Search Documents

By L Edwards, M Haest, D Mittrup

The focus in the iron ore industry has shifted from increasing production volumes with less regard for cost, to efficient production of quality tonnes. BHP Billiton iron ore geoscience and exploration has embedded infrared spectroscopic sensing of drill hole samples to help meet this challenge.Infrared spectroscopy is delivering mineral predictions that are used for (automated) geology logging and modelling. The spectra are processed together with other available data sets to predict geometallurgical and geotechnical variables that include lump per cent and uniaxial compressive strength.Trials are ongoing to test the benefit of infrared spectroscopy during mining, including the analysis of grade control samples and remote sensing of mine faces. Results show great benefits in the fields of short-term geology modelling, better understanding of material (handling) properties, identification of geotechnical risk areas and high resolution ore-waste delineation.These trials are bringing BHP Billiton iron ore closer to its ultimate goal of having infrared spectroscopic data collected across the mining value chain. Once such data are available everywhere, regression models can be trained at one point (eg iron grade model trained on exploration samples) and be applied elsewhere (eg iron grade predicted on mine faces). Such predictive analytics will enable not only high precision mining, but also provide maximum time to tailor plant design to the ore in the ground, based on learnings from ores processed in other plants. This will improve planning outputs that will eventually increase mining efficiency, processing capability and product quality.CITATION:Haest, M, Mittrup, D and Edwards, L, 2017. Infrared spectroscopy in BHP Billiton iron ore with a focus on in-mine infrared sensing, in Proceedings Iron Ore 2017, pp 549–556 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By S Watson, L Martinez

Mine projects are complex opportunities that demand a constant assessment of uncertainty, ie risk and upside potential. This is because the value of a mine project is typically influenced by many underlying economic and physical uncertainties, such as metal/mineral prices, metal/mineral grades, costs, schedules, quantities, and environmental issues, amongst others, which are not known with much certainty at the beginning of the project. But, is uncertainty an enemy or an ally of the mine planner/analyst? To answer this question, this paper first assesses and elaborates upon the general concept of uncertainty. It then looks at the different sources of uncertainty in a mining project, such as the orebody, costs and product price uncertainties, and their effect on the final project value. Next, a general?review?of current mine evaluation techniques highlighting their limitations when dealing with uncertainty is made. Finally, an extended evaluation and risk management framework that addresses the existing uncertainty in the (greenfield/brownfield) mine evaluation process is proposed. One important characteristic of this framework is that it uses and manages uncertainty in order to generate additional value to the project; this is done through operational and managerial flexibility, which allow mine planners to minimise/maximise project risk/upside-potential giving a more realistic estimate of the projectÆs market value - this is shown in practical and simple examples occurring at different stages of a mine project, such as exploration and operation. Final conclusions are provided at the end.CITATION:Martinez, L and Watson, S, 2012. Uncertainty - An important source of (additional) value for mine projects, in Proceedings Project Evaluation 2012 , pp 131-140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By Jonty Tshipa

The Mine Site Technologies, MST BlastPED ST is a wireless/remote blasting system used in more than sixty (60) mines (including two mines in Zambia and one in Tanzania) since its release in 2002. The system consists of a controller and signal tube initiator which communicate wirelessly using spread spectrum frequency. This technique ensures a robust and secure wireless link between the controller and the signal tube initiator. The configuration of the system ensures ease of use with all the instructions for initiating the blast printed on the equipment. This means little or no formal training is required to use the system. The technology enables you to have your blasting point at a distance of up to 4 km, line of sight (LOS), as opposed to the traditional distance of 500m from the blast. This ensures the blast takes place from a safer and secure location. The paper and presentation will provide the audience with the benefit of many years of international mining know-how in this technology as well as more recent local African experiences. There will be references to demonstration blasts done in South Africa, current users in Africa and elsewhere. Practical Return on Investment (ROI) calculations and references to safe blasting practice will also be included.

Jan 1, 2008

By A. Golshani, M. Oda, K. Suzuki, T. Takemura

Anisotropic behaviours of OhshimaOshima granite were investigated by carrying out uniaxial compression tests, together with observations of microcracks under an optical microscope. The elastic modulus tensor of Oshima granite at 10 per cent strength,E10, were calculated using theoretically formulation of elastic modulus tensor in terms of the second-rank crack tensor for pre-existing open microcracks. Furthermore, with the assumption of orthorhombic elasticity, the nine moduli of Oshima granite E10were determined by uniaxial compression test. Twenty-onemoduli of samples, calculated without assuming any symmetry, also showed orthorhombic features. Direction of the symmetry axes agreed well with the orientation of preexisting cracks. Comparison of crack tensor-based formulation results with the experimentally determined one show that the anisotropy of elasticity of Oshima granite is caused by pre-existing open microcracks, not by pre-existing healed microcracks and also crack tensor formulation can be used, as a first-order approximation at least, to describe the anisotropy of Oshima granite induced by pre-existing open microcracks. ZUSAMMENFASSUNG: Das anisotrope Verhalten des Oshima-Granits wurde mit Hilfe voneinachsigen Kompressionstests und durch die Betrachtung von Mikrorissen unter einem optischenLichtmikroskop untersucht. Das Elastizitätsmodul von Oshima-Granit bei 10 Prozent Kraft E10wurde berechnet, indem man die Formulierung des Elastizitätsmodultensors, ausgedrückt alsRisstensor zweiter Ordnung theoretisch auf bereits existierende Mikrorisse angewandt hat.Außerdem wurden die neun Module des Oshima-Granits unter der Annahme orthorhombischerElastizität E10mit einem einachsigen Kompressionstest bestimmt. Einundzwanzig Stichproben,die ohne die Annahme irgendeiner Symmetrie genommen wurden, zeigten ebenfallsorthorhombische Merkmale. Die Richtung der Symmetrieachsen stimmte mit der Orientierungbereits vorhandener Risse überein. Der Vergleich der Ergebnisse der auf dem Risstensorbasierenden Formulierung mit der experimentell bestimmten Formulierung zeigt, dass dieAnisotropie der Elastizität von Oshima-Granit von bereits vorhandenen offenen Mikrorissenverursacht wird, und nicht von vorhandenen vernarbten Mikrorissen, und dass dieRisstensorformulierung auch zumindest für eine Annäherung erster Ordnung benutzt werdenkann, um die durch vorhandene offene Mikrorisse induzierte Anisotropie des Oshima-Granits zubeschreiben. RESUME: Les comportements anisotropes du granit d’Oshima ont été étudiés en réalisant destests de compression simple, et en observant les microfissures au microscope optique. Le tenseurdu module d’élasticité du granit d’Oshima sous une résistance de 10 pourcents, E10, a été calculéen se servant de la formule théorique du tenseur de module d’élasticité basé sur le tenseur defissures de second ordre des microfissures ouvertes préexistantes. En outre, sur base del’hypothèse de l’élasticité orthorhombique, les neuf modules du granit d’Oshima ont étédéterminés par des tests de compression simple. Vingt et un modules d’échantillons, calculés endehors de toute hypothèse de symétrie, ont aussi montré des caractéristiques orthorhombiques. Ladirection des axes de symétrie correspondait bien à l’orientation des fissures préexistantes. Lacomparaison des résultats de la formule basée sur le tenseur de fissures avec les résultatsdéterminés expérimentalement montrent que l’anisotropie de l’élasticité du granit d’Oshimaprovient des microfissures ouvertes préexistantes, et non de microfissures préexistantes referméeset que la formule du tenseur de fissures peut servir, au moins comme première approximation, àdécrire l’anisotropie du granit d’Oshima marqué par des microfissures ouvertes préexistantes.

Jan 1, 2003

By George W. Doffing

Numerous contradictory statements have been made in the past regarding the importance of the seasonal influence of demand for motor fuel on prices of oil securities. It has often been said that the time to buy oil securities is in the spring, or just prior to the heavy consuming season for gasoline. The fallacy of this argument is brought out in the following paragraphs. Seasonality of Oil-security Prices The indexes used in this paper as indicators of prices of oil securities and general industrials are those compiled by Standard Statistics Co. The oil producing and refining stock index includes 14 representative petroleum companies, while the all-industrials index is made up of 347 issues. All figures are stated as relatives, with 1926 = 100. The primary basis of the index, and one that gives a good weighting of the relative importance of the company within the industry, is the total market value of the stock issue outstanding; i.e., the market price times the number of shares outstanding. Adjustments are made for the addition or elimination of issues from the group index, for stock dividends, split-ups, stock rights, et cetera. At the present time the oil producing and refining index includes the following companies: Atlantic Refining Co., Consolidated Oil Corporation, Continental Oil Co., Gulf Oil Corporation, Humble Oil & Refining Co., Ohio Oil Co., Royal Dutch Co., Shell Union Oil Corporation, Socony-Vacuum Oil Co., Standard Oil Company of California, Standard Oil Co. (Indiana), Standard Oil Co. (New Jersey), Texas Corporation, Union Oil Company of California. In calculating the seasonal for oil-security prices several periods have been selected as indicat,ive of major changes in the industry, as follows: 1. 1918 through 1936. This gives an over-all picture of the industry during the motor-vehicle, motor-fuel era. 2. 1927 through 1936. This period includes the control stages, both voluntary and coercive. 3. 1927 to September, 1933. This is the pre-code period of control.

Jan 1, 1937

By Louis Huntoon

HISTORY of the Porcupine area has been pub-lished in detail by the Ontario Bureau. of Mines in several issues of its annual reports. An. interesting volume could be written on: this topic; especially if personalities were introduced, such as the. transaction whereby the original title to the Hollinger group of claims was settled between Ben Hollinger and Alex Gillies by the toss of a coin. The early history of the McIntyre mine also had its thrilling events, such as its manager, R. J. Ennis, dodging the sheriff and deposit-ing red-hot gold bricks in the bank to meet his pay-roll. The occurrence of quartz veins containing low gold values was reported in 1896 by E. M. Burwash and again in 1899 by W. A. Parks. The first application for a mining claim appears to have been applied for on Dec. 30, 1906, by W. 0. Taylor, of Toronto, one of the old employees of the Hudson Bay Co. On the recom-mendation of Mr. Taylor, early prospecting was done on the shores of Porcupine Lake. It. was not until the spectacular discovery of the surface croppings at the Dome mine, by J. S. Wilson in 1909, that a rush to the district took place. Exploration was carried on during 1910 and 1911. The big boom was on in 1911, when claims sold on the evidence of mere rock croppings, owing to the prevailing heavy overburden. Rock croppings with specks of gold brought big prices. The country was heavily timbered and most difficult to prospect. My first trip was made during the summer of 1911, while the railroad was under construction from Porquis Junction to South Porcupine. I published my observations in the Canadian Mining Journal, Dec. 15, 1911, discussing in particular the character of the ore deposits and the future prospects of the camp. The first mills were erected in 1911, only to be destroyed by the disastrous fire in July of that year. They were rebuilt and the first important shipments are recorded in 1912. The history of the camp from the discovery of the Dome to the present consists of alternate chapters of great optimism and those of a more non-committal nature. For the engineer unfamiliar with the character of the deposits of this area, and the north country in general, it is at times most difficult to draw conclusions and submit definite recommendations. When valuable orebodies apex at depth, with no surface showings other than slightly mineralized veins of quartz or quartz containing a little visible gold; when at depth valuable veins and ore deposits, paralleling the one being explored, are developed by cross-cutting, such as Nos. 85-58 on the Hollinger, which have been its largest producers, the engineer assumes responsibilities rarely called for in other mining districts. This fluctuating aspect is exemplified in the three large producers, and may be duplicated with some of the old producers now being explored.

Jan 8, 1923

By Herbert Clark Hoover, Lou Henry Hoover

As stated in the preface, the nomenclature to be adopted for weights and measures has presented great difficulty. Agricola uses, throughout, the Roman and the Romanized Greek scales, but in many cases he uses these terms merely as lingual equivalents for the .German quantities of his day. Moreover the classic language sometimes failed him, whereupon he coined new Latin terms adapted from the Roman scale, and thus added further confusion. We can, perhaps, make the matter dearer by an illustration of a case in weights. The Roman centumpondium, composed of zoo librae, the old German ceniner of 100 pfundt, and the English hundredweight of 1112 pounds can be called lingual equivalents. The first weighs about 494,600 Troy grains, the second 721,900, and the third 784,000. While the divisions of the centumpondium and the centner are the same, the Libra is divided into 12 unciae and the pfundt into 16 unizen, and in most places a summation of the units given proves that the author had in mind the Roman ratios. However, on p. 509 he makes the direct statement that the centumpondium weighs 146 librae, which would be about the correct weight if the centumpondium referred to was a ceniner. If we take an example such as " each centumpondium of lead contains one uncia of silver", and reduce it according to purely lingual equivalents, we should find that it runs 24.3 Troy ounces per short ton, on the basis of Roman values, and 18.25 ounces per short ton, on the basis of old German. If we were to translate these into English lingual equivalents of one ounce per hundredweight, then the value would be 17.9 ounces per short ton. [ ]

Jan 1, 1950

By J. A. L. Napier

This paper presents an overview of work carried out by the CSIR Division of Mining Technology and formerly by the Chamber of Mines Research Organization (COMRO) to quantify the behaviour of the stope fracture zone near deep level goldmine stopes. The motivation for this work is first reviewed in the context of the unsatisfactory status of current mine layout design criteria. Numerical methods to represent failure processes are reviewed briefly. Specific studies of microfracture processes are described as well as physical modelling experiments that can yield insights into deformation mechanisms. Modelling of stope scale deformation mechanisms are presented and considerations relating to elastodynamic modelling of the rock mass are described. The implications of this understanding in relation to prospects for active fracture zone ?engineering? are outlined and finally, the directions of future research work are proposed.

Jan 1, 1997

By Paul Weir

FOR the first time in 1938, bituminous coal production for the week ending Nov. 19 surpassed that of the corresponding week in 1937, and indexes of industrial activity indicated the possibility that the remaining weeks of 1938 would run ahead of the corresponding weeks of the preceding year. But regardless of this year-end pickup, total production in 1938 was approximately 25 per cent less than in 1937. The estimate of 340 million tons for 1938 places the bituminous industry slightly above the production level of 1933 and approximately 10 per cent above the modem low of 1932. Anthracite production is not subject to the same extent as is bituminous coal to fluctuations arising out of the rate of industrial activity, hence the decline from 1937 has not been so great being approximately 14 per cent under 1937. The estimate for 1938 production is approximately 45 million tons, but this represents the lowest level reached in the last fifty years with the possible exception of several strike years.

Jan 1, 1939

By T. E. Wakefield

Over several decades in Southern Africa the advance rates when sinking vertical shafts have declined significantly. The upside has been a substantial improvement in shaft bottom conditions and a commensurately improved safety performance, with an increasing number of shafts being sunk without fatalities and disabling injuries. This paper briefly reviews historical sinking rates and matches changed sinking productivity to the introduction of new sinking methods that have been adopted to eliminate/mitigate safety risks. Meeting the challenge of returning to historical advance rates whilst progressing in the quest for zero harm by utilizing three dimensional animated computer modelling is described. Making use of commercial modelling software makes it easier to evaluate different methods, sequencing, in shaft barrel ergonomics, and stage and shaft bottom layouts before procuring project plant and equipment. Benefits accrue not only in better communicating methods and configurations for detailed planning and design, but also during crew training. The traditional engineering ?as-built? drawing practice has been extended to the concept of an ?as executed? sinking model which seeks to capture operational experience and learning for future best practice. The paper concludes with some of the organizational culture challenges being overcome as this non traditional approach to shaft sinking optimization is being introduced.

Jan 1, 2009

By Douglas F. Stevenson

Your committee doesn't assign any easy topics to us speakers. How do you define "successful" in what is essentially a losing game? I am reminded of the fellow who returned from a one-week vacation in Las Vegas, and proudly stated, "I only lost $150." To him, that was "success." I am afraid that workers' compensation is a losing game for employers, too, and success has to be defined in terms of how much or how little is lost. We have no chance of producing a profit for our employer. We will narrow down to some suggestions about conducting a workers' compensation program at the plant level, but first I want to discuss the general legal, social and legislative climate in which your plant program operates. Workers' compensation is a statutory program with its general parameters established by the legislature. These parameters are then amplified by the boards and commissions established to administer workers' compensation. What influences the legislature and the boards and commissions as they establish the framework in which we must function?

Jan 1, 1986

Risk management has become an essential tool for mining companies to ensure their projects are well-managed and profit expectations are achieved. Risk management has also become a mandatory corporate governance requirement in Australia for publicly listed companies and equally important to attract investors. This paper provides a brief overview of the essential tools needed to implement a practical risk management framework to comply with the internationally recognised ISO 31000:2009 risk management-principles and guidelines from the perspective of small or soon to be producing mining companies. To?successfully?deal with the unknown and to manage the opportunities and risks involved with a mining project requires a clear understanding of the basic risk management principles. These include how to develop a project risk register, how to develop a project risk treatment plan and how to manage and monitor project risks to take full advantage of the opportunities presented.The first step is to identify and fully appreciate the risks that face a mining project. There are many risk identification methods that can be used including checklists, brainstorming and hazard and operability (HAZOP) studies. These often lead to a telephone book full of risks which are near to impossible to manage. A risk library specifically designed?for mining?projects containing no more than 100 risks will cover the major showstoppers, is practical and can be readily implemented and successfully managed.A risk framework also needs to be established which is compatible with the companyÆs structure and objectives. Once each risk has been assessed in regard to consequence and likelihood and the risk control systems are in place they need to be assigned to the responsible manager. The extreme or high risks will require a risk treatment plan to be developed. Risks will change during the life cycle of a mining project. Hence, a reliable monitoring system is also required for compliance.CITATION:Jones, J A, 2012. Mine project risk management, in Proceedings Project Evaluation 2012 , pp 117-122 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By H. W. Brandt

A field test was designed to inject a specially formulated two compound epoxy resin into the roof rock ahead of a working face to cement fractures and formation interfaces at the Westmoreland Coal Co., Winding Gulf Div., Eccles No. 5 Mine, Eccles, West Virginia. Five 30 foot long X 2 inch diameter, hold were drilled at an angle of 15° above the plane of roof line front the face of a working entry. The epoxy resin compounds were pumped through a proportioning unit and mixed in-line before being discharged into the drill hole under treatment it injection pressures up to a maximum of 450 psig. When the coal face was advanced an anomalous failure of the roof rock occurred in the treated section. Further testing was suspended until the cause of the failure could he determined. The polymers were tested, under confined conditions, in 2 inch pipe columns. Extreme temperature and pressure (up to 2400 psig) rises were recorded as they cured, It was concluded that this pressure source fractured the rock and caused the roof failure. The entire program was terminated after it was determined that the heat rise and resultant high pressures could not he controlled chemically or mechanically.

Jan 1, 1978

Powder River Basin (PRB) mines were originally built to serve power plants designed specifically for their coal. Sulfur was the major concern, with BTU and sodium limiting the market for some. The Clean Air Act has extended the PRB market into plants converting from other coals. These new customers are more sensitive to constituents affecting boiler and precipitator performance. At the same time, the prospect of deregulation is forcing power companies to control cost more stringently than ever. Jacobs Ranch Mine has responded to the changing marketplace with an expanded coal quality and customer service program.

Jan 1, 1998

By Glenn A. Shirey

The objective of this contract as to prepare a detailed, readily usable handbook on dust control techniques for longwall mining operations. Information was gathered from available literature, and through contacts with industry and government personnel. The handbook describes those methods of dust control applicable to today's longwall mining systems, and contains sufficient design elements to assist operators with problems in testing or implementing new control procedures. Complete reference lists are presented at the end of each chapter to direct the reader to additional information.

Jan 1, 1985

By C. van der Poel, R. L. Chuoke P. van Meurs

When an initially planar interface between two im-ttitcihle liquids is displaced at constant rate, U, nor-mat to the front, instability will occur for all rates greater than a critical rate. U, given by provided the Fourier decomposition of the spatial pertmrbcrtiott or deformation of the moving displacetment front contains modes with wavelengths. A, greater than a critical wavelength, given by tit there expressions, p, p and k, with the subscripts I and 2 distinguishing the two 1iquids under consideration, are density, viscosity and effective pemeability coefficients respectively; g is the absolute value of the acceleration due to gravity; and cos (zz') is the direction cosit7e between the vertical carlesian coordinate z' (positive upward) and the z coordinate norma1 to the initially plane macroscopic interface taken positive in the direction from Liquid I to Liquid 2. U is the average volumetric velocity (injected volume of liquid pet. unit time per unit of area normal to Z) and is positive for Liquid I displacing Liquid 2, negative for the reversc displacement and r2 is an effective inter-fucial tension (for displacements between parrallel plates, t0= s the ordinary bulk interfacial tension). further, there is a wavelength of maximum instability given by For natural perturbations, this wavelength will preclotninate and characterize the form of the instability as a quasi-sinusoidal deformation, i.e., viscous fitzgers of peak-to-peak separatiotr, A,,. Comparison of experitient with theory rei'eals tltat these considerations are recsonably valid for displacements in hoth parallel plate chantzels and nnconsoli-clutt'd glass ptnvder packs. These results are. tij particular interest for interpretation of data from laboratory experiments with regard to fielil applica/iotz.s. It is quite possible for A,, although st7zall relative to the large lateral dimension of the reservoir, to rxceed the greatr.st lateral extent of the lahoratory sample or model. If it does, frontal displace- ment occurs in the laboratory experiments, and oil INTRODUCTION Thc puposes of this paper are to present theoretical and experimental evidence for occurrence of macroscopic instabilities in displacement of one viscous fluid by another immiscible with it through a uniform porous medium and to compare available experimental data with some predictions of a theory of instability developed by the first author. The instabilities are referred to as macroscopic in the sense that spatially quasi-sinusoidal, growing fingers of the displacing liquid are formed, the width and peak-to-peak separation (wavelength) of which is large relative to a characteristic length of the particular permeable medium such as grain size. Visual models of two kinds have been used to obtain observations: displacement of oil by water-glycerine solutions through the flow channel formed by closely spaced parallel plates and displacement of oil by water with and without initial interstitial water through unconsolidated glass powder packs, employing the technique of matching indices of refraction. In all cases we have observed macroscopic instabilities or fingers under conditions predicted by the theory to be favorable for their occurrence. The phenomenon discussed here is not the production of streamers due to gross inhomogeneities such as permeability stratification of the porous medium. It is our object to show, on the contrary, that a quantitative prediction of finger spacing is possible in a porous medium known to be macroscopically homogeneous and isotropic throughout. The importance of the phenomenon in its influence on the configuration of oil and water with respect to oil production behavior was noted earlier by Engel-berts and Klinkenberg' who coined the term "viscous fingering". THEORY Necessary and Sufficient Conditions ior Instability anc Initial Kinematics There are several levels of increasing complexity in the theoretical description of instabiIity of fluid displacements in permeable media. Of these, the simplest description, ;tdapted to low permeability systems, is selected for presentation.' More inclusivc tlescriptions are reserved for separate publication.

By A Giblett, B Putland

This paper provides a simple guiding framework for grinding circuit optimisation, focussing on common themes in past optimisation success stories, the conditions for success and techniques that can be employed to identify and define opportunities. Many significant grinding circuit improvements have been reported for operating plants, based on recurring themes such as the optimisation of mill feed size, mill liner design, process control, critical size, grinding media and classification. The paper condenses these experiences into a set of simple questions for the operator to ask, and provides guidance towards identifying and achieving the optimisation goals.CITATION:Giblett, A and Putland, B, 2018. The basics of grinding circuit optimisation, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 129–140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Joseph J. Feiler

Fires in underground coal mines are persistent problems anywhere in the world that coal is mined. Coal fires pose safety and health hazards in the form of mine subsidence, loss of energy reserves, destruction of property and surface improvements, and air pollution. In 1995, the US Bureau of Mines (US-BM), in cooperation with the Colorado Division of Minerals and Geology (CDMG),entered into a contract with Goodson & Associates Inc. (GAI) to design and field test the effectiveness of a new foamed grout technology called ThermoCell. GAI is a Lakewood, CO geotechnical and mining reclamation engineering firm. The company developed ThermoCell to control and extinguish underground coal fires. The viability of the special grout and the technology of application were established during a full-scale field demonstration at the abandoned IHI Coal Mine fire, near Rifle, CO. Following acquisition of additional funding by CDMG in 1999, Goodson returned to the site in April to continue the grouting to fully extinguish the IHI fire.

Jan 1, 2000

By Harold L. Overton, Leonard B. Lipson

The first paper in this series1 outlined practical methods for applying the theory of steady-state flow of an ideal Bingham plastic liquid through a circular pipe and axially through a stationary concentric annulus to the enginekring analysis of friction loss problems. In the present paper the properties of another useful rheological model, the pseudoplastic generalized Newtonian liquid, are considered. The terminology applied to the rheological models is derived from the following classification of rheological models. The term "generalized Newtonian" is a class designation applied to models which do not have yield points but which exhibit a dependence on shear rate. The term "pseudoplastic" applies to a sub-group of models within this class which exhibit a decrease in "viscosity" with increasing shear rate. The term "power model" refers to a mathematical model proposed for describing the behavior of the pseudoplastic liquid. This model is of interest since certain of the salt saturated, oil emulsion, and "low solids" drilling fluids, inverted emulsion- and oil-base drilling fluids, aqueous gels, gelled crudes and blocking agents employed in hydraulic fracturing operations are of this type. The present treatment considers the equations describing steady-state Poiseuille flow through a circular pipe and a stationary concentric annul us, and Couette flow between concentric rotating cylinders for a particular pseudoplastic model. As in the previous paper' it is demonstrated how these equations can be applied to engineering calculations of friction losses. Graphical procedures for recovering the various flow curves and cxample calculations are included. A method for simplifying turbulent-flow correlations is also proposed. PROPERTIES OF PSEUDOPLASTIC GENERALIZED NEWTONIAN LIQUID In contrast to the Bingham plastic the generalized Newtonian liquid is yield point-free. However, in the flow region the relation between stress and rate of shear is not linear as it is with ordinary Newtonian fluids. If the stress increases with shear rate at a less than linear rate the system is called pseudoplastic. While there is no yield point in this system, the Bingham advocates' coined the term pseudoplastic to distinguish this kind of behavior from Bingham plastic behavior. For the pseudoplastic a plot of flow rate vs friction loss or rpm vs torque, from pipe flow or rotational viscometer measurements, respectively, generally has three qualities: (1) it can be clearly extrapolated toward the origin; (2) there is very little slope at the origin. This accounts for the high apparent viscosities at low mixing and pumping rates; and (3) the flow curve possesses a continuous curvature which gradually diminishes as the shear increases. Rheological measurements on a pseudoplastic liquid can be easily misinterpreted as indicating Bingham plastic behavior. A typical case in point is illustrated in Fig. 1. These data were obtained from measurements on an oil-emulsion mud using a commercially available rotational-type viscometer (Model 35 Fann V-G meter). Applying the "two-point"* method3 gives a plastic viscosity of 17 cp and a yield point of 24 lb/100 ft2; at the same time weighting material settles very easily in this system. This illustrates that it is not possible to distinguish between the pseudoplastic and the Bingham plastic from only two data points. It is possible to determine qualitatively which model is more appropriate by a combination of dynamic and static measurements. Experience indicates that the simplest criterion for the Bingham plastic liquid is that the calculated dynamic yield point should be of the same magnitude as the measured gel strengths. For the oil-emulsion drilling fluid illustrated in Fig. 1, a value of 4 lb/100 ft2 was obtained for gel strengths measured

By A. M. Khan, I. Fatt

A new type of steady-state thermal conductivity apparatus is presented and described. Results of measurements on Berea sandstone, Solehofen limestone, Bandera sandstone and Bakelite are presented. The measurements were made in a two-hour period at temperatures up to 80C and axial stress to 125 bars. Results show that the thermoelectric heat pump and tbermistor-controlled electric heater can be used in a steady-state apparatus for measuring thermal conductivity of mck. Steady-state is reached within two hours. With Urethane foam insulation, not more than 3 per cent of heat is lost by radial flaw. The apparatus can be used as a comparator or for absolute thermal conductivity determinations. INTRODUCTION Calculations of heat flow through the earth, both for scientific purposes and engineering design, require thermal-conductivity data on rock. However, the high variability of rock often makes handbook thermal-conductivity data of little value. For engineering purposes in particular, it is desirable to have measured data on samples of the rock mass under study. Laboratory methods for measuring thermal conductivity of rock use either time-dependent1-3 or steady - state temperatures .4,5 The time -dependent (transient) techniques give thermal diffusivity from which thermal conductivity can be calculated if the specific heat and density of the sample is known. Most transient techniques require lengthy and involved sample preparation. Also, the accuracy tends to be low. Steady-state techniques are more exact and are the most commonly used. The steady-state methods, however, also have their difficulties. A long time is often required to reach steady state, troubles have been encountered in establishing good thermal contact between the heating and cooling elements and the rock sample, and unaccounted-for heat losses are difficult to prevent. In this paper we present a description of a new type of steady-state thermal conductivity apparatus. With it, measurements have been made in two hours at temperatures up to 80C and axial stress to 125 bars. Sample preparation is simple and no thermal conductivity standard is needed.6 APPARATUS Our steady-state apparatus is an improvement . over the conduction pile used by Zierfuss and van der vliet4 and Somerton.5 A linear heat flux is established through a conduction pile consisting of the rock sample and a standard material of known thermal conductivity in series. The thermal conductivity of the sample is calculated from the ratio of the temperature drop across the sample

Jan 1, 1966