Search Documents

By Peter H. Grimley

It is important to realize that lending institutions have a very different risk-profile from that of an equity investor. For bank financing, a feasibility study must address the concerns of the lender and these can be summarized under the four 'PI Is: Project, Performance, Product and People. Generally, feasibility studies focus on the measurable project risks associated with a new venture, but frequently insufficient emphasis is placed on key risk areas such as ore grade and metallurgical recovery. Before accepting full or even partial non-recourse risk, financial institutions will demand evidence that the project was constructed according to specifications and within budget and that its Performance within agreed limits has been demonstrated. Product risk should be discussed in detail in any feasibility study. For industrial minerals, penetration of the market can be critical to success and for commodities with volatile prices, the sensitivity of the cash flow to a range of prices should be carried out. Methods of reducing price risk such as long term contracts or, in the case of gold, forward selling should be carefully evaluated. The People risk is rarely discussed in feasibility studies, but can be a key element. Few projects turn out to be faithful copies of the study and the ability of the operator to identify

Jan 1, 1988

By J. Drelich, J. D. Miller

The wetting behavior of liquid polymers at solid surfaces and the adhesion forces involved at polymer-filler interfaces should always be considered in the preparation of high-quality polymer composites, including those made with mineral fillers. Spontaneous polymer spreading over the filler surface is a basic condition for the design of polymer-mineral composites. In this regard, the wetting and adhesion characteristics of polymer-mineral systems are reviewed. Based on this review it is clear that several aspects of wetting phenomena at mineral filler surfaces require further systematic study. Specifically, efforts should be made to determine the wetting characteristics of molten polymers at mineral-filler surfaces in greater detail. Also, the effects of mineral-surface contamination (including surface hydration) on wetting and adhesion phenomena need specific investigation. It is expected that an improved fundamental understanding of wetting and adhesion phenomena for polymer-mineral composites will provide the basis for further technological development.

Jan 1, 1996

By G. L. Dollinger, W. H. Hamilton

INTRODUCTION Design and development of new products generally proceeds through a phase of initial development and discovery based on the evolution of existing arts, followed by technical innovation and development based on both pure and applied research. The development of the mechanical tunnel boring machine (TBM) has followed a similar pattern, with the first machines closely resembling continuous coal miners. In general, however, the design of TBM's to date has been more a result of evolution and discovery than of new technical innovation, even though large sums of money have been spent on research and development. In particular, the results of experimental laboratory and field investigations have had little effect on tunnel boring machine design, and the better performance of TBM's today over those of 10 or 15 years ago, is due more to increased mechanical reliability and greater operating experience, than to improvements in penetration rates and rock fracture capability. The improvements made, have been mainly by the machine and cutter manufacturers who recognize the greater efficiency and economic advantage of utilizing large single row cutters with high load capacity along with large edge spacing. Are there any improvements to be made, therefore, in TBM performance without new and dramatic technological breakthroughs? Can TBM manufacturers design greater performance into their machines by a logical extension of the present art, and by applying what has been learned in the laboratory and field? Some, for example, believe that the kerf cutting system of boring rock is at, or close to, its opti¬mum and little improvement can be made in the present TBM concept.

Jan 1, 1979

By Numan Elmas

This paper presents detailed information on the genesis, formation, and industrial utilization of Yaylacik magnesites. Tectonically, the study area is located within the Tavsanli Zone, immediately south of the Izmir-Ankara suture in western Turkey. The geologic setting mainly comprises ophiolitic melangks basics, and ultrabasics associated with very rich magnesite deposits and lacustrine sediments. The ophiolitic unit tectonically overlies the schists and carbonate rocks. The presence of glaucophane and lawsonite indicates a low-temperature/high-pressure metamorphism. The ultra- basic rocks, which exhibit cumulate composition, have been mostly serpentinised and represent the oceanic floor of the Yaylacik ophiolite. Basic intrusives consist of dolerite and diabase, and they show the characteristics of within-plate dolerites. The magnesite occurrences are commonly observed in block, stockwork, lens, and vein forms and were deposited within the serpentinites. In most magnesite samples, secondary quartz/chalcedony formations are observed as fracture fillings due to the highly effective tectonic movements. Field surveys and microscope studies reveal that magnesites had been formed by the metasomatic alteration of serpentinites. Chemical analyses show that, although MgO content of the magnesites varies from 43.41% to 50.48%, Fe203 and CaO are lower than 1%. Silica contents are as high as 5.52% in a few samples. Although Yaylacik magnesites are not suitable for making basic refractory bricks, they are widely used as caustic-calcined magnesite in a variety of applications, including animal food, artificial fertilizer, chemical (acid neutralizer), medical and pharmaceutical, and water treatment.

Jan 1, 1999

By K. Biswas, S. J. Jung

Health and safety of workers in mineral industry in the U.S. is still a vey important issue as Mining along with Agriculture, Forestry and Fishing and Construction industries have contributed most of the fatal occupational injuries ill between 1980 - 1995 (Worker Health Chartbook, 2000). Health and safety issues, especially for the mining or related excavation industries, arise either from exposures of the human workers to the contaminants liberated or generated by mining operations that have adverse effects on human health (for example coal dust etc.) or from the exposures of the human workers to hazardous working environment that constitutes mining operations (for example blasting etc.). One of the biggest challenges is to understand the combinatorial effect of numerous work-condition (e.g. exposure to dust) and human-factor (e.g. smoking habit) variables on a health or safety-condition variable (e.g. incidence rate of a disease). This paper uses an example dataset on Coal miners' cough problem to illustrate the applicability of Generalized Linear Modeling (GLM) in understanding the relation between cough and other response variables, such as, age, height, smoking habits, time of underground exposure etc.

Jan 1, 2002

By Bruce D. Hulman, Robert .. F. Gorman

Introduction Groundwater resource evaluation has historically required extensive field investigative work, usually at great cost. More recently, the advent of the microcomputer has made difficult aquifer and groundwater evaluations comparatively simple and less expensive. A groundwater model is a numeric solution to a set of equations that calculates the water level in an aquifer or other types of water bearing strata. A computer will execute the solution of the set of equations rapidly and thereby permit evaluation of large amounts of hydrogeologic data rapidly. Computer modeling of groundwater resources is very often used to forecast the effects of multiple uses of a single groundwater resource. Modeling of heavily used aquifers has proven to be beneficial for averting problems arising from competitive use of a groundwater resource. This paper describes the work tasks performed in order to evaluate a large alluvial aquifer and thereby predict the hydrologic impact of additional groundwater withdrawal. Purpose and Scope Neyer, Tiseo & Hindo, Ltd. (NTH) was retained to evaluate the groundwater supply potential of the Missouri River alluvium underlying the Fairfax District in Kansas City, Kansas (Figure 1). The proposed groundwater supply is being considered for industrial use as non-contact process water and a heat exchange medium for plant climate control. The anticipated peak groundwater demand is estimated to exceed 30 million gallons per day (MGD) during the summer months, with an average daily demand of nearly 25 MGD. The proposed groundwater supply was to be developed from 15 large-diameter production wells located at positions that would minimize potential interference.

Jan 1, 1987

By S. P. Banerjee

Injection of inert gases to combat mine fires has been practiced in various parts of the world for a long time. Of late, nitrogen has become the preferred inert gas for control of mine fires and safe salvage of longwall equipment as compared to carbon dioxide or fuel gases produced from burning of fuel. In India, carbon dioxide has been used for fire fighting in a number of mines during the 1960s and 1970s. More recently inert gas produced from burning of fuel oil in surface plants has been used in controlling the atmosphere in fire areas in two mines. In yet other cases, liquid nitrogen has either been poured directly into fire areas in liquid form or injected in gaseous form to keep the fire in check. Nitrogen produced in liquid form in an oxygen plant is more costly than nitrogen produced from PSA (pressure swing adsorption) based plants. A PSA-based plant has been installed in one of the Indian mines in 1986 and more are in the offing. This paper reviews the application of various inert gases in Indian mines and discusses the likely trend of inert gas application in Indian mines in the future.

Jan 1, 1987

By Pentti Kallio

From the aspect of economic feasibility of mining, ineffective use of expensive mechanization investments is becoming a problem. In many cases, the machinery is in operation only 50 - 60 % of the total working time. The lost time when the machines are idle means a considerable over-investment in machines. The lost time, with LHD equipment in particular, accumulates from the following constituents: - the needs of the person operating the machine trips to the work site, lunch, coffee and other breaks, want for comfort, etc. - deficiencies in the monitoring and control systems for machine operation waiting periods at loading and unloading stations, unnecessary and erroneous actions, inefficient work, etc. - deficiencies in the machine condition monitoring system , and inefficient service and maintenance work The data transfer and computer technology of today provides means for resolving problems in several areas - including the area of underground loading operations. In the paper those areas of automation and data handling are considered which make possible an improvement in the usage and monitoring of LHD equipment. These fields are: remote control of equipment, use of TV cameras and monitors in remote control, locating equipment and data transfer down the mine, measurement of the load and the data storing system, systems for following the condition of the equipment, unmanned operation of equipment.

Jan 1, 1989

By M. J. Shulman

The exploration geologist is frequently confronted with the problem of allocating his resources, i.e., exploration effort, among various areas. Although geologic, financial, and logistic considerations influence the allocations, no objective criterion is usually given that determines the optimal allocation. Maximizing the expected gain in information, subject to the constraint of a limited exploration budget, is used as the objective criterion to allocate airborne reconnaissance effort. The information function, I(x), quantifies the expected gain in information, where x is the scale of exploration. To calculate the information function, the following probabilities are required: the probability that an area contains a deposit; the probability that an anomaly is produced by the target; and the probability that an anomaly is produced by a barren area (false signal). Alternatively, the barren areas can be replaced by other targets. To illustrate the allocation method, the optimal number of line kilometers, i.e., the optimal line spacing per area, is determined for an aeromagnetic survey for iron in Egypt.

Jan 1, 1987

By Changwoo Lee

Under drastically deteriorated situations, diesel equipment was introduced to some of local coal mines, aiming at higher productivity and better safety. To accommodate various diesel equipment in conventionally developed mines, mining system itself had to be modified; much larger trackless haulage ways were excavated. Possible health hazards of diesel not taken into account at the beginning become a serious concern and effective control measures are being searched for. The purpose of this paper is to study the diffusion characteristics of diesel exhaust in local coal mines. One of the parameters affecting dispersion of diesel contaminants is the coefficient of turbulent diffusion. Since CO2 is known to be closely correlated with other contaminants such as CO, NO, NQ, SO2 and RCD, it was chosen as a tracer gas in a series of dispersion experiments. A large diesel passage as well as a conventional track haulage way were the sites for the experiments. Rectangular dispersion pulses were generated for 30 ~60 seconds and CO2 concentrations were recorded at several locations 50~190 m downwind. The diffusion coefficients calculated graphically vary between 0.10~0.48 m2/s at both haulage ways. The results are analyzed to find any correlation with the air velocity and the distance from the disperser. Skobunov's empirical formula is applied to the experimental data for comparison and the relationship between Reynolds number and Ex/Dp/sci0.4 Sc1…

Jan 1, 1995

By Fred W. Stuart

Microprocessor technology has revolutionized the business community by placing tremendous computing power in the hands of the end-user for a very inexpensive price tag. The range of applications covers process control, to office automation, to personal computing capabilities. With the influx of this new technology, which these systems have to offer, also comes some unique operational and control considerations. But before we address these items, let us lay a foundation of common terms to be used throughout this presentation. Due to the rapid advances in microprocessor technology, where a new generation of computers is announced every two or three years, it becomes difficult to define a microprocessor system and have it valid for an extended period of time! Therefore, for this presentation, we will be dealing with a subset of microprocessors called Personal Computers or PC's. At the heart of a PC is a Central Processing Unit or CPU. The CPU performs the actual program and command execution. The programs dealing with driving the various peripheral equipment is referred to as the Operating System (for example: DOS : Disk Operating System, CP/M - Control Program/Microcomputers, etc.). The CPU is normally housed in an enclosure which contains power regulators, peripheral equipment interfacing 'cards', and expansion 'slots' to enlarge the capabilities of the PC system.

Jan 1, 1989

By Ted M. Noskiewicz, James A. Ramsay

INTRODUCTION During the various stages of an underground project from inception through design and construction, probably the single factor of most interest and concern is the nature of the ground. The ground conditions more than any other item govern costs and feasibility; and although the methods available for assessing the ground have become increasingly reliable during the past thirty years, it is still very difficult in many cases to predict the behaviour of soil and rock during and after excavation. To help in this ground evaluation process, we have frequently supplemented the boring program with one or more large diameter inspection holes; and during the past eighteen years, seventeen of these holes have been constructed on tunnel projects which we have designed. There are references in the literature to similar inspection holes (1); however, as far as we are aware, no detailed description of them has been published. The behaviour of soil or rock during and after excavation and the effect of ground water on tunneling operations are of vital interest to tunnel designers and contractors. A comprehensive geotechnical investigation is therefore among the early and most important tasks carried out on a tunnel project and the backbone of every geotechnical investigation is the boring program. A series of borings, typically 50 to 100 mm (21 to 4 in) diameter, are drilled from which soil samples or rock core are recovered and the ground water observed.

Jan 1, 1979

By Jim M. Johnson

INTRODUCTION The facility water balance and maintenance of sufficient excess storage volume in the solution control system are often amongst the most critical facets of design and operation of heap leach facilities in cold, snowy climates. The purpose of this paper is to summarize and discuss climatic and operational factors which have a significant impact on heap leach water balance evaluations in high snowfall climates. Example water balance simulations are presented for proposed heap leach projects located in areas subject to high snowfall in the northwestern United States. The climatic data input to these simulations represent both net evaporative and net precipitation climates. FACTORS AFFECTING WATER BALANCE EVALUATIONS The combined effects of seasonal operations, re1atively low evaporative losses, and potentially large inflows to the solution control system from snowpack and spring storms require an enhanced awareness of the factors which impact facility water balance. Unlike operations at mines in more arid climates, seasonal excess water rather than a shortage of make-up water is the rule. A thorough understanding of a number of factors, including regulatory constraints, climatic influences, and impact of operating philosophy and techniques, is critical to successful development of an incident-free heap leach operation under high snowfall climatic conditions. A process water circuit schematic for a typical heap leach operation is shown on Figure 1.

Jan 1, 1988

By Charles N. Speltz

The cost of transportation of industrial minerals frequently is higher than the cost of the product. When a mine, industrial-mineral plant, or customer is served by a single railroad, because of the lack of competition, that railroad may in- crease rates and/or reduce service so that the economics of that mine, plant, or customer are affected adversely. Transloading of industrial minerals from rail-to-truck or truck-to-rail to improve economics and sales of product is not a new concept. However, transloading to create competition and reduce freight costs or to improve service is a relatively new concept brought on by the recent mergers of many of the main-line railroads, both in the eastern and western United States. For example, in 1998, with completion of the Burlington Northern/Santa Fe (BNSF) and the Union Pacific/Southern Pacific mergers (UPSP), the western United States has only two main-line railroads. The industrial-mineral producer, to reduce the cost of transportation or increase the level of service, must evaluate potential transloading opportunities in light of higher prices and reduced service brought on by reduced railroad competition. This paper discusses industrial-mineral transloading and examines the case history of the Tucker Hill perlite project in southern Oregon. The Tucker Hill project is a classic study of industrial-minerals transloading where the project would have failed without the transloading.

Jan 1, 1999

By J. F. Cuderman

In situ experiments at the Department of Energy's Nevada Test Site (NTS) have extended the technology of propellant-based fracturing to include liquid- filled, uncased boreholes. Previous work had developed the technology for liquid-free, uncased wellbores. Test results show that fracturing behavior is considerably more complex in liquid- filled boreholes than in the liquid-free case. Compared to liquid-free boreholes, liquid-filled boreholes have faster pressure risetimes and lower peak pressures, large hydraulic-type fractures propagating several meters beyond the end of the test zone, numerous oscillations in the pressure history, and variable types of fracturing within a single test region. Multiple fracturing is initiated in the wellbore of a fluid-filled borehole when the proper propellant mixture is used but, unlike fluid-free wellbores where up to eight fractures propagate, only one to three hydraulic- and/or shear-type fractures propagate. Hydrodynamic effects involving liquid compression during borehole pressurization appear to be responsible for the differing phenomena observed in fluid- filled boreholes.

Jan 1, 1986

By J. Maiti, A. Bhattacherjee

A literature review on quantitative analysis of mine safely studies revealed that numerous investigators explored a wide- range of techniques, including the investigation of bivariate and multivariate statistical models. Although these researchers addressed various issues of accident causation and prevention, they, in general, did not investigate through the use of quantitative models the multivariate relationships of several factors affecting mine safety in a causal framework. In this paper, systems dynamics and structural equation modeling are presented to simultaneously represent and study the effect of policy variables related to accident prevention along with the factors causing accidents and injuries. The application of these models to a group of mines revealed that current training practices at these mines do not appear to alleviate accident occurrences. It is inferred that the use of these quantitative techniques can provide a new direction of research in mine-safety studies.

Jan 1, 2000

By Lawrence F. Rooney

The wide distribution of limestone and dolomite and the decentralization of the depedent industries give the State Geological Survey a major role in the, development of these mineral resources. The amount of geological information necessary for efficient exploration is so large that few companies can afford to do the necessary basic field work or store the data. The state surveys fill these responsibilities and thus might be said to serve as the geological research departments of the limestone and dolomite industry. At the Indiana Geological Survey, the data of most value to limestone producers are in the form of unpublished measured sections, well records, cores, chemical analyses, directories, and geologic maps. Much of this information is published in summary form. The Survey also assists individual members of industry in exploration and evaluation of mineral deposits. In addition, a progressive State Survey provides the geological infor¬mation necessary for the development of new resources which do not appear to justify industry's own preliminary efforts.

Jan 1, 1966

By N. Djordjevic

The vibration energy that travels beyond the zone of rock breakage is wasted - all it does is cause damage and annoyance. Under favorable geologic conditions, this energy may travel many kilometers before it finally drops bellow the background noise level. This has forced the introduction of more restrictive limits to the allowable vibration levels. To maintain the profitability of a mine or quarry and to comply with environmental protection legislation, blasting needs to be performed in a more predictable way that will ensure that the final results are optimal in both mining and environmental terms. Minimization of ground and induced structural vibration is, therefore, a matter of good blasting practice - not just an attempt to avoid complaints from neighbors. A new approach to blast vibration minimization is presented. The method utilizes the existence of the local minimums in the frequency spectrum of single-hole blast vibration. The results are presented as a delay map showing maximum ground or structural vibration velocity for many combinations of interhole and interrow delays. A blast engineer can use this map to select an optimal combination of delays that will produce a low vibration velocity at a selected location and, at the same time, will be acceptable from the point of view fragmentation or muck pile shape.

Jan 1, 1997

By M. A. Marticorena, R. Stratton-Crawley, C. I. Basilio

Diethylenetriamine (DETA) is a selective depressant for nickeliferous pyrrhotite during pentlandite flotation. Laboratory flotation tests conducted on ore and process samples showed that pyrrhotite rejection is greatly improved by small additions of DETA; however, the effectiveness of this depressant is most noticeable when the mineral sample is oxidized. LIMS and XPS analyses conducted on flotation products and pyrrhotite specimens showed that the difficulty in pyrrhotite rejection arises from inadvertent activation of the mineral by heavy metal ions, such as Ni2+, cu2+ and Ag+, that are present in the process water. In the presence of DETA, however, the mineral is deactivated under oxidizing conditions. The deactivation mechanism may involve oxidation of the activation products, which are likely in the form of heavy metal sulfides, followed by solubilization by DETA. FTIR spectra of pyrrhotite electrodes contacted with DETA showed no trace of the reagent on the surface, substantiating the view that its role is one of complexing agent that enhances the dissolution of activation products under oxidizing conditions. FTIR spectra of pyrrhotite contacted with amyl xanthate solutions showed that both dixanthogen and iron xanthate are formed on the surface, the latter becoming more predominant at higher potentials. In the presence of DETA, however, only a small amount of xanthate is adsorbed on the mineral at potentials (Eh) approximately 200 mV higher than the case without DETA.

Jan 1, 1995

By N. A. Frazier

The technology for using limestone or lime to scrub SO2 from power-plant flue gas has significant implications to the limestone industry. A brief status report on these processes will be made, possible process requirements on the limestone properties will be reviewed, and projections on the buildup of demand with respect to time will be reviewed. Disposal problems inherent with the use of these throwaway processes will also be summarized. Given a viable technology, relations among (1) distance of power plants from low- and high-sulfur coal and limestone deposits, (2) modes of handling and transporting immense tonnages of bulk material-coal and/or limestone, and (3) regional air-quality standards are some of the factors which will ultimately determine the demand for limestone. A discussion of these factors will be presented, with the intent of identifying geographic regions where significant increases in production can reasonably be expected.

Jan 1, 1974