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By Paul Javor

Optimization of a process is achieved by selecting, 'from all the known options, the most beneficial method of obtaining a product. It is rare that the optimum process is arrived at by conventional methods, because of the great amount of time required for developing and comparing all the options. On the other hand, it is now possible, by means of an optimization program based on special mathematical formulas involving an algorithm and implemented by a computer, to plot the optimum process realizing considerable savings and in a reasonably short time. The flow sheet arrived at in accordance with the optimization program described in this paper investigates and develops all the possible options and, with the aid of the computer, makes it possible to select the most economical ore beneficiation process. The options in an ore beneficiation process are all the possible trajectories that can be traced through the particle sizes to which the ore is reducible in the extraction of its valuable minerals. Although an ore can have a wide range of composition and several valuable minerals that can be extracted, this paper is concerned with the special case in which only one mineral is extracted from the ore and in which the maximum allowable percentage of impurities in the end product is defined.

Jan 1, 1971

By Claude Froger

The compared advantages of digital and analogue computers for solving ventilation problems have for many years been a matter of discussion among the specialists whose respective arguments have prevailed in turn depending on the progress of technology. In the French coal mines however none of these two techniques has superseded the other so far. In France, between 1956 and 1962 only the digital computer and from 1962 to 1967 only the analogue computer was used. Since then they are both used concurrently and complementarily. Depending on the problems dealt with, the most advantageous method is chosen in each case. In the case of ventilation planning for projected workings, it is possible to test variant forms of the development plans and many parameters can be varied. In such a case the flexibility of the analogue computer is a great help. Wrong lines taken will be rapidly abandoned and little by little solutions will be found. By examining the results of a test, new ideas will generally come into the mind and they can be tested right away. Such an investigation is always-carried out in conjunction with the engineers of the mine concerned. In complex networks it often leads to solu¬tions which could not have been devised from the start. The same work could be done by using a numerical method and the digital computers operating in the different coal mine districts, but for the same tests, the time required would be much longer and the participants would not be encouraged to use their imagination so intensively. Or the other hand for calculations of ventilation networks in ventilation surveying, use is made of the digital computer which gives the possibility of storing the data corresponding to the different mines concerned. The questions to be solved concern problems for which the ventilation network is essentially known, and in which only a small number of parameters can be varied. The few possible alternatives to be calculated can therefore be handled by the digital computer in spite of the relative lack of flexibility of the method. To sum up our ventilation studies are conducted in France as follows: - For ventilation studies and modifications due to projected workings use is made of the ana¬logue computer. For a given mine the updating of such ventilation studies is carried out every 3 or 5 years according to the progression of the workings. - For ventilation surveying while normal working operations are in progress, use is made of the digital computer.

Jan 1, 1980

By G. T. Lineberry

Reduced clearance is one of the most important characteristics of encumbered space in underground coal mining. Another key variable is the maximum velocity at which a piece of mobile mining equipment can operate in this limited space. Typical velocity- clearance curves for different mine transportation systems are developed and characterized. Applications of the relationships are examined, emphasizing their significance in the design and control of mine materials handling systems.

Jan 1, 1983

By Atmesh K. Sinha

The demand for thermal coal both nationally and internationally is projected to increase rapidly. The marketability of high ETU thermal coal produced in the USA is, however, limited by its high sulfur content. Fortunately, over 70 percent of the sulfur exists in pyritic form. The research conducted at Southern Illinois University indicates that over 90 percent of the pyrite can be removed by simple devices such as concentrating tables, cyclones, or froth flotation cells and the desulfurized coal can be blended with low sulfur western coal to produce EPA compliance coal. Thus, both the low BTU western coal and the high sulfur midwestern coal can be rendered competitive in the utility markets, here and abroad due to improved utilization.

Jan 1, 1983

By Larry Powell

Rend Lake is an Army Corps of Engineers reservoir located in Franklin and Jefferson Counties in south-central Illinois. The lake consists of 20,000 acres of water and 19,000 acres of public access land. The site attracts over two million visitors a year and is surrounded by campgrounds and other recreational facilities. The lake overlies the largest tonnage of low sulfur coal in the state. Coal is being removed beneath the lake from five mines operated by three coal companies. Currently high extraction mining operations are approaching low-lying, environmentally sensitive, and high-use recreational areas. Advanced planning to maximize coal extraction and minimize potential effects of subsidence requires the development of procedures to assess the impact of high-extraction mining on the land use of the area. The Bureau of Mines, the Corps of Engineers, and the coal companies have initiated research to assess the following proposed planning steps to ensure the maximum recovery of the coal resources while minimizing impacts to surface land use: 1) Establish a dialogue between the surface and mineral owners; 2) develop a geographic information system to aid in assessing existing land use and potential changes; 3) assess the potential effects of subsidence on drainage, wildlife habitats, and changes in land use prior to mining; 4) coordinate the mining displacements with surface activities to minimize disruption; and 5) develop appropriate mitigation plans before mining occurs.

Jan 1, 1986

By John W. Rushton

Maintenance and inventory are usually the last items considered in mine development. They need to be addressed properly and early. The micro-computer brings sophistication within the reach of even the smallest mines. Maintenance and inventory programs, if properly installed, will reduce costs 15 to 25% and allow management time to address the mining and metallurgical problems at start up. Shops and warehouses are rarely designed properly. Large engineering firms spend 5 to 20 times more than is necessary for first class facilities. There is an optimum design, size, and layout. Take the time necessary to assure you get the right people, programs, and facilities in that order. Maintenance, inventory, and inventory control must be addressed early if a small mine is to have a chance at optimizing costs during the first two years of operation. This is hard work and is usually put on the back burner until the mine is in some degree of trouble. Hiring an experienced maintenance superintendent is important but it is not the complete solution. Maintenance systems, design of facilities, and use of computers are not skills that maintenance people usually have. In addition, the work of ordering spare parts and working with erection people is a full time job and any maintenance people on site during construction are quickly recruited. The end result is that few mines start up with an adequate Maintenance or Inventory System in place. The months, and in some cases years, that the mine attempts to operate without a system are both painful and expensive. Designs of successful integrated maintenance and inventory programs are virtually 100% supported with some outside assistance. Our system is the approach that we are most familiar with and this paper will isolate how Rushton International would go about setting up systems and designing support facilities. Micro-computers are the only way for a small mine to go. ~ini-computers cost more originally and operating costs are many times higher than even the most sophisticated micro system. Micro- computer software is developed further and recent advances in hardware makes medium priced units equal to most mini's in RAW COMPUTER POWER. Mines in general, and especially small mines, have no need for main frame power. MAINTENANCE A good maintenance program has: 1. Equipment Master List a. Equipment Detail Reports 2. Work Order and Backlog Control Program 3. Component Control Program 4. Tire Program 5. Wear Materials Program 6. PM Control Program 7. Maintenance History Program 8. Performance Program We also track miscellaneous items such as MSHA training and inspections, timekeeping, etc. Rather than going through the program step-by-step, it makes more sense to go through a typical Maintenance Day and show how the programs are used. The first thing maintenance supervision needs to know is "how we are doing." We

Jan 1, 1987

By Adrianus Halim, Jenni Hooli, Bartłomiej Skawina, Fredrik Sundqvist

Transitioning from diesel-powered loading and hauling machinery to battery-electric vehicles (BEVs) responds to the need for deepening underground mines as regulations become tighter. When using BEVs, exhaust gases and diesel particulate matter (DPM) emissions can be eliminated, and the energy required for the machines is used more effectively. Unlike their diesel counterparts, which are refueled, BEV loading and hauling machines — specifically, load haul dump (LHD) machines — can use battery swapping. This brings additional aspects to the operation that need to be considered, which have not yet been studied extensively. This study used discrete event simulation (DES) to analyze how the different numbers of BEV LHDs affect queueing and productivity when using different numbers of batteries and different swapping times in an underground block cave mine. The results identified the formation of working groups, where the machines swapped their batteries concurrently within each group, and their relation to the queueing time. Additionally, the minimum number of batteries per machine was identified to maximize productivity while minimizing queueing time. This study demonstrates DES as a powerful tool to assess and analyze conceptual systems and identify their underlying structures, which can enhance the deployment of BEV LHDs in underground block cave mine operations.

Apr 1, 2025

By J. H. Daniel

Dust-related respiratory disease remains the major health concern in mining, and health agencies are proposing more stringent standards. The U.S. Bureau of Mines (USBM) is investigating techniques to continuously monitor respirable dust in real-time during the coal or ore extraction process. Continuous monitoring will allow mine operators to evaluate hazardous dust concentrations and adjust the operations to produce less dust. Mine instrumentation applications include machine-mounted and hand-held monitors, personal monitors, and area/environmental monitors. Six dust detection methods have been considered to meet application requirements. These are: light-scattering instruments, a smoke-particle detection technique, correlation of pressure drop across the collection filter with amount of dust deposited, the Tapered-Element Oscillating Microbalance (TEOM) instrument, a method that relates the amount of dust collected on a filter with the vibration of the filter, and beta attenuation measurement of dust. Studies to date have identified the TEOM instrument and the technique of correlating the amount of dust collected with the vibration ofthe filter as having the most promise for success. Development of the machine-mounted monitor is the highest research priority. The application options and progress to date in developing continuous monitoring instrumentation are presented.

Jan 1, 1995

By V. Matthews

"INTRODUCTION Typical grinding electrification requirements are defined by high power, constant torque and slow speed. Dual pinion mills also include a need for tight tolerances in torque between the two motors, to avoid overloading any single motor. Standard induction (asynchronous) motors have often been used but only in combination with mechanical gearboxes (reducers), required to reduce process speed to the correct level for mill pinions. The gearbox introduces added system complexity, capital cost, maintenance and energy cost due to mechanical losses. SYNCHRONOUS AND ASYNCHRONOUS MOTORS Elimination of the gearbox requires a motor designed to operate at a very low speed (rpm). Traditionally, mill motor requirements were best served by synchronous motors. The benefits of synchronous motors include- • Higher Efficiency (no conductor losses in rotor) • Very high power at low speed • Flexible Power factor (leading or lagging) • Constant speed (not load dependent) • More accurate speed control Synchronous motor cost is higher due to construction complexity, need for exciter and excitation panel, brushes, brush lifters. Figure 1 represents the equivalent circuit for a synchronous motor.Asynchronous motors, also known as squirrel cage induction motors, are singly excited, per Figure 2, the resulting equivalency circuit is less complex and only in need of a single voltage source.Commonly, a DC voltage supply is connected to the rotor (both physically and electrically) via brushes. The DC voltage enables the production of flux in a single direction. The brushes are connected to rings. The slip rings encircle the rotor but are insulated from the rotor. The slip rings are connected to a rotor winding known as a field winding. On large motors, brushless exciters are often used. A brushless exciter is a small AC generator whose field circuits are mounted on the stator and armature circuits are mounted on the rotor shaft. The exciter generator’s 3-phase output is rectified to DC by a 3-phase rectifier (mounted on the shaft) and fed into the main DC field circuit. It is possible to adjust the field current on the main machine by controlling the small DC field current of the exciter generator (located on the stator). [1] Brushless synchronous motors are often preferred over the traditional brush design but introduce additional complexity to motor construction in the form of additional windings and rectifiers comprising the excitation circuit. It stands to reason that because of the additional complexity, a synchronous motor will be higher in cost than an equally rated asynchronous induction machine."

Jan 1, 2015

By J. Hanna, I. Anazia

Selective fatty acid flotation of carbonate gangue from sedimentary apatites was achieved under acidic pHs without a specific apatite depressant and without conditioning the pulp with the collector. Concentrates (35% to 38% P2O5, 0.8% to 1% MgO) with high recoveries (80% to 85%) were produced from Indian and Chinese dolomitic ores. The calcareous and/or dolomitic-siliceous phosphate ores of South Florida and Utah required two flotation stages: one for carbonate removal, as mentioned above, and the other for phosphate recovery from siliceous gangue. Preliminary tests on the South Florida ore gave concentrates analyzing 29% P2O5 and 0.8% MgO, with a P2O5 recovery of 76%. A concentrate obtained from the western US phosphate ore from Utah assayed 30% P2O5 and about 1% MgO, with a P2O5 recovery of 89%.

Jan 1, 1988

By Jeremy Cawley, Jeff Murphy, Horry Parker, Brock Gaspar, Jake Keegan

The Lower Olentangy Tunnel project includes 47,000 cubic yards of planned ground improvement for earth pressure balance machine (EPBM) tunneling (5.2 km) and microtunneling (335 m) in glacial soils. Jet grouting started in late 2021 and will continue through 2023 to complete operations at 5 shafts, 14 safe havens, 5 watermain ground improvement zones, and a river crossing. Typical jet grout columns are installed at depths between 15–24 meters. Discrete soil-cement blocks range from 267–8,900 cubic yards in volume. This paper discusses the methodology, testing, and technical considerations associated with jet grouting operations in glacial overburden across an urban environment.

Jun 13, 2023

By Dwane K. Johnson

INTRODUCTION The small mining company faces the dilemma of how to finance the development of its properties because it doesn't have the financial resources to pay for the development costs from its own funds and doesn't have the financial strength which will enable it to borrow the money needed for development. However, with a little imagination and the right set of circumstances, a financing can be arranged for the small mining company. This paper is an attempt to describe the fundamental steps on how such financing can be obtained --in other words--what is required to provide ad- equate capital at a low cost for developing and bringing a mining property into production. Innovative financing follows from this. The basic keys for building and maintaining a successful mining company are "the four M's": Management, Market, Mine, and Money. The writer believes their order of importance is as presented and each is a building block required in order to obtain the type of financing that best suits the borrower and lender. MANAGEMENT Management must be experienced, highly organized, realistic, able to take advantage of opportunities and fulfill promises. Mine financing requires a variety of skills and concentration on the part of management. Management should have a thorough understanding derived from experience in geology, construction, mining and metallurgy and environment, marketing, and financial matters. Management must realistically visualize what will be produced at what cost and truly evaluate the risks associated so the proper security can be correctly designed. Since risk cannot be eliminated, the objective of management is to identify the risk which will be present in a given venture and assess the level of that risk which will be acceptable to the firm. Generally the risk which is present is subject to little or no modification. After management identifies and measures the acceptable risk the firm will proceed in a way that it will be least exposed. Management must determine its long-term objectives and strategies within the context of a constantly changing world. This question must be addressed before examining the sorts of risk which affect the development and operation of a specific property. The compilation and interpretation of "hard data" by competent people is good to a point but the experience and instinct of seasoned individuals are the important factors in management choosing a long-term direction for the corporation. The attitude towards risk greatly affects the goals of the corporation. Major risks in a mining project can be placed in four categories: 1. Market - Price, demand, substitution. 2. Costs - Capital, operating, financial. 3. Regulation. 4. Taxation. The feasibility study for a project is the fundamental tool used in the management of risk. Management should employ an experienced team with an established and well-understood set of ground rules for the preparation and assembly of a feasibility study. The necessary degree of realism is built into all levels of the study and if the project is technically feasible, the company's hurdle rate is then used to discount the base-case project cash flow in order to determine its financial viability. Understanding the geological significance of the mineral deposit is critical. There should be strong interplay among the pure regional geologist, the detailed mine geologist, the mining engineer, and the metallurgical engineer. The collaboration among these different disciplines will yield a feasibility study that is more reliable. The essence of this work must be appreciated and understood by the executives planning the financing. It is vital that they thoroughly understand the risks and make the proper risk assessments to cope with our rapidly changing market environment. Projecting future revenue values is paramount and is subject to much estimation. One way to mitigate fluctuations and the risk of falling prices is by selling production for future delivery. MARKET Since mining is a worldwide industry it is mandatory that bankers be aware of what is occurring in the marketplace, both foreign and domestic. The marketing of the production is a very important facet when considering financing for the small

Jan 1, 1987

By G. H. Schnakenberg Jr.

In response to the underground mining industry's growing concern with the exposure of workers to the diesel particulate matter (DPM) component of diesel exhaust, a method was developed to estimate the average workplace concentration of DPM that could be expected from using the new lower DPMemitting engines now being approved by the US Mine Safety and Health Administration (MSHA) when these new engines are equipped with state-of-the-art exhaustcontrol technology for filtering and combusting DPM. The resulting estimate uses the MSHA-reported particulate index for these engines, the prevailing rule-of-thumb ventilation rate of 150 cfm/hp and the available diesel-exhaust filter technology that has been shown to be at least 80% effective in reducing tailpipe DPM. In the estimate calculation, every engine used in an underground mine is assumed to be equipped with this control technology. Under the stated reasonable conditions, an average DPM level of 90 µg/m3 (mass) is predicted as technically feasible.

Jan 1, 2002

By R. R. Klimpel

The use of froth flotation as a means of separating and upgrading sulfide mineral concentrates is standard industrial practice throughout the world. Froth flotation is also widely recognized to be a very complex system having highly interactive and often self-compensating factors at work. Several summary articles have been recently published which discuss at length some of the important practical aspects of optimizing the use of existing commercial flotation reagents. Klimpel (1987). Klimpel and Hansen (1987a), Klimpel and Hansen (1987b), and Klimpel (1988). It is apparent from monitoring the industrial practice of sulfide mineral flotation over the last decade that considerable progress has been made in optimizing the operating aspects of flotation. For example, the availability of improved instrumentation and related computer devices, modified mechanical flotation cell designs, better reagent dosage control leading to less reagent usage per ton of ore, blending of feed ores, more attention to coarse and fine particle flotations, etc., are all examples of this progress.

Jan 1, 1988

In the estimation of recoverable resources, geostatistical techniques such as Multiple Indicator Kriging require a change of support correction to derive theoretical recoveries based on an assumed level of mining selectivity. The change of support models most widely used in practice entail model based generalized corrections either on a global or local basis. Examples include the affine and indirect lognormal methods. Change of support corrections derived empirically through short-scale conditional simulation realizations often show notable differences compared with theoretical corrections determined using model variogram parameters. The existing changes of support models are reviewed and an alternative method is proposed.

Jan 1, 1999

By George B. Griswold

The two most stringent parameters for in place fracturing of rock are the lack of any initial void space in the rock which to expand into and the ability to gain access only through drill holes. These two restrictions have proven so severe that as of today the only proven techniques for efficient fracturing are the contained nuclear detonation and hydrofracing. Both of these methods have highly developed technologies for their application. Hydrofracing has been a standard oil field practice for two decades, and the experience gained from a couple hundred underground nuclear detonations has resulted in a thorough understanding of the phenomenology of cavity and chimney formation. What is still lacking is a practical method to create a suit- able degree of fracturing for those ore bodies which do not meet the application criteria for either the nuclear explosion or hydrofracing. Nuclear applications must be restricted to thick ore deposits so as to take advantage of chimney collapse height--preferable in excess of 200 feet thick. Other requirements such as ground shock, containment, and radioactive contamination further reduce the number of sites that prudently can be selected.

Jan 1, 1969

By M. E. Orman

Many factors must be considered when designing a heap leach pad. Geotechnical properties of the ore, can and will affect how well an ore leaches, the solution recovery, stability of the heap, and settlement. As a heap is stacked some of these properties will change due to the increased load. In order to properly design a heap these properties should be determined beforehand so that the heap performs as intended.

Jan 1, 1997

By R. M. Von Storch

Most coal mining areas of the Western United States are characterized either by thick beds, steep pitches or heavy cover. Individually, each of these may present inherent safety hazards that influence miring. When all are met at one location, the combined effect is to make the safe operation of the mining property a challenge to management. These combined, conditions are met in most coal mines in southeastern Utah including those of the United States Steel Corporation. This coal bed measures up to 16 feet in thickness, the pitch is as much as 25% and mining is under a cover approaching 2, 000 feet. The Sunnyside coal bed is found in the Book Cliff Mountains, a great escarpment extending from west of Castle Gate, Utah, some 180 miles to Grand Junction, Colorado. West of Green River, Utah, the Book Cliffs swing sharply to the north because of the domelike uplift of the San Rafael Swell to the southwest..It is in this northerly extension of the Book Cliffs that the Sunnyside coal in the Blackhawk Formation of the Mesa Verde Group, Upper Cretaceous Age is found. The strata are transected by numerous faults with from a few inches to as much as a hundred feet of displacement. All of these faults have had some effect on the mining operation, either in roof control or, in the case of major faulting, the pattern of mine development.

Jan 1, 1967

By Vincente M. Jr. Lim, Brain W. Lawrence

Underground mining operating costs consist pri¬marily of direct costs such as labor, supervision, ma¬terials, and supplies, plus indirect costs. The material and supply costs vary substantially between mines but commonly range from 35 to 60% of the total direct costs. As part of the preparation of accurate operating cost estimates for a project, information must be as¬sembled to select the material and supply items and to determine the quantities of these items that will be required. Cost data then can be incorporated with the estimated material and supply requirements to determine the total material and supply costs for the project. Estimated quantities will vary considerably between mining projects depending upon factors such as the type of material being mined, the mining method, the equip¬ment selected, drilling and blasting techniques, mucking and haulage methods, ground support requirements, number of men employed, etc. Valuable information often can be obtained from suppliers and manufacturers, including data on current operating practices for similar projects, recommenda¬tions for the specific project, and preliminary cost quota¬tions. However, quotations obtained for estimates are generally higher than the prices paid at the time of purchase. Mines operating in the area, or those mining under similar conditions, also can provide essential design information, but it often is difficult to obtain cost information from the operators. Estimated costs for the most common major items of underground materials and supplies are presented in the accompanying tables. They represent current costs or cost ranges and are intended to be used only as a guide when preparing budgetary estimates for materials and supplies. Cost data were obtained mainly from suppliers and manufacturers, with up to three quotations being ob¬tained for each item whenever possible. In most cases, as noted in the table footnotes, prices were based on quantities representing normal requirements for me¬dium-size mine operations. Every attempt was made to assure accuracy. However, the cost for most items, especially those with multiple sources, can deviate sig¬nificantly for various reasons such as geographical loca¬tion, current market conditions, quantities ordered, size of the customer (which could influence the ultimate quantities purchased), and the ability of the purchasing department. It is also for these reasons that the actual amount individual mines are now paying for specific items may vary from the estimated cost in the tables. The cost for specific sizes of items that do not appear in the tables often can be factored from the data pre¬sented. Costs for many items can be converted easily to a unit that sometimes is more basic, but not as com¬monly used, such as from a length to a weight unit. Other items not listed, such as repair parts for equip¬ment, will involve contact with suppliers to determine specific recommended requirements and to obtain costs for these items as related to each individual project. Costs are expressed in terms of US dollars as of 1978 unless otherwise specified. All measurements, sizes, and weights are expressed in conventional units (i.e. feet, inches, pounds) ; applicable metric conversion fac¬tors follow each table. Costs are represented for drill steel and bits; mining explosives; blasting caps; blasting supplies; ground sup¬port items; ventilation equipment; utility pipe, utility hose, and accessories; mine track and accessories; tires for underground equipment; lubricants and fuels; and miscellaneous supplies.

Jan 1, 1982

By B. Devulapalli

A mathematical model of the industrial hydrocyclone based on fluid dynamics is a better alternative to the currently existing empirical models. The swirling-flow velocities are determined by solving the Navier-Stokes equations with an appropriate turbulence model. The solution of the momentum-balance equations yields the flow field inside the hydrocyclone which determines the particle trajectories, and subsequently the classification curve. The essence of the model is that the physical dimensions of the hydrocyclone and the slurry characteristics can be incorporated, and the influence of these parameters reflects on the flow predictions. The predicted tangential and axial velocities in a 250-mm hydrocyclone are in good agreement with the laser-Doppler velocimetry measurements. Finally, the predicted classification curves show good agreement with experimental data measured on a KREBS Dl0B hydrocyclone.

Jan 1, 1993