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By S. C. Tadolini

The use of resin-grouted cable supports to control large ground movements in several types of underground mines has increased substantially since being introduced in 1991. Cables offer several advantages over traditional support systems, having large support capacities coupled with the flexibility to be used in low openings. Cable slings have been designed to be installed on-cycle using no-spin technology or a two-piece unit that can be placed with hand-held drilling equipment. Additionally, yielding cable supports have been developed and are being used to control large amounts of movement in coal and evaporite deposits.

Jan 1, 1998

By Roy A. Grancher

Construction materials indeed face a dilemma...as does the building industry as a whole. A stop & go economy; a severe drop; in housing starts; lingering indecision over just what corrective steps are to be taken or to their degree of commitment; no less basic disagreement in regard to which of the, Nation's problems is really the most pressing -- inflation or recession? Optimism has become a rare quality these days. At moat the cautious view is that this new year will see a long, hard struggle back, with hopes that 1976 at least can truly mark a dual anniversary celebration for the United States and its economic health. Yet the paradox is that once recovery does return, those very construction minerals and materials --which in recent years have experienced the ups and downs of overcapacity, shortage, and now declining demand again-- will once more face the spectre of mass inability to service revived and growing needs for its product. Mounting costs, present marginal expansion investment, and substantial lead times required for new facilities to come into production, could well form a bottleneck to economic upswing. The result again can be another cycle of shortage-induced inflation, and with it continued gyrations within the demand supply relationships of the country's building industries.

Jan 1, 1975

By Edward C. Dowling

Froth flotation has been used industrially for many years to separate valuable minerals from their associated gangue constituents. Notwithstanding the significance of this process to the mineral industry, many of the engineering tools needed for the evaluation of the flotation process are still in a developmental stage. Traditionally, the evaluation of a flotation test on both the laboratory and industrial scale has been based largely on a rougher recovery value achieved at a sufficiently long time to give a "final" or "equilibrium" recovery value. The assumption of a time equivalency for a given recovery value between various flotation tests or between laboratory tests and industrial operation underlies this method of evaluation. Such an assumption implies that flotation is an "equilibrium engineering process" and that the time-rate recovery of material from the flotation cell is not affected by changes in the flotation system. It has been shown by Bushell (1) and by Klimpel (2) that the assumption of time equivalency between various flotation tests is unjustified. Consequently, better tools are needed for evaluating flotation test results, Because mathematical flotation models which incorporate both a recovery and a rate function can completely describe flotation time-recovery profiles, they can provide an excellent tool to evaluate flotation tests.

Jan 1, 1984

By M. Moats, I. E. Paschalidou, K. Awuah-Offei

Tellurium (Te) is a rare metalloid that is predominantly produced from the treatment of anode slimes formed during copper (Cu) electrolytic refining. The US Government lists Te as one of the 50 critical minerals, partly, because of its use in thin-film photovoltaic (PV) technology. Given policy initiatives to increase Te production, it is important to evaluate the life-cycle environmental impacts of Te recovery as a by-product of Cu processing. The literature contains a few specific life cycle assessment (LCA) studies of groups of metals that include Te without proper regard to impacts per life-cycle stage of Te production or the effect of allocation on the results. This study builds an LCA model of the production system of Te from anode slimes treatment to evaluate the effect of allocation on life-cycle impacts. We build life cycle inventories using data from the Ecoinvent v3.7.1 database, literature, and engineering calculations and allocate impacts in proportion to products’ mass and economic value. The results show that economic value-based allocation yields greater impacts than mass-based allocation indicating the significant effect of the allocation approach on life-cycle impact estimates.

Feb 1, 2023

By C. Flores

The most common experimental approach of studying one variable at a time while holding all others constant is extremely inefficient. Use of statistical methods enables engineers and scientists to obtain meaningful information with the fewest experiments, reducing cost and wasted effort. In particular, the Taguchi method can be more efficient than traditional full factorial experiment designs, as it can study more variables with fewer nuts, and it is more robust against process "noise." Taguchi designs are also simple to formulate and the results can be analyzed by simple PC spreadsheets. The role and benefits of using the Taguchi method in experiments to develop and optimize processes is discussed.

Jan 1, 1998

By Bror Nyman

Wide settlers are a way to decrease the linear velocities of advancing liquid phases. It has, however, been found unnecessary to risk a proper settler performance by building shallow settlers in order to avoid a so-called interface turbulence due to a too big difference between the linear velocities of the organic and the aqueous phase. This conclusion has been reached from tests using a large transparent settler model, where the behaviour of a clean interface between two advancing liquids has been investigated. Also in a more realistic case, making an organic in aqueous or an aqueous in organic dispersion to move between the liquid phases, no obstacle has been found to use a somewhat more deep and correspondingly ore slowly t10wing aqueous phase. Based on above findings, support can be given to a new trend to build the settlers slightly deeper than what has been typical for the so-called low-profile design. In this way, it is much easier to avoid an excessive air introduction and other severe difficulties, like those caused by crud moving from one stage to another. It is further shown, how gravity can be used to slow down and distribute a dispersion being fed into a settler of a VSF unit. Entrainment levels have been found to be reduced by a careful design of primary dispersion distributors and picket fences of the settler. Finally, it is demonstrated, how outlets from the side of the settler can be used to simplity interstage pumping and to decrease the rotation speed of any pumping device.

Jan 1, 1996

By Robert R. Unterberger

The purpose of this paper is to summarize the research of the past sixteen years on three distinct methods of probing into solid rock. The first method is to use radar of the appropriate frequency. The second method is to use sonar. The third method is of recent vintage and uses techniques of nonlinear sonar also known as parametric sonar. The first two concepts, that of radar and sonar, are common to most people. Very few have heard of nonlinear sonar. Each of the probing techniques were investigated in order to overcome deficiencies in the former technique. Each has its advantages and disadvantages. It should be emphasized that all of these techniques for probing (or seeing) into rock are used in mines, and generally speaking not from the surface. Only in very special cases, such as certain very dry parts of Egypt or Peru, or, for example, the surface of the moon, will these probing techniques work from the surface. The reason for the development of these probing techniques has been to alert miners to possible hazards ahead of mining. Such hazards may be (1) old (unknown) boreholes connected with high pressure water zones above, (2) fractures that might connect to the Gulf of Mexico above the mine, (3) water-filled fractures that threaten the safety of miners, or (4) the discovery of dry faults ahead that can disrupt the planning of future operations.

Jan 1, 1983

By J. L. Watson

n the U.S., lead has been produced via blast furnace processing for over a century, and the slags from that pyro-metallurgical process have been accumulating on industrial sites over that extended period. Lead blast furnace slags typically contain both lead and zinc compounds in an iron-silicate matrix, and it appears highly likely that such materials will have to be processed in the near future to meet with EPA regulations. Thus it is appropriate to investigate possible processing routes to render the slags non-hazardous and simultaneously to recover metal values to partially off-set the inherent high cost of processing such materials. There are two major processing alternatives: one being pyrometallurgical and the other hydrometallurgical. The research reported here investigates leaching/solution purification/recovery processes for lead and presents experimental data for the treatment of lead blast furnace slags from S.E. Missouri. The results of the research suggest that both lead and zinc can be removed effectively from the slag, and that metallic lead can be recovered directly from the organic extractant utilized for solution purification.

Jan 1, 1995

By VÍCTOR VÁZQUEZ-VÁZQUEZ, GUILLERMO TIBURCIO-MUNIVE, María M. Salazar-Campoy, JESÚS L. VALENZUELA-GARCÍA, OFELIA HERNÁNDEZ-NEGRETE

This study examines a process for the recovery of precious metals from difficult minerals that exhibit refractory characteristics to cyanidation: low extraction of metals and high consumption of leaching reagent. A mineral sample from Monte del Favor Mine, located in Hostotipaquillo, Jalisco, Mexico, was physically and chemically characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), fire assay and atomic absorption spectroscopy (AAS). Two stages of leaching were carried out, first to eliminate manganese from the sample using sodium sulfite (Na2SO3) as a reductive reagent along with sulfuric acid (H2SO4), and second to dissolve gold and silver with hydrochloric acid (HCl) and sodium hypochlorite (NaClO). The results show extractions of around 96 percent for manganese (Mn), 98.73 percent for silver (Ag) and 83 percent for gold (Au). The usefulness of high acidity and Na2SO3 to obtain better results in Mn and Ag leaching are discussed along with the roles that HCl and NaClO play in Ag and Au dissolution values.

By Edwin B. Wilson

Electric power generation remains the greatest market for coal in the United States. In 1967, about 272 million tons of coal, amounting to over 51 percent of total coal consumption, were burned to satisfy this nation's hugh demand for power. The size of the utility market is currently five times that of 1941 and continues to grow with the demand for more and more energy. A major reason for this strong market has been the ability of the coal industry to supply a superior product for combustion while maintaining competitive prices. Now that the coal industry is engaged in intensive competition with nuclear power for future energy demand, it becomes ever more imperative that superior coal products are produced. One important problem when burning some coals is a liquid phase corrosive attack on boiler tube metal in the superheater and reheater areas of the furnace where steam temperatures may exceed 1050°F.

Jan 1, 1969

A knowledge of airway friction factor (K-factor) is necessary to designing mine ventilation systems for least cost and optimum effectiveness. The friction factor used must be accurate and reliable to estimate correctly roadway resistances and pressure sources for required flows. Though the resistance to flow offered by mine airways has been an object of study over the last half century, no accurate relation has yet been established from which the prediction of the resistance of a projected airway can be made. In Kentucky, only limited and incomplete data on local K-factors are available. Therefore, there is a need for field investigations to determine these values in-situ for existing mining conditions. The author describes a study concerning K-factor that was carried out in ten coal mines, located in eastern and western Kentucky. The results of these investigations are presented in both tabular and graphical form.

Jan 1, 1991

By E. Galán

The largest Spanish kaolin deposits formed on granites occur in Galicia (NW Spain) due to a widespread kaolinization of Variscan granitoids. This paper provides insight of the origin of this kaolinization process on the basis of a mineralogical and geochemical study carried out in two kaolin deposits, presently mined to be used in the paper industry. Mineral composition of the deeply kaolinized rocks is dominated by well-ordered kaolinite with minor quartz, K-feldspar, mica (illite/muscovite), locally gibbsite, and traces of resistant accessory phases (rutile, ilmenite, zircon and monazite). The content and structural order of the kaolinite decrease with depth. Kaolinite formed by extensive replacement of feldspars (plagioclase). Differential mobilization of major and trace elements during kaolinization has been inferred by using a mass-balance approach. Significant amounts of Na, Ca and minor Mn, Sr, P and U were removed from incipiently leachable minerals (plagioclase and apatite), and K, Rb, Cs and Ba were released from K-feldspar and mica. On the contrary, Ti, Zr, Th, Hf and the REE are retained in the resistant trace minerals that are concentrated in the fine fractions of the kaolins.

Jan 1, 2010

By Suresh P. Babu, Joseph W. Leonard, Richard Muter, D. P. Sen

OUTLOOK FOR COAL UTILIZATION In 1975, about 650 million tons of bituminous coal and lignite mined in the United States was used to meet 55% of the primary energy input for electric power generation and 26% of the total industrial consumption.1 Even though this amounts to only 21% of the total energy requirements, it is believed that with the declining natural gas resources and uncertainty of liquid fuel imports, coal will assume a more dominant role in suppplying our future energy needs. A regional breakdown of the coal reserves of the United States along with their characteristics is shown in Table I. At present the United Stares Energy Research and Development Administration (ERDA) and the US Bureau of Mines (USBM) are financing extensive research programs in advanced mining methods and energy conversion processes. The increased demand for wal which may result from these research programs may also create large-scale environmental protection problems. As more and more coal is mined the production of undesirable coal fines and dust also increases proportionally. The USBM and the Environmental Protection Agency (EPA) research in this field includes development in the areas of instrumentation for qualitative and quantitative analysis of wal dust, protective devices, and dust collectors. Dust control by water sprays, steam, and foam are also being investigated. Other aspects of safety in mining include developing methane drainage techniques prior to coal mining, fire and explosion prevention, and neutralization and disposal of acid mine waters. It is the belief of coal technologists that when the emphasis shifts to coal as the primary source of energy. the existing methods of mining and preparation of coal must be improved considerably to supply large quantities of quality coal for energy conversion. It is the objective of the present large-scale research financed by ERDA to produce substitute fuels from coal. Large-scale gasification pilot plants are being constructed by Bituminous Coal Research, Consolidation Coal Co., Institute of Gas Technology, and the Pittsburgh Energy Research Center to produce coal gas of natural gas standards at 1,000 psig. The processes being adopted by these pilot plants are oriented towards recovering most of the sulfur from coal by absorbing H2S and its subsequent conversion to elemental sulfur. The environmental protection standards will be strictly followed in using the results of these pilot plants to construct large-scale coal gasification plants in the latter part of the 1970's. With the increasing awareness of the need for air pollution control, considerable research is being done to minimize sulfur dioxide emission from thermal power plants. Utilization of limestone and dolomite scrubbing systems and caustic treatment of stack gases have proved to reduce sulfur and nitric oxide emissions by about 90 to 96%.3 Currently, about 22 scrubbers are in use in the United States to reduce sulfur in stack gas emission. In the long-term, it appears that optimal combinations will be developed involving both advanced coal preparation technology and wet scrubbing. The sulfur compounds are converted either to elemental sulfur of sulfuric acid. Besides the sulfur compounds, the major byproduct of the coal utilization industry is the large amount of coal ash. The Coal Research Bureau at West Virginia University has developed a practical use for coal ash as a structural material. The coal industry will undergo revolutionary changes when coal becomes the primary source of energy. New coal mining and preparation processes will be introduced to meet the ever-increasing per capita energy requirements. 2. BENEFICATION Introduction Coal preparation, like the beneficiation of ores, is also aimed at the separation of values from associated waste. Even though the unit operations involved when enriching ores and coal are similar, there are certain characteristics unique to coal preparation. Unlike the scattered and concentrated veins of underground minera1 ores, coal is distributed uniformly and very much in abundance in the coal mines. Coal occurs as the metamorphosed sedimentary deposits of vegetable matter, while metal and mineral deposits occur in great varieties of forms, structures, and origin-from igneous to sedimentary and metamorphic. The mined coal, being much more friable than mineral ores, is subjected to less intensive size reduction operations. Ores are usually ground to a very fine size for subsequent concentration, while coal is crushed to a coarser size, since considerably less liberation is needed to achieve the desired degree of separation. Since mineral matter is to a great extent discretely distributed in coal, concentration is mainly achieved by taking advantage of differences in specific gravity between clean coal and associated waste. In general, about 90% of coal is concentrated using specific gravity separation and about 10% by froth flotation. In contrast, these operations are frequently reversed in the beneficiation of ores. In coal preparation almost all fractions separated during various stages are made use of. while large amounts of gangue material are rejected in the concentration of ores. Hence, coal generally has a much lower ratio of concentration than ores. Since ore deposits are frequently more variable and mineralogically complex than coal, beneficiation of ore may require more plant flexibility and point-to-point quality control. This characteristic difference between the mineral ores and coal is attributed to the generally used one-step processing in coal as compared to the multiple-step processing of ores. Dewatering to enhance the energy content of coal is usually considered a major unit operation. Even though thickening and filtration are common for dewatering ore concentrates and cleaned coal, vibrating centrifuges and disk filters find unique application in the coal industry for achieving these types of solid-fluid separation. In coal preparation, thermal drying is carried out in separate units at the mine. While ore concentrates are usually dried at the smelter. Although the drying of ores is seldom considered dangerous, volatile matter and combustible dust are reasons why the thermal drying of coal can be hazardous. Open air storage of ores and mined coal results in partial oxidation. Unlike the oxidation of ores, the oxidation of the pyritic and carbonaceous constituents of coal together with the heat of condensation of moisture contribute to spontaneous heating and the subsequent combustion of coal in storage. Among the other significant difference between concentration of ores and coal are the weight and capacity of processing equipment. Coal processing employs less cumbersome, higher capacity units while the beneficiation of ores usually requires much more massive and frequently lower capacity equipment. Properties of Coal Which Influence Design The widely varying and heterogeneous composition of coal, due to metamorphism, determines the preparation design and uses of the resulting products. Petrography serves as a useful system of classification to identify the coal types present and their distribution. Early

Jan 1, 1985

By Konrad J. Banaszak

At least for the time being, these seems to be general but not universal agreement that Mississippi Valley type ore deposits formed entirely or in major proportion from heated connate brines (e.g. 1) Even with that agreement, major questions remain. I will present a coherent geochemical model and look at alternative views in the context of that model. The pattern of the following discussion is 1) the general geochemistry of the ore fluid, 2) the density-temperature relations and possible mechanisms of flow of those fluids, 3) the mechanisms of transportation and deposition of the ore minerals, and 4) a summary of a coherent model of genesis. The data equivocally define much about the deposits. The answer is still elusive.

Jan 1, 1979

By M. Ziegler

The article deals with the use of a digital twin in the assessment and optimization of a conveyor system in the Chilean copper mine. This example shows that a digital twin is initially just a new (albeit powerful) tool with which the system behavior can be examined. The benefits for the customer arise through the system identification and automatic detection of critical deviations from the target state. This knowledge allows mine management to react and coordinate operational and/or maintenance counter measures to insure optimal performance of their conveyor system. The information derived from the BeltGenius digital twin also allows mine management to gain a clear perspective of the overall efficiency of their conveyors, which will be invaluable for future conveyor component selections.

Mar 2, 2022

By J. S. Lee

Alkyl hydroxamates are well known collectors for oxide copper minerals as evidenced by the large amount of published literature. Our studies on a wide variety of copper ores from around the world have shown that alkyl hydroxamates will recover most of the "floatable" oxide copper minerals from an ore. They are available commercially, and they offer many advantages over alternative technologies for oxide copper recovery. In spite of this, the full potential of hydroxamates has not been exploited in the industry. The objective of this paper is to provide relevant practical aspects and guidelines to facilitate successful application of hydroxamates in operating plants. A critical analysis of the available information and data, based on several case studies, notation testing, and microscopic analysis indicates that alkyl hydroxamates can effectively recover well-defined oxide minerals of copper, but not copper occurrences such as Cu-bearing goethite (often misidentified as cuprite) which report as Acid Soluble copper in chemical assays. Prior to any notation testing with hydroxamates, it is necessary to assess the various modes of occurrence of Acid Soluble copper using microscopic and microprobe analysis.

Jan 1, 1998

By J. S. Carman

As with the slogans of Madison Avenue, catch words or phrases frequently become topical. Much is heard these days of the confrontation between governments of developing countries and international mining capital. In actual fact, sadly there are too few cases of anything as positive as confrontation because such an action at least signifies a dialogue which may begin badly but end up fruitfully. Instead we have in general a climate of indifference and fear with the mining companies of note marking off most of the developing world as being unsafe for investment. There is an unreal air to this damaging impasse. The common sense and objectivity which are prerequisites of positive action are lost in a swirling cloud of mythology, embraced largely by governments. Let us examine some of the dangerous misconceptions.

Jan 1, 1977

By Theodore H. Budd, Austin M. Cooney

The North Shore 9 Collector System comprised an integral part of the Milwaukee Metropolitan Sewer District's Water Pollution Abatement Program. The project required the construction of 1,490 m of tunnel, ranging from 1.5 m to 4.6 m in diameter along three separate alignments beneath arterial streets traversing Milwaukee's central business and cultural districts. This paper details the various aspects of the tunnel drives which were accomplished using two Lovat EPB type TBMs in conjunction with pipe-jacking procedures. Shaft configurations developed for the project, including ancillary subsidence mitigation components and portal pressurization facilities are discussed. Anomalies in observed soil behavior at variance with the parameters delineated in the project's geotechnical report are addressed.

Jan 1, 1991

By Theodore H. Budd, Austin M. Cooney

The North Shore 9 Collector System comprised an integral part of the Milwaukee Metropolitan Sewer District's Water Pollution Abatement Program. The project required the construction of 1,490 m of tunnel, ranging from 1.5 m to 4.6 m in diameter along three separate alignments beneath arterial streets traversing Milwaukee's central business and cultural districts. This paper details the various aspects of the tunnel drives which were accomplished using two Lovat EPB type TBMs in conjunction with pipe-jacking procedures. Shaft configurations developed for the project, including ancillary subsidence mitigation components and portal pressurization facilities are discussed. Anomalies in observed soil behavior at variance with the parameters delineated in the project's geotechnical report are addressed.

Jan 1, 1993

By Hun-Joon Sohn

Chemical metathesis and electrochemical reductive conversion of chalcopyrite in the presence of cupric ions were studied in sulfuric acid solutions for temperatures up to 90°C. The process results in the displacement of iron in the chalcopyrite lattice by copper ions with rejection of ferrous ions to the aqueous phase. The rate of reaction was found to be very slow, requiring subsieve-sized particles for extensive reaction to occur. The reaction was insensitive to copper ion concentration. Stirred ball milling of chalcopyrite introduces lattice strain. The reaction rate with strained particles was markedly higher than with annealed chalcopyrite. The reaction rate was found to be diffusion-limited, showing two distinct reaction stages corresponding to the formation of CuS (covellite) followed by Cu1.8S (digenite). The experimental activation energy for the first stage was 102 J (24.4 kcal) and the second stage 123 3 (29.4 -kcal) per mole. The rate-controlling process is diffusion of lattice ions, probably iron. The enhanced rate after milling is attributed to a recrystallization process which provides new paths for diffusion along dislocations and grain boundaries.

Jan 1, 1984