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By Richard R. Klimpel

INTRODUCTION Froth flotation is the most widely used and economic means of concentrating metal sulfide ores such as those containing copper, lead, zinc, nickel, molybdenum, and pyrite. Also recoverable are other metal species that are often associated with sulfide ores, such as cobalt, platinum, gold, silver, etc. Flotation of metal sulfide ores has been successfully practiced at the industrial scale for more than 50 years. It is the relative technical/economic ease of floating metal sulfide minerals that has been a major driving force behind the rapid expansion in the supply/demand of metals over this 50 year period. It is estimated that 1.6 billion tons of feed sulfide ores are processed each year in the free world based on the froth flotation process, Klimpel (1987) and the manufacture/use of associated chemical reagents is a major portion of the 1.5 billion dollars (U.S.) free world mining chemicals business, Klimpel (1988b). The use of froth flotation appears to be increasing partially due to the ever decreasing feed grades and liberation sizes of the feed minerals. Froth flotation has shown itself to be a flexible process that lends itself well to many solid/solid separations. Thus, with surprisingly little equipment modification, separations can involve very different particle sizes and densities, and relative weight ratios of materials to be separated. In addition, the flotation process is economic, especially when compared to size reduction, its associated precursor process. Flotation also lends itself to continuous operations with a variety of equipment configurations. Such operations exhibit an ability to vary feed rate of solid to the process by as much as 50% without a total collapse of separating efficiency. In addition, the widely used mechanical flotation cell is scalable from 2.8 to 57 or 85 m3 (100 to 2000 or 3000 cu ft) with surprising ease relative to other unit engineering operations over the same relative size increase. The separating medium used is water. Most of the chemicals required -- pH regulators, frothers, collectors, activators, and depressants -- are all relatively inexpensive and common. They are not usually used in large quantities. While there has been a tendency for the quality of metal sulfide ores in any one geographic location to deteriorate over time due to mining intensity, the overall global supply of sulfide minerals is still very ample. Thus, the physical supply side of sulfide ore concentrates has not been under strong technology improvement pressure with increasing metal demands. Part of this is due to the ability of capital to consistently move to new geographic sources having suitable-grade sulfide ores. In these moves, the actual froth flotation technology used (including collector chemicals) has had to change little. As an illustration of this trend, of the approximately 80,000 metric tons of thio collectors used commercially (1980) in the free world, almost 987 were known and manufactured in some form 25 years ago. This is clearly not typical of reagent development in other process-related industries. In addition, the industrial-scale practice of froth flotation applied to sulfide ores has proceeded since the 1920's with often little direct (predictive) scientific explanation due to the extreme complexity of the flotation process. Empirical testing has been a mainstay of industrial flotation reagent development and use. Even today there is often strong disagreement between researchers as to the mechanisms of chemical flotation practices that have been performed successfully on an industrial scale for many years. Thus the industrial process of froth flotation, especially as applied to the recovery of sulfide minerals, poses a dilemma: such a process is widely used, economic, versatile, forgiving, etc. and yet is still not very well understood in a mechanistic sense leading to prediction of results from fundamentals even after 50 years of usage. Lack of such predictive ability has not limited the general over-all industrial use of froth flotation in sulfide mineral recovery. Rather the lack of

Jan 1, 1989

By T. J. Fronapfel

Impacts to ground water from mining are being comprehensively regulated in Nevada through specific requirements for design, construction, operation, permitting and closure. This program is the nation's most comprehensive for control of activities at mining operations which have the potential to cause groundwater degradation. It encompasses virtually all types of facilities, including placer, physical separation, flotation, testing, leaching and milling. Minimum design requirements are established by regulation, and must be met by each facility. Site-specific monitoring requirements are established for each facility, and are heavily emphasized. Regulatory and technical requirements and relevant permit conditions are presented and discussed.

Jan 1, 1992

By Richard C. Smith, Steven H. Brown

Commercial scale in-situ leach uranium facilities (i.e., solution mining) have operated since late 1975, and have begun to appear in increasing numbers in the last few years. Solution mining involves the pumping of ground water, fortified with oxidizing and complexing agents, into an ore body, leaching and solubilizing the uranium in-situ, and then pumping the solutions to the surface where they are fed to a mill. Milling is by conventional means, involving ion exchange, precipitation, calcining and packaging processes. This paper presents an overview of the solution mining process, and discusses an empirical method that has been used to determine the radon gas release rate in Bq (curies) per year for the overall operation of the facility including wellfields, milling processes and waste storage reservoirs. In addition to radon generation on the surface from radium decay, it has been determined that the major component of radon release is associated with the dynamic generation of radon from solutions returning from underground. Process parameters impacting this evaluation and the mathematical expressions developed are discussed. The preliminary data accrued is presented.

Jan 1, 1981

By David Atkin

This paper presents methods and results of environmental planning conducted for a proposed coal and iron ore transshipment terminal which would be located on reclaimed land west of Lisbon, Portugal. Oceanographic, navigational, marine, structural, material handling, and financial studies of the terminal were conducted along with the environmental analyses. However, because of the proximity of the terminal to heavily used recreational resources, residential areas, and biologically valuable habitat, anticipating and reducing the environmental effects of the terminal to minimum levels was a very important part of the overall project. The results of the study indicate that even the impacts associated with worst-case conditions would be acceptable because of appropriate pollution control measures and planning.

Jan 1, 1983

By Walter E. Kramer

The advantages derived from the use of pellet burdens in blast furnaces are so great, that hematite ores are being converted into pellets in greater quantities each year. The conversion of these ores into pellets appears on the surface to be relatively simple. In reality, this is not so. Serious difficulties are encountered in drying these pellets that do not exist in the drying of taconite concentrate pellets. The ores that present problems are goethite and earthy hematites. Green pellets prepared from these ores have very law shock temperatures, 200-600° F. The shock temperature of a green pellet according to our definition is the highest initial temperature to which a green pellet may be exposed without suffering decrepitation. Decrepitation may involve spalling, fracturing or total disintegration. The poor shock properties of these green pellets result from the inability of the vaporized water to escape freely and easily as it is formed with¬out affecting the integrity of the pellet. As a consequence, the pellets must be carefully dried prior to induration. This careful treatment is costly. The slow drying process restricts productivity and requires larger furnaces than desired. The use of an additive to elevate the shock temperature of the green pellets would increase productivity. Bentonite is used in some pellet plants to improve balling but it raises the shock temperature only slightly. Nalco became interested in the shock temperature problem because of its activity in the development of organic pelletizing aids for taconite concentrates. The findings reported here are an outgrowth of our experimental work on the development of shock temperature additives.

Jan 1, 1967

By Milton F. Searl

Introduction The urgency of further development of our domestic energy resources becomes more apparent every day. The production capability of existing facilities, taken in the aggregate, declines perhaps 10% per year; imported energy is expensive if available at all; conservation helps reduce demand but eventually will reach a point of diminishing return; new energy sources are promising but past experience, as with nuclear power, teaches us lead times are long and success is not assured. To approach the energy future rationally, it is essential to have some idea of the size of the nation's remaining energy resources, their characteristics, and the degree of uncertainty involved in their estimates. Resources are, of course, only one end of a long chain leading to energy supply to the ultimate consumer. They are an essential element, however, and the only one not under society's control. Given that the resources and a national will to produce the energy exist, it is possible to convert the resources to supply in, generally, an environmentally reasonable manner. However, the process of developing supply takes time. Government must permit access to the resource, and remunerative prices and further evolution of technlogy are required. This paper does not deal with these essentials, but they must not be forgotten. This discussion is limited to coal, oil, natural gas and gas liquids, uranium, and oil shale. Other energy sources are discussed elsewhere in this issue. Crude Oil Conventional crude oil resources are of greatest concern today, given our dependence on imported oil and its rapidly rising price. Estimates of oil originally in place (OOIP) range from 619 billion bbl to 1,094 billion bbl, differing by almost a factor of two (Table 1). This is surprising because the U.S. is a mature petroleum province with over 120 billion bbl produced and over 400 billion bbl OOIP discovered. Differences in the estimates involve differences in the experience of the various estimators, the interpretation of present geologic information and historical statistics, the methodology, and probably the extent (i.e., water depths) for which offshore resources are included. The range shown for the estimate of a given estimator appears to be primarily due to geologic uncertainty. This uncertainty can be measured by taking the ratio of the low and of the high estimate to the expected estimate for that information source. The low estimates range from 0.85 to 0.87 of their respective values. The high estimates range from 1.18 to 1.27 of the expected values. In all cases the high estimate is further from the expected value than the low,

Jan 1, 1980

By Searl. Milton F.

Introduction The urgency of further development of our domestic energy resources becomes more apparent every day. The production capability of existing facilities, taken in the aggregate, declines perhaps 10% per year; imported energy is expensive if available at all; conservation helps reduce demand but eventually will reach a point of diminishing return; new energy sources are promising but past experience, as with nuclear power, teaches us lead times are long and success is not assured. To approach the energy future rationally, it is essential to have some idea of the size of the nation's remaining energy resources, their characteristics, and the degree of uncertainty involved in their estimates. Resources are, of course, only one end of a long chain leading to energy supply to the ultimate consumer. They are an essential element, however, and the only one not under society's control. Given that the resources and a national will to produce the energy exist, it is possible to convert the resources to supply in, generally, an environmentally reasonable manner. However, the process of developing supply takes time. Government must permit access to the resource, and remunerative prices and further evolution of technology are required. This paper does not deal with these essentials, but they must not be forgotten. This discussion is limited to coal, oil, natural gas and gas liquids, uranium, and oil shale. Other energy sources are discussed elsewhere in this issue. Crude Oil Conventional crude oil resources are of greatest concern today, given our dependence on imported oil and its rapidly rising price. Estimates of oil originally in place (OOIP) range from 619 billion bbl to 1,094 billion bbl, differing by almost a factor of two (Table 1). This is surprising because the U.S. is a mature petroleum province with over 120 billion bbl produced and over 400 billion bbl OOIP discovered. Differences in the estimates involve differences in the experience of the various estimators, the interpretation of present geologic information and historical statistics, the methodology, and probably the extent (i.e., water depths) for which offshore resources are included. The range shown for the estimate of a given estimator appears to be primarily due to geologic uncertainty. This uncertainty can be measured by taking the ratio of the low and of the high estimate to the expected estimate for that information source. The low estimates range from 0.85 to 0.87 of their respective values. The high estimates range from 1.18 to 1.27 of the expected values. In all cases the high estimate is further from the expected value than the low,

Jan 9, 1980

By F. Dingwu

The demand of manufacturing high-purity magnetite concentrate leads to the advent of various magnetic separators. A novel magnetic drum separator has been developed with an optimal permanent magnet system and a complex-forces field is adopted, involving magnetic force, gravitation, fluid resistance, friction, inertial centrifugal force, etc. Proper ultrasonic probes are inserted into the bottom tank to break up the magnetic floes. The performance of magnetite in the complex-forces field is described and the optimal operation conditions are suggested.

Jan 1, 1995

By Markus Thewes, Mario Galli

"INTRODUCTIONProject-related studies showed that lab tests are a helpful tool for the planning of EPB tunneling and soil conditioning in cohesionless soils. This type of ground commonly represents the extended application range for EPB shields, which demands for a treatment with additives. Considering soil conditioning with foam, so far, approaches exist for the investigation of the foam quality and of the conditioning behavior of soils (e.g. (EFNARC GUIDELINES 2001 2003)), but not any standards for testing procedures related to soil conditioning. State-of-the-art research on the topic is and was conducted for example in Bochum (Germany) cf. (Budach 2012; Maidl 1995), in Lyon (France) cf. (Quebaud et al. 1998), in Oxford and Cambridge (Great Britain) cf. (Borghi 2006; Peña Duarte 2007), in Delft (Netherlands) cf. (Bezuijen and Schaminée 2001), in Turin (Italy) cf. (Borio 2010; Peila et al. 2013; Vinai 2006), and in Aachen (Germany) cf. (Vennekötter 2012). Additionally, applied science is reported by the tunneling practice and suppliers of conditioning agents. Although the research focus in all these and further studies varied, similar test methods and test series were applied. A standardization of essential properties and testing methods (setup and procedures) however did not take place. The results from laboratory testing can only function as index values for practice because in the studies, production and application of the conditioning agents mainly takes place under atmospheric conditions. Nevertheless, the tests enable basic understanding of feasibility as well as processes and interactions going on during soil conditioning. For recommendations for standardized and reproducible testing see (Budach 2012; Budach and Thewes 2015).The most extensive investigations on the flow behavior of soil-foam mixtures have been performed by using the slump test from concrete engineering, cf. (DIN EN 12350-2 2009-08), which originally is applied on evaluating the workability of fresh concrete. Although this test does not describe the actual flow behavior, it rather represents an index on the workability, very much experience exists with this test method. Besides others, the workability – or flow behavior – of the EPB support medium certainly is a major factor of influence on the properties of the material in the excavation chamber and thus, for effective tunneling with EPB shields, cf. (Galli and Thewes 2014). For a summary of various investigations on the workability of conditioned soils using the slump test and resulting recommended slump ranges see (Budach 2012; Vinai 2006). Thereof, slumps between 10 and 20 cm have been reported as suitable workability for EPB applications. However, there is actually not much known about the real flow behavior of soil-foam mixtures related to rheological properties such as the viscosity (?) or potential yield stresses (t0). These physical values are necessary for a realistic determination of face pressure, for the design of required torques, and for an evaluation of the material flow at different locations in the excavation chamber, in the screw conveyor or on the conveyor belt. To generate a linear pressure distribution at the tunnel face, as it is assumed a priori, a low-viscosity fluid is favorable, whereas in the screw conveyor, a high-viscous fluid is needed for a controlled pressure decrease. On the conveyor belt, yield stress plays an important role preventing deliquescence and spilling from the belt. Attempts in characterizing the actual flowing of soil-foam mixtures have so far only been made by few researchers, the application of rheometry is rare."

Jan 1, 2016

By Patrick Doig, Ross Webb

The Bradshaw Section 5A Interceptor involves the construction of two miles of 108-inch, finished diameter tunnel in dry soils. Excavation is generally by Lovat TBM with ribs and lagging support. The tunnel is beneath a recreational parkway and stringent measures have been enacted to preserve the parkway and minimize disruption to the neighborhood. Apart from these constraints, the project would have been unremarkable but for the intervention of CalOSHA and the local fire department who ordered extraordinary fire protection measures. The paper discusses the cause and effect of these measures and comments on the potential repercussions for other projects.

Jan 1, 1999

By R. L. Grayson, S. S. Peng

Sampling of respirable dust and analyses of samples have been partially completed for a longwall panel. Physical and compositional properties which have been characterized include: 1. Respirable mass concentration, 2. Mineral composition, 3. Particle size distribution by mineral, 4. Particle shape distribution by mineral, 5. Particle angularity distribution by mineral, and 6. Respirable size distribution. Analytical techniques used in the characterization of samples are described, and results are reported with emphasis placed on relationships between the various characteristics and worker locations. Details of existing mining conditions, equipment arrangements, dust control methods and operating system parameters are presented.

Jan 1, 1986

By Maxine Wiber, Ross D. Gallinger, Brain A. Lewis

Poirier was an underground copper and zinc mine located in Northern Quebec that operated between 1965 and 1975. There are 5 million tonnes of acid-generating tailings, which have contributed acidity and metals to the Kananewesig and Kistabiche Creeks. The final closure plan incorporates the placement of all reactive material into the tails basin, installation of a geomembrane liner over the tailings deposit and a one metre soil layer to protect the liner. The environmental effect of the residual seepage was assessed from an ecological risk perspective. The Reclamation Plan has been accepted, and work commenced in 1998 to restore the site.

Jan 1, 2000

By Richard L. Patterson, Alan P. Finch

Twenty years ago, when tunnel projects in the UK were generally procured by the public sector, many were completed late and over budget. Now a significant proportion of new infrastructure is developed by the private sector. Seeking more certainty in cost and programme, promoters have tried new and radically different methods of procurement and contract forms. The paper will review these developments, then examine the approach adopted for some of the largest current UK tunnelling projects (both in the public and private sectors) including the Channel Tunnel Rail Link, the Heathrow Terminal 5 Development and new highway tunnels.

Jan 1, 2003

By Gunter Zimmermeyer, Hartmut Eicker

Radon in the Environment Radon, as a natural nobel gas, can be detected nearly everywhere in the environment as a decay product of ubiquitous uranium. As it is emanated from soil and rocks measurable concentrations have been found at the surface of soils and in even higher concentrations in enclosed spaces like, for example, mines and buildings. While above soil surface activities caused by radon have been found in an order of magnitude of up to 1 pCi/l (Weigel, F. 1978), concentrations in enclosed spaces and mines are higher because of the lack of atmospheric circulation. Beside air circulation the relevant figure depends on the Ra226-concentration in the surrounding rocks or building material, as well as on emanation coefficient and the diffusion coefficient. While representative Rn222concentrations in well ventilated buildings are reported to be in an order of magnitude of 1 pCi/l maximum values up to one order of magnitude higher have been found in badly ventilated brick buildings (Ettenhuber, E., Lehmann, R., Clajus, P., 1978) (Aitken, J.H., et al., 1977). Just now it was stated that the reduced air circulation due to German legal regulations on energy conservation will increase radon exposure of the public considerably (Jacobi, W., 1979). Radon in Mines Radon exposure of workers is, of course, a matter of concern in uranium ore mines where relatively high concentrations of the uranium to be mined are present. Measures to protect workers' health have been implemented, based on experience on dose-effect relationship. They serve to meet exposure standards by limiting inhalation of radioactive particles, in reducing radon concentrations or in limiting working hours. Both improved measuring devices and capacity as well as the lower discrimination threshold enable to measure radon concentrations in other mines, e.g. in coal mines. It is known that radioactivity in coal is small compared with that in other minerals and even soil, rocks. Nevertheless, radioactive elements were identified in coal and so the question was whether the concentrations of radon in coal mines might be a subject of concern. The problems encountered when measuring radon in coal mines are described below, as the measuring device has to be flame proofed which is an important additional requirement. Measured radon concentrations in British coal mines have already been published (Duggan, M.J., Howell, D.M., Soilleux, P.J., 1968 (Dungey, C.J., Hore, J., Walter, M.D., 1978). The authors found concentrations of up to 14 pCi/l in Cornish mines. In most cases the values were in the order of 2 pCi/l. These results were consistent with measurements reported from U.S.-coal mines (Lucas, H.F., Gabrush, A.F., 1966). Such concentrations of radon were not considered to represent a hazard for British miners (Ogden, T.L., 1974). In Germany, too, first measurements have been carried out in five coal mines in the Saarland in the 60's. Air samples were taken at different places in the coal mines, dried, fed to an ionisation cell and measured by a device including reference cells. Samples taken at ventilated places showed radon concentrations consistent with the lower British results. They all kept within the standards of the first German regulation on protection against radiation. Measuring the radon daughters was renounced because of the relatively low radon concentrations and the requirements for flame proofness in coal mines. Moreover, it can be ascertained that because of the effective ventilation the disequilibrium factor between the decay products and the radon concentration remains far below the value of one (Muth, H., 1978) (Keller, G.). In 1979 the committee on mine safety and health protection in coal and other mines of the EEC proposed to have measured and evaluated radon concentrations in European coal mines to find out whether they complied with international standards. Great Britain and Germany agreed to this proposal and by commissioning such measurements to scientific institutes complied with the request to harmonize the methods used. In the Federal Republic of Germany, e.g. Westfälische Berggewerkschaftskasse (WBK) and Staatliches Materialprüfungsamt; Dortmund (MPA) were requested to carry out the measurements in coal mines of the Ruhr coalfield whereas Saarberg Interplan was responsible for the Saar coalfield. The WBK measurements are reported in later paragraphs.

Jan 1, 1981

By A. J. Benham, H. Kessler

In the UK a high proportion of land-won sand and gravel is extracted from sub-alluvial gravels and river terrace gravels located within river valleys. However, extraction from deposits of this type is increasingly proving to be less acceptable. Quarries within river valleys often have a high visual impact and the cumulative impact of these operations in close proximity to each other can be high (figure 1). River valley operations are almost always restored to open water. Whilst these may be attractive for nature conservation and provide leisure activities, they can also have a serious impact on the natural hydrology of the flood plain. Wet restoration of quarries located close to airports or airfields can also lead to concerns regarding increased risk of bird strike on aircraft. The Civil Aviation Authority recently suggested that an exclusion zone of 13 km be applied around all airports and airfields to reduce the potential for bird strikes on aircraft. This action is likely to have a serious impact on the availability of potential sand and gravel extraction sites in river valleys.

Jan 1, 2005

By B. Bag

Saturated and unsaturated fatty acids are used in the flotation of iron values present in iron ore. Among the several fatty acids, oleic acid and its sodium salt are widely used. To substantiate the flotation results, the quantum chemical calculations of a few such acids have been carried out by adopting the semi-empirical AM1 method. These acids have been further optimized in the presence of an iron atom. The electronic interaction of the polar carboxylic head group of oleic acid with the iron atom is higher compared to the other acids. The numerical results support the flotation behavior of iron ore with oleic acid. Key words: Iron ore, Flotation, Fatty acids, Quantum chemical calculations, Semi-empirical AM1 method

Jan 1, 2009

By Edward F. Fries

Computerized, real -time monitoring had its beginning in the U.S. coal industry in the early 1970's. Over the last 10 years, developments in technology have made systems available that are capable of monitoring and controlling many mine parameters that can increase safety and production. However, situations currently exist where computerized monitoring systems are not being utilized to their fullest capability. They produce reams of printed output that are not sorted in a useful format, and human operators are not able to react fast enough in emergency situations tn tile large amount of information that the systems generate. A solution is the application of an expert system as the interface with real-time monitoring. An expert system would use an extensive knowledge base and human-type reasoning ability to make decisions on optimum strategies. Expert systems have been applied successfully to problems in other industries, and could provide significant benefits to mine information management systems. The use of an expert system with real-time mine monitoring is discussed in this paper.

Jan 1, 1986

By M. C. Rockwell, G. F. T. Lay

Promising placer gold exploration sites offshore Lunenburg County are drowned pre- and post-glacial river channels and auriferous glacial tills. Gold values up to 5.67 9/m3 have been encountered in the vicinity of the Ovens Peninsula offshore Lunenburg County. Moderate gold values associated with notable amounts of heavy minerals were reported from various other exploration sites in this area. This paper highlights the major geological and gemorphological features for placer gold depositions in southern Nova Scotia. The past to present gold exploration activities nearshore and offshore Lunenburg County are summarized and potential areas for placer gold identified.

Jan 1, 1988

By Leonard W. Postregna

Prior to January, 1986, the city of Austin, Texas was on notice by the Federal Government's Environmental Protection Agency and the Texas Water Commission, that they were illegally polluting the Colorado River. The wastewater facilities presently in use in South Austin were inadequate to handle the vastly increasing population. The city of Austin, Texas hired Parsons Brinckerhoff Quade and Douglas, Inc. and Dannenbaum Engineering Corporation to design and supervise the construction of an update to their existing system to alleviate this problem. A major criterion handed down to the Designer and Contractor was that the system had to be completed within a two year time frame. The biggest link to the entire design was a tunnel project consisting of 43,000 linear feet (13,106 m) of tunnel, eight feet (2.44 m) in diameter with connecting structures tying into existing and future facilities. The project was awarded to S. A. Healy Construction Company of McCook, Illinois with a low bid of $24,755,000.00. This article summarizes the techniques used in the construction of this tunnel project.

Jan 1, 1989

By R. Sharma, S. Svoronos, S. Gupta, N. A. Abdel-Khalek

This paper presents the results of a column flotation study on a fine feed sample of Florida phosphate. A central composite design was used to study the main and interaction effects of parameters affecting column efficiency. The statistical design is also used to determine the optimum conditions. The results indicate that, depending on the experimental conditions, it is possible to produce a high-grade concentrate with a high recovery. A 15ppm concentration of nonionic frother was found sufficient to maximize the recovery at pH of 9.5.

Jan 1, 2002