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By M. C. Ruiz, M. E. Godoy, J. B. Rivarola, M. W. Ojeda

The amount of Pd recovered from an exhausted olefin hydrogenation catalyst was found to depend on mixing technique, particle size, carbon percentage, chlorine flow, reaction time and temperature. Pd extraction was total when a sample in the 125-175 micrometre particle size range was chlorinated for 60 min at 723 K with 20 cm3 Cl2/min, for 60 min at 748 K with 30 cm3 Cl2/min and for 30 min at 773 K with 30 cm3 Cl2/min. No C addition was needed; the initial C content of the catalyst was sufficient for total recovery. Pd extraction was also affected by heat treatment in different atmospheres before chlorination. Treatment with O2, N2 and N2 with traces of O2 led to different degrees of oxidation of C and permitted the formation of oxidised Pd species. Thermal pretreatment in N2 with traces of O2 was most conducive to Pd extraction

Jun 21, 1905

By Wilton Johnson

The development and use of minerals and mineral fuels are essential to national security and to the maintenance of an expanding economy. As a Nation, we often met these needs but failed to recognize and assess the impact that mining and mineral processing activities have on other natural resources. Currently, the growing demand for energy and minerals is accompanied by an increasing awareness that the provision of these resources must not conflict with society's demand for a clean and habit-able environment. Although present mining and mineral processing activities incorporate, or have under development, technology capable of minimizing environ-mental impacts on land, air, and water, many older operations, particularly in the first half of this century, lacked the technological, social, and environmental insights that exist today. Consequently, a substantial backlog of damaging and potentially damaging conditions remains from such problems as mine subsidence, acid water generation, burning and nonburning waste banks, abandoned surface-mined lands, abandoned underground mine fires, and abandoned mine shafts and oil and gas wells.

Jan 1, 1979

By Carlos F. Perucca

"Potassium is one of the three basic plant nutrients along with nitrogen and phosphorus. There is no substitute for potassium compounds in agriculture; they are essential to maintain and expand food production.Potash is extracted from buried ancient evaporites by underground or solution mining. This accounts for most of the potassium produced. Another important source is brine from landlocked water bodies, such as the Dead Sea, Salar de Atacama or Great Salt Lake.About 95% of potash produced worldwide is used in agriculture. The rest is found in several other industrial uses, including glass manufacturing, soaps, plastics and pharmaceuticals.Currently, three producers: IMC, PCS and Agrium operate 8 conventional and two solution mines in Saskatchewan, five of which run froth flotation circuits, two heavy media-flotation, two run forced crystallization and one natural crystallization.Potash in SaskatchewanPotash was discovered in Saskatchewan in the early 1940’s while drilling for oil. The deposits lie diagonally across the southern plains of Saskatchewan sloping southerly from a 1,000m depth at Saskatoon to more than 1,600 m depth at Belle Plaine and up to 3,000 m in depth in North Dakota. The known deposits are massive, accounting for more than 40% of the world’s known reserves."

Jan 1, 2003

By Patrick Bermingham

The advancement of hydraulic impact hammers has followed the general advancement of hydraulics. The construction industry has been revolutionized by the application of hydraulics in excavators, cranes and, of course, in the hydraulic vibratory driver/extractor, which has become a standard tool. The innate ability to move a large mass with a very small displaced volume has given hydraulic power the advantage over previous power mediums. Recent development of more specialized and complex seal configurations and compounds has greatly improved the reliability and permitted the use of higher pressures in hydraulic systems.

Jan 1, 1987

By S. T. Wlodek

The surface and subscale oxidation reactions were followed by means of continuous weight-gain and metallographic techniques over the range 1600" to 2200°F (871° to 1204 °C) for up to 400 hr. Full identification of all scale and subscale reaction products was obtained by electron and X-ray diffraction. At or below 1800°F (982°C) a linear rate of reaction (QL = 46.0 kcal per mole) governed the oxidation process, extending for up to 100 hr at 1600°F (871 "C). During linear oxidation the surface scale consisted of an amorphous SiO2 film overgrown with Cr 2O 3 and NiCr204. This initial linear process was followed, and above 1800°F completely replaced, by two successive parabolic rate laws (Qp = 60 and 57 kcal per mole). This parabolic reaction involved the formation of a complex scale consisting of Cr2 O3 and smaller amounts of NiCr2O4. Parabolic oxidation appeared to coincide with the disruplion of the silica film present during linear oxidation and was followed by subscale (internal) oxidation of crystobalite and NiCr2O4. The balance between the subscale and surface oxidation reactions controls the oxidation of this commercial alloy. The amorphous silica film appears to result in the linear rate and diffusion through Cr2O3 is the more likely rate-limiting step during parabolic oxidation. THE oxidation of a multicomponent composition is a complex phenomenon not presently amenable to a rigorous classical interpretation. Nevertheless, even a qualitative understanding of the scaling and subscale reactions that occur in a commercial composition can illuminate the reactions that limit its high-temperature stability in an oxidizing environment. This study of the oxidation of Hastelloy Alloy X presents the first of a series of studies with the above approach in mind. Hastelloy X exhibits one of the best combinations of strength and oxidation resistance available in a wrought, solution-strengthened, nickel-base alloy. Although during long time exposure some precipitation of M6C and M23C8 carbides as well as a complex Laves phase occurs, the amounts are probably small enough to have no appreciable effect on the chemistry of the matrix. Radavich has identified the oxidation products on Hastelloy X oxidized for 5 min to 10 hr at 1115°F as NiO and the NiCr2O4 spinel. Oxidation for 5 to 15 min at 1500°F produced a scale of spinel, NiO, and a rhombohedra1 phase, probably Cr2Os. Sannier et 2. have reported continuous weight-gain data for Hastelloy X at 1650" and 2010°F and internal-oxidation measurements after 150 hr at 2010°F. In addition, much of the data on binary Ni-Cr alloys recently reviewed by Kubaschewski and okins' and Ignatov and Shamgunova4 as well as studies of binary Ni-Mo alloys5 are also pertinent to the oxidation of this composition. EXPERIMENTAL Continuous weight-gain measurements and metallographic measurements of subscale reactions were the main experimental techniques used in this study. X-ray and electron diffraction backed up by a limited amount of electron-microprobe analysis served to characterize the nature of the scale- and subscale-reaction products. Two heats of commercial sheet of the composition given in Table I and identified as A and B were used in the bulk of this study. Internal-oxidation measurements were made on a third heat of material in the form of a 0.5-in.-diam bar. In order to assure homogeneity, all heats were reannealed 4 hr at 2175°F prior to sample preparation. weight-Gain Measurement. All specimens (1.5 by 0.4 by 0.03 in.) were abraded through 600 paper, electropolished, and lightly etched in an alcohol-10 pct HCl solution. An electrolyte of 150 cu cm H,O, 500 cu cm HsPO4 (85 pct conc), and 3 g CrO3 at a current density of 0.9 amp per sq cm or a solution of 10 pct HaW4 in alcohol used at 4 v and 0.3 amp per sq cm was used for electropolishing. The resultant surface exhibited a finish of 3 ± 1 p rms. Continuous weight-gain tests were made at 1600°, 1700°, 1800°, 1900°, 2000", and 2200°F on auer' type balances capable of recording a total weight change of 110 mg with an accuracy of k0.1 mg. All tests were made in air dried to a dew point of -70°F and metered into the 2-in.-diam reaction

Jan 1, 1964

A detailed study of the capital investment and production cost for copper electrowinning plants shows that significant savings in both can be achieved by increasing the current density. From the economic analysis it is determined that the optimum current density which will result in lowest capital investment and lowest operating cost is between 60 A/sq. ft. and 70 A/sq. ft., or at least three times as high as the Conventionally employed current density. The specific investment, expressed as $/ton-year, is found to be a function of both the current density and plant capacity and has a minimum value at the optimum current density. Empirical equations are developed for the purpose of estimating the capital investment and operating cost for plants of any production capacity operating at any current density.

Jan 1, 1972

By Rolando Gonzalez

Mexico’s role in the world economic community continues to grow. And it is important that the country makes use of its natural wealth, including its large underground deposits of minerals and metals. With that in mind, Industrias Peñoles S.A. de C.V.(Peñoles), a mining, smelting and refining company, began mining lead, zinc and other metals from the Francisco I. Madero Project (FIM). The mine is located about 600 km (370 miles) northwest of Mexico City in the state of Zacatecas. Peñoles plans to remove about 3 Mt/a (3.3 million stpy) of ore from FIM. To achieve this goal, the company needs to optimize its processing, to maximize the amount of metal it extracts through FIM’s large flotation lead-zinc concentrator. To ensure high productivity, Peñoles and its contract engineering firm, M3 Engineering and Technology, of Tucson, AZ, have implemented anore processing system.

Jan 1, 2003

By A. F. Kaczmarek

Cerro Negro is an undeveloped ore body located at the Cerro Verde mine near Arequipa, Peru. The mineable reserve contains 70 Mt of oxide ore grading 0.532% copper. Mineralization is hosted in three distinct rock types: tourmaline breccia, crackle breccia and granodiorite. Rock type effects copper recovery and acid consumption. The paper describes Cyprus' testwork philosophy and the resulting four-phase metallurgical program used to define the commercial leaching parameters. Copper recovery and acid consumption were monitored as functions of crush size, heap height, irrigation rate and acidulation conditions. Single lift, on-off and permanent multi-lift heaps were considered. Leach cycle times were based on incremental copper extraction and acid consumption rates, with added constraints imposed by operational requirements. The optimum leach system involves an on-off pad using tertiary crushed ore acidulated with 20 kg/t acid and stacked to a height of 6.5 m. The active leach cycle is 82 days at an irrigation rate of 0.26 l/min/m2. Under these conditions copper recovery is expected to average 81% over the life of the mine.

Jan 1, 1999

By P. Zhang

A multiyear, comprehensive study of flotation reagents used in phosphate beneficiation was conducted. The study involved the evaluation of pure fatty acid compounds, comparison of various anionic collectors and testing of iso-acids. Various C12 to C22 fatty acids were tested as Florida phosphate collectors. The saturated fatty acids were found to be very poor collectors when using the standard conditioning procedure, whereas the unsaturated C16 to C22 fatty acids showed fair to good phosphate collecting ability. The C18 fatty acids oleic, impure oleic and linoleic and the C20 eicosenoic acid were shown to be the best phosphate collectors. The best flotation results were obtained using Liqro GA tall oil and oleic acid. Four isostearic/iso oleic acid type fatty acid collectors were compared with a commercial grade oleic acid and with Liqro GA tall oil as phosphate collectors using standard laboratory conditioning and flotation procedures. The most selective collector evaluated was Century 1108, a high isostearic acid-type reagent. However, it was concluded that this excellent-performing reagent was too expensive for commercial use. Overall, the most promising reagent was probably Century MO-5. This collector is essentially an iso-oleic acid/stearic acid mixture (not isostearic acid), and it costs much less. This program laid a sound foundation for developing single collector, all anionic flotation processes.

Jan 1, 2009

By E. J. Dulis, A. Kasak, R. C. Westgren

The potential of uirought tungsten- and tantaluw-rich alloys of the W-Ta-Mo-Cb system was investigated for high-strength structural applications above 2500° F. Appreciable strengthening of tung-sten and tantalum—essentially attributable to solid-solzction effects—was obtained with binary, ternary, and quaternary alloys. Tensile strengths as high as 67,000 psi were achieved at 3000 OF. ThE quest for wrought structural materials which possess good strength properties at temperatures above 2000°F has led to a considerable research effort during the past decade. In addition to exploring the potential of various high-melting-point refractory metals (such as molybdenum, columbium, tantalum, and tungsten) for very high-temperature structural applications, alloy-development programs have been undertaken to achieve greater strengths than could be achieved with unalloyed refractory metals. The methods of strengthening refractory metal alloys have included both solid-solution and dispersion strengthening. General relationships among the relevant properties (melting point, recrystallization temperature, and high-temperature strength) of refractory metals indicate that the highest strengths at temperatures of 2500°F or higher would be obtained with tungsten-or tantalum-base alloys. Therefore, the present investigation was undertaken to determine the high-temperature strength potential of solid-solution strengthened alloys based on the binary system W-Ta; to effect further strengthening, minor additions of molybdenum and columbium (at the 6 and 12 pct levels) were made. The portion of the W-Ta-Mo-Cb quaternary alloy system of interest is shown schematically in Fig. 1. The component metals—W, Ta, Mo, and Cb—have a bcc structure at all temperatures, and their binary systems are mutually completely soluble.' Complete solid solubility in the W-Ta-Mo and W-Ta-Cb alloy systems has been demonstrated,' and, therefore, it was expected that the quarternary alloys of the system would also exhibit complete solid solubility at all temperatures. In the virtual absence of contamination by interstitial elements, all the alloys would be truly solid-solution strengthened. Twenty specific compositions of this investigation included binary, ternary, and quaternary alloys of the W-Ta-Mo-Cb system as well as unalloyed tungsten and tantalum. The compositions are shown in Table I. EXPERIMENTAL PROCEDURE Consumable-electrode vacuum-arc melting with ac power was used to produce small laboratory-sized, cylindrically shaped ingots (1-1/4 in. in diameter and 2 to 3-1/2 in. long) of the twenty compositions. A furnace was specially constructed to melt as many as four electrode rods simultaneously into molds lined with tungsten or tantalum sheet. High-purity rods of tungsten, tantalum, molybdenum, and columbium were used for consumable electrodes; the diameter of each rod was determined by the desired weight percentage of the component metal in a given alloy. The details of the construction and operation of the melting furnace will be discussed in another p~blication.

Jan 1, 1964

By D. -A Tremblay

Dynamic wetting spread factors and interfacial heat transfer coefficients were determined for aluminum droplets solidifying on copper substrates, The spread factors were determined from the droplet geometries while the heat transfer coefficients were obtained by solving inverse heat conduction problems, 1-D and 2-D heat transfer models are presented and the results they provided are compared, For the latter, a sensitivity analysis was also performed to determine the influence of thermophysical properties and boundary conditions. Experiments were alternatively carried out with three different gaseous atmospheres and the dynamic wetting spread factors were correlated to the interfacial heat transfer coefficients.

Jan 1, 2005

By Lamont G

The significance of blasthole stemming in determining blasting efficiency has been extensively studied for small diameter holes using gelignite explosives. Recent developments in blasting technology with the use of large diameter holes and low cost blasting agents have not included studies of the effectiveness of different types of stemming materials. A review of previous measurement techniques and the relevance of these earlier results to present stemming practice is presented in this paper. A survey of operating mines in Australia provided information for this analysis. The value of stemming in reducing blast noise and improving blasting efficiency is generally accepted but the use of bulk-loaded explosives in underground operations has resulted in the practice of eliminating the use of stemming material.In surface operations drill cuttings are used for stemming on the basis of availability rather than efficiency in providing resistance to movement. The development of laboratory testing techniques, based on noise level and borehole pressure measurements, to evaluate the relative efficiency of different types of stemming materials is described. The results of an extensive series of tests with ANFO explosive showed similar trends tothose obtained from earlier published results with gelignite type explosives. Conclusive quantitative results on the relative effectiveness of different stemming materials will require minor modifications to the existingequipment. Observations and the results of pressure measurements indicated the presence of shock wave effects which caused the ejection of the top section of the stemming column when using coarsely fragmented material.

Jan 1, 1979

By Jürgen F. Brune, Liming Yuan, Alex C. Smith

To provide insights and assistances for the optimization of ventilation systems for U. S. under-ground coal mines facing both methane control and spontaneous combustion issues, a computational fluid dynamics (CFD) study is being conducted to investigate the effect of the ventilation scheme on the prevention of spontaneous combustion in longwall gob areas. This report focuses on the flow patterns within the gob under three different ventilation systems; one-entry and two-entry bleederless systems as well as a three-entry bleeder system. The gas flow in the caved gob area is simulated as a laminar flow through porous media while the gas flow in ventilation airways is simulated as a fully developed turbulent flow. The air flow patterns are visualized using flow path lines. Air velocity contours and vector data are also obtained. The possible location of critical velocity zones where the gob is most liable to spontaneous heating is discussed.

By Larry A. Cramer

"Three primary drivers are setting the trend for base and precious metal processing . they are: continued low real base metal prices, environmental concerns, and continued high prices for PGM.s. Low base metal prices are increasing the search for economies of scale and company consolidation as well as the development of some hydrometallurgical technologies. Environmental concerns are pushing for continued reductions in SO2 emissions and hydrometallurgical technologies. The high prices for PGM.s are driving major expansions and a focus on minerals processing recoveries and, to a lesser extent, reductions in the refining metal lockup.In nickel, HPAL operations on laterites have failed economically but Inco is still pursuing some alternatives. BHP-Billiton and others are developing bioleaching alternatives for nickel laterites and sulphides.Copper continues to be dominated by the hydrometallurgical and pyrometallurgical debate; new hydrometallurgical developments are being tested at several sites whilst the pyrometallurgists continue to make competitive cost and environmental improvements.Gold processing developments are dominated by the use of improved gravity recovery equipment and by the development of thiosulphate as a more environmentally acceptable lixiviant.PGM processing trends are the use of fine grinding technologies, higher power input flotation cells, and new pyrometallurgical technologies. Hydrometallurgical options for some applications are being sought.OVERVIEW The metals industry has remained under price pressure for some time; low and decreasing real prices for most metals have become an expected scenario. Occasional price spikes give some relief but invariably bring expansions and new entrants into an already oversupplied commodity market, thus leading to the continued price pressure. Technical innovation, economies of scale, and improved work systems are continually sought, so as to improve the competitive position of each individual company in such a climate; however, these developments add to the downward price pressure. In such a situation the application of scarce funds to research and development is a difficult task. Excess funding is not available in tight economic times and yet the main route to higher profits is clearly the application of technical developments to lower the cost of producing a metal commodity. Many technical centers have closed as a cost saving exercise and some have coalesced to obtain economies of scale. The Australian based AMIRA research organisation has grown to serve the R&D part of the market well in Australia and in South Africa by acting as the catalyst to form research partnerships between a number of industry players and as an administrator to direct the funding of research projects towards the various applicable research institutions. AMIRA has developed closer ties to Camiro (Canadian Mining Research Organisation) through the appointment of Camiro.s metallurgical processing research director as AMIRA.s North American based director. AMIRA is continuing discussions with MIRO (Minerals Industry Research Organisation) in regard to a merger, with a report outlining the merger proposal expected in March of 2003. Company focused research centers continue to be effective at Anglo American Research Labs, Teck-Cominco Research, Falconbridge Research center, Inco Research and some others."

Jan 1, 2003

By Fred Leighton

The Bureau of Mines has developed rock noise source location techniques that may be used to obtain precise and practical source locations from micro-seismic field data. These techniques enable one to monitor all or any part of a rock structure and map progressive stress buildup or rock movement. Thus, the microseismic method of determining instability in rock structures is becoming an invaluable engineering tool for the mining or civil engineer engaged in rock excavation and construction.

Jan 1, 1970

By P. Sharma, J. C. W. Fowler

This paper discusses the wind blast / air blast phenomenon, how it is managed in coal mines and how it might best be managed in other underground mines. L'article qui suit a pour objets de décrire le phénomène de tir a l'air comprimé et les méthodes de modération de celui-ci dans les mines de houille, et d'indiquer de quelle manière il pourrait être surmonté dans d'autres mines souterraines. Dieses Seminararbeit diskutiert die Windexplosion / Luftexplosion Phänomen, wie es in Kohlenberg-werken geleitet wird, und wie es am besten in anderen untertage Bergwerken geleitet werden könnte.

Jan 1, 2003

By Michael J. Lord, Richard H. O. Wagner

"The technologies used in the mineral processing of ores are being increasingly applied to the identification and remediation of metal contaminated industrial, military and landfill sites. The objective of mineral processing treatment of contaminated site material is to restore the value of the land and to concentrate the contaminants into a very small volume of separated material which, depending upon its nature, can be further processed, marketed, or sent to a landfill. A systematic characterisation of the site material is first undertaken. Bench and pilot testing follows to evaluate criteria for metal separation. The testing may examine one or more physical or physico-chemical reprocessing methods, singly or in combination, for the remediation of the test samples. These mineral processing tests determine the % metal removal fiom the soil and the contaminants concentrated from the medium. The usefulness of mineral processing testing for site remediation flowsheet design and execution is illustrated by the case studies presented. This paper will present the test results of three case studies: an industrial site decontamination, the cleanup of a small arms firing range, and the reclamation of property within a landfill.INTRODUCTIONEnvironmental legislation and our society’s quest for a cleaner environment has led to the application of mineral processing expertise and technology for industrial site decontamination, military site cleanup and landfill reclamation. Although the required level of decontamination varies between jurisdictions, a site becomes a candidate for decontamination once the contaminant concentrations are found to exceed the Canadian Council of Ministers of the Environment (CCME) Interim Remediation Criteria for soil (decommissioning guidelines) or applicable provincial guidelines. The objective of mineral processing treatment of contaminated site material is to restore the value of the land and to concentrate the contaminants into a very small volume of separated material which, depending upon its nature, can be further processed, marketed or disposed of in a landfill"

Jan 1, 1999

By W. W. Cutler

An oil-field drilling campaign is used in this paper to signify the spacing of the wells to be drilled as well as the drilling program, which is interpreted as the number of wells drilled in a unit of time, This has an important bearing upon the time of receiving income, as well as upon the amount of revenue obtained In periods of low prices for oil, such as the present, the margin of profit is at the best very small, and the correct determination of the drilling campaign may be the deciding factor between incurring financial loss or gain during the depressed period. General policy of the operator. Drilling should be planned by the field engineer to conform with the general policy of the operator. This policy may be one of conservation daring the early life of the property, but as mentioned later, this may result in a smaller ultimate recovery it often occurs that the market price of oil does not warrant rapid development, or it may be desirable to hold in reserve a supply of oil for a refinery. The policy may be to recover all of the oil as quickly as possible, or it may be to maintain a constant and sustained production. In any case, the operator should, outline as far as possible a definite policy, and should understand the principles underlying the recovery of oil, the influence of rapidity of drilling and effects of spacing, in order that he may obtain the oil as required with the least expenditure.

Jan 1, 1921

By Zorigtkhuu Davaanyam, Bern Klein, Stefan Nadolski, Amit Kumar

"The High Pressure Grinding Rolls (HPGR) is a relatively new comminution technology that has been shown to be more energy efficient compared to semi-autogeneous (SAG) mills. Full and fair consideration cannot be given to HPGR-based comminution circuits in early stage projects, because presently pilot scale testing is required for assessing and sizing; pilot scale testing requires bulk samples weighing more than one tonne. A CAMIRO research program was conducted at the University of British Columbia to develop bench scale tests that would reduce the quantity of sample required to assess HPGR.Three test procedures were developed.1. The Direct Calibration Methodology calibrates piston press test results to pilot scale test results such that piston press tests can then be used to determine the energy–size reduction relationship for a range of ore types.2. The Database Calibrated Methodology, which is similar to the Direct Calibration Methodology except that it calibrates piston press tests against a database of pilot scale and piston press tests.3. The Semi-Mechanistic Methodology was developed to use piston press test results as an input for an HPGR based energy-size reduction performance model.Through utilization of these methodologies, the energy–size reduction performance of an HPGR can be predicted with minimal sample requirement. In addition, piston press testing is far more cost effective, faster, and accessible than pilot-scale HPGR testing.IntroductionOne could argue that in the future, decisions regarding selection of comminution circuits will be made primarily on the basis of energy consumption. The following facts and predictions support the argument:"

Jan 1, 2015

By Steve Kral

For an industry that provides more than half of the nation’s energy needs, the U.S. coal industry still attracts negative publicity. However, the nation’s energy appetite continues to increase. And political leaders and the public are beginning to understand that alternative fuels will not be enough to keep up with that appetite. Does that mean the nation will now embrace the coal industry? No, according to speakers at the Rocky Mountain Coal Mining Institute (RMCMI) meeting. The industry still needs to sell the public on coal’s advantages over other fuels. And the industry must continue to develop technology that will allow coal to meet and exceed strict clean air and clean water regulations.

Jan 1, 2002