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By J. E. Litz

The hydrometallurgy review did not arrive in time for publication in the May issue. 1992 was not a banner year for hydrometallurgical installations or new hydrometallurgical developments. Installation of copper solvent extraction/electrowinning circuits were under construction or began operation in Nevada (Yerrington ), Arizona (SilverBell), Chile (Copiapo and Escondida), Peru (Toquepala and Cuayone) and Australia (Girilambone). These installations will produce more than 100 kt/a (110,000 stpy) of cathode copper. Several new heap leach gold facilities using conventional technologies were announced or were put into operation. New technologies undergoing widespread testing include biological oxidation of low-grade ores in a heap leach mode and evaluation of new agglomerating agents.

Jan 1, 1993

By S. E. Phillipson

Underground mine mapping is a critical component of understanding the controls on ground instability. Many relatively localized examples of ground failure are associated with geologic features, such as faults, joints, compaction zones, or sedimentological transition zones. In contrast, long-running, directional roof falls are associated with regionally directed horizontal stress fields, which are induced by tectonic plate interactions in the earth?s crust. When stress-related features are distinguished from geological features, underground mapping can be an effective method for inferring the direction of horizontal stress at individual mines. Comparisons with data compiled in the World Stress Map confirm that underground mapping can be a valid method for determining the orientation of maximum principal horizontal stress at a variety of scales, ranging from individual mines to an entire mining district or coal basin. Comparisons are presented between the maximum horizontal stress directions inferred by MSHA?s Roof Control Division through underground mapping and the azimuths of maximum horizontal stress in the World Stress Map database for North America?s Pennsylvanian-aged Appalachian, Illinois, Black Warrior, and Arkoma Basin coal fields. The comparison indicates that azimuths are similar for both data sets, even where variations in the direction of horizontal stress are present. It is interpreted that inconsistencies in direction are attributable to near-surface affects such as deeply incised stream valleys, or to fault zones that represent heterogeneities in the crust.

Jan 1, 2009

By Russell G. Shomperlen

Grinding mills in excess of 5 meter diameter and 3500 kilowatts per mesh are putting new demands on big gears. This paper returns to the basics of ring gear design beginning with the fundamental power formulas specified by AGMA. Specific emphasis is given to those elements in the rating equations which require closer attention as gear diameters and transmitted power increase. Strict process control in the manufacture of the gear blank is also stressed. Finally, the writer offers a guide to proper installation, lubrication and maintenance.

Jan 1, 1981

By M. G. Bakker, D. D. Murphy, D. R. Spears

The US Bureau of Mines studied the mechanism of shear flocculation of silica with stearic acid. At pH 6 and 12, shear flocculation of silica was not observed with the addition of up to 4.5 x 10-4 M (5 lb/st) stearic acid. However, in the presence of 0.1 M NaCl at pH 6, shear-flocculation was observed at stearic acid concentrations = 10-4 M (22.5 lb/st). Adsorption of stearic acid on silica was studied using stearic acids spin-labeled with a doxyl group. The presence of the spin-labeling group did not greatly affect the shear flocculation properties of stearic acid. Adsorption of labeled stearic acid on silica was measured as a function of surfactant concentration with electron paramagnetic resonance (EPR) spectroscopy and gas chromatography (GC). The GC results indicated that the stearic acid was predominately adsorbed on the surface at concentrations above 10-4 M. From the EPR spectra, the formation of aggregates of stearic acid was apparent at concentrations of approximately 10-5 M (22.5 lb/st). The results are discussed in terms of a possible mechanism for shear flocculation.

Jan 1, 1995

By L. M. Gochioco

The Seismic Interactive Interpretation Workstation (IIW) integrates various sets of geophysical and geological data to form a network of information which is stored in a database. Computer models are generated from known drillhole information and later correlated with the processed seismic data. Seismic color processing adds another dimension to the interpretation process. Complex trace attributes provide better definition of subtle features not easily observed from black and white sections. Utilizing the computer workstation, the explorationist gains valuable insight and conducts more intelligent interpretation of seismic data through a more comprehensive network of data analysis.

Jan 1, 1989

Caterpillar and Fortescue Metals Group have moved forward with the delivery, installation and support of a complete Cat MineStar System at Fortescue?s Solomon iron ore mine in the Pilbara region of Western Australia. The complete technology suite was implemented for the first phase of Solomon, the 20 Mt/a (22 million stpy) Firetail manned mine, in October 2012. As part of an autonomous mining solution for phase two, the 40-Mt/a (44-million stpy) Kings Mine, eight Command for hauling Cat 793F CMD trucks were commissioned and commenced operations in the second quarter of 2013. The mine plan calls for a progressive ramp up to 45 autonomous trucks during the next several years. In addition, other Cat MineStar System capability sets, Fleet, Terrain, Detect and Health, are being used across the mobile equipment fleet, including support equipment and light vehicles. Working closely with Fortescue and its mining contractor, Leighton Contractors, Caterpillar and the Cat dealer in Western Australia, WesTrac, are providing a full solution for managing, operating and supporting Cat MineStar System and Command for hauling. The greenfield Solomon Mine has brought together the skilled team from Caterpillar, Fortescue, Leighton Contractors and WesTrac to deliver an efficient, cost effective autonomous mining solution.

Nov 1, 2013

By C. Jardine

The concept of the system is to minimize costly unscheduled breakdowns of equipment by replacing components earlier than their "life" expectancy. Periodic unit services are scheduled according to pre-set constraints. Service sheets are generated by matching a job and component master listing based on assigned cyclic component lives. The system can provide accountability of all man-hours reported and history information can be selectively retrieved. By reducing unscheduled equipment shutdowns, this system allows for better utilization of manpower and an overall improvement in equipment reliability and availability.

Jan 1, 1979

By R. W. Salmi

The authors discuss the cooperative efforts by Minnesota Ore. Operations and Research; from the earlier development, testing and installation of fine shear screens in the Minntac Step III concentrator to the most recent testing and operating data that has resulted in the installation of Derrick Multifeed sandwich deck screens in Minntac Steps I and II. Pilot-plant test results that were obtained at the Coleraine, Minnesota Research Laboratory are also reported and demonstrate the effects of feed rate and feed percent solids on sandwich screen performance with two sizes of Minntac fine screen feed.

Jan 1, 1984

By A. L. Frank, Benton

INTRODUCTION The selective sensitivity of plastic nuclear track detectors (PNTD's) to low energy 4He particles in an environment which also contains gamma and beta radiations has made these detectors prime candidates for the dosimetric measurement of the concentrations of radon and its daughter products in mine air. Their passive, integrating mode of measurement, small size, low weight and inexpensiveness are attractive characteristics for large scale personnel dosimetry. The detectors can be used in either active or passive dosimeters. In active devices, the PNTD is placed in close proximity to a sampling filter. The filter collects, from a calibrated air flow, all the daughter nuclei which are in suspension. As the daughter nuclei pass through the decay chain, through 214Po, a fraction of the 4He particles emitted are registered as latent tracks in the plastic. In passive devices, the PNTD is placed in direct contact with the ambient air containing the radio-nuclei concentrations to be determined. The active dosimeters have the advantage of excellent sensitivity, and the measured track densities yield very close approximations to accumulated Working Level (WL)** exposures. They have the disadvantage that the simplicity of the passive PNTD is lost, since a battery-driven constant flow-rate air pump is a necessity. The passive dosimeters are simple in construction and use, but they have the disadvantage that WL exposures are not directly measured and certain assumptions concerning radon and daughter equilibrium conditions must be made in determining WL exposures from the measured track densities. Also the sensitivities, in track densities per Working Level Hour (WLH) exposure, are much less than for active dosimeters. Dosimeters of both types have been investigated. Passive devices have been tested extensively both in the laboratory and in mines. Active devices have been laboratory tested. In our earlier measurements, cellulose nitrate plastic detectors were used exclusively, since this material had the highest sensitivity of the PNTD's then in use. When the properties of CR-39 plastic were discovered (Cartwright, 1978; Cassou and Benton, 1978), this material was used, where possible, to take advantage of its superior sensitivity. The results of our earlier work have previously been published (Frank and Benton, 1977). * Research sponsored by the Bureau of Mines, U.S. Department of Interior, under Contract No. JO-188003. ** A Working Level is defined as any combination of the short-lived radon daughters containing 1.3 x 105 MeV of potential 4He-particle energy per liter of ambient air. PASSIVE DOSIMETRY In the earliest testing of PNTD's for passive WL dosimetry, a single strip of cellulose nitrate plastic was used to determine the total cumulative 4He-particle activity in the air of simulated uranium mine and uranium mine environments (Rock, 1968; Rock [et al], 1969; White, 1969). The measurements yielded a close relationship between track densities and WL exposures in a controlled, static environment, but poor accuracy in the active mine tests. It was assumed that equilibrium differences contributed largely to the variations found. The response of PNTD's to airborne 4He-particle emitters, derived by Lovett (1969), demonstrated that detectors such as cellulose nitrate, which has a sensitivity cutoff at 4He-particle energies below the emission energies of radon and its daughters, are equally sensitive to the activity concentrations of radon, 218po(RaA) and 214Po(RaC'). Since radon does not contribute to WL as it is defined, and since, under normal ventilated uranium mine conditions, the radon activity constitutes about 40% to 70% of the total 4He-particle activity, the WL exposures calculated from measured track densities are very sensitive to the particular radon daughter equilibrium conditions. Also, the detector does not weight the individual daughter activities in proportion to their importance to WL. The equation for WL is WL = 0.00103C2 + 0.00507C3 + 0.00373C4 (1) where C2, C3 and C4 are the activity concentrations of RaA, RaB and RaC-C', respectively, in pCi/[L]. The detector leaves C3 unmeasured and weights C2 and C4, equally. [This problem has been approached by Domanski et al (1975, 1979), for some non-uranium mines, by measuring equilibrium conditions throughout the mines to determine a mean value for A, the inverse of the Working Level Ratio (WLR = 100 WL where C1 is the activity of radon-222 in pCi/[L].) The distribution of values allowed Domanski to determine probable errors in calculating WL exposures from track densities. However, measurements of equilibrium conditions in U.S. uranium mines (Breslin et al, 1969; Holub and Droullard, 1978) indicate that this method would not be accurate enough for uranium miner personal dosimetry.] A two-element dosimeter was designed at our laboratory to compensate for equilibrium variations. The first element is a radon detector; the second is a detector for the total 4He-particle activity in the ambient air, just as in the single element dosimeters cited above. The addition of the radon detector allows the equilibrium conditions for the individual nuclei to be determined, given certain assumptions concerning the interrelationships between the nuclei concentrations in mine air. The two detectors and the problems involved in calculating WL exposures from their measurements are discussed below.

Jan 1, 1981

By Lawrence P. Kennedy

The Lynne deposit is a volcanic-to volcaniclastic-hosted, Zn-Pb-Cu-Ag orebody located in the early Proterozoic magmatic terrain of northern Wisconsin. As of February 1991, core drilling has partially delineated a multi-million ton, near-surface, disseminated to massive sulfide deposit. The deposit is hosted by a gently dipping sequence of fragmental rhyolites, felsic tuffs, less abundant dacite to andesite flows, and fine-grained volcanic sediments. The deposit is broadly conformable With the host rock stratigraphy, but the ore zones thicken and coalesce in the central part of the deposit.

Jan 1, 1991

ShouSteel Mining Ltd., a subsidiary of ShouSteel (Group) Co., was founded in 1959 and is located in QianAn City in Hebei Province, China. ShouSteel?s pelletizing plant uses iron ore as a raw material combined with limestone, dolostone, or olivine, with bentonite as a binder. After mixing the raw materials and forming them into small, spherical balls, ShouSteel then fires pellets in kilns for hardening. The company sells the finished pellets as raw materials for blast furnaces used to produce industrial metals such as iron. ShouSteel?s handling capacity is approximately 24.5 Mt/a (27 million stpy) of ore. The company?s production capacity is 3.2 Mt/a (3.5 million stpy) of oxide pellets and 560 Mt (650 million st) of sinters. Until recently, ShouSteel Mining had not replaced its electronic scales in its series of ingredient chambers. Because of the wear and tear on these older scales, the weighing system began to encounter regular problems. The company experienced a high failure rate from the integrator, an unstable signal, weak anti-interference ability and low accuracy. ShouSteel also found that spare parts required during repairs were consistently high in cost and that system calibration was becoming increasingly frequent.

Jan 1, 2012

By J. W. Currier

The compositions and natures of the materials charged to a blast furnace, as well as their respective distributions within the furnace, are known to int1uence furnace performance. However, fifteen years ago, there was little reason to believe that any significant variation of these parameters had been overlooked. Nor was there any particular reason to believe that olivine might be a particularly useful raw material for blast furnace applications.

Jan 1, 1989

By Ian Mitchell, Peter Faganl, Paul Haddad, Rob Dunne

During the gold cyanidation process, cyanide can be lost from the leachate by various chemical routes. The products of these cyanide losses include base metal cyanide complexes, thio­cyanate and cyanate. These losses are particularly important when treating pyritic or cupriferous ores since the two most sig­nificant cyanic ides, in order of importance, are sulfides and cop­per bearing minerals (I). Cyanidation of pyritic minerals results in the formation of thiocyanate. The problems caused by cyanide soluble copper minerals are well known to the gold processing industry and have been reviewed by several authors (e.g. 2, 3). An important consider­ation, especially with a number of more recent leaching tech­nologies, is the effect of the CN :Cu mole ratio, R, on the gold leaching kinetics. In order to efficiently leach cupriferous ores, it is important that R is maintained at a level that allows suffi­ciently rapid leaching without excessive use of cyanide. The optimum value for R in a fixed leaching system would appear to lie between 3 and 4. This is based on the early observations that the leaching rate is very slow when R is below 3, with a rapid increase in the leaching rate above 3 (2, 3,4). The leaching rate increases gradually when R is greater than 4 (4). The major Cu(I)-cyanide complex in this range of R values is the [Cu(CN)J]2· species. It has been postulated that leaching occurs due to either uncomplexed cyanide or the fourth ligand in [Cu(CN)4]3·, since the stepwise formation constant for this complex is very small (2, 3). An additional consideration when leaching cupriferous ores is the oxidation of cyanide by Cu(II) minerals, resulting in the formation of cyanate. It has also been reported that both sulfide minerals (5) and activated carbon (6, 7) catalyse the oxidation of cyanide to cyanate. From the above discussion, it is important for the leaching con­ditions to be carefully controlled when treating pyritic and cuprifer­ous ores in order to achieve efficient and economically viable leach­ing. For example, large concentrations of thiocyanate in the leachate would reveal large cyanide losses and thus indicate the need for a pretreatment step to oxidize the sulfides. Alternatively, a low R value would indicate slow leaching kinetics and consequent low gold recoveries, indicating the need for increased cyanide dosage.

Jan 1, 1996

By G. Davey

High speed stirred milling is a relatively new method of grinding in the metalliferous process industries. However it has been it has been in wide spread use in the industrial mineral field for over 30 years for various minerals. Many existing metallurgical operations are looking to maximize economic return from existing deposits, requiring new thinking and technologies. The operating experience of two existing copper operations will be covered to show the effect of the introduction of the Metso Stirred Media Detritor (SMD) a new type of high speed stirred mill. Both operations have derived significant metallurgical benefits from the introduction of this new technology. The benefits and process difficulties are covered and explained.

Jan 1, 2003

There are many risks associated with the storage of nuclear or other toxic wastes. One of the major risks is the escape of material from the repository. No matter how well a storage facility is engineered, the potential escape of dangerous material must be studied. This kind of study will include some estimation of the "travel path" of the particles. The travel path of a radio-nuclide particle will depend on the geological and hydrological parameters of the surrounding rocks. These parameters must be estimated from a limited number of samples available within the study area. Any estimation will -of necessity -contain a certain amount of uncertainty or "estimation error". This uncertainty will be carried through to the analysis of potential movement of particles, so that the estimated travel path itself will be subject to some error. This paper discusses an approach which may lead to a quantification of the uncertainty on the predicted travel path.

Jan 1, 1989

By L. E. Allen, J. F. Abel, D. R. Morgan

The Waste Isolation Pilot Plant (WIPP) is a geologic repository for disposal of transuranic waste and is operated by the U.S. Department of Energy (DOE). The repository is located at a depth of 655 m in the Permian age salt beds of the Salado Formation, 40 km east of Carlsbad, NM. A key component in the design of the WIPP repository is the installation of concrete structures as panel seals in the intake and exhaust drifts after a panel has been filled with waste containers. The DOE has proposed several panel closure design modifications to the EPA. EPA approval of the changes is required since the details of the designs are specified in EPA’s final rule as a condition for WIPP certification. The Environmental Evaluation Group, in its role of providing technical oversight on the WIPP project, has evaluated the proposed modifications. An analysis of this evaluation is discussed.

Jan 1, 2003

By Edmond O’Donovan

Mooranbah North is a new greenfield project in Australia's Bowen Basin that is projected to produce 4 mtpa of hard coking coal from a single longwall. Located in Central Queensland in Australia's northeast, this is one of Australia's main coal producing regions. From the outset, Mooranbah North's approach to equipment selection has differed markedly from that usually taken in the mining industry, and the conveyor industry in particular. Until recently, no performance requirements have been placed on conveyor equipment suppliers. This arose from a practice of purchasing components in an ad-hoc manner from a variety of sources, and the mine then configuring the system. More recently, single source supply has been adopted as a means of obtaining some performance guarantee, usually expressed in terms of system availability. Unfortunately, the term "availability" has a multitude of definitions, particularly in the underground coal sector. A conveyor availability of 98% is a common goal but this rarely means the conveyor must operate 165 hours/week, 52 weeks/year. There are mines that have one maintenance shift for each production shift and claim availability of 100%. What is meant is that no down time is logged to the conveyor during the hours that it is wanted. This "generous" definition of availability would not be tolerated in many industries and nor should it. Unfortunately, a true definition of availability, such as is applied to steam turbines in the power generation industry, is not particularly helpful. Five day/ week operations would immediately face a 28% penalty against 7 day rosters, and there would be no sensible manner in which weekend maintenance could be incorporated into the availability formula. The approach adopted by Mooranbah North was to specify a period of "Failure Free Operation," which would be followed by a maintenance period. This

Jan 1, 1998

By G. P. Hand

The graphite industry as a whole has gone through many changes over the years. Most of the graphite used in major applications since the turn of the century were basic natural or electrode by-product synthetic materials, processed using simple crushing, screening, or grinding techniques. In the mid 1970's new thermal technology was developed which changed the face of the .graphite industry, and opened up a panacea of new products and capabilities. Materials produced through this new technology have helped revolutionize new products and processes in industries including automotive, batteries, fuel cells, electronics, iron, lubricants and steel. This paper outlines the continued improvements in those industries as well as the as well as the outlook for new technology in this rapidly changing area.

Jan 1, 1997

By Jon C. Jenkins

In order to plan the most efficient mine installation, a company should take advantage of all available information and tools. One of the first factors of a coal reserve that needs to be determined as accurately as possible is the quality of coal the mine will have access to during the life of the installation. With the aid of many types of well logs and computor analysis, we are investigating several methods of log correlation to determine such data as moisture, ash, sulphur, and BTU on an in place basis. It may be possible to determine this data more accurately in this manner than by using diamond drill cores for analysis and thus allow for a more profitable mine installation. The production of an underground mine is based on many factors, two of these being roof control and line water, where present either in the roof or coal seam. Using many of the same logs obtained from reserve and active mine areas, we have attempted to determine roof and floor characteristics such as strength, lithology, and moisture properties. Using data obtained from this program, we will make comments on possible length of bolt to be used, possible mining width, and pillar size as they would pertain to these reserves and active mine areas.

Jan 1, 1969

By E. S. Bianchin

The more complex control needs of today's mineral processing plants combined with ever-changing digital technology have brought numerous improvements to process control systems. This paper discusses recent advancements in distributed control systems (DCS) which facilitate the implementation of process plant automation. Some of the topics of discussion include integrated function controllers, weigh scale and analyzer interfacing, operator interfacing, personal computers, process information management and process plant management.

Jan 1, 1988