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By Michael P. Meisel

Solinox is a physical scrubbing process capable of removing a number of noxious materials from off-gasses, especially SO2, hydrocarbons, halo¬gens, heavy metals such as dust, etc. As these materials are dissolved physically, (not chemically bound), the solvent is absolutely stable and no by-products are formed in the scrubbing cycle. The process has been installed in three plants up to now, treating from approximately 30 MMSCFD to approximately 100 MMSCFD. These installations are in a non ferrous metal smelting operation, in a cellulose factory, and in a roasting process.

Jan 1, 1992

By Michael P. Heisel

Solinox is a physical scrubbing process capable of removing a number of noxious materials from off-gasses, especially SO2, hydrocarbons, halogens, heavy metals such as dust, etc. As these materials are dissolved physically, (not chemically bound), the solvent is absolutely stable and no by-products are formed in the scrubbing cycle. The process has? been installed in three plants up to now, treating from approximately 30 MMSCFD to approximately 100 MMSCFD. These installations are in a non ferrous metal smelting operation, in a cellulose factory, and in a roasting process.

Jan 1, 1992

By Jr. Loper, M. H. Kim, H. H. Jo, C. S. Kang, T. S. Song

"An investigation has been conducted to describe the effect of grain refiner (e.g.,Ti) or modifier (e.g., Sr) on the microstructure of an Al-11.3wt%Si alloy produced by the Ohno horizontal continuous casting process using a heated mold so as to obtain directional solidification at high cooling rate of 300 to 2000°C/s. Experimental results demonstrated that the directionality of the primary a grain was promoted by the addition of0.2 to 0.4%Ti or by the addition of0.02%Sr, whereas the addition of0.6%Ti suppressed this directionality. Feathery a grains were promoted by the addition of 0.2%Ti, while these feathery a grains were suppressed when over 0.4%Ti (grain refinement) or when 0.02%Sr was added. The addition of Ti also resulted in increased coarsening of the eutectic Si in these Al-1 l.3wt%Si alloys.IntroductionThe mechanical properties of conventionally cast Al-Si alloys can be enhanced through judicious control of the casting parameters, by the addition of grain refiners (e.g., Ti) and by the addition of eutectic modifiers (e.g., Sr).[1-3] The Ohno continuous casting process[4-5] uses a heated mold (maintained at a temperature above the alloy liquidus temperature) to produce a casting with a mirror surface free of shrinkage defects. The process is especially suitable for the production of high quality and non-deformable rods of small diameter. This study was conducted at investigate the effects of Ti and Sr on the microstructure of Al-1 l .3wt%Si rods cast by the 01).no process."

Jan 1, 1998

By Dai Xi

In the present work, the viscosities of molten FenO-MgO-Si02 and FenO-MgO-CaO-Si02 semi-synthetic slags for nickel flash smelting were measured in the temperature range from 1473 to 1723K by a rotational viscometer. The ratio of Fe to Si02 was fixed at 1.2, calcium and magnesium oxide contents varied in the range from 2 to 8 mass% and 9 to 12 mass%, respectively. The results showed that silicate anions became smaller by increasing CaO content, which results in a decrease of the viscosity of the slag. In the case of MgO addition the viscosity behavior was complicated. At MgO content below 11 mass%, the viscosity increased with the increase of MgO at all temperatures tested. However, when the MgO content was above II mass%, the viscosity decreased slightly for FenO-MgO-CaO-Si02 system. At higher MgO contents, low-viscosity slags can be obtained by adding CaO. At a given composition, the viscosity decreased with increasing temperature. The higher the temperature, the more MgO can be added before saturation. The effect of Fe304 on the viscosity was quite significant. The viscosity of slag increased by 300mPa's at l573K when Fe304 content varied from 3 to 9 mass%. The viscosity values are presented as the functions of temperature and composition. A comparison between FenO-MgO-Si02 and FenO-MgO-CaO-Si02 systems is given in this study.

Jan 1, 2003

By Guojun Ma

The entrainment of charge materials, evaporation or volatilization of elements and ejection of slag and metal by spitting or the bursting of gas bubbles are mechanisms whereby stainless steel plant dust are generated from the electric arc furnace and refining converter. TCLP and ASTM D 3987-85 tests on dust that was collected from the baghouse filter system of a South African Stainless Steel plant showed that this dust can be considered hazardous according to South African legislation, due to the high degree of Cr (VI) leachability (~13mg/l for TCLP and ~8mg/l for ASTM vs. regulation threshold of 0.05mg/l in drinking water). The dust is therefore considered to be harmful to both the environment and human health, due to its high solubility in water and carcinogenic properties. It should therefore be treated before being stockpiled or land filled. This paper consequently describes an investigation into the formation of Cr(VI)-containing stainless steel plant dust and the stabilisation thereof in a sintering process, whereby the dust was mixed with a silica-rich clay. It is postulated that Cr(VI) form when the (Mg,Fe,Mn,Cr)3O4spinel phase, CaO, Ca(OH)2 and CaF2 (all of which are present in the dust) react. This reaction was found to take place both at ambient and at high temperatures (1100°C). Stabilization of Cr(VI) in the dust could be achieved at an optimum sintering temperature of 1100°C for a 50mass% dust : 50mass% clay mixture. Chromium emission during the sintering process was found to be low, and within environmental limits.

Jan 1, 2006

By Hideyuki Takahashi, Taro Aichi, Kazuyuki Tohji, Makoto Muramatsu, Rie Sato

"There are several ways to condition lead-based alloy anodes for zinc electrowinning: electrochemical treatment, chemical treatment and physical treatment. Two advantages of physical treatments are their productivity and variety. In this report, physical treatments, including blasting with silica, alumina, steel grit and cut zinc wire, were tested. The laboratory tests confirmed there were differences in the formation of anode scales during electrowinning and in the suppression of lead dissolution from the anodes. With an increase in the surface roughness, the misfit between the PbC""2 and the MnC>2 was mitigated and the anchor effect was promoted; these effects resulted in dense Mn oxide scales on the anode.IntroductionZinc is widely used for hot-dip zinc plating and for die casting alloys. As a supplier of materials, we have endeavored to produce zinc that is economical and contains as little impurity as possible. As a result of our efforts, a technology for consistently providing special high-grade (SHG) zinc has been established. However, as seen in the issuance of the Restriction of Hazardous Substances (RoHS) Directive, public awareness of the industrial impact of heavy metals on the environment has been heightened. Increasing efforts to control environmentally sensitive substances will be necessary for our production processes.Electrolytic SHG zinc is produced by electrodeposition in an acidic solution with a Pb-Ag or Pb-Ag-Ca alloy for the anode and an Al alloy for the cathode. Pb alloy anodes are widely used because of their excellent durability; however, they are a source of Pb, which is the main impurity of the product."

Jan 1, 2012

By Ladislav Bebar, Tomas Parizek, Radek Dvorak, Petr Stehlik

"More and more sweeping environmental regulations initiate research, development and introducing into operation up to date technologies for cleaning off-gas and flue gas generated in various branches of industry and municipal waste treatment. The following systems based on novel types of equipment are shown: thermal and catalytic treatment of waste gases polluted by VOC (Volatile organic compounds) and carbon monoxide (alternatively NOx), catalytic filtration for efficient destruction of PCDD/F (dioxins) and potentially NOx, wet cleaning of flue gases polluted by SO2, HCl and HF with a original type of homogenizer “O-element”, integrated equipment for cleaning waste gases polluted by solid particulates, SO2, HCl, HF and heavy metals (alternatively NOx or PCDD/F). The outstanding features of all equipment mentioned above are low investment and operating costs together with high removing efficiency of pollutants. These units can be used mainly in incineration plants, refineries and other chemical plants. The paper represents a review based on papers published in reputable international journals and a monograph under preparation as well as on experience from industrial applications.IntroductionIn the recent years, more and more emphasis is put on preserving clean environment. One of the most closely monitored objects of general public attention are exhaust gases, containing a number of undesirable compounds like NOx, CO, SO2, HCl, HF, fly ash a PCDD/F. These harmful species are created in chemical processes mainly in the industry, transport and energy sectors. There is therefore a strong impetus for abatement of these harmful pollutants. Sectors of industry are thus subject to emission regulations specific to various types of units. In the framework of increasing demand for a clean environment, the concerned legislation is becoming increasingly strict and requires removal of pollutants by modern methods that would ensure efficient abatement of emissions at reasonable investment and operating costs.Attention is focused chiefly on methods for decreasing harmful emissions from thermal waste treatment facilities processing industrial and municipal waste that may be subsequently applied in other sectors of industry. Units for the thermal treatment of waste not only provide means of its disposal, but may become also important sources of energy, provided that strict emissions limits are satisfied. Figure 1 compares emission limits given by the legislation for municipal waste incinerators and limits for a selection of energy sources with heat capacity up to 50 MW (see EU regulation 200/76/EC). The Figure implies that the values of emission limits for waste incineration are mostly comparable with emissions from the combustion of natural gas. Thanks to the continuing improvements of the methods for removal of harmful pollutants, the emissions from waste incinerators are typically deep below the limits."

Jan 1, 2008

By Xi-Shan Li, Qian Li, Yong-bin Yang, Li-na Cui, Tao Jiang, Jie Ge

"With regard to control environment pollution in the roasting pretreatment of sulfur & arsenic-bearing gold concentrate, roasting of double-layered pellet was proposed. In the paper, the characteristics of double-layered pellet roasting were studied. Removal and solidification rates of sulfur and arsenic were investigated as primary factors. The result indicated that the removal and solidification rates of arsenic reached up to 95.91 % and 98.95% while the sulfur was 97.19% and 97.90% respectively on the premise of adopting slaked lime as solidified agent at temperature of 6000, the package proportion of 2.14 and roasting time of 3h. However, pyrite and arsenopyrite were transformed to hematite and magnetite and product of solidification mainly consisted of calcium sulfate, calcium arsenate and calcium sulfite within optimum roasting parameters.IntroductionUtilization of refractory gold resources has been gradually concentrated on with the depletion of the gold resources which are easy to deal with in the world [1]. Sulfur and arsenic-bearing gold ore is a typical refractory gold one, in which ultrafme gold is encapsulated in the structure of metal sulfide minerals [2,3], so it gives poor recovery through direct cyanide leaching. These refractory ores need pretreatment before the process of cyanide leaching to undermine lattice structure of pyrite and arsenopyrite containing gold [4] so that the gold could touch with cyanide solution [5]. Among various methods of pretreatment, conventional roasting method is most effective, but this process generates gases such as S02 and As203 harmful to environment. Therefore solidification roasting was proposed to solve this problem occurring in the conventional roasting at the end of last century."

Jan 1, 2013

By Jian Wang, Hongyang Cao, Binxiu Wu, Junhong Li, Jimin Wang

"The enrichment and separation of scattered metal indium component in the pressure leaching solution with sulfuric acid from vacuum furnace germanium slag were studied by iron substitute and P204 extraction, which is supplied by shaoguan smelter. The experimental results show that the extracting power of P204 for indium from pressure leach solution is powerful. The optimal technological condition were the ratio of P204 and sulphonating serosene 3:7, phase ratio 1:3, solution pH 1.2, and extracting 5 minute. The enrichment indium solution of 21.7 g/L In at 95.2% recovery ratio was obtained by three-stage counter flow extraction and four- stage counter flow stripping.IntroductionScattered metals, such as Indium and germanium, were inriched as intermediate product or by-product during the metallurgy process of other non-ferrous metals, such as lead, zinc, copper and tin. For example, the indium and germanium were inriched in vacuum furnace germanium slag, which is the by-product of zinc vacuum distillation operation from hard zinc. It is difficult to recovery the indium from the vacuum furnace germanium slag, because the indium content is low, and the chemical composition and phase compositon were complex.Recovery indium from bearing indium zinc slag was researched extensively, such as pressure acid leaching, high temperature evaporation, solvent extraction method[l-7], acid leaching method has the advantages of high leaching rate, which can be separated hydrochloric acid, sulfuric acid and silicon fluoride acid systems. Solvent extraction method has the advantages of low production cost, fast reaction speed, high enrichment ratio, and simple operation."

Jan 1, 2013

By Lijuan Li, Xin Xia, Junjun Huang, Qijie Zhai, Xiang Jiang

"Some experiments with different temperatures (1173, 1223, and l273K) and different annealing times (3, 4, 5, 6min) were carried out on cold-rolled plate of Fe-36Ni invar alloy. The microstructure and the mechanical properties were observed and tested respectively, and the fracture morphology was observed by SEM. The results show that with increasing of the temperature and the annealing time, the austenite grains gradually grow up accompanied by a small amount of annealing twin crystals, meanwhile, its plasticity and toughness are improved, and it is typical ductile fracture under the condition of tensile failure. After annealed at l223K, the invar alloy has better comprehensive properties than that at the other annealing temperatures, and the grains size is more uniform. Furthermore, when the annealing time is 4min, the invar alloy has the best comprehensive properties.IntroductionAs we known, most metals and alloys expand with increasing temperature. More than one hundred years ago (in 1897), Guillaume observed that Fe-Ni alloy with face-centered cubic (fcc) crystal structure, consisting of36%Ni, showing a very small thermal expansion coefficient below the ferro-to-paramagnetic transition, the thermal expansion coefficient around room temperature( <2 X 1O-6K-1 compared to most metallic materials which have a thermal expansion coefficient of 10-20 X 1O-6K-1) [1,2]. Since then, the subject has attracted many researchers, and various alloys with low thermal expansion coefficients have been developed. These alloys, generally known as ""invar alloys"", are in demand where dimensional changes due to variation in temperature must be minimized and where high stability is required [3, 4]."

Jan 1, 2012

By L. H. Lewis

The relationships that link microstructural properties of advanced permanent magnet materials with magnetic properties such as the coercivity are often difficult to quantify, especially in materials with nano-scale structures. Recent work on RE2Fe14B-based powders fabricated with rapid- solidification techniques such as inert gas atomization (IGA) and melt-spinning provide insight into the nanostructural features which affect the acquisition and stability of coercivity. In all cases the coercivity is found to be a function of both the scale of the constituent microstructure and of the presence and distribution of minor phases.

Jan 1, 1997

By H. H. Law

Large amounts of waste material in the form of flue dust are generated in the operation of copper smelter furnaces. As a result of increasingly stringent disposal, it has become important to develop methods for treating such metallurgical wastes to extract metals and convert them into salable products. A two-step closed-loop hydrometallurgical process, has been developed: (1) extraction with sulfuric acid removes about 90% of zinc and decreases the dust volume by 50%; (2) extraction with hydrochloric acid dissolves the lead and further decrease the dust volume by 75%. A process scheme for generating salable products is proposed.

Jan 1, 1992

By Zviad Kovziridze

It is stated that the specific character of SPHTS specimens of TiCx consists in crystal lattice strength reflecting the condition of synthesis in ?burning wave?. The use of roentgenographic and other methods of analysis allow to estimate the effect of the conditions of synthesis causing the carbon sablattice defect on the grinding intensity of TiCx -phases. The study of the kinetics of vibratory grinding of TiCx -phases in ethanol and benzene medium allows to establish high grinding intensity of the phases close to stoichiometry and the possibility of producing high dispersion powders (Ssp 4.5-6 m2/g).

Jan 1, 2006

By Jamil M. Khalifeh, Shadia J. Ikhmayies, Bothina A. Hamad

"The structural and electronic properties of cubic d -NbN are investigated using density functional theory (DFT) and all-electron full potential linearized augmented plane wave method (FPLAPW). The equilibrium structural parameters are determined by fitting the total energy as a function of volume to the Murnaghan's equation of state. We calculated the total and partial densities of states (DOS) and compared them with those computed by different authors. Our DOS at Fermi level is found to be very close to the experimental value. The band structure is computed, discussed and used to find the characteristic energy separations. Valence electron density contours are recorded and discussed. We deduced the partial charge densities of different bands and binding energies of valence core levels and compared them with experimental and theoretical results obtained by different authors.IntroductionNiobium nitride has been intensively investigated over the last decades because of its interesting physical properties and technological applications (superconducting microdevices, microelectronic, catalytic probes, and hard coatings) [l]. While the group IV transition metal nitrides (TMN) mainly crystallize in the cubic NaCl structure (Bl type), those of group V and VI nitrides occur as different phases. Thus for niobium nitride, many phases have been reported in the literature: cubic fcc d -NbN, tetragonal ? -Nb4N3, hexagonal d -NbN, hexagonal e -NbN, and low nitrogen content hexagonal ß -Nb2N [l, 2].Structural and electronic properties of niobium nitride were investigated theoretically and experimentally by many authors. For example, in 1975 Schwarz [3] obtained the partial density of states for NbC and NbN from APW band structure calculations. In 1975 Kallne and Pessa [4] studied the electronic structure of Nb, NbC and NbN by using X-ray emission. In 2003 Amriou et al. [5] studied the electronic structure and bonding mechanism of NbC and NbN compounds using first principle total energy calculations using the full-potential linearized augmented plane wave method. Also in 2006 Sanjines et. al [l] studied the electronic structure of the hexagonal~Nb2N, hexagonal' d -NbN, and cubic d -NbN thin fihns by using X-ray photoemission spectroscopy. They [l] also calculated the densities of states for these phases and used them in the interpretation of the experimental valance band spectra. Most of these studies are old and there is a need for more recent studies. According to our knowledge, there are little comprehensive theoretical studies on this subject by using FP-LAPW method [5], which proved its ability to give accurate results. In this work we used the FP-LAPW method to study the structural and electronic properties of the cubic (fee) o-NbN (space group Fm-3m, prototype NaCl) crystal."

Jan 1, 2013

By Wenbo Luo, Jilai Xue, Tiepeng Li, Jun Zhu

Sodium silicate solutions for producing silica have been ultrasound treated to enhance the precipitation process in laboratory scale. Higher precipitation rate was found with ultrasound treated solutions than those without ultrasound. The obtained SiO2 powder products were characterized using XRD, SEM, BET and laser particle size analyzer. The particle size distribution and the specific surface area of the powder products varied with the power input level and the processing time of the ultrasonic treatment. The results indicate that the efficiency of the precipitation process can be improved optimally when the ultrasound is conducted into the solutions before the nucleation stage.

Jan 1, 2015

By Kliment Y. Hakobyan

A new technology for treating molybdenum sulfide concentrates has been developed. It includes roasting the concentrate in a special regime with water vapor, cooling and neutralizing exit gas, oxidation roasting of rhenium containing MoO2, and the extraction of rhenium from exit gases. This technology allows economically efficient and environmentally safe processing of molybdenum concentrates: The degree of molybdenum extraction is 98.8%, rhenium-90%, sulphur-98.4%. The technology also ensures high extents of extraction of selenium and tellurium as well as the fixation of sulfur in the form of sodium sulfide or elemental sulfur.

Jan 1, 2006

By B. G. Belew

Recent operating improvements at the Phelps Dodge Chino Smelter, coupled with intensive capital expenditures since 1987, have resulted in a safer, higher quality, more productive smelter. This paper briefly reviews the flowsheet of the Chino Smelter with emphasis on recent capital expenditures. The main focus of the paper is to provide case studies of how operating functions have been improved. Case studies presented include: (1) safety, (2) anode quality control, (3) flash furnace cross-over build-up control, and (4) flash furnace temperature control. Most of these accomplishments have been achieved by providing specific measurable goals and subsequent feedback to operating crews.

Jan 1, 1993

By F. Ríos

Fundamental research, at laboratory scale, on the biomass adsorption capacity of a liquid mining effluent has been done. The biomass used corresponds to a Chilean seaweed called Gracilaria chilensis. The waste water effluent corresponds to clear water coming from thickeners of a Chilean copper mining operation. The biomass was dried, washed, treated with an acid solution, and then reduced in size. A characterization of Zeta potential was made, finding negative values in a wide pH range with a ZPC equal to 2.5 1. Adsorption tests were made- in an agitated system containing an artificial solution of CuS04 at a controlled temperature of 25 degrees Celsius; also, the effect of pH over the copper adsorbed was studied. Maximal adsorption of copper was found at pH equal to 6, and the Langmuir model indicated values for saturation of 52.08 mg/g and for standard free energy of about -21 KJ/mol. Kinetic adsorption was very high and fitted very well with a second order model equation, finding that 90 per cent of the adsorption occurred during the initial 10 minutes. After stoichiometric when 1 mol of copper is adsorbed, 2 mol hydrogen are released, showing that the main mechanism to remove heavy metals is the ionic exchange, and the seaweed ensures total discharge of copper adsorbed when the pH value is about 1. Experiments done with real waste water from thickeners lead us to conclude that optimal results for copper and molybdenum adsorption are at pH around 3.25 and the remaining treated water may be partially discharged into the water currents, thus showing that Gracilaria chilensis can be used to remove heavy metals easily from liquid effluents in the copper mining industry.

Jan 1, 1999

By D. T. Smith, L. M. Hsiung, J. J. Schmitt, J. W. Golz, R. L. Lankey, H. N. G. Wadley, J. Z. Zhang, B. L. Halpern

"The microstructure and mechanical properties of Al/AI2O 3 metal-oxide nanolaminates fabricated by' a novel Jet Vapor Deposition (JVD) process at substrate temperatures of ~25° and -250°C have been investigated using transmission electron microscopy (TEM) and nanoindentation methods. The thickness of the oxide layer was held constant between 2 and 5 nm, whilst the Al layer thickness was systematically varied from -3 to -50 nm. Continuity of the Al layers was significantly improved when the nanolaminates were deposited at an elevated substrate temperature (-250°C). The yield strength of the nanolamintes with Al layers greater than -25 nm follows a Hall-Petch type relationship, whereas that of the nanolaminates with Al layers less than -25 nm is better predicted by a Koehler-Lehoczky strengthening model. IntroductionAluminum-aluminum oxide (presumably A12O3) nanolaminates have been recently fabricated using a novel Jet Vapor Deposition (ND) process developed and patented by Jet Process Corporation [1-4]. ND uses sonic, high purity helium (He) gas jets to entrain atomically dispersed vapor and deposit films. It is of interest here because it can deposit multilayered structures (laminates) inexpensively at high rates. Materials with a thin, multilayer structure are of interest because they potentially offer novel mechanical and physical properties [5]. Koehler in 1970 used an image force model to investigate the strength of laminated materials and proposed the use of alternating layers of high and low shear modulus metals to produce high strength composite materials [6]. He predicted that dislocations would have to overcome a large repulsive image force in order to move from metal layer B of lower shear modulus (uB) into metal layer A of higher shear modulus (uA)' The image force (F) is given by the relation:"

Jan 1, 1994

By Dean G. Heitt

"The Rain and SMZ mines from 1987 to 1994 produced a total of22.0 t of gold from a pre-mine reserve of 14.24 Mt of ore grading 2.13 g/t Au.Gold at Rain is hosted within the basal portion of the Mississippian Webb Formation. ·Mineralization is closely tied to the Rain Fault which is interpreted to be the main feeder for the deposit. Multiple collapse and hydrothermal breccia events provided permeability for the mineralizing fluids in the otherwise unreactive siltstones. Major alteration events include: decalcification and dolomitization of the Devils Gate Limestone; and silicification, baritization, argillization and oxidation of the Webb Fm. Six ore types based on XRD and visual rock chip Jogging have been identified: siliceous ore containing >40% quartz and <30% barite; siliceous-baritic ore containing mostly silica but >30% barite; baritic ore containing >40% barite; argillaceous ore containing >40% total clays (including alunite); calcareous ore containing mostly calcite and dolomite; and carbonaceous ore which has significant pyrite and organic carbon. Metallurgical testing of the oxide leach grade ores found that recoveries, on -1.3 cm crushed material, were greater than 70%. Results also found that Rain ore has strong grind dependency due to silica encapsulation.The Rain leach pad was commissioned in 1988, and to date 9.3·Mt at an average grade of0.65 g/t Au have been placed. Life to date recovery, through December 1995, is approximately 51 %, for a total of3.87 t of gold produced. Two major factors have contributed to the low leach recoveries at Rain when compared with the metallurgical testing: 1) More argillaceous ore than expected was placed on the pad especially late in the mine life and 2) approximately 50% of the tons placed were run-of-mine with no agglomeration."

Jan 1, 1997