Search Documents

By Pandey H. D.

The paper describes a fluidised bed ion exchange method for simultaneous removal of phenols and cyanide from the effluent. Use of an eluant enables regeneration of the resin in the continuous operation mode. The breakthrough experiments conducted both on the laboratory scale and on a pilot plant scale have shown that while the level of phenol can be brought down from 462 ppm to about 6 ppm, the free cyanide is almost totally removed. An examination of data indicates that the method can serve the twin objectives of pollution control and phenolic compounds recovery.

Jan 1, 1992

By K. Yarnaguchi

In the Mitsubishi Continuous Copper Converting Furnace, calcium femte slag is used. Due to its extremely high basicity, the improvement of corrosion resistance of the refractory lining is in need. In order to clarify the corrosion mechanism and to search for a new corrosion resistant material, first, the surface snuctures of bricks corroded in molten slags were observed by EPMA. Second, the dissolution behaviors of sintered MgO-based pellets containing various oxide additives were examined. It was found that the formation and the dissolution of magnesiofemte at the surface of the bricks play an important role in their corrosion and an addition of NiO, Mn02, or Ti02 to MgO is effective in stabilizing the magnesio-femte and improving the corrosion resistance of MgO.

Jan 1, 1994

By Sergio N. Monteiro

Jute fabric obtained from discarded sackcloth is a promising low cost and post-used material being considered as reinforcement of polymeric matrix composites. In particular, the combination of this fabric with a recycled plastic constitutes an environmentally correct composite with both economical and environmental advantages. The present work investigates the toughness of recycled polyethylene composites reinforced with up to 40 wt% of post-used jute fabric extracted from discarded sackcloth. Standard Izod notched specimens were impact tested and the results showed an increase in toughness with the amount of jute fabric. Observation of the composite fracture by SEM revealed that the fabric weave, in spite of damages caused by the previous use of the sackcloth, act as an effective obstacle to crack propagation.

Jan 1, 2009

By F. Kassabji

This publication presents the main experimental and theoretical results on the recovery of aluminum scrap (dross and Used Beverage Can) without use of any addition of fluxing salts. Dross and UBC's processing experiments have been conducted in a rotary plasma furnace operating in the transferred and non-transferred mode, using different plasma gases. The investigation involved the treatment of more than 100 kg of dross and other aluminum residues using plasma torches with less than 100 kW power. The experimental work showed that this process is .far more economical and kind to the environment than the conventional route using a salt flux. An equilibrium thermodynamic calculation at elevated temperature makes possible the prediction of by-products at various temperatures for different plasma gases.

Jan 1, 1994

By Luciano B. Oliveira, Alexandre M. Stumbo, Luis G. C. Marques, Valdo S. Marques, Sergio N. Monteiro

"Similar to the ethanol program, initiated more than 30 years ago, the recently created biodiesel program in Brazil is expected to rely on private initiative based on agribusiness for vegetable oil production. Campos dos Goytacazes is a large county in the northern of the state of Rio de Janeiro with land still available for oily vegetables plantation in addition to the land traditionally occupied by sugar cane plantation, which is used to produce ethanol. In order to extend the biodiesel program to Campos dos Goytacazes, the State University of Northern Rio de Janeiro (UENF) is conducting a technical project for the development of the infrastructure for biodiesel production. In this work, the infrastructure based on versatile equipment for biodiesel esterification built in the Center for Alternative Energy of the UENF is presented.IntroductionBiofuels are gaining worldwide attention as a possible economical solution for the prediction of declining reserves of petroleum and related increase in price of barrel. However, nowadays, a more relevant question is the climate changes caused by burning fossil fuels. This is especially the case of coal and petroleum based fuels, mainly gasoline and diesel that propel the majority of vehicles and generate a large amount of CO2 emissions responsible for global warming. This combination of economical an environmental problems is already providing a strong motivation to substitute conventional fossil fuels by renewable biofuels. More than just the interest of the market financial forces, government legislation is imposing a new order that obliges the use of biofuel. Many countries including the USA, the European Community, Japan and Brazil are committed to gradually substitute biofuels into their fleet of vehicles."

Jan 1, 2008

By Bowen Li, Matthew D. Andriese, Jiann-Yang Hwang, Zhiwei Peng

"Magnetic iron sulfide ore particles heat rapidly by microwave (MW) irradiation generating plasma during oxidation of surfaces. The high temperatures produced by the exothermic event decompose local portions of samples forming a differentiated flux of partially melted silicate (si-mt) with entrained metal-sulfide (sul-mt) droplets. The si-mt forms crystals of olivine (01) in Ca-rich pyroxene (Cpx) melt that resorbs a portion of iron sulfide (Po). The immiscible sul-mt droplets of (Fe,Ni,Cu)1-xS contain magnetic subsolidus Ni-pyrrhotite (Ni-Po) with Cr-bearing ferrospinel (Mag). Sub-micron sized flecks of Au are found on the surface of a sul-mt droplet with scanning electron microscope (SEM).IntroductionSulfide ore deposits supply the world's mineral resource in the production of non-ferrous metals. Particularly, Cu-Ni deposits are chemically enriched in metals from high sulfur saturation during magmatic formation that creates the proper geochemical environment for metals enrichment [1, 2]. The sulfur and oxygen fugacity control redox conditions of a differentiated silicate/sulfur magmatic melt with the concentration of iron playing a dominate role in the chemical partitioning of metals in sulfide liquid [3, 4]. The initial magnetic crystallization of (Fe,Ni)i-xS monosulfide solution (mss) from metal-sulfide liquid has an exclusive effect on the fractionation of mineral assemblages (zoning) [5].Phase equilibria of sulfide melt (sul-mt) components are related by a miscibility gap with mss forming Ni-rich pyrrhotite (Ni-Po) followed by the crystallization of (Fe,Cu)1-xS intermediate sulfide solution (iss) [6]. Precious metals form stable chacogenides and are retained in solution until the final liquid solidifies. The redistribution of metals now occurs by subsolidus cooling of mss and iss that exsolve low-temperature Fe-Cu-Ni bearing mineral assemblages [7]. The proper interpretation of ore genesis increases processing capabilities by isolating chemically enriched zones during extraction and should be used to aid in sustainable mine site development [8-11]."

Jan 1, 2013

By Yong-ming Chen, Chao-bo Tang, Yun Li, Long-gang Ye, Sheng-hai Yang, Hao-tian Xue

In order to achieve high recovery of Cu and Co during cobalt-bearing copper sulphide ore smelting process, reducing agent (coke) and sulphidizing agent (pyrite) were added into molten smelter slag for reducing-sulphidizing smelting to product Cu-Co matte. Effects of reductive atmosphere, pyrite dosage, smelting temperature and smelting duration on Cu, Co, Fe distribution behaviours were investigated. The results show that the distributions of Cu and Co are mainly enriched in Cu-Co matte, and the distribution ratio, LCu and LCo, improve with increasing of coke amount or pyrite addition, whereas above 6 wt.% coke or 20 wt.% pyrite, Cu and Co tend to transfer from matte to cleaned slag. A properly high temperature(1300) and smelting duration(3h) are beneficial to the enhancement of the distribution ratio of valuable metals, and under the given set of conditions, LCu > LCo generally. However, an undesired high Fe contents in matte limit further increase of LCu and LCo.

Jan 1, 2015

By Theo Lehner

The Rönnskär smelter has wide experience in the field of recycling of non-ferrous metals. Today, smelting and refining from primary and secondary raw materials are integrated in a complex flow sheet. Boliden operates a lead flash smelter, a lead refinery, a copper smelter and refinery, a sulphuric acid and sulphur dioxide plant, a slag fuming plant and precious metal plant at its Rönnskär smelter in the North of Sweden. The Business Area Smelter Operations also incorporates Boliden Bergsöe, Sweden's lead-acid battery recycler, and Norzink, Norway, where recycled zinc accounts for more than 20% of it's production. Raw materials for the Rönnskär smelter include concentrates, ashes, slags, metallic scrap, electronic scrap and electric arc furnace (EAF) steel-making dust. This paper briefly describes current operations and illustrates current measures to improve productivity. Limits to recycling as experienced by a non-ferrous smelter are, illustrated. The deportment of critical elements contained in raw materials is also discussed.

Jan 1, 1998

By James C. Sever

Two green field magnesium reduction plants are under consideration using dolomite as the raw material. The Calix calciner was independently selected for both plants. The unique design of this calciner is detailed and the advantages defined for the specific application. The low carbon foot print of this unit combined with the ability to capture food grade carbon dioxide makes this an environmentally proactive approach to carboniferous ore calcination.

Jan 1, 2015

By Hongbo Yang, Tongbo Zhang, Ting Huang, Jingshe Li, Fangfang Song

"Liquid core length is a very important parameter of the process of continuous casting, which directly reflects the cooling status in secondary cooling zone and solidification rate of the slab. In this paper, the billet caster in some steel plant in China was chosen as the prototype of simulating. A numerical simulating model for calculating the liquid core length of continuous casting billet was built by ProCAST software, which was verified reasonable and accurate by pin-shooting technique. Based on the model, the relationships between casting speed, casting temperature and liquid core length of casting billet were found, which was very practically useful for the workers on sit to improve casting billet quality. IntroductionContinuous casting process developed very rapidly because of the high metal yield, energy saving, and low-cost 111• And the quality requirements of continuous casting billet for customers became higher and higher with the fast development of economic121• Internal defect usually is the major quality problem for continuous casting billet[3•61 , which is influenced by the solidification process of casting billet, especially the solidification process of liquid core17•81 • So it is very important to study on the relationship between casting parameters and the liquid core length which means the distance between the crystallizer meniscus and the casting billet solidification end-point. In practical production process, the workers usually control the quality of casting billet according to the liquid core length."

Jan 1, 2013

By Jörg Wallner

In order to limit SO2 emissions, the Montanwerke Brixlegg AG has installed a desulphurisation plant with the primary aim of reducing the peak emissions from the copper converter that are of particular ecological concern. The author discusses the process requirements, the desulphurisation process selected and the results achieved.

Jan 1, 1996

By Sergio N. Monteiro

Fibers extracted from the ramie plant have been traditionally used in textile and are now being considered as polymeric composite reinforcement owing to their superior strength. Recently the mechanical behavior of ramie fiber reinforced polyester composites was investigated but no significant improvement was found. Therefore, the objective of this work was to carry out a similar investigation by changing the type of polymeric matrix. Specimens with up to 30% in volume of ramie fibers incorporated into epoxy were bend-tested until fracture. The results showed a moderate improvement with a tendency of decreasing stress for higher amounts of ramie fibers due to the weak interface developed with the epoxy matrix.

Jan 1, 2009

By L. M. Abrantes, A. P. Paiva

"A brief review of some innovative methods for the direct recovery of metals from loaded organic phases is presented; emphasis is given to electroreductive stripping and cementation, which are described and illustrated by examples: of current research. The recovery of silver using a two-phase electrolysis - by direct application of an electrical potential to a mixture of a metal loaded organic phase· containing Cyanex 471X, obtained by solvent extraction, and a stabilized sodium thiosulfate solution - is more extensively discussed. The overall efficiencies are analyzed and compared with data obtained by conventional stripping procedures. Some preliminary results achieved for the recovery of the precious metal using galvanic stripping, applied directly to similar organic solutions and involving zinc and iron powders as reducing agents, are also evaluated.Introductory ReviewThe application of hydrometallurgical methods to the recovery of metal values from ores and concentrates has been receiving a growing interest, either from researchers or from the mining industry [1].For the concentration / purification of the relatively low concentrated metallic solutions resulting from the leaching of those raw materials, solvent extraction (SX) is a well established technique [2]; the loaded organic solvent is then conventionally contacted with a suitable aqueous solution, the metal in its final form being usually recovered from this solution by electrowinning.As an efficient and / or selective stripping is sometimes difficult to achieve, depending on the specific characteristics of the system under consideration, some alternative procedures have been analyzed in order to overcome this problem. One of the chosen routes, mainly developed by Hirai and Komasawa, is to promote the reduction of the desired metal species in the organic phase, in such a way that the stripping stage becomes feasible; for the selective stripping of vanadium from a solvent containing a mixture of vanadium and molybdenum, the authors successfully used reductive [3], electro-reductive [4,5] and photo-reductive [6] techniques. The two latter methodologies have also been applied to the recovery of europium from a solvent containing europium, samarium and gadolinium [7,8].However, further processing is necessary to recover the metal in its solid state; therefore, methods causing the direct reduction of the metal species in the organic phase to their fmal metallic form would be of interest, as an intermediate step would be avoided"

Jan 1, 1997

By Mariana H. Staia

The present communication reports the results obtained by applying different concentration methods, at laboratory level, to the black sands from Estado Bolivar, Venezuela, with the aim of obtaining an adequate ilmenitic concentrate for the subsequent chlorination process. Sizing analysis was performed and plasma emission spectroscopy method was used to determine the chemical composition. It was found that from the two hydrogravimetric methods used, the Humphrey spirals is much more effective than Wilfley tables, leading to a 85% recovery. The most convenient particle size group for these concentration methods was the one corresponding to ASTM 40-140 mesh. When magnetic concentration was applied to the concentrate, obtained as a product from Humphrey spiral, a recovery of ilmenite more than 90% was obtained in the first step. It has been shown that the ore would respond to the separation techniques employed, giving individual minerals: ilmenite, zircon and silica as concentration products.

Jan 1, 1995

By Chengyi Ding, Xuewei Lv, Changyang Ji, Rende Zhang, Xiangwei Zheng

The fraction of liquid phase in sintered ore can be the most important factor to determine the sinter quality and yield in sintering process. The generation ability of liquid phase for mixture of iron ore powders is determined by basicity, roasting time, roasting temperature and chemical composition of iron ores. Five different iron ores were selected in this study and the dried powders of iron ore and CaO reagent (<200 mesh) were homogeneously mixed together at their required proportions, then 15g of the mixture was pressed under a pressure of 20MPa to make a cylindrical sample with a diameter of 20mm. The sintering temperature in this study was kept at 1280℃, the gas phase is air, the holding time was varied with its three levels of 5min,10min and 15min. After that, the sample was cooled under room temperature in the air, and the cooled sample was analyzed by using zeiss optical microscope. The mineral phase compositions were quantitatively determined with an open source image processing software, Image J whicn can calculate the fraction of liquid phase. Besides, the study on how to estimate the sintering behavior of the raw materials in different conditions by the theoretical calculation is of vital importance, and the development of this will greatly improve the sintering production. Factsage will be used to calculate the liquid phases formulation during the sintering. Comparing the experimental results and the theoretical calculation shows that the mass of liquid phase increases with increasing basicity during the sintering, besides, the mass of calcium ferrite increases with increasing basicity. The generation ability of liquid phase of iron ores can be predicted through the experiment verification.

Jan 1, 2015

By Preben Ingerslev

Control of the reheating of ingots is based either on surface temperature measurements using optical pyrometers or on furnace set points and reheat time determined empirically. This paper presents a real-time mathematical heat flow model, named BESTT, which calculates the temperature distribution in an ingot cross section when reheated or cooled. The model runs on a 486 PC in less than one minute for a variety of ingot cross sectional shapes such as circular, square and with some considerations octagonal and heavy-cornered square. Initial temperatures can either be uniform or nonuniform while accounting for temperature dependent thermophysical properties. The model was developed and verified using 718 alloy ingots in box type furnaces. When integrated with on-line pyrometric measurements, BESTT can provide for improved feed back in the reheating control loop. The use of BESlT will assist in reducing energy costs, and improving product quality and consistency. EPD Congress 1994 Edited by C. Warren The Minerals, Metals k Materials Sodety, 1993

Jan 1, 1994

By Edward Peters

Scandium (Sc) has unique properties and is one of the more valuable elements in the periodic table. Scandium can be used in solid oxide fuel cells and to produce high strength aluminium alloys of value, for example, in the aerospace industry. Scandium is often grouped together with the rare earth elements (REE). Amongst others, scandium can be found in bauxite residues, so called red mud. It is possible to extract and enrich scandium from red mud by leaching and solvent extraction. Scandium can then be recovered from the pregnant strip liquor by crystallization. The strip liquor will however still contain certain impurity elements. In the present work, a method for obtaining a pure scandium solid phase by direct crystallization from the strip liquor is evaluated. It was found that Fe and Ti co-precipitate with Sc under the conditions employed.

By Naiyi Li, Henry Hu, Alfred Yu

"In the past few years, various squeeze cast aluminum components have been developed and successfully implemented in various vehicles by the automotive industry because of their superior engineering performance. However, fundamental understanding of the formation of air gap during squeeze casting processes is still very limited despite of its significant influence on the extent of heat transfer between the casting and mould. In this paper, a mathematical model has been developed to simulate phenomena of air gap between the casting and mold' during squeeze casting of aluminum alloys. The model considers the effect of process parameters such as applied pressures and mold temperatures on the events of air gap formation. The predication indicates that the occurrence of highly enhanced heat transfer in squeeze casting of aluminum alloys primarily results from the presence of excess applied pressures.IntroductionA number of squeeze cast Al components has been developed and used in mass-produced vehicles in the past few years, such as steering knuckles, Road wheel, Engine Block etc. This is attributed to their superior engineering performance. In squeeze casting, the cooling rate can be increased by applying high pressure during solidification which results in the noted refinement in the micro structure scale leading to better casting properties. However, the excessive pressure increased interfacial heat transfer coefficient is affected during the solidification by air gap formation and die surface condition etc., which is believed to increase thermal resistance at the casting/die interface [l - 4]."

Jan 1, 2004

By Huimin Lu, Lian Zhou, Qiang Li

"A three-dimensional mathematical model is developed for the regenerative rotary hearth furnace with 40 meters medium diameter. The influence of combustion switchover and outlet pressure on the fluctuation and distribution of temperature and pressure is studied with numerical simulation method. The results showed that the temperature field and flow field is suitable for requirement of industrial production; the fluctuation of the temperature field and pressure is acceptable; the influence of outlet pressure on the furnace pressure is great.IntroduceRotary hearth furnace which is originally utilized as heat treating and reheating industrial furnace, now is also used for carbon based DRl production. With the need of market and the concern of resource recycling and environmental issues, the DRl production from ore or from waste material by rotary hearth furnace attracts more and more attentions from steel industry [1,2].When rotary hearth furnace works, the feed pellets are charged on the hearth and rotate within an annular furnace chamber with the process of reduction. For the sake of rapid reduction, usually the depth of the pellet is one or two layers, accounting for less than 90% of the volume of furnace. As result, the exhaust gases carry away a lot of heat, so that energy utilization efficient is low [3]. Currently, in order to reduce the consumption of energy and improve the production efficiency, many methods have been adopted. The regenerative combustion technology is one of the most promising."

Jan 1, 2013

By Hideki Minoura

"Two novel electrochemical techniques for the preparation of highly crystallized CdS film have been presented. One is cathodization of a conductive substrate in an acidic chemical bath containing cadmium salt and thioacetamide, where electroreduction of proton at small current densities induces a growth of highly crystallized CdS thin films, whose growth is not disturbed by the reactions in the solution phase. The other technique is electoreduction of aqueous Cd2+— SCN complex. An advantage of this technique lies in no formation of solid particles in the bulk, of the bath.IntroductionIn recent years much attention has been paid to materials preparation by solution processing because of its advantages in lowering the cost as well as the stress to the environment, as compared to the conventional gas phase techniques which unavoidably require high temperature and/or vacuum. We have been trying to explore novel techniques for preparing functionalized compound semiconductors by aqueous solution process. Semiconductors which we have been mainly focusing on are CdS and ZnO, which are important semiconductors finding applications in various devices. In the present paper, some of the techniques that we have recently established for the preparation of highly crystallized CdS will be presented.Methods of the CdS film processing in solution phase (wet process), which have been reported so far can be divided into two major groups; one is chemical bath deposition (CBD) in alkaline solution containing Cd2+ and thiourea 1)4) and the other is electrodeposition (ED) in acidic solution containing Cd2+ and thiosulfate ions - 5)-8) or organic solutions containing dissolved sulfur 9)-11)."

Jan 1, 2000