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By J. H. Swisher

An experimental study has been made of the possible mechanisms for foam stability in the system CaO-SiO2-Cr2O3, where Cr2O3is the foaming agent. The degree of lowering of surface tension by Cr2O3 was determined at 1600 "C for high -silica melts. Measurements were also made of foam stability under standardized conditions. The results of the two sets of measurements then were correlated by applying the Gibbs and Marangoni theories of film elasticity. It was demonstrated that the Marangoni elasticity effect is probably the largest single contributor to foam stability, although the high uiscosity of' silicate melts makes some contribution in controlling the rate of drainage of liquid from bubble lamellae. ThE tendency of metallurgical slags to foam has frequently been observed during steel-refining operations. In the open-hearth furnace,this tendency is considered undesirable because it slows down the rate of heat transfer from the burners to the molten-metal bath. On the other hand, it is sometimes desirable to have a "foamy" slag in the basic oxygen converter.' A more effective blanket over the steel bath is made by a "foamy" slag, and loss in yield of metal due to splashing is minimized. In addition, a flush slag can be removed more easily in this condition. Since slag-foaming problems in the field have been attacked largely on an empirical basis, it appeared desirable to obtain a better basic understanding of the mechanism of foam stability. The experimental work was directed almost entirely toward the behavior of Cr2O3 as the foaming agent in CaO-SiO,-Cr2O3 melts. In the first stage of the investigation, the degree of lowering of surface tension by Cr2O3 was determined at 1600°C. The second stage consisted of measuring foam stabilities under standardized conditions. The two sets of experimental results then were correlated by applying various theories of foam stability. For convenience in interpreting the surface-tension and foam-stability results reported here, a portion of the CaO-SiO2-Cr2O3 phase diagram2 is reproduced in Fig. 1. EXPERIMENTAL 1) Surface-Tension Measurements. Very little information is available in the literature on the lowering of surface tension of slags by foaming agents. Kozakevitch 3 mentioned that the addition of 1.5 pct Cr2O3 lowered the surface tension of FeO slightly. In another system, some data on the lowering of surface tension of foaming slags by P2O5 were reported by Cooper and Kitchener.4 The technique used for the surface-tension measurements was the maximum bubble-pressure method,' using a single tube immersed to various depths in the melt. This method has been used extensively in high-temperature systems, such as in liquid metals, slags, and glasses.6,7 It has the advantage that the contact angle between the liquid and the tube material need not be known. The equation used for calculating surface-tension values from maximum bubble-pressure measurements is the Schroedinger equatioq5 which can be written as follows:

Jan 1, 1964

By Vladimir Panjkovic, Ostrovski. Oieg, Campbell Cripps Clark, John Truelove

"Effects of properties of raw materials and blast on the performance of an iron bath reactor have been examined by a mathematical model. The model consists of three modules: 1) chemical reactions in the gas phase and heat transfer from gas to droplets ejected from the bath; 2) heat losses from the vessel and radiative heat transfer from the freeboard to the bath; and 3) heat and mass balances for the bath. The following parameters of the process are calculated: coal, ore, flux and oxygen consumption, post-combustion ratio and heat-transfer efficiency, temperature and composition of the off-gas, and slag and metal chemistry.IntroductionOne of the anticipated advantages of smelting reduction over conventional ironmaking is the use of lower-grade raw materials. In this work, the effect of-properties of raw materials on the performance of an iron-bath reactor is examined with a numerical model. The model is also used to assess the effect of properties of the blast (flowrate, temperature and oxygen enrichment) and ejected droplets (generation rate, size and ratio of total weights of slag and iron droplets) on the key parameters of the process. In the process coal, oxygen, ore (which may be partly prereduced) and fluxes for specified slag composition are charged to the bath. Slag and iron droplets are ejected from the bath into the gas phase, where they are heated before returning to the bath. Iron droplets undergo decarburisation and reoxidation with CO2 and H2O. Dust is also generated from the bath, and oxygen or preheated air for post combustion is injected from the top of the vessel.The model consists of three modules: 1) reactions in the gas phase and heat transfer from gas to droplets ejected from the bath; 2) heat losses from the vessel and radiative heat transfer from the freeboard to the bath; and 3) heat and mass balances for the bath. The structure of the model and the data exchange between the modules are shown in Fig. 1. The following parameters of the process are calculated: coal, ore, flux and oxygen consumption, postcombustion ratio (PCR), heat transfer efficiency (HTE), off-gas temperature and composition, slag and metal chemistry, and rates of decarburisation and reoxidation of the iron droplets."

Jan 1, 1996

By R. J. Mechin

Top-slicing was introduced in the Pachuca district in 1917 by T. C. Baker, at that time mine superintendent of the Santa Gertmdis mine. There then existed 1200 ft. below the surface, lying between the fourteenth and eighteenth levels (a vertical distance of 354.2 ft.) a block of ore having a length of 295 ft. and an average width of 82 ft. and dipping at an angle of 65°. This block lay in the hanging wall of the vein and consisted of highly altered and fractured andesite, cut through with mineralized quartz stringers. On the foot-wall side, 26 ft. of old filling, left by former operators, was of payable grade. Stoping therein was first undertaken by the square-set filling system, but because of the extremely heavy hanging wall and loose dry filling in the foot wall, all square setting had to be accompanied by spiling, which made the operation exceedingly slow and costly. A system of mining was sought that would eliminate the difficulties inherent to the square-set system in heavy ground and that at the same time would effect the desired economies in mining. After several years, top-slicing has met all the conditions most satisfactorily, so that when similar conditions presented themselves in El Bordo mine, this method was adopted with necessary modifications. El Bordo mine is operated by the Santa Gertrudis company, and is situated about two miles north of Pachuca. Because of the diversity of the orebodies, a number of different mining methods are in use, among them top-slicing. Description of Block of Ore Former operators, when mining the original vein, left in the foot wall ore of too low grade to be profitable at the time; also, considerabe low-grade material was sorted out and stored as filling in the stopes. Some pillars were left in place, either for support or because they were not payable. All this has formed a body of ore that can now be exploited

Jan 1, 1925

By C. -K. Fang

"Aging effect on the wear resistance of alumina particulate-reinforced 6061 aluminum matrix composites with a block-on-ring wear tester has been investigated. Specimens with various Al2O3 volume fractions of 0%, 10% and 20% were employed in this work. Experimental results indicated that over-aged monolithic 6061 Al had the best wear resistance, as compared with under-aged and peak-aged conditions. For the composite containing 10% Al2O3, over-aging and peak-aging resulted in similar wear resistance, which was higher than that for underaging conditions. For the composite containing a high volume fraction (20%) of Al2O3, the wear resistance reduced with the increase in aging time. Although longer aging time was favourable to the wear resistance of monolithic 6061 Al, it was detrimental to that for the Al2O3/6061 Al composite with high volume fraction of particles. IntroductionMetal-matrix composites (MMCs) have received attention in many engineering applications because of the demands for high specific strength (strength-to-weight ratio) and specific stiffness, good high temperature capabilities and wear resistance. The manufacturing processes of fiber-, whisker-, and particulate-reinforced MMCs have been well developed (Hosking et al., 1982). Because of the reduction in fabrication cost, the applications of MMCs have been widely extended to light weight-bearing sleeves, calipers, automobile parts (brake rotors, drive shafts, connecting rods, piston rings, and cylinder liners), sporting goods, aerospace components, tanks (wheels, speed brakes, and track shoes) and other industrial applications. Among the three types of metal matrix composites, particulate-reinforced MMCs are promising because of their homogeneous and isotropic material properties and low cost. Additionally, they can be formed using conventional metal processing techniques."

Jan 1, 2003

By Nasser Madani, SULTAN ABULKHAIR

The abstract of the paper discusses the challenge of quantifying iron content in a coal deposit in Kazakhstan. The iron dataset is limited, coming from only three drill holes and some stope samples, while a large amount of geological information is available from legacy drill hole data. The paper proposes a workflow using multiple-point geostatistics to model geological domains and two-point geostatistics to model iron content within these domains. The results show that the direct sampling (DeeSse) algorithm effectively reproduces the complex seam layers, and sequential Gaussian simulation models the iron within each domain.

Mar 30, 2022

By J. Ita, F. Malekzadeh

"Multi-scale simulation in coupled fluid flow- geomechanical systems is a computationally efficient method for numerically solving large poroelastic systems. When using multi-scale methods, care must be taken in ensuring consistency when information is exchanged between systems that have a different discretization. Here a method is presented which provides consistency between the pore pressure being calculated on a fine scale fluid flow domain and upscaled to the coarser scale geomechanical domain and the pore volume change being calculated on the coarse geomechanical domain and down-scaled to the fine fluid flow domain. Central to this process is the characterization of the mechanical properties of the poroelastic system at both scales.Another advantage of the method presented here is that it is applicable to hydraulically disconnected but laterally drained (i.e. multi-porosity) layered systems as well as hydraulically connected, layered systems. Thus it can be used in geological situations where thin shale streaks or hardpans impede flow between laterally extensive, hydraulically conductive units. This is significant as the pressure evolution of such a hydraulically disconnected, laterally drained system can be very different than a hydraulically connected one as shown here. INTRODUCTIONA multi-scale treatment of fluid flow and deformation is a key enabler when simulation of poroelastic phenomena is limited by computational resources. As the spatial domain of the geomechanics model is usually larger than the fluid flow model, it is desireable to use a coarser discretization in the geomechanical model compared to the fluid-flow model. This type of multi-scale simulation requires a consistent up-scaling of pore pressure from the fine scale fluid flow model to the coarse scale geomechanical model and down-scaling of pore volume change from the geomechanical model to the fluid flow model (see Figure 1)."

Jan 1, 2015

By M. Gous

Namakwa Sands is a heavy minerals mining and beneficiation business in the Anglo Base Metals Division, and operates along the West Coast of South Africa. The business encompasses mining, mineral concentration, separation, and smelting operations. The smelting process comprises the carbonaceous reduction of ilmenite to produce titania slag with a TiO2 content of 86%, and iron with a carbon content of 2.5%. The Namakwa Sands smelter, situated near the Saldanha Bay harbour, commenced smelting operations in 1994, when a 25 MW DC-arc furnace was commissioned. The smelting operations were expanded in 1999, with the commissioning of a second 35 MW DC-arc furnace. Despite the fact that ilmenite smelting poses a technical challenge in terms of the high temperatures required, the physical characteristics of the slag, the constraints placed on the feedstock, and the tight product specifications, Namakwa Sands has continually increased slag production since 1995. High furnace feed-on utilization and furnace stability, complemented by continuous improvement drives, will be thevehicle to drive performance in the short-term, with longer-term performance enhancements due to strategic process development. Keywords: Pyrometallurgy, Namakwa Sands, ilmenite, DC-arc furnace, titania slag, pig iron

Jan 1, 2006

By M. K. Gangal, E. D. Dainty

CANMET/MRL has been contributing to an industry/government program to assess the quality of air in mines, and improve the working environment for Canadian miners. The ultimate aim of this program is to recommend a sampling methodology and appropriate concentration limits for both the soot (diesel particulate matter - DPM) generated by diesel equipment, and respirable combustible dust (RCD) as measured underground. The program was conceived by the Canadian Adhoc Diesel Committee, which consists of representatives from seven major Canadian mining companies, three provincial inspectorates, one union representative, two manufacturers of diesel equipment, and CANMET, a Federal Canadian research agency. This paper describes the modification and laboratory confirmation of an existing methodology for the sampling and analysis of DPM/RCD, including: sampling problems, filter selection, filter efficiency, DPM size distribution, the approximate performance of fractionating devices, and it reports the results of current ambient measurements of exposure levels in Canadian underground mines. Because of the concern about the health impact of DPM/RCD on mine workers, North American agencies are in the process of establishing limits for these aerosols. So far, the Province of British Columbia is the only jurisdiction in North America to legislate the maximum exposure level of RCD in its underground mines, i.e. 1.5 mg/m3 interim level recommended by the Adhoc Diesel Committee. It has also recommended the use of the CANMET/ADHOC RCD sampling protocol.

Jan 1, 1993

Notices COMPETITION FOR STUDENT MEMBERS OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY Each year the Institute offers a prize (or prizes should the entries warrant it) of up to RlOO for the best paper or dissertation on a topic appropriate to the interests of the Institute. The competition is open to all Student Members of the Institute. APPLICATION AND PRACTICAL OPERATION OF HYDROCYCLONES Dr H. F. Trawinski of Amberger Kaolinwerke, Hirschau, West Germany, gave a very interesting lecture on this subject to an audience of over one hundred, composed largely of members of the Institute, on 15th August, 1973, at the University of the Witwatersrand. ROTARY INTERNATIONAL Applications are invited before 15th March, 1974, for the following awards of The Rotary Foundation: Post-graduate Fellowships Under-graduate Scholarships Awards for Technical Training Awards for Teachers of the Handicapped. NIM REPORTS Report No. 1509 The instrumentation developed for electrochemical studies of the le(Whing of uranium dioxide. Report No. 1550 A fundamental study of the dissolution in (Wid solutions of uranium minerals from South African ores. Report No. 1552 The preparation and analysis of minerals for use as reference material.Progress report No. 2. Report No. 1556 The spectral analysis of solutions.2. The analysis of leach liquors, concentrates, slags, and residues. Report No. 1559 A cost assessment of the production of elemental sulphur by chlorination roasting. Report No. 1562 Application of a flotation model to an industrial plant

Jan 11, 1973

By M. R. Leonard

It is estimated that between 5 and 15 pounds of solid waste are generated monthly by each individual. Finding a final resting spot for such waste is an important matter. In the "good ole days," dumps of every description and condition were available. Not so now. Almost all states have adopted and are enforcing strict regulations regarding the disposition of solid waste. Many companies, owing to the nature of their business, have potentially good waste-disposal sites available. Cleveland Quarries Company falls in this group; but in spite of our having state and county permits, opposition by the local community denied us the opportunity to provide a needed local service.

Jan 1, 1974

By E A. Agorhom, M Beyuo, C Owusu, I Quaicoe

Understanding the mineralogy and liberation of gold particles in an ore is key to the development and optimisation of gold processing operations, being cyanidation or gravity separation. This can be achieved through basic historic geological information, gold deportment studies, chemical speciation and metallurgical test works. The present study assessed the nature of the occurrence of gold particles (mineralogical composition, liberation, associations and surface chemistry) and its effect on the process route (cyanidation and gravity separation) of a typical paleo placer gold ore deposit within the Tarkwaian Rock system. The investigative approach used involved chemical assay, quantitative X-ray diffraction (QXRD) and quantitative evaluation of minerals using scanning electron microscopy (QEMSCAN). The ore samples (A, B, C, D, E, F) used were obtained from six active pits of a gold mine working on this orebody. The results of the mineralogical analysis revealed that the ore is highly oxidised and comprised quartz (>80 per cent) and Muscovite mica (>6 per cent) as the major mineral phases in all the samples. Trace amounts of hematite, kaolinite and todorokite were also identified in all the samples. The chemical analysis showed presence of gold (Au) in all the samples with samples B (3.62 g/t) and C (3.96 g/t) containing the highest concentrations. Trace amounts of copper (Cu), iron (Fe), sulfur (S), aluminium (Al), arsenic (As) were also detected in all the ores. The QEMSCAN mineralogical liberation and gold association results revealed that the gold grains were relatively coarser in all samples (P80 > 80 µm Au in size) except F (P80 < 32 µm Au in size). Gold grains were highly liberated especially in sample B with the majority of the locked gold grains forming complex associations. All the samples responded well to cyanidation and gravity separation except samples C and F, respectively.

Aug 24, 2022

By Thomas J. Peters

The King Mountain study area is centered about 120 air km northwest of Blackfoot, and 30 air km north of Arco, Idaho. The study area makes up the southern one-third of the northwest-trending Lost River Range--the highest mountain range in Idaho. The area is predominantly underlain by Paleozoic-age marine limestone and lesser dolostone, with a relatively small inlier of silica-rich, Ordovician-age quartzite. There are vast, unquantified resources of these industrial minerals present; however, special markets need to be developed for these resources which are near enough for transportation costs to be competitive. Five prospects were found in the study area; however, only one, the Elbow quartz silica prospect, contains resources and current claims. There has been no mineral production in the study area.

Jan 1, 1993

By N. S. Dalal, X. Shi

"It has been recently suggested that the exceptionally high antitumor and antibacterial activity of natural fredericamycin A (FMA) is related to its ability to spontaneously generate the superoxide anion (02-) and hydroxyl (""OH) radicals in aerobic solutions [Hilton, B. D., Misra, R., & Zweier, J. L. (1986) Biochemistry 25, 5533]. With a view to understand the mechanistic details, attempts were made to reproduce earlier electron spin resonance (ESR) evidence for the oxygenated free radical formation in well-aerated solutions of natural FMA in dimethyl sulfoxide and dilute H 20 2• Little or no evidence was obtained for the formation of the 0 2- and methoxy (""OCH3) radicals, while the detected formation of the 'OH and methyl ('CH3) radicals was attributable largely to mechanisms not involving FMA. These results thus reopen the T question regarding the mechanism of its exceptionally high tumoricidal-bacteriocidal activity. This paper reports on an electron spin resonance (ESR) investigation of the formation of oxygenated free radicals in solutions of natural fredericamycin A (abbreviated as FMA) which has recently been reported to be a highly potent anti¬tumor antibiotic (Pandey et al., 1981; Warnick-Pickle et al., 1981). The impetus for this undertaking was provided by recent reports (Hilton et al., 1986; Stinson, 1986) suggesting that the strong tumoricidal activity with high therapeutic—toxic index of FMA was related to its ability for the spontaneous generation of superoxide anion (02-) and hydroxyl (OH) radicals. For example, the suggested mechanism for the formation of 02- by FMA was (Hilton et al., 1986)FMA-OH + O2 FMA-O + H+ + 02-Here FMA—OH is simply the FMA molecule emphasizing the —OH moiety which becomes FMA-O, the free radical rep¬resenting the oxidized form of the drug. While some other highly effective anticancer drugs in current clinical application, such as bleomycin, are also thought to exert their antitumor effects via the formation of reactive drug-based or oxygenated free radicals (Carmichael et al., 1985; Gianni et al., 1983), FMA was considered unique in that only in this case the free radical formation was thought to be spontaneous, rather than through a metal- or an enzyme-activated process (Hilton et al., 1986; Stinson, 1986). Thus it was suggested (Hilton et al., 1986; Stinson, 1986) that FMA could be the forerunner of a new class of anticancer drugs. However, we noted that while the hypothesis seemed plausible, the reported ESR spectral evidence appeared to be ambiguous. Because of the high significance of the earlier conclusions (Stinson, 1986), we undertook a systematic ESR study of the radical formation in FMA solutions, and as discussed below, our conclusions disagree with those reported earlier."

Jan 1, 1989

By S. R. La Brooy, P. C. Earley

Gold and Resource Developments NL (GRD) operates the Macraes Gold Project in East Otago in the South Island of New Zealand, treating a carbonaceous, refractory sulphidic gold ore. The ore is concentrated by flotation, then reground, followed by CIL cyanidation, to minimise loss to the preg-robbing natural carbonaceous material. As the mine has progressed there has been some variation in the preg-robbing nature of the ore, with average overall gold recovery generally in the range 70- 75 %. The Macraes Gold Project has been operating since 1990 and still has an estimated 11 year mine life, which has stimulated the continuing drive to enhance gold recovery. Testwork in 1994 showed there was no improvement in CIL gold recovery after conventional acid pressure oxidation of Macraes Gold Project flotation concentrate. Hence roasting was initially considered as the preferred option to improve gold recovery, being the only established technology to deal with both carbonaceous preg-robbing and sulphide encapsulation. However Newmont Gold Company pressure oxidation technology, as used at Twin Creeks in Nevada, has proved to be applicable to the Macraes Gold Project concentrate. Pilot scale testwork has shown that both roasting and pressure oxidation could achieve similar CIL gold recoveries on the concentrate. However, capital cost, simpler arsenic stabilisation, the ability to operate autothermally at a lower concentrate sulphur grade and simpler environmental consenting factors, has tipped the balance in favour of pressure oxidation. Overall average gold recovery is expected to improve to approximately 84% with adoption of pressure oxidation. GRD has appointed Minproc Limited as EPCM contractor to install pressure oxidation at the Macraes Gold Project, together with upgrading the existing flotation and grind circuits at a cost of NZ$ 30M (US$ 16M). Construction is 60% complete and on schedule for 1 October 1999 start up.

Jan 1, 1999

By Ben H. Daud

The systems optimization approach to mine planning has led to the adoption of a number of mathematical and computer models for short, medium and long range planning of mining operations. In the realm of open pit mine planning, the most common uses of such an approach have been in the areas of optimal pit design and planning of materials handling operations. Since a truck-shovel combination is the most widely used method of materials handling in open pit mines, a number of models have been presented in the past to analyze and optimize such systems. Broadly, these models can be divided into two categories. The simulation model, which is primarily used as an aid in analyzing the performance of either an operating or a proposed haulage system under the influence of externally alterable parameters, and the linear or integer model which is used as a tool for short or medium term optimization of the system under the operating constraints. In the first part of this paper, a brief discussion is presented of the linear/integer optimization models presented in the past, and in the second part a new model is described which is actually a combination of the simulation and the integer programming models. In its bare essentials, the model consists of an integer optimization algorithm, but the constraints are regularly and dynamically updated by incorporating the conclusions drawn from a stochastic simulation model of the mine haulage system. Since the successive optimization is performed by the mine operator who manipulates the constraints to guide the model towards the optimum, the mystical black box approach is minimized and should help in adoption of the model by the mine personnel. Also, by combining the stochastic simulation model and the deterministic integer model, some of the advantages of each are acquired.

Jan 1, 1976

By Dave Bulled, Khiratt Husain

"The use of High Pressure Grinding Rolls is gaining significant interest as a replacement for SAG milling in the comminution of hard rock ores because of the potential for reduced costs in terms of energy and grinding ball consumption. Estimation of expected energy consumption for fullscale operations has conventionally involved the testing of a few fairly large samples in pilot scale HPGRs. This paper describes the development of a small-scale batch test method for determining a work index for HPGR of a large number of samples that can be used to show the variability of the ore as an integral part of a geometallurgical approach to circuit design and production forecasting.The test equipment that was developed comprises a hydraulic press with adjustable pressure operating on small batches of ore in a locked cycle test procedure. A work index measurement was determined that links the specific energy consumed in the test to the breakage achieved such that the index can be used to predict comminution energy requirements.The measurements were calibrated against laboratory scale HPGR equipment to develop a model for design and forecasting that includes crushers, HPGRs and ball mills in a complete comminution circuit.INTRODUCTIONEstimation of the expected energy consumption for full-scale HPGR operations has conventionally involved the testing of a few fairly large samples in laboratory and pilot scale machines (Danilkewich, 2006). With the financial input of five mining corporations, SGS Lakefield Research has developed a small scale test capable of providing relevant information on the variability of energy consumption and size reduction from drill core samples. It is our intention that the values measured in the test will be scaled up, through benchmark comparison with pilot sized and full sized HPGR units, to allow plant design and throughput forecast on a block by block basis of the mine plan using a new CEET program. CEET® (an acronym for Comminution Economic Evaluation Tool) is an advanced grinding design and performance predicting tool that uses energy relationships to model the performance of SAG / Ball mill circuits."

Jan 1, 2008

The southern portion of the Swan Coastal Plain, a geomorphological element formed since late Tertiary times, contains commercially exploitable accumulations of ilmenite, zircon, rutile and monazite associated with a series of raised shorelines. The location of the deposits is controlled by a locally outcropping Archaen granite/ granulite complex and a sea current pattern determined by local geography and a prevailing wind direction. A progression from medium to high titanium ilmenite is evident parallelled by progressive leucoxenisation as the age of the deposits increases. Variations in trace element content accompany this process. Circulating groundwater has caused vertical mineralogical variations within individual deposits and by precipitation of iron has formed layers of hardpan.The Geographe Bay deposits are of important economic significance.INTRODUCTIONObservations made during the course of a brief survey of the southern portion of the Swan Coastal Plain provide an outline of the geology and mineralogy of the mineral sand deposits of the area. This preliminary study will require considerable modification in the light of more detailed work in the future.REGIONAL GEOLOGYThe Geographe Bay area is situated in the south-west corner of Western Australia between longitudes 115&#176; O&apos;W. and 116&#176; O&apos;W. and latitudes 33&#176; 15&apos;S. and 33&#176; 45&apos;S.The general geology of the area is shown in Fig. 1 where the control of the physiography exercised by the Cape Leeuwin-Cape Naturaliste basement ridge is readily apparent. Between this ridge and the Precambrian east of the Darling fault lies the southern part of the Perth basin which contains outcropping Jurassic to Recent sediments and lavas (McWhae, et al., 1958).The Leeuwin-Naturaliste ridge is the exposed portion of L Assistant Production Managcr. Laporte Titanium (Aust.) Ltd.

Jan 1, 1964

By Bernd Kopacek

"Nowadays more and more consumers substitute their conventional TV-sets and computer monitors by LCD panels. In the near future huge amounts of LCDs will start coming back to recycling. As LCDs with hazardous mercury backlight lamps are used an appropriate recycling technology has to be implemented.IntroductionLiquid Crystal Displays (LCDs) are widely used in notebooks, organizers, mobile phones, pocket calculators, measuring and control instruments, electronic games, hand-held miniature TVs, audio-video equipment, large signboards, automotive displays and more and more also for PC monitors and TVs.According to a study from Stanford Resources (San Jose, California) the annual value of LCDproducts reached 35 billion EUR in 2002, about 30% of this within the European Union, representing a total area of 2,1 million m2 Liquid Crystal Displays. An annual increase rate of about 15% is estimated for the next years (up to 4,1 million m2 in 2005).As LCDs are already on the market for several years, larger quantities of the more than 2,5 billion LCDs are coming into their End-of-Life stage for treatment. In 2005 this figure will become even more dramatic - 40.000 tons of LCD-modules contained in 2 million tons of waste electrical and electronic equipment (WEEE) or about 30% of total WEEE within EU. An amount which is representing 400 million EUR costs for incineration.Currently the only method used to deal with redundant LCD units is incineration or landfill. Both are expensive and causes emissions into the atmosphere (global warming) respectively water contamination (Class II) and difficulties in biodegradation. Up to now there is no recycling solution for LC-Displays available.As a consequence European Commission requests the disassembly of LCDs with an area bigger than 100 cm2 in the Directive 2002/96/EC of the European Parliament and of the Council on Waste Electrical and Electronic Equipment (WEEE Directive) of February 13, 2003."

Jan 1, 2008

By J. Morris, R. Sellaro

El petrodiesel es un colector común para la flotación de carbón, pero la partición de compuestos orgánicos de diesel (DRO por sus siglas en inglés) en corrientes de proceso no ha sido ampliamente estudiada. Investigaciones preliminares sugieren que bajo esquemas de dosificación normales los contenidos residuales totales de DRO en aguas de procesos deben estar limitados a la fracción soluble en agua (WSF por sus siglas en inglés) sub-ppm. Es más, los hidrocarburos aromáticos poli-cíclicos (PAH por sus siglas en inglés) debería segmentarse de manera proporcional con los compuestos orgánicos de diesel (DRO). El propósito de este estudio fue confirmar estos resultados en pruebas de flotación realizadas en laboratorio. Se midieron los contenidos totales de DRO Y PAH en aguas asociadas con los flujos o corrientes de concentrados y relaves. Los resultados muestran que las aguas con concentrados tenían de manera consistente mayores cantidades de DRO que las aguas de relaves. Es más, los contenidos de DRO en ambos flujos generalmente se incrementaban con el aumento de la dosis de diesel. De acuerdo con la investigación preliminar, los DRO parecían estar limitados a la fracción soluble en agua (WSF) y los PAH tendían a segmentarse proporcionalmente con los DRO. Bajo condiciones de operación típicas, los DRO residuales no deberían representar una preocupación medioambiental, pero deben evitarse situaciones que permitan una sobredosis significativa de diesel.

Jan 1, 2014

By Suguru Kohno, Yoshihiro Momose, Masakazu Honma, Tokirou Kamosawa

Copper metal surfaces have been examined by an extremely sensitive surface analysis technique called temperature programmed photoelectron emission (TPPE). The surfaces were ultrasonically cleaned and subsequently abraded by a screw in organic solvents and water. The TPPE apparatus is composed of a Geiger counter with Q gas (He+ iso-C4H10). The curve of photoelectron emission (PE) intensity vs. wavelength from 300 to 170 nm, termed PE spectrum, was repeatedly measured at different temperatures in the temperature- increase process from 25 to 350°C. The number of emitted electrons in a PE spectrum (PE total count) increased, reached a maximum at-250°C, and decreased with increasing temperature. With the surfaces cleaned alone in the liquids the maximum PE total count decreased in the order C3H70H > (CH3) 2CHOH > C2HpH > CHPH > H2O. With the mechanically abraded surfaces in the liquids the maximum PE total count changed as a function of the abrasion period and the maximum tended to appear at higher temperature with increasing abrasion period; the maximum value at 10-min abrasion decreased in the order H2O > CHpH > C2HPH > (CH3) 2CHOH > n-C3HpH. It was suggested that the TPPE behavior can be related to the acid-base interaction between the alcohols and the abraded metal surfaces and the presence of a contaminant over layer on the surface. From the XPS analysis of the 01 s spectra it was suggested that the chemical change of the adsorbed oxygen to oxide oxygen with temperature plays a substantial role in the appearance of the maximum PE total count.

Jan 1, 2000