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By L. Whitby-Costescu

The Shebandowan mine and concentrator, with a capacity of 9072 t/week (10,000 st per week), was opened in 1972 after several years of environmental study and planning. The mine is located in a popular vacation cottage .area about 96 km (60 miles) west of Thunder Bay, Ontario. Undertaken before environmental assessment procedures had become an established requirement, Shebandowan is one of the first Canadian examples of effectively integrating environmental work into overall planning. Although it is an underground mine, many of the environmental considerations are common to open-pit operations, and hence, it provides a case history for the use of all mine planners. Computers can play a part in such studies by simulating the annual production of mine wastes, by on-line polling of environmental sensors and by processing sensor data. Early attention was focused on establishing base-line conditions in a two-year water quality monitoring program. Since production began, water quality monitoring has shown that mining has not caused any significant changes. However, mine drainage disposal arrangements had to be modified in the light of operating experience. There is no townsite associated with the mine, and workers commute from established municipalities. Harmonious relations have been achieved with local cottage residents after their initial fears were dispelled. Plans are ready to begin revegetating the tailings when a sufficient area of dry elevated tailings has been accumulated. Rehabilitation of the land disturbed during development was begun before start-up and was completed during initial operations.

Jan 1, 1979

Cost reduction programs can focus on total cost or unit cost, but unit cost is usually the principal objective. The production cost per unit is: [Unit cost = Total cost Production volume] Consequently, any activity that reduces the total cost or increases the production volume will reduce the unit cost. Production volume is increased by (1) maximizing the availability of the production equipment and (2) maximizing equipment performance during periods of operation. Most operations managers routinely focus on volume because the factors influencing volume are generally well understood and congruent with the managers' technical skills. In fact, production volume (as a percentage of maximum achievable capacity) is widely recognized as one of the most significant measures of operational performance.

Jan 1, 1999

By C. B. Daellenbach

The influence of reduction roasting and thermal shock on the grindability of a refractory low-grade Michigan iron ore was examined in bench scale tests. The quantitative effects of the various treatments were evaluated at three sieve levels: 48, 100, and 400 mesh, using ball mill grindability and work index parameters as response indicators. Data from the testing program were analyzed statistically as a means of isolating the effects of cooling rate, roasting temperature, and ore chemical condition. All three variables were found to have an important influence on the grindability of the treated ore; ore chemical condition and roasting temperature had the most pronounced effects.

Jan 1, 1970

By M. Hardy, K. Nielsen, M. Ramey

American Soda, LLP has commissioned the first solution mine for recovery of naturally formed sodium bicarbonate (nahcolite) from low-grade deposits using high-pressure, high-temperature injection fluid. This project, known as the Yankee Gulch Project, was commissioned33 years after discovery of the deposit and followed an intensive four-year feasibility study that included a full-scale pilot test. The nahcoliteis co-mingled with oil shale and is impermeable. Solution mining is achieved by a combination of thermo-mechanical cracking and dissolution. Elevated temperatures are required to initiate the thermally induced cracking and to enhance solubility of the nahcolite, which is highly temperature dependent. This paper will provide an overview of the development of the project from discovery, characterization, pilot testing, permitting and commissioning, with emphasis on the solution mining aspects.

Jan 1, 2003

By C. J. Bise

Virtual reality (VR) is a concept in which the human experience of perceiving and interacting with a computer-modeled environment is achieved through the use of sensors and effectors. It is an advanced form of computer graphics. The images are generated based on where the user looks and how the user moves. As personal-computer-based (PC) instruction gains acceptance as an innovative approach to providing safety training, VR can provide a multisensory, rather than merely a multimedia, mode of presentation. New technology continues to be introduced into the mining industry to meet the productivity needs of coal and noncoal producers. There is also an increased need for more innovative training of mine workers. New technology and equipment designs often affect the basic causes of accidents. For example, the development of cabs and canopies for underground coal-mine equipment has reduced the number of accidents related to roof falls and rib rolls. However, safety-training specialists then had to focus on the machines themselves, because the modifications had the potential for causing "pinch-point" accidents. In fact, although the overall physical demands on mine workers have diminished, there has been an escalation in the concerns about trauma from repetitive physical activity. Thus, health-and-safety training specialists have shifted their atten¬tion to the recognition, evaluation and control of workplace hazards (Hancock and Hill, 1995). Recognizing that the spatial relationships of a workplace convey more information about hazards when experienced rather than described, trainers agree that simulation is the method of choice. Unfortunately, until recently, simulation systems were either simple software programs that did not come close to portraying the real experience or were complex hardware systems (such as flight simulators) that did, but at a cost of millions of dollars (Fritz, 1991). However, researchers and training specialists are excited about an emerging approach to work-force education based on virtual reality. VR is also described as cyberspace, immersive simulation, artificial reality, telepresence, virtual environment or virtual world (Meyer and Dunn-Roberts, 1992; Peterson, 1992). It represents a group of concurrent advances in computer and interface technologies. They enable an individual to interact in a multisensory way with a computer-generated environment. To achieve this, a typical VR system incorporates a computer that contains the necessary databases for producing realistic images and audio; a head-mounted display (HMD) or screen for viewing the images; and a three-dimensional controller, joystick or data glove for interacting with the computer-generated environment. If virtual reality is to become an effective tool for the safety training of mine workers, its attributes will have to be measured against other forms of delivery. Accordingly, Carr (1992) listed the following areas in which VR should be considered the method of choice: ? When training mistakes would be costly. ? When the necessary environment cannot be experienced in the real world. ? To build interfaces that are sensible and can be manipulated. ? To make training situations really "real." ?To make perceptible the imperceptible.

Jan 1, 1997

By C. E. Jordan

Under its program of advancing minerals technology, the Federal Bureau of Mines has developed a laboratory apparatus for continuous separation of minerals according to their dielectric properties. The unit consists of a rotating wire grid drum electrode and a fixed curved wire screen electrode positioned 3 mm apart. By applying high voltage across the electrodes, which are immersed in a dielectric fluid medium, a high-gradient electric field is produced. The high-dielectric-constant minerals are attracted and conveyed through the separator by the rotating drum electrode, whereas the low-dielectric-constant minerals settle through the fixed electrode. In typical tests, a sample of Montana chromite ore containing 43 percent chromite was concentrated to 72 percent chromite with 90 percent recovery.

Jan 1, 1977

By A. G. Naguib

In essence, any magnetic separator operates on the basis of imparting a preferential magnetic force on particles of higher magnetic susceptibility which are to be separated from particles of lower magnetic susceptibility. A certain amount of directional deviation to the particles takes place thus allowing for collecting each category of particles separately. The forces in action on particles in a wet magnetic separator of the established designs can be analyzed in a simple manner as shown in Figure 1.

Jan 1, 1972

By Maria S. Adusmilli, Bhaskara A. Rao, Jorge G. C. Barros, Augusto F. Mendonca

Lateritic gold has been the object of study only for a very few years, though nuggets have been mentioned in earlier works even as early as 1984 by Hartt in Brazil. In Mato Grosso State, lateritisation is intense, as is common in all tropical forest areas of the world. Exploration has revealed the presence of recoverable "nugget gold" of variable sizes (30 - 200 gms) but frequently of good size (0 - 40 gms), especially near Cuiaba and Alta Floresta regions. In both of them the host system is a lateritised breccia indicative of a fault or shear zone breccia, though in different lithological domains. The Cuiaba occurrences are phyllitic and show a profile as follows, from top to bottom: 1) Compact ferralite crust. 2) Oolitic to pisolitic compact crust (+ some gold). 3) Mottled concretionary laterite crust. 4) Lateritised "eluvial material" (gold nuggets). 5) Mottled patchy to banded laterite. 6) Banded lateritised phyllite with lenticular to banded goethite. 7) Altered red goethitic phyllite, with quartz veins (+ fine gold). 8) Unaltered grey phyllite with quartz veins (Protore). The Alta Floresta-Juruena River occurrences are volcano-sedimentary and show a profile as follows: 1) Deep brown siltitic, argillaceous and arenaceous material with organic matter (+ gold). 2) Modular and concretionary laterite, compact and indurated, with arsenophyrite in quartz fragments (gold nuggets). 3) Band with silty-clayey matrix and arenaceous in nature. 4) Bedrock meta-arcosian arenite. 5) Volcano-sedimentary with rhyodacites and andesitic basalts, with intercalations of arkosic and greywacke nature. Breccias and quartz veins, and granites associated in different portions (Protore).

Jan 1, 1988

By T. Chandler, R. Buchan, J. H. Blowes, E. G. Haldeman

The regional geological setting and nature of the serpentinized ultramafic rocks are described. It is postulated that lateritization started in Miocene time. Repeated uplifts led to at least four physiographic cycles and to the development of a mature lateritic soil profile. Complete profiles are subdivided from top to bottom as follows: Zone A - chocolate-brown limonite; Zone B - ochre-brown limonite; Zone C - soft serpentine; Zone D - hard serpentine; Zone E - serpentinized peridotite; Zone F - ultramafic rock. Zones A and F rarely attain ore grade. Canga is conspicuously absent. Rocky ore of Zones D and E amounts to 40%, limonite ore of Zone B to 25% of total ore reserves. Nickeliferous serpentine is the major crystalline phase in Zone C. In this zone and deeper, crystalline quartz occurs, particularly in fracture zones where nickeliferous cryptocrystalline quartz is of ten accompanied by garnierite.

Jan 1, 1979

By Peter L. Siems

Humid tropical environments pose many problems for mineral exploration. The problems result from thick lateritic soils, dense vegetation, seasonally heavy rains, deep chemical weathering, few outcrops and thick saprolites. Although geochemical exploration should be potentially a useful technique in these environments, it appears from the scarcity of reports in the literature that insufficient attention has been paid to developing procedures that are specific to the needs of humid tropical areas. For this reason, the authors believe that this account of a geochemical study in a tropical coastal area on the edge of the Brazilian shield is of general interest and importance for potential geochemical exploration surveys in similar areas within the tropics. The objective of the geochemical study was to develop a practical technique of reconnaissance geochemical prospecting for copper deposits in Brazilian tropical coastal lowland areas. In order to achieve this objective, information concerning the secondary dispersion of copper in these areas was required. Consequently, an orientation survey was designed to provide this information. The present account contains details of the geochemical study and the information about the secondary dispersion of copper that was acquired during the course of the orientation survey. Location and Climate The field area is on the Atlantic coastal lowland of Brazil at latitude 13°S. It lies approximately 10 kilometers south of Maragojipe, a city of 15,000 inhabitants; this city is on the western side of the Bay de Todos os Santos about 45 airline kilo¬meters northwest of Salvador. (See Fig. 1) A good gravel road from Sao Felipe to Sao Roque do Paraguay crosses the southern part of the field area. The climate of the area is hot and moist, and is without prolonged dry periods. The mean annual rainfall is about 1600 mm (63 in.) and the greatest precipitation occurs during the winter months of May and June and the summer months of December

Jan 1, 1972

By John A. Organiscak

The Bureau of Mines evaluated a new dust control technique for longwall personnel required to work at the tailgate end of the face. This technique utilizes a water-powered scrubber to clean a portion of the face air, which is discharged behind a brattice partition at the working area. Laboratory simulation of this system in a wind tunnel resulted in average efficiencies greater than 70 pct with system efficiency directly related to scrubber quantity. Underground evaluations indicated a similar direct relationship between scrubber quantity and system efficiency. Gravimetric measurements of respirable dust made during these underground evaluations resulted in average protection efficiencies ranging from 30.7 to 42.5 pct with increasing scrubber air quantity.

Jan 1, 1983

By R. H. T. Garnett

Reserve estimation is a process that commences with sampling and culminates in the issuance of a reserve statement. The tin, gold and diamonds that occur as marine placers on the continental shelf are low grade with very erratic mineral distributions. Sampling, using a variety of special equipment, determines the extent and grade of the mineralization. The sample size is important, especially for diamonds. Together with the sampling density, it determines the accuracy of the grade estimate. Bulk sampling is a confirmatory process. The choice of mining equipment, either new or developed from onshore activities, dictates the unit costs, the cutoff grades and the selectivity of extraction. Thus, the size of the blocks that comprise the mining plan and the reserves are determined. A variety of estimation methods of different reliability are available, with the most sophisticated being kriging. Dilution and losses during mining must be taken into account in estimation, and a grade-volume curve should be constructed. Diamond deposit estimation also involves an extra variable, the dollar value of the stones. During and after mining, essential feedback on the accuracy of un estimation may be given by the RIE factor and by a mineral balance. Reserve estimates are required for several reasons and may be subject to public disclosure. The use of the correct definitions is, therefore, important.

Jan 1, 1999

By S. W. Swerson

25.1-THE PURCHASING FUNCTION The word "purchase" means "to obtain by paying money or its equivalent; to buy for a price." This definition is all too simple to properly describe the word "purchase." One should consider the basic objectives of purchasing-to procure the right material, of the right quality, in the right quantity, at the right time, from the right source at the right price. Here it should be noted that in purchasing it is recognized that the best quality or grade of materials may be the only grade to purchase for a specific job. However. there are other jobs where the medium, standard or poor grade of materials is the right quality, as the lesser grade will perform adequately. In some companies the purchasing department makes the decision as to the right quality, while in others this function is shared with other departments. Years ago in business the owners controlled the purchase of required materials and services by performing the task themselves. The owners obtained the type materials and services they needed and paid the price demanded. This function was performed along with all the other duties requisite to the owner of a business, namely, clerical, hiring and firing of personnel, financial management, etc. As companies grew in size, clerical duties were assigned to other personnel and the owner usually retained the purchasing authority. This same division exists today in many small companies. However, in the larger companies, the purchasing function has been assigned to a separate department. Importance of the Purchasing Function-The larger the company the greater the need for a separate department to perform the purchasing function. Today the purchasing agent for most larger progressive companies has policy-making authority. Therefore, it is reasonable for him to report to the president or vice president of his company. Studies of several hundred companies show the purchasing department head reporting to top management 87.5% of the time. This fact in itself is indicative of the importance of recognizing that effective purchasing requires a department staffed with specialists in the field of procurement with knowledge and experience sufficient to perform in today's complicated business atmosphere. In the manufacturing field it is a common axiom that usually half of the company's dollar expenditures are for materials. If a purchasing department functions properly and the right product or service is purchased and a savings accomplished, the contribution to the net profit of the company is much greater, as opposed to sale dollars, where only a small portion is carried forward to net profit. Thus, the importance of the purchasing department and the contribution it can make to the success of the company are obvious. 25.1.1-THE PURCHASING FUNCTION 1. Responsibilities of the Purchasing Function-The purchasing agent in performing his function is acting as an agent for the company and others in the company requiring materials and services. Accordingly, he is committing the company for materials and services subject to certain limitations which the board of directors may stipulate. In view of this, the purchasing agent,'^ position must of necessity he

Jan 1, 1973

By I. M. Konduri

Theoretical investigation and laboratory experimentation have shown a great potential for jet fan ventilation in mines. Jet fans, also called induction fans due to the induction effect of the fluid jet to ventilate headings, may have particular application in remote-controlled production operations. This paper summarizes ongoing research using a scaled laboratory model. The model uses water as a fluid medium and simulates a typical 25m long heading of 1.5mx6m cross-section. The effects of various nozzle positions and designs have been investigated by using still photography as a tool for flow visualization. It is also found that the use of jets in combination with line curtains has enhanced the overall ventilating effect in the model entry.

Jan 1, 1996

By R. W. Smith, J. Dubel, M. Misra

The bacterium Mycobacterium phlei is highly hydrophobic and negatively charged. It has specificity for selective adhesion to fine coal particles, mainly due to hydrophobic interaction. However, it does not attach to pyrite and ash forming minerals present in the coal matrix. Results have shown that this bacterium is an excellent flocculant for fine coal. Not only, are the coal particles visibly aggregated, but the optical micrograph has shown that the coal particles are held in the aggregate by adhesion and bacterial bridging. With Mycobacterium phlei, the flocculation characteristic of coal is markedly different from that usually observed with synthetic polymeric flocculants. In particular, the entwining characteristics of the long chain molecules of synthetic flocculants are absent in the case of Mycobacterium phlei. Since the hydrophobic interactions between the adhering particles are of greater importance in the formation of particle aggregation, the flocculation process is very selective.

Jan 1, 1994

By G. Ferrara

Hydrocyclones and other dynamic separators are normally fed with pulps of water and solid particles. The particles have different sizes, shapes and densities and, except in the special case of mono-characteristic particles, are segregated into size, shape and density. Segregation is magnified by the high values of centrifugal acceleration in the hydrocyclones. This paper develops the theory of the segregation, indicates the major variables involved and reports experimental data of segregation under different operating conditions for mixtures of magnetite and/or ferrosilicon and non-magnetic minerals.

Jan 1, 1995

By C. E. Tackett

The Greenwich Collieries Co. is a subsidiary of the Pennsylvania Mines Corporation, and a wholly owned subsidiary of the PP&L Co. which serves the northeastern portion of Pa. PP&L annually consumes about 11 million tons of coal per year and is the largest consumer of both bituminous and anthracite coal on the eastern seaboard. Development work for Greenwich started in 1969. The coarse coal plant was constructed in 1970, with the raw fines bypassed. This worked very well for our requirements at that time; however, the Greenwich mining plans were extensively changed, longwall mining units were installed and low coal was encountered, resulting in dirtier coal, a finer coal and an ever increasing ash in the shipped product. All this demanded a more efficient ash removal process for the fine coal fraction. In 1971, the Pennsylvania Department of Environmental Resources and the Federal Environmental Protection Agency were pushing for the now stringent sulphur emission limits at our power plants. The Greenwich Mine coal reserves contained large quantities of 3.5 to 4% sulphur along with some low sulphur reserves. It was, therefore, essential that any new plant have the capability of efficient sulphur removal to meet the Pennsylvania Department of Environmental Resources and the Federal Environmental Protection Agency required limits. To meet these limits our design would have to be capable of producing a product of 2.0% sulphur or less.

Jan 1, 1977

Copper cathode and Uranium Oxide production at WMC (Olympic Dam Corporation) Pty. Ltd. involves processing leach liquors through a copper solvent extraction plant followed by a uranium solvent extraction plant. This paper discusses the processing problems, metallurgical testwork and circuit changes made due to contamination of amine in the oxime circuit and vice versa.

Jan 1, 1996

By Merih Celasun

The literature in operations research centered on mineral exploration has been comparatively limited in view of the significant implications of mineral discoveries upon the national economies in general and mineral industries in particular. Much of what has been published is of somewhat unsure academic nature, indicating to a certain extent the scarcity of industrial applications. Mineral exploration activities present quite difficult operational and conceptual problems. The purpose of this paper is to discuss the principal characteristics of decision problems encountered in planning an exploration program, to indicate an optimization approach to a certain class of allocation problems, and to suggest directions for future research effort.

Jan 1, 1962

By J. M. Kaufman

Recent mining regulations have increased the need for detailed engineering and environmental information pertaining to the hydrogeologic environment in mining areas. The cost of obtaining such hydrogeologic information has also increased. After mineralization of potentially economic grade ore and tonnage has been identified, and after completing preliminary mining feasibility studies (suggesting that development is merited), a second exploration phase can incorporate a simple, cost-effective baseline hydrogeologic data reconnaissance program that is linited but useful. Using exploration drill holes only, this program can provide a direct indication of where ground water is encountered. Also, reasonable estimates can be made on the relative production of water from various water-bearing strata, a composite potentiometric surface map can be prepared, and the general chemistry of the ground water can be characterized.

Jan 1, 1984