Development and Testing of Down-the-Hole Deployabe X-Ray Florescence Spectrometer

To allow a truly in-situ elemental analysis, an Australian resource company commissioned the development and building of a down-the-hole deployable ED-XRF sensor. The instrument was designed to be deployable up to a depth of 30 m for drill holes of varying diameters as well as being run in a bench-top mode. Following the development and upon commissioning, the ED-XRF system was investigated in the laboratory for its suitability for use in the Iron Ore industry by using well characterised crushed iron ore samples, standards made from analytical reagents and large iron ore rocks that had been sectioned to provide a curved surface for presentation to the XRF. The effects of operating conditions and other parameters were studied using the standards made from the analytical reagents. It was found that the system could be used to determine the elemental Fe content with reasonable accuracy when used on crushed powder samples. The curved surfaces of the sectioned rocks increased the variability of the amount of Fe detected. Two trace elements, Al and Si were also investigated using the same methodology. It was found that the ED-XRF system was not suitable for distinguishing the Al and Si. This paper outlines the ED-XRF system used, the testing methodology employed and the results of the laboratory testing

Gouging abrasion test for rock abrasiveness testing

Wear parts of many mineral processing and mining equipment are often subjected to high stress loads applied at high speeds and at varying angles of incidence, where the prevalent mode of wear is high-stress gouging/sliding impact abrasion. Examples include crusher liners, wear liners in hoppers and chutes, picks on roadheaders, discs on tunnel boring machines and ground engaging tools. Abrasion under these conditions is characterised by a high material removal rate and thus has a direct bearing on wear rates and service life of the equipment concerned. However, at present there appears to be no method for rock abrasiveness assessment under these conditions. This paper describes a new Gouging Abrasion method and apparatus for testing abrasivity of rocks under high-stress gouging/sliding impact wear. A Gouging Abrasion Index (Gi) is introduced, which can be used for prediction and assessment of component life expectancy and efficiency of mineral processing and materials handling equipment. Experimental data from Gouging Abrasion testing of numerous Australian rock types are presented. It is suggested that the results of Gi testing can be used for wear rate predictions for a variety of mineral processing and materials handling equipment working under high-stress gouging/sliding impact abrasion condition

Elastic Properties of Steel-Cord Rubber Conveyor Belt

Reinforced with steel-cord rubber conveyor belt (SCB), i.e. a unidirectional composite material (CM) with some of the fundamental mechanical properties values of its reinforcement and matrix differing by a factor of ten thousand, is a key infrastructure component of overland minerals transportation industry. Critically, to date no investigative work has been performed on the mechanical behaviour of SCBs subjected to the extreme dynamic-loading conditions of tropical cyclones, hurricanes, and tornados. Determination of a full suite of elastic characteristics of the belt will enable the study of the mechanical behaviour of SCB subjected to these natural hazardous wind events. We investigate tensile and shear moduli of a commercial SCB with the use of modified standard practices and innovative approaches, including tensile testing and methods of torsion of long straight bar and of square plate. We propose a novel design of mechanical tensometer which allows tensile testing of significantly shorter test specimens as compared with the test specimen dimensions per current standards. Analytically, tensile modulus is determined using the rule of mixtures and shear moduli are calculated based on the variational principles. We find that the tensile modulus of SCB can be determined analytically with high confidence. However, analytically derived in-plane shear moduli values can only be considered as a first approximation and need to be verified experimentally. The results of our work improve understanding of stress-strain state and thus can help predict the mechanical behavior of the SCBs under the irregular and extreme dynamic loading conditions of natural hazardous wind events

On the optimal model configuration for aerodynamic modeling of open cargo railway train

This study is concerned with the optimal model configuration for aerodynamic modeling of long open cargo railway trains. Frontal air drag of several train configurations was studied using numerical modeling and physical i.e. wind tunnel testing of 1:40 scale railcar models in a range of cross-wind angles. In a long train, the locomotive and the last railcar influence the aerodynamic characteristics of the first three and the last three railcars only. Aerodynamic performance of all other railcars in the long train is similar and can be represented by two inner-train railcars only. A model train configuration combining the shortest computation time with the lowest experimental error was determined from numerical modeling and this was then used for wind tunnel testing. It has been shown that, for long open cargo railway trains the model consisting of six railcars with two streamlined bodies is the optimal configuration, with both the numerical modeling and wind tunnel testing results in good agreement

Plasma blasting of rocks and rocks-like materials: An analytical model

Plasma blasting technology (PBT) is a potential alternative to chemical blasting and mechanical cutting methods for fragmentation of natural rocks, concrete, geopolymers, and other rocks-like materials. We present an analytical model of PBT addressing currently inadequate understanding of the dynamics of shock waves generation and propagation versus the electric energy release conditions. The proposed model describes the operation of the electrical discharge circuit, plasma channel initiation and expansion, and the generation and propagation of shock and pressure waves in the destructible solid. The dynamics of the power generator energy conversion into the plasma channel and into the wave of mechanical stresses in the solid are considered and the main factors determining the efficiency of the method, namely the pulse generator circuit parameters, exploding wire length, and shock wave-transmitting media, are evaluated. Solid fracture efficiency is shown to depend on the pressure pulse wave shape which, in turn, is determined by the rate of electrical energy deposition into the plasma channel. Increasing the exploding wire length leads to an earlier formation of the tensile tangential stresses and to their higher magnitude and thus facilitates material's fragmentation. The use of acoustically stiff media for shock wave transfer marginally improves material's fracture efficiency. Preliminary verification of the functionality of the model was carried out using commercial concretes, with good agreement between the analytically derived and experimentally obtained values. The results demonstrate that the proposed model allows to simulate PBT fracture over a wide range of instrumental and process conditions and can therefore be used for PBT process design, thus realising environmental and economic benefits through significant savings in time and experimental confirmation costs

Security informed safety assessment of industrial FPGA-based systems

The strong interconnection and interrelation of safety and security properties of industrial system which are based on programmable logic (field programmable gate arrays, FPGA) is reviewed. Information security, i.e. system's ability to protect the information and data from unauthorized access and modification, is a subordinate property with respect to safety of many instrumentation and control systems (I&Cs), primarily to the NPP reactor trip systems. Such subordination may be taken into account by implementation of security informed safety (SIS) approach. The methodology for safety assessment of FPGA-based systems which are widely used in industrial critical systems is described. It is based on joint using of security analysis techniques (GAP-analysis and intrusion modes, effects and criticality IMECA analysis) and also their reflection on the final safety assessment picture of the system with two channels. This methodology forms so called security informed safety approach. Additional aspects of safety assessment of diverse instrumentation and control FPGA-based systems for safety-critical application are described

Vibration-induced phenomena in bulk granular materials

Vibration is one of the mechanisms affecting bulk granular materials behaviour in transportation and material separation efficiency in pharmaceutical, chemical, food, mineral processing and other industries. Understanding fundamentals of vibration and their influence on bulk materials handling is gaining an increasing importance in the economies of scale. However, at present there appears to be no accurate and sufficient description of various phenomena observed in a granular material affected by vibration. This paper presents a concise review of physical phenomena observed in bulk granular materials affected by vibration, taken here as mechanical oscillations of relatively low amplitude and relatively high frequency. This includes three main characteristic regimes of vibration defined as vibro-fluidisation, vibro-compaction and vibro-boiling. The analysis of other factors influencing bulk granular material behaviour under vibration including air resistance, wave effects and particle oscillations decay are also given. A new characteristic regime of vibration is introduced, defined as vibro-hovering. Description of main characteristic vibration-induced bulk granular material states combined with the analysis of other contributing factors result in a more complete classification of vibration phenomena and an improved understanding of vibration-induced bulk material behaviour. Analytical conclusions are supported by the results of experimental studies, with significant potential for improvement in material separation efficiency indicated. Prerequisite vibrational parameters for effective bulk granular material flow promotion are discussed with a specific focus on physical separation processes and optimum ranges of vibrational parameters for separation and flow promotion of dry particulate matter are recommended

Low-temperature magnetic properties of chalcopyrite (CuFeS2) studied by 63,65Cu-NMR and 57Fe-Mössbauer spectroscopy

Chalcogenide minerals exhibit a fascinating variety of crystal-chemistry and physical properties that is of both scientific interest and potential practical application value. The role of ternary chalcogenide CuFeS2 (referred to as chalcopyrite) should be specially emphasized. On the one hand, chalcopyrite is known as a very important commercial source of copper ore. On the other hand, chalcopyrite-based chalcogenide group of minerals is considered as a perspective generation of solar cells. This is due to their high optical absorption coefficient when compared with known materials, with their energy band gap varied within the range of 0.8-3.5 eV by controlling chemical composition. This is also the reason for these materials finding wider application in optoelectronic devices. From scientific point of view, CuFeS2 has drawn strong interest as an antiferromagnetic semiconductor. One of known specific features of CuFeS2 is the occurrence of polymer-like structure consisting of –Cu–S–Fe– chains. This structure leads to the presence of several unusual properties of electronic and magnetic origin. Particularly, the values of Fe magnetic moments in CuFeS2 with 3.85μB are significantly less than those for the magnetic trivalent Fe, necessitating considerations of valence states of iron and copper ions [1]. Unusual behavior of electrical resistivity of chalcopyrite leads to the discussions about the nature of its electronic type (for example, zero-gap semiconductor [2] or unusual insulator of Haldane–Anderson type [3]). Neutron diffraction examination reveals phase transition in CuFeS2 at 50K temperature [4], however earlier Mössbauer studies provide no evidence of such behavior [5].Thus, clarification of the points mentioned above requires comprehensive study of local properties of CuFeS2 and local methods providing experimental information at micro- and nano-scale are most suitable for this purpose. In addition, combination of different local methods appears to be more expedient in complex studies due to the possibility of observing and comparing electron-nuclear interactions using different nuclei probes [6]. Joint application of nuclear resonance spectroscopic methods (Mössbauer Effect and NMR, NMR and NQR, Mössbauer Effect and ENDOR and other) are some of the examples of such joint experimental techniques. In this report, we present some preliminary results of chalcopyrite studies by simultaneous application of two nuclear resonance spectroscopic methods at low temperatures: 63,65Cu nuclear magnetic resonance (NMR) and 57Fe Mössbauer Effect. In particular, at approximately 50K temperature we have experimentally observed rapid deviation of CuFeS2 relaxation parameters from what is normally considered as standard behavior typical for the majority of semiconductors. On the basis of the experimental data obtained and their analysis, some aspects of electronic structure and physical properties of CuFeS2 are presented and discussed.[1] C.I. Pearce, R.A.D. Patrick, D.J. Vaughan, C.M.B. Henderson, G. van der Laan, Geochim. Cosmochim.Acta 70 (2006) 4635. [2] L. V. Kradinova, A. M. Polubotko, V. V. Popov, V. D. Prochukhan, Yu. V. Rud’, V. E. Skoriukin, Semicond.Sci.Technol. 8, 1616 (1993). [3] K. Sato, Y. Harada, M. Taguchi, S. Shin, A. Fujimori, Characterization of Fe 3d states in CuFeS2 by resonant X-ray emission spectroscopy, Phys. Status Solidi A 206, No. 5, 1096–1100 (2009). [4] J.C. Woolley, A.-M. Lamarche, G. Lamarche, M. Quintero, I.P. Swainson, T.M. Holden, Low temperature magnetic behaviour of CuFeS2 from neutron diffraction data, Journal of Magnetism and Magnetic Materials L62 (1996) 347-354 [5] H. N. Ok, K. S. Back, E. J. Choi, Mossbauer study of antiferromagnetic CuFeS1-xSex, Phys.Rev.B, vol.50(14), 10327-10330, 1994. [6] V.M. Bouznik, Nuclear resonance in ionic crystals, Nauka, Novosibirsk, 1981