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By Stanley V. Lachmansingh

Bauxite can be regarded as a mixture of hydrated aluminium oxides the predominant constituent - and oxides of iron and titanium, silica and silicates. Heterogeneous and non-crystaline, most bauxites vary in average composition from one deposit to another both in terns of impurities as well as the proportion of Gibbsita and the Monohydrates Diaspore and Boehmite. Iron levels (as Fe2O3) can vary from less than 1% to as high as 30% with the alumina content ranging from 40 to 6o%,. Gore than 90% of all bauxite mined in Guyana is used as feed for the - production of refractory grade calcined bauxite. There are -however, several speciality grades used in various industrial applications and these are characterised by the quality of the bauxite in particular ;,with regards to iron and silica levels which generally have to be low. The main speciality grades are designated Refractory, Abrasive and Chemical. Bauxitte is also used in the production of nigh alumina cements,, activated bauxite end in the manufacture of electrical insulators.

Jan 1, 1977

By A. Röttger, W. Theisen, J. Küpferle, M. Alber

"Wear of TBM tools significantly affects tunneling advance rates. Wear-prediction models are based (amongst others) on the abrasivity of the present geology, which is determined via laboratory tests. To evaluate the results from such tests in context, this work considers the tribological system TBM tool from a materials technology perspective. In so doing, the microstructures of different application-oriented materials are presented and discussed in terms of their wear behavior and wear resistance. The significant influence of tool materials on the abrasivity of the geology and thus wear prediction models has already be identified. LCPC, Cerchar and nano-scratch experiments have been performed as confirmation. Material-dependent wear mechanisms and their correlation in terms of tunneling have shown that it is mandatory to consider the complete tribological system to estimate the wear of TBM tools. 1 INTRODUCTION Mechanized tunneling is vital to ensure necessary infrastructure development in megacities like Tokyo (Bay Tunnel), Istanbul (Eurasia Tunnel) and Mexico City (Tunnel Emisor Oriente). The use of Tunnel Boring Machines (TBMs) has been established for many years. In contrast to other methods such as boring and blasting or excavation using dredgers, tunneling with TBMs allows simultaneous excavation and removal of both the mineral and tunnel lining by tubbing segments or shotcrete. This makes tunneling more efficient, allowing for faster development of the tunnel in both hard rock and soil [1]. When budgeting such tunneling projects, precise planning and coordination in terms of tunneling technique choice (e.g. EPB or Slurry-shield), the relevant geology, and the associated penetration rates and tool wear are required. In particular, wear to TBM tools has a significant impact on tunneling progress. Due to wear, tools become dulled or lose their functionality because of brittle material behavior, thus reducing penetration rates and therefore tunneling efficiency [1]. As a result, additional tool changes are necessary, leading to higher overall costs due to down times and maintenance costs. Therefore, there is strong interest in a reliable and precise wear prediction model for TBMs. As already mentioned, the geology and associated wear of the tunneling tools define the maintenance times."

Jan 1, 2016

By James W. Griffith, Sarah A. Riling

Bituminous coal dust was repeatedly placed into one lung lobe of anesthetized Macaca nemestrina monkeys using a flexible fiberoptic bronchoscope. Radiographs taken at 15 day intervals showed a focal radiographic density after 90 days time when a total of 1 gram of dust had been instilled. The radiographic density progressed slightly in size until 12 months by which time 3 grams of dust had been instilled and the animals were euthanized. At necropsy, the only significant gross lesion detected was the focal black pulmonary lesion located at the dust instillation site. Histologically, the lesion was composed of coal dust laden macrophages located primarily within interstitial tissue and interspersed with a slight amount of reticulum and connective tissue fibers. The distribution of coal dust was limited to the instillation site in the right caudal lung lobe based on radiographic, gross and histologic examination. Bronchoalveolar lavage of both right and left caudal lung lobes was performed 8 times during the 12 month long experiments without significant complications. More macrophages were found in lavage fluid from the right lung than the left, and most macrophages from right lung contained coal dust particles. Based upon a limited physical examination and complete blood count at 15 day intervals the animals remained normal during the experiment. We conclude that the primate lung's response to focal experimental bituminous coal dust resulted in a marked focal increase in pulmonary alveolar macrophages, which can be recovered regularly in high numbers by bronchoalveolar lavage. The model described has significant potential for investigating the pathogenesis of various respirable dust-induced pneumoconioses, for evaluation of new therapeutic approaches, and for refining experimental and clinical diagnostic applications of bronchoalveolar lavage. Key words: Coal Workers Pneumoconiosis, Disease model; Primate, Lung Lavage Fluids

Jan 1, 1991

By F. W. Brackebusch

Paste is a high density mixture of water and fine solid particles with a relatively low water content (10-25%) such that the mixture has a consistency as measured by the ASTM slump cone test from slightly greater than zero up to nearly 12 inches (305mm). Particles of different size classes will not segregate or settle when the paste is not being agitated or when it is stationary in a pipeline. Cement may be a component of paste. Larger particles of aggregate can generally be added to a paste without greatly changing the pipeline transport characteristics. A paste may bleed water slightly when it is allowed to be motionless for periods of up to several hours, but the solids do not become so dense that the paste cannot be easily re-fluidized. The dividing line between the definition of a high density slurry and a paste is not sharp. It is a practical matter that must be considered when designing a pipeline transportation system. If the pipeline is very short, there is very little risk of plugging the pipeline with a high density slurry when flow is stopped for short time periods. With longer pipelines the mixture must remain stable without motion for periods as long as several hours to avoid pipeline plugging. The fine particles in a paste mixture can be composed of mine tailings or naturally-occurring clays, silts and fine sands. The mineralogy of the particles thus can have a wide variety from quartz and feldspar to clays, micas and even salts.

Jan 1, 1993

A Mark IV surface force apparatus (SF A) was used to conduct direct force measurements in dodecylamine hydrogenchloride collector solution between mica surfaces at varying pHs. It has been found that the long-range hydrophobic forces reach a maximum at pH 9.5, which also corresponds to the maxima attained by the contact angle and flotation recovery of quartz. The charge densities are comparable on both mica and quartz surfaces (0.40-0.48 run2), making it possible to draw conclusions on the flotation of quartz from the direct force measurements conducted on mica. Therefore, it may be suggested that the maximum flotation recovery of quartz m the range of pH 8.0-10.3 may be attributed to the appearance of long-range hydrophobic force, which in turn can be related to the formation of a close-packed monolayer (or hemimicelle) in the presence of neutral amines formed as a result of hydrolysis.

Jan 1, 1996

By C. Bazin

The fundamental error associated to the sampling of heterogeneous ore particles is unavoidable and can only be minimized by an adequate selection of the sample mass and/or size reduction of the sample before division into sub samples for testing or assaying. The preparation of ore batches to carry out the mineral processing evaluation of an ore is a sampling process. The fundamental error associated with the division of the ore into batches is responsible for the differences in the composition of the batches. This paper attempts by various means to assess the reproducibility of the gold content of test batches prepared from a gold ore sample. The results of the investigation shows that for fine gold grain sizes the variability in the composition of the batches is less than that predicted by Gy?s formula and that the gold grain size is a strategic information in the assessment of the gold content variability of test batches.

Feb 23, 2014

By M. S. Prasad

This paper presents the process methods of beneficiating various copper-cobalt and copper-zinc ores mined by Gecamines in Zaire. Geology and mineralization of both sedimentary and vein type deposits are described with special emphasis on the production of oxide, dolomitic and sulfide concentrates. Description of different types of concentrators and their treatment methods are discussed for the production of sulfide, oxide and dolomitic concentrates. Production of concentrates, their consumption and stocks are briefly reviewed. Modernization of the concentrators with substantial investments on grinding, classification, flotation methods and tailings treatments are also discussed to improve the metallurgical efficiency of the concentrators with a view to improve the production of concentrates both qualitatively and quantitatively.

Jan 1, 1990

By J. H. Gasper

The overall success of steep slope (>20°) contour mining is dependent upon many factors. The major factor is the selection of the mining method that best suits the premining site conditions both environmentally and economically. These conditions can be divided into three major categories: 1) Geometric Conditions --machine limitations, slope stability restrictions, erosion capacity, among others; 2) Physical Conditions--material properties, rock strengths, diggability, driving surfaces, among others; 3) Chemical Conditions --acid/base relationships, blending or selective placement of overburden, among others. This paper incorporates these conditions through conceptually modeling compliance oriented contour mining methods; in particular Haulback methods, utilizing: 1) the Front-End Loader (FEL)/Truck; 2) Tractor Scrapers; and 3) Combined FEL-Truck/Scraper. Engineering analyses including machine selection, sequencing, ease of varying production rates, slope requirements (for stability and running surfaces), drainage requirements and many others can be performed after the geometric constraints dictated by in-situ conditions and regulatory requirements have been conceptualized. Once all generalized geometries have been established, reduction to idealized three-dimensional views is achieved. These are then reduced to two-dimensional symbolic models, mainly plan views, but also elevations and sections. Equipment activities and operations are then conveniently overlayed. Without this simple two-dimensional reduction, technology transfer remains awkward and non-analytical.

Jan 1, 1991

By W. H. Langer

The U.S. Geological Survey (USGS) in cooperation with the New Mexico Bureau of Mines is conducting an assessment of mineral resources in the 36,800 km2 Mimbres Resource Area, southwestern New Mexico. Included in the assessment is a literature-based evaluation of sand and gravel that utilizes third party geologic information. The USGS has developed a method based on existing 1:500,000 scale geologic maps supplemented by remote sensing, statistical models, and point data such as test hole or pit records. The method defines the areal extent, quality, and quantity of aggregate.

Jan 1, 1996

By A. A. Sobek

Controlled release systems delivering the required concentration of an effective bactericide over an extended time period have been developed by The BFGoodrich Company's ProMac® Systems group. The ProMac system is site-specific and includes a four-step approach to controlling acid mine drainage (AMD): (1) Diagnosing the problem, (2) Prescribing the treatment, (3) Supervising the application of controlled release bactericides, and (4) Honitoring the success of applied treatment. The success of the ProMac system is evidenced by improved water quality, healthy vegetation, a reduction in levels of acidophilic thiobacillus, and a corresponding increase in population of beneficial microorganisms.

Jan 1, 1986

By R. L. Grayson

Evidence has accumulated indicating that cultural change toward safer workplace behaviors is beginning to occur systematically in the coal industry. Through a range of programmatic mining company successes, enforcement and litigative actions, economic responses to competition, and integrated efforts by federal and state agencies, a broader participation of safety and training professionals is being achieved to address prioritized workplace problems at mines. Small steps in workplace-related improvements have been realized already, but the trends in industry safety statistics, coupled with focused programmatic initiatives, indicate that more definitive and systematic steps are occurring to improve safe behavior in the workplace routinely.

Jan 1, 1996

By D. A. Norrgran

The process of magnetic separation is based on the differences among magnetic susceptibilities of various mineral species. Performed either wet or dry, the separation has application in both the recovery and concentration of value minerals and in removing deleterious mineral constituents from a product stream. There are two major catagories to be considered when addressing magnetic separation of minerals. The first catagory refers to particle characterization and relative differences in magnetic susceptibility. The second catagory refers to design parameters and the magnetic field generated by the separator.

Jan 1, 1987

By R. L. Keiski, H. Miettunen

"The serpentinite massifs of Hitura are located in the municipality of Nivala in Central Finland. The most important sulfide minerals in the ore are pentlandite, pyrrhotite and chalcopyrite. The ore body consists of amphibolite rocks in contact with serpentinite against mica gneiss. The mean Ni grade of the ore is about 0.7%, and the highest Ni grades have been encountered in close contact. In general, the inner parts of the ore are strongly serpentinized ultramafite and some sulfides have been converted to mackinawite and valleriite. The degree of alteration varies considerably within the ore body and, correspondingly, the grain size of the sulfides varies as well. In this study, flotation tests were done with samples from different zones of the ore body. The flotation test results on the bench scale and plant scale are discussed in terms of the mineralogical features of the ore. Ores in the North Hitura zone differ from those in the South Hitura zone.IntroductionThe Hitura nickel mine, like the entire Nivala area, is part of the Bothnian Svecokarelian schist zone, where numerous Ni-Cu boulders have been discovered since the early 1930s. The Nivala area has therefore been the subject of exploration activities by the Geological Survey of Finland (GSF) and mining companies. The first period of exploration started in 1936, and the Makola nickel deposit, located 3 km south of the Hitura mine, was discovered by GSF in 1937. About 415,000 tonnes of ore were mined at Makola between 1941 and 1954. In 1937, during the exploration and development stage of the Makola mine, boulder tracing and a geophysical survey revealed a significant ultramafic body with some lowgrade Ni-Cu occurrences in the South Hitura zone.In 1961, GSF continued the exploration program in the area and discovered the North Hitura ultramafic complex and its allied Ni-Cu occurrences. In 1964, Outokumpu Oy bought the property and, after underground exploration, comprehensive mineralogical studies, process research and a feasibility study, production started in 1970 (Isohanni et al., 1985)."

Jan 1, 2015

By W. C. Yates

Lack of visibility from cabs of the large haulage trucks used in open-pit mines has become a serious safety problem. This Anaconda research program was conducted to develop a low-cost system for alerting haulage truck operators of the presence of small vehicles in their blind areas. Several systems, developed and tested to help solve this problem, are summarized and evaluated in this paper. As the size of the haulage trucks used in large open-pit mines has increased, so have the blind areas. Mine utility vehicles, pickup tucks and cars become concealed within these blind areas and, thus, become a serious safety hazard. Figure 1 shows the typical blind areas of a 150-ton haulage truck. The areas of greatest concern are those at the rear center and front right corner of the truck. It is within these areas of "no visibility" that numerous small vehicles over the years have been crushed by the large haulage trucks at various mine sites. Although the occupants in most instances, have escaped the vehicle before it was destroyed, injuries and deaths have occurred. The accidents, in most cases, were attributed to negligence or carelessness on the part of the driver of the smaller vehicle, but the problem of limited visibility still exists, and a solution is needed.

Jan 1, 1982

By Valerio Violo, Antonio Raschillà, Livia Cicinelli

"The Cityringen project foresees the construction of a new circular metro line in and around the city center of Copenhagen. Both drives, the north and the south one, required the TBMs to be equipped in order to cope with contaminated water table and soil. The north drive mined in water contaminated with chlorinated compounds, including chloroform and vinyl chloride, while the south TBMs excavated in a highly benzene contaminated area, becoming the first TBMs to complete such a challenge. Despite the pollution and the stricter operative procedures, the production has been extremely successful with record up to 520 m in one month and 32 m in one day. 1 INTRODUCTION The Cityringen is an extension of the existing metro line. The 15 km long twin tunnels will form a new circular line with 21 new stations (17 + 4 crossovers). When finished it will interchange with the existing metro, rail and bus infrastructure at key locations around town, taking 90% of Copenhagen citizen at less the 600m from a metro station (Figure 1). The Contract has been awarded in April 2011 to the Copenhagen Metro Team (CMT), a joint venture between the Italian companies Salini Impregilo, Tecnimont and Seli SpA. Tunnels are being excavated with 4 Seli-Kawasaki EPB TBMs, two of which manufactured in Denmark by Seli Tunneling Denmark ApS, which is also operating them. At the moment this article is written 50% of the tunnels have been completed and over 40% handed over for the electromechanical works. Seli Tunnelling Denmark is a Danish company constituted in 2012 as a subsidiary of Seli SpA for this project and subsequently acquired by the Salini Impregilo Group in 2015."

Jan 1, 2016

By Arthur R. Still, Paul A. Bailly

5.1-PURPOSE, PROCEDURE, METHODS, MANAGEMENT Exploration can be technologically defined, with regard to the discovery of new mineral deposits, as all the activities and evaluations necessary before an intelligent decision can be made establishing size, initial flowsheet and annual output of new extractive operations. The purpose of mineral exploration is the discovery and acquisition of new mineral deposits amenable to economic extractive operations now or in the future. A prime objective of mineral exploration, however, is to find and acquire a maximum number of such mineral deposits at a minimum cost and within a minimum time. Immediately upon the heels of a successful ''exploration" discovery follow activities called, first, development, then operation. Under U.S. Internal Revenue Code regulations (Secs. 1.615.1 and 1.616.1) in effect at the time of this writing, which state that the "development stage" has been reached when "deposits of ore or other minerals are shown to exist in sufficient quantity and quality to reasonably justify commercial exploitation by the taxpayer," exploration in the technological sense may well continue after a mineral property has entered the "development stage" as defined for tax purposes. In many instances continued exploration, after reaching the tax defined "development stage," has disclosed additional reserves which justify a much larger, more efficient and more profitable operation than that which would constitute the minimum feasible. Even after a mine goes into production, continued ore search generally will increase the reserves, either justifying expansions in plant capacity or prolonging the life of the operation, but this work (actually "exploration") is normally considered, for bookkeeping and tax purposes, a part of mine development. Each exploration entity defines its own objectives in terms of acceptable mini- mum rate of return on investment for any deposit found and retained, and in terms of which commodities, and markets, are to be involved. For these reasons, exploration programs, and aims, will vary over a wide range, although all have the common objective of endeavouring to create new profit centers for the future. 5.1.2-EXPLORATION METHODS Exploration has evolved in the past several decades into a highly sophisticated and expensive endeavor in which large corporate entities, or subsidaries, normally are directed and staffed by highly trained exploration specialists. In some instances consultants, with expertise in a given field, are utilized to the benefit of such corporate groups. The "grasshopper" approach to exploration-searching only for outcropping minerals and/or investigating only mineral prospects offered by the discoverers of such outcrops has given us most of the past and present mines in the US., but this method is rapidly approaching the point of diminishing returns in areas that have been thoroughly prospected for currently marketable commodities. With

Jan 1, 1973

By R. W. Waytulonis

New exhaust control techniques and devices may be necessary to meet future diesel particulate matter emission standards in underground coal mines. This paper reviews conventional work practices and devices used to control diesel exhaust emissions, and new techniques being tested by the Bureau of Mines. Discussions will center on important work practices and on the function and efficiency of exhaust after-treatment devices. An industry/government cooperative research project to develop and test an exhaust after-treatment system for part 36 equipment is also discussed.

Jan 1, 1990

By Ralph Musick, Brian Briggs

The U1h Shaft Project is a design/build subcontract to construct one 6.1 meter(m) (20 feet [ft.]) finished diameter shaft to a depth of 321.6 meters (m) (1055 ft.) at the Nevada Test Site (NTS). Atkinson Construction was subcontracted by Bechtel Nevada(BN) to construct the U1h Shaft for the Department of Energy (DOE). The project consists of furnishing and installing the sinking plant, construction of the 321.6 m(1055 ft.) of concrete lined shaft, development of a shaft station at a depth of 297.5 m(976 ft.), and construction of a loading pocket at the station. The outfitting of the shaft and installation of a new hoist may be incorporated into the project at a later date. This paper will describe the design phase, the excavation and lining operation, shaft station construction and the contractual challenges encountered on this project.

Jan 1, 2001

By Lech Bolinski, Joe Shirley

Over two dozen Resin-in-Pulp (RIP) plants have been in operation in the fonner Soviet Union since the beginning of 1970. Currently approximately 50% of the gold produced in Russia, Uzbekistan and Kazakhstan, which equates roughly to 10% of the total world output, is recovered using the RIP technology. An alternative to activated carbon, ion-exchange resin has several advantages for the recovery of gold. Resins are less prone to clay or organic foul­ing and do not require thennal regeneration. They also have poten­tially higher loading capacities, faster adsorption kinetics, and are more resistant to abrasion. The original Russian RIP process was based on engineering expertise developed for uranium ore pro­cessing and has a few major drawbacks. The biggest problem is an 18-30 day resin stripping process, which results in a huge gold lock-up. The problem was recently overcome by the development of a new stripping technology which cuts the time to 12-24 hours. Currently, there is rather limited practical knowledge of the Russian RIP process in the West, but often Western mining com­panies developing gold mines in the fonner Soviet Union are hard pressed by their local joint venture partners to take a serious look into RIP. It is probably only a matter of time before one of these companies will cross Soviet technology with Western engineering and develop a modem RIP process as an attractive option to the current CIP and CIL technologies.

Jan 1, 1996

The Sage Mill Project w approved by Santa Fe Pacific Gold Corporation's Board of Directors in October 1994. The Sage Mill Project included a pressure oxidation plant designed and constructed to process refractory carbonaceous ore using fine grinding/autoclaving technology developed specifically to treat Twin Creeks ore. The project was constructed in two phases. The first phase was put into operation on May 5, 1997, just hours before the transfer of ownership to Newmont Gold Company occurred. The second phase started in October 1997. This paper reviews schedule, costs, scope changes, and methodology used on the project that spanned almost five years from project definition through commercial operation.

Jan 1, 1999