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By G. G. Marino

Little comprehensive information has been reported on the behavior of room-and-pillar mines. The objective of this paper is to present case data on mine failures in the Illinois basin for use in practice. Presented are results of an ongoing study and details on the site characteristics of cases where sags have developed on the surface. Site data are reported to show the geologic, mining, and sag conditions that existed. Sags mainly develop from pillar, floor, or pillar-floor failure. The character of the sags depends upon the type of mine failure as well as the overburden response.

Jan 1, 1989

By H. H. Murray

New and improved benefication techniques are available to allow the production of clay minerals of exceptionally high purity. This is particularly true for kaolins and smectites. Wet processing techniques including particle size separation, high intensity magnetic separation, chemical leaching, flotation, and selective flocculation are described and results and applications are discussed. The blending of clay minerals with other minerals provide opportunites to make special ceramic materials such as cordierite and other minerals which have very special ceramic properties including low heat expansion, high fired strength, low absorption, and other desired qualities.

Jan 1, 1989

By T. Janke

When Homestake Mining Company's Mclaughlin Gold Project was being evaluated for development, it was apparent that recovery of gold from mined ore would be difficult and relatively expensive. The ore was refractory, averaging less than 50% recovery in conventional direct cyanidation milling tests. Extensive testing narrowed the processing choices to either autoclave or roaster oxidation before cyanidation. Roasting was ruled out due to higher capital and operating costs --the Mclaughlin mill would be the first large-scale application of autoclave oxidation of a refractory gold ore.

Jan 1, 1989

By S. S. Peng

A hybrid boundary element-finite element model was formulated to model roof bolt reinforcement of the roof strata with bedding planes. This model was used to analyze the stress distribution around a rectangular opening with variables such as opening width-height ratio, number of bolts installed, number/location of bedding planes, in-situ stresses, etc. The most critical areas are identified and the number and length of roof bolt required are then determined. Two case examples are illustrated.

Jan 1, 1989

By Shawn Boltz, Erik Westman, Derrick Chambers, Xingdong Zhaoa, Qiankun Zhua

Microseismic passive velocity tomography is becoming an effective technology for large-scale mining-induced stress monitoring in underground mines, especially in the field of early warning of mining-induced hazards. Aiming at the problems of missing low-magnitude events in traditional microseismic monitoring, as well as the potential to increase the resolution of the tomograms in both time and space, a microseismic passive velocity tomography analysis method based on the template matching method was proposed. First, the template matching method was used to pick microseismic events. Then, the probabilistic, non-linear, global-search earthquake location method was used to locate the events and calculate travel time and travel distance. Finally, the fast-marching method was used to carry out passive velocity tomography analysis to image the movement of the abutment stress associated with the longwall. The results show that the selected templates can identify more microseismic events than the traditional microseismic analysis, and the variation trend of events in each day is consistent with the data from the traditional analysis. Using microseismic event locations, travel times and travel distance can effectively complete microseismic passive velocity tomography analysis in each day during the study period and can effectively identify the forward and side abutment stress zones of that longwall panel. This study provides a reference for the identification of mine-induced high stress zones, which has implications for hazard identification and mitigation, with increased resolution of the tomograms in time and space.

Jun 25, 2024

By H. B. Charmbury

In the United States and in Pennsylvania in particular the coal mine drainage problem is of continuing and growing interest to the coal mining industry, the state government, the federal government and the public at large. The 1965 amendments to Pennsylvania's Clean Streams Law prohibit the discharge of acid mine drainage into the streams of the Commonwealth after January 1, 1967. Because of this new legislation, the coal mining industry and state government are extremely aware of the necessity for new techniques for treatment and prevention of the flow of acid mine drainage from the active mines of the Commonwealth in order to keep the coal mining industry in business in Pennsylvania. Approximately one-third of the total volume of mine drainage presently polluting the streams of the Commonwealth originates from "active" coal operations and two-thirds comes from "abandoned" mine discharges. As early as 1963 it became evident that the Commonwealth of Pennsylvania and the coal industry in Pennsylvania would have to take active steps to abate the mine drainage pollution of Pennsylvania's streams and rivers. This became quite clear during the deliberations in Harrisburg which climaxed a twenty year struggle for effective strip mining legislation. The bituminous strip mining law enacted that year made it unlawful to have any acid discharge from active stripping operations.

Jan 1, 1968

By J. R. Henke

Dewatering wells producing iron-rich water experience rapid declines in yield and drawdown due to the formation of ferric (Fe +) hydroxide deposits in well screen, pump intake and riser pipe. Precipitation is caused by a combination of dewatering-promoted iron oxidation and iron-oxidizing bacteria. Physical and chemical well rehabilitation techniques, as well as alternative well construction and well development techniques designed to minimize well clogging, were evaluated in this study. The addition of acid downhole feed systems to dewatering wells prone to iron encrustation can, in some cases, prolong their operational lives up to 500 percent that of unacidified wells.

Jan 1, 1989

By A. L. Wilder

Coeur d'Alene Mines Corporation's newest precious metals property is located in the old Rochester Mining District approximately twenty-five miles northeast of Lovelock, Nevada. Built at an elevation in excess of 6 000 feet, the Coeur-Rochester gold silver heap leach property encountered cold weather operational problems typical of most northern Nevada heap leach properties, soon after the start-up of operations last fall. Due to the size of the heap area under leach at Rochester, it was decided that 1 the usual practice of spraying to an "ice field" and waiting for the spring thaw was impractical. Further, the delivery schedule for a solution heating system of the size required was unacceptable. Accordingly, Rochester personnel embarked on a program to seek out a leach solution distribution system that would enable an operation through the winter and yet be cost effective. The findings of this program were rather dramatic and, as a result, the whole perception of heap leach solution application at Rochester has changed forever.

Jan 1, 1988

By J. Frenzel

The computation of hydrometallurgical equilibria is very difficult because of the many complex species in solution, the precipitates, condensed species, or solids, and the activity coefficient corrections necessary to non-ideal thermodynamics. Our objective was to tryout recently developed genetic algorithms to minimize free energy and solve the equilibrium computation. We selected test problems that were seemingly unsolvable with more traditional algorithms, and we applied genetic algorithms to them. We were pleased to find that genetic algorithms succeeded where other algorithms did not. We concluded that they are an effective tool for hydrometallurgical equilibria.

Jan 1, 1992

By P. M. Brown

The Bureau of Mines, U. S. Department of the Interior, has developed a method of dewatering clay slurries based on flocculation by high-molecular-weight polymers and water removal from the formed flocs using a trommel or hydrosieve. The exchange ion on the clays affects their dewaterability. Metal ions in solution and on the exchange sites of smectite clays are known to act as Lewis acids. Recent work has determined that these ions can be titrated with high-molecular-weight polymers. The relative acidity of the exchange ion and the basicity of the polymer determined by the new method give insight into the dewatering mechanism.

Jan 1, 1988

By R. H. Sailors

During the last 15 years, the North American Mining Industry has experienced increasing usage of cast high chromium white iron grinding media in wet grinding applications. First introduced into the cement industry (klinker grinding) where wear rate reductions of four or five times have been realized compared to steel balls, this same grinding media serve the iron, copper, and phosphate markets by resisting not only impacts and abrasion, but also corrosion which occurs in wet grinding. In these markets, single mills containing 250,000 kg of grinding balls are not un-common and hence the economic potential with respect to lower wear rates can be significant. Add to reduced wear rate the increased production efficiency that is possible and it is readily understood why much of the mining industry uses cast high chromium grinding media. Metallurgically, the alloys used consist of a martensitic matrix containing hard M7C3 eutectic carbides. Carbon (2.0 to 3.5%) and chromium (12 to 277.) are characteristically used to arrive at the desired properties.

Jan 1, 1989

By B. V. Knelson

Although the concept of centrifugal recovery has been around in one form or another for many years, it has not been until recent times that it has became clearly understood am properly put into perspective. Simplistic in theory, it is when one begins to examine the variables involved that the true complexities of this matter begin to emerge. In creating an enhanced g force concentrator, there are many aspects both positive and negative that are encountered.

Jan 1, 1989

By V. Karra

Based on extensive investigations on the effect of design variables on process performance, during 1982-85, Nordberg developed a 1000 hp cone crusher, with the objective of boosting crushing productivity in existing plants. The 2390 fits on the same foundation as the 7' SHD Symons cone, but is designed to give two times the capacity of the 7'. The economies of scale involved give the customer substantial cost savings. In this paper process performance of the Nordberg 2390 relative to the 7' SHD Symons cone, while crushing the same ore, will be presented. Also, implications of such a crusher scale-up to associated cost savings will be addressed.

Jan 1, 1988

The CERAMEC pressure filter is used for the filtration of fine materials whose cake moisture cannot be achieved with vacuum. Development work has been carried out to achieve a well-controlled cake forming and cleaning of the filter media as well as an efficient solids discharge system. Operating costs are low due to low energy input and negligible consumption of pressurized air.

Jan 1, 1999

By T. K. McMahon

Formally, a mathematical model could be defined as: A set of equations whose solution will approximate the response of a physical process or system to a set of stimuli which appear as parameters in the equations. The purpose of a mathematical model is to permit the rationalization of experience to proceed by simulation rather than by physical experimentation. In the application of digital computer control to an industrial process, the mathematical model of the process (subsequently called the process model) is needed to calculate the present process performance from the measured variables and to predict the response of the process to a control change. Functionally, the cardinal element in process model development is a concise set of control objectives. These, besides implicitly defining the boundaries of the system to be modeled, will determine the accuracy demanded of the model its nature: dynamic or steady-state, and so forth, The objectives should explicitly define what process efficiencies, production rates, qualities are to lie within the scope of the computer control project, thereby providing a basis for simplifying assumptions in the development of the model. This requirement, a limited set of control objectives, is so often disregarded in formulating industrial control problems that its repetition can scarcely be avoided.

Jan 1, 1965

By Richard J. Ebens

The trace element geochemistry of the cherty, clay-rich carbonate residuum. Covering much of southern Missouri and adjacent parts of Arkansas was investigated during the early 1970's as part of a statewide geochemical survey of Missouri-1/2/3 The study was environmentally oriented and focused on the character of the "natural' geochemical environment of the state. A great deal of effort was made to collect samples that would represent the geochemical variability of the near-surface environment in an unbiased way. In general, this was accomplished by use of randomization procedures in both collection and analysis. Most of the sampling sites were selected randomly to prevent personal bias from entering into sample selection. In the laboratory, samples were analyzed in a randomized sequence to circumvent the effects of any systematic bias that may have entered into the laboratory procedures. Several residuum samples contained 1 000 parts per million (ppm) or more of Pb, Zn and Ba. All these samples were collected in Washington County in or near the barite district. The frequency distributions shown in figure 1 indicate just how unusual the residuum in Washington County is with regard to these three metals and copper. The shaded parts of the histograms represent the samples from Washington County. The histograms are based on analyses of 141 samples from 38 localities scattered over the subcrop of the Cambrian and Ordovician Formations of southern Missouri and northern Arkansas. Eight localities were selected randomly from over each of four bedrock units--Bonneterre Dolomite, Potosi and Eminence Dolomites, Roubidoux Formation, and the Jefferson City, Powell and Cotter Dolomites. Six localities were selected randomly from over the Gasconade Dolomite. The geochemical "background" for these elements in residuum is defined by samples from outside of Washington County (unshaded part of the histogram); lognormal distribution curves have been fitted to the corresponding parts of each histogram. Clearly, these lognormal models (curves) describe well the background

Jan 1, 1977

By Jonathan K. Hrica, CASSANDRA L. HOEBBEL, Jennica L. Bellanca

Accidents involving powered haulage and mobile equipment like haul trucks are a major safety concern in the U.S. mining industry. They account for more than 50 percent of surface mine fatalities each year [1]. A recent National Institute for Occupational Safety and Health (NIOSH) analysis of 91 fatal incidents identified loss of vehicle control and situational awareness as key contributors [2]. However, the first-hand perspectives of operators are often missing, emphasizing the need for deeper insights into operators’ decisionmaking, lessons learned, sensory cues and mental strategies used during near-miss events. The findings in this analysis will help inform the development of training and safety solutions to prevent or reduce haul truck accidents.

May 1, 2025

By F. E. Kottlowski

Widespread high-calcium limestones in New Mexico region are low -in magnesium, but some units include shale interbeds deleterious for sulfur removal usage. Thick limestones in Mississippian Escabrosa, Lake Valley, and Leadville, Pennsylvanian Madera and Hermosa, Pennsylvanian-Permian Horquilla, Permian Hueco and Capitan, Cretaceous U-Bar, and some Cenozoic travertines are high-calcium units. Significant outcrops are in mountains of southwestern, south-central, central, southeastern and north-central New Mexico, southeastern Arizona, southwestern Colorado, and northwestern Chihuahua. Coal-fired powerplants are mainly in northwestern New Mexico and eastern Arizona, thus transport is mainly by railroad.

Jan 1, 1994

By Gregor de Ratmiroff

Field prospecting for bauxite in Venezuela has had a long but interrupted history having till now oferred but evidence of occurrences. The Venezuelan Government, trough the Corporación Venezolana de Guayana (C.V.G.), in 1974, formalized a major effort in prospection for bauxite in the Shield area and the Orinoco Delta in orden to establish the possibility of raw material supply to an upcoming and expanding aluminium industry. The Corporation, in turn, created and delegated to the Division of Geological Stu- dies, the formulation of the necessary infrastructure and execution of work in orden to determine the existence of economically exploitable bauxite deposits.

Jan 1, 1979

By D. C. Shumway

Mining in Cushenbury Canyon began in 1860 when John Cushenbury left his Holcomb Valley gold prospect and discovered a silver vein in the limestones of the present day Cushenbury Mine. Cushenbury Canyon is located along the western boundary of the Mojave Desert in Southern California and on the north slope of the San Bernardino Mountains. The Holcomb Valley, immediately southeast of Cushenbury Canyon was the most prolific gold producer in Southern California. Gold mining dominated the area until World War II when interest in the Lucerne Valley Limestone deposits was peaked by the construction of the Kaiser Steel Plant in Fontana, California. The steel making process required large amounts of metallurgical grade limestone and Kaiser geologists located claims in most of the limestone deposits. Kaiser Cement constructed a cement plant and limestone mine in Cushenbury Canyon in 1956. Kaiser Cement modernized the facility in 1982 to a four stage preheater-precalciner system. Mitsubishi Cement Corp. purchased the property in April, 1988, and through further system modifications have created the most efficient and modern cement plant in the United States.

Jan 1, 1992