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By Minjun Tang, Jianfeng Zhou, Feng Chen, Linjiang Qing, Xiaolei Song, Yufeng Guo, Tao Jiang

"Reduction swellability index (Rsn and low temperature reduction disintegration index (RDI) of vanadium-titanium magnetite oxidized pellets are harmful to the processing of ironmaking, for example, causing serious gas permeability, decreased yield, higher coke ratio and more furnace dust. Thus, the improvements of RSI and RDI of vanadium-titanium magnetite oxidized pellets were investigated in this paper, including the pretreatment of raw material, additives of dolomite or boric acid, pellets treated in chloride solution and so on. The results showed that damp milling as pretreatment and boric acid added in pelletizing were conducive to the RSI which decreased 5% and 7% respectively, while they were not efficient enough in improving RDI. Dolomite was efficient in improving RSI, but had negative effect on RDI. There was no evidence to show that RSI and RDI would be improved when pellets were treated in chloride solution. Pursuing this further, the mechanism of those improvements were investigated.IntroductionIn the world, vanadium-titanium magnetite utilization is investigated around how to recover iron, titanium, vanadium, and divided into blast-furnace method and non-blast-furnace method according to respective characteristics. Blast furnace method [1, 2] can recover iron and vanadium effectively, but Ti02 cannot be recycled. Non-blast-furnace methods include rotary kiln-electric furnace method, pre-reduction electric furnace method, reduction- grinding method and sodium vanadium-rotary kiln-electric furnace method and so on. [3-7]Comparing to the Non-blast-furnace method, the method of blast furnace smelting has been put into industrial applications. And it has the following advantages: First of all, effective recycling iron and vanadium; Second, technical problems of high titanium slag in blast furnace smelting; Third, it has mature technology in blast furnace smelting."

Jan 1, 2013

By N. Pradhan, B. K. Mishra, B. D. Nayak, B. K. Mohapatra, R. K. Mohapatra

"Present study is about use of a group of Iron[Fe(III)] Reducing Bacteria (IRB) to convert the goethite (a-FeOOH) present in the original lateritic Nickel ore to magnetite under an anaerobic condition and subsequently release the bound Co(III) and Ni(II) through leaching. The lateritic Nickel ore contains 0.8% Ni, 0.049% Co, 1.92% Cr, 0.32% Mn and 50.2% Fe. An anaerobic dissimilatory Fe(III) reducing bacterial consortium capable of using acetate as carbon source (electron donor) and lateritic ore as terminal electron acceptor, changes the initial light brown color of the ore to dark brown. The change in color is due to the conversion of goethite to magnetite, which was confirmed by XRD. When the IRB treated sample was subjected to both bioleaching and acid leaching, it shows a greater recovery of Nickel and Cobalt values as compared to untreated original lateritic Ni ore. Further a magnetic separation method was used to separate the magnetic part of the treated lateritic ore and subjected to acid- and bio-leaching for better recovery of Nickel and Cobalt.IntroductionIt has been known that micro-organisms have the potential to reduce metals but more recent observations have shown that a diversity of specialist bacteria and archaea can use such activities to conserve energy for growth under anaerobic conditions [12]. Natural Fe(III) oxides are high in surface area and are reactive [1]. Fe (III) oxides adsorb a wide range of metal cations and anions by complexation to surface hydroxyl groups [17], and function as the primary redox buffering solid phase in many sediments and subsurface materials [5].Recently a number of bacteria have been isolated based on their ability to use metal ions, including Fe(III), as electron acceptor under anaerobic conditions. These are capable of producing energy by coupling the oxidation of organic compounds to reduction of Fe(III). Iron[Fe(III)]-Reducing Bacteria (IRB) have been isolated and identified from a wide variety of environments including freshwater and marine aquatic sediments and submerged soil [8]. The biogeochemical cycle of iron is linked to those of the trace metals, as many trace metals coassociate with Fe(III) oxides or reduced iron phases (e.g., magnetite, siderite, or iron sulfide). IRB can utilize Fe(III) oxides as terminal electron acceptors for respiration [18]; thereby reducing all or a fraction of the solid. The reductive portion of the iron biogeochemical cycle in non-phototropic environments (e.g., sediments and subsurface materials) is driven by the direct enzymatic reduction of Fe(III) oxides to Fe(II) by dissimilatory iron reducing bacteria [13,14]."

Jan 1, 2009

By Malsuzaki. Kenji

A mathematical simulation model of the Imperial Smelting Furnace operation has been developed for purpose of improving the furnace operation. The model consists of top, shaft and bottom regions. Analysis in the shaft region is based on differential heat and materials balances taking account of reaction kinetics and heat transfer rates, and those in the top and the bottom regions are based on heat and materials balances under a steady-state condition. Longitudinal distributions of process variables such as temperatures of gas, sinter and coke, gas composition and fractional conversion under a practical operating condition were calculated. With this model, the furnace performance under various operating conditions also can be shown reasonably predicted.

Jan 1, 2003

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 V. Yahorava

Mintek has developed a non-destructive Resin-in-Leach method for the recovery of Rare Earth Elements (REE) from phosphogypsum (PG) waste dumps. However, PG from different sources was found to be highly variable in terms of REE recovery and physical properties. Development of a pre-treatment process was initiated to improve the robustness of the current REE recovery process in order to render it effective for any type of PG. Extensive research into the mineralogy of REE associations with PG revealed that the majority of REE are trapped inside phosphogypsum clusters which inhibits their recovery. Hydrothermal treatment of PG-containing slurry was found to result in re-crystallisation of gypsum with the release of REE phases encapsulated in it. This process was tested on various PG samples and subsequent REE recoveries improved from 5 to 80%. This approach carries a large potential for unlocking value associated with gypsum dumps worldwide.

By René Winand

A new process was studied at large laboratory scale at Université Libre de Bruxelles, under contract with Metallurgie Hoboken-Overpelt. A two cathodes (1m long ; 0.2 m high) channel cell was used at 2000 A/m2, with an electrolyte flow rate up to 1.8 m/sec. The main results may be summarized as follows : cathodes are electro¬refined grade in analysis ; metallographic structure and surface roughness are kept under control up to 1.3 cm (one side deposits) ; silver in cathode is controlled by CI and Br ions in solution ; organics must be used at very low concentrations (in the range of 0.1 mg/1, with a consumption of about 0.01 mg/lh).

Jan 1, 1987

By Jim Sundal

Primary steel manufacturers using electric arc furnaces generate one of the largest hazardous waste streams nationwide. The waste stream, known as electric arc furnace dust, is a listed hazardous waste with the designation K061. Oregon Steel Mills, Inc., (OSM) of Portland, Oregon, has implemented a process known as Glassificationn, which uses KO61 as an ingredient in an onsite recycling process. Because OSM was able to demonstrate that the Glassificationm recycling process beneficially uses all toxic constituents in the electric arc furnace dust and that the recycling process produces marketable products, the process is not subject to Resource Conservation and Recovery Act (RCRA) permit requirements. The marketable products manufactured using Glassificationn include roofing granules, ceramic glazes and colorants, abrasive blasting media and, more recently, synthetic slag fluidizers. The purpose of this paper is to identify the regulatory issues for recycling hazardous waste and demonstrate that OSM glass frit is effective as a slag fluidizer in primary steel manufacturing.

Jan 1, 1994

By Susanne Pignolet-Brandom

Fourteen samples of crushed Duluth Complex rock were characterized by the QEM?SEM automated scanning electron microscope image analysis system to evaluate the application of the system to mining waste rock characterization. The system can reliably distinguish the iron sulfides, the copper-iron sulfides and the nickel-iron sulfides. Calcite was distinguished from all other minerals except fluorite. The volumetric abundances were verified by comparing elemental abundances calculated using the QEM"SEM volumetric percentages and appropriate mineral compositions with elemental abundances determined by standard laboratory procedure. The pH and sulfate concentrations of rinse water from laboratory leach experiments correlated well with the mineralogical data.

Jan 1, 1989

By Kirsi M. Riihilahti

The oxidation characteristics of solid copper matte particles under simulated Kennecott-Outokumpu Flash Converting conditions are presented. The effects of feed matte grade, matte particle size, oxygen-to-matte mass ratio, oxygen content of the process gas and temperature on the particle oxidation rate, quality of conversion, particle size change and particle morphology were determined. The converting quality was highest (~68) with the 58% copper matte at 1100°C. At similar conditions, the 72% copper matte was more likely to produce copper oxides and leave unoxidized particles rather than directly produce sulfur dioxide at 1100°C, resulting in an average converting quality of 55. The quality of conversion was poorest for the 72% matte at 920°C (~45); the sulfur removal was extremely low even with a relatively high degree of oxidation. Fragmentation of the particles was significant in all cases with the 72% matte. A higher O2/matte .ratio and higher temperature, in general, resulted in increased fragmentation while oxygen enrichment had no significant effect. With the 58% matte, particle size was found to increase for the finest fractions rather than to decrease due to particle expansion.

Jan 1, 1998

By Nadia H. Rafat, Iman S. El-Mahallawi, Hussein Badr, N. Khattab, Ahmed A. Abdel-Rehim

The basic part of solar water heaters is the collector and the main functional part of the collector is the absorber layer. In this work, a commercial locally available black painting (PACEN code 10382 colour 890), used for swimming pools solar heating, was modified by adding nano-graphite dispersion. The effect of nano-graphite particles percentage on the spectral absorbance of the material was examined on samples containing two values of 1.5 and 2.5% nano-graphite particles by weight. Fourier transform spectroscopy (FTIR) analysis was also used to identify the functional groups in the developed material. A simple experimental setup was designed to evaluate the performance of the developed nanodispersed selective coating polymeric based material, by measuring the increase in temperature of circulating water. It was shown that adding 1.5–2.5% nano-graphite particles to a polymer based black coating causes an increase in the optical absorptance, and an increase in the circulating water temperature.

Mar 1, 2018

By Moto Goto

Onahama Smelter of Onahama Smelting & Refining Co., Ltd. has two green- charge reverberatory furnaces; the old furnace was constructed in 1965 and the new one in 1973. This paper discusses the use of oxygen-oil burners in a green-charge reverberatory furnace and also compares the copper loss in slag between the two furnaces at Onahama Smelter. During the past ten years of operation, no shutdowns of the old furnace were necessary and the smelting capacity was increased by 25% by the use of two oxygen-oil burners. These burners are suitable for a green-charge reverberatory furnace to in- crease the smelting capacity without causing an increase of the exhaust gas volume and refractory erosion. After two years of operation of the old furnace, a bottom build-up in the charging zone of approximately 50 centimeters was experienced, and this build-up has stayed at this level since then. In 1973, a new additional reverberatory furnace was put into operation. Copper content in slag of the new furnace was lower by approximately 0.15% than that of the old one during the first several months after the start-up. Investigations were then made on the effect of the bottom conditions in the charging zone on the copper content in slag.

Jan 1, 1976

By Dieter Neuschiitz, Pengfu Tan

"In order to understand the sintering phenomena during iron ore sintering process, a CFD model of iron ore sintering has been developed, combining with the kinetics of 15 relevant chemical reactions with the aim of describing the temperature fields and the gas flow patterns in the sintering bed. This CFD model can be used to simulate the concentrations of the gaseous and solid species, temperatures of the gas and solid, melting and molten fractions of the mixture, gas velocities, temperature zones and residence times of the gas in each temperature zone. IntroductionThe off-gas analyses clearly revealed that the off-gas of a sinter strand does not have a composition corresponding to thermodynamic equilibrium, for example, the CO, CO2 and O2 concentrations are not the mutually consistent equilibrium values. Apparently the chemical reactions in the sinter bed are controlled kinetically. Therefore kinetic modeling of sintering reactions combined with CFD modeling is necessary to understand the sintering phenomena during iron ore sintering process.Several models of iron ore sintering have been developed since 1970 [l-l 4l, each being more refined than its predecessor. The models were formulated as a series of differential equations to describe chemical and physical changes occurring at a point in the bed. These equations were solved numerically in a vertical plane along the strand. The present CFD model, based on the Nath's model [14], has been published in the reference [15]. In this work, some new chemical kinetic models of gas-solid reactions are incorporated in the present CFD model. The concentrations of gaseous and solid species, temperatures of gas and solid, melting and molten fractions of solid, velocity of gas, and residence time of gas in each combustion zone can be calculated by this model."

Jan 1, 2004

By Charles L. Richman

The effect of the addition of Silver Sulfide on the rate of Chalcopyrite (CP) of Sulfuric acid (H2SD4 leaching is discussed, Although Ag2S in an expensive addition, a theoretical explanation of it's use will aid in the development of a economic substitution. We have used cyclic voltammography to show the presence reaction species at different potentials. Cyclic Voltammography maps the surface reaction current peaks on CP, to regions on the CP Phorbaix diagram. AC Electro-lmpedance spectroscopy (EIS) models the surface impedance properties, which control the rate of electron and ion transfer, and the surface kinetic reactions, with and with out light. EIS and other measurements show that AgCuS u Photo-reactive material- The EIS results are compared with the SEM and EDXA results to show the presence of diffusion pores, and diffusion controlled reactions during CP leaching without the addition of silver sulfate. We hypothesize that AgCuS is an ionic conductor like Ag2S. EIS shows an imposed negative leaching rate greatly. Our theory shows how the formation of Silver Copper (1) sulfide layer at open circuit potential gives an effect similar to negative potential, that is enhanced with illumination. We verify that AgCuAS is an N-type semiconductor that forms a diode type junction with the electrolyte with the Mott-Schoottly relation.

Jan 1, 2001

By Sibin Zhang, Shengli Wu, Youhao Yin, Yuandong Pei, Zhixing Zhao, Jiangshan Shi, Zhengyun Fan

Spraying medium to achieve an energy-saving and emission reduction for iron ore sintering has been researched, such as spraying natural gas, coke oven gas, oxygen, sintering flue gas and gas from annular cooler. This paper focuses on effect of spraying steam on sintering surface on reduction of NOx and dioxin emissions in practical sintering production in Shougang Jingtang. It can be found that, with the increase of sintering bed spraying steam amount, NOx and dioxin of flue gas showed a decreasing trend. As spraying steam 1 t/h for 550 m2 sintering machine in Jingtang, NOx content decreases 2.6–9.5 mg/Nm3, and dioxin decreases 0.007–0.014 TEG ng/Nm3.

Mar 1, 2018

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 G. Kyle Green

Zirconium chlorinator residues contain an array of rare earths, scandium, unreacted coke, and radioactive thorium and radium. Because of the radioactivity, the residues must be disposed in special waste containment facilities. As these sites become more congested, and with stricter environmental regulations, disposal of large volumes of wastes may become more difficult. To reduce the mass of disposed material, the U.S. Bureau of Mines (USBM) developed technology to recover rare earths, thorium and radium, and unreacted coke from these residues. This technology employs an HCl leach to solubilize over 99% of the scandium and thorium, and over 90% of the rare earths. The leach liquor is processed through several solvent extraction stages to selectively recover scandium, thorium, and rare earths. The leach residue is further leached with an organic acid to solubilize radium, thus allowing unreacted coke to be recycled to the chlorinator. The thorium and radium waste products, which comprise only 2.1% of the original residue mass, can then be sent to the radioactive waste facility.

Jan 1, 1995

By Xuan Cheng

The electrochemistry of sulfide mineral flotation is reviewed with particular emphasis on galvanic interaction among minerals and grinding media, and its relevance to flotation of complex sulfide ores is discussed. Surface alteration due to galvanic interactions among chalcopyrite, pyrrhotite and mild steel is analyzed in terms of voltammetric and chronoamperometric studies on individual minerals and through galvanic current measurements in 2- and 3- electrode combinations. The results are related to laboratory flotation behaviors of chalcopyrite-pyrrhotite mixtures simulating copper-nickel bearing Duluth gabbro.

Jan 1, 1993

By Ahmet Haxhiaj, Jaroslaw Drelich

"Both composition and porosity of pellets are the main parameters influencing the reductive melting process in water-jacket furnace during the roasting of sulfide lead concentrate. Roasting in a smelter located in Trepçë is done at about 9000C, for pellets which are composed of PbS, CaCO3, Fe2O3, and SiO2. In order to faciltiate the formation of slag in the reductive melting, the pellets must have the proper content of CaO, SiO2, and FeO, and porosity. The plant’s practice indicates that pellets with porosity of 18% do not melt adequately in the water-jacket furnace. The optimum porosity for the proper melting of pellets needs to be 32-40% and can be achieved when pellets are loaded with more than 10 wt.% CaO. Pellets with less than 10% CaO have a limited network of pores, such that reactive gases cannot reach the entire ore structure. Also, the composition of the pellets must satisfy the ratio of CaO : SiO2 : FeO = 1 : 1.2 : 1.8 to facilitate the formation of slag in the reductive melting process.IntroductionAgglomeration roasting of sulfide lead concentrate is an important phase in the production of lead by reductive melting [1-6]. The reductive melting process is a complex process with contradictory effects of several technological indexes which many times are hard to measure and determine. In this process, loading the water-jacket furnace with pellets of optimized composition and structure can reduce the consumption of coke, and achieve high level of lead recovery. Pellets (agglomerates) should be porous, but at the same time they should have necessary mechanical strength. ‘Self-melting’ ability of pellets is controlled by the types and quantities of fluxes blended into the pellet composition. Three major additives and their role are:"

Jan 1, 2011

By Francis Vanbellen

Umicore Precious Metals Refining operates an integrated precious metals smelting and refining plant in Hoboken, Belgium. Once a smelter and refiner of complex concentrates, the plant today?s feed consists exclusively of industrial and consumer recycled products, making it the world?s largest recycling facility for precious metals. Unlike the fairy tale of the Frog Prince, it took much more than a princess? kiss to successfully realize this makeover. A completely renewed plant has been built over the past decade. The most visible technological innovation was the commissioning of the Pb-Cu smelter. Its flexibility towards very different types of feed makes it perfectly suited as main entry to the Hoboken flow sheet. A new Cu-leaching & electro winning plant and precious metals refinery make up the Precious Metals Operations (PMO) whose targets are fast throughput and maximized yields for gold, silver and the platinum group metals. The Base Metals Operations (BMO), flexibly process the by-products from the PMO, valorizing ?impurities? like indium, tellurium, selenium and others. Off gas and waste water treatments ensure compliance with strict environmental standards. Precious metals recycling is an art that goes beyond mastering a unique flow sheet. Umicore Precious Metals Refining offers a complete recycling service, taking care of sampling and assaying, metals management and logistics. The quality of this integral service is recognized through the attribution of ISO certifications for our operational activities, sampling and the environmental care. And it?s an art that follows Michelangelo?s experience: ?Art is 5% of inspiration and 95% of transpiration.?

Jan 1, 2006

By Oscar Restrepo, Juan C. Nino, Henry A. Colorado

New and extraordinary physical-chemical properties of materials at nanoscale open up new applications for the building and infrastructure industry such as structural reinforcements, electronic properties and energy harvesting. Therefore the issues and risks associated with the manufacturing of nanomaterials are now of big concern due to the large volumes and typical processing involved in this industry. This paper presents a discussion and selected applications of nanotechnology in the construction and building materials: from metals and alloys, clay and minerals, ceramics, cement and concrete, asphalt, wood and composites, to finishing systems and some of the most used characterization techniques. Besides the progress in some areas, nanotechnology is just emerging in this field, with many challenges and opportunities, problems unsolved and business opportunities. A discussion regarding the potential health issues and risks of using nanomaterials for workers and the potential environment effects is included as well. New images and diagrams are presented and discussed.

Mar 1, 2018