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By B. Zeifert, C. Martínez-Morales, A. Romero-Serrano, A. Pineda-Rivera, H. Martínez-Gutiérrez, G. Diaz-Sandi

In this work, the effects of CaO/SiO2 ratio and the FeSO4 and FeS2 contents on the stability of the mineralogical species in chromium-based slags were studied. The chemical stability was evaluated by leaching with an acid solution. The main Cr-compounds in slags with FeSO4 and CaO/SiO2=1 were FeCr2O4 and Ca3Cr2Si3O12, while Cr3S4 predominated in slags with FeS2. The slags with CaO/SiO2=2 mainly contained CaCr2O4. The highest Cr concentration levels in the leaching liquors corresponded to slags with CaO/SiO2= 2, and the lowest Cr concentration corresponded to slags with high FeSO4 or FeS2, owing to the stable binding of chromium in the compounds FeCr2O4, Cr3S4 and FeS•Cr2O3.

Jan 1, 2011

By Malti Goel

"Ferrous and non-ferrous metals industries are source of both direct and indirect greenhouse gas (GHG) emissions. Metal industry accounted for 29.7% of the total GHG emitted from the Indian industry sector in 2007. Aluminum is second largest contributor after steel. Indian Aluminum industry has been growing and is adopting several effective measures for better efficiencies through process change and waste utilization. Improvement in the energy efficiency can form the basis of monitoring reduction in emissions. Under the National Action Plan on Climate Change 2008, National Mission for Enhanced Energy Efficiency (NMEEE) aims to upscale the efforts to unlock the market for energy efficiency improvement on a public private partnership (PPP) basis. For a transition to low carbon economy industry is undertaking voluntary measures through scientific and technological innovations both in upstream and downstream sectors. In this paper an attempt is made to overview recent developments in Indian Aluminum industry as well as summarize scientific & technological challenges and prospects.IntroductionAluminum plays a vital role in industrial development. It is a substitute for different type of materials ranging from wood to copper and steel. The aluminum industry has high energy consumption and high contribution to greenhouse gases from carbon dioxide and perfluorocarbons (PFCs) emissions. It is estimated that CO2 equivalent burden of aluminum industry is about 1% of total anthropogenic emissions. The anticipated world growth rate is 3.5% for aluminum demand. Through measures to reduce both direct and indirect CO2 emissions, electricity consumption was reduced from 25 kWh / kg of Aluminum in 1998 to 15 kWh / kg of Aluminum produced in 2008. It is targeted to further reduce it to 10.8 kWh. Aluminum industry is also responsible to about 60% of all PFC emissions. The PFC emissions are harmful to environment, accumulate in surrounding vegetation and contaminate. Efforts to reduce PFC emissions from aluminum industry started early and reduced to 0.5-1 kg / tonne in 1990 [1] from 12-15 kg / tonne in 1940. Since 1990s to 2000 it further reduced to 0.2 -0.4 kg / tonne as seen in Fig. 1. The Global Aluminum Sustainable Development Initiative (GADSI), targets perfluorocarbon (PFC) specific emissions reduction of 80% for 2010 relative to 1990."

Jan 1, 2011

By A. Tohn, L. May, Adham. K.

The path from process conception to commercial implementation poses significant technical, economic, and sometimes political challenges for every project team. Solving the technical challenges typically distinguishes successful projects from those that fail. Here, the authors provide an outline for technical success based on lessons learned from years of experience in process design and R&D. Challenges faced by new technology developers, with regard to design and definition, are described. Experience-based methods to avoid missteps are shared. Special emphasis is placed on the selection of viable unit operations, definition of known and unknown parameters, experimental screening of options, and piloting for scalable design information. Use of computational models to define, assist, and interpret the pilot operations and results are described. Furthermore, the value of active collaboration amongst the design, research, and owner team is demonstrated.

Jan 1, 2011

By K. Ohto, B. B. Acihikari, H. Kawakita, M. Gurung, S. Alam

Two kinds of adsorbents were prepared from persimmon tannin extract to investigate their adsorption behavior of metal ions from hydrochloric acid solution; one was prepared by treating with concentrated sulfuric acid while another was prepared by immobilizing functional groups of quaternary amine. The former adsorbed only gold(III) and its maximum adsorption capacities was evaluated as high as 1510 g/kg while the latter adsorbed not only gold(III) but also palladium(II) and platinum(IV), the maximum adsorption capacities of which were evaluated as 820, 89 and 101 g/kg, respectively. For both adsorbents, practical adsorption of base metals was not observed.

Jan 1, 2011

By B. Oraee

Accurate estimation of equipment costs is a key factor in feasibility study and evaluation of design alternatives of mining projects. In this paper, capital and operation costs of backhoe loaders are estimated using multiple linear regression (MLR), based on principle component analysis (PCA). These cost functions are consisted of five independent variables; bucket size, digging depth, dump height, weight and horse power. The MLR is conducted in two steps. At the first correlation between independent variables is omitted using PCA technique. Thereafter, MLR functions are established using selected significant PCs and total cost functions are constituted as functions of initial variables. At the end, accuracy of functions are evaluated using mean absolute error rate method.

Jan 1, 2011

By Hideaki Kitajima, Ryo Sakamoto, Katsuya Sasaki, Maehata Hidehiko

The Electric Discharge Impulse Crushing System (EDICS) is a technology for carrying out crushing by using electrical power and nitromethane. It is designed for construction tasks such as splitting of concrete and rocks.The EDICS consists of an electric discharge generator that supplies a high-voltage high-current pulse, a cartridge that generates power by using electric discharge energy, and cables that connect the electric discharge generator and the cartridge. The cartridge contains a thin metal wire that evaporates because of the electric discharge energy and a nitromethane that reacts with this evaporated metal wire. The cartridge can be used to generate a high pressure on the order of gigapascals within a time interval of several hundred microseconds, and crushing power equivalent to that generated by explosives is generated during this period. In recent years, the EDICS has been widely used in Japan because of its good performance and favorable characteristics.

Jan 1, 2011

By N. Giguère

Until recently, the heat treatment of pressure die cast parts has always been considered unpractical because the solution heat treatment resulted in unacceptable blistered parts. This was due to the presence of massive porosity associated with the die casting process where the inflow of metal inside the mold cavity is extremely turbulent. With the steady improvement of foundry practices and the generalization of vacuum die casting, porosity defects have been reduced to the point that a partial solutionizing heat treatment can be applied without any damage to the casting. However the solutionizing temperature must be lower than that applied to macroporosity free castings and for much shorter time. The object of the present study was to determine the optimum solutionizing temperature that can be applied to aluminum 383 die cast brackets along with the optimal temperature and time of aging resulting in the highest improvement in mechanical properties (both strength and ductility). This was done by testing strength and deformation on the casting itself using a specially designed jig; the crushing force to deformation curve was analyzed so as to quantify the improvement in both strength and ductility gained with the partial precipitation hardening heat treatment.

Jan 1, 2011

By Hongbo Zhu, Jinhui Peng, Linqing Dai

"To optimize the process variables for making direct reduced iron (DRI) by microwave heating, the reduction temperature, reduction time and the ratio of coal to material were studied with the central composite design (CCD) and their interactions on the Metallization rate were also investigated. The predictive polynomial quadratic equations model was analyzed by ANOVA. Optimal conditions of making DRI can be concluded as follows: 28 min at 1139?, the ratio of coal to material is 20.95%. Under these conditions, the metallization rate is up to 97.06%.1. IntroductionThere are some technical problems in making direct reduced iron (DRI) or sponge iron using iron ore concentrates containing coal and lime. In reduction of the iron ore concentrates containing coal with microwave heating, the strength of pellets needn’t to be considered. It reduces the costs and improve quality of materials, but also eliminates the need for pellet preparation process, simplifying the process and achieving a cleaner production.Microwave energy is a clean energy, and has characteristic of selective heating. The speed of heating is also fast. It researched by Chen Jin that when the mole mass of C: O is 0.627 and the microwave power is 15KW, it only spends 15min from 15? to 1021.6? with 1 kg iron ore containing coal with microwave heating [1]. There are many factors affecting metallization rate. In order to find a suitable condition for reduction process, it is necessary to design a series of suitable experiments.Response surface methodology (RSM) is one of the relevant multivariate techniques which can deal with multivariant experimental design strategy, statistical modeling and process optimization [2–5]. It is used to examine the relationship between one or more response variables and a set of quantitative experimental variables or factors. This method is often employed after the identification of the vital controllable factors to find the factor settings that optimize the response. Designs of this type are usually chosen when a curvature in the response surface is suspected. The process optimization of the microwave reduced iron ore was seldom reported in literature. Hence the present work intends to assess the effects of variables such as reduction time, reduction temperature and the ratio of coal to identify the optimum conditions using a central composite design (CCD). The characteristic of product was assessed using scanning electron microscope (SEM)."

Jan 1, 2011

By E. L. Thyse

Keywords: Pyrometallurgy, converter, nickel, matte, distribution Metallic elements occupy a wide range in granulated nickel converter matte phases. The distribution of these metallic elements, particularly during crystallization path events, appears to be poorly understood. The present study serves to investigate the distribution of Fe, Co, Ni, Cu, and Pb between nickel-sulphide, copper-sulphide, and alloy phases. A novel combination of thermo-chemical modelling, electron microscopy, and electron probe microanalysis was applied to understand crystallization path events and the associated metallic element distribution. This study has demonstrated that major Ni incorporated during copper-sulphide crystallization would serve to mobilize minor Co towards distribution in copper-sulphide phases. In addition, solid solution substitution of Cu by Ni is manifested by compositional zoning of copper-sulphide phases. The role played by Ni during alloy crystallization suggests that minor Co was also mobilized, along with an increase in principal Ni. Fe, by contrast, seems to be incompatible with principal Ni. In addition, solid solution substitution of Ni with PGEs and Cu is manifested by compositional zoning of NiCu-alloy phases.

Jan 1, 2011

By U. Thorley

Management of mine and tailings reclamation activities by surface mining oil sands operations in Alberta, Canada is experiencing increased national and international attention. Of particular concern is the ability of existing mines to execute and fund reclamation activities. Concern stems from a lack of demonstrated tailings reclamation technologies, perceptions of a poor track-record of reclamation activity by industry, and a lack of transparency with respect to the potential cost of reclamation activities relative to the monies secured in Alberta?s Environmental Protection Security Fund (EPSF). Limited information is publicly available regarding reclamation costs and technologies. Available data typically comes from disparate sources. This paper examines the expected costs of oil sands reclamation activities through a study of corporate Asset Retirement Obligation (ARO) liabilities, the Province of Alberta?sEPSF, and published data relating to reclamation costs.Issues relating to current liability funding are introduced.

Jan 1, 2011

By P. Gautier

Current feedstock in the aluminum hot forging processes can be used in the cast or extruded forms. The microstructural variation between as-cast and extruded materials could result in different mechanical properties and corrosion resistance for hot-forged products. Corrosion performances were examined for forged parts produced by two AA6082 feedstocks at different conditions using the following corrosion tests: open circuit potential, anodic polarization, salt spray exposure and corrosion fatigue. With the help of optical and scanning electron microscopes, metallographical investigations were carried out on cast-forged and extruded-forged materials before and after corrosion. The corrosion behavior of both materials was compared in both as-forged and aged tempers. Results show that there is no significant difference in the corrosion performance for final cast-forged and extruded-forged products.

Jan 1, 2011

By R. L. Wiegel

Some of the mineral deposits that are being processed today, and especially those expected to be processed in the future, have relatively low compositions of the valuable mineral. With these low-grade ores, it is necessary to be able to design processes that are sufficiently low-cost to permit exploitation. One approach to minimizing the capital and operating costs for these processes is to use the capabilities of computer process simulation in the design phase of development, to make important technical and economic decisions regarding the evaluation of alternative process flow schemes, the selection of equipment and the choice of operating conditions. There are mathematical simulation models for most mineral processing operations, including several each for size reduction, size classification and mineral separations. To be able to tie these individual operating models together in an integrated mineral process simulation, however, it is important, in fact in some cases essential, that there be a model which describes how the mineral system responds to size reduction in making the liberated valuable and waste mineral particles available for concentration or rejection operations and the locked particles available for possible recirculation. This, then, is the role played by the mineral liberation model, showing the relationship between particle size, quantity and composition throughout the process.

Jan 1, 2011

By D. Mkhwanazi

The purpose of the project was to optimize load haul dump (LHD) machinery use as they were spending too much time doing what they should not be doing. During the investigation, the author found that the machine's actual availability was 86% and the utilization ranged between 30% and 42%. This shows that the availability of the machine has met its target. Therefore the main problem was with the LHD utilization and that is what the project focuses on. To satisfy the objectives, the author firstly studied the existing mining data like the key performance indicators (KPIs) in order to analyse the machine's availability and utilization; this is what gave direction to the problem. Secondly the author did a literature review on mines with similar problems. This gave the author ideas on what to look at in approaching such a situation. Thirdly, the author gathered information on what the LHDs are doing on a daily basis by doing a time study. This gave the author an idea of how long it took the LHDs to complete a specific task. The author also interviewed operators and their supervisors in order to find the best practice work. This helped in identifying the problem areas when comparing the best practice work with what the LHDs are actually doing. According to the project results, it was found that the LHDs are underutilized due to shortage of drivers and the long distances the LHDs have to travel for material loading and refuelling. The author recommended that the machine utilization should be improved by training more operators in order to eliminate the 'no operator' downtime; the cost arrangement of this recommendation is included in the report. The author also recommended that the travelling time should be reduced by using tractors instead of LHDs when long distances need to be travelled for material loading. Another recommendation for reducing travelling time was to bring the mobile fuel tank closer to a section; the cost arrangement for this recommendation is also included in the report. Keywords Optimizing, LHD utilization, LHD availability, key performance indicators (KPI), shortage of drivers, long distances, mobile fuel tanks.

Jan 1, 2011

By G. Wang

Industrial minerals processing has gained importance lately, not only due to its wide range of new and regular applications in processing different industrial minerals, but also due to the strict specs under which products are commercialized. Among the processes applied to industrial minerals, flotation is a leading technology. The laboratory study and commercial operation demonstrate that the sulfonated reagents are very effective collectors for industrial minerals. This paper compares synthetic petroleum sulfonate with fatty acid on iron reduction in glass sand processing and describes the effect of conditioning pH on iron reduction using synthetic petroleum sulfonate as collector, the effect of molecular weight of natural and synthetic petroleum sulfonates on their flotation performance and the enhancement made for certain products.

Jan 1, 2011

What is your assessment of the status of the mining industry as we see some evidence of an economic recovery? I am optimistic about the short and midterm prospects for the industry and, hence, for the professionals in the industry that constitute the majority of the SME membership. All who will read this interview recognize that the quality of life we enjoy today is largely a result of our achievements in the mining and minerals processing sectors. I believe that the sustainability of that quality of life and the aspirations of other sectors of the global community to attain that same lifestyle will significantly depend on the continued successes of these industries. Looking at some of the traditional economic indicators, we see predictions of continued increases in gold prices during the next 12 months as a new round of quantitative easing keeps real interest rates low and drives excess capital flows from countries with trade surpluses - who have traditionally parked their money in U.S. government bonds - into other investable assets, such as gold. On the fuel side of the industry, we have during the last decade seen a steady rise in the cost of coal, and some of the recent spot prices have seen dramatic increases. Some suggest that coal prices may rise sooner than anyone expects, as global reserves are revised downward. This is based on the hypothesis that some of the main coal-producing countries are overestimating supplies and that coal prices could start rising far sooner than anyone thinks - with obvious serious implications for energy policy. Those forecasters note that, for the past couple of decades, global supply has been dropping at a faster rate than consumption.

Jan 1, 2011

By Alwin Frei, Aldo Steinfeld, Peter G. Loutzenhiser, Enrico Guglielmini

"Using concentrated solar radiation as the energy source of high-temperature process heat, the carbothermal reductions of Al2O3 to Al and SiO2 to Si were examined thermodynamically and demonstrated experimentally at vacuum pressures. Reducing the system pressure favors Al(g) and Si(g) formation, enabling their vacuum distillation and avoiding contamination by carbides and/or oxycarbides. Exploratory experimentation in a solar reactor was performed with mixtures of charcoal with alumina and silica in the ranges of 1300-2000 K and 1997–2263 K, respectively, at 10-3 bar by direct exposure to concentrated thermal radiation. Distilled samples contained up to 19 wt% of Al in Al-Al2O3 mixtures and 79 wt% of Si in Si-SiO2 mixtures. When the reducing agent is derived from a biomass source, the solar-driven carbothermal processes are CO2 neutral.IntroductionMetallurgical extractive processes for producing Al1-2 from Al2O3 and Si3-6 from SiO2 are characterized by their high specific energy consumption and concomitant emissions. Alternatively, concentrated solar energy can be used as a high-temperature heat source to drive the carbothermal reductions and, thus, avoid greenhouse gas emissions and other pollutants derived from fossil-fuel-based processes7-12. When the reducing agent is biomass charcoal, the solar-driven carbothermal reduction is CO2 neutral. The carbothermal reductions of Al2O3 and SiO2 are represented by the simplified overall stoichiometric reactions:"

Jan 1, 2011

By A. J. Vietti

A pilot plant paste thickening campaign was conducted at the Anglo Platinum Limited Mogalakwena South Concentrator plant in South Africa in order to determine the water saving capability of P&TT technology. In the process a simple water consumption model was developed for estimating the overall water consumption of the mine. The model indicates that for the Mogalakwena tailings, significant water savings are achieved by discharging thickened tailing directly to the TSF but only at densities where free water release at the TSF is close to zero. Keywords Paste, thickened tailings, thickener, water savings, water consumption.

Jan 1, 2011

By F. T. Cawood

The new mineral royalty regime for South Africa was signed into law in November 2008, with its main objective being to compensate the State for the depletion of public minerals through a royalty charge payable from 1 March 2010. The aims of this paper are to establish the potential impact of mining royalties on State revenues, industry affordability, and explore whether the dual formula system is likely to encourage miners to become refiners. It also measures the royalty dispensation against economists? tax standards in an attempt to make a judgement on the ?equity? of the new system. This paper argues that most stakeholders should be comfortable with most of the requirements of the Act for most of the time. However, the new regime is unlikely to motivate miners to become refiners, as the benefit of the reduced rate on refined minerals appears to be insufficient to justify the additional costs to refine the mineral resource to the prescribed states of beneficiation.

Jan 1, 2011

By Yi Luo

Simulation of the multi-entry and multi-crosscut (MEMC) ventilation systems commonly employed in U .S. underground coal mines can be very tedious, due to the large number of crosscuts with stoppings to be represented in the network models. In order to reduce the amount of work needed to build the models, a common practice is to represent a number of crosscuts with one equivalent airway. However, this introduces certain errors into the simulation results. In this paper, algorithms have been proposed to simplify the ventilation networks of common MEMC systems encountered in panel development operations. The algorithms can be used to reduce a MEMC system into one airway with an equivalent resistance and to determine the airflow distributions in the system and the leakages through the stoppings.

Jan 1, 2011

By Jinsheng Chen

For underground openings, many factors can cause roof failure and thus roof falls. The most common factors related to Mother Nature are weak roof lithology, geological structures, and an abnormal in-situ stress field. Theoretically, any underground opening can be successfully supported under any geological and mining conditions if the opening width is limited and the roof supporting system is well designed. However, roof control cost must be taken into account. In practice, to minimize the roof control cost, different roof control plans have to be considered to take care of the uncertainty or variation in geological and mining conditions. For most underground mines, it is unsafe or economically unrealistic to use one fixed roof control plan for the entire mine. Therefore, local, abnormal geological and mining conditions must be identified and a site- or area-specific roof control plan must be employed. This study tries to identify the major factors that have significant impact on entry roof stability by analyzing the historical roof fall data at Rofomex mine. Finally, the appropriate roof control plans or roof bolting systems for different geological and mining conditions are recommended.

Jan 1, 2011