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By N. A. Abdel-Khalek

An experimental study was carried out to compare the results of laboratory column flotation versus conventional flotation for the cleaning of fine coals of different rank and their oxidized samples as well as discrete size fractions. Surface oxidation caused a significant reduction in the flotation yields achieved with both methods. However, the column flotation produced concentrates? of lower ash content. The recovery -size curve achieved with column was similar in shape to that obtained with conventional cell, with superior results in the region of fine fractions. The influence of some column operating parameters was also discussed.

Jan 1, 1990

By Byron C. Hardinge, E. R. Palowitch, Albert W. Deurbrouck, David J. Akers, Edward R. Torak

During 1983, 42.2% of the 686.0 (624.3 Mt) million tons of coal reported, 289.6 (263.5 Mt) million tons were mechanically cleaned, of which 107 (97.4 Mt) million tons were cleaned by dense media (magnetite and sand) processes.' The percentage of bituminous coal and lignite cleaned mechanically by dense medium processes increased from 7 to 38% between 1938 and 1983. The Electric Power Research Institute estimates that 150 million tons (137 Mt) of coal were cleaned by heavy-media processes in 1986, and that this number may increase to 265 million tons (241 Mt) by 1990.2 Dense medium separations include those coal preparation processes that clean raw coal by immersing it in a fluid having a density intermediate between clean coal and reject. As there is a general correlation between ash content and specific gravity, it is possible to achieve the required degree of removal of ash-forming impurities from a raw coal by regulating the specific gravity of the separating fluid. Dense medium processes generally offer the following advantages over other coal cleaning processes: • Ability to make sharp separations at any specific gravity within the range normally required even in the presence of high percentages of raw coal whose specific gravity is near the specific gravity of separation. • Ability to maintain a separating gravity that can be controlled within + 0.005 sp gr units. • Ability to handle a wide range of coal sizes. • Ability to change specific gravity of separation to meet varying market requirements. • Ability to handle fluctuations in feed, in terms of both quantity and quality. Unfortunately, dense medium processes can have the following disadvantages: • Relatively high capital costs caused primarily by the need for equipment to collect and recycle the medium. Relatively high operating costs caused primarily by operation of medium recycle equipment and loss of medium.

Jan 1, 1991

By K. F. Jakob

Sustainable development is a principle for the way we should act in the present. It ensures also options for the future to achieve a balance between social, economic and ecology development. The efficiency of raw material utilisation is being enhanced through technological developments, starting from extraction through all the following stages of the value creation chain. The use of domestically produced resources helps to assure the technological know-how. Additional indicators being collected and published by individual companies are questionable in countries with a tightly regulated legal framework such as in Germany, but make sense in developing and threshold countries. Sustainability in terms of efficient use of raw materials will manifest itself at the next stages of the value creation chain. Examples for efficiency improvement can be found in the steel, the power generation and agriculture industries. The approval procedures for German mining operations entail an internationally extremely strict assessment of the potential impact on the environment. All the mining activities include remediation and recultivation where the practise in Germany has become model character by international levels.

Jan 1, 2005

By Z. Hajnal

Three years ago a research program was initiated at the University of Saskatchewan to develop seismic surveying techniques for use in the Precambrian geological environment. The success of the reflection method in many younger geological settings suggested that this is the technique which would be the most suitable for experimentation. A successful adaptation of this technique to the Shield environment would make mapping of rock formations possible to much greater depth than is possible at the present time with any other applied geophysical technique. This presentation attempts to illustrate the advances which have been made in this program and will provide some insight into future plans. The field investigations were limited to the Flin Flon basin near to the town of Flin Flon, Manitoba (Fig. 1). This area was chosen because the surface geology has been mapped in great detail and it is a very important base metal producing region. It is an ancient sedimentary basin with some characteristics similar to areas where the reflection method has been successful.

Jan 1, 1976

By Dominique Francois-Bongarcon

The world mining industry is facing a severe recession. Thus, it is time to recall the value of geostatistical methods which were formerly developed as a money-saving and productivity-increasing tool. The situation has worsened, but the techniques of geostatistics have dramatically changed. Up to millions of dollars can be saved during exploration with simple use of variograms; then, during reserves estimation with kriging methods; and finally, with the parameterization of reserves, when evaluating a project and optimizing its global mining parameters.

Jan 1, 1983

By Patrick Ph. D. Kennedy, Osvaldo A. Ph. D. Bascur

With the revolutionary progress in information and computer technologies, applying the latest information technologies in metallurgical complexes has become a serious challenge to both a major opportunity and a serious challenge to both management and technical teams. The emerging component and object technologies are changing the way everyone can beneficially use their computer and networks to add to their corporate bottom lines. Most mining and metallurgical plants use predictive maintenance policies based on statistical analysis and special techniques, like vibration analysis and oil and lube analysis for critical equipment. Process control strategies are installed in several metallurgical sites. All process equipment and control strategies require maintenance from local personnel at the mine. Integrated use of existing and emerging technologies is making it possible to implement an overall process effectiveness control index. This index is based on key indices such as losses due to plant availability, performance efficiency and rate of quality. The availability of real time and process history to identify the most critical part of the processing system from mechanical integrity is highlighted. An emerging plant integration paradigm is described to simplify the implementation of business enterprise resources management and distributed plant management systems.

Jan 1, 1998

By Bruce R. Sutherland, Jim B. Ramsden, Gerry L. Bolton

Conductive metal powders are important building blocks for today's micro-electronic circuitry. Formulated into inks, they provide the interconnects needed to complete a complex integrated circuit and the means to enter the world of miniaturization. Traditionally, the inks have been based upon expensive metals such as silver, palladium, platinum and gold because of their excellent electrical conductivity and resistance to corrosion and oxidation. The use of a copper based ink, as an alternative to precious metal inks, recently has received considerable attention. Instability in the prices and limited supply of certain precious metal systems have driven up production costs, making the development of a lower cost copper system more attractive to manufacturers. However, lower production costs are on1 y real ized if performance and reliability can be maintained. While the development has been driven by cost, copper does offer some significant performance advantages over noble metal systems: conductivity as good as silver and 4W better than gold; leach resistance better than silver and equal to gold; stability at high frequencies better than gold or silver; strong film bonding characteristics; and compatibility with most solders. These benefits, however, do not come without cost. The inherently reactive nature of pure copper, while providing unique performance properties, makes it difficult to process. Unl i ke precious metals which can be fired in air, copper would oxidize and so requires special furnaces and atmospheres. Despite these difficulties, the transition from precious metal thick film systems to copper is gaining momentum. Manufacturers of high density, high performance circuitry are exploring the performance advantages of copper over gold and silver and the manufacturers of consumer products are considering the potential cost savings of copper over silver-palladium. Sherritt has developed a fine copper powder for this industry. Through association with the ink manufacturers, it has been found that performance properties of the ink vary with the physical and chemical characteristics of the powder. Production Process The production of very fine copper powders at Sherritt is based upon the disproportionation of cuprous ions as outlined in Equation [1] (1).

Jan 1, 1990

By A. Bergmann

Location The Meggen Mine and the concentrator plant of the "Sachtleben Bergbau G.m.b.H." are located in the southern part of the Ruhr-district of the Federal Republic of Germany. The mine has been in operation for more than 100 years, but the concentrator described in this paper was built in 1962 and started up in January 1963. Goelogy and Mining The Meggen ore-body is of sedimentary origin and occurs in a zone of limestones, graywacke and shales of Devonion age. The average thickness of the deposit is 3 meters and, due to an intense folding of the area, the mineralized zone dips very steeply at 800 toward the north. The ore consists of 85 percent of sulfides and 15 percent gangue that mainly contains silicates from the host rocks. The principal ore minerals are pyrite (67 percent), sphalerite (16 percent) and galena (2 percent) with minor amounts of marcasite and only traces of chalcopyrite. As shown in Fig. 1, the sphalerite and galena are very finely disseminated in the massive pyrite of the Meggen ore, and a very fine grinding combined with a special flotation technique are required to liberate the valuable sulfides and to produce separate concentrates of lead, zinc and pyrite. Mining is performed by the sub-level stoping method and employs trackless equipment. Present operations provide ore from the 600 meter level. Annual ore production is 870,000 metric tons.

Jan 1, 1972

By D. P. Patil, B. K. Parekh

Water is the mainstay for beneficiation of fine size coal and minerals; however, it is also the least desirable constituent in the final product. The basic concept of the novel process described in this paper is based on the differential surface heat conduction/ absorption capacity of individual particles, which differs for different species of minerals. When a mixture of fine material is exposed to a radiant energy source, the various solids present in the mixture will absorb heat energy depending on their heat-conducting properties and there will be a difference in the surface temperature of the particles. When this differentially heated solid mixture is placed on a moving belt, which is coated with a low temperature melting resin, the hotter component of the mixture will stick to the belt and relatively cooler particles will stay free on the belt and fall off at the end of the belt run. Experiments were conducted with pyrite, coal, and quartz of 6 × 18 mesh particle size. The goal of the test program was to find the optimum conditions at which there exists a required temperature difference between minerals and coal particles by controlling the operating system variables. Preliminary tests results showed that there is a potential for separating mineral matter from coal using the thermo-adhesive separation technique.

Jan 6, 2022

By Benno Ring

"When designing segmental lining at a cross passage, modern solutions try to bear the loads transferred around the opening within the rings by using shear elements in the ring joints. Commonly used shear systems providing coupling are cam & pocket, shear keys, bicones and steel dowels. These solutions have advantages and disadvantages, but most importantly they have limits in their capacity to stabilize the lining at cross passages. With the help of 3D-FE-analyses for an opening of one segmental ring these different solutions are compared taking various ground conditions into account. As a result the capacity of the individual system is determined. Notice is made regarding the applicability of the system as well as the consequences for the design and the verification. INTRODUCTION The design of the lining at a cross passage is among the most difficult tasks when designing TBM-tunnels. At one time the bedding of the lining disappears due to the excavation behind the lining, at another the ring-structure is interrupted when parts of the lining are removed for the opening. The trick is to transfer the loads around the opening into other segments and to areas of the lining which are still supported by the ground. In the rings immediately at the cross passage this creates a distribution of forces within the segments that strongly deviates from that of the regular lining. The design needs to consider the boundary conditions of the respectively chosen solution for stiffening of the opening and its peculiarities in the modeling as well as in the verifications. In the past segments of steel or an internal strutting of steel (DAUB 2013) placed around the later openings were commonly used, see Figure 1. The application of a strutting from the outside to the rings is restricted to such circumstances when for example a connection from a shaft to the tunnel can be made in suitable ground conditions (Ring and Glomp 2012). Though steel segments provide a robust solution, they are expensive due to their laborious manufacture, the high proportion of construction steel required and the time consuming installation in the tunnel (Häfliger 2013). A strutting of steel requires extensive design and verification. The resulting structure usually weighs several tons and must be erected as well as demounted within the confined space of the tunnel, requiring suitable transport and assembly equipment. The cross section remains restricted, thus causing a bottleneck for TBM operations and hindering the works and installations for the cross passage works."

Jan 1, 2016

By M. Machina

Anew approach to the use of projectiles for rock fragmentation uses recently-developed technology to optimize projectile shape and composition to achieve the desired type of breakage. Projectiles can also be made of various materials, as determined by the requirements of downstream processes. This paper describes laboratory tests with an 21-mm (8-guage) gun, and field tests with a 60-mm cannon.

Jan 1, 2003

By Ruiren Jin

In alkaline pulp, galena is depressed by sodium carboxymethyl cellulose (NaCMC), while Cu(II)-activated sphalerite exhibits a high flotability so that satisfied separation can be achieved. In addition to hydrogen bonding, chemical bonding of NaCMC with galena is confirmed by IR; only hydrogen bonding is involved between NaCMC and Cu(II)-activated sphalerite. It is also found that the greater the degree of substitute and polymerization of NaCMC, the stronger the depressive effect of NaCMC and that lower stirring speed favors the depression.

Jan 1, 1987

By R. L. Pozzo

A previous investigation showed that corrosion currents estimated from polarization curves for the pyrrhotite-grinding media system under abrasion correlated well with corrosion currents estimated from marked ball wear test data by applying the Faraday's Law. Freshly abraded metal debris were magnetically attracted to pyrrhotite and lowered the rest potentials of the mineral particles, thereby affecting the corrosive wear. The investigation was extended to explore the interactions between a nonmagnetic sulfide mineral, pyrite, and abraded metal debris and their effects on the corrosive wear mechanism. The electrochemical behavior of a three-electrode system involving pyrrhotite, pyrite and grinding media was also investigated as a first step towards elucidating the nature of interactions that occur in the grinding of complex sulfide ores.

Jan 1, 1987

By Charles J. Kucera

Today's highly publicized issues of resource development and environmental protection are not new. But recently these issues have been played one against the other, and some would have us believe they are mutually exclusive. Why? Because modern man has realized that the shortest route to achieving economic progress is to subdue nature. He extracts mineral resources from the earth to provide the raw materials upon which other processes and services are based. But often in his search for economic progress he finds that other highly- held values (e.g., an unspoiled environment) have been violated. The natural response is a counter action - to attempt to protect nature. But this response is basically unsatisfactory because it is reactive.

Jan 1, 1979

By J. H. Fowler

Canada's gypsum industry began over two hundred years ago in the Maritime Provinces when farmers attempted to supplement their incomes by selling "land plaster" to traders bound for the United States. Rising from such humble beginnings, gypsum now contributes significantly to the economies of nine of Canada's ten provinces. Thirteen open-pit and three underground mines produced a total of 8.38 million tonnes of crude gypsum and seventeen processing plants manufactured 2.49 million tonnes of finished products in 1985. Recent economic growth in North America has resulted in steady increases in gypsum production, however, competition from foreign producers and by-product gypsum poses a growing threat to Canada's gypsum mining industry.

Jan 1, 1987

By F. Habashi

Chile is at present the largest copper and rhenium producer and was before World War I the largest nitrate producer. She is also an important producer of lithium carbonate and molybdenum oxide. An important event in the history of the country is the Pacific War of 1879-1883 in which she acquired the northern provinces initially belonged to Bolivia and Peru. In 1888 Chile annexed Easter Island. The Chilean mineral and cultural history is briefly reviewed together with the people who contributed to her development. The present report is the result of a number of academic and industrial visits to Chile during the period 1992 to 2009.

Jan 1, 2011

By Ulrich Kappus

The purpose of the project is to divert flood flows of North Potato Creek. The project is located in the southeast corner of Tennessee near Copperhill, approximately 160 kilometers north of Atlanta, Georgia. The project consists of: a 28-meter high dam, a 90-centimeter diameter outlet conduit; an emergency spillway; and a 4.0-meter diameter hard rock trans-basin diversion tunnel. This floodwater management system was part of Cities Service Company mine safety program for the Cherokee orebody which is partially located within the stream channel. The following paper describes the entire project development from feasibility studies to design and construction management.

Jan 1, 1978

By P. D. Pattillo, J. B. Cheatham, Y. -H. Lin

The stability of a hemispherical cavity, intended to model a perforation opening in the vicinity of a borehole, is analyzed for the case of poroelastic-plastic material behavior. Two plasticity models of differing complexity are considered, with the emphasis in either model being the use of strain softening to calculate inelastic stiffness. Sample results illustrate the effect of steady fluid flow on the response, and possible collapse, of the near perforation region.

Jan 1, 1986

By David R. Delling

Tenneco is a large, diversified, energy-based company which has grown rapidly during its forty year life. We're the youngest corporation among Fortune's top 20 companies. Tenneco Minerals Company is the division of the Corporation responsible for nonfuel minerals exploration, development and operations. Tenneco Minerals Company is headquartered in Lakewood, Colorado. Exploration offices are in Colorado, Nevada, Alaska, and Perth, Australia. We currently operate two gold mines in Nevada and a large underground trona mine and soda ash processing plant in Wyoming. The latter has a capacity of 907 000 tonnes per year of soda ash and is the subject of my presentation today.

Jan 1, 1984

By Donald G. Wieland, James H. Meinholz

INTRODUCTION The Milwaukee, Wisconsin Metropolitan Area provides an ideal opportunity to review the advancement of the art and science of mixed face tunneling in the past 65 years. Although there were earlier tunnel projects in the Milwaukee area, by other agencies, the majority of those driven in the Twentieth Century have been done under contract with the Milwaukee Metropolitan Sewerage District through the agency of the Sewerage Commission of the City of Milwaukee and the Metropolitan Sewerage Commission of the County of Milwaukee. Legal Description of District The Milwaukee Metropolitan Sewerage District was created by the Wisconsin Legislature in 1921 together with the Metropolitan Sewerage Commission of the County of Milwaukee. This concept of subregional wastewater control was an outgrowth of an investigation and report from a commission appointed by the Common Council of the City of Milwaukee in 1909 to study final sewage disposal for the City. In 1911 that Commission, comprised of J. W. Alvord, George C. Whipple and Harrison P. Eddy, recommended that the City construct a water filtration plant, construct a Menomonee River flushing works, expand the intercepting sewer system and, after a thorough study of the then existing and developing methods of sewage treatment, construct a sewage treatment plant. In response to those recommendations, the Wisconsin Legislature, in Chapter 608 of the Laws of 1913, created the Sewerage Commission of the City of Milwaukee. Recognizing that the improvement of surface water quality would require action on a watershed basis, the Legislature, in Chapters 554 and 590. of the Laws of 1921, created the

Jan 1, 1979