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By Shilai Yuan, Huimin Lu, Zhijiang Gao, Panpan Wang

"Solvent refining of silicon through using Si-Al melts is a valid method to remove the impurities from metallurgical grade silicon (MG-Si) melt. The thermodynamic behavior of impurities Fe, Al, Ca, Ti, Cu, C, B and P in MG-Si during the solidification of MG-Si was studied based on the available thermodynamic parameters and experimental data. The morphology of inclusions was investigated by Scanning Electron Microscope (SEM). The chemical composition of inclusions in MG-Si and Al-Si melt was analyzed by EPMA. It is found that the amount of white inclusion reduces and most impurities are solved into the Al-Si melts. After solidification of Si–Al alloy using induction heating and acid leaching, impurities can be effectively removed. The solidification of silicon from the Si–Al melt is found to be more effective for purification than general silicon solidification.IntroductionPhotovoltaic energy is one of promising energy resources in a sustainable society because of its inexhaustibility and cleanliness. Although the production and installation of solar cells have increased significantly during the last decade, the cost of solar cell installation is still high. Multicrystalline silicon has now become the main material in the photovoltaic market because of its low production cost and because of the relative high conversion efficiency of solar cells made from this material, which has been studied for a long time [1-3].Electronic grade (EG) silicon (99.9999999% Si) is commonly used as the raw material to produce SOG-Si (99.9999% Si). Silicon produced from the chemical routes restricts the development of solar cells due to environment threaten, high energy consumption and low productivity. Purification of metallurgical grade silicon (MG-Si) is a low cost, environment friendly method. Although several metallurgical processes such as directional solidification, vacuum refining and electron beam melting [4], have been developed, the cost reduction and refining efficiencies for manufacturing silicon is still have to be further optimized.In the purification process, it is difficult to remove boron and phosphorus by the conventional metal refining method. The refining efficiency depends on the segregation behavior of different elements in solid silicon and the liquid phase. The segregation ratios of all investigated impurities were found to be much smaller than the segregation coefficients between solid and liquid Al-Si melts [5]. For instance, the segregation coefficient of B in Si is 0.8 at the silicon melting point (1687K), whereas it is around 0.2 when silicon is solidified from Si-Al melt at 1273K. For phosphorus the segregation coefficient is 0.06 when silicon is solidified from Si-Al melt at 973K°C, which is much less than 0.35 for recrystallization from liquid silicon. Since the segregation coefficient of boron in silicon is 0.8, it cannot be removed by directional solidification."

Jan 1, 2014

By Neale R. Neelameggham

"Ferrous and non-ferrous metal industries are used to handling several billion tons a year of ore bodies, fuel and fluxing agents by mineral processing techniques and varieties of extractive metallurgy ""Reduction"" processes. Metal industry know-how can be applied to meet the challenge of Reducing CO2 in the atmosphere. Processes for generating alloys of carbon and hydrogen by Reducing the CO2 and water mixture, [carbonated water or water vapor] called Soda, to easily stored fuels are normally endothermic. The processes are similar to generation of hydrogen alone from water which is also endothermic. But hydrogen is more difficult to store than compounds [or alloys] of carbon and hydrogen. This recycling of CO2 and water are possible by using other forms of energy by innovative carbon capture methods.Thermodynamic Diagrams developed for Soda [CO2 and H2O] - metal reactions provide hints for using low cost unused stored energy in un-recycled metallic waste for thermal conversion. Choices for conditions for the electrochemical approaches [using solar - wind - hydropower] are also discussed.INTRODUCTIONIn 2006, I was reading some of the arguments put forth by learned scientists on the benefits and lack of benefits of bio-fuels. I found that the arguments rose partly from the differing system boundaries that were chosen by one versus the other. Some part of the argument may have been based on political climate or atmosphere rather than the analytical science. This situation is seen when scientists discuss which came first - the chicken or the egg, the fuel or biological matter, the oxide or the element, and so on.Then I thought –[just like many of the learned persons participating in this symposium] that common fuels - regardless of them being simple hydrocarbons or oxygenated hydrocarbons or carbohydrates - can all be made from the respective oxides of carbon and hydrogen by simple chemical reductions efficiently carried out in an economical fashion. This is the systematic approach we take when designing a chemical or metallurgical process facility."

Jan 1, 2008

By M. Demuth, B. Holleis, M. Potesser, D. Spoljaric

"In 2005, Messer Group established a technology competence centre for metallurgy in Gumpoldskirchen (Austria), with the aim to develop oxygen burners which satisfy today's and upcoming standards of legislation as well as customer requirements. With the assistance of the Development Sponsorship Fund (FFF) of Austria, cooperation with the University of Leoben was agreed on. With the long term experience of the Gas-Warme-Institut ""GWI"" in Essen (Germany) and the University of Leoben, different new burners have been developed.The efficiency of industrial combustion processes can be increased in two ways (which can be seen in Figure 1 ), either by preheating the fuel and combustion air or by adding oxygen. Due to the high 79 % Nz ballast in air combustion, only low flame temperatures can be reached. This results in high heat loss in the exhaust gas, caused by the low combustion efficiency. Oxygen can be introduced into the combustion chamber using different techniques:• Oxygen fuel burners• Direct oxygen injection into the fuel air flame• Underlaying of the fuel air flame• Enrichment of the combustion airIn Figure 2, the theoretical flame temperature for the stoichiometrical combustion of natural gas is plotted as a function of oxygen enrichment. Therefore, it can be concluded that even low enrichment values produce higher flame temperatures and result in higher combustion efficiency."

Jan 1, 2012

By Adam J. Gesing

Eddy current separators are increasingly used by the auto shredder operators to produce higher grade of nonferrous metal concentrate for recycling. While this increases the unit price of the concentrate, metal losses through inefficient metal recovery quickly offset the price differential. We show how to optimize the eddy current separation system at the shredder to maximize mate- rial throughput, nonferrous metal recovery and grade of the nonferrous metal concentrate.

Jan 1, 1998

By James R. Craig

The slags generated during gasification of petroleum coke are heterogeneous and con-sist of many different phases. These phases are important because their physical properties affect the operability of gasifiers and because they concentrate many elements that are present in the petroleum coke feed in only minor to trace quantities. An understanding of the chemistry and physical nature of these slag phases is necessary to predict behavior in the gasifier and in considering the ultimate use or disposal of the materials. Slags typically consist of silicate glasses, calcium-silicates, free iron-nickel metallic phases, iron sulfides, and aluminum oxide spinels enriched in iron, chromium, and vanadium. The partitioning of elements among these phases has been analyzed and will be discussed.

Jan 1, 1989

By R. W. Adams

A new process has been developed for leaching zinc sulphide concentrates at atmospheric pressure using air or oxygen plus nitrogen dioxide in dissolved or gaseous form as? an oxygen carrier. The process is flexible and can cope with variations in the degrees of retention and regeneration of dissolved nitrogen dioxide in the leaching phase. By controlled addition of concentrate a leach solution with low residual nitrate concentration can be produced. Following separation by filtration of unleached solids and elementa1 sulphur and conventional oxidation/precipitation of dissolved iron, the leach liquor can be treated with metallic zinc to remove the remaining nitrate and other meta111c impurities such as copper, cadmium and cobalt to provide a solution suitable for electrolytic recovery of zinc. Pilot scale testing of the process .has given zinc recoveries in the high nlnet1es, production of a hi.gh grade jarosite-free Pb/Ag residue (50% Pb.) and a saleable high grade of elemental sulphur. .A wide range of concentrates can be treated containing substantial levels of lead and copper as well as zinc. Indicative cost estimates suggest that the new process is competitive with alternative procedures such as pressure leaching.

Jan 1, 1990

By M Kolbe

Co-Cu exhibits a metastable miscibility gap in the region of the undercooled melt. Specimens have been undercooled and solidified containerlessly into the metastable miscibility gap in an electromagnetic levitation facility (EML) and in drop tube (DT) experiments. Due to the high undercooling the velocity of the solidification front is very high and the microstructure is frozen in instantaneously. The microstructure of samples processed in the EML is influenced by the electromagnetic stirring due to the induction of electrical currents into the melt. A variety of microstructures has been observed. After undercooling below the binodal the liquid melt separates into the Co-rich L1-phase and the Cu-rich L2-phase. Two basic morphologies of the L1-phase can be observed, they can be attributed to the transition in dendrite growth from diffusionally and thermally controlled to only thermally controlled growth. Transient microstructures are observed after solidification in the vicinity of the binodal. Drop tube experiments, which lead to a rapid solidification of a distribution of droplets under reduced gravity conditions, in contrary allow for the observation of the early stages of demixing: the microstructure shows a homogeneous distribution of spherical particles of the minority phase in the droplets. The cooling rate of the droplets and its dependence on the droplet radius has been calculated. The solidification velocity as a function of undercooling has been measured in the EML for the composition Co-lB.Bat%Cu. The data are analysed in the framework of the LKTlBCT model with a velocity-dependent distribution coefficient as well as within a model of Galenko and Danilov using a kinetic growth coefficient of u=0.22 m/Ks.

Jan 1, 2002

By Jan A. Aune

The paper describes a number of electric furnace equipment modules especially developed or modified for slag furnace applications. Both the resulting design concept for a modern electric sulfide smelter and some of the changes in traditional process-concepts made possible are outlined.

Jan 1, 1983

By Pavol Loderer

Mineral froth pumping utilising centrifugal slurry pumps is a major engineering challenge for the end users and pump manufacturers due to the undesirable outcome of unstable pump performance. Most of these challenges occur due to incorrect pump selection and suction tank design. The traditional approach is to oversize the pump for pumping mineral froth. New horizontal slurry froth pump designs offer opportunities to improve the mineral froth with challenging (high) Froth Volume Factor while maintaining high efficiency, long wear life and stable pumping performance. This paper examines the flotation process in detail and how froth pumps are designed to handle this arduous process.

Two pilot-plant investigations were conducted in which strong-base resins were compared with activated carbon for the extraction of gold cyanide from leached pulp from the Golden Jubilee Mine. The results show that gold can be recovered with carbon, but that the extraction efficiency is poor, probably because high concentrations of humic and fulvic acids are. present m the pulp. .However the extraction of gold cyamde from this material with strong-base resins JS very effo:1ent, and the overall efficiency of extraction is better with resin than with carbon, even when the concentration of resin is one-third that of carbon, and the flowrate of resin is one-third that of carbon. The results of the pilot-plant campaign reported in this paper led to the conversion of the Golden Jubilee plant from carbon-in-pulp to resin-in-pulp in February 1988.

Jan 1, 1989

By Forsén. O.

In this ?paper practical solidification of anodes containing nickel, arsenic, antimony and bismuth is compared with the equilibrium? diagrams and kinetic ?factors. In order to clarify the distribution of the impurity elements in the anode the structures were studied after the solidification and also after the electrolysis of anodes. This examination was carried out with optical microscope, scanning electron microscope and electrochemical measurements. All the nickel is remaining metallic in the copper matrix during the solidification and therefore nickel is dissolved in the electrolysis at all oxygen contents, when the nickel content is 0.25 wt-% or less in the anode. The practical .solidification mechanism of the anodes, when the nickel content exceeds 0.25 wt-%, proceeds by the crystallization of nickel oxides. In oxygen containing copper anodes nickel oxide is verified to crystallize together with antimony in certain conditions and to form a micaceous compound (3Cu2O?4NiO?Sb2O5), which may build up a very harmful floating slime in the electrolyte. Arsenic is strongly enriched along the phase boundaries in oxygen free copper anodes. An intermetallic compound Cu3As is formed when the amount of arsenic in the anode. exceeds 0.7 wt-%. This compound is more noble than the copper matrix. This means 'that a selective dissolution of copper-arsenic compounds takes place. The copper matrix dissolves more strongly than the grain boundaries. The solidification structures of oxygen free bismuth containing copper anodes show clearly the influence of bismuth. Thin bismuth films which are less .noble than the metallic copper matrix, are formed during the solid1ficatton process. As a result of this the?grain boundaries are dissolved faster than the copper matrix.

Jan 1, 1987

By S. L. Kher

The Singhbhum Copper Belt located in the state of Bihar in Eastern India bears evidence of ancient workings and indicates the existence of a civilized habitation in this region in the past. It was in 1833. how- ever, that the first official announcement of the occurrence of copper in the district was made. Although the occurrence was confirmed in 1847, it was not until 1857 that the first company was formed to exploit the deposits. This Company was dissolved in 1859 and from then until 1920, there were many unsuccessful attempts to develop and exploit the copper deposits in the Singhbhum area. In 1920. the Cordoba Copper Co. took an option on the Mosaboni area, which is nearly 10 km away from the present works located at Moubhandar, Ghatsila and exercising the option in 1924, purchased the mining rights from the Cape Copper Company. The Cordoba Copper Co. was then converted into Indian Copper Corporation Ltd. This was subsequently taken over by the Government of India in March 1972 and is now known as Indian Copper Complex (ICC), forming one of the two smelting units of Hindustan Copper Ltd.

Jan 1, 1976

By L. J. Lutz

The U.S. Bureau of Mines has developed an electrorefining process to recover Ni, Co, Cr, and other metals from mixed and contaminated superalloy scrap. The superalloy scrap is cleaned then directly electrodeposited as a Ni -Co deposit. The process recovers approximately 90 pct of the Ni-Co available from the scrap as a 99t pct pure Ni-Co alloy. During electrorefining the electrolyte undergoes a purification process which results in Cr and other refractory metals reporting to the purification residue. Operating data is given for a 3-L compartmented electrolytic cell. Techniques for the removal of Fe, Cr, and trace impurities from the recycled electrolyte are outlined. The economics of a facility producing 15 mt/d of a Ni-Co alloy are also discussed.

Jan 1, 1993

By Lionel Ryan

In 1996, the Dominican Republic operation of Falconbridge (Falcondo) developed a 5-year Process Control Plan in conjunction with the corporate Process Control group located in Sudbury, Ontario, Canada. This plan was further refined into an analysis of the areas of the highest potential economic return for the company with the reduction shaft furnace operation being the most promising. Historically, the reduction plant, which comprises 12 shaft furnaces, has been the bottleneck of ferronickel production. Since 1996 there has been a history of control development, and the current status is that all 12 furnaces are using advanced model-based multi- variable predictive control. The combination of advanced process control (APC), improved control system performance and improved process information management has resulted in an increased throughput of 6% per shaft furnace and a reduction in operating costs of 4.5 US cent/lb of Ni. This paper reviews some of the major milestones that have been achieved in this development Keywords: Advanced Process Control; Model Based Predictive Control; Connoisseur, Reduction Shatt Furnace; Nickel Laterite Ore; Ferronickel; MonitorMV

Jan 1, 2004

By Takahiro Furuzono

Saganoseki Smelter and Refinery of Pan Pacific Copper Co., Ltd. started treating copper anode slimes using a unique hydrometallurgical process in chloride media in 1997. The process comprises the following stages, decopperizing, wet chlorination, solvent extraction for gold, silver chloride reduction, and separate reduction stages that treat the gold extraction raffinate with sulfur dioxide gas. Precious metals and rare metals in the copper anode slimes are dissolved in an aqueous solution of hydrochloric acid by oxidative leaching, which is termed wet chlorination. Gold is efficiently extracted from the chlorination liquor by dibutyl carbitol in the solvent extraction stage. Gold is reduced by oxalic acid from goldloaded dibutyl carbitol and recovered as gold powder. The gold powder is cast directly into granules or ingots of more than 99.99% purity without electrorefining. Selenium is recovered as a selenium residue by reduction with sulfur dioxide gas and refined through vacuum distillation. The plant was designed to process 132 tonnes of copper anode slimes per month and has a current capacity of 206 tonnes per month due to several enhancements. Compared with the conventional process, the hydrometallurgical process described here provides some advantages, in particular, a higher product quality, shorter gold-retention time, and reduction in environmental load.

By P. R. Bruggink

"A quantitative tool has been developed to assess the impact of changes in recycling rates on the environmental impact of aluminum supply. It has been applied to the USA to forecast sources of aluminum scrap and to examine the impact of an increase in Old Scrap recovery on the USA supply system and the subsequent effect on the Life Cycle Impact of aluminum supply. The reported data for primary, secondary and import/export supply and product shipments for aluminum in the USA show a fairly good balance between supply and demand on average over the years. Therefore, it is reasonable to use the data, along with published estimates of average product lives, recycling rates and recoveries to draw conclusions about future aluminum scrap generation· and recovery. The Life Cycle Impacts of increasing post-consumer recovery rates to recover an additional 450,000 MT/yr (1 billion lb/yr) has been estimated using the model.The spreadsheet model upon which this work was based was developed in U.S. Customary units. Converting the figures to Metric units would have required converting the entire model and rebuilding the figures. I have chosen to leave the figures in U.S. Customary units. I apologize for any inconvenience this may cause."

Jan 1, 2000

By Larry Twidwell, Ed Rosenberg, Courtney Young, Sean Dudley, William Gleason, Maureen Chorney

Experimental and industrially produced polystyrene and silica resins are tested for recovery capabilities of Rare Earth Elements (REE). Testing regimes being used are typical of resin analysis. Inductively Coupled Plasma-AES results indicate that preferential separation and recovery is possible in the adjusted pH range of2 to 10, solution conditions, and resin type. Testing conditions are resulting in structure modification of the composite resin as indicated by X-Ray Diffraction, Differential Scanning Calorimetry, Scanning Electron Microscopy, Mercury Porisometry, and density analysis. Resin modification indicates both surface and internal structure alteration outside of reported standard behavior of resins. Structural changes have ramification for both Rare Earth Recovery RER and traditional resin operations. Analysis shows that the resin uptake of REE can be manipulated for concentration. Further analysis with SEM work indicates that widespread surface and interior modification is taking place as resins load with REE. This modification is leading to pore rupture and particle breakage. Further investigation is being performed to determine the mode of breakage.

Jan 1, 2015

By Paulo von Krüger

This paper deals with the cell design and operation of a tin electrorefining 1:5 pilot plant. The purpose of the work was the fitting of the basic parameters to be used in a full-scale tankhouse from a major Brazilian tin producer. The main specific difference was the use of permanent stainless steel cathodes instead of conventional tin starting sheets. The results of both product quality and operating parameters are discussed.

Jan 1, 2003

By C. Beckennann, C. Y. Wang

"Computer simulations of structural and compositional development in equiaxed dendritic alloy solidification are performed using a recently developed multi phase model. The model not only accounts for the transport phenomena occurring on the macroscopic (system) scale, but includes also the grain nucleation and growth mechanisms taking place at various microscopic length scales. In this paper, a numerical technique consisting of a fully implicit control-volume based finite difference method and a multiple time step scheme is developed for accurate and efficient simulations of both micro- and macro-phenomena. Sample numerical results are presented to reveal the effects of liquid now and crystal sedimentation on segregation and the final grain size distribution. In particular, the importance of the interplay between the dendrite microstructure and multiphase now patterns is shown.IntroductionIn recent years, modeling of equiaxed dendritic solidification without convection has experienced considerable progress (1,2]. Nucleation and growth kinetic laws have been coupled with transient heat conduction calculations to determine the solidification microstructure. However, modeling of equiaxed dendritic solidification with melt convection and solid movement has not been attempted so far, largely because of the complications associated with the transport of free equiaxed crystals in the melt. The gravity-induced transport of free crystals is fundamental to the development and extent of the equiaxed zone and also greatly affects the columnar to equiaxed transition. Another possible effect of crystal sedimentation or floatation is to cause severe macrosegregation as well as structural inhomogeneities. The only study available in the literature that accounts for both liquid convection and solid transport is by Ni and Beckermann (3], but deals with globulitic structures (as opposed to dendritic)"

Jan 1, 1994

By Mingchun Lu, Yunjin Yan

"This paper describes a new type of bell-less top installed on two relined blast furnaces at Tianjin Iron Works and another new-built at Echeng Steel Works in China. A compact installation was presented for existing furnace top innovation with the least reformation of existing top structure. A water cooling and sealing gearbox used for driving the chute discards completely the traditional idea about necessity of continuous supply of cooling gas for the gearbox. A multiring spreader and its dozens of selectable charging patterns enables an operator to achieve optimal burden distribution easily under the condition of a minimum investment of control equipment. Some useful conclusions have been made through a small-size model and a full-scale model tests. The excellent characteristics and the superiority of the new top have been fully proved at both works.IntroductionIt is known that there are some advantages with the bell-less top of a blast furnace: suitable for furnace to operate at high top pressure, capable of realizing optimal burden distribution, less investment and maintenance costs, etc. But why do most of blast furnaces in the world still remain using conventional bell top. One of the concerns is that current bell-less tops still have some shortcomings:1) The height of a current bell-less top might be lower than three or four-bell top or two-bell plus valve seal top, but still much higher than an ordinary two-bell top.2) The gearbox for driving the rotating chute is positioned onto the lip of the furnace. It is subject to attack by crude hot bf gas. Continuously pumping cooling gas (pressurized nitrogen or clean bf gas) into the gearbox is indispensable to withstand such a harsh working environment. Therefore, a plant furnished with blower8 and its ancillaries has to be built, It involves a large sum of investment and much expense in its annual running costs.3) Although the current bell-less charging device as a means of controlling burden distribution possesses a wide range of freedom, it is difficult to realize optimal burden distribution. There are some large blast furnaces realized better burden distribution, but sophisticated control means is indispensable so that the investment of control means is much higher."

Jan 1, 2000