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By W. G. Davenport

The remainder of this book develops and uses mass and heat balances to describe steady"state flash smelting. Its objectives are to: a) describe the many ways a flash furnace operator can produce specified products, e,g. 65% eu matte, 35% SiOz slag, 1500 K (b) determine the oxygen, air, flux and hydrocarbon fuel requirements of each method (c) show how the flash furnace can be controlled to give specified products with varying feed compositions (d) suggest how the flash furnace operator can maximize profitability while producing specified products. This chapter develops the basiC heat and mass balance equations of steady-state ?flash smelting. It then adapts the equations to industrial feed materials .and products. Lastly it determines the amounts of oxygen and flux needed to produce molten matte and 35% SiOz slag from chalcopyrite concentrate in an Inco oxygen flash furnace,

Jan 1, 2001

By Chaoying Ni, Dimitry Sediako, Prashant Karandikar, Sean Fudger

Neutron diffraction measurements were performed on steel encapsulated metal matrix composites (MMCs) in order to quantify bulk residual stresses. A coefficient of thermal expansion (CTE) mismatch induced residual compressive stress method is utilized as a means of improving the ductility of the MMCs and overall efficiency of several macro hybridized materials systems. Systems consisting of an A36, 304 stainless steel, or Nitronic® 50 stainless steel shell filled with an Al-SiC or Al-Al2O3 metal matrix composite are evaluated in this work. Upon cooling from processing temperatures residual strains are generated due to a CTE mismatch between each of the phases: steel, aluminum, and reinforcement. The analysis shows variation in the measured strain and stress results due to outer steel thickness, difference in CTE between materials, and relative position within the composite.

Mar 1, 2017

By Guo Chen, Jin Chen, Jinhui Peng

"In this paper, the methods of life cycle assessment for microwave hot air systems, and the concept of green degree were proposed. Greenness evaluation index, evaluation system and evaluation model of microwave hot air systems were established. Also, life cycle assessment processing based on these ideas was introduced. Analytic hierarchy process and fuzzy decision- making method were utilized to establish and solve the greenness evaluation of assessment model, while the scores of green degree in microwave hot air systems were obtained. The results show that Life cycle assessment can be applied effectively and efficiently to the microwave hot air systems.IntroductionHot air systems are an important industrial operation condition, which is used to provide high temperature air for materials processing. Nowadays, high temperature airs are manufactured by the conventional heating processes, in which some ceramic materials are used as heating materials. However, these processes pollute the environment. Therefore, to explore new method to produce high temperature air with low energy consumption and less environment pollution are necessary.Microwaves are now being used in various technological and scientific fields in order to heat dielectric materials [1]. Microwaves irradiation has been explored in materials processing in recent years [2-3]. The main advantage of using microwave heating is that the treatment time can be considerably reduced, which in many cases represents a reduction in the energy consumption as well. Since there is energy absorption but no heat conduction, the heating is very rapid and highly efficient, resulting in energy savings and the shortened processing time [2, 4]. Compared with conventional heating techniques, the additional advantage of using microwave irradiation is that microwave irradiation achieves both internal and uniform heating [5-7]. In addition, it is more convenient to control the microwave irradiation processing, because of no direct contact between the heating source and heated materials with less equipment size and waste [2, 8-9]. Life cycle assessment is used and accepted methods for the evaluation of the environmental impacts of products or systems [10]. Recently, many appropriate evaluation methods have been developed for life cycle assessment [11-12]. These proposed methods usually are employed for the evaluating product and analyzing results [13]. Among them, the analytic hierarchy process and the fuzzy comprehensive evaluation stand out as a popular method utilized in many fields [14-16]. Analytic hierarchy process and fuzzy comprehensive evaluation are a combination of mathematical and statistical technique that is useful for analyzing the effects of several independent assessment aspects on the system goal without the need of the predetermined relationship between the objective function and the assessment aspects [17-19]."

Jan 1, 2013

By Isabela Leao Amaral da Silva, Felipe Perisse Duarte Lopes, Alice Barreto Bevitori, Sergio Neves Monteiro, Ruben Sanchez Rodriguez

"The fibers extracted from the stem of the ramie plant are among the strongest natural lignocellulosic fibers with a potential to be used as reinforcement of polymer matrix composites. Characterization of the ramie fiber has recently been conducted for its physical and mechanical properties. However, the effect of increasing temperature on the ramie fiber behavior has not yet been fully investigated. Therefore, the objective of this work was to perform a thermal analysis on ramie fibers with different diameters within the naturally found range of practical interest. The analysis was conducted by thermo-gravimetric, TGA and DTG, as well as differential scanning calorimetric, DSC, techniques. It was found that the ramie fibers present thermal stability up to 200°C and then suffer a sharp deterioration between 300 and 500°C, resulting in characteristic peaks.IntroductionSince the middle of last century, polymer composites have substituted many conventional monolithic materials in applications ranging from aerospace to sport [l]. The main advantages of these composites are the low density and flexible properties specially using fiber as reinforcement to suit the mechanical performance requirements [2]. These are usually high strength and stiffness requirements that could be reached with synthetic fibers such as glass, carbon and aramid fibers. In recent years, however, the use of synthetic fibers is being questioned in terms of problems caused to the environment. In fact, as non degradable material, synthetic fibers are associated with long term pollution when discarded. Moreover, the expended energy for fabrication and processing can be related to relatively large amounts of C02 emissions and represents a contribution to global warming [3]. Glass fiber, in addition, is toxic and cannot be incinerated as a waste in thermal power plants [ 4]. Possible substitutes for glass fiber are the natural fibers. Many natural fibers are today being considered as viable alternatives to replace glass fiber as reinforcement of polymer composites. In particular, some natural lignocellulosic fiber extracted from plants present a real potential for this replacement [2-8]. Their comparative advantages are lower density and reduced cost as well as renewability, biodegradability, recyclability and neutrality with respect to C02 emission [3]."

Jan 1, 2011

By Dachun Liu, Xutao Guo, Wenlong Jiang, Baoqiang Xu, Bin Yang, Yong Deng, Heng Xiong

Typical copper dross, the byproduct of lead bullion pyrometallurgical refining for copper removal, mainly contains Pb, Cu, S, As, Sb and Sn etc. In traditional treatment process, copper dross is transformed to be copper matte by smelting with iron scarp and iron pyrite. Here, a new treatment process of converting-vacuum distillation (CVD) was proposed and investigated. Based on this concept, the converting process was tentatively investigated in this paper. The results of element distribution of converting samples showed the sample has three layers. The upper layer is mainly sulfides of lead and copper, the middle layer is mainly copper arsenide, and the lower layer is lead arsenide and crude lead. On the condition of oxygen flow rate 400 ml/min, the converting temperature 1000 °C, the holding time 1 h, the converting time 10 min, the lead copper alloy containing 0.17% S was obtained.

Mar 1, 2018

By H. H. Kellogg

The thermochemical properties of molten solutions in the binaries Cu-Bi, Cu-Sb and Bi-Sb, as well as the ternary Cu-Bi-Sb, have been correlated and described in mathematical form by use of the associated species concept combined with the three-suffix Margules equations to account for the non-idea 1 behavior of the solution species. Agreement of the correlations with experimental data is excellent (relative deviation of less than 2.5% in the values of the activity coefficients) in most cases. The correlations are applicable over the entire composition range of each system, and in the temperature range 700°-1250°C.

Jan 1, 1985

By Mohamed Y. Bakr, Aly M. Abdel-Rehim

The present work is related with mechanical activation of processing of Egyptian wolframite by simultaneous ball-milling and pressure alkaline leaching, to improve the recovery of tungsten from wolframite. The results show a total recovery of tungsten from wolframite (97.8- 98.7%) by simultaneous ball–milling and alkaline leaching at temperature 175-200oC. It is concluded that processing of wolframite by simultaneous ball- milling and leaching is mechanically activated and accelerated as a result of the grinding action of steel balls that caused the immediate rupture by continuous removing the product layer of the reaction ( sodium tungstate and iron and manganese hydroxides ) from reacting particle surfaces. This leads to the exposing of fresh and activated wolframite particle surfaces to alkaline leach solution and consequently the acceleration of the reaction of wolframite leaching .The results of the kinetic study 0f alkaline processing of wolframite and its mechanical activation show that the system is under kinetic control.

Jan 1, 2015

By Tianzu Yang, Weifeng Liu, Lin Chen, Deyu Wang

"Due to the gradual exhaustion of easily extractive gold ores, it is vital to make efficient use of refractory gold ores which hold 30% gold storage of the world. However, the disadvantage of current processing technologies for refractory gold ores consists of severe pollution, low gold extraction ratio, high investment, etc, thus great research interests were attracted during recent years. This article provides an overview of the distribution and categories of the refractory gold ores in the world. The state of art in processing refractory gold ores by pyrometallurgy, hydrometallurgy and biometallurgy techniques and their industrial applications are highlighted. Potential environmental conservative techniques for efficient gold extraction are also reviewed.IntroductionResources of Refractory Gold OresAs easily extractive gold ores are going to be exhausted with the large scale mining nowadays, refractory gold ores are becoming more and more important. Gold in the refractory gold ore cannot be fully extracted using conventional method (cyanidation) even with fine grinding. The amount of gold in the refractory gold ores is about 1500~2000t in China, which occupies 30~40% of the total gold storage [1]. Therefore, it is vital to make efficient use of refractory gold ores."

Jan 1, 2013

By Olga Slavkina

A new technology of bacterial leaching by means of the Thiobacillus ferrooxidance bacteria is proposed. The equations of reactions that describe of the first and the second stage of bacterial leaching of sulfide raw materials containing non-ferrous metals are given. The theory is analyzed and the technology of processing of some complicated substandard concentrate containing copper and zinc is proposed. The main technological operations including a two-stage bacterial leaching and stages of copper and zinc recovery in the form of marketable product are described. The results of the experimental validation of the main technological parameters of the first stage are given. The main possibilities of a more complete zinc and copper recovery at the second stage of bacterial leaching are discussed in comparison with single-stage leaching process.

Jan 1, 2003

By Chen Tian, Tingfeng Wu, Qinghai Pang, Junhong Zhang, Zhijun He

Microwave technology as new aided tool has been applied on waste water treatment and metallurgical fields. This paper explores the affected factors such as microwave power, microwave irradiation time, polyaluminium chloride (PAC) amount and addition of phosphoric acid on treatment of Blast Furnace gas washing water by utilization of coagulation associated with microwave. Through the orthogonal experiment, the optimum experimental parameters were obtained in the course of treatment of 300 ml Blast Furnace gas washing wastewater: 396 W microwave power, 2 min of microwave irradiation time, 0.12 ml Added PAC and 0.8 ml added phosphoric acid. It indicates the affected factors in descending order on removal of SS in BF gas’s washing water: Added PAC level, added phosphoric acid level, time of microwave irradiation, and microwave power while those parameters that can affect suspended solids(SS)’s hardness reduction in descending order are added phosphoric acid level, added PAC level, time of microwave irradiation, and microwave power. Also, it demonstrates those parameters that can affect washing water’s turbidity in descending order: Added PAC level, time of microwave irradiation, added phosphoric acid level, and microwave power. The results showed that PAC coagulation associated with microwave on treatment of Blast Furnace gas washing wastewater has several benefits: short treatment time, strong sedimentation velocity and other excellent characteristics, it can effectively remove suspended solids in wastewater, the SS hardness and turbidity can be reduced.

Mar 1, 2017

By Manis Kumar Jha, D. D. Pathak, Rekha Panda

Platinum Group Metals (PGMs) play a significant role in the manufacturing of catalysts, super alloys, electronics, space materials, biomedical equipments, jewellery, etc. due to their excellent electrical and thermal conductivity as well as chemical resistivity. The rising demand of PGMs in industrial applications and their limited natural resources have laid emphasis on the development of feasible and eco-friendly processes for the extraction of these metals from different sources to meet their future requirements. Present review reports commercial processes based on pyro-/hydro- and hybrid techniques to recover PGMs from various resources. The salient findings on different processes used for recovery of PGMs have been reviewed with respect to various methodologies and objectives.

Mar 1, 2018

By John R. FitzPatrick

The separation and purification of uranium from either nitric acid or hydrochloric acid media tan be accomplished by using either solvent extraction or ion-exchange. Over the past two years at Los Alamos, emerging programs are focused on recapturing the expertise required to do limited, small-quantity processing of enriched uranium. During this period of time, we have been investigating ion-exchange as a method for extraction/purification of uranium from acidic media. In addition, waste stream polishing is associated with this effort in order to achieve more complete removal of the uranium prior to recycle of the acid. Extraction chromatography has been demonstrated' to further polish the uranium from both nitric and hydrochloric acid media thus allowing for a more complete recovery of the actinide material and creation of less waste during the processing steps. We will discuss contact experiments for evaluation of eleven different resins for uranium removal from nitric acid, the evaluation (again by contact experiments) of uranium elution from the ion-exchange media by various chemicals, and small-scale experiments for the removal of 235U from nitric acid. Larger-scale (100-gram) flow experiments using depleted uranium, were done after the small-scale evaluation Of the selected resin. A discussion is also included concerning the shortcomings of the contact experiments and how the flow experiments were modified in order to overcome these problems. We will also discuss the application of ion-exchange for some specific process needs at Los Alamos Contact experiments were used to evaluate some commercially available solvent-impregnated resins in addition to evaluation of several resins of this type synthesized in our laboratory. These experiments' involved both nitric and hydrochloric acid media. The data from these experiments will be used to determine the column size and' amount of resin required to polish the waste stream produced by the ion-exchange process described above. Small-scale flow experiments will be described and data given on the mass balances achieved using this two step process. Future work for evaluation of new ion-exchange and solvent-impregnated resins as well as the search for new eluants will be discussed. Other future experiments for both processes, including large-scale experiments, will be discussed in detail.

Jan 1, 1996

By B. K. Chakrabarti

Modeling and a screening design of experiment (DOE) was performed with the process variables to identify the greatest effect of variables on the response quality in the dead burning of magnesite refractory in a rotary kiln. Among various interdependent variable factors, the design variables chosen were raw magnesite (RM) feed rate, kiln rotation time i,e, seconds per rotation(SPM) and burning zone temperature (BZT). The response variables chosen were exit gas temperature and density of dead burnt magnesite(DBM). ANOVA and normal plots were used to evaluate the effects.This work had enabled to correlate the BZT, RPM, RM feed with the exit gas temp and density of magnesite produced. The result opens up an avenue to look into the optimum region of operations within the ranges of variables considered in order to conserve energy and to minimize the exhaust gas temperature and to maximize the density of the DBM produced

Jan 1, 2015

By T. R. A. Davey

Previous publications on the application of EIETSIM include the modelling of an electrolytic zinc plant and a copper flash smelter. In the present case METSIM has been used to model the desilverising of lead by the reagent zinc, whereby a silver-zinc intermetallic compound is formed, and floats out of the lead. This compound has a variable composition, depending upon the ratio of dissolved zinc/silver in the lead bath. Its solubility in lead decreases with falling temperature. A number of variations and modifications of the Davey Desilverising Procedure are modelled, and applied to a wide range of silver contents in lead bullions at several plants. METSIM uses both feed- back and feed-forward controls to simulate plant conditions, and a logic control to distinguish between different phases in the Zn-Ag system. Use is made of extensive (previously unpublished) fundamental data on the ternary Pb-Ag-Zn system, and of plant data, to establish certain operating parameters.

Jan 1, 1993

By B. W. Lightfoot, Neill F. Arthur

"The AusIron process is a new development of the well established Ausmelt bath smelting technology(l). The development of this technology has been tied to the South Australian Steel and Energy (SASE) project which brings dedicated coal and iron resources together with this new technology. SASE is a joint venture between Ausmelt (40%), Meekathara Minerals (40%) and the South Australian Government through Mines and Energy South Australia (MESA) (20%). It will use a multiple lance furnace to process iron ore using steaming coal for both fuel and reductant.It is intended to build the simplest plant economically possible. Refinements such as preheating and prereduction of the ore are compatible with the technology but are not expected to be necessary in the first generation plant.The joint venture is negotiating with suitable partners for funding of the project through to commercial implementation at a target scale of2.5 mt/a of pig iron.ObjectivesAusIron aims to produce pig iron directly from steaming coal and from any of a variety of iron sources in a simple furnace system with a minimum of pre-processing of either coal or iron ore. Preheating and prereduction of ore are compatible with the technology but may not be necessary. The immediate aim is not to be the technology that uses the least quantity of coal to produce iron metal but rather the technology that uses the least number of dollars to produce metal.The chemistry of iron making is well known, probably better known than that of smelting of any other metal. Iron has been made for thousands of years and it is possible to make iron from charcoal and ore in a simple blast furnace the size of a beer barrel. The focus is therefore not making iron but rather making it more cheaply than it is made by current technologies. Large blast furnaces now set the standard and new technologies must perform better if they are to gain market share. It is still the cost of iron, energy units and capital going into these mega blast furnaces which ultimately set the market price for pig iron."

Jan 1, 1996

By Bora Derin, Onuralp Yucel, M. Seref Sonmez, Murat Alkan

"Latest stage in the production of boron carbide by metallothermic methods using magnesium was the leaching process. Boron carbide particles obtained by self-propagating high temperature synthesis contained several impurities such as magnesium oxide and magnesium borates after the metallothermic reactions. Removal of such contaminates by hydrometallurgical methods required to produce high purity boron carbide. Leaching by concentrated hydrochloric acid solutions resulted in the production of pure boron carbide together with high magnesium and boron containing solutions. Removal of such ions from the spent liquor was the necessity to have dischargeable solution. In this study, precipitation of magnesium and boron compounds from relevant chloride containing spent liquors and the production of saleable products was aimed. The effects of chemical reagents, pH of the solution on the precipitation efficiency of magnesium and boron compounds were investigated in the study. Chemical analysis and the characterisationof solid phases by using x-ray diffraction analysis were the latest stage.Introduction A variety of advanced ceramics, inter-metallic, organic and inorganic compounds, oxygen free single crystals, and polymers can be synthesized by using different SHS techniques [1, 2, 3]. In the SHS process, after initiation, reaction becomes self-sustaining and propagates in the reactant mixture. A high amount of heat which is generated during the process accelerates the reaction rate and thus it makes the process highly productive and economically feasible for different production scales. After the SHS process obtained powder mixture needs to reacted with acidic solutions to purify the product. In this case B2O3 was reacted together with C and Mg to synthesis fine B4C powder resulted in the production of MgO as well according to the Eq. 1 and then MgO was removed from the mixture by leaching with the concentrated HCl solution as shown in Eq. 2, respectively [4, 5]."

Jan 1, 2008

By Lixin Qian, Tiejun Chun, Yifan Wang, Huan Wang, Hongming Long, Zhengwei Yu

To solve the problem that the sintered liquid phase fluidity characteristic of low silica (w(SiO2) < 3 wt%) and high silica (w(SiO2) > 7 wt%)) iron ores were different from actual sintering production with using the common method based on w(CaO)/w(SiO2), a new improved method based on n(Fe2O3)/n(CaO) was proposed. The differences between two methods for iron ore fluidity detection were studied. The results show that when the common method is used to detect the liquid phase fluidity, as the content of SiO2 increased from 2.12 to 11.68 wt%, the amount of CaO addition augmented from 7.88 to 32.65 wt% and the corresponding fluidity index changed from 0 to 5.68. The fluidity index has a linearly positive correlation with the content of SiO2. The improved method could significantly reduce the effect of the change of CaO addition on the fluidity characteristic of iron ore which caused by the difference of SiO2.

Mar 1, 2018

By V. I. Lakshmanan, R. Roy

Base metals and PGMs are currently recovered from sulfide concentrates using pyrometallurgical processes. These processes suffer from several limitations such as being capital intensive, scaling problems, S02 emissions and long delay in value recognition. Alternative hydrometallurgical technologies have so far not been successful and currently total pressure oxidation and partial pressure oxidation hydrometallurgical technologies are being evaluated. Process Research ORTECH has developed a unique hydrometallurgical process to recover base metals and precious metals using mixed chloride technology. In a first stage leach, base metals are recovered and elemental sulfur is liberated from hydrogen sulfide formed during this leaching stage. During second stage leach, precious metals are recovered using proven separation technologies. Some of the advantages of the process are the recovery of elemental sulfur from sulfide sulfur, recycle of the chloride lixiviant thereby eliminating effluent treatment steps and use of excess energy from the Claus reactor for the pyrohydrolysis step.

Jan 1, 2011

By Hebi Yin

A coupled cellular automaton (CA) - finite element (FE) model was developed to calculate the growth of dendrites during the solidification of cubic and hexagonal metals. The model solves the conservation equations of mass, energy and solutes in order to calculate the temperature field, solute concentration and the growth morphology of dendrites, including the grain structure and the dendritic microstructure. Validation of the model was performed by comparing the simulation results with calculation results from previously published works, showing qualitatively good agreement in the dendritic morphology. Application to magnesium alloy AZ91 illustrates the difficulty of modeling dendrite growth in hexagonal systems, observed as deviations in growth direction caused by mesh-induced anisotropy. The model was applied to the simulation of small specimens with single- and multiple- equiaxed grain growths and columnar grain growth in directional solidification. The influence of cooling rate and some kinetics parameters on the grain morphology are also discussed.

Jan 1, 2009

By Ailton S. Ferreira, Rubén J. Sanchez Rodriguez, Sergio N. Monteiro, Felipe Perissé D. Lopes, Teresa E. Castillo

"Polyester composites reinforced with natural lignocellulosic fibers have, in recent times, been gaining attention in engineering areas as lighter and cheaper alternatives for traditional composites such as the ""fiberglass"". One of the strongest, the curaua fiber, is today being considered as reinforcement of composites for automobile interior parts. In fact, several research works are currently being dedicated to curaua fiber composites since physical and mechanical properties are required for practical uses. In this work, the thermal behavior of polyester composites reinforced with up to 30 % in volume of curaua fibers was investigated by differential scanning calorimetry, DSC. The results showed endothermic and exothermic events associated with water release and possible molecular chain amorphous transformation. Comparison with similar composites permitted to propose mechanism that explains this DSC thermal behavior.IntroductionThe modem composite materials, especially those reinforced with synthetic fibers such as glass and carbon, have been used since last century to attend the demands required by most technological fields, from home appliances to aerospace [1]. In fact, fiber composites offer significant advantages over monolitic materials, such as common metallic alloys, plastic and ceramics. One of the most important is the ratio between the ultimate stress and the density, known as the specific strength. For example, in common glass fiber polymer composites, the so called ""fiberglass'', the specific strength of around 400 MPa.cm3/g is higher than any conventional monolitic material. However, drawbacks exist. The energy required to fabricate ""fiberglass"" generates large emissions of C02, which are responsible for global warming. Moreover, ""fiberglass"" is not recyclable and cannot be incinerated [2]. As a result, most synthetic fiber composites end up in landfills or contribute to rivers and oceans pollution."

Jan 1, 2011