Search Documents

By D. Bhattacharyya

The adsorption and desorption of gold cyanide by activated carbon is significantly influenced by particle size of the activated carbon particles and the chemical environment. A series of adsorption and elution experiments have been performed with ten different particle size fractions. The tests indicate that although the ultimate adsorption capacity is independent of the activated carbon particle size, the adsorption rate is strongly affected by the particle size. Further, desorption characteristics using traditional Mintek and atmospheric Zadra procedures reveal interesting trends with variation in particle size and will be discussed in this paper.

Feb 23, 2014

By J. D. Grenia

The Buick Mine is a joint venture of American Metals Climax, Inc., and Homestake Mining Company located 120 miles by road southwest of St. Louis, near the village of Boss, in the 'New Missouri Lead Belt' (See Figure 1). Since start-up in 1969, over four million tons of lead-zinc ore have been mined and milled at Buick. Situated about 1,100 feet below the surface at an elevation 270 feet above sea level, the flat lying sinuous ore bodies are up to 250 feet wide, 85 feet high and several thousand feet long. Mineralization is galena, sphalerite and chalcopyrite in dolomite, Access to the mine is through two 18'Ø concrete lined vertical shafts - one for servicing and the other for hoisting ore (See Figure 2). The mine is being worked by a modified room and pillar method using both rubber tired equipment and a sub-level rail haulage. Ore is broken from first pass headings, back and bench faces and transported by load-haul-dump units to ore passes located on 900 foot centers. The ore is pulled from chutes on the sublevel 90 feet below into 15 ton bottom dump cars and delivered in 10 car lots by a 15 ton diesel locomotive to a 42" gyratory crusher (See Figure 3). A recent innovation has been the introduction of two 50 ton trucks with plans to haul up to 60% of the ore on the mining level to an ore pass feeding directly to the primary crusher (See Figure 4). Ventilation raises up to 16'Ø, which were originally planned for 900 foot centers, are now driven on 450 foot centers.

Jan 1, 1973

Sedimentation is used to clarify process effluents or to thicken process slurries. The sedimentation cycle of a suspension is presented as a settling curve. This curve is simply a plot of the height of the interface between the settled suspension and clear liquor versus time. Figure 1 shows a series of graduate cylinders which contain a suspension at various stages in its settling cycle. Cylinder 1 shows the suspension completely mixed at time zero. After a brief period of time (see cylinder 2), the suspension is observed to settle from its initial height Ho to height H1, leaving behind a volume of clear (or turbid) liquor, called the supernatant. The interface between the supernatant and suspension is termed the mud line. It is also possible to distinguish at the bottom of the cylinder a layer of sludge representing solids which have settled from the suspension. The interface between it and the suspension is called the sludge line. The sludge line moves upward in the cylinder.

Jan 1, 1992

By Jinke Li, Fenghua Wang

"While coal fueling China's economic growth it has already been causing severe pollution and amounts of CO2 emission. How to make deep reductions in carbon emission is not only a huge challenge for the greatest consumer of coal, but also a revolution for China’s coal industry. The paper explores how to shrink CO2 emissions during the lifetime of coal. The paper points out that increase of coal mine efficiency and productivity, green mining, utilization of coal mine methane and environment-friendly disposal of coal gangue can reduce CO2 during coal mining; coal preparation and coal by wire can decrease CO2 during coal preparation and transportation; improving combustion efficiency, CO2 capture and storage (CCS) and coal transformation can lessen CO2 during coal utilization. The paper also points out that Circular Economy Park is a practical way to develop a low carbon economy for coal industry. An econometric model for total coal industry and each sector are constructed to measure carbon emissions based on CO2 equivalent emissions, then with detailed calculations, based on potential greenhouse-gas emission's reduction, a most likely low carbon roadmap of China's coal industry is depicted with scenario analysis method.Introduction Global warming poses a profound threat to humanity and the natural world and is one of the most serious challenges humankind has ever faced. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface temperature increased 273.89 ± 273.33K during the 20th century (IPCC 2007). Increasing concentrations of greenhouse gases have caused most of the observed temperature increase since the middle of the 20th century (United States National Academy of Sciences 2008), and CO2 is the most important cause of global warming. In 2005, CO2 contributed 76% of global greenhouse gas emissions, CH4 contributed approximately 16%, N2O contributed approximately 6% and the combined F-gases contributed approximately 2% (IEA 2010). Among the many human activities that produce greenhouse gases, energy use is by far the largest source of emissions. Since 1870, CO2 emissions from fuel combustion have risen exponentially (IEA 2009). Of the three types of fossil fuels - coal, natural gas and petroleum - coal constituted only a quarter of the world total primary energy consumption in 2007. The situation is even more critical in China than in the rest of the world, as energy-intensive industrial production is growing rapidly, and large coal reserves exist in combination with limited reserves of other energy sources. The development and production of the coal industry provide stability in China's economic growth. There are more than 7000 coal enterprises in China; the coal enterprises are the main contributor to China's ""economic miracle""."

Jan 1, 2017

By Liuhuai Ding

Background of Ocean Mining Research Inspired by the 1970?s deep seabed mining activities of other nations, China started ocean mining research work within the framework of the International Law of the Sea Treaty (UNCLOS) and the subsequent establishment of the International Seabed Authority in the 1990?s. This work has been carried out mainly with the cooperation of the Changsha Research Institute of Mining And Metallurgy. We have been committed to this work to fulfill our responsibilities and obligations as a Pioneer investor under UNCLOS and also to support the much needed development of deep-sea technology in China. Exciting recent advances by Nautilus Minerals in the development of seafloor massive sulfide deposit exploitation has led us to a new perspective of ocean mining and some re-evaluation of ocean mining economics. This has provided us with an opportunity to support more efforts in ocean mining research. We will not delay the development of our ocean mining system and corresponding technology, although commercial mining in the deep-sea area may not occur for many years.

Jan 1, 2008

By Kenneth R. Miller

Surface mine equipment operators in the Campbell County region of Wyoming's Powder River Basin have found new ways of solving old problems. Technology, experience, competitive pressures and an increasing grasp of economies of scale have driven mine operators, equipment manufacturers and suppliers to specialization of applications. In economic terms, today's coal price of $4.95/t ($4.50/st) equates to $2.53/t ($2.30/st) in 1980 terms - an incomprehensible value at that time. This article describes some examples of change and adaptation made by Powder River Basin coal operators in overburden stripping equipment and techniques. It focuses on the evolution of the design and use draglines, shovels, trucks, scrapers and dozers.

Jan 1, 1998

By J. L. Mehaffey

A variety of chemicals offered by Armak were evaluated as dewatering aids for aqueous slurries of silica sand, sparsand and feldspar; an established commercial dewatering aid was used as a control. A number of Armak's potential dewatering aids yielded lower moisture retention values than did the commercial product on all of the mineral samples. In addition to the chemical dewatering evaluations, some of the mechanisms involved in the removal of water from these mineral samples were examined.

Jan 1, 1983

By G. J. Trezek

The use of polysilicates for treating heavy metals in soils and mining sludges is discussed. Results of the treatment are given for soil contaminated in a metal scrap yard operation and for copper mining processing sludges. The types of metals of concern are arsenic, lead, copper, nickel, cadmium, and zinc. The application of the treatment is predicated on the mixture and relative concentrations of the metals as well as the material matrix. Reductions in soluble concentrations (STLC or TCLP) of one to two orders of magnitude can be achieved with relatively small additions of silicates and cementitious materials.

Jan 1, 1992

By Edwin K. Maughan

The Rocky Mountain region contains part of the paleocontinental shelf that lay in Arizona and New Mexico through Utah, Colorado, and Wyoming into Montana and North Dakota. The shelf was bounded by the northeast-southwest-trending Transcontinental arch and the Cordilleran miogeocline in late Paleozoic and early Mesozoic time. Major tectonic features that affected middle Phanerozoic sediments on the shelf were the Big Snowy trough and Williston basin in the north and the ancestral Rocky Mountains in the central part of the region. The Zuni uplift and similar positive areas occurred along the axis of the Transcontinental arch in the southern part. The late Paleozoic and early Mesozoic sedimentary rocks record transgressive-regressive marine cycles in which the Cordilleran shelf and much of the adjacent craton were inundated by epeiric seas. Early in the Carboniferous, an epeiric sea covered most of the shelf. Greater topographic relief developed in Late Mississippian, was at a maximum in Middle Pennsylvanian, and then diminished through Permian and Triassic time. The development in the Pennsylvanian Period of horsts and grabens along northwest- trending faults on the northwest flank of the Transcontinental arch resulted in the ancestral Rocky Mountain system. The eastern part of the region was emergent by Middle Triassic, and the emergence lasted until Middle Jurassic, owing to uplift along the Transcontinental arch. During the early part of the Mesozoic, the sediments were dominantly terrigenous and were deposited mostly in shallow littoral marine environments shifting to continental. Most middle Phanerozoic structural elements within the area of the shelf are characterized by lineaments that have either an east-northeast or a conjugate north-northwest trend. The east-northeast lineaments closely parallel the northeast trend of the continental slope (miogeocline) in Nevada to southern Idaho. The conjugate set closely parallels the northwesterly continuation of the miogeocline north of an approximately right- angle bend in south-central Idaho. The northeasterly trending Transcontinental arch and the northwest-trending margin of the Canadian Shield are parallel structural elements with the north- east and northwest trends of the miogeocline. The rectangular lineament pattern on the shelf suggests a system of rectilinear fractures within the underlying Precambrian crystalline basement rocks that moved several times in the Phanerozoic in response to external forces applied against the continental crust. Movement of these blocks influenced erosion, deposition, and lithofacies of the sediments in middle Phanerozoic time. Zones of crustal weakness, represented by the lineaments bounding these blocks, probably were influential in localizing sedimentary mineral accumulations and petroleum deposits, as well as later igneous intrusions, volcanism, and emplacement of hydrothermal ores. Igneous activity in this region was rare during the middle Phanerozoic, but these conjugate fractures seem to have been avenues for later passage of hydrothermal solutions responsible for ore emplacement.

Jan 1, 2013

By C. A. Holley

The generation of coal fines is a growing problem which has serious environmental and resource recovery Impact. Several methods of agglomeration are studied including the production of briquettes for the consumer market. Simplified process flow diagrams, "order of magnitude" plant capital cost and operating costs are presented.

Jan 1, 1986

By Kendall Y. Keuhey

The Mercur Mine, developed and operated by Getty Mining Company, is designed to process 3,000 tons/day of gold ore from the historical Mercur Hill mining district. The mill process involves crushing, grinding, and cyanide carbon in leach for recovery of gold ores ranging from 0.08 to 0.10 oz/ton. During the mining of normal grade ore, a substantial tonnage of material containing 0.02 to 0.05 oz/ton is mined and would be available for heap leaching. Also, Getty Mining is developing methods to test and prepare lower grade material for heap leaching by rejecting a course rock fraction from the grinding circuit SAG mill. This lower grade fraction is suitable for heap leaching, and its removal will upgrade the regular mill feed. Other test methods are directed toward leaching techniques on some 4.0 million tons of tailings that resulted from roasting and/or cyanide leaching Mercur ores in the early 1900s. The natural carbons associated with the Mercur deposits require special treatment to reduce their gold adsorption effects when leached with cyanide.

Jan 1, 1983

By Ehsan Alavi Gharahbagh

Tool and cutterhead wear is a crucial issue in soft ground tunneling, especially because tool inspection, maintenance, and replacement are done under difficult conditions, and often under pressurized faces or under ?hyperbaric interventions?. Overall, tool inspection and changing is a time consuming and costly step, which needs to be quantified and the related costs accounted for in any construction contract for scheduling and costing of the tunnels at design stage or bid preparation. However, lack of a universally accepted index or measure for soil abrasivity in the geotechnical reports has made it difficult, if not impossible, to define cutter wear for this purpose. Soil abrasion and its impact on cutting tools for tunneling machines under dry or wet conditions have recently been under spot light due to construction claims in several of the recent tunneling projects. The objective of this paper is to examine soil?s physical, mechanical and tribological properties related to the interface of the soil and excavation tools and discuss ways to measure soil abrasivity in a quantitative and repeatable manner. The paper will discuss the efforts that are underway to develop a new soil abrasivity index and the fabrication of a new testing device for this purpose.

Jan 1, 2010

By C. L. Schneider

The calculation of the liberation spectrum in the product from continuous milling operations is a problem of considerable importance and is difficult to solve because the population balance equation must be integrated in two-dimensional space. Complete solutions require the estimation of a large number of parameters unless a structural model of the ore texture can be used. A very simplified textural model based on the use of the modified Andrews-Mika diagram and the PARGEN simulation of multi-phase particles has been formulated and is used to simulate the behavior of a continuously operating laboratory ball mill. A sensitivity analysis for this mill has been done to show the likely effect of model approximations on the predicted liberation spectrum which will be measured.

Jan 1, 1992

By Christopher J. Bise

The potential of the coal reserves in the western United States for meeting future energy needs has been recognized for quite some time. However, two of the major constraints which have tended to limit the development of these reserves which can only be deep-mined are the great thicknesses of the coal seams encountered and their high pitch. Although new mining methods may need to be developed to recover these reserves, at least in the short- term the industry has to incorporate presently available equipment which were not originally designed for thick-seam mining. The purpose of this paper is to present an analysis of the various equipment that are in use today and their possible application to thick-seam mining. The paper also addresses the various ground control and safety considerations that are unique to thick-seam extraction.

Jan 1, 1981

By Roberto Pimentel de Souza

Since 1976 CVRD is carrying out tests to develop a type of pellet made with organic binder. One binder that showed good possibility to be used in industrial plants is Peridur. An extensive framework of tests was run in CVRD's pilot plant. The results are presented in this paper. Finally, the decision was taken to carry out an industrial production of 50.000 t of pellets. It was scheduled for March '81. The results are shown in this pager. It was not observed any detrimental effect of the peridur neither in the process nor in the product quality.

Jan 1, 1981

By T. V. Ramey

Heap leaching in certain parts of the world, such as Chile's Atacama Desert, brings unique design problems in the form of possible large differential settlements of the foundation soils due to the dissolution of salts in northern Chile the soils often contain very high concentrations of soluble salts (nitrates, potassium, magnesium, and common sodium). When a leak in the liner occurs, the escaping solution dissolves these salts and triggers differential settlement. If the settlement is great enough, the geo-membrane tears, the leakage increases, triggering more differential settlement. The nitrate plants have experienced many occurrences of this phenomenon where a brine pond will undergo a sudden and complete loss of the impounded liquors. The authors present a simplified technique to quantify the differential settlement resulting from dissolution and provide a method which can be used to select a geo-membrane with suitable flexibility under axi-symmetric (multi-axial) load conditions to tolerate the predicted settlement. (This paper was previously published for Randol Gold Forum 1996 [Ref. 6]).

Jan 1, 1997

By T. M. Klemetti, T. J. Batchler, T. Matthews

From 2013–2017, there were over 1,120 documented injuries, including fourteen fatalities, from ground falls in underground mines in the United States (MSHA 2017). The majority of these ground-fall injuries were not caused by a major roof collapse, but from falls of smaller rocks from the immediate roof. Roof screen can significantly reduce the number of these injuries and has been widely used in underground coal mines for surface control. Because of the potential of reducing ground-fall injuries, the National Institute for Occupational Safety and Health (NIOSH) is further evaluating the performance characteristics of welded-wire screen as used in underground coal mines by conducting a laboratory testing program using the Mine Roof Simulator (MRS) in NIOSH’s Bruceton Research Center Laboratory in Pittsburgh, PA. The load-displacement characteristics of an 8-ft x 12-ft area of 8-gauge welded-wire screen were evaluated using a test frame designed for testing multiple load-pull locations. In previous tests, load-pull contact was always in the center of the bolted screen section. In this study, larger pull contact areas are used to simulate roof falls. The information obtained in this and similar studies can be used to better understand the loading behavior and surface control capability of roof screen in underground mines. INTRODUCTION AND BACKGROUND The large majority of ground-fall injuries are caused by falls of smaller rocks from the immediate roof. Various controls are currently being used in mines to control this surface rock, including the use of wire roof screen. In mines where wire roof screen has been installed, injuries from rock falls have been reduced dramatically (Robertson and Hinshaw, 2001). Roof screen has the potential to prevent hundreds of injuries caused by the fall of small rocks between permanent roof supports (Compton et al., 2007). Because of this potential for reducing ground-fall injuries, the National Institute for Occupational Safety and Health (NIOSH) is evaluating the performance characteristics of welded-wire screen as used in underground coal mines by conducting a laboratory testing program in the Mine Roof Simulator (MRS) in NIOSH’s Bruceton Research Center Laboratory in Pittsburgh, PA. Previous tests to evaluate the performance characteristics of various types of screen have been conducted by the University of Alberta (Tannant, 2001). In this study, the load-displacement properties of welded-wire, chain-link, and expanded-metal mesh were measured by performing full-scale pull tests. A flat steel plate was pulled through a screen test sample that was bolted to a special test frame while the pulling force and mesh displacement were measured. These tests established the general load-displacement behavior of the screen. Peak load capacities and stiffness were determined for each screen type, showing how welded-wire mesh has a much stiffer initial loading response, whereas chain-link and expanded-metal mesh have large displacement capabilities and exhibit significant post-peak ductility.

Jan 1, 2019

By J. -M. Lopez-Cuesta, C. Petter, B. Otazaghine, M. Batistella, R. Sonnier

"Kaolinite is a dioctahedral aluminosilicate widely used as paper filler and coating pigment. At the best of our knowledge, kaolinite is not widely used in polymer industry. Therefore, in this study, the flame retardant effect of kaolinite in ethylene vinyl acetate copolymer (EVA) and polypropylene (PP) were studied and compared with an alumina trihydrate (ATH) and Talc. Cone calorimeter results shows that the weight percentage of ATH in EVA/ATH composites must be at least 50 wt. % in order to reach an improvement in fire retardancy in terms of pHRR. In the case of EVA/kaolinite, even with 35 wt. % the pHRR is largely reduced. Comparing PP/Talc and PP/kaolinite composites at 30 wt. %, both fillers leads to same reduction in pHRR with a slightly better performance for PP/kaolinite composites. In both cases an intumescent behavior of kaolinite composites was observed that could slow the rate of the rising degradation products, allowing radical recombination reactions. Also, it was observed that kaolinite forms a protective layer on the surface of the samples, which could insulate the material. These behaviors (intumescence and formation of a protective barrier) could reduce the transfer of the degradation products to the flame and explain the better performance of kaolinite composites. INTRODUCTION The use of mineral fillers as fire retardants in polymer matrix are well known and widely studied [1]–[10]. Aluminum and magnesium hydroxides (respectively ATH and MDH) are the most widely used inorganic fire retardants. To achieve fire retardancy with these mineral fillers, about 50-60% loading is required which decrease the physical properties of the composites. The fire behavior of composite EVA has been the subject of many studies [4], [7], [9]–[15]. EVA copolymers are commonly used in the cable industry, due to their high ductility, even at high loading rates. In such applications, the flame retardant systems should be introduced into the polymer to improve the fire reaction. Many flame retardant systems have been tested but the most used industrially relates to formulations based on hydrated mineral fillers (aluminum hydroxide and magnesium hydroxide). Their low cost and reduced fumes generation explains their success. However, to obtain good performance with this type of flame retardants, it is necessary to incorporate high levels (up to 65 wt %), which severely impact other properties such as processability and mechanical behavior. The main modes of action of these flame retardants are the dilution of the gas phase, the endothermic decomposition and a barrier effect created by the inorganic oxide residue which may be improved by the incorporation of other components such as montmorillonites, silicas or talcs."

Jan 1, 2015

By W. M. Lewis

Product losses to tailings ponds have long been a source of frustration for the mining and utilities industries. The utilization -of the Lewis Econosizer to recover lost products has proven to be very cost effective through reduced acreage requirements, cleaning costs and increased production. The unit is successfully operating in coal, aggregates, industrial minerals, clay, fly ash, heavy minerals and many other ores. Utilizing an upward flow of slurry in a free settling environment, particles stratify within the unit according to settling velocities and are removed as sized products. Ultra fines or clarified water is removed off the top of the unit. The Econosizer requires no power and only minimal maintenance.

Jan 1, 1998

By William J. Miles

The inhalation of dust has been a problem in the mining industry since antiquity. Crystalline silica is now known to be the cause of silicosis, a form of pneumoconiosis that is associated with excessive exposure to respirable particles in some mining and industrial environments. Crystalline silica was reviewed by the International Agency for Research on Cancer (IARC) in 1986 and classified as a Group 2A, Probably Carcinogenic to Humans in Volume 42 and Supplement 7 of the IARC Monographs (1987). In 1996, IARC reviewed additional literature and studies published in the intervening decade and recommended that quartz and cristobalite, two polymorphs of crystalline silica, be listed as Group 1, Carcinogenic to Humans. Their recommendations and reclassification were published in 1997 in IARC Monographs 68.[2] In both Monographs, IARC classified amorphous silicas as Group 3, Inadequate Evidence for Carcinogenicity to Humans.

Jan 1, 1998