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By John V. Beall

The Mining Engineering Handbook is written primarily for persons interested in the economic extraction of minerals. Not everyone referring to this book will be knowledgeable about mining and, therefore, this section is intended to explain to interested persons the scope of mining as well as fulfilling the title of "Mining's Place and Contribution" among the industries of society. 1.1-MINERALS, ROCKS AND ORE In the year 1971, the number of known elements amounted to 104. Fifteen of these have been made only in the laboratory, others may have persisted from the primitive atmosphere, but, by and large, elements originated from magmas or igneous rocks of the outer rocky shell of the earth. Only eight elements constitute 98% by weight of the earth's crust. These are oxygen, 47%; silicon. 28%; aluminum, 8%; iron, 5%; and sodium, magnesium, potassium and calcium, less than 4% each. These common elements and the other less common ones are the building blocks of minerals, of which there are over 2,000 varieties. According to Webster: "A mineral is an inorganic substance occul.ring natura!ly in the earth and having a consistent and distinctive set of physical properties and a composition that can be expressed by a chemical formula. The term is sometimes applied to organic substances, such as coal." Thus, minerals are precise combinations of elements. Rocks, as distinct from minerals, are composed of assemblages of minerals. When minerals are found in sufficient concentration to warrant extraction by mining, the mineralized area is considered an ore deposit. The definition of ore is mineral that can be extracted from the ground at a profit. The economic connotation is implicit in the word ore. Since most of the useful elements compose such a small percentage of the earth's crust, the occurrence of ore deposits as we know them would not have transpired had not geologic processes concentrated the elements (see Sec. 4). 1.2-DEFINITIONS OF MINING TERMS Extensive coverage of the many descriptive terms used in mining may be found in a good mining glossary, such as is available from the Superintendent of Documents (see Sec. 35), but for convenience a number of the more common definitions are given here. Mining may be defined, as by A. B. Cummins, as the act, process or work of extracting minerals or coal from their natural environment and transporting them to the point of processing or use. Mining techniques are applied to extracting metallic minerals, such as ores of gold, copper, lead or zinc; to fuels, such as coal, anthracite, lignite and tar sands; and to nonmetallic minerals, such as lime-

Jan 1, 1973

By Erik Marsh, Frederick C. Harris Jr., Javad Sattarvand, Joshua Dahl, Alireza Kamran Pishhesari

Based on the mine safety and health administration (MSHA)reports, mining truck accidents are among the significant causes of fatalities in the mining industry. The major causes of haulage accidents can be divided into non-driving and driving factors, such as truck-related sudden failures and operator performance. Numerous parameters affect trucks' safe operation, but situational awareness plays a significant role. Due to the distinct structure of mining trucks, making them efficient for mining purposes, the operator has a very limited field of view (FOV), making them prone to accidents resulting in losing lives. The cabin's position blocks the truck's right and rear sides, creating several blind points around it. Aiming to test/train the operator's awareness of the surrounding, a proximity detection system is developed through a multiplayer virtual reality (VR) application to investigate the human factor in equipment collisions. The operators were examined and monitored when asked to conduct what exactly happened in the Marigold mine truck accident without being aware of the scenario. After receiving sound, vibration, and visual alarm warnings, their reaction and performance were analyzed. The platform is developed using the Unity game engine for HTC VIVE virtual reality goggles. An Omni-direction treadmill and a motion simulator platform are utilized for the player and dump truck operators. Fifteen students were monitored when driving the dump truck receiving/not receiving proximity detection alarms. None of them repeated the accident when receiving proximity alarms. Also, they found the visual alarm the most comfortable while driving the truck.

Jun 25, 2023

By J. Smolensky, M. Paul

The Nordhalde is a waste rock pile resulting from uranium mining near Ronneburg, Germany. The pile contains over 27 million m3 of waste rock. Typical seepage water has a pH of 2.7 and a sulfate concentration of 10,000 mg/L. Geochemical investigations of the Nordhalde from 1993 to 1996 included drillholes, test pits, ABA and metals analyses, column tests, and a detailed review of the construction history of the pile. In 1996, eight drillholes were instrumented for monitoring oxygen and temperature. Monitoring continued for a fill year. Hourly temperature and pressure readings were taken by automated data recorder. Oxygen concentrations were measured three times per week, and periodic gas samples were obtained for complete analysis. The resulting data set is believed to be one of the most comprehensive of its kind. Effects noted elsewhere, such as thermal convection, are evident. However, unlike other data in the literature, the NordhaIde data shows a strong seasonal effect, with convection dominating oxygen transport only in the winter months. Analysis of the data allowed the amount of contaminants associated with ongoing and historical oxidation to be compared, and results were used to assess the potential effectiveness of proposed remediation measures.

Jan 1, 2000

By H. F. King

In 1982, the result of a 3-year study was published as "A Guide to the Understanding of Ore Reserve Estimation". The principal conclusions were that computation formed only part, and perhaps not the most important part, of an estimate and that the estimate should recognize that geological, mining engineering and metallurgical judgements formed an essential part of the eventual result. Subsequent expectation/realization studies of several mines have produced case histories which form the principal basis of the paper. These imply that geology is even a larger factor than thought earlier.

Jan 1, 1985

By Robert W. Lawson

INTRODUCTION The two basic types of mine-air compressors are the positive-displacement compressors and the dynamic compressors. Positive-displacement compressors con¬fine successive volumes of air within a closed space and increase the pressure by reducing the volume of that space. Reciprocating and rotary compressors operate on this principle. Dynamic compressors utilize an impeller to acceler¬ate the air, with the increased air velocity converted to pressure through a stationary diffuser. Centrifugal compressors and turbocompressors operate on this principle. Reciprocating Compressors Reciprocating compressors include both single-stage and multistage units. For mine service the most com¬mon is the two-stage intercooled compressor having an atmospheric pressure intake and a discharge pressure of 689 to 861 kPa (100 to 125 psi). The cylinders of a reciprocating compressor may be either single acting or double acting. In the single-acting cylinder, compression occurs on only one side of the piston, while, in double¬acting cylinders, compression occurs on both sides of the piston. Fig. 1 shows a cross-sectional view of a typical two-stage double-acting water-cooled reciprocat¬ing compressor. Fig. 2 illustrates the sequence of opera¬tions occurring in the cylinder of a reciprocating com¬pressor. Most modern mine compressors are double acting and are driven by electric motors. Induction motors are used on low-powered compressors, and synchronous motors are used on larger compressors. Steam-driven compressors once were common and still are applied where a reliable source of low-cost steam is available. For this type of compressor, steam is a desirable power source since a governor that senses the discharge pres¬sure can be used to control the steam inlet. This can be used to regulate the compressor speed to compress only air sufficient to meet the mine's requirements (up to the capacity of the unit). Unlike a constant-speed electric¬driven compressor, no other regulation is required for the cylinders of a steam-driven unit. Rotary Compressors Rotary compressors include sliding-vane, liquid¬piston, two-impeller straight-lobe or cycloidal, and helical-lobe units. Each of these has specific advantages and applications. Of these, the helical-lobe or "screw" compressor has the greatest application for supplying "100-lb air" [689 kPa (100 psi) ] to small- and medium¬size underground mines. Fig. 3 illustrates the operation of a sliding-vane compressor. Fig. 4 illustrates the operation of a helical lobe or screw compressor. Fig. 5 illustrates the operation of a two-impeller straight-lobe compressor. Fig. 6 illustrates the operation of a liquid¬piston compressor. Centrifugal Compressors Centrifugal compressors deliver 0.94 m3/s (2000 cfm) or more of air, and they are best suited to supply¬ing large volumes of compressed air for base loads. The efficiency of a centrifugal compressor declines rapidly when its operation deviates from its design point. If the power cost is not a critical consideration, a centrif¬ugal compressor is attractive as a result of the low initial and installation costs and the high degree of reliability. Fig. 7 illustrates a typical four-stage centrif¬ugal compressor, and Fig. 8 is a cross section of this type of unit. COMPRESSOR SELECTION The process of selecting a compressor requires sev¬eral considerations, including the capacity, the control system, the location, the power supply, and the cooling provisions. Compressor Capacity To determine the required capacity, the total air quantity and pressure requirements must be calculated. The air consumption of various tools, as listed in Table 1, must be included in this calculation. Some of the other considerations include: 1) The correction factor for altitude, as listed in Table 2, must be included in the calculation. While pneumatic tools require additional compressed air as the altitude increases, the compressor produces less. 2) A correction factor must be incorporated for the use of multiple tools. Table 3 lists appropriate correc¬tion factors for rock drills.

Jan 1, 1982

By J. A. Herbst

Fine coal cleaning by froth flotation has become common practice in the U.S. with more than 80,000 tons treated in this way per day. In spite of this large tonnage, developments in the automatic control of coal flotation circuits have lagged significantly behind those for mineral systems. One reason such developments have been limited is that instruments have not been available for the on-line measurement of carbon or ash and another critical variables in coal slurries. A second reason is that the influence of the operating variables on coal flotation has not been completely understood. During the last few years some of the required instrumentation has been developed and an improved knowledge of the flotation process itself has occurred through mathematical modeling; as a result certain control strategies for coal flotation are beginning to emerge. This paper attempts to evaluate several control strategies using a detailed flotation dynamic simulator, DYNAFLOAT. After constructing a process matrix for the system of interest, promising alternatives for linking manipulated and controlled variables have been analyzed. In order to develop combined grade and recovery control strategies, the authors found it necessary to construct a grade/recovery map with the aid of the simulator to drive the system to known final, feasible grade/recovery operating conditions. Finally, an advanced strategy which uses an on-line model to identify disturbances and take control actions is proposed.

Jan 1, 1983

By John A. Herbst

Flotation control systems in use around the world today owe their effectiveness to the coordinated use of appropriate sensors, control hardware, and decision-making strategies. This paper traces the development of these three main elements of the "control triangle" over time. Based on an analysis of recent developments, it is concluded that improvements occurring in instrumentation have basically been evolutionary, while advances in hardware and strategies have, in contrast, been revolutionary. An attempt is made to extrapolate developments in each of the "control triangle" elements into the future in order to make a projection concerning flotation control systems for the next millenium.

Jan 1, 1999

By J. W. Merks

Spreadsheet software is an effective tool for simulating dynamic stochastic systems such as mineral processing plants. The two-product formula is used to show how to set up a Monte Carlo simulation in a spreadsheet template and how to calculate variances of dependent variables. The key to a reliable and realistic simulation model is to obtain unbiased estimates for all independent variables and variances in the set that defines the stochastic system. Monte Carlo simulation is also a powerful tool for optimizing sampling procedures, for applying sensitivity analysis and for designing and evaluating experiments.

Jan 1, 2000

By Bahaa Alyosif, Murat Erdemoğlu, Muhammet Kürşat Aydemir, Turan Uysal

The effect of intensive milling on the conversion of microcline ( KAlSi3O8) to potassium chloride (KCl) occurred during the chlorination roasting process for artificial KCl production was investigated. A feldspar ore with 10.89% K2O grade and containing microcline was dry milled by a planetary ball mill for mechanical activation. Milled ore mixed with calcium chloride was roasted at temperatures between 500 and 1000 °C to get the chlorination roasting process. The product was then leached in water to dissolve KCl occurring during the roasting, which will be precipitated from the pregnant leach solution by evaporation. Results showed that potassium recovery from the unmilled ore increased rapidly up to 800 °C, and dramatically decreased at higher temperatures due to the removal of KCl from the furnace by means of evaporation. A potassium recovery of 31.95% was achieved by the unmilled ore, whereas it was 88.43% when 15 min milled ore was roasted at 750 °C. It was concluded that intensive milling caused mechanical activation of microcline to reduce the roasting temperature of the chlorination roasting process.

May 31, 2023

By A. Kalogeropoulos, T. Michalakopoulos

The DEM has been used in several studies to numerically simulate the response of rocks to the cutting action with drag tools. In this research, the aim is to realistically simulate the rock material and the cutting process by controlling the grain interlocking of the numerical assembly and streamlining the calibration process while focusing on the cutting force and the failure mechanism.

Apr 1, 2023

By Pengfei Wang, Guorui Feng

"With the depletion of easily minable coal seams, less favorable reserves under adverse conditions have to be mined out to meet the market demand. Due to several historical reasons, a large amount of remnant coal was left unrecovered. One such case history occurs with the remnant rectangular stripe coal pillars using partial extraction method at Guandi Coal Mine, Shanxi Province, China. The challenge that the coal mine is facing is that there is an ultra-close coal seam right under it, with an only 0.8 to 1.5 m sandstone dirt band in between the two. The simulation study was carried out to investigate the simultaneous recovery of upper remnant coal pillars while mining the ultra-close lower panel using longwall top coal caving (LTCC). The remnant coal pillar was induced to cave in as top coal in LTCC system. Physical modelling shows that the coal pillars are the abutments of the stress arch structure formed within the overburden strata. The stability of overhanging roof strata highly depends on the stability of the remnant coal pillars. The gob development (roof strata cave-in) is intermittent with the cave-in of these coal pillars and the sandstone dirt band. FLAC3D numerical modelling shows that the multiple seam interaction has a significant influence on mining-induced stress environment for mining of lower panel. The pattern of the stress evolution on the coal pillars with the advance of the lower working face was found. This demonstrates that the stress relief of a remnant coal pillar enhances the caveability of the pillars and sandstone dirt band below them.INTRODUCTIONChina is one of the world’s coal-rich countries. Coal has played a significant role in the growth of China’s economy. Coal reserves have been mined commercially in China for over one hundred years. The demand for coal in China is still going to grow at a relatively high rate (BP Energy Outlook, 2019). Long-term large-scale and intensive coal mining activities have created tension between increased demand and limited resources (Bai et al., 2018). Easily minable coal seams such as sub-horizontal, tabular, and laterally extensive coal seams are being depleted, and therefore the remaining reserves are becoming less favorable. However, in many situations, the coal reserves under adverse conditions have to be mined out to meet the market demand for energy.Due to sedimentary environments and geological conditions, many coal seams are interspersed with sedimentary bands, or partings both within an individual seam and between seams. These bands and partings lead to appearance of ultra-close coal seams, as well as giving rise to considerable variation in their structural and mechanical properties (Ghabraie and Ren, 2016). Difficulties are encountered in the mining of such coal seams. If ultra-close coal seams are mined sequentially, that requires the design of a mining system for each individual coal seam; also, a large number of gateroads have to be excavated, which is not a high-efficiency option. If ultra-close coal seams are mined at a great mining height at once, for instance, using longwall top coal caving—a longwall mining method that is widely used in China for the mining of ultra-thick coal seams—then the location and characteristics of the band would have a significant influence on success of their extraction."

Jan 1, 2019

By W. J. Kennedy

Energy management in industry has recently achieved notice as a way to reduce costs without decreasing production. The same approach used in industry can be used in mining, even though the processes are different. This approach is based upon a three phase system of data collection, implementation, and monitoring, all aimed at gathering and evaluating information in such a way as to have a maximum impact on energy costs. This approach has these advantages: (1) attention is directed toward the part of each mining system where the most energy is used, (2) input is collected systematically from all persons involved in the operation of each system, and (3) a means of monitoring the progress toward established goals is created. The mining systems considered are truck haulage, conveyor haulage, blasting and crushing, and lighting. After describing the general procedure, the authors have described a specific method for improving the efficiency (and hence the energy consumption) of round-trip truck haul age systems.

Jan 1, 1982

By G. D. Hood

The U.S. Bureau of Mines investigated rapid froth flotation through the use of more efficient bubble-particle collisions that improved the overall flotation kinetics. An in-line static mixer efficiently mixed the air bubbles, water, and ore, rapidly attaching the hydrophobic mineral to the bubble surface. As the mixture entered the flotation chamber, the hydrophobic mineral was already attached to the bubbles and was quickly floated away from the remaining ore pulp. A rougher concentrate containing 4.5 pct copper was obtained from a western porphyry copper ore containing 0.67 pct copper. Over 99 pct copper was recovered from the ore at a rate 7 times faster than conventional flotation.

Jan 1, 1991

By J. P. P. Silva

Sodium silicate (water glass) is a modifier reagent widely used in flotation with the function of a depressant or dispersant. The interaction between sodium silicate and mineral surfaces is still not well understood. This investigation aimed to illuminate the sodium silicate action mechanism as a depressant in the flotation of the minerals quartz and calcite. The experiments were done with high-purity mineral samples in the particle size range below 147 µm. The microflotation tests in a modified Hallimond tube showed that, in all systems tested, the efficiency of sodium silicate increased with the concentration. At concentrations above 1,500 g/t, almost total depression (96% for calcite and 97% for quartz) was achieved. The variation of sodium silicate modulus did not alter the quartz flotation performance in the presence of amine (150 g/t). The most efficient depression pH range was observed between 5 and 8. Above pH 10, the depressant action of sodium silicate was negligible. The infrared spectra obtained at pH 7 after silicate contact showed the presence of the groups OH and Si-OH, both suggesting that the adsorption of the neutral species Si(OH)4, as well as siloxane groups (Si-O-Si), attributed to adsorption of polymeric species. Sharing electron pairs is the proposed adsorption mechanism between Si(OH)4 and polymeric species and the surface sites (Si-O on quartz and Ca-O on calcite). At pH 11, the electrostatic repulsion prevents the species adsorption, impairing the sodium silicate action.

By Brian E. McGee

The Federal Coal Management Program represents the culmination of several years of effort by the Department of the Interior (001) to reformulate the manner in which coal owned by the United States is leased and developed. These efforts began in 1970 with a study by the Bureau of Land Management (BLM), which indicated that unless drastic changes were made in. the federal coal leasing procedures, federal coal lands would be leased almost for the asking while production of coal from those lands had been decreasing. Consequently, informal action was taken in 1971, which resulted in no further leasing being authorized until February, 1973. At that time, a formal moratorium on most coal leasing was established, with exceptions granted only for leases needed to satisfy short-term needs such as maintaining existing mines or supplying reserves for new contracts in the immediate future. This leasing policy embodied a long term objective of developing an entirely new planning system for federal coal leasing, as well as to schedule the preparation of a programmatic impact statement for this new system. As a result of the 1973 moratorium and the ensuing application of short-term criteria, only 10 federal coal leases (covering approximately 30,177 acres) were issued from February, 1973, through January l, 1976.

Jan 1, 1982

By ERIK CHARRIER, ADITYA JUGANDA, Jürgen Brune, Patrick Maier, Gregory E. Bogin Jr

Confined explosions are a major risk in underground coal mine operations. Depending on confinement, ignition location and obstacles in the flame path, methane explosions can transition to detonations. As a result, the severity of mine explosions ranges from minor damage to loss of lives and permanent mine closure. Experimental results have shown that the inclusion of obstacles can significantly increase the flame propagation velocity by inducing turbulence. This research focuses on explosion experiments in a 71 cm diameter, 30.5 m long reactor that includes rock piles as obstacles along with developing the corresponding CFD model that captures the observed flame behavior and interaction with the obstacles. The rock rubble increases the flame front propagation velocity by 500% compared to the maximum velocity observed in the empty reactor experiments. The 2D and 3D CFD models predict the experimental flame front propagation velocity, whereas the 3D model shows a more explicit conformity than the 2D model. Although the computational time to complete the simulation is much less for the 2D model than for the 3D model, the 2D model is not sufficient to simulate cases with rock rubble since it cannot capture the propagation of the flame through the small voids between the rocks with the same effective blockage ratio as the 3D model. The validated CFD model can be scaled up to simulate methane explosions in full scale mine and industrial settings.

Nov 20, 2023

By D. Zim

Mining activity in South America is a growing enterprise. One of difficulties found in many areas of the South American continent, especially in north Chile and south Peru, is the shortage of water supply. In order to overcome this difficulty some mining companies proposed to transport the water from Pacific Ocean up to the mountains. This can be accomplished by the use of stainless steel pipelines, but this is a cost prohibitive solution and is also subject to severe pitting corrosion in a saline environment. The use of mild steel may be a lower cost solution than stainless steel as the material of construction for pipelines but it is subject to corrosion anyway. The corrosion in this case can be internal or external corrosion although cathodic protection as well preventive maintenance usually is enough to mitigate external corrosion without the need to shut down the pipeline. The same is not true about the prevention of internal corrosion. It is not practical, sometimes not even possible, shutdown a pipeline to carry out an inspection and fix sections where potential failures are detected. It is possible avoid corrosion caused by sea water within the mild steel pipelines by applying a proper chemical program designed to virtually eliminate dissolved oxygen in the water commonly called deaeration.1 This type of treatment obviously involves additional capital investment since it requires the construction of one deaerator with the first pumping station and additional equipment at each point where the water can come into contact with oxygen. Deaerators will increase operational costs and subsequent injection of chemicals will be required in the case of multiple degasification facilities thus increasing the consumption of chemicals. grams based on oxygen scavengers, the objective of the present study is to develop a new water treatment capable of preventing mild steel corrosion in aerated sea water. The new treatment must be able to prevent both generalized and localized (pitting) corrosion and overcome the necessity to construct and operate deaerators.

Feb 23, 2014

By E. K. Albert

Computer oriented simulation techniques can be effective in the design and analysis of complex mining systems. In fact, a number of computer software products are available for mine systems simulation. While providing a useful tool for the investigation of mine planning problems, the availability of graphic output was limited or non-existent. Computer graphics is a natural extension of mine simulation methods and provides a more dramatic level of understanding and interface with an engineer. With today's high cost of venture development, the need for an easy to use but complete systems model which includes the major elements of mine planning with an interactive graphics interface has never been more apparent. In this paper, the underlying philosophy of design of an interactive interface to a complete surface mining simulation model is described. The basic structures of the surface mining system and the simulation model are discussed. The methods and algorithms used to implement the various subsystems are presented. Practical considerations of the design of displays and user interaction are illustrated, especially as they apply to the application of the package by a mining engineer. A simple example is provided to demonstrate the concepts embodied in the model and to show how a simulation is built from mine data.

Jan 1, 1984

By Elham Najafi, Sina Ghassa, Ata Akcil, Hadi Abdollahi, Sandeep Panda, Zohreh Boroumand

The present study investigates the influence of ferrous iron (as FeSO4) and ferric iron (as Fe2 (SO4)3), and pyrite (FeS2) on the ability of bacterial leaching of a high-grade sulfide Zn–Pb ore. In this regard, shake flask experiments were carried out at 5% (w/v) pulp density of the ore sample (having 40.7% Zn and 12.4% Pb initial metal content) using a consortium of mesophilic iron and sulfur-oxidizing acidophiles. A concentration of 0.04 mol/L of ferric iron in the leaching media was found to be optimum for zinc extraction without affecting growth of the microorganisms. Under this concentration, the dissolution of Zn, Pb, Cd, and As was found to be 57%, 0.2%, 0.03%, and 9.9% in 25 days. Using ferrous iron in the media, 0.16 mol/L of Fe2+ was found to be the optimum concentration for efficient bacterial growth and metal dissolution (54.6% Zn, 0.08% Pb, 0.03% Cd, and 10.2% As) from the sample in 25 days. On the other hand, using pyrite as the source of energy for bacterial growth, an initial 12-day lag period was observed when compared to the effect of ferrous iron in the media. Under the optimum concentration (test with 0.24 mol/L iron in the form of pyrite), the dissolution of Zn, Pb, Cd, and As was found to be 39.8%, 0.1%, 0.03%, and 10% in 25 days. The surface chemistry analysis indicated formation of a sulfur layer over the particle surface that hindered reagent diffusion and affected metal recovery through bioleaching.

By P. Verhoeven, G. Hefter, P. M. May

The dissociation (ionisation) constant of hydrogen cyanide, pKa(HCN), has been measured by high precision glass electrode potentiometric titrations in saline solutions containing up to 5 mol/L sodium chloride. The dissociation constant of water that is necessary for the calculation of pKa(HCN) has also been measured. In saline solution, and in contrast to literature values, pKa(HCN) changes considerably at both high and low ionic strengths as a result of changes in activity coefficients. In addition an equation is presented, using literature data, that describes the variation of pKa(HCN) with temperature up to 150°C. The significance of the changes in pKa(HCN) for optimising the pH of alkaline cyanide gold recovery streams is briefly discussed.

Jan 1, 1991