Search Documents

By J. P. Ibáñez

The uptake of copper from extremely dilute aqueous solutions by alginate in the form of protonated dry alginate beads was investigated. Barium was used to cross link the alginate forming the beads. The effect of various experimental parameters such as pH and metal ions concentration on the uptake of copper were studied. The uptake was strongly dependent on the Cu-bearing solution pH up to a value of 4.5. A removal of 100% o was achieved when the initial concentration of copper was as low as 8.0 mg/L. The maximum uptake, i, e., the loading capacity, was found to be 167 mg of copper per g of beads. The mechanism governing the removal of copper was found to be ion exchange between protons of the alginate beads and cupric ions of the solution. For this ion exchange process a molar ratio, d[H+]/d[Cu2+], of 2.0 was determined. EPMA-EDX analysis of the Cu-loaded beads showed a uniform distribution of the ions throughout the structure of the alginate, regardless the solution pH. This may suggest that this sorbent material is a porous ion exchanger having high permeability and capacity. The uptake of copper and of the heavy metals cadmium and zinc by this sorbent is compared.

Jan 1, 1999

By M. E. Reed

Clyde Materials Handling (CMH) and WorleyParsons have developed a concept for a flash furnace feed system using the specialist pneumatic conveying equipment expertise of CMH and the flash furnace process experience of WorleyParsons. CMH has developed a proprietary volumetric feeder (called a Rotofeed) which is extremely accurate and overcomes many of the problems inherent with loss-in-weight screw feeders and drag chain conveyors, previously regarded as state-of-the-art. Initial indications are that the Clyde-WorleyParsons Feed System could deliver the following benefits to Flash Furnace operation: ? Accurate pulse-less delivery of feed material to the head of the burner leading to improved combustion performance and process stability; ? Highly accurate split to the individual quadrants of a conventional burner tube, or provision of a smooth hollow curtain to a burner without guide vanes; ? Decreased pressure pulsation in the furnace due to improved combustion control and performance; ? Decreased temperature fluctuations in the furnace due to improved combustion characteristics and hence reductions in refractory thermal stress and wear; Plant measurements have indicated a correlation between the discharge of concentrate from the drag chain conveyor and high speed pressure fluctuations in the flash furnace settler. Pilot scale test have been conducted to illustrate that the system delivers pulse-less feed to the burner with even feed distribution axially.

Jan 1, 2006

By Pekka Taskine

In the Kokkola zinc smelter, as in most other zinc roasting plants, there is now a trend towards using concentrates with an increasing impurity content. This also often means that the size distribution of the concentrates gets finer. Iron is present in sulfidic zinc concentrates with the highest percentage as a single impurity. The behavior of iron in zinc roasting was studied in laboratory experiments. Commercial zinc concentrates with a low and high (1.5 - 16 wt-%) iron content as pyrite or in the sphalerite lattice were oxidized to various degrees to establish the reaction mechanisms of iron in roasting. Microscopy studies were carried out on the calcine, and the findings were presented in numerous photographs of the polished cross sections. SEM/EDS techniques were used for analyzing the phases and particle morphologies present in the samples. An oxidation mechanism of zinc concentrates with a high iron content was suggested.

Jan 1, 2002

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 Tomas Astorga

APEC, the Asia Pacific Economic Cooperation is the forum of 18 economies, having a combined GDP of approximately 56% of the total world income, and over 45% of global trade. Its mining sector produces a large portion of the main minerals and metals in the world. In 1997, APEC economies produced 67% of world copper output, 55% of gold, and over 45% of other base metals. Mining in APEC captures more than 60% of the total mining investment in the world. Against this background, the Expert Group on Minerals and Energy Exploration and Development, in short GEMEED, was created in 1996, under the auspices of the APEC Energy Working Group. The sustainable development of mining activities is a main concern in APEC and GEMEED. Several programs related to the subject are actively being pursued by the Expert Group. Among them, it should be noticed the creation of an Environmental Cooperation Sub Group coordinated by Japan, whose main aim is to encourage proposals related to the environmental soundness of mining projects in the region. Also, it should be noted the existence of a Database Steering Committee whose focus is the development of an information network related to mining opportunities in the region GEMEED is a gathering of experts from all the APEC economies. As such, it represents a privileged forum to discuss policy issues related to mining. On this regard, the paper focuses on concrete actions taken by GEMEED to enhance the sustainability of the copper activity in the region.

Jan 1, 1999

By Richard Hollis

The Mount Isa copper smelter was expanded in 1998 to a capacity of over 250000 t/y anode copper. This tonnage will be produced from a single stream consisting of an Isasmelt smelting furnace, and four Peirce-Smith converters - one of which was installed as part of the expansion project. During the course of the expansion project Mount Isa Mines Limited (MIM) signed an agreement with WMC Fertilizers Ltd (WMCF) to supply sulphur containing smelter gases over the fence to a new sulphuric acid plant to be built by WMCF. This will result in a further increase in copper production by reducing the time when smelting is curtailed by Air Quality Control restrictions. As well as the need to modify the primary gas system to connect to the acid plant, the hoods and crossover ducts and their support structures on the original three converters required replacement, and secondary ventilation was also needed to improve converter aisle hygiene. Each of these areas was addressed by the project. Preliminary ideas for carrying out the modifications were found to have a serious impact on converter aisle operations, and would have led to a production loss of over 50000 tonnes of copper. Following benchmarking in other copper smelters, a suitable construction plan was developed and carried out to minimise this loss. This paper describes the methodology and construction plan adopted.

Jan 1, 1999

By Kalathur S. Narasimhan

Powder metallurgy is a net shape process competing favorably with machining, stamping, forging and castings. The growth of ferrous powder metallurgy over the past four decades reflect the advancements in materials technology, compaction technology, sintering technologies and other related fields. This presentation gives a brief background on how materials technology evolved.

Jan 1, 2006

By Dirk Verhulst

The Altair process employs digestion of ilmenite ore in concentrated hydrochloric acid, solvent extraction to concentrate Ti in a purified stream and spray hydrolysis to produce a TiO2 hydrate, followed by final calcining and milling. HCl gas is regenerated by pressure-swing distillation and reinjected in the leaching solution. All chloride streams are recycled. Chromium compounds generally remain in the residue. Solvent extraction provides flexibility for the removal of naturally occurring radioactive elements (NORMs) present in some ilmenites. The process was previously tested at a 5 t/day feed scale. Recent work at pilot scale (40 liter reactor) led to further improvements. Recovery of Ti in solution is now at least 90% with ilmenite ores, while crystallization at lower temperature lowers the amount of Fe in solution to about 5 g/l and improves solvent extraction, which is now conducted in columns. Higher Ti and lower Fe concentrations in the SX eluate improve the economics. A new formula for pigment production via spray hydrolysis produces a pigmentary base with a narrow particle size distribution.

Jan 1, 2003

By Lars O. Werme

Already the KBS Project proposed copper as a suitable material for encapsulation of spent nuclear fuel. The basis for this choice was the thermodynamic stability of copper in water and the fact that deep granitic groundwaters in Sweden are oxygen free. With a limited supply of oxidants, a copper canister would have the potential for a very long service life. The research and development work aiming at encapsulating nuclear fuel entered a new phase in 1993, when SKB launched its Encapsulation Plant Project. Within this project, SKB has: ? designed a facility for encapsulation of nuclear fuel, ? laid down the design premises for a canister for disposal of nuclear fuel, ? tested and developed fabrication methods for copper canisters, ? evaluated the long term chemical and mechanical behavior of the canister, ? made preliminary plans for a factory for the production of copper canister, ? constructed a canister laboratory for full scale testing of the key operations in an encapsulation plant. The conclusions of this project were that a canister consisting of an outer layer (50 mm) of copper over an insert of cast nodular iron would provide sufficient corrosion protection and would have sufficient mechanical strength. This canister can be produced by several methods of which forming from rolled plates, hot extrusion, and "pierce and draw" have been tested at full scale. The canister will be sealed by electron beam welding in the encapsulation plant, and the integrity of the weld will be verified by ultrasonic testing and' high-energy radiography. The final development work in this area will be performed in the canister laboratory.

Jan 1, 1999

By Alpagut Kara

Turkey is the fifth biggest ceramic tile exporter in the world. Considering the expectation that the Turkish tile sector continues to expand, further studies both on the improvement and the development of tile formulations are necessary in order to make the producers advantaged in the world market while maintaining the capital and running costs at reasonably competitive levels as well. In addition to such studies, waste management in tile manufacturing has also recently become an important issue. Accordingly, the industrial use of wastes in the traditional ceramic industry has been intensively investigated in the recent years. This work describes part of a detailed research project carried out jointly on the possible re-use of muds (raw production waste) from glazing and pressing lines of a local tile company in the development of new wall and floor tile formulations. In order to achieve this, the waste material was firstly investigated in function of chemical and mineralogical compositions. Then, the particular focus was given to the presence of the waste material in increasing amounts on the thermal behaviour and physico-mechanical properties of the re-formulated tile bodies. During the studies, SEM in combination with EDS, and thermal analysis techniques such as non-contact dilatometry were widely employed. The results indicated that it was possible to use the waste materials in the commercial tile production without deteriorating the relevant technological properties.

Jan 1, 2006

By Toshiyuki Kozuka

CdTe semi-conducting materials have been expected as solar cell materials because its theoretical energy conversion ratio is very high. The actual efficiency still low, however, many research works have been done in order to improve the efficiency. And crystal orientation is one of possibilities for that. In this work, a new method using intense magnetic field for a control of texture of CdTe crystals will be proposed, where the CdTe film was electro-deposited under an intense magnetic field. CdTe is less affected by magnetic field, because of its cubic structure, but Cd or Te has hexagonal structure, which is sensitive for magnetic field. In this paper, crystal orientation of Cd or Te film, which can be utilized as basic layer for CdTe deposition, will be developed.

Jan 1, 2006

By D. R. Spink

A partial desulfurization roasting (PDR) technique has been developed for use on zinc concentrates whereby the sulfide sulfur associated with the iron content is selectively removed over a very short residence ?time in the roaster. The resulting PDR product is then leached for the selective removal of the iron. The resulting leach restdite is an upgraded zinc sulfide concentrate which has a very low iron content. The up-graded zinc concentrate can be subjected to a conventional dead roast without formation of deleterious zinc ferrite so that hot acid leaching and jarosite (or other) iron precipitation steps are obviated. Examples are presented for the treatment of three very different types of zinc concentrates.

Jan 1, 1990

By K. Soldenhoff

The Bulong deposit, situated near Kalgoorlie in Western Australia and owned by Resolute Limited, is a lateritic deposit containing on average 1.1% nickel and 0.09% cobalt. A process has been developed and tested at the mini-plant scale for direct solvent extraction and separation of Co and Ni from solutions derived by acid pressure leaching of Bulong ore. In this paper, two solvent extraction processes are described. The first process uses Cyanex 272 to extract cobalt and reject nickel to the raffinate. The second process uses Versatic 10 to extract and purify nickel. The loaded strip nickel solution is suitable for electrowinning. Results of both batch laboratory tests and continuous mini-plant trials are presented. The selectivity of the solvents with respect to the major impurities such as Mn, Mg, Ca, and Zn is also discussed.

Jan 1, 1998

By B. C. Blakey

The economic feasibility of the sulphuric acid pressure leaching route for the extraction of nickel and cobalt values from limonitic ores is highly dependent upon the behavior of aqueous aluminium. This is primarily due to its precipitation as hydronium alunite ((H30)A13(S04)2(OH)6), which is one of the major scale-forming compounds found in autoclaves used for pressure leaching. As a result of renewed interest in the pressure leaching process, an investigation of the aqueous-solid eqilibria in the aluminium-sulphate-water system under acidic (< pH l), high temperature (230 to 270°C) conditions has been conducted. Pure hydronium alunite was synthesized in an autoclave by leaching boehmite (A100H) at elevated temperatures in sulphuric acid solutions initially 0.25 to 0.75 m H2S04 in concentration. Spontaneous, in situ precipitation of hydronium alunite followed. A high temperature solution speciation model was used for the analysis of the resulting solubility data in order to calculate equilibrium constants for the precipitation reaction.

Jan 1, 1994

By Rafael Padilla

The recovery of copper from chalcopyrite concentrates by leaching is difficult due to the slow dissolution kinetics of this mineral in most leaching media. However, recovery of copper from sulfidized chalcopyrite (a mixture of CuS and FeS2) by leaching is faster and could be selective depending on the leaching media. In this paper, the result of an investigation on the H2SO4-O2 pressure leaching of sulfidized chalcopyrite is presented. The variables considered in the study were stirring speed, concentration of sulfuric acid, temperature, and partial pressure of oxygen. The experimental data indicated that stirring speed over 500 rpm and sulfuric acid concentration over 0.1 M had very little effect on the leaching rate. An increase in temperature from 90 to 100 ºC increased both copper and iron dissolution; however, further increase to 120 ºC affected negatively the copper dissolution. Oxygen partial pressure was found to be the main variable that controls the copper/iron selectivity of the leaching. An increase in oxygen partial pressure increased significantly the rate of copper dissolution but deteriorated the copper/iron selectivity. The analysis for sulfur of the leaching solid residues indicated that most of the copper sulfide sulfur in the sulfidized concentrate oxidized to elemental sulfur.

Jan 1, 2006

By Afrodite Ntziouni, Vassilia Kasselouri – Rigopoulou, Athanasia Kyritsi, Konstantinos N. Pistiolas, Stamatia Gavela, Konstantinos Kordatos, Lazaros Iliadis

"The present study deals with the production and characterization of rice husk ash (RHA) and its use in the synthesis of zeolite of type ZSM-5. Rice husk was combusted in various temperatures with aim to find the suitable conditions for the production of amorphous silica. The resulted amorphous silica ash was then utilized as a starting material for the synthesis of ZSM-5 zeolite using the low temperature and atmospheric pressure process. The method led successfully to the synthesis of highly siliceous zeolite of type ZSM-5. The produced material was characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM).IntroductionRice husk is a major by-product of the rice-milling industries and it is usually used as a fuel for steam generation due to its high calorific power. During its combustion, rice husk ash (RHA) is produced. Knowing that the annual rice world production is over 615 million tons (2005), thus resulting in a potential production of more than 22 million tons of RHA [1], it can be understood that the RHA disposal is a crucial issue towards the environmental protection. However, due to the high silica content, RHA can be used as an alternative cheap source of silica for many uses, including as filler in polymers [2], concrete [3] and synthesis of zeolites [4-7].The burning of rice husk in air results in the formation of RHA with content in SiO2 that varies from 87 to 97% depending on the burning conditions, the rice variety, the climate and the geographic area [8]. Some small amounts of inorganic impurities are always present in the ash along with unburned carbon. The unburned carbon can be removed from the ash by further heating treatments in high temperatures, but this usually leads to the crystallization of the amorphous silica to cristobalite and/or tridymite [9]. The crystallization of the contained silica of the ash is also occurred when the burning conditions of husk are uncontrolled [10]. This crystallization is a disadvantage towards the preparation of silicon based materials, because the silica ash is rendered inactive in its crystalline form [11]."

Jan 1, 2008

By Tangstadm Merete, Eli Ringdalen

"This paper presents an overview of results from The Norwegian Research Institution SINTEF and the Norwegian University of Science and Technology, NTNU regarding new and ongoing research in silicon production. The main studies are related to condensation of SiO gas and cavity formation. If SiO gas condensation is increased at the top of the furnace resulting in SiO content in the off-gas closer to equilibrium, the Si yield will be increased significantly. Experimental work, simulating a cavity under industrial conditions, has shown that the cavity grows downwards from one layer. Physical appearance of zones in industrial furnaces, and selected reactions in these, are discussed based on results from excavation of industrial furnaces and results from laboratory experiments. Experimental studies of reaction rates for the formation of SiO are presented. Quartz properties are demonstrated to vary between differing quartz types and the effect of this is discussed.Introduction Both the theoretical and industrial issues associated with the production of silicon are described in detail in the textbook written by Schei et al [1]. This book covers the knowledge of silicon production process up to 1998. Together with the work by Myrhaug [1] and by Aasly[2], this is the main basis for this paper. Recent and ongoing research at SINTEF and NTNU focusing on production of Si and SiO in the high temperature zone, dissociation of SiO and condensate and cavity formation will be discussed."

Jan 1, 2012

By Geir Wedde, Anders Sorhuus

"Vast quantities of energy are released as heat to the environment from industrial operations. Many countries target waste heat recovery to mitigate CO2 emission. Exhaust gases from industries such as primary aluminium smelting, carry a substantial portion of the waste heat generated. For a cost efficient capture of more valuable heat (higher exergy), heat exchangers should operate on the exhaust gases upstream of the gas treatment plants. Heat exchange surface would be exposed to dust laden gases with risk of fouling. Heat exchangers of innovated design and operation have overcome the potential of excessive fouling rates. Heat exchangers of the ""shell and tube"" design have been demonstrated for exhaust gases from ferroalloy as well as primary aluminium smelters. In addition to the heat recovery, gas cooling results in smaller gas treatment plants with lower costs and reduced emission. The aluminium experience is exampled in the paper.IntroductionIndustrial usage of energy continues to grow as a result of increasing volumes of production, a trend that is likely to continue in the coming decades as living standards keep rising globally. World energy consumption (Figure la) is to grow 49 % by 2035 (ref. 2010) as reported by EIA [1]. The industrial sector consumes somewhat more than 50% of the total world energy consumption predominantly the energy increased demand comes from non-OECD countries in Asia. The industrial consumption by production of metals iron and steel accounts for 14 % and for non-ferrous metals 3 % mostly for aluminium production (Figure lb). Aluminium production will be discussed in this paper as an example of an industry with large quantities of waste heat to recover"

Jan 1, 2012

By T. I. Arbuzova

The present work presents the original data concerning using a high pressure torsion method and a shock wave loading technique to produce compact oxide nanomaterials and investigations of the effect of severe plastic deformation on a microstructure, crystal lattice and stability of these compounds. This allowed us to compare two ways of deformation action that can be characterized as quasi-static and dynamic effect, correspondingly. Particular attention was paid to a stoichiometry and surface composition changes upon severe plastic deformations. A procedure for studying chemistry of the oxide nanomaterials by means of nuclear microanalysis and Rutherford back scattering has been worked through. For surface studies the X-ray photoelectron spectroscopy has been used. It was shown that both distortion methods permit to produce massive nano-scale oxide materials from the coarse-grained powder during a single technological cycle. Bulk nanocrystalline materials based on LaMnO3, TiOy and ZrO2:Y2O3 were obtained by the quasi-static deformation technique. Nanoscaled ceramics of CuO, Mn3O4 and LaMnO3 were produced by the dynamic deformations. The density of the nanoceramics comes to 99%. Size effects and specific imperfection of the nanoceramics obtained lead to a set of particularities of physical properties.

Jan 1, 2006

Plastics recycling has become an established national industry in Korea. However, it is still in its infant stage and experiences growing pains. In Korea, mixed plastic wastes generated from households after hand picking and/or mechanical sorting processes amount to 1,700,000 ton per year in 2005, and most of these waste are finally end up with landfill and/or incineration due to lacks of separation technologies and economical reasons. These plastic wastes can not be used as raw materials for chemical and/or thermal recycling because of their high content of PVC (upto 4.0 wt.%). In the present work, gravity separation system has been developed to remove PVC from the mixed plastic waste and recover the individual plastics. The separation system mainly consists of air classification, crushing, feeding system at fixed rate and wet-type gravity separation system. The gravity system based on centrifugal separation also consists of mixing, precleaning, separation, dewatering, recovery system, wastewater treatment system, etc. The main objective of this process to be developed is to achieve high separation efficiency of polyolefins (PE, PP, PS) with less than 0.3 wt.% PVC content and less than 10% moisture content in the final products. The system with a capacity of 0.5 ton per hour is developed and operational results are presented.

Jan 1, 2006