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The Application of Roasting Pretreatment for Antimonial Refractory Gold and Silver Ores

Sep 13, 2010

By K. N. Karparov

The classical limit equilibrium methods are suspected to be ineffective in predicting the potential for highwall failure in many instances in coal mines around the world. Slope engineers have for many years recognized a block thrust failure mechanism for slope failures, but little work had been done before 2000 to explain the actual mechanisms which must be responsible for the failure. The main reason for this is that limit equilibrium methods implicitly assume rigid blocks, and the resulting force equations must be satisfied everywhere simultaneously for them to have any meaning. This paper will show that the material involved in the slope failure is not rigid; indeed it undergoes considerable permanent deformation during failure. This observation allows the authors to treat the block boundaries independently, because they need not maintain a constant spatial relationship with one another, as is assumed in other methods. To enable analysis of this type the authors assume that the weight of the blocks is evenly distributed. This is reasonable, because the slope material is not strong enough to be self-supporting without some sort of constraint, or strong enough to be able to apply point loads to the surrounding material. The purpose of this paper is to extend the practical application of the analytical method developed from mechanism studies to provide an objective assessment of the risk of slope failure, and therefore guidelines for more stable slope designs. This work is based on studies carried out on two failures in an open pit coal mine in South Africa, and provides a methodology to assess the potential for failure more objectively than is possible with currently accepted methods, while at the same time remaining sufficiently simple to allow a ?back of the cigarette box? assessment by geotechnical engineers on site.

Jan 1, 2009

By J. Hartikainen

19 papers were allocated to this session by the paper classification committee, 8 related to bored piles, 5 to continuous flight auger piles (CFA piles), 3 to slurry trenches, 2 to both bored piles and slurry trenches, one of them also dealing with root piles. There were no papers dealing with root piles only, as root filling is a different technique. One paper concerns sheet piling (Table 1). Table 1. Papers for session 1: Recent Technological Developments in Deep Foundations with Soil Excavation. [ ] Table 2. Classification of pile type in Belgium - van Impe W.F. /10/. [ ] Trends in piling Trends in piling in Central Europe were studied by van Impe for his brilliant lecture to the Finnish Civil Engineering Society. He claimed that bored piling is on the decrease and CFA pilling on the increase (Table 2). Thus the numbers of papers presented here do not conform to recent developments or trends. The papers submitted arc of course influenced largely by the fact, observable in Table 3, that bored piling is

Jan 1, 1994

By Giovanna Valdivia Málaga

Dado que la comunidad de Michiquillay recibe una gran cantidad del canon minero a través de la gestión de la Municipalidad del mismo nombre, se planteó mejorar las relaciones de parentesco y la inmersión en la modernidad económica y socia de dicha comunidad y pasar de una economía informal a una economía social o solidaria. En ese sentido, el presente texto describe el proyecto de participación colectiva entre los miembros de la comunidad Michiquilllay y La Encañada, con el objetivo de construir una propuesta de privatización del proyecto minero Michicallay. El trabajo de campo se realizó en los ocho sectores y se desarrolló desde hace dos años, alcanzando la comunicación y sostenibilidad del mismo.

Sep 12, 2011

By R. W. Pugh, D. G. Bellow

"This paper will describe how cultivator shanks are made in one company and how the manufacturing was studied with a view to increasing product consistency and reducing manufacturing cost. The product: which is used extensively in the agriculture industry, was analyzed to determine which geometric parameters optimized its design and whether there was justification for the great variety of styles and shapes that are available in the market. Finally, an extensive series of field trials were undertaken which showed that it is advantageous to the manufacturer to be better aware of the loads and forces that his product is subjected to by another industry.IntroductionStelco maintains a Research Group for its Western Region operations headquartered in Edmonton, Alberta. Because of the small staff, a location that is isolated with respect to its Burlington, Ontario centre and a diverse set of processes and products, a university relationship has developed which may be different from that which would be developed at a larger integrated Steel Works. This paper outlines the type of cooperative studies carried out by Stelco Inc. in Edmonton and the University of Alberta. .To meet the research needs covering a wide variety of steelmaking processes and steel products produced in Edmonton would require more staff and equipment than the sales volume in the West justifies. The gap is filled by cooperation with university personnel. This cooperation has provided these benefits to Stelco Inc.:• access to specialized test equipment and a trained staff to operate it; and• assistance from experts in the areas of product testing and problem solving.Moreover, the close proximity of the university to the plant allows frequent meetings and ensures that practical solutions are developed and implemented. A good example of the ongoing university I industry relationship developed is the joint work on improving cultivator shanks."

Jan 1, 1982

By H. Jalkanen, L. Holappa

The main role of slag in oxygen converter processes is to absorb the non-volatile oxidation products of hot metal impurities, Si, P, Mn, Ti, V, etc. The importance of converter slag as deP and de Smedia has ceased with implementation of special pre- and post-converter treatments. The transfer from top blowing (LD) to combined blowing converters has decreased the amount of slagged iron that, together with the tendency towards lower silicon and manganese contents, has decreased slag to steel ratio. Still the control of slag forming and behaviour during the blow is of great importance. In this paper the thermodynamics of the slag forming reactions, the role of slag in the modern oxygen converter process for impurity elimination, splashing, lining wear, dust formation and post combustion are discussed on the basis of common knowledge and experience of Finnish steel plants.

Jan 1, 2004

By Edmund J. Cardoza

The paper describes the design, construction and quality control aspects of the installation of a cement-bentonite (CB) cut off wall to impede seepage through a flood control dike. Special emphasis is placed upon the development of a proper specification, distinguishing the CB method from the Soil-Bentonite technique. The importance of the pre-construction laboratory testing program and field quality control procedures is emphasized by the fact that the in-place properties and characteristics of the CB cut off may not be known until after a majority of the work is complete. Sections are included which describe the construction method, the specialty equipment and personnel requirements and the quality control/quality assurance aspects of the project.

Jan 1, 1992

By F. Bruey

The Factorial Model Experimenters are often interested in systems that are multi-factorial. A multi-factorial system is one whose output is believed or known to be dependent on the particular settings of several inputs, or factors. We can think of these factors as defining a space, with each point in this space corresponding to a particular set of factor settings. Experimenting can be thought of as exploring this space - finding out how the response of the system changes as factor settings are changed. There are several challenges in this exploration, among which are deciding what region to explore, designing an experiment that explores it most effectively, and describing the results of the exploration. This paper deals principally with the last of these; it shows how the factorial model can be used to describe how the response of the system changes as factor settings are changed. A strength of the factorial model is that it treats the factors as causes of change in the system's response and focuses on relations among these causes. In particular, the factorial model focuses on whether causes act independently on the system (in a sense to be explained below), or whether they interact. This is important because the experimenter generally seeks to control the system, and because control based on causes that act independently of other causes is relatively simple, whereas control based on causes that interact is more challenging. Also, mapping the space - finding out how the response of the system changes as factor settings are changed - will require less work if, during the exploration, it can be determined which of the causes act independently. For the sake of example, let us assume that the space we are exploring is three-dimensional, and that we have already defined, for each of the three factors, the range of interest. Let us consider all the ways in which the response of the system might depend on the settings of these three factors. In the simplest case, the response in this region does not depend on any of the factors. The response is constant throughout the space, at say, 80 units.

Jan 1, 2007

By Dennis Dolinar

Improperly designed support systems have led to unplanned roof falls in longwall tailgates. To prevent such falls requires appropriate support and adequately designed support systems. The National Institute for Occupational Safety and Health (NIOSH) is currently developing a standing support design methodology based on the ground reaction curve. To design the support system with this methodology requires a quantitative assessment of the ground and support interaction, which is developed from instrumented test sites installed in longwall tailgates. To compliment and expand the field data results and to optimize the support design, numerical modeling is also conducted. The models are calibrated from the test site data. In the present study, data was obtained from a longwall tailgate in the Illinois basin. The test site was located in the Herrin No. 6 coal seam at a depth of 500 ft. At the site, the immediate roof was a weak shale overlain by a competent limestone. Above the limestone, sandstone formed the intermediate roof. The floor consisted of a weak underclay. In the study, the performance and interaction with the surrounding rock mass of two different standing supports, an engineered crib and a conventional 4-point wood crib were monitored. The two cribs have similar load-displacement characteristics at least through 6 in of displacement. Beyond 6 in, the engineered crib becomes unstable and begins to strain soften and shed load. The measurements and developed ground reaction curves indicated that the tailgate at the mine was a low convergence environment until well inby the face. Because the convergence was well below their capacity, both supports provide more than adequate levels of support to the tailgate. Significant convergence and support loading did not occur until 90 to 100 ft inby the face. The results of this study were also compared with results from similar studies conducted in the Pittsburgh seam to further advance the development of the ?ground reaction curve? based support system design.

Jan 1, 2009

By M. M. Fine

"INTRODUCTION One of the principal activities of the Bureau of Mines during the recent war was to help to increase the supply of strategic and critical minerals. Fluorite was one of the most critical of the nonmetallic minerals because of the increased demand for it as a flux in basic open-hearth and electric steel furnaces and as a raw material for the production of artificial cryolite used in the aluminum industry. Wartime developments in the technology of hydro-fluoric acid, such as the use of the anhydrous acid as a catalyst in high-octane-gasoline production and the use of organic fluorides as carriers for insecticides, also increased the demand for acid-grade fluorspar. 2/ In 1943 the consumption of acid-grade fluorspar was advancing at a more rapid rate than production and was only slightly less than production during the latter half of the year.The outlook for the postwar market for fluorspar is encouraging. Steel production is expected to remain high until the domestic demand for commodities not manufactured during the war is satisfied. The uses for hydrofluoric acid also are expected to increase under the impetus of war-initiated research. In consideration of these and other factors some authorities predict a new peacetime demand for fluorspar equal to 60 to 75 percent of the war production, 5/ 6/ and others believe that the fluorspar industry will be permanently expanded. 7/"

Dec 1, 1947

By S. Uddin

An integrated device has been developed to measure sedimentation potential, conductivity and pH simultaneously of particulate systems. Maxwell?s model was used to calculate volume fraction of solid from the conductivity data. In this approach, all system variables are known and zeta potential can be calculated from Smoluchowski?s equation. The technique is validated by comparing zeta potential vs. pH for alumina and silica suspensions with electrophoresis measurements. The technique was extended to mixed alumina/silica systems. Sufficient column height along with size difference between the two minerals allowed gravity fractionation during settling. Sedimentation potential measured over time identified the transition from one mineral to the next. Using XRD analysis the results supported the correlation between surface charge and sample composition. This is a step towards characterizing surface charge of mixed systems of interest in mineral processing.

Jan 1, 2010

By Charles M. Mason

The Bureau of Mines evaluated equipment and procedures for drop-weight testing of explosive liquids as prescribed by Test 4) a widely used method. It was demonstrated that partial ignitions, originally designated as negative results, should be designated positives; it was also shown that wear or erosion of the sample cups and the type of mount used for the apparatus had important effects on the results. Relative sensitivity as measured by Test 4 was found to vary slightly with temperature. The Bureau also designed a fixed 2-kg weight and associated electromagnetic release, which subsequently were incorporated as standard in a revision of Test 4. The original concept that the test involves only adiabatic compression was found to be an oversimplification; an alternate mechanism for the initiation process is proposed in which due consideration is given to the effects of cavitation and microjets.

Jan 1, 1966

By G. L. Bartlett

"INTRODUCTION The major objective of our research is to help reduce the incidence and severity of coal worker's pneumoconiosis (CWP). To that end, this project is designed to improve our understanding of the processes that lead to pulmonary dysfunction following mine dust exposure, and how those processes might be interrupted or attenuated. The response of the lung ' to inhaled particles is complex, and the course of development of disabling CWP is slow and unpredictable. From among the numerous cellular and molecular interactions involved in the pulmonary response to inhaled particles, this project is focussed on the role that the pulmonary alveolar macrophage (PAM) may play in regulating the activity of fibroblasts.The PAM is the lung cell that has the most immediate and the most obvious interaction with inhaled particles. Within a short period after particles are arrested in the alveolus of the lung, they are phagocytized (engulfed) by these specialized cells. The PAM then has a diverse potential repertoire of subsequent activities. Which reaction actually ensues is determined, in large part, by the nature of the phagocytized _particles. Activated PAMs produce a variety of products that may affect adjacent lung tissue, including superoxide free radical, elastase, collagenase, prostaglandins, platelet activating factor, etc. Those may well be important in the pathogenesis of CWP, but they are beyond the scope of this project. Background information that is cogent to this project has come primarily from investigations using animal models of silicosis and asbestosis. PAMs that have ingested silica particles synthesize and release molecules that control the behavior of surrounding cells. One such mediator is interleukin-1 (IL-1), a molecule that plays a central role in many aspects of the response to injury. It can stimulate fibroblasts (the cells that help to hold tissues together) to release the enzyme collagenase, resulting in breakdown of the structural collagen fibers that support the lung tissue. IL-1 also stimulates fibroblasts to undergo mitosis and to proliferate, which is an initial stage of fibrosis. Certain stimulants cause PAMs to release fibroblast growth factors (FGFs) that are distinct- from IL-1. Under other circumstances activated PAMs synthesize and release molecules that stimulate fibroblasts to accelerate synthesis of collagen fibers, thus contributing to fibrosis. Although these observations provide a valuable precedent for analysis of the mechanisms involved in CWP, their relevance to CWP cannot be assumed since most of those studies involved macrophages or fibroblasts obtained from tissues other than the lung, and because almost none of them have used CMD as the stimulating particles. Therefore, the goal of this project is to learn how exposure to CMD affects the behavior of PAMs, and in turn how products of dust-exposed PAMs affect fibroblasts and the process of fibrosis in the lung."

Jan 1, 1988

By M .. Hori, H. Onishi, Y. Goda

The split-lining structure was newly developed for the air-tight lining of the underground compressed air storage cavern. This structure consists of separated reinforced concrete (RC) segments and air-tight membrane. It is most important for the Compressed Air Energy Storage Gas Turbine (CAES-G/T) system to develop the economical lining. In order to verify the applicability of split-lining structure, CAES-G/T pilot plant was constructed and operated for 6 months. We confirmed the practical usefulness and safety of this system through the operation. This paper presents the mechanical behaviour of surrounding rock mass and the lining structure observed through the operation of CAES-G/T pilot plant. Nous avons mis au point une structure de revêtement modulaire pour le revêtement des cavernes souterraines hermétiques à pression. Ce revêtement est composé de segments de béton armé et de membranes hermétiques. Il était très important, pour le CAES-G/T (Compressed Air Energy Storage Gas Turbine), de développer un revêtement économique. Afin de vérifier l’aptitude d’application de notre revêtement modulaire, nous avons construit un système pilote CAES-G/T et nous avons effectué des essais de fonctionnement pendant six mois. Ces essais nous ont permis de confirmer l’utilité et la sécurité du système. A travers le présent rapport, nous rendons compte de la structure de ce nouveau type de revêtement et du comportement mécanique de la masse rocheuse environnante que nous avons pu observer au cours desdits essais. Als luftdichter Druckbehälter wurde eine gegliederte Belagsstruktur für tief unterirdisch liegende Felshöhlungen entwickelt. Diese Struktur ist aus Stahlbetonabdeckung und luftdichter Plane aufgebaut. Bei der Entwicklung des Pressluftgasturbinen – Stromerzeugungssystems (CAES-G/T) war es die wichtigste Aufgabe, einen wirtschaftlichen Belag zu entwickeln. Deswegen wurde zum Nachweis der Effektivität der gegliederten Belagsstruktur eine Pilotanlage errichtet und 6 Monate lang betrieben. Durch den Betrieb konnten wir die Praktikabilität und Sicherheit des Systems bestätigen. Dieser Aufsatz ist ein Bericht über das Verhalten der durch Betrieb der CAES-G/T Pilotanlage beobachteten Belagsstruktur und umliegenden Felsmasse.

Jan 1, 2003

By Giovanni A. Bonita

The new Embassy of the Peoples Republic of China in the United States (Chinese Embassy) is located in the Embassy Row portion of Northwest Washington DC. The 475,000 ft2 (44,125 m2) structure has five levels below ground and four above, making it the largest embassy in Washington DC. The structure approaches the property line on all sides, and is immediately adjacent to several foreign embassies and a secure U.S. Federal Building. A vertical soil nail wall was used as the primary support of excavation (SOE) system for the project. The soil nail wall was irregularly shaped, benched in areas, and reached total heights up to 98 feet (29.9 m). The soil nail and shotcrete system consisted of approximately 1,600 soil nails and 50,000 square feet (4,645 m2) of exposed shotcrete wall surface. Tight excavation requirements were defined for the project due to the location of the building relative to the property line, requiring fairly precise wall positions and shotcrete tolerances. Design challenges included soft soil conditions, inside wall corners, underground utilities, and seismic impacts from blasting. The paper will focus on the design, construction, and performance of the soil nail SOE system, as well as touch on the logistical and political factors that influenced the design. The paper also notes the Value Engineering and communication approaches that were generated during construction. These efforts resulted in a significant improvement in the quality control and quality assurance exhibited on site, expedited the schedule, and led to significant cost savings to the contractors, engineer, and owner.

Jan 1, 2006

By Gunderson C. T

The use of carbide tipped integral drill steels and detachable bits is discussed in relation to the means of drilling or cutting employed. It is stressed that only by correct use can the full value of these tools be realised.Factors affecting carbide quality, the design of shanking steels and the requirements and techniques of brazing in inserts are considered.It is essential that the brazed jointing between carbide and steel be strong but ductile. The methods used for the manufacture of carbide tipped tools are briefly outlined.INTRODUCTIONIn recent years the application of tungsten carbide to various mining tools in the mining industry, has developed to the stage where it is now regarded as an essential item in the production of coal and metal ores. In fact it is claimed that certain mining operations would not be possible if it were not for the benefits obtainable from the characteristic properties of tungsten carbide. The advantages of this hardmetal have, to some extent, influenced manufacturers to revise design specifiations of some machines, while againsome machines have actually been designed with tungsten carbide as their basic medium for operation.In general the applications fall into the following three categories:(a) Drilling hard rock by percussive means.(b) Drilling soft rock and coal by rotary means.(c) Coal cuttingThis paper is concerned with tungsten carbide tools associated with these three activities in Australia, the effectiveness of their application and significant points in their design and manufacture.

Jan 1, 1958

By Frank K. Cameron

"The DepositsThere are two large deposits or groups of deposits of potash salts which, at the breaking cut of the great world war in 1913 and for several decades preceding, were practically the only commercial sources of supply for the entire world. In both cases the origin of the deposits was sea water, the potassium salts being deposited by desiccation, but there were modifying factors which were not entirely the same in both cases so that well defined and important differences exist in these deposits. The larger and better known group, called the Stassfurt Deposits, are in Germany in the region about or adjacent to Magdeburg and Halberstadt. The general character of these deposits and the methods for recovering potash from them have been frequently described, not only in technical publi¬cations, but in the non-technical propaganda long maintained by the Kali Syndikat, an organization founded on a ""cartel"" with the supervision and support of the late Imperial German Government.Less well known are the smaller though nevertheless extensive deposits in the neighborhood of Mulhouse in Upper Alsatia, which were also under the control of the Kali Syndikat at the breaking out of the war but have now passed to French control, with the reentrance of Alsace into the French Republic.The Alsatiaa deposits, while less extensive than the German deposits, are, nevertheless of great magnitude. They occupy a large part of the area between the Vosges Mountains and the River Rhine, from Col¬mar on the North to Mulhouse on the South. Indeed a few borings on the East bank of the Rhine indicate that the deposits may extend under the river and to some distance beyond Buggingen Linken, Baden, though it has not been Shown as yet that this extension is of commercial significance.As is well known, the Stassfurt potash occurs as potassium chloride or potassium sulphate or both salts, intimately mixed with salts of sodium, magnesium eau& calcium (lime) and contaminated with substances. insoluble in water such as ferric oxide, clay etc. The potash salts are segregated in more or less extensive 'pockets' throughout the salt mass, these segregations departing usually from the horizontal. But the main ""potash region"" is a stratum varying from 30 to 150 feet in thickness and at a depth requiring shafts 5000 feet."

Jul 1, 1919

By P. W. J. van Rensburg

Our mineral heritage - PRESIDENTIAL ADDRESS given by P. W. J. van Rensburg, Pr. Eng.. B.Sc. (Eng.)(Rand) INTRODUCTION Stone Age people were living in various parts of South Africa as recent,ly as a thousand years ago, when they were displaced by Iron Age people with a culture developed in the far north. These invaders brought farming, building, and the earliest mining developments to the Transvaal, thus ushering in the beginning of our great mineral heritage. It is of particular interest to record that, up to comparatively recent times, some of these people were excavating iron-bearing shale rocks for their smelting furnaces on the Melville Koppies in J ohannesburg. Although the most recent the iron-smelting furnaces discovered on these koppies is estimated to be some five-hundred years old, it believed that these Iron Age people were driven out, and their settlements destroyed, by Zulu impis only one-hundred-and-fifty years ago.

Jan 10, 1973

By W. Pawlos, A. Bakalarz, M. Duchnowska

This paper presents the results of an investigation into the influence of hydrodynamics on a preflotation process for the copper sulfide ore from the Fore-Sudetic Monocline deposits in Poland in a flotation machine. The main aim of the preflotation stage for Polish copper ore is to remove the easy-to-float organic matter — organic carbon — that causes serious problems in metallurgical processes. The organic matter is connected with the presence of shale ore. This paper describes the preflotation experiments conducted to investigate the effect of various stirrer speeds. The upgrading selectivity of copper and organic carbon were analyzed and compared. The results show that the effectiveness of separation between organic carbon and copper decreases with increased stirrer speed in the laboratory flotation machine. The more intensive the mixing of the flotation suspension, the lower the selectivity of the preflotation experiment. Lower stirrer speed probably provides lower mechanical entrainment and flotation of copper minerals.

By R. R. Sayers

The increasing use of hydrogen fluoride (annual consumption now exceeds 500,000 pounds (1)4/) directly and its occurrence as a byproduct of the utilization of fluorine compounds in the mineral industries, especially in metallurgical processes and in the refining of petroleum products, has aroused interest in its toxicity, and a brief review of the literature, with special reference to the hazard of poisoning in the mineral industries, seems to be opportune. Recently, residents in the vicinity of aluminum plants have been complaining of injury to livestock and vegetation as well as to their own health from the gases discharged into the air during operation of the plants, hydrofluoric acid gas apparently being the offender. The comparatively recent utilization of hydrofluoric acid in the alkylation process for the production of high-octane gasoline has raised the question of the hazard of poisoning in the petroleum Industry. In addition, the use of fluorine-containing refrigerants has extended the potential al exposure outside of industry (2).

Jan 1, 1945