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By Vladimir Lobanov, Vladimir Skorohodov, Boris Radionov, Olga Makovskaya

"The synthetic sorbents and the activated carbons which are used for the metals extraction from weak process liquors are rather expensive. It is propose to use mineral and synthetic high-porous substances which sharply increased sorption properties by special processing. For achievement the desirable properties sorbents are impregnated by specially prepared solutions. Such solutions should contain the substances or its anionic forms which on the one hand are strong enough fixed in a supporter pores, with another are capable to form the insoluble compounds with extracting metals. Selectivity is provided by chemism of the reagent interactions with extracting metal. Due to the high concentration of a reacting ion in a sorbent phase the capacity and rate of sorption increases. Formed insoluble compound remains in a phase of the sorbent and necessity of its filtration disappears. For synthesis the sulfhydryl compounds which chemical properties allow to increase degree of extraction and capacity of the activated carbon were used. At hydrometallurgical processing of precious metals mineral raw materials the commercial solutions with the concentration of gold from 0,1 to 5 mg/dm3 are received. Commonly gold is precipitated from cyanic solutions by the zinc dust. The sorption methods are widely applicable. But the synthetic sorbents and the activated carbon using to these purposes are rather expensive. Expenses for sorbents even at its regeneration can reach 10-15 % from total expenses of gold extraction from ores. When sorbent regeneration, mostly for carbon, is not provided, this share increases to 30-40 %. Thereupon search of the sorbents combining availability, the sufficient capacity, demanded degree of extraction and the low price is actual. For the specified purpose it is offered to use the mineral and synthetic high-porous materials which sorption properties are sharply rose by special treatment. Among such substances are natural zeolites, silica gel, lignine et al. Similar treatment can improve the sorption properties of sorbents used in practice, particularly, the activated carbons. The simplest treatment of potential sorbents consists in its impregnation by specially prepared solutions. Such solutions should contain substances or its anionic forms - impregnating agents. These agents should be on the one hand strong enough fixed in a carrier pores, on the other hand are capable to form with extracting metals insoluble compounds. The more strong compounds are formed the high degree of metals extraction from solutions. The sorbents with similarly changed properties are named the impregnated sorbents."

Jan 1, 2008

By Bob Drew, Alfred Spanring, Kirschen. Marcus

"Increasing material conversion and energy efficiency, and decreasing carbon dioxide emission levels are crucial for sustainable production processes in the aluminum, cooper, and steel industries. RHI supports these targets by providing a diverse range of solutions including high quality refractory linings, optimum lining maintenance, and process improvements. In this paper examples are provided of process improvements and increased energy efficiency in copper refining, potential energy savings during electric arc furnace and ladle operations in the steel industry, and increased energy efficiency by improved heat transfer in anode baking furnaces in the aluminum industry. In all cases, RHI’s expertise in close collaboration with the customer resulted in an improved performance of the reactor lining and the actual high temperature process with a positive impact on the material conversion and energy efficiency and as a result a decrease in specific carbon dioxide emission levels.IntroductionRefractory linings play an important role in heat transfer during high temperature processes in for example the aluminum, copper, and steel production industries. Due to constantly increasing energy prices worldwide and the increasing demands for environmental and climate protection, improving the energy efficiency and decreasing emission levels of these energy intensive production processes is of significant importance. In this paper, the contribution of modern RHI lining technologies to energy saving measures and the corresponding reduction of specific carbon dioxide emission are described. The type of current refractory solutions for energy intense processes are illustrated with four examples: Optimization and increase of material conversion and energy efficiency in copper refining, energy saving potentials in both electric arc furnace and transport ladle operations in the steel industry, and heat transfer improvements during the carbon anode annealing process in the aluminum industry. These examples focus on particular production processes operating with a high proportion of recycled copper, steel, and carbon anodes. Increased energy efficiency directly decreases the specific energy related carbon emission levels whereas improvements to the metallurgical processes aim to increase material conversion efficiency and, therefore, decrease specific process related carbon emission levels. Significant energy savings can be achieved by maximizing the refractory campaign length through a combination of appropriate refractory material selection, grade zoning, correct installation, careful preheating, and effective maintenance strategies. Besides the efforts to improve the performance and energy efficiency of customer high temperature processes, RHI continuously promotes the development of new low emission carbon-containing refractory bricks and unshaped products."

Jan 1, 2008

By Doon Gibbs

In this talk, we review highlights of x-ray magnetic scattering studies performed during the last decade, concentrating at the beginning on experiments on the rare earth metal holmium.(1-4) Besides intrinsic interest in the x-ray scattering cross-section and its description, studies of this type are motivated by the possibility that new structural and magnetic properties of rare earth metals might be revealed, and that new techniques may thereby be developed. As a result, interest in x-ray magnetic scattering experiments. has grown rapidly during the last 10 years particularly, with the regular application of synchrotron radiation techniques- Magnetic scattering experiments have by now been performed at most of the x-ray synchrotrons around the world. In addition, insertion .device beamlines dedicated to x-ray magnetic scattering experiments are planned at each of the next-generation storage rings presently under construction in the United States (APS), Europe (ESRF), and Japan (SPRING-8). Generally, the results of x-ray magnetic scattering experiments may be analyzed within two regimes of the incident x-ray energy, namely, in the limit of high x-ray energies, when the incident x-ray energy lies above the excitation energy of any absorption edge, and at resonance, when the incident energy lies near an absorption edge. In the high energy limit, the amplitude for x-ray magnetic scattering has the simple form [L(Q)?A + S(Q)?B](5-7) Here, L(Q) and S(Q) refer to the Fourier 'transforms of the atomic orbital and spin magnetization densities, respectively, and the vectors A and B depend on the incident and scattered wavevectors and on the: incident and scattered polarization vectors. 7) Because the vectors A and B are not identical, the polarization dependence of the orbital contribution to the magnetic cross-section differs from that of the spin contribution. This leads to the possibility that the orbital and spin magnetization densities maybe distinguished, in x-ray scattering experiments. The same distinction is not directly possible by neutron diffraction techniques (in dipole approximation, where the polarization dependence of the orbital contribution is identical to that of the spin contribution), and is important to a fundamental understanding of the electronic structure of magnetic materials. A particular

Jan 1, 1992

By T. Xin

A vertical grain boundary intercepting a horizontal free surface forms a groove to reduce the combined surface energy of the system. We study grooving by surface diffusion with anisotropic surface energy. A recently developed delta-function model of facets is used to describe the surface energy with three or four fold symmetry. It is found that the groove grows following a similarity law. The self-similar groove profile is solved numerically by a shooting method. Even with strong anisotropy, the groove profile can be smooth if the exposed surface orientations do not include a facet orientation. The smooth self-similar groove shape is the same as an isotropic groove, but the size is reduced by a factor that depends on the degree of anisotropy. This induces a large error on the value of surface diffusivity if the isotropic model is used for an anisotropic system. In this talk. we will describe how to correct for this error.1 I Xin, T. and H. Wong, "Grain-Boundary Grooving by Surface Diffusion with Strong Surface Energy Anisotropy," Acta Materialia 51, 2305-2317 (2003). Keynotes: Grain growth, Surface Diffusion, Surface energy, Anisotropy

Jan 1, 2003

By Petr Stehlík

"This paper is aimed at showing and demonstrating progress in technologies and improvements in units for the thermal processing of various types of waste. The following areas are covered: units for the thermal treatment of hazardous industrial waste and common MSW, technologies for the thermal treatment of industrial and sewage sludge, utilizing waste in cement production (material and energy recovery), up-to-date off-gas cleaning systems, original and unique units for the thermal processing of polluted gases, low-NOx burners. The paper represents a review based on industrial applications, papers published in reputable international journals and a monograph under preparation.IntroductionThe present contribution is an overview of the activities and achievements of the Institute of process and environmental engineering (UPEI) of the Brno University of Technology (VUT). The Institute belongs to European leading teams in the field of the thermal processing of various types of waste. The research in the institute currently revolves mainly around a strategic project “Waste and Biomass Utilization focused on Environment Protection and Energy Generation” that is supported by the national government. Due to the limited space this paper is conceived as a review of papers published especially in reputable international journals.Main (strategic) target of the research is development of new, efficient processes (eventually modernized processes with novel original elements) for effective and highly efficient treatment of waste and biomass, including their maximum utilization as renewable energy sources while minimizing harmful emissions. To this purpose, highly advanced know-how for the design and construction of the related technology lines is being developed, supported by mathematical modeling (see e.g. [1]), experimental validation and optimization.Municipal and Industrial Solid Waste – Concept of Waste-to-Energy CentersThermal processing of various types of wastes is not only waste disposal and/or treatment at present. It has to be regarded as waste to energy process wherever and whenever possible and feasible. This observation was at the origin of the concept of new regional Waste-to-Energy Centers (WTEC), outlined in the following paragraphs. The proposal of the centers is based on a combination of experience, know-how and sophisticated approach. The main fact influencing the concept of WTEC is the necessity to treat different types of wastes. Typical types of wastes as well as main products of the processes in a WTEC are shown in Figure 1."

Jan 1, 2008

By M. Rockandel

"Universal Dynamics Ltd. of Vancouver, Canada has developed, patented and commercialized the ""REMERC"" process for the treatment of mercury contaminated sludges and soils. Mercury is extracted into an acidified and oxidizing, sodium chloride brine solution. REMERC was initially developed to treat mercury contaminated EPA listed wastes (K106) generated by the chlor-alkali industry. More recent work has expanded the capability;' of REMERC to include remediation of mercury contaminated sites, equipment and building materials.In the process mercury is currently recovered from solution by cementation on iron powder in an agitated reactor. The process recovers high purity elemental mercury (99.9% purity). Cementation typically recovers about 90-95% of the mercury in 30 minutes. Higher recovery is not necessary because of the recirculation of the leach solution. When treating highly contaminated chloralkali wastes (5-13% mercury content), REMERC will reduce the mercury laden solutions from 400-1,000 mg/L mercury to 50-100 mg/L. In the treatment of less concentrated wastes «1,000 mg/kg mercury) such as those encountered in site remediation, the treated solutions will generally contain 10-20 mg/L mercury. Cementation while being simple and able to achieve the required recovery has the. undesirable properties of; requiring a solid-liquid separation and adding iron to solution which must be precipitated, ultimately increasing the weight of residue to landfill. .The potential advantages of electrolysis were recognized early in the development of REMERC. Mercury electrolysis is well known in gold and chloralkali processing. Initial testwork utilized a liquid mercury cathode and a coated titanium anode both common to chloralkali producers. The mercury cathode appeared susceptible to polarization and solution impurities significantly affected performance. Agitation of the mercury pool improved performance but it was still not possible to achieve the reduction objectives. Current efficiencies were low, near 10%, and it was apparent that a relatively large cathode pool would be required to limit the current density. A number of electrode combinations with and without a membrane were then tested in a vertical electrode' configuration but the desired performance was not obtained."

Jan 1, 1997

By Art Johnston

Gas handling at Magma Copper Company's, San Manuel smelter receives process gas from a flash smelting furnace and four copper converters. The major gas handling equipment consists of four electrostatic precipitators and a sulfuric acid plant. Process vessels in gas handling are typically confined spaces. Lethal gases., mechanical and chemical hazards, and the difficulty of rescue, should an accident occur, makes this area a must in the safety plan. The presence of hazardous chemicals and explosive gases in process vessels and piping are of major concern when repairs are required. Proper job procedures are critical to prevent injury during repairs. This includes plant employees and contractors who are likely to be unfamiliar with the hazards involved. The safe operation of a gas handling operation must include the functions of operations employees on a daily basis. This includes a safe working environment and involvement. of all employees in the safety program. If an injury does occur quick medical response is critical to prevent serious injury. Medical responders must be adeqliately trained and prepared to treat the injured person without becoming victims themselves.. The methods used at Magma copper Company to deal with these safety problems are the focus of this presentation.

Jan 1, 1992