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By Cong Wang, Kexin Jiao, Yongan Zhao, Haibin Zuo, Jianliang Zhang

Traditional refractory materials for blast furnace hearth lining are mainly composed of carbon bricks and the ceramic cup. However, these materials can’t meet the demands for long service life design of blast furnaces. In this paper, a new refractory called carbon composite brick (CCB) was introduced, which combined the advantages of carbon bricks and the ceramic cup. In this case, the resistance of the CCB against corrosion was equal to the ceramic cup and the thermal conductivity of the CCB was equal to carbon bricks. From the results of more than 20 blast furnaces, the CCB could be well used in small blast furnaces and large blast furnaces. In the bad condition of low grade burden and high smelting intensity, the CCB gave full play to the role of cooling system, and effectively resisted the erosion of hot metal to improve the service life of blast furnaces.

Jan 1, 2015

By I. M. Richardson, M. Janssen, I. J. Bennett, V. A. Popovich

The most critical processing step during the manufacture of screen-printed crystalline solar cells is firing aluminium and silver contacts, which generates residual stresses and solar cell bowing. In this paper, an alternative Ag contact formation mechanism is proposed and aspects related to electrical contact properties, residual stresses and layer delamination are investigated. It is found that there are two main processing parameters affecting the uniformity and delamination of the Ag/Si interface, namely the peak firing temperature and the silicon surface roughness. Silicon surface polishing gives a better wetting of the silicon surface by the glass layer, resulting in a good contact and lower incidence of large voids, compared to the case of highly textured surfaces. The non-uniformity in the glass layer and large voids at the Ag/Si interface (in the case of a textured surface) are expected to have a negative effect on the mechanical strength of the solar cell.

Jan 1, 2015

By Jesse White, Tyler Salisbury

Research projects contain many stages of development from the conception of an idea to a fullscale commercial operation. The transition from laboratory-scale research to bench-scale roasting can represent a significant increase in complexity and cost, depending on how many variables are being evaluated. Thermogravimetric analysis (TGA) can simulate roasting conditions and produce a small sample for chemical analysis or materials characterization. A simultaneous thermogravimetric and differential scanning calorimetry (TG–DSC) can identify endothermic and exothermic reaction temperatures. Using thermal analysis, some of the process variables can be tested and eliminated such as ore and reagent blends, retention times, operating temperatures, and some atmospheres.

Jan 1, 2015

By Ligang Zhang, Wen Chen, Xinghua Liu, Jialin Li, Xiaoyin Liu, Zhenhong Liao

A research-scale fluidization and magnetization roasting device was developed to evaluate a processing option that might offset the complexity and high cost of the conventional magnetization roasting process on siderite. In this study, the operating parameters of the fluidization and magnetization roasting device for siderite were evaluated through cold-flow tests and magnetization roasting tests. The reaction mechanism functions of the fluidized roasting process are revealed with kinetic studies.

Jan 1, 2015

By Sheng-li Wu, Guo-liang Zhang, Bo Su

The mineralogical characteristics of iron ores can influence their high temperature sintering performance. In this study, eight iron ore samples from Brazil, Australia, and South Africa were characterized by their chemical composition, mineral types, particle morphology, and gangue dispersity. Meanwhile the influence rules between the mineralogical characteristics and the high temperature characteristics were evaluated and analyzed. The results showed that the effect of SiO2 on assimilation characteristic of iron ores was relatively complex, Al2O3 and LOI of iron ores had negative correlation with assimilation temperature of iron ores, the dense slab-flaky mineral granule restrained to the assimilation characteristics of iron ores; liquid phase of iron ores with high SiO2 content and low Al2O3 content had high fluidity, and the higher dispersity of gangue minerals in iron ores was good to the fluidity of liquid phase.

Jan 1, 2015

By D. M. Fermino, C. G. Bastos Andrade, V. F. Justo, F. R. Valenzuela-Diaz, M. G. S. Valenzuela, C. Volzone

The present paper presents the study of light green smectite clay, from Paraiba, Brazil, submitted to mild acid attack under moderated conditions. Usually, clays are subjected to treatment with strong inorganic acids at temperatures near the boiling point and at high acid concentrations and then, widely used as bleaching agents. The treatment occurred under bellow boiling temperature and at short times of reaction (90°C, reaction times of 1, 6, 12, 18 and 24 hours in close reactor, concentration of the aqueous solution of hydrochloric acid 1.5 M, clay/acid solution ratio of 1g/10mL). The purpose of these attacks is to reduce the concentration of impurities providing color, with minimal change in the clay minerals structure, aiming at use in products of high value such as cosmetics and polymer/clay nanocomposites. The raw clay and the attacked samples were characterized by X-ray diffraction (XRD), cation exchange capacity (CEC), stereomicroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray detector (EDS).

Jan 1, 2015

By Lei Wang, Jianjun Wang, Lingen Luo, Zhengbang Li

Dearsenication in molten steel was studied by adding Ca-Fe Alloy-based arsenic removal agent. In order to improve the utilization rate of Calcium Iron Alloy and improve arsenic removal ratio, [O] is less than 0.0005% and [S] is less than 0.0035%, Al is added into the molten steel. In the processes of adding CaO-Al2O3 based alkalinity slag for arsenic removing in molten steel (initial arsenic content is 0.0080%), arsenic removal ratio reaches 50% when Ca-Fe Alloy addition amount is 18%. During the arsenic removal experiment, adding Rare Earth promotes the arsenic removal reaction and makes the arsenic removal more effectively.

Jan 1, 2015

By Mingming Zhang, Mallikharjuna R. Bogala, Ramana G. Reddy

Steelmaking desulfurization slag samples were characterized using chemical, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) methods. The objective of this work is to investigate the occurrence of sulfur and phosphorus components in the slag samples and to identify their origin and associations with the iron phases. Thermodynamic calculations results confirm the presence of phosphorus and sulfur components in the slag sample at high temperatures (1400 to 1800oC). The main constituents of slag include Ca3SiO5 (28.1%), MgO (9.31%), Ca3(PO4)2 (9.18%), CaS (8.39%) and CaO (5.68%). The major phosphorus and sulfur components of the slag are Ca3PO4 (99.2%) and CaS (79.3%) respectively. Characterization studies indicate the presence of microparticles of different sizes and shapes in the slag sample. Elemental analysis of these particles confirm the presence of major elements (O, Mg, Al, Si, S, Ca and Fe) in the slag sample.

Jan 1, 2015

By Qiang Zhong, Bin Xu, Qian Li, Yongbin Yang, Tao Jiang

Viscosity of slag determines the production efficiency, energy consumption and distribution of elements between metal and slag, which is very important for pyrometallurgy. Slag of goldantimony ore blast furnace smelting has seldom been studied. In this paper, the viscosities of gold-antimony ore smelting slags of different composition have been studied by the rotating cylinder method. The results showed that, for a slag of 38.95% SiO2, 16.17% CaO, 25.97% FeO, 10.25% Al2O3, 5.17% MgO, the viscosity can be decreased by reducing 3.24%-8.5% SiO2 or increasing 3.31%-9.56% CaO content. Complex SixOy z- from SiO2 acts as the main cause for the high viscosity in a slag of high SiO2. The increasing of CaO causes the decreasing of the amount of SixOy z- and the O2- dissociated from CaO breaks the complex SixOy z-, which can decrease the viscosity. Viscosity of different composition slag in the appropriate range temperature can be calculated from the Arrhenius equation.

Jan 1, 2015

By Bhagyadhar Bhoi, Chitta Ranjan Mishra, Pravas Ranjan Behera

Red mud of Indian origin contains around 55% plus of Fe2O3 and is considered as a hazardous waste for the alumina industry. For production of one tone of alumina employing the Bayer’s Process, around two tones of red mud is generated from three tones of Bauxite. Conventional process of steel making is not devoid of environmental pollution. In the present investigation, efforts have been made to produce steel from red mud by adopting reduction roasting, magnetic separation and hydrogen plasma smelting route. Magnetic fraction, containing enriched iron oxide and minimal content of alumina, is produced following the first two stages which is then subjected to hydrogen plasma smelting process for production of steel. This novel concept follows a green path way for production of steel free from pollution and is termed as green steel. Further, the only by-product that is produced in the process, is water, which is eco-friendly and recyclable.

Jan 1, 2015

By R. Koen, H. Visser, A. Roodt

"SynopsisThe tetraethylammonium salt of the mono-anionic coordination compound mer-oxidotrichlorido(thenoyltrifluoroacetylacetonato- K2O,O’)niobate(V) (NEt4)[NbOCl3](ttfa)], has been prepared under aerobic conditions and characterized by single-crystal X-ray diffraction. (NEt4)[NbOCl3](ttfa)] crystallized in the monoclinic P21/c space group, with a = 11.483 (5), b = 12.563 (5), c = 17.110(5) Å, and ß = 100.838 (5)o. The complex structure exists in a 50.0% (NbA) : 50.0% (NbB) positional disorder ratio.IntroductionComplexes containing organometallic type ß- diketone ligands with O,O and O,N donor atoms are used widely in coordination chemistry and have applications in catalysis, radiopharmaceuticals, etc. (Schutte et al., 2011; Roodt, Visser and Brink, 2011; Brink et al., 2010; Otto et al., 1998). These ligand systems are very useful because of their highly coordinative nature, high solubility, and also due to their ability to be functionalized with various substituents on the carbonyl carbon atoms (Schutte et al., 2011).Only a small number of ß-diketonate ligands have successfully been coordinated to a Nb(V) metal centre, with only a select few being characterized by X-ray crystallography (Viljoen, 2009; Bullen, Mason and Pauling, 1965; Preuss, Lamding and Mueller-Becker, 1994; Funk, 1934; Davies, Leedlam and Jones, 1999; Allen, 2002. The synthesis and crystal structure determination at room temperature of mer-oxidotrichlorido (thenoyltrifluoroacetylacetonato- k2O,O’)niobate(V) {(NEt4)[NbOCl3(ttfa)]} was first reported by Daran et al. in 1979. Accordingly, for this current investigation, (NEt4)[NbOCl3(ttfa)] was re-evaluated at 100 K to determine if the structural features might change with temperature."

Jan 1, 2015

By H. Utsunomiya, J. Su, K. S. Tamimi, S. Yue, M. Sanjari, L. Kestens, A. S. Kabir, R. Petrov

The recrystallization and texture evolution of AZ31 sheets obtained through two stages was investigated at different stages of post-rolling annealing. The specimens were rolled at the temperature of 100? and at a fast speed of 1000m/min and low speed of 15m/min with a reduction of 30% in one pass. The results show thatAZ31B sheets rolled at 15 m/min and 100 °C has fractured for reductions of more than 30% per pass. However, by increasing the rolling speed to 1000 m/min the rollability was improved significantly and the material can be rolled to reductions of more than 70% per pass. The high speed and heavily deformed materials are fully recrystallized even at 100 °C.

Jan 1, 2015

By D. Virely, M. Gasc-Barbier, J. Guittard

"The valleys of the Dordogne and the Vézère (France) have been inhabited since prehistoric times, as evidenced by the famous site of Lascaux. A few miles away, the village of La Roque-Gageac is also a very popular tourist destination (about 1.5 million tourists per year): The village is sandwiched between a massive limestone cliff and the Dordogne river. The collapse of a cave roof high above the village in January 2010 led us to characterize instability together for the cave and the whole cliff and propose a adapted instrumentation to monitor the fracture openings in the rock mass that are linked to climatic variations. Measurements have been going on and been recorded for nearly 4 years. They point out the role of thermal stress fatigue in the breakdown of the rock mass. In this paper we describe the site under study, the instrumentation and its main results. INTRODUCTIONThe phenomenon of thermal fatigue has been very little studied as far as rocks are concerned, whereas it is rather well characterized for other types of materials: Elsevier published a journal dedicated to fatigue (International Journal of fatigue). In the case of rocks, thermal phenomena and their impacts on mechanical behavior have been analyzed from a micro-structural point of view, and it is now well-known that an increase in temperature causes a dilatation of crystals (Arnould et al., 2004; Berest & Weber, 1998). This dilatation may lead to the development of inter-granular traction and compression stresses, and if those stresses are greater than fracture strength, inter-granular and intra-granular cracks may take place. On the other hand, the fatigue phenomenon (cyclic repetition of a temperature variation which is less extreme than the one that may lead to this inter-granular or intra-granular fracture) is a phenomenon which has not been much studied.The principal studies on thermal fatigue on rocks come mainly from the field of geomorphology, particularly in connection with the analysis of the evolutions of past climate that can explain the present shapes of those landforms: those studies remained essentially qualitative and not quantitative. Le Ber & Oter Duthoit (1987) proposed a thermal and thermodynamic approach to analyse the disaggregation of rock masses. This analysis is dedicated to the study of paleoclimates and was implemented to better understand the formation of slope deposits in order to propose transfer models permitting the reconstruction of the climactic conditions contemporary to their appearance. Since deterioration in the cliff only appears after several cycles, it means that it is a gradual and irreversible deterioration which leads to an increase of the « disorder ». Seen from a macroscopic system point of view, this irreversible evolution is quantified by the internal creation of entropy."

Jan 1, 2015

By Yihan Liu, Jintao Zhang, Chen Xiao, Xiaomeng Zhao, Guanglei Song

To estimate the performance of the inert anode materials based on NiFe2O4 spinel ceramic during it used for aluminum electrolysis, we investigated the wetting process of cryolite molten salt which is in composition of industrial aluminum electrolysis with carbon anode and NiFe2O4 based cermet materials, by means of determination the interface wetting angle between the molten cryolite electrolyte and the solid anodes interface. The results show that the wetting angle between the electrolyte and carbon anode is larger than 90 angulation, this means that they basically can not wetting; however the nickel ferrate spinel ceramics behaves much better. In regard to the NiFe2O4 matrix materials, their initial wetting angles is 76.9. The initial wetting angles for 1.0wt%MnO2, 2.5wt%TiO2 and 0.5wt%V2O5-doped samples are respectively 56.86°, 52.98° and 51.93°. However, after 50s later, all the wetting angles came down below 15°.

Jan 1, 2015

By Harry Thompson

In using explosives to blast stumps from the ground in order to prepare it for farming, it is comparatively easy to place the charge under a stump having a semitaproot or a lateral system of rooting by boring or digging a hole in the earth to a point under the center of resistance and deep enough to give the desired effect.1

Jan 1, 2015

By A. McLean, M. Barati

In this paper, examples are presented of pyrometallurgical research and associated teaching activities during the past century within the Department of Metallurgical Engineering, now the Department of Materials Science and Engineering, at the University of Toronto. Throughout these years, pyrometallurgical research has been characterized by recognition of the importance of the interdependence of measurements and models as well as the development and application of sensors, for the generation, validation and practical implementation of new knowledge. The important role played in the delivery of lectures and participation in joint research by Adjunct Professors with strong backgrounds in the pyrometallurgical industry is described. Projects conducted in close collaboration with the industrial sector and opportunities for students to obtain practical experience working as teams on a "round-the clock" shift basis within an industrial pilot plant environment are outlined. These activities, together with the involvement of students in poster competitions and the presentation of papers at society conferences and technical meetings, are still vital elements in the development of pyrometallurgists equipped with the appropriate professional skills for subsequent employment within academia, government laboratories or the industrial sector.

Jan 1, 2015

By A. McLean, W. Q. Chen, W. Yan, M. Barati, Y. D. Yang

In order to maximally remove the harmful impurities phosphorus and reduce the loss of valuable elements from Si-based alloy for production of solar-grade silicon, thermodynamic properties of the Si-based alloy were studied. In this work a new model, the Molecular Interaction Volume Model (MIVM) derived from statistical thermodynamics, was successfully used in the Si-based and Si-Fe-based alloy. The calculation started from binary Si-Fe, Si-P and Fe-P systems, then the thermodynamic parameters of ternary systems could be derived based sub-binary systems. Using the activity coefficients of the elements in the Si-based alloys and the saturated vapor pressure of the pure substance of the components, mass fraction of P during vapor-liquid equilibrium can be calculated. The calculated thermodynamic parameters were compared with experimental data available in different publications, and it is found that the thermodynamic parameters calculated using MIVM model are in good agreement with the measured results. The calculated result shows that the mass fraction of phosphorus during vapor-liquid equilibrium of Si-Fe-P melt increases with the increasing phosphorus content and decreasing temperature. This is an important direction for experimental practice in vacuum or low-pressure EML refining of ferrosilicon for potential production of solar-grade silicon without significant vaporization loss of valuable element.

Jan 1, 2015

By P. Schumacher, M. Fein

"INTRODUCTION Newmont’s Twin Creeks operation, part of its Nevada operations, produces gold from two large open pit mines. Mined ore is processed at one of three on-site facilities: a refractory mill with two autoclaves, an oxide mill and heap leaching facilities. Twin Creeks also processes various off-site sourced concentrates and ore including high grade underground ore from the Turquoise Ridge joint venture with Barrick Gold Corporation. This paper discusses Twin Creeks’ strategic mine planning process which is part of an in-depth continuous improvement program called “Full Potential.” The process involves cost analysis, phase design validations, life-of-mine production scheduling optimization, mill blending strategy and stockpile management. Through this Full Potential strategic planning, Twin Creeks is creating significant value by increasing near term free cash flow and life of mine net present value (“NPV”) and achieving cost reductions. TWIN CREEKS OPERATION Twin Creeks is one of the major gold producers in Newmont’s Nevada operations (see Figure 1, 2 and 3). Located approximately 15 miles north of Golconda, Twin Creeks produced approximately 28 % of the Nevada operation’s 2013 gold production of 1.8 million ounces (Newmont 2014). The production included Turquoise Ridge sourced gold ore from the joint venture (75% Barrick Gold Corporation, 25% Newmont).At Twin Creeks, there are two large open pits, named Mega Pit and Vista Pit (see Figure 4, 5 and 6). There are 3 to 5 phases in Mega Pit and 2 to 5 phases in Vista Pit depending on the gold price assumption. There is also an underground exploration project at the bottom of the Vista Pit. Twin Creeks produces gold from a variety of ore types requiring different processing techniques depending on economic and metallurgical characteristics. To ensure the best use of processing assets, engineering and processing groups at Twin Creeks utilize a Mixed Integer Linear Programming (“MILP”) model to guide the flow of mine sequences and material routing to various process facilities (Kawahata, Schumacher and Hufford 2013)."

Jan 1, 2015

By C. Díaz, M. Barati

Prof. Torstein Utigard's untimely death, in the spring of 2012, put an abrupt end to a meritorious career in the field of high temperature chemical process metallurgy. As an academic in the Department of Materials Science and Engineering of the University of Toronto, Torstein made solid contributions to the advancement of knowledge pertaining to production and refining of both nonferrous and light metals, and to the development of inquisitive and innovative young people in extractive metallurgy. In this profile, the authors highlight aspects of Torstein's rich personality and of his contributions to his field of expertise.

Jan 1, 2015

By J. L. Ellenberger, G. S. Esterhuizen, T. Miller, M. M. Murphy

A limestone mine in Ohio has had roof instability problems that have led to massive roof falls extending to the surface. This paper describes a collaborative study of these events undertaken by the National Institute for Occupational Safety and Health and the mine owners. The study focuses on the roles that weak, moisture-sensitive floor and weak bands in pillars play in a general instability that led to roof falls at this mine. The NIOSH Stone Mine Pillar Design software (S-Pillar) does not include analysis for weak floor or weak bands and recommends that when such issues arise they should be investigated further using a more advanced analysis. It is important to recognize that without the impact of the floor or weak bands, the calculated inherent stability factor for these pillars is within the recommended design range. Therefore, to further investigate the observed instability occurring on a large scale at the Ohio mine, FLAC3D numerical models were employed to help determine the failure mechanism. Roof-to-floor convergence monitors were also installed in the areas predicted to have further instability. This case study will provide important information to limestone mine operators regarding the impact of weak floor causing the potential for roof collapse, pillar failure, and subsequent subsidence of the ground surface. This recent case demonstrates that weak floor can be a significant factor in pillar stability and should be assessed during the design stage of the mine.

Jan 1, 2015