Search Documents

By Nickolas J. Themelis

Nearly thirty two million tons of municipal solid wastes (MSW) are combusted annually in over one hundred U.S. Waste-to-Energy (WTE) power plants, thus reducing the use of fuel oil by about 1.6 billion gallons of fuel oil One of the advanced WTE processes is the 0.9-million ton/y SEMASS facility at Rochester, Mass. Most of the combustion in the three giant combustion chambers occurs while the injected shredded wastes are in suspension, i.e., in flash combustion mode. The velocity, temperature, and concentration profiles in the SEMASS combustion chamber were simulated by representing the combustible fraction of MSW by the simplified formula C6HIO04 and using the CFD program Fluent to solve the turbulent energy and mass transport equations. After validation against plant data, this model will be used to examine options for increasing the productivity of WTE combustion chambers, such as optimum distribution of primary and secondary air and oxygen enrichment.

Jan 1, 2003

By Osarnu Inoue

In Mitsubishi Continuous Copper Smelting and Converting Process, smelting, slag-matte separation and matte converting are continuously carried out in series in three furnaces connected by launders. As a result of this operational configuration of the furnaces, influence of the change in operating condition in upper stream, such as variation of feeds in the smelting furnace, propagates to down stream with some delay. In order to achieve stabler operation, process control algorithm based on the dynamic characteristics of each furnace would be very effective. In this study, the dynamic process simulation model was developed for the smelting furnace. The model consists of two mathematical modules, i.e. the thermodynamic module and the mixing module. The calculation results using operating data obtained at Naoshima Smelter showed good agreement with the actually observed change in temperature, composition and flow rate of matte and slag at the outlet of the furnace. In addition, operation parameters such as reaction efficiency of oxygen and coal, dead volume of melts were estimated.

Jan 1, 1999

By Dale T. Peters

Conductivity, both electrical and thermal, are attributes accounting for about 70% of the applications of copper and its alloys. This paper presents results of on-going research into two new applications that depend on copper's excellent conductivity. The Copper Development Association (CDA), together with materials and motor company partners, is working toward a solution to the key problem preventing pressure die casting copper for the conductor bar/end ring structure of the induction motor rotor, i.e., lack of a durable high-temperature mold material. Work is showing that a combination of high- temperature materials and elevated temperature processing gives much improved mold life compared to die steels. Substitution of copper for aluminum in the rotor can result in a 20% decrease in electrical losses in motors consuming 35% of electrical power generated in the U.S. The second development uses the excellent thermal conductivity of several high-strength high-copper alloys to simultaneously improve productivity and part quality in the injection molding of plastic parts.

Jan 1, 1999

By Ali Akbar Mottahedi

Chromate conversion coating is a process for making a complex layer at the surface of zinc galvanized steel which makes the metal more resistant to corrosion, especially at marine atmosphere, and increases the adhesiveness of color. In this work the influences of various compositions on commercial zinc galvanized steel sheet to the color of chromate conversion coating has been investigated at normal temperature and the factors that affect the control and optimization of the process have been determined. A bath composition of 20 g/liter Cr203 and 10 g/liter NaOH and a dipping time of 50 seconds at room temperature (25-30°C) make a desirable color of chromate coating. A slow agitation at a constant pH of I (with additions of NaOH or H2SO4) assures a constant bath condition and develops the color. This kind of coating has more corrosion resistance and this bath condition and composition are also more economical.

Jan 1, 2003

By T. A. Larssen

The efficiency in production of manganese ferroalloys is dependent on the gaseous reduction of the higher manganese oxides in the ores used as raw materials. The materials, descending in the furnace, will meet the furnace gas that contains significant amounts of CO(g) and reduce in subsequent steps, the last step being reduction of Mn3O4 to MnO. This step may to varying extent occur at temperatures exceeding 800 °C, i.e. in the active region of the Boudouard reaction. The gas reduction of Assmang and Comilog manganese ores were investigated in CO-CO2-atmosphere at temperatures up to 1000 °C. It was seen that decreasing ore size correlates to a lower reduction temperature and increasing reduction rate. Similar effect was observed with increasing CO-content in the gas atmosphere. Further, it was found that Comilog ore obtained a complete prereduction at 600 °C, whereas reduction of Assmang ore was not complete at 800 °C for the majority of the experiments.

By Sarel Johannes Francois Gates, Ida Kero, Yan Ma, Gabriella Tranell

During the tapping and casting of manganese ferroalloys, fumes are generated and released to the working environment. The fumes are mostly composed of metallic oxides generated due to reaction between high temperature molten metal and ambient oxygen in the air. From an environment perspective, it is important to limit these emissions. However, to do so, it is important to understand fuming mechanisms and kinetics as well as fume compositions, i.e. element behavior during the oxidation process of liquid manganese ferroalloys. Silicomanganese alloys are composed of aminimum of 65 wt% Mn and 17 wt% Si, 2 wt% C as well as minor and trace elements. These elements include Fe, Mg, Al and other elements originating from ores and reductants. Trace elements behavior in fume from liquid silicomanganese generated under an impinging air jet in the temperature range of 1450–1700 °C has been investigated in this work. The thermodynamic and kinetic conditions governing the generation mechanisms are discussed.

Mar 1, 2017

By F. A. Steward

Copper is one of the trace minerals essential to life. It is added, usually in the form of copper sulfate, to virtually all formulated feedstuffs and to dietary supplements fed to animals on forage. Over the past five years, an improved inorganic copper source trademarked Micronutrients TBCC™, has been developed, tested and commercially introduced. TBCC is a crystalline form of basic copper chloride. Synthesis is accomplished in a continuous neutralization I crystallization process. In current commercial production, the primary sources of copper currently used as feedstocks are the etching solutions used to manufacture electronic printed wiring boards. These solutions have traditionally been managed as hazardous wastes, but their use to manufacture TBCC™ exempts them from regulation as wastes under the "Use/Reuse" provisions of RCRA. Research conducted over five years at multiple universities has shown that animals are healthier when fed this source of copper and that vitamin losses in feed are reduced by its use.

Jan 1, 2000

By Alfonso Nájera

Turbulent flow of liquid steel and its control is studied using different geometries of turbulence inhibitors. Four designs of turbulence inhibitors were characterized through experiments of tracer injection I a water model and mathematical simulations using the Reynolds Stress Model (RSM) of turbulence. Geometries included octagonal-regular, octagonal-irregular, pentagonal and squared. A layer of oil was used to model the behaviour of tundish flux during steel flow. Fluid flows in a tundish using these geometries were compared with that in a bare tundish. Experimental and simulation results indicate that the flow in the bare tundish and a tundish using turbulence inhibitors open large areas of oil due to strong shear stresses at the water-oil interface but the squared inhibitor. These phenomena are explained by the high gradient of the dissipation rate of the turbulent kinetic energy using the squared inhibitor. Using this device the kinetic energy reports a high gradient from the tundish floor to the free bath surface as compared with other geometries.

Jan 1, 2006

By Junji Shibata

Through-hole copper plating is performed to make a multi-layer printed circuit board. The through hole plating is first carried out by Pd catalyst treatment, followed by copper non-electric plating. The amount of Pd catalyst used in one plant is about 0.25-2 m3/month (8 g/dm3 PdCl2 base) depending on the plant scale, and the cost of the catalyst reaches 17,000¬I35,000 US$/month. In this study, the flow and material balance of a Pd in Pd catalyst treatment process was investigated. About 60% of Pd catalyst adheres on the through-hole and other part of setup, while 25% is released into the washing liquor. Pd in the washing liquor should be collected by a suitable method like a pressure filtration using diatomite. The material balance of Pd in Pd catalyst treatment process and the recovery method of Pd from waste solution containing Pd catalyst was investigated.

Jan 1, 2003

By A. V. Tarasov

An environmentally clean and virtually waste-less technology for treatment of domestic solid waste and other toxic chloride-containing materials has been developed and proven on a full scale by the Gintsvetmet Institute in cooperation with some other Russian organizations. The proposed process resolves the acute and globally significant problem of dioxin formation. The purpose of the proposed technology is to ensure such destruction of the structural lattice of toxic compounds that would guarantee irreversible transformation of the resultant substances to prevent formation of dioxins. The preconditions that are required to achieve this purpose are: temperature of >125O0C; an oxidant excess coefficient of >I .05; a certain retention time of the products under these conditions (ADZ s); and thermal instantaneousness of the process involving a transition with no intermediate phase. These conditions were achieved with the experimental development of the Vanyukov furnace design commonly used for sparged smelting processes at non-ferrous metallurgical plants in Russia and Kazakhstan.

Jan 1, 2002

By T. Feldmann

Despite the ubiquity of applications for germanium, there is a lack of practically useful solubility data in acidic solutions. Previous studies were done at ambient temperature and only for commonly used acids (H2SO4, HCl). Hence, an investigation of the solubility of GeO2 in different acids was undertaken. Several inorganic and organic acids were studied in the concentration range of 1–11 mol/L and at 23, 40, and 60 °C. In the case of H2SO4 and HCl previous data was confirmed. Lower acidity resulted in a higher solubility for Ge at all tested temperatures. Tests done at 40 and 60 °C and low to moderate acidity levels, gave slightly increased solubility values at higher temperatures compared to 23 °C. This wasn’t the case at higher acidity levels, i.e., the solubility curves at different temperatures converge at high acidity. Lastly, a relationship of water activity and GeO2 solubility in different acid media was established.

By M. A. Vera

This paper proposes a simple two-parameter model for the typical inverse relationship between recovery and flotation concentrate grade. The model is based on the mineralogical limitations imposed by the material properties. One parameter (R*) describes the proportion of metal content which is floatable, and the other (b) is the rate at which the fastest floating particles are being contaminated by the other less valuable particles present in the mineral system. One significant feature of the recovery-grade curve is that initial recovery (i. e. R ? 0) is at the purest attainable mineral grade, (but as recovery rises the cumulative grade of the concentrate tends to the feed grade. The ideal recovery-grade curve for a particular mineralogical system can be obtained by release analysis: the release analysis curve determines the maximum or limiting separation efficiency. The model proposed in this work is similar to the linear recovery - cut-off grade model of Dell (1), but has the advantage of describing the whole curve.

Jan 1, 1999

By J. C. Agarwal

Most metals are produced from minerals containing one or more of the desired metals, some contaminating metals, silicate, oxides, carbonates, and sulfides. Therefore, in the production of metals, there is generally a gaseous effluent in pyrometallurgical processes and a liquid effluent in hydrometallurgical processes. There are also solid residues such as waste ore, tailings, dust, and slag, created by the metal recovery processes. There are two important distinctions between the effluents and the residues: I. Effluents ? gases and liquids ? affect the neighboring environment for miles from the point of emission, while residues affect only the soil on which they are stored or dumped. 2. The environmental and economic effects of effluents are known and felt essentially immediately. By contrast, the environmental effects of the residues may not be known for a long time. For these reasons, the economic impact and the potential corrective actions required are very different for effluents and residues.

Jan 1, 1992

By R. Angulo

Carbon nanotubes (CNTs) have recently emerged as materials with outstanding properties. This has promoted their consideration as reinforcements for other material systems, such as ceramics. However, one of the fundamental problems with producing CNT-reinforced ceramics is the effective dispersion of CNTs during processing. This has been successfully carried out recently using organic solvents. This paper is a preliminery investigation into the rheological behavior of aqueous CNT-alumina slips, with the objective of moving towards a more environmentally friendly aqueous tape casting process for the production of CNT-ceramic composites.

Jan 1, 2008

By A. Shemi

Tungsten carbide scrap (WC–Co) is material generated from the tungsten carbide manufacturing process and worn out or used carbide parts from industry. Tungsten (W) ores contain about 3 wt% WO3 and their W concentrates about 10– 75 wt% WO3. Tungsten carbide scrap typically contains 40–95 wt% W. The high intrinsic value of W and the fact that the least valuable scrap contains more W than the average tungsten ore makes tungsten carbide scrap a worthy material for re-use. This study has investigated the selective dissolution of the cobalt (Co) binder phase, and recovery of tungsten monocarbide (WC) and Co using an acid leach process. The Co component was selectively leached leaving the WC solid particles intact. Further investigation using a complexing agent-aided acid leach process that takes advantage of organic chelating agents that form a soluble tungsten complex in place of the passive insoluble tungsten oxide is envisaged. The optimal dissolution of the Co binder phase using an inorganic acid in conjunction with an organic complexing agent is a novel approach with the potential of reduced leaching times and possibility of regenerating the unreacted organic acid.

By R. Chiarizia

Third phase formation, i.e., the splitting of the organic phase in two layers, is a common feature observed, under conditions of high loading, for many solvent extraction systems of both analytical and industrial interest. Although this phenomenon has been investigated in a large number of works, a structural and physico-chemical description is still lacking. In this work, small-angle neutron scattering (SANS) data for the tri-n-butylphosphate (TBP)-n-octane,Th(NO3)4-HNO3 solvent extraction system have been interpreted using the Baxter model for hard-spheres with surface adhesion. The increase in scattering intensity in the low Q range, observed when increasing amounts of HNO3 and/or Th(NO3)4 are introduced into the organic phase, has been interpreted as arising from interactions between small reverse micelles containing three TBP molecules plus solutes in their polar core. This intermicellar attraction, under appropriate conditions, leads to third phase formation.

Jan 1, 2003

By V. Bredykhin

The efficiency of scrap processing depends firstly on reliability of information about its chemical composition. The paper presents the results of the investigation and development regarding solid copper alloy scrap in the range of lump size 40÷300 mm. Nowadays the sorting of lump scrap is done by two methods: 1. Sorting according to metals and alloys is done at places of scrap generation, and further till metallurgical processing each lot has its "certificate"; 2. Hand sorting of scrap is done according to the marks on solid items in special shops using proximate analyzers or manually by experienced workers. This sorting process is labor - consuming low efficient and involves mistakes. The informational method is a promising trend in the copper scrap sorting. The method is direct, i.e. as a result of sorting the chemical composition of each scrap lump or main elements is determined, and assured data of qualitative and quantitative composition are received.

Jan 1, 2006

By Yu Yamashita

There have been increasing in melting recycled scraps in copper smelting processes, and thus growing interests in the chlorine behavior. In this study, chloride dissolution in FeO-Fe2O3-SiO2slag (SiO2sat.) at 1523 K has been measured with varying in PCl2 from 1.13x10-8 to 1.30x10-7atm. and the oxygen partial pressures encountered in typical copper smelting furnace, i.e. PO2=10-8 to 10-10 atm. Discussion is made on the chloride capacity of FeO-Fe2O3-SiO2 slag in terms of its characteristics and the dissolved chlorine species. It has been shown that the mostreasonable dissolution reaction and chloride capacity can be expressed by the following reactions, where chlorine dissolves in the form of Cl-; here, aO2-, oxygen ion activity, is shown a function of oxygen partial pressure in the atmosphere. [ ]

Jan 1, 2006

By Fjeldstad Karin Jusnes

Two quartz types used in the silicon and ferrosilicon industry were heated to temperatures of 1600 and 1700 °C. The parameters varied were the temperature and the holding time at maximum temperature. The amount of quartz, cristobalite and intermediate amorphous phase were measured using XRD and the internal standard method. Type P showed a much larger ability to transform to cristobalite at lower temperatures than type A. Type P had a larger amount of alkali and alkaline earth impurities. This could have enhanced the transformation to cristobalite. For quartz type A the amount of cristobalite was larger at 1600 °C than 1700 °C. This can also be seen for some of the samples of type P at shorter holding times.

By Feng-guang Li, Rui Guo, Ju Zhang

Cooling stave is one of the most important equipment of blast furnace for iron making. The heat transfer performance and service life of the cooling stave, to a large extent, determines the efficiency and economy of the iron making process. In this paper, a 3-D heat transfer model of cooling stave was founded by ANSYS based on FEM theory, and the heat transfer characteristics of cooling staves which were made of different materials (cast iron, cast steel and copper) were analyzed. Then, several suggestions on choosing material of cooling staves were given according to the calculation results and the actual working conditions of the cooling staves.

Mar 1, 2017