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The ready solubility of gold in dilute aqueous solutions of the cyanides of the alkalies or alkaline earths provides a convenient method for the separation of the precious metal -from the large surplus of associated materia1. The finely ground ore is pulped with a weak solution of cyanide, agitated to dissolve the gold, filtered and washed. The lowgrade filtrate is then clarified and the gold precipitated by some electronegative agent, the most usual being finely divided zinc or zinc dust. The slight precipitate is collectedon some form of filter coated with a filter aid, the filter cake being then known as "gold slime".A typical analysis of this slime is given in Table 1.

Jan 1, 1956

By Robert Leach

THIS paper gives a brief summary of the process of manufacture of sterling silver, and some of its more important physical properties, as observed in commercial production of rolled sheet and wire. Although papers have been published by Turner and Smith,1 Rose,2 Sperry3 and Jordan,4 there are few technical data available, and unfortunately the time allowed for the preparation of this paper has not been sufficient to make it as comprehensive as the title might indicate. ANALYSIS OF STERLING SILVER Fine or pure silver is too soft for coinage and the manufacture of articles in which strength and resistance to wear are desired. From the earliest times of which we have record, copper has been the metal generally used to harden silver. Analyses of coins and silver articles from ancient tombs show varying amounts of copper, and old Roman silver objects in the British Museum have approximately the same analysis as our sterling. The first authentic record of the establishment of a standard alloy is during the reign of Henry II in England. During the twelfth and thirteenth centuries, the people in the Eastern Provinces of Germany had a reputation for the standard and purity of their silver coinage, and it is said that Henry II employed some of these Easterlings, as they were called, to improve and standardize the English coinage, which had become debased. The peculiar standard adopted is probably accounted for by the system of weights used. A troy pound contains

Jan 1, 1928

By D. M. Hausen

A computer program has been developed by Newmont Exploration to convert mineralogic data by XRD into rock type and ore type classifications. This method has proven useful in identifying lithology from cuttings samples, where percussion drilling was an alternative to expensive core drilling. Computer printouts of rock type and ore type identifications can be generated simultaneously with mineralogic analyses, resulting in a considerable time savings in manual calculation. XRD-computer logging was first applied to the Carlin mine in north central Nevada, and later to the Maggie Creek and Gold Quarry gold deposits, southeast of the Carlin mine. Impure Paleozoic limestones of the "lower plate" Roberts Mountain Formation and the "upper plate" transitional facies have been decarbonatized to altered siltstones and shaley units along vertical faults and permeable stratiform horizons. Advanced stages of decarbonatization were accompanied by silicification. Quantitative XRD data are initially sorted into principal rock type units (limestones, siltstones, dolostones, shales) based on major mineralogic components (calcite, quartz, dolomite, clays). On the basis of relative amounts of less major constituents, descriptive subclassifications (dolomitic limestones, dolomitic siltstones, argillaceous cherts) are made. XRD lithologic data provide assistance in correlating lithologic units, and delineating favorable replacement horizons associated with gold mineralization.

Jan 1, 1982

By Yoginder P. Chugh

Subsidence may be observed above partial extraction shallow room-and-pillar mines where the coal seam(s) is associated with weak and thick claystone in the floor. This paper presents results of subsidence studies at such a mine. During the 26-month study period, a time dependent subsidence causing a maximum vertical movement of 50 mn was observed. After a subsidence rate of 6.0-6.5 m/month for the first two months after development of mine workings, the rate decreased to 0.8-0.9 mm/month after 17 months. However, presumably due to settlement of barrier pillars, it increased therafter to 1.7 mm/month for the next 9 months. Angle of draw, based on zero subsidence, was calculated to be about 29 degrees. Maximum tensile strain and compressive strain values observed were 0.040 pct and 0.039 pct respectively. A hypothesis was fomlated to correlate surface subsidence movements with observed underground movments. The data collected to date fits reasonably well within the formulated hypothesis.

Jan 1, 1989

The 107th Annual General Meeting of The South African Institute of Mining and Metallurgy was held at The Country Club, Johannesburg, Napier Road, Auckland Park on Wednesday, 11 August, 2004. Welcome The President extended a special welcome to the guests and representatives of our sister institutes and other associations, also to recipients of awards, senior members of industry, Honorary Life Fellows, past-presidents, our members and other guests, among them the following: Ralph Bagirathi, Executive Member, African Mining Association Rudi Rudolph, President, Association of Mine Managers of South Africa Andrew Whibley, President, Association of Mine Resident Engineers of South Africa Dr Con Fauconnier, President, Chamber of Mines of South Africa Nxolisi Diliza, Chief Executive Officer, Chamber of Mines of South Africa

Jan 1, 2004

By Allan E. Koski

Ceveland-Cliffs uses a specialized software package in mine planning at the Empire Mine, an iron ore mine it manages on Michigan’s Marquette Iron Range. The application puts together years of mining experience that began in the early 1960s on the eastern end of the Marquette Range. The Empire Mine is in its 38th year of production. It uses the software to model a complex and highly variable low-grade magnetite ore body, capturing the economics of mining and processing to the final product. With special attention given to geostatistical methods, the software is used for all geologic modeling, ore reserve estimation, ore control, pit design and short- and long-range planning.

Jan 1, 2000

By Thornton L. Neathery

Vertical magnetic surveys have been made over about 3, 150 miles of the crystalline area of east-central Alabama. A contour map (100-gamma interval) showing regional magnetic anomalies has been prepared (scale 1:250,000) from data points located at quarter-mile intervals on all public roads. Small one- and two-station anomalies were eliminated, leaving only areally extensive anomaly features associated with regional geology. The regional gradient was "filtered" from the basic data and the resulting magnetic configuration compared to the regional geology. Regional lines of vertical magnetic intensity trend northeast and follow the structural framework of the area. Correlations can be made between a large number of geologic and magnetic features. The strongest regional anomalies are associated with the Goat Rock, Bartletts Ferry, Towaliga, and Brevard fault structures. The Inner Piedmont area is characterized by a broad regional high. The magnetic values of the northern Alabama Piedmont grades gently northwestward, disrupted occasionally by elongate highs and lows associated with amphibolites or granites. Scattered throughout the Piedmont are anomalous areas of high magnetic intensity; some are related to magnetic-bearing rocks, and some Indicate possible mineralization. Most of the anomalies have not been evaluated,

Jan 1, 1972

By Marlion T. McQuinn

This paper will discuss the design, construction, and performance of the support of excavation on the Dulles East and West Automated People Mover Tunnels and Station projects. The elements of the system included drilled soil nails and rock anchors with reinforced shotcrete to the excavated face. We will discuss the geotechnical characteristics, design and construction considerations, loading criteria, construction techniques, schedule constraints, and performance of the support of excavation system. In consideration of the conference theme, there will be a discussion of the application of the real-time instrumentation monitoring program. The project team worked to design and install approximately 710,000 square feet of shotcrete and 19,000 soil nails/rock anchors as well as excavate over 720,000 cubic yards of rock materials within 15 months and in such a manner as to minimize the disruption to airport passengers and operations.

Jan 1, 2006

By André Vien, Pedro Gonzalez, Julio Palomino, Rob Perry

"In many mineral processing plants ore is reclaimed from a stockpile using multiple feeders. The discharge from these feeders is combined onto a single conveyor from which total tonnage is measured. Typically, operators set feeder output ratios to adjust the proportion of total tonnage drawn from each feeder. From a process control perspective, this system is not easy to control because the response time of each feeder depends on the distance from the feeder to the weightometer. This paper proposes a simple and elegant process control strategy to manage feeder ratio changes and the associated long and varying process dead-times. Changes in feeder speed are delayed and filtered to compensate for transport delays between feeders. The strategy was evaluated by simulation and installed on a mill feed system.ResumenEn numerosas plantas procesadoras de minerales, el mineral es extraido desde una pila de almacenamiento usando varios alimentadores. La descarga de estos alimentadores es recibida por zinica correa transportadora, en la cual se mide el tonelaje total. Comzinmente, los operadores colocan un valor determinado en cada controlador de razdn para ajustar la proporcidn del tonelaje total extraido por los alimentadores. Desde el punto de vista del control automatic0 de procesos, este sistema es dijkil de manejar debido a que el tiempo de respuesta de cada alimentador depende de la distancia de este respecto a la ubicacidn del pesdmetro. Este trabajo, propone una estrategia de control, simple y elegante, para compensar los cambios de razdn a cada alimentador y los tiempos muertos del proceso largos y variables. Los cambios en la velocidad de los alimentadores son retardadas y filtradas para compensar los retardos del transporte entre alimentadores. La estrategia fue evaluada por simulacidn, instalada y probada en un sistema de alimentacidn a molino."

Jan 1, 2000

By Markus Reuter, Antoinette van Schaik

In this paper the link between process metallurgy, classical minerals processing, product centric recycling and urban/landfill mining is discussed. The depth that has to be achieved in urban mining and recycling must glean from the wealth of theoretical knowledge and insight that have been developed in the past in minerals and metallurgical processing. This background learns that recycling demands a product centric approach, which considers simultaneously the multi-material interactions in man-made complex ‘minerals’. Fast innovation in recycling and urban mining can be achieved by further evolving from this well developed basis, evolving the techniques and tools that have been developed over the years. This basis has already been used for many years to design, operate and control industrial plants for metal production. This has been the basis for Design for Recycling rules for End-of-Life products. Using, among others, the UNEP Metal Recycling report as a basis (authors are respectively Lead and Main authors of report), it is demonstrated that a common theoretical basis as developed in metallurgy and minerals processing can help much to level the playing field between primary processing, secondary processing, recycling, and urban/landfill mining and product design hence enhancing resource efficiency. Thus various scales of detail link product design with metallurgical process design and its fundamentals.

Jan 1, 2014

By C. C. Merrill

The Bureau of Mines beneficiated the wastes generated by commercial titanium chlorination operations to reclaim metal values and reduce the problem of disposing of solid wastes. A water leach solubilized about 40 percent of the dry weight and over 75 percent of the metallic impurities. The residue from the water leach was rich in titanium dioxide and carbon; it was combined with rutile and recycled to a laboratory chlorinator. The contained carbon was used in lieu of part of the coke requirement.

Jan 1, 1969

By R. Karl Zipf

The sudden, violent collapse of large areas of room-and-pillar mines poses a special hazard to miners and mine operators. This type of failure, termed a "Cascading Pillar Failure" (CPF), occurs when one pillar in a mine layout fails transfering its load to neighboring pillars causing them to fail, and so forth. Recent examples of this kind of failure in coal, metal and nonmetal mines in the U.S. are documented. Mining engineers can limit the danger posed by these failures through improved mine design practices. Whether failure occurs in a slow, nonviolent manner or in a rapid, violent manner is governed by the local mine stiffness stability criterion. This stability criterion is used as the basis for three design approaches to control cascading pillar failure in room-and-pillar mines, namely, the containment approach, the prevention approach, and the full extraction mining approach. These design approaches are illustrated with practical examples for coal mining.

Jan 1, 1996

By F. R. Hensel

P. R. Kalischer.*—I should like to amplify a little one of the points made by Dr. Hensel, and rather violently disagree with him at the same time. He brought out the point that when the higher forming pressures are used on the green compacts there is a marked decrease in the density as sintered. We found that to be true and, of course, many of you notice that that is true with copper compacts also. But, in my opinion at least, it is not true that the expansion is due to entrapped air. We have vacuum-pressed both silver and copper compacts and obtained almost exactly the same numerical expansion as we secured by pressing in air. The powder, however, that is vacuum-annealed does show a slight decrease in expansion on sintering, but almost the entire increase on expansion can be overcome by very slow rates of heating. And it is our opinion that a majority of the expansion is due to dissolved oxygen in the discrete metal particles themselves rather than to entrapped gases. Another interesting observation that we have made is that often with silver or copper compacts it is desirable to silver solder or braze the compact into some part of a piece of equipment after completing powder metallurgical operations on it. If such a compact is sintered and coined, say a silver compact, given an initial forming pressure of 10 to 15 tons per square inch, and sintered, there is an adequate amount of shrinkage and it can be coined at about 50 or 60 tons per square inch and bring up the density nearly to theoretical. If, then, that compact is silver-soldered into some part of a fixture or a machine, it will expand very beautifully, and the only way that this can be overcome. as far as we know, has been to reanneal after the coining operation at a temperature higher than is to be used in any subsequent operation. In that way, a density very nearly theoretical can be achieved, but the coining operation cannot be carried to the excessively high pressures or expansion and bubbling of the compact will occur again.

Jan 1, 1945

By C Thompson, D Connelly

The history of mill liners has evolved over time and this paper tracks the changes and development of liner technology. It provides an overview of the primary types of liners, the design and the materials of construction. The design of a mill liner is driven by application, materials of construction, casting technology and handling issues. The choice of solid steel, grid liners, rubber or composites and magnetic liners is based on many factors.The methods used for monitoring wear and predicting eventual change out time are many and varied. The contribution of discrete element modeling (DEM) analysis in predicting wear profile is discussed.Mill trajectory and DEM software programs are used with great effect to predict the effect of lifter height, face angle, high low lifters or mill speed. In the field, trial and operational experience is used or improvements/design concepts at one operation are applied to another. Broken mill lifters, accentuated wear and other problems can be better understood using hardness testing, chemical analysis and photo micrograph analysis of pearlitic or martensitic structure along with fracture face observations. This forms a part of the typical root cause analysis. However given correct and sound liner and lifter, feed and discharge design media selection, and materials of construction, the majority of premature liner or bolting failure is normally attributed to incorrect operational methods such as excessive high ball to feed ratio, incorrect mill speed relating to lifter ball throw, incorrect media selection, "tramp" material entering the mill charge from upstream or recirculating process and understanding the specific mill operation in question.It is hoped that this paper will benefit mill operators who are faced with challenges of improving wear life and at the same time optimizing mill throughput and performance.CITATION:Connelly, D and Thompson, C, 2013. The selection design and application of mill liners for large wet grinding mills, in Proceedings MetPlant 2013 , pp 133-140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By Dennis Nottingham

Spin-fin pipe piles can develop large loads in tension, thus have evolved as a foundation product of great potential. Currently, over 500 spin-fin piles have been used successfully in dolphins, docks, buildings and bulkheads. Spin-fin piles are pipe piles with plates welded near the tip at a batter-in-screw fashion. Thus, as the pile is driven, the pile screws into position. Tests show this pile type to have highly unusual stress/strain relationships, wherein plunging failure is usually never reached either at normal or large deformations. Tension capacity can approach pile capacity in bearing; thus, large reserves are usually available for tension. Tests have been performed on 8-5/8-inch to 24-inch-diameter piles in silt, sand, and gravelly soil, to provide a broad spectrum of data.

Jan 1, 1990

The Bega granite at Whipstick, N.S.W., consists of a granite metasomatically altered to leucogranites and a spessartite-granite. The ore occurs in pipes controlled by jointing and shows evidence of post-depositional tectonic forces.The principal ore minerals are molybdenite and bismuthinite, with minor amounts of uraninite, pyrite, gold, bismuth, joseite A, joseite B, tetradymite, chalcopyrite, arsenopyrite, and skutterudite. The gangue minerals are microcline, albite, quartz, muscovite, and spessartite, with fluorite, chlorite, magnetite, and biotite as accessory minerals.The intrusion of granite was followed initially by ascending metasomatic fluids which penetrated along joints to be trapped in the domed roof of the intrusion to form the leucocratic granite. Iron-manganese-rich fluids metasomatically altered the granite to a spessartitegranite which is associated with the later deposited ore.Quartz veins and dykes of varying composition post date the ore deposition.

Jan 1, 1968

By Dexter C. Hatch

At MacIntyre Development of the National Lead Company, Taha s, New York,, the flotation plant was set up to recover ilmenite from the finer size fraction of the ore that cannot be efficiently treated in the main gravity-magnetic separa¬tion process. It was later expanded to handle the reground middlings from the tables wetherill magnetic separators. The ilmenite-magnetite ore is ground to minus 20 mesh in five 6 x 12 ft. rod mills in closed circuit with DSM screens. The minus 20 mesh screen undersize is pumped to four parallel sections each consisting of two rougher wet-magnetic separators and one cleaner separator for magnatite removal. The screen undersize from the fifth section is distributed to all four sections. The magnetite removed in the roughers is pumped back to the cleaners and the cleaner magnetite is dewatered in rake classifiers and carried by belt to the winter plant or the stockpile area. The nonmagnetic sands from rougher and cleaner magnetic separator are sized for table feed in eight pocket hydraulic sizers. The slime overflows from the Crocketts, the sizers, and the magnetite rakes are collected and pumped to three-inch cyclones for thickening and desliming. The cyclone underflow is the principal flotation plant feed.

Jan 1, 1962

By W. A. Gibson, A. D. Trujillo

The Santa Rita copper deposit first served as a source of native copper for Indian implements and weapons. In 1801 Santa Rita copper, trans- ported by mule train to Chihuahua, began to be used commercially for making coins. It was a small- scale operation made difficult by Indian raids, transportation costs and depletion of the higher grade ores. There was, moreover, no known method for economically extracting copper from the under- lying low grade sulfide ores. Originally, copper and copper oxide ores were mined by underground methods, but there was virtually no development of the deposit-which became United States territory after the Treaty of Guadalupe Hidalgo in 1848-for almost a hundred years. A number of small underground mines had been started during that time, but it was not until 1873 that all the principal claims were consolidated under one control.

Jan 1, 1966

By Patterson B. G

The small party of mining men who formed the original Mount Morgan Syndicate in 1882, commenced operations on the top of the mountain with what were practically nothing more than small hillside quarries, It was not until 1891 that underground stoping began, and open-cut mining therefore commenced with the commencement of operations. This hillside quarrying, however, seems to have been quite haphazard and unsystematic ; there is no trace or sign of any properly devised mining scheme. This can be seen plainly enough from an examination of old mine plans; for in less than five years after stoping was; adopted, the open-cut was down into the stoped-out ground. The following table, prepared from these old plans, shows the downward trend of the excavation in the past fiftyseven years:-

Jan 1, 1939

By Juan Mendoza Marsano

"El presente texto revela las primeras transacciones de la venta del oro en el Perú -en tanto se determina su precio a través de un acuerdo denominado""on the spot"", donde el vendedor ofrece sus mercaderías a uncomprador y se acuerda un precio pagado con dinero al contado y de inmediato. Hasta 1914 el precio del oro estuvo determinado o fijado por la denominación de las propias monedas circulantes de oro y sus monedas equi- valentes. Sin embargo, la primera determinación del oro en el Perú surge en Cajamarca, 1553. Posteriormente se describe la circulación de este durante la Colonia, los diferentes métodos de transacción y las especificaciones del contratos de oro, así como los factores que influyen en el precio del oro."

Nov 1, 1978