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By J. A. van Huyssteen, P. H. Radcliffe

With the profit squeeze of recent years and indeed the survival of many mines at risk due to low gold prices and declining grades, many inventive solutions have been found of increase production and decrease cost. One of these is the application of process auditing methodology which is essentially a tool to determine systematically whether a process is delivering optimally and, if not, to identify the basic causes. Then a prioritized action plan can be developed with the client. Our experience has shown that problems are seldom what they appear to be and that most processes can operate far more efficiently with relative little effort. A process auditor requires good facilitation skills to overcome initial suspicion, and for sustainable solutions client involvement is essential. Process auditing as it is being applied in Anglogold has evolved over many years to reach its current format. The lessons learned and insights gained in the process are shared here with the reader.

Jan 1, 1999

By L. Landryova

The Department of Control Systems and Instrumentation, VSB - the Technical University Ostrava, has been involved in a project dealing with utilization of landfill gases, when the methane gas utilization and minimization of its release into the atmosphere was the main concern. The landfill site is generally a place, where technology for energy production can be built. The conditions for this technology implementation vary and depend on various factors. This paper is presenting findings and experience gained regarding a method of methane gas utilization for energy production. This method is concerning building bioreactors at the landfill sites, which are already operated. Every bioreactor can be thought of as a process, which is controlled in order to maximize energy production and minimize the methane gas escape into the atmosphere. The bioreactor landfill can represent a number of environmental and cost savings and, at the same time, is able to comply with all legislative issues.

Jan 1, 2005

By Stanley Bunk

The fluidized bed was invented by Fritz Winkler of Germany in 1921. The first application in the U.S. was in the development of the fluidized bed catalytic cracking of petroleum in 1942. Today, fluid bed cracking reactors are an integral part of every oil refinery. When fluid bed technology was first considered for applications outside the petroleum industry it was recognized to have uniform temperature, close control of the gaseous atmosphere and excellent mixing between solids and gases. Roasting of sulfide ores and concentrates was an obvious match. The first application was a single stage roaster for gold refining in 1947. There have been over four hundred commercial fluid bed roasters built and operated successfully in the four decades since the fluid bed was invented. There are three general categories of roasting applications. The largest number of roasters fall into the dead roasting category which includes gold ore roasters. The other categories are sulfating roasters and partial roasters (Reference 1).

Jan 1, 1990

By D. Lenartowicz, K. R. Alexander, M Collings

Cosmo Howley is a gold deposit in the Northern Territory of Australia. The geology is complex and the input of geological data is an important part of the grade control process. As the geology of the deposit has become better understood, grade control and mining techniques have evolved to meet the changing circumstances. Present grade control depends on the use of angled blast holes, 21/2 benches and selective mining. Data is processed on site using 2 386 PC's running Surpac software. An environmental protection programme is employed, including soil stripping and stockpiling, sulphide waste containment and water quality monitoring.

Jan 1, 1989

By C. J. Bise

Continuous mining accounts for about 69% of the nation's underground coal production. This level is not expected to change much in the near future. This is because continuous mining represents the primary means of under- ground coal production. It is also the primary means of driving development entries for underground coal mines, including longwall mines. The continuous miner worksite contains many characteristics that can lead to personnel accidents. It continues to be an area of concern for mine managers, safety engineers, and training coordinators. In an effort to assist mine management in attempts to reduce the number of accidents and injuries sustained in this area, this paper presents a loss-control-based, non-intrusive strategy for conducting safety evaluations at continuous miner worksites.

Jan 1, 1991

By J. A. Herbst, K. N. Han, P. B. Queneau, S. W. Asihene

As hydrometallurgy matures as a technology, more of its existing process knowledge will continue to be summarized in the form of detailed mathematical models. This development is happening at a time when major improvements in computer hardware have reduced the cost of computing. The opportunity then exists, through the solution of these process models, to design, control, and optimize hydrometallurgical plants on the basis of the physics and chemistry of its processes and less on empiricism. In this paper, a review of the current capabilities of sensors and phenomenological models for selected hydrometallurgical processes is presented. Future trends, in terms of the control and optimization of hydrometallurgical plants, are then explored. The possibility of simultaneously optimizing plant design and associated process control system performance is discussed.

Jan 1, 1993

By H. H. Murray

Significant changes in ownership and production of industrial clays have occurred since 2000. Clays covered in this presentation are kaolins, ball clays, smectites, (bentonite), and palygorskite (attapulgite)-sepiolite. IMERYS discontinued production of paper coating kaolins at their Cornwall operations and have expanded their kaolin production in Brazil. J. M. Huber sold their kaolin operation in Georgia to KaMin whose headquarters are in Ft. Worth, Texas. BASF purchased Engelhard?s kaolin and attapulgite operations in Georgia. ActiveMinerals purchased Southeastern Kaolin in South Carolina, Wilkinson County Kaolin in Gordon, Georgia, and Zemex Attapulgite in Quincy, Florida. Chemical Lime purchased Spinks Ball Clay Company in Paris, Tennessee. Most of the ball clays used in Italy and Eastern Europe comes from expanded operations in the Ukraine. Bentonite operations have expanded production in Wyoming and Montana because of strong demand for drilling mud, foundries, cat litter, and iron ore pelletizing. The production and exports of palygorskite in China continues to increase. Nanoclays utilizing sodium montmorillonite, palygorskite, and halloysite are actively being developed.

Jan 1, 2009

By F. F. Aplan

Prologue Antoine Marc Gaudin (Fig. 1) was truly a giant in the field of mineral processing, and his shadow is still cast long on our profession. "Tony," as his students affectionately called him (but never to his face), came to the United States in 1917 and enrolled at Columbia University where he studied under Professor Arthur F. Taggart. Later, as a lecturer, he wrote his classic comminution paper (Gaudin, 1926). This important work led to his appointment as an associate professor at The University of Utah, where he conducted highly original work on flotation fundamentals that is still widely quoted today (Gaudin et al., 1928-30). In 1929, he was appointed Research Professor of Ore Dressing at the Montana School of Mines in Butte. Shortly thereafter, he published his first book, Flotation (Gaudin, 1932). Because Gaudin could so quickly cut through the fog to get to the essence of a problem, this is still a valuable reference book. It is a valued part of my personal library, and I consult it frequently. Over the next decade, he conducted an outstanding graduate research program at Butte, but, more importantly, he honed his undergraduate lectures and produced the century's outstanding text in the field, Elements of Mineral Dressing (Gaudin, 1939). More than 50 years later, this terse book is still found to contain most of the elements of the discipline. Its sections on the

Jan 1, 1994

By John Stroiazzo, Bernard C. Aubé

Brenda Mines, located 22 km Northwest of Peachland in British Columbia, Canada was an open pit copper- molybdenum mine which closed in 1990 after 20 years of operation. The primary concern in Brenda's tailings and waste rock drainage is molybdenum at a concentration of approximately 3 mg/L. The mine drainage is alkaline and contains little or none of the typically problematic heavy metals. Given that the waters downstream are used for municipal water supply and some irrigation, a discharge limit of 0.25 ma molybdenum was imposed with specific water quality guidelines in the receiving creek. A review of all existing and potential molybdenum removal methods was undertaken prior to mine closure. The chosen process is a two-step iron co-precipitation with clarification and sand filration at a slightly acidic pH. A 4,000 usgpm (912 m3/h) treatment plant was constructed and commissioned in 1998, at a cost of $10.5M. The successful removal of molybdenum from the drainage water is explained with details on some design innovations and operational challenges encountered during plant start-up. Investigated sludge disposal options are discussed although the long term disposal scenario has not yet been finalised.

Jan 1, 2000

By R. L. Grayson, S. Yuan

A goal-programming-based, worker-scheduling model has been incorporated in the Mine Management Support System (MMSS) for assigning workers to prioritized jobs on a shift basis. In the model, the accomplishment of each regular and non-regular job is a goal, and the objective is minimization of the deviations from the goals. A number of coefficients are employed as premultipliers of the decision variables to address practical considerations associated with the utilization of workers and the requirements of jobs. This model is applied to a 41-worker problem.

Jan 1, 1992

By Sangwhui Cho

In comminution processes including crushing, grinding and pulverizing, the efficiency of the comminution system is very low. Since the early 1980s, research has been conducted to increase the efficiency of pulverizing mills. Additionally, the application of microprocessors and Personal Computers to process control have come into general use. Given appropriate models of the process and control algorithms, these systems can economically control comminution processes. The ring-roller type mineral pulverizer is known as an energy saving mill. In this study, a control strategy to increase the efficiency of this type mill is explained.

Jan 1, 1992

By J. M. Keane

The Solution Mining review arrived too late to appear in the May issue. Solution mining, in its broadest definition, includes all forms of leaching where a lixiviant solution is brought into contact with a metalliferous or non-metallic ore and the resulting pregnant solution is processed for recovery of the valuable soluble material. Technologies such as dump leaching, heap leaching, stope washing and in situ lixiviant solution injection and recovery fit into this definition of solution mining. A publication entitled the US Gold Industry (Dobra and Thomas) reflects the major impact that solution mining techniques have had on precious metal recovery. In 1989 (the last year for which statistics are available), the United States passed Australia to become the third largest gold producing country in the world after South Africa and the Soviet Union. It is estimated that when the final figures are in for 1990, the US will probably pass the Soviet Union in gold output. If the state of Nevada is ranked as a separate country, it will rank fourth in the world in gold production for 1990. A good proportion of this increase in gold production over the past few years can be attributed to the application of solution mining technology to low-grade, precious-metal-bearing material. Solution mining techniques have also made inroads in copper production. Many operations located at former underground mine sites employ in situ leaching as an adjunct to conventional dump and heap leaching practices.

Jan 1, 1991

By Half Zantop

While the Andean belt of Chile contains porphyry copper deposits of considerable economic importance, only one major and several minor deposits of this type have been discovered in neighboring Argentina. There are no obvious geologic reasons for the country's apparent paucity of important porphyry copper deposits. Instead, a lack of exploration because of poor accessibility and past inadequate mining legislation may partly account for this situation. Western Argentina has porphyry copper prospects ranging in age from late Paleozoic to Pliocene. Many of these prospects have host rock and alteration characteristics that are very similar to those of large Chilean deposits. The economic potential of many of these prospects has not been tested adequately by geoehemical, geophysical, or chilling programs. A recently enacted mining promotion law and updated mining code removes some past exploration obstacles in Argentina, and makes in-depth exploration and evaluation of' the county's porphyry copper potential attractive.

Jan 2, 1981

By John T. Awald

The Bradshaw Mountains of west-central Arizona cover an area of 1600 square miles and contain numerous old mines and prospects. The area has been geochemically sampled on a reconnaissance basis to relate mineralized areas to regional structure and rock types. Copper analyses of stream sediments have been classified and contoured to show the distribution of low background, high background, and low, intermediate and highly anomalous areas. Contoured results are compared to geology and known mines. Several prospecting areas are indicated.

Jan 1, 1970

By G. T. Lineberry, W. J. Wiehagen, L. L. Rethi

This paper discusses a practical method for enhancing the performance of mining work crews. The method, described as the Work Crew Performance Model (WCPM), seeks to define performance variability within similar tasks of an underground work crew. Key components of the WCPM include: •job definition through task analyses, •the ranking of job elements by perceived cost consequence, •observational techniques to establish performance baselines, and •cost linkages between adherence to task procedures and measures of consequence for noncompliance. The components of this model emphasize a reliance on learning from a veteran work force and using that information to reinvest in strategies to enhance safety and efficiency. These strategies are not limited to technological efforts but include consideration of the so-called "soft-skill technologies, " aimed at reducing variability in individual performance and at effecting a continuous improvement in overall system effectiveness.

Jan 1, 1996

By R. A. Wharton, Z. Yang, R. W. Smith

The electrokinetic and flotation behavior of the green alga Chlorella vulgaris was studied in the absence and presence of Pb(II), Al(III) and flotation collectors. It was found that the presence of Al(III) is necessary for good flotation of the organism, whether or not Pb(II) is present, when dodecylammonium chloride or sodium dodecylsulfate is used as collector. Best flotation using dodecylamine is at about pH 8, and best flotation when using sodium dodecylsulfate is at about pH 4. It appears because of the small size of the organisms that the Al(III) is necessary for flocculation to enhance bubble-cell contact and C. vulgaris removal from water. When N-dodecyl-2-aminopropionic acid is used as collector, good flotation occurs at about pH 4 without the addition of Al(III).

Jan 1, 1992

By David A. Gulley, William A. Vogely

INTRODUCTION The Scope of the Chapter This chapter discusses environmental regulation and closely-related public policies associated with mineral development in the United States. This chapter outlines the nature, extent, and amelioration of secondary effects of mineral development. It sketches the policy foundations of regulation; discusses the implementation of environmental law; describes land use conflicts and land management regimes; and surveys the costs and benefits of environmental regulation. Since regulations are subject to frequent change, the chapter emphasizes basic factual and conceptual material, rather than specific regulations. The goal is to familiarize the reader with the general nature of environmental impacts and mitigation which arise in the minerals industry, and with the issues surrounding the regulation debate. The chapter is organized as a series of sub- chapters. The first of these is a discussion of the conceptual foundations of regulatory policy. The second section summarizes the principal federal environmental statutes, and the implementation of such regulation. Following that, the third section summarizes the current state of knowledge regarding the types of environmental impacts associated with mineral development. This discussion, organized in a format similar to that used in environmental impact statements, can be thought of as a guide to reading and understanding such statements. Next, the fourth section surveys studies of the costs and benefits of environmental regulation. 'These empirical studies are evaluated in terms of the framework developed in the first section of the chapter. In the fifth section, the discussion turns to federal, state, and local approaches to land use control and siting, and the economic analysis of such conflicts. Included are discussions of the two principal forms of public lands mineral entry, the 1872 location patent system and the 1920 leasing approach. CONCEPTUAL FOUNDATIONS OF REGULATORY POLICY David A. Gulley The Role of Regulation in a Market Economy What is Regulation?: Regulation is the intervention of government in the activities of the private market. In a market society, the private sector is presumed to be the most appropriate economic agent. Given this presumption, regulation generally begins with a demonstration of persistent problems under laissez-faire in a given context. Environmental and related regulation occurs because the public believes the free market does not properly value environ- mental quality. In this section, concepts are advanced to aid the reader in understanding the government's role in this respect.

Jan 1, 1985

By F. F. Aplan

The material known as coal has a highly variable composition. As a consequence, coals show a great variation in their physical and chemical properties as a function of coal rank. The situation is further complicated because the preparation engineer must deal with raw coal, as mined. This is an assemblage of coal, upwards of 30% mineral matter and, typically, several percent pyrite. The kind and amount of the mineral constituents is also highly variable from source to source. A knowledge of coal rank and source location, and the kind and amount of associated impurities, is the first step in evaluating the response of a raw coal to preparation procedures. The raw coal must first be characterized before information from one source can be extrapolated to that of another.

Jan 1, 1988

By Louis W. Cope

Placer material, regardless of the value of gold, tin, titanium, diamonds or other value mineral it contains, remains worthless until the valuable constituent is separated from the bulk of the material. This separation is no mean task when considering that a gold placer containing 0.01 to 0.03 oz/yd3 of gold, which is the range of grade of typical placer deposits; yes, 1:3,000,000! It is a miracle that gold placer mining has ever been profitable. Added to the situation of minute quantities of gold are several other problems, such as the gold often being very finely divided, the association of boulders and clay, and running and/or ground water. As each placer deposit is individual and distinctive, many factors have to be considered in planning the method for gold recovery from the alluvial deposit. Previous chapters have shown that in the exploration and sampling stage, some knowledge of the amount of each size of coarse and fine material which occurs in the deposit as well as the size distribution of the discrete gold particles is determined. Unless informed to the contrary, as a general rule of thumb, plant designers will consider that 40 percent of the material will pass through a 5/8-inch screen or punched plate hole. Also that there may be an occasional nugget and normally considerable amounts of fine gold. The designer must

Jan 1, 1992

By John D. Batty

With the emergence ofbiooxidation as a viable process for the pre treatment of refractory gold ores, so have the number of publica­tions on this topic increased dramatically. To a novice in the field of biooxidation, the infonnation presented is often confusing and sometimes even incorrect. Infonnation has also been published that is misleading in that it highlights a particular feature of a process that is either totally irrelevant or of no consequence to the ultimate goal viz. achieving the maximum economical gold recovery. To assist a potential user of biooxidation in evaluating the available published infonnation some guidelines or considera­tions for some of the more important aspects are given, as well as some extracts from publications that demonstrate the manner in which information has been presented.

Jan 1, 1996