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By John L. Watson

The dewatering of steel industry waste sludges prior to discard or recycling often presents significant problems due to the fineness of the sludge particles, which may blind the filter medium and/or produce a cake with limited porosity, Several steel plant wastes, such as sludges from BOF and EAF gas cleaning operations exhibit not only a very fine particle size, but also some degree of magnetic character, A novel process has been developed to utilize the magnetic character of such sludges to enhance dewatering through a multi-force operation involving magnetic, chemical and vacuum forces, The process consists essentially of undertaking vacuum filtration of a flocculated sludge in a magnetic field, This is achieved by installing a permanent magnetic in a fixed position on the axis of a vacuum drum filter, thus effecting filtration of magnetic and non- magnetic particles, bound together in flocs, in a magnetic field, Previous tests using a modified laboratory vacuum drum filter treating artificial (magnetite) and industry waste (BF sludge) feeds have demonstrated that filtration capacity may be enhanced significantly with increases of up to 3000/0, An explanation of the mechanisms associated with the enhanced filtration was not obvious, and this research was undertaken to permit the cake formation in the magnetic field to be monitored to provide an insight into the manner in which particles agglomerate to form the cake. These tests revealed that the magnetic field caused magnetic particles to be aligned perpendicular to the filter surface and to form channels through which filtrate could freely pass thus increasing capacity, The effects of various magnetic fields and field strengths on the filtration process were also investigated. A simple computer model was constructed to demonstrate the proposed theory of multi-force dewatering, The model output graphically illustrated the suggested mechanism and confirmed the enhanced capacity of the novel dewatering process,

Jan 1, 1996

By Philip Arthur

The ISASMELT process is making a significant contribution to the global metals industry. ISASMELT furnaces are now operating successfully in eight different countries and treating approximately 3 million tonnes of concentrates and secondary materials per year. The process is currently used in both lead and copper smelting. The most recently commissioned plants were in Germany and China, one for treating scrap copper and the other treating low-grade copper concentrates. The Copper ISASMEL T furnace ("CIF") at Mount Isa Mines Limited (UMIM") has continued to set new operational records, with throughput of more than I million tonnes of concentrate per year and very low operating costs. This paper summarises the latest operational data from the Mount Isa Copper ISASMEL T plant and outlines the successful approach to industrial R&D taken by MIM in the development of the ISASMEL T process.

Jan 1, 2003

By Linfeng Zhou, Yuanbo Zhang, Rong Sun, Guanghui Li, Zhiwei Peng

The volatilization behavior of rhenium in the process of oxidative roasting of a molybdenite concentrate with 43.55 wt.% Mo and 321 g/t Re is explored based on identifying the relationship between volatilization of sulfur and rhenium. The results show that rhenium volatizes after sulfur and precise control of operating variables plays an important role in separating rhenium from molybdenite concentrate. When the roasting parameters are optimized as follows: roasting temperature 600 oC, roasting time 2 h, roasting atmosphere air, the volatilization rate of rhenium reaches 89.26%. In the process of solidification roasting, the volatilization rate of rhenium decreased almost to zero when the ratio of slaked lime/molybdenum concentrate was 10% excess to the stoichiometric requirement at 600 oC for 2 h.

Jan 1, 2016

By Hong Yong Sohn, Miguel Olivas-Martinez

"Different approaches are used for calculating the ‘energy requirement’ of a process. The determination of energy requirement becomes confusing for a process in which a fuel is also a reactant. The key issue is which heat of chemical reaction should be included in the ‘energy requirement’ value. We will use the example of ironmaking processes to illustrate the problem. The different approaches essentially boil down to the question: does one include the combustion heat of the reductant used in the reduction reaction or just the heat of the reduction reaction? Depending on the viewpoint, either approach can be accepted; it is a matter of convention. There is a need, however, to select a standard approach because the absolute value of ‘energy requirement’ of a process depends on the choice. The energy requirement of a novel flash ironmaking process will be compared with that of an average blast furnace operation.IntroductionDifferent approaches are used for performing energy balance calculations and perhaps more significantly in presenting the ‘energy requirement’ of a process. The question becomes more involved for a process in which one or more reactants are also used to generate the process heat by combustion. Often the key issue is which heat of chemical reaction to include in presenting the ‘energy requirement’ of the process.It is worthwhile to note at the outset that the difference in energy requirements between different processes for converting similar raw materials to the same desired product is largely unaffected by the choice of chemical reactions to be included. However, the absolute value presented as the ‘energy requirement’ of a process can be different by a large amount depending on the approach. We use the example of ironmaking processes to illustrate the problem. In these processes, as currently practiced or under development, carbon and/or hydrocarbons (including hydrogen) are used as the fuel as well as the reactant for reducing the iron oxide mineral.The different approaches in this case essentially boil down to the following question: does one include the combustion heat of the reductant used in the reduction reaction or treat the reductant portion as just a reactant? Depending on the viewpoint, either approach can be considered acceptable. It is a matter of convention. There is a need, however, to select a standard approach because the absolute value of ‘energy requirement’ of an ironmaking process (e.g., the currently dominant blast furnace process) depends on such a choice. It is particularly important to clearly state the specific approach used when the energy requirement of ironmaking is compared with those of other industrial processes such as petrochemicals production."

Jan 1, 2014

By Z. B. Moukhametshina

The process of various zirconium alloys iodination by the iodine vapor was investigated. The nature of impurities, conditions of iodination, iodine flow rate, and zirconium tetraiodide condensation rate effect on the metal impurities transfer process was analyzed, both qualitative and quantitative correlations were established. Impurities were classified according their transfer extent. Another classification of impurities transport dependence on iodination process temperature was also offered. Obtained results were compared with impurities transport data in the process of iodide refining available in literature. Some impurities transport mechanisins and iodide-refined metals improvement possibility by means of iodination conditions control were discussed.

Jan 1, 1997

By J. Rajek

The novel multi-component, multi-particle, multi-phase precipitation model developed recently is used to predict the precipitation kinetics in complex 9-12% Cr steels investigated within the European COST 522 project. These steels are used for tubes, pipes, casings and rotors in USC (ultra super critical) steam power plants for the 21st century. In the computer simulations, the evolution of the precipitate microstructure is monitored over the entire production heat treatment starting with the casting process, including austenizing, several annealing treatments and in-service conditions. The main interest lies on the concurrent growth and coarsening interaction of different types of precipitates. Keywords: Precipitation kinetics, heat treatment, power plant steels, simulation

Jan 1, 2003

By Rafael Colás

Computer visualization can be employed in industry as an aid to the understanding of the complex interactions between variables encountered in production. The examples of ingot casting of rimming steel and that of hot rolling of low carbon steel strip are presented. Both processes are mathematically modeled, and their results are presented in a graphical way. Such models have been proven to be an asset in quality improvements and increase of productivity as the personnel involved get a better understanding of their job.

Jan 1, 1993

By J. Rastas

The recovery of lead, silver and gold from existing and potential zinc process residues using a sulfidization-flotation method was investigated on a laboratory scale. The following residues were tested: neutral leach residue, high acid leach residue, and hematite residues. The sulfidization of lead and silver is carried out at low pH by the addition of a stoichiometric amount of sulfide at a controlled rate. To increase the particle size of the sulfides, seeding with synthetic lead and silver sulfides -is employed. The flotation is carried out at pH 2-4 using low pH-collectors such as dithiophosphates and dithiophosphinates. Special attention must be paid to the role of oxygen in the conditioning stage. The effect of different parameters on both the sulfidization and the flotation has been evaluated. Recoveries of 85-90, 90-95 and about 80 % were obtained for lead, silver and gold, respectively. Typically, concentrates containing 50-60 % lead, 3-5 kg/t silver and 10-15 git gold were produced.

Jan 1, 1990

By Xiangru Chen, Honggang Zhong, Qijie Zhai, Qingqing Sun

"A horizontal directional solidification equipment, with an in-situ pouring system, was employed to physically simulate the solidification behavior of continuous casting. In this paper, the 2304 duplex stainless steel (DSS 2304) was investigated using this equipment due to its microstructure produced by continuous casting process was usually not satisfied. The grain size combined with the position of columnar to equiaxed transition (CET) of DSS 2304 were observed and the results showed these microstructure characteristics were very close to those of the continuous casting slabs. In addition, the influences of pouring temperatures and cooling conditions on the CET behavior were investigated. The results revealed that the length of the columnar grains decreased with decreasing the pouring temperatures and flow rates of the cooling water. Besides, the content of austenite decreases with increasing the distance from the chilled sidewall.IntroductionDuplex Stainless Steels (DSSs) have been widely used in industry for their excellent mechanical strength and superior corrosion resistance in Cl- environments when compared with other stainless steels [1,2]. Their good performances are mostly on account of the duplex phase structure-ferrite (d) and austenite (?) and the high proportion of alloying elements. Although, DSSs have good ductility, but worse formability compared to the austenitics, and this is the key to restrict DSSs application [3]. This is due to the differences properties between the two phases. The hot workability of ferrite (d) is better than austenite (?) and exhibits a lower flow stress during hot rolling processing [4]. The early workers had revealed that coalescent force of phase interface, microstructure, difference of mechanical property between two phases and the precipitations are the main factors affecting the formability of DSSs [5,6]. Another important reason that affects the alloy’s mechanical properties is columnar to equiaxed transition (CET) [7]. It often occurs during continuous casting solidification process and induces inhomogeneous mechanical properties and the microstructure varies with different processing parameters, such as pouring temperatures, cooling conditions (water flow rates in the cooling zones) and casting speed [8]."

Jan 1, 2012

By T. Mason, R. Macko

Electroless nickel (EN) coatings are widely used in the manufacture of automotive parts, providing uniform coating, corrosion protection, wear resistance and lubrication. In contrast to EN plating benefits, the disposal and treatment of waste solutions can cause many difficulties. The use of electrochemical treatment technology greatly improves _the operation of the main wastewater treatment process and reduces operation costs. A new, state-of-the-art job shop in the Chicago area, which provides EN plating for the automotive industry, has installed a large separated electrolytic cell for the treatment of spent EN solution (from dumps and wastewater). The waste/wastewater is handled by the separated electrolytic cell, batch treatment system, filter press and neutralization station. The implementation of modem electrolytic technology and auxilliary equipment provides an effective waste treatment process that meets environmental compliance criteria.

Jan 1, 2000

By Nathan A. Tiner

Sulfuric acid anodizing process is extensively used in many industrial and consumer products to provide corrosion resistance to aluminum alloys. The anodic coatings produced consist of amorphous alhnum oxide with a pornus structure which is easily sealed and colored with dyes. The coatings may contain defects due to surface flaws, canposition and microstructure of the aluminum alloy, and/or due to the anodizing process conditions. This paper will describe the techniques used in anodizing process, various defects which may be produced in anodic coatings and the methods to control them.

Jan 1, 1992

By Honglei Zhang, Wuguo Xiang, Xinhao Huang, Guotao Xu, Xilai Chen

"The service behavior of refractories used in hot air pipeline for hot air stoves in a 3200 M3 blast furnace of WISCO was analyzed. The damage factors can be concluded as the poor quality of and alusite based bricks, the severe thermal shock damage, the more porosity in structures, loose bonding capability, and the unreasonable choice of materials and design of bricks. By analysis, the service life of hot air stoves can be enhanced by the measurements such as the reasonable choice of materials and their match, the use of light-weight refractories, the improvement of brick type, etc. Thereafter, the normal production operation of hot air stoves is guaranteed.IntroductionThe No.7 blast furnace of WISCO has been used for about 5 years and it was mid-repaired in March, 2012. The top phenomena of worn hot air pipelines are brick drop, breakage, severely local wear and deformation, existing hidden danger, so the worn hot air pipelines were renewed. Investigations have been done on the stove damage and design [1,2]. In order to clarify the wear mechanism, the used refractories for hot air pipelines were sampled and analyzed, the properties and structures of worn materials and reused materials are relatively studied."

Jan 1, 2013

By C. A. Morais

The present work describes the development of an efficient and relatively simple process to obtain high grade CeO2 from a mixed rare earth chloride solution. The process involves cerium oxidation and precipitation by addition of a KMnO4-NaCO3 solution. The experiments were carried out at room temperature (25 1° C). The results indicated that the major parameters affecting cerium recovery are the molar ratio of KMnO4/Ce, the initial acidity of the chloride feed solution and final pH of Ce(OH)4 precipitation. In strong acid solutions (pH < 1), the oxidation of Cl to Clo took place in addition to the oxidation of Ce(III) to Ce(IV), so increasing the permanganate consumption. Conversely, low acidity (pH >3) led to coprecipitation of the other rare earth elements. Under the selected conditions, cerium was selectively precipitated as ceric hydroxide, together with some manganese dioxide. Further purification was carried out by the dissolution of Ce(OH)4 in HCl, followed by precipitation as cerium carbonate. The filtrate was neutralised with a Na2CO3 solution in order to recover the associated rare earth elements for further separation. The final product, assaying 99.7 % CeO2, was obtained with a recovery of nearly 100%.

Jan 1, 2003

By Ángel Ruiz-Sánchez

Ethylene glycol additions to aqueous acid solutions for leaching copper sulfides increase both copper and iron extractions compared to a conventional sulfuric acid leach with hydrogen peroxide (H2O2). The role of ethylene glycol is to prevent peroxide destruction, which normally occurs in solutions that contain both cupric and ferric ions. However, despite this improvement, ethylene glycol and sulfuric acid concentrations must be high (3.5 M and 0.7 M, respectively) to obtain satisfactory conversion levels at room temperature. In the present investigation, EDTA was used as an additive to complex the cupric and ferrous ions, lowering the requirements of ethylene glycol and H2SO4 to 0.11 M and 0.007 M, respectively, while minimizing oxidant decomposition. The experimental results for a mainly chalcopyrite, copper concentrate showed complete copper extraction in 24 h at room temperature, with the stoichiometric quantity of EDTA for the copper and iron dissolved. Tests using seawater were equally as successful.

By Jinxing Ji

Several fundamental aspects related to the nickel electrowinning from chloride electrolytes have been addressed in this paper. The thermodynamic study includes the activity coefficient of the hydrogen ion and the speciation diagram of NiCI2 solutions. The activity coefficient of the hydrogen ion (YH+) was calculated and estimated experimentally using a combination glass pH electrode. It was found that YH+ was greater than one in concentrated NiCl2 solutions and increased significantly with increasing NiCl2 concentration. The speciation diagram for NiCl2 solutions was plotted with YH+ and the effect of the ionic strength on the equilibrium constants being taken into account. It was discovered that the predominant nickel species in the acidic region were Ni2+ and NiCI+ in 0.937 M NiCl2 solution at 25°C. Electrodeposition tests demonstrated that higher Nit&apos; concentration in the electrolyte improved the current efficiency of nickel electrodeposition (CENi). The additions of H3BO3, and NH4Cl increased very little the current efficiency of nickel electrodeposition at pH 1.5 and temperature 60°C. However, the addition of sulfate decreased the current efficiency of nickel electrodeposition. Nickel electrodeposition was also found to be a steady-state process since the amount of acid added to the electrolyte at a constant pH increased linearly with time during galvanostatic electrodeposition. The cathode surface pH during nickel electrodeposition was measured using a flat-bottom combination glass pH electrode and a 500-mesh gold gauze as cathode. The cathode surface pH was found always to be higher than the pH in the bulk electrolyte, and if the current density was sufficiently large, it would eventually reach a level causing precipitation of insoluble Ni(OH)2(s) on the cathode surface. Rotating disc electrode studies revealed that the rate of nickel electrodeposition was first order with respect to the activity of nickel ion and zero order with respect to the activities of chloride and hydrogen ions. The rate of hydrogen evolution was found to be first order with respect to the activity of hydrogen ion and to be zero order with respect to the activities of nickel and chloride ions. These findings indicate that nickel deposition and hydrogen evolution proceed independently.

Jan 1, 1995

By Manjie Li, Mingrui Yang, Haijun Peng, Shuxing Qiu, Wei Liu, Shengfu Zhang

It is important to produce and utilize highly reactive coke in order to reduce the energy consumption and CO2 emissions through improving shaft efficiency in blast furnace. The present study aimed to investigate the transformation of iron minerals and properties of iron coke (the coke mixed iron ore fines). Along with the increase of iron ore fines, cold strength displayed a slight downtrend and the pore structure wasn’t inferred to be a major factor affected the properties of iron coke. During carbonization, the majority of mixed iron oxides were reduced to metallic iron by CO and H2 and the degree of metallization achieved to approximately 75%. Nevertheless, produced metallic iron was oxidized by pure CO2 during gasification. Iron coke reactivity index (ICRI) was obviously enhanced and the iron coke strength after reaction (ICSR) drastically decreases, which were also significantly influenced by crystal structure of carbon.

Jan 1, 2015

By I. D. Reznik

On blowing nickel matte in a converter without quartz, first the oxidation of metallic iron and a part of FeS occurs without evolving sulfur dioxide, the formed FeO dissolves in a sulphide smelt and form a homogeneous oxysulphide smelt. On further increasing the FeO content, the oxysulphide separates into 2 layers. Based on the laboratory investigation of FeO-(FeS+Fe°) - (Ni3S2+Ni°) ternary phase diagram we have identified the separation region at 1250°C. The boundaries of the separation region have the form of an arc and the composition of the separated oxysulphide layers is defined by the canodes. In the nickel or copper-nickel matte - silicacalcium oxide slag system at 1250°C three layers, namely sulphide, oxysulphide, and slag may be formed. A high slag basicity due to the presence of CaO can serve to enhance the activity of FeO; a low nickel content in the matte corresponds to a high concentration of FeS therein; FeO from slag and FeS from the matte form a homogeneous FeO-FeS solution, i.e. an oxysulphide layer. The investigation on the "Camebaks" apparatus and by the nuclear gamma-ray resonance spectroscopy method of the phase composition in a slowly cooled oxysulphide layer has shown the presence of four phases: wustite, troilite, ferronickel grains, and calcium oxide-silica inclusions. Knowledge of regularities in the oxysulphides formation makes it possible to use them in pyrometallurgy of nickel and cobalt or preventing their formation.

Jan 1, 1997

By Daniel K. Kim

The charge for the copper refinery is a mixture of anodes produced at San Manuel from BHP source concentrate and copper purchased from external sources. Control of unwanted impurities in the tankhouse - is very important and beneficial. Currently available removal/recovery technologies were reviewed for the control of bismuth and antimony levels in the electrolyte. Recent studies have focused on solvent extraction (SX) technology and generated successful results for the removal and subsequent recovery of bismuth and antimony. The SX system employs the reagent, ACORGA SBX-50, in conjunction with a patented high chloride stripping system. The latter enables recycle of the eluant, avoiding the high costs associated with conventional systems, such as regeneration of resin. Concerns over potential transfer of organics and chloride ion to the electrolyte were readily addressed, solved and demonstrated using conventional, established technology. This paper describes the benefits of electrolyte purification, the flexibility afforded by the SX system, the operational practices necessary for maintaining adequate control of bismuth and antimony impurities in the electrorefining environment and possibilities for future development /exploitation of the Zeneca SX system at the San Manuel refinery.

Jan 1, 1998

By Marcelo B. Mourão

The reduction of iron ores by solid carbon, when both are agglomerated together in the form of pellets, has important kinetic advantages. Although several studies have been performed on the subject, some points on the controlling mechanisms need clarification. There is a big scatter in the values of the apparent activation energy reported in the literature, and this may be due to factors like heat transfer, flow of gases in the reduction system, pellet size and composition. This work is concerned with the effect of several parameters on the reaction rate. The parameters studied were temperature (in the range 1173 K to 1423 K), carbon type (coke or charcoal), pellet size, gas flow rate, catalyst action of the produced metallic iron and added sodium carbonate. It has been shown that the values of the apparent activation energy can change according to the reduction conditions employed, and hence any modeling effort will have to take account of these parameters. EPD Congress 1994

Jan 1, 1994

By Bradford H. Miller

Separation and Recovery Systems, Inc. (SRS) provides on-site waste minimization and resource recovery using its state-of-the-art MX-1500 centrifuge and MX-2000 thermal desorber. The MX-1500 can process over 450 feed tons of material per day, resulting in centrifuged cake containing 20% to 60% by weight. The MX-2000 is a hollow-flite thermal processor indirectly heated by either steam or hot oil. SRS has dewatered and/or deoiled over 1,000,000 feed tons of material in the refining, chemical, and energy industries using the MX-1500. SRS estimates that over 300,000 barrels of reusable oil have been recovered from that material. Additionally, SRS has dried and/or detoxified over 150,000 wet tons of solids or soil to regulatory or customer-specified limits using the MX-2000.

Jan 1, 1994