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By L. C. Stilwell

The paper will attempt to identify the threats, however obscure, that could confront the South African platinum industry. South Africa has the largest reserves of platinum group metals in the world, and is the largest producer of those metals. This situation is no different from that which existed in the gold sector fifty years ago. Since then South Africa?s share of world gold production has dwindled, and the gold mining industry has lost its dominance. Unlike gold, platinum has widespread use as an industrial commodity. Its investment value is a minor portion of its total value. It is therefore subject to different market forces. The sheer magnitude of the industry in South Africa obscures the fact that it is a wasting industry, and that South Africa exports almost all its production as a refined metal in the form of autocatalyst. Since Hotelling published his seminal work The economics of non-renewable resource in 1931,the science of mineral economics has developed exponentially. The paper will present a background of mineral economic theory and compare to this the development of the South African platinum industry. Of particular concern to a mineral exporting country is the question of mineral rent?its definition and employment. This will be the mail theme of the paper.

Jan 1, 2006

By F. E. Bash

PREVIOUS to the war, this country depended on Europe for its supply of a number of alloys of great importance in the manufacture of electrical apparatus and equipment. When this source was cut off shortly after the beginning of hostilities and the small stocks in the United States were exhausted, either inferior substitutes had to be used or the manufacture of the apparatus suspended. Since electrical equipment was of primary importance in the prosecution of the war, the substitutes had to be used until the composition and processes of manufacture of the alloys could be determined. Included among these alloys was one generally known as manganin, which is composed chiefly of copper and manganese and which, beside having a low-temperature coefficient of resistance, has a low thermal electromotive force against copper. These qualities make it valuable for the manufacture of electrical instruments and machines in which it is used in the shape of wire, rod, and strip. As a result of these circumstances, an investigation was started to deter mine how manganin could be made on a commercial basis so that a product of uniform quality and the necessary electrical characteristics could be produced. The object was to procure an alloy with temperature coefficient of resistance not greater than T 1 X 10-5 per ° C. and a thermal e.m.f. against copper no greater than that of the imported material. It is characteristic of manganin that the temperature-resistance curve is not a straight line but has a peak, which varies in position with different samples; it is most desirable, however, to have it at a temperature of 25° C. if possible. The coefficients of manganin from all records available ranged from a large negative to a large positive value. The composition as reported by different authorities is given in Table 1. Prof. Matthew A. Hunter, of Rensselaer Polytechnic Institute, made up a number of small melts of manganin in a graphite crucible and the one that he reported as having the best coefficient gave the following analysis: Copper, 83.6 per cent.; nickel 2.5 per cent.; manganese,-13.6 per cent.; iron, 0.3 per cent. An analysis of a sample of German manganin gave the following: Copper, 82.6 per cent.; nickel, 3.8 per cent.; manganese, 12.8 per cent.; iron 0.7 per cent.

Jan 9, 1919

By Vasileios A. Drosos

The response of pile foundations to lateral loads is an important factor for the successful performance of several critical structures. A new numerical code for the analysis of single piles under lateral load is outlined. The code can simulate (through appropriately chosen parameter values) not only the non-linear behavior of soil, but also the inelastic structural response of the pile itself under lateral load. Emphasis is given on the calibration of model parameters and the verification of the code. For the calibration of the parameters, data is used (a) from the well documented in the literature p-y curves, and (b) from experiments conducted either in full scale or in the centrifuge. Results are compared to those of well known published codes for inelastic analysis of single piles under lateral load.

Jan 1, 2006

By E. L. Reed

This paper addresses the state and federal permit- ting requirements and regulatory constraints associated with the development of new "grass roots" surface coal mines in the Western United States. Since a major portion of new coal development in the West will be on federally leased coal in Wyoming, my comments are directed towards that geographical area. This will give the reader some insight into the current regulatory framework within which western mining companies must operate-i.e., the major applicable state and federal laws and regulations, the more important state and federal regulatory agencies, and the major construction and operating permits that are required. Before discussing the impact of the regulations on our business, I would like to tell you something of my company and then briefly discuss Exxon's forecast of the long range outlook for coal. Carter Mining is an Won affiliated surface coal mining company. Exxon became interested in the coal business in the mid 1960's with the recognition of the future need for alternative fuel sources. Since that time, it has acquired coal reserves located in Wyoming, Montana, North Dakota, Arkansas, Texas, Illinois and West Virginia. Carter's first surface mine, the Rawhide Mine, located north of Gillette, Wyoming began production in August, 1977. Our second surface mine, Caballo, located just south of Gillette, began operating last October. We have a third block of federally leased coal just east of Gillette. By 1985 we anticipate Carter's western surface mines will be producing at an annual rate of 30 million tons, subject, of course, to successful market development efforts and regulatory considerations. Rawhide will ultimately have a permitted capacity of 24 MM tons per year. The coal at Rawhide is in two seams; one 80 feet in thickness and the other 20 feet (including a 6 to 10 foot parting). A large shovel is used to remove the overburden, and a similar shovel and dragline are used to mine the coal. Caballo has a 75 foot seam; otherwise it is similar in design and operation to the Rawhide Mine.

Jan 1, 1979

By K R. Vining, T E. Norgate

A study was carried out to compare the environmental impacts of the two major iron ore agglomeration processes, sintering and pelletising, using life cycle assessment (LCA) methodology. The following agglomeration processing routes, with the fuel options shown, were investigated:sintering with combined natural gas/coke breeze or charcoal as fuel, grate-kiln pelletising with combined natural gas/coke breeze as fuel, and straight-grate pelletising with combined natural gas/coke breeze as fuel. Inventory data for each process derived from the literature, and in some instances supplemented by additional simulations and calculations, were used in the study and the environmental impact categories considered were gross energy requirement (GER), global warming potential (GWP) and acidification potential (AP). The results of the study showed that the GER, GWP and AP for a sinter plant are higher than those for a pellet plant for the same amount of metallic iron in the agglomerated products. These results are partly due to higher consumption of solid fuel and flux in the sintering process. However, it should be pointed out that the study only compared substantially fluxed sinters with acid pellets that may require additional flux (and hence potentially more greenhouse gases emissions) to be a balanced blast furnace feedstock. Extending the LCA to the blast furnace process stage was beyond the scope of the current study. Within the sinter plant, the sintering stage itself is the largest contributor to the GER, GWP and AP. In the case of pellet plant, the pellet induration stage is the largest contributor to the various environmental impacts. The GER and GWP of a straight-grate pellet plant are marginally higher than those of a grate-kiln pellet plant due to the higher electrical power required by the straight grate system. The substitution of coke breeze with charcoal in the sintering process results in an increase in GER but a decrease in GWP. However, a substantial proportion of the GER is derived from renewable sources (wood), resulting in a decrease in the non-renewable components of this environmental impact. Given the source of the inventory data and the assumptions and approximations made in carrying out the LCAs, it is emphasised that the results presented in this paper should be considered as indicative rather than as definitive results for the two iron ore agglomeration processing routes considered.

Jan 1, 2006

By U B. Pal

Downsizing and decommissioning of nuclear facility operations is increasing the stockpile of various different grades of Radioactive Scrap Iron (RSI). Disposal of this material not only represents significant resource and value lost, but also necessitates long term monitoring for environmental compliance. The latter results in additional recurring expense. It is desirable to be able to decontaminate the RSI to a very low level that can be recycled or used for fabrication of containers for RSI disposal instead of using virgin metal to fabricate the container. Electro-Slag Remelting and Refining (ESR) is often used for decontaminating radioactive contaminated sources of scrap iron such as stainless steel. Non-radioactive oxides of cerium are used to simulate the radioactive oxide contaminants of Uranium and Plutonium. The success of the ESR process is strongly dependent on the capacity of the slag to rapidly incorporate the radioactive contaminant (simulant). In this study we have measured the slag-metal partition coefficient for cerium and investigated the reaction mechanism for the dissolution CeO, in the slag.

Jan 1, 2002

By F. B. Plummer

PETROLEUM ENGINEERING deals with the production, transportation, and refining of crude oil. Refining is chiefly the work of the chemical engineer; production, that of the petroleum engineer. Production engineering only is discussed in this paper. Petroleum production engineering is closest related to and, in fact, is a branch of mining engineering. Formerly, many petroleum engineers were trained as mining engineers or mining geologists. The profession is related also to mechanical and civil engineering to about the same extent that mining engineering is. Petroleum production draws upon the mechanical branch for drilling and pumping machinery and upon civil engineering for the construction of transportation lines, water supplies, and water-disposal plants. Fundamentally, petroleum production engineering deals with the removal of the oil from the reservoir rocks, just as mining is concerned with the removal of ore. The process of oil production demands a specialized knowledge just as distinct from mechanical and civil engineering as mining is distinct from operating a Diesel engine. Even though the chief tools of the petroleum engineer are the drill and the pump, these may be of little avail, and certainly not efficient, if their selection and use is not based on a knowledge of the physical chemistry of oil, the geology of the formations, the structure of the oil sand, the hydrodynamics of the reservoir, and the interrelation of all these many factors.

Jan 1, 1936

By H Kim, M J. Sun

In order to reduce carbon emissions from the steelmaking process and achieve carbon neutrality, global steel companies are establishing their own medium to long-term strategies and implementation plans using competitive technological advantages held by each steel company. At this point, Hyundai Steel has formulated a product-oriented carbon-neutral strategy based on innovative processing that makes use of Hyundai Steel’s own strength. Based on our experience in electric arc furnace product manufacturing and blast furnace operation in an integrated steel mill, Hyundai Steel is driving the Hy3 (Hy-cube) project, which involves a unique hybrid production system utilising hydrogen and hydrogen-based renewable energy sources. This initiative aims to achieve carbon-neutral production and eventually specialise in producing premium carbon-neutral automotive parts. The project has originality in that it involves not only designing processes using electric furnaces to produce premium steel products such as car body panels and electrical steel sheets, but also aims to reduce carbon emissions from the process, developing carbon-neutral products based on market demand. To assess the feasibility of the Hy3 project, Hyundai Steel conducted two pilot productions. The first pilot was producing a prototype of lower-arm part using electric arc furnace with three different kinds of raw materials: molten iron, HBI (hot briquetted iron), and scrap. Successful performance evaluation of auto parts with 1 GPa strength was achieved. The second pilot has been focused on tire cord steel, with the first-phase tests yielding a 33 per cent reduction in carbon footprint (CFP). Using the advantages of operating experience in electric arc furnace, Hyundai Steel is preparing for test operations producing various automotive parts using an electric arc furnace (EAF) to advance the Hy3 concept. From a medium to long-term technological development perspective, Hyundai Steel’s blueprint includes producing high-end carbon-neutral steel products using hydrogen-reduced iron as raw material.

Jun 19, 2024

By Chang Wei, Fan Zhang, Zhigan Deng, Minting Li, Cunxiong Li, Gang Fan, Xingbin Li

Marmatite is an important resource of zinc, which exist in forms of high iron and high indium. In order to recycle the valuable metal from these ores, the testwork of simultaneous leaching on neutral residue mixed with zinc concentrate of high iron and high indium has been conducted. The primary objectives are to leach the zinc and indium remaining in the neutral leach residue as ferrite using acid, and to reduce the ferric iron in solution to the ferrous by zinc concentrate, thereby extracting the zinc and indium in the zinc concentrate. The results indicated that in the following conditions, mass ratio of neutral residue to zinc concentrate of 1:0.25, particle size of 74-58 μm, initial sulfuric acid concentration of 150 g/L, liquid to solid ratio of 8 L/kg, temperature of 90°C, reaction time of 4h, the leaching efficiency of zinc and indium were over 95%, nearly 90% Fe was Ferrous in the leaching solution. This process effectively extracted zinc and indium and converted Fe3+ into Fe2+ in solution, and simplified the traditional process of reduction after leaching.

Jan 1, 2016

By Francisco Sena Leite, Pedro Brito, Auã Kiahla, Raquel Carvalhinha, Tomi Kouvonen, Vinicius Miranda

Shockwaves that generate vibration in the surrounding environment of a blast, are one of the most important factors to control drill & blasting works near delicate buildings as well as in sensitive structures (wall control). On top of the damage to the buildings themselves, sensitive equipment such as computers, measurement apparatus and medical devices can be also compromised. The most commonly measured values from vibration are PPV (peak particle velocity), acceleration and displacement. Some devices and techniques have been developed in the last decades to measure the impacts of these vibratory phenomena. This information can be used to predict levels of vibration for future blasts and improve their quality of design using the attenuation law. From traditional studies to modern seismographs, a range of solutions are used for this propose. The main problem of applying this kind of technology is the high cost associated with each measurement device. In order to measure the ground vibration using new technologies while lowering the cost, a device has been developed using a microcontroller and electronic sensors commonly found on the market. This new equipment was tested side by side with traditional seismographs and the results were sent to a server for analysis. After several blasts, the necessary data was generated for the validation of the prototype. Through numerical mathematical processing (Taylor’s approach and numerical derivation) the original data supplied by the accelerometer’s sensors was transformed into velocity and, after the data mining, a statistics residue analysis was applied in order to evaluate if the data from the prototype and from the traditional seismographs were similar. The data from each system was used to estimate the attenuation law and the results are shown in this paper.

By F. E. Bash

Previous to the war, this country depended on Europe for its supply of a number of alloys of great importance in the manufacture of electrical apparatus and equipment. When this source was cut off shortly after the beginning of hostilities and the small stocks in the United States were exhausted, either inferior substitutes had to be used or the manufacture of the apparatus suspended. Since electrical equipment was of primary importance in the prosecution of the war, the substitutes had to be used until the composition and processes of manufacture of the alloys could be determined. Included among these alloys was one generally known as manganin, which is composed chiefly of copper and manganese and which, beside having a low-temperature coefficient of resistance, has a low thermal electromotive force against copper. These qualities make it valuable for the manufacture of electrical instruments and machines in which it is used in the shape of wire, rod, and strip. As a result of these circumstances, an investigation was started to determine how manganin could be made on a commercial basis so that a product of uniform quality and the necessary electrical characteristics could be produced. The object was to procure an alloy with temperature coefficient of resistance not greater than 1 X 1X per " C. and a thermal e.m.f. against copper no greater than that of the imported material. It is characteristic of manganin that the temperature-resistance curve is not a straight line but has a peak, which varies in position with different samples; it is most desirable, however, to have it at a temperature of 25' C. if possible. The coefficients of manganin from all records available ranged from a large negative to a large positive value. The composition as reported by different authorities is given in Table I. Prof. Matthew A. Hunter, of Rensselaer Polytechnic Institute, made up a number of small melts of manganin in a graphite crucible and the one that he reported as having the best cocfficient gave the following analysis: Copper, 83.6 per cent.; nickel 2.5 per cent.; manganese, 13.6 per cent.; iron, 0.3 per cent. An analysis of a sample of German manganin gave the following: Copper, 82.6 per cent.; nickel, 3.8 pcr cent.; manganese, 12.8 per cent.; iron 0.7 per cent.

Jan 1, 1921

By J. Matos e Silva

The paper refers two examples of structures located in seismic areas (Cases 1 and 2). The first one (Case 1) is the Torroal Bridge, located about 100 Km South of Lisbon, in the road Troia-Grandola. The horizontal loads due to the seismic actions were mainly carried by an anchor curtain connected, to the abutments, by reinforced concrete struts-ties. For the some purpose diaphragm walls were also placed under the pile caps of the column foundations. The second one (Case 2) refers to a building located about 50 Km South of Lisbon, at Sesimbra, near a cliff. To reduce the horizontal displacements of the structure due to seismic actions, in order to prevent the endangering of the cliff stability, an anchor curtain was adopted and connected, to the structure, by prestressed anchors.

Jan 1, 1996

By H. H. Kellogg

Equations representing the standard free energy of formation as a function of temperature, for thirty metallic chlorides, are presented and plotted on a free-energy vs. temperature diagram. The use of these data for calculations on reduction of metallic chlorides, refining of metals with chlorine, and chlorination of metallic oxides and sulphides is illustrated. CHLORINE metallurgy' has attracted metallur- gists for more than a century because the unusual properties of the metallic chlorides—low melting point, high volatility, and ease of formation from the oxides—make possible many useful extractive processes. Interest in chlorine processes is undergoing a renaissance due to present availability of chlorine at relatively low prices, and to recent advances in technology. During the present century there have accumulated a considerable number of reliable values of the thermodynamic constants for the metals and their chlorides. These data permit the calculation of free-energy equations for many metallurgically important reactions. Consideration of free-energy values makes possible certain predictions of the direction and extent of a given reaction, as well as the effect of temperature, pressure, and composition upon the result. Reaction rate, although not predictable from free-energy data, is usually sufficiently great at elevated temperatures that diffusion of the reactants and products to and from the zone of reaction determines the actual rate. Thus, if the free-energy indication is favorable, the chances are good that a high temperature metallurgical reaction will proceed at a reasonable rate, if adequate provision for rapid diffusion has been made. This paper presents standard free-energy equations for a number of metallic chlorides, based on data which are scattered throughout the literature. The equations are presented in a form that simplifies their use, and typical examples are given of the application of free-energy data to metallurgical processes. Free Energy of Reaction The free-energy change (AG) of a reaction is the true measure of the "driving force" of the reaction under a given set of conditions, and this is related to the standard free-energy change (AGO) of the reaction as follows: For the reaction: bB + cC = dD + eE ?G = ?G°+RTln ADd. AEA / ABb. ACc where A, = activity of constituent (i) T = absolute temperature, OK R = gas constant The criterion of a spontaneous reaction from left to right, at constant temperature and pressure, is a negative value for the free-energy change (?G). The standard free energy of the reaction is equal to the free energy of the reaction when all the reactants and products are at unit activity, since under these conditions the second term on the right-hand side of eq 1 is equal to zero. The concept of activity is treated fully in many textbooks on chemical thermodynamics1 and in a recent article by Chipman.2 Briefly, the activity (A,) of a constituent (i) is a measure of the reactivity of this constituent relative to its reactivity in some arbitrary standard state. For liquids and solids the standard state most often used is the pure liquid or solid constituent. Thus the activity of a pure liquid or solid in a metallurgical reaction is equal to unity. Gases under moderate pressure and at elevated temperatures behave very nearly as 'idea1 gases,' and the standard state is chosen as the gas at 1 atm pressure. The activity of an ideal gas is therefore equal to its partial pressure, and this relation is sufficiently exact for real gases in most metallurgical reactions. For a liquid or solid solution there is in general no simple way to express the activity of a constituent as a function of its concentration, and activity must be determined by experiment. A few solutions follow a so-called 'ideal' behavior, and if the pure constituent is chosen as the standard state, the activity of a constituent in an ideal solution becomes equal to its mol fraction. When a reaction reaches a state of thermodynamic equilibrium at constant temperature and pressure, AG becomes equal to zero and eq 1 reduces to: [ADd . AEe ?G°=RTln Abb ¦ Ac c equilibrium [2] The brackets surrounding the activity term are used to emphasize that each of the activities is an activity under equilibrium conditions—not just any arbitrarily assigned value. The bracketed term is the equilibrium constant (K) of the reaction. Eq 2 makes possible the calculation of equilibrium activities for a given reaction, if AGO is known at the desired temperature. The standard free-energy equations presented in this paper were calculated from the fundamental thermodynamic values of enthalpy of formation at 298°K (AH°,), standard entropy at 298°K (So298), heat capacity as a function of temperature (Cp), and enthalpies of transition, fusion, vaporization, and sublimation for the various constituents. Where possible the data reported in the recent "Selected Values of Chemical Thermodynamic Properties," published by the Bureau of Standards," were used. A large number of data came from the publications

Jan 1, 1951

By Paul H. Johnson

Heap leaching is a simple means of recovering copper from oxide and oxide-sulfide ores. Although this method requires relatively low capital investment, it suffers from low copper recoveries and relatively high acid consumption. The objectives of this study were (1) to determine what factors influence these shortcomings, and (2) to establish a basis of correlation. between laboratory and field testing. The principal methods of leaching copper ores at the present time are heap, dump, in-place, and vat. A number of references are presented in the bibliography on the theoretical and practical aspects of these methods. In the heap-leaching method, crushed or uncrushed oxidized copper ore is placed on a prepared drainage pad. Acid leach solutions are dis¬tributed over the top of the heap, caused to percolate downward through the ore bed by gravity, and are drained from its base. The leach duration is generally a matter of a few months. Dump leaching is used to recover copper from very low-grade oxide-sulfide pit-waste materials. Here again, leach solutions are, percolated downward through a heap. However, in this method, little or no acid is added to the leach liquors, prepared drainage pads are not used and the leaching cycle is generally measured in terms of several years. Leaching agents are usually autogenously generated by the breakdown of sulfide minerals within the dump.

Jan 1, 1970

By Michael J. Friedel

The scale-dependent hydraulic properties in a fractured porphyry copper oxide deposit are investigated for relevance to in situ leach mine (ISLM) design. In most well field designs, mine operators assume that hydraulic properties represent a continuous spatial function, or continuum. The problem, however, is that the representative elemental volume, the volume over which hydraulic properties are described as a continuum, is a domain (if it exists) that occurs between end members representing varying degrees of heterogeneity. At the Cyprus Cas a Grande mine, transmissivity fluctuations are spatially correlated suggesting that at the scale of ISLM, the hydraulic process is heterogeneous and a typical continuum representation is inappropriate for design. Alternatively, a conditional stochastic approach using the simulated annealing (SA) technique is deemed useful for the imaging of heterogeneous hydraulic properties. Specifically, SA preserves transmissivity extremes and spatial complexity, both necessary for accurate conditioning of a flow simulator. Also, the stochastic continuum approach provides an avenue whereby uncertainty (or risk) may be addressed. Currently, the SA weaknesses are that it is computationally time consuming, and uncertainty may increase when simulating under conditions of statistical isotropy. Recognizing that ISLM exerts a dynamic influence on hydraulic properties with time, the mine design should be reevaluated at intervals throughout the evolution of the leaching process.

Jan 1, 1993

By Gary P. Sames

Shale roof deterioration in coal mines. caused by ventilation air humidity fluctuations, is a common ground control problem. Shale roof deterioration often results in increased accidents, decreased production, inadequate ventilation, and increasing operating costs in maintaining haulage roads and airways. The results of Bureau of Mines research indicate that air tempering entries are an effective method of controlling deterioration prone shales. Some of the conclusions and recommendations drawn from Bureau research include (1) moisture sensitive shales will react adversely to moisture gains and losses, (2) the majority effect of specific humidity fluctuations can be concentrated in and absorbed by tempering entries, (3) tempering entry panels should be located as near to the main intake as possible, (4) tempering panels should be designed for a conservative recovery and provide a minimum of 20-to 30-min air residence time, (5) ventilation and escapeway requirements must be considered early in panel design, and (6) an efficient support and sealant plan can increase the life expectancy of a tempering panel.

Jan 1, 1985

By O. Rielo, P. Katsabanis

Traditionally fine aluminum is not used in dry commercial explosives due to the hazard associated with aluminum dust explosions during mixing. An industrial process has been developed which enables the safe use of paint grade Aluminum with ANFO. The addition of fine aluminum particles resulted in increased velocity of detonation of ANFO compositions. Velocities of detonation, in 52mm (2 1/16 in.) diameter confined charges were 20% higher than velocities of detonation of straight ANFO. The detonation performance of fine grained ANFO was not benefited by Al at the diameter tested. Furthermore use of larger Al flakes resulted in decreased velocities of detonation. The results are compatible with the experience of Al addition to high explosives. Tests were also conducted using bio-diesel, finding no substantial difference in the performance of AN fuel explosive compositions which used bio-diesel.

Jan 1, 2009

By R. J. Durrheim, Y. Yabe, M. S. D. Manzi, DSeis team, N. Z. Nkosi, S. B. Mngadi, Jr. H. Ogasawara

On 5 August 2014, the Orkney M5.5 earthquake, the largest in South African gold mining districts, occurred with an unusual strike-slip mechanism at great depth of 4.78 km below the surface. In a rare case, the ML 5.5 earthquake occurred within the area covered by the legacy 2D and 3D reflection seismic data acquired in the 1990s and 2000s for gold exploration and mine development. In addition, the earthquake ML 5.5 rupture plane was recorded and accurately delineated by the underground in-mine seismic network near the source region. The integration of the legacy 2D reflection seismic data and mine seismicity data allowed us to identify a near-vertical structure, striking northnorthwest-south southeast (NNW-SSE). The ICDP-DSeis team drilled three holes (Hole A, Hole B, and Hole C), and two holes (Hole B and Hole C), intersected the upper edges of the ML 5.5 rupture. These holes recovered metasediments, metabasalts, intrusive rocks including dolerite sills and lamprophyre dykes adjacent to the fault zone, and the fault gouge. Late Prof. Tullis Onstott and geomicrobiologists installed a packer in Hole A and successfully recovered saline water and detected gas (~10 MPa). Slip weakening and rupture propagation are significantly influenced by the existence of fault gouges and the production of wear material between two sliding rock surfaces. Using the fault gouge material recovered from Hole C, we conducted friction experiments under dry and room temperature conditions at high slip velocity of ~100 mm/s and normal stress of 2 MPa. The resulting steady-state frictional strength was ~0.66 over a slip weakening distance of ~9.1 m. The steady-state frictional strength was high, which may be caused by large gouge thickness, and the rate of wear generation. As a result, it is proposed that the Moab Khotsong ML 5.5 seismogenic zone is complex and could be controlled by three main processes: a) the complex structural architecture of the seismogenic zone (e.g., intersection of fault, lamprophyre dykes, and dolerite sills); b) the mechanical process induced by tectonic and/or mining related stresses; and c) the mechanical and chemical processes caused by the water and rock interaction.

Jan 12, 2025

By D R. Venkatesulu, N K. Nanda

Due to increased production of steel in India, the thrust is now on iron ore producers not only to enhance productivity from existing mines, but to look also into alternative resources, like lean grade iron ores such as banded haematite quartz (BHQ)/banded haematite jasper (BHJ), which are available in abundance but not yet utilised for want of suitable process technology. In this context, BHJ ore from the Bellary-Hospet sector was collected and subjected to detailed physical, chemical and mineralogical characterisation and beneficiation studies. The as-received sample was found to occur physically as alternating layers of haematite and jasper. The chemical analysis of the sample was 41.20 per cent Fe, 39.10 per cent SiO2 and 0.86 per cent Al2O3. Based on the mineralogical observation, haematite was found to be the lone ore mineral and jasper was the major gangue mineral. The microscopic observations revealed that the ore minerals liberate at a top size of 0.150 mm. Guided by the characterisation results, indicative tests were conducted using gravity and magnetic separation equipment, namely, Floatex«, gravity slime table and wet high intensity magnetic separator (WHIMS). The results indicate that it is possible to upgrade the sample by both gravity and magnetic separation techniques. However, the WHIMS results indicate that jasper grains report to the concentrate at higher gauss intensities. Therefore, based on the encouraging gravity separation results and the availability of new design spirals for treating fine particles, the applicability of gravity spirals for beneficiating BHJ in the liberation size range of -0.150 mm was studied. The sample was ground to a top size of 0.150 mm and was subjected to preconcentration using wash waterless spirals. Tests were conducted at different feed rates, pulp densities and splitter positions. The results indicate that it is possible to upgrade the sample from a feed grade of 41.20 per cent Fe to a preconcentrate ranging from 46 per cent to 62 per cent Fe with a yield ranging from 19 per cent to 55 per cent. The obtained preconcentrate was then subjected to a cleaning stage by using a combination of wash water and wash waterless spirals. The test results indicate that it is possible to obtain a final concentrate assaying 65.75 per cent Fe and 4.75 per cent SiO2 with a yield of 25.9 per cent and an iron recovery of 41.31 per cent. It was concluded that further test work is necessary to increase the recovery and improve the product specification.

Jan 1, 2009

By C. D. Mishra

The recycling potential for any gainful utilisation of the waste products is dictated by their quality, especially the chemical characterisation. The methods commonly used for the analysis of fly ash e.g. wet chemical, AAS, ICP-AES etc are time consuming. The paper describes a rapid XRF-based method for routine analysis of fly ash which involves preparation of local standards, optimisation of sample preparation technique and use of a simple PC-based software to account for interelement effects. The matrix corrected values are found to agree well with the wet chemical data.

Jan 1, 1992