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By S. C. A. Franca, M. T. Millqvist, A. B. Luz

Laboratory experiments were performed on a Brazilian diatomite from Bahia State to produce an industrial product for use as a filter aid. Bench and pilot plant tests were conducted consisting of: diatomite desegregation, organic matter and clay removal, filtration, drying and calcination. Calcination temperature and sodium carbonate addition influenced diatomite particle size distribution. Optimum filtration rates for calcined products were obtained at 900°C and 47 min. residence time with 3% (w/w) of sodium carbonate addition, and resultant products met specifications imposed on filter aids.

Jan 1, 2002

By S. Underwood

The tracer gas method of conducting ventilation surveys is a means of determining air quantity in underground mines with knowledge of the concentration of the tracer in the atmosphere and the flow rate at which the tracer is being released. The technique is useful in inaccessible areas of underground mines and areas where traditional point measurement of velocity is not practical. Sulfur hexafluoride (SF6) is the industry standard tracer(Kennedy 1987) used in underground mines because it is safe, stable, and not naturally occurring in the mine environment. The implementation of a second tracer will increase the versatility of the tracer gas technique allowing for simultaneous releases for the study of interrelated ventilation circuits, and for conducting multiple experiments in less time. This paper will detail the selection of perfluoromethylcyclohexane (PMCH) as a novel tracer with sensitivity, physical properties, and analysis characteristics similar to SF6. Methods for the release of liquid PMCH into underground mines will be recommended, and the vulnerabilities of sample loss due to condensation of vapor PMCH will be explored. Finally, the benefits and implications of using PMCH as a second tracer will be discussed.

Jan 1, 2012

By A. Supomo, A. Partanen, M. Mular

Although many SAG operators may agree that on-line measurement of SAG feed-size is an attractive notion, applying this information in a control strategy that recovers the investment, engineering time, and maintenance is not necessarily straightforward. The P. T. Freeport Split-Online system was justified based on the assumption that SAG feed-size could be used in a feed-forward control strategy either at the regulatory or expert system control level. Something like “as the feed size changes adjust the throughput to avoid under or overloading the mill” was envisioned. However, following installation and calibration, Cluster Analysis showed that such an approach would not be successful. However, the sensor has been successfully integrated into Freeport’s grinding control strategy other ways. It provides an input to the Kalman filter parameter estimator used in a model-based control strategy that optimizes throughput and grind. The Split sensor also provides a characteristic feed size parameter for use in an on-line work index estimator. This paper describes the calibration and installation of the Split SAG feed-size analyzer, and reviews the evolution of its use in the Freeport C3 grinding circuit control strategy.

Jan 1, 2001

By M. H. Weinecke, B. P. Faulkner

This paper will discuss the process for making lightweight aggregate, the waste materials that make good lightweight aggregate, the chemistry of making lightweight aggregate and finally a discussion of the commercial prospects for making lightweight aggregate from wastes. Svedala Industries has been making lightweight aggregate (LWA) from waste materials for the last ten years. Many clay-like materials, such as coal-fired boiler ash and washings from a granite quarry, can be used alone or with additional waste materials to produce a commercially saleable LWA.

Jan 1, 2001

By B. J. Sauer

Variable frequency drives (VFD’s), or adjustable frequency controls (AFC’s) as they are more precisely identified, have been available to the mining industry for over 20 years. However, in recent years as the push to cut production costs has become ever so crucial, AFC usage has become more widespread. This paper seeks to provide professionals in mineral processing plant design and operation with an introduction to AFC’s, insight as to why AFC control for AC induction motors can be advantageous, and specification and design considerations.

Jan 1, 2002

By Ray Brainard

The subsurface investigation for the Reach 4 Tunnel was expected to be completed in a single phase. This assumed that data from two nearby previous tunnels, combined with limited new subsurface information and surface mapping would be sufficient to characterize the rock behavior. Unforeseen rock conditions and complex faulting led to the recommendation for a second phase. This decision was not reached easily, as much of the follow-on work required helicopter support, and associated costs. The second phase of drilling found significantly more variability than the first phase and led to a very different and better understanding of the geologic and geotechnical conditions, and rock characterization.

By J. D. Miller, R. J. Smith

Earl C. Herkenhoff Publication of the article "The Flotation Behavior of Digested Asphalt Ridge Tar Sands" by R.J. Smith and J.D. Miller has confirmed and again spotlighted a most significant and important development in the field of tar sand and heavy oil mining. This is the ability to recover 95 % of the bitumen in dry tar sands by a hot water process. The initial investigation by Miller and Sepulveda in early 1978, "Separation of Bitumen from Dry Tar Sands," was the first blockbuter. It is disappointing that there has been so little scientific and industry ackowledgement that the authors laid to rest the long entrenched belief that the sand grains had to be "water wetted" for a hot water process to be applicable. Dr. Miller and his researchers at the University of Utah used slightly different mineral dressing terminology in describing their process but it is essentially the old, established technique of high solids attrition scrubbing at elevated temperatures with a conditioner or modifier, followed by dilution and froth flotation. Similar techniques were described in detail for other nonmetallic minerals in the mid-1940s by Stuart Falconer of American Cyanamid Co. The authors used a 15-minute "scrub" period (or in their terminology "digester step") at 73% solids and 95°C (203°F) in a 0.3 m solution of sodium carbonate -about 4 kg/t (8 lb per st) of tar sand. Flotation was at 10% solids. Obviously, the scrub is an expensive step with respect to energy input but the high recovery of bitumen appears to justify it. Two basic questions then arise: • What are the effects of shorter scrubbing time, lower temperature, and less sodium carbonate? • Would a two-stage approach be advantageous? That is, could you get the major proportion of the bitumen with a mild scrub and apply the high power and temperature only to the refractory portion? These variables should be evaluated. Apparently, all results were only for rougher flotation. What would the grade and recovery of bitumen be if multiple cleaner flotation steps were employed? We must concede that a 60-62% grade of bitumen leaves considerable room for upgrading. Finally, it should be noted by all executives who approve funds for heavy oil recovery schemes, most of which are variations of in-situ methods, that mining can yield a 95% recovery of bitumen. That is correct, 95%. Imagine what that does to the total barrels recovered from a heavy oil resource compared with the scrawny 30-35% maximum recovery we are getting now. The conclusion-let's mine heavy oil and tar sands. Reply by R.J. Smith and J.D. Miller We, too, share Mr. Herkenhoff s enthusiasm for the mining of tar sands-heavy oil and continue the development of related processing technology. Specifically, it will be noted that by appropriate control of bitumen viscosity in the feed (probably the most important variable for successful separation) the recovery can be accomplished at low digestion temperature and low addition of alkali. A 91 t/d (100 stpd) pilot plant based on our technology is now being operated by Enercor in Salt Lake City (Hatfield, Oblad, and Miller, 1982). In these same pilot facilities, rougher concentrates containing more than 80% bitumen on a dry basis are being produced from Asphalt Ridge Feed. However, the processing of certain other tar sands results in incomplete digestion of bitumen/sand aggregates as discussed elsewhere (Miller and Misra, 1982). Such undigested aggregates are shown in Fig. 1. In this regard, it is intended that a recycle stream will be installed in the pilot plant to provide for redigestion of middling products. Further details regarding surface chemistry aspects of this tar sand technology have recently been published (Misra, Aguilar, and Miller, 1981). References Hatfield, K.E., Oblad, A.G., and Miller, J.D., 1982, "Pilot Plant Recovery of Bitumen from Oil Wet Tar Sands," Processing, Second International Conference on Heavy Crude and Tar Sands, Caracas, Venezuela, Feb. 7-17. Hatfield, K.E., Oblad, A.G., and Miller, J.D., 1982, "Pilot Plant Processing of Oil-Wet Tar Sands," Symposium, Rocky Mountain Fuel Society, Salt Lake City, Utah, Feb. 18-19. Miller, J.D. and Misra, M. 1982, "Hot Water Process Development for Utah Tar Sands," Fuel Processing Technology, Vol. 6, No. 1, April, pp. 27-49. Misra, M., Aguilar, R., and Miller, J.D., 1981, "Surface Chemistry Features in the Hot Water Processing of Utah Tar Sand, Proceedings, "Symposium of Separation Science and Technology for Energy Applications," Gatlinburg, Tennessee, May 5-8.

Jan 11, 1982

By Magno Rodrigues Ribeiro, Alexandre Cabral Stelzer, Cacio José da Silva, Leonardo Nogueira Ferri, Marcelo Ciminelli Mendes, Christophe Bouché, Marco Aurélio Soares Martins, Evenilson Soprani Lopes, José Xavier da Silva Filho, Sérgio Luiz Dalvi

Since 2001, CVRD is carrying out a modernization project in it’s pelletizing plant’s automation systems, that comprehends instrumentation, control and information systems. In addition, the project includes implementation of advanced control systems, using artificial intelligence techniques, including fuzzy logic, expert systems and dynamic physical models, to increase production, reduce fuel and energy consumption and improve quality. This paper reports CVRD’s experiences in carrying out an optimization project.

Jan 1, 2005

By Charles T. Steuart

The Arkansas Novaculite of Devonian and Mississippian age is the most distinctive formation in the central Ouachita Mountains of Arkansas from the standpoint of both topography and lithology. The formation typically forms precipitous, narrow ridges (hogbacks) which reflect the steepness of dip and the resistance and thickness of the rock units. The Arkansas Novaculite varies from less than 200 feet thick in the north to locally over 800 feet thick in the south and outcrops over an east-west distance of 360 km (200 miles) in the Ouachita Mountains of Arkansas and Oklahoma. Most of the rocks of the formation are highly siliceous with novaculite predominating, and lesser quantities of chert, siliceous shale, conglomerate and rarely sandstone. Novaculite is commonly defined as a homogeneous mostly white rock, translucent on thin edges with a dull to waxy luster and composed almost entirely of microcrystalline quartz. The word novaculite comes from the Latin word novacula, meaning razor hone. This term was first used by Richard Kirwan in his mineralogy text of 1784. The origin of novaculite remains controversial but we believe it was a primary silica derived mostly from the alteration of submarine volcanic-rich materials, with numerous fine biogenic components and some minor clastics (derived mostly from foreland facies via turbidity currents) and deposited as an amorphous siliceous ooze in the deep Ouachita trough. It was subsequently converted to microcrystalline quartz during diagenesis by the compaction of the overlying rocks and the intense Late Paleozoic Ouachita Mountain tectonism. In the central and southern portions of the region three divisions of the formation have been defined: a Lower Division predominantly of light-colored novaculite; a Middle Division of interbedded dark chert and shale; and an Upper Division of massive often calcareous novaculite. In the northern exposures the formation is thinner and contains more black chert and shale, chert-shale conglom¬erate, sandstone and less novaculite. The massive novaculite of the Upper and Lower Divisions is a source of high purity silica (99+%). Indians were the first to use novaculite. They made their various tools and hunting implements from the weathered broken rock until they learned the quarrying techniques. The first white men in the area recognized the use of novaculite for sharpening their tools and knives: previously whetstones were obtained in small quantities from Europe. To this day whetstone is quarried mostly in areas which the Indians and possibly the Spanish previously worked. Some of the current mining practices have changed very little from those of the early quarryman. In areas where the novaculite of the Upper Division is poorly cemented, this friable tripolitic material has found applications in such uses as an abrasive, as a filler or extender in paints, plastics and other purposes. Some of the dense novaculite is suitable as a filler in fire bricks and also in plastics. Because some of it has the tendency to decrepitate when heated not all novaculite can be used for these applications. Several quarry operators are crushing novaculite for road, concrete, and other aggregate. This use was formerly rather limited due to the abrasiveness of the novaculite on crushing and screening equipment. Further potential uses of novaculite are speculative but include application of high purity silica in the production of silicon metal for solar cells, seed or "growing", and fusing quartz for electronics.

Jan 1, 1985

By S. Ersayin, I. Iwasaki

Application of a magnetic field was shown to be effective in controlling iron losses in pilot-scale cationic silica flotation in the processing of magnetic taconite concentrates. The design of a magnetic field distribution device and batch flotation test results using a 1.42m3 (50 cu. ft.) WEMCO cell are reported. Major losses of iron units in froth products were in the -25µm (500 mesh) fraction, and the application of a magnetic field decreased the flotation of fine magnetite, thereby improving the selectivity of separation. The “as received” sample was sufficiently magnetized and no further benefit was gained by magnetizing treatment. Selectivity was somewhat adversely affected by demagnetizing the sample, though its effect was minimal due to the magnetic field. The device is simple in construction, low cost and may be installed readily in existing equipment.

Jan 1, 2002

By S. Brummelkamp, G. Van Weert

Separation of minerals by shape has received little attention, since minerals normally do not break into different shapes during crushing and grinding. However, comminution of consumer wastes generates opportunities for novel separations based on particle shape. For instance, ductile plastics are broken into longer curved shapes, whereas brittle plastics yield angular particles. Using spouting beds for particle separation in water requires controlling the spout's instability. The preferred geometry for such redesigned spouting beds is reported. Plastic cylinders, discs and spheres were separated as a function of rising water velocity and amount of particles in the system. By using 5 mm particles, differences in settling behavior could be video recorded.

Jan 1, 1999

By J. Chilton

The fact that methane ignitions continue to occur at the mining face indicates that monitoring with machine-mounted methanometers does not always indicate the presence of high methane concentrations. Methane concentrations at the face change quickly due to changes in airflow. By measuring these changes in airflow, it may be possible to predict changes in face methane levels more quickly. Currently there are no techniques or instruments to accurately measure airflow inby the mouth of the ventilation curtain or tubing. Tests conducted in the NIOSH ventilation test gallery compare the data provided by one-, two-, and three-axis ultrasonic anemometers. The effects of changes in airflow direction and turbulence on instrument readings are discussed, and guidelines are given for selecting the type of instruments to be used for monitoring airflow near the mining face.

Jan 1, 2007

By K. A. Stanley, N. A. Karl, D. R. Wilburn

"This summary of international mineral exploration activities for the year 2014 draws upon information from industry sources, published literature and specialists in the U.S. Geological Survey (USGS) National Minerals Information Center. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry and presents analyses of exploration activities performed by the mineral industry.Three types of information are reported and analyzed in this annual review of international exploration: 1) budgetary statistics expressed in U.S. current dollars provided by SNL Metals & Mining (SNL) of Charlottesville, VA; 2) regional and site-specific exploration activities that took place in 2014 as compiled by the USGS and 3) regional events that affected exploration activities including economic, social and political conditions, which were derived from published sources and discussions with USGS and industry specialists. Commodity and regional compilations are presented in this summary. Because multiple sources are used to develop these compilations, statistics may differ depending on the source and type of data that are being reported.The SNL data summarize planned company budgets for worldwide exploration activities in 2014 for 19 nonfuel mineral commodities based on company surveys. Research focused on precious metals (gold, platinum-group metals and silver), base metals (cobalt, copper, lead, molybdenum, nickel, tin and zinc), bulk commodities (iron ore, phosphate and potash), and specialty mineral commodities (diamond, lithium, niobium, rare-earth elements, tantalum and uranium). Information on uranium exploration activities was included for the first time in 2007. Data on lithium, niobium, phosphate, potash, rare-earth elements and tantalum were compiled for the first time in 2010 because of their increased significance. Since 1999, companies with exploration budgets of $100,000 and greater were included in the SNL compilations. SNL budget estimates exclude bauxite, coal and oil and gas. Exploration budget estimates for iron ore have been compiled since 2011 but reported separately. The 2014 SNL company survey is reported by SNL to cover an estimated 95 percent of the world’s nonferrous, nonfuel mineral exploration budgets. The 5 percent that is not covered includes companies that chose not to participate in the SNL survey, private companies that do not publish their budget data, and government-funded exploration activities"

Jan 1, 2014

By Steven W. Hunt, Safdar A. Gill

Design and construction of temporary shafts for underground facilities often require evaluation of bottom stability due to rupture (blow-ins) caused by water pressure acting on a bottom plug. This paper provides an overview of shaft bottom stability evaluation methods for the case of a relatively watertight soil plug which overlies an artesian aquifer. Methods of considering plug perimeter shear, plug buckling and pressure relief are discussed. Minimum factors of safety are suggested. Future use of the shaft subgrade is also considered. Bottom plug failure case histories at several shafts are evaluated. This paper should be useful to project designers, ground support system design engineers and contractors involved with construction of shafts for underground facilities

Jan 1, 1997

By M. Frenzel, D. Ebert, K. Bachmann, A. D. Renno, R. Möckel, J. Gutzmer, J. Krause

With the increasing demand for metalliferous and mineral raw materials and the consequent depletion of the global natural resource base, the possible utilization of secondary raw material sources is receiving more and more attention. In the present study, we present results from a detailed vanadium deportment study of three basic oxygen furnace slag (BOS) samples known to containing elevated bulk concentrations of vanadium. Complementary analytical methods that were used to quantify the abundance and composition of V-containing phases include SEM-based automated mineralogy, X-ray fluorescence analysis, and X-ray powder diffraction as well as electron probe microanalysis. The vanadium deportment was quantified using Monte-Carlo simulations of the data obtained from automated mineralogy and electron microprobe analysis. The total V concentrations identified by XRF are between 1.7 and 2.2 wt.% V. The most important hosts of vanadium are larnite-, brownmillerite- and portlandite-solid solutions. In two samples Ca carbonates also significantly contribute to the V deportment, while wuestite, lime, and native iron do not contribute significantly to the vanadium deportment. A thorough consistency check identifies considerable uncertainties in the density of the V-bearing phases as the most likely reason to explain remaining discrepancies between measured and calculated V values.

Oct 14, 2023

By Leonel Lopez

Throughout Mexican history, mining has been an important, traditional activity. Before the "Discovery of America," native miners worked a variety of deposits throughout the country, including Mixtec gold and gem mines in Oaxaca State and Aztec gold, silver and copper from mines in Michoacán. The 500th anniversary of Mining in Mexico after the "Discovery of America" was initiated by the Mexican mining sector on April 15, 1991. As early as 1548, when the Guanajuato mining district was discovered, Mexico had become a leading world producer of precious metals. Since then, Mexican mineral production has developed in cycles, responding to changing technological, economic and political conditions. During the 20th century, Mexican mine output reached its peak in the decades of the 1930s and 1940s, when it was producing about 40% of the world's silver, 15% of its lead, 10% of its zinc, 4% of its copper and 3.5% of its gold. In 1990, by way of contrast, these percentages of world output stood at 13.5% for silver, 4.7% for lead, 4.1% for zinc, 3.2% for copper, and 0.43% for gold. The lowest production levels were recorded during the 1960s and 1970s, when Mexicanization of the industry and increasing state controls weakened mineral economics to a point that mineral exploration budgets were sharply reduced or eliminated, along with the industry's future. Only the noble old mining districts continued to supply production, with occasional eruptions of "bonanzas" and new extensions in established mining districts.

Jan 1, 1994

By A. Zeni, S. L. Bessinger, T. A. Palm

San Juan Coal Company (SJCC) operates an underground coal mine near Farmington, New Mexico. Continuous miners and a longwall produce 7-8 million tons per year. The coal seam at SJCC has tested to have a propensity for spontaneous combustion. As such, during feasibility for this project, it was elected to utilize a bleederless ventilation system on the longwall. Three-entry gateroads are developed, and the longwall gob is sealed as mining progresses. SJCC utilizes a nitrogen injection system to continuously inertize the gob. In 2004, the mine was nearing completion of its first longwall district. The next district would contain longer panels (up to 12,500 feet). Due to the liberation of methane, and to a lesser extent hydrogen sulfide, a typical wrap-around ventilation system would not be appropriate. Not only would gas concentrations likely be challenging, but the overall ventilating pressure in the mine would have to be increased beyond limits established to mitigate the potential for spontaneous combustion. Given the above-described operating constraints, SJCC determined a need for a small ventilation shaft in the back (longwall setup area) of the next district that would draw adequate air past the longwall seals to maintain low gas levels and permit the required regulatory inspections to occur. Extensive ventilation modeling and gas desorption testing indicated that the shaft would be required to handle a volume of air ranging from 40,000 cfm to as high as 185,000 cfm. This large range is driven by the position of the longwall face with respect to the shaft and the effectiveness of the SJCC degasification program (SJCC uses vertical gob vent boreholes and horizontal in-seam methods). Ventilation simulations determined an appropriate diameter for the 350-ft-deep shaft to be 5 feet. Having determined shaft size, the next decision related to the method of shaft construction. Conventional shaft sinking was ruled out, due to the small diameter. Raise boring was an attractive option but had two drawbacks: (1) development crews would reach the bottom of the shaft just a few weeks before longwall startup, leaving a compressed timeframe to install the shaft, and (2) raiseboring requires additional underground entries to be developed to stow the project’s cuttings. While raiseboring remained a viable option, the problems associated with it led SJCC to also investigate blind drilling.

Jan 1, 2006

By Y. K. Yen, J. D. Miller, C. L. Lin

A PC image-based, on-line coarse particle size analysis system is being developed for the control of crushing and grinding circuits. Initial results had indicated that the system is accurate when tested with irregularly shaped particles which are stationary and do not overlap with each other. Now the system has been successfully tested in the dynamic mode with a moving belt conveyor. On-line size analysis for actual plant operations is discussed and includes: (1) the video system with respect to lighting and data acquisition requirements for a rapidly moving belt and, (2) image sampling, specifically the number of observations needed for accurate sampling and the total time required to perform the calculations for a representative data set.

Jan 1, 1993

By R. Hedin, M. Dunn

The Pennsylvania Department of Environmental Protection (US EPA 319 program) provided funding to aid a public-private effort in the installation of an environmentally-friendly system to treat abandoned mine drainage at Jennings Environmental Education Center (Pennsylvania Department of Conservation and Natural Resources). Through this cooperative effort among state and federal agencies, mining, excavation, and environmental companies, college and home school students, Girl Scouts, and volunteers, a successful multi-component passive system, readily accessible for upgrades and public education/research activities, was built. 90 people were directly involved in construction of this award-winning system and about 1000 people annually benefit from the educational opportunities.

Jan 1, 2002

By S. A. Diatchkov

There is a misconception that mineral-project economic evaluations in the former Soviet Union are either nonexistent or very limited. This is not the case. In fact, there are at least two basic methods that can be utilized to evaluate the vast mineral resources of the Commonwealth of Independent States (CIS). Evaluation procedures are based either on a comparison to known projects, which may rely on limited available data, or on potential-profit calculations, which generally uses more extensive databases. Significant philosophical differences between these systems and those utilized in the Western world include the following: •Under the centralized-government system, the economic evaluation of a mineral project was based on artificially determined mineral prices and costs. Every ten to 12 years, prices for concentrates and metals were established by the Council of Ministers and remained unchanged until the next reconsideration of prices .

Jan 1, 1995