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By Sigmund J. Sulinski

The following is a progress report on a continuing study being made by the Sanitary District for purposes of developing reliable data for predicting costs and progress on future tunnel contracts. All data available to date on five separate tunnel contracts has been analyzed. All were machine-mined in soft ground, all used steel ribs and wood lagging and finished inside diameters varying from 5'6" to 6'6". Basic data regarding progress per shift, hours mined per shift, hours of downtime per shift, cause of downtime and type of soil mined were reported by the District's resident engineer at the job site. Figure 1, Weekly Mining Report is an example of the form used. Data regarding manpower and equipment used during tunnelling operations was also supplied by the resident engineer during the course of construction. Soil type being mined was verified by the resident engineer during construction, by visual observation, and compared with data listed on a previously prepared soil profile. The soil profile is a graphic presentation of anticipated soil stratas superimposed on a cross section

Jan 1, 1997

By M. J. Zdunczyk

Sand is one of the most common materials on the earth’s surface. It is a naturally occurring material resulting from the physical and chemical breakdown of rocks. The definition of sand varies, as do the number of products made from the material. Sand is generally classified by grain size, however the measurement or scales differ depending on the context in which it is being used. Geologist define sand as particles of rock between .05 and 2 millimeters in diameter. The variability of the mineral composition generally dictates which sand can be used for different industrial purposes. For example, sand used for Portland cement concrete and asphaltic concrete mixtures can be very different in physical and chemical composition than sand used in the making of fiberglass. In this paper, construction uses of silica sand, which consists almost entirely of the mineral quartz (SiO2), will be discussed and analyzed.

Jan 1, 2001

By B. Denby, R. Hollands, S. Cooper

Augmented Reality (AR) is a technology that can be used to mix computer-generated images of data with views of the real world. The University of Nottingham is developing AR technology in a major research project which can be used to assist mining companies in visualising complex mine data whilst out in the field. The technology comprises of integrated GPS surveying technology and electronic orientation devices to provide location and viewing information, video capture via digital camera and portable computing hardware to overlay 3D models on views of the real world. The paper describes the concepts of the technology in some detail and concentrates on the possible applications of this in the surface mining and exploration industries.

Jan 1, 2002

By K. C. Jordi

Many systems which are modelled mathematically result in a model where the relationships between some or all of the parameters are found to be non-linear. These systems are usually complicated further by a desire to make the system achieve multiple and often conflicting objectives or goals simultaneously. Rozwadowski (1970) developed a model to describe the total discounted net profit of a mine as a function of the amount of ore developed and of the grade of the amount of ore mined. Dynamic programming was used to determine the policy which gave the maximum net present value. In this paper it is shown that the relationships between the variables can be approximated by piecewise linear functions. This is amenable to solution by an algorithm based on the simplex algorithm of linear programming. The goals of maximizing the net present value, the total net profit and the total gold output are incorporated simultaneously into a goal programming formulation of the system. The resulting model is characterized by a large number of disconnected constraints. These are decomposed into several smaller problems and the problem solved. The solution is examined to discover the sensitivity of the system to changes in certain parameters. In particular the interaction between the three goals is analysed to determine whether there is conflict between any of the goals and, if so, what the trade-offs between the conflicting goals are.

Jan 1, 1979

By V. Nenov

The study is based on the so called METASEP process which includes selective sorption of heavy metals by special bonding agents (BA), separation of boding agents from the water by means of microfiltration and/or flotation and regenerating the loaded bonding agents, leading to a metal concentrate for reuse or discharge. The bonding abilities of different bonding agents suitable for application in METASEP process were evaluated. Two groups of BA are studied, namely: chelating ion exchange resins and water soluble oligomers. The group of ion exchange resins studied includes eight organic resins, mostly chelating cation exchangers and representatives of conventional strong and weak cation exchangers. The resins with iminodiacetic and aminomethyl phosphoric acid groups showed highest affinity towards several heavy metals. The study of resin particle size showed that this parameter is a key factor influencing the kinetics of heavy metal sorption. The group of water soluble oligomers (WSO) includes polyvinyl alcohol, carboxyl-methyl-cellulose, polyvinylethylenimin and pectin. The Metal-WSO complexes were separated by Ultra Filtration. The effect of Metal-WSO mole ratio and pH was studied. Depending on the operational conditions the heavy metal retention varies within 68-99%. It was shown that regardless of pH and mole ratio Metal-WSO, separation of certain ion from the metal mixture is not possible.

Jan 1, 2006

By V. Carabias-Hütter, A. J. Basu

The paper aims at promoting sustainability assessment and reporting into practice using a globally acceptable set of guidelines and a common framework for internal and external reporting at a project/site level. Indicators are used for measuring performance, and this paper addresses development and implementation of performance indicators for sustainability assessment and reporting at local as well as global levels. The selection of a proper set of indicators is a challenging task. The indicators selected should provide the expected information for making right decisions. Relevant and credible sustainability reporting supported by a consistent performance indicator system can be the starting point for benchmarking environmental and social performance for the natural resources sector.

Jan 1, 2004

By J. Patrick Powers, Arthur B. Corwin

Modern improvements in hydrogeology make it possible to predict with good reliability the performance and cost of ground water pumping systems in many tunneling situations. The testing and analysis techniques are presented. Data from the Buffalo NY LRRTS (1978-1980) illustrate the successful application of the technique for tunneling in rock. Data from the Red Hook Interceptor Tunnel in Brooklyn NY (1978) illustrate the application in soft ground. The Red Hook project also illustrates concerns for the side effects from dewatering, such as ground settlement and damage to timber structures. At Red Hook protective measures included compressed air, artificial recharge and controlled dewatering. Given the uncertainties of the underground, the possibility of unexpected situations must be considered. A hard rock sewer tunnel in Atlanta, Georgia (1982) illustrates an unexpected problem, and the emergency measures used to solve it.

Jan 1, 1985

By Vljay K. Chhipa

Artificial intelligence is" an emerging technology in the field of computer application. Expert system have been developed to imitate human intelligence and reasoning process. Expert systems have much scope of application in the decision making process in mineral exploration as such decisions are highly subjective and expert opinions are very helpful. This paper presents a small expert system to analyze reasoning process in exploring for uranium deposits in sandstone.

Jan 1, 1989

By R. T. Swindeman

"INTRODUCTION This paper will discuss the topics in the recently released Conveyor Equipment Manufacturers Association’s (CEMA) Belt Conveyors for Bulk Materials, 7th edition, that deal with safety and maintenance. The most effective way to improve conveyor safety is through designing out hazards in the earliest stages of a project. When the safest way to perform maintenance is also the easiest, mechanics will naturally take the obvious and least hazardous approach. IMPORTANCE OF ACCESS Studies have shown that mechanics spend almost one-third of their time accessing the components to be serviced and approximately 25% of all fatal conveyor accidents occur during maintenance1. Chapter 2 of Belt Conveyors for Bulk Materials deals with design considerations. In Chapter 2 there are recommendations for access at the various sections of a typical conveyor for cleaning, inspection and maintenance. While, in some cases, providing access will increase the cost of the conveyor system there can be significant paybacks in reduced injuries, faster maintenance and easier cleaning. Piping and Conduit One of the significant recommendations in Chapter 2 for access is to restrict the mounting of piping and conduit to the conveyor structure in the Loading and Discharge zones of a conveyor. Piping and conduit are more permanent fixtures than maintainable components and should be located out of the way of components needing frequent maintenance. If electricians and pipe fitters are given convenient locations to make their runs they will natural use them. Flexible conduit and hoses can be used to connect to components from pipe racks and cable trays which further enhances maintenance. Access for Cleaning Another critical aspect of access is for cleaning. Approximately 33% of all fatal conveyor accidents occur while cleaning spillage and carryback under and around conveyors2. In the loading zone having sufficient height under the conveyor for cleaning increases the cleaning interval and allows for safer cleaning. In the discharge zone having adequate access for belt cleaning installation has a direct effect on the ability to install a proper cleaning system and perform maintenance."

Jan 1, 2015

By P. Tsang, S. S. Peng

Mine floor failures, such as floor heave and floor buckling, occur frequently in underground coal mines where soft mine floor exists. The types of failure can usually be classified into two categories; shear punching failure and tensile failure. A model based on the Winkler's elastic foundation is proposed in this paper for floor stability analysis. The model considers material properties of floor strata, in-situ horizontal stress, pillar size, entry width, and configuration of multiple-entry system and predicts stress conditions in the mine floor based on given in-situ mining and geological conditions, as well as deformation of the mine floor. This information is used to predict possible failures of mine floor by comparing the strength of mine floor with its stress condition. The validity of the model is verified by in-situ data described in this paper.

Jan 1, 1992

By K. C. Vories, C. D. Elifrits, F. F. Haston

The required reclamation of land disturbed by surface coal mining often results in the creation of some oversteepened slopes that are prone to rapid erosion and sediment production. This natural activity on such slopes is not desirable nor allowed under current regulations. Experience has shown that novel approaches must be devised to address the problem. Research conducted on field sites in Missouri has indicated that construction, during the reclamation and grading processes, of a man-made drainage system will control the erosion. The drainage system must replicate or exceed the natural system in terms of drainage density and channel frequency. Basic design considerations are summarized in this paper, and field results are shown.

Jan 1, 1987

By R. V. Ramani, R. Bhaskar

While the National Academy of Sciences has stated that gravimetric sampling technology for compliance purposes is adequate, research into various aspects of respirable dust control require data on many other parameters of airborne dust. These, in turn, have created the need to use many instruments, other than personal gravimetric samplers, in mine environments for dust measurement. There is a need to evaluate the performance of these instruments under conditions of potential use. As part of research in the Generic Technology Center for Respirable Dust, cascade impactors, gravimetric personal samplers and gravimetric samplers collecting dust using isokinetic sampling principles were employed for dust measurements under identical conditions in a mine airway. During the course of the experiments, 8-stage cascade impactors and gravimetric samplers drawing air isokinetically were located in the center of a mine airway at various stations. Two types of data were examined - concentration of dust and size distribution of the dust collected in the samplers. The data show that the amount of dust collected by an impactor is less than half the amount collected isokinetically. The size distributions of the dusts collected from the two instruments, though comparable, show a consistent difference in median diameters. The cause for this bias is examined. The paper presents and discusses the results of the tests, including the concentrations and size distributions obtained from the two instruments for different experimental conditions. There is a need to document the performance of various dust measuring devices in mine airflow conditions.

Jan 1, 1987

By Thomas O’Neil

Part 2 of this article continues with a discussion of features that distinguish contemporary investment analysis in mining from earlier methods. Part 1 traced the evolution of evaluation methodology from the traditional and discounted cash flow methods to the present. Quantitative investment models of the past 20 years played an important role in mine evaluation, but a new integrated approach to mine investment decision-making is now developing because of growing economic, technical, and political uncertainties. One of those uncertainties -inflation-was discussed in Part 1. Increased Risk At a time when mineral production technology and analytical evaluation tools have never been more sophisticated, it may seem anomalous to claim that mining ventures are riskier. Whereas technical risk has, indeed, been notably reduced, business risk the chance of a major loss due to market factors-has increased. This has been caused by two factors: the rapidly rising capital requirements of new projects and increasingly unpredictable future economic conditions. These difficulties are compounded by the long lead times of large, new mining projects. Rising Capital Requirements A $100 million investment is no longer considered to be a large mining project in most cases. For a large metal mining project, the total cost of the concentrator alone can exceed $100 million. Amoco Minerals' Thompson Creek molybdenum mine being developed in Idaho will cost over $350 million, for a relatively modest sized (23-kt/d or 25,000-stpd) ore operation with no extraordinary features. For a major grass roots copper operation producing blis¬ter or refined copper, the capital requirements are billions of dollars, not millions. Project costs are higher for two reasons. One, the projects themselves are larger; and two, the capital cost per unit of production is rising rapidly. Projects are larger because lower grade ores, yielding smaller margins, must be mined in greater volume-particularly in view of the high fixed costs of modern technology. When analysts contemplate any capital project, an important consideration is the minimum economic size of the facility. This is the smallest size that can be built and still be competitive on a total unit production cost basis. In the conventional copper smelting business, for example, a production rate of at least 91 kt/a (100,000 stpy) of blister copper is about the absolute minimum for reducing unit fixed costs to competitive levels. Clearly, many variables affect the minimum economic size of a mining facility, but with few exceptions that size continues to grow. Unit capital costs of new mining projects also are continuing to rise. The accompanying table shows that the capital costs in primary copper production have risen faster than the cost of living. Of particular note is the capital charge of over $1.70/kg (77411b) required for a new, fully integrated facility in 1981. Thus, the mid-1982 copper price would not even cover the cost of capital for a new copper producing complex without considering the direct operating costs for such a facility. The breath-taking costs of new mining projects are caused by factors such as increasingly complex technology, the rising social costs of creating attractive living and working conditions for employ¬ees, and the expenditures re¬quired for environmental protec¬tion. For whatever reasons, how¬ever, unit capital costs in mining continue to exhibit staggering growth rates. Future Economic Conditions Risk is not only a function of the size of the potential loss-an im¬portant measure of which is the capital intensity of mining dis¬cussed above-but also of the like¬lihood of incurring the loss. It is here that the ever increasing lead times of mining projects and the glaring limitations of economic forecasting are so important. In comparison to nearly all other in¬vestments, mining has more capi¬tal at stake for a longer period of time before commercial uncer¬tainty is resolved by distant eco¬nomic conditions that are subject to high forecasting errors. A sobering example of the pre¬ceding points occurred with the Lakeshore copper mine in south¬ern Arizona that Hecla Mining Co. undertook to finance and manage in 1969. The project was a joint venture of Hecla and the El Paso Natural Gas Co. and included two mines-one producing oxide ore and a second in the sulfide zone¬and a complex processing facility producing both electrowon cop¬per cathodes and copper precipi¬tates. The project originally was

Jan 12, 1982

By Dean D. Turner

Exploration geochemistry requires computer processing for quick and efficient reduction and interpretation. An easy to use microcomputer based geologic workstation fulfills this need and allows the geologist to independently process geochemical data. Functions necessary for geochemical data processing are: 1)Digitizing; 2)Communications; 3)Data base management; 4)Statistical analysis; 5)Mapping analysis; and 6)General purpose applications (ie: word processing). A geologic workstation that can perform these tasks will yield significant advantages in processing and interpreting geochemical data.

Jan 1, 1987

By R. H. King

The US coal industry has been using continuous room-and-pillar mining (CRPM) machines for more than 30 years for longwall development. This equipment has also been used for production mining in areas that are not appropriate for longwall mining. From 1977 to 1987, the portion of annual US production mined by continuous miner (CM) sections grew slightly from 65% to 70%. Over this time, mine operators and manufacturers have made some advances to attain the full production potential of this method. This is evidenced by the fact that average tons per eight hour shift for continuous miners in the US grew from 180 t (200 st) in 1977 to 431 t (475 st) in 1987. The authors (1990) reported that the increase in productivity was due to several factors: • a drop in prices; • a more mature workforce; • union stability and incentive programs; •procedural improvements; and •technological advances. The authors estimated that about one-third of the increased production came from the first three and other unaccounted for factors and one-third each for the last two. Even though improvements were considerable, continuous miner capacity is much higher than 431 t/shift (475 st per shift). For example, the machinery is capable of mining more than 9 t (10 st) per machine for the 6.5 available hours per shift or 3.5 kt (3900 st). However, this has never been attained on development. The averages of most mines are less than 900 t/shift

Jan 1, 1991

By Donovan F. Symonds

INTRODUCTION The selection of the optimum coal preparation plant flowsheet is a vital part of the development of a new plant or the expansion of an existing facility. Selection of an inappropriate flowsheet or individual equipment items can result in costly production losses, or needless expenditures or redundant or oversized equipment. The accuracy of the flowsheet selection process is, like most decisions, heavily dependent upon the amount, reliability, and quality of the database. A flowsheet which is based on simple borehole information from an area that has experienced little or no previous mining activity must necessarily include significant allowances for uncertainties. However, a plant which is to be built at an existing mine with good information on run-of-mine (ROM) coal quality, as well as bulk washability data and accurate projections of future quality, can be optimized. The following chapter will describe the processes which should be followed to select the most appropriate flowsheet for each unique operation. They include: 1. Examining and adjusting the washability database to reflect the ROM feed. 2. An evaluation of clean coal specifications. 3. Selection of the level of washing required. This includes no washing, if the coal is already at the desired specification, all the way through to complex total washing circuits for metallurgical grade coals. 4. Selection of the appropriate circuit such as dense medium bath vs. Baum jig. The most appropriate circuit is generally determined on the basis of economics. An approach for performing the evaluation will be desired. 5. The steps that need to be followed to develop a balanced plant flowsheet. ADJUSTING WASHABILITY DATA It is not unusual to have as many as 10 to 20 sets of washability information available for a particular mining property. These may be a combination of core and bulk samples or all bulk samples. In the latter case, they may also be face and/or ROM samples. It is necessary to reduce all of this information to a single set of washability data that is representative of the mean feed to the proposed preparation plant. This set is used to compare the clean coal yield and quality characteristics of the various flowsheet options. The term "representative" has some serious negative connotations. It is recognized that ROM coal quality will vary throughout a mine. However, over a period of 250 to 350 days per year, certain trends can be established. If possible, this "representative" sample should be close to the coal quality of the mean daily sample in terms of raw ash and sulfur contents, clean coal yield, and clean coal ash and sulfur content. If possible, this sample should be within the

Jan 1, 1991

By Charles H. Tiernon

Separation of particles on a table deck* results from differences in specific gravity, plus a number of other interrelated phenomena: size of particles; shape of particles; stratification (consolidation trickling); and hindered settling. The effective use of these factors may be controlled and aided by the following table adjustments: differential action of the drive or head motion; speed of motion; length of stroke; side tilt; end elevation; size of deck area; shape of deck; character of deck surface; riffle design; amount and distribution of wash water; feed water-to-solids ratio; feed rate; and feed uniformity. The typical concentrating table used in the US coal industry is essentially a rhombohedral-shaped deck supported by a suitable subframe. It generally slopes in the direction of the short axis, tilts upward at the refuse end of the long axis, and is differentially reciprocated in the direction of the long axis. This head motion tends to move the particles longitudinally toward the end of the table. At right angles to this movement, wash water (distributed along the high side of the table) tends to move particles down the slope parallel to the short axis of the table. Hence, the natural path of a particle on a concentrating table is from the feed box corner to the diagonally opposite corner of the deck (Fig. 1). There is a natural tendency for heavier particles to sink to the deck of the table and for lighter particles to stay nearer the surface. As a consequence, the heavier particles are carried further along the longitudinal axis since, being on or near the surface of the deck, they are more affected by the table's reciprocating action. The lighter particles, being at or near the top of the moving bed, travel slower in a longitudinal direction and thus separate from the heavy particles. Wash water and the diluting water in the feed cause lighter gravity particles to move down the short axis of the table. The feed material then fans out from the feed box, where it enters onto the table with heavy gravity particles moving in one direction and lighter particles moving in another. By properly adjusting all of the previously mentioned factors, a clear-cut separation is possible between high- and low-gravity particles, or between refuse and coal. Riffles are of great importance to tabling. They create considerably more capacity than is possible with smooth decks, and they are responsible for better separation accuracy. Particles in their downward movement along the deck's slope are delayed behind the riffles. Hindered settling, consolidation trickling, and other phenomena occur as the particles tumble over the riffles and stratification ensues. The heavier particles settle to the deck of the table and are trapped behind the riffles, thus insuring their positive movement toward the end of the table. Since stratification and separation of particles are not complete as a result of any one riffle, a series of riffles are used. The cycle of stratification and hindered settling is repeated from riffle to riffle. The result is purer products as particles fan out and progress forward and downward over the table. The smallest, heaviest particles stratify downward to the surface of the deck more quickly and are carried out by table movement toward the refuse end at a faster rate than coarse, heavy particles. Light gravity, larger pieces ride on the top layer of particles and flow down the deck's slope as a result of the cross flow of wash water at right

Jan 8, 1980

By Mark J. Dowiak, Daniel Threlfall

The disposal of hazardous chemical wastes will be one of the major environmental issues of the 1980s. About 45 Mt of hazardous wastes are produced yearly. One major aspect of the problem is the siting, design, and construction of' environmentally acceptable disposal facilities to accommodate this huge volume of material. Surface mines have been considered attractive for development as disposal sites for several reasons. • Surface mines offer an open pit that can conveniently serve as a repository for wastes. This could represent a significant economic, savings when compared with sites on undisturbed lands that might require extensive excavation or embankment construction. • Surface mines often have an abundance of mine spoil available that could potentially serve as construction material. This could result in a significant economic advantage over other sites that might require extensive amounts of construction material to be excavated or hauled in. • Operation of a commercial disposal facility in a surface mine can reduce or totally alleviate reclamation costs. • For an abandoned surface mine, conversion into a disposal facility could represent a positive form of land use and may provide a means for reclaiming lands that would otherwise remain unreclaimed. Despite these positive reasons, there are many technical factors associated with surface raining that can make the prospect of disposal site development an uncertain one. Before discussing factors associated with mining that can present siting, design, or construction problems, some understanding of the basic components of a chemical waste disposal facility is necessary.

Jan 2, 1981

In a future world of 8.5 billion people in 2035, the Energy Information Administration's (EIA) projected 50% increase in energy consumption will require true "all of the above" energy resource use from oil, gas, renewables, nuclear, and coal. In particular, coal will continue to be the world's energy cornerstone, providing more incremental energy over that same time period than any other single fuel. Coal has long been a centerpiece of a low-cost, high-reliability electricity grid. Today there are 1.3 billion people across the globe without access to electricity and 2.7 billion people who do not have clean cooking facilities. The problem is spread across the developing world, but it is particularly severe in sub-Saharan Africa and developing Asia, which together account for 95% of people in energy poverty. Without a commitment to achieve universal energy access it has been estimated that by 2030, there will be an additional 1.5 million premature deaths per year caused by household pollution from burning wood and dung and through a lack of access to clean water, basic sanitation and healthcare. Modern energy sources are essential to meeting these challenges.

Jan 1, 2012

By S. G. Axen

Design of wells for in-situ leaching is based on individual mining operation and ore deposit requirements. Major design considerations are well flowrate, depth, fluid composition, expected well life, mine operating plan and cost. A large variety of downhole equipment, materials of construction, contract services and methods of well completion and stimulation are available. A generalized design procedure which allows the engineer to optimize well design for a particular ISL application is described.

Jan 1, 1988