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By J. Douglas

The past year has been a strange one for the fertilizer industry of the world and the United States. Listening to news stories, you would think the sky is falling on the world's agriculture and probably conclude that we should have had an exceptionally poor fertilizer season. In some respects, we did. Prices were low, profits were low, and in some cases nonexistent, but volume was good. We heard much in the press about the farmers' credit crunch. The truth of the matter is that only 6.6 percent of the U.S. farmers have debt-equity ratios of 70 percent or more, and a large percentage of our farmers have absolutely no debt but operate entirely on their own cash assets.

Jan 1, 1985

By J. M. Mercier

Approximately seven (7) years of recent intensive mining activity in the Wasatch Plateau Coal Field of Utah has revealed distinct geologic patterns which, at times, profoundly influence reserve estimates, coal quality, mine layout, and reserve accessibility. Mine planning, economic feasibility, and resource recovery activities by Getty Coal Company utilize a multi-faceted approach by necessity when evaluating Utah properties. Two specific operating mines offer examples of the affects of adverse geologic conditions on mine operation and project economics.

Jan 1, 1984

By J. R. J. Edwards

Jaspilite, a mineral consisting of silica and iron oxide in varying proportions, is one of the host rocks of the high grade ore deposits situated in the Middleback Range of South Australia. As a result of laboratory investigations, a flowsheet was postulated for the beneficiation of jaspilite to produce an acceptable grade product for feeding to blast furnaces, The flowsheet involved the reduction of the hematite in the haspilite to magnetite, the grinding of the reduced product to 95 pct minus 325 mesh Tyler followed by wet magnetic separation, hydroseparation and filtration to yield a magnetite concentrate. Agglomeration of the fine concentrate would then be necessary to meet the physical requirements of blast furnace feed. To prove the postulated flowsheet, to obtain a more accurate estimate of costs and to obtain design data for a commercial installation, a pilot plant was constructed at Whyalla, South Australia.

Jan 1, 1960

By Gösta W. Diehl

During the past five years the use of all-hydraulic drilling equipment has increased rapidly, and we have now reached a point where the hydraulic drill has become an alternative to be seriously considered for every drilling operation. The hydraulic drills have many advantages over pneumatic drills, but they also have certain characteristics, which makes a potential user hesitate before making the switch. And when the decision to use hydraulic drills has been made, the user then faces another choice of equal difficulty: the choice between different hydraulic systems. This paper discusses some of the factors to be taken into account when considering hydraulic drilling equipment for rapid tunneling in hard to medium hard rock. THE CHOICE BETWEEN HYDRAULIC AND PNEUMATIC EQUIPMENT The choice between a hydraulic and a pneumatic drill is much more than just that: It is a choice between two different systems. The choice is usually based on the productivity, economy or ergonomy of the system. However, also other factors should be considered, such as service capabilities and training requirements. And finally the choice will be influenced by the need to acquire know-how in the new technology. Productivity If the prime consideration is to achieve the highest possible tunneling speed, then the high penetration rates of the hydraulic

Jan 1, 1979

By D. J. A. Chambers, J. M. Wempen, K. D. Koper, M. K. McCarter, K. L. Pankow

"The EarthScope Transportable Array (TA) of broadband seismometers (www.usarray.org) was deployed across southwest Wyoming from November 2007 through May 2009. During this time period the Array Network Facility (ANF, anf.ucsd.edu) detected and located a total of six seismic events near the trona-mining district. This lack of seismicity is atypical compared to coal mines employing similar mining methods. In this study, eighteen months of continuous seismic data from several nearby TA stations are reexamined using conventional and correlation-based methods to detect seismic events. Waveform cluster analysis and epicentral locations are used to discriminate between mining induced seismicity (MIS) and seismic energy generated from surface blasts at nearby coal mines. The locations and magnitudes of the 143 newly detected MIS events are compared to regional subsidence as measured by Differential Interferometric Synthetic Aperture Radar (DInSAR). INTRODUCTION An abundance of natural resources and a favorable political climate have made southwest Wyoming home to multiple large mining operations. Among these operations are five underground trona mines located approximately 50 km west of Rock Springs, Wyoming. The trona mines employ room and pillar, longwall, and solution mining methods over an area roughly 900 km2, and produce a sizable portion of the world’s soda ash (Brown 1995). Historically, in the Rock Springs mining district, several relatively large magnitude seismic events have occurred. These events are thought to have been related to mining activity and have caused notable subsidence (Case 1997). The largest event in the region recorded by seismometers, ML 5.1, has been confirmed as the 1995 Solvay Trona Mine collapse (Pechmann et al. 1995). In addition, blasting at surface coal mines near Rock Springs produces significant amounts of seismicity; approximately 50% of all daytime seismic events in the Mountain time zone from 2007 to 2009 locate near an active surface mine in this region (Astiz et al. 2014). Much of the current research related to surface subsidence and induced seismicity focuses on wastewater impoundment (Ellsworth 2013) and hydraulic fracturing. The observable seismicity in geological injection environments is widely variable and McGarr (2014) has argued that, in such environments, the maximum amount of seismic energy that can be released is proportional to the injected volumes. Like injection environments, in extraction (mining) environments seismicity is highly variable depending on many geological and operational variables (Boltz et al. 2012; Carnec and Delacourt 2000; Fritschen 2010; Iannacchione et al. 2005; Sen 2013) and does not always correlate well spatially with subsidence, a surface expression of extraction at depth."

Jan 1, 2015

By Benjamin Grunauer, Anthony Iannacchione, Taylor DaCanal

"In Pennsylvania’s rich mining history, various forms of room-and-pillar mining have been in use for over 150 years. Longwall mining, introduced in the late 1960s, occupies only the last 60 of those 150 years and now represents the dominant method of extracting coal in the Pittsburgh coalbed. The introduction of longwall mining allowed larger quantities of coal to be extracted in safer and more efficient manners than room-and-pillar mining. However, the associated formation of subsidence basins have elevated both the number and intensity of watersource and surface structure impacts. When these first longwall panels were mined the factors responsible for these impacts were poorly understood and regulations were focused only on surface structures. Today, with over 600 panels mined under a wide range of conditions, these factors are known and regulations have developed to help mitigate water supply and surface structure impacts.The cause and severity of surface effects are thought to be dependent on multiple factors, including the location within the subsidence basin, overburden, panel width, and orientation of the panel. The changing characteristics of over 600 longwall panels mined in the last 60 years are analyzed to determine factors important in subsidence related surface impacts. This study compares the location of the surface impacts with the longwall panel size, overburden, and maximum predicted vertical subsidence. The data shows that changing these characteristics are impacting surface features in a significant manner as measured by the number of company liable reported effects.INTRODUCTIONLongwall mining has occurred in Pennsylvania for over 60 years, and at the current mining rates, longwall mining is expected to continue in the Pennsylvania Pittsburgh Coalbed until the reserves are exhausted. Figure 1 shows all mining that has occurred in the Pittsburgh Coalbed, as well as the area that is left to mine. It is predicted that there are 40 years left of longwall mining on the Pittsburgh Coalbed, under the assumption that 50% of the total 280,000 acres will be mined at the current rate of 3500 acres/year."

Jan 1, 2019

By H. E. M. N. Moursy, Hassan El-Shall, M. N. Ahmad, Ponisseril Somasundaran, C. R. Holland, D. Chandler, G. Walker, Regis Stana, Patrick Zhang

The reaction kinetics of the acidulation of Moroccan phosphate rock (32% P?05) using 45% nitric acid were investigated using the Shrinking Core Model (SCM) , a newly developed Diffusion Model (DM) and a newly developed Combined Reaction and Diffusion Model (CRDM). This was achieved buy conducting a number of experiments in a controlled batch reactor system at different temperatures. The conversion and the reaction rate were calculated at different time intervals. The SCM based on reaction time and the CRDM characterize the acidulation process of phosphate rock. Diffusion of nitric acid and the products of acidulation at the early stages of reaction through the phosphate rock were found to be the rate-controlling step, resulting in a dif- fusion coefficient, which controls the mass transfer process. The reaction kinetics were found to fit first-order kinetics especially during early stages of reaction time. The deviation of the kinetics from first-order at later stages was due to the fact that the overall reaction was mass transfer controlled with respect to nitric acid and products diffusion.

Jan 1, 2002

By W. A. McKinney

In conventional dump leaching of porphyry mine strip wastes, many years are required to extract up to 20 percent of the copper from the contained sulfide minerals. Furthermore, none of the molybdenum, gold, or silver in the strip wastes is recovered by current leaching practices. Because mineralization occurs predominately along fracture planes, breaking of the rock during mining operations liberates and concentrates some of the metal values in the fines. Research shows that upgraded fines can be screened from mine wastes and froth floated for early recovery of copper, molybdenum, gold, and silver. For example, screening a dump sample assaying 0.35 percent copper as chalcopyrite removed about 20 percent of the copper as minus 1/4-inch material that analyzed 0.6 percent copper. About 35 percent of the molybdenum and 20 percent of the gold and silver also reported in the fines. Crushing the mine dump sample to minus 3 inch before screening increased the distribution of copper and molybdenum in the minus 1/4-inch screen fraction to 28 and 50 percent, respectively. Similar results were obtained by screening fines from two other large samples of mine waste dump materials. Flotation studies established that the enriched minus 1/4-inch fines from the three dump samples could be effectively concentrated. Comparative testing revealed that the combination of froth flotation of fines and acid-ferric sulfate leaching of the coarser fraction enabled doubling the recovery of copper over direct leaching of the samples. In addition, significant amounts of molybdenum, gold, arid silver were recovered by flotation.

Jan 1, 1970

By A. J. Naldrett

Over the past six or seven years important new ideas have been developed concerning the origin of nickel sulfide deposits. To a large extent these have been stimulated by the major nickel discoveries of the Eastern Goldfields area of Western Australia (Woodall and Travis, 1969; Ewers and Hudson, 1972). Prior to these finds, the most important nickel camps were regarded as being associated exclusively with intrusive rocks such as the Nickel Irruptive at Sudbury or the intrusive peridotites at Thompson, rocks that were thought to have no close association with volcanism. Study of the Australian discoveries, coupled with work in South Africa (Viljoen and Viljoen, 1969) and Canada (Naldrett and Mason, 1968; Pyke, Naldrett and Eckstrand, 1973), has shown that volcanic rocks with true ultramafic compositions and extrusion temperatures of 1400 to 1600°C were a common feature during the Archean. Under certain circumstances economic concentrations of nickel sulfides have formed from these rocks, either settling to the base of their associated flows or accumulating in shallow intrusive feeders to the flows. The aim of this article is to show how these ultramafic rocks can be recognized, how the nickel deposits, if present, are likely to occur within them, and what special features characterize ore-bearing examples of the rocks.

Jan 1, 1975

By S. W. Beckman, L. Williams, A. E. Seep, R. Fischer, J. Hubbard

Introduction The Summitville Mine located in southwestern Colorado was added to the National Priorities List in June of 1994. Summitville was the site of mining operations that began in 1873 with the discovery and development of gold placer and lode deposits in the late 1800's. The mine site is located about 25 miles south of Del Norte, Colorado in the San Juan Mountains adjacent to the Rio Grande National Forest at an approximate altitude of 11,600 feet. The site was mined for gold, silver and copper between 1873 and 1947. The Summitville Consolidated Mining Corporation, Inc. (SCMCI), a wholly-owned subsidiary of Galactic Resources, Ltd of Vancouver, Canada ran a large tonnage open-pit mine and cyanide heap leach operation from 1986 to 1992 (Pendleton and Posey, 1992) During the mine operation by SCMCI, approximately 10 million tons of gold ore was mined, crushed and stacked on a lined leach pad. Heap leach operations experienced water balance and unplanned solution discharges from the start of the mine life. Despite the production of 249,000 troy ounces of gold during the mine operation, SCMCI was unable to meet remedial requirements and notified the state of Colorado of its intention to file a Chapter VII bankruptcy in December 1992. The EPA Region VIII Emergency Response Branch took over site operations on December 16, 1992 to prevent a catastrophic release of hazardous substances to the environment. The multiple contamination sources at the mine site are due to both historic and SCMCI mining operations. Emergency response operations at the site have prevented releases of severely contaminated solution and a permanent treatment for all waste units at the site is under investigation. A Request for Proposal (RFP) was issued in October 1993 by Environmental Chemical Corporation (ECC) at the Request of EPA Region VIII, Department of the Interior and Bureau of Reclamation. The RFP requested that interested companies provide information on their ability to implement innovative treatment technologies to improve treatment efficiency and reduce treatment costs for remediation of the heap leach pad (HLP) spent ore and ore leachate solutions. Dames & Moore and Pintail Systems, Inc. (PSI) jointly submitted a proposal suggesting application of biotreatment processes for detoxification of cyanide in spent ore and HLP leachate solutions. The proposal was accepted for pilot and field demonstration under the SPA Superfund Innovative Technology Demonstration Program (SITE) with additional funding from EPA Region VIII. This report discusses the test program and results of a Focused Feasibility Study which demonstrated biotreatment processes for spent ore cyanide detoxification.

Jan 1, 1995

By R. R. Beebe

Marcona Corporation produces about 3.5 million long tons of iron ore pellets annually on its two travelling grate pelletizing machines at San Nicolas, Peru. During 1969, these pellets will be shipped to customers in four marketing areas--Japan, the United States, Europe, and South America. All of these sales are on the open market, and product quality is a major concern. Typical chemical, structural, and quality test results for Marcona pellets are given in Table 1. [ ]

Jan 1, 1969

By M. D. Ross

Complex combinations of technical, economical, safety and environmental factors are causing mining engineers everywhere to review their operations. Naturally, some of the traditional methods still have a large role to play because they are, in certain circumstances still adequate and are well understood. But, as circumstances change, a new approach is required. The combination of technical and economical reasons for introducing Long- wall mining in some seams in the United States is associated with strata control. Other reasons include simplifications and improvement of ventilation, reduced coal dust, more output from each unit and crew, increased percentage of recovery from each area of the coal deposit, and reduction of rock dusting. The innovations which transformed Longwall mining from a cyclic to a continuous mining system were the armored conveyor and power loading machines, but the crucial breakthrough for application to high production was the development of the powered roof support, which at once gave the system the advantages of mastery of strata control, increased rate of advance, significant reduction of manpower, and increased safety.

Jan 1, 1974

By Wayne Wride, Amy Lamb, Debra Sonntag

In today's "information age", we have the ability to collect volumes of data about a company's performance. The challenge is to turn that data into information employees can understand and use to fine-tune equipment, modify work processes, and ultimately manage production. Software programs have increasingly given end users control over what data is used and how it is presented. Kennecott has implemented an information system capable of collecting and storing data at the primary level. This enables plant personnel to transform historical data into information for action. Kennecott plans to expand its data collection and use trending and reporting capabilities to move toward a fully optimized operation.

Jan 1, 2000

By Thomas L. Mell

Continuous processing plants handling liquids have achieved a high degree of centralized automatic control. Many chemical plants are operated from one room, with automatic control of the various process flow rates. These plants know from experience that automatic control can produce higher through-put, better uniformity of product, decreased operating costs and reduction of storage capacity, Plants which process materials in the form of bulk solids have not been able to use control to as great an extent, primarily due to the lack of measuring equipment capable of providing the same types of continuous automatic control available with liquid flow meters. This paper will describe a scale for measuring flows of bulk materials on conveyor belts which is particularly adaptable to remote centralized instrumentation and automatic control, and will also describe some typical control applications. Fig. 1 illustrates the basic method of measurement of this scale. A conveyor belt idler is supported on a rigid carriage which in turn is mounted in two anti- friction bearings on the conveyor stringers. The pivoted carriage is prevented from rotating about the pivot shaft by an electric strain gauge load cell connected between the carriage and a cross support. Increasing load on the conveyor belt increases the moment of the carriage frame about the pivot shaft, and proportionally increases the tension in the load cell. The belt speed is measured by a conventional d. c. tachometer generator driven from a pulley, usually on the return belt. The speed signal from the tachometer generator and the load signal from the load cell are combined to produce a signal proportional to the flow rate of material in tons per hour, or lbs. per foot, or equivalent units, It will be important to remember, in considering various control applications, that the flow rate of material on the belt is composed of these two component signals, namely the weight of material and the speed at which it is moving. The feed rate is then indicated and recorded by a self-balancing potentiometer of the type used for measuring temperature by means of thermocouples. These instruments may also be equipped with integrating mechanisms reading the totalized tonnage over a period of time.

Jan 1, 1958

By M. K. Rizkalla

This paper discusses the time-dependent behaviour of rock when it involves the presence of several layers of rock strata in the vicinity of mine openings, mining in sequences and the placement of backfill. The paper describes numerical techniques which proved useful when such situations are encountered in practice. The model is elastoviscoplastic. At given time stations, short term loading or changes can be made to the creep behavior of the rock. The modelling technique is first described and is followed by simulations of stresses and displacements in a potash mine with the primary objective to demonstrate the effect of such aspects as mining and fill sequences in 3-D. This involves cutting finite elements representing the strip of the mining face and simultaneously filling those elements representing the newly placed fill. The stiffness of the fill varies with the degree of compaction at each point. In this way, the effect of the time of fill placement, the gap between the top of the fill and the back as well as the degree of compaction are simulated. The second example is a 2-D problem simulating the long term effect of backfill, as a material compacting with time, on the settlement of the layers above it as well as the closure of the room.

Jan 1, 1996

By C. S. Davis

In being asked to present this paper on the improvements in loading and hauling equipment and the effect on unit costs, Mr. Van De Water, your program chairman, stated that his reason for coming to a contractor was due to the wide experience of, and I quote: "a large contracting firm using a variety of equipment on varying types of earth moving jobs." We people in Utah Construction Company are flattered that Mr. Van De Water singled out our Company for this assignment. Utah Construction Company's participation in open pit mine stripping antedates the 1920's, when overburden was being removed from copper ore in Bingham Canyon, Utah. Our first stripping con¬tract for the Copper Company was finished in 1912. Since that early beginning, Utah has, as a contractor, been engaged to strip and mine iron ore properties, coal properties, copper properties, uranium properties, phosphate,-gypsum, limestone and dolomite properties. And, as you know, the Company has become a major producer of iron ore from Company-owned open pit mines. Utah Construction Company has been instrumental in the evolution of open pit mining tools. Some of the first tools were the old wood and coal fired stream shovels which had to be fired hours before a shift started to insure a full head of steam, providing power to excavate with the then large 1-1/2 cubic yard buckets. Today, Utah's strip mining is done, with 18 cubic yard and 10 cubic yard crawler shovels. Yesterday's horse and mule drawn, iron wheeled wagons, with 1 and 2 cubic yard capacity, which were hand dumped by removing the false bottom, one 2 x 4 at a time, have been replaced by today's- 50-ton capacity, hydraulic, rear dump trucks and giant 40-ton coal haulers. Utah Construction Company used the early fresnes and wheeled scrapers which were horse and mule drawn. Often, an operator holding too tightly to a handle was thrown into his horses when a hard spot turned the scraper, a contrast with today's 20 and 25 cubic yard, self-powered diesel and diesel electric Gargantuan rigs; with power controls that relieve the operator of practically all physical work. This Company has pioneered many of today's advances in equipment with shop made prototypes, features of which were adopted and elaborated upon by equipment manufacturers.

Jan 1, 1959

By M. Scaggs

"Respirable dust in underground coal mines has long been associated with lung diseases, and regular dust sampling is required for assessing occupational exposures. At present, respirable dust concentration and crystalline silica content are commonly determined, but considering recent and yet unexplained increases in the incidence of lung disease amongst miners in specific geographic regions, more information about specific dust characteristics is urgently needed. While particle-level dust analysis is ideal, it is impractical for large numbers of dust samples because it is both time and cost intensive. Thermogravimetric analysis (TGA), however, is an alternative option, which offers the ability to determine the total coal to mineral mass ratio in a dust sample – analogous to proximate analysis of bulk coal samples for determining ash content. Here, preliminary development of a TGA method for this purpose is presented. The method is being developed to evaluate dust collected on mixed cellulose ester (MCE) filters using approved permissible sampling equipment. INTRODUCTION Based on the particle size, airborne mine dust can be classified in three categories: inhalable dust (< 100 µm in size), thoracic dust (< 25 µm in size), and respirable dust (< 5 µm in size) (Ramani et al., 2003). The World Health Organization (WHO, 1999) defines inhalable dust particles as those which can be breathed into the nose and mouth, and thoracic dust particles as those which can penetrate airways of the head and enter the airways of the lung. On the other hand, respirable dust particles can penetrate beyond the terminal bronchioles into the gas-exchange regions (alveoli) of the lungs (WHO, 1999). Hlavay (1992) reported that the seriousness of the damage in the lungs and respiratory tract is based on amount of dust remaining in these organs, and the amount of dust depends on the extent of dust exposure, the size distribution of the dust particles, and the capability of the body for dust elimination. Inhalation of respirable coal dust by miners can cause a disabling and potentially fatal lung disease which is called coal worker’s pneumoconiosis (CWP). Silicosis is another fatal lung disease caused by inhalation of respirable silica dust. In CWP and silicosis, dust particles deposit in the lungs, damage the lung tissue, and ultimately cause scarring which cannot be reversed (Colinet, 2010). While overall incidence occupation-related lung disease amongst coal miners in the US has been declining for over 40 years, it appears that there has been a recent increase in specific locations in Central Appalachia (CDC, 2006; Pollock et al. 2010; Suarthana et al., 2011). Although this trend is yet unexplained, one theory is that particular dust characteristics in these locations may be a factor (Hassan and Lau; Page & Oraniscak 2002). For example, several studies have indicated that different coals may generate different amounts of respirable dust (e.g., see Page, 1993 and Litton and Page, 1994), and the surrounding geology may also play a role in terms of the types of dust particles generated. Although respirable dust concentration and crystalline silica content are commonly determined as part of regulatory compliance sampling, more information about specific dust characteristics (e.g., size, shape and composition) is urgently needed."

Jan 1, 2015

By R. K. Singhal

This new tool can be used for the proper assessment of the potential economic wealth of any risky capital project. It does provide an unambiguous recommendation of the type "go or no go" to the decision-maker simply by comparing two different ratios profit/investment. One ratio determines the minimum value required to at least break-even while the other measures a probable value based on the asymptotic theory of statistical extremes (weakest link concept). Its application is briefly illustrated by means of an underground gold mine project, an oil sands mine project and a poly-metallic open pit project.

Jan 1, 1993

By Harold V. Fairbanks

This investigation included a study of three different methods for the acoustic drying of ultrafine coals. Ultrafine coal being defined as coal which passes through a 100 mesh sieve. The first method employed stationary drying of small coal samples in sound fields having frequencies of 12,000 cps and 20,000 cps. Sound intensities up to 150 db were used. The second method employed the use of rotary drying kilns. The effect of such variables as temperature, sound intensity, coal feed rate, air flow rate, and initial moisture content were studied. The third method employed the use of a multi-tiered, vibrating screen dryer. The effect of initial moisture content and residence time were studied.

Jan 1, 1970

By L. R. Nelson

Cyprus Pima is a medium-sized open-pit copper mine located 35 km (22 miles) south of Tucson, AZ. The ore body was discovered using geophysical prospecting methods in 1953 and was originally worked as a small underground mine followed by small open-pit operations. As mining equipment grew larger and the economic ore grade dropped, the operation grew in size, through four expansions, to the present 50 500 tpd (56 500 stpd) milling rate. The remaining stripping ratio is about 2.5 to 1. Mining equipment includes 11 electric shovels ranging in size from 6 to 15 m3 (8 to 20 cu yd) and 42 diesel-electric haulage trucks ranging in size from 89 to 223 t (100 to 250 st). Mine planning is performed at Cyprus Pima to serve several functions. The most important is to plan ahead, one year at a time, to predict the ore grade and stripping requirements on a month-by-month schedule. This yearly plan is necessary for budget preparation and is revised once each quarter to incorporate variations in actual production experienced during the preceding quarter.

Jan 1, 1979