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By H. Y. Sohn, S. PalDey

"A new chemical synthesis process for the preparation of intermetallic compounds has been developed. It involves the vapor-phase reduction of mixtures of constituent metal chlorides by magnesium vapor to produce intermetallic compounds in the form of fine powder. The advantages of the process include (a) the use of inexpensive raw materials, (b) low reaction temperatures, and (c) products in the form of fine particles. Titanium and nickel aluminides were prepared by this method. The effect of AlCl/TiCl3 partial pressure ratio on the formation of different titanium aluminides was studied. A two-phase mixture containing 80 mol % of TiAl and 20 mol % of TiA13 formed at an AlC13/TiC13 ratio of 10. The amount of TiA13 was maximized to 72 mol% at an AlC13/TiC13 ratio of 16. The maximum conversion of the limiting chloride TiCl3 was 94 % . In the case of nickel aluminides, NiAI, NiAl3, and Ni2Al3 were formed by reducing mixtures of NiC12 and A1Cl3 vapors. The effect of the partial pressure ratios AlCl3/NiC12 and Mg/NiC12 on the formation of nickel aluminides was studied. The maximum content of NiAl obtained was 98 mol % . At the AlC13/NiC12 ratio of 19, a two-phase mixture of 17 mol% of NiAl and 83 mol% of NiA13 was produced. The product particles were very fine in the size range of 0.05 to 0.2 µm.A. IntroductionIntermetallic compounds are attracting much attention [1]. Titanium and nickel aluminides have attracted a great deal of attention from the aerospace as well as automobile industries because of their potential for high-temperature application (e.g., low density, good oxidation resistance, and high-temperature strength retention [2, 3]). Gamma TiAl and two-phase (TiAl and Ti3Al) alloys [4] are used for gas turbine engine rotational components as well as automobile exhaust valves. TiAl3 is one of the most extensively investigated aluminum-rich intermetallics. Nickel aluminides are attractive because of their low densities, relatively high melting point and good high-temperature strength properties. For example, Ni3Al shows increasing rather than decreasing yield strength with increasing temperature [5]."

Jan 1, 1998

By C. S. Ek

Tests have been performed to recover silver and lead from residues produced after a super-hot leaching in a zinc hydrometallurgical plant operating with jarosite precipitation. When this residue is leached in ammoniaammonium sulfate or in diethylenetriamine solutions, lead dissolution is not complete and its recovery from the aqueous solutions is either difficult, due to the operating conditions, either expensive due to the amount of added reagents. In both cases, silver is partly dissolved, partly left in a new residue still containing lead and baryum sulfates. The best treatment seems to include a selective flotation producing first a silver concentrate assaying about I % Ag, then a 50 % lead concentrate collecting the baryum salts, and a final quartz-gypsum tailing. Metal recoveries can reach 50 % and 80 %, respectively.

Jan 1, 1989

By Mike Dry

While McCabe-Thiele plots are useful for designing single-component solvent extraction systems, not least because of their simplicity, they are less useful for multi-component solvent extraction. This paper presents a relatively simple method, compared to other approaches, for modelling solvent extraction as chemical equilibrium reactions between the various aqueous and organic species. The essence of this approach is how values for the equilibrium constants can be extracted from standard laboratory data. Synergistic solvent extraction of nickel is used to illustrate the method.

By Jianjun Wang, Jiaqing Peng, Lingen Luo, Zhenbang li, Yinghe Lin

Copper removal from ferronickel by FeS has been exploring studied. It is found that the decopperizing agent FeS makes the copper removal in ferronickel effectively. The effects of FeS addition amount, carbon content in ferronickel and experimental temperature were investigated. The results showed that the removal rate of copper in ferronickel increased with the amount of FeS increasing. When the dosage of FeS is 20% (mass percentage)，the removal rate of copper can reach higher than 11%. The rate of copper removal rises with the amount of carbon content increasing in ferronickel. When the amount of carbon content is 1.86%, the removal ratio of copper is 41.3%. Higher experimental temperature promotes the copper removal reaction in certain extent. The flux is acidity and weak oxidative can also promote the reaction of copper removal.

Jan 1, 2015

By Annette Revet

Aluminum fluxes have been used for the remelting of secondary aluminum since the beginning of the recycling industry. During the last sixty years, a number of fluxes have been designed, researched and tested at the laboratory and plant scale. Fluxes are primarily a mixture of potassium chloride and sodium chloride with the addition of some other chloride and fluoride containing salts. The conventional Mining methods of potassium chloride and sodium chloride yield products that are not high in purity without costly reprocessing or additional refining. In 1993, Kalium Chemicals, Ltd. began supplying flux mixtures to the aluminum industry. Kalium produces potassium chloride and sodium chloride which are mined and refined by a patented solution-mining process. The salts produced by this process are high in purity with lower concentrations of iron oxide, sulfates, and other impurities. This paper will present the different mining methods used in the production of sodium chloride and potassium chloride. The paper Will address how these mining methods affect the purity of the final product as well as the effect of purity on the performance of the fluxing salt.

Jan 1, 1995

By J. W. Matousek

In the flash smelting of copper sulfide concentrates, the course of reactions from the burner tip, through flame "burn-out" (the point of oxygen depletion), to settled matte and slag is of particular interest in understanding the mechanisms of the process. Numerous reaction sets can be proposed to describe the chemical changes that might be taking place, but from outside the furnace no one set offers an obvious advantage in explaining the actual processes involved. Only a combination of mathematical modeling and flame and bath sampling can achieve this result. This paper shows that flash smelting, while still reasonably orderly, is a more complex process than suggested by the technical literature.

Jan 1, 1993

By I. J. Moon

The reduction behavior of hematite by H2 and H2-CO gas mixtures was investigated to elucidate the reduction mechanism at 800-950 °C. The hematite compacts were made by Cold Isostatic Pressing to produce compacts of uniform shape and size. The compacts were sintered at 1000° C for 30min, and showed a contraction of 29%. Mercury pressure porosimeter was used for measuring the total porosity, pore size distribution and pore surface area of the compacts. Reduction was measured by means of weight-loss technique using Cahn Balance (Model : TG-171, capacity log, accuracy f 10pg). Microscopic examination and X-ray analysis were used to correlate the structure of reduced compacts with the mechanisms of reduction. Neither chemical reaction control nor diffusion control is adequate in describing the complete course of reduction of the hematite compact. The reduction of hematite compacts was initially controlled by the chemical reaction at oxidelmetal interface. The reaction goes through a transition phase .where it is undergoing a mixed control, followed by the diffusion control towards the end of the reduction. The values of apparent activation energies for chemical reaction control were 3.48-8.43 kcal/mol depending on the gas compositions.

Jan 1, 1997

By Jinliang Zhang, Jian Pan, Deqing Zhu

"Limestone and burnt magnesite were added to vary MgO content and basicity (CaO/SiO2 ratio) of pellets for investigating their influences on the properties of specularite pellets. At fixed MgO content, the addition of limestone does not affect on the properties of green balls significantly. The addition of burnt magnesite has obvious influence on the quality of green balls, especially on the thermal shock temperature. Without burnt magnesite, the thermal shock temperatures are about 400°C, and, the thermal shock temperature increases to 600~630°C by adding burnt magnesite. For preheated pellets, when the burnt magnesite is added, the compressive strength will be decreased. For roasted pellets without burnt magnesite, the calcium additives can form binding phase of calcium-ferrite, and suitable liquid phase will improve recrystallization of hematite, but excessive liquid will destroy the structure of pellets, so the compressive strength of pellet increases firstly and then decreases. When adding burnt magnesite, the compressive strength will increase as the basicity increases. When the basicity is more than 0.2, the compressive strength of the pellets various MgO content and basicity is above 2500N/pellet and then MgO-bearing fluxes can be added to prepare pellets with good high temperature properties.IntroductionWith the rapid development of the steel industry in China, oxidized pellets, possessing good mechanical and metallurgical properties, are becoming indispensable burdens for blast furnace ironmaking [1-3]. However, this has resulted in the shortage of domestic iron concentrates, so many Chinese steel plants begin to use imported hematite concentrate to prepare pellets. Compared with magnetite pellets, the hematite pellets require high roasting temperature and narrow roasting temperature range (1300–1350°C) and possess low compressive strength [4,5].1"

Jan 1, 2012

By Donghai Li, Cheng Pan, Xuewei Lv, Mei Liu, Enguang Guo

"Phosphorite is the main raw material for the production of phosphorus in chemical industry. More attentions have been drawn to the phosphorite concentrate beneficiated from low-grade phosphorite due to the decrease of high-grade phosphorite. For another, the agglomeration process is necessary for the phosphorite concentrate after beneficiation process. The mineralogy and sintering process of the phosphorite from Leshan, China were studied in this work. The result shows that the main phases in the phosphorite are fluorapatite (Ca3(P04)3F), hydroxylapatite (Cas(P04)3(0H)), quartz (Si02) and dolomite (CaMg(C03)2). The yield of the sinter increases with increasing the carbon dosage to 7%, and then decreases when it continuously increases. Similar regularities were found for the strength and the content of P20s of the sinter. The best strength of the sinter as well as its P205 content were discovered when the carbon dosage is 7%. Fluorapatite ((Ca5(P04)3)F) is the main phase in the sinter while fuggerite (Ca2MgSiz01) is the main binder phase.IntroductionPhosphorus is an important foundation industrial raw material of national defense industry, food industry and chemical industry, where it is used to produce red phosphorus, phosphonium hydroxide, phosphorus pentasulfide and phosphoric anhydride[l-2]."

Jan 1, 2013

By Tiruttani Munikamal, Suresh Sundarraj

"A numerical model of the induction hardening process of steel cranks has been developed and the predicted results of temperature and phase distribution during this solid state phase transformation process are verified with experimental data from the literature. This heat treatment process involves heating the crank to the austenitic temperature range followed by rapid quenching in water to harden the surface of the crank. The model has been developed using ABAQUS, commercial FEA software. The formation of martensite, pearlite, and retained austenite phases are modeled and implemented through a user defined function in ABAQUS. A sensitivity study on the various process parameters affecting the amount of phase distribution has been carried out.IntroductionThe type of surface and sub-surface microstructure as well as the residual stresses that are present in a component after manufacturing, significantly affects it fatigue performance. The wear resistance of the automotive components such as crankshaft, gears, camshaft and bearings depends on the surface hardness. In order to achieve the surface hardness, these steel components are subjected to a type of quench hardening heat treatment process. There are several heat treatment processes available for the industrial application to improve the mechanical properties of the final part. Case hardening using induction heating is one of the widely used industrial techniques for improving the surface microstructure of a steel component. It consists of two stages i.e. induction heating cycle, followed by quenching in a fluid medium (usually water or oil)"

Jan 1, 2012

By Dai Yongnian

The methods of treating zinc crust and its development in the last hundred years are compared and reviewed. There are better effects from normal pressure metallurgy turned into vacuum metallurgy. The traditional methods dezinc only. But we must consider that delead on further step. From lab tests to industrial scale experiment are researched. The first step-dezinc, second-delead, crude ,metal of, zinc, lead and silver are produced, The flowsheet of treating zinc crust are simplified, material consumption reduced, work condition improved, environment protect mended. This method is pointed out that its application can be expanded.

Jan 1, 1992

By Saskia Duyvesteyn

For many applications in hydrometallurgy and water treatment it would be advantageous to use ion-exchange resins in stirred reactors. However, attrition of the resin may lead to significant losses of both resin and metal values and prevent water quality goals from being reached. We have studied the recovery of fine resin particles by froth flotation, using the model copper - Dow XFS4195 chelating resin system. As the functional group on the resin is a bis-picolylamine, the resin should be amenable to flotation by anionic collectors, such as sodium dodecylsulfate and sodium dodecylsulfonate. The kinetics of copper loading from dilute aqueous solutions in an agitated vessel were studied as a function of copper concentration, pH and resin bead size. The flotation of unloaded resin was investigated for different types of collector, collector concentration, conditioning time, and resin bead size. Potential applications are discussed.

Jan 1, 1995

By Renato G. Bautista

The solvent extraction separation of nickel, cobalt and their associated metals have been considered for industrial application since the early 1960's. This review of the solvent extraction processes is limited to the industrial applications, pilot plant and the more extensive bench scale studies reported in the literature. The processes with their significant chemical and technological contributions are discussed in detail whenever the information are available. The application of solvent extraction to the nickel-cobalt processing has so far been limited to the secondary separation of nickel-cobalt containing feedstocks derived from other primary nickel-cobalt separation methods.

Jan 1, 1993

A sinter plant baghouse dust has been treated as a hazardous solid waste, and disposed at a very high price. A series of leaching tests were conducted to examine the possibility to produce high grade potassium chloride from the solid waste. It is found that around 40% of the solid wastes can dissolve into water, and a deposit with more than 90% KCl can be produced after simply drying the solution.

Jan 1, 2009

By Marco Olper

The CX-EW technology, developed by B.U.S Engitec, is improved introducing besides the battery paste electrowinning, the direct electrorefining of metallic lead (grids and poles) obtained from CX breakers. This new concept of electrorefming the antimonial lead scrap is aimed to the production of 99.99 lead and of slimes with high antimony content, avoiding gaseous emissions in melting lead scrap, and expensive and pollutant thermic refining operations. In this way, practically all lead content in the battery is available as 99.99 lead, hence with a wider market for the lead recyclers. This paper will describe the tests performed on a pilot plant scale with special reference to the relatively low energy consumption of the process.

Jan 1, 1993

By M. Neises, M. Roeb, C. Sattler, S. Stenger

"A two-step thermo-chemical cycle process has been developed and investigated. It is based on metal oxide redox pair systems, which can split carbon dioxide as well as water molecules by extracting oxygen atoms and reversibly incorporating them into their lattice. If concentrated solar radiation is used as the heat source, a promising method exists to produce synthesis gas from water and CO2. An easy way of operation is gained by the combination of a ceramic substrate as the absorber structure, which can be heated to high temperatures with concentrated solar radiation, and of a metal oxide coating which is capable to carry out the redox reactions. The performance and kinetics of a ferrite based redox material coated on ceramic substrates were investigated in a laboratory set-up. CO2 could be reduced with significant conversions. In addition, several side reactions were observed like the formation of carbon and like the Boudouard reaction.IntroductionThe search for alternative energy carriers and for processes able to reuse carbon dioxide stimulates the research for sustainable routes of alternative fuel production. In the scope of this search thermo-chemical processes combined with sources of concentrated solar energy have become more and more attractive. Ideally, the only raw materials for such processes are water (H2O) and carbon dioxide (CO2) enabling not only a process free of emissions, but also allow to reduce emissions of other processes by reusing CO2 to provide synthesis gas, which itself can be applied to produce chemical commodities or even better synthetic fuels like methanol or petrol.In contrast to the direct splitting of those raw materials, thermochemical cycles split water and CO2 in several steps and enable hydrogen (H2) and carbon monoxide (CO) generation at temperatures controllable by today’s technical equipment. One of the most interesting thermochemical cycles is a two-step process using metal oxide based redox systems. During the first step of this cycle (the regeneration step) the metal oxide is reduced setting some of its lattice oxygen free according to reaction (1). In the next step (the splitting) the reduced and activated material is oxidised by withdrawing oxygen from water and CO2 and at the same time hydrogen and CO is set free according to reactions (2a) and (2b) respectively."

Jan 1, 2011

By David Forrest

In 1981, K. E. Drexler proposed using massively parallel nanomechanical systems to manufacture large atomically exact structures. As in macroscopic mechanical systems, they would contain components that serve traditional functions such as trusses for support, gears to transmit power, bearings for low-friction support of rotating surfaces, motors to supply torque, pipes and conveyor belts for material transport, and channels for coolant. Many of these components would only contain a few thousand atoms. Specific designs for these devices became available in the early 1990s, and a few working devices appeared in laboratories by the early 2000s. As advances continue, a thorough understanding of the operative transport phenomena will guide the intelligent design and construction of nanomechanical structures, devices, and systems. The familiar equations of continuum mechanics are generally inadequate to describe the flow of heat and mass in the proposed nanosystems. Boundary conditions often need to be described in terms of potential surfaces. Surfaces are not geometrically smooth, but periodic according to the locations of atomic nuclei. Friction occurs not due to the plastic deformation of asperities on mating surfaces, but to phenomena such as thermoelastic damping and phonon viscosity when atoms slide past each other. Electrostatic forces dominate over gravitational forces by orders of magnitude; there is no role here for natural convection. Structural components, no matter how stiff and strong, are in constant motion due to the thermal noise in the system. The fluids are described in terms of individual molecules in constant motion.

Jan 1, 2006

By David T. Bunney

In .December of 1987, International Mill Service, Inc. signed an exclusive licensing agreement with Tetronics Research & Development Co. Limited of Faringdon, Oxfordshire., England to commercialize plasma technology which had been demonstrated in an EAF dust processing application. The intent of the process is to reduce and volatize the zinc, lead and cadmium oxides inherent in EAF dust and collect these elements as metals in an ISP (Imperial Smelting Process) zinc splash condenser, and to render the resultant slag an inert, non-hazardous material. With these objectives in mind, IMS started commissioning facilities in 1989 at Florida Steel in Jackson, Tennessee and Nucor-Yamato Steel in Armorel, Arkansas. This paper will address the commercial development and progress of the technology at these two installations. Process Description In the EAF steelmaking process typically the off gas stream is cleaned by some form of baghouse. The particulate collected is known as Electric Arc Furnace dust and has been designated by the U.S. EPA as hazardous waste number K061, once it leaves the collection system. This designation was given to the material due to the high toxic concentrations of lead and cadmium (nickel and chromium for stainless EAF dusts) inherent in the dust. IMS' method of operation is to locate the facilities on the client mill's property adjacent to the baghouse. The dust is transported directly to IMS via a closed conveyance system. This method enables the technology to be an additional processing step in the steelmaking process. Once the dust has been transported to the IMS facility, it is fed, metered and mixed mechanically in the feed conveyance system with a carbon reductant (typically coke breeze). The carbon reductant is approximately 10% of the dust feed rate. This mixture passes through the feed system and enters the furnace

Jan 1, 1992

By Hongbo Zhao, Jun Wang, Wenqing Qin, Guanzhou Qiu, Xueduan Liu

Bio-hydrometallurgy technology was applied for the extraction of copper from the raw ores of Chambishi Mine in Zambia. A copper extraction of 93.29% was obtained for small scale column bioleaching within 63 days, while a copper extraction of 89.05% was achieved for large scale column bioleaching in 90 days, thus confirming the amenability of the raw ores for effective extraction via bioleaching. The bacteria were cultured in a 6-stage enlarge cultivation. The bacterial cultures with cell concentration of more than 1×108 cells/mL were added into a spray pond of sulfuric acid to be applied in the dump leaching, and a copper extraction of about 50% was achieved within 2 months. The production report revealed that the copper extraction increased by approximate 20%, and the acid consumption was reduced to around 35% as a consequence of adding the bacteria. The industrial demonstration of the bio-hydrometallurgy technique is now well established in Zambia, and further applications of bio-hydrometallurgy in both Zambia and Congo are currently in progress.

Jan 1, 2015

By Wei Luo, Yuanbo Zhang, Zhixiong You, Zijian Su, Guanghui Li, Tao Jiang

"In this study, the appropriate sintering process parameters for low-grade ferromanganese ores were investigated. The results showed that, under the condition of natural basicity (R=0.03), the optimal parameters were obtained as follows: moisture of mixture 9 .1 %, coke powder 9 .9% and sintering negative pressure 7 KPa. And the corresponding yield, ISO tumbling index and utilization coefficient reached at 80.18%, 61.27% and 1.515t·m-2·h-1, respectively. Under the optimal parameters, the emission of harmful gases, such as S02 and NOx, were reduced evidently with 30% of coke powder replaced by biomass charcoal. Moreover, it was found that the basicity had obvious effects on the quality of the sinters when it changed between 0.03 and 2.4. The ISO tumbling index gradually decreased from 61.27% to 55.47% with the basicity increasing from 0.03 to 1.2, then, it began to increase after the basicity further increased to 2.4.IntroductionManganese is mainly consumed by steel and battery industries, particularly in the steel plants and ferroalloy units. The consumption of metal manganese in the ferroalloy industry accounts for 85%-90% of the total Mn [1-2]. Therefore, ensuring sufficient manganese alloys is essential to meet the rapid development of steel industry. Recently, rich-manganese slag containing high grade Mn (>40%), low Fe (1%) and P (<0.03%) is considered as superior raw materials for manganese alloys. While the sinters made from manganese ores are major raw materials for producing rich-manganese slag with the increasing exhaustion of natural rich manganese lump ores [3-5]."

Jan 1, 2013