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By W. C. Lacy

It is the responsibility of educators to look ahead and prepare young engineers and scientists to cope with industrial and social problems of the future. We are faced with a review of history as well as prophesy of the future. The mining industry exists in a "bubble" with little interaction or communication with the outside. This isolation must be broken down if the industry is to survive in the U.S. and Canada. The ability to communicate with the general public and public officials is essential. Many changes are occurring that will require readjustments in technology and staffing. Aging population will result in raising retirement and increasing available workforce. This may force shorter working weeks to supply additional jobs. Environmental concerns will likely direct more attention not only to these concerns during mining, but to planning for post-mining land usage. Retraining and up-dating educational programs are required to cope with these changes.

Jan 1, 1994

By J. C. Squire, E. W. Baker, G. A. Sullivan, G. W. Flathers

A mine collapse severs communication with trapped miners. Landlines are crushed and commercially available radios cannot penetrate hundreds of feet of dense, conductive earth without the use of regenerative repeaters that may also be crushed. This paper describes a proof-of-concept device that uses seismic P-waves, instead of radio waves, to allow communication of a code that represents prearranged messages, including the safe haven location identifier, number of people and air quality, from trapped miners to aboveground rescue units. The transmitter designed is about 0.03 m3 (1 ft3) in size and can broadcast for four hours from its 27-kg (60-lb) battery pack. The receiver consists of a geophone and a 2.5-kg (5.5- lb) signal conditioning unit attached to a laptop computer, which displays the communication signal in real time. Testing in a bituminous coal mine with an MSHA representative revealed the device was able to transmit through 271 m (890 ft) of overburden, at 0° and 12° from vertical, using 500 W of power.

Jan 1, 2009

By James M. Barker

Industrial minerals are critical to most aspects of modern society. They are pervasive in both industry and in everyone's lives (McVey, 1989; Barsotti, 1993). They are also the dominant class of minerals produced in the United States but this fact is little known outside the industry. For example, in 1993 (U.S. Bureau of Mines, 1995, table 1) industrial mineral dollar value was double that of metals ($20.86 billion vs. $10.88 billion) and employment levels were nearly so (74,000 vs. 40,000). A further difference is that transportation tends to dominate production costs (FOB end user) whereas they are much less significant in other mining ventures or other industries. Finally, metal mines are more concentrated west of the Mississippi; industrial mineral operations are more prevalent to the east (U.S. Bureau of Mines, 1995, p. 16-17). The significance of transport cost is discussed in Part 2, which is essentially Barker and Austin, 1995. Part 1 will update and expand portions of Barker and Austin (1995) and provide a more detailed discussion of import/export relationships using a China/United States reference point because of China's dramatic influence on some industrial mineral markets since the mid-1980s (barite, etc.).

Jan 1, 1996

By Wayne D. Gould

The Cities Service Company's Pinto Valley mine and concentrator lie about 6 miles west of the town of Miami, Arizona at an elevation of approximately 4,000 feet above sea level. The concentrator started its first ballmill in July 74 and all six were available by November. Every effort was made to reduce capital costs, consequently, each unit process was studied critically to eliminate excess capital costs without loss of efficiency. Equipment selection was made on the basis of proven dependability and operating costs rather than on low bids. The result is a very workable plant with some important innovations. The concentrator is nominally 40,000 tons per day. The flowsheet is typical with 3 stage crushing, single stage closed circuit grinding, flotation, regrinding of rougher concentrate and cleaning of the rougher concentrate. The major equipment list is: 1 60 x 89 Traylor Primary Crusher 1 84" x 20' Stevens-Adamson Apron Feeder 3 7' x 16' Double Deck Tyler Screen 3 7' Nordberg Standard Crushers 6 8' x 20' Tyler Screens

Jan 1, 1975

By A. Noble

"In coal and mineral processing, several numeric parameters are used to quantify the separation performance of unit operations. For density-based separations, the partition curve is used as the starting point for many stages of diagnostic analyses. The curve is often quantified by its midpoint slope sharpness, and this single value is subsequently used for technical evaluation, benchmarking, and comparison. While this analytical approach does depict misplacement by relative density class, it inherently prioritizes middling separation and does not consider process economics or the micro-price value of individual classes. Alternatively, the organic efficiency parameter does consider process economics; however, it does not reveal information on the root cause of lost revenue or misplacement. In this paper, a new analytical approach is introduced which reconciles the technical misplacement data derived from the partition curve with the economic data derived from micro-pricing. The result is a new analytical procedure which reflects a better use of performance data. INTRODUCTION Partition curves are commonly used in the characterization, evaluation, and simulation of various physical separators. In mineral processing, partition curve analysis is routinely applied to hydrocyclones, screens, and density separators. Graphically, the partition curve depicts the recovery of particles as a function of a physical property on which the separation is based (e.g. particle density, size, magnetic susceptibility, etc.). Given the probabilistic nature of many real separators, the partition curve often exhibits a characteristic “S” shape (Fig. 1), similar to a cumulative normal distribution. Other geometric features of the curve are also depicted in Fig. 1, including the high and low closeout (or bypass) values, the midpoint slope, and the separation cut point (property value with 50% recovery). Partition curve analysis was originally proposed to evaluate coal washability (Tromp, 1937). Given the limited computational resources at the time, the analytical methods relied heavily on graphical construction and interpretation of the curve. Owing to the simplicity of the calculation and interpretation, many of these graphical approaches are still widely used for performance analysis today. The most common calculations are based on the slope of the partition curve at the midpoint. Increased slopes correspond to enhanced separation performance, since a perfect separation exhibits a stepwise transition from 0 to 1 at the desired cut point (i.e. an infinitely large slope). One common formulation of this slope, the Ecart Probable (Ep), is derived by evaluating the slope between the 25% and 75% recovery points:"

Jan 1, 2015

By J. G. Asbury

Broadly conceived, the demand for electricity depends upon three sets of variables: (i) the growths of the many individual demands for energy services; (ii) the competitiveness of electrically driven technologies in meeting these demands; and (iii) the energy-conversion efficiencies of installed electrical technologies. The first set of variables establishes the size of the potential market; the second, the market penetration of electrical equipment; and the third, the quantity of electricity required to operate the equipment. All forecasts of electricity consumption ultimately depend upon inferred or assumed relationships to describe the future behavior of these variables. This partitioning of the demand-forecasting problem is conceptually useful and will guide the discussion presented in this paper. However, it is also something of an oversimplification. Examined in more detail, the electricity fore-casting problem is exceedingly complex. The variables mentioned above are, in turn, found to depend upon more fundamental sets of demographic technological, resource, and policy variables. The demand projections developed by the major forecasting services are usually developed in terms of these underlying variables, which themselves must be independently forecast.

Jan 1, 1985

Relatively lower recoveries (60%) of coarse phosphate (-16 +35 mesh) particles are attributed to the difficulty in transportation of coarse particles from the pulp to the froth column and rapid drainage of these particles from the froth column to the pulp. Increasing the hydrophobicity of coarse particles by higher, more efficient coating of the collector and using larger froth volumes have been suggested to overcome these problems. In this study, the role of emulsification of the fatty acid-fuel oil collector on the flotation recovery of coarse particles was examined. It was determined that emulsification can not only increase the coarse particle recovery, but do so at higher fractions of fuel oil in the collector, thereby reducing the reagent cost as well.

Jan 1, 1989

By M. E. Rossi

Reconciliation of long-term block model reserves and mine production frequently shows significant discrepancies. This reconciliation can be done comparing the long-term block model reserves against a grade control model (generally, a model based on blast holes or production data). in this paper called an FI factor for tonnages, grade, and ounces; and also it should be done comparing the grade control model to the mill feed (or loaded to heaps) tonnages, grades and ounces (called an F2 factor). The long-term model usually contains blocks with dimensions larger than the size of the selective mining unit (SMU) of the operation. The smoothing effect of an estimator such as kriging will generally result in a grade-tonnage curve that does not match the grade-tonnage curve of the SMU's to be recovered. This problem is partly to blame for the reconciliation discrepancies found. In addition, in-pit perfect selection is impossible. and therefore the grade-tonnage predictions based on blast holes also need to be assessed, considering both unplanned dilution and the errors of estimation of the grade control model. This paper will focus on using conditional simulations to assess the uncertainty of the predicted grade-tonnage curve in terms of minable reserves, and in the framework of long-term mine planning. Quantifying the uncertainty in no uncertain terms is done in conjunction with a popular pit optimizer, which will yield not one, but several possible minable reserves, and therefore a range of possible minable tonnages and grades per pit shell or scheduled phase. This is a step further from the usual sensitivity analyses that are performed for deposit evaluation or development planning. Specifically, this approach takes into account the volume-variance relationship, the selectivity of the mining operation, planned and unplanned dilution. and carries the local uncertainty implicit in grade estimation into the mine design and mine planning phases. The motivation for the approach is discussed through an example, as well as a description of the procedures and steps involved.

Jan 1, 1998

By Farlow C. Davis

Magma Copper Company, San Manuel Division, is a wholly owned subsidiary of the Newmont Mining Corporation and located at San Manuel, Arizona. The ore body is a dessiminated porphry copper deposit in quartz monzonite. The primary copper mineral is chalcopyrite with minor amounts of chalcocite, bornite, and covellite. The molybdenite occurs mainly on fracture faces or else associated with quartz veinlets. Pyrite is the major sulphide mineral in gangue. The feed to the concentrator from the underground mine is approximately 0.720 percent copper and 0.029 percent molybdenite. The concentrator has a design capacity of 62,000 tons of ore daily. After a standard ore treatment circuit consisting of grinding, rougher flotation, regrinding, and cleaning, a bulk concentrate is produced which contains 27 to 29 percent copper and 1.0 to 1.2 percent molybdenite. This concentrate is pumped to the molybdenite plant feed thickener.

Jan 1, 1977

By Richard E. McGee

The paper presents a description of the procedures that were used to generate a ventilation criterion based on measurements of ambient mine air exhaust pollutant gases and ventilation airflow quantities. Today's economics dictate that a ventilation requirement be based on actual operating conditions. This will assure optimum economics and a safe working environment at the same time. The paper presents a methodology by which a ventilation requirement is based on the average maximum expected concentrations of nitric oxide (NO), nitrogen dioxide (NO2), carbon monoxide (CO), and carbon dioxide (CO2) that equipment operators in one of our Southeast Missouri mines will be subjected to. A graph has been generated whereby the expected maximum levels of NO, NO2, CO and CO2 are plotted against the ventilation quantity of a mine stope.

Jan 1, 1982

By Chuck R. McLendon

A new face ventilation system was needed at the Allied Chemical Trona mine, near Green River, Wyoming. The development of an exhaust manifold face ventilation system came from a need to reduce the dust and noise concentration level while maintaining methane control at the continuous miner working face. Dust laden air from a heading being driven by a continuous miner was contaminating the intake air in the mine around the roof bolter operator and adjacent headings. Each working heading was exhausted into the last open crosscut by a face fan. A face fan would contaminate the adjacent downstream heading with dust-laden air until a high dust concentration developed in the final entry before the returns. A face ventilation system was needed to give the exhaust of each heading an individual path to the return air. In addition, the system could not interfere with the present room and pillar mining process. A manifold system of rigid duct ventilation tubing was designed using the existing fans in a parallel arrangement. Each system was to consist of the rigid duct tubing in three headings junctioned together at the last open crosscut and exhausted at a common branch in the return air. Each heading was to have its own damper (or valve) so that air could be directed where it was most needed. The system was installed using both round and oval rigid duct ventilation tubing to minimize head loss and to allow proper ground clearance for mining machinery. Two fans in parallel were used to exhaust three headings. By adjusting the valves at each heading, up to 18.0 kcfm (9.36 cu m per sec) could be exhausted from one heading and still keep the methane level controlled in the other two headings. The manifold exhaust system has proven to be an efficient, long lasting ventilation system at the Alchem Mine. It has reduced the dust and noise exposure levels at the working faces while keeping the methane level under control.

Jan 1, 1980

Approximately forty years ago, the military services began a realistic investigation of the problems involved with the replacement of high pressure gaseous systems with liquid oxygen systems. The program was temporarily discontinued because of numerous State-of-the-Art problems. Ten years later, interest in the liquid oxygen breathing concept was revived. Initial testing of this concept was completed in 1946. The ensuing years have seen the general acceptance of many cryogenic breathing systems for airborne applications. The inherent features of weight savings (approximately 70%) and space savings (approximately 80%) make it very desirable for high performance military aircraft. A typical aircraft system consists of a storage container with appropriate integrated control valving (the liquid oxygen converter), a heat exchanger, breathing regulator, and oxygen mask. Normally the liquid converter is located in the aircraft wheel well for easy access by ground crew personnel and the breathing regulator is mounted in the cockpit where the pilot can connect his oxygen mask. An aircraft system such as this will provide the pilot with eight hours of breathing oxygen after a 24 hour standby period. Early in 1960, the National Aeronautics and Space Administration sought a means of providing a cooling system for their personnel involved in fueling the rockets used in the space program. While fueling rockets N.A,S.A, personnel wore a completely enclosed butyl rubber suit and were susceptible to heat prostration. Using the concept of an aircraft system, Aro redesigned the container, heat

Jan 1, 1971

By R. Freer

Recent developments in expanded PTFE membrane filter cloths offer high flow rates and sub-micron particle removal. These high strength, industrial grade filter cloths can be tailored for tubular filters, leaf filters and rotary vacuum drums. Filtration techniques using tubular filters make possible filtration of difficult slurries with the elimination/reduction of filter aids and chemical additives. This paper describes principles of surface filtration, applying the membrane filter cloth and comparisons to gravity separators. Benefits to the mining industry include clear effluent, enhanced solids recovery and accelerated cost payback.

Jan 1, 1996

By L. R. Chirinos

The Tintaya mine of BHP Copper, located in Southern Peru, includes a copper oxide deposit hosted in a mineralized skarn zone. The ore contains large amounts of clays and high acid consuming species resulting in low heap leaching performance. A treatment scheme was proposed that included a wet screening separation. The coarse fraction would be treated by heap and the fines by agitation leaching. The dissolved copper would then be recovered through solvent extraction and electrowinning (SXEW). Testwork determined the optimum heap leaching conditions to treat the oxide in on/off pads of 3 meter height with an initial acid cure followed by variable acid strength during irrigation. The method resulted in a reduced acid consumption and good copper recoveries.

Jan 1, 1997

By David Brown, Adrian St. John, John Comins, Mike King

"INTRODUCTION The Crossrail project provides an East-West link across London enabling an additional 200 million journeys each year linking up major business centres and existing transportation interchanges, while reducing congestion at street level and within the current underground system. The project has built major structures in Sprayed Concrete Linings (SCL), including 5 new stations, 6 crossover caverns and numerous passages, adits and ventilation tunnels. Construction has taken approximately 4 years, and has involved the spraying of over 200,000m3 of concrete. At the start of the project there was a lack of available records from previous projects concerning concrete falls, which hindered risk assessments and the ability to make meaningful comparisons around spraying or material performance. This paper redresses this lack of data by providing information on falls experienced on this project and makes recommendations to assist future projects. Construction Methods Table 1 below summarises the main contracts with elements of permanent SCL. The listed primary lining lengths include pilot tunnels, side drift tunnels and enlargements as separate tunnels.A range of construction sequences were used in order to deal with the design requirements, geometry, and the ground and ground water conditions. The following briefly summarises the build up by layers, with typical design dimensions provided for a platform sized tunnel (approximately 9m internal diameter), excluding tolerance allowances. Some linings were sprayed in more than one layer to allow for inclusion of reinforcement layers or to avoid a too aggressive build-up of thickness: •,Initial shotcrete, or sealing, layer (ISL) of 75mm followed by a Primary Lining (PL) of 300mm. •,Regulating layer of 40mm followed by a Waterproof membrane (Sprayed membrane, 3-6mm). •,Secondary lining (SL) of 250mm with a separate sprayed fire protection layer (FPL) of 50mm."

Jan 1, 2016

By R. C. Bunge

The selective flotation of semi-soluble salts with fatty acids is often negatively affected by the interaction of the potential determining cation with the ionic surfactant in bulk solution. This problem can be avoided by floating at low pH which involves the emulsification of the collector. The research presented here focuses on the influence of the Ca2+ ion on the flotation of fluorite with palmitic acid at low pH. Our results show that the surfaces of collector emulsions are dominated by precipitation phenomena similar to those encountered in bulk. In turn, fluorite in palmitic solution at intermediate pH displays surface properties similar to those of the collector by itself. This may be due to two alternative mechanisms (i) adsorption of bulk precipitate on the fluorite surface or (ii) the formation of a bilayer of surfactant ions on fluorite. Possibly, both mechanisms occur simultaneously.

Jan 1, 1993

By Felicia F. Peng

The naturally occurring aged manganese oxide coated on the granular media was found to have a catalytic effect on the removal of low concentration of Mn(II) (-1 ppm) from drinking water. Applying this principle, a manganese removal technique was developed for removal of higher concentration of Mn(II) (-100 ppm) from mine drainage by using various aged filter media and synthesized granular media with manganese oxide coatings. Laboratory-scale continuous granular media column experiments were conducted to assess the feasibility of manganese oxide-coated granular media for Mn(II) removal from synthesized mine drainage. The removals of Mn(II) were evaluated as a function of operation parameters including solution pH, manganese oxide concentration coated on the media, interstitial velocity, and oxidant concentration of influent. Higher solution pH and/or higher manganese oxide concentration promoted the removal of Mn(II) on the oxide-coated granular media under low interstitial velocity. Addition of sodium hypochlorite as an oxidant in the influent resulted in continuously regenerated oxidized surface to serve as the catalyst for Mn(II) oxidation reaction on the surface of oxide-coated media.

Jan 1, 1994

By J. M. Applegate

In the same way that a blueprint communicates information about a structure, a useful systems architecture should provide information that guides the construction and implementation of computing systems. Taking the blueprint analogy a step further, a plot plan can also show where in the "bigger picture" a particular design fits (if in fact it does) and what a builder needs to know about the environment in which he or she will operate. In the context of business systems, a meaningful architecture should convey the following: 1. The primary purpose of computer based systems relative to particular task or operation. 2. The relationship of systems to each other and an indication of their interaction and dependencies. 3. The relationship of systems relative to the organization and its objectives. 4. Indications of where IS/IT resources can best be allocated to support the organization. 5. The overall context in which new systems and technologies can be assessed for both their impact on current system and on the organization itself.

Jan 1, 1998

By Madan M. Singh

Increasingly, geotechnical data are being collected for various types of coal development projects. In many cases, a specific design concern is addressed. However, many data collection programs are not intended to immediately support mine design activities or to resolve a specific concern. The following discussion describes some current geotechnical approaches in mine planning, development of reserves, and peripheral activities. Types of Data Collection Programs Geotechnical data collection is increasingly becoming a part of standard coal exploration programs, performed along with stratigraphic evaluations and coal quality tests. The aims of such programs vary. The purpose of the exploration may be to fill out the portfolio on a block of reserves that is to be sold, leased, or held for potential future development. In such a case, a generic suite of geotechnical data are collected. The resulting engineering reports may touch on the more well known mining problems of the area, but detail may be lacking. The geotechnical data are mostly intended to enhance the saleability of the package. Mine design alternatives are generally not addressed.

Jan 1, 1985

By A. Noble

"In coal and mineral processing, several numeric parameters are used to quantify the separation performance of unit operations. For density-based separations, the partition curve is used as the starting point for many stages of diagnostic analyses. The curve is often quantified by its midpoint slope sharpness, and this single value is subsequently used for technical evaluation, benchmarking, and comparison. While this analytical approach does depict misplacement by relative density class, it inherently prioritizes middling separation and does not consider process economics or the micro-price value of individual classes. An alternative parameter, the organic efficiency, does indirectly consider process economics, but it does not reveal information on the root cause of lost revenue or misplacement. In this paper, a new analytical approach, the partition moment of inertia, is introduced. This parameter reconciles the technical misplacement data derived from the partition curve with the economic data derived from micro-pricing. The result is a new analytical procedure that promises better use of performance data. IntroductionPartition curves are commonly used in the characterization, evaluation and simulation of various physical separators. In mineral processing, partition curve analysis is routinely applied to hydrocyclones, screens, density separators and other beneficiation technologies that are based on intensive physical properties. Graphically, the partition curve depicts the recovery of particles as a function of the physical property on which the separation is based, such as particle density, size or magnetic susceptibility. Given the probabilistic nature of many real separators, the partition curve often exhibits a characteristic S shape (Fig. 1), similar to a cumulative normal distribution. Other geometric features of the curve are also depicted in Fig. 1, including the high and low closeout, or bypass, values; the midpoint slope; and the separation cut point, defined as the property value with 50 percent recovery.Partition curve analysis was originally proposed to evaluate coal washability (Tromp, 1937). Given the limited computational resources at the time, the analytical methods relied heavily on graphical construction and interpretation of the curve. Owing to the simplicity of calculation and interpretation, many of these graphical approaches are still widely used for performance analysis today. The most common calculations are based on the slope of the partition curve at the midpoint. Increased slopes correspond to enhanced separation performance, as a perfect separation exhibits a stepwise transition from 0 to 1 at the desired cut point, that is, an infinitely large slope. One common formulation of this slope, the Ecart Probable, Ep, is derived by evaluating the slope between the 25 and 75 percent recovery points:"

Jan 1, 2016