Due to the increasingly complex mineralogy, and lower grade of many current ore reserves, technology has, over the past decade, had to evolve rapidly to treat these materials economically in an industry which has undergone severe periods of recession. However, most of the technical innovations, such as the increasing use of solvent-extraction, ion-exchange etc., have been in the field of chemical ore processing, and, apart from the use of computers and ever larger unit process machines, there have been few major evolutionary changes in the field of physical mineral processing, where conventional crushing and grinding methods, essentially unchanged in half a century, are followed by the 'old-faithfuls'- flotation, gravity, magnetic and electrostatic methods of separation. Many of these techniques have major limitations in the treatment of 'new' ores such as complex sulphides, and the main purpose of the NATO Advanced study Institute (ASI) "Mineral Processing at a Crossroads" was to review the future of mineral processing. One of the great failings of physical methods is their inability to treat ultra-fine particles, and much research effort is required in this area. Flotation is still the most widely used and researched method for separating minerals, and is the only method which can be used to produce separate concentrates from complex sulphide ores. However, its performance on these 'modern' ores is poor, and it is in this area particularly that chemical methods will increasingly be integrated into plant circuits.

This book treats magnetic separation from the point of view of both the engineer in the field who operates magnetic separators and the research scientist in the laboratory. It emphasizes those aspects of magnetic separation where lack of support in fundamental research is most evident. The intention is to bring the engineer and the scientist closer together, to promote the application of basic physical phenomena in engineering practice, and to gain the acceptance of the industry. The book presents a fairly broad survey of magnetic separation as applied to and practised primarily by the mineral-processing industries, although its use in other industries is reviewed briefly. It includes information on the physical principles of magnetic separation, magnetic properties of minerals and their measurement, the generation of magnetic field, theoretical and practical problems of magnetic separation, and experience gained in the design and operation of magnetic-separation systems. In detail, the book consists of six chapters dealing with the following topics: The Physical Properties of Magnetic Separation, Review of Magnetic Separation Techniques, Theory of High-gradient Magnetic Separation, Practical Aspects of Magnetic Separation, Industrial Applications of High-gradient Magnetic Separation, and The Economics of Magnetic Separation. The six appendices deal with symbols, abbreviations, values of physical constants, conversions from one unit to another, definitions of derived units, and a list of selected equipment manufacturers. There is a comprehensive bibliography (almost 600 items) and a subject index. The book should be of value to engineers and consulting metallurgists, as well as to students who want to learn more about this branch of technology. It attempts to meet the needs of the growing number of engineers, technologists, and applied physicists who are engaged in the practical exploitation of magnetic separation.

This book reflects changes that have occurred during the last two decades in theoretical understanding and practical implementation of magnetic techniques in materials treatment. Research and development needs, based on the current strategic thinking and on principles of sustainable development are outlined. Development of magnetic separators based on powerful permanent magnetic materials, construction of reliable superconducting separators, design of efficient eddy-current separators and industrial implementation of magnetic carriers and magnetic fluids are examples of innovative changes that have taken place during the last twenty years. The book reflects the current technological trends and re-positions the research, development and practice of magnetic methods of material treatment in such areas as minerals beneficiation, recycling, waste treatment and biomedical and clinical applications.

Removing molybdenite from chalcopyrite by flotation has long been a challenge due to their similar floatability as sulfide minerals. However, the difference in the magnetic susceptibility of the two minerals may be employed to address this challenge. Recently, pulsating high-gradient magnetic separation (PHGMS) has been reported effective as an environmentally friendly and economical strategy for separating chalcopyrite from molybdenite, but the mechanism of their magnetic difference is unclear. The current investigation employed crystal field theory and density functional theory calculations to theoretically elucidate the magnetic properties of these two minerals, and their difference was further demonstrated by experimental investigations. Under optimized conditions in a SLon-100 cyclic PHGMS separator, a chalcopyrite concentrate assaying 31.47% Cu and 0.44% Mo at 81.93% Cu and 5.56% Mo recoveries was produced from a pure chalcopyrite-molybdenite mixture that initially contained 26.29% Cu and 5.42% Mo. After the separation process, the Cu grade decreased to 15.06%, whereas the Mo grade increased to 16.22% in the nonmagnetic product. These findings have potential implications for the separation of chalcopyrite from molybdenite using PHGMS.

This book includes 12 papers from around the world on topics related to physical separation and enrichment in mineral processing. Physical separation is commonly used in the mineral industry to separate valuable minerals from gangues using differences in their physical properties. Physical separation methods have several advantages over other mineral processing techniques due to their high efficiency, low capital and operating costs, no additional chemicals required, and consequently, lower environmental hazard. They can be applied to the ores from mines or tailinsg, or in the recycling stage for scavenging the desired elements.