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By M. Gunter, M. Buzon

"Talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic, and lacking in amphiboles. In southwest Montana, talc formed from hydrothermally altered dolomitic marbles, and is still actively mined. These talc deposits are typically in contact with quartzofeldspathic gneiss and marble. Accessory minerals vary between these rocks and the ore producing body; the identification and characterization of such minerals requires carefully selected analytical methods. Recent litigation and ensuing confusion over the petrology and asbestos content of these deposits challenges the talc mining industry in Montana, and elsewhere in the world. INTRODUCTION Commercial talc has been mined from the deposits in southwest Montana since the 1940s, and by 1956 the region had output 200,000 tons of talc ore (Chidester et al., 1964). Commercial talc refers to rocks containing more than 20% of the mineral talc (McCarthy et al., 2006); the ores from Montana typically contain upwards of 90% talc. This region remains the leading domestic source of talc in the U.S. partly due to the reserves in the area, and partly due to the diagnostic purity of the ore compared to that of other regions, some of which are no longer actively mined. The mineral talc, a sheet silicate, is expressed by the formula Mg3Si4O10(OH)2, and therefore can form in geologic environments that are rich in Mg, Si, O and water. The protolith for the talc deposits in southwest Montana is a dolomitic marble, but other common protoliths include ultramafic igneous, mafic igneous, and siliceous dolomites (McCarthy et al., 2006). Physical properties such as hardness of 1 on Mohs hardness scale, white streak and slippery feel are among some of the reasons why talc is so widely used as fillers in a number of industries. In decreasing order, ceramics, paper, paint, roofing, plastics, rubber, and cosmetics are the leading domestic industries that use talc despite the decreasing trend in U.S. talc use and production since 1994 (Virta, 2015). The purpose of this paper is to describe the mechanism of talc formation in southwest Montana by focusing on talc deposits and surrounding rocks in the Ruby, Greenhorn, and the Gravelly Ranges, and to relate the mechanism of formation to the composition of talc ores. The compositional data show mineral content of selected ores, and the major and trace element content of those minerals, specifically talc. Our electron microprobe (EPMA), powder x-ray diffraction (XRD) and x-ray fluorescence data for samples from five mines in these three ranges provide continued evidence of the purity of these ores despite claims made during recent litigation that these ores contain asbestos. The five mines that we discuss include the Beaverhead, Treasure, Regal, Willow Creek, and Yellowstone Mines (Figure 1.)"

Jan 1, 2016

By A. A. Jonke

The combustion of fossil fuels in a fluidized bed of calcined limestone particles is a potentially efficient and economically attractive process for the generation of steam for electric power production and other uses. The process results in greatly reduced emissions of both sulfur oxide and nitrogen oxide pollutants. Development work, evaluations and design studies are being carried out by various organizations under contract with the U. S. Environmental Protection Agency and the Dept. of Interior (Office of Coal Research). The AEC's Argonne National Laboratory is one of the principal participants in the development program under interagency agreements with EPA and OCR. This paper covers the principal reasons for developing fluidized-bed combustion, its advantages and disadvantages over conventional combustion methods, and some of the potential applications of the process. The participants in the multi-organizational program, the sponsoring agencies, the general status of development of the overall project, and the chief program areas that still require resolution are discussed. The main features of the program of work at Argonne National Laboratory and the results achieved so far are also included.

Jan 1, 1974

By D. Lelinski

Air-sparged hydrocyclone (ASH) flotation is one of the new promising technologies. Numerous applications have been successfully tested since its conception; nevertheless, research and development efforts have continued to provide for further improvements with respect to operating conditions and design considerations. Results from experimental studies on bubbles generation in the ASH system are presented in this paper. Bubble size distributions generated during ASH operation have been determined using a high-speed photographic technique. The influence of many factors including surfactant concentration, water flowrate, and porous tube pore size has been studied. Test results indicate that these process variables have a profound effect on the bubble size distribution. With an increase in surfactant concentration or water flowrate (shear field) the bubble size distributions become narrower and shift toward smaller average bubble diameters. However, the influence of pore size is more complicated. Depending on the experimental conditions the average bubble size was found to range from about 100 to 300 microns in diameter.

Jan 1, 1995

By Edward T. Koch

With the dramatic increase in world demand for basic raw materials, open pit mining is proceeding at an unprecedented rate. A viable demand is the ever tempting Siren's song for increased production or new facilities. When the Siren's lure is viewed against the panorama of today's world economic milieu the concomitant Scylla and Charybdis are seen in the form of high capital cost and high operating cost. If the economic realities of present day open pit mining are to show a proper return on investment, a clear and penetrating eye must be cast upon the area of mine planning. This paper deals with the problem of overburden removal. In almost every open pit mining operation overburden removal is a significant part of the capital cost and operating cost of the total operation. This paper deals with a new and unique method to affect economical overburden removal. Well known to all are the parameters surrounding draglines, shovels, and bucket wheel excavators. All of these machines require a reasonably stable soil to support them and the shovel and bucket wheel excavator require a reasonably stable bank in which to operate. Their reliability, portability and rate of production per dollar of invested capital are good.

Jan 1, 1975

By S. K. Kawatra, H. J. Haselhuhn

"Thickening is used during two primary mineral processing operations: water removal and desliming. During water removal, the pulp density is increased through the injection of flocculants. These flocs settle and create a dense pulp while clarified water is removed through the overflow. During desliming, fine particles are removed through the overflow. Desliming can also be used as a mineral separation process known as selective flocculation-dispersion, where valuable minerals are flocculated and gangue minerals remain dispersed and exit through the overflow.There are many ways to analyze thickener performance on a laboratory scale, but these analyses often do not correlate well with full-scale performance. Some pilot-scale systems have been designed using a semicontinuous approach, but the amount of material required to perform their tests can make semicontinuous pilot thickeners impractical for most applications. This paper focuses on the design and optimization of a continuous pilot-scale deslime thickener that requires minimal material to operate. The design, optimization strategy, and an example study of reagent selection are demonstrated. IntroductionMany laboratory methods have been employed to size and optimize thickener performance. The most common of these include the Coe and Clevenger method and methods derived from the Kynch theory of sedimentation. The Coe and Clevenger method was developed in 1916 and was proven for slurries that do not require flocculation to settle. This method proposed that the settling rate of the pulp is only a function of the solids concentration. It is executed by creating slurries of several different concentrations of solids and performing bench-scale settling tests in graduated cylinders. For each concentration, a thickener unit area can be determined using the following equation (Coe and Clevenger, 1916; Laros, Slottee and Baczek, 2002):"

Jan 1, 2017

By MOHAMMAD R. H. GORAKHKI, CHRISTOPHER BAREITHER, MANUEL APARICIO, IV JOSEPH SCALIA

Comingling filtered tailings and waste rock in a tailingsdominated mixture is a mine waste management strategy that has the potential to create geotechnically and geochemically stable landforms. Potentially acid-generating (PAG) waste rock can be sequestered within a filtered tailings matrix to enhance water retention and decrease hydraulic conductivity relative to a waste rock pile, potentially minimizing acid rock drainage (ARD). Enhanced water retention can reduce oxygen ingress limiting oxidation and resultant acid generation. Reduced hydraulic conductivity can slow inward percolation and outward drainage. In dry climates, the tailings matrix can hold precipitation near the ground surface accessible to evaporation and transpiration, thereby decreasing percolation. This paper presents an evaluation of comingled filtered tailings and waste rock in a tailings-dominated mixture (termed GeoWaste herein) and illustrates that ARD can be reduced under field conditions in a subtropical–highland climate.

By Leon J. Jacobs, Kyle R. Ott

This paper discusses design and construction aspects of the tunnel, shaft and station for the Weehawken Tunnel and Bergen line Avenue Station. The project consists of a 1,269 m (4,156 ft) long existing railroad tunnel, which will be enlarged and equipped with a two-track light rail system. The project also includes construction of a deep underground station, with a large shaft connecting the surface station to the below ground station for access and ventilation purposes. Vibration and noise from blasting is a critical community issue and blasting adjacent to two 230-kV duct banks located in the tunnel invert required special blasting procedures.

Jan 1, 2003

By Ronald A. Crowson

Detailed stratigraphic studies of the overburden at North Carolina Phosphate Corporation new South Creek Mine have delineated several aquifers and acquicludes within the 30-meter-thick overburden section of late Pleistocene sands and clayey sands. A major aquifer occurs in the 10-meter-thick sequence of shelly sands of the early Pleistocene Croatan Formation. The water-charged Croatan sands thicken into a paleodrainage surface on top of the Pliocene Yorktown Formation, a major aquiclude. A three-phase dewatering program is projected: 1) improve surface drainage around mine perimeter to reduce both flowage into the pit and rainfall recharge; 2) use a wellpoint system to dewater the upper 8 meters; and 3) use recharge wells along the axis of the paleo- drainage to dewater the overburden below 8 meters.

Jan 1, 1983

By L. G. Closs

Gold continued to be the primary focus of minerals exploration worldwide during 1995. Other targets, though, included primary diamonds and base metals, especially copper deposits amenable to solvent-extraction/electrowinning (SX/EW) processing. The discovery of nickel, copper and cobalt at Voisey Bay in Labrador, Canada was an unusual surprise. Meanwhile, exploration geochemistry continues to evolve to meet new challenges. The major event in this category during 1995 was the17th International Geochemical Exploration Symposium (IGES) held in Townsville, Queensland, Australia in May. The meeting was sponsored by the Association of Exploration Geochemists, which celebrated its 25thanniversary of service to the mineral industry, and the Economic Geology Research Unit of James Cook University, Townsville.

Jan 1, 1996

By L. B. Bramlett

The Archean (2.65 b.y.) aged Canning Stock at Copper Mountain, Wyoming contains an average of 20 ppm U. The North Canning and Fuller deposits occur within the enriched interior of the stock. Post-Laramide development of super gene enrichment blankets occurred in wide (25- 100 m) crushed zones. Hematite and chlorite accompany pyrite and sooty pitchblende in the mineralized zones. Reduction mechanisms proposed for deposition of pitchblende are: 1) sulfides, 2) hydrocarbons, 3) bacteria, 4) the water table, or 5) some combination of these. Abundant tar- type organics appear to have preserved the enrichment blankets from degradation. Trace element and radiometric data define target zones, but exploration models focus on favorable structure.

Jan 1, 1980

By William D. Mayercheck

The introduction of continuous mining machines in the late 1940's prompted the mining industry to reassess shuttle car batch-type haulage. Between place changes, the continuous miner could cut and load coal on a nearly continuous basis, but after loading a shuttle car, the high-capacity machine had to wait until the second shuttle car came inby and spotted itself under the miner tail boom. Thus, the wait-for-shuttle-car delay periods became the new bottleneck for increased coal production from the mine section. Recent studies have shown that nearly 25 pct of the continuous miner cycle time is consumed by delays in the haulage system, usually waiting for shuttle cars. Computer simulations of a face operation indicate that up to a 45 pct increase in coal production may be realized through the use of a continuous haulage system, assuming of course that the outby haulage system can handle this increased capacity. Coincidently, there are recent claims by some mines using continuous face haulage of a production increase of 45 pct compared with shuttle car haulage. These documented production records, computer simulations, and common sense indicate the potential of continuous face haulage in underground coal. The late 1960's and early 1970's saw several mining machinery manufacturers market mobile bridge carrier and piggyback bridge conveyor continuous haulage systems for use in underground coal mines. These systems have shown limited potential in some mines and outstanding success in others. It appears that no one system can be universally applicable to all underground mining conditions; thus, the Bureau of Mines has conducted extensive research over the last few years to investigate different types of continuous haulage systems for use in high and low coal seams that will advance the state of the art.

Jan 1, 1977

By Wilfred Walker

Much is known of the geography of the Alpine orogeny because it has now ended and all geosynclines are in their terminal, cordilleran form. The principle of sea floor spreading, continental drift, and mantle cells has gained general acceptance, but the number and position of the cells, even during the Alpine orogeny, is controversial. The oceanographers have demonstrated the uprises and in this paper it is suggested that downflows are marked by island arcs in the oceans and geosynclines (now cordillera) in the continents, for a total of about a dozen cells. Major mineral deposits associated-with the Alpine downflows are porphyry copper, molybdenum, nickel, chrome, lead-zinc-silver, gold, mercury, tungsten, and tin. Amore precise environment is known for some of these metals, for example, nickel, chrome, and mercury in flysch (which flanks mantle downturns), Ten major orogenies have taken place from 3500 m.y. to the present, Their re¬construction and metallogenesis is the subject of a continuing study.

Jan 1, 1971

By G. C. Allen

Selective flocculation is used for the purification of clay minerals. Here we present data from a surface spectroscopic investigation into the polyacrylamides mediated selective flocculation of kaolin from an impure matrix. Use of X-ray photoelectron spectroscopy (XPS) was shown to offer a useful approach for investigating the observed selective separations. In particular, a new small area XPS technique was used to characterize, in situ, the differential competitive, f1occulant adsorption onto mixed kaolin/gangue systems.

Jan 1, 1998

By John G. Hall

Everyone forms his own mental picture when the subject of copper is mentioned. To an architect, copper is a warm, enduring metal with a quiet beauty; to the historian, man's first metal; to the product engineer, the best electrical and thermal conductor of all commercial metals; to the investor, a volatile stock; to the speculator, the daily price quotation; to those in the mining industry, the challenge of producing copper for rising needs in the face of rising costs and lower grades of ore. At this meeting, we will look upon copper as a key raw material in industry, in national defense, in technology, in world trade, and as a principal commodity in the economies of several developing countries. As miners, and most of us here are miners, we are prone to view our role as suppliers of copper. We locate, mine, smelt and refine the metal. In the complexities of today's world, however, following a period of the longest domestic copper strike in history which caused critical world-wide shortages and widely fluctuating prices; it becomes necessary for all of us to concern ourselves with the whole spectrum of copper affairs -"from mine to consumer " But first we need to look at the miner's side of the picture -- capacity and production. We will examine these functions in terms of the whole world -- not simply the free world. Nature did not endow all regions of the earth equally, and copper in world trade has a way of ignoring political boundaries. Science and technology, as well, know no national boundaries. It is said that the "Engineering & Mining Journal" has as many readers in the Communist World as in the Free World. Nor is this a one-way street. We presently have available to us in the. U.S., cover-to-cover translations of many Communist World mining and metallurgical journals.

Jan 1, 1968

By Roberto Carranza

The planning of experiments and the importance of statistical interpretation of the results have been recognized for years by scientists and engineers. The Factorial Design of experiments is among the various methods used for this purpose and is being widely applied in all branches of research and production. The basic principles of this tool have been described in detail (1, 2, 3, 4) and several examples of its application in various fields have been published (5). In recent years the mineral industry has also used Factorial Design to improve the efficiency of research, testwork and plant operation (6, 7, 8, 9). This method permits for a qualitative determination of the influence of the variables studied in a process and also a qualitative measure of the interaction of the variables. By graphic means or derivative methods, one may also establish the optimum conditions of the process (ibid 7, 8, 9). It is desirable, however, to develop mathematical methods to evaluate quantitatively these effects and restrict the optimization to the practical limitations of the variables. It is also convenient to adopt a notation system to generalize the Factorial Design.

Jan 1, 1971

By James S. Browning

Mica mining in the United States is confined largely to pegmatites and schists in a few well-defined areas. The largest region extends from central Virginia southward through western North and South Carolina, northern Georgia, and east-central Alabama. 1, 2, 3 Whereas in western North Carolina these pegmatite dikes are weathered to only a shallow depth, they are deeply weathered in the Carolina Piedmont and in Georgia and Alabama. Particularly in Georgia and Alabama, mica is found in the decomposed slates and schists adjacent to the pegmatites, and in deeply weathered granites. Most flake mica is obtained as the major marketable product by crushing and milling pegmatites.4 To a lesser extent, mica is produced as a byproduct of feldspars and spodumene.6 Past research by the Bureau of Mines has developed two methods for mica flotation. One method utilizes acid-cationic flotation for recovery of mica." This method requires thorough desliming of the ore with consequent fine mica losses. The other method utilizes an alkaline-anionic-cationic process for recovering fine size mica from pegmatite ores after desliming sufficiently to remove clay materials but not so drastically as to remove the fine mica. 8, 9, 10, 11, 12, 13 The latter process has also been successfully applied to a micaceous schist ore from California.14 This report summarizes the results of these research studies. Both of the flotation processes developed by the Bureau of Mines have been adopted by the mica industry and are being commercially utilized separately and in combination for flotation of mica from weathered pegmatite ores.

Jan 1, 1969

By Kadri Dağdelen, Matthew Deutsch, Thys Johnson

Nested pit analysis in open-pit long range mine planning is used to define approximate ultimate pit limits and an initial high-level schedule in the early stages of a project. Modern ultimate pit optimizers can solve for dozens, or even hundreds, of nested pits however often a smaller subset of pits which are evenly spaced with respect to contained tonnage are desired for downstream analysis. In situations where that pushback selection process must be automated, such as when performing sensitivity analysis, or when the best subset of pushbacks is required; an optimization procedure is warranted. This paper describes a dynamic programming algorithm for selecting pushbacks following nested pit analysis, which is performant and addresses a long-standing inconvenience faced by long range open-pit mine planners.

Jun 25, 2023

By S. Usui

In a previous article1 the methyl stretching vibrations for a series of xanthates and amines were reported, and the frequency of the methyl stretching vibrations in a homologous series of the alkyl compounds were shown to decrease exponentially with chain length and approach a limiting value corresponding to that of saturated hydrocarbon beyond six or seven carbons. These observations were explained quantitatively by the theory of Goto and Takenaka2 who proposed an equation relating the frequency shifts to the inductive effect of polar groups. As a result, the alkyl groups in the shorter chain heteropolar compounds were interpreted as becoming somewhat polar, and a good correlation was observed between the CH3-stretching frequencies and such surface chemistry parameters as contact angle, surface tension lowering, solubility, and critical micelle concentration" The substitution of fluorine atoms, the most electronegative of all atoms, for the hydrogen atoms in alkyl groups was expected to reverse the direction of the inductive effect within a heteropolar molecule, and its effect on the C-F stretching frequency shifts and on some surface chemical properties became of interest. In a recent study the C-F stretching frequencies of a series of normal perfluorocarboxylic acids and a few 1,1' -dihydroperfluoro alcohols were determined as a function of chain length and the results were compared with the corresponding hydrocarbon analogs. Furthermore, the nature of the induced polarity in the hydrocarbon and fluorocarbon groups was investigated through surface potential measurements at the interfaces of air-aqueous solutions of normal butyl alcohol and of l,l'-dihydroperfluorobutyl alcohol and through differential capacity and electrocapillary measurements at the interfaces of mercury-aqueous solutions containing the above two alcohols. Experimental Normal perfluorocarboxylic acids and 1,1' -dihydroperfluoro alcohols were provided through the courtesy of the 3M Company, St. Paul, Minnesota. Normal butyl alcohol was purchased from Distillation Product Industries, Rochester, New York. A Perkin-Elmer Model 621 infrared spectrophotometer was used to investigate the spectra in the frequency region of 1200 to 1270 cm-l with frequency scale

Jan 1, 1971

By James McManus

The Lornex mine is located on the Southern slope of the Highland Valley in South Central British Columbia. The large low grade deposit was discovered in 1964; stripping began in 1970, and the mill started commercial production in October of 1972. The orebody is classified as a complex porphyry type having as major constituent quartz diorite, with varying amounts of quartz, grano diorite, and porphyry. A substantial degree of alteration is evident in the host rock, and this became the key factor in major equipment selection for the grinding section. A pilot plant was constructed on the property capable of treating 100 TPD of ore. The ore was mined to be as representative as possible of the entire orebody by sinking a shaft and cross cutting the deposit underground.

Jan 1, 1975

By G. S. Dobby

Particle collection is considered to occur by particle collision with the bubble followed by the particle sliding over the bubble during which attachment may occur. Collision is quantified by a collision efficiency, EC. The existing model for EC is extended by including particle inertia. Attachment is quantified by an attachment efficiency, EA calculated as the fraction of particles which reside on the bubble for a time greater than the induction time. These calculations use recent data on the liquid velocity distribution over the upper half of rigid spheres. Collection efficiency, EK is given by EK = EC ? EA. Detachment is not considered. The mode is examined and shown to agree with much experimental data. For example the maximum observed in recovery vs particle size (d) can be explained as E increases with increasing d , while EA decreases. The decrease in selectivity at fine sizes is in accord with the model result that for dp < 5µm, EA ? 100% (i.e. EK ? EC) almost regardless of induction time. A decrease in bubble size does increase EK but does not improve selectivity. A high particle density (> 5g/cm3) is shown to cause a sharp peak in recovery vs size and a decreased maximum size of floatability. Finally, the possible effects of bubble and particle concentration are explored.

Jan 1, 1985