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By Hemraj Dangi, S. Murali, Bhisham Yadav, Mohini Saxena, P. Asokan

"Demonstration studies were carried on the use of fly ash as soil modifier and supplier of micronutrients to improve the agricultural productivity based on the process optimised at lab scale at Advanced Materials & Processes Research Institute, Bhopal. The field trials were conducted in Uttar Pradesh (North India) Orissa (South Eastern India) and Madhya Pradesh (Central India) under different soil and crop conditions. 100-650 tonnes of fly ash per hectare were applied depending upon the soil and fly ash characteristics. Both short and long term studies on impact of fly ash on soil and food quality were conducted. With the fly ash application, the edible yield of tomato, cabbage, potato, wheat, pea, onion, paddy, sunflower, maize etc., were increased from 12 - 46% as compared to the control soil where no fly ash was used. The crop response to various elements mainly heavy metals grown in soil and fly ash applied soil was found comparable to that of control, which are within the permissible limits and meet the food quality standards. The results of impact of fly ash on biotic and abiotic properties of soil, along with the quantity and quality of agricultural produces generated under pilot scale demonstrations in three different parts of India are discussed in this paper. The outcome of this work could act as guiding force for confidence building and to maximise the use of fly ash, generated from thermal power plants worldwide as one of the major mineral waste for agriculture purposes.IntroductionThe advantages of application of fly ash in terms of improvement of soil properties and crop yields have been published by various researchers in India and abroad. Attention is also given about the possible negative and beneficial impact of pond ash in agriculture due to presence of heavy elements, radioactive nuclides and plant nutrients in fly ash. It is evident from the analysis of Indian fly ash that the presence of heavy elements and radionuclides levels are comparable with normal soil. The positive impact that has been reported is with regard to germination, yield and crop growth. The significant impacts are: long term effect of heavy and toxic elements content of fly ash on soil and up take of these elements by plant. Pilot scale demonstration studies have been completed with varying soil crop-combination under different agro-climatic conditions showed considerable improvement in the productivity of cereals, oil seeds and vegetables."

Jan 1, 2008

By Rick Deschamps

A reoccurring problem with support of excavations in urban areas involves the placement of external support components like anchors or nails in right-a-ways, subway and utility setbacks, in areas occupied by adjacent structures, and within the property of non cooperative neighbors. Such a situation occurred for a project in Arlington, Virginia, which ultimately resulted in the preliminary design of a large footing supported cantilever retaining wall that was extremely costly and impractical to build. An innovative design alternate consisting of a series of vertical concrete elements (VCEs) supported by post tensioned tiedowns was proposed to the General Contractor and accepted by the owner. The VCEs were designed to serve as the main structural elements for both the temporary support of excavation system and the permanent wall. The VCE?s were constructed using single bite diaphragm wall panels oriented perpendicular to the excavation face including a rebar cage and tremie concrete. Threaded inserts were placed within the rebar cage to attach the cast in place exterior wall. Overall stability and lateral movement of the VCEs were controlled by high capacity vertical anchors embedded within the VCE. A detailed instrumentation program was installed to monitor the movements of the VCEs with relation to the excavation depth. The paper present the project case history by discussing the design concepts of the VCE, the construction approaches used to install them, the construction challenges encountered, and the performance of the unique system.

Jan 1, 2008

Research cruises dedicated to seafloor hydrothermal activity along the Kermadec arc first began with the Sonne-135 expedition in 1998. This was followed by the worldÆs first systematic survey for venting along an arc during the 1999 NZAPLUME I expedition. Since then, cruises dedicated to mapping plumes along the Kermadec arc include NZAPLUME II (2002), NZAPLUME III (2004) and ROVARK (2007). In addition, the manned submersible cruises SWEEP Vents (2004) and NZASRoF (2005) utilised the Shinaki 6500 and Pisces V, respectively, to sample in detail select hydrothermalsystems for mineralised samples, rocks and vent fluids. The ROVARK (2007) cruise was the first to deploy an autonomous underwater vehicle (ABE) along the arc which surveyed Brothers volcano at a far greater resolution than had been done previously by ships on the sea surface. While these expeditions have largely been led by GNS Science, together with its collaborators from National Oceanic and Atmospheric Administration, Pacific Marine Environmental Laboratory (NOAA/PMEL), significant contributions have been made by other groups from various nations, exemplifying the global interest in seafloor hydrothermal activity associated with intraoceanic arcs. This is an ASTRACT only. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By A. Longval, Q. Jiao, T. Shannon

In 2000, Xstrata Zinc (former Falconbridge Ltd.) Brunswick Smelter commissioned a modified lead blast furnace. Since then, efforts have been made to improve its operation in order to achieve optimal operation in terms of coke consumption, lead loss to slag, and improved environmental and hygiene conditions. This paper will review the important step changes in operational philosophy, undertaken since 2004, for the control of the blast rate, oxygen enrichment in blast, slag chemistry and charge level. Furthermore, a review of the improvements made in secondary materials consumed at the blast furnace will be made. This paper will also discuss the significant reduction of the frequency of accretion removal as a result of improved furnace operation.

Jan 1, 2008

By M. Holmes, R. Molnar, E. Norton, K. Baxter, J. Riordan

The Boleo Copper-Cobalt-Zinc-Manganese Project of Baja Mining Corp. is situated adjacent to Santa Rosalia on the Baja Peninsula of Mexico. The El Boleo ore is a mixed oxide-sulfide deposit with major values in copper, cobalt, zinc and manganese. The metallurgical process designed to treat the El Boleo orebody involves a sulfuric acid leach in seawater using oxidative and then reductive leaching to maximize metal extraction. The leach solution is separated from the barren solids via counter current washing through a series of high rate thickeners. Copper is recovered using conventional SX-EW processing as cathode. Zinc and cobalt are extracted from the copper SX raffinate after iron and aluminum precipitation. The CSIRO DSX solvent system (Versatic® 10 and LIX® 63 mixture) are used in this extraction. Manganese remains in the DSX raffinate and is recovered by soda ash addition as a high quality manganese carbonate precipitate. Zinc and cobalt are acid stripped from the loaded DSX solvent. Zinc is then re-extracted away from cobalt using Cyanex® 272 extractant and stripped into a highly concentrated strip liquor (+100 g/L Zn) and directed to either a spray dryer or a granulator for production of zinc sulfate monohydrate. The zinc solvent extraction raffinate, containing cobalt, advances to another SX circuit using Cyanex® 272, for the recovery of cobalt as cobalt cathode. In this paper, the detailed results from bench and integrated pilot plant testing for zinc recovery from the El Boleo ore will be described. The results of this testing are currently being used to engineer the commercial plant at El Boleo.

Jan 1, 2008

By Dennis R. Dolinar

The National Institute for Occupational Safety and Health?s Pittsburgh Research Laboratory conducted a full-scale test of a composite polyurethane-aggregate seal in a hydrostatic chamber at the Lake Lynn Experimental Mine. This composite seal consisted of a polyurethane and limestone aggregate core that was formed between two concrete block walls. In the hydro-static chamber test, water is used to pressurize the seal. During the test, the maximum average water pressure the seal was able to withstand was 18.9 psi. Further, the seal began to yield at an average water pressure of only 17 psi. At the time of the test, the minimum seal design requirement was 20 psi under 30 CFR4 75.335 (2005). Therefore, based on this test, the seal did not meet the regulatory minimum design requirement. Uniaxial compressive tests conducted on samples from the polyurethane-aggregate core revealed that both the compressive strength and the elastic modulus of the material were much less than that for polyurethane only with a density of 10.0?12.0 lb/ft3. The significant reduction in the strength and stiffness of the polyurethane-aggregate mixture results from the formation of a soft polyurethane foam around each piece of aggregate. The formation of the soft foam seems to be caused by residual moisture from the aggregate. The moisture also caused the density of the polyurethane in the polyurethane-aggregate mixture to be less than the design requirements. The lower density of the polyurethane in the mixture, along with the formation of zones of pure polyurethane only, resulted in the overall seal density being less than the design requirements. During seal construction, steps were taken to control the moisture, but were not successful. An analysis of the seal failure showed that the calculated shear stresses at failure and the estimated shear strength of the polyurethane-aggregate mixture are fairly close. This suggests that the strength properties of the polyurethane-aggregate mixture along with a weak zone of poorly bonded aggregate controlled the maximum pressure the seal could withstand. At the time of the seal testing, the minimum design requirement was 20 psi, as specified at 30 CFR 75.335 (2005). New emergency temporary standards for seal designs were promulgated on May 22, 2007, with a minimum requirement of 50 psi under specified conditions. However, it will be shown that the evaluation of the polyurethane seal performance as designed to meet the older 20-psi criterion can be relevant to the design requirements under the new standards.

Jan 1, 2008

By Eric S. Weiss

The National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted joint research to evaluate explosion blast effects on typical U.S. mine ventilation stoppings in the NIOSH Pittsburgh Research Laboratory?s (PRL) Lake Lynn Experimental Mine (LLEM). An innovative Australian-designed brattice stop-ping was also evaluated. After mine explosion accidents, MSHA conducts investigations to determine the cause(s) as a means to prevent future occurrences. As part of these postexplosion investigations, the condition of underground stoppings, including the debris from damaged stoppings, is documented as evidence of the approximate strength and the direction of the explosion forces. The LLEM data showed that a typical dry-stacked and coated solid-concrete-block stopping survived a total explosion pressure of ~6.7 psi (~46 kPa) and was destroyed at a total explosion pressure of ~7.6 psi (~52 kPa). In comparison, a typical dry-stacked and coated hollow-core concrete block stopping survived a total explosion pressure of ~3.4?4.3 psi (~23?30 kPa) and was destroyed at a total explosion pressure of ~3.6?5.2 psi (~25?36 kPa), depending on the length of the pressure pulse and the value of the pressure-time integral. A typical steel panel stopping design survived a total explosion pressure of 0.8 psi (5.5 kPa) and failed at a total explosion pressure of 1.3 psi (9 kPa). The LLEM data also showed that an obstacle blocking the path of a pressure wave resulted in a higher reflected pressure at the obstacle. An 8-in (20-cm) thick wet-laid solid-concrete-block stopping coated on one side survived a total explosion pressure of ~26 psi (~180 kPa); this stopping was not tested to failure. A 6-in (15-cm) thick wet-laid solid-concrete-block stopping coated on one side survived a total explosion pressure of ~14 psi (~97 kPa) and was destroyed at a total explosion pressure of ~25 psi (~172 kPa). An innovative Australian woven cloth stopping survived an explosion pressure of 4.0 psi (27 kPa) and was destroyed at an explosion pressure of ~6.1 psi (~42 kPa). These results will help investigators determine the approximate explosion forces that destroy or damage stoppings during actual coal mine explosions.

Jan 1, 2008

By John A. Organiscak

Enclosed cabs are a primary means of reducing equipment operators? silica dust exposure at surface mines. The National Institute for Occupational Safety and Health experimentally investigated various factor effects on cab air filtration system performance. The factors investi­gated were intake filter efficiency, intake air leakage, intake filter loading (filter flow resistance), recirculation filter use, and wind effects on cab particulate penetration. Adding an intake pressurizer fan to the filtration system was also investigated. Results indicate that intake filter efficiency and recirculation filter use were the two most influential factors on cab penetration performance. Use of the recirculation filter reduced cab penetration by usually an order of magnitude over the intake air filter alone because of the multi­plicative filtration of the cab interior air. Intake air leakage and filter loading affected the cab penetration to a lesser extent, while wind had the least impact on cab penetration between the calm and 10-mph wind velocities tested. Adding an intake pressurizer fan notably increased intake airflow and cab pressure with only minor changes to cab penetration. A mathematical model was developed that describes cab penetration in terms of intake filter efficiency, intake air quantity, intake air leakage, recirculation filter efficiency, recirculation filter quantity, and wind penetration.

Jan 1, 2008

By Kim Verbeken, Evelien Van de Steene, Marc Verhaege, Jeriffa De Clercq

"AbstractThe industry is confronted with stricter discharge levels and an increasing awareness to avoid toxic waste (such as heavy metal containing sludge obtained in physicochemical water treatment) and recover valuable metals. This can be realized by ion exchange or by electrodeposition. Both techniques however show an optimum concentration range to efficiently remove and/or recover metals: electrolysis can recover the metal in its metallic form but suffers from low efficiency when applied to diluted solutions, whereas ion exchange can only be applied economically in the low ppm range.A combination of ion exchange followed by electrodeposition was applied to an industrial wastewater. The strong acidic ion exchange resin was stripped with H2SO4 giving a solution of 9g/L nickel. From this solution, nickel was electrodeposited in an ammonia buffer on a Ti-mesh cathode with high current efficiency. It is shown that organic compounds (surfactants, brighteners, …) present in the industrial wastewater do not influence the recovery process.IntroductionAlmost all rinse waters emerging from metal plating plants are generated during the washing operation of plated materials. These solutions with low metal content must either be recycled within the process or be discarded to the surface water after decreasing their metal content to acceptable levels determined by the local environmental regulations, which become more and more stringent. Today, the most commonly used practice is a physico-chemical treatment (precipitation) and a resin post treatment to meet the standards. A more sustainable approach should use a technology to recover efficiently the metal or metal salt without the production of sludge and the effluent should be consistent with environmental regulations."

Jan 1, 2008

By Carlos Maurício Fontes Vieira, Sergio Neves Monteiro, Diogo Neves Henriques

"This work evaluates the effect of incorporation of an ornamental rock waste into an industrial clayey body used for roofing tiles fabrication. Formulations with 0, 10, 20 and 30 wt.% of waste were prepared by replacing the sand in the industrial clayey body. The plasticity of the formulations was determined by the Atterberg limits. Specimens were fabricated by 18 MPa press-molding and then fired from 850 to 1100oC. The specimens were tested to determine the water absorption, linear shrinkage and three points bending flexural strength. The results indicated that the waste improves the extrusion performance of the clayey body by decreasing its plasticity. The use of the waste was beneficial to the water absorption and mechanical strength of the fired clayey ceramic at temperatures above 1000 ° C.IntroductionOrnamental rock is a natural resource available in the municipal area of Santo Antônio de Pádua and located 150 km from the city of Campos dos Goytacazes, northe of state of Rio de Janeiro, Brazil. Intense industrial activity related to ornamental stones, especially gneisses, is traditionally occurring in the region. After mining, the flagstone is submitted to sawing to obtain blocks and then, after a manual operation, the final products are small flagstones [1,2]. During the sawing operation, a sludge composed of water and fine particles of rock is generated. A monthly production of 1000 tons of ornamental rock waste is estimated to be produced at Santo Antônio de Pádua. The final disposal of this waste has brought serious environmental problems. Since most industries do not have an adequate sludge treatment, the waste is contaminating the soil and underground waters as well as obstructing rivers and lakes.Ceramic bodies industrially fabricated in the municipal area of Campos dos Goytacazes, 280 km from the city of Rio de Janeiro, are still empirically elaborated using a mixture of local clays. These clays are predominantly kaolinitic mineral, associated with high plasticity. Due to the excessive plasticity of the ceramic bodies, it is common to have dimensional defects in the final products after the drying and firing processes. Moreover, the kaolinitic structure and the presence of aluminum hydroxide confer a refractory behavior to the local clays. This impairs sintering during the firing operation. In the case of clay ceramics for civil construction, this results in greater porosity associated with elevated values of water absorption and low mechanical strength [3,4]. To avoid these problems, it is necessary to reformulate the ceramic body composition. The addition of both non-plastic materials to reduce plasticity and fluxes to condition the refractoriness is a possible alternative."

Jan 1, 2008

By Nicola Baldo, Marco Pasetto

"Recycling of tyre rubber in the road pavement, may be one of the best way to reduce waste tires in large quantities and, at the same time, improve some engineering properties of asphalt mixtures. The paper discusses the results of an experimental study, developed in order to analyse the potentialities of crumb rubber from road tyres in bituminous mixtures, using the dry process. Two types of porous asphalt mixtures and reference mixes without rubber were formulated by the traditional Marshall methodology, and mechanically evaluated by means of the Indirect Tensile Stiffness Modulus test, the Creep test (with confinement), and the Indirect Tensile Fatigue Test. Results of this study indicate that the tyre rubber has a positive influence on the performance characteristics, depending also on the grading and volumetric properties of the mix being studied: an interesting increase of the fatigue life, a better stiffness behaviour at lower temperatures and a bigger permanent deformation resistance at high temperatures are guaranteed. Introduction Recycling the rubber from used tyres, in the construction of road pavement layers, is potentially one of the more interesting and advantageous solutions from both the technical and environmental points of view, in order to reduce the total amount of car and lorry tyres to dispose. In road-building techniques, a technology, termed “wet”, for modifying bituminous binders with crumb rubber has by now become well consolidated. There have been numerous scientific studies conducted on this technology and its applications, particularly in the United States, where it has been adopted and codified in specific technical regulations (ASTM D-6114). If the wet process can be considered amply tested, the same cannot be said for a second technology, termed “dry”, which deserves careful study to evaluate its suitability and advantages. In “dry” processes, the rubber is usually used as a partial substitute of aggregate of equivalent grading and mixed with bitumen after integrating the crumb rubber in the lithic skeleton."

Jan 1, 2008

By M. Omneya El-Hussaini, M. Galal Abdel Wahab, A. Mohamed Mahdy, M. Fathi El Shahat

"Um-Gheig Pb-Zn representative sample was collected from the main adite of Um-Gheig mine along Red Sea coast in Egypt. Its chemical analysis shows that, it contains 16% Zn, 2.3% Pb, 0.1% Cd and 0.1% B as elements of interest. After H2SO4 agitation leaching, the chemical composition of Um- Gheig Pb-Zn deposit ore residue assayed 2.26% Pb, 1.5% Zn, 0.085 % B and 0.01% Cd. This residue was leached with 20% HCl at S/L ratio 1/3 for 2 hours at 80o C. The chloride leach liquor was found to contain 18 g/l Pb, 13 g/l Zn, 0.1 g/l Cd and 0.75 g/l B with the corresponding leaching efficiencies 79%, 86%, 100% and 88% respectively. Lead was precipitated from the chloride leach liquor using concentrated H2SO4 to obtain PbSO4 with precipitation efficiency 96%. While boron was extracted by the selective resin Amberlite IRA743 with loading efficiency of 80%. On the other hand, Zn and Cd were precipitated using Na2S solution with 86.7% and 100% recovery efficiencies respectively.IntroductionLead-zinc ores occur in Egypt in a few localities distributed along the Red Sea coast between El Qusier and Ras Banas.. The reserve of the ore deposits has been estimated by Soviet and German Experts to be about 900,000 Ton, [1]. Onal et al., [2] recovered Pb from Pb–Zn sample containing 10.17 % Pb and 10.98 % Zn from Aladag in Turkey. El-Sherif, [3] used concentrated HCl to leach lead-zinc ore sample of Um-Sammuki area in Egypt. As had been published by Marchioretto et al. [4], the precipitation of heavy metals with lime, sulfide and caustic soda are the most commonly used economical methods for metal removal. Lead was completely removed from the anaerobically digested sludge by precipitation with NaOH and Na2S at waste water treatment plants. Mahdy et al., [5] had successfully extracted boron from the bittern solution of Qaron Lake by ion exchange resin (Amberlite IRA 743). The extraction of boron was mainly depending upon the pH value. They extracted 80% of boron at pH 5.5, while at pH 3.9 about 74% boron was extracted. Kabay et al. [6] used the column-mode to remove 1g/l of boron from geothermal waste water of the Kizildere-Geothermal Power Station by using Diaion CRB 02 Nglucamine- type chelating resins. In this regard, the removal of lead, cadmium and boron allow the residue to be reclassified as non hazardous material."

Jan 1, 2008

By Georgios N. Anastassakis, Nickolaos Georgiou

"Soil contamination by oil as well as by other organic pollutants poses a major problem to the environment. Various methods have been used to remove organic contaminants from soil, such as: biological, thermal, chemical and physical. Methods based on Mineral Processing principles have also been used (cyclone separation, gravimetric separation, attritioning and washing). This paper studies the possibility to remove a rich-in-contaminant soil fraction by applying flotation. The contaminated soil was artificially prepared by mixing soil with diesel fuel. Sodium dodecylsulfate (SDS) and a tertiary amine (TA) were used as collectors. The effect of collector quantity added and conditioning time was studied. The results showed that the removal of a rich-in-contaminant soil is feasible while a clean fraction is also obtained. In several cases, the removal of oil-contaminated soil approaches or reaches 100%. Introduction Human activities are intimately associated with environmental pollution to the air, water and soil, as well. Soil pollution from inorganic and organic compounds is of equal importance with that of air and water, as it results in soil degradation and its concomitant problems with respect to meeting the human needs (house building, agriculture etc). Heavy metals along with their compounds are encountered among the most usual soil inorganic pollutants. The corresponding organic soil-pollutants are oil, oil-derivatives, pesticides, various aromatic (benzene, phenols, cresols, toluene etc) and poly-aromatic (naphthalene, anthracene etc) hydrocarbons, as well as various other organic compounds (pyridine, cyclo-hexane etc). Oil remains the basic energy source sharing 38% of the global needs, being followed by coal and gas with a share of 26 and 21% correspondingly [1]. The entire activities related with oil production, transport and consumption promote pollution in the air, water and soil. Consequently, soil pollution from oil is favoured at refineries, storage sites (due to possible pipe and tank leakage, tank cleaning works, loading and transportation) and, finally, at the oil-selling sites. Oil (or diesel-oil) fuel is a mixture of hydrocarbons, with 10-20 carbon atoms in the chain of each. It is mainly composed of paraffins, naphthenes and various aromatic compounds. In general, oil is composed of 20-30% in aromatic compounds, 5-6% in naphthenes and the rest is paraffins [1]."

Jan 1, 2008

By Marta Cabral, C. A. Nogueira, F. Margarido

"Physical processing of spent batteries which includes shredding and sieving operation is the first step for chemical treatment by hydrometallurgy. A laboratory study was carried out to evaluate physical processing efficiency, by analysing the resulting particle size, of alkaline and saline mignon-type Zn-MnO2 batteries. After shredding with a tip shredder, results obtained showed that alkaline batteries were more efficiently size reduced than saline batteries. Difference in particle size distribution was larger for granulometric fraction -20+11.2 mm and also higher for saline batteries. Average diameters (d50) for saline and alkaline batteries were respectively 9.1 and 6.2 mm. Chemical composition carried out on several granulometric fractions allowed to identify metals distribution through size categories. This analysis showed that zinc concentration with the grain size was almost constant, while manganese decreased when particle size increased. More than 95% of iron scarp from the battery cases had a particle size higher than 5.6 mm.IntroductionRecycling process of spent batteries includes physical unit operations which involves a fragmentation step in order to open the battery cases and to allow the access of chemical reactants to the electrode materials, on further chemical unit operations. Shredders are usually used for that purpose, using cutting mechanisms and allowing efficient fracture of residues in order to promote further processing of the contained materials. Batteries are complex products with a large variety of sizes and shapes which causes serious difficulties for predicting and carrying out its fragmentation.Domestic-type batteries are essentially of the Zn-Mn systems and with cylindrical shape, varying from the large size Mono (or D) type to the small size Micro (or AAA) type [1]. Recycling of batteries involves collection, sorting [2] and metallurgical processing [3, 4]. In some processes, the first step of metallurgical processing is dismantling and size reduction by shredding. Research work on spent batteries considering grinding/shredding and physical separation of fractions is scarce [5-7], but investigation in this domain is very necessary."

Jan 1, 2008

By Wantae Kim, Jaechun Lee, Tatsuya Oki, Sungbaek Cho, Sangbae Kim

"Effect of attrition scrubbing on the recovery of platinum group metals(PGMs) from automotive catalytic converter was discussed. The attrition scrubbing as comminution and separation process was effective for the recovery of the catalyst layer, ?-alumina, from ceramic supporting matrix, cordierite, by physical impact and shearing action between particles in the scrubbing vessel. The catalyst layer was dislodged from the surface of the supporting matrix into fine particles less than 45µm by attrition scrubbing. The production of fine fraction less than 45µm increased as the residence time for attrition scrubbing increased. The fine fraction obtained at the residence time of 40min contained 19.25% CeO2, 1.93% ZrO2 and 418.8ppp PGMs. The recovery of ?-alumina in the fine fraction increased as the residence time increased. Simultaneously, the recoveries of CeO2, ZrO2 and PGMs increased and reached up to 82.9% CeO2, 78.7% ZrO2 and 78.9% PGMs at the attrition scrubbing time of 40min. The production of the fine fraction and recovery of ?- alumina increased when the solid concentration and initial feed size increased.IntroductionThe automobile catalytic converters contain appreciable amount of PGMs. Currently several million tons of used catalytic converters are disposed annually worldwide, each containing about 0.5-1g of platinum and 1-2g of all PGMs1). The recovery technologies of PGMs from spent catalytic converters have been thoroughly reviewed by numerous researchers since last decades. Two types of methods, wet and dry processes, have been commercially operated. In the wet process, the PGMs on the spent catalytic converters were dissolved mostly in the form of chlorocomplex, MCl6 2-, by contacting with aqueous solutions. Subsequently the resulting solutions are treated to concentrate and the precious metal ions are reduced by introducing metals such as Al, Fe and Zn in the concentrated system2). In the dry process, the spent catalytic converters are melted, in some case with CaO, at an elevated temperature to produce a low viscous slag. The PGMs in the melt are separated by allowing them to adsorb on Fe or Cu having high specific gravity7). Although highly pure precious metals could be obtainable, the recovery technologies of PGMs currently operated seem not to be cost-effective since PGMs embedded in these types of catalytic converters are present in very small quantities."

Jan 1, 2008

By Isabella Lancellotti, Fabrizio Passarini, Luisa Barbieri, Fernanda Andreola, Ivano Vassura, Luciano Morselli

"The techniques able to incorporate wastes by means of a heat treatment present the advantage to fix the residue with chemical bonds. Among these techniques there are vitrification and sintering which are characterised by different operating temperatures in the range of 950-1500°C and the involved raw materials develop silicatic crystalline phases and glassy matrices capable to immobilize heavy metal contents in the waste matrix. In this work incinerator bottom ash, polishing and glazing ceramic sludges have undergone to thermal treatments in order to valorise the waste as secondary raw material for the obtainment of re-products. The chemical efficiency of the process adopted has been evaluated by comparing the results of release tests applied to the as-received wastes and to the thermally treated materials in order to verify the effectiveness of the different matrices to fix the waste components.IntroductionVitrification is one of the most promising technological options for the treatment of some kinds of waste. The high temperature involved in the process (1200-1500°C) leads to the complete destruction of organic pollutants, such as dioxins, and glassy network formed can incorporate heavy metals. Some vitrification processes naturally occur: glasses produced by volcanic eruptions, such as obsidians (Na2O-K2O-Al2O3-SiO2) and basaltic (CaO-MgO-Al2O3-SiO2) rocks, are basically inert materials even when they contain toxic elements, because these are embedded in an extremely stable glassy matrix. The disadvantage of vitrification is that it is an energy-intensive process involving relatively high costs, therefore its use is better justified if a high-quality product with optimised properties can be fabricated. The most effective way to improve the properties of the vitrified material is the transformation into glass ceramic. This is a fine-grained polycrystalline material (typically from 50% to 98% of the volume may be crystalline) formed when a glass of suitable composition is heat treated and hence undergone to controlled crystallisation (phenomenon named devitrification). The three key variables in the design of a glass-ceramic are: glass composition which controls glass viscosity related to the effectiveness of nucleation and rapidity of crystallisation; glass-ceramic phase assemblage (that is, the types of crystals and the proportion of crystals to glass) which is responsible for many of the physical and chemical properties; nature of the crystalline microstructure (crystal size and morphology and the textural relationship among the crystals and glass) which is the key to many mechanical and optical properties. In particular, a partly crystalline material can be obtained by powder sintering."

Jan 1, 2008

By Susan Fredholm, Randolph Kirchain, Jeremy Gregory

"Jurisdictions across the world have struggled to create and finance systems that can effectively collect and process electronics waste (e-waste). Many different system architectures have been proposed and implemented, but it is difficult for policy-makers and system architects to compare the costs and benefits of different systems, particularly when the systems operate in different contexts. This paper presents a systematic methodology that seeks to address this challenge and uses data from several existing electronics recycling systems across the world to illustrate its implementation. The methodology characterizes three main system characteristics: architecture (e.g., financing and collection methods), context (e.g., jurisdiction population, density, and wages), and performance, both economic and materials collection. A comparison of systems in Europe and North America with different system architectures and contexts illuminates the importance of using the methodology to discern the extent to which architecture and context drive system performance.IntroductionElectronic waste (e-waste) recycling offers several environmental benefits when processing is done responsibly. The controversy around e-waste recycling systems rarely debates such benefits; rather, it focuses on the characteristics of an effective system and whether benefits outweigh costs. Historically, the costs of recycling most electronics have outweighed the value of the scrap recovered. Thus, in the absence of legislation, e-waste recycling systems have been limited to private recycling of high-value waste with minimal consumer participation. E-waste recycling systems now exist in many locations worldwide including Asia, the European Union, Canada and the United States and the amount of related legislation continues to increase. Numerous approaches have been proposed including landfill bans, extended producer responsibility (EPR) and consumer advance recovery fee (ARF) funded recycling systems."

Jan 1, 2008

By S R. Pecover

AustraliaÆs opal and sapphire mining industry has fallen from its peak in the 1980s and 1990s into a significant low today. This is not due to exhaustion of the resource, but instead an over-reliance of the Australian miner on achieving a fair price for the gemstone product from offshore middlemen dealers. Gemstone and geological research is also at a low as Federal higher education expenditure has fallen with research institutions relying increasingly on private funding in an environment of restricted autonomy and flexibility for researchers. What little remaining research skills the universities have is being bled into the private sector as a result of the mining boom and encouraged by lower than average academic salaries. Nevertheless, some highly innovative research has been taking place, often by self-funded individuals and retired academics simply with a desire to advance the understanding of the particular branch of science in which they are interested. New models for the formation of sapphire and opal are now beginning to be applied to the exploration for these gemstone commodities. This research, together with well thought out plans for managing the gemstone product through its value-adding steps to the jewellery retail level, has the potential to bring about a resurgence in the Australian gemstone industry.

Jan 1, 2008

By N. M. S. Balbinot, A. L. Rodríguez, C. M. Mahlmann, R. de C. de S. Schneider

The use of sunflower oil co-products it was studied for production thermoplastic composites. Thermoplastic composites have been processed in polyethylene matrices of virgin linear low density polyethylene (LLDP) or recycled. Samples have been formulated with 10% mass fraction of sunflower bran, seed coat and mixture of bran and seed coat. The material characterization has been achieved by mechanical tensile test and Shore D hardness and by density physical testing. The results have demonstrated better properties to thermoplastic composites with sunflower seed coat.

Jan 1, 2008

By Javier Antoñanzas, Susana Caballero, Eduardo Fernández, Jorge Aragón, Juan Carlos Múgica, Lourdes Yurramendi

Air Pollution Control (APC) residues treatment by plasma was studied as a technology for vitrification. During the project a protocol to verify the plasma technology was developed and afterwards applied to a specific case study: the APC residues from Municipal Solid Waste Incinerators (MSWI). Different operational conditions were tested and the vitrified products obtained were analyzed using standardized leaching tests in order to evaluate their new properties concerning safety storage. Two leaching tests were used for the evaluation, the European EN 12457-4 compliance test for leaching of granular waste materials and the French XP X 31-211 test for the determination of the leachability of a solid waste material initially massive or generated by a solidification process. Finally, conclusions about the environmental performances of the technology were obtained.

Jan 1, 2008