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By M. C. Ruiz

This work outlines the results of leaching studies on a copper concentrate containing chalcocite (Cu2S) and digenite (Cu9S5) with an acid saline solution of cupric chloride oxygenated at ambient pressure. The variables studied included the stirring speed, concentration of cupric ions, concentration of HCI, concentration of chloride ions, oxygen flow rate, temperature and time. The leaching system was found to be very effective for the dissolution of the concentrate. Over 95% of the copper was dissolved in 30 minutes with negligible dissolution of iron. The dissolution of copper increased with the stirring speed up to about 400 rpm and depended little on the total chloride concentration. The oxygen flow rate affected the dissolution of copper only below 0.1 1/min. The concentration of HC1 did not influence the dissolution providing its was sufficient to avoid the precipitation of copper oxychloride. The study of the effect of the temperature showed a maximum in copper dissolution around 90 "C

Jan 1, 1997

By Thomas M. Harris

Cation exchange is not sufficiently selective to be used for the removal of heavy metal ions from a general industrial wastewater. However, if the metals can be converted to polyvalent anions through complexation, they may be removed both selectively and efficiently by anion exchange. This approach, referred to as chelation-assisted anion exchange (CAAE), has been examined using industrial wastewater samples contaminated with Ni2+ and Cr3+. For this particular application, the Ni2+ is complexed with 8-hydroxyquinoline-5-sulfonic acid, and the Cr3+ with sulfosalicylic acid. Removal efficiencies and adsorption isotherms for both the complexants and the complexes were determined in batch-mode tests.

Jan 1, 1994

By Yasumasa Hattori

An extensive study including fluid dynamic calculations, cold model tests, pilot plant tests as well as measurements in a commercial flash furnace was carried out in order to develop a new Sumitomo flash smelting concentrate burner. The pressure measurements in the commercial burner indicated that the premixing of the concentrate and reaction air in a burner was insufficient. Pilot plant tests showed that enhancement of the premixing of the concentrate and reaction air is very effective for improving the burner performance. Using the additional pressure drop of the reaction air as an indicator of the premixing, a new type Sumitomo premixed concentrate burner was developed.

Jan 1, 2003

By John J. Jonas, Sang-Hyun Cho, Ki-Bong Kang

"The recrystallization behavior of Nb micro alloyed steels containing Cr, Mo, Ni and Ti. was studied using hot torsion testing with the aim of modeling the recrystallization processes and the mean flow stress taking into account the microstructural behavior during hot rolling. The kinetics of static and metadynamic recrystallization were characterized and appropriate expressions were formulated for the recrystallization kinetics. These are shown that the recrystallization kinetics depend on steel composition and the processing conditions. The stress-strain curves were determined in order to derive new equations for the peak stress, peak strain, mean flow stress and softening kinetics. The peak strain is influenced by the presence of alloying elements; their addition, which has a solute drag effect, retards the rate of grain boundary motion, shifting the peak to the right. The addition of Nb to the steel results in a significant increment in the activation energy for hot deformation, and Mo has smaller effect than Nb, but Cr has the opposite effect. It was also found that the deformation activation energy in these steels was not altered by the addition of Ni. The rate of metadynamic recrystallization increases with strain rate and temperature and is observed to be independent of strain, in contrast to the observations for static recrystallization.The mean flow stress (MFS) calculations, based on the Sims analysis, are then compared with the predictions of a model based on an improved Misaka mean flow stress equation in which solute effects, strain accumulation, as well as the kinetics of static and metadynamic recrystallization are accounted for. Good agreement between the measured mean flow stresses, which is obtained from the mill logs of POSCO Kwangyang #3 HSM (hot strip mill), and 'predicted ones is obtained over the whole range of rolling temperatures. The results demonstrate that dynamic recrystallization followed by metadynamic recrystallization, supported by the unexpected load drops, sometimes occurs for the rolling schedules studied in the present analysis."

Jan 1, 2001

By Xiao-hui Fan, Xu-ling Chen, Xiao-xian Huang, Gui-ming Yang

Grate-kiln-cooler is a predominant process of producing iron ore pellets in China. Since this process is of multi-variant, strong coupling and large hysteresis characteristics, a reliable performance monitoring is thus essential to ensure product quality and economic benefits. Aiming to efficiently monitor the pellet induration within this process, this study proposed an approach that combines statistical analysis and quality soft-measurement. Soft-measurement of pellet quality was accomplished based on the predicted time-temperature profile, and the soft-measured indices were on-line monitored using statistical control charts. Based on the proposed approach, a monitoring system for grate-kiln-cooler thermal process was developed for a domestic pelletizing plant. Running results demonstrate that our system can assist in the detection or diagnosis of abnormal thermal state and finally helps to stabilize the pellet production.

Jan 1, 2016

By Margarete Kalin

Mine abandonment is associated with the securing of access to underground workings, shafts, raises and adits. Waste rock piles and tailings are generally contoured and revegetated. When the waste materials contain pyritic material seepages can often emerge long after the physical reclamation work has been carried out. Their extent and origin has to be delineated to facilitate remedial measures. The depth to which the seepages extended can be determined with an electromagnetic (EM) survey. This paper reports on the experience gained using a winter and a summer EM survey correlated with measurements of specific conductivity at the sediment water interface. Lake sediments and ponds which represent a homogenous background material are good media, where specific conductivity and electromagnetic conductivity can be correlated. The origin of the seepage within the recontoured mine site requires detailed site knowledge, as many anomalies in heterogenous materials such as represented by a mine site are evident.

Jan 1, 1994

By Huaming Yang

The vanadium-doped SnO2 nanoparticle was synthesized by the co-precipitation reaction and subsequent calcination from the vanadium(III) chloride and tin(IV) chloride. The crystal size, pore size distribution, micrograph and properties of the nanocrystalline powders were examined by differential thermal analysis (DTA). thermogravimetric analysis (TGA). X-ray diffraction (XRD), desorption isotherm (Barrett-Joyner-Halenda method) and transmission electron microscopy (TEM). Thermal treatment of the precipitate powder at 600'C led to the formation of crystal0nmincrystal size. Most of the pores in the narmparticle are about 5~15nm in diameter. Effect of doped vanadium on the crystal size of the nanoparticle was discussed.

Jan 1, 2003

By Scott A. Howard

MgO is routinely used as the basis for refractory materials, however, its susceptibility to hydration may result in dimensional instability and subsequent failure. The addition of boron has been shown to reduce th,e hydration susceptibility of MgO yet its dissolution into certain grades of steel may degrade their performance. In order to predict the efficacy of reducing hydration susceptibility by the incorporation of mono-, di-and tri-and quadravalent cations, the lattices of various cation-substituted systems were modeled. To more accurately simulate the substituted lattices, either cation or anion vacancies were incorporated to maintain electrical neutrality and all possible arrangements of defects in a 2x2x2 MgO supercell were investigated. Correlations were then made between the lattice energies of these systems and their susceptibility to hydration as reported in the literature. The results indicate the presence of higher charged cations tended to increase lattice stability while the cations with lower valency tended to have lower lattice energies. The relatively small body of experimental results available in the literature are consistent' with this study's results.

Jan 1, 1989

By Zhigang Liang

Effects of the configuration parameters of submerged entry nozzle on the flow field in slab mold were investigated through a water modeling. The experimental results showed, when the original submerged entry nozzle was applied, there was an appreciable level fluctuation in the mold with obviously naked surface and entrapment of mold flux at higher casting speed. By increasing the outlet area of submerged entry nozzle, without any change of other configuration parameters and submergence depth, a proper fluid field with active surface and good covering of mold flux can be obtained, which is proper to meet the requirement for increasing the casting speed and improving the slab quality simultaneously.

Jan 1, 2009

By Lauri E. K. Holappa

Ferrochrome, as the central constituent in stainless steels is one of the most rapidly growing primary metallic products. In this contribution results of a comprehensive study on the reduction process of chromite ore to FeCr are presented including thermodynamic examination, experimental work on kinetics and mechanisms in solid state, and smelting reduction conditions as well as kinetic modelling of solid state reduction.

Jan 1, 1999

By Ma Keyi, Yang Xianwan, Zhu Xiaoyun, Guo Zhongcheng, Zheng Yanping

"The oxidation of the Multifunctional Electrodeposited RE-Ni-WP- SiC Composites at high temperature is investigated. The results show that during high temperature oxidation the relationship between the mass change of pure Ni , Ni-W-P, Ni-W-P-SiC or RE-Ni-W-P-SiC coating and the oxidation time follows a mixed curve, i.e. it is approximately a linear relationship when the oxidation time is less than 60 mins while it is a power function relationship when the oxidation time is over 60 mins. The order for the oxidation rate of the four coatings is Ni> Ni-W-P> Ni-WP- SiC>RE-Ni-W-P-SiC. The mass change of Ni-W-P, Ni-W-PSiC or RE-Ni-W-P-SiC coating increases exponentially with a rise of oxidation temperature. The high temperature-oxidation resistance of RE-Ni-W-P-SiC composite coating is 3-4 times that ofNi-W-P alloy coating. The cross section morphologies and Xray diffraction patterns indicate that the high temperature oxidation resistance of RE-Ni-W-P-SiC composite coating is better than any other coatings.1. IntroductionWith the rapid development of modem industries the products in engineering industry are continually challenged by the requirements of long-term and stable working at higher temperature, pressure, speed and under adverse conditions. Consequently, the surface properties of the products, such as the resistance to oxidation at high temperature, the resistance to wear and the resistance to corrosion, should be improved continually."

Jan 1, 2000

By Walter Curlook

An improved process of hydrometallurgical treatment of laterite ores of the limonitic type for the recovery of nickel and cobalt using sulphuric acid has been developed and patented [I]. The major improvement is brought about by recycling a significant portion of the "mother liquor" emanating from the pressure leaching reaction back to the feed preparation stage thereby substituting for all or at least a major proportion of the fresh water that must be added. The amount of process effluent waters is correspondingly reduced. Concomitantly with the major savings in fresh water requirements, a degree of reduction in new sulphuric acid requirements is effected, along with a savings in limestone and lime required for subsequent neutralizations. Keywords: Acid pressure leaching; Nickel laterites

Jan 1, 2004

By Akira Yazawa, Kazuo Koike, Mitsuhisa Hino

"The vapor pressures of MS (PbS, SnS and Sb2S3) in the molten Cu2S-MS, FeS-MS pseudo-binary and Cu2S-FeS-MS ternary systems were measured by means of a transportation method in the temperature range of 1323 and 1423K to calculate MS activities in the sulfide melts. The activities of MS in these systems show negative deviation from ideal behavior except the FeS binary systems which exhibit nearly ideal behavior in the homogeneous melts. The activities of the Cu2S-FeS pseudobinary system, which is fundamentals of the copper matte, were estimated from the activity values in the ternary systems and exhibit negative deviation from ideality.The distribution behavior of tin between the ·matte and silica saturated fayalite slag was investigated under the controlled partial pressures of S02 at l 523K. It was found that, in general, tin is distributed in the both phase, while tin is concentrated to the slag phase with increasing copper content in the matte. The activity coefficient of SnO in the slag was calculated based on the distribution ratio combined with the activity coefficient in the Cu2S-FeS system.IntroductionThe thermodynamic properties related to the Cu2S-FeS system and the Cu2S-FeS-MS systems (where MS can be PbS, SnS, Sb2S3, As2S3, Bi2S3, etc.) is required to be better understanding of the copper smelting process. However, thermodynamic analysis such as the distribution of impurities among the gas, slag and matte phases is difficult due to lack of thermodynamic data. In this study, the vapor pressures of MS (PbS, SnS and Sb2S3) in the Cu2S-MS, FeS-MS. and Cu2S-FeS-MS systems were measured by a transportation method. The distribution behavior of tin between the matte and silica saturated fayalite slag was also investigated. The results in the present experiments are useful to analyze thermodynamically the behavior of component in the copper matte smelting."

Jan 1, 2000

By Jiann-Yang Hwang, Ying Qin, Shu-Jing Zhu

Metallurgical Oil Sludge (MOS) is a byproduct created in the process of steelmaking. More than a million tons of MOS are generated each year throughout the world. The material contains hazardous components such as heavy metals and pathogenic organics, which can cause serious environmental problems and health issues. Landfill, combustion, and pyrolysis have been investigated for the disposal of MOS. However, these methods are unsatisfactory since they are unable to reach the clean environment goal. In this study, we investigate the possibility of using MOS as a reductant in a high temperature metallurgical process. The results are reported and discussed.

Jan 1, 2015

By Moo Eob Choi

The reduction of iron oxide particles by hydrogen is one of the most widely investigated gas-solid reactions. The search for new methods for producing iron by the direct reduction of iron oxide has resulted in a large number of exhaustive studies of the various aspects of this reaction. However, previous studies have largely been done with either pellets or lump ores. Little has been published on the hydrogen reduction of very fine concentrate particles smaller than 37 µm (-400 mesh). The kinetics of hydrogen reduction of fine iron oxide concentrates were investigated in the temperature range of 900 - 1300°C.

Jan 1, 2006

By Munyaradzi Kwatara, Ron Schonewille, Edgar Peek, Juzer Tayabally

"The potential recovery of nickel from a South-American saprolitic laterite ore using the segregation roasting technique was investigated. The ore was heated to temperatures that ranged between 900 and 1 000°C in a rotary kiln. In all the tests, the laterite ore was first mixed with a predetermined amount of calcium chloride and either coal or coke. By varying the temperature, calcium chloride and reductant in the different tests, a preliminary set of optimal conditions was established for the specific laterite ore that was tested. A combination of chemical analysis and electron-probe-micro-analysis (EPMA) were used to determine and evaluate the effectiveness of segregation roasting on the recovery of nickel. The present paper describes the test procedure and the results that were obtained.IntroductionIt is known that laterite ore resources account for an estimated 72% of the world's nickel resources, with sulfide sources accounting for the remaining 28%. Yet sulfide resources account for 58% of the world's primary nickel production while laterite resources account for the remaining 42% [I]. There are numerous reasons for this discrepancy, but the most important one is the mineralogical and compositional complexity that is associated with laterite ore deposits. For example, this complexity currently offers only limited opportunities for upgrading, thereby creating capital intensive whole ore processing facilities. It then follows logically that the identification and application of a low-cost processing option for the treatment of laterites could potentially open up an opportunity for exploiting these vast untapped laterite resources.To this end, a preliminary screening investigation was initiated by Xstrata Process Support to evaluate the potential application of the so-called (nickel) segregation process as a unit operation that could potentially be integrated into a laterite processing flow sheet. Laboratory bench tests were performed on this segregation process and this paper details some of the findings from this preliminary investigation."

Jan 1, 2011

By F. Chabchoub

A mathematical model has been developed to study the influence of process variables on the horizontal Ohno continuous casting process. The model simulates the heat transfer and fluid flow in a wide plate ingot of pure tin. A two dimensional numerical analysis based on a control-volume finite difference approach, the Semi-Implicit Method for Pressure-Linked Equations algorithm (SIMPLER), and an Enthalpy Transforming Model was used. The shape and position of the solid-liquid interface were calculated at different casting speeds, ingot thicknesses, and cooling device characteristics, as well as various mould temperatures. Results of the mathematical model were compared with

Jan 1, 1992

By Finn Olesen, Melina Garcia, Mark William Kennedy

"Furnace resistance is a function of the complex interrelationship between many factors including: operating practice, slag conductivity, temperature, power intensity, and geometry (electrode shape, diameter, spacing, immersion, slag depth, etc.).Accurate prediction of resistance is critical for success of the overall furnace design. The sizing of electrodes, columns, bus-bars, and transformers are all impacted. Estimation of minimum and maximum resistance or maximum operational current, as well as the maximum operating voltage are of fundamental importance.Various mathematical tools have been developed to assist designers with the selection of furnace dimensions and the prediction of resistance. Elkem found the methods of Downing and Urban 1965 and Westly 1975, to be particularly useful.In the current paper, comparisons are drawn between data from spent aluminum pot lining (SPL) demonstration testing at Elkem Bjolvefossen and predictions based on these classical tools and 3D finite element modeling (FEM) with COMSOL.®"

Jan 1, 2012

By Alpagut Kara

Turkey is the fifth biggest ceramic tile exporter in the world. Considering the expectation that the Turkish tile sector continues to expand, further studies both on the improvement and the development of tile formulations are necessary in order to make the producers advantaged in the world market while maintaining the capital and running costs at reasonably competitive levels as well. In addition to such studies, waste management in tile manufacturing has also recently become an important issue. Accordingly, the industrial use of wastes in the traditional ceramic industry has been intensively investigated in the recent years. This work describes part of a detailed research project carried out jointly on the possible re-use of muds (raw production waste) from glazing and pressing lines of a local tile company in the development of new wall and floor tile formulations. In order to achieve this, the waste material was firstly investigated in function of chemical and mineralogical compositions. Then, the particular focus was given to the presence of the waste material in increasing amounts on the thermal behaviour and physico-mechanical properties of the re-formulated tile bodies. During the studies, SEM in combination with EDS, and thermal analysis techniques such as non-contact dilatometry were widely employed. The results indicated that it was possible to use the waste materials in the commercial tile production without deteriorating the relevant technological properties.

Jan 1, 2006

By David G. C. Robertson

A new approach is described for the calculation of the kinetics of metal/slag, metal/slag/gas, and metal/matte/slag/gas reactions. The algorithm assumes that equilibrium is achieved at the interface between phases, and uses an equilibrium solver (such as SOLGASMIX) to compute the equilibrium state at the interface at each time step during the reaction. For multiple phase systems a number of unit operations, representing the different phases and interfaces, must be connected together in a reasonalbly complex manner, and the METSIM software package has been utilized for this purpose. The new approach is superior to the SMAK software developed by the author and his co-workers over the past decade, for the reasons discussed in this paper.

Jan 1, 1995