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The use of controlled recirculation can be dated back to the early 1930s. Although this method has been applied in many mines since then, a generalized comprehensive network analysis is still lacking. This paper presents a unique approach in which the ventilation network with a controlled district recirculation is divided into two subsystems: a main subsystem and a recirculation subsystem. The subsystems are analyzed individually and the results and their relationships are then integrated into discussions of the total ventilation system. The analysis of the recirculation subsystem is facilitated by introducing a non-dimensional parameter A, which represents the ratio of the air quantity for the working face to that for the subsystem. As a result, fan and regulator pressures and air power for various recirculation arrangements can be effectively expressed as a function of A and the subsystem air quantity. Numerical examples are included.

Jan 1, 1995

By I. H. Gundiler

Although cyanidation has been universally applied in the processing of gold and silver ores, the search for less toxic alternatives continues. Difficulties encountered in processing ores containing oxidized copper minerals and the inherently slow kinetics of cyanidation have generated a renewed interest in thiosulfate leaching. This process, as well as the catalytic effects of copper ion, were well recognized and widely applied towards the end of the past century. In this study, the effects of copper, ammonia, and thiosulfate concentrations on gold dissolution were investigated using the rotating disk technique. Extraction of gold and silver from an oxidized copper-bearing ore was also studied utilizing a statistical experimental design, and these results were displayed in the form of contour plots.

Jan 1, 1993

By Oscar M. Wicken

Iran was a lodestone for the attention of industrial countries and companies wanting to share in its industrial development during the last two decades and particularly after 1972. Prior to 1972, most industrial projects in the private sector were on a relatively small scale and could be carried out in reasonably orderly fashion in spite of limitations of a primitive infrastructure and meager indigenous supply of managerial and technical skills. People with these skills could be found but not in abundance, and many of them were total¬ly engaged in various government ministries and projects. Thus it was that nearly all private sector industries, even long-established ones, required one or more foreigners to give guidance. A barite mine and processing facility was brought on line by Dresser Industries in 1960 without serious operational problems. A few expatriate experts were able to select and train a stable group of staff and production people and establish sound management principles for continued growth. The huge and increasing oil revenues after 1973 gave superficial credence to ideas of the Iranian government that the country could easily finance the jump into the industrial 20th century. All necessary skills and equipment not available in Iran would be imported, and intensive training programs would prepare Iranians for operating the new facilities. Large projects for steel production, copper production, oil refining, petrochemical production, cement production, and others were started or expanded. These are basic industries that consume substantial quantities of refractories. Studies made in 1972 indicated that the existing industries plus expanded and new projects scheduled to come into production would lead to a market sufficiently large to justify a refractory producing plant. Concurrent studies of raw material sources showed that clay, the largest tonnage item, would be locally available; the other raw materials would be imported. Iran Refractories Company (IREFCO) was founded in 1973 and started production in 1976.

Jan 1, 1981

By B. K. Mishra, R. K. Rajamani, R. Venugopal, P. Songfack

Millsoft is a computer-simulation software that predicts the performance of large industrial grinding mills. This software surpasses all other tumbling-mill analysis techniques available today because it is based on fundamental laws of physics instead of empirical correlations. Graphical user interface (GUI) forms simplify the specification of the following design and operating parameters: mill diameter, length, speed, charge density and size distribution, lifter material and geometry. All of these parameters are taken into account in the discrete element numerical technique that constitutes the essence of the simulation software. In turn, the software produces a visual animation of grinding-charge motion, predicts mill power and gives the distribution of impact energy. In this paper, a case study of an 8.5-m-(28 ft-) diam SAG mill is used to illustrate the application of Millsoft for mill design and trouble shooting.

Jan 1, 2000

By Charles Kimbell, L. Nahai, E. Shekarchi

INTRODUCTION AND SUMMARY World mineral trade during 1960 to 1984 has shown substantial changes both in value and tonnage. Although fuel commodities dominated total mineral trade during this period, this paper will focus attention primarily on nonfuel minerals. Brazil and Australia, modest producers of iron ore in 1960, have become dominant producers and exporters, together accounting for about half of major iron ore exports in 1984, far surpassing traditional export suppliers such as Sweden. Australia has also become the largest producer and trader of bauxite and alumina, and worldwide alumina trade has increased at the expense of bauxite trade. Similarly, shipments of ferroalloys have increased more than shipments of ores such as those of chromium and manganese. Canada, retaining its first rank in world export of zinc, has become also the leading source of potash and sulfur in world trade, and South Africa has been the dominant factor in chromite, manganese and their respective ferroalloys. Developing countries' share of world copper trade has increased, with Chile maintaining first rank, but developed industrialized countries have continued to dominate production and trade of lead and zinc. Phosphate, sulfur, and potash have been the principal crude nonmetallic minerals traded worldwide. Looking to the near future, dramatic increases in export of iron ore, phosphate, potash and sulfur are not envisaged. Bauxite exports will continue to decline relative to alumina but at a slower rate than in the recent past. Zinc concentrate will continue to be exported but lead will be traded more as metal than as concentrate. For iron and steel, there will be some production shift from traditional producers to certain developing countries and recently industrializing developing countries such as Brazil, India, the Republic of Korea, and Taiwan. In the following sections dealing with specific commodities, it should be understood that information is presented only on the major forms of each commodity that move in trade, and only for a selected group of countries for each commodity or major form of each commodity. Thus, totals shown or mentioned generally represent only the totals of figures presented here and do not include estimates for minor forms of material or for countries that are not listed. However, the data provided is regarded as sufficiently complete to reflect major patterns and trends, and exclusions are there- fore not seen as affecting conclusions that may be drawn from the material provided. FUEL AND NONFUEL TRADE Values of Fuel and Nonfuel Trade The value of world export trade in major mineral commodities (ores, concentrates and scrap, crude minerals, iron and steel, nonferrous metals, nonmetallic minerals and mineral fuels) in 1983, the latest year for which comprehensive data are available, was reported by the United Nations in May 1985 to have totaled over 514 billion current U.S. dollars (Table 1). This was 79% of the historic record high of nearly $649 billion ,current dollars set in 1980, but almost 18 times the current dollar value reported for 1960. [1/] The value of these 1983 exports in constant 1960 dollars was $164 billion (Table 2), only 66% of the record 1980 high of almost $250 billion, and only about 5.7 times the 1960 dollar level.

Jan 1, 1986

By T. J. Fenner

Surface and underground mining operations are often hindered by unknown tunnels and stopes and the precise locations of adjacent workings. Mine safety and planning are adversely affected especially in previously undermined areas where historical records are incomplete or non-existent. The results of several Ground Penetrating Radar (GPR) studies for the detection of known mine tunnels in underground coal; salt, and gold mines are presented. A case study to locate unknown, abandoned mine workings at a surface gold mine successfully located all workings to a depth of 11 meters.

Jan 1, 1992

By A. Mertzanis

The way and methods used for the surface mining of bauxite until the end of the twentieth century in the area of Ghiona, resulted in a significant burden to the natural environment, especially in the cases where it covered extended parts of forests and forest areas as well as important geomorphological formations. The impacts from the surface mining of bauxite which in fact constitute the object of this study relate mainly to the interruption of the natural continuity of the land relief and the alteration of the natural geomorphological activities and are due to: a) the alternating excavations with fronts of great heights, b) the depositions of large volumes of waste materials which originate from the revealing of the ore and c) the dense road network constructed in order to get access to the mine locations.

Jan 1, 2006

By D. Wright, J. Samborski

DuPont’s Florida Plant has been mining in northeast Florida and supplying titanium-bearing minerals, zircon and staurolite for over 50years.The site has successfully implemented and “sustained” a land reclamation/habitat enhancement program that goes beyond regulatory requirements and standard industry practices. However, the term sustainability has been used by so many organizations, many with divergent viewpoints, that it is important for a mine to develop its over-all concept and approach to sustainable operation. As a foundation, the outstanding reclamation efforts at DuPont’s mine will be presented followed by a broader look at the overall sustainability strategies and tactics used at the site.

Jan 1, 2004

By J. F. Power

Returning the original soil material to the surface of smoothed mine spoils is n practical means of restoring agricultural productivity. Research has established that high-sodium spoils in North Dakota (a) must be covered with about 70 cm of soil material to achieve maximum production; (b) topsoil must be segregated and spread separately from subsoil; (c) potential production depends on the quality of the soil material returned; and (d) erosion and upward salt movement must be controlled for sustained production. Erosion is best controlled by reducing final grades as much as possible during the smoothing process followed by prompt establishment of vegetation. Almost half the nation's cool reserves are in the Northern Great Plains underlying several million hectares of agricultural land. Social pressures to return mined land to agriculture or other productive uses have resulted in recent enactment of state and federal legislation, which is intended to restore productivity to disturbed areas. All such legislation relating to the Northern Great Plains has stipulated that useable soil material be saved and returned to mined land after spoils are smoothed. This requirement immediately raises questions as to how much soil material is needed, what criteria are important in defining useable soil material, how is the soil material to be handled in the earth-moving operations involved, and how can replaced soil material be maintained and revegetation. Scientists at the USDA Northern Great Plains Research Center at Mandan, North Dakota have conducted research on the reclamation of disturbed lands since 1970. Initially this research was designed to identify and characterize those physical and chemical properties of spoils that are most restrictive to plant growth (1). Basically, they found that any properties of spoils that reduced the efficiency of storage and utilization of the limited precipitation received adversely affected plant growth. Thus, in the Northern Plains, revegetation of mined land was found to depend upon the management of factors affecting the availability of water to plants - the same as on unmined land. After the major problems in revegetation were identified, technologies were developed to circumvent the effects of the growth-limiting factors (2). Basically two approaches were identified by which plant growth-restricting properties of spoils could be corrected: (a) various amendments (gypsum, sulfur, Fertilizers, mulches, calcium chloride, etc.) could be applied to spoils to improve their ability to conserve precipitation and provide water for plant growth; or (b) undesirable spoils could be covered with suitable soil materials to reduce or alleviate adverse effects. The latter approach appeared to be more feasible in most instances And is the approach specified in current legislation. The remainder of this paper discusses research on the use of roil materials returned to spoils and summarizes the information obtained.

Jan 1, 1978

By D. E. Ranta, G. H. Giroux, A. W. Randall, D. A. Barr

Zinc-lead ores of the Pine Point District, Northwest Territories, Canada, are hosted in paleokarst cavities within a Middle Devonian carbonate barrier complex. Of the nearly 100 deposits found, most are irregularly distributed along two main regional stratigraphically controlled trends. The ores, which occur predominantly as open space filling, form deposits most of which average one million tonnes in size with an average grade of 10% combined zinc plus lead. Geological features related to karsting control not only distribution of deposits but also their shape, size and grade. The higher grade ore in these deposits generally occurs in a relatively small core area. Consequently, accuracy of reserve estimation is dependent on drill-hole density and understanding of karst geometry. Several case examples will be reviewed to demonstrate the relationship between shape, size and grade of deposit, geological reserves and drill-hole density, along with a discussion of geological ore reserve estimation methods.

Jan 1, 1992

By S. C. Westerfeld

The original patent for the gyratory crusher was granted to Philetus W. Gates in 1881. This first crusher was used by the Buffalo Cement Co. At the time these early gyratory crushers were developed all mining and quarrying, either underground or open pit, was done by hand; tonnages generally were small and product specifications simple and liberal. Likewise plants were small and demands for small product sizes practically nonexistent. In addition to substantial amounts of hand labor, the available material handling equipment was small, simple, and not suited to handling large run of mine ore. Mine can, cable ways, or belt conveyon transporting crushed material to the mill had limited capacity per hour. At the turn of the century the largest Gates crusher, the No. 9, had a receiving opening of 21 x 48 in. with a three-arm spider and a 21 x 80-in. opening with a two-arm spider. The steam shovel began to change the entire picture of open pit quarrying. As a result of the use of steam shovels around 1910 crushers with 48-in. receiving openings were built; thus it can be seen that the basic gyratory crusher was developed prior to World War I. The improvement of the internal combustion engine and the use of pneumatic tires created a new set of operating conditions. Early mines were small, using shrinkage stoping and small mine can. The capacity of material handling was small, limiting the size of the largest piece and the feed rate. Improved material handling resulted in more and more large open pit mines with large shovels and a tremendous increase in the size of off road or mine haul trucks or rail can. Primary gyratory crushers also increased with receiving openings as large as 60 in. and connected hp of 1,000.

Jan 1, 1985

By O. J. Tassicker

The Electric Power Research Institute (EPRI) initiated a program in 1976 to develop and demonstrate an instrument system for on-line continuous measurement of coal properties. The program has focused on the use of Prompt Neutron Activation Analysis (PNAA) for elemental determinations and microwave absorption for moisture determination. One of the major results of the EPRI program is the development of the CONAC (Continuous On-Line Analysis of Coal) instrument, with Science Applications, Inc. (SAI) as the prime contractor and Kennedy Van Saun Corporation as a subcontractor.

Jan 1, 1983

The leaching of gold and silver by ammonium thiosulfate solutions in the presence of copper has been actively studied in recent years. Newmont Gold Company has successfully tested the ammonium thiosulfate for gold extraction following biooxidation pretreatment of low grade refractory carbonaceous/sulfidic ores. In this paper, the chemistry of the copper catalyzed leaching process is reviewed. Factors affecting both the leaching reactions and the stability of the lixiviants are reviewed and discussed from a solution chemistry perspective.

Jan 1, 1996

By V. Rastogi

Acid rock drainage is the result of exposure of sulfidic materials, such as pyrites and sulfidic ores, to air and water. The oxidation of these sulfides is catalyzed by more than a million times by the bacteria Thiobacillus jerrooxidans and close families. Inhibition of these bacteria can mitigate 98% or more of the acid loading generated. This can be achieved by the use of certain surfactants that are selectively bactericidal to the lithotropic acidophilic bacteria. Bactericides are used in two ways. As periodic or continuous treatments for prevention of acidification of material actively handled and moved, and in controlled release form for reclamation where treatment sets up a change in site microbiology to replace Thiobacillus jerrooxidans with heterotrophic bacteria and creates a stable site without need for further treatments. Use of bactericides begins with laboratory testing of the site material to qualify the site for bactericide treatment and dosage determination. Site specific treatments are designed for active sites and reclamation. Once acid production is controlled, solubilization of metals is correspondingly reduced. Results and economics of use from active and reclamation sites are presented.

Jan 1, 1995

By F. G. Rinker

The world demand for metallized iron continues to increase, keeping pace with steelmaking requirements for lower cost hot metal. Virgin iron ore and in-plant oxide fines can be reduced to direct reduced iron (DRI) and hot briquetted iron (RBI). MR&E has developed an improved coal-based process for cost-effective production of either DRI or HBI. Starting with dry compaction, the process combines the latest technology for material preparation, rotary hearth furnace construction and environmental control. Coarse iron ore fines are blended with pulverized non-metallurgical coal to produce a highly metallized (>90%) product. This paper presents production and installation cost data based on operating and under-construction iron oxide reduction facilities.

Jan 1, 1999

By A. J. Lynch, M. J. Lees

Introduction The design of wet grinding circuits may vary considerably according to the duty which is to be performed. Grinding machines which are commonly used in these circuits are rod mills, ball mills, autoge¬nous mills, and pebble mills while size separation machines commonly used are vibrating and wedge-wire screens, hydrocyclones, and rake classifiers. In some circuits, such as those producing feed to cement kilns, all the ore entering the circuit is discharged in a single product stream. In others, such as those operating on magnetite-taconite ores, the feed entering the circuit leaves in two or more streams. Grinding circuits in flotation plants normally include sections in which either the concentrate or the tailings from the primary flotation circuit is reground and these additional sections should be regarded as an inte¬gral part of the grinding circuit. A typical circuit is shown in Fig. 18. Problems in achieving maximum efficiency may occur at three stages: 1) At the design stage when the optimum size reduction flow¬sheet must be selected with respect to the types, numbers, and sizes of processing units. 2) At the operating stage when the correct selection of values must be made for those variables which may be altered while the circuit is off-line but which are constant while the circuit is on-line, for instance the vortex finder diameter of the cyclones. 3) Under conditions of continuous operation when changes in the circuit feed or in the mechanical operation of the circuit may cause undesirable changes in the circuit product. The first two prob¬lems are concerned with optimization, that is, with making the best choice from many possibilities, and the last with control. Optimization Problems. The main purpose of a wet grinding circuit is to produce particles with a sizing distribution which will ensure optimum performance of the later chemical reaction or physical concentration circuits, because it is on the efficiency of these later circuits that the economics of the total mineral treatment process depend. The size distribution of the product from a grinding circuit may be affected by many variables, some concerned with the arrange¬ment and operation of the machines and some concerned with the ore characteristics, and it is important that these should be recognized in the design and operation of the circuit. For instance, in a simple ball mill-cyclone circuit the variables which affect the product size even for constant feed characteristics are shown in Fig. 19. In addition, the rate, size, hardness, and mineralogical composition of the feed will affect the performance of the circuit and the product size. When the circuit contains more than one mill, both the number of choices available and the complexity of the problem are increased consider¬ably. Consequently, one type of problem which is to be solved if an optimum product is to be obtained from an existing grinding circuit is that of circuit design, and this includes arrangement of processing units and selection of those operating conditions which cannot be altered when the circuit is operating, such as mill speed and cyclone inlet and outlet dimensions. The other major problem in optimization is encountered at the design stage when a choice must be made about the type, number, and size of processing units. For instance, for a typical high-capacity size reduction operation, should two circuits each containing one rod mill and two ball mills or three circuits each containing one rod mill and one ball mill be used? Alternatively, should ball mills only be used and if so, how many, what size, and what arrangement?

Jan 1, 1985

By Roger Bell

Most modern mines can profit from improvements in information handling. Recording systems in many cases were designed to satisfy certain necessary legal requirements, but not specifically to provide management information. As a consequence, the top managements of these properties work with cost data and production information that is dated, lacking in detail and clouded with supposition. It is the intent of this paper to describe an information system for a mine-plant complex in terms of the type of data, application areas and the existing equipment technology that may be applied to improve this situation. The economics of information processing and data handling will not be discussed in detail. This paper is based on the premise that information is something of value and that information processing like a manufacturing operation works for and is subject to management control. Information, the product, must be of quality, and the cost must be favorable in terms of its use.

Jan 1, 1965

By S. Mafi

The Broken Aro project is associated with a 1910 abandoned underground mine complex that has been discharging aeid mine drainage from entries, seeps and springs. The Ohio Department of Natural Resources(ODNR), R&F Coal Company (R&F) and American Electric Power (AEP) are involved with this unique project that will remine the abandoned underground complex and install a mine seal constructed of fixated flue gas desulfurization (FGD) material. The goal of the project is to eliminate or reduce the acid mine drainage that is discharging into the watershed. This paper discusses remining, installation of the FGD mine seal, government financed reclamation projects and future application to active and abandoned mining sites.

Jan 1, 1998

By Charles C. Mosher

An in-mine seismic technique for detecting faults has been tested in a Western U.S. coal mine. This technique has been used extensively in the U. K. to help guide longwall mining operations. Explosives detonated on the face of a seam generate sound waves which propagate into the seam. Reflections from faults are picked up by sensors on the same face. Computer processing is then used to determine the fault locations. A known fault was successfully located in this test. Modifications to the U. K. procedures were required for the relatively thicker roan and pillar mines common in the Western U. S.

Jan 1, 1983

An appropriate scale-up methodology is very useful for ball mill design and optimization of the grinding circuit. To date, the scale-up is based on the selection and breakage function method using lab mill data. However, a major drawback of that approach is that the charge motion in a lab mill is vastly different from that in a large industrial mill. Therefore, in the methodology proposed here, first the energy of individual collision in the mill is computed employing the discrete element method (DEM). Then the breakage of particles as a function of collision energy is studied in a separate experiment. Together, this information constitutes what is known as collision energy based population balance method. The appropriateness of this method is shown for 38-cm ball mill.

Jan 1, 1998