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By R Carstens, L Munsamy, L Prinsloo, C Huang, C Zhang, R Liang, I Canbulat

With recent advances in machine learning, data-based automated decision-making has been proven successful with promising outcomes in many industries. Its application in the mining sector can be ground-breaking; particularly the data-driven analytics that can support decision-making in the mine and consequently enhance mine safety, efficiency and sustainability. However, the current data science applications in the mining industry are mostly noncomprehensive, especially inadequate in evaluations, thus often requiring further study to be potentially beneficial to operations. Furthermore, it was found that existing literature paid limited attention to understanding the role of such techniques. Hence, in this paper we aim to build an end-to-end machine learning powered data-driven framework for intelligent geo-hazard analytics to support decision-making for underground mining data management, where multiple types of data are managed in an integrated database to support the unified machine-learning model. Here we present the framework as data-driven workflow processes, including data gathering, data preparation, data processing and data presentation. In addition, we present an application scenario of the proposed framework, where falls of ground (FoG) is managed with the historical FoG investigation reports, related panel hazard ratings, compliance data and rock mass characteristics. A demonstration can be dynamic forecasting of high-risk areas for FoG based on both spatial and temporal factors, including a 3D data visualisation. Such a scenario shows the potential of the proposed framework to establish connections among various data fields across a diverse category of data. Furthermore, the results offer important insights for ground instability management and can potentially optimise the underground operation flow.

Nov 29, 2022

By D. J. McAdam, R. W. Mebs

The technical cohesive strength of a metal means, not the interatomic forces, but the technically estimated resistance to fracture. An example of such resistance to fracture is the so-called "true" breaking stress of a tension-test specimen, the breaking load divided by the sectional area at fracture. According to the prevalent view,8 the technical cohesive strength of a metal. in any particular state as regards prior mecharlical treatment and heat-treatment, is determined by a limiting value of the algebraically greatest principal stress. In two previous papers by one of the authors, evidence was presented to indicate that the technical cohesive strength of a metal cannot be represented by a single stress value, but that it comprises an infinite number of values corresponding to the infinite number of possible combinations of the principal stresses. The technical cohesive strength thus comprises an infinite number of technical cohesion Limits, each representing a specific stress combination at fracture. In the same papers, evidence was presented that plastic extension causes a continuous increase in the technical cohesive strength. Such a variation is not in accordance with the prevalent view that plastic extension first increases, then decreases, the technical cohesive strength.' In this paper, as in the previous papers,14.15 the algebraically greatest principal stress will be designated S1, the least principal stress will be designated 33, and the intermediate principal stress will be designated S². The technical cohesion limit under polarsymmetric tension (S1 = S2 = S3) will be termed the "disruptive stress," and the cohesion limit under unidirectional tension (S2 and S3 = o) will be termed the "severing stress."l4, .l5 The yield strength of a metal, according to the generally accepted theory, may be represented by a constant value of the shearing-strain energy, and hence by a constant value of the sum of the squares of the three principal stress differences. In the second of the previous papers,15 however, evidence was presented that the limiting yield stress decreases with increase in the volume stress, the algebraic average Of the three principal stresses.* This in fluence of the volume stress becomes prominent only in the field of triaxial tension. In the two previous papers,".'5 diagrams were presented to show the variation of the technical cohesion limit, yield stress, and ultimate stress with the combination of principal stresses and with plastic extension. Those diagrams and the resultant • Any stress system ma? be resolved into a polarsymmetric stress causing pure volume strain and a combination of pure shearing stresses. which cause no change of volum

Jan 1, 1945

By S. H. Ward

Since the advent of the first airborne electromagnetic system, it has been evident that such systems were inherently limited to shallow depths of exploration of the orderof 100 to 200 feet. Hence in 1948 the author and his associates commenced a study of the feasibility of applying natural audio frequency magnetic fields to investigation of the electrical properties of the subsurface in order to provide a system capable of overcoming this limitation. This research culminated, in the summer of 1958, in the development of a new airborne prospecting device — AFMAG. This device has detected surface massive sulphide bodies while flown at heights as great as 3000 feet. Hence, by inference, it is deduced that it could find similar sulphide bodies if they were buried 2500 feet below surface and the aircraft flown at 500 feet. Thus a considerable improvement over conventional airborne electro-magnetic systems is obtainable with AFMAG. Airborne exploration in mountainous terrain involving deep valley fill now becomes possible. Examples are presented of the results of actual airborne AFMAG test surveys over known deposits of massive sulphide mineralization. Interpretation of the data is discussed with particular reference to the knowledge of size, dip, depth, depth extent, and conductivity of causative bodies as deduced from the flight records. The possibility of mapping major geologic structures, for both mining and oil exploration purposes, is discussed with the aid of examples of airborne AFMAG data. INTRODUCTION Electrical prospecting with natural audio frequency electromagnetic waves as a source has, within the last three years, become a practical reality. Both airborne and ground survey instruments under the trademark "AFMAG" (for audio frequency magnetics) have been used successfully in the search for conductive mineral deposits. It is the object of this paper to discuss the principles of airborne AFMAG and to illustrate its application by means of examples obtained over known geological situations. WHY AFMAG? In view of the large number of good airborne electromagnetic systems available for purchase or contract surveying, one may well ask, "Why another new system?". Primarily the answer lies in the fact that AFMAG does not suffer from the very limited depth of exploration available with, and inherent in, any conventional airborne electromagnetic system. AFMAG is not conventional insofar as an artificial transmitter is not required. Only a receiving and detecting device is employed. The electromagnetic fields measured are those from millions of electrical discharges in the atmosphere (e.g;..- lightning strokes). Their random distribution in time and space make these fields difficult to employ and it is only with recent advances in the electronics of geophysical instrumentation that this has become possible. A second reason for AFMAG and one of its

Jan 1, 1961

By Raymond E. Krauss

The McLaughlin Mine is based on a world class epithermal gold deposit located in the coastal thrust fault of northern California, about 1 12 air km (70 air miles) north of San Francisco. Owned and operated by Homestake Mining Co., the McLaughlin deposit contains about 18 Mt (20 million st) of gold ore at an average grade of 5.2 g/t (0.152 oz per st), or about 93 t (3 million oz). The area was identified as a gold target by Homestake in early 1978. Drilling confirmed it to be a commercial deposit by 1980. The mine was then planned, engineered, built and brought into production by March of 1985. The deposit was historically a part of the Knoxville District. It was mined for cinnabar, which was used to produce mercury for use in recovering gold and silver in the Mother Lode and Comstock districts. At that time, the mine was called the Manhatten and later the One Shot Mine. It was worked for more than 100 years, producing about 76,000 flasks of mercury without any awareness of the presence of economic concentrations of gold. By 1978, the site was largely disturbed and entirely unreclaimed.

Jan 1, 1990

By P. A. Flinn

ALTHOUGH many physical properties of superlat-tices have been studied intensively, relatively little attention has been paid to their mechanical properties until recently. Even for the well-known transformation in 0 brass, the effect of the transformation on plastic behavior has only lately been extensively investigated.''' A partial analysis of dislocation structure in superlattices has been given by cottrel13 and his theory agrees well with the experimental results on CU3AU.4,5 His analysis, however, is implicitly limited to low-temperature effects, since it does not include the behavior of dislocations at temperatures high enough for diffusion, and hence climb, to occur. The work of Herman and Brown2 on the creep of 0 brass indicates that important effects occur under such conditions, and consequently, the theory should be extended to include them. Such high-temperature effects cannot be observed in Cu3Au, since it disorders below the temperature at which diffusion occurs at a reasonable rate. There are materials of the same structure, however, such as Ni3A1, which retain their order up to, or close to, the melting point. GEOMETRY OF THE COMMON SUPERLATTICES The two best-known ordered structures are the 0 brass type, B2, shown in Fig. 1, and the Cu3Au type, Ll2, shown in Fig. 2. In the B2 structure the (000) and (1/2, 1/2, 1/2) sites are different in that they are occupied by different types of atoms. The symmetry of the structure is then lowered from a body-centered cubic, A2, in which the sites are equivalent, with atoms located randomly in the sites, to simple cubic. This lowering of symmetry has the consequence that two types of regions may occur within a crystal: regions where A atoms are in the (0, 0, 0) sites, and regions where they are in (1/2, 1/2, 1/2) sites. The boundary between two such regions will contain bonds between like atoms, and be a surface of higher energy. These regions are known as antiphase domains and the boundary as antiphase boundary. In the B2 structure, boundary formed during the ordering process should disappear as a result of domain growth, since any domain growing to the boundary of two others will join one and engulf the other.' In any well annealed crystal, only a single domain should exist, with antiphase boundary present only in connection with dislocations, as discussed below. The L1, structure is related to the A1 (face-centered cubic) in much the same way as the B2 is to the A2. The face-center sites are occupied by A atoms, and the corner sites by B atoms. The symmetry is again lowered to simple cubic, and antiphase domains can exist. In this case, however, there are four initially equivalent sites in the unit cell: (0,0,0), (0, 1/2, 1/2), (1/2,0, 1/2) and (1/2, 1/2, 0). In the ordered structure any one may be occupied by a B atom and the other three by A atoms. Thus four types of antiphase domains can occur in this structure. This is sufficient to permit a metastable "foam structure" to exist within a crystal.''7 Antiphase boundaries along three different planes are shown in Figs. 3, 4, and 5.* *The presence of a layer of disordered material between antiphase domains, as suggested by Jones and Sykes8 does not seem likely. Such a layer would be a region of unnecessarily high energy which could readily be reduced by the formation of the type of boundary discussed here.__________________________________________________________ The notation (111) [110] means a boundary lying along a (111) plane between antiphase regions related by a 1/2 [I10] translation. It may be seen in Figs. 3 and 4 that an antiphase boundary usually results in incorrect nearest neighbors (shown connected by braces). However, as pointed out by Wilson, a boundary of the (001) [I101 type can exist

Jan 1, 1961

Mining One (M1) is often challenged with the task of evaluating deposits considering open cut and/or underground (UG) mining methods. In many near surface deposits a combination of both methods results in the optimum economic means of exploitation. As common as it is to have open pit mines eventually develop into underground mines, theory associated with determining the optimum underground/open pit interface location continues to be subject to refinement. With recent developments in underground software packages, the generation of rudimentary underground mining stopes from basic economic inputs is not only fast, it provides a practical underground mining solution. The determination of the open pit/underground interface is not new to Gemcom's Whittle 4X (Whittle). However, its solution has only ever claimed to be indicative, mainly due the rudimentary nature of how Whittle represents any potential underground mining. The efficient generation of the aforementioned underground mining solution has provided mining engineers with a unique opportunity. Underground mining can now be represented within the Whittle environment to allow the open pit/underground mining scenario to be modelled with increased accuracy. Providing Whittle with the ability to now consider mineable underground stopes combined with the consideration of time value of money (discounting), has delivered a solution with higher credibility than ever before.This paper will elaborate on the potential value gains associated with improved accuracies in the modelling of any potential underground mining in the Whittle environment. Furthermore, it will explain the importance of incorporating time value of money in the optimisation process to provide a consistent solution through to pit selection and final analysis.

Dec 6, 2010

The 109th Annual General Meeting of The South African Institute of Mining and Metallurgy was held at The Country Club, Johannesburg, Napier Road, Auckland Park on Wednesday, 16 August 2006. Special General Meeting A Special General Meeting to consider the changes to the Constitution was held immediately prior to the AGM. 1. Purpose In order for the SAIMM to remain relevant and ensure maximum value to all members, Council propose three changes to the Constitution. 2. Background Three changes to the Constitution were proposed by the Council on 21 July 2006. These changes now have to be approved by means of a ballot at a Special General Meeting. These three proposed changes are discussed briefly below:

Jan 1, 2006

By R Beaulieu, D Burlingame, C Hanks

The Ekati Diamond MineÖ is CanadaÆs first diamond mine and is located 300 kilometres northeast of Yellowknife in the Northwest Territories. The development of the mine supports sustainable development through the integration of environmental, economic and social considerations with the broad aim of minimising environmental impacts while maximising opportunities and benefits to northern residents and northern businesses. The environmental assessment and regulatory processes for the Ekati Diamond MineÖ were the most extensive seen in the NWT to that date; in Canada only uranium mines receive more attention. In addition to the regulatory requirements, an Environmental Agreement was negotiated with the Governments of Canada and the Northwest Territories to address environmental concerns not covered by existing legislation and regulation. Under the agreement an Independent Environmental Monitoring Agency was set up to oversee the regulatory process and implementation of the Environmental Agreement. Environmental stewardship is implemented through an Operational Environmental Management Plan, part of which includes effects monitoring programs for wildlife and aquatics where available traditional ecological and scientific knowledge are integrated to broaden our understanding of the tundra environment. A Socio-economic Agreement was concluded with the Government of the Northwest Territories to maximise employment and business benefits to the north. Voluntary and confidential Impact Benefits Agreements (IBAs) were also negotiated with four Aboriginal groups who use the area where the mine is located. The intention of the IBAs is to foster development initiatives and a partnership thereby helping to insure that benefits from the project flowed to the Aboriginal groups despite a lack of settled land claims in the region. All these were completed before commercial production in October 1998. Employment targets of 62 per cent residents of the Northwest Territories and 31 per cent Northern Aboriginal have consistently been met thereby ensuring benefits flow to residents of the Northwest Territories. In 2000, $316 million was spent to support operations at the Ekati Diamond MineÖ. Of this, 82.2 per cent of total spending and 26.6 per cent total northern spending was northern and northern Aboriginal businesses, respectively. The environmental and socio-economic monitoring results are reported annually to the responsible government agencies and potentially affected Aboriginal groups. To date, there have not been any significant adverse environmental effects documented and socio-economic targets have been met.

Jan 1, 2002

By H. Y. Cheng

A pulse column solvent extraction system was evaluated as an alternative to mixer-settlers for the separation and purification of rare earths. The column tested had an inside diameter of 44.5 mm and had 36 sieve plates with a free area of 25%. Pulsing was provided pneumatically using a solenoid valve controlled by a timer so that both pulse amplitude and frequency could be varied. Feed to the column was a mixed rare earth chloride solution containing 10 g RE L-1. The extractant was 5% Ionquest® 801 in Shellsol 2037 diluent. Hydraulic performance of the pulse column was excellent with no propensity towards stable emulsions or crud formation under normal operating conditions. The column was operated in organic-continuous mode with flow rates chosen so that yttrium and the heavy rare earths were extracted with high efficiency while the light rare earths were rejected. Yttrium extraction varied from 83 to 99.2%. Concentration profiles were measured in both the aqueous and organic phases, and, from this data, the height of a transfer unit (HTU), the mass transfer coefficient (Kxa) and the continuous-phase axial dispersion coefficient (Ey) were computed. The HTU ranged from 17-92 an which is within the range of values reported for other (non rare earth) pulse column systems.

Jan 1, 1992

By Maurice Lauzon

"Aerial surveys of the open pits have been conducted regularly at Lake Asbestos of Quebec, Ltd. -a subsidiary of American Smelting and Re-fining Company -since 1958. Ground controls are supplied by Lake Asbestos, and a topographic map of the pits at a scale of 1 in. to 50 ft., with 2-foot contour intervals, is obtained by aerial photography. The information from the topographic map is then transferred by the Lake Asbestos engineering staff to sections from which the volumes removed are calculated. Considering the size and complexity of the operation, this system has proved to be the cheapest, fastest and most accurate way of determining the quantities of rock and overburden removed. More than 11,000,000 tons of ore and waste are mined each year in three different pits. Further-more, the nature, shape and extent of the orebodies make it necessary to mine on many (up to eight) benches of a pit during a single year. In addition, there are sections of the pits where it is impossible or un-safe to survey the crest of some benches by standard ground methods. For these reasons, the tonnages obtained by truck count are checked and adjusted by aerial survey. These surveys are now taking place every six months. With this system, it is possible for a two-man surveying crew to look after all field work in the mine area."

Jan 1, 1967

By F. Chen, L. J. Gaydos, D. C. Kuhn, Demersm L. M., S. C. Sun

"Summary: In this report the differential regulation of NF-KB and nitric oxide (NO) was investigated in the mouse macrophage cell line RAW 264.7 following exposure to a mineral dust (silica) and /or an endotoxin (Lipopolysaccharide, LPS). The results indicated that silica and LPS can significantly induce the activation of NF-KB as well as elicit enhanced production of NO in RAW 264.7 cells as part of an early inflammatory response mechanism. A 24-hour time-course study showed that NO release from these cells continued to increase following the initial stimulus by LPS or silica. In contrast, activation of NF-KB was maximal at 6 hours and then showed a steady decline to 24 hours. The production of NO was suppressed by protease inhibitor and antioxidant, both of which block the activation of NF-KB. Surprisingly, the use of an NO synthase inhibitor resulted in an enhancement of NF-JCB activation. These findings suggest that NO produced in macrophage cells in response to an inflammatory stimulus like silica or LPS my be linked to a negative feedback role on the activation of NF-KB. It is now accepted that nitric oxide (NO) plays a pivotal role in the inflammation response process when macrophage cells are activated by a pro-inflammatory stimulus (l). Production of NO is dependent on the activity of the enzyme nitric oxide synthase (NOS). Up until now, at least three distinct genes have been described which encode different isoforms of NOS. NOS has been cloned from a variety of different mammalian cells, including constitutive neuron NOS, constitutive endothelium NOS and inducible NOS (2). Macrophages appear to be the principal cellular source for the inducible form of NOS (iNOS) activated in response to an inflammatory producing event. The mechanisms subserving the regulation of the iNOS gene and NO production have been under intense investigation in recent years (3-5). Several binding sites for transcriptional factors have been identified in the promoter region of iNOS gene, including NF-lCB, AP-1, NF-IL6, Oct-I to cite a few (5). NF-KB appears to play a"

Dec 1, 1996

By W. Curlook

"A review is presented of a growing number of imperatives, some self-imposed, some imposed by society, which the mining and metals industry faces in carrying out its business. These imperatives bear on all activities from the exploration phase, through engineering, design, plant construction and operation, to decommissioning.IntroductionThe mining and metals industry must learn to cope with, i.e. manage, a growing number of imperatives. Some of these, such as the need for responsible stewardship of natural resources, the requirement to respect laws and regulations, the need to provide for safe and healthy workplaces, and the need to provide appropriate returns to investors of capital , have been with the industry for a long time (fable I). But the industry now faces additional imperatives that are growing in number and in importance (fable 2):• There is the growing concern about the impact of operations, not only on the workplace environment and the external environment, but also on the need to monitor not only the chemical concentrations in various effluents but to also monitor the effects of such emissions on the environment; i.e. there is a growing concern about the ""net"" consequences of operations.• There is the need for on-going improvement in productivity and safety to compete and survive in a global economy. The global business environment has become paramount.• There is the imperative to failsafe all designs, equipment and operational procedures, and having done that to provide for containment of unavoidable spills, and to have ready and in place systems for emergency response.• There is the need, indeed the imperative, to involve all employees in various quality improvement programs.• There is the imperative to face up to ""virtual elimination/zero emissions""; and• One must have waste management plans in place to cope with the need to reduce, reuse, and recycle; and• There is the need for decommissioning plans for all operations, for the restoration of business habitats to their original states (or better). Indeed, one must engage in the decommissioning exercise from day one, i.e. right from the time of design and commissioning."

Jan 1, 1992

By E. I. Salkovitz, F. W. von Batchelder

AS Slawson1 and others have already shown, from a geometrical view twinning in the diamond structure may be considered as a reflection across a (111) plane or as a reflection across a (112) plane. An analysis by Ellis and Treuting2 showed that the twinning plane must be the (111) plane, but that a twin might have lateral boundaries along (112) planes. Earlier Slawson1 and Ellis3 had shown that only (111) twinning was present in diamond and germanium respectively. Since an ingot of silicon, 1 in. in diam and 1 1/2 in. long, prepared from Dupont silicon to which 0.2 pct Be had been added was available, it was examined for twinning. The ingot had been cooled slowly from the bottom. A section 1/16 in. thick was ground off from the bottom and then the ingot was sliced vertically through the center. Spectrographic analysis indicated only faint traces of iron and silver, in addition to the beryllium. The sample was first etched with a hot solution of 10 pct NaOH in water.and photographed. Back-reflection Laue patterns were made of the vertical and horizontal sections in the regions designated in Fig. 1. Orientations were obtained for each twin using the Greninger technique. Several regions of the same orientation were found; thus regions A and K were identical, similarly N and P, and C, G, J, and L. Knowing the angles between the traces of the twinning plane on the surface and the specimen axis, the indices of the twinning plane were deduced. In all cases the twinning plane was found to be (111); lateral boundaries, however, were found which were (112) such as the one indicated in Fig. 1. Therefore, as in the case of diamond1 and germanium' only (111) twinning occurs in silicon. We wish to thank Mr. Hino for the use of the ingot as well as for its metallographic preparation. References 1C. B. Slawson: American Mineralogist (1950) 35, p. 193. 2 W. C. Ellis and R. C. Treuting: Trans. AIME (1951) 191, p. 53; Journal of Metals (January 1951). 3W. C. Ellis: Trans. AIME (1950) 188, p. 886; Journal of Metals (June 1950).

Jan 1, 1953

By C. van Dijk

In Sept., 1960, a steam-drive project was started in the solution-gas drive area of the Schoonebeek field. A part(ern of three five-spots and one four-spot was selected covering an area of 65 acres. The pay in the project area has good lateral continuity and dips slightly to the northeut; it is about SO ft thick and permeability increases from 1,000 and at the bottom to approximately 10,000 md at the top. The oil originally in place was 12.6 X 10' bbl. The oil has an in situ viscosity of about 180 cp. At the start of the steam drive the cumulative primary production due to. solution-ga.7 drive amounted id 4 Percent of the oil originally in place. Reservoir pressure had dropped about 120 psi and no significant primary re-.serves remained. Some 11.3 million bbl of steam (all steam quantities are expressed in barrels of water vaporized) have been injected, resulting in production of an additional 4.1 X I0 9bl of oil, or 33 percent of the oil originally in place. This corresponds to a cumulative oil-stearn rario of 0.37 bbllbbl. It appears that the steam preferentially moves r updip while liquids are produced mainly from downdip wells observations indicate that tile steam flows through only the upper part of the formation. The lateral steam distribution in the pattern is satisfacrory since several prodriction wells hardly reacted and, hence, cori tributcd little to the oil production. Production performance and results from material balance calcutlations agree satisfactorily with the results of large-,scale laboratory experiments. On the basis of these experirmental results the .steam drive, together with a cold water follow-up. is expected to bring ultimate recovery to a value of crt leas: 50 percent of the oil originally in place. No serious production problems have been encountered. However, due to mechanical fuilure, two old prodriction wells and one injection well had to be replaced. An extension of the. steam drive in this area is under connstruction. Introduction The Schoonebeek oil field, discovered in 1943 and developed after World War 11, is situated in the eastern part of the Netherlands. The main oil reservoir in this field is the Valanginian sand. A completely sealing fault divides this reservoir into two areas (Fig. 1): the southwestern part of the sand body where primary production is ob- tained by means of a solution-gas drive, and the remain. der where edge-water drive is the production mechanism. In the greater part of the field the reservoir consists of a single, unconsolidated sand body. The net thickness ranges from 30 to 100 ft and the top is between 2,400 and 2,800 ft below sea level. Formation permeability varies from approximately 10,000 md at the top to values of the order of 1,000 md at the bottom, and porosity is about 30 percent. The reservoir contains a paraffinic oil of 25" API gravity with an in situ viscosity of 160 to 180 cp. Initial oil saturation was high (85 to 90 percent). The relatively large quantity of oil in place (more than 10' bbl), and the low ultimate primary recoveries expected from this field — approximately 15 percent stock-tank oil initially in place (STOIIP) for the water-drive area and 5 percent STOIIP for the solution-gas drive area — clearly indicate ample scope for secondary recovery. Because ies-ervoir and crude characteristics made this field suitable for thermal secondary recovery, a hot-water drive project was started in the water-drive area about 10 years ago. A few years later a steam drive and an in situ combustion project were started in the solution-gas drive area. This paper deals with the performance of the steam-drive project, which was started in Sept., 1960, and which is still in operation. Design of Steam-Drive Project, An experimental investigation of the steam-drive process carried out by schenk in 19561 indicated that under schoonebeek conditions steam injection could be an attractive secondary recovery method. the findings and encouraging results of a pilot test in the Mene Grande field in venezuela,i led to the design of a steam-drive project in the schoonebeek field, Pruject Site and Pattern In 1958 the reservoir pressure in the solution-gas drive area had decreased to about 120 psi, and oil production rates of wells in this area had dropped to 7 to 10 B/D. The cumulative primary production was about 4 percent STOIIP, leaving an oil saturation of approximately 85 percent. In view of the large amount of oil left behind in the reservoir, the solution-gas drive area was selected for the planned steam-drive project. The area in the vicinity of Well S1 3 (Fig. 2) was considered to be suitable since it is at least partly isolated from the rest of the field by faults and the sand is relatively thick (about 80 ft).

Jan 1, 1969

By S. Banisi, J. A. Finch, A. R. Laplante

"A technique for on-line simultaneous estimation of gas and solids holdup (volume fraction), based on a combination of conductivity and pressure difference measurements, is proposed and tested in a laboratory flotation column (10cm in diameter and 447cm in height). Fundamental concepts underlying this technique and the effect of relevant parameters are discussed. In the studied range, 3-30 %v/v gas holdup and 2-18 % v/v solids holdup, experimental results showed good agreement between the estimated and actual holdup values (as determined by an isolating technique). The relative accuracy of the solids holdup estimation increased when solids density or solids concentration increased. Frequent re-calibration of pressure transducers was found necessary for accurate phase holdup estimation.IntroductionGas holdup is a key parameter in controlling the performance of flotation columns. For example, flotation rate is affected by bubble size and gas rate both of which, in turn, affect gas holdup. Moreover, gas holdup also determines the slurry residence time which indicates a direct influence of gas holdup on recovery.Gas holdup determination has been the focus of many studies (e.g., Castillejos, 1986; Marchese et al., 1992). Some of the techniques which have been used are given in Table 1."

Jan 1, 1994

Dr R. E. Robinson, Pr. Eng., obtained a B.sc. (Chem. Eng.) cum laude from the University of the Witwatersrand in 1950 and a Ph.D. (Eng.) from the same University in 1953, where he was awarded the Haikes Memorial Medal for Industrial Chemistry. Professor G. G. Garrett was appointed Professor of Physical and :Fabrication Metallurgy in the Department of Metallurgy at the University of the Witwatersrand in June 1980, and in January 1984 he became Head of the Department. Mr P. A. van Wielligh, Pr. Eng., climbed the mining ladder in the hard way, starting as a Mine Surveyor in 1936 and working his way up as Chief Surveyor, Underground Manager, Mine Manager, and Consulting Engineer, to Executive Director, including the intermediate steps. Mr H. E. James, Pr. Eng., is a graduate in Chemical Engineering from the University of the Witwatersrand. Both his B.sc. degree (1961) and his M.sc. degree (1964) were obtained on bursaries, the former from Gold Fields of South Africa and the latter from the Atomic Energy Board. Mr G. Pienaar, Pr. Eng., obtained a B.Eng. (Met) in 1967 and an M.Eng. in 1973, both from the University of Pretoria. Dr A. K. Haines, Pr. Eng., obtained all his degrees from the University of Natal, finishing with a. Ph.D. in 1971. Mr B. C. Alberts, Pr. Eng., obtained his academic training at the University of Pretoria, where he was awarded B.sc. degrees in both agricultural engineering (1963) and mining engineering (1965). Mr H. C. van Zyl, Pr. Eng., holds B.sc. degrees in mining engineering (1968) and civil engineering (1972), both from the University of Pretoria.

Jan 1, 1984

By Christopher M. Kenney

Augered-cast-in-place (ACIP) piles have been utilized on commercial projects throughout many parts of the country for years, but are only beginning to be scrutinized for use on major infrastructure projects and other critical structures in some regions. Numerous engineers are aware that ACIP piles are an economical foundation alternative, and many technical papers have been presented that provide reliable methods of estimating ACIP pile load capacity. However, designers may not yet appreciate that the load-settlement behavior of ACIP piles is very similar to that of drilled shafts. This paper analyzes ACIP pile case histories from throughout the country and demonstrates that ACIP pile settlement under applied load is consistent, predictable, and very similar to the documented behavior of drilled shafts. This paper also presents a simple but accurate method of estimating ACIP pile settlement at the design load, and illustrates the need to estimate the equivalent diameter of the as-built ACIP pile when estimating pile behavior. Finally, this paper presents back-calculated values of the drained elastic modulus from the ACIP pile case histories that may be useful to those using more sophisticated methods of estimating ACIP pile settlement.

Jan 1, 2001

By Thor Skjeggedal

The Norwegian contracting firm A/S Høyer-Ellefsen has for the last 2.5 years carried out substantial pregrouting in a 7600m long tunnel just outside the city of Oslo. This has been done to avoid groundwater lowering and consequent damage to surface structures. A WIRTH TBM is used in combination with a 2 boom Atlas Copco hydraulic jumbo for the drilling of groutholes in front of the machine. The detailed procedure for the drilling and grouting will be discussed, and the results obtained will be presented.

Jan 1, 1981

By M. Moseki

Paper written on project work carried out in partial fulfilment of B.Sc. (Eng.) (Metallurgy of Materials) degree This paper presents the research into melting of scrap for job creation purposes in rural areas. The research was done on behalf of Mine Recycling Services (MRS), the company that will implement the project. The project involves the research into available cost effective and easy to operate technology. The paper covers the experimental and theoretical work that was conducted. The results were used to determine the best equipment and method for melting and casting brass scrap.

Jan 1, 2002

By A. H. Shapiro

A decanter centrifuge of novel design was developed for the dewatering of fine-solids slurries having micron-range particles that form paste-like, flowable, hard-to-dewater cakes. The design combines a compound beach with a cake-flow control structure that allows expressed liquid from the cake in the dry beach region to be returned back to the liquid pool while maintaining high solids throughput. In order to provide optimal performance with various operating parameters (feed rate, centrifugal gravity, pool, differential speed, concentration of feed solids, and different slurry types), the cake-flow control is adjustable. The second part of the beach is preferably at zero angle. Tests showed that the new design allows increases in both solids dryness and solids throughput.

Jan 1, 2001