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By V. Oberholzer

The presence of fines (particles smaller than 6 mm in diameter) causes hydrodynamic problems in gasifiers and therefore it is of great importance to minimize the amount of fine coal in the feed. This serves as motivation for understanding coal?s breakage mechanisms, which could lead to the ability to predict the generation of fines. The aim of this project was to simulate the pulsating effect of the conveyor belt in order to investigate factors influencing the breakage. Results indicated that an increased initial particle size had an increasing effect in the amount of fines generated. Weathering had an insignificant effect on the breakage of coal. To conclude, a breakage model was developed to describe the rate of breakage out of the top size when a combination of two breakage modes is present.

Jan 1, 2009

By Jr. Raleigh

Three run-of-mine bituminous coals, which ranged in rank from low volatile to high volatile A, were floated at nominal -28 mesh (590 µ m), -100 mesh (150 µ m), and -400 mesh (37 µ m) feed particle sizes with selected pyrite depressants and a dispersant. For the coals tested, pyrite and ash-forming minerals were usually rejected best at a -100 mesh feed particle size. Depressant additions tended to improve flotation selectivity between pyrite and coal. When joint dispersant-depressant systems were used at -100 mesh (150 µ m) feed particle sizes, the total sulfur content of the clean coal decreased further. For a comparable coal yield, less fuel oil collector was required for the flotation of -100 mesh coal than was required for the flotation of either -28 or -400 mesh feed.

Jan 1, 1990

By Charles F. Herbert

It is difficult to decide who most deserves credit for discovery of a mining district that has produced over 19.8 Mg (7,000,000 fine oz) of gold and still contains a large reserve of low grade ore. Fred Culver may have made the first discovery. In the summer of 1867, the ship's log of the Hudson's Bay Co.'s steamer Otter stated that Fred Culver had been found nearly lifeless from wounds, without provisions, but with some 2.3 kg (80 oz) of rough, placer gold in the bottom of his canoe; he told of finding a rich creek and an attack by Indians that caused the death of his two companions. The place of rescue was about 24 km (15 miles) southeast from the present site of Juneau. Possibly John Muir, the hero of modem environmentalists, should be given important credit. In 1879 he reported finding mineralization along what later became to be known as the Juneau Gold Belt, and it was his report that induced the cantankerous German mining engineer, George Pilz, to grub- stake some of the prospectors who had drifted into Sitka from the declining gold placers of Cassiar, British Columbia. Pilz also offered rewards to Indians who might report gold discoveries.

Jan 1, 1990

By Tiago Nunes Lima

Novas ligas de Ti estão sendo desenvolvidas como uma alternativa para aplicação em implantes cirúrgicos e em componentes estruturais por possuírem propriedades atraentes em comparação à liga Ti6Al4V, com destaque ao menor módulo de elasticidade, menor citotoxicidade, maior resistência à corrosão e propriedades mecânicas similares, alta resiliência e elevada formabilidade. Este estudo tem como objetivo observar as características mecânicas de ligas Ti35Nb2Sn deformadas a frio e seguidas de envelhecimento. A liga foi laminada a frio com 80% de redução e envelhecida a 400 ºC por 48 horas. Foram realizados ensaios de tração, dureza, metalografia e análise das superfícies de fratura. A liga laminada apresentou uma maior relação de resistência à tração pelo módulo de elasticidade e maior ductilidade do que a liga envelhecida.

Aug 16, 2017

By Jim A. King

The total pressure oxidation of copper concentrates is a potentially viable option for treating copper concentrates that are either low grade or contain significant impurities. Both concentrate types are heavily penalized in smelter contracts. The total pressure oxidation process involves autoclaving the copper concentrate at temperatures of 200-220 C under oxygen pressure. The autoclave discharge can be separated into a solid (oxidation residue) and a liquid (oxidation solution) product. The oxidation solution can be treated for copper recovery by solvent extraction - electrowinning or by direct electrowinning. The direct electrowinning recovery of copper requires prior removal of selenium and tellurium by cementation on finely divided scrap copper. The oxidation residue is washed thoroughly to remove acid and dissolved copper prior to precious metals recovery by conventional cyanidation in the presence of lime. The results of a benchscale investigation involving a number of copper concentrates are reported. Copper recoveries in autoclave oxidation and gold recoveries by cyanidation of the oxidation residue exceeded 99%. The results of benchscale experiments to demonstrate copper recovery are described. Various flowsheet options are presented.

Jan 1, 1993

By Benoît Pinier, Jason Furtney, Gustavo Sampaio Lopes, Jorge Valencia, Johan Hawinkel

This paper describes a numerical modeling study on the effect of airdecking on vibrations, fragmentation, and movement in mining-related rock blasting. Practice has shown that air gaps reduce blast vibrations and damage while maintaining the required fragmentation and movement, yielding similar blast outcomes with less explosive mass per hole. Given that the premise of “replacing explosives with air” for better blast results is counterintuitive, this paper aims to shed light on the physical mechanisms and processes occurring in a blast with airdecks. It is hypothesized that airdecks are effective and beneficial because they load the rock at pressures lower than what is required to crush the rock. In the airdeck, the explosive gasses directly fracture rock and avoid energy loss due to crushing. In essence, the airgap allows similar outcomes in fragmentation and throw with less total explosive product, as the lower pressure gasses in the airdeck are still effective at breaking and moving the rock. This is distinct from only having less explosive and more stemming, as the stemming reduces the pressure more than an airdeck at the same position. This study uses the blastFoam software (for modeling of single and multiphase flows) to accurately calculate the pressure history throughout a blasthole and air gap. The pressure and gas loading are coupled to numerical models of vibration, fragmentation, and blast movement. Using this modeling technique, a suite of blast scenarios for typical configurations in a range of commodities is assessed with and without airdecks. Rock blasting practitioners have a responsibility to protect communities, infrastructure, and heritage — demystifying airdecks through a better understanding of the physics provides another tool in the blasting engineering toolkit to serve this goal.

Jan 21, 2025

By Pedro Hugo Tumialán de la Cruz

Dado que es difícil determinar el potencial minero de un yacimiento durante los primeros meses, es necesario la aplicación de un sistema de exploración geofísica que prevea el estado de mineralización a futuro. En este sentido, el objeto del texto radica en señalar los problemas encontrados en algunas zonas mineras del Perú, así como las posibles soluciones para este problema, a partir del uso de este sistema. Los casos a analizar son: exploración en yacimientos de cobre de la mina Acotambo, la exploración en el sistema polimetálico, la exploración en el distrito minero de Caylloma y la exploración en el yacimiento Pasto Bueno (Ancash).

Nov 20, 1978

By Thomas T., Read

IN this survey of the progressive development (of education for the mineral industries throughout the United States, the review of .the history of each school has usually been completed wherever it is first mentioned, but the history of the schools in the cities of the eastern seaboard was not carried beyond 1870. It is necessary now to cover what happened during the period of approximately the last quarter of the nineteenth century in several of the schools in the east. Philadelphia Of Philadelphia, it has been related in chapter 4 that the Polytechnic College of Pennsylvania began offering a curriculum leading to the B.S. in mining in 1853; that the school did not prosper, and finally closed about 1890. The establishment of a Department of Mining, Arts, and Manufactures at the University of Pennsylvania in 1855-56 was also mentioned, but its history was not carried beyond 1860. In 1859 J. Peter Lesley was appointed professor of mining in the University of Pennsylvania. The son of a cabinetmaker, born in Philadelphia Sept. 17, 1819, he had taken his A.B. degree at the University of Pennsylvania in 1838 and then secured a position on the Geological Survey of Pennsylvania under H. D. Rogers. When the Survey was discontinued, in 1841, he went to Princeton to study theology, was ordained a Presbyterian minister and followed that career until 1852, when the Pennsylvania, Geological Survey was again started and he rejoined its staff. He published "A Manual of Coal and its Topography" in 1856, and studied at the École des Mines, Paris, in 1856-57. He published an 800-page "Iron Manufactures Guide" the year that he was appointed to the staff at the University of Pennsylvania. In 1863-64 a College of Agriculture, Mines, Arts and the Mechanic Arts was established, but it was not a separate school

Jan 1, 1941

Maximising margins in today's competitive international commodity markets demands superior productivity. This requires more than simply selecting the best equipment. It requires efficient production and commercial processes together with management systems recognised as international best practice. This paper introduces an integrated way of working that includes management systems for successfully changing work practices and attitudes, developing managers and increasing accountability. It provides an improvement methodology that includes systematic involvement of people in true continuous improvement of processes for maximising productivity and safety while minimising costs. Even though the principles are proven in all industry sectors worldwide, they are not always used correctly. This paper provides examples of traditional performance measurement systems to show how managers miss opportunities to control and improve both production and supporting service processes. It also describes the basic methodology for correct use of the principles and provides examples of correct implementation of modem systems in mining. The charts from actual mining case studies will be elaborated upon in the conference presentation. This paper's main aim is to provide background material for the presentation by introducing integrated principles for building best practice management systems for superior productivity and safety - for higher margins.

Jan 1, 1996

By A. Navarra

Peirce-Smith converting (PSC) is applied for roughly 50% of primary nickel and 70% of primary copper production. PSC cycles produce batches of ironfree sulfide matte (or blister copper, in the case of copper smelters), that are subject to further processing. However, the number of cycles that can be performed simultaneously is limited by the offgas handling system. Moreover, PSC suffers from variation in the yield and duration of the cycles. This variation is managed by conventional smelter designs, in which the upstream smelting capacity exceeds the nominal converting capacity; PSC is thus a major bottleneck in conventional nickel and copper smelters. Stabilization and standardization of PSC operations can therefore increase smelter throughput. The current paper presents a discrete event simulation (DES) framework to assist in smelter debottlenecking. It features random number generation to represent cycle variability, and time-adaptive finite differences to represent thermochemical complexity. Preliminary computations are presented.

By V. K. Risinggård, M. Sparta

We report on the development of a finite-element method model for a pilot furnace for the production of manganese alloys. The model is a multiphysics model that addresses material flow, electrical conditions, heat transfer, and physical and chemical transformations. It is capable of studying both quasi-steady and transient states in time-dependent simulations. The model includes common charge materials and fluxes and can simulate production of both ferromanganese and silicomanganese alloys with acid and basic slags, as well as changing charge compositions. The model output provides access to the material distribution in the furnace during furnace runs, temperature profiles, current paths, energy balances, and alloy and slag production rates and compositions.

Apr 16, 2024

By F. P. Haver

The Bureau of Mines is developing a leach-electrolysis procedure to produce Special High Grade (SHG) zinc from sulfide concentrate without the generation of sulfur oxide gases. Chlorine-oxygen leaching of the concentrate yields zinc chloride (ZnCI2) which, after purification, is electrolyzed in a fused-salt cell to obtain molten zinc metal and chlorine gas for recycle. This paper describes a laboratory-scale investigation made to develop a procedure for electrowinning zinc metal from ZnC12. Zinc chloride by itself is not a suitable electrolyte because it fumes badly above its melting point and is a poor conductor of electricity. Other salts therefore must be added to prevent fuming and improve the conductivity. Optimum results were obtained with a KC1-LiCl-ZnCl2 bath at 500° C, using a current density of 5 amp/in2 and an electrode spacing of 0.5 inch. Under these conditions, SHG zinc was produced at a current efficiency of 94.3 pct and an energy requirement of 1.16 kwhr/lb. Fused-salt electrowinning eliminates the need to handle and melt cathodes and increases the production of metal per unit cell volume through the use of higher current densities than are possible with aqueous electrolysis.

Jan 1, 1976

By Robert M. Cox

The objective of this study was to determine if significant relationships exist between coal mine roof stability and the time roof is left unsupported. Additional factors such as geology, opening geometry, and mining methods were also studied: to determine their relative influence on mine roof stability. The results of the study indicate that geologic factors such as shear zones (either joints or faults) and changes in roof rock lithology were the principal factors governing mine roof stability. The time lapse factor appeared to be of critical importance when poor mine roof conditions are encountered. The study pointed up the need for improved and permissible rock mechanics instrumentation for use in coal mine investigations.

Jan 1, 1974

By H. Cho

A study was undertaken to investigate the liberation behavior of coal macerals through size reduction and density separation. It was seen that the liberation of coal organic components could be achieved by size reduction, allowing selective separation of coal organic components. However, the degree of liberation is dependent on the history of coal: the extent of liberation decreased when the size of the primogeniture coal decreased. The liberation of coal macerals was analyzed by examining the Liberation Index. It was seen that although comminution produced fine particles enriched in inertinite (primarily fusinite and semifusinitie), these particles were less liberated than the coarser particles. However, the liberation of macerals increased when all the feed was ground to a finer size.

Jan 1, 1996

By Diego Canez Fernandes, Henriquison Bottrel Reis, Mauricio Covcevich Bagatini

As técnicas que visam aumentar a densidade de carga possibilitam elevar a produtividade da coqueria e, além disso, permitem utilizar carvões com menor poder coqueificante. O aumento de densidade pode contribuir ainda para a obtenção de um coque de melhor qualidade, o que contribui para a redução do coke rate no alto-forno. Uma alternativa para aumentar a densidade de carga é a adição de óleo na mistura de carvões, o que reduz a tensão superficial da água, permitindo uma maior aproximação entre as partículas e favorecendo o contato efetivo durante a fase plástica. Neste contexto, o presente trabalho teve como objetivo avaliar o efeito da adição de óleo na densidade de carga para diferentes condições de granulometria e umidade do carvão empregado. Para isso foram realizados ensaios para medir a densidade de carga em três níveis de umidade (8%, 10% e 12%) e granulometria (82%, 85% e 88% < 2,83 mm). Posteriormente, foram realizados ensaios de coqueificação em escala piloto, e o coque produzido foi avaliado quanto ao DI15/150 (drum index), CRI (coke reactivity index) e CSR (coke strenght reaction). Os resultados mostraram que a adição gradativa de óleo promoveu aumento na densidade de carga enquanto a elevação da umidade do carvão e seu afinamento provocou a redução desse parâmetro. A qualidade metalúrgica do coque aumentou com a elevação da densidade de carga demostrando que essa é uma técnica com potencial de uso em plantas industriais.

Oct 1, 2019

By V. P. Keran

Design of the Bajo de la Alumbrera Project started in June 1995 and concentrate production commenced early in the Third Quarter of 1997. The project is situated in North-Western Argentina and is being developed by Minera Alumbrera Limited which is owned by MIM Holdings Limited of Australia (50%), North Limited of Australia (25%) and Rio Algom Limited of Canada (25%). This paper outlines the key features that were incorporated in the design from both process and plant layout perspectives. It explains the background of flowsheet and equipment selection for the plant. A feature of the flowsheet is that it incorporates gravity gold circuits in both primary and regrind circuits for recovery of gold to dore as well as in the copper concentrate product.

Jan 1, 1998

By James P. Roe

I. INTRODUCTION. THOSE who deem the subject of this paper an old and super¬seded one may recall with advantage the words of the great proverb-maker, bidding us to seek the new in the ashes of the old. The manufacture of wrought-iron began with the small hearth built upon an eminence, and relying on the wind for blast. Next came, either the hearth about 12 in. in diameter by 2 ft. in height, blown by a man operating two goat-skins for bellows, or, a hearth of greatly varying diameter and about 10 ft. high, depending for its blast upon natural draft. The former appeared in India, the latter in Burmah; and both were in operation until quite recently, though their origin is lost in prehistoric times. The Catalan forge was the evolutionary descendant of the foregoing, and the parent of the Blase-ofen, which in turn led to the high bloomary or " Stückofen," the father of the blast-furnace, as a producer of cast-iron. The production of cast-iron checked the growth of the direct processes; and led to the introduction of various hearths, such as the Walloon, for low-silicon irons; and the South Wales process, combining the run-out fire with the finery, for higher-silicon irons. Some of these are still in operation in localities possessing the necessary raw materials; and their product is used for purposes requiring wrought-iron of exceptional quality, the supply of which is still smaller than the demand. We have to look back but a century and a quarter to see the introduction of the puddling process by Henry Cort; a process which, reinforced by the iron-oxide bottoms and fettling of Hall, was not less revolutionary in character, and more revo-

Jul 1, 1905

By E. J. Lintner

This paper is one of a series being prepared by the United States Bureau of Mines describing clay mining, crushing, and grinding methods and costs at various operations throughout the United States. These papers are designed to disseminate technical information regarding methods used. The cost tabulations represent local operating expenditures only and not total production costs. It is recognized that in many instances publication of total production costs may cause embarrassment to the individual operator as well as to the industry as a whole. On the other hand, operating costs are essential to a technical discussion and study of the methods employed. The attention of the reader is called specifically to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. The following report deals with the methods employed by the Malvern Clay Co., Malvern, Carroll County, Ohio. The author wishes to acknowledge the assistance of the following persons: H. C. Ross, vice-president and general manager, and H. C. Dormer, secretary and treasurer.

Jan 1, 1937

By Daniel Scott

Mines have used explosives for economical fragmentation for many years. It can therefore be expected that the mining industry has thoroughly researched how to achieve the most efficient blast. However, there is still a large amount of iteration that must be undertaken before blasting at a mine site can be refined enough to allow for consecutively successful blast results. And then the geology changes. This paper will present an approach to blast design that considers production goals, geology, budget, and safety, and will contrast the proposed method with well established blasting theory.

Jan 1, 2012

By C Harwood

Underground coal mines in the United States are in the process of completing installations for tracking and communication systems, mandated by Congress after a number of recent coal mine disasters. Yet, evaluation, modelling and testing of such systems has lagged due to legislated changes, abruptly introduced into the coal mining industry. System installation in a wide array of mine types, configurations, layouts and characteristics has provided a wealth of information regarding their potential in underground environments. Data collected from numerous installations for a variety of systems can be used to further define true capability and accuracy of communication and tracking packages. This paper describes a uniform means of evaluating the performance of a communication and tracking system. Several performance measures are proposed and described. These measures can also be predicted using an interactive software program. This program predicts the signal propagation, given the input mine characteristics and layout, with numerical and visual feedback. New or alternative system installations can also be more accurately designed to potentially minimise initial system cost and time required for trial and error installs. The focus of this research is to develop tools and protocols that can evaluate and measure the effectiveness of installed underground communication and tracking systems.

Nov 22, 2011