advantage over conventional heavy civil practices have prompted innovative solutions for ring and segment design, ring build assembly and annulus backfill grouting. Intended for soft ground conditions, relationships between soil parameters and structure design are also explored. Mining Engineering, 2011, Vol. 63, No. 9, pp. 81-88. Official publication of the Society for Mining, Metallurgy and Exploration, Inc.

Jan 1, 2011

By Henry P. Ehrlinger

These are exciting times for those of us involved in the discovery, development, beneficiation, sales and end uses of industrial minerals. The known sources of traditional raw materials are rapidly being consumed or covered up with highways and urban developments. We would never knowingly cover up a source of gold, silver, diamonds, or even base metals with a shopping center, but it has been difficult to justify not locating construction atop a limestone, granite, or sand dune deposit. During the last ten or so years most of the users of significant amounts of industrial minerals have established task forces made up of geologists, mining engineers, beneficiation experts, ceramic and refractory scientists, and senior members of their purchasing departments whose duty it is to determine where the raw materials for their particular finished products will come from now and farther down the road, like 20 years from now. Likewise, these same ceramic and refractory scientists are developing new materials which require a never ending change into different raw materials and the traditional materials must be refined by selective mining, exotic beneficiation practices and expensive but necessary post-beneficiation treatments to produce minerals for commercial use that were either theoretical minerals or at best showcase specimens when most of us here today were in school studiously acquiring a vocabulary which included Calcite, Magnesite, Dolomite , Feldspar, (Labradorite had the play of colors the prof could see but which I rarely focused on) Wollastonite, Celestite, Chromite, Olivine, Barite and Lepidolite to name a few.

Jan 1, 1976

By R. J. McGregor, Deepak Malhotra

Engineers frequently encounter situations where decisions that are counterintuitive to the logically trained engineering mind are made because of other influences, whether they be financial, social, cultural, or environmental. Such influences can overrule the "logical" decision-making process. The aim of this book is to explore some of the nontechnical issues, which most engineers don't learn about in school, that can have a major impact in the mining industry. This chapter gives a brief overview of this volume and introduces the topics that will be addressed.

Jan 1, 2001

By O. Salami, G. Xu

Fire accident is one of the most classic safety concerns in underground mines both in the USA and abroad. It may occur from pool fires due to leakages in hose or pipes, vehicle fires, or fires in tires and conveyor belts in the underground mines. It may also result from the storage of flammable materials such as gasoline, diesel, and explosives in the underground. When fire occurs in an underground mine, it releases heat, smoke, and other toxic gases such as carbon monoxide, and methane to the surrounding thereby making life unbearable to the miners. Furthermore, smoke greatly impact visibility in the underground which makes evacuation even more onerous and challenging. To this end, a thorough investigation of fire behavior and spread of toxic gases in a practical underground mine is imperative to develop a reliable emergency evacuation plan in an event of fire disaster in the underground mine. The objective of this study is to investigate temperature variation and CO spread along mine airways by conducting full-scale fire experiment in the underground mine. The results presented from this study are crucial to developing evacuation plans in underground mines. In addition, the findings from this study could be used to validate existing evacuation models.

Mar 2, 2022

By Ihsan Berk Tulu, Mustafa Can Suner

The synthetic rock mass (SRM) approach is a relatively new method to study the mechanical behavior of rock masses. Recently, an SRM approach was established to estimate pillar strength from laboratory scale to in-situ dimension using the two-dimensional Universal Distinct Element Code (UDEC). In this study, the developed methodology is applied to the S-Pillar database to estimate pillar strength and failure mechanisms as a function of width-to-height ratio of the pillars. First, stone mine rocks are categorized into three as low-, medium-, and high-strength according to their uniaxial compressive strength (UCS). Later, laboratory-scale intact rocks are scaled-up to the average in-situ pillar dimensions by explicitly considering the naturally existing joint sets. It is found that the strength of the pillars with low-UCS are overestimated when compared to pillars with high-UCS. This observation is attributed to the high joint density of the pillars with high-UCS. After obtaining in-situ pillar strength, the width-to-height ratios of the pillar models varied from 0.5 to 2.0 to gain a robust understanding of pillar mechanical behavior. Tensile failure is found to govern the pillar behavior with the width-to-height ratio of 0.5 while the combination of tensile failure in rib elements and shear failure in the core

By William C. Peters

"A large proportion of the earth's surface is blanketed by young sedimentary formations and by recent lava flows. How many Guanajuatos lie concealed beneath the rhyolitic capping of the Sierra Madre of Mexico? How many Kirkland Lakes are under the drift cover of the Canadian Shield? How many Wilunas are still hidden by the alluvium of the desert of Western Australia? How many ore deposits lurk underneath the basalt-covered plateaus of the Columbia River region? If erosion at Goldfield, Nevada, had stopped 100 feet higher, probably no ore would have been exposed. How many Goldfields are still awaiting discovery?" --Hugh Exton McKinstry, 1948

Jan 1, 1969

By William H. Engelleitner

Agglomeration by balling in cylindrical or shallow pan devices dates back to the early part of this century. The first sintering tests conducted by Dwight-Lloyd on nonferrous ores included a mixing step for ore, flux and fuel carried out in a deep pan device similar to the balling pans, or discs, presently in use. Further work directed mainly toward sintering of ferrous and nonferrous ores always included a preparatory step, usually referred to as mixing, agglomerating or green-balling of the ingredients. In the late forties and early fifties two methods of particle preparation prior to firing were in general use. In Europe the balling pan was used predominantly, both as a mixer and as a pelletizer. In the United States many pilot plants and semi¬commercial plants used balling drums. When the first iron ore pelletizing plants were built in this country, the most frequently used device for green-balling was the cylindrical drum. At the same time, the pan device was used both in Europe and the United States for many other materials such as fertilizer, cement, flyash, alumina and copper concentrates, as well as to mix the feed for sinter machines. The difference between these two balling devices - -the drum and the disc - has been the subject of much discussion and is well covered by several papers included in the 1962 publication "Agglomeration' issued by AIMS, based on their 1961 International Symposium held in Philadelphia. (1)

Jan 1, 1965

By J. W. Oberholzer

This paper describes research being undertaken by the Chamber of Mines Research Organization (COMRO) which is designed to assist the continuous miner operator and section foreman in the performance of their jobs. The project will initially provide visual assistance to the miner operator, and later will semi-automate the mining (cutting) process. Using a technique known as "RF tagging," the project will also provide real-time or near-real-time information about the performance of the loading and hauling units to the section foreman, allowing him to quickly detect problems and take action where appropriate. The project is based upon the application of currently available technology, and the first phase is scheduled for in-mine testing within the next year.

Jan 1, 1991

By S. D. Thompson

Since 1965 several researchers have independently developed computer models for designing gathering belt and surge bin capacities in underground coal mine belt systems. Table 1 summarizes the models applicable to U.S. mining systems. Most of the models, employ the Monte Carlo simulation technique. Basically, the belt loading at each loading point is randomly produced from probability distributions. In some cases, a combination of deterministic calculations and probability distributions are used to simulate the loading. Once the loading is simulated, it is systematically moved through the belt system in a deterministic fashion based on belt speeds, belt lengths, and storage bin discharge rates. The coal flowing from each loading point is tracked as it moves through the belt system. When the loading from tm different sources combines on a belt or in a surge bin, checks are made to determine if capacities have been exceeded. If capacities have been exceeded the amount of spillage is calculated. At the end of the simulated time period, the cumulative spill- age is used to evaluate the belt and surge bin capacities. Naturally, a considerable amount of spillage indicates the capacities are unacceptable. Acceptable capacities are generally indicated by minimal spillage. Numerous trial simulations are often necessary to find the acceptable capacities.

Jan 1, 1987

By Dean E. Albon

In the late 1940's and early 50's in southern Illinois, the usual open pit blasting in the coal field consisted of one or two rows of churn drilled vertical holes being shot with instant electric blasting caps. The entire shot detonated at one rime. In southern Indiana and Ohio most mines were drilling horizontal holes and they too were primed with instant EB caps. During the ten years from 1355 through 1965 many changes occurred in drilling and blasting methods. The churn drill in southern Illinois and the horizontal drill in Indiana and Ohio were replaced by the rotary vertical drill. The ammonia dynamites and liquid oxygen explosives were replaced by ANFO. The elctric blasting cap in the hole was replaced by a detonating cord down line and detonating cord trunk lines made the connections between holes and rows of holes. Host open pit mining was in areas far enough from town that the noise and vibration from blasting was, if not ignored, at least tolerated. During the 1960's open pit mining expanded to account for nearly 50% of the coal produced. Mines came closer to town and towns expanded along the highways with suburban homes and mobile homes. The mines began receiving complaints about the noise and vibrations from blasting operations.

Jan 1, 1976

By James K. Kindig

Solvent extraction as a method of purifying and concentrating metal values from solution has become a standard hydrometallurgical operation for recovery of both uranium and vanadium, and within the past two years it has been put into operation in a commercial plant for recovery of copper from leach solutions. In this first full scale solvent extraction plant for recovery of copper operated by Ranchers Exploration and Development Corporation near Miami, Arizona, a kerosene solution of an organic compound, LIX-64® is used to selectively extract the copper from the dilute acidic copper sulfate leach liquor obtained from heap leach operations. The copper is back extracted from the solvent into a stripping solution which is fed to an electrolysis circuit producing cathode copper for sale.

Jan 1, 1970

By S. G. Axen

Design of wells for in-situ leaching is based on individual mining operation and ore deposit requirements. Major design considerations are well flowrate, depth, fluid composition, expected well life, mine operating plan and cost. A large variety of downhole equipment, materials of construction, contract services and methods of well completion and stimulation are available. A generalized design procedure which allows the engineer to optimize well design for a particular ISL application is described.

Jan 1, 1988

By Francesco Chiappalone, Miriam Piemontese, Lance Waddel, Paolo Perazzelli, Emidio Tamburri, Roberto Schuerch

The Three Rivers Protection & Overflow Reduction Tunnel is part of the Long-Term Control Plan of the City of Fort Wayne, Indiana (USA). The 4.9 m internal diameter tunnel, of length approximately 7.5 km, is excavated at a depth of approximately 40–60 m through carbonate rocks using a slurry TBM. Due to the high hydraulic conductivity of the rock mass and the high in-situ ground water pressure (up to 6.5 bar), the management of the water inflow during the TBM advance and standstills, represents the major challenge for the project. This paper outlines the geotechnical conditions and the hazards related to the large water inflows expected in the pre-excavation phase and discusses the experience gained during the construction of the first 8,224 feet (2,507 m), (first third of the total length of the tunnel).

Jun 13, 2021

By John Mahoney

We live in a world of change and the mining industry is enjoying some of the most rapid changes today that have been seen in a long time, We'd like you to open your mind to a new concept in material handling. Figure # 1 Shows a new concept combining some of the proven application advantages of the power shovel with which we are all familiar, and applies the advantages of the dragline for the benefit of the user. First, the hydraulic excavator enjoys tooth forces of the shovel because the dipper is attached to the machine with a dipperstick and boom, and can often actually realize greater tooth forces than a shovel because of the prize action of the dipper in hard digging. Second, the hydraulic excavator enjoys the application advantage of the dragline because both the operator and the machine are up above, sitting on top where the operator oversees the excavation and the machine's operating work range is greatly increased.

Jan 1, 1973

By Muriel S. Robinette

Ground-water contamination from uranium operations could be avoided with proper site analysis techniques. Contamination from tailings disposal sites is carried downgradient within permeable hydrostratigraphic units which can be located and delineated with a combination of drill holes, borehole geophysical logs and surface geophysics. Several case studies are presented to illustrate this application.

Jan 1, 1980

By L. Yuan, J. H. Rowland

"In 1995 and 2003, the U.S. Mine Safety and Health Administration (MSHA) conducted surveys to determine the number of atmospheric monitoring systems (AMS) that were being used in underground coal mines in the United States. The survey reports gave data for the different AMS manufacturers, the different types of equipment monitored, and the different types of gas sensors and their locations. Since the last survey in 2003, MSHA has changed the regulation requirements for early fire detection along belt haulage entries. As of Dec. 31, 2009, point-type heat sensors are prohibited for use for an early fire detection system. Instead, carbon monoxide (CO) sensors are now required. This report presents results from a new survey and examines how the regulation changes have had an impact on the use of CO sensors in underground coal mines in the United States. The locations and parameters monitored by AMS and CO systems are also discussed.IntroductionThe last survey conducted by the U.S. Mine Safety and Health Administration (MSHA) on atmospheric monitoring systems used in underground coal mines in the United States was in 2003 (Francart, 2005). A total of 146 active mines were surveyed. The survey report states that since 1995 there had been a steady increase in the use of atmospheric monitoring systems in underground coal mines as the technology of carbon monoxide (CO) sensors was improved by manufacturers. Atmospheric monitoring systems had become more reliable, and some CO sensors could be purchased with the capability to discriminate between the CO produced by a fire versus CO produced by diesel equipment. This increase in reliability had reduced the number of false alarms and the response time. The faster response time to a developing fire allowed miners to take the necessary action to put out the fire or exit the mine.At the time of the last MSHA survey, some mines still used point-type heat sensors to detect the presence of a fire on conveyor belts. This detection method works by measuring the temperature of the air around the sensor. As a fire starts to develop, smoke and hot gases are produced from the combustion process, and the air is heated up. Once the air and gases reach a designated temperature detected by the point-type heat sensor, a fire alarm signal is generated. Studies have shown that the response times for detecting the presence of a fire using CO sensors are much shorter than when using point-type heat sensors (Conti and Litton, 1995)."

Jan 2, 2018