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By Heinz Distelmeier

The New Austrian Tunneling Method was, as is well known, developed from conventional rock tunnelling. In Germany about 10 years ago the NATM began to be applied to partially stable soils by incorporated excavation and support methods to allow its use with these soils. The advantages of this tunnelling technique - adaptability, ecomomy, and quality have resulted in its widespread usage. Today, about 85 % of all mined tunnels in Germany are produced with this technology. This rapid development has resulted in about 40 companies operating within a geographical area about the same size as the state of Illinois that are capable of utilizing the NATM. In most cases German contract/award procedures allow the contractor to develop alternate design and plans. As a result of this flexibility and intense competition, safety factors have been gradually reduced to the lower limit of what could be regarded as demonstrably safe, and the utilization of the NATM has expanded to include higher risk conditions, namely * excavating larger cross sections. * working with less overburden. * work undertaken under less stable soil conditions.

Jan 1, 1983

By G. T. Adel

During the past decade, researchers at Virginia Polytechnic Institute and State University have worked to develop a novel flotation process for treating very fine particles. This process, which is now commonly known as [microbubble column flotation] (MCF), has been shown to be very effective in a number of applications related to fine coal processing. These applications include the retrofit of existing preparation plant circuits and the recovery of additional coal fines from refuse streams. In addition, work conducted under the sponsorship of the United States Department of Energy indicates that the MCF process is capable of producing superclean and ultraclean coals from many eastern U.S. coals. This paper describes some of the basic problems associated with fine particle flotation and the design and operational features of the MCF process used to minimize these problems. Also presented are the results of ongoing pilot- and field-testing programs.

Jan 1, 1989

By Ji Changsheng

In a large surface mine design, different kinds of mining equipment can be selected. Even though the major purpose of capital investment is to get more profit from mining activities, there are some other complicated factors which influence the selection of mining equipment must be considered as well. A fuzzy evaluation model with fuzzy set theory is proposed in the paper to make a good selection of mining equipment in which different kinds of factors including quantitative and nonquantitative ones can be taken into account at the same time. With the model, mining equipment selection of a large surface mine can take into consideration not only economic factors but also some other factors which play important role in mining system.

Jan 1, 1996

By K. N. Han, X. Xie

The dissolution behavior of palladium powder in thiourea solutions was investigated. The variables studied were temperature, stirring speed and the concentrations of thiourea, acid and ferric ion. Palladium was found to be soluble in thiourea solutions in the presence of an oxidant such as ferric ion. The dissolution of palladium in thiourea solutions was believed to be chemical-reaction controlled, with an apparent activation energy of about 25.3 kJ/mol.

Jan 1, 1997

By Robert L. Bates

United States production of the industrial minerals, ahead of that of the metals since 1946, has shown a steady and rapid growth. By 1963, their value was more than twice that of the metals. Yet papers on the metallic ores continue to dominate the meetings of the Society of Economic Geologists and constitute nearly nine-tenths of the lead papers in Economic Geology. Most of the geological communication that does take place concerning the industrial minerals deals with high-value special-purpose minerals, which are comparable to the metallic ores in geologic complexity. The large-bulk rock products, which are growing fastest in production value, are characterized by relatively simple geology and by thousands of small producing firms, many of which do little or no geological work. The need for geological advice by this very large segment of the industry is bound to increase. In the meantime, a plea is made for more geological communication among those concerned with the industrial minerals of all varieties.

Jan 1, 1966

By Sigmund J. Sulinski

All Sanitary District contract documents for new tunnel construction permit the Contractor a choice of four (4) separate alternate tunnel sections. This is the result of a continuing District policy to encourage at all times the use of the most suitable construction techniques and to attract to District construction the broadest spectrum of proven capabilities. Figure 1 indicates the alternate tunnel sections allowed on District contracts as follows: 1. A horse shoe section, ribbed and lagged, and a poured reinforced concrete tunnel liner; 2. Circular section, ribbed and lagged, and a poured in place reinforced concrete tunnel liner; 3. Circular section, ribbed and lagged, and a precast reinforced concrete pipe liner grouted in place; and 4. Circular section, no temporary lining, and a precast reinforced concrete pipe liner to be jacked in place. The Sanitary District now has in operation 10,500' of 5'6" I.D. and 6,500' of 5'0" I.D. jacked tunnel. An additional 5,600' of 7'6" I.D. jacked tunnel is currently under construction.

Jan 1, 1997

By Alfredo Dammert

The paper presents the results of a model built at the World Bank in order to analyze the aluminum industry. Bauxite demand for the year 2000 is estimated as a function of alumina refineries' requirements and of non-metal uses for bauxite. Bauxite supply by countries or regions depends on economic factors such as investment costs, operating and transportation costs, as well as on tariffs and levies. Various scenarios are considered as a result of varying the assumptions of the model.

Jan 1, 1984

By P. Tanaskovic

This is presentation of a model which simplifies application of project management in control of the construction procedure of industrial units (mines, power stations etc). The model is made for further referrence of investors. The most demanding problem in large units is to find the best way of locating all activities within a network. The model uses term "line" (which refers to a construction unit) for a serie of activities which are to be sequentially executed (up to 1000 lines, each with 10-20 activities). The lines are coded in advance. Each line is described by a competent expert. Team of experts provide liason between lines on the basis of computer drawings. The method proved to be extremely effective. In order to provide smooth monitoring at all management levels, graphic documentation is given at 4 levels. The initial level is the third one, made based on input data (more than lo listings per one drawing). By condensation of activities along one line, another level is obtainable. Grouping of lines gives the first level (1-2 listing) for the highest management level. More detailed information is given for a limited (shorter) period at the forth level for the purposes of operational management. Each activity has three phases: prior to contracting, post contracting and accomplishment. All phases are presented at all levels, which enables investor to be continually well informed about construction advancement. Model is written in FORTRAN language. Programs comprise: maintenance of data base, calculation of time and costs and elaboration of graphic and other documentation.

Jan 1, 1986

By J. E. Garlanger, R. K. Shrestha

During mining, the surficial aquifer and, in some cases, the top of the uppermost confining unit within the mined areas are excavated. Portions are removed from the area for resource recovery. Until the mined areas are reclaimed, the surrounding unmined area continues to dewater. The impact of mining and subsequent restoration of the surficial aquifer on the ground and surface water resources of the watershed affected by the mining will be described. This will be done in terms of ground water recharge, ground water levels, and base flow and runoff to surface streams. Data from actual mining situations will be used in analyses and discussion. Recommendations will be made for further research.

Jan 1, 1992

By Bela Koman

Abstract - A shiploading terminal near Punta Arenas, the southernmost city of the world (lat. 53°-10'S, long. 70°-54' W) is described. Strong winds, choppy seas, frequent gales, rain, and snow make it difficult to load ships at an offshore berth in this area. Detailed site investigations, including a wind-recording program, supplied sufficient information for the analysis of operating conditions. The weather pattern of the entire region, including the predictability of gales, was utilized in the analysis. The results showed that a bulk loading terminal at this location is feasible, provided that the design takes into consideration the specific problems of the site. The final layout shows a terminal that can be approached from several different directions, depending on the direction of the wind. The mooring system is arranged to allow alter- native ways of attaching and casting off mooring lines and executing docking and departing maneuvers. The berth is supported on piles and contains the minimum of structures, relying on a slewing shiploader to reach the ship in any position, with only limited fore and aft shifting of the vessel for loading the extreme hatches. Results of wind recording, statistical analysis of wind and wave data, operating criteria, and the results of berth availability analysis are included in the paper.

Jan 1, 1987

By R. D. Shackleton

Medusa Cement Company, a division of Medusa Corporation, is a medium-sized cement manufacturer serving the midwest, east, and southeast. Medusa's eight plants are located in Georgia, Pennsylvania, Ohio, Illinois, Michigan, Wisconsin, and Canada. Of these, six have active limestone, shale, clay, and sand quarries now in operation. This paper deals with the various individual state laws regulating mining and reclamation at the Georgia, Illinois, and Pennsylvania quarries. Several recommendations for future state mining laws are discussed also.

Jan 1, 1974

A form of column flotation cell is described in which the contact between the feed and the air stream is made in a mixing device at the top of a vertical downcomer. The air-liquid mixture flows downward to discharge into a shallow pool of pulp in the bottom of a short cylindrical column. The bubbles disengage and rise to the top of the column to overflow into a concentrate launder, while the tails are discharged from the bottom of the vessel. The main advantages of the device described are that the overall height of the column is reduced to about 1 m (3 ft), and the column can be self-inducing with respect to the air supply. Experimental results are given from tests on a feed stream to a conventional zinc cleaner circuit. Using wash water to reduce gangue entrainment, the column gave high concentrate grades and high recoveries.

Jan 1, 1987

By L. A. Hansen, D. L. Buffington, G. H. Beckwith

This paper reviews geotechnical engineering considerations in heap leach pad design, discusses design philosophy and provides design procedures. A brief discussion of surface water hydrology ground- water protection and other design considerations are also presented. Special emphasis is placed on projects in the arid and semiarid regions of the Western United States where annual evaporation exceeds rainfall, and where good foundation conditions are usually present.

Jan 1, 1987

By James L. Hendrix, David Castillo

Cyanidation is one of the most common practices used in the extraction of gold and silver. One method of application is heap or dump leaching which entails the leaching of the gold or silver ore by spraying or dripping a cyanide lixiviant over the ore and collecting the effluent. The ore is placed on what is known as a leach pad system. A typical leach pad system consists of a foundation, a leakaqe detection system, a liner, and a cover layer (Strachan and van Zyl, 1988). There are many types of liners available for use. The type of liner depends upon what type leaching pad system us used. Generally, leaching pad systems can be categorized into two types: an expandable pad and a reusable pad. An expandable pad exposes the liner to the elements only in the initial stages of ore placement on the leach pad system. A reusable pad exposes the liner to the elements on a periodic basis. In addition to the exposure to the elements, the liner is also under the stress of the ore placed on it and the stress of the vehicular traffic across it. These stresses and exposure to the elements are the major causes of liner failures, which can appear as punctures, tears, cracks, and deterioration. Because of the possibility of the failure of the pads to contain cyanide-laden solutions the designs for liners of pads and ponds have become more and more stringent. Currently, though, there is some recognition that in some locales such stringent design criteria may not be required (Chatwin, 1989). Some soils have significant cyanide attenuation and degradation capacity. It has been found that soils containing carbon- aceous materia1 wi11 remove cyanide from solutions percolating through them (Chatwin, 1989). Of course metallurgists have long recognized the deleterious effect of carbonaceous material in the mill circuit. Sheridan, et a1 (1988) have shown that WAD cyanide is detected in the effluent of a 2 m column filled with ground carbonaceous ore only after it had been continuously washed with greater than 9 pore volumes of NaCN solution. It was decided to examine the potential of successfully attenuating cyanide by placing an organic material layer between a 1iner and the prepared soil base. One consideration for the selection of the organic material was cost. Sawmill wastes, ground agricultural wastes (such as corn cobs), and other organic wastes were considered. But the first waste to be tested was a product found at any metropolitan area, sewage sludge.

Jan 1, 1990

By Ronald J. Vance

One of the key elements of change in the mining industry has been the ever-increasing integration and coordination of previously highly segregated business disciplines, the extent to which the marketing and finance functions have evolved and merged within the mining industry. If one listens to the language of mine product marketers today, one hears terms like contango, backwardation, forwards, options, min/max, synthetics, swaptions, caps, collars, FRA's, spot deferreds, double bottom, head and shoulders. The list is endless and a glossary may be out-of-date even before the ink is dry. No longer can a marketer of mine products get through the day and, more importantly, keep his or her job merely by reciting statistics on supply, demand, prices and the jargon of quotational periods, delivery and payment terms. Walk into the office of any marketing department today, and computer terminals spewing on-line market prices and instantaneous news retrieval command the attention of all who enter. Traditionally, mining companies, particularly those in North America, took a passive view toward marketing their products and an even more passive view toward management of price risk. The typical, albeit simplified, gold producer of the 1970s and early 1980s spent all of its energy exploring, delineating, developing and producing a product that was placed by the mine gate. Like magic, anonymous buyers took it away and left piles of dollars in its place. No fuss, no muss and nothing to get in the way of more exploring, delineating, producing etc. The typical copper producer, meanwhile, was slightly more creative. Copper producers still spent most of their energy exploring, producing etc., but they at least acknowledged the identity of their customers. Many even went so far as to fabricate finished mine products into shapes and sizes that their ultimate customer needed. Wire, cable, sheet and extrusions were all in forms ready to be purchased by power companies, motor manufacturers and telephone companies. But, while production and costs steadily increased, research and development into new expanding markets was funded by little more than lip service. Competitors and competitive products steadily eroded market share and realized prices. The now-famous Business Week magazine cover that proclaimed "The Death of Mining" was an imminent reality.

Jan 1, 1993

By Steven McCutcheon

As most of us have learned through prior and often frustrating experience, anyone proposing to construct a new or expanded mining-ore processing facility must first contend with a rather complex array of environmental laws and permitting regulations administered by a number of different Federal, State and local agencies. At our lost count, there were about 55 federal enactments affecting base and precious metals projects. Applicable State and local laws will usually increase that number significantly. The time and costs associated with complying with all these various regulatory programs usually constitutes one of the major areas of uncertainty in the development of a proposed project. There are many in the mining industry who firmly believe that these environmental regulation and permit programs necessarily causes significant delays and increased costs in the development of a project. This belief, unfortunately, is probably a result of a basic misunderstanding of how the environmental permitting and regulatory system actually works.

Jan 1, 1984

By W. W. Koczkodaj, J. Partyka

Beat exchange in an open air-water system is considered. The system incorporates a vertical cooling tower, and a horizontal multi-stage spray chamber with unlimited number of stages. Mixing of two streams of both water and air is permitted. A spread-sheet implementation estimates temperatures of outgoing water and air for given mass flow of water and air, factor of merit for heat exchangers, barometric pressure, wet- and dry-bulb temperatures, and the temperature of incoming water.

Jan 1, 1987

By A. M. Al Taweel, S. M. El Mofty, T. A. Hassan, M. R. Moharam, A. M. Ramadan

The axial mixing characteristics of a pilot-scale flotation column were investigated with the objective of identifying means to mitigate the extent of axial mixing that adversely affects its grade/recovery performance. A wide range of design and operating conditions was investigated and the experimental results, obtained using the dynamic response method, were analyzed using three axial mixing models. The dynamic response of the column can best be described using the axial dispersion model. The results obtained suggest that the value of the axial dispersion coefficient, EL. can be signi6cantly reduced by judicial selection of hydrodynamic conditions and/or the use of column inserts that suppress the onset of hydrodynamic instabilities inherent to the operation of conventional flotation columns. Up to 40% reduction in the value of EL was thus obtained by using spargers that produce more uniform bubble sizes, while up to 30% reductions were obtained by controlling the residual frother concentration.

Jan 1, 1995

By J. Libaude

The Changement mine in French Guyana has, since 1983, processed gold ore by classical gravity methods. A large part of the gold is in the form of very small, free or enclosed grains. Recovery by gravity methods is thus limited (25-30%) and the present plant produces about 40,000 t annually of auriferous waste assaying about 6 git. The company therefore decided to retreat the waste by heap cyanidation. After laboratory tests which showed the feasibility of the method, a pilot test was set up on site. An experimental 3000 t heap, composed of waste of 0-8 mm grain size, was laid out by bucket loader on an impermeable pad covered by PVC and geotextile cloth. The upper layer of the heap was reworked by mechanical shovel to break up the area that had been compacted by the passage of the loader so as to restore adequate permeability.

Jan 1, 1998

By W. H. Strickland

The research reported here characterizes ultrasonic ranging sensors for autonomous navigation on underground mine mobile equipment. Because ultrasonic rangers are inexpensive, have no moving parts, have no lenses to clean, are small and unobtrusive, and can measure distances in dusty environments, they are especially sui ted to underground mi ne environments. The investigation began with laboratory tests of field of view, angle of incidence, intersensor variation, and ranging accuracy of individual rangers and a ring array of 24 sensors. The results showed the sensors have good accuracy and low variability. Additional experiments at AHAX' s Henderson mine Showed the sensors could accurately and reliably measure rib features, convex and concave corners, and drift intersections. The results showed that when used and analyzed properly, the sensor data may be used reliably for underground mobile equipment navigation.

Jan 1, 1990