The paper presents a global perspective of the current technologies used for steel production and the steel markets. The iron and steel industry is a very complex sector that is strongly related with the rest of the economy due to the importance of steel products for industries such as construction, automotive, and other manufacturing sectors. Moreover, the iron and steel industry demands significant amounts of raw materials and energy, and most companies producing raw materials are located remote from the areas of highest steel demand. In consequence, both steel products and inputs are traded internationally (mostly by sea) and in large quantities, what additionally complicates analyses of the iron and steel industry. Steel prices depend on several variables, and there is not a single price for steel since there is a great variety of steel products traded. Those prices depend on supply and demand interaction (between steel producers and consumers, but also on interaction with other industries competing for the same inputs), and on transport conditions. As concerns the ownership structure, the steel industry consists of some large firms that operate globally and produce significant output, and many small firms that operate at a lesser scale. Recently, some of those firms have consolidated into large multinationals (such as ArcelorMittal, formed in 2006 by the merger of Arcelor and Mittal Steel, Arcelor being the result of the previous merger of Aceralia (ES), Usinor (FR), and Arbed (LX) in 2002). The results of this article form the basis for further long- and mid-term analyses of the development of the global steel industry. The main conclusion of the paper is that any future analysis of the iron and steel industry should be based on quantitative modelling tools that: (i) properly capture the technological diversity of the industry and the key features of the supply chain, (ii) are able to consider the strategic behaviour of all the key players of the industry, and (iii) consider all those factors at the global scale.
Proper values of physical and mechanical properties and their homogeneity are one of major requirements deciding about technological suitability of the rocks quarried to manufacturing aggregates. These properties depend on the natural features of a rock, its mineral composition, texture and structure. The characteristic of aggregates and the technical requirements they must meet are normalized in adequate standards that describe the procedures of conducting particular determinations and the methods of interpreting their results. In the basaltoids (usually called basalts) of selected deposits of Lower Silesia that represent different intrusive forms, five textural varieties have been distinguished: aphanitic, aphanitic-porphyritic, porphyritic-aphanitic, porphyritic-nodular and nodular-porphyritic. The petrography and essential physical and mechanical properties of these varieties have been described in Tables 1 and 2, respectively. The highest technical parameters have the aphanitic and aphanitic-porphyritic rock varieties. They result mainly from the textures of these rocks and their insignificant weathering, and to a lesser degree from their mineral composition. The resistance to wear (micro-Deval) and the resistance to fragmentation (Los Angeles) of the aggregates that represent the grain fraction 10-14 mm of the five varieties of basaltoids and the rock composites were determined according to the standards PN-EN 12620: 2008 and PN-EN 13043: 2004. Of the aggregates produced from the five major varieties, only those made of the nodular-porphyritic basaltoids have the properties of lower categories, whereas the remaining four are the materials of very high quality. Additionally, it has been shown that by combining various basaltoid types it is possible to produce composite aggregates with the variable qualities belonging to the categories LA and MDE (Tab. 3). The effect of rock petrography on the differentiation of the parameters of aggregates depending on the grain fraction of the products (Fig. 1, Tab. 4) is the lowest in the case of the aggregates produced from the homogenous and not weathered rock. In contrast, the range of variability of the parameters is higher if the starting material to produce aggregates is composed of several textural varieties and shows signs of weathering as well. The possibility of delineation of the areas occupied in the deposit by basaltoids with specific textural varieties creates the conditions of determining the rock zones, from which the aggregates of the predicted quality may be produced. This quality may be controlled and partly changed to the user needs by producing aggregates from the specially prepared rock mixtures (i.e. the charge to crushers) with specified proportions of the basaltoid varieties.
The paper presents the application of the Analytic Hierarchy Process technique to evaluate and choose the best alternative for acquiring hard coal for energy purposes by a potential Investor operating in the mining and energy sector. Six different sources supposed to provide hard coal were analysed, each of which might ensure a secure and independent supply of the material to the newly built coal-fired power plant. When choosing the best decision alternative, the positive and negative impacts of alternatives were considered through the BOCR analysis: benefits (B), opportunities (O), costs (C) and risks (R) analysis. For this purpose, 4 independent hierarchical models were developed. Different models have the same decision alternatives assessed, but they differ in criteria used to develop the models. In each of the models, in accordance with the AHP rules, were calculated final, global weights for the alternatives being assessed. Showing the best alternative was possible by applying the multiplicative formula (B ź O)/(C ź R), which value was used to rank and choose the best alternative from all assessed ones. The best decision alternative is the alternative where the (B ź O)/(C ź R) ratio is the highest.
Complex circuit of milling-classify systems are used in different branches of industry, because the required particle size distribution of product can seldom be reached in a single-stage grinding on the same device. The multistage processes of comminution and classification make possible suitable selection of parameters process for variables graining of fed material, mainly through sectioning of devices or change of their size and the types. Grinding material usually contains size fractions, which meet the requirements relating finished product. Then profitable is preliminary distributing material on a few size fractions, so to deal out with them demanded fraction of product, whereas remaining to direct alone or together with fed material to the same or different device. If the number of mills and classifiers in a circuit is large enough, building the model of particle size distribution transformation becomes rather complicated even for the circuit of a given structure. The situation becomes much more complicated, if we want to compare characteristics of all possible circuits, that can be constructed from these mills and classifiers, because the number of possible circuits increases greatly with the increase of number of devices being in the milling-classify system. The method creating matrix model for transformation of particle size distribution in a circuit of arbitrary structure of milling-classify system is presented in the article. The proposed model contains the mass population balance of particle equation, in which are block matrices: the matrix of circuit M, the matrix of inputs F and the matrix of feed F0. The matrix M contains blocks with the transition matrix P, the classification matrix C, the identity matrix I and the zero matrix 0 or elements describing the transformation of particle size distribution in the circuit. The matrix F is the block column matrix, which elements describing all particle size distributions at inputs to the circuit elements. The matrix F0 is the block column matrix, which elements describing particle size distributions in all feeds to the circuit. In paper was discussed this model in details, showed algorithm and three examples formatrix construction for the closed circuit ofmilling-classify systems. In conclusion was affirmed, that presented model makes possible to forecasting particle size distribution of grinding product, which leaving chosen the unit of system. The matrix model can be applied to improving modeling of mineral processing in the different grinding devices.
The safe environmental disposal of sulphide-rich copper/zine mine tailings is fast becoming a major economic factor in determining the profitability of mining operations. There have been new approaches and better technologies practised in the recent years which allow the mining industries to reduce and/or eliminate the environmental impacts of harmful mine tailings. One of these approaches is the use of high-density paste backfill (HDPB) which is consisting mainly of a mix of solid particles (with the cement) and water, containing between 70% and 85% by dry weight of solids. The increased use of HDPB has improved the reliability, and has reduced the cost of the preparation and transportation systems. This paper focuses on the potential environmental benefits of using the HDPB when tailings are acid generating, and also provides a case study conducted in an underground copper/zinc mine in northeast Turkey in order to illustrate these benefits.
The cenospheres are formed during the mineral transformation stage in coal combustion. Their content in fly ashes from the combustion of different types of coals varies over a rather wide range from 0.01 to 35.6 wt.%. The cenospheres has three main elements, silicon, aluminium and iron, the oxides of which account for about 89% of the material. Mineralogical analysis using XRD shows that as-received cenospheres mainly contain mullite and quartz as main mineralogical phases. The size of cenospheres varies between 5 and 500 [...], as the most common dimension is 20-300 [...]. The cenospheres are characterized by a low bulk density (0.2-0.8 g/cm3) and can be easily separated by gravitational methods in the form of a concentrate in aqueous media or collected from a water surface of lagoons intended for storage of ash and slag waste. The unique properties of these hollow microspheres make them amenable for wide applications. For example the cenospheres can be used to produce various lightweight construction products, including lightweight cements and aggregates in lightweight concrete.
Acid mine drainage (AMD) is widespread environmental problem associated with both working and abandoned mining operation, resulting from the microbial oxidation of pyrite in presence of water and air, to form an acidic solution containing metal ions. The present study aims to adjust low pH, remove iron, manganese and sulphate from AMD generated at open pit Jiří and depth Jiří, Sokolovská uhelná, Czech Republic. The local AMD is very problematic due to its composition and process taking place in the Water Preparing Plant Svatava (WPPS), where only pH value is adjusted and mainly high concentration of iron and suspended solids are removed.
Oil can be produced from reservoirs by use of primary methods that use natural reservoir drive, secondary methods, involving a physical displacement of oil and tertiary (enhanced), in which additional types of energy support oil recovery. About 25-35% of original oil in place for light and medium oil and about 10% heavy oil could be extracted by primary and secondary methods. Injection of CO2 into the oil fields (CO2-EOR) is one of the tertiary oil recovery method. Carbon dioxide is used for increasing oil extraction due to the fact that: to maintain reservoir pressure, reduces the oil viscosity and facilitates its movement in the reservoir, reduces density and increase the volume of oil, interacts with rocks. Depending on the oil composition and the reservoir pressure and temperature injected carbon dioxide can displace oil from the reservoir miscible or immiscible. Additional 10-20% of the oil extraction over primary and secondary methods recovery can be obtained under the miscibility conditions, in immiscibility condition additional oil production is lower. EOR method selection depends on many geological, reservoir and economic parameters. These include: density, viscosity and composition of the oil, minimum miscibility pressure, the recovery factor and vertical and horizontal reservoir variability. Using the above criteria appropriate EOR method for given oil field can be selected. The five parameters: the reservoir depth, the oil density, pressure and temperature of the reservoir is used for the selection of oil fields suitable for miscible oil displacement.
The subject matter of the articles published in Mineral Resources Management covers issues related to minerals and raw materials, as well as mineral deposits, with particular emphasis on:
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