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By Huayi Yin, Wang. Dihua, Wei Xiao, Xuhui Mao, Diyong Tang

"The world production of crude steel reached 1.55 billion tons in 2012,which generated ~2.5 billion tons of CO2. Electrochemical metallurgy especially through high temperature molten salt electrolysis with renewable electricity stands for a great opportunity for producing “green” metals. In recent years, electrolytic production of iron without emission of CO2 in different molten salt systems has been reported. A cost-affordable inert anode is the key to produce acceptable eco-friendly iron by the novel molten salt electrolysis processes. Based on the authors’ research, this paper will discuss iron production by molten salt electrolysis using a nickel alloy inert anode. On the other hand, the paper also covers a novel molten salt CO2 capture and electrochemical transformation (MSCC-ET) process, in which CO2 is effectively converted to value-added carbon and oxygen in a molten bath using a cost-affordable nonconsumable SnO2 anode.1. IntroductionEnergy and materials are cornerstones to support the development of human society. The traditional primary metal production, especially iron and steel, and electricity production are mainly based on the reactions between carbon (coal) and oxygen (represented by equations (1) and (2) respectively), which produce huge amount of CO2.MxOy + 0.5y C = x M + 0.5y CO2 (g) + Q1 ( 1 )C + O2 (g) = CO2 (g) + Q2 ( 2 )In 2012, the world production of crude steel reached 1.55 billion tons, of which 46.3 %, ~0.7165 billion tons were produced in China. Based on the average level of 1.7t CO2 emission per ton steel, more than 1 billion tons of CO2 generated from steel industry in China in the year. Besides the iron and steel industry, thermal power plant leads the CO2 emission in both USA and China. The total consumed electricity in China increased to 4959 billion kWh in 2012, ~70% of it was from coal fired power plant. The average CO2 emission for electricity production in the typical thermal power plant in China is around 0.78 kg kWh-1. It accounts for ~ 3.868 billion tons of CO2 emission from thermal power plant in 2012 in China."

Jan 1, 2014

By Bin Du

In recent years, concurrent product design and process is gaining popularity and will become a norm of the industry of the future. Forging has been a critical manufacturing process for production of components with superior tensile strength, toughness and grain flow. This paper describes an expen system which is being developed for forging die design and forging process analysis in concurrent engineering environment. Rules and guidelines pertaining to forgeability are formulated and incorporated into the knowledge-base in building the system. The system is built using an object-oriented paradigm. The object-oriented approach and hierarchical rule structure paradigm are briefly discussed. Finite element analysis packages (ALPID-2D) were incorporated into the program to give the simulation result of the forging process. The system can automatically produce a competent design and recommend a set of processing parameters for a given product. The designer can modify the design according to the result of the simulation.

Jan 1, 1992

By Hector Henao

To provide thermodynamic data for converting the nickel matte to liquid nickel, an experimental study was conducted in the phase equilibrium between the Ni-S alloy and the CaO-Al2O3 based slag melted in a MgO crucible at 1873 K under controlled Pso2 of 10.1 kPa and Po2 in a range between 2.5x 10-and 10.1 Pa by using CO-CO2-SO2 gas mixtures. The content of nickel in the slag at Po, of 10.1 Pa, above which solid NiO is expected to precipitate in the equilibrium state, was found to be 4, I mass% and the contents of sulfur and oxygen in the nickel melt were 0.4 and 02 mass%, respectively. ft was clarified that increase in the temperature reduces the solubility of nickel in the slag and the contents of sulfur and oxygen in the alloy, The distribution of minor elements such as gold, silver, copper, cobalt, iron, arsenic and antimony between the Ni-S alloy and the CaO-Al2O3 based slag was also studied. The distribution ratios of iron and cobalt, defined by (%X in slag)/[%X in alloy] where X is the minor element, are larger values than that of nickel, while those of copper, silver and antimony are similar to that of nickel. The distribution ratios of arsenic and gold are lower than that of nickel in the higher range of oxygen partial pressure.

Jan 1, 2003

By Yong J. Kim, J. M. Park

"Solid/melt interface shape during continuous casting process has a strong influence on the resulting microstructure of the ingot. The interface shape is primarily governed by the heat flow condition between the molten metal and mold (or container). The roll of the microstructural transition resulting from various solid/melt interface shapes is discussed using the Sn-22.6wt%Pb alloy. Three different types of mold such as cold mold, resistantly heated mold, and electromagnetically heated mold were used to generate those interfaces having different curvatures. Experimental measurements of complete temperature profile along the axis and surface of the ingot during downward continuous casting are presented to determine the solid/melt interface geometry. The results provide an explanation of the ingot property with emphasis on microstructure.IntroductionA large scale of continuous casting process of alloys often has a rather deep V channel type of solid/melt interface resulting from a limited heat flow condition. As a result, the deep V type solid/melt interface shape entraps defects such as pores and inclusions and also creates canter segregation. In order to reduce the defects concentration, electromagnetic stirring(EMS) mechanism has been applied to the melt in the channel[l]. Speith and Bungeroth introduced first experimental EMS device to the continuous caster in 1952.[2] Today, with wide ranges of benefit, a large variety of such technique is available. Electromagnetic field on the melt can be divided into three aspects. First, eddy current is induced on the metal surface by alternating magnetic field with high frequency, which results in heating the metal. Second, electromagnetic body force which is generated by the magnetic field and the eddy current reduces the melt pressure on mold or support the melt not to contact with the mold[3,4,5]. This force is used for electromagnetic casting process(EMC). Finally, it causes stirring in the melt. Many research efforts have been done on the EMC process to improve surface quality of slab[6] and control meniscus shape where three phases such as melt, solidified metal, and mold powder coexist[7,8]. However, the eddy current heating effect on the surface of the ingot was less considered. It is worth noting that induced eddy current on the surface of slab melts the solidified shell and thus changes the heat flow condition between the mold and melt. Mold heating effect was first proposed by A. Ohno[9] and its processing conditions were identified in details[ 10, 11]. The so-called Ohno process is based on the fact that by keeping the mold temperature slightly above the melting temperature of the liquid, no grain can be nucleated on the mold wall[12]."

Jan 1, 1998

By Rolando Campos

The CODELCO-CHILE Teniente Converter Technology, is presently being applied in four Chilean smelters (Caletones, Chuquicamata, Potrerillos and ENAMI-Ventanas). A Teniente Converter is due to be used at ENAMI-Hernan Videla Lira (Paipote) smelter in the near future. Also, a Teniente Converter is to be installed as part of a retrofit project for Nkana smelter of Zambia Consolidated Copper Mines Ltd. (ZCCM). The charge to be treated through this smelter will consist of a blend of concentrate arisings from the various concentrators within the ZCCM group. The present status on the application of the Teniente Converter Technology at Caletones smelter as well as its projected performance when used at Nkana smelter, are presented in this paper. The design operational basis, autogenous smelting throughputs, concentrate to matte ratios and benefits due to the use of technical oxygen, are presented and analysed.

Jan 1, 1992

By Xiaojie Gao, Jingshe Li, Chengsong Liu, Haiyan Tang

In order to clarify the reaction between MnO-SiO2 oxides with low FeO content and Fe-Mn-Si alloy, two diffusion couples were produced by the new method using confocal scanning laser microscopy (CSLM). The interface of the alloy and oxide, content of Mn and Si in the alloy near the interface, size distribution and composition of the particles which precipitated in the alloy were observed and analyzed using the electron probe microanalysis (EPMA). Results show that though the FeO content in the oxides decrease to 1% which is lower than the equilibrium with the molten steel at 1873K, the diffusion of oxygen from oxide to alloy still exists during the heat treatment at 1473K and causes shorter Particle Precipitated Zone (PPZ) and Manganese Depleted Zone (MDZ) normally for the reduction of diffusion flux of oxygen.

Jan 1, 2015

By Matthew C. Binsfield

The simultaneous electro winning of zinc and manganese from waste water treatment plant sludge was studied as a part of the overall research program, which was conducted to develop the methods for removal of environmentally hazardous metals from the Bunker Hill Superfund Site. This paper discusses the electrolytic method for recovery of zinc and manganese from the solution produced by leaching of sludge with S02 + H2S04. After three stage purification of the leaching solution, zinc and manganese were electro won simultaneously in an undivided electrolytic cell. Zinc was deposited on an aluminum cathode, while manganese was simultaneously produced (as Mn02) on a lead silver anode. The electrowinning parameters studied were the effects of: temperature, current density, electrode material, spacing of electrodes, composition of electrolyte, and electrolyte additives. Anodic and cathodic efficiencies were 30 and 91%, respectively. In light of the process design parameters discussed in the paper, which are affecting the electrowinning, these efficiencies were found as acceptable with regard to the quality and marketability of the products.

Jan 1, 1996

By G. Gao

Flyash from municipal solid waste (MSW) incinerators is frequently classified as a characteristic hazardous waste due to its lead and cadmium content. Extensive investigation has therefore been carried out to detoxity the flyash by leaching and to recover lead, cadmium and zinc. Detoxification can be accomplished by leaching in HCI/NaCI solutions. Optimization of leaching conditions for effective detoxification and subsequent metal recovery can be achieved by controlling the acidity of the lixiviant and flyash to lixivaint ratio. Lead and cadmium In the leaching solution is recovered by cementation with zinc dust. Leaching and cementation experiments have shown that zinc concentrations suitable for electrowinning, > 15 g/liter, can be achieved. Experiments have also been performed to determine the effects of pH, particle size of the zinc dust used, quantity of zinc added and dissolved impurities on the cementation kinetics. After recovery of lead and cadmium, electrowinning or electrowinning coupled with solvent extraction can be used to recover zinc. A process flowsheet is presented.

Jan 1, 1991

By Shaohua Ju, Jin-hui Peng, Ya-jian Wang, Shuai-dan Lu, Li-bo Zhang, Lei Guo

"The granulation of a red mud is of great importance for recycling this material as an adsorbent for waste water or gas. A new granulating process was developed and its effect was evaluated. To reduce the cost of the granulation process, the wet filter cake (containing 25% water) was directly mixed with different cement contents (4%, 6%, 8% and 10% based on wet material). The mixtures were placed in a moist environment for 4 days, and then were washed with deionized water until the pH values of leachants were lower than 9.0. The efflorescence ratio, surface area and particle size of the aged mixture were determined, respectively, by bottle shaking experiments, N2 adsorption and screening. The results showed that the best addition of cement is 2%, and this yielded granulated material with a particle size of less than 2 mm, an efflorescence ratio of 4.83% and a specific surface area of 17.42 m2/g.IntroductionRed mud is a residue of the aluminium industry that is produced during the alkaline extraction of alumina from bauxite by the Bayer process. For every ton of alumina that is produced, the amount of red mud generated can vary from 0.3 to 2.5 tons, depending on the characteristics of the bauxite. In its typical form, red mud is brick red in colour, caustic, about three times as dense as water and, when un-neutralised, has a high pH, typically around pH 13 [1]. It is primarily composed of iron oxide, silica and alumina, along with traces of heavy metals. Red mud particles are quite small; typically 99% will pass through a 0.6 mm sieve and 87% through a 0.038 mm sieve [2],"

Jan 1, 2012

By L. J. Cabri

The level of mineral exploration activity for platinum in recent years, especially in North America, has ranged widely. Exploration programs have been based on a variety of ore deposit models and deposit types. These range from the classic magmatic model for sulfide/oxide deposits and their associated placers, through hydrothennal models for bonanza-type deposits, to low-grade mineralization potentially amenable to lower cost bulk mining methods. The platinum-group element (PGE) distribution in these different deposit types is not well-known however, and PGE determination is fraught with analytical difficulties. To properly assess a prospect or to achieve effective recovery by mineral processing, it is important to determine the mineralogical distribution of the PGE.

Jan 1, 1988

By John Dasher

One of our War Plants processed Bolivian concentrates as low as 17% Sn by the Arnhem process (pressure leach with HCL) and sent the waste acid down a ditch to Galveston Bay where the chlorides, mostly iron, hydrolyzed. Oyster men, and Texas, demandedimpoundment until a disposal process could be developed. A recycle process found by lab work was recommended, piloted and a plant built. This involved cementation of As Sb, Cu, Bi and Ag on light moving scrap iron and of Sn & Pb on Al turnings (then not recyclable), evaporation and crystallization of hydrous FeCl2, roasting crystals in a muffle furnace and absorbing HCI for reuse. The residue from leaching the low grade concentrates was floated to remove undissolved sulfides, classified and passed over sand and slimes tables to get a smeltable concentrate, a discardable sand tail and a slimes tail worth treating After desliming at 2 micro meters cassiterite, oxide flotation gave good, lab results; but commercial equipment wasn't adequate then. Chloride volatilization, with or without smelting gave high recoveries of Sn as SnCl2, whose marketing was questionable. I have heard this was finally fluxed and smelted.

Jan 1, 1992

By Dae Jin Ha

Sticking phenomenon occurring during hot rolling of two STS 430JlL ferritic stainless steels was analyzed by hot-rolling simulation tests. The sticking started from the initial nucleation stage in which the rolled materials were stuck onto the roll specimen surface, proceeded to the growth stage in which stuck fragments grew further, and reached the saturation stage. The modified 430JlL steel had a smaller number of sticking nucleation sites and slower growth rate than the conventional 430JlL steel because of higher high temperature hardness, thereby leading to less serious sticking. When the simulation test was conducted at 1070 °c, Cr oxides were formed on the surface of the rolled materials, and thus the sticking was drastically reduced because of the increased surface hardness of the rolled materials. In order to prevent the sticking, high-temperature properties of the rolled materials should be enhanced when rolled at 900°C or 1000 °C, and rolling conditions and alloying compositions, under which the oxide formation was promoted, were more important than high-temperature properties when rolled at higher temperatures than 1000 oC.

Jan 1, 2008

By T. Lezhava

A new reactor model with rotating cathodes has been developed where various forms (dendrite, spongy) of metal depositions and their uninterrupted removal are accomplished by the realization of high current densities and low energy consumption. At the same time in contrast with the existing methods a high quality metal powder may be obtained from concentrated electrolytes without any specific organic or inorganic additives, which allows raising the intensity of the process. The reactor can be used for electrowinning of metals with low adhesive capacity (Pb, Ag, Cu, Zn, Ni, Co, etc.) and the powders. The obtained products may be utilized in general metallurgy as well as in powder metallurgy.

Jan 1, 2006

By Wenbin Liu

A novel route for rapid synthesis of ultrafine WC-Co cemented carbides with homogeneous binder phase distribution is reported. The composite powder is produced by in situ reduction-carbonization reactions by using WO2.9, Co3O4 and carbon black as raw powders. The reaction equilibrium and phase stability are studied by thermodynamic calculations. The WC-Co composite powder is condensed by spark plasma sintering (SPS) to obtain the cemented carbides bulk. The sintering temperature is lower than that in the conventional sintering methods by 1500C, while the sintering time is remarkably reduced by 3-5 times. The high performances of the hardness and the fracture toughness are obtained. The experimental results confirm that the present processing scheme of in situ reduction-carbonization reactions and subsequent SPS sintering is an efficient way to prepare WC-Co cemented carbides, and is apparently superior to the conventional long-period techniques of preparing composite powder and cemented carbides bulk.

Jan 1, 2008

By M. S. Moats

Galvanic stripping, in conjunction with solvent extraction, has been proposed as a technical option to the challenging problem of iron removal in certain hydrometallurgical processes. The galvanic stripping process is based on the ability of a solid metal to directly reduce ferric ion to the ferrous state in an organic media. Stripping the iron into the aqueous phase is then easily accomplished. Previous work has shown the reaction kinetics and efficiency are affected by such operating parameters as water and oxygen contents, temperature, time and metal reductant. In this study, the optimum operating range for some of these variables was determined. Both zinc and iron metal were used in the separate stripping of iron from D2EHP A. Reasons for the differences in the extent of the reaction obtained using the various conditions are discussed.

Jan 1, 1996

By Qian Xu, Guangshi Li, Xionggang Lu, Xingli Zou, Hongwei Cheng, Cong Xu, Changyuan Lu

The roasting of nickel-bearing sulfides is a complex but important process which has not been adequately characterized. Combination of X-ray diffraction and scanning electron microscopy has been proved to be useful for such experiments. The leaching results of nickel, copper, iron and cobalt was analyzed by ICP methods. Process possibility of polymetallic sulfide concentrates through a three-step procedure (oxidation roasting - chlorination - water leaching) was suggested. Ammonium chloride could react with nickel/copper oxides to produce intermediate complexes. At the temperature range of 280~340 oC, these complexes further decomposed to the corresponding simple chlorides. Roasting sulfide concentrate using NH4Cl is effective for complex ores.

Jan 1, 2016

By E. Yegan Erdem, Fiona M. Doyle, Alyssa A. Maich

"There is an expanding interest in synthesizing high quality magnetic nanoparticles, most notably for biomedical applications. Different processing routes have been reported for the synthesis of magnetite and maghemite. However, some ambiguity remains on their precise chemistry, intermediates, and final products, due to the structural similarity of maghemite and magnetite, and the relative ease of redox transitions during synthesis. Here we present the results of TEM, x-ray and electron diffraction, and SQUID studies aimed at characterizing the products from two different reaction systems, thereby clarifying the reaction chemistry. The first system hydrolyzed aqueous FeCh and FeCb chlorides with ammonia in a micro fluidic reactor at ambient temperature; although the reaction product displayed a uniform distribution, it included non-magnetic goethite and lepidocrocite. If the aqueous solutions contained dissolved oxygen, there appeared to be extensive oxidation of Fe(II). The second system thermally decomposed iron (III) acetylacetonate in ether. In prior studies, oleylamine has been reported to serve as both a reducing agent and capping ligand to control particle characteristics; however, our studies revealed little reduction, with maghemite dominating the reaction products.IntroductionMagnetite and maghemite nanoparticles are co=only used in ferrofluids, in medical applications, and in drug delivery. Superparamagnetic properties, along with low cytotoxicity, colloid stability and bioactive molecule conjugation capability, make these nanomagnets ideal for both in-vitro and in-vivo biomedical applications [1]. One of the major constraints on widespread adoption of nanoparticles for these applications is the amount needed. Typical batch synthesis methods produce polydispersed nanoparticles, which require further size selection procedures to isolate the mono disperse nanoparticle population needed for many applications. In order to maximize the yield of usable particles from a synthesis operation, the reaction conditions must be closely controlled. This requires full knowledge of how the reaction conditions control the various aspects of nanoparticle growth. Many methods have been used to synthesize iron oxides, including sonochemical reactions, mechanochemical synthesis, hydrolysis and thermal decomposition. This work examines the latter two methods, focusing on oxidation and reduction of iron."

Jan 1, 2012

Reduction of titania and ilmenite ores by Cf4-H2-Ar gas mixture was investigated in a laboratory fixed bed reactor. Titania was reduced to titanium oxycarbide in the temperature range of 12OO-1500°C. At 1400-15000C, the extent of reduction of titania to titanium oxycarbide achieved more than 85% in 90 min. Optimum conditions for titanium oxycarbide synthesis by reduction of titania include temperature in the range of 1300-1450°C, methane content 8 vol% and hydrogen content above 35 vol%. Ilmenite ore was reduced by Cf4-HrAr gas mixture to metallic iron and titanium oxycarbide. Metallic iron catalyzed methane cracking and solid carbon deposition. Titanium oxycarbide formed at temperatures as low as 950°C. The optimum temperature for reduction of ilmenite is 1200°C and the optimum methane content is 8 vol%. Increase in hydrogen content increased both rate and extent of reduction. With 5 vol% CH4-75 vol% Hr20 vol% Ar gas mixture, the reduction of ilmenite completed in 60 min. Reduction of titanium oxides to oxycarbide with following chlorination may be an efficient alternative technology for processing of titanium minerals.

Jan 1, 2001

By J. E. Allen

The trend in refractory technology for the copper and nickel industries has been to higher quality raw materials and improved processing technology. These changes have been dictated by the changes in pyrometallurgical processes in these industries. For example the introduction of flash smelting, reaction type smelting and auxiliary slag cleaning furnaces havedemanded better refractories materials. Extensive field applications and improved laboratory testing procedures have helped make this transition possible. Changes in refractory technology, primarily in basic refractories, are followed from the late fifties to the present and into the future.

Jan 1, 1994

By Sarah Beutner Mavrogenes

The mineralogy of three slags from a domestic secondary copper refinery were studied by applied mineralogical techniques to determine the: 1) phases present, 2) phase chemistry, 3) phase abundance, 4) associations, 5) crystalline habit, 6) grain size, 7)microtextures, and 8) causes for certain metallurgical problems, such as metal losses to the slags. The slags were produced by skimming the bath prior to melt-down to allow heat from the flame to reach the bath. The first slag is highly viscous and all three slags contain a large amount of copper. The "first slag", which is skimmed prior to treatment of the bath with fluxes, contains metallic copper, cuprite, delafossite, magnetite, Mg-hercynite, common spinel-chromite solid solution, picrochromite-chromite solid solution, common spinel-picrochromite solid soiution, gahnite, cassiterite, silica-rich glass, and corundum. Its abundant solid refractory phases make the slag difficult to skim. The "soda-rich slag", skimmed after the treatment of the bath with sodium carbonate flux, contains cuprite, delafossite, magnetite, cassiterite, Na-Al-silicate, and Na-Al-Ca-silicate. It contains less metallic copper than the first slag and lacks the refractory minerals. The "phosphorus-rich slag", skimmed after treatment of the bath with a copper phosphide flUX, contains metallic copper, cuprite, delafossite, berlinite, cassiterite, silica, apatite, Cu-Fe-rich apatite, copper phosphate, Cu-Fe-phosphate, and a Pb-phosphate. In contrast to the above three copper-rich slags, recent charges have produced a silver-copper-rich slag. The "silver-rich slag", skimmed after the treatment of the bath with a copper phosphor ide-borax flux, contains, cassiterite, delafossite, cuprite, a Na-Al-silicate, magnetite, metallic copper, MgO, common spinel-chromite solid solution, and wollastonite. Silver ranging from 0.05 to 2.02% was found by atomic absorption and inductively coupled plasma spectrometry analyses in the metallic copper phase.

Jan 1, 1989