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By R. W. Adams

A new process has been developed for leaching zinc sulphide concentrates at atmospheric pressure using air or oxygen plus nitrogen dioxide in dissolved or gaseous form as? an oxygen carrier. The process is flexible and can cope with variations in the degrees of retention and regeneration of dissolved nitrogen dioxide in the leaching phase. By controlled addition of concentrate a leach solution with low residual nitrate concentration can be produced. Following separation by filtration of unleached solids and elementa1 sulphur and conventional oxidation/precipitation of dissolved iron, the leach liquor can be treated with metallic zinc to remove the remaining nitrate and other meta111c impurities such as copper, cadmium and cobalt to provide a solution suitable for electrolytic recovery of zinc. Pilot scale testing of the process .has given zinc recoveries in the high nlnet1es, production of a hi.gh grade jarosite-free Pb/Ag residue (50% Pb.) and a saleable high grade of elemental sulphur. .A wide range of concentrates can be treated containing substantial levels of lead and copper as well as zinc. Indicative cost estimates suggest that the new process is competitive with alternative procedures such as pressure leaching.

Jan 1, 1990

By J. B. Winter

The present Inspiration Consolidated Copper Company Smelter/Acid Plant complex located near Miami, Arizona, was designed and built specifically to conform to the ambient air quality standards imposed by the Federal Clean Air Act of 1971. The present plant replaced a facility which had been in operation since 1915. The electric furnace, siphon converters and acid plant complex were commissioned in May, 1974 (1). At that time, the Plant was considered to be one of the most extensively monitored and instrumented facilities of its kind in the world. Several control areas were located in close proximity to the controlled process, in addition to so-called central control rooms in the Smelter and Acid Plant. The control rooms were staffed with officials below the foreman level. Instrumentation consisted of conventional analog devices, except for a computer used in monitoring ambient air environmental conditions and limited use of programmable logic controllers. The harsh service conditions prevalent in the plant rendered a significant portion of the instrumentation unreliable and, in many cases, inoperable. Failure of the facility to obtain the total sulfur collection for which it was designed was, in part, due to serious inadequacies in control system logic and sulfur recovery averaged 79% in the early years. After careful study of the smelting process, engineering hardware and high labor cost inherent in the organizational structure, management made a judgement decision to convert to centralized control of the process with high level supervision 24 hours per day. A distributed digital control system with supervisory arid data acquisition/information reporting computers was selected to satisfy the requirement of central control. Operations are now controlled and coordinated from a primary control room in the Smelter and a satellite control area in the Acid Plant.

Jan 1, 1983

By Ross R. Bhappu

Anticipating a major power cost increase in 1990, Cyprus Copper Company decided to modernize the Miami Smelter at a cost of $92.5 million. The modernization project included the addition of an Isasmelt vessel for use as the primary copper smelter and the modification of the existing electric furnace to a slaglmatte separating vessel. The project was completed in June of 1992 and is currently operating at close to its design capacity. This paper provides a summary of the decision making process, a description of the project, a summary of start-up problems and solutions and the current status of the smelter operation.

Jan 1, 1994

By P. Myllykoski, J. Nylander, A. S. Korhonen, J. Larkiola

The coefficient of friction and the deformation resistance have been determined from the measured rolling parameters by applying the Bland-Ford-Ellis rolling force model and the artificial neural network model (ANN). The dependence of friction on the parameters such as reduction, rolling speed, front and back tensions, contact pressure and deformation resistance have been studied by the ANN model. Measured data of over 10 000 coils have been used in the training stage. Various dependencies have been examined and the results show that the friction coefficient does not depend much on the rolling speed. The reduction and deformation resistance seem to have the strongest effect on the friction coefficient. A friction model based on neural computing has been included into the existing rolling force model.

Jan 1, 1994

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 B. Mishra

The application of various bydrometallurgical, pyrometallurgical and electrochemical processes in the extraction, purification and production of radioactive metals as well as the use of various materials, eg. metals and alloys, ceramics, polymers, etc. in the process, construction and handling equipment in the nuclear industry has generated a large stockpile of radioactively contaminated waste material and scrap metal which can not be directly discarded, recycled or considered for long-term storage due to its volume and potential hazards, without the separation of radionuclides. This paper reviews the emerging methods that have been 'investigated and suggested for dealing with some of these wastes' and scrap material. The separation technologies studied for the recovery of radioactive components from the pyrometallurgical and electrochemical processing wastes have been discussed in details with results from some of the recent theoretical and physical modeling work as well as the data obtained? from the actual waste treatment. Specific processes shall be described in terms of its advantages and limitations. These emerging separation technologies are being considered by the US Department of Energy as alternatives for dealing with the issues of environmental management [EMI' and decontamination and decommissioning [D&D].

Jan 1, 1996

By N. Tsuneyama

Sumitomo Metal Mining Company has been operating Waelz Kiln at the Shisaka Works for 12 years to recover zinc and lead from electric arc furnace (EAF) dust. To increase the capacity and cut down the operating cost, some improvements have been carried out resulting in the capacity of 60,000 t/ y of EAF dust as compared with 32,000 t/ y in 1977. The current capacity is equivalent to 20% or EAF dust generated in Japan. The number of workers has been decreased by the introduction of an automatic control system, and the productivity per worker is now twice as much as 10 years ago. This paper will describe the progress of the operation at the Shisaka Works after the previous? paper reported in "Zinc' 8 5? and summarize the status or EAF dust recycle in Japan.

Jan 1, 1990

By D. Donald Downey

Pilot Testing Ion Exchange Resin (IEX) can go from very simple beaker testing to complicated column testing. Space velocities, regenerant quantities, loading capacities, ion leakage, are all terms that get accumulated together to prove or disprove a resin’s (or resins’) ability to load a single ion (or specific set of ions). Not getting all the resin’s operating parameters correct will disqualify (or at least skew) the results. Laboratory tests for capacity, moisture content, bead size, metals fouling, etc.—what does it all mean? At last count, there were over twenty-five separate ion exchange resin tests (analyses) that were available to end users. Standard testing procedures identify the resin properties but more specific procedures can be used to identify problems with equipment operation. Then, there are the costs to consider; simple cation resin testing (moisture content, total capacity and bead integrity) is in the $200/sample range. However, add to this Chatillon, Russian Ball Mill Test, HIAC particle size, metals and % regeneration test procedures and the lab work can increase to over $1000/sample. In this paper, the author will explain the “must-do” pilot and test procedures and why they are important and the key to understanding how resin performs ion exchange.

By Eren Hüseyin Obuz

In this study, the leaching kinetics of rare-earth elements were investigated using HCl and HNO3 solutions. A standard crushed complex ore was utilized as raw material. The complex ore (particle size of under 54 μm) contains REE (Ce, La, Nd, Pr, etc.). Different leaching durations were selected for the kinetic studies. The highest leaching efficiency was obtained in HCl solution, and the leaching mechanism was identified to diffusion through a product layer. The rate constants of Ce, La, Nd, and Pr were calculated as 1.08 × 10−2, 0.86 × 10−2, 1.87 × 10−2, and 1.34 × 10−2 h−1, respectively.

By V. M. Paretsky

The basic work conducted by Prof. A.Yazawa has demonstrated that in order to ensure single- stage white metal production by autogenous smelting of copper sulfide raw materials, it is most favorable to use highly basic slags, in particular oxide systems CaO-FeO-Fe2O3-SiO2. The special studies have been conducted in the Gintsvetrnet Institute to investigate the composition and structure of slags produced on a semi-commercial scale when testing the KFP and FBP processes for white metal smelting. as well as the slag obtained in a full-scale KFP furnace at the Almalyk copper smelter. The investigations conducted have demonstrated why production of high-grade matte or white metal is associated with lower loss of copper in slag in a series: silicate slag I silicate-calcium slag I ferrite-calcium slag.

Jan 1, 2003

By A. D. Damodaran

Batch scale and continuous rotary kiln carbothermic metallisation of ilmenite followed by different down-stream treatments such as catalytic rusting, acidic chloride leaching, oxidation-leaching etc. has given rise to a high grade synthetic rutile (98% TiO2). Rotary reactor metallisation experiments had concurrently given important information with respect to mean residence time, dispersion number, hold-up and axial velocity profiles of the solids bed. A mathematical model based on law of additive reaction times has indicated that Boudouard reaction becomes faster than reduction reaction at higher conversions. A possible use of high grade synthetic rutile in paint industry and metallised ilmenite as welding electrode flux material are discussed.

Jan 1, 1992

By Ko-ichiro Ohno

It is recently recognized that the iron reduction and melting as well as the slag separation of a composite of granular iron ore and coal are completed in a very short period of about 10 minutes when the composite is rapidly heated up to approximately 1673K. These phenomena are expected to be applied to a new iron-making process. The mechanism of iron ore reduction and iron-slag separation during rapid heating has not yet been revealed and the fundamental research has just started. Carburization of the reduced iron is regarded as one of the most important steps in this process. In the present work, the composite was prepared from four kinds of coal or graphite as a carbon source and electrolytic iron powder as a completely reduced iron ore. The temperature at which the liquid formation and iron carburization occurred was monitored. Direct observation of smelting reduction behavior was made by a confocal laser-scanning microscope combined with the infrared image-heating furnace to clarify the effect of molten ash on iron carburization. It was found that the meltdown temperature of composite became lower as the melting temperature of coal ash decreased. From the observed result, it was presumed that the liquid slag would act as an important media for the carbon transfer from coal to iron. The carburization mechanism during the smelting reduction was estimated as follows. When slag containing iron oxide melted down and contacted carbon, iron oxide in the slag was reduced and the formation of the metallic iron particle as well as the its carburization occurred simultaneously at the slag-carbon interface. Carburized iron particle was carried from slag-carbon to slag-iron interfaces due to the slag convection flow caused by the difference of the interfacial tension between the carbon-slag and iron-slag interfaces. Carburization of reduced iron could proceed with a repeat of the above-mentioned process.

Jan 1, 2003

By M. K. Alam

Chemical Vapor Deposition (CVD) processes are currently attracting special attention in materials processing. CVD processes are now used to produce special materials in the form of thin films, coatings, composites, and optical fibers. This process produces material of high purity, in complex shapes, and in a variety of microstructures. It is a capital intensive process, involving use of high cost raw materials. Modeling simulations have the potential of reducing the time for CVD . process design, and the need for experimentation. Modeling would, therefore, appear to be an attractive option for producing a product of acceptable quality. At Ohio University, progress has been made in modeling of CVD processes, specially in the areas of optical fiber preform fabrication, and fiber coating.

Jan 1, 1990

By A. A. el-Geassy

High-grade iron ore fines rejected from the DRl plants (>96%Fe20) were isothermally reduced in 30-60%COIH2 gas mixtures at 973-1273K. The freshly reduced reaction products were then subsequently carburised in either H2/CO or H2/CO/S mixtures at 823-1073K for 30-120 min. The thermogarvimetric technique was used to follow up both of reduction and carburisation reactions as a function of time. The carburised samples were characterized by X-ray and Mossbauer techniques. Chemical and carbon analyses were also applied. The influence of temperature and gas composition on the reduction behavior was investigated. The calculated values of apparent activation energy, application of gas-solid mathematical formulations were correlated with the microstructures to predict the reduction mechanism, The influence of carburization time, temperature, CO contents in H2/CO or H2/CO/S were investigated. A conversion extent of Fe to Fe3C was taken as a measurable index for the efficiency of carburization reaction under the different experimental conditions.

Jan 1, 2003

By Knut H. Bech, Stein Tore Johansen

"The collision efficiency for small particles relative to 2D spherical bubbles in a developed turbulent flow field were calculated applying an adopted version of the CPD program FLUENT. The turbulence field was related to bubble size and fluid properties. The results were compared with analytical theory. The turbulence intensity was found to be the most important single parameter for collision efficiency. Effects of boundary layer thickness and particle diameter were discussed. IntroductionRemoval of inclusion particles from melted aluminium can be facilitated by means of a rotor system that supplies kinetic energy and gas bubbles to the floating metal. At the surface the inclusions adhere to the surface dross or slagg which is removed at regular intervals by the operators. When applying computational fluid dynamics (CFD) to model such a system, one experiences difficulties with the large range of turbulent length-scales encountered, from the large geometrical scales of the rotor and container, through the bubble size and down to the particle diameter. A mathematical model for the complete system will be both complex and require an extreme spatial resolution. Another way of dealing with the problem is to model the micro-scale phenomena separately and apply the results to create a model for the macroscopic system. In a previous work [12] we addressed these problems and developed a procedure for calculating turbulence enhanced flotation to bubbles. It was found that turbulence may have a profound effect on the collision rate of particles to idealized bubbles. In this study we recognize that only a fraction of the total turbulent kinetic energy generated by the rotor's work on the liquid metal may contribute to enhanced flotation. By using a model spectrum for the turbulence, the fraction of turbulent energy in eddies smaller than the bubble diameter is calculated. A twodimensional CFD model was then constructed to calculate the collision efficiency between particles and bubbles of various sizes."

Jan 1, 1999

By Uchil Jayagopal, P. V. Krupakara, S. Manjunath

"This paper deals with the corrosion characterization of quartz particlate ZA-27 alloy metal matrix composites (MMCs). Quartz particles of size 50-80 microns are used as reinforcement. MMC's are prepared according to ASTM standards. Composites containing. 2, 4, and -6% by weight of quartz and unreinforced matrix were tested using 1 -N hydrochloric acid: The composite was found to be more corrosive resistant than matrix alloy. In each test the corrosion resistance of both alloy and composites were found to decrease with the exposure time.1. IntroductionMetal matrix composites- (MMCs) offer designers many added benefits, as they are particularly suited for applications requiring good strength at high temperature, good structural rigidity, dimensional stability, and light weight 1-5. The trend is towards safe usage of the MMC parts in the automobile engine, which work particularly at high temperature and pressure environments Particles reinforced MMCs has been the most popular over the last two decades.ZA alloy MMCs have most popular families being represented by. ZA-27 alloy reinforced with ceramic particulate. Although the incorporation of the second phase into a matrix material can enhance the physical and mechanical properties of the base metal, it could also significantly change the corrosion behavior.ZA alloys have been used extensively in industry. This is attributed to their excellent fludity, castability and good mechanical properties. Among the zinc-based foundry alloys, the ZA family of alloy have been widely used during the past few years. ZA alloys have many advantage over aluminium based ones, especially high strength with a low casting temperature 8."

Jan 1, 2000

By John A. Clark, Danylo Oryshchyn, Casey Carney, Stephen Gerdemann, Cathy Summers, Thomas Ochs

"Limited analysis of combustion gas streams where carbon capture is not of interest is done mainly to ascertain operation parameters. Stringent regulations on acid gases and particulates promote careful flue gas analysis. Unregulated components are typically not analyzed. Typically not more than four points (two in the boiler, and one each in the flue and the stack) are sampled. A successful oxy-fuel process with carbon capture and compression is anticipated to require as many as 12 sample points with analysis for water, nitrogen, oxygen, argon, NOx, SOx, and carbon monoxide. Carbon dioxide captured for beverages produces a high value product and the cost associated with analysis is warranted. However, carbon capture for disposal must keep all costs to a minimum. This paper will compare alternative approaches for cost-effective sampling and analysis of the carbon dioxide product streams from oxy-fuel combustion, through all stages of production through compression and pipeline/vessel delivery.IntroductionAnalysis of gases in an oxy-combustion process with carbon capture is essential to the operations of the oxy-fired boiler and the subsequent collection, compression, and purification of carbon dioxide. The process is charged with pure oxygen and not-so-pure carbon in the form of coal at the front end, generating a product of mainly carbon dioxide with traces of argon, nitrogen, sulfur compounds, nitrogen compounds, oxygen, hydrogen, and mercury. It is possible that hydrogen chloride and hydrogen sulfide may also be present in trace amounts [1]. The trace components primarily come from impurities contained in coal such as water, sulfur, nitrogen, and volatile organic compounds. Coal also contains a good deal of mineral matter that is transformed into ash during combustion, becoming particulates that can complicate the analysis regimes utilizing standard analytical equipment."

Jan 1, 2010

By C. T. Philipp

Recycling of waste is much preferred over disposal. This paper discusses the Enviroscience, Inc. (ESI) process, now being commercialized by MetWool, Inc., to recycle hazardous wastes using an extractive metallurgical process which is followed by vitrification of non-reducible metal oxides. In this process, volatile and reducible metals are reclaimed as their respective oxides and elements.

Jan 1, 1995

By A. V. Tarasov

Investigations of thermodynamic properties of Cu-Ni and Cu-Ni-S systems and mattes have been conducted with the aid of a MC-130 I mass-spectrometer designed for studies of processes of vapor formation of hardly volatile substances. The instrument comprised a combination of an evaporator of Knudsen chamber type with a mass-spectrometer for analysis of the vapor phase. In the process of studies of molten Cu-Ni-S systems and commercial-grade mattes within a temperature interval of 1400-1800 K the partial pressure of sulfur was measured by means of complete isothermal evaporation and the partial pressure of copper and nickel by comparison of ionic currents. The partial pressure values of the components above the molten Cu-Ni-S were used for calculation of activities of the respective components in the melt. The copper and nickel activity data obtained was used for assessing the amount of dissolved losses of these metals in autogenous smelting slags.

Jan 1, 2003

By Fangqing Yin, Qingyu Deng, Zhengfeng Qu, Mengjun Hu, Meilong Hu

Titanium bearing blast furnace slag, which contains 20%-30% TiO2, is a valuable secondary titanium resource. Based on the thermodynamics calculation effect of the temperature on the reduction of the slag in vacuum were studied at certain vacuum degrees. The results show that magnesium vapor and silicon monoxide vapor can be obtained at the condition of high temperature and low pressure. The purity of TiC increases with temperature increasing. When the temperature arrives at 1623K TiC can be obtained besides the reductant carbon. XRD result of the powder collected from the furnace cover show that magnesium and silicon in the titanium bearing BF slag leave the slag system during carbothermal reduction in vacuum. From the above it can be concluded that TiC can be obtained from the titanium bearing BF slag and silicon and titanium in the slag can be separated by carbothermal reduction in vacuum and acid leaching.

Jan 1, 2016