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By Ulrich Neumann

Mining coal by employing a method called longwall mining is gaining more and more popularity in the United states since it offers many advantages over the conventional deep mining methods. Those advantages are a higher productivity, an almost total extraction of the mineral since no pillars must be left behind for support, and an increase in safety since the personnel are protected by the shield supports and rarely have to work near unsupported, exposed root. However, on some longwalls, the dust levels liberated by various equipment such as belt conveyors, chain conveyors, crushers, longwall shearers, and moving shield supports can exceed the maximum permissible limits and therefore have an adverse effect on productivity. Many attempts have been made over the past years to reduce the dust liberation by changing designs, installing various types of sprays or scrubbers, treating the mine water with wetting agents, or even using foam to catch dust before it becomes airborne. In the year 1984, the Bureau of Mines awarded Eickhoff Corporation a contract to demonstrate a water-jet-assisted cutting system for the multiple purposes of reducing dust levels, improving bit consumption, and increasing material size. During the previous phases of this contract, various trials were conducted aimed to design, build, and test d shearer loader to meet the objective of the contract. In the early stages of the research program, it was expected to see a reduction in the overall power consumption of the machine due to the fact that the high-pressure water jet would pre-cut the mineral in front of the bit. This, in turn, would then reduce the bit wear. Since there is less cutting action performed by the bit, a reduction of the dust liberation and a reduction of product fines was sought.

Jan 1, 1991

By Mario Bendezú Chalco

La estimación de un mineral contenido en un yacimiento minero es un paso importante en el proceso de explotación. En este sentido, el texto señala la valoración de depósitos masivos de mineral a partir de la técnica del "Krigeage", la cual determina un estado lineal óptimo y calcula no solo el error cometido en la estimación, sino minimiza el error estimado. Asimismo, para lograr la aplicación del marco teórico señalado, se describe un sistema de programas compuesto de rutinas en Algol-W y Fortran IV, desarrollándose una interacción entre ellas.

Nov 20, 1978

By Joaquim Luiz Monteiro de Barros Júnior

Este trabalho tem como objetivo principal apresentar de forma didática e com um exemplo prático a viabilidade da instalação de turbinas TRT, com a finalidade de gerar energia elétrica em plantas siderúrgicas.

Oct 30, 2017

By Jamal Rostami, Asok Ray, Samer S. Saab Jr., Wenpeng Liu

Ground instability, such as roof or rib failures, is one of the most serious and frequent safety hazards that occur in underground mining, tunneling, and underground construction. The ground-related parameters and features of interest, in assessing roof or rib failures, are location, frequency, and orientation of the joints, voids, as well as rock-strength. These parameters are the main components of rock mass characterization that offers effective strategies for ground support, which, in turn, allow one to mitigate the risks related to ground instability. The main objective of this study is to determine the location of joints and classify rock-strengths by analyzing the drilling data recorded from an instrumented roof bolter while drilling for rock bolt installation during the operational cycle. For this purpose, computer programs based on updated pattern recognition algorithms were developed for joint-detection and classification of rock types to offer an estimated strength. This paper briefly introduces ongoing research on joint detection, especially for joints with an aperture less than 0.125in (3.175mm), by employing an instrumented roof bolter in controlled environments. To improve the capability and precision of joint detection programs in detecting the joints from the drilling data and reducing the number of false alarms, many laboratory tests with various simulated joints and rock-strengths were carried out at a J.H. Fletcher & Co. facility. This paper reviews testing procedures, data analysis, updated algorithms used for joint detection, and discusses the latest round of testing in samples with simulated joints at various angles along the borehole.

Jan 1, 2017

By Józef Czemecki

Polish copper concentrates are characterized by high levels of impurities, particularly Pb and As. Two technologies are being used for copper concentrate smelting at KGHM Polska Meidz S.A., namely the shaft furnace process (Legnica Copper Smelter, Glogów I Copper Smelter) and a single-stage process for direct to blister concentrate smelting in a flash furnace (Glogów II Copper Smelter). Both technologies are used at different physical and chemical conditions which results, in different impurities behavior. The paper presents flow sheets for copper production in a plant using the shaft furnace process and in another in which a single stage flash process is used. The metals distribution in particular semi-products is given as well as a method for elimination of impurities from the copper production cycle. Methods are also discussed for alloy and matte converting and copper refining to obtain low Pb and As concentrations in anode copper (0.3% Pb and 1500 ppm As maximum) that are being used in the KGHM Polska Meidz plants. Useful co-operation between the plants using different technologies, aimed at the limiting the effect of undesired impurities on the quality of blister copper produced, is also described.

Jan 1, 1998

By L. L. Oden

The Bureau of Mines analyzed vapor-aluminum-diffused stainless steels prior to conducting corrosion measurements in severely sulfidizing environments. These studies were conducted in response to the national need to better control the environmental and economic costs of corrosion. Specimens of a ferritic alloy and austenitic alloys types 316 and 310 were treated by a proprietary vapor-aluminum diffusion process and a dual vapor-aluminum diffusion process. Weights and dimensions were recorded before and after treatment, and comprehensive metallographic, X-ray, and electron micro-probe analyses were conducted for both single-and dual-vapor-aluminum-diffused specimens. Surface aluminum concentrations ranged from 26 to 34 wt-pct for all alloys. Dual treatment increased the quantity of aluminum per unit area by a factor of 2 and increased the depth of penetration by a factor of 3. The aluminum-diffused region of the ferritic alloy was single-phase aFe solid solution that was ordered on the surface, whereas two distinct diffusion layers were ob-served on the austenitic alloys. The outer layer comprised aFe solid solution that was ordered on the surface, and the inner layer was a two-phase mixture of aFe solid solution and the interrnetallic compound AINi.

Jan 1, 1982

By Y Xie, L O’Connor, S C. Dominy

"Sheeted vein gold deposits are characterised by multiple subparallel veins and free milling gold. In situ heterogeneity of mineralisation results in grade and process parameter variability, which will increase project risk. Measured variability is often enhanced by poorly designed sampling and test work protocols. Protocols that are optimised within the framework of the theory of sampling to suit the ore type, together with quality assurance/quality control systems, will reduce variability and provide fit-for-purpose results. The geometallurgical approach requires spatially distributed samples within a deposit to support variability modelling. Diverse attributes from core logging, mineralogical/textural determination and small-scale tests are used to measure variability. This contribution emphasises early stage geometallurgical intervention during project development. It presents a discussion of representative sampling in the context of the theory of sampling. A case study presents a protocol that exemplifies how data can be gained from a well-designed and planned program to support a resource estimate and prefeasibility study.CITATION:Dominy, S C, O’Connor, L and Xie, Y, 2016. Sampling and Test Work Protocol Development for Geometallurgical Characterisation of a Sheeted Vein Gold Deposit, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 97–112 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By Barry K. McMahon

Following minor slope failures at the commencement of mining the west wall of the Kanmantoo Mine was redesigned from an overall slope between haul roads of 55° to 46°. This decision was based on a probabilistic analysis which indicated that 46° was the optimum economic slope.

Jan 1, 1983

By Raymond Derzay

This publication is intended to be of value to the mineral industry in establishing and maintaining effective programs for preventing noise-induced hearing loss. Factors involved in this loss and the need for and the requirements of an effective hearing conservation program are discussed. The legal and legislative history of compensation for hearing loss is briefly reviewed. A review of statutes is not attempted since several States have recently modified) or are in the process of modifying their laws regarding permissible noise exposures) required hearing protection) and/or compensation for hearing loss. A review of other aspects of the problem of industrial noise in terms of medical, physiological) and psychological frames of reference is included. A hearing conservation program is described in detail. Appendixes detailing the names and addresses of a few equipment suppliers are included. References are provided for those who may wish to delve more deeply into the medical, technical, and scientific considerations of noise and its effect on man.

Jan 1, 1972

The Aluminum Co. of America raised its 99.5 percent unalloyed aluminum ingot selling price in March by 34 to 514 per pound. Other producers, including Kaiser Aluminum and Chemical Corp. , Anaconda Aluminum Co. , and Reynolds Metals Co., followed Alcoa's lead, raising their quotes to 51$. In late March, domestic merchants quoted ingot at levels ranging between 49.56 and 50.50 per pound. BISMUTH: Several domes tic dealers lowered their bismuth prices in recent weeks by 50t-606 to within a range of $5.60-$5.75 per pound; producers continue to hold published prices at $7.50.

Jan 1, 1977

By N. H. Jensen

SINCE the sixties, Utah has been one of the leading metal mining states of the Union. During the last fifteen years its mines have supported the largest smelting center in the world. Its rank as a metal producing state is reflected by its 1924 production which had a value in excess of $65,000,000 making it the leading silver producing state, third in both copper and lead and sixth in gold production. During the past year, metallurgical developments for the recovery of zinc contained in lead ores has made rapid progress so that the future zinc output will be of substantial importance. The largest silver mines of the nation and the world's largest open cut copper mine are within its borders. Settlement of Utah started in 1847, with the advent of the "Mormons," and originally the area of the state was much greater than now. The first metal mining

Jan 1, 1925

By B. C. Paul, R. Q. Honaker, K. Ho

Recent research has shown that froth flotation is not effective at treating fine coals (-28 mesh) containing a large portion of middling particles. Due to their relatively large density differences, middling particles can be separated more efficiently using gravity-based processes. The ability of gravity separators to treat fine particles has been limited by the lack of particle inertia relative to the surface drag forces. However, particle inertia can be enhanced by the application of a centrifugal field. A commercial-scale centrifugal Falcon concentrator capable of treating a mass flow rate of greater than 1 tph continuously has been used to evaluate its feasibility for treating fine coal as an alternative to froth flotation. Tests conducted on a -28 mesh fine coal circuit feed have found the Falcon concentrator to be very effective at cleaning the 28 x 325 mesh size fraction. For an Illinois No. 5 coal sample, the ash content was reduced in the 100 x 325 mesh size fraction from about 18% to 8% while achieving a high combustible recovery value of nearly 97%. In addition, the total sulfur content was substantially decreased from 2.6% to 1.7%. The effects of the critical operating parameters on separation performance have been studied and their values optimized.

Jan 1, 1995

By Robert M. Busche

[Recent developments in the gasification of coal, both by the Bureau of Mines and American industry, have intensified interest in the thermodynamic and kinetic principles necessary for understanding the reaction mechanism and rates and the physical changes that take place. In the course of a Bureau of Mines study of the kinetics of coal gasification at the Synthetic Liquid Fuels Demonstration Plant, Louisiana, Mo., a bibliography of approximately two references was compiled. They are listed n this publication and refer both to American and foreign sources.]

Jan 1, 1952

By P .. R. Ammann

A two-stage pyrometallurgical process has been developed for the recovery of copper (and other non-ferrous metals) from copper smelter slags. All types of slags, including highly oxidized, converter-type slags, are cleaned in an electric furnace which employs mechanical mixers to promote magnetite reduction and copper extraction at high rates. In a 10-ton pilot furnace, it has been demonstrated that slags can be cleaned to 0.2-0.3 per cent copper with economically acceptable usage of raw materials and energy; copper is recovered as a high-grade matte. Pilot plant data have been scaled up to a commercial furnace and engineering designs have been made for a furnace to treat 60 tons per hour of slag from a Noranda Reactor and the associated converters. Plans are being formulated for the construction of a prototype slag cleaning furnace.

Jan 1, 1976

By M. A. Evanto

Since the late 1970's, the Roof Control Division (RCD) of MSHA's Technical Support has been performing linear analyses for the enhancement of miners' safety. This remote sensing process uses Landsat data to predict areas of potentially hazardous ground conditions in underground mines. To date approximately 700 analyses have been completed by the RCD, with nearly 75 being performed with the current equipment, software and methodology which was updated in early 1995. While success is difficult to measure, requests for linear analyses continue to come from large and small mining companies which suggests the industry's acceptance of the process.

Jan 1, 1998

By C. R. Kuzell

IN COMPARISON with recent years 1932 has yielded much less tangible evidence of progress in copper reduction and refining. The industry has been extremely quiet, especially in the United States. Design and construction has been throttled by lack of new capital expenditures. The excess producing capacity of the whole industry and the extremely gloomy outlook for the future have made it unwise to tie up more capital except under special conditions. The plants built during the previous year have, however, been placed in operation. Older plants have been abandoned, temporarily shut down, placed on part time operating basis, or continue to operate at a low percentage of normal capacity. In the United States the Phelps Dodge Corporation at Douglas, Ariz., has completed the remodeling of the former Calumet & Arizona smelter. A new roaster and Cottrell plant chimney was completed this year. Though operations have been limited the new equipment has been found to justify all expectations. The reverberatory plant addition consists of two furnaces 26 by 107 ft. inside dimensions, with a high arch, and modern steel binding of excellent design. Natural gas fuel gives good results. One of these furnaces will treat 1000 tons of solid charge per day with a fuel consumption of approximately 3,000,000 B.t.u. per ton. The larger converters have not only yielded the expected lower costs, but have simplified operations in the converter department. One of the noticeable results is the greater cleanliness in the environment and the absence

Jan 1, 1933

By Edmundo Alfaro, Álvaro Ordoñez

En el Perú existen diversos yacimientos mineros con contenidos de oro, plata y de metales base tales como el cobre, zinc, plomo, hierro, presentándose tanto como especies mineralógicas sulfuradas como de óxidos. En la zona sur del Perú se encuentran yacimientos de Zn–Pb–Cu–Ag–Au con depósitos híbridos de carbonatos y sulfuros masivos polimetálicos en rocas volcánicas. El tratamiento de este tipo de minerales presenta diversas dificultades para la recuperación de todos los metales de valor. En este sentido, se ha desarrollado investigación técnica preliminar utilizando el sistema peróxido de hidrógeno / amoniaco. (H2O2 / NH3); el peróxido actúa como agente oxidante y el amoniaco como agente acomplejante, dentro de una solución alcalina.

Sep 30, 2022

By Abrahan Barriga

The present study demonstrates the feasibility of the ultrafine grinding and atmospheric leaching process applied to refractory gold concentrates from Salave Project located in northern Spain. At bench scale, it was found acceptable sulfide oxidation was about 84-85% and CIL gold recoveries between 95-96% applying specific energy consumption between 30 and 60 kWh/t during ultrafine grinding. The atmospheric oxidation of the sulfide concentrate was controlled between pH 4.4 and 4.8 with a mixture 90/10 of CaCO3/NaCO3 with residence time of 48 hours for the atmospheric oxidation and 30 hours residence time for the CIL process.

Sep 30, 2022

By Yun Zhang, Haijun Jiang, Shenggen Cao, Chen Wang

The distribution of front abutment pressure is closely related to the force, deformation and energy distribution of hard roof before periodic weighting. So it is necessary to carry out research on the relationship between them. According to front abutment pressure distribution feature, using the location of peak front abutment pressure as the dividing point, coal seam is divided into two parts along the direction of mining: the yield zone that is the area between the faceline and the point where the maximum front abutment pressure occurs, and the elastic zone that is the part before the point of peak front abutment pressure. The proposed mechanical model of unit width hard roof at the panel center periodic weighting consists of five parts including the yield zone. All parameters of the deflection equations for each of the five parts that satisfy the continuity conditions and natural boundary conditions are obtained by using the Matlab software. The continuous curves of front abutment pressure, deflection, bending moment and bending strain energy density distribution of hard roof are obtained by iterative approximation method. The following conclusions can be drawn through analyzing those curves: (1) The position of peak front abutment pressure is located at the transition of coal seam foundation from yield zone to elastic zone (elastoyield critical point), the distance of it to the faceline is equal to the width of yield zone. The peak front abutment pressure increases with yield zone with. (2) The peak bending moment in front of the faceline, and the distance of it to the faceline increase with the yield zone width. The deflection of hard roof at the face and midspan also increase with yield zone width. (3) As the yield zone width increases, the accumulated elastic energy of hard roof in front of the faceline increases, and the core zone of energy moves forward away from the face. (4) When the yield zone width is zero, the whole coal foundation is regarded as elastic foundation, and the peak front abutment pressure occurs at the faceline.

Jan 1, 2015

By Richard D. Harvey

Petrographic properties of carbonate rocks are useful guides to the utilization of these rocks in SO2-scrubbing systems. High porosity and fineness of grain are thought to be the principal properties that contribute to high dissolution rates of the rocks in the scrubbing liquor. Lake marls and chalks are the major types of carbonate rocks that have these properties. Lake marls are composed mainly of equant grains of calcite (mean grain size generally less than 4 microns) weakly agglomerated in- to larger, porous particles. The marls commonly consist of 80 to 90 percent CaCo3 as calcite and aragonite. Impurities are, for the most part, quartz silt and organic matter. The average pore volume for samples of lake marls (1- to 1.2-mm particles) is about 0.50 cc/g, which corresponds to a porosity of about 57 percent. The mean size of pores in these marls is generally between 1 and 2 microns in diameter. Surface areas of lake marls range from 0.8 to 6.8 m2/g. Chalks have grain sizes and shapes similar to those of lake marls, but they generally have smaller amounts of quartz and organic matter and minor amounts of clay minerals. Pore volumes differ from one chalk formation to another; the 1- to 1. 2-mm particles average about 0.20 cc/g, which corresponds to a porosity of about 35 percent. The mean diameter of pores in chalks tested ranges from 0. 15 to 0.76 micron. Surface areas of chalks range from 3. 2 to 20. 1 m2/g. In the United States lake marls are restricted largely to Pleistocene- age sediments that occur in the states around the Great Lakes. Chalk and chalky limestones are restricted mainly to the Upper Cretaceous and Tertiary strata in the Kansas-Nebraska-Colorado area and in the south- eastern states, from Texas to Florida. Results of laboratory tests of the relative dissolution rates of samples at pH 6 and 44°C indicate that, in addition to many lake marls and chalks, oolitic aragonite, pelecypod shells, and carbonate waste sludges from certain industrial plants also have high dissolution rates.

Jan 1, 1974