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By MANZOOR ALI BROHI, IZHAR MITHAL JISKANI, Atta Ur Rehman, SHUAI HAN, MUHAMMAD TARIQ, NIAZ MUHAMMAD SHAHANI

The analysis of mine safety indicators using a scientific method can improve mine safety and assist management in making informed decisions. This research establishes a mine safety evaluation index and proposes an integrative evaluation model based on the entropy weight and grey clustering methods. The index consists of 27 indicators classified into seven criteria: working environment (A), miners’ attributes (B), safety policies and education (E), prevention and control (F), and monitoring and supervision system (G). Using Pakistan’s mine safety situation as a case study, the proposed model categorized the indicators into five safety levels (very low, low, medium, high, very high) for the present situation and for their relevance in terms of future safety improvement. The results show all of the criteria falling into the very low level for the current mine safety situation. Three of the criteria — C, E and G — are identified as having very high levels of significance for future safety improvements.

By L. J. Trilli

RECENT studies have indicated that there may be considerable difference in the cleanliness of the central pipe cavity of open top ingots. It has been speculated that some of this difference arises becausk of reactions that occur during reheating in the blooming mill soaking pits. In this respect, it has been recognized that an oxide coating or flow of slaggy material in the cavity could inhibit welding during hot rolling and thus reduce the amount of sound product which may be obtained. This note is intended to summarize some observations on the structure of a split ingot top which may be useful in describing a mechanism whereby the shrinkage cavity could be oxidized during reheating. A 221/2x241/2 in., big-end-down, test ingot was secured from a routine production heat. The chemical analysis representing this ingot is as follows: 0.08 pct C, 1.04 pct Mn, 0.062 pct P, 0.315 pct S, and 0.02 pct Si. The deoxidation practice used on the heat from which the experimental ingot was

Jan 1, 1957

By B. Derin, T. Uzunoglu, O. Yücel

In this study, reduction behaviours of Turkish chromite concentrate (48 % Cr2O3, 13.30 % FeO, 18.33 % MgO, 12.37 % Al2O3, 5.76 % SiO2) and nickel oxide by Fe-C alloy in graphite crucible were investigated. In the first stage of experiments, steel scraps were melted in graphite crucibles and were saturated with carbon at 1600 °C and 30 min. In the second stage, mixtures of different amount of chromite concentrate, nickel oxide and flux additives (CaO,SiO2 and CaF2) were charged into the graphite crucible containing the Fe-C alloy and heated to 1600 °C for different reduction times (0-180 min) under argon gas. The highest Cr and Ni con-tents in alloys were found as 11.41 and 14.37 % and the highest Cr and Ni recoveries were found as 88 and94 %, respectively at 180 min.

Jan 1, 2007

By Pedro Henrique L. M. Lopes, Édio Pereira Lima Jr., Fernanda Santos da Luz, Fábio de Oliveira Braga, Sergio Neves Monteiro

Several works have been dedicated to study the ballistic response of multilayered armor systems (MAS), including those using natural fiber composites as second layer. These composites disclosed good ballistic performance, having economic and environmental advantages. In the present work, the objective was to investigate the effect of areal densities of each MAS layer, in the overall performance of a MAS with an alumina ceramic front, a curaua fabric reinforced composite filling, and an aluminum alloy backing the target. Ballistic “backface signature” tests were conducted, varying the areal densities of the MAS layers according to a Box-Behnken design. The results showed a similar influence of the ceramic and aluminum layers in the MAS “backface signatures”, although deformation and failure mechanisms were significantly different. The composite also showed significant participation in the overall MAS performance. Since the composite is cheaper and lighter, a balance minimizing the other layers would be advantageous.

Mar 1, 2018

By L. M. Pidgeon, K. T. Aust

There has been considerable interest in the possible use of titanium in magnesium alloys.' Zirconium has shown some promise in this connection2 and its general similarity with titanium suggests that the latter might act in a similar manner. A literature survey revealed that quantitative data on the Mg-Ti system was unavailable. Several patents3 have claimed that titanium additions from 0.2 to 4 pct to magnesium alloys were possible, but no mention was made as to the form in which the titanium existed in the alloy. Kro114 succeeded in introducing only traces of titanium into magnesium by bubbling TiCl4 through the metal under argon or by reacting it with sodium titanium fluoride. The application of theoretical data given by Carapella5 based on Hume-Rothery's principles, involving atomic size factor, crystal structure, valency and the electro-chemical factor, suggests that a Mg-Ti alloy is a favorable case, and the system appeared to warrant experimental examination. Experimental Procedure and Results THERMAL ANALYSIS If titanium is appreciably soluble in magnesium, a change in the melting point of the magnesium might be detectable using standard cooling curve methods. Magnesium was melted in graphite crucibles under an argon atmosphere, the assembly being enclosed in a silica tube. Graphite thermocouple protection tubes served also to stir the melts. The apparatus was very similar to Fig 1, with the addition of a refractory and baffle system to prevent undue heat losses from the top of the crucible. Chromel-alumel thermocouples were calibrated using Al of 99.97 pct purity. Dominion Magnesium Limited sup- plied redistilled high purity magnesium of the analysis given above. Titanium was added in three different forms: 1. Titanium powder —100 mesh, from the Titanium Alloy Manufacturing Co., Niagara Falls, N. Y. 2. Sheet titanium from the U.S. Bureau of Mines, produced by Mg reduction of TiCl4. 3. Magnesium —50 pct titanium master alloy from Metal Hydrides Inc., Beverly, Mass. The melting point of the high purity magnesium used was measured experimentally as 651.0°C. More than a dozen tests were conducted using titanium from the three sources referred to above, in calculated additions up to 20 pct titanium, at temperatures between the melting point and 1000°C and holding periods up to 6 hr. In no case was evidence obtained of solubility of titanium in magnesium, using inverse-rate and time-temperature curves. The melting point of the magnesium was unchanged within the accuracy of measurement, namely -+0.5°C; and no other thermal arrests were detected. Metallographic investigation of the thermal analysis billets indicated that the titanium additions were apparently mechanically entrapped in the magnesium in segregated areas. Consequently, these samples were not analyzed for titanium. The master alloy proved to be a mechanical mixture of titanium particles in a magne- sium matrix. These results indicated that the titanium solubility, if such existed, could not be obtained by the usual thermal methods. X RAY DIFFRACTION INVESTIGATION In an effort to detect solubility of titanium in magnesium, samples were investigated using both the Debye-Scherrer and the Focusing Back-Reflection methods. Filings from samples of the thermal analysis billets and from pure magnesium were annealed in argon one hour at 350°C to relieve mechanical strain. Measurements made of the interplanar spacings showed no difference between the Mg-Ti samples and pure magnesium. The interplanar spacings could be measured to within 0.0002A, and the greatest variation found was 0.0004A, in the back-reflection method. The diffraction lines for magnesium were not shifted by the titanium additions indicating that the solid solubility of titanium in magnesium is of a very low order—less than 0.5 pct. From both diffraction methods, a d or interplanar spacing of 0.817A was obtained for the redistilled high purity magnesium. This latter value is not given in the standard X ray diffraction cards for magnesium metal or vacuum distilled magnesium. Theoretical calculations for a close-packed hexagonal space lattice for magnesium indicate that the planes {2134) should give a line which was found. The relative intensity for this reflection at 0.817A is slightly less than that at 0.870k for magnesium. SOLUBILITY OF TITANIUM IN LIQUID MAGNESIUM The Mg-Mn system was examined by Grogan and Haughton6 who were

Jan 1, 1950

By K. V. Raj

In the mining industry, computational fluid dynamics (CFD) modeling is used extensively to simulate air flow in underground mines. CFD modeling of pollutant transport in open-pit mines is relatively new. Modeling the actual pit geometry of an open-pit mine and the open domain is complex. The complexity is primarily due to the faceted geometry of an open-pit mine with its numerous associated sharp features. Important issues that are not considered carefully at the geometry level are generally propagated to the subsequent processes. Several challenges and pitfalls are encountered in modeling pollutant transport in open-pit mines. These challenges and pitfalls are related to the geometry, meshing, boundary conditions, and turbulence modeling parameterization. An appropriate mesh selection is critical. A detail discussion of the meshing of the domain of an open-pit mine is presented in this paper. The selection of an appropriate turbulence model, such as kappa-epsilon (?-e), large eddy simulation (LES), Reynolds stress model (RSM), etc., to obtain the best possible solution is equally significant. This paper discusses the various challenges in modeling the pollutant transport process in an open pit and some of the approaches adopted to address these challenges.

Feb 27, 2013

By D. A. Wilson

A cyclic leaching process was developed for selectively leaching and recovering cadmium from nickel-cadmium scrap battery waste. The six major steps in the process are the following: (1) washing the plates to remove KOH electrolyte, (2) roasting at 550° to 600° C to oxidize metallic cadmium and decompose cadmium and nickel salts, (3) leaching with an ammonium nitrate solution, (4) precipitation of the leached cadmium from solution as cadmium carbonate using CO2 gas, (5) removal of CO2 from the lixiviator by adjusting to pH 4.5, heating, and evacuating the system, and (6) removal of small amounts of leached nickel from the lixiviator using a solvent extraction technique. The regenerated lixiviator is then recycled to leach additional plates. Cadmium extraction was 94 percent and the cadmium carbonate product contained 0.14 percent nickel and 0.12 percent cobalt impurity. The leached plates were smelted to a high nickel-low iron alloy with no detectable amounts of cadmium.

Jan 1, 1971

By R. V. Higgins

This report presents computer instructions for calculating the performance of three-phase flow of gas, oil, and water. The calculated results for an illustrative example are presented. The example is the waterflood of a reservoir containing free gas in the reservoir as a result of the partial depletion of the oil by the expansion of the gas initially in solution. The flood pattern for the example is a 5-spot.

Jan 1, 1967

By Burrows. A.

Temperature profiles in the lead smelter sinter bed at Xstrata Zinc Mount Isa sinter plant have been measured using a wireless temperature probe. Corresponding sinter samples have been collected for characterization. The sinter peak bed temperatures were found to be in the range of 1000 - 1200 °C. Microstructures and softening temperatures of these sinters have been characterised. Strong correlations have been observed between peak bed temperature and peak hood temperature, and between mean sinter softening temperature and peak bed temperature. It was found that higher peak bed temperature results in higher sinter softening temperature. For the feed material used in the trials, to obtain sinters with mean softening temperatures above 1050 °C, peak bed temperatures above 1130 °C are required. There appears to be a direct correlation between granule size distribution in the feed and peak bed temperature attained. High peak bed temperatures are observed in sinters with narrow granule size distribution.

Jan 1, 2008

By Wenbo Lu

A combined method is present in this paper in analysis the dynamic stability of rock slope under the loading of blast induced seismic, in which, by combining the dynamic load calculating method of quasi-static method with the load inputting method of dynamic finite element method, such factors as the decay of seismic wave along its way of propagation, the frequency. amplitude. the phase difference of seismic wave, etc., can all be taken into account in analysis of the dynamic stability of slope.

Jan 1, 1999

By J. P. Savely, D. E. Nicholas, R. D. Call

Progress in the technology of slope design over the past 15 years now permits the selection of rational slope angles if suitable data on geology, hydrology, and rock properties are available for a specified project. Although a full-scale slope design study remains the best course of action, there are situations where an extensive study is not feasible due to time or budget constraints. Two typical examples are: (a) selecting pit slope angles for a preliminary feasibility study at the exploration stage; and (b) coping with a slope failure in an operating mine. In both instances, slope angles must often be chosen on the basis of data that are currently available or can be readily obtained. All too often during exploration programs, a feasibility study is initiated shortly before the decision deadline to drop the property or proceed to purchase. If the only existing data at this point are a few cross-sections at odd angles showing ore and waste contacts or a dog-eared map of the surface geology, there may not be time to collect and organize sufficient information for the design of slope angles. On the other hand, if during the drilling program geologic cross-sections were constructed and the structural data compiled in tabular form, rational slope angles could be computed within the allotted time.

Jan 4, 1977

By Shadia J. Ikhmayies

CdSxTe1-x and CdS1-yTey solid solutions are usually formed in the interfacial region in the CdS/CdT thin film solar cells during the deposition of the CdTe layer and/or the processing steps of the device. It is well known that CdCl2 heat treatment encourages the formation of the CdSxTe1-x alloy which improves the solar cell performance. In this work, indium doped CdS1- yTey thin films are produced by first producing CdS:In thin films by the spray pyrolysis (SP) technique on glass substrates, then annealing the films in nitrogen atmosphere in the presence of elemental tellurium. The films are characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmittance measurements. The transmittance is used to deduce the optical parameters such as; the extinction coefficient, refractive index, besides to the real and imaginary parts of the dielectric constant. The dispersion parameters such as Eo (single-oscillator energy) and Ed (dispersive energy) of the deposited films are also estimated and discussed.

Jan 1, 2015

By Bruce Chalmers

INTRODUCTION TIE most important practical problem with which Physical Metallurgy is faced is the control of the mechanical properties of alloys. The most difficult aspect of this problem is the development of new alloys with the properties that are required for meeting exacting engineering requirements. A great measure of success has been achieved by following the empirical method and most, if not all, of the present variety of alloys have been developed by the process of experiment and observation or trial and error. It may, however, be that this method will become. less productive as time goes on, and that eventually it should be replaced by a process based on an understanding of the factors that determine the properties, so that alloys can be 'designed' to meet the requirements. This method of investigation will not be possible until a much better fundamental understanding of metals has been gained, and this will come only about as a result of a great deal of detailed research. The subject of Physical Metallurgy can be divided, as follows, into two parts: we may consider the factors which determine the structure, in the broadest sense, of an alloy. These include the composition and also the treatment to which the material has been subjected. The second aspect is the influence of the structure on the mechanical and other properties. In order to make an effective contribution in this field, it is necessary for an individual or a group to concentrate on a specific and very restricted topic. It is proposed to discuss in some detail the particular subject in which the writer and his colleagues are working.

Jan 1, 1951

By M Lovitt, T Hewitt

The extraction of drawbells in Lift #2 at Northparkes Mines E26 orebody was achieved by single shot blasting, enabled through the use of electronic detonators. This paper discusses the designs considered at the time of the feasibility study and the various changes made to these designs prior to and during the construction phase of the Lift #2 block cave. Operational issues encountered are highlighted, as are ways in which these were overcome. The amount of personnel utilised to mine the drawbells is also covered. Lists of design and operational considerations to be used for drawbell extractions have been included.

Jan 1, 2005

By Patricia Martínez Nicolás

Nickel and ferronickel are some of the major components in the production of special alloys; however, the energy consumption for their production greatly increases their price. A cheaper option could be to use NiO and a reducing agent. This work presents experimental and theoretical analysis to estimate the effect of slag basicity and amount of reducing agents on the NiO reduction from the slag which interacted with molten steel at 1600 °C in an EAF. The slag system contained CaO, SiO2, CaF2 and NiO together with a reducing agent, ferrosilicon or carbon. The NiO content in the slag was 25 mass%. The amounts of the reducing agents (Si and C) were 1 to 4 times the stoichiometric mass to reduce NiO. The CaO/SiO2 ratio was 1.5 and 2.5. The kinetics of the process was very fast since after few minutes the maximum nickel yield was obtained. The slag basicity had a negligible effect on the reduction of NiO.

Jan 1, 2006

By Robert K. Towner, Francis S. Kendorski

Shotcrete drift linings at the Climax Mine of the Climax Molybdenum Company have undergone four years of extensive evaluations as a replacement for thick poured-in-place concrete linings. Any drift lining at Climax must be able to withstand the rigors of undercut and secondary blasting, weight problems induced by panel caving, and the abrasion of slusher mining. Examined here are the conclusions reached so far on shotcrete drift linings which have not yet completed the approximately six-year cycle from development to ore exhaustion. Properly applied shotcrete is an adequate drift lining for all phases of the Climax panel caving system of mining. Undercut blasting will damage shotcrete unless blasts are correctly timed. Weight problems will destroy shotcrete drift linings as efficiently as it will destroy concrete or steel support systems. Abrasion and secondary blasting results are inconclusive as the shotcrete lined slusher drifts have not entered the ore production stage of the mining cycle. In addition to drift linings, Climax has found shotcrete to be invaluable for lining large underground shops, for temporary support systems, for permanent ventilation bulkheads and for the repair of abraded or weight damage concrete lined slusher and haulage drifts.

Jan 1, 1974

By J. A. Zimmer, M. S. Hillis, D. Moredock, J. A. Organiscak, A. B. Cecala

Enclosed cabs have been used on surface mining equipment for many years to protect equipment operators from health and safety hazards. The surface mining and quarrying process is a highly mechanized process that generates large quantities of respirable dust. Due to economic factors, more older mining equipment is being used today than in years past. With this older equipment, it is common to observe deterioration of many components on the enclosed cabs, which greatly reduce their protection effectiveness. NIOSH has performed a number of different field studies, as well as a comprehensive laboratory study, evaluating various factors and parameters regarding enclosed cabs. NIOSH has recently completed a cooperative research effort to evaluate the effectiveness of a newly designed unidirectional powered precleaner, filter and pressurizer that brings clean filtered air in at the roof of the cab and extracts all recirculated air near the floor. This research effort provided another example of the enhancement in air quality that can be achieved in an enclosed cab from the implementation of an improved filtration system and by establishing positive pressurization from increased intake air volume and sealing the cab. This testing showed a significant reduction in respirable dust levels in the enclosed cab when comparing baseline versus post-testing results. Since dust levels were similar near the roof and floor of the cab during post-testing, the unidirectional flow pattern did not appear to significantly improve the performance over the conventional design in this study.

Jan 1, 2009

By L. Zhou, L. Yuan, D. Bahrami, Y. Xue

Underground mine accidents, such as mine fires, remain a health and safety risk to mine workers. Researchers at the National Institute for Occupational Safety and Health (NIOSH) are developing a data-driven, predictive model for characterizing the location and size of unknown underground fires. This study examines applying a machine learning-based model to predict fire size and location in a large underground metal mine based on hypothetical scenarios on the model performance. The results show that the size and location of an unknown fire can be determined with over 80% and 90% accuracy, respectively, and potentially help to reduce the risk of hazardous conditions for emergency response.

Feb 1, 2024

By K. L. Marshall

A facetious title was purposely given this talk, so that a formal paper would not be expected. TWO or three days ago, while discussing with Mr. Dickinson some of the details of the dust explosion demonstrations we are planning for this coming Saturday, I remarked that we would like to have as many people as possible see some samples of 20 and 200 mesh dust, so they would more fully understand just what was causing the explosions. Mr. Dickinson requested that I bring samples and screens and in this informal manner, give you all a ".close-up" of coal dust which is considered in Explosion Hazard reports. While sampling mines, for road, rib, and roof dust, in connection with safety service and hazard reports which the Bureau of Mines Engineers make at the request of coal operators, I have often been assisted by under- ground mine officials or other men of many years experience and on almost every occasion, while we were carefully brushing the very fine dust from timbers or coal surfaces, they would make some remark such as: "never had noticed this kind of dust, didn't know it was here", or "well, that's the first time I really understood what all 'this dust talk was about." Such experience makes me believe that the much published terms, 20 mesh and 200 mesh are just numbers to the great majority of both miners and operators. We are now going to have lesson one in the primer of coal dust explosions and I want to say, in all sincerity that a complete course in the hazards of mining is deserving of a place in the curriculum of the best mining schools of this country. Sample No. 1 is fine coal and dust and is a fair sample of what can be found every where in rooms and entries of a mine, as it is too small to be gathered up with a shovel and is left in the ordinary mining at the faces and is spilled along the entries in haulage. In this you will see some quarter inch coal, much eighth and sixteenth inch coal, in fact those are the sizes I find many people have in mind when they are asked about the dust made in mining. Although the sizes mentioned are the ones which seem to almost entirely make up this sample, such is not the case, for from 10 to 20% of such a sample will usually pass this 20 mesh screen and in Sample No. 2 we have 20 mesh dust. Result of many tests, supports .the statement of the coal mining division of the Bureau, that it is quite probable that coal over 20 mesh does not take part in any but the most violent of explosions and that all dust under 20 mesh may take part in any explosion. The largest particles in this sample will not be over .03 inches in their largest dimension and a pound of dust to a foot of average heading is very easily found in most every mine I have visited and usually a great deal more can be readily gathered up. It was .found early that the finer the dust the more dangerous it was for a given coal. So for the early explosion tests conducted by the Bureau a commercial pulverizer was used and it turned out a 20 mesh dust of which about 75% would pass 200 mesh. Some men question whether the ordinary mining methods made such a dust and so doubted the explosibility of the dust in their own mines. The question was well taken, and hundreds of dust samples were taken by the field men of the Bureau to determine the kind of dust being made in all methods of mining and all classes of coal. The result of such sampling showed some coals. resisted breakage more than others and that actual mine road dust, through 20 mesh, would show from 10 to 20% through 200 mesh, and for actual rib and roof dust through 20 mesh, they would get from 20 to 40% of 200 mesh dust. In testing the

Jan 1, 1924

By A. L. Mular

Steady-state material balances calculated from data measured at various locations around process units are useful for many purposes, such as metallurgical accounting, on-line control, and the development of mathematical models. Often it is possible to calculate material balances by several independent procedures when excess measurement information, i.e., redundant data, is available. Clearly, if the data were collected without measurement errors, a theoretical condition never found in practice, all material balances calculated from redundant data would be in agreement. The real situation is that error exists in practical measurements, so that the results of material balances determined from available optional procedures differ. Consequently, best fit computational procedures to improve the material balances by taking measurement errors into account have been formulated. Such procedures can be used also to judge whether measurements are grossly in error due to either faulty observations or defective data sensing devices. A variety of mathematical techniques are available which serve to adjust raw data. The adjusted data permit mass balancing that does not depend on the computational method. To illustrate the need for an adjustment procedure, Table 1 shows a raw data set acquired around the Brenda Mines Ltd. No. 4 grinding circuit shown schematically in Fig. 1. At least seven optional ways to calculate a circulating load ratio may be employed. These are shown in Table 2 where, depending upon the calculation [ ]

Jan 1, 1979