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By J. I. Schoenherr, T. A. Baloun

Mixed cable waste, which amounts to more than 200,000 tpy in Germany, is subjected to recycling. In most cases cable recycling means only recovering copper and/or aluminum metals. The remaining cable waste contains nearly 3-8% of the reusable materials, and is disposed of in landfills. Aluminum is recovered within copper products and leads to lower product prices. Preliminary laboratory tests show that the use of shaking hydro-tables as well as electrostatic separators result in less than 1 % of metals in the residual material. The products are high in grade at metal recoveries of more than 85%. Furthermore, applying a modified electrostatic separator may also lead to an efficient Cu-Al separation. The separation efficiency amounts to up to 95%.

Jan 1, 2002

By J. W. Merks

Applied statistics provides scores of powerful tests and techniques that are widely used and abused in science and engineering. The variance is the basic measure for variability, precision and risk. The formulas for the variances of the arithmetic mean and the weighted average are derived from the variance of a general function, as defined in probability theory. The requirement of functional or mathematical independence in probability theory translates into the concept of degrees of freedom in applied statistics. Geostatistics is the only variant of statistics in which functional dependence and degrees of freedom are irrelevant. This paper examines whether such basic elements of probability and statistics can be ignored with impunity.

Jan 1, 1998

By F. R. Corwin, M. S. King, R. W. Zimmerman

A model has been developed to relate the velocities of seismic waves in unconsolidated permafrost to the porosity and the extent of freezing. The permafrost is idealized as an assemblage of spherical quartz grains imbedded in a matrix which itself is composed of spherical water inclusions in ice. The theory of Kuster and Toksöaz, based on wave-scattering considerations, is used to determine the effective elastic moduli, and hence the wave speeds. The model predicts Vp and Vs to be decreasing functions of both the porosity and the water/ice ratio, and Vp/Vs to be an increasing function of these two parameters. The theory has been applied to laboratory measurements of shear and compressional wave velocities in thirty-three permafrost samples from different sites in the North American Arctic. Although no direct measurements were made of the extents of freezing in these samples, the data are consistent with the predictions of the model. The theory can be used to infer the extent of freezing of the water in the pore spaces, based on knowledge of the porosity and either of the two wave speeds.

Jan 1, 1986

By David M. Spatz

Anyone who scans the modern literature will realize that concepts of leadership have changed during the past few years. And like change in so many areas of our culture, change has been rapid in the perception of leadership. Many traditional leadership traits are still highly regarded and many of the longstanding personal qualities that improve leadership abilities continue to be effective. In the past, though, leaders could rely on dominance, intimidation and fear to accomplish their goals through the actions of others. In contrast, effective leaders today build relationships, provide vision and guidance, and strive for communication, cooperation, trust and employee satisfaction. Earnest leadership involves moral issues like honesty, integrity, fairness, empathy and respect. Modern leaders guide, facilitate and coach, rather than command and direct. But how well equipped are managers in the mining industry to meet the leadership challenges that lie ahead? More importantly, is he or she becoming a better leader? This article outlines steps to becoming a more effective leader. Management consultants stress that the changes that lie ahead will demand swift organizational adjustments and managers who are equipped to lead during times of change (Boyett and Conn, 1991; Hesselbein et al., 1996; White et al., 1996 and Kotter, 1997). Becoming a better leader begins with self-assessment and a commitment to unify all who depend on one's leadership abilities. Simply defined, leadership is leading others. Contrary to common practice, leadership is not about advancing one's own career but about bringing out the best in others. The beauty of modern leadership, however, is that the path of serving others creates synergies. They benefit everyone, including the leader, those the leader manages, upper management and company shareholders.

Jan 1, 1998

By S. Ford

The introduction of recent advances in molecular biology into the field of microbial ecology has made available a powerful set of analytical tools for dissecting the structure of microbial communities in natural environments. The use of these approaches, many of them based on DNA-DNA hybridization enables the researcher to assess the occurrence of specific DNA sequences among the natural bacterial flora (Ford and Olson 1987). These techniques promise to have wide application as tools for monitoring the spread of introduced microorganisms (Trevors, 198'): Ford and Olson. 1987) and have been used to examine the response of bacterial communities to environmental contaminants and stressors (Barkay and Olson. 1986. Olson and Ford. 1986. Olson. Ford and Lester 1987) The occurrence of heavy metal resistance among microorganisms has been discussed as a possible tool for the detection of pathfinder elements employed in mineral exploration (Olson and Barkay 1986). In addition, the occurrence of heavy metal resistant bacteria may be utilized in protocols for assessing the occurrence and biological impact of contamination occurring as a consequence of mining operations. In this context the use of DNA hybridization technology enables the investigator to directly quantify the number of heavy metal resistant bacteria by the use of genetic probes specific for those resistance genes. The implementation of a strategy for detection of heavy metal resistance genes by hybridization technology is dependent on the availability of data on the genetic systems which encode resistance The availability of extensive DNA sequence data on mercury resistance genes (Brown et a11986. Barrineau et al 1984) has lead us to use gene probes specific for mercury resistance within natural bacterial populations as a model system for investigating the response of these bacterial populations to the occurrence of mercury In the environment.

Jan 1, 1988

By J. W. Merks

Applied statistics provides scores of powerful tests and techniques that are widely used and abused in science and engineering. The variance is the basic measure for variability, precision and risk. The formulas for the variances of the arithmetic mean and the weighted average are derived from the variance of a general function, as defined in probability theory. The requirement of functional or mathematical independence in probability theory translates into the concept of degrees of freedom in applied statistics. Geostatistics is the only variant of statistics in which functional dependence and degrees of freedom are irrelevant. This paper examines whether such basic elements of probability and statistics can be ignored with impunity.

Jan 1, 1997

By Paul F. Richardson

Liquids containing suspended solids are encountered in most mineral processing applications. Solids levels cover a very wide range, from ppm levels in cooling water systems to slurries containing greater than 70% solids. When the aqueous phase is recycled or further processed, a solid/liquid separation process is used. Chemical additives used to carry out this process are called coagulants and flocculants. In other cases, one seeks to control or modify the properties of the suspension. Dispersants are chemicals used to aid in suspending solids in a liquid as well as to control the properties of the resulting suspension. Dispersants find a range of uses in mining and mineral processing such as scale control, filter aids, flotation aids, and slurry viscosity modification. Materials used as dispersants include inorganic salts, alkalies, organic surfactants, and polyelectrolytes. This paper discusses the use of dispersants in mineral processing, with an emphasis on control of slurry viscosity. The mechanism of dispersion and factors that affect the choice of dispersant will be discussed.

Jan 1, 1986

By Marek Niec

Native sulfur deposits in Poland occur in Upper Miocene strata on the northern (platform) border of the Carpathian foredeep. Systematic exploration since 1953 has resulted in the discovery of seven stratifom-stratibound sulfur-bearing limestone deposits that together contain about 0.6 billion tons of demonstrated sulfur reserves and about 0.5 billion tons of inferred and hypothetical resources. One open pit and three Frasch mines are currently in operation; another is under construction and one has been abandoned. Total production is about five million tons per year from ore containing on the average about 25% sulfur. Field, isotope, and micropaleontological data indicate that the sulfur-bearing limestone was formed through the bacterial reduction of gypsum in the presence of methane discharged from source beds and traps in the Carpathian foredeep. Subsequent recrystallization of the sulfur-bearing limestone, tectonic activity, jointing, karstification, and partial leaching of the sulfur has transformed the sulfur deposits and has altered the thickness and content of the sulfur-bearing strata, and their porosity and permeability, affecting the productivity and water consumption of the sulfur wells. Caputerized borehole logging techniques and geostatistical reserve estimates are used in mine planning. Great environmental impact constrains the development of sulfur mines.

Jan 1, 1992

The mining industry has indeed gone global. International minerals producers are spending big money to move into countries that were off limits a few years ago. Due mostly to political reasons, these countries' huge mineral deposits - worth billions of dollars - were locked up and mining companies could only sit on the side and wonder "what if." Now much of the world is going the free market route. Once closed countries and developing nations are rewriting their mining and tax laws hoping to attract foreign investment to develop their natural resources. And big businesses - mining companies included - are lining up to get their share. But with new opportunities come new risks. While emerging nations are slowly accepting the free market concept and the privatization that goes along with it, many remain plagued with political instability and violence. Even developed nations carry their unique risks. Some of these include inadequate or contradictory legal and regulatory infrastructures, political patronage and outright corruption. So companies hoping to expand into new regions of the world must do more than examine the market. They must study the political stability and structure of a country, as well as its tax and environmental laws. And they must guarantee the safety of their employees. Control Risks Group is an international management consulting company that assists companies preparing to move into a new country. It employs about 225 people in 14 offices throughout the world. Control Risks personnel include lawyers, bankers and former law enforcement officers and intelligence people. The company held a one-day seminar in Washington, DC to update some of its clients on the state of affairs in various regions of the world. The seminar also covered extortion, corruption and product diversion. About 175 people attended the seminar. Speakers included Control Risks' operators, analysts and investigators. Here is a summary of what some of those people had to say.

Jan 1, 1998

By K. Professor Heiskanen

The improvement of grinding circuit efficiency is a constant industrial requirement. It has often been connected to the improvement of classification. The paper discusses some operational aspects of hydrocyclone classification. A hydrocyclone should be operated close to roping but should not with high density slurries go to roping. Unfortunately roping is not well understood and roping models for controlling hydrocyclone operation are not adequate. The paper discusses also some ways of improving the classification in terms of bypass and imperfection. The last part of the paper discusses the effect of bypass and imperfection on circuit performance.

Jan 1, 1997

By P. Corser

Operational and geotechnical constraints on mining within steeply dipping deposits and historic landslide areas, which are characteristic of subarctic coal deposits in Alaska, will be discussed. The current plan for mining through these areas will be presented, as well as an alternative plan for minimizing the adverse effects of mining through an historic landslide area.

Jan 1, 1988

By G. A. Eltringham

Mining and extraction methods in the copper industry use basic technologies developed over a period of almost 150 years. Paradigm shifts in the industry have been rare, yet human involvement in the activities has changed dramatically. Clearly defined extraction paths have become more blurred as economic considerations broke down the barriers that had encouraged specialization. What had been a labor-intensive industry unfettered by environmental restrictions was forced to change. Better productivity and "cleaner" operations resulted in much higher capital costs on a plant basis. Many of the changes were truly innovative in the same spirit as in the mining revolution of the first decade of the twentieth century. What role will innovation play in the next 20 years as lower-grade, mixed-metal orebodies are exploited in more remote locations?

Jan 1, 1998

By Anthony G. Grice

This paper discusses the contribution that backfill is making to the Australian mining industry and provides some information on the largest operations together with some novel applications. Each of the three major backfill types; hydraulic, rock and paste are discussed in turn with a focus on new ideas and advances in understanding, technology and operating practices.

Jan 1, 2001

By S. M. Hsiung, Wen H. Su, Syd S. Peng

This paper examines the interaction problems of multiple seam mining by combining underground investigation, laboratory testings, and numerical modeling. One case of multiple seam interaction that occurred recently in West Virginia was carefully studied. Causes for the interaction problems were identified and the corresponding mining recommendations were proposed. The principle of pillar columnization and the effect of a remnant pillar on mining operations in the underlying and over- lying seams were also carefully examined. Considerable attention was given to the effect the pillar size, the pillar width, the coal stiffness, the extraction ratio, the degree of inhomogeneity in the interburden, the overburden thickness, the mechanical properties of the interburden rocks, the strata inclination, the interburden thickness, and the in-situ horizontal stresses have on the pillar load transfer mechanism.

Jan 1, 1986

By J. L. Post, L. Borer

Small seams of fibrous tremolite and actinolite commonly occur in many California counties. A number of larger seams of this fibrous material were mined from 1882 until about 1955. The fibers from these mines were used for making acid filters, battery cases and fire-resistant paint. With increasing population, new residential areas are being developed in the foothill regions, leading to increased contact with seams of fibrous amphiboles. These forms of asbestos can be particularly dangerous to human health. Thus, it is necessary to determine the locations of these mines and adjacent veins and to identify the specific amphibole minerals present.

Jan 1, 2003

By E. S. Bianchin

The more complex control needs of today's mineral processing plants combined with ever-changing digital technology have brought numerous improvements to process control systems. This paper discusses recent advancements in distributed control systems (DCS) which facilitate the implementation of process plant automation. Some of the topics of discussion include integrated function controllers, weigh scale and analyzer interfacing, operator interfacing, personal computers, process information management and process plant management.

Jan 1, 1988

By M. S. Duffy

To exploit the mineral resources of fine grained ore bodies the minerals processing industry is turning to fine grinding technology, of which tower milling has become an established part. However, compared to other mills relatively little is known about the operating mechanisms in tower mills. In all milling processes one of the keys to understanding how they work is in knowing how their grinding media move. To investigate the ball motion in tower mills a glass unit was therefore constructed and measurements taken of the movement of the grinding media. This paper describes the results from this study.

Jan 1, 1998

By Vladimir L. Konyukh

Robotics is topical for mining owing to deterioration of miner's safety as a depth of winning, limited functions of traditional mechanization and automation, rise of miner's labor cost. Mining robot is an autonomous mining machine with a free programmable control that provides a multifunctional use of working head. After analysis of world publications the database “Technological applications of robotics in mining" has been built. In most cases robots are suggested for imitation of miner's motions. The following shapes of robotics had been classified for mining: technological robot as a flexible controlled mining machine, remote manipulator, mine rescue robot. The problems of both non-repeated environment recognition and telepresence without direct visibility must be solved. The more a robots integration is the less investments and the more efficiency are. Computer simulation of robotics-based mining is founded on a base of 6 robots functional models, Petri nets and library of 30 robotized technologies. There are some examples of mine robotization in the paper.

Jan 1, 1996

By B. J. Arnold, F. F. Aplan, S. Chander

There is a broad range of chemical reagents of potential use to the coal preparation industry: flotation frothers, flotation collectors (for coal, ash minerals or pyrite) and collector-assisting (conditioning) agents, flotation depressants (for coal, ash minerals or pyrite), pH regulating agents, acid mine drainage treatment chemicals, flocculants, filtration aids, dispersants, dust suppressants (wetting agents and car-top or pile binders), freeze conditioning agents, water treatment chemicals (corrosion and scale inhibitors) and suspension stabilizing reagents (dispersants, stabilizers, biocides). The application of each of these types is discussed with particular attention paid to those of greatest importance: flotation frothers and collectors, pH regulators and acid mine drainage treatment chemicals, flocculants and freeze conditioning agents.

Jan 1, 1986

By Claude Hébert

The Grenville structural province, a 400 km-wide belt of Precambrian metamorphic rocks which crosses the province of Québec in a northeasterly direction, is the host of several wollastonite occurrences. Most of these are found in marble and calc-silicate rocks enclosed within or located near intrusive bodies. Reconnaissance and detailed mapping of such zones have helped to identify areas of interest for wollastonite exploration. The most important zone is located in the huge Lake Saint-Jean anorthosite massif in the central part of the Grenville. A recent geological mapping project has revealed the presence of wollastonite in metasedimentary faulted remnant of the roof. The main occurrence consists of diopside and wollastonite in a zone at least 3 km long and 150 m wide. Preliminary sampling suggests and average grade of 50 percent wollastonite with an aspect ratio of 151. Other wollastonite deposits occur in the western part of the Grenville, mainly north and west of Montreal, where the Morin anorthositic complex and a large syenite mass intrude the metasedimentary rocks of the Grenville Supergroup. Marble bands with up to 70 percent wollastonite occur locally at the southern margin of the complex or as an inclusion in the syenite. Significant wollastonite occurrences have recently been found in the eastern part of the Grenville. One of them is located in metamorphosed calcareous rocks which are part of the granulite facies Manicouagan metamorphic complex. A representative sample analyzed 54 percent wollastonite. Farther south, an inclusion diopside-wollastonite gneiss containing an estimated 40 percent wollastonite occurs at the margin of the Pentecôte River anorthositic complex.

Jan 1, 1995