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By Darrell E. Young

This presentation will define what talc is, how it is mined and processed, and how talc is used in the paper industry. It will also give you some idea about who Luzenac America is and from where it came. Luzenac America was formed in July, 1992 as a result of the acquisition of the talc assets of Cyprus Minerals by RTZ of the United Kingdom. Cyprus Industrial Minerals was then merged with the other RTZ talc interests under the Luzenac name. Luzenac is a town in the Pyrenees of Southern France -and the home of Talc de Luzenac, RTZ's first talc acquisition. The Luzenac Group is the largest talc producer in the world.

Jan 1, 1993

By Melvin A. Jennings

Even though the title of this paper is quite long, the ideas presented herein are very simple. In fact, it occurs to me to be somewhat humble about coming before such a distinguished group with such a simple presentation. However, the application of these ideas has proven useful in at least two copper flotation plants. The purpose in presenting this paper is to inspire some interest in the great stores of data chat the Mining Industry often accumulates without making any attempt at analysis. Unfortunately, many milling engineers rely rather heavily on percent recovery as a strict measure of a concentrator's relative performance. The fallacy of this reasoning is not difficult to see since, by definition, percent recovery is a function of feed assay, tails; and concentrate grade. If copper tailing is constant, and it very nearly is for a strictly sulfide copper ore, percent recovery must fluctuate almost directly to the feed assay. The point that I wish to make here is that it is very seldom justified to compare the percent recovery figure from one period of time to another without considering the difference in feed assay. The problem of comparing results is even further complicated when the ores are of mixed oxide and sulfide mineralogy.

Jan 1, 1978

By Erik Westman, Enji Sun, Xu Ma, Ben Fahrman

"Shale gas has become an increasingly important clean energy, which has been explored worldwide in recent decades. Supercritical CO2 acts as fracturing fluid for shale gas production. The safety monitoring is essential to prevent any kinds of leakage from the reservoir as the supercritical CO2 physically stored hundred kilometres underground. Seismic tomography is an imaging technique that uses induced seismic waves to create three dimensional images of the subsurface. It is an effective monitoring method to evaluate the caprock integrity in the carbon dioxide sequestration storage (CCS). In this experimental research, a simulated uniaxial compressive load is applied on a granite sample to analyze the stress redistribution for long-term in-situ caprock integrity during CO2 injection. The induced seismic waves are recorded and seismic events are traced based on the Geiger algorithm. The frequency of seismic events correlates with the caprock failure evolution. The acquired seismic data is divided into four regimes based on the frequency of seismic events and the failure process to examine the failure evolution. Furthermore, the travel time and distance is plotted to analyze the variation of velocity. Finally, the double difference tomography (TomoDD) algorithm using arrival time is adopted to recalculate the locations of seismic events and velocity structure in each regime. The results indicate that the passive seismic system can map the caprock stress distribution and allow for imaging of the caprock integrity. TomoDD exhibits sound improvements to relocate seismic events both in relative and absolute locations as well as to characterize the local velocity structure. The study further reveals that seismic monitoring along with TomoDD could evaluate the caprock failure accurately in the CCS.Introduction To reduce the CO2 concentration in the atmosphere, CO2 capture and sequestration (CCS) has been suggested to as a means of continuing to use fossil fuel resources while offsetting their negative environmental impacts (Eiken et al 2011). A positive CCS project should retain 99% of the injected supercritical CO2 (pressure is greater than 7.38 MPa and temperature is above 31.04? and a density is of about 700 kg/m3) over at least 100 years (Davidson et al 2005). As large quantities of supercritical carbon dioxide are being injected into full scale storage projects, caprock stress is redistributing and the leakage could occur anywhere over a wide storage area (Hou et al 2012). Acoustic waves are emitted from the caprock, as it fractures due to the CO2 injection, which can be detected by passive seismic sensors (Shitashima et al 2013). Tomography techniques are advantageous for imaging the integrity of the caprock in the CCS projects. Velocity tomography uses waves to model entities based on the arrival time of waves (Westman et al 2001, Westman 2004, Luxbacher et al 2008). Seismic tomography is a data inference technique that exploits information contained in seismic records to constrain 2D or 3D models of the Earth's interior. It generally requires the solution of a large inverse problem to obtain a heterogeneous seismic model that is consistent with field observations (Kudryavtsev et al 2012)."

Jan 1, 2017

By G. R. Hart

The expected 1990 Clean Air legislation is providing electric utilities with a series of challenges and decisions as the utilities prepare strategies to comply with the resulting regulations. This paper addresses the strategy development of a coal-based utility --the legislation, the process used, the fuel issues, the options available, and the decisions to be made.

Jan 1, 1991

By H. Kempton

New methods for remediating metals-contaminated groundwater include in-situ emplacement of highly adsorptive substrates to permanently retard solutes. Substrates are introduced by sequential injection of soluble components that precipitate in the aquifer, forming a permanent high-retardation zone. This method overcomes the factors that limit pump-and-treat remediation; i.e, long-term source loading and slow desorption. Column tests demonstrated efficient substrate emplacement, increasing retardation coefficients of Cr(VI) by 20 and As(V) by 40. Similar effectiveness is expected for other heavy metals. Simulations using a coupled advective-geochemical model accurately matched substrate emplacement and arsenic attenuation, allowing extrapolation to other constituents and larger-scale applications.

Jan 1, 1999

By R. L. Grayson, Y. J. Wang

An application of material requirements planning (MRP) to coal mine inventory control is presented. MRP is an efficient material control system that integrates the production planning and inventory management functions. Net material requirements are determined from the production forecast utilizing bill of material files, the inventory status file, and the purchase order status file. Net requirements are computed for each period in a specified planning horizon, and purchase orders, offset by lead time, are initiated routinely to ensure timely receipt of materials. The MRP system is especially useful in production-inventory systems in which con¬sumption of materials is directly production dependent.

Jan 1, 1987

By E. P. Gustafson

Demand by precious metals explorationists for cost effective means to target subsurface geologic structures worthy of evaluation by means of drilling has led to the use of the predictor-correlator technique. To locate polarizable targets, the predictor-a localized inhomogeneity in electrical properties-is placed at various locations in the computer-simulated subsurface region, and correlated with the potential distribution observed in the field. The correlation coefficient obtained is assigned to the subsurface location. IP targets are extracted by calculating a second correlation section based on higher-frequency illumination and subtracting it from the first. The locations of correlation difference correspond to the locations of polarizable mineralization.

Jan 1, 1989

By Matthew J. Hrebar

Dragline stripping operations account for over one-half of the U.S. bituminous coal production mined by surface coal mining methods. The dragline is a popular stripping tool because of its flexibility in varying overburden depths and relatively low operating costs per cubic yard of overburden. Because of the relatively high capital costs of the machines and their use as a primary stripping tool, the selection process is an important step in the mine planning procedure.

Jan 1, 1979

By George W. Poling

Designing optimal placer gold recovery plants requires a detailed knowledge of the size, shape and surface physical characteristics of the gold particles and the host alluvium in the pay gravel, sand or clay. Results of a recent pilot-scale study of the quantitative performance characteristics of riffled matted sluice systems are presented. For the appropriate non-coherent pay gravel-sand with medium-flat gold, simple sluices can recover gold at greater than 85% efficiency down to 100pm diameter. Alternatives to simple sluices are presented and discussed briefly.

Jan 1, 1987

By T. Brady, J. Johnson, J. Whyatt, B. Pariseau, M. Stahl

An elastic-viscoplastic material model allows for time- dependent rock mass motion in proportion to excess stress above the elastic limit. The model produces rounded stair-step curves of displacement vs. time that are similar to those obtained from recent borehole extensometer measurements made in the central portion of the Ross Shaft pillar at the Homestake mine. The work in progress, including two- and three-dimensional finite element analyses using the UTAH2/3 codes, indicates that the model is a step towards more realistic safety and stability analysis, but that inclusion of rock mass damage may be desirable.

Jan 1, 2000

By Joe W. Siefke

The world-class Kramer sodium borate deposit is being developed by modern open pit operations near Boron, California. The deposit is a bedded, lenticular sedimentary sequence of borax and kernite crystals together with claystone. The borates dip south into a structural basin-bounding fault and were formed in the bottom muds of a permanent shallow lake. The lake was fed boron and sodium-rich solutions from a thermal spring source of volcanic origin. In addition to deposit geology, present day geotechnical concerns such as groundwater and slope stability will be discussed.

Jan 1, 1995

By M. Manrique, E. E. Vidal, I. Accorsi, P. R. Taylor

Various pyrometallurgical methods for treating ilmenite and zircon concentrates are reviewed. Laboratory experiments using a thermal plasma reactor were performed to evaluate the conversions of ilmenite to TiC or TiC-Fe and zircon to ZrC or ZrC-SiC. Results are examined and possible processing routes are identified.

Jan 1, 1999

By F. G. Boehm, T. S. Golosinski

This paper identifies the components of belt conveyor shifting force as a vertical force, Pv, a lateral force, Ph, and a longitudinal force, Pl. A method for estimating these forces is proposed that relates each of their values to the properties of the conveyor structure and rails, the shifting operation parameters, and other site-specific conditions. The effect of this force on the shifter behavior is analyzed, and guidelines are developed for selecting a suitable shifter. As well, other equipment requirements for the shifting operation are discussed.

Jan 1, 1988

By J. C. Yingling, R. Kumar, J. Sottile

The capability for on-line measurement of the quality characteristics of conveyed coal now enables mine operators to take advantage of the inherent heterogeneity of those streams and split them into wash and no-wash stocks. Relative to processing the entire stream, this reduces the amount of coal that must be washed at the mine and, thereby reducing processing costs, recovery losses and refuse-genera¬tion levels. In this paper, new ap¬proaches for optimal control of the segregation process using time-se¬ries models and empirical distribu¬tions are presented and demon¬strated using field data.

Jan 1, 2000

By F. L. Pirkle, D. A. Podmeyer

The mineral zircon is mined for use as specialty foundry sands, abrasives, ores of Zr02 and zirco¬nium metal, refractories and zirconium chemicals. It is produced as one of several products from heavy-mineral sand deposits associated with ancient shorelines. Because of its low coefficient of thermal expansion, its high melting point, its high refractive index and its chemical inertness, it is an attractive refractory material. Zircon varies from deposit to deposit in terms of grain size, grain shape and chemical purity. Thus, there is a wide range of commercial zircon products that differ in impurity levels, particle shapes and grain sizes.

Jan 1, 1993

By M. G. Karfakis, K. P. Chong

Determination of fracture toughness using the semi-circular specimen, the chevron edge notch round specimen, the short rod specimen and the cylindrical burst specimen, are critically reviewed. These methods, among all, are the most applicable for fracture toughness determination of rocks. They require minimum machining. Samples are small, and testing procedures are simple. They have a sound analytical basis and allow the fracture toughness to be determined without measurement of fracture length.

Jan 1, 1986

By P. J. Ryan

December 1988, Phelps Dodge Corp. brought an underground gold mine into production in the republic of Botswana. The mineralization is associated with steeply dipping shear zones in Archean greenstones of the Tati schist belt. The gold is intimately associated with sulfides and is refractory in nature. The deposit is being exploited by underhand open stoping methods. Vertical and inclined shafts are used to hoist the ore to the surface where it is treated by conventional crushing, milling, and flotation, followed by fluid bed roasting with cip elution and carbon regeneration. Adjacent deposits are being explored with a view to increasing production. Legal and taxation aspects of operating in Botswana are discussed.

Jan 1, 1991

By Thomas G. Johnston, Garston H. Blackwell

The development of a block model for a copper molybdenum ore deposit is described. The early use of the inverse distance power estimator, and later transition to geostatistics and kr iging, produced block models suitable for global reserve estimates. Because the global reserve was inadequate for routine mine planning, the production blast hole assays were incorporated into the block model, resulting in excellent local grade prediction. The on site use of small mini, and more powerful personal computers for estimating grades is described. The development of a computer aided, interactive graphic, mine planning system utilizing the grade block model is detailed.

Jan 1, 1987

By T. S. Golosinski, J. Wolski

Procedures are presented for determining the hourly production rate, mechanical and physical availability, utilization, use of availability, and global performance factors for the bucket wheel excavator (BWE) itself, as well as for the system composed for the BWE, conveyors, and stacker. An example demonstrates the flow of calculations. Using available data from mines that use BWE technology, the ranges of values of the BWE performance factors are presented in tabular form. They can be used as a guide during mine planning as well as to evaluate existing systems.

Jan 1, 1987

By Henry P. Cole, Andrzej M. Wala

Engineers and psychologists at the University of Kentucky have developed simulation exercises that teach and test proficiency of mining technical personnel for coping with planned and accidental connections between separate air courses in underground mines. The exercises are based upon investigations of actual mine disasters. The exercises are judged as valuable and interesting training materials by experienced mining personnel. Although these specialists generally perform well on the exercises, potentially fatal errors are not uncommon. The use of such realistic exercises may better prepare miners for preventing and coping with underground mine ventilation emergencies.

Jan 1, 1987