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By K. Feledi

"A booster fan is an underground mechanical ventilation equipment installed in series with a main surface fan that is used to boost the air pressure provided by the surface main fan passing through it. As mining continues to expand and go deeper, the need for improved and efficient ventilation increases. This has led to the use of booster fans and other auxiliary ventilation devices in underground mines. This paper details experiments and results carried out at Missouri S&T Experimental Mine that investigated air leakage and recirculation caused by the use of booster fans. The results were compared with the situations where booster fans are used and not used.The variables considered were the booster fan blade angle and the fan combinations. Air quantity measurements were taken at each individual stopping under a number of scenarios and across four blade angle settings. The first set of situations examined were; the main surface Joy fan only running, the main Joy, and the west booster fan running, and the main Joy fan and east booster fan running. Observations were made which lead to the conclusion from the experimental analysis that booster fans affect the behavior of leakage and recirculation. The locations of the booster fan and the blade angle setting have the most effect on leakage and recirculation. To limit the potential for system leakage and recirculation, the location and size of a booster fan in a ventilation system should be thoroughly evaluated.INTRODUCTION Missouri S&T Experimental Mine ventilation system The Missouri S&T Experimental Mine has two shafts. One currently serves as the main intake shaft. Air is forced through the main shaft by a Joy Manufacturing Vane Axial fan and follows the direction shown on the map on Figure 1. The air is currently naturally exhausted through the Wheeler portal. As indicated on the map there are eight stoppings in the mine, with stoppings number 2 and 8 fitted with man doors. The mine also consists of three raises which are either fully or partially blocked, two portals with one acting as an exhaust and the other generally closed by a hydraulic Kennedy door."

Jan 1, 2015

By C. A. Rowland

Wet grinding rod mills have been used for 50 years to grind ores and to make specification sand. The application of wet grinding rod mills is well understood. Until recently, there have been very few installations of dry grinding rod mills. The basic principles learned from wet grinding rod mills that were used in the application of dry grinding rod mills are 1. It is possible to extrapolate the performance of 5' and 6' diameter wet grinding rod mills into larger diameter rod mills with the larger mills performing as predicted. Wet grinding rod mills as large as 14' diameter (inside shell) by 20' long using 19.5' long rods are in use operating satisfactorily. 2. Wet grinding rod mills generally grind more efficiently when the fines are left in the mill feed than when the fines are removed from the feed. 3. Wet grinding rod mills produce little tramp oversize and generally can be operated in open circuit except when very close control on the top size in the product is required. When operated in closed circuit, the circulating load is normally less than 100%. 4. The power required for the desired grind can be accurately determined from the work indices obtained from rod mill grindability tests on the material to be ground. Where required it is necessary to, apply inefficiency factors for oversize feed and for larger or smaller than normal- ratios of reduction. Recent applications for rod mills have developed where it is required that dry grinding be used. These recent applications cover the grinding of 1. Lead sinter, lead slag and limestone. 2. Iron ore. 3. Silica for making glass sand. 4. Cement clinker. 5. Coke.

Jan 1, 1968

By J. LaForest, R. Riggle

In today’s challenging mining environment, everyone is focused on minimizing cost per ton. With haulage costs approaching up to 45% of the overall mining costs, and loader performance driving production, optimizing payload on the truck is a big opportunity. This paper will focus on technology’s role in loaders achieving the truck target payload. There are constantly new innovations in technology, but not everyone uses them correctly. Technology is intended to help achieve the next level of performance, but still requires the right people and processes to effectively utilize the benefits. In today’s mining business, miners, engineers, trainers, supervisors, and managers have ever increasing roles and responsibilities as never seen before in past decades. Technology can make these roles more efficient, but fully relying on the technology can detract from optimization. Sometimes the old-fashioned method of loading to a consistent pass match will provide a lower cost per ton. Before blindly trusting your technology feedback, know these three areas discussed in this paper: (1) Prerequisites to utilize technology in payload management; (2) Types of payload management technology; (3) How to use the data to manage operator behavior. The objective of this paper is to provide low-cost recommendations to efficiently increase production. INTRODUCTION Whether miners claim to have been around and experienced it all, or they are the data-driven new generation on the mine site, miners are expected to execute the mine plan at the lowest cost possible. So why is it so difficult to execute this task? Shouldn’t supervisors just have to staff the equipment, tell operators to have a safe day and tally up the numbers at the end of the shift? Let the technology system do the rest; what could go wrong? Lots. Having examined numerous mining operations that use the latest loading technologies over the past several years, one common denominator is the opportunity to improve loader operator performance. Mining companies seek help from consultants, training departments, performance reporting systems and an arsenal of resources. Armed with all this information, but the improvements don’t happen, what could have gone wrong? It comes down to people, not managing the resources to drive the right behavior and as a result, the mine’s performance is not where it should be. Understanding how to make “Great Miners” out of these people is critical to this constant struggle to move more with less and get the costs down. Extraction CPT (Cost-Per-Ton) is most sensitive to optimizing loader production which can be generalized into 3 categories of influence: machine specifications, cycle timing, and continuous management using technology. After establishing a basic production machine configuration, utilizing technology to manage cycle times, operator efficiency and payload can be advantageous. Prerequisites to Utilize Payload Management Technology It is important to begin with the primary considerations that enable the use of technology to continuously manage loading productivity. All systems are interdependent in mining, but these are divided into the simplest terms to remember. First, fix your timing and geometry.

Jan 1, 2019

By K. J. Sollman

As a class, silicate minerals have likely found the broadest, if not largest volume, use in combination with polymeric binders of all industrial minerals. Among the silicates, calcium metasilicate, wollastonite, enjoys a front runner position in a near universal sense. It is a viable and desirable part of composites ranging from thin films to large moldings; from a common filler/extender for paint for your garage to a reinforcement for the exterior surfaces of a luxury vehicle affordable to very few. This article is focused upon the variations in particle morphology and the surface characteristics which, by way of commercial examples and discussion of active research programs, make this environmentally benign mineral so unique.

Jan 1, 1993

By R. Heersink, C. H. Wells

Innovations in communications and real-time information systems are providing industry opportunities to improve profitability. Real-time operating data is collected from equipment across a site or even several sites into a central server for secure PC and PDA-based Internet access. This paper includes discussion of how operating staff can use wireless devices to see equipment and processing data from anywhere throughout the mines and concentrators, and how management can view results from multiple mines, all in real time. Additional opportunities enabled through the remote access by equipment vendors or mining consultants is also presented, as well as an overview of typical benefits and current installations.

Jan 1, 2002

By M. P. Adamson, Bryson D. Trexler, R. V. Ramani, Mark L. Koenig, V. Rajaram, Alan Burton, C. S. Crocker, Kim. Y. C., A. G. Law, William C. Larson

Another record year vas experienced by the mining industry as the value of nonfuel minerals production soared to $23.5 billion-up 15% from the previous year. Based on preliminary estimates by the Bureau of Mines, US mine output was the basis for about $225 billion worth of minerals-derived materials. Metal mining accounted for $8.5 billion, or 36%, of the total. Of the 22 metals produced in the US, 11 showed quantity increases, while 16 had value increases. Business Week's survey of 1200 companies (Mar. 17, 1980, pg. 81) revealed that 21 metals and mining companies had sales increases of 30% with earnings up 104%. Higher prices and increased demand for metals were primary factors behind the improved performance. The steel sector reported a 30% decrease in earnings for the year, but the slump was primarily the result of a $383-million loss for US Steel coupled with a 17% decrease in earnings at Inland Steel. Other firms did well in 1979, with earnings up 279% at Interlake and 269% at Kaiser Steel. Major obstacles facing the steel industry included substantial tonnages of dumped and subsidized imports, environmental expenditures, runaway inflation, and price controls. Turning to nonmetallic production, of the 49 commodities reported by the US Bureau of Mines, 29 had higher outputs and 39 had increased values. While production statistics may seem encouraging, government regulations continued to stifle industry efforts to develop needed new capacity. A case in point may be publication of the Environmental Protection Agency's simplified procedure to streamline five permit programs by consolidating them into one. The five included: hazardous waste management, national pollution discharge elimination, dredge and fill, underground injection control, and prevention of significant deterioration. The new procedure, published by EPA in the Federal Register, took 149 pages. AMC's J.A. Overton, Jr., noted that (MCJ, Nov. 1979, p. 39) to visually depict the complexity of the proposed regulations, Sell Oil Co. developed a flow chart mapping a path through one section. The chart required 10 days to map and two weeks for two draftsmen, using computerized drafting techniques, to plot the results. Overton said, "Perhaps the greatest service EPA has performed in preparing its proposal is to demonstrate again that federal regulations have become a complexity compounded by confu¬sion that culminates in a conundrum." While regulatory agencies promulgate new regulations, the lack of a cohesive government minerals policy remained a matter of significant importance to mine management. A non-fuel minerals study to provide input to the Administration for a national minerals policy program was a dismal shock, according to Rep. Jim D. Santini (D-NV). He said the first phase of the program, which was to identify industry problems, failed to come to grips with the hard decisions necessary regarding these problems, their impact, and their interrelationship. Santini said the report failed to acknowledge government's role in the process and absolved the government of any adverse influence on the domestic minerals industry. In response to the phase one report, eight senior mining executives testified before Santini's House Subcommittee on Mines and Mining concerning mineral supply, access to foreign sources, environmental protection, conservation and recycling, national security, and capital formation. By year's end, Rep. Santini promised to prepare a hard-hitting committee report on problems affecting the non-fuel minerals industry to provide a better base for subsequent policy recommendations (MCJ, Jan. 1980, p. 34). On the technological front, interest again centered on mechanization, automation, and scaleup to improve and expand production. Computer use increased for calculation of ore reserves, mine planning, operations research, and mineral processing.

Jan 5, 1980

By Alizeibek Saleimen Nader

The intensive use of computers for mineral application at Serrana's phosphate mine in Jacupiranga, State of Sao Paulo, Brazil, began in the late seventies. The early hardware and software available are described in sufficient detail to allow comparisons between that solution and the new one, based on a personal computer and a new software package - PC MINE SYSTEM from GEMCOM SERVICES INC - that provides full color graphics capabilities plus mine design and planning tools. The process needed for adaptation to the new technology' and its impact on SERRANA S.A. DE MINERACAO are described. Finally, future enhancements to the System and mine control and planning are focused.

Jan 1, 1989

By William H. Dresher

Introduction A subject long debated but rarely resolved involves the interaction between the academic community and industry in the sponsorship and conduct of research. The subject is, unfortunately, too often treated as a controversy involving ethics and the profit motive. But, in fact, the two branches of society - industry and academia - are necessarily part of the same system. In the last 25 years, the realization has developed that research alone is not sufficient to bring about use of those results to benefit society through productivity gains and economic growth. The flow of events shown in Fig. 1 was generally believed to be the steps required for reaping the benefits of research. Today, research still has the very important role of creating new information or new ideas. However, it is recognized to be but one of many steps in a process that we now refer to as technological innovation. Charpie (1967) said, "Technological innovation is the driving force behind economic growth in the US. In this context, innovation means the process by which a new idea is successfully translated into economic impact within our own society, by providing better products, and simultaneously creating new jobs in the manufacturing of those products. Only after an investigation is put into sufficient use to have an economic effect, is it termed an innovation." One of the best depictions of the technological innovation process is shown in Figs. 2 and 3. These are adapted from Haeffner (1975), and modified by the Committee on Mineral Technology of the National Research Council (1981). Figure 2 identifies the many steps involved in the process. It designates a generalized form for interaction between the academic community and industry. Figure 3 identifies the steps in the "innovation activity" box of Fig. 2. Academia is generally responsible for developing of new knowledge and ideas, as well as maintaining and enlarging the collected body of scientific knowledge. Industry is responsible for developing new products, methods, and processes. Both institutions operate for the benefit of society, but under different driving forces. In academia, the driving force is the achievement of academic excellence. In industry, the driving

Jan 10, 1984

By Geoffrey Purcell

Improvements which have been made in commericial flotation systems during the past fifty years have resulted more from trial and error methods in the mill than from research in the laboratory. Research has often provided explanations of why mill changes have improved the metallurgical process. Hopefully, in the next fifty years, changes in mill flowsheets will come about, primarily, as a result of research work. However, since minerals, in their infinite variety, cannot be reduced to a standard state, research on commercial ores will have only a local utility, and research on pure minerals will have little commercial application. What will emerge from research on pure systems are mechanisms of adsorption, and this in turn may throw some light on the very much more complex adsorption processes taking place in the pulps of commercial ores. Quartz, without a doubt, has been the subject of more research effort than any other mineral, but we are still a long way from completely understanding its behavior in flo¬tation. Hematite and calcite have received considerably less attention. Ores containing a mixture of all three minerals, however, are commercially important, and the iron deposits in Alabama have been extensively studied by the United States Bureau of Mines (1). The literature reveals no reports of research on synthetic mixtures of all three.

Jan 1, 1967

By Adam Bezuijen, Tiago Gerheim Souza Dias

"The construction of mechanized tunnels in soft ground has evolved significantly over the last 20 years, especially in the control of the face pressure and the closure of the soil-lining void to reduce the induced settlements. On the other hand, several mechanisms of the TBM excavation cycle are still not taken into account for routine design calculations, such as the increment of water pressures in front of the tunnel face, the flow of excavation fluids around the shield, the dynamic equilibrium between the grout pressures and the excavation convergence, among others. This paper discusses specifically the issue of face pressures and how several mechanisms, which are routinely not considered, can be easily verified and incorporated into the state-of-practice of design. INTRODUCTION The stability of underground excavations is traditionally assessed through analytical solutions based on the lower bound theorem of plasticity (Atkinson and Potts 1977; Mühlhaus 1985) or the limit equilibrium method (Anagnostou and Kovári 1994; Messerli et al. 2010). These methodologies depend on the tunnel geometry, certain ground parameters and the support pressure. When conventional construction methods are used, the internal support pressure is an abstract representation of the combined effects of partial excavation, ground reinforcement, and the different support elements. The use of closed-face tunnel boring machines (TBM) changed this perspective, as the magnitude of pressures acting on the excavation boundary could be controlled in a more direct way. In front of the TBM the ground is excavated as the cutterhead rotates and the cutting tools scrape the ground from the tunnel face while additives are injected to condition the material. Water, polymers, bentonite, and foam can be used as additives under different conditions (Thewes et al. 2012). The loosened ground with additives, herein referred to as the mixture, flows through the openings at the cutterhead and into the excavation chamber. This mixture is kept pressurized to support the face."

Jan 1, 2016

Power consumption of stirred media mills has been studied by an approach developed from work on stirred reactors. Relationships between torque required to rotate both disc and pin impellers immersed in dense particulate media as a function of speed, impeller and tank dimensions, and other relevant variables are evaluated. Data collected during numerous different experimental conditions are analyzed. The results can be summarized and presented in the form of characteristic plots, general equations and dimensionless group correlations involving power and modified Reynolds numbers. Special attention is directed towards the rheological properties of the media, which is considered as non-Newtonian liquids and hence, the equation of power law liquids is employed. Procedure for estimating parameters of effective viscosity and scale-up guidelines with respect to power consumption are put forward.

Jan 1, 1994

By P. J. Hyde

Cyanide is a significant contributor to the cost of producing gold. Any reduction in consumption that can be achieved through more reliable measurement and/or more efficient management of dosing rates can have a significant financial impact. An automated analyser, by its mechanical nature, is not prone to the variations of human operators, particularly notice­able from shift to shift. Reducing the standard deviation of the measurement (ie, reducing noise ), the automated measurement will give the metallurgist a truer picture of the underlying patterns of usage. The combination of automated analysis with on-line operation and a control loop provides timely information that is efficiently utilised in the management of the plant. Until the release of the Chemtronics On-Line Cyanide Analyser (OTA3000) about 12 months ago, the Australian experience with automated analysers (especially on-line) had been substantially negative. Since its release, the Chemtronics instrument has outperformed both manual titrations and other automated instruments, gaining an enviable reputation for accuracy and reliability in the process. The instrument is built around the technique ofpotentiomet­ric titrations, in which the potential of an indicator electrode is measured as a function of the volume oftitrant that is added to the sample. As the cyanide in the sample is depleted, the potential on the indicator electrode changes rapidly, producing a typical sigmoidal curve. The OTA3000 takes the first differ­ential of the curve, identifies the apex of the peak as the endpoint and reports the result in parts per million of sodium cyanide. The OTA3000 accepts the peak as valid only if it exceeds a certain minimum height. That minimum height is a programma­ble parameter and is used to optimise the relationship between sensitivity and the rejection of spurious peaks. The instrument will track cyanide trends through both positive and negative slopes of any magnitude, but it will provide a warning if it the slope becomes excessive, not because it affects the instrument but because it means that something unusual is occurring in the tanks. There are a limited number of conditions under which the instrument will produce a result of zero. In these cases the OTA3000 holds any output lines at the last valid result while it repeats the titration. This feature was incorporated for reasons of stability in a feedback loop.

Jan 1, 1995

By Nural Kuyucak

Several thousand years ago, metallurgists discovered that by combining two relatively soft metals, copper and tin, they could make a new material, bronze, that was stronger than either metal separately. Bronze and other alloys show how different materials can be integrated to create something new and better. Today?s mining industry can likewise find benefit in an integrated approach to managing the external impacts it has through its waste materials and its use of water. Just as using bronze gave ancient nations an economic and military advantage, mining companies can gain competitive advantage through finding better ways to manage water and waste. Trends pushing this include: ? Environmental ? Regulations on water-taking and the quality of discharged water are becoming more stringent. Net zero discharge requirements are often imposed by regulators. Mining companies also come under pressure to manage environmental impacts of mine waste, including minimizing the area occupied by waste and seepage amount resulting from infiltration of water from a smaller surface area. ? Social ? Particularly in arid parts of the world, there are multiple possible uses for each gallon of water. Local residents do not want to see a reduction in supplies of water for agricultural, domestic, manufacturing and other purposes. They get suspicious about any potential impact of water being mixed with their water reservoirs if it comes from a mining site, even if it would be treated. Such suspicions may cause conflicts among the stake-holders and delays in project approval processes.

Jan 1, 2009

By M. G. Premo

The McKinley Mine is located in the northwest New Mexico, in McKinley County, approximately 25 miles from Gallup. The mine is operated by The Pittsburg & Midway Coal Mining Co. (P&M), a wholly owned subsidiary of the Chevron Corporation. P&M is headquartered in Englewood, Colorado. Since the McKinley Mine began operations in 1962 a total of 83,391,000 metric tons of coal have been sold through 1990. The 1991 production was approximately 5.000.000 metric tons. The mine operations are contained on a 109.000 square kilometers lease area of which 44.000 square kilometers are on the Navajo Nation. The present customer base consists of four utilities and one industrial account, all of which are located in Arizona. The utility customers are the Arizona Public Service Co. Cholla Station at Joseph City, The Salt River Project. Coronado Generating Station near Joseph City, and The Tucson Electric Company, Irvington Generating Station in Tucson. The industrial customer is the Stone Container Corporation, Snowflake Paper Mill.

Jan 1, 1992

By S. J. Schatzel, J. D. Addis, V. Gangrade

In longwall mining, ventilation is considered one of the more effective means of controlling gases and dust. In order to study longwall ventilation in a controlled environment, U.S. National Institute for Occupational Safety and Health (NIOSH) researchers built a unique physical model called the longwall instrumented aerodynamic model (LIAM). The LIAM is a 1:30 scale physical model geometrically designed to simulate a single longwall panel. It has an 8.94 by 4.88 m (29 by 16 ft) footprint with a simulated face length of 220 m (720 ft) in full scale. LIAM is built with critical details of the face, gob and mining machinery, and scaled to preserve the physical and dynamic similitude. This paper discusses the gob-face interaction, airflow patterns within the gob, and airflow dynamics on the face for varying roof caving characteristics. Results are discussed to show the impact of caving behind the shields on longwall ventilation.

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 George L. Wilhelm

Timber support of mine openings continues to be an effective system for ground support, due to its avail¬ability, flexibility, and ease of installation. Timber support of mine openings as a primary method to support loose rock has been replaced to a large extent by rockbolting and by filling systems. How¬ever, the many designs of square-set timber and varia¬tions of crib and stull support that have been developed to suit many stope configurations have proven reliable over many years of application. Integrated in modern excavation and stoping methods, timber remains an im¬portant ground support material for today's mines. ADVANTAGES AND DISADVANTAGES OF TIMBER SYSTEMS Timber, when used as a part of the total support system, is recognized for its unique support properties. More than a cover to prevent minor falls of ground, timber systems have been carefully designed to provide adequate support with sufficient compressive qualities to achieve a safe working environment in extremely diffi¬cult ground conditions. In some cases, a timber support method is designed to yield while retaining its protec¬tive support qualities. Little or no initial investment in equipment or plant is required for incorporating timber into the mining support system. Low cost cutoff saws and portable chain saws are sufficient equipment for effective use of dimen¬sioned (sawed) or round (stull) timber support. Until recently, small sawmills of various complexity were com¬mon at mine surface plants. Sawmills at the mine sites have generally been replaced by timber vendors' mills. Suppliers have been able to use efficient cutting and lumber handling methods to reduce the cost of mine timbers. Most suppliers will package dimensioned mine timber into bundles that are suitable for handling down mine shafts and on level conveyances. The principal disadvantage of timber as a support method is higher material cost and labor cost associated with its labor-intensive installation. Furthermore, stand¬ing timber reserves of mine quality wood are in short supply in some areas, and heavy competition exists for alternative uses of the timber supplies. Vendors are reluctant to supply large cross section dimension tim¬bers relatively free of defects. Some mine operations require 4.8-m (16-ft) lengths of firm timber over 0.09 m2 (144 sq in.) in section and these are difficult to obtain in large quantities. APPLICATION OF TIMBER FOR MINE SUPPORTS Timber used in mine support has been cut from many species of trees. A firm hardwood with physical properties similar to western Douglas fir has been pre¬ferred in the US. Other harder and softer woods, how¬ever, have been used when readily available or where the specific strength or crushing quality of the wood is a desired specification of the support system design. Hard¬ wood, commonly oak, has been used where maximum crushing resistance is required. Mahogany and fir are widely used for shaft guide timber. Normally, timber is used with its core axis parallel to the long axis of the timber dimension. However, in some cases, it is placed normal to its core in a "butt" log position, so as to provide maximum resistance to abrasion of the ore passage adjacent to the cut end of the block. By selective placement of timber block¬ing, controlled resistance to ground closure can be achieved which will prevent early failure of primary sup¬port members of the timber structure. Timber is widely used in modern mining operations as a construction member for chute-lip support. These designs are tailored to each operation to conform to the dimensions of the haulage equipment being used. As a construction material, wood requires none of the spe¬cial equipment necessary for placement of concrete or steel support. Placement of these alternate support ma¬terials requires carefully dimensioned and engineered excavation for their installation. Wood can be easily sawed to fit on location. The successful use of timber in heavy ground de¬pends on the careful and accurate placement of block¬ing and bracing to achieve the controlled yielding re¬sistance needed to support the mine opening. Similarly, frequency, size, and placement of top and bottom block¬ing stulls in flat-bedded deposits are carefully determined to provide adequate support at the mining face. Con¬trolled caving through failure of the stulls may be required as the scope retreats from the earlier mined-out sections. The support program must achieve both of these dimensionless qualities by specification of stull frequency and size. The utility of the square set-system of ground sup¬port and timber support is described in Chap. 2, re¬printed from US Bureau of Mines Information Circular 6691. Four examples of effective use of timber for support of stoping and other mine openings are pre¬sented in other chapters in this section. The Gilman mine's use of Mitchell slice stoping described in Chap. 3 is an early modification of the square-set mining system. This application proved reli¬able for heavy ground and overcame some of the dis¬advantages of conventional square-set timber. Chap. 4 describes the Burgin mine's use of timber with other reinforcement material. This combination of materials achieved high strength and control with yielding com¬ponent members necessary for heavy, squeezing ground. Chap. 5 describes the Bunker Hill mine's use of square¬set timber in a new configuration that provides an effi¬cient and safe support for stoping using small load¬haul-dump (LHD) mobile equipment. Chap. 6 describes some considerations in placing the widely used stull in bedded ore deposits. Finally, in Chap. 7, cost calcula¬tions for

Jan 1, 1982

By Andreas Eberhorn

The evaluation criteria for cost comparison of the Gearless Drive, also called Ringmotor or wrap-around motor, as variable-speed drive with a Twin Drive System using synchronous motors are reviewed. Both mechanical and electrical components of the drive system are considered. The evaluation criteria are described and for the cost comparison the applicable method is demonstrated. The cost comparison is based on a medium and large sized mill system. Each drive package will display cost details with regard to capital cost, maintenance, power losses, overall efficiency, overhead and loss of production. As conclusion the benefits and disadvantages of the two drive/mill packages will be presented together with a payback diagram.

Jan 1, 1996

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

By Edward Thomas

Yucca Mountain Overview The U.S. Department of Energy?s Yucca Mountain Project is a geologic repository project designed to receive, handle, package, transport, and emplace spent nuclear fuel and high level radioactive waste. The planned repository would be located in Yucca Mountain on the western edge of the Nevada Test Site, about 90 miles northwest of Las Vegas, Nevada, and would include both surface and subsurface areas. Yucca Mountain rock formations consist of successive layers of volcanic rocks (called tuffs) approximately 14 to 11.5 million years old, formed by eruptions of volcanic calderas to the north. With the volcanic rock the potential for methane emission is not an issue and the subsurface repository is a non-gassy (methane) classification. This paper will provide a summary of the development ventilation system design that provides fresh air for subsurface construction activities, and the emplacement ventilation system design that removes heat generated by the waste packages. The subsurface layout, illustrated in Figure 1, contains 108 emplacement drifts, one Performance Confirmation(PC) observation drift, nine intake/exhaust shafts, and three access ramps. The existing Yucca Mountain facilities, shown in bold lines in Figure 1, include a 7.8 km long, 7.62 m (25 ft) diameter U shaped tunnel that is formed by the North and South Ramps at both ends of the Exploratory Studies Facility (ESF) drift and a 1.5 km long, 5.0 m (16.4 ft) diameter Enhanced Characterization of the Repository Block drift (ECRB) that were constructed from 1994 through 1998. These drifts were used for site characterization activities and have been incorporated into the subsurface repository configuration. The unexcavated perimeter access main and exhaust main drifts are typically 7.62 m (25 ft) diameter TBM excavations and the emplacement drifts are 5.5 m (18 ft) diameter TBM excavations. The turnouts leading into the emplacement drifts are to be excavated by either mechanical, or drill and blast methods and serve as the launch chambers for the emplacement drift TBM excavations.