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By Merete Tangstad, Ragnar Tronstad

Ferromanganese production in electrical furnaces is quite an old process. However, as the furnaces are getting bigger, the requirements of cost, yield, product quality, emissions and security are raised. With the increased expectations, the fundamental knowledge must follow. Within the last 25 years there has been a great effort both in the industry as well as the academic environment to push the limits of this process. This article will show some examples of improvements within fundamental data, reaction mechanisms and emissions over this time period.

Jan 1, 2014

By T. T. Chen, J. E. Dutrizac

Noranda Inc., CEZinc presently employs a cement-stabilization (jarofix) process to stabilize its jarosite residues for direct disposal. In this process, Portland cement partly decomposes Na-jarosite to form Ca6Fe2(SC>4)3(OH)i2.nH20, ferric hydroxide and sodium sulphate which further reacts to form gypsum; approximately one-third of the Na-jarosite reacts in the current commercial product. The cured jarofix products also contain minor amounts of various Ca-Al-Fe silicate-sulphate-hydrate phases and traces of calcite. Together with gypsum and a Ca-Fe sulphate phase, these species bond the various particles together, imparting mechanical strength and reducing the permeability. Water-soluble Zn and Mg are stabilized in the Ca-Al-Fe silicate-sulphate-hydrate phases. The freshly cured products usually contain small amounts of moisture and traces of residual Portland cement, which provides additional alkalinity for the neutralization of any residual acid species. Jarofix products stored for more than six years in the laboratory, after curing, are usually dry and exhibit the same micro-textures as those of the freshly cured products. However, the stored products are depleted in the Ca6Fe2(S04)3(OH)i2.nH20 and Portland cement phases, and are enriched in gypsum and calcite which reflects the highly alkaline environment of the jarofix products. The aged products also have increased amounts of the Ca-Al-Fe silicate-sulphate-hydrate phases which have elevated Zn and Mg contents. This implies a further immobilization of residual water-soluble Zn and Mg during stora

Jan 1, 2000

By T. T. Chen

Hydrometallurgical products are difficult to characterize because of their fine grain sizes, heterogeneity, often amorphous structures and water soluble or hydrated constituents. Such products are advantageously studied using complementary mineralogical techniques including >50, ore microscopy, SEM-EDX, electron microprobe analysis, selective leaching and wet chemical analysis to determine the phases and their morphologies, to identify specific element carriers, and to elucidate the chemical reactions occurring during the metallurgical process. Sample preparation is an important consideration for these materials. For extremely fine-grained particles, or soft and brittle products such as elemental sulphur, the study of loose powder mounts provides information not available from the examination of polished sections. To demonstrate the application of the various mineralogical techniques, commercial zinc roaster calcines and leach residues, copper refinery anodes and anode slimes, and laboratory bornite leach residues were examined in detail. The various sample preparation and mineralogical methods are presented, and the use of these complementary and practical mineralogical techniques to improve the understanding of a particular hydrometallurgical system is discussed.

Jan 1, 1989

By Ann M. Hagni

Flash reduction of zinc oxides is an alternative, environmentally safe method to leaching and electrowinning for zinc recovery. Zinc and lead are volatilized in a flash reactor, a non-hazardous residue is generated, and the fuel source is inexpensive coal in the flash reduction process. Results from experimental laboratory tests yielded low zinc recovery for this process. Mineralogical and textural characterization of the residues from the flash reduction tests for different feed materials and temperatures were conducted to determine the cause for the low zinc recovery. Reflected light microscopy, cathodoluminescence microscopy, scanning electron microscopy-energy dispersive spectroscopy, and X-ray diffraction were utilized in this applied mineralogical research. The original zinc calcine is composed primarily of fine-grained, iron-bearing zincite particles, 25-40 um in diameter, in a porous texture. Pellets processed at 1150°C were found to produce reaction rims of franklinite-magnetite-jacobsite solid solution that are 125-200 um thick and surround cores of unreacted iron-bearing zincite in a Zn-Fe-Si-Ca glass matrix. The reaction rims have subsequently oxidized to form an outer 10 ~m thick rim of hematite. Slags from calcines processed at 1275°C are primarily triangular particles with porous centers, cenospheres, and spheres of iron-bearing zincite, in addition to rectangular particles composed of non-porous franklinite-magnetite solid solution cores with iron-bearing zincite rims. Slag particles from calcine processed at 1200°C are predominantly 100-250 ~m triangular-shaped, spheres, and cenospheres containing fine-grained franklinite and franklinite-magnetite solid solution in an iron-bearing zincite matrix. Slag from calcine processed at 1300°C are also predominantly 1 00-250 um triangular-shaped, spheres, and cenospheres but contain coarser-grained iron-bearing zincite. The zincite in the penets and the slags typically contain 10-20% iron. Based upon these mineralogical observations, it is concluded that the significant amounts of iron in the zincite prevent volatilization of the zinc in the flash reduction process.

Jan 1, 1995

By S. C. Sharma

The aluminium matrix composites with ceramic dispersoids can be separated by density difference concept. In the proposed work composite scrap is recycled using an oil fired furnace. The scrap is melted in the furnace and temperature is maintained below 740 degree centigrade. Because of the density difference the lighter dispersoids will float and heavier dispersoids will settle down. The clean melt is separated be removing the floating and settled disperssoils, and then filtering using ceramic filters.

Jan 1, 1995

By Stephen K. Pave1

Over 1,100 tons per day of Fluid Catalytic Cracking Unit (FCCU) catalyst is used worldwide. During the cracking reaction, catalyst is contaminated by deposited metals including nickel, vanadium, potassium, copper, iron, sodium, etc. To compensate for contaminants, a portion of the circulating catalyst inventory is withdrawn for disposal and fresh catalyst is added. The DEMETR process takes spent FCCU catalyst and removes a portion of the metal contaminants, enabling the refiner to recycle demetallized catalyst, thus reducing the solid waste from the refinery. Through August, 1993, the operation of one unit for one refiner has resulted in the recycling of over 7,500 tons of spent catalyst.

Jan 1, 1994

By Shigehisa Endoh, Hitoshi Ohya, Atsushi Inaba, Shigeki Koyanaka

"Recycling should be promoted to keep the global environment. However, it is difficult to detennine the quantitative impact. A life cycle assessment is one of the most reliable methods to estimate the global environment impact.Exergy is useful like entropy when considering the sustainable development. All of our activities have been obtained exergy resources and/or energy itself and throw away waste and/or waste heat. We are trying to use exergy to estimate the quantity of energy and matter for resource accounting. For recycling plastic, plastic has two aspects; material and energy source.The environmental assessment of plastic recycling suggests that the exergy reduction of the entire system is estimated by the yield of matter and the process efficiency. The material recycling is better than the thennal recycling when the process efficiency is high. However, the thennal recycling is much better for the low efficiency. The transition point is able to be decided by the efficiency of the manufacturing and the electric power generation.IntroductionRecently, many of the global environmental problems have become conspicuous like global wanning, ozone layer depletion and acid rain. Some of the methods like life cycle assessment for solving these problems have been presented. Anxiety concerning the proble1ns of energy and resources has led to a rapid increase in the interest in describing and understanding the conversion processes of energy and other resources in today's society. All human activity is supported by obtaining power and products of high exergy from the environment and throwing away the waste material and the waste heat of low exergy back the environment. However, the total exergy in the whole system becomes absolutely smaller than before.The rate of obtaining high exergy products and energy itself by human activity and the speed, by which waste and waste heat having low exergy are thrown away are too fast to attribute to environmental problems [1-3].A material's use by recycling was often common in a circulating society mainly. A significant amount of energy is consumed during circulation. An environmental impact assessment method for the process or the system has not been devised when both of them are taken into consideration. Even if the life cycle assessment evaluation, which has been correctly used up to now, is applied, it is not sufficient for an overall evaluation concerning matter and energy.The real sustainable development is that the exergy reduction value by all human activities on the earth is kept within the range of the exergy reduction in order to consider the earth as closed stationary system. It is important to evaluate the process or the system by using the exergy, and design them so that the exergy loss may decrease as much as possible. We have to consider what process improvement is the most effective."

Jan 1, 2000

By I. Kim, J. C. Choi, W. D. Cho

"The effect of yttrium addition on the oxidation behavior of Fe3Al intermetallic compound was investigated in the range of temperature 800 to 1100 °C in 0.2 atm 02 in terms of oxidation rate and oxide adhesion. The oxidation rate of alloys, Fe-14.3 wt% Al and Fe-14.1 wt% Al-0.3 wt% Y, was nearly identical and the parabolic rate constant calculated as a function of temperature is Kp=5128 exp[-39506(cal/mol)/RT] mg2/cm4 hr.Rapid cooling and ultrasonic stress tests were carried out to test adhesion of scale formed on the alloys. While the oxide layer formed on the Fe-Al alloy without Y was found to be fragile and detached easily during the tests, the oxide layer formed on the Fe-Al alloy containing Y was protective, dense, and adhesive. The following two mechanisms were proposed to explain the adhesion improvement of Ah03 formed on the Fe3Al containing yttrium : (1) the addition of yttrium decrease generation of growth stress in alumina scale because the preferential diffusion of yttrium through grain boundary in alumina scale prevent internal oxidation of Al, one of main causes of growth stress, and (2) the second phase formed on the oxide scales prevents crack propagation through the scales, leading to better mechanical stability of the oxide scales.IntroductionIron aluminides have attracted the attention of many researchers as a candidate for use at high temperature because of their excellent oxidation resistance due to the formation of protective alumina scale. In order to resist aggressive environments at elevated temperatures, oxide scale formed on iron-uluminum alloy must satisfy the following three requirements : (1) thermodynamic stability (2) slow growth rate (3) adherence on substrate. According to Wallwork and Hed [l], the most suitable alloys for high temperature application are Fe, Ni, and Co alloys with the protection of Si02, Cr203, and Ah03 scales. While chromium oxide can vaporize as Cr03 above 1000 °C and silicon oxide may form low melting silicate [2,3], Alz03 has a high melting point and is the most stable among the three oxides thermodynamically [6]. In this respect, iron aluminides forming alumina seem to be most suitable for use at high temperature. However, alumina scale formed on the iron aluminum alloys tends to be easily spalled during oxidation due to the combination of growth stress and thermal stress."

Jan 1, 1998

By B. S. -J. Kang, M. A. Alvin, J. M. Tannenbaum

"A load-based micro-indentation technique has been developed for damage assessment and non-destructive spallation detection of TBCs at room temperature. This micro-indentation technology has been further extended to the development of a high temperature (HT) test methodology. Elastic modulus calibration tests performed on Hl 3 Tool Steel to 500°C and Haynes 230 at 1000°C displayed excellent agreement with reported values. Moreover, indentation creep tests of Haynes 230 at 1200°C were found to be in agreement with known creep exponents as well. Finally, a HT thermal flux indentation apparatus was assembled for conducting TBC turbine component testing under high temperature moisture-containing environments (= 50% steam with controlled gas content temperatures up to 1250°C). Description and design considerations of this test apparatus are discussed. Preliminary tests of ReneN5/MCrAlY/APS TBC coupons in steam/air environments with in-situ HT micro-indentation testing are conducted. Furthermore, the coupon is removed and examined for damage assessment at periodical intervals.IntroductionLoad and depth relationships acquired throughout the indentation process provide insight to material mechanical properties such as elastic modulus and hardness. Unloading segment analysis of these load displacement curves are utilized in the acquisition of a material's elastic properties. Yet, indentation tests are complex processes involving contact mechanics, material nonlinearity and even fracture mechanics. Thus exact analytical solutions for these processes are difficult to obtain. As a result, much of the current knowledge regarding the indentation process has been acquired through experimental methods and finite element simulations. Initial efforts by Tabor resulted in the application of spherical indentation to obtain post-yielding stress/strain relationships [1]. Soon thereafter, analytical load-depth relations for elastic indentation were developed [2], yet it was Lure who further derived the explicit relationships for both spherical and conical indenters [3]. Improving upon this, these interactions were later extended to indenters with various geometries by various researchers [ 4]. Additionally, by establishing the linearity of the initial unloading slope within the load-depth curve, a relationship between elastic indentation depth, maximum load, unloading slope and indenter geometry was established [5]. From this a theoretical method by which elastic modulus could be determined was established."

Jan 1, 2011

By Torben L. Edens

Norddeutsche Affinerie is the largest copper producer in Europe. Two sites are in operation for the production of refined copper: primary copper production is located in Hamburg and secondary copper production in Lünen. A total of just under 560,000 tonnes of copper cathodes is produced annually at the two sites. Primary copper production using the flash smelter furnace has been in operation in Hamburg since 1972. Over the years, the capacity of the flash smelter has been increased in three expansion projects from 120,000 t to almost 500,000 t of anode copper p.a. The anode sector consisting of two anode furnaces and a 24 mould casting wheel still features just about the same equipment as in 1972. The paper describes the most important steps taken to optimise operation which have put NA in a position to cast meanwhile more than 500,000 t of anode copper annually with the two anode furnaces and 24 mould anode casting wheel.

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2 versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Pekka Hanniala

The Outokumpu Flash Smelting process today is the most feasible method for copper matte smelting. The economic feasibility of the process has always been one of the main decision making criteria in smelter projects. Thus, today about 50 % of the world primary copper production utilizes Outokumpu Flash Smelting Technology. However, in the future, environmental criteria will have stronger and stronger impact on decision making. Flash Smelting technology offers the best pollution control features of any process. today. It is foreseen that, in the near future, the global trend will be that all the smelters must decrease their emissions at an accelerating rate, compelling the smelters to make increasingly larger investments on environmental protection. In most of smelters ?today, Peirce-Smith converting and transfer of the molten material in ladles are the number one pollution source. The key today for copper converting and minimizing emissions is the Kennecott-Outokumpu Flash Converting process, which has proven to be the most effective converting method in terms of pollution control and, production efficiency including capital and operational costs. Outokumpu Flash Smelting technology is applicable also for small to medium scale smelters but the most interesting area is the upper capacity limit for smelting in one line, which has not yet been reached. We predict that by the year 2000 to 2005, there will be at least one smelter which produces 500,000 tonnes of Cu per year based on one Flash Smelting and Flash. Converting unit. The current state-of-the-art of the Outokumpu Flash Smelting - Flash Converting process is presented in this paper as well as some new options for copper production to be utilized in the near future but which are available already today.

Jan 1, 1998

By Charles H. Buclmam

"Environmental regulatory requirements for discharge of solutions and closure of operations for the gold mineral processing industry have been gradually lowered and in certain instances have been targeted to USEP A inorganic drinking water standards for dissolved ions in solution. The use of jar tests for water treatment process development is suitable for preliminary scoping work to be conducted in the research laboratory, as well as for optimization studies at the site of the treatment requirement. This paper will describe experimental methods which were performed using standard jar test equipment in efforts to produce solutions which meet USEP A inorganic drinking water standards after chemical treatment of cyanide solutions. The materials tested included gold bearing pregnant solutions from heap leaching operations, gold plant barren solutions from the Merrill-Crowe zinc cementation gold recovery process and gold heap leach wash solutions after carbon-in-column gold recovery. Experiments included cyanide destruction with sodium hypochlorite and arsenic and selenium co-precipitation coupled with mercury precipitation.IntroductionCyanide leaching solutions are used to selectively dissolve metallic gold from commercially viable mineral deposits. The heap leaching process involves stacking of gold bearing ores on specially designed solution containment pads and percolating alkaline cyanide solutions through the ore to dissolve the gold. Pregnant solutions containing the dissolved gold are collected and sent through a gold recovery process. After selective recovery of the gold, the barren solutions are recycled to the gold extraction process after adjustment of the solution alkalinity and available cyanide concentrations."

Jan 1, 1997

By N. Shi, T. C. Lowe, S. J. Zhou, M. L. Lovato, Y. T. Zhu, J. A. Valdez, W. R. Blumenthal, M. G. Stout

"A major problem of short-fiber composites is that the interfaces between the fiber and matrix become a limiting factor in improving mechanical properties such as strength. For a short fiber, a strong interface is desired to effectively transfer load from matrix to fiber, thus reducing the ineffective fiber length. However, a strong interface will make it difficult to relieve fiber stress concentration in front of an approaching crack. Stress concentrations result in fiber breakage. We report in this paper an innovative approach to overcome this problem: reinforcement morphology design. Short-fibers with enlarged ends are processed and used to reinforce a polyester matrix. The initial results show that the bone-shaped short-fibers produce a composite with significantly higher strength than can be attained with conventional short, straight fibers.IntroductionThese interfaces between the fiber and the matrix in short-fiber composites play a critical role and, in many cases, become a limiting factor in improving such mechanical properties as strength and toughness of the composites (1-4). For a short fiber, a strong interface is desired to effectively transfer load from matrix to fiber. A stronger interface can reduce the ineffective length at both ends of the fiber and, therefore, can increase the effective length that carries load (5-9). However, with a strong interface it is difficult to relieve fiber stress concentration -in front of an approaching crack; and such stress concentration can result in fiber breakage (10, 11). This effect is particularly severe for ceramic matrix composites, because of their low matrix toughness and lack of plasticity. Even for a composite with a highly ductile matrix, such as plastics, too strong an interface may still cause successive adjacent fiber breakage and subsequently reduce composite toughness (1, 11). On the other hand, a weak interface significantly decreases the fiber load-carrying length due to ineffective load transfer and complete fiber interfacial debonding and pullout during loading. A compromise in the interfacial bond strength will also compromise the load-carrying potential of short fibers."

Jan 1, 1998

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006