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By L. R. Raymond

With the trend toward deeper and consequently hotter holes, measurements of drilling mud properties at atmospheric temperatures are becoming increasingly inadequate.' Both the prediction and control of down-hole mud properties depend in part upon our knowledge of temperatures in the wellbore. Consequently, a better understanding of factors that affect temperatures during circulation and trips could improve drilling operations. It was toward the goal of obtaining this understanding that this study was directed. Other investigators2 have studied the response of fluid temperature in the borehole during trips. However, all of these studies have used an assumed formation temperature profile at the conclusion of circulation and have provided no means to calculate this profile directly. In this study, the formation profile during circulation was calculated. Other investiga-tors3-5 have also studied bottom-hole temperature during circulation. However, they have developed neither general techniques for calculating the entire temperature profile in the system nor generalized methods for predicting bottom-hole fluid temperatures during circulation. Such techniques and methods have been developed and are discussed briefly in the following pages. Temperature Behavior During Circulation Circulation of fluid during the drilling operation is represented schematically in Fig. 1. The process of circulation has three distinct phases: (1) fluid enters the drill pipe at the surface and passes down the drill pipe; (2) fluid exits the drill pipe through the bit and enters the annulus at the bottom; and (3) fluid passes up the annulus and exits the annulus at the surface. To simulate the thermal behavior of the fluid in the system, each of the phases of circulation must be described mathematically. In Phase 1, the fluid enters the drill pipe at a specified temperature, TDo. As the fluid passes down the pipe, its temperature is determined by the rate of heat convection down the drill pipe, the rate of heat exchange between the drill pipe and the annulus, and time. Phase 2 of the circulating process merely requires that the fluid temperature at the exit of the drill pipe be the same as the fluid temperature at the entrance of the annulus; i.e., TD(L,t) = TA(L,l). Thus in Phase 3, the fluid enters the annulus at TD(L, t). As the fluid flows up the annulus, its temperature is determined by the rate of heat convection up the annulus, the rate of heat exchange between the annulus and the drill pipe, the rate of heat exchange between the formation adjacent to the annulus and the fluid in the annulus, and time. These rates of heat exchange and the time dependency of mud temperature are described by well known heat-flow equation.6 Consequently, as shown in the Appendix, the temperature profiles in the drill pipe, annulus, and formation can be obtained by solving Eqs. 1 through

Jan 1, 1970

By M. Matema

Paper written on project work carried out in partial fulfilment of BSc (Eng.) Metallurgy and Materials Engineering Small and large welded aluminium specimens were tested in fatigue and the results compared with design curves for aluminium in specification BS8118. Metallurgical tests were also performed on the specimens in order to correlate microscopic and macroscopic phenomena. The small-scale fatigue test results were in reasonable agreement with results in BS8118, whereas the large-scale fatigue tests showed that BS8118 is conservative.

Jan 1, 2005

By A. R. Gaba

Phase I of the Canary Wharf development in London's docklands involves the construction of six fifteen storey buildings located predominantly over water of the West India Docks. The buildings are supported on some 1000 No., 25m long, open ended steel tubular piles driven through 10m of dock water to found in dense sand at a depth of about 15m below dock bed level. The piles are of composite section with reinforced concrete within the upper 17m of the steel tube. Three trial piles were installed in the dock to investigate the driveability and performance of the driven steel tubular piles. The piles were subjected to dynamic and static load testing. Loads were applied in both vertical and horizontal directions. Vibrating wire strain gauges were installed on the inside of the steel piles, on the reinforcement and in the concrete to determine the relative proportions of the applied load carried by the steel tube and concrete infill and to establish how these proportions varied along the length of the piles. Inclinometers were also installed to monitor the lateral deflection of the piles. This paper describes the driving, construction and testing of the three trial piles. The results of the vertical and horizontal loading tests are discussed and comparisons are made between dynamic and static tests carried out on the piles.

Jan 1, 1989

By M. Rahmanpour

"Mine planning is a multidisciplinary procedure that aims to guarantee the profitability of a mining operation in changing and uncertain conditions. Mine plans are normally classified as long-term, intermediate-term, and short-term plans, and many factors affect the preciseness of these plans and cause deviations in reaching the objectives. Commodity price is the heart of mine planning, but it has a changing and uncertain nature. Therefore, the determination of mine plans in the presence of uncertain mineral price is a challenge. A robust mine plan reduces the risk of early mine closure. A procedure is presented to determine the value at risk (VaR) in any possible mine planning alternative. VaR is considered together with downside risk and upside potential in order to select the most profitable and least risky plan. The model is tested on a small iron ore deposit. IntroductionMining projects are normally evaluated with the objective of maximizing economic value, as measured by the net present value (NPV). The aim of mine planning is to develop a yearly extraction plan that guides the mining operation to the highest NPV (Dagdelen, 2007; Yarmuch and Ortiz, 2011). This plan considers the technical constraints such as blending requirements, block sequencing, and pit slope (Caccetta and Hill 2003). Thus, the mine plan affects the economics and the payback period of mining operations.Mine planning is a procedure based on which the profitability of the mining operation is guaranteed in changing and uncertain conditions (McCarter, 1992). However, conventional mine planning ignores the volatility and uncertainty of future commodity prices and does not allow for managerial flexibility. It is common practice to assume a deterministic and constant commodity price through the mine life. The problem with this approach is that the commodity price is the heart of the mine planning procedure and governs the profitability and feasibility of the operation; thus ignoring price volatility will result in a sub-optimal mine plan."

Jan 1, 2016

By Vojtech Gall

Pre-support measures for urban tunneling have seen a substantial development in the recent past. Ground improvement techniques, pipe-arch and spiling methods now allow for non-disruptive tunneling at very shallow depths under sensitive structures, rail tracks and roadways. The paper presents experience gained on national and international projects built over the past decade that represent case histories and therefore may be used as guidance for the development of similar solutions for future tunneling projects at shallow depths. Reference projects include tunnels for the Washington, DC Metro, London Underground, Dulles Inter-national Airport, Busway tunnels in Boston and the Ft. Canning Tunnel in Singapore.

Jan 1, 2008

By Willem Le Roux

1.1 Section 47(1) of the Mine Health and Safety Act, 29 of 1996 (?the MHSA?) establishes a Mine Health and Safety Inspectorate which is administered by the Chief Inspector of Mines. The Mine Health and Safety Inspectorate is part of the Department of Mineral Resources. The Chief Inspector is appointed by the Minister of Mineral Resources (see section 48(1) of the MHSA). 1.2 The Chief Inspector must, amongst other things, ensure that the provisions of the MHSA are complied with and enforced, and that all the duties imposed upon the Chief Inspector and the other Inspectors of Mines in terms of the MHSA and any other law are performed. The Chief Inspector of Mines must appoint Principal Inspectors of Mines and Inspectors of Mines to assist him/her to discharge his/her duties (see section 49(1)(a) and (c) of the MHSA).

Jan 1, 2011

By A. T. van Zyl, M. Mthenjane, M. J. Cole

Growing global concern over the impacts of climate change, attributable largely to fossil fuel energy sources, has led to the widely shared goal for a ‘just transition’ to cleaner energy and reduced dependence on carbon-based fuels. As the world’s 14th biggest CO2 emitter and being particularly vulnerable to the impacts of climate change, South Africa must embark on a just transition pathway. This paper reviews expected coal mine closures and associated community vulnerabilities and local governance challenges in South Africa. Decommissioning schedules for all coal-fired power stations and operating coal mines are plotted, and 69 mining host communities and 21 municipalities are mapped, classified, and described. Community socio-economic profiles are measured using a set of SDG indicators and census data and municipalities assessed through financial audits. Our research shows that five coal-fired power plants (8.9 GW) and 15 coal mines (29.5 Mt/a) will probably close by 2030, and a further four plants (14 GW) and 23 mines (106 Mt/a) by 2040. Thus, the shift to cleaner energy will likely occur without the premature closures implied by the just transition. The impact of mine closure on the 2.5 million residents of host communities will be significant, particularly as levels of income, employment, and education are already very low and many municipalities are in financial distress. The South African approach to the just transition needs to take local realities into account and the narrative must support an effective transition that does not undermine energy security and economic growth.

Jun 5, 2023

Overcasts are indispensible ventilation control devices to permit one airway to pass over another without mixing in room and pillar coal mining. The airflow distribution inside the overcast depends on its spe-cific configuration at which the flow enters into it. This study uses 3D numerical simulation to examine the pressure and velocity distributions inside an overcast. The effects of the overcast angle on the flow field are also examined. The flow is assumed to be turbulent and isothermal and the standard k-e model is utilized. Simulated results display flow separation and recirculation regions of different sizes occurring not only upstream and downstream from the overcast but also inside it. The results also show that the size of the recirculation regions in-creased with the increase in the angle before and after the overcast influencing significantly the flow field and pressure losses. The stream-lines are plotted to show the 3D structure of the flow field. The results from the simulation can guide overcast design commonly used in un-derground coal mines. Keywords: 3-D simulation, Overcast, Room and Pillar, Turbulence, Recirculation Region

Feb 27, 2013

By Yoshihiro Kawarabata

INTRODUCTION With only about 30% of Japan's entire population served by sewer systems at the end of 1980, extensive sewerage construction programs have been implemented. As major sewer networks in large cities are near completion, construction of smaller sewer networks in less populated areas and branch sewers in urban areas is on the rise, where a demand for sewer tunnels of 600mm to 1500mm diameter is very heavy. The pipe jacking technique, usually employed to excavate such small diameter tunnels, therefore has become the subject of further technological development and sophistication to cope with the increasing volume of construction. At the 1979 RETC, the state of the art on the slurry shield tunneling method at that time was reported. This paper is a follow up to the last paper and discusses a newly developed boulder crushing equipment and automatic pipe jacking system for the slurry shield method and their application. Such technological advancement as high-degree mechanization and automation will significantly improve tunneling operations in response to the aging society to come. Through application of the technique on so called factory automation, this is a step towards field automation for the construction industry.

Jan 1, 1983

Several years ago, Hudco Industrial Products began experimenting with the idea of levitating a conveyor belt with a film of air, much like the puck on an air-hockey table. While conducting its research, the company found out that some Russian and Dutch companies attempted the concept during the 1970s. After studying those conveyors, Hudco determined that its design was better. The Hudco advanced air-supported conveyor consists of an air-tight plenum, or chamber, that runs the length of the belt. The topside of the plenum has a formed trough. It corresponds to the profile of conventional troughing rollers. Low-pressure air is provided to the sealed plenum from a low horsepower blower. This pressurized air is metered and released through the central portion of the trough and reacts against the underside of the belt. The differential pressure between the top and bottom surfaces creates the lift to support the loaded belt. Airtight covers are installed to seal the transported materials in the plenum trough.

Jan 1, 2002

By Met M, Worner H. K

In pursuance of the investigation into the influence of various elements on the properties of lead during the past year, the effect of several elements on the creep rate of commercially pure lead has been investigated; a standard initial stress of 500 lb. per sq. in. having been adopted for comparison purposes. Other work which has been carried out indicates that the relative results of creep tests may be altered by varying the applied stress, but this aspect of the problem will need to await further investigations for itscomplete elucidation. The results obtained with dilute tellurium alloys are considered sufficiently interesting, and in some respects are so extraordinary, as to warrant publicatiorr at this stage.n must be realised however that, since the results obtained appear to be at variance with those said to have been obtained in practice and those previously published, the present investigation can only be considered as a contribution to our knowledge of the general problem.Consequently it is not considered advisable or necessary to offer detailed explanation of the results given. In fact, some features of the tests about to be described will need further investigation before an adequate explanation is possible.

Jan 1, 1936

By Andrea McGlynn

Iron Ore Company of Canada, Labrador City 2011?Canada's largest iron ore producer, leading global supplier of iron ore pellets and concentrates ?Rio Tinto (58.7%), Mitsubishi Corporation (26.2%), Labrador Iron Ore Royalty Income Fund (15.1%)

May 1, 2011

By Oswaldo Ortiz Sánchez

El presente trabajo describe la alternativa de uso del mortero de resina en la fijación de pernos de anclaje de las excavaciones mineras, consolidación y disipación de vibraciones en los cimientos de plataformas para la instalación de molinos, winches, tolvas, etc. Esta opción surge en respuesta al problema de reforzamiento con pernos de anclaje en ambientes con aguas corrosivas o en proceso de deformación acelerada en las excavaciones mineras, así como ante obstáculos de subsidencia de cimentación en plataformas, donde se encuentran instalados equipos de gran tonelaje, y que producen fuertes vibraciones durante su funcionamiento.

Jul 31, 2003

By J. F. Lupo

Leaching operations combine both metallurgical and hydraulic processes to extract metals from the ore heap. In the design of leaching operations, metallurgical tests and simple hydraulic tests are often conducted to define operational parameters such as leach cycle time, application rate, lift height, and effective leach area. While metallurgical constraints are often the primary focus on leach facility design, the hydraulic factors are also critical to the overall success of the operation. Some of the hydraulic factors that are known to impact solution flow through heaps include: • Ore physical and hydraulic properties, • Variation in ore properties under heap loading, • Ore mineralogy and its susceptibility to chemical and/or mechanical degradation, and • Heterogeneities within the heap. This paper presents a discussion on hydraulic factors that may impact the effectiveness of leaching operations. In addition, methods are presented which may be used to assess flow conditions within active and inactive heaps.

Jan 1, 2000

By Pound J. R

THIS mine, which is the property of the S. and M. Syndicate, London, is located at Moina, in North-West Tasmania, 18 miles from Stavertorr railway station and 36 miles from Devonport. There are metalled roads from both of these places, and, althoughhilly, these are good for team or motor traffic. Mails and passengers are provided for by a tri-weekly coach service from Sheffield, a railway town, distant 23 miles. The Moina mining field is situated on a main spur between the Forth and Iris Rivers, andat an elevation ranging from about 500 ft. above sea-level at the Forth River to 2400 ft. at the All Nations mine. The elevation at the mine office of the S. and M. mine is 1900 ft. The average annual rainfall, as recorded for the past eight years, is. 68 in.This inclildes, however, a couple of years during which the rainfall was much above normal, and taken over a longer period 60 in. would be nearer the average.

Jan 1, 1919

Characterisation of Manganese Ores

Sep 13, 2010

By T. O. Hagan

A simulated rockburst experiment was conducted underground at a deep level gold mine. This was done by means of a large explosion detonated in solid rock close to a tunnel sidewall. The resultant shake-out damage is typical of that associated with a small seismic event in close proximity to a tunnel that is subjected to the estimated field stress, as in this case, of 50 MPa. The experiment involved: ?the design of a blast to mimic a seismic source ?seismic monitoring using a dense seismic array ?high speed video filming ?a study of rock mass conditions (fractures, joints, rock strength etc.) before and after the simulation using mapping and ground penetrating radar ?special investigations to evaluate the mechanism and the magnitude of the damage ?a study of support behaviour under excessive dynamic loading.

Jan 1, 2001

By P. C. Schutte

Ergonomics is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance. Despite the fact that the application of ergonomics principles can make a major contribution to the management of significant occupational safety and health risks, ergonomics is currently applied on a limited scale in the South African mining industry. The objective of this paper is to provide a perspective of ergonomics, the main aim being to create a point of departure for the development of strategic objectives to enhance existing health and safety initiatives through the application of sound ergonomics principles. Two of the major consequences of poor ergonomics, namely work-related musculoskeletal disorders and worker fatigue, and possible means of introducing ergonomics into the South African mining industry, are discussed.

Jan 1, 2005

Shortly after Denny, Robson, and Irwin published their first paper in 1937, on the prevention of silicosis by metallic aluminium, experiments were begun on the practical application of the discovery.It was thought at that time that aluminium powder, to be effective in aluminium therapy, would have to be intimately admixed with siliceous dust at the latter's source. There followed several years of experimental work underground, during which the application of aluminium powder was tested in:(1) Speakers on machine columns, vibrated by drills.(2) Vials placed in drill holes to be blasted.(3) Both homogeneous and heterogeneous mixture with explosives.(4) Packages with tamping.(5) Compressed-air lines.(6) Special compressed-air ejectors for use while drilling and after blasting.(7) The discharge of ventilation fans.(8) The filters of respirators.It was concluded from this research that any adequate method of introducing aluminium powder into a mine atmosphere would require too much extra gear, supervision, and aluminium p;wder, and would interfere unduly with underground routine.Later, animal experiments by Denny, Robson, and Irwin2 showed that aluminium powder provided effective therapy when inhaled independent of silica dust. Therefore, some means of surface treatment was deemed more practical.APPARATUS USED IN THE DEVELOPMENT OF ALUMINIUM PROPHYLAXIS SAMPLINGA basic requirement was a method of sampling to assess accurately the particle-size concentrations of dispersed aluminium powder. Konimetry, though regularly practised at McIrityre, was inadequate for the research in mind. On the other hand, the efficiency of the thermal precipitator was recognized as being very high. Accordingly, the latter instrument was chosen as best suited to our needs. Through the courtesy of the Ontario...

Jan 1, 1945

The Manto Verde mine is found in the coastal ranges of the Atacama desert, 1000 km north of Santiago, Chile . The deposit is a fault-breccia specularite-oxide copper mineralisation hosted by the Jurassic andesites of La Negra Formation. It is located in a tensional fault that joins twoparallel arms of the Atacama Fault. The mine is in feasibility study: reserves are of the order of 60 Mt at 0.9 wt per cent soluble copper; mining will be undertaken at a rate of 11 000 tpd utilising an open pit and the ore will be heap-leached with acidified sea water, with copper recovery and by SX/EW.

Jan 1, 1992