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By Guo Chen, Jin Chen, Jinhui Peng

In this paper, solving common problem of electrostatic precipitator (ESP), which was frequently ruptured of the cathode insulation in the production process were studied. The microwave heating airflow technology was introduced, which takes full advantage of its unique properties, solves the output problem of the high temperature air, achieves purpose of energy conservation, important economic significance and environmental significance. The mathematical models and designing of microwave high-temperature hot air system was calculated. The common forms of heat exchangers and comparative analysis were also introduced. The conditions found to be at the temperature of 240 °C. Under optimum conditions, the microwave heating power was 1482 W. Based on the mention results, this microwave heating method can be applied effectively and efficiently way for the production process of electrostatic precipitator.

Jan 1, 2015

By L. S. Montagna, R. M. C. Santana

"Since the industrial revolution, plastic products sector has growing bigly, however this fact presents as consequence the increase of municipal plastic waste (MPW).The aim of this work is to developmet polymer mixture from MPW with the adittion of rubber tire (TR) post use and to study the mechanical and morphologycal properties. The polymer mixtures Polypropylene/High impact polystyrene/TR (PP/HIPS/TR), where rate weight TR used was 10, 20 and 30 % and with three size particles (500, 710 e 1000 µm). The specimen tests were obtained by injection molding. Preliminary results of mechanical properties showed that the increase of TR influence in a reduction of the flexural and tensile resistance. Results by scanning electronic microscopy on the fracture surface of mixtures PP/HIPS/TR showed a better interaction of TR particle with HIPS than with PP. Also, the presence of microcavoids was observed, characteristic in PP/HIPS blends, favouring in the increase of its opacity.IntroductionOne great part of the municipal solid waste (MSW) is composed of polymer mixed since commodity plastics, blend to polymer composite. The processing of plastics mixtures for recycling has been attempted with some success, but poor mechanical properties and uncertain economic value limit their more versatile reuse. Polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), poly(vinyl chloride) (PVC) and polystyrene (PS) are among the most common plastic waste, predominantly used in packaging food industry [1].One other problem that preoccupy to the society is the increase of rubber tire waste in the proportion of MSW. In Brazil, from 1999 to 2004, 39 % from 386 mil ton of tire post-use were destined to ciment Industry as source of energy [2]. However this destiny produces one other problem, environment pollution, due to gas mixture emitted.Recycling represents a valid alternative to the disposal of post-consumer plastics in common landfills if it is possible to obtain new materials with good final properties compatible with practical and, above all, by cheap methods [3]The reutilization of group tire rubber (TR) powder as a dispersed elastomeric phase in a thermoplastic matrix offers an opportunity to design second generation materials which would be recyclable due to the thermoplastic matrix and which potentially could present thermoplastic elastomer (TPE)-like mechanical behavior. [4]."

Jan 1, 2008

By David Tisdale, Phillip Mackey, Nagendra Tripathi, Matthew Kreuh, Pascal Coursol

Xstrata Nickel’s Sudbury smelter operation is based on fluid bed roasting of Ni-Cu sulphide concentrate, followed by electric furnace reductive smelting and Peirce-Smith converting to produce a Bessemer matte for electro refining, along with sulphuric acid produced from smelter gas. While the site dates back to the 1930s, the present smelter configuration has been operational since 1978, and currently has a nominal capacity of about 67,000 tpy of contained nickel and is investigating options to expand in future up to 85,000 tpy. As part of a review of plant capacity options, a new metallurgical model of the plant was developed in order to examine a number of processing alternatives. Based on the METSIM™ platform, the present model includes the ability to examine the impact of a number of plant parameters on potential plant performance including; for example, the following: percent of sulphur elimination in roasting, matte grade, degree of matte metallization, temperature, coke requirements, sulphuric acid production, CO2 emissions and overall energy requirements. The process model also includes a number of special features adopted; for example, approaches to effectively model the complex Ni-Cu-Co-Fe-S-O matte system. This paper provides a description of the model and gives an overview of the results. As well as presenting the results of the present study, the applicability of this modeling approach to pyrometallurgical systems in general is also briefly discussed in the paper.

Jan 1, 2009

By Michael D. Odekirk

The U.S. Bureau of Mines investigated solvent extraction methods for recovering scandium from water leach filtrates of sulfated tantalum tailings. These complex solutions typically contained 20 or more metals in significant quantities. Two commercially available organics, DEHPA and PC-88A, were identified as effective scandium extractants. The two organics were tested in continuous solvent extraction circuits to compare loading and stripping kinetics, recyclability, and general processibility. Results showed that 95 pct of the scandium, greater than 80 pct of the zirconium, and only small amounts of other solubilized metals were extracted. Scandium was stripped directly as a 3.6 pct Sc precipitate when a 3n NaOH liquor was used as the stripping agent. This precipitate was subsequently upgraded to 94 pct ScE3 via a selective HE leach.

Jan 1, 1993

Plastics recycling has become an established national industry in Korea. However, it is still in its infant stage and experiences growing pains. In Korea, mixed plastic wastes generated from households after hand picking and/or mechanical sorting processes amount to 1,700,000 ton per year in 2005, and most of these waste are finally end up with landfill and/or incineration due to lacks of separation technologies and economical reasons. These plastic wastes can not be used as raw materials for chemical and/or thermal recycling because of their high content of PVC (upto 4.0 wt.%). In the present work, gravity separation system has been developed to remove PVC from the mixed plastic waste and recover the individual plastics. The separation system mainly consists of air classification, crushing, feeding system at fixed rate and wet-type gravity separation system. The gravity system based on centrifugal separation also consists of mixing, precleaning, separation, dewatering, recovery system, wastewater treatment system, etc. The main objective of this process to be developed is to achieve high separation efficiency of polyolefins (PE, PP, PS) with less than 0.3 wt.% PVC content and less than 10% moisture content in the final products. The system with a capacity of 0.5 ton per hour is developed and operational results are presented.

Jan 1, 2006

By Veneta Groudeva

A pyritic ore containing zinc, lead and copper as? the relevant primary sulfide minerals, .as well as gold and silver finely disseminated in the sulfide matrix, was? leached in percolation columns. Each column contained 30 kg of ore crushed to minus 10 mm. Firstly, zinc and copper were efficiently leached by means of chemolithothrophic bacteria? in acidic sulfate bearing medium. Zinc was leached more rapidly than copper but the final extractions of these metals were similar (about 75% in 300 days). A part of the galena was oxidized to the. insoluble lead sulfate during the leaching. The pyr:ite was, however, relatively slightly attacked. The ore was then leached by means of FeC11 - HCl solutions both in the presence and in the absence of bacteria to solubilize the lead. The chemolithotrophic bacteria grew in media containing both chloride and sulfat~ ions and maintained a high ferric to ferrous ion ratio in the percoiating solutions. The chemical leaching was, however, more efficient since ft was possible to carry it out at higher chloride ion concentrations. About 10% of the lead was leached in this way in 90 days. Finally, the ore was leached by thiourea in the presence of a gold-oxidant (oxone) to extract the gold and silver. Over 60% of the gold and over 55% of the silver were extracted from the ore in 150 days, while. the extractions of these precious metals from an untreated ore sample were lower than 25%.

Jan 1, 1991

By O. G. Rivera, R. D. Moser, P. G. Allison, W. R. Whittington, P. Rivera-Soto, Z. McClelland, D. Francis

This research examined the evolving microstructure of quasi-static and dynamically loaded fully annealed metastable 301 austenitic stainless steel (SS). Experiments were performed to an interrupted strain value of 20% and to failure using a tension Kolsky bar (1000/s) and an electromechanical load frame (0.001/s). Electron Backscatter Diffraction (EBSD) identified the microstructural evolution from the as-received condition to the 20% strain level for the high and low rate interrupted samples. This material achieved over 60% elongation to failure with increasing strength as strain rate increased, as expected. Fractography analysis using SEM showed particles in the microstructure and a ductile failure mode. The 301 SS exhibited a greater amount of phase transformation from parent austenite to -martensite at the dynamic strain rate when compared to the quasi-static strain rate during the interrupted experiments. This result is indicative of the increased propensity for austenite to -martensite phase transformations at the high strain rate.

Jan 1, 2016

By A. J. Paul

Traditionally, 16"/50 caliber projectile shells have been fabricated from forged steel. The Naval Surface Warfare Center (NAVSWC) has determined that cost savings of approximately 60% (-$4.7M/year) as well as improved shell fragmentation can be achieved by casting these shells from austempered ductile iron. One of the technical concerns arising out of this material substitution is the role of the casting process in controlling the quality of the cast shells. Optimizing the process through proper orientation of the mold, placement of chills, superheat, etc., can minimize shrinkage porosity and, consequently, flaw size. For this purpose, the mold filling and subsequent solidification of the projectiles was simulated using a 3-D, fully transient, coupled fluid flow and heat transfer model based on finite differences. Several casting orientations were investigated and the casting parameters were varied to optimize the process and minimize casting defects. A comprehensive software tool, which was developed using state-of- the-art visualization techniques, has been used to analyze the process of casting. Emphasis is placed on the use of this visualization tool as an aid to the foundry engineer for process optimization.

Jan 1, 1992

By C. G. Anderson

Throughout the world, there are many orebodies or materials which have significant value but also contain arsenic. As regulations on the transport, exposure, disposition and emission of arsenic have become more stringent; it has become increasingly more difficult to derive the values from these resources. This paper will outline the fundamentals of alkaline sulfide hydrometallurgy and its successful application to arsenic bearing ores, concentrates and materials.

Jan 1, 2005

By Chao Lian, Hongxu Li, Hao Bai, Wei Wei

"Application of high-emissivity coating on inner walls in industrial furnaces increases the furnace thermal efficiency. The coating with high emissivity strengthens radiation heat transfer in the furnace, however, according to Wien's displacement law and Planck's radiation law, under heating temperature, the wavelengths of the radiation transfer are mostly between 1-5 µm, implying that increasing emissivity of the coating in near infrared band is more effective for higher thermal efficiency. In this paper, a new CuO-ZnO-based coating material sintered at 1600K was developed. The emissivity of the samples were measured and the result shows that, in near-infrared band, the emissivity of the sample reaches 0.98 at 773K with 13at.% of CuO doped in ZnO. In addition, the effects of CuO doping and use temperature on emissivity were also discussed. Furthermore, crystallization behaviors of ZnO-CuO sintering were investigated by DTA,XRD and SEM-EDS etc., which offered information for possible optimal design of the material.1. IntroductionIndustrial furnaces are widely used in various industrial heating. For example, the metal smelting furnace, ore sintering furnace in metallurgical industry; the distillation furnace, cracking furnace in petroleum industry etc,. The research on efficient energy saving technology has important significance. High emissivity coatings are widely used in many high temperature applications to effectively transfer the heat by radiation [ 1]. The theoretical calculation and experimental studies have shown that, coated high emissivity coating in the heating surface is an effective method to enlarge the infrared radiation power [2].At present, the infrared high emissivity coating has been widely used in China, and have been achieved remarkable energy saving effect. According to Wien' s displacement law and Planck' slaw, most energy of the black body at high temperature is radiated in the wavelength range of l-5µm; however it happens that many materials have the low emissivity within this range. Thus, it is important to improve the near-infrared band emissivity of materials [3]."

Jan 1, 2013

By M. K. Yelloji Roa

Effect of conditioning with Thiobacillus ferrooxidans on the floatability of sphaierite and galena has been determined in this work. The flotation behavior of the conditioned minerals clearly shows that such bacterial conditioning does produce marked modification of their surfaces. The variables affecting the surface modification and thereby the flotation response of the minerals were found to be cell concentration used for bacterial conditioning, the period of biotreatment and the pulp density. Importantly, while the enhancement in flotation obtained due to sulphuric acid treatment was retarded by biotreatment in the case of galena at all cell concentrations due to electrochemical effects, such decrease occurred in the case of sphalerite only at cell concentration sufficiently high for their attachment to the mineral surface. The effect of bacterial conditioning has significant implications to the differential flotation of sphalerite and galena. Mechanisms responsible for the modification of the surface properties of these sulphides due, to bacterial conditioning are discussed.

Jan 1, 1991

By Andre L. De Vegt

For the past eight years Paques has been engaged in the development and installation of treatment systems based on biotechnological processes to remove sulfur compounds from water, air and gaseous streams. Metal and sulfate can be removed from mine waters using two biological steps: 1. Sulfate reducing bacteria convert sulfate to hydrogen sulfide (HzS). The HzS reacts with the dissolved metals to form insoluble metal sulfide precipitates. 2. Sulfide oxidizing bacteria convert excess H2S to elemental sulfur. Paques has designed and installed a groundwater treatment system for the Budelco zinc refinery in the Netherlands to remove metals and sulfate as described above. The system has been operating since May 1992 treating a flow of 5000 m3/d. A test program, utilizing a large scale pilot plant, will commence in November 1995 at a copper mine in the U.S.A. to remediate groundwater contaminated with sulfate and heavy metals. Biological reactor performance and selective metal recovery will be studied. Sulfur dioxide (S00 can be removed from fluegas using a combination of scrubber technology and the two biological steps. The end product is elemental sulfur. A commercial size biological desulfurization plant has been in operation since July 1994 treating 50,000 Nm3/h of fluegas. Sulfide can be removed from mining waters or anaerobic wetlands using a THIOPAQ® Sulfide Oxidizing reactor.

Jan 1, 1996

By Ross Baldock, Ross Andrews, Gu Helin, Lan Xu, Markus Reuter, Song Xingcheng

"A commercial lead smelter using Outotec Ausmelt TSL Technology has been successfully commissioned and put into operation at Yunnan Tin Company Ltd operations near Gejiu City, in Yunnan Province, China. The plant was commissioned in July 2010 after three years in the design and construction phase. The process uses a three stage batch process to produce lead bullion and zinc fume, and a slag that is low in metal values. The paper provides details of this lead smelting project, including the theoretical evaluation of the multi-stage process chemistry, engineering design, plant commissioning and the final operation. Comparison of the design targets and actual performance of the plant is emphasized. The fast ramp-up to full production of the largest Ausmelt TSL lead furnace built to date is highlighted.IntroductionIn 2002, Ausmelt and Yunnan Tin Company (YTC) successfully commissioned a smelter to modernise the Yunnan Tin smelter in Gejiu City, Yunnan Province, China. A single Ausmelt furnace was installed by YTC to process tin concentrate and revert materials, to produce YT Brand tin product. The advanced Ausmelt Technology furnace at YTC replaced seven existing reverberatory furnaces and provided a flexible, energy efficient and environmentally beneficial system to complement the world leading refinery facilities of YTC."

Jan 1, 2012

By Antonio Huerta

The effects of potassium ethyl xanthate collector and potassium dichromate used as a depressor on a PbS mineral were studied by high frequency impedance technique. Measurements of complex permittivity, at 100 MHz suggested that is possible to obtain from isotherm adsorption the adequate industrial collector concentration being this in the range of lE-3 to 5E-3M of KEX. The e' values (320-420) in the PbS-KEX system was increased as the KEX concentration was lowered). In the other hand the PbS- K2Cr2O7 system showed higher values of e' (420-510) as the K2Cr2O7 concentration was increased. The PbS-KEX-K2Cr2O7 system was evaluated.

Jan 1, 1997

By Jewel Gomes

Green rust is an important intermediate in oxidative transformation of Fe(II) phase. This unstable compound contains a mixture of ferrous and ferric hydroxides that belong to a family of minerals known as layered double hydroxides (LDH). Its general formula is [FeII(6-x) FeIIIx (OH)12]x+[Ax/n-*yH2O] x-, where A is an n-valent anion mainly Cl-, CO3-2 and SO4-2, and in which either the bivalent or the trivalent iron can be replaced for other trivalent or bivalent metal ions. It was first identified as corrosion product, later in soils as a product of interactions between microbes and metals in soils. Due to its high reactivity, it is used in the reduction of organic and inorganic compounds, As removal, and the treatment of acid mine drainage. In this paper, we described the method of electrochemical generation of green rust, its characterization by XRD, SEM and FT-IR, and its implications to electrocoagulation.

Jan 1, 2009

By Andre Thess, Oleg Zikanov

"Direct numerical simulation methods are applied to study the influence of a constant magnetic field on turbulent flows of liquid metals. The flow is assumed to be homogeneous and the problem is reduced to the classical case of the turbulent flow in a 3D box with periodic boundary conditions. The main subject of the study is the anisotropy developing in a liquid metal flow affected by constant magnetic field.To investigate the long-time evolution of initially isotropic flow the large-scale forcing is applied to maintain the flow energy at a statistically steady level. It is found that the flow evolution depend strongly on the magnetic interaction parameter (Stuart number). In the case of small Stuart number, the flow remains three-dimensional, turbulent, an approximately isotropic. At large Stuart number (strong magnetic field) the turbulence is suppressed rapidly and the flow becomes two-dimensional and laminar. Very interesting is the intermittent flow evolution at moderate Stuart number. Long periods of almost two-dimensional, laminar behavior are interrupted by strong turbulent three-dimensional bursts.The influence of a constant magnetic field on scalar transport properties of liquid metal turbulence is investigated using the simplified formulation of homogeneous flow driven by an imposed mean temperature gradient. Such a flow consists primarily of two turbulent antiparallel jets providing an effective mechanism for heat transfer. It is shown that the magnetic field parallel to the mean temperature gradient stabilizes the jets and, thus, enhances heat transfer considerably."

Jan 1, 1999

By Jie Ma, Bo Wang, Jieyu Zhang, Jian Zhao, Zheng Chen

"In this paper, solidification process of steel ingot was simulated by ProCAST software, based on cellular automaton-finite element (CAFE) model. A 22 t steel ingot was divided into continuous small zones (100x150x180 mm) in radial direction, then the temperature field, shrinkage cavity and porosity, particularly, the microstructure were simulated. The results show that: there was a columnar-to-equiaxed transition in microstructure on radial direction. Zones, closing to the center of the ingot, had a more developed and fined equiaxed zone, while zones closing to the periphery of the ingot had a more developed columnar zone. It indicated that temperature gradient has a great influence on microstructural morphology. Thus, the simulation results were highly agree with the experimental results, verifying the feasibility of this simulation method. It significantly reduces the time of simulation, and has important significance for predicting the microstructure of large steel ingot.IntroductionSolidification microstructure of steel ingot have a significant effect on the quality of the final steel products. Although many experimental works have been carried out in order to obtain the optimum condition for solidification process of continuous casting, it is also very desirable to establish mathematical models to simulate the evolution of solidification structure. The simulation methods can be divided into deterministic models and stochastic models, which have been developed rapidly over the last couple of decades. Cellular automaton method is one of the stochastic models. Rappaz and Gandin [1, 2], Nasatac and Stefanescu [3, 4] are the earliest researchers engaged in the this field. Moreover, Rappaz and Gandin simulated the solidification structure and CET (columnar grain to equiaxed grain transition) of metals using the CAFE method (cellular automaton-finite element method) for the first time [1, 2]. Recently, the CA (cellular automaton) model also considered the effects of fluid flow on the solidification process. Zhu, et al. [5-11] improved method of CA , they used the KGT model to describe the undercooling needed during the growth of the dendrite tip."

Jan 1, 2014

"Mineral flotation processes are often characterized by long dead times and slow process dynamics. The process dynamics change due to different ore types, feed grades and circulating loads. These are some of the factors that can make control of flotation processes difficult. Implementation of adaptive control algorithms at Brunswick Mining has made controlling these processes feasible. The role of adaptive controllers in plant optimization and the overall control philosophy is discussed.IntroductionBrunswick Mining is located just outside of Bathurst, New Brunswick, Canada. The concentrator processes approximately 10,250 tonnes per day of ore that assays at approximately 8.9 %Zn, 3.6 %Pb, 0.3 %Cu and 100 gram/tonne of Ag. The four products produced are zinc concentrate assaying 51 %Zn, lead concentrate assaying 36 %Pb, copper concentrate assaying 21 %Cu, and a bulk concentrate assaying 32 %Zn and 18 %Pb.The original flotation process control system, supplied by Outokompu Oy of Finland, was replaced in the summer of 1988 by a Provox system supplied by Fisher Controls Inc. The Provox system consists of two redundant integrated function controllers (IFC's), two operator console stations with two screens each and a Digital Equipment Co. microVax II computer running Fisher's Computer Highway Interface Package (CHIP).In January 1989 a boiler management package, which includes the boiler control hardware and another operator's console, will be added to the Provox system. In late spring of 1989, a Vax 3200 computer running G2 artificial intelligence software from Gensym Corporation will be installed. These devices are all connected using a redundant data highway that runs around the plant.The primary measurement devices in the flotation circuit are two Courier on-stream X-ray analyzers. The Courier systems each have 14 sample cells with two streams multiplexed into each cell. Each pass of the on-stream head takes approximately 6 minutes yielding a nominal sampling interval of 12 minutes. The Courier passes its assays to its respective IFC. The IFC handles the digital and analog I/O, DDC and cascade loop control, some low level calculations and sequencing. The CHIP microVax has 9MB of memory and 220MB of mass storage running under the VMS operating system. The CHIP microVax is a central database for the Provox system. It is used for data trending, metallurgical modelling and balancing, instrumentation database, long term storage, and on-line adaptive assay control."

Jan 1, 1989

By Shi Yuan

Molten copper was deoxidized using a one-end-closed yttria-stabilized zirconia (YSZ) tube. A thin layer of porous Ni-Zr02 cermet electrode was deposited on the inner wall of the YSZ tube. The outer surface of the tube was in contact with the melt and the inner surface with a flowing reducing gas. Without applying external EMF, the melt was deoxidized by short-circuiting the melt with the cermet electrode. The deoxidation process was analyzed and the rate controlling steps were identified. These experiments were also conducted at different temperatures to evaluate the effect of temperature on the deoxidation kinetics.

Jan 1, 1994

By Stein Tore Johansen

Some ferro-silicon fumaces have heat-recovery equipment. Here, the recovery of electric energy from the off-gases can be increased by increasing the off-gas temperature. This is easily done by reducing the amount of air which usually is mixed into the off-gas to cool the gas mixture. If the off-gas becomes too hot problems with severe fouling or clogging of the gas channels? close to the fumace is observed~ The result is irregular stops to clean the off-gas channels. The paper focuses on the nature? of the clogging phenomena and some of the ways to avoid clogging. A detailed experimental study was carried out at the Elkem Thamshavn Plant. Theoretical studies were performed to understand the particle deposition, turbulent multiphase fluid flow and off gas combustion in the off-gas channels. The study has resulted in reduced clogging.

Jan 1, 1992