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By John L. Burnett

Field criteria are needed to help the prospector recognize a potentially expansible shale, clay, or slate. Certain criteria have proven useful in California even though the physical-chemical mechanisms of expansion are not thoroughly understood. Three conditions must be satisfied before expansion can take place, The raw material must partially fuse at a low temperature (1800-2000°F.), Concurrently a gas must form. The raw material must be sufficiently impermeable to trap the gas within the particle. Low temperature melting, which is controlled by bulk chemical composition, is difficult to assess in the field but most common shale, clay, and slate is suitable in this respect, The presence of organic carbon, the most common source of an expanding gas, is indicated by dark color of the rock, A large proportion of clay-sized particles promotes impermeability; fine grain-size is indicated by conchoidal fracture, The shape of the expanded particle is commonly indicated by the texture of the raw material. Rocks with well-developed slatey cleavage produce accordion-shaped particles; massive rocks tend to form rounded particles. Undesirable materials commonly present with expansible shale include: weathered shale; sandstone and other coarse-grained sediments; and limestone, Weathering, which is indicated by color, reduces or eliminates expansion; therefore, surface samples seldom are representative of the shale found at depth. Sandstone does not expand and will increase the average weight of the finished product, Limestone or particles of carbonate minerals can be actively harmful because they are converted to free lime (CaO) during the firing process, If free lime is present in concrete, hydration will cause expansion of the lime particles which result in surficial ?popouts.?

Jan 1, 1963

By Paul Nicholas, Raju Gottumukkala

"India’s economy is expanding with rapid urbanization. Improvement in infrastructure is a keystone to the Indian government’s economic plans, including expansion of transit systems. Most of these systems are designed with elevated and underground sections. New Delhi, a city of 23 million people, suffers from heavy traffic congestion and pollution. The transit (metro) system is seen to be of critical importance. Phase 3 of the Delhi transit system project is 140 kilometers (km), with 40 km of twin-bore tunnels requiring 35 tunnel boring machines (TBMs) for construction. Transit systems are also under design or construction in Chennai, Bangalore, Kolkata, Hyderabad, Jaipur and Mumbai. Most have twin-bore tunnels. At present, 55 TBMs are operating on underground metro construction, and future projects will increase this number. This paper highlights the unique challenges of construction of underground metro systems in highly congested urban environments, using Kolkata and Delhi systems as examples. INTRODUCTION The first transit system in India was constructed in Kolkata (India’s third-largest city by population.) This line is 28 kilometers (km) in length, has underground and at-grade sections, was built in phases, runs north/south, and has 24 stations. This project was sanctioned in 1972, started construction in 1984, and was completed in 1995. The tunnels were constructed primarily by cut and cover methods with some open-face, compressed air shield tunneling. In 2006, the urban transport policy recommended construction of transit rail systems in all urban cities with a population exceeding 2 million. Further, in 2014 the central government stated that it would assist in financing transit systems in all cities with a population of over 1 million. In 2015, the central government approved the development of transit systems in 50 additional cities across India with a budget of $75 billion (see Figure 1). Transit development is just part of a huge expansion in planned rapid transport systems, which include metro, bus, high-speed rail, and monorail systems. Metro systems will include elevated and underground sections with twin-bore tunnels and underground stations. In the Delhi/National Capital Region (NCR), now the largest city in India by population, Delhi Metro Rail Corp (DMRC) was formed in 1995 as a joint venture company between the central government and Delhi state. DMRC operates the Delhi metro system. (see the case studies described later in this paper). DMRC has developed an external function to carry out studies and to offer consultancy to other cities planning transits. Since its inception, DMRC has produced Detailed Project Reports (DPRs) for every metro and monorail project in India. In 2012, DMRC became a partner in the management consultancy for Jakarta Mass Rapid Transit System, its first project overseas. DMRC became a model organization for other cities to follow. These cities have included Chennai, Hyderabad, Kolkata, Bangalore, Jaipur, Mumbai, Ahmedabad, and Nagpur. Other cities (e.g., Lucknow and Patna) are in the metro planning phase. Metro systems are under construction or partially operating in Hyderabad, Bangalore, and Jaipur."

Jan 1, 2016

By J. Espí

The mineral price assigned in mining project design is critical to determining the economic feasibility of a project. Nevertheless, although it is not difficult to find literature about market metal prices, it is much more complicated to achieve a specific methodology for calculating the value or which justifications are appropriate to include. This study presents an analysis of various methods for selecting metal prices and investigates the mechanisms and motives underlying price selections. The results describe various attitudes adopted by the designers of mining investment projects, and how the price can be determined not just by means of forecasting but also by consideration of other relevant parameters.

Aug 1, 2013

By V

"Recent regulations, as well as a general aversion to central dust collectors within the Powder River Basin Coal user’s community, have created a need for an alternate method for eliminating airborne dust. This paper addresses the capital expenditure as well as the cost of ownership of an integrated point source air cleaning system in comparison to a central collection system. This assessment was conducted by comparing the cost to purchase and operate a central dust collection system and integrated air cleaner system on a typical multiple transfer point application. The central dust collector consists of a negative pressure blower, a series of filter bags, a collection hopper, a screw conveyor to place collected material back into the material stream, and a series of ducts to pull air and dust from individual pickup points. The point specific integrated air cleaners consists of a negative pressure blower to pull dust and air from an application point through a bag-less filter media located at the application point. The agglomerated material is then redeposited into the material stream at point of use without the need for ducting or a central material hopper. The assessment yielded a 54% reduction in capital expenditure and a 26% reduction in operating costs for the same application when using individual dust filters as opposed to a central system. In addition to the lowered cost, there are reductions in risk associated with the elimination of ductwork and the central containment enclosure for collected explosive dust. By the conclusion of this paper, the reader will have a better understanding of the quantifiable differences between a central dust collection system and a set integrated air cleaner systems. BACKGROUND Spillage has always been a problem in the bulk solids handling industry. As long as there have been conveyors, there has been spillage. Spillage is material that falls off a conveyor belt and creates a hazard in the environment around a conveyor belt."

Jan 1, 2016

By S. B. Patton

To fully utilize a ventilation simulator as a planning and production tool, the network database must keep pace with mining progress. By using AutoCAD's attribute-definition function, the branch data and node coordinates can be stored as part of the branch-diagram file, and updated with the drawing. Attributes are drawing entities that contain text which can be extracted in a standard spreadsheet format or as an ASCII text file. The data can be subsequently loaded into a ventilation simulator with plotting capabilities, such as VNETPC. This paper presents the methodology for using AutoCAD's attribute feature in a ventilation simulation.

Jan 1, 1994

By Hesam Dehghani, Farid Alimohammadnia, Nima Babanouri, Mokhtar Kalhori

In open-pit mining, blasting pattern design is performed to achieve a desired degree of fragmentation for loading, hauling, and crushing operations. Inappropriate fragmentation of rock will result in numerous problems such as incurring extra costs for secondary blasting, production interruption, etc. Wetness of the blast holes is one of the most important factors, which can cause the inappropriate rock fragmentation. Lowering ambient temperature in the vicinity of the explosion, the presence of water in the hole adversely affects the quality of the explosive while dissipating part of the explosion energy, ending up with inappropriate fragmentation problems. In the present research, in order to study blast-induced fragmentation conditions in Baba-Ali Iron Ore Mine, three scenarios were considered: explosion of ammonium nitrate with fuel oil (ANFO) in dry hole, explosion of ANFO in wet hole, and explosion of the emulsion in wet hole. For this purpose LS-DYNA, a numerical simulation code was used. Results of the present research showed that, compared to the explosion of ANFO in wet hole, the explosion of the emulsion produced more uniform distribution of fragment size, while the explosion of ANFO in dry hole resulted in fewer large fragments.

By James B. Meredith

The European Economic Community (The Common Market) is now shifting from I a coal oriented to an oil oriented economy. The proportion of energy supplied by oil has increased from only 13% in 1950 to 38% in 1962, and will approach 50% by 1970. In the past five years Common Market petroleum demand has in- creased 15% per year compared with only 3% per year in the United States. This rapid shift to oil can be explained by looking at oil's competition, First; there is simply not enough other energy - European coal, natural gas and hydro-electric power - to meet the demand, Secondly, oil?s primary competing energy in the Common Market is coal, and Community coal is high-priced - it costs more than two and a half times as much as U. S, coal at the pithead. The third reason for the shift to oil is consumer preference for the ease of handling, convenience and cleanliness of liquid fuels. As these reasons suggest, much of the shift to oil and the resulting growth in demand would have occurred whether or not the Common Market organization had existed. On the other hand, the Common Market has stimulated the use of oil by causing a higher rate of energy consumption, and oil has been the beneficiary of most of this growth.

Jan 1, 1963

In recent years, Computational Fluid Dynamics, CFD, has been commonly utilized in the mining industry to model the fluid flow behavior in underground mine workings. This paper uses CFD modeling to simulate the airflow behavior in underground crosscut regions, where brattice sails are used to direct the airflow into these regions. Brattice sails are cost effective ventilation control devices for temporary or permanent use in underground mining. They can be used to deflect air into the unventilated areas such as crosscut regions. Their design and installation is a fundamental issue for maintaining a sufficient supply of fresh air and achieving effective air circulation and contaminant removal. At the same time, they should have little impact on the mine ventilation system. This paper presents the results of a two-dimensional CFD model, which examines the effects of brattice length on fluid flow behavior in the crosscut regions. The results of this study will assist in understanding the ventilation air behavior and in determining the optimum size of brattice curtain (sails), which provide a highly effective contaminant removal from the unventilated mine areas. This, in turn, helps the mine ventilation designers to meet the mine safety requirements.

Jan 1, 2009

By Joseph Kuti

Longwall mining is the term used for the underground extraction of a wide and deep panel of coal. Such a panel may be blocked out by one or more entries on either side ("head" and "tail") of a longwall face. If all the entries are pre-driven, the panel extraction is termed longwall retreat mining. With one exception, all the longwall faces in the United States are of this type. (1) prior to the general decline in the rates of production with Continuous Miners, the development of the multiple entries generally kept ahead of the longwall extraction rate. This is no longer the case: longwall extraction rates far exceed the rate of development. In addition to this problem, in newly established mines, the development of a haulage and bleeder system based on multiple entries results in a lead-time of three years or more before longwall mining can be applied. This is one reason why earlier projections and much of the optimism attached to longwall mining as a principal "savior" in the energy crisis should be viewed with some caution.

Jan 1, 1978

By T. F. Dumm

With increasing interest in the physical cleaning of fine coal, there is a need for extension of the sink-float analysis procedure to finer sizes. Problems arise, however, in ensuring complete dispersion of the particles in the heavy liquids. A procedure has been developed in which surfactants are used as dispersing agents and solids concentration is minimized (using a simple formula to estimate the minimum weight needed for statistical reliability). Using centrifuges to increase separation rates and sub-sieve particle size analysis of the specific gravity fractions, a complete size-specific gravity distribution can be obtained. Analyses have been performed on coal samples as fine as -10 µm.

Jan 1, 1987

By G. V. Henderson

Large reserves of high calcium limestone have been outlined in the Redwall formation at Nelson, Arizona. Geologic mapping, core drilling and shallow seismic refraction studies have outlined more than 100 million tons of high quality, chemical and metallurgical grade limestone in the Mooney Falls member of the Mississippian Redwall Limestone. Well developed Karst zones in the Redwall were delineated by field mapping, seismic profiling and core drilling. Development of large reserves of high quality, thick beds of limestone near the present mine and rail facilities was the basis for the current mine and plant expansion. When completed in 1978 the planned 1800 Tpd production will represent the largest lime operation in the Western United States.

Jan 1, 1978

By T. W. Eddy

Research was conducted in which elemental mercury and its sulfide mineral (cinnabar) are removed from a copper sulfide concentrate by low temperature thermal applications. The goal of this research was to reduce, volatilize, and collect mercury vapor from concentrated smelter feed in a simulated drying environment while maintaining the chemical integrity of the residual. The study used synthesized concentrates composed of copper sulfide and mercury bearing minerals (such as cinnabar (HgS) or elemental mercury) to determine optimal residence times and temperature ranges.

Jan 1, 1996

By S. Kemball-Cook, D. Heinze, A. Kornberg, M. Harmon

Climate change presents risks to mine infrastructure, operations and long-term obligations to protect environmental conditions. Management strategies and design of infrastructure and containment systems based on past or current climate conditions may be inadequate in the future if changes in climate are not taken into account in planning for mine operations, decommissioning, closure and post-closure. Data-driven assessments using climate model projections of the future can be used to quantify: • Changes in site-specific risks to mine structures, access, containment facilities, operations and staff safety. • Changes in vegetation and water balance/chemistry, and potential for acid mine drainage, erosion and design failure. Climate- and weather-related risks are a serious threat to the mining industry, but risk transfer solutions can alleviate these vulnerabilities. Mining companies can protect themselves through bespoke solutions which provide operators, investors and buyers with protection against weather-related disruptions to operations by hedging to smooth revenues. Using risk transfer structures to mitigate climate risks is a mechanism that is available to all types of mining operations world-wide. In this paper, we describe methods for evaluating site-specific climate change impacts and developing risk transfer solutions to mitigate their effects. EVALUATING MINE RISKS FROM CLIMATE CHANGE The best available tool for understanding potential future changes to the earth’s climate system are global climate models (GCMs) (IPCC, 2014). GCMs are computer simulations of the climate system which include the atmosphere, ocean, land surface, cryosphere and biosphere. Because of the computational demands of running a global model for many decades, the spatial resolutions of the GCM grids are necessarily coarse, typically on the order of 100-300 km. GCM data are therefore suitable for evaluating future physical risks on global or continental scales, but may not be appropriate for evaluating location-specific risks (e.g. Kotamarthi et al., 2016). For site-specific, quantitative physical risk assessment, GCM projection data are “downscaled” or adapted for use at the local level using statistical techniques together with observed data (statistical downscaling) or using high-resolution regional climate models (RCMs) that focus on a single geographic region and have spatial resolutions of 10-50 km (dynamical downscaling). Downscaling bridges the gap between the GCM scale and regional/local scale. Through the downscaling process, new information is added to the GCM output from observations and/or RCMs, resulting in patterns for weather variables that are more consistent with local terrain and weather influences. Downscaled climate change projections for the mine site are selected considering mine location and geography, the availability of local observations, and the performance of the downscaling method and global/regional models used to develop the projection in simulating the variable under study. Where possible, we use projections from an ensemble of global and regional model runs spanning a range of future greenhouse gas (GHG) scenarios.

Jan 1, 2019

By Charles A. Hickey

The dining industry game tome Spruce Pine area a few years after tine Civil War. Two Yankees came down from Massachusetts to mine sheet mica to sell to the stove manufacturers for windows in heating stoves. At this time the method of mining was very crude; it was done only with pick and shovel. They were mining mica from the soft veins. Later they progressed to hand grilling and blasting. Hand drilling was quite an art in the area. One man would hold and turn the steel while one or two other men would drive the steel with hammers. In shaft raining, the muck and water was removed by hand winches called windlasses. About 1920 air compressors and jack hammers came into use. These were perhaps tide greatest improvement that has ever come to the area's mining industry. Later carne gasoline hoists, air drive water pumps, and all electrical equipment. Mica mining has, for the past few years, been very modern and efficient.

Jan 1, 1962

By Manoj Khandelwal, Jian Zhou, Yingui Qiu, Peixi Yang, Pingan Peng

Rockburst prediction is crucial in deep hard rock mines and tunnels to make safer working conditions. Due to the complex interaction of many factors involved in rockburst prediction, such as multi-variable and multi-interference factors, three hybrid support vector machine (SVM) models optimized by particle swarm optimization (PSO), Harris hawk optimization (HHO), and moth flame optimization (MFO) are proposed to predict rockburst hazard level (RHL). The RHL is determined according to four kinds of microseismic characteristic parameters including angular frequency ratio, total energy, apparent stress, and convexity radius. Then, six types of microseismic characteristic parameters are taken as input variables in 343 sets of data, including angular frequency ratio and total energy, etc.. And the RHL is taken as the output target of rockburst prediction. The classification performance of PSO-SVM, HHO-SVM, and MFO-SVM hybrid models is evaluated by accuracy (ACC), precision (PRE), and kappa coefficient. Findings reveal that the MFO-SVM model performs best in terms of accuracy, with ACC, PRE, and kappa coefficients reaching 0.9559, 0.9063, and 0.9094 respectively, while PSO-SVM and HHO-SVM have similar performances. However, the PSO-SVM, HHO-SVM, and MFO-SVM all perform better than the unoptimized SVM model. This confirms that the three optimization algorithms significantly enhance the rockburst prediction capacity of the SVM model to help mine practitioners apply machine learning methods to rockburst prediction problems appropriately.

Feb 3, 2023

By T. B. Jarboe

The 150 MWe circulating fluidized bed (CFB) power plant described in this paper is the product of recent Bechtel experience in the industrial power and steam market, where the economic feasibility of fluidized bed projects has been proven. The inherent ability of CFB boilers to burn low grade fuels makes it possible to also burn low ranking coals or coal wastes, including anthracite culm, coal mine rejects, and coal wash plant waste slurry. The impact of fuel characteristics on plant design is addressed. This includes solids handling, steam generation, sulfur capture, and auxiliary load requirements.

Jan 1, 1988

This paper reports on the behavior of mercury and its compounds during the thiosulfate leaching and recovery of gold. Thiosulfate solutions are shown to dissolve Hg0 and Hg2Cl2 to a similar extent as cyanide, but the leaching of HgS is significantly slower in thiosulfate solutions compared to cyanide. Hence, the use of thiosulfate may be an option for treating ores containing high levels of cinnabar, especially since the legislation concerning the discharge or sale of mercury is becoming more restrictive. The deportment of mercury during gold thiosulfate loading and recovery using a strongly basic anion-exchange resin was also studied. Although the mercury thiosulfate complex loads on the resin, the adsorption is weaker than for gold, with an equilibrium constant between gold and mercury of 51. Resin loaded with gold, mercury and copper was pre-eluted with thiosulfate (to remove copper) and eluted with a chloride and sulfite eluant. The majority of the mercury is eluted by the eluant and, hence, its deportment closely follows gold and the eluate would need to be treated to remove either mercury dur-ing or prior to gold electrowinning.

Jan 1, 2010

By M. G. Eiselein, R. A. Smith, C. H. Sheerin

FMC Gold's Paradise Peak Mine was one of the top two producers of mercury metal in North America in 1988 and 1989. As a by-product, elemental mercury is produced from cyanide soluble mercury minerals, primarily to reduce the health risks incurred with the refining of precious metal precipitate containing elemental mercury and mercury amalgams. A discussion of the design, primarily the Merrill-Crowe units, and permitting for the safe production of mercury will be presented. Additionally, laboratory testwork to determine the effect of mercury on reagent requirements in the Merrill-Crowe process will be discussed.

Jan 1, 1990

By Ricardo Oliveira Gallart de Menezes, Claudio Gerheim Porto, Reiner Neumann

This study presents the results of the mineralogical characterization of Ti-Zr ore from the Jiboia deposit, located in the municipality of Brejo Grande, Sergipe State, Brazil. The goal is to identify the main Ti, Zr, and REE carrier phases in the different particle size fractions in order to subsidize the development of a cost-effective processing route for the production of heavy minerals concentrate. The mineral resources are estimated at 31.5Mt @ 3.5% of total heavy minerals (THM) for the Jiboia Ti-Zr deposit, of which 5 Mt @ 3.39% THM were classified as measured and indicated. The mineralogy of the heavy mineral concentrate recalculated to 100% is represented by 22% pseudorutile, 20% ilmenite, 15% zircon, 5% rutile, 2% monazite, and 36% gangue. The ore minerals are preferably concentrated in the 150 × 53-μm granulometric fractions, which represents 80% of the THM and only 27% of the ROM (Run-of-Mine) ore. Therefore, by cutting the ore to 150 μm, it is possible to discard 73% of the ROM mass and recover 80% of the THM, including 100% of the zircon and monazite which are the most valuable minerals present in the heavy mineral concentrate. The global recovery of THM starts to decline rapidly in the fractions finer than 106 μm and the mass disposal (tailing) does not follow in the same proportion. Higher zircon contents in the concentrates of the fractions finer than 150 μm imply a significantly lower recovery of heavy minerals like ilmenite, pseudorutile, and rutile that make the fractions coarser than 150 μm.

Jan 9, 2024

By S. S. Szoke

The concrete masonry industry, represented by the National Concrete Masonry Association has significantly expanded its markets since the industry's inception. The concrete masonry industry has developed and refined concrete masonry units by producing a variety of quality products on automated machines. In the sixties, architectural concrete masonry units gained popularity. In the seventies, the concrete paver market expanded. In the eighties, segmental retaining wall units became popular. The industry continues to research and develop new products and applications for concrete masonry to satisfy the needs of designers, specifiers, installers and owners. Both existing and innovative technologies in the concrete masonry industry are discussed.

Jan 1, 1993