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By Alan Rhodes

This study is initiated to investigate the efficiency of separation of mineral slimes using electroflotation as compared to that of column and conventional flotation techniques. Important parameters such as collector concentration, pH, current density, aeration rate, etc., have been studied. The results indicate that electroflotation can be used more efficiently in processing rutile slimes (10 µ) under certain operating conditions.

Jan 1, 1982

By Haydn H. Murray

This paper presents the results of test work performed with a Pacific Electric Motors (PEM) high intensity magnetic separator (20 kilogauss) , a unit capable of separating weakly, as well as strongly, magnetic minerals in the particle size range of sands to clays. Tests were performed on some 40 industrial minerals. With some minerals excellent separations were attained and with others intermediate and poor separations were accomplished. This study is a preliminary survey and many of the intermediate and poor results can be improved as separation problems are worked out with additional test work. It is demonstrated that with a number of industrial minerals high intensity magnetic separation is a viable beneficiation technique that is economic ally feasible.

Jan 1, 1976

By James S. Falcone

Soluble sodium silicate materials have well known applications in flotation for desliming, selective depression and corrosion control. Recent advances in the understanding of the complex polymeric nature of silicate solutions using NMR spectroscopy, combined with our studies of the effects of polymeric silicate anions on metal ion activities in solution, oxide mineral surface charges and surfactant adsorption on clays are related to beneficiation processes. The results of these studies indicate the sodium silicates can be used to cause a solution chemistry and particle surface charge characteristics favorable to enhanced effectiveness in typical ore beneficiation systems.

Jan 1, 1981

By Robert R. Unterberger

The purpose of this paper is to summarize the research of the past sixteen years on three distinct methods of probing into solid rock. The first method is to use radar of the appropriate frequency. The second method is to use sonar. The third method is of recent vintage and uses techniques of nonlinear sonar also known as parametric sonar. The first two concepts, that of radar and sonar, are common to most people. Very few have heard of nonlinear sonar. Each of the probing techniques were investigated in order to overcome deficiencies in the former technique. Each has its advantages and disadvantages. It should be emphasized that all of these techniques for probing (or seeing) into rock are used in mines, and generally speaking not from the surface. Only in very special cases, such as certain very dry parts of Egypt or Peru, or, for example, the surface of the moon, will these probing techniques work from the surface. The reason for the development of these probing techniques has been to alert miners to possible hazards ahead of mining. Such hazards may be (1) old (unknown) boreholes connected with high pressure water zones above, (2) fractures that might connect to the Gulf of Mexico above the mine, (3) water-filled fractures that threaten the safety of miners, or (4) the discovery of dry faults ahead that can disrupt the planning of future operations.

Jan 1, 1983

By C. L. Karr

Researchers at the University of Alabama are investigating artificial intelligence based computer models of mineral processing systems. Two approaches have been found to be particularly effective in developing data-driven computer models. The first approach employs neural networks which are computational paradigms based on the mechanics of the human brain. They are able to extract the basic relationships between input and output variables from large data sets. The second approach combines fuzzy mathematics with genetic algorithms to produce an adaptive modeling system. Fuzzy mathematics provide computers with the capability of manipulating abstract concepts like those which humans use so effectively in decision making. Genetic algorithms are search algorithms that mimic evolutionary processes apparent in nature. Together, these two techniques can be used to produce an effective modeling system. In this paper, the two approaches to modeling are compared and contrasted with respect to accuracy and computational time while used to model three mineral processing systems: (1) a grinding circuit, (2) a hydrocyclone separator, and (3) a flotation circuit.

Jan 1, 1997

By J. C. Haptonstall

Stoping methods at the Homestake Gold Mine through 1978 had been traditional overhand cut-and-fill, shrinkage or square set. High costs, low-productivity and safety concerns prompted the mine to search for and adopt a "bulk mining" technique as a primary stoping method. Blasthole stoping had been successful but it is very development intensive, and was not suitable for the mine's accelerated mining program. Vertical Crater Retreat stoping was selected, and today accounts for over 50% of ore production. Case histories representing both the successes and failures of VCR stoping in the mine are discussed.

Jan 1, 1986

By P. T. Bissert, J. P. Ducarme, J. L. Carr, A. K. Smith

The continuous mining machine is a key piece of equipment used in underground coal mining operations. Over the past several decades these machines have been involved in a number of mine worker fatalities. Proximity detection systems have been developed to avert hazards associated with operating continuous mining machines. Incorporating intelligent design into proximity detection systems allows workers greater freedom to position themselves to see visual cues or avoid other hazards such as haulage equipment or unsupported roof or ribs. However, intelligent systems must be as safe as conventional proximity detection systems. An evaluation of the 39 fatal accidents for which the Mine Safety and Health Administration has published fatality investigation reports was conducted to determine whether the accident may have been prevented by conventional or intelligent proximity. Multiple zone configurations for the intelligent systems were studied to determine how system performance might be affected by the zone configuration. Researchers found that 32 of the 39 fatalities, or 82 percent, may have been prevented by both conventional and intelligent proximity systems. These results indicate that, by properly configuring the zones of an intelligent proximity detection system, equivalent protection to a conventional system is possible.

Jan 1, 2016

By D. S. Yantek, L. A. Alcorn, M. J. Lowe, H. E. Camargo

U.S. National Institute for Occupational Safety and Health (NIOSH) studies show that 43.5% of surveyed coal preparation plant workers had noise exposures exceeding the U.S. Mine Safety and Health Administration permissible exposure level of 90 dB(A). Sound levels around vibrating screens in these plants often exceed 90 dB(A). NIOSH is currently developing noise controls for horizontal vibrating screens. To characterize noise sources, NIOSH researchers performed sound pressure level (SPL) measurements on a vibrating screen at their Office of Mine Safety and Health Research laboratory in Pittsburgh. The results show that the entire screen contributes to noise below 1 kHz, and the vibration mechanism housings are most significant above 1 kHz. Constrained layer damping (CLD) treatments and an enclosure were used to reduce mechanism housing noise in this range from 1-10 kHz. These were evaluated using sound power level measurements according to ISO 3744. The CLD treatments reduced the A-weighted sound power level by 3.1 dB in the 1 to 10 kHz one-third-octave bands. A panel-on-frame vibration mechanism enclosure using various types of panels further reduced the A-weighted sound power level from the CLD configuration in the 1 to 10 kHz one-third-octave bands by 3.7, 4.0, and 3.9 dB for aluminum, steel, and Dynalam™ panels, respectively. The combination yielded a 7 dB reduction from baseline in A-weighted sound power for the same frequency range.

Jan 1, 2011

By James A. Decker

Hanna has developed three production planning systems to help the mine engineers determine the sequence of mining from available ore supples. The Production Scheduling System was developed to give the staff a tool for long range planning by sequencing the removal of blocks from an open pit property. It was needed to determine the year of removal for each block so that the optimum present-valued pit limits could be established by our pit design program. Since in this type of planning short term grade control is less of a factor than it is in daily or monthly planning, the system gives the program greater control and more latitude in block selection. It permits only full blocks to be taken.

Jan 1, 1984

By R. V. Ramani

In this paper, the application of the concepts of reliability engineering to the evaluation of longwall system performance is illustrated with data from an operating longwall face. A number of cases are analyzed to highlight the impacts of longwall equipment, geological conditions and outby haulage on systems reliability and availability.

Jan 1, 1988

By J. R. Carr

A crucial concern when implementing computer algorithms for geostatistical analyses on microcomputers is speed of execution. Kriging, in particular, typically relies on a Gauss elimination algorithm to solve for weights. Because such an algorithm is required for each estimate, the solution for weights can result in very slow program execution speed on a microcomputer. One approach to enhancing the efficiency of Gauss elimination is demonstrated herein. The upper triangle plus diagonal of the intersample covariance matrix is used in a modified banded Gauss elimination algorithm. Results show that such an algorithm yields approximately a two-fold reduction in execution time for kriging when the number of nearest neighbors used for estimation is large.

Jan 1, 1990

By M. J. Zdunczyk

The final 1995 figures on industrial sand and gravel have not yet been compiled by the US Geological Survey (USGS). There is usually about a nine-month lag time in receiving and compiling this information. However, USGS estimates that domestic production of industrial sand and gravel will increase about 4% to 28.2 Mt(31 million st). The average unit price is expected to increase as well. The top five producers during 1995 were Unimin, US Silica, Fairmount Minerals, Oglebay Norton and Morie Co. Glass manufacturing for containers, automobiles and buildings was mixed during 1995. Containers, the largest consumer of silica sand, remained steady, with regional increases. However, silica use in glass containers face increased competition from plastic and recycled glass (cullet). It was reported that the Pepsi Cola announced plans to replace glass containers with plastic during 1996.

Jan 1, 1996

By Remi Tremblay

This paper describes the laboratory study which permitted an exploration of high grinding ball consumption in the secondary open circuit wet grinding mills at the Sidbec-Normines plant, Port Cartier, Québec. Corrosion undoubtedly exists but is of minor importance. Abrasion resulting from the physical nature of the company's iron concentrate is the main reason for the high ball wear. It was found that at least 30% reduction in ball consumption is possible by decreasing attrition grinding through the use of lifters in the mill. At the industrial level this would entail more lifters and/or higher lifters in the mill linings.

Jan 1, 1984

By W. C. Shanks

The Pioche District of Lincoln County in southeastern Nevada (Figures 1 and 2) has been an historically important producer of silver, zinc, and lead. Economic geology of districts in the Pioche area is summarized most adequately in recent reports by Tschanz and Pampeyan (1) and Gemmill (2) and only a few major aspects will be discussed here. Production in the Pioche District began in 1869 and early mining concentrated on silver-bearing fissures in lower Cambrian quartzites. In the early 1870's the Pioche District was second only to the Comstock Lode in world silver production (3). More recent mining activities have centered on the other major ore type in the area, bedded replacement of lower Cambrian carbonates by Ag-Zn-Pb sulfide ore. Production of replacement ore peaked around 1950. The present study is focused on the Pan American Mine because it is an excellent example of low grade carbonate replacement deposits, because there is little structural dismemberment, and because access was readily available. Most previous workers have suggested that both the fissure vein deposits and the bedded replacement deposits of the Pioche districts are a result of spatially related Laramide igneous activity. The purpose of this study is to determine whether ore genesis is a result of igneous activity or if mineralization might be related to late diagenetic processes such as formed Mississippi Valley "type" deposits. Stable isotopes of sulfur, carbon, and oxygen in ore and gangue minerals have been studied to determine the probable isotopic composition of the ore fluid and paleomagnetic studies of the carbonate rocks have been utilized to determine timing of mineralization. Additionally, petrographic and field studies of carbonate lithologies were undertaken in an attempt to delineate non-structural controls on ore localization. These studies are still proceeding and the results presented herein are, therefore, preliminary in nature.

Jan 1, 1979

By M. E. Kuchta

Surface coal mine design can be facilitated with the use of an interactive graphics personal computer program. This mineral inventory and planning program (POLY CALC) is described and its use is illustrated with a case study. The case study deals with investigating a stripping sequence and associated dragline stripping requirements.

Jan 1, 1986

By D. A. Meyer

The long and arduous process of bringing aggregate produced in Mexico to the Gulf Coast of the United States really began in the 1970s when the first exploratory trips were taken by Vulcan's geologists. It was not until the middle of the 1980s that all of the elements of the project seemed favorable and the largest capital investment in Vulcan's history was given the green light. The history of the project will be covered along with a discussion of the role that market forecasting played in the process. Is this the first of many or a once in a lifetime project? In July 1987, Vulcan and its joint venture partner broke ground in Mexico for a world-class limestone quarry and crushed stone production facility. This project is the largest ever undertaken by Vulcan's Construction Materials Group, with a total cost of over 200 million dollars -a cost shared equally by Vulcan and its joint venture partner, Ingenieros Civiles Associados, or ICA, a diversified Mexican company which is also the largest construction firm in Latin America.

Jan 1, 1995

By Vladimir Adamek

Due to the variability of subsidence characteristics across the U.S. coalfields, it was concluded that it would be practically impossible to develop a universal predictive model for mining-induced subsidence based on theoretical assumptions. Therefore, an effort was made to find a procedure to develop an empirical subsidence predictive model based on a sufficient Mount of field data from one mining area (in this case the Northern Appalachian Coal Region). It was also thought that this procedure, if successful, could be used as the template for developing predictive capabilities for other coalfields with different subsidence characteristics given a reasonable amount of field data. It has been found, in the Northern Appalachian Coal Region, that the variability of subsidence characteristics can be expressed by a polynomial equation developed through regression analysis of the variable subsidence coefficient and derived directly from the field data. In this study, field data were obtained from 11 Bureau longwall panel studies (16 half profiles) for static subsidence and 14 panels for dynamic subsidence. The effects of lithology, expressed in the form of a variable subsidence coefficient, have been separated for each test site by introducing a correlation between hythetically homogeneous overburden and existing ithological conditions. For each longwall panel, the characteristic of the variable subsidence coefficient was defined along individual static profiles. The definition of mean values with acceptable deviations is the substance of the predictive method. The same procedure was used to develop a predictive model for dynamic subsidence, since it war discovered that the rate of longwall face advance is not a necessary functional parameter. This paper presents the theory, development, and application of the static and dynamic subsidence prediction models.

Jan 1, 1986

By G. V. Sullivan

As part of its program to conserve domestic mineral resources through advancing mineral resources technology, the U.S. Department of the Interior, Bureau of Mines, conducted investigations to determine the feasibility of recovering high-grade barite concentrates, suitable for use as well-drilling mud, from current and old waste pond materials and materials bypassed in present mining operations. Flotation studies of waste pond samples from Missouri and Nevada yielded barite concentrates containing over 95 percent BaSO4 with recoveries of 86 percent and 96 percent, respectively, of the barite in the flotation feed. Flotation studies of a hard-rock sample from Georgia, currently bypassed in mining, yielded a barite concentrate containing 97 percent BaSO4 with an attendant recovery of 97 percent of the barite.

Jan 1, 1980

By Kanaan Hanna

A joint research program between the U.S. Department of the Interior's Bureau of Mines and Cyprus-Yampa Valley Coal Company is being conducted at the Foidel Creek Mine, Oak Creek, Colorado. This program goal is to study the effects of state-of-the-art, high-speed, automated longwall mining on health and safety, and primarily, ground stability under various geological conditions. The Bureau installed an automated data monitoring system, known as the Ground Control Management System (GCMS), to monitor in real-time the effect of rapid mining on pillar and face loading, stress redistribution in and around the longwall panel, and caving characteristics of the roof. The Bureau's GCMS, combined with the company's existing monitoring systems, which include environmental monitoring, a computer programmable conveyor belt system, and gamma ray roof control thickness indicators, has been effectively used to improve safety at the face, increase productivity, and reduce production costs.

Jan 1, 1991

By James R. Craig

The Central and Southern Appalachians were the major sources of gold in the United States throughout the first half of the 19th century and have continued to yield gold to the present day. Small amounts of gold were probably extracted by the Indians and the Spaniards but the first documented report of gold in the region was made by Thomas Jefferson who found a four pound lump of gold ore, which yielded 0.85 troy oz., in the Rappahannock River of Virginia in 1782. Gold was subsequently discovered in North Carolina between 1793 and 1799, in Virginia in 1806, in South Carolina in 1827, in Georgia in 1829 and in Alabama about 1830 (Becker, 1894-5; Pardee and Park, 1948). The gold belts of the Central and Southern Appalachian Piedmont and Blue Ridge Provinces are shown in Figure 1. The superimposed circles indicate the mount of production from some of the more productive and well known areas. Although North Carolina produced far more gold than the other states, the most significant concentrated area of production is the Dahlonega District in Georgia which yielded more than 500,000 troy ounces. After discovery, gold production increased rapidly as shown in Figure 2. Production was at its maximum between 1830 and 1852 with combined totals generally exceeding 30,000 troy ounces per year. Production dropped sharply after the California gold rush in 1849 as experienced miners moved westward in search of bigger and easier stakes. After the Civil War briefly halted gold mining in the Appalachians, production rose to an average of about 8,000 ounces per year from 1865 until 1878 and to an average of about 13,000 ounces per year from 1881 until 1915 when it again fell to near nil (Pardee and Park, 1948). Minor resurgences occurred in the 1930's and 1940's. Although there has been no reported production in recent years, it is likely that "weekend panners" still remove hundreds of ounces from streams annually. The total reported production for the area through 1959 is in excess of 2.5 million troy ounces.

Jan 1, 1981