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By Joe Zhou

"Mineralogical characterization and metallurgical extraction of silver is challenging due to its complex mineralogy and chemistry. Over 200 Ag-bearing minerals have been identified and a silver-rich ore body would typically contain 5 to 10 different silver minerals. Silver can occur not only as discrete microscopic (visible) silver minerals but also as submicroscopic (invisible) silver in other minerals. During processing, silver may form passivation compounds such as silver hydroxide, silver sulphide, jarosite-like silver sulphate, silver halide or silver cyanide precipitate, all of which may negatively impact on silver extraction. Knowing the deportment of silver in the ore and its metallurgical products is important in flowsheet design and plant optimization. This paper begins with the classification of silver ores and minerals and a review of processing techniques, and focuses on the major mineralogical factors to explain why and how these factors affect silver extraction. Case studies are provided to demonstrate the application of silver process mineralogy in flowsheet design and plant optimization.INTRODUCTIONSilver was known to and utilized by mankind since ancient time. Actually, it was one of the earliest metals discovered and utilized by mankind after gold and copper.Silver is the whitest metallic element. It is rare, strong, corrosion resistant, and unaffected by moisture, vegetable acids, or alkalis. Silver is also resonant, moldable, malleable, and possesses the highest thermal and electric conductivity of any substance. The chemical symbol for silver is Ag, from the Latin argentum, which means white and shining. Although silver does not react with many chemicals, it does react with sulfur, which is always present in air at trace amounts. The reaction causes silver to tarnish, and consequently it must be polished periodically to retain its luster.Silver possesses many special physical characteristics and qualities that make it useful to a variety of industries. The photography industry is the biggest user of silver compounds. Silver forms the most light-sensitive halide salts, which are essential to developing highquality photographic prints. Silver also has the highest electrical conductivity per unit volume of any metal, including copper, so it is used extensively in electronics."

Jan 1, 2010

By R. Mohan Srivastava

In any operating mine, especially in precious metals operations, immediate improvements in profitability m readily achievable through more effective grade control. Just as the oil industry has come to recognize that enhanced oil recovery (EOR) in existing oil fields yields a higher return on investment than exploring for new oil, so too must the mining industry recognize the benefits of enhanced metal recovery (EMR). Current grade control practices are generally dismal. The very word "control" suggests a willingness to make the best of a bad situation -- as in "damage control" or "disease control" -- and a failure to perceive the opportunities for improved profit. While damage and disease can merely be controlled, success and improved profit can be engineered. This paper presents one approach to enhanced metal recovery. It shows how existing methods can be used to address the issue of ore/waste discrimination. The following sections outline the problem, describe the current state of the practice of grade control, propose an alternative approach and. illustrate the application of the proposed alternative to actual blasthole data from an operating gold mine.

Jan 1, 1992

By Kenneth M. Smith

"The kaolin deposits of Aiken County, South Carolina (fig. 1), have been worked continuously since 1852. It has been long known that the deposits contain a high percentage of alumina and that large reserves exist. These facts led to the early selection of this area for examination in the search by the Bureau of Mines for high-alumina clays. An exploratory program was started by the Bureau, and drilling was carried on from June 27, 1942, to October 31, 1942.The kaolin-bearing district occupies an area approximately 25 miles long and 11 miles wide, running northeast, with its center at Aiken, S. C. (fig. 1). Within this district, a triangular area bounded by Horse Creek, Silver Bluff Road, and Hamburg Road was roughly prospected by boring 43 machine and 12 hand holes. As a result of the data obtained, a final smaller area was chosen for more systematic prospecting. This area is bounded by Pine Log, Tewkesbury, Silver Bluff, and Craig Sawmill Roads and covers about 4,000 acres.Mineral exploration agreements covering 11,272 acres were signed by 35 property owners, and 11,956 feet was drilled in 200 holes on these properties.The Bureau of Mines exploration work in the district has indicated 19,514,000 short tons of kaolin, of which approximately 10,000,000 tons would average over 35 percent alumina.The tonnages and grades of kaolin developed by this exploration are tabulated below.All grades of this kaolin average approximately 2 percent Fe203 and 1.5 percent Ti02.This project was under the general supervision of J. R. Thoenen, supervising engineer, Non-Metals Mining Section of the Mining Division, Bureau of Mines, until July 1942. The -project was then under the general supervision of E. J. Lintner and later Rowe McCrae, consecutively district engineers for Georgia, South Carolina, and Florida. The final report was prepared, under the general supervision of V..J. Lynch, chief, Raleigh Branch, Mining Division, by William A. Beck from the original report by the author.Acknowledgment is made for the wholehearted cooperation and assistance given to the Bureau of Mines by the various operating companies in the district. Particular thanks are due Theodore Henderson, general manager; North American Clay Co., Wilbur Driver, general manager, and Howard Driver, assistant general manager, The Huber Clay Co.; H. W. Smith, president, The South Carolina Clay Co.; and J. Richard Parker, president, J. R. Parker Clay Co., all of Bath S. C.; J. B. Howard, Jr., superintendent/ the Immaculate Kaolin Co., Langley, S. C.; Richard Jones, president, National Kaolin Co., and William Winans, president, The Southern Clay Co., both of Aiken, S. C.; and W. S. Burkalter, Warrensville, S. C.Acknowledgment is also due the Metallurgical Division for analytical determinations and to James J. Page of the Federal Geological Survey for his aid in mapping and logging the holes.The first known use of kaolin from this district was by the Bath Pottery Co., which began mining an outcrop in Horse Creek Valley, near Bath, in 1852.. In 1867, R. McNamee, of New York City, acquired this pit and continued mining. This first mine is still known as the McNamee, and from its operation grew the present kaolin industry of South Carolina."

Dec 1, 1949

By Joseph A. DeCarlo

Coal is one of our basic sources of energy (heat, power, light) and an essential raw material for most metallurgical processing. More than two-thirds of the electricity currently produced by thermal powerplants in the United States is generated by coal, and it is expected that coal will continue to be the major fuel used for this application at least through the 1970's. Coke produced from bituminous coking coal is the principal fuel of iron blast furnaces, and unless ironmaking methods change greatly, coal will continue to maintain a dominant role in iron-ore processing and steel manufacturing for many years. Export markets are expected to increase also, adding to the overall increased demand for coal. Accompanying the increased total requirement, however, will be an ever-increasing demand for higher quality coals, specifically, coals of low sulfur content. Except for special-purpose coals such as those used for the production if coke and ceramics where impurities in the fuel contaminate the end product, the amount of sulfur in coal has been only a minor consideration in the selection of a particular coal for fuel. Major considerations, particularly for the coals used to generate electric power, have been availability and cost. An increased national concern for control of air pollution, however, particularly that resulting from the emission of sulfur oxides in stack gases to the atmosphere, has led to more rigid specifications on coal quality, and the sulfur content of coals will become increasingly more important in the future.

Jan 1, 1966

By Joseph A. DeCarlo

Coal is one of our basic sources of energy (heat, power, light) and an essential raw material for most metallurgical processing. More than two-thirds of the electricity currently produced by thermal powerplants in the United States is generated by coal, and it is expected that coal will continue to be the major fuel used for this application at least through the 1970's. Coke produced from bituminous coking coal is the principal fuel of iron blast furnaces, and unless ironmaking methods change greatly, coal will continue to maintain a dominant role in iron-ore processing and steel manufacturing for many years. Export markets are expected to increase also, adding to the overall increased demand for coal. Accompanying the increased total requirement, however, will be an ever-increasing demand for higher quality coals, specifically, coals of low sulfur content. Except for special-purpose coals such as those used for the production if coke and ceramics where impurities in the fuel contaminate the end product, the amount of sulfur in coal has been only a minor consideration in the selection of a particular coal for fuel. Major considerations, particularly for the coals used to generate electric power, have been availability and cost. An increased national concern for control of air pollution, however, particularly that resulting from the emission of sulfur oxides in stack gases to the atmosphere, has led to more rigid specifications on coal quality, and the sulfur content of coals will become increasingly more important in the future.

Jan 1, 1966

By Woodcock J. T, Jackson N

Wattle Gully Gold Mines N.L. of Chewton, Victoria, has decided to replace its present battery plant by a new mill to treat a free milling gold ore, after fine grinding, by concentrating coarse gold in a jig concentrate for amalgamation, and fine free gold and auriferous sulphides in a flotation concentrate for cyanidation. This paper outlines the economic justification and advantages of this step. In a review of the present position at the mine, a history of the company is followed by a description of the ore and its occurrence.Present treatment practice in two separate battery plants is described. Treatment tailings assay 1 dwt/ton gold and a substantial part of this gold is finer than 200 mesh.Experimental work showing how recovery may be improved is discussed and alternative methods of concentrating coarse gold mentioned. It is decided that the most suitable method for recovering gold from the ore is by jig concentration plus flotation.The merits of various flowsheets incorporating these techniques in the existing plant and in a new plant are assessed. It is concluded that there is no advantage in extending or converting the existing two battery plants, and it would be more economical and satisfactory to build a new plant.An economic study shows that for a capital expenditure of £120,000 a new plant could be erected to treat 70,000 tons p.a., working a 5-day week, and return an additional 14.2/- per ton, or £50,000 p.a., in revenue over the existing plant. It is estimated the plant cost can therefore be recouped out of savings inside three years. Probable ore reserves are sufficient to cover this period and additional ore will certainly be developed.INTRODUCTIQNSince 1934, Wattle Gully Gold Mines N.L. has been mining a lode gold ore at Chewton, near Castleniaine, and treating it by stamp milling and plate amalgamation, plus table concentration of auriferous sulphides. In 1954, following two years of unprofitable operation, a rehabilitation programme of all sections of the mine and plant was commenced. In the treatment section, two, major prospects for improvement...

Jan 1, 1959

By Merete Tangstad, Ragnar Tronstad

Ferromanganese production in electrical furnaces is quite an old process. However, as the furnaces are getting bigger, the requirements of cost, yield, product quality, emissions and security are raised. With the increased expectations, the fundamental knowledge must follow. Within the last 25 years there has been a great effort both in the industry as well as the academic environment to push the limits of this process. This article will show some examples of improvements within fundamental data, reaction mechanisms and emissions over this time period.

Jan 1, 2014

By Reinis Sipols

AGENDA ? Introduction ? Definitions and Key features ? PEA - Preliminary Economic Assessments ? PFS ? Preliminary Fesibility Studies ? FS ? Feasibility Studies ? Costs and Risks ? Cash Flow, Economic Analysis and Reporting ? Recommendations for Improved FS accuracy INTRODUCTION ? The reporting of material information on mineral deposits has been governed by NI 43-101 legislation for almost a decade. ? The investment sector depends on the independent, professional QP to provide objective observations, comments and recommendations through all levels of geological, engineering and financial evaluation until a mine construction decision has been made.

May 1, 2013

By ATF Publications

The following is a summary of the changes that were incorporated into the new Federal Explosives Regulations, 27 CFR Part 55, dated 9/2000. However, in light of the recent events of September 2001, additional changes in the Federal Explosives Laws and Regulations may be forthcoming. The nature and extent of any such potential changes are impossible to gauge at this time. However, this synopsis of the changes contained in the September 2000 Orange Book, ATF P 5400.7 was current at the time of this writing. Any questions regarding this paper should be directed to the Public Safety Branch in ATF Headquarters in Washington, D.C.

Jan 1, 2002

By Michael S. Moats, Prashant Bagri

"In recent years with increasing concerns about energy consumption in hydrometallurgical processing, there is an ongoing attempt to use Catalytic Titanium Anodes (CTAs) for copper electrowinning. For this work, anodes with IrO2 - Ta2O5 coatings were prepared in the laboratory with the same total coating loading but varying the number of layers by changing the speed of withdrawal in dip coating. A second set of CTAs were fabricated on niobium, Ti Grade 1, Ti Grade 7 and Ti Grade 36 metal substrates. All the anodes prepared in the laboratory were characterized using standard electrochemical techniques and subjected to accelerated life testing. It was found that the coating would not adhere to the niobium substrate, the grade of titanium had a minimal to no effect on the life of the anode, and it is observed that as the coating speed slows, there is an increase in the electrochemically active surface area of the coating which seems to directly contribute to an increase in the Tafel slope of the anodes. There was inconclusive evidence on the effect of coating speed on anode lifetime.INTRODUCTIONLarge scale hydrometallurgical extraction of copper has become widely practiced over the last 40+ years. The hydrometallurgical route entails leaching, solvent extraction and electrowinning. With the increasing desire to process refractory sulphides like enargite and chalcopyrite through the hydrometallurgical route, use of hydro-processing of copper is expected to remain high.In conventional electrowinning, copper is deposited on the cathode and an inert anode is used for oxygen evolution. Presently, the most common anode material is rolled lead-calcium-tin and the cathode is 316L stainless steel (Robinson et al., 2013). This lead alloy is fairly inexpensive and is robust, providing lifetimes typically of 4+ years. The main drawbacks of lead alloys are their relatively high oxygen evolution overpotential, the need for cobalt in the electrolyte to reduce their corrosion, the contamination of cathode product by lead, and the generation of harzardous by-products (Hiskey, 1999)."

Jan 1, 2016

By Norbert Patzelt, Johann Knecht, Wolfgang Baum

The principle of high-pressure interparticulate comminution has been used very successfully since the mid 1980's for grinding a wide range of different materials. A number of reports about operating experience have already been published. High-pressure grinding rolls (HPGRs) are currently making their debut in the mining industry. Experience is being gained with test machines, particularly for the comminution of hard rock. In the grinding of diamond-bearing ore, (Fig 1) interparticulate comminution has already become the standard for liberating the diamonds from the matrix. The advantages of interparticulate comminution are also recognized for the grinding of concentrates (chrome ore, iron ore). Numerous HPGRs are being used very successfully in this field. A testing plant for first-time industrial grinding of coarse, very hard and highly abrasive copper ore was built at Cyprus Amax's plant in Sieretta, Arizona (Fig. 2). The operating experience gained here showed that the grinding of very hard ores places particularly high mechanical demands on the mill. While the machine itself meets the high availability requirements, the wear-protection system proves to be the most sensitive point. Naturally, the properties of the ore to be ground exert a considerable influence on the lifetime of the grinding rolls. This paper describes the wear mechanisms and the wear­protection systems designed to combat these.

Jan 1, 1997

By A. W. Davis

Sapping and mining have constituted an important part of siege operations ever since powder came into general use in Europe. Before this period, famine was the main weapon in the hands of the besiegers, and the history of the middle ages is replete with accounts of sieges lasting two and three years. With the advent of explosives, a position impregnable to assault might be readily won by mining under, and blowing up, its defences. The natural offensive against this method of attack is to countermine and stop the attackers underground before their objective is reached. Thus developed the art of military mining. The French and British, in the Peninsular war, were adepts at this method of warfare, and the explosion of a mine and the formation of a breach were the usual preludes to the general assault of a position. In the Crimea, at Sebastopol, the British and Russians did a lot of underground fighting, as the old maps of their galleries, now in the museum at Chatham, will testify. In the siege of Port Arthur, in still later times, the Japanese and Russians were hard at it as well.

Jan 1, 1926

By C. Schlumberger

INTRODUCTION The object of the present paper is to discuss, from a geological point of view, the practical results obtained by the authors with the method of the 'resistivity map of the subsoil' in the study of various mining problems. Some of the studies described date from 1920, 1922, and 1923. They are, therefore, quite old, at least as far as geophysical research is concerned (1). Others, on the contrary, are very recent (2). We shall deal only very briefly with the theoretical and technical sides of the processes employed. This paper has, essentially, a practical purpose, and it has seemed unnecessary to enter into a detailed discussion of the methods. Such a discussion cannot be presented without introducing ,quite. Complex considerations both of mathematics and experimental physics, which interest only the geophysicist: whose work is highly specialized.

Jan 1, 1931

By John D. Kalasky

Continuous mining has revolutionized the coal industry but intensified the problems of earlier mechanization. From the installation of the first miner, it was recognized that face ventilation would be one of these problems. To establish an efficient work cycle for the equipment being used, conventional mechanized mining provides four or more development faces. Continuous mining, relying on a single machine, requires only one face, although more than one can be driven alternately by the same machine. In gaseous areas mined by the older methods, the intermittent rate of exposure allows time for the face to bleed off or be cleared, and the width obtained with conventional units makes it possible to hang a brattice line almost to the face. Continuous mining increases the ventilation hazards; there is no margin of time, and very limited space.

Jan 9, 1959

By A L. Randriamanjatosoa, G Small, C Greet

In flotation simulation models, the effects of pulp chemistry other than pH are often ignored and reduced to particles hydrophobicity or contact angle, neither of which can be measured readily in real time in an operating plant. The flotation response of a given sulphide mineral is known to be influenced and can be improved by changing the chemical characteristics of the pulp during grinding and flotation. The on-line measurement of pulp pH, potential, dissolved oxygen, temperature and oxygen demand of a process stream was completed with the PCM® (Pulp Chemistry Monitor) developed by Magotteaux in this study. The data generated together with relevant plant operating parameters were used to construct an empirical model and simulate the metallurgical performance of the ore. The same approach was also applied to laboratory flotation tests data using various grinding media types. The flotation models better fit the actual data when the chemistry of the pulp is taken into account.CITATION:Randriamanjatosoa, A L, Greet, C and Small, G, 2018. Effects of pulp chemistry on plant and laboratory flotation modelling, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 423–432 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Breno Totti Maia

In these hard days for Brazil steel market, all steel shops want to achieve the same goal, work with: productivity, low costs and high performance. In this scenario the Slagless® technology (which is applied into BOF converter) was important to reach these targets. After use has been reduced the number of times of tip exchange in more than 04 times. Was reduced too, the time to remove lance skulls. Lance keeps clean during all his life with record number of the life 1255 .Blow keep stable due strong measure control at the nozzles and more improvements are planning.

Oct 30, 2017

The mineralisation consists principally of layered pyrite, phalerite and galena, situated conformably within a sequence of tuffaceous, bituminous shales and dolomitic sediments that include slump breccias. The sediments show little evidence of post sedimentary reconstitution. A volcanic-exhalative-sedimentary origin is postulated for the mineralisation. Attention is drawn to the similarity between the McArthur deposit and the lead-zinc-silver orebodies at Mount Isa. The primitive nature of the sulphides is reflected by their adverse metallurgical behaviour, and it seems that the best prospect for milling and flotation benefication may lie in the production of separate zinc and bulk concentrates

Jan 1, 1968

By Yi Luo

In dealing with various subsidence cases, accurate predictions of mining induced subsidence are the basis for correct assessment of subsidence influences and subsequent mitigation efforts. There is a good demand for a reliable tool to perform the subsidence predictions and related tasks. A comprehensive and integrated subsidence prediction model, CISPM, developed by the senior authors in the later 1980?s and early 1990?s (Peng and Luo, 1992) is one of such tools. Built on solid mathematical models and calibrated by a large number of collected subsidence cases, CISPM provides a rich set of features needed in subsidence engineering and research works. Its reliability and usefulness have been proven by numerous field applications. This upgrade of CISPM will not only preserve its original features and reliability but also provide some new needed features and a more user-friendly working environment.

Jan 1, 2008

By Robert H. Dickson

This paper describing the mining practices at the Verde Central mine at Jerome, Ariz., is one of a series being prepared by the United States Bureau of Mines on mining practices, methods and costs in various mining districts of the United States. ACKNOWLEDMENTS The costs contained in this paper were prepared by R. J, Huddleston, chief clerk, Verde Central Mines, Inc.

Jan 1, 1931

By J. Dubbert, T. H. Jones

"This paper describes a rib-control methodology that uses standing support to provide most of the lateral resistance to the rib. The method is analyzed, and its boundary conditions for rib control are described. In this method, an animal-fencing mesh product covers 80 percent of the rib surface and is sparsely bolted to the rib. Can supports or other similar stiff supports are installed primarily as roof support for the entry. As the rib spalls and dilates, the mesh catches the material and expands, pressing against the standing support. Mining proceeds, and vertical roof loads increase the normal force on the Can supports, causing friction at the top and bottom of the support to go up, thereby improving lateral resistance to rib swelling.At one mine in the western United States, this method has proved excellent at preventing the buildup of rib spall. It substantially reduces the number of bolts used for screen installation, improves installation efficiency, reduces manual labor and provides more rib coverage than many screening methods. Because standing support is typically part of the roof-control plan in longwall tailgates, no additional standing-support costs are incurred. IntroductionRib safety in underground coal mines is an oft-studied topic because ribs are high-hazard areas. An overview of early rib safety research can be found in Jones and Mohammed (2014). There is a significant difference between rib support and rib control. Support improves safety through the installation of strengthening elements, such as bolts and dowels, designed to reduce rib spalling. Although spall reduction is preferred, controlling how the rib fails is enough to ensure safety in some situations. Rib control uses external elements to provide confinement, thereby holding sloughed material in place, or to prevent falling rib material from striking mine personnel. This paper presents a study of a control method used on the pillar side of a longwall coal mine tailgate in the western United States."

Jan 1, 2015