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By H. H. Murray

Abstract. World reserves of bauxite are abundant. Domestic reserves are limited and as a consequence the United States must rely on foreign suppliers for over 90 percent of its bauxite. Nationalization of many bauxite mining operations, levying of higher taxes, increased production and transportation costs, and attempts to create a uniform market price combined to place the United States in a vulnerable position. Alumina from kaolin, alunite, anorthosite, and oil shale have-been-or are being evaluated. World bauxite reserves are increasing and attempts to establish a uniform price have failed; therefore, it may be many years before domestic non-bauxite sources of alumina can compete with imported foreign bauxite.

Jan 1, 1980

By A. Kalogeropoulos, T. Michalakopoulos

The DEM has been used in several studies to numerically simulate the response of rocks to the cutting action with drag tools. In this research, the aim is to realistically simulate the rock material and the cutting process by controlling the grain interlocking of the numerical assembly and streamlining the calibration process while focusing on the cutting force and the failure mechanism.

Apr 1, 2023

By F. Seymour

A dynamic programming algorithm is presented that takes a series of nested phases, a fixed mining rate schedule, a fixed plant production capacity schedule, and finds the mining and cutoff grade sequence that maximizes the Net Present Value. This tool allows the Mining Engineer to quickly look at project sensitivity to various production capacities, commodity prices, and costs. A description of the algorithm is given along with examples of how it has been used at Newmont.

Jan 1, 1995

By J. Stachurski

Flotation tests were carried out on 6 coal samples of different rank as well as their oxidized samples. A mixture of diesel oil and alcohols was used in these tests. Surface oxidation caused a distinct decrease of the flotation recovery with some improvement in the grade The reduction in the recovery increased with increasing the concentration of the oxidizing agent. The floatability of low rank coals was affected by oxidation to a higher degree than medium and high rank coals. The recovery size curves of oxidized samples mere similar in shape to that of non-oxidized coals.

Jan 1, 1990

By Thomas Jancic

Two of the open-pit, copper-molybdenum mining operations of Duval Corporation are located in the foothills of the Sierrita Mountains approximately 30 miles southwest of Tucson, Arizona. In March 1959, mining from a moderate sized porphyry deposit known as the "Esperanza orebody" was begun at a rate of 10,000 tons of ore per day. Some five years later, a sizeable group of mineral claims west of Esperanza became available to Duval. Earlier exploration and development drilling in this area by others indicated an orebody of greater size but lower tenor than that of Esperanza. A drilling program conducted by Duval not only verified the results of the prior drilling but in addition, revealed a continuation of the mineralization to the south and east. Thus was developed the Sierrita orebody. Open pit design delineated 414 million tons of ore containing an average copper content of 0.35 percent and a molybdenum content of 0.036 percent. In April 1966, the office of Emergency Planning authorized General Services Administration to undertake a program under the Defense Production Act to en¬courage additional domestic production of copper in the interest of national defense. Duval's Sierrita Project was brought to GSA's attention in May 1966 on November 28, 1967, an agreement providing for the development of the Sierrita Property was consummated with GSA. In March 1970, the first copper-molybdenum concentrates were produced in the 72,000 tons-per-day concentrator. Pre-production stripping exceeded the scheduled 105 million tons despite the comparatively short lead time available to equip the mine, build the mine plant facilities, and staff the technical, supervisory, and labor forces. Shortly before the first concentrates were produced, plans were being formulated for a program to increase processing capacity by approximately 15 percent, which entailed increasing overall mining capacity by approximately 50,000 tons per day. This program is scheduled for completion early in 1971.

Jan 1, 1971

By Paul H. Johnson

Chemical mining may be defined as the in-place extraction of metal values from ores located within the confines of a mine (that is, broken or fractured ore, stope fill, caved material, or ores in permeable zones) or ores located in dumps, prepared ore heaps, or tailing ponds. The term solution mining has, in general, been used to mean the in-place dissolution of water-soluble mineral salts with leach solutions. Chemical mining is presently in its embryonic stage. Basic research needs to be done to understand the influence of physical and chemical factors in chemical mining, and applied research needs to be done on both a small and a large scale to develop practical techniques of field practice. The areas of research include the following: (1) Leaching chemistry, the influence of physical, chemical, and biological factors in in-place leaching (2) Hydrodynamics of chemical mining systems (3) The development of new, as well as old, leaching agents for use under chemical mining leach conditions (4) The development of new means of contacting fine and coarse materials (with solutions) under static leach conditions (5) The development of new processes for generating and regenerating chemical mining leach solutions (6) The development of metal recovery processes

Jan 1, 1969

By K. Biswas

For the pillars, which have been standing long after mining, the stability depends much on the weathering action in the presence of mine moisture. From the field observations, it has been found that this weathering action becomes critical in terms of pillar stability if the coal seam contains partings or binders in it. The weathering action degrades both the partings and coal in terms of their load bearing capacity as the mine moisture penetrates into them. This paper investigates the effect of weathering action on coal and partings in the laboratory. In the field, the strength profile in the coal and the partings and the effect of time (in terms of the pillar age) on them have been studied by using borehole penetrometer. In this paper, an attempt has also been made to establish formulae for time dependent strength of coal and partings.

Jan 1, 1997

By D. Scott Barr

The Zarafshan/Newmont Joint Venture operates the Muruntau heap leach project, located in the Kyzylkum desert of central Uzbekistan. The mine produces more than 12.4 t/a (400,000 oz/year) of gold from low-grade oxide ore stockpiles adjacent to the Muruntau open pit. It is op¬erated by the Navoi Mining and Metallurgical Combine and is one of the largest gold resources known (Fig. 1). Since commissioning in 1995, total heap leach production has exceeded 21 t (675,000 oz). The joint venture uses four-stage crushing and screening to produce a final product for heap leaching, Merrill-Crowe processing and local refining.

Jan 1, 1998

By William P. Lorenz

Overlying the sulfide mineralization at Anamax Mining Company's Twin Buttes Mine is an oxidized zone up to one hundred meters in thickness. The principal copper minerals in this zone are chryso-colla, tenorite, cuprite, native copper and copper-manganese-iron wad. This ox¬idized zone also contains minor amounts of uranium ranging in concentration from 0.002 to 0.010 percent. Since pit development through 1980, some 38 million tonnes of oxide ore with copper contents greater than 0.6 percent have been brought to the surface. Copper in the oxide ore is extracted at Twin Buttes in, an agitated sulfuric acid leach plant followed by solvent extraction and electrowinning producing 90 tonnes per day of copper cathode. During leaching of the oxide ores small amounts of uranium are solubilized along with the copper values. This is not limited to Twin Buttes as most acidic copper bearing leach solutions throughout the southwestern United States contain small amounts of uranium.1

Jan 1, 1982

By Diogo Peixoto Cordova, Italo Gomes Gonçalves, Andre Cezar Zingano

The top-down extraction sequence in the sublevel open stope method relies on rib pillars to support excavations, making pillar and stope stability crucial for controlling dilution. This study introduces an integrated methodology using a genetic algorithm to optimize the layout of open stopes and rib pillars while considering both economic and geomechanical performance. The methodology incorporates user-defined parameters such as the minimum size of stopes and pillars, maximum accepted dilution and acceptable percentage of pillar failure. A profit function that attributes economic value to the geometric configurations, including geomechanical performance, is employed. The geomechanical performance, assessed using numerical models in FLAC3D, includes the average percentage of pillar failure and potential dilution. The study was tested on a mining panel from an underground gold mine using a top-down mining sequence. The optimization achieved an 8 percent increase in net profit compared to the traditional engineer’s design when 70 percent hangingwall support efficiency was assumed, and a threefold reduction in pillar failure percentage. When no hangingwall support was considered, the net profit increase reached 22 percent. These results demonstrate that the proposed methodology enables integrated optimization, balancing mining costs with geomechanical performance and reducing the need for secondary support compared to traditional methods

Nov 1, 2024

By Cleland N. Conwell

The term "tender tundra" is a myth---a well-developed myth, but contrary to the fact. Any area that supports herbivores must have a plant base to supply food, In Alaska, herds of caribou migrate and live north of the Arctic Circle. And, if there is enough growth in the moss and lichens and arctic grass to support a caribou herd, the "tender tundra" can heal after it has been disturbed by mining. Another myth is that Alaska is an ice box. Actually, many areas In the state---particularly the Interior---have a high agricultural potential. Nevertheless, the fact remains: whether it is reclaimed by advancing the productivity from forest to agriculture or is allowed to remain a wild-life habitat, Alaskan land will revegetate. Reseeding speeds reclamation, but left to nature, native species will reclaim the land whether it was disturbed by forest fires, roads, villages, or mining. In fact, it is impossible to find many of the old gold mining camps.

Jan 1, 1975

By Edwin B. Wilson

Over the past several years, state governments have been vigorously refurbishing old health department agencies and smoke control laws in anticipation of pending federal developments. Many states now possess a mature air pollution control administrative organization and a fairly sophisticated set of regulations on air pollution, This developing network of state control legislation and regulation is the machinery which will be called upon to implement federal standards, In order to prevent the wasted effort and resources which inevitably result from hasty action, industry should be in con- tact with local and state control agencies and be familiar with lines of communication to agency representatives. Thorough knowledge of applicable laws and regulations, both current and pending, is required. Moreover, federal law and future federal air pollution control plans, should be well known. Industrial air pollution control should be geared to a long range plan which utilizes existing technology while at the same the recognizing that today's technology will be improved upon with time, Regulation, too, can be expected to become more stringent. The implications of air pollution control in the Appalachian region of the United States will be felt most strongly by the coal industry of this area. Either directly or indirectly most regulations in these states have a significant bearing on coal mining, processing, utilization or waste disposal. The extent of coal-related activity in the Appalachian States of West Virginia, Pennsylvania, Maryland, Virginia, Kentucky, and Tennessee can be observed from the data provided in Table I. This data indicates that 86 percent of active bituminous coal mines and 69 percent of bituminous coal production were accounted for by these states. The purpose of this paper is to provide information on current and proposed legislation and regulations on air pollution in the Appalachian states, The information should prove valuable not only to the coal industry but also to industry in general as a means of evaluating both pollution control action that has been taken to date and the course of future control measures. Reference information in the forms of addresses of appropriate agencies and citations to specific state laws and regulations is provided. All information is current as of February, 1969.

Jan 1, 1969

By James H. Barks

Exploration for ore deposits in southeastern Missouri in the 1950's resulted in the important discovery of lead, zinc, copper and silver in 1955. Further discoveries in the area led to the naming of the Viburnum trend. It has sometimes been referred to as the "New Lead belt" to distinguish it from older lead-producing areas to the east. As presently developed, the "trend" is 35 miles long, running north and south about 50 miles west of the Lead belt. Galena (lead) is the principal ore mined, with lesser quantities of sphalerite (zinc), chalcopyrite (copper) and silver recovered as economic by-products. The ore body is as much as 140 feet thick and 1,200 feet wide, and is found in the Bonneterre Dolomite (Upper Cambrian) at depths ranging from 700 to 1,200 feet. Since its discovery many companies have engaged in exploration and several major companies have developed new mines and constructed mills and a smelter in the area. The first mine in the Viburnum trend came on stream in 1960, but as more mines came on stream and others reached capacity, lead production increased to the point that the Southeast Missouri Lead district produced 432,576 tons of lead in 1970 to become the world's largest lead-producing region (Missouri Geological Survey and Water Resources, 1971). The Viburnum trend area with its rolling, heavily forested hills and numerous clear running streams is in the Clark National Forest of the Missouri Ozarks. Until the recent development of its mineral resources, the area was sparsely populated and nearly unmarked by the activities of man. Industrial development is almost certain to be accompanied by environmental changes. In a day of growing awareness of the need to preserve the quality of the

Jan 1, 1971

By A. D. Rovig

Metallurgical evaluation of autogenous grinding of Anaconda's Berkeley Pit ores indicated that tonnage throughput increases, at a finer flotation feed size, were possible by converting autogenaus mills to steel ball mills. In addition, initial test work showed that the improved grind resulted in slight recovery gains in subsequent flotation processing.

Jan 1, 1974

Machine breakdowns and maintenance delays are large contributors to lost production and increased operating costs in the mining industry. The U.S. Bureau of Mines is investigating the applications of expert system technology to diagnostic and predictive maintenance tor mining equipment. This will help increase mining productivity and decrease operating costs, by reducing the frequency of equipment failures and repair times. The Bureau has begun this effort by applying expert system techniques to the diagnosis of hydraulic system problems on a continuous mining machine. This paper discusses the development of the hydraulic diagnostic expert system.

Jan 1, 1990

By A. Rai

"This paper provides an overview of the current use of auxiliary ventilation product and the challenges with limited air quantity in dead-end entry or working face. The PVC low frictional factor, low physical constraint and minimum leakage ventilation duct was development with ""made in US and used in US"". The PVC duct development covering operational and total cost of ownership with on-going success will be presented. This paper will discuss mine sites using new PVC vent duct underground and the results from operational and technical side making a difference. INTRODUCTION The Turquoise Ridge Joint Venture (TRJV) is located in northern central Nevada, and is situated within the Basin and Range province, near the northeast end of the Osgood Mountains (see Figure 1). The TRJV mine consists of typical Carlin type- gold mineralization characterized by low strength rock of altered limestone’s, siltstones, and mudstones. The weak nature of the ground facilitates the underhand cut and fill mining methods [3].Mining Method; Underhand cut and fill : The mine uses underhand cut and fill method which has 12’x12’ top cuts and several different size undercuts. The ore body is accessed off of a secondary development heading, utilizing a heading with a cross section of 14W x 14H or 15W x 16H configuration. In the wider and more massive zones, two headings in a production panel may be worked at any one time. Drift round lengths are determined by the type of drilling machine being used. An example of a typical topcut and associated undercut layout is shown in Figure 2. SECONDARY / AUXILIARY VENTILATION IN UNUNDERGROUND METAL MINES The auxiliary ventilation system provides the required air volumes at the face of dead-end developments and production workings, which in many cases may be considered as the primary method of assuring that the air quantity and quality standards in these working areas are satisfied. The Auxiliary fans and ducting systems are usually the primary means of delivering the required air volumes to the face of dead-end developments and production workings. Both centrifugal and axial-flow fans are used in underground auxiliary ventilation systems, usually electric powered. The internally direct driven axial-flow fans tend to be more popular because of their compactness and adaptability to staging. The most commonly used materials for ridged tubing are coated steel, alloyed steel, fiberglass and resin. Flexible (collapsible) ventilation tubing is also used and is usually made from neoprene-coated or nylon material. To add stiffness and reduce collapsibility these fabric ducts can be formed over a steel spring frame. A very important factor in the design of an auxiliary ventilation system is to minimize leakage and reduce the frictional pressure losses along the auxiliary ducting systems by minimizing their friction factors (K)."

Jan 1, 2015

By J. A. Herbst

Ball mill grinding circuits can be subject to upsets that arise from variable characteristics of the feed ore. These upsets are transients in critical circuit variables such as ball mill mass holdup, circulating load, sump level, cyclone efficiency and product particle size. They may occur frequently so that the operation is continuously fluctuating or they may be of such magnitude that some of the equipment is overloaded, resulting in shutdown, or an undesirable product particle size. The feed ore characteristics that influence ball mill circuit behavior in this manner include the grindability of the ore, the eventual transport characteristics of the ore in the mills and the feed ore size distribution. Control strategies for grinding circuits using conventional proportional-integral (PI) control have limitations to their effectiveness in controlling against feed ore disturbances. The first of these are the interactive nature of two or more control loops on a single circuit. Under some circumstances they begin to fight each other, increasing control error and settling time. PI control loop gain constants can be tuned to give best response for some set of conditions but once these change, as they would with a change in the feed ore, they are no longer the "best" ones (Shinsky, 1967). Due to these limitations, alternatives to conventional PI control strategies have been investigated for grinding as well as other mineral processing operations. These alternatives, all computer-based, include self tuning regulators, decoupling control and optimal control (Herbst and Bascur, 1983).

Jan 1, 1984

By T. A. de Almeida, M. de Paiva Bueno, M. Powell

The mining industry is one of the foundations of modern society, providing not only the raw materials needed to maintain a contemporary lifestyle, but also serving as a basis for the development of future technologies. From the most basic components of an appliance to the materials needed to design an electric car or a space rocket, each raw material has gone through a painstaking procedure of extraction and processing, and ways to make this process more efficient will be of great help to meet an ever-increasing demand for minerals. One of the biggest challenges when extracting mineral resources is to measure the variability of the mineral body prior to processing. Comminution is the most power-demanding stage, and the lack of geometallurgical testing, often for financial reasons, may result in an inefficient operation. The Geopyörä Rock Breakage test was developed with the objective of making mineral variability data more accessible by providing both standard comminution parameters and rock mechanical properties at low cost, and with a modest sample size, allowing a larger number of samples to be tested to reduce uncertainties and assure productivity. The objective of this paper is to present the results of an extensive validation of this new rock breakage method against two of the main tests currently in use, namely the SMC® and Bond ball mill work index tests. More than 100 samples have been tested and the results compared, showing that the new method can accurately estimate the parameters of the traditional tests. This confirms that the new test is a reliable tool for comminution and geometallurgical tests.

Feb 1, 2023

By William J. Wiehagen

The training of mining personnel is a large and continuing activity for the mineral industries. Although safety and skills training has long been recognized as an essential element for reducing injuries and improving productivity, the research literature lacks definitive reports documenting the specific value of such training. The training literature presents a variety of testimonials as to the "benefits of training," but lacks data that specifically tie that training to the performance of the worker.

Jan 1, 1983

By Enrico Pavese, Tim Kearney, Stefan Lemke

Watertightness is of central importance in hydraulic and underground structures but has always been associated with a risk, as demonstrated by the very high impact that water inflows have on the damage of linings and infrastructure (Howard, 1991; Sandrone and Labiouse, 2011). Concrete is vulnerable to groundwater and chemical contaminants in the soil. These can leach into the pores and cracks of the concrete and degrade its integrity, causing spalling and corroding the reinforcing steel. Moisture migrating into the building can also degrade structural elements over time and lead to mold and other hazards to occupants’ health. In this connection, the demands placed on the setup and detailed design of the seal depending on the negative influence by water on the one hand and on the other hand on the function of a construction in view to its watertightness classification. Thus, the reliable functioning of a seal is of particular significance in the case of traffic tunnels, which are not easily accessible for all subsequent repairs after the construction in seepage water and especially when located in a pressure water zone (risk–cost assessment). Requirements for the long-term efficiency and quality of underground structures have increased in recent decades. Today, the standard lifetime requirement for an underground infrastructure project is 100 to 120 years and, in some cases, even higher. This calls for high increased attention to the durability of the whole structure and of each individual element. Standards, which started as application guidelines given by the manufacturers, are available in the market since the 1980s and are constantly adapted to the current developments in various technical committees. Differentiations are made between: Manufactures application guidelines, case studies or published articles Test standards for the laboratory to guideline the testing procedures (air temperature, type of test equipment, dimensions, test speed, test duration, concentration, type of liquids, monitoring, tolerances, interpretation of results, documentation, etc.), developed by committees based on material and laboratory experts Application standards, which include test standards but also the related minimum performance requirements (values) for material, processing, and quality assurance (practical tolerances), developed by committees based on a wide range of experts (e.g., designers, construction companies, applicators, manufactures, owners, test institutes, quality engineers) and therefore also based on a wide field of experience, different views and up-dated case studies. In the following there are some examples of guidelines and published information’s, ranked according to the year of issue, which are relevant for the development of waterproofing specifications in the tunnel industry:

Jun 13, 2023