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By J. D. Steenkamp

Southern Africa has a history rich in the pyrometallurgical processing of ores. Two of the alloys produced are high-carbon ferromanganese (74?83 per cent Mn) and silicomanganese (59?67 per cent Mn and 14?31 per cent Si). The largest land-based manganese ore deposit in the world is based in the Northern Cape Province of South Africa. In 2010, 6.3 Mt of ore from the deposit was exported, mainly to China, Norway, Japan, and India, and an estimated 1.1 Mt beneficiated locally to produce manganese ferroalloys. In southern Africa the producers of manganese ferroalloys are Metalloys and Assmang, and of silicomanganese Transalloys, Mogale Alloys, and Match Corporation. Submerged arc furnace technology is utilized in the production of high-carbon ferromanganese (HCFeMn) and silicomanganese, applying the discard slag practice in both instances. The carbon content of HCFeMn is reduced using converter technology and that of SiMn using the Perrin process. Ninety per cent of the world?s manganese ferroalloys production is consumed by the steel industry. The consumption (and production) of manganese ferroalloys therefore closely follows worldwide steel production. From 2001 to 2010, the doubling of the worldwide production of manganese ferroalloys can be attributed to an increase in production capacity in Asia and Oceania, with the largest increase in the production of SiMn. Manganese ferroalloys produced in Asia and Oceania are mainly for the local market, with North America, Europe, Russia, and Turkey the major markets for alloys from southern Africa. The major challenges faced by the southern African manganese ferroalloy producers are increasing electricity tariffs and productivity of labour, which require a concerted effort by all parties involved to achieve a satisfactory solution. Keywords manganese ferroalloys, ferromanganese, silicomanganese, southern Africa, South Africa, manganese ore, high-carbon ferromanganese, refined ferromanganese, refined silicomanganese.

Aug 1, 2013

By Clarence Karr

THE BUREAU OF MINES is investigating methods for upgrading tar produced by the low-temperature carbonization of bituminous coal. This survey was undertaken to compile information needed for identifying the ether constituents of low-temperature tar. Physical properties are listed for 1,024 aromatic ethers. The compounds include cyclic and noncyclic, polyfunctional and monofunctional ethers with oxygen joined directly to either one or two aromatic rings. Alkyl groups up through butyl are included. The compounds are divided into 37 groups ranging in complexity from alkoxybenzenes to dibenzopyrans. Compounds containing aromatic ether groups are important constituents of the neutral oxygen components of low-temperature tar. For example, at Morgantown, W. Va., the Bureau of Mines has identified and determined the amounts of benzofuran, 2-, 3-, 5-, 6-, and 7 -methylbenzofuran, diphenyl ether, dibenzofuran, 2,3-dimethyldibenzofuran, and two other dimethyl-dibenzofurans in the neutral oil from a low-temperature bituminous coal tar (103, 104).3

Jan 1, 1962

Grouting is mainly used to improve mechanical properties or decrease the permeability of rock mass around civil and mining projects. The purpose of this paper is to present the most effective factors on grout penetration depth in rock mass. Such factors are essential for reliable estimation of the grout penetration depth and the expense for cement take of any grouting project. In this paper, about 50 different types of the relations presented so far by various researchers to estimate the depth of penetration in fractured rock were studied. The effective factors are classified to rock mass properties, grout properties, and operational factors. Results show that firstly, the discontinuities aperture and Lugeon value are respectively the most investigated factors of rock mass properties influencing on penetration depth. Secondly, the yielding stress, viscosity, and density of grout are the most effective factors of grout properties. Finally, grouting pressure has an intense effect among other operational factors. The investigations were also verified in Siah Bishe dam case study. Keyword: grout penetration depth, rock mass properties, grout properties, operational factors.

Feb 27, 2013

Background: Frictional ignitions continue to be a problem facing the U.S. underground coal mining industry. Many methane igni-tions are associated with the impact of mining machine cutter bits on quartzitic material (e.g., sandstone) during the coal-cutting process. Most ignitions result in small methane-air fireballs often only a few feet in size and limited to the cutter head location. However, under certain conditions, frictional ignitions can lead to larger methane explosions and/or fires with the potential for causing serious injury or death to the mining machine operator and other nearby miners. The requirements for a frictional ignition are a flammable volume of methane-air and an ignition source. This source is usually the hot streak caused by the frictional impact of the mining bit on hard rock, and the frequency of occurrence increases with increased bit wear. Another possible ignition source is the fric-tional impact of rock on rock during a roof fall.

Mar 1, 2008

By H. Nelisse, S. K. Patra, A. Natani, S. Rakheja

The current laboratory methods for assessing the vibration attenuation performance of seats involve repetitive trials with a number of human occupants, and raise certain ethical concerns. Moreover, the measurements with human subjects yield considerable variability in the data. Alternatively, several anthropodynamic manikins have been developed for effective assessments of the coupled seat occupant system [1]. The effectiveness of a manikin in predicting the response of a coupled seat-occupant system lies in its ability to reproduce the biodynamic response of the seated human body in terms of force-motion relationship at the body-seat interface, such as apparent mass (APMS). A number of prototype manikins have thus been developed on the basis of biodynamic characteristics of vertical vibration-exposed seated occupants of different body masses in the vicinity of 5th, 50th and 95th percentile male population. This study concerns with the analysis of a passive prototype manikin to enhance its ability to reproduce the idealized APMS response characteristics of the vibration-exposed seated human subjects defined in ISO-5982[2] for mean body masses of 55, 75 and 98 kg. Methods The APMS responses of a prototype anthropodynamic passive manikin were thoroughly characterized in the laboratory under different excitations and body mass configurations. The manikin was designed with sufficient flexibility to configure mechanical-equivalent models corresponding to seated body masses of 55, 75 and 98 kg, by adding/removing specified masses and springs (Fig. 1). The manikin, configured for a specific body mass, was positioned on a rigid seat without a backrest, which was fixed to the force platform of a whole-body vertical vibration simulator. The simulator was programmed to synthesize random vertical vibration with flat acceleration power spectrum in the 0.4-20 Hz frequency range with two different magnitudes: 1 and 2 m/s2 overall rms acceleration. The total static and dynamic forces of the manikin to and the seat were measured using the force platform, while a single axis accelerometer was installed on the seat pan to measure acceleration due to vertical excitation. The measured data was appropriately corrected for the rigid seat inertia force, and the apparent mass [ ]

Jan 6, 2006

By W. Valderrama, D. G. Almond

Operation of large SAG mills requires a change in the conceptual approach to grinding processes. The traditional energy consumption criteria are now enhanced with new criteria derived from the mechanical dynamics of the mill load. This new approach demands instrumentation capable of providing accurate information about the load movement and the ratio of balls and ore inside the mill. This paper discusses two new performance enhancing tools available to meet these needs.

Jan 1, 2004

By V. T. McLemore

Petrographic analysis of rocks is traditionally performed with optical microscopy using thin sections and point counting. However, this does not provide accurate mineral proportions for sedimentary, volcanic, and soil-like material, because rock fragments, groundmass, and matrix are not identified as specific minerals. In addition, groundmass phases in volcanic rocks can be too fine to identify individually, and making thin sections of intact soil-like material is difficult because much of the material is not well cemented. ModAn is a normative calculation that estimates modes ??by applying Gaussian elimination and multiple linear regression techniques to simultaneous mass balance equations? (Paktunc, 2001) and allows location-specific mineral compositions to be used. One of the features of ModAn that makes it appropriate for this study is that it can model one of several sulfide minerals. Mineral compositions for Questa minerals were determined from electron microprobe analysis and entered into ModAn. Then by combining and normalizing results, bulk quantitative mineralogy can be determined using ModAn, petrographic observations, electron microprobe analysis, clay mineral analysis, and the whole-rock chemistry of the sample.

Jan 1, 2009

By G. L. Smith

This paper introduces and defines the concept of a linkage between long-term planning parameters (?global assumptions?) and possible future world views as conceived in scenario planning. Scenario planning, the tool that is used to arrive at plausible future worldviews, is described in the context of the platinum industry. The interpretation of the scenarios into long-term planning parameters is made, followed by an illustration of how the long-term planning process has been adapted at Anglo Platinum to include the notion of uncertainty.

Jan 1, 2008

By Robert C. Steckley

A study of joints in Marathon County, Wis., was made to determine the orientation of regional paleotectonic stresses and to develop a method of using optical diffraction analysis (ODA) in studying joint orientations and spacings. Standard geologic and petrofabric techniques employing the use of a geologic compass and a Schmidt net were used in gathering, describing, and reducing joint orientation data. Analysis of selected outcrops with ODA indicates that ODA can be applied to study both joint orientations and spacings. ODA is shown to be a rapid method that can be used to complement standard petrofabric techniques, especially in the study of joint spacings.

Jan 1, 1972

By M. Schafer

The 20 foot diameter cast-in-place tunnel lining for Phase 3 of the Mill Creek Tunnel (MCT-3) has been completed. This paper will summarize aspects of liner design and address the construction approach in placing the liner in areas of tunnel that experienced crown overbreak. Tunnel lining production rates, installation procedures and form buoyancies experienced during concrete placement will also be presented.

Jan 1, 2008

The annual reports of the supervising engineers of the seven sections comprising the Mining Division are assembled in the following pages and constitute the annual report of the division. In planning activities, the aim has been to adapt the work to changing conditions and needs of the mining industries and to avoid becoming bound to any particular type of investigation when others are found to be of more pressing interest.

Jan 1, 1939

By E. L. Garton

Michigan is becoming one of the important oil-producing States of the country. The amount of crude oil produced within its boundaries has increased from only 4,000 barrels in 19253/ to nearly 16 million barrels in 19935.4/ The Bureau of Mines method of crude-oil analysis and classification-indicates that the oils from the several producing fields are predominantly paraffin-intermediate-base, wax-bearing crudes. In general, they will yield 25 to 35 percent of highly paraffinic gasoline and about the t- me amount of kerosene and gas-oil combined, 7.2 to 15 percent of lubricating oil stock, and 20 percent of residuum with a carbon residue or about 6 to 7 percent. In addition, there appears to be some correlation between certain properties of the crude oils and both the geographical location and geological structure of the oil-producing areas within the State. These general conclusions are based on the analytical data presented in this report, which is one of a series of papers that record the general characteristics of crude oil from the many producing fields of the United States. This report discusses briefly the oil fields of Michigan and the characteristics of the crude oils produced from them. The analyses of 15 samples are given. These samples were obtained from 13 fields in 9 counties in the lower peninsula and represent crude oils produced from the Berea sandstone, Upper Traverse and Traverse limestones, and the

Jan 1, 1937

By T. Markus, K. Hilpert

Discharge vessels of advanced light sources are made of translucent polycrystalline Al2O3(PCA).These tubes contain salt mixtures, which essentially consist of metal halides. The salt mixture is present as a melt at the coldest spot of the vessel under operating conditions and vaporizes partly. The temperatures of the coldest spot range between 1200 K and 1300 K, depending on the lamp performance. The maximum wall temperatures range up to 1500 K and for special purposes up to1700 K. Important constituents of the melt are alkali halides AX (A = Na, Cs, X= Br, I) and rare earth metal halides LnX3(Ln = Dy, Ho, Tm). Severe corrosion attack on the wall material is observed in the PCA discharge vessels. The aim of this work is to elucidate the corrosion mechanism. Annealing experiments under well defined temperatures were carried out in order to understand the complex chemical corrosion processes. Two different annealing vessels were used, one for experiments under isothermal conditions with a temperature of 1473 K and one for experiments with a linear temperature gradient from 1450 K to 1600 K. The vessels were filled with salt mixtures of different compositions and annealed for 1000 h. The corrosion attack was characterised by XRD, analytical electron microscopy, high temperature mass spectrometry, and chemical analysis of the salt melts. The results of our investigations show that the corrosion attack is caused by vapour species and by the salt melt. The most severe corrosion is observed in vessels filled with mixtures of alkali halides and rare earth metal halides. No corrosion of the alumina is practically observed if pure alkali halides or pure rare earth metal halides are present in the annealing vessel. Keywords: thermodynamic, corrosion, lamps, metal halide salt

Jan 1, 2004

By Lise Chénard

El presente texto señala los lineamientos del proyecto REFORMIN, así como su repercusión en la dinámica de promoción de la industria minera. REFORMIN surge en el 2001 como un proyecto bilateral entre Canadá y Bolivia, cuyo financiamiento proviene de la Agencia Canadiense de Desarrollo Internacional (ACDI). Su finalidad es apoyar al Viceministerio de Minas, facilitándole el acceso a la pericia canadiense para lograr una gestión más sana y eficaz de los recursos minerales del país. Para ello, se basa en los principios fundamentales tales como: mejora de la gestión del medioambiente minero, apoyo a la prevención y gestión de conflictos sociales en las comunidades mineras, a los mineros artesanales y a la promoción de los recursos minerales del país, -en tanto benefician al desarrollo de la industria minera en un contexto de mercado globalizado.

Apr 22, 2003

By L. B. Hales

Image analysis for feed belts and flotation has been used for over 20 years. It has been shown to aid in the modelling and optimization of Sag Mill circuits, and any improvements in the image analysis result in improvements in the model for control. Using a laser to measure the height-profile of rocks on the conveyor has been shown to increase the accuracy of the size classification. We have developed a system using two cameras in a stereoscopic configuration to provide height-profile measurement without the added expense and safety concerns of using a laser. Additionally, we have developed a novel technique for calibration of the system, using artificial intelligence techniques to optimize the model fit by adjusting the image analysis tuning parameters to values resulting in the best classification.

Feb 27, 2013

By Forrest T. Moyer

The safety record of the coal-mining industry in 1968 worsened appreciably .in fatality experience but was slightly better in nonfatal-injury experience. Work fatalities in 1968 totaled 311 and occurred at a frequency rate of 1.33 per million man-hours or worktime. The fatality total was 89 higher, and the rate of occurrence was 45 percent higher than the corresponding figures of 222 fatal injuries with a frequency rate of 0.92 in 1967. The worsened fatality record in 1968 resulted primarily from two major disasters (a single accident which results in the death of five men or more) which killed 87 men, nine in one and 78 in the second. The total of 9,639 nonfatal injuries was the lowest annual figure in complete records back to 1930. The frequency rate of 41.12 nonfatal injuries per million man-hours of worktime for 1968 was the second lowest annual rate of occurrence. The severity rate of all injuries, 10,513 days lost or charged per million man-hours, and the average severity, 248 days lost per injury, in 1968 were the worst annual data in the series started in 1944. Total worktime of 234.4 million man-hours and coal output of 553.3 million tons in 1968 were, respectively, 3 and 1 per- cent lower than in 1967.

Jan 1, 1972

By Trevor Harris, Martin Harris

"This paper evaluates the effect of grind size on the flotation performance of a platinum ore from the UG2 reef of the Bushveld Igneous Complex, in South Africa. The study was conducted on the Mintek Flotation Pilot Plant Facility, located in Johannesburg, and represented a thorough evaluation of the application of the flotation modelling methodology developed jointly by the University of Cape Town and the Julius Kruttschnitt Mineral Research Centre at the University of Queensland through the AMIRA P9 Project. A simulation model of the pilot plant data was successfully implemented, providing a set of circuit modelling parameters that appeared to be both consistent and well correlated to measurable characteristics of the ore and the pilot circuit operating conditions. The findings indicate that the methodology that was used could well provide a useful framework for developing optimisation criteria for industrial flotation circuits in combination with appropriate feed grind size and regrind size targets.INTRODUCTIONIt has long been recognised that the size distribution of an ore is one of the most important factors in the determination of the performance of a flotation process. It therefore follows that the optimisation of a flotation plant cannot be considered without due recognition of the interdependence of this process with the process of comminution. There are numerous qualitative guidelines for the selection of an optimum grind target for a particular operation. Mineralogical analysis can readily provide information on liberation as a function of grind, and the desirable particle size range for optimum mineral flotation is well established in both theory and practice (see for example Trahar, 198 1). For some operations, meeting these two criteria simultaneously is relatively simple. For the majority of operations, such mineralogically “easy” deposits, if they ever existed, have long been exhausted, and the optimum grind represents a highly complex compromise between liberation and overgrinding of both desirable minerals and gangue. This is particularly true for circuits that include regrind stages, where both primary and secondary (and sometime even tertiary) grind targets must be specified. As has been pointed out in a recent paper by Bazin and Hodouin (2001), there is little or no information in the literature to assist plant engineers in the selection of optimum grind targets for complex ore deposits, so current practice is primarily based on rules-of-thumb and experience. This problem is further compounded by the fact that once grind targets have been selected for a particular operation, the assessment and adjustment of these targets based on plant surveys is extremely difficult, time consuming and expensive, and is often not attempted unless the plant significantly underperforms relative to expectation. It is therefore clear that the development of a practical quantitative approach to this problem is a high priority for flotation research and development studies."

Jan 1, 2002

By G K. Jorkenson

The SABREX Blast Modelling Program was developed joinlly by the companies of the ICI Explosives Group. of which C-I-L Inc. is a member. SABREX (Scientific Approach to Breaking Rock with Explosives) is a modular computer program which incorporates new technology with a number of tested programs that have been in use world wide.

Jan 1, 1989

By R. H. Sprute

This report describes Bureau of Mines laboratory test results in electrokinetic dewatering and consolidation of metal-mine tailings. Tailings were placed in 0.3-cubic-foot Plexiglass models, and dc potential was applied until dewatering ceased. Time-oriented measurements of water removal, changes in resistivity, and power consumption were recorded during the dewatering process. Dewatered material was tested for moisture content and density. Equipment and procedures were developed to optimize the method for unclassified mill tailings from a particular mine in the Coeur d'Alene, Idaho, district. Results indicate the method to be highly effective in dewatering and consolidating this material.

Jan 1, 1974

By J. Böhlke, B. Friedrich, E. Hecker

The legislation for the disposal of heavy metals contaminated substances is still going to be tightened up in the future. The main criteria for the utilization or deposition of these residues are the content and the water solubility of these metals. Through this, the use of slags from the lead-and zinc-industry in road building may become limited or even not possible at all. From an economic point of view this would lead to Pb/Zn losses and costs for safe dumping. This paper investigates the feeding of the reducing agent via hollow electrode DC smelting and the yield of metal reduction. After carrying out thermodynamic calculations, the process window conditions for electric-arc furnace tests were determined. Doing this, the zinc could be reduced, evaporated and recovered as an oxidic intermediate product flue dust, while the lead was present either in flue dust or in metallic form. The zinc content in the final slag could be reduced by up to 90%. The slag product has undergone an eluation test which allows it to be used as building materials. Keywords: zinc reduction, lead reduction, hollow electrode, slag treatment, electric arc furnace