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By Jiu-ju Cai, Wen-chao Liu, Fei Liu

"The material flow of urban eco-industrial system includes linear flow, recycling flow, branching flow, converging flow, etc., which consequently lead to the system complexity. Comparing the urban eco-industrial system to ecosystem, it can be concluded that this complexity is caused by the system adaptability. In the system, the interaction and adaptability between the agents themselves and between the agents and the environment stimulates the changes of material-flow mode, which lead to the evolvement from traditional industry to the eco-industry. Focusing on the evaluation of this evolvement process, two material-flow models are established in this paper, one of which is for the system itself and the other for the agents in system. The latter model is applied to analyze the interrelationships among mass, energy and pollutant flow in the iron and steel industry, and to make the direction clear to improve the resource and energy efficiency and decrease the environmental load.1 IntroductionIndustrial system is a subsystem of urban system, and they are interconnected and interrelated through material flow. The industrial development causes the urbanization. But the traditional industrial mode, characterized by high consumption, high pollution and low efficiency, also causes the “urban problems”, and leads to the reduction of resources carrying capacity and the increase of environmental load. Nowadays a lot of researches focus on how to realize the sustainable development of industries and cities. Thus comes the urban eco-industrial system guided by industrial ecology.Regarded as a Complex Adaptive System (CAS), the urban eco-industrial system evolves for quite a long time. According to Holland’s description on CAS, CAS consists of adaptive agents, which interact with the environment and other agents, learn and accumulate experiences, and accordingly change their own structures and motion modes. In this way, the evolution of the whole macro system is improved [1]. The evolution from traditional industrial system to urban eco-industrial system is mainly reflected in the variety of internal material flows which include not only linear flows but also recycling flows. Therefore, to construct models which clearly analyze industrial metabolism, is of great importance to evaluate industrial system evolution.The article is organized as follows: Section 2 describes the urban eco-industrial system. Section 3 presents the system-oriented metabolic analysis model and the agent-oriented one, analyze the interrelations of energy flow, material flow and pollutant flow in Chinese iron and steel industry through the latter model, and indicates the directions of improving the resource efficiency and energy efficiency, and decreasing the environmental load. Section 4 concludes."

Jan 1, 2008

By Ilkka V. Kojo

This paper gives an overview of the primary copper smelting business during the years of flash Smelting in the light of various projects taking into account the sustainability of copper production. Also the future challenges of copper smelting are addressed with special emphasis on the environment. Flash Smelting connected with either Peirce-Smith converting or Flash Converting offers the most economical and environmentally friendly alternatives for the smelting of normal and lean copper concentrates. For rich copper concentrates the feasibility of Outokumpu Direct Blister Flash smelting is, understandably, beyond compare. When the total investment costs for building a smelter and acid plant are considered, it is clear that Flash Smelting is the more feasible option compared to bath smelting. Reduction of equipment and operating cost is further achieved by the LUREC-process developed by Outokumpu Technology for operating plants with SO2-contents up to 25 % by volume. As an example the Kennecott-Outokumpu Flash Converting Furnace (FCF) has been in operation at Kennecott Utah Copper for 10 years and has achieved excellent results both environmentally and production vice. The FCF treats the entire output of the Kennecott Flash Smelting Furnace and has excess converting capacity. Furnace life, initially projected at two to three years, is now projected to be more than 5 years. It is likely the life will be essentially the same as a well-operated Flash Smelting furnace.

Jan 1, 2006

By G. J. Shiflet

This paper will review work done in our laboratory on the formation, thermodynamics and crystallization of aluminum based metallic glass with the addition of rare earth elements. The results demonstrate that the metallic glasses are truly amorphous and not microcrystalline and that they are unusual in their formation because the alloys contain 90 at. % aluminum and there is no deep eutectic present in the phase diagram. Tensile strengths that exceed 900 MPa are obtained for several of the compositions and exceed 1000 MPa after partial crystallization.

Jan 1, 1992

By A. Kapilashrami

Slag foaming proves to be both blessing and curse for the process productivity, depending on where in the process it occurs. In pyrometallurgical processes, slag foaming is often a result of chemical reactions taking place in the slag. As the slag composition and reaction rates are changing, foaming occurs under dynamic conditions. In the present work, slag foaming was studied with XRF. The foam displayed a fluctuating behaviour, unaccountable by existing models. The concept of foaming index was found not to be satisfactory in describing the foam, resulting in the need for alternative theories. The rate of fluctuations was seen to be related to the difference between rate of gas generation and rate of gas escape from the system (Ug-Ue) as well as the bubble sizes. Thus, model development of dynamic foaming phenomenon has to take the effective chemical reaction rate as well as the bubble sizes into consideration. The first step in obtaining foam is to form bubbles. In the present work, gas bubbles were generated through chemical reaction at interface between two immiscible liquids and the bubble formation was studied optically. The gas bubble size was seen to be uninfluenced by the reaction rate. However, bubble formation was seen to take place in one of the phases and since the bubbles consequently traversed the interface under the influence of buoyancy, the viscosity of the first phase was found to influence the final bubble size where increased viscosity would yield a larger bubble size.

Jan 1, 2006

By J. M. Casas

This work presents the development of an ionic equilibrium model and its use to simulate the distribution and concentration of chemical species (speciation) in sulfuric acid - cupric sulfate solutions in the 0-2 pH range, 0.1-10 gpl copper concentration range and 15-45°C temperature range. The model consists of a set of equations which represent the equilibrium relationships for the ionic reactions and the mass balances for the components present in the system. The effect of ionic strength was taken into account by correcting the equilibrium constant in concentrated solutions. Several species can be formed at different pH and temperature values, the principal being: HSO-4, SO42-, CuSO4(aq), Cu2+, and H+ in order of increasing solution acidity. Simulations show that concentrations are highly dependent on pH. The sulfuric acid speciates mainly as bisulfate ion (HS0-4) and hydrogen ion (H+) at pH values lower than 1. The model presented in this work can be applied to predict and analyze the solution composition in electrolytic copper processes such as electrowinning, electrorefining and electrodialysis, as well as the purification of various industrial solutions.

Jan 1, 1999

By M. D. Bishop

Loss of organic solvent extraction circuits occurs through several accepted methods. Losses are commonly attributed to entrainment of the plant organic and evaporative loss of diluent. Evaporative losses of diluent have been estimated using various models or by considering all losses over and above entrainment to be due to evaporation. Other possible loss mechanisms are discussed and data on losses during weather conditions are presented. Accurate estimation of evaporative loss is vitally important to the industry due to both cost factors and environmental concerns. Data for and description of the Diffusive Flux Model are presented as an improved-method of estimating evaporative losses:

Jan 1, 1999

By Jiu-ju Cai, Wen-caho Liu, Fei Liu

"With the northern cities of China as study objects, and to confirm Ground-source heat pump system of the environmental benefit and the developing direction. In this paper LCA was applied to the environmental benefit Ground-source heat pump System from raw materials acquisition to system production, utilization and disposal. The conclusion shows that Ground-source heat pump system of the environmental benefit in the northern cities of China. The result showed that Ground-source heat pump system had remarkable environmental benefit. 1. Introduction Life cycle assessment Originate in the sixties of last century, what it paid close attention to is to obtain processing from products raw materials, the processing of products produces, products transportation, products use and maintain to the influence to environment of course. It is a products -oriented environmental management style, it is the environmental management mode of meeting the needs of sustainable development strategy [1]. The research object was in the city and lie in the North of China, would undertake Beijing Olympic Games some football matches in the second half of 08, in order to improve the local environment, adjust the energy structure, reduce the heating consumption of urban coal in the centre, eliminate the coal-burning boiler under 10 tons, since 2005, the local government promotes and utilizes actively the heat pump technology in the source substitute the heating of coal-burning boiler. At present, this area is adopted the technological heating area of heat pump of source reach 20 million square meters, account for this area heat 11.2% of area always, it is estimated, by 2010, adopt the technological heating area of heat pump of source will reach 65 million square meters, the proportion of the area rises to about 30% to account for this area and always heat [2 ]. Study to the whole lifespan of heating system of heat pump of ground source of this area on the basis of LCA method, obtain the products impact on environment of different stages and environmental benefit, find out and reduce or dispel the measure of the influence, improve the environmental benefit of the ground source heat pump heating system.2. MethodologyThe research approach used in this research is the Life cycle assessment, the frame of the research approach is goal and scope definition, the inventory analysis, impact assessment, interpretation.[3][4][5]"

Jan 1, 2008

By Bruce Cavender

Managers are frequently faced with the decision to perform a task or manufacture an object in-house or to hire an outside vendor to perform the function. Outsourcing decisions are usually driven by economics: work is outsourced if it can be completed at a lower cost or in a shorter time than it can in-house. A technique termed incremental analysis can be used to make this decision. Incremental analysis examines the financial impact of outsourcing decisions as a function of the firm's fixed and variable operating costs. To use this tool, individual components of production cost are identified as being either constant or varying with levels of production activity. The assignment of cost type can be made in several ways: though analysis of historical operating data, understanding of individual expense types, and so forth. Changes in fixed and variable costs resulting from each potential course of action are explicitly identified to project the financial outcome of each alternative. The alternative having the greatest positive impact on profit is selected for implementation. By using the fixed- and variable-cost framework, the analysis is conceptually straightforward and substantially simplified. Production managers can therefore use incremental analysis as a tool for fast economically beneficial decisions on a real-time basis.

Jan 1, 1999

By A. A. Bustos

Four Air Liquide Shrouded Injectors (ALSI ) were installed and operated for over one year in a Peirce-Smith converter at the Falconbridge nickel smelter in Falconbridge, Ontario, Canada. A shrouded injector consists of an inner pipe and an annulus, through which high oxygen enriched air and nitrogen flow, respectively The nitrogen cools the injector and protects the refractory in the vicinity of the injector tip, allowing for substantial increases in oxygen flow rates to the converting reactions. Several injector designs were tested to study the effect of changes in the cross-sectional area and changes in the entrance geometry of the annulus. An optimum design would minimize the injection pressure required for a given flow rate to achieve choked flow conditions at the tip of the injector. The operation of the ALSI was simple and did not require any special care or maintenance, either between blows or between converter cycles. In particular, the shrouded injectors did not require punching, as is the case with conventional tuyeres. In terms of refractory performance, the ALSI, operating at 30-40 % oxygen enrichment, were superior or equal to the conventional tuyeres, which operated at 21-23% oxygen. The results of the demonstration program led Falconbridge Limited to implement the ALSI technology on a commercial scale The paper presents the demonstration program results in terms of gas flow rates, accretion formation, punchless operation and refractory wear.

Jan 1, 1999

By V. Jiricny

The novel spouted-bed electrode (SBE) is a cathode system where copper is deposited at a high current density in a moving bed of copper particles. Preliminary results on the deposition of copper from acidic sulfate electrolytes using this novel cathode system were described during Copper '95 conference. Despite a high current density, the electrical energy consumption was equal to or lower than that in the conventional electrowinning. The present paper describes more investigations on SBE. The SBE consists of copper particles with approximately 1 mm diameter onto which copper is deposited from acidic sulfate electrolyte whose composition is similar to conventional electrowinning. Three types of anodes were used in conjunction with the spouted-bed cathode, namely, DSA anode for oxygen evolution, and two novel anodes. One anode is less expensive than DSA; however it showed much promise in energy consumption. At a superficial current density of 2200 A/m2, the energy consumption was around 1.0 kWh/kg copper. The research activities described in this paper were supported by BHP Copper.

Jan 1, 1999

By Kamal Adham

Hydrochloric acid is used as lixiviant in such hydrometallurgy processes as synthetic rutile production and nickel extraction. The intermediary metal chloride is normally roasted to release gaseous HCl and a solid metal oxide. A large amount of fuel is required for this thermal regeneration, mainly to vaporize the water content of the feed solution. To conserve fuel, some energy recovery from the off-gas is currently achieved, but the fuel costs can further be reduced by process optimization and energy recovery from the gaseous, aqueous and solid products of the regenerator. Here, first the existing limitations to fuel efficiency in the industrial scale HCl regeneration roasters are described. Then, for the case of a dilute feed solution, options for pre-evaporation and fuel minimization are modeled and compared. Finally, energy recovery technologies including heat pumps, acid heat exchangers and solid waste heat boilers are described, and their potentials as the heat source for pre-evaporation of the feed are evaluated.

Jan 1, 2003

By Jean-Louis Dirion, Guy Depelsenaire, Patrick Sharrock, Souhila Kribi, Ange Nzihou, Jocelyn Ramaroson

"This study assesses the Novosol® process, an emerging technology developed by Solvay to treat heavy metals from dredged sediments using phosphoric acid. The main goal is to convert toxic metal ions, such as Pb2+, Cd2+, Zn2+ and Cu2+ to insoluble metallic phosphates. The effectiveness of the treatment was evaluated by performing the chemical reaction in a tubular reactor, followed by convective drying and maturation of the treated sediment at ambient temperature and finally thermal destruction of the organic matter by calcinations (500°C-700°C). Selected variables (acid concentration, volume fraction of solids, flow rate, drying and calcination temperature and time) were investigated. Laboratory scale experiments were carried out with various combinations of these parameters. The influence of the quantity of acid and the temperature of calcinations on physical properties of the sediment and stabilization of the heavy metals are discussed. Introduction The French territory counts 525 000 km of rivers which transport each year on average 6 million m3 of sediments. Their deposit causes the silting of channels, rivers and lakes. This completely natural phenomenon is exacerbated by the introduction of industrial and urban wastes into the erosion and sedimentation process. This silting leads to clogging of rivers, with a reduction in their flow rates. Consecutively, other problems appear, such as flooding risks, decrease of biological purification capacity and associated loss of the biodiversity. The presence of toxic compounds (from industrial, household or agricultural origins) in the sediments worsens the situation, and requires curing to restore the natural environment and its function. The dredged sediments are either spread on agricultural land, land tipped, confined or sent for chemical or physical treatment [12]. The first research programmes on toxic sediments appeared at the end of the Eighties in the United States, in Canada, in the Netherlands and in Germany. Several techniques of treatment were developed for the sediments; these techniques can be used alone or in combination. These techniques include extraction and concentration of the pollutants: the pollutants are isolated from the sedimentary matrix and the sediment is decontaminated. In some cases of organic contaminations, the pollutants are destroyed by chemical oxidation or biodegradation and in other cases, the contaminated material is either stabilized (mixed with hydraulic binders), or destroyed (incineration) [14,15]. Phytoremediation by afforestation has also been reported [19]."

Jan 1, 2008

By M. M. Salari Rad

An investigation of gold distribution in the mill products of Sar Cheshmeh beneficiation plant demonstrates that on average 44% of the gold is routinely recovered as a by-product in the copper concentrate, and the remaining is lost to the tailing. In order to evaluate the causes of gold losses, the distribution and mode of gold occurrence in the Sar Cheshmeh ore and mill products were studied. Searching for gold within samples and within individual grains of sulphide minerals was carried out by SEM in the backscattered electron mode and SIMS, respectively. The mineralogical distribution of gold revealed by microbeam techniques were combined with the results of relevant metallurgical experiments including, sizing, heavy liquid separation, and diagnostic leaching tests, and the nature and location of gold in the ore and mill products were determined. The combined results of the experimental approaches pursued suggest that while there are some gold in solid solution and/or -colloidal size within sulphides of the Sar Cheshmeh ores, "visible" gold is the principal form of gold occurrence at Sar Cheshmeh.

Jan 1, 1999

By Jitka Jandová

In this study, hydrometallurgical processing of waste ZnO flue dust arising during zinc removal from galvanized low-alloy steel sheets was investigated on a laboratory-scale to obtain electrolytic zinc. The flue dust was separated from flue gases, generated during heating waste galvanized steel sheets in an electric furnace under air atmosphere at temperatures of about 1000oC. The dust, comprising tetragonal ZnO and insignificant amounts of SiO2, was contaminated by Fe, Mn, Pb, Al, Mg, Pb, Cu and Ca. The dust was leached in 0.5 and 1.0M H2SO4 and/or in 20 and 30% NaOH at different temperatures and different liquid-to-solid ratios to determine the optimum conditions leading to the highest possible selectivity of leaching and efficiency of Zn extraction in minimum time. The subsequent electrowinning process was performed with refined zinc sulphate leach liquors and/or with untreated zinc caustic solutions. Zinc sulphate leach liquors were purified using a combination of a hydrolytic pH-controlled precipitation, cementation and carbon refining. Effects of operational variables on Zn electrowinning have been studied for both sulphate and caustic electrolytes. The conventional plate-plate electrowinning cell has been explored in this study. Comparison of results obtained for both zinc electrowinning from acid sulphate and alkaline solutions is presented contribution.

Jan 1, 2003

By M. S. Moats

A considerable amount of research has been conducted to determine the causes of anode passivation. Chemical and electrochemical reactions that occur after passivation have received little attention. Chronopotentiometry, linear sweep voltammetry, cyclic voltammetry, and impedance spectroscopy have been used to elucidate three reactions that occur after passivation of commercial copper anodes. These involve the dissolution of silver and subsequent cementation and transformation of selenides, the oxidation of lead sulfate to lead oxide, and oxygen evolution. The amount of silver dissolution depends on the silver content of the anode, the time to passivation, and the molar ratio of Ag/(Se+Te). The oxidation of lead from PbSO4 to PbOx explains a potential plateau of oxygen evolution. Silver affects the duration of oxygen evolution on the PbOx. Anodes containing kupferglimmer display a characteristic oxygen evolution potential. It is believed that kupferglimmer provides a lower overpotential for oxygen evolution than the other slime phases or passivated surface.

Jan 1, 1999

By C. Flores

The direct cementation of copper from a loaded D2EHPA 20 % vol. in kerosene using zinc, zinc-lead alloy and iron metallic powders was studied. Copper was loaded into the organic solvent from an aqueous copper sulfate solution. Results indicated that copper is reduced spontaneously with relatively fast reaction rates. The effects of several operating parameters such as water content in the organic system, initial copper concentration, reductant surface area, oxygen and nitrogen atmosphere, intensity of the agitation and temperature on the galvanic stripping of copper were studied. For a better understanding of the electrochemical reactions involved in the galvanic stripping, the dissolution of metallic copper in the organic solvent was also studied. Copper did not dissolve unless a small amount of water was present in the organic system. The results and possible reaction mechanisms are discussed.

Jan 1, 1999

By Alireza Zakeri

To evaluate the behavior of minor elements in the copper smelting process, activities of silver, selenium and tellurium at minor concentration were determined at 1473 K within the miscibility gap of the Cu-S-Me (Me = Ag, Se, Te) and Cu-Fe-S-Me systems varied in Fe/Cu ratio. Phase relations between the immiscible metal and matte phases in the foregoing systems were first established by a quenching technique at 1473 K to supplement the activity measurement data. A Knudsen-effusion mass spectrometer, capable of handling complex gaseous systems and relatively small vapor pressures, was adopted for activity determination. Using a multiple Knudsen-cell, the ion intensity of minor element in the sample under study was measured simultaneously with that in a reference sample. Activity was obtained from the ratio between the measured ion intensities as well as the known activity value of the minor element in the reference sample. Limiting activity coefficients of the minor elements were correlated with composition of the matte. Based on the experimental results, the vaporization behavior of the minor elements has been discussed.

Jan 1, 1999

By V. M. Paretsky

Recent developments made in the Gintsvetmet Institute in the field of autogenous smelting processes have confirmed that autogenous smelting continues to be the main prospective technology for pyrometallurgical processing of sulfide raw materials. This technology ensures energy conservation and environmental safety conforming to the current world standards for production of heavy non-ferrous metals. Two alternative processes of single-stage autogenous smelting producing white metal as well as high-basic ferrite-calcium slags have been developed and can be recommended for technical modernization of Russian copper smelters.

Jan 1, 2002

By J. A. Sanhueza

The environmental regulations and terms issued by the Chilean Government for all copper concentrate smelters have been a very important reason for permitting project developments that drastically decrease the sulfur emissions due to the pirometallurgycal copper process. A remarkable case of the Hernan Videla Lira Copper smelter, located on the Copiapó Valley and very near some housing-sets of a city of high development, are described. Results of this project's implementation of the control and reduction of off gas emissions, the control and monitoring system, the community conflicts, and the strategy to comply with the demands established by the state environmental institutions, are presented.

Jan 1, 1999

By John Jiang, Yeonuk Choi, Olivia Wang, Gus Van Weert

"As part of a general review of processing double refractory ores through Barrick Gold's autoclaves/CIL facility at Goldstrike, Nevada, blanking the gold cyanide adsorbing native carbon in the ore with hard (m.p. >55°C) paraffin wax was proposed. To avoid interference from other ore constituents in the exploratory testwork, commercial activated carbon was substituted for native carbon in the ore to establish the best conditions for de-activation of carbon with molten wax.IntroductionDouble refractory gold ores present two barriers to gold extraction. The first is generally a physical barrier: the gold is encapsulated or dispersed in a matrix which is impervious to the gold lixiviant. In most cases, including the Goldstrike deposit, this involves a pyrite or arsenopyrite matrix, although minor gold may also be dispersed in competent silica (quartz) or iron oxides. Gold can be rendered accessible by oxidative destruction of such sulphide matrices. At Goldstrike this is practised by roasting and autoclave oxidation (POX). It is the latter route to which this paper refers.The second barrier refers more correctly to gold recovery. Gold may be extracted from the autoclave oxidized solids with cyanide, forming a gold cyanide complex. One characteristic of this complex is that it adsorbs on graphitic surfaces. This behaviour is used advantageously on a large scale by gold millers, who use man made activated carbon particles to remove the gold from solution during leaching: the Carbon-In-Leach, or CIL process. The gold bearing carbon particles are larger than the ore solids and can be separately recovered by screening. Goldstrike uses the CIL technology to recover gold after autoclave oxidation."

Jan 1, 2012