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By Filippos Patsiogiannis

Laboratory size (4.5 kg) low carbon steel melts were deoxidized using Al and FeAl (33% Al), with and without synthetic fluxes, in alumina and zirconia crucibles. The dissolved oxygen, total oxygen, soluble aluminum, insoluble aluminum, silicon and carbon contents in the melt were determined as a function of refining time and temperature. It was observed that the reaction between aluminum and oxygen in solution closely follows thermodynamic equilibrium. Silica present in the alumina crucibles was found to be a source of oxygen for the melt, while this was not the case for zirconia crucibles. Reoxidation of the melt occurred through oxygen pick-up from the atmosphere. The extent of this reoxidation was found to be a function of oxygen content of the bath and the slag cover on the surface of the melt. The effectiveness of calcium-aluminate based fluxes in protecting the melt from the reoxidation and in increasing the rate of removal of inclusions was evaluated.

Jan 1, 1992

By Cang Daqiang, Li Yu, Liu Xiaoming, Zong Yanbin

"Utilization of high-quality heat in melting slag is a great challenge for iron and steel industry. In the paper, a new method is put forward to concurrently utilize heat and slag by converting the melting slag directly into high valued materials, slag glass-ceramic. A glassceramic with a higher basicity of 0.7 than traditional basicity of 0.45 was prepared from steelmaking slag in order to utilize more hot melting slag. Effects of Alz03 on its crystallization processes were researched by XRF, DTA, XRD and SEM. Results show that Alz03 in glassceramic would have great effected on its property. When the Alz03 content ranges within 12%-15%, glass-ceramics with basicity of0.7 could reach the best performances. The change of dominant phase in glass ceramics from akermanite and wollastonite to akermanite and gehlenite would significantly degrade its mechanical property. An increase of Al2O3 content leads to a rise of the viscosity and crystallization activation energy of the glass, while results in increasing sintering temperature and crystallization temperature of glass, which contributed to its fully crystallization and densification process.IntroductionSteel slag is a by-product under a process of converting iron to steel at above 1600°C, and 0.1-0.15 ton molten steel slag would be discharged for producing per ton of steel in the process. The discharged steel slag at 1600°C has heat of 68 kgce/t. In 2012, China's steel output reached 716 million tons, and produces about 100 million tons of steel slag and 68,000 tee of heat in it [1,2]. But at present, utilization of both slag and its heat at 1600°C is a great challenge for iron and steel industry.Dry granulation of melting steel slag by air and then recovering the heat of the hot air are a traditional technology which have not yet been put into practice for very low heat conductivity of the slag and low efficient of heat exchange among the different processes [3,4]. Therefore, a new method for high efficient utilization of both steel slag and its high temperature sensible heat is put forward [5,6], which is on-line reducing and extracting iron from molten steel slag and then directly preparing glass-ceramic by use of the residual molten slag."

Jan 1, 2014

By A. Schönecker, P. Y. Pichon, B. Kraaijveld, Y. Meteleva-Fischer

"Ribbon-growth-on-substrate is a casting method, which offers a possibility to control heat flow, nucleation and subsequent crystal growth at the liquid-substrate interface. This technology allows for low-cost and high throughput shaping of silicon sheets with controlled crystal grain size and orientation for use in solar cells. In this work, sheets of silicon- metal silicide composite materials were produced and their microstructure was studied. It was shown that depending on the relevant phase diagram and casting conditions, a micro/nano-sized eutectic structure of the casted sheet can be formed. Such composite materials possess properties promising for various applications in energy generation, storage and conservation. The advantages, potential and challenges of the ribbon-growth-on-substrate technique for production of composite sheet materials as well as novel areas of application for such materials are discussed.IntroductionThe Ribbon Growth on Substrates (RGS) process is well known in the solar industry as a process to produce multicrystalline silicon wafers. An industrial size pilot production line for continuous casting of silicon wafer was developed by RGS Development B.V. in the Netherlands (Figure 1). A comprehensive review of this technology and properties of the produced silicon wafers were reported by Schönecker et al [1]. The principle of the RGS process is explained in Figure 2. The relatively cold substrate extracts the crystallization heat from the liquid silicon in the casting frame. This results in the growth of a silicon ribbon (Vc) in contact with the substrate. When the substrate (Vp) is transported from the casting zone into the cooling section, the crystal growth stops, the wafer can be removed and the substrate can be re-used. Last few years large work was done on the industrialization and market development of RGS wafers for the solar industry. Part of this work was discussed by Schönecker et al [2]. Although there is still a good perspective on the middle and long term solar market for the RGS wafers, the current market situation was found to be unfavorable for new entrants."

Jan 1, 2014

By Christina Viklund-White

Life Cycle Assessment has been used to compare the environmental performance of landfilling versus recycling of the zinc used for galvanizing steel. Hypothetical process routes were com-posed involving four different EAF dust treatment processes; Waelz kiln, DC-furnace, EZINEX and slag fuming, as well as scrap dezincing. The study shows that recycling of zinc used for galvanizing steel has environmental benefits in that it saves zinc resources. However, zinc recovery does not necessarily decrease the potential impact on global warming and acidification. The magnitude of these two impact categories is tightly correlated with the amount and type of primary energy consumed in a process. Due to the high electricity consumption in the dezincing process, this route has the highest impact on Global Warming Potential as well as Acidification Potential. The major part of the energy requirement for the production of zinc from primary and secondary sources is consumed in the reduction of ZnO to Zn. The consequence is that the theoretically possible savings in primary energy by recycling zinc-containing materials are relatively minor. The impact categories "land use" and "waste generation" are not considered in this study, but most likely the evaluation of such impacts would further increase the potential environmental impact of the landfill alternative. The results also show that the location of an electricity-intensive process highly affects the potential environmental impact. Comparing process and material alternatives in LCA studies where branch average data is used, is considerably more complex than when LCA is used within a company.

Jan 1, 2000

By Mansoor Barati, Shaghayegh Esfahani

"The slag from extraction of ferrous and non-ferrous metals is a potential heat source which if treated properly can contribute to recovery of a significant amount of energy. The waste heat of slag may be used to generate steam, synthetic fuel gas, or electricity. Although several technologies have been investigated for this purpose, very little has been achieved in terms implementing the technology in industry. In this article, the development and application of various granulation techniques are reviewed and the methods to recover energy from granulated slag are discussed.IntroductionEvery year, more than 422 million tons of slag is being produced around the world as a by-product of the metal manufacturing at temperatures of up to 1300-1600°C [1, 2]. Currently slags are either disposed of or treated by processes such as granulation. Through the granulation process, most slags can be converted into a material which may be fully used as a cement feedstock. Conventional cement production is an energy intensive process with large emissions of CO2; therefore, the replacement can both be energy saving and environmentally friendly. However, for this purpose, the slag should have what is known as a “glassy” content (i.e. it should be amorphous) which requires rapid cooling rates that are not easily achieved due to the very low thermal conductivity. The main challenge in all these processes is to granulate the slag at a high cooling rate while the heat is also being recovered."

Jan 1, 2012

By F. J. Arriagada

Where gold is present in a finely disseminated form within sulfide particles, the porosity and surface area of the calcined material strongly influence leaching since they control the penetration of solution inside the gold-bearing grains. On the basis of a stability diagram for the Fe-O-S in the temperature range of 400 to 750aC, the expected sequence chemical transformations associated with the oxidation of pyrite is discus-sed. By using analytical techniques which include scanning electron microscopy, X-ray diffraction and BET gas adsorption, the chemical and structural changes experienced by auriferous pyrite-arsenopyrite concentrates and pure pyrite samples are studied under an oxidizing roasting atmosphere of com-position 80% N + 20% O2 in the temperature range of 450 to 750°C. The results indicate that as the roasting temperature increases, the surface area of the calcines decreases sharply after a maximum value attained at about 450-500°C. SEM micrographs show that the needle-shaped tips which characterize the surface of the oxide product become wider and the size of the pores between them is decreased when the roasting temperature is in-creased from 550 to 750°C. This effect suggests that the formation of a more "closed" hematite product at higher temperatures is due to sintering associated with a faster growth and crystallization of the oxide. A strong correlation is shown between increasing roasting temperature and increase in gold lost in cyanidation tailings, an effect which may be partly attributed to the loss in surface area of the calcines.

Jan 1, 1982

By J. W. Evans

Mathematical modeling has now become a standard technique in the development of new technology and the improvement of existing technology in the processing industries. Physical modeling has a longer history but a smaller following at present. The paper reviews some examples of the application of both types of modeling in non-ferrous metal extraction, particularly within the copper and aluminum industries. The objective is to show that well founded models can lead to results that have practical consequence in scaleup, design and operation.

Jan 1, 1993

By Kota Nakashima

Residues from titanium smelting tend to contain scandium. The scandiumis discarded because no suitable process exists for its recovery from the residue. Valuable-metal recovery from discharged residue is critical for environmental conservation and to achieve a sustainable society. Since 2015, JXNippon Mining&Metals has been developing a process for scandium recovery from the residue of a titaniumsmelting process. The process consists of the following steps: scandium concentrating by classification or neutralization, selective scandium leaching, impurity removal by neutralization, solvent extraction of scandium by using D2EHPA, purification, and roasting. We optimized the above steps to achieve an effective process to obtain scandium oxide (Sc2O3). In this paper, we introduce results from the bench-scale test of the scandium recovery flowsheet developed by JX Nippon Mining & Metals.

By Denis Shishin

The pyrometallurgical production and recycling of non-ferrous metals involves the use of complex feed stocks, having awide range of chemical compositions from sources that include mineral sulphide concentrates, high value obsolete materials and process wastes. The commercial viabilities of these operations hinge on the ability to extract value from these materials. Increasingly, modern computer-based tools are used to describe and predict process outcomes, including mass and heat balances, the partitioning of elements and phase equilibria. At the heart of these predictive tools are thermodynamic databases that describe the fundamental chemical properties of a system and all the components present. A comprehensive research program has been established to develop an accurate, self-consistent thermodynamic database describing all gas-slag-matte-metal-speiss-solid phases in the system Cu2O-PbO-ZnO-Al2O3- CaO-MgO-FeO-Fe2O3-SiO2-S-(As-Bi-Sb-Sn-Ag-Au). The database can be used in conjunction with the FactSage computer platform. The accuracy of the database and its application to industrial practice is demonstrated.

By Minji Jun

Leaching of the surface-coated metals from waste acrylonitrile butadiene styrene plastics (WABSP) has been investigated in the ammoniacal solution. The ammoniacal leaching of WABSP (typically containing 4.1 wt% Cu, 1.3 wt% Ni, 0.03 wt% Cr) efficiently dissolved copper and nickel, leaving unleached chromium as fine particles. The results indicate that the anions of different buffer media for metals leaching follow the order: CO3 2− > Cl− > SO4 2−. A declined leaching with high NH4OH–(NH4)2CO3 ratio (8:1) and a steep rise in extraction with high pulp in solution revealed the influence of anion (CO3 2−) and cation (Cu2+) present in the system. The leaching performed in carbonate solution by maintaining 5.0 M total NH3 concentration as NH4OH–(NH4)2CO3 ratio, 4:1; pulp density, 200 g/L; agitation speed, 400 rpm; temperature, 20 °C and time, 120 min yielded the maximum extraction (>99%) of copper and nickel. The study reveals a plausible recovery of the surface-coated metals from the WABSP without altering the properties of polymer material that can be recycled separatel

By J. S. Becker

Technology developed and first implemented in the United Kingdom enables very low grade aluminum scraps containing oils, organics, plastics and ferrous metals to be directly charged, without pretreatment, into a unique melting furnace. The system has been in full scale production for four years. The oxy-fuel-based furnace design incorporates internal afterburning in the furnace's hot zone, producing excellent thermal efficiency and very low emissions. The furnace is inherently low in NOx. This paper will provide both theoretical background and extensive operating results for this new melting concept. Applications describing both purpose built new furnaces and retrofits of existing reverberatory furnaces will be presented. Extensive operating emissions data will be presented.

Jan 1, 1997

By Richard A. Heckman

Destructive Thermal Technology (DTT) is used in the management of various waste streams. DTT includes Destructive Distillation, Pyrolysis and Classical Incineration. Recent work has more clearly defined the differences in these technologies based upon a more rigorous thermochemical approach. The U.S. Environmental Protection Agency (EPA) has chosen Classical Incineration as the Best Developed Available Technology (BDAT) for the management of hazardous organic wastes. Municipal Solid Wastes (MSW) and Sewage Sludges (SS) are also managed using Classical Incineration. Three environmental problems plague the use of Classical Incineration. Destructive Distillation, on the other hand, avoids these problems. It is an environmentally benign DTT for managing a wide variety of organic waste streams, including hazardous wastes. Thermochemical analysis of the available data on the performance of three types of DTT will be discussed.

Jan 1, 1994

By Satu Jyrkönen

A single-particle laminar-flow technique was used to study oxidation of four synthetic nickel mattes, which were screened into three size fractions, Experimental conditions were: reaction gas from N2 - 21 to 75 vol-% O2; gas preheating temperatures ranging from 500 to I 100'C. The four mattes were synthesized so that Ni/Cu ratios of I and 10 were obtained with high and low iron contents. Chemical analysis of the particles was used to determine the oxidation degree of the materials, and optical and scanning electron microscopy were used to detect their morphology, internal composition and structure. The best sulfur removal from the synthetic nickel mattes was achieved under the most oxidizing conditions with the finest size fraction. The matte with Ni/Cu = 1 and high iron content was found to be most reactive. The least reactive matte was with Ni/Cu = 10 and low iron content; the coarse fraction particles did not react at all under the conditions studied.

Jan 1, 1996

By R. J. Wesely

The paper describes the various methods which are currently being used or considered to refine gold and silver. These methods are then compared on a technical and economic basis. Conclusions are drawn on the factors which might influence the choice of process for different feed stocks and economic constraints

Jan 1, 1990

By Du Sichen, S. Seetharaman, A. Jakobsson

"In the Present paper, the principles of oxygen potential measurements have been discussed along with the design details for oxygen sensors that are used in copper industry. A description of some of commercial probes is presented along with their salient features. The application of these sensors in flash smelting, converter and casting sections of copper production are discussed along with their implications on process optimization.I. IntroductionThe high temperature galvanic cells have come into prominence on account of their numerous applications in both fundamental as well as applied measurements. Since the inception of the oxygen-ion conducting electrolytes like ZrOrCaO·by Kiukkola and Wagner [1], the oxygen concentration cells have been extensively used in laboratories as well as in industries. In metal-production technology, these cells have been used to monitor the oxygen potentials in metallic, slag as well as gas phases and also to control and styr metallurgical processes. The pioneer among the various industrial users of such cells is the copper industry. To-day, high temperature solid electrolyte cells involving oxygen ion conducting electrolytes have become an integral part of copper pyro-refining and continuous casting. In the present paper some of the applications according to the industrial processes are described including the developments that are going on in the European scene."

Jan 1, 1997

By Joël P. T. Kapusta, Romeo U. Pagador, Noparut Wachgama, Chumnoom Khuankla

"Thai Copper Industries (TCI) is a custom copper smelter and refinery in Rayong, Thailand, with an annual capacity of 165,000 tons of cathodes. It employs the El Teniente Technology as the primary smelting reactor to produce white metal from copper concentrates. The white metal is further treated in Hoboken Siphon Converters to produce blister copper then refined in anode furnaces before being cast into anodes for electro-refining in the on-site tankhouse.Thai Copper Industries is the first copper smelter to install and successfully operate on a commercial scale with the Air Liquide Shrouded Injection (ALSI™) Technology in the Hokoben converters with sonic injection of oxygen enriched air and nitrogen for cooling of the injector tip areas. Following commissioning and the establishment of operating practices, the performance of the Hoboken converters with ALSI™ Technology produced outstanding results. The unique combination of an El Teniente and Hoboken siphon converters, both of which are bath smelting operations, offers very high blowing and oxygen efficiencies. As a consequence, reverts recycling was accelerated with minimal build up on the mouth, end-plates or even below the siphon that is typical in Hoboken converters.These outstanding results in the Hoboken Siphon Converters with ALSI™ Technology helped the TCI Plant reach a production of about 75% of its capacity within four months despite the fact that the TCI staff is quite young and its converter know-how and experience are not yet fully developed."

Jan 1, 2009

By Hongbo Zhao, Jun Wang, Wenqing Qin, Guanzhou Qiu, Xueduan Liu

Bio-hydrometallurgy technology was applied for the extraction of copper from the raw ores of Chambishi Mine in Zambia. A copper extraction of 93.29% was obtained for small scale column bioleaching within 63 days, while a copper extraction of 89.05% was achieved for large scale column bioleaching in 90 days, thus confirming the amenability of the raw ores for effective extraction via bioleaching. The bacteria were cultured in a 6-stage enlarge cultivation. The bacterial cultures with cell concentration of more than 1×108 cells/mL were added into a spray pond of sulfuric acid to be applied in the dump leaching, and a copper extraction of about 50% was achieved within 2 months. The production report revealed that the copper extraction increased by approximate 20%, and the acid consumption was reduced to around 35% as a consequence of adding the bacteria. The industrial demonstration of the bio-hydrometallurgy technique is now well established in Zambia, and further applications of bio-hydrometallurgy in both Zambia and Congo are currently in progress.

Jan 1, 2015

By Qing-Yun Huang, Xiao-Yi Zeng, Bing Xie, Hong-Yi Li, Jia-Rong Yan

"In order to utilize vanadium resource in vanadium-titanium magnetite ore efficiently, vanadium distribution ratio between hot metal and slag should be improved during BF process, meanwhile the precipitating of Ti(C,N) in slag must be minimized. Effects of temperature, Ti02 content in the slag and basicity on vanadium distribution between slag and hot metal were investigated by experiment and thermodynamic calculation. The results indicated that high temperature, low Ti02 content and high binary basicity of slag were beneficial to increase the vanadium distribution ratio. The effects of temperature and Ti02 content in slag on vanadium distribution were stronger than that of slag basicity.IntroductionVanadium is an important element that is widely used in industrial fields. Most of vanadium resource is hosted in vanadium bearing titanomagnetite [l]. Vanadium bearing titanomagnetite is thus one of the domainate raw materials to produce the vanadium products. In other words, the comprehensive utilization of vanadium bearing titanomagnetite is beneficial for vanadium resource utilization. Vanadium bearing titanomagnetite sources are abundant in Pan Xi of China [4]."

Jan 1, 2013

By Mikko Loponen

Outotec has developed an operator training simulator (OTS) platformsuitable for various hydrometallurgical processes. The complete solution is run in the cloud, where virtual client instances can be managed on-demand. The aim is to build a generalizable model that produces coherent results even when operating outside of ideal parameters, allowing the operator to train in unsteady state conditions such as start-up and shutdown. Complex software products are commonly associated with significant development time and cost. Utilizing modular software architecture, only the control system and processmodel are tailored for theOTS,whereas modules such as user administration and cloud-based client machine spawning can be imported, shortening development time. A generic acidic pressure oxidation process (POX) operator training simulation consisting of feed preparation, autoclave, dual-stage flash evaporation and off-gas scrubbing is described. Process is simulated using Outotec HSC Sim 9 process simulator and controlled by Siemens Simatic PCS7 control system.

By Tina Maniatis

Applied Biosciences has developed a biological technology for removal of arsenic, nitrate, selenium, and other metals from mining and industrial waste waters.The ABMet® technology was implemented at a closed gold mine site in Canada for removing arsenic from tailings pond water. The system included six bioreactors that began treating water in the spring of 2004. Design criteria incorporated a maximum flow of 567 L/min (150 gallons per minute) and water temperatures ranging from 10°C to 15°C. Influent arsenic concentrations range from 0.5 mg/L to 1.5 mg/L. The ABMet® technology consistently removes arsenic to below detection limits (0.02 mg/L). Data from the full scale system will be presented, as well as regulatory requirements and site specific challenges. Keywords: Arsenic, Sulfate Reduction, Metal Sulfide Precipitate, Biological Water Treatment

Jan 1, 2005