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By Varadarajan Seshadri

A physical model based on similarity principles was constructed for simulating the RH degasser of CST (Companhia Siderurgica Tubarao, Vitoria, ES, Brazil) to evaluate the circulation rate of the metal which essentially defines the degree of exposure of the metal to vacuum in the chamber and thus of the refining rate, The circulation rate on the other hand will influence the decarburization rate and removal of dissolved gases like nitrogen and hence it is essential to optimise this parameter to get maximum refining efficiency with minimum refining times, thus improving the productivity of the secondary refining process. Mixing characteristics in the ladle is evaluated by pulse tracer addition using conductivity-meters located at the down leg as well as at several locations in the ladle. The influence of gas injection through nozzles in the upleg with simultaneous bottom injection of gas as well as nozzle blockage on the circulation rates were investigated. Also simulation experiments of kinetics of decarburization were carried out using CO2 adsorption-desorption process in sodium hydroxide solution as circulating fluid and the effect of, bottom gas flow rate in this case was also evaluated. The results were carried over to prototype and to optimize the process.

Jan 1, 2003

By Mingming Zhang, Marshall S. Coe, Marcelo W. Andrade

To supply iron units and flux burden in blast furnaces, sinter basicity is one of the vital parameters for sinter plants. The sinter basicity also plays an important role in sinter quality since it imparts the formation of different mineral phases in sinter. Pot-grate sintering tests were carried out with low and high basicity to investigate the effects of sinter basicity on sinter mineralogy, properties and productivity. It was found that with an increase in sinter basicity, both sinter productivity and reducibility (RI) increased. Tumbler index (TI) and low temperature degradation index (LTD) of high basicity sinter were comparable to low basicity sinter. Softening and melting tests showed that sinter with 3.5 C/S basicity had slightly higher softening temperature comparing to lower basicity sinter with C/S 2.6, acid and fluxed pellets. XRD analyses confirmed the formation of silico-ferrite of calcium and alumina (SFCA) and calcium ferrite (CF) in the tested sinter samples.

Jan 1, 2015

By Ram V. Ramachandran

As an industry with major potential impacts (both good and bad) on water resources and due to the rising costs of process water, the mining and metallurgical processing industry has a key responsibility to contribute to the overall goal of preserving both the quantity and quality of water available within the watersheds they operate in. As we plan for new and existing mining and metallurgical projects, we need to consider a hierarchy of options to minimize our impact within the watersheds we operate; keeping clean water clean by diverting around our operations; reduction in the amount of water we use; reuse of water wherever possible, and improvements to water quality for recycling and/or release to environment. Technology is needed to treat water to improve its quality for reuse or release to the original watershed. While lime precipitation followed by sulfide polishing is effective for removal of most of the metals, it does little or nothing to remove ammonium ions and anions such as chloride, nitrate, molybdate, arsenate and selenite/selenite. Regulations on sulfate limits in treated discharge water has drawn close attention to the treatment of acid mine drainage (AMD). Management of brine and salt disposal is also posing a problem due to strict regulations and cost of disposal. This paper will: (a) address issues associated with managing water with the objective of maintaining water sheds—status quo-during and after operation (b) discuss potential technologies for advanced water treatment plants.

By Qiang Zhong, Bin Xu, Qian Li, Wei Gao, Yongbin Yang, Yaxuan Wang

Lump coal with high volatility is used for providing heat and reductive gas, and ensuring permeability in COREX. However, it is apt to be pulverized in transport and storage process. Therefore, comprehensive utilization of the pulverized coal to produce coal briquettes with appropriate binders is significant, among which the molasses binder cannot meet the technological requirements. In this paper, coal tar pitch binder and BJ additive were used in briquetting and carbonizing process of coal powder. The results showed that BJ effectively activated cold state cohesiveness of the pitch and make it bond the coke particles to a firm briquette at room temperature .Carbonizations of coal and coal tar pitch achieved obvious constriction and formed a carbonized skeleton. The drop resistance of wet briquettes reached over 50 times/1meter. When cured at 1000 °C for 1h under nitrogen atmosphere, the compressive strength of carbonized briquettes came to 6.43 Mpa.

Jan 1, 2016

By Evgenii Pavlov, Ivan Tronin, Viktor Timofeev, Vladimir Kislov, Sergei Bogovalov

"Modeling of the magnetohydrodynamical (MHD) and thermodynamical processes during the industrial scale Direct Chill (DC) casting of aluminum slabs is performed using a combination of ANSYS/CFX and ANSYS/EMAG software. The electromagnetic field is modeled through ANSYS/EMAG, while hydrodynamic and thermodynamic processes are modeled through ANSYS/CFX. Both packages were modified in order to calculate MHD flows in the liquid pool that forms during aluminum DC casting, and they were unified into a software combination that provides simultaneous simulation of all the above processes. The simulation shows that the electromagnetic stirring of the molten aluminum changes the shape of the solidification front (solid-liquid interface) very dramatically, namely it becomes significantly flatter. This effect should improve the internal structure of aluminum DC slabs and allows us to increase the casting velocity.IntroductionProduction of Aluminum alloys with high mechanical properties and structural uniformity is one of the main goals of industry. The preferred production method of aluminum alloys in most modern plants is Direct Chill (hereafter DC) casting because it offers high productivity and commercial success. One important limitation of this technology is the development of centerline shrinkage in slabs larger than about 1 meter. The improvement of the internal structure of long DC cast slabs can be achieved by electromagnetic stirring (hereafter ES) of the liquid metal above the solidification front. This intensifies heat transport in the zone close to the solidification front and suppresses shrinkage formation."

Jan 1, 2013

By H. A. F. de Souza, Dana S. Mills, P. E. Burgener

"ICP-MS has moved from a laboratory curiosity to a functional analytical tool. This paper discusses how ICP-MS has been used to solve difficult analytical problems encountered when analyzing various mine materials. Comparisons between analytical techniques applied to the analysis of gold and the platinum group metals illustrate the advantages and problems of ICPMS when. applied to trace levels of some metals iri the presence of ore grade metals. Interferences and matrix effects are compared to ICP, AA and Neutron Activation. The necessity to select chemical extractions which are compatible with ICP-MS are also discussed.The ICP-MS techniques explained in the examples on Au and precious group elements (PGE) have validity in analytical problems encountered in testing of trace metals in the presence of major elements found in mine materials. Exploration and environmental testing are other areas that require the same analytical approach to quantify trace levels in the presence of major interfering elements normally associated with mining environments."

Jan 1, 1999

By Motang Tang, Chaobo Tang, Shenghai Yang, Lulu Guo, Yun Li, Yongming Chen, Jing He

A new innovative process for one-step and cleaner extraction of lead from spent lead-acid battery by reductive sulfur-fixing smelting was presented. This paper summarized and discussed several potential sulfur-fixing agents and molten salts which can be used in this new technique. Thermodynamic analysis involving reaction mechanism, ΔGT and predominance-area diagrams of different smelting systems were performed, respectively. The results proved the technical feasibility and high-efficiency of this process. Copper oxide ash (CuO), zinc oxide ash (ZnO) and iron oxide bearing residues (FexOy) can be used as sulfur-fixing agent to extract lead through exchange reactions. Sulfur-fixed efficiency of CuO, ZnO and FeO decrease slightly in turn. Sulfur contained in PbSO4 is fixed in form of Cu2S, ZnS and FeS respectively which avoids SO2 emission. The addition of molten salt can significantly decrease temperature of reductive sulfur-fixing reactions. Molten salt can be regenerated and recycled in smelting system after filtering solid residues.

Mar 1, 2017

By John W. Graydon

Incineration is an attractive alternative to the disposal of MSW in landfill sites. However, the process of incineration generates fly ash which contains significant levels of leachable heavy metals - particularly cadmium, lead, and zinc - and it is essential to manage this fly ash in an environmentally sound manner. The compositions, phases, textures, morphologies and size of fly ash particles have been studied by light microscopy, scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. The detailed spatial relationships and speciation of the environmentally significant constituents have received particular emphasis. The information obtained is useful in understanding how fly ash is formed during incineration, in understanding the leaching behavior of untreated fly ash if it is disposed of in a landfill and, most importantly, in guiding the development of the best treatment strategies for fly asti to mitigate its environmental impact.

Jan 1, 1992

By Jerry L. Smith

Industry on a whole has not been very receptive to government prodding to implement waste minimization programs. Waste minimization has the appearance of substantial benefits, however, there are underlying difficulties and suspicions that need to be addressed before industry will support pollution prevention initiatives. They can be summarized as follows: - Human behavior resists change, uncertainty, and unknowns. - New waste minimization techniques are difficult to find and research. - Calculating the true cost of present waste practices as well as new techniques being considered is difficult and time consuming. - Getting a consensus opinion of all the individuals affected on the course or technique to be employed in a pollution prevention program. New software products have addressed many of the problems associated with implementing pollution prevention programs: They contain research on a large number of pollution prevention techniques and case studies; they generally are accessed by EPA ID number, chemical name, or synonym; and some programs have the option to print a comprehensive written user-specific pollution prevention program.

Jan 1, 1994

By Yang Xianwan, Zhu Xiaoyun, Guo Zhongcheng, Zheng Yanping, Zhai Dacheng

"Corrosion resistance of RE-Ni-W-P-SiC composite coating and 3 l6L stainless steel in corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions at different concentrations by means of immersion methods and anodic polarization curves obtained by DHZ-1 electrochemical synthetic tester and HDV-7 transistor constant potentiometer. Immersion experiment results show that corrosion rate of RE-Ni-W-P-SiC composite coating as-deposited in HCl solutions increases with the rise of HCl concentrations, on the contrary, the corrosion rate of the composite coating after heat treatment decreases with increasing the HCl concentrations the corrosion rates of the coatings as-deposited and after heat treatment in H2SO4 and H3PO4 solutions respectively decrease with the rise.of H2SO4 and H3PO4 concentrations the corrosion rate of the deposit as-deposited in FeC13 solutions decreases with increasing FeC13 concentrations, while the rate of the composite coating after heat treatment increases .with the rise of FeC13 concentrations.In addition, the corrosion rate of 3 l 6L stainless steel in the corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions at different concentrations increases with rising of concentrations. Furthermore, the corrosion rate of 316L stainless steel in the corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions respectively is much greater than that of the RE-Ni-W-P-SiC composite coating as-deposited and after heat treatment in the same corrosion media.1. IntroductionAll the materials and their products, when processed, stored and used, it is inevitable that the corrosion, wear, fatigue and crack occur owing to the actions of surroundings. Those early failure and abrasion, through all kinds of departments and profession that corrosion consumes one percent of tens of the steel products of the whole world; and two or four percent of the GDP is lost because of the corrosion."

Jan 1, 2000

First, a classification of the various primary sources of feed materials for the production of cobalt is presented from a mineralogical point of view : sulfides, arsenides, sulfo-arsenides and oxide minerals. Each of these cate- gories will be characterized by its behaviour towards concentration methods, taking account of the presence of the associated minerals of other metals and of the nature of the gangue minerals. Then, for each category of cobalt bea- ring ores, typical flowsheets of treatment will be presented and discussed and the characteristics of the cobalt concentrates produced will be under- lined having in view their subsequent processing by pyro - and (or) hydrome- tallurgical methods.

Jan 1, 1988

By Nathalie Neveux

For the first time, dehydrated ferrous sulfate was successfully used for the dry synthesis of potassium ferrate. In addition, ferrate ion is stabilized as a solid solution where hexavalent iron is partially substituted by S(V1) leading to a sulfato-ferrate having the following formula K2(Fe,S)04. This substance has an efficient life time of about six months. Ferrate ion is a powerful oxidant ( EO = 2.2V ), a bactericidal agent and possesses coagulant, flocculant properties. Its reduction generates nascent oxygen, hydroxyl groups and Fe(OH)3. Alkali metal ferrate is probably the future global agent for water treatment. Applications of this material in the field of urban and industrial effluents treatment have been investigated. Heavy metals cations such as Cu, Cd, Mn, Ni, Pb, Zn, ... were successfully removed. The results of sulfato-ferrate use for cyanide destruction, decrease in COD, soil, discoloration of pulp and paper effluents will be summarized.

Jan 1, 1999

By Gordon A. Irons

"Powder injection for melt refining is widely practiced in the steel industry, and is gaining acceptance in the non-ferrous industries. In these commercially-important systems, the thermodynamics and kinetics may be very complicated. More than one element may be removed by refining, and often the refining agents are not just one compound. In this paper, the thermodynamic and kinetic aspects of these processes are reviewed. A number of examples are given, such as the desulphurization of iron with a variety of reagent mixtures, and selenium removal from copper with several different reagent combinations.IntroductionI am very pleased and honored to present a paper at this Symposium recognizing the many contributions of Professor Howard Womer. Even at the time I was an undergraduate student, the WORCRA process was part of the curriculum. I remember at the time that I was fascinated by the concept, and due to it and the many other rapid developments in Process Metallurgy, I chose it as my field of study. I think the Symposium is testimony that Professor Womer has touched the lives of many others as well.My original assignment was an overview of the basic aspects of gas and solids injection. However, I reviewed most of this material at the Savard/Lee Symposium [1]. In the present paper, I will present some of the basic issues related to refining with powder injection, using work that we have recently completed in both ferrous and non-ferrous systems."

Jan 1, 1996

By Chai Li-yuan

The anodic behavior of AZ31 magnesium alloy in NaOH alkaline solution was investigated in this paper. The effects of anodizing parameters, such as applied current density, concentration of NaOH and temperature of the solution on the formation, structure and surface morphology of the anodic films were also studied. The formation of the anodic film was analyzed by analyzing the anodic polarization curves, the potential-time curves and XRD, SEM graphs of samples obtained at different anodizing time. The results of corrosion resistance tests, XRD and SEM observation showed that the temperature greatly affected the formation and anti-corrosion property of the anodic film, but the concentration of NaOH not. The film with best anti-corrosion resistance was obtained at applied current density of 10mA/cm2, 353k in 1mol/l NaOH solution.

Jan 1, 2006

By Ming-Feng Ye, Jun Wang, Guang-liang Wu

In order to reduce the Al2O3 inclusions in 50Cr5MoV roller steel produced by EBT-LF-VD-VC process in a steelmaking plant, the LF refining slag was optimized and the influence of optimized slags with different w(CaO)/w(Al2O3) ratios on reducing inclusions were investigated in the laboratory. The results showed that, when w(CaO) = 50–55%, w(Al2O3) = 25–30% and w(CaO)/w(Al2O3) = 1.5–2.0, this optimized slag can not only reduce massive Al2O3 come from aluminium deoxidation, but also change the remain into plastic CaO-MgO-Al2O3 spherical compound inclusions with 1–5 lm diameter, the harm on the performance of the steel was minimized.

Mar 1, 2018

By Lin Li, Xiang Li, Yifang Zheng, Jilai Xue, Jun Zhu

"Al drops and gas bubbles in the anode-cathode space of aluminum electrolysis cell are of great importance for cell operation improvement in metal loss, current efficiency and energy consumption. A direct observation on the Al drop, gas bubble and ultrasound was carried out through a see-through cell. The Al drop immersed into the cryolitic melt was found moving up and down irregularly in the anode-cathode space without electrolysis, which was then completely dissolved into the melt. During electrolysis, the Al drop came to the anode area and reacted with the gas bubbles generated on the anode. Under ultrasound, the gas bubbles were removed from the anode surface while the Al drop was kept on the side of anode. The observed phenomena were useful for technology improvement in reducing the anode-cathode distance or lowering the energy consumption in aluminum electrolysis.IntroductionDuring aluminum electrolysis, aluminum metal drop and anodic gas bubble are in close contact each other within the anode-cathode space, and the interaction between them can produce significant impact on metal loss, current efficiency and energy consumption. The motions of the Al drop and the gas bubble are also related to the dissolution of aluminum metal into cryolitic melt and the cell voltage drop due to the bubble layer covering the anode surface.A number of studies have been carried out using different types of see-through cells, where the dissolving process of metal Al into cryolitic melts (metal fog) in the anode-cathode space was directly observed and photographed [1, 2]. With the similar method, some direct observations on the anodic bubble behaviors with and without ultrasound were performed during aluminum electrolysis [3-6]. However, to our best knowledge, there is no published work on direct observation on the behavior of Al drops and anodic gas bubbles staying together within the same anode-cathode space, as well as the motion and interaction of them in cryolite-alumina melts."

Jan 1, 2011

By Brajendra Mishra

Molten Salt electrolytic processes offer unique opportunities to extract and refine metals where gaseous or metallothemlic reduction, hydrometallurgical extraction and aqueous electrolytic methods are thermodynamically constrained. Production of aluminum and magnesium by molten salt electrolysis are well known commercial processes. Several other reactive metals, such as lanthanides and actinides, as well as beryllium and calcium, make use of molten salt processing for extraction and refining. This presentation describes the science of molten salt chemistry and electrochemistry for winning and refining of several metals. In addition, recovery of metals from waste process salts by molten salt reduction as well as oxidation have been discussed. Material issues in design of molten salt reactors have been included. Various applications have been presented through case studies. Experimental data have been included to justify the suitability as well as limitations of these specific processes.

Jan 1, 2003

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 Djalma Souza, Jean Igor Margem, Sergio N. Monteiro, Frederico M. Margem

Synthetic fibers have been used for many years to attend the demands required by the technologica lfields. However, the use of them has been questioned due to the impact on the environment. In this way, the natural fibers have received extensive attention, in particular hybrid fabrics of natural fibers to reinforce environmentally friendly polymer matrix composites. Thus, the present work has the objective of evaluating and comparing the mechanical properties of composites formed by hybrid fabric with 70% Malva—30% Jute in epoxy polymer matrix. The tests carried out are the Charpy and Izod Impact Tests, with specimens of 10, 20 and 30% in volume of hybrid fabric environmentally friendly into polymer matrix composites at room temperature. The 30% samples had the best results, functioning as an efficient reinforcement.

Mar 1, 2018

By Sepp Härkki

The energy crisis in Finland after World War I1 together with a sharp rise in the price of energy caused Outokumpu Oy to consider replacing the electric furnace smelting of copper concentrates by some other method. The flash smelting method developed under these circumstances offered a considerable saving of fuel through the utilization of the reaction heat of sulphides and yielded a high recovery of sulphur in the form of acid. The pilot plant testing of the new process was carried out in the years 1947 - 1948. The process was adopted for the smelting of copper concentrates (1) (2) (3) on a commercial scale in 1949 and applied successfullv to the smelting of -nickel concentrates' at the Harjavalta Works in 1959 (4) (5) (6). In 1962 Outokumpu adopted another type of flash smelting where elemental sulphur is recovered from the gases after the thermal decomposition of pyrite in the flash smelting furnace (7) (8): In recent years, the copper-nickel flash smelter and pyrite process have been combined to produce elemental sulphur instead of SO2 from the smelter gases (9) (10). The basic idea of the Outokumpu flash smelting process for sulphidic ores is that the conventional methods with separate roasting and smelting operations are replaced by a combined roasting, smelting and part-converting process carried out in one unit. The heat generated from the exothermic reactions can thus be used for smelting the ore so that only a small amount of additional fuel is needed. The characteristic of the method is also that the dried, fine-grained concentrate is smelted in suspension, which offers the best conditions for rapid reactions. The recovery of waste heat from the furnace off-gases had been considered already in the original flash smelting system. A

Jan 1, 1976