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By T. N. MacAuley

"The Ingerbelle and Copper Mountain deposits are located near Princeton in southern British Columbia. They are owned by Newmont Mining Corporation's wholly owned subsidiary, Similkameen Mining Company Ltd. The property includes the Copper Mountain mine, a former producer. Ore reserves recoverable by open-pit mining are estimated to be 76 million tons containing 0.53% copper. Production commenced during 1972 at a rate in excess of designed capacity (15,000 tpd). All of the known major copper deposits in this area lie in a 14,000- by 3,500-foot belt of Triassic volcanics (Nicola Group) that is situated between a well-defined syenitemonzonite- diorite stock on the south and a variable intrusive complex on the north. The Nicola rocks consist of andesitic tuffs and agglomerates with lesser amounts of flows and some lensy siltstone layers. The orebodies are essentially disseminated sulphide deposits, although fracture-fillings are also important in many areas. Total sulphide content is usually less than 5%. At lngerbelle, and at Pit 2 and most of Pit 1 at Copper Mountain, the sulphides are chalcopyrite-pyrite. In part of Pit 1 and most of the former underground mine they are chalcopyrite-bornite. At lngerbelle the predominant alteration associated with mineralization is a pale greenish-gray bleaching of the dark andesitic rocks. This has been identified as albitization, with lesser amounts of epidote, chlorite, biotite, scapolite and calcite. This bleaching is plentiful at Pit 2, but K-feldspathization is also evident here. These orebodies can better be classified with pyrometasomatic deposits than with typical porphyry coppers. Their relationship to intrusives, the probably extensive metasomatic replacements, the evidence of pneumatolytic activity, the formation and redistribution of magnetite, and the irregular distribution of mineralization are all characteristic of this class. Deep-seated faults probably acted as channelways for mineralization; fracturing, faulting and rock contacts influenced ore localization in detail."

Jan 1, 1973

By B. Panton, J. Carvalho, E. T. Brown

"A major consideration in the design of high capacity tiedown anchors for dam, bridge and tower foundations is the tensile resistance of the rock mass to pullout, typically as a result of overturning moments or hydrostatic uplift. Rock mass pullout capacity for installed anchors is developed from the tensile strength and fracture propagation properties of intact rock, the orientation and physical properties of the discontinuities and anchor confinement at depth. The typically assumed, but generally conservative, design approach is to calculate anchor pullout capacity using the dead weight of a uniformly shaped inverted “cone” with an assumed initiation point and breakout angle. In some cases, some tensile or shear strength is considered across the area of the assumed pullout cone, however, these strength estimates are based primarily on based on limited historic testing data, empirical relationships for rock mass strength developed for other applications, and engineering judgement.As an alternative to the current foundation anchor design method, this paper presents a new approach to the rock cone pullout problem using Discrete Fracture Networks (DFN) combined with numerical simulations. The simulations presented in the paper investigate the influence of fractures in a synthetic rock mass on ultimate anchor strength. In addition, the global influence on fracture network statistics on rock mass pullout failure is also discussed and it is contended that some of the aleatory and epistemic uncertainty inherent in the design of rock anchors can be reduced by considering fracture statistics in anchor design."

Jan 1, 2015

By M. E. Hurst

SINCE 1934 there has been a marked revival of interest in the Porcupine district, especially in the eastern portion of the area, where exploration on the property of Pamour Gold Mines has indicated the presence of extensive gold-bearing deposits. Owing to the prevalence of overburden and the limited amount of exploratory work that has been done, little information is available as yet concerning the distribution and structural relationships of the rocks in the area to the east of Porcupine lake. In order to throw some light on the structural conditions in this section, a brief discussion of the sequence and character of the formations in the better known, producing section of the camp has been included. It should be emphasized that this paper is a preliminary study and that, consequently, the conclusions expressed should not be regarded as final. The writer wishes to acknowledge his indebtedness to P. C. Benedict, whose study of the geological relationships on the Foley-O'Brien property has made possible a fuller understanding of the structure in the central portion of the area. The writer also wishes to express his appreciation of the information and facilities placed at his disposal by R. M. Macaulay and C. D. Stevenson, of Pamour Gold Mines, and by A. Bell, of Noranda Mines, Limited.

Jan 1, 1936

By David A. Edgecombre

This paper discusses modern practices in the extrusion of steel. Particular emphasis is given to a description of the Ugine Sejournet method of extrusion, involving the use of glass as a hot work lubricant. Other methods are also mentioned. A brief history of extrusion is presented; present practices in the quality extrusion of tubing and solids are described; and the future potentials of the) process as a tonnage producer are briefly discussed. The advantages of extrusion and the reasons for the use of a glass lubricant, as well as the various methods of using glass, are given. The process, as described, is being used in the manufacture of large commercial quantities of stainless steel tubing and sections. This extrusion process is an essential and unique means of forming such atomic-age materials as titanium, zirconium, molybdenum and other super alloys all of which are materials required in the creation of nuclear installations.

Jan 1, 1963

By G. Reuben Yourt

IN 1935, Wright-Hargreaves Mines, Limited, initiated an enlarged programme of ventilation. In the mine, surveys were made from time to time by the geological staff, and improvements in ventilation were effected to accord with progress in mining as greater depth was attained. In the summer of 1938 an engineer was trained in the technique of dust sampling. Instruments and equipment for this purpose, such as konimeter, microscope, furnace, etc., were purchased, and a suitable office, equipped with laboratory facilities, was provided. The full time of the engineer is devoted to ventilation and dust control. On surface, in the mill crushing-plant and in the assay office and sample crushing room, an elaborate arrangement of hoods and exhaust systems has been installed to eliminate the dust. These installations, however, are not described in the present paper, which deals only with an extensive programme of underground ventilation as a method of coping with high dust concentrations, increasing temperatures and high humilities.

Jan 1, 1940

By I. Cotman

Dimensional stone processing has become an important part of the world extractive industry, and today?s total stone block yearly production is estimated to be around 134.000.000 tons and is still growing by an average yearly rate of approximately 20%. In future, the same production will become an important part of the mining industry and presently, in some countries it represents even the main mining output. New environmental regulations, together with landscape and nature conservation requirements, create a number of difficulties in setting up new open pit dimensional stone quarries. As a result, many dimensional stone producers have recently started to apply underground techniques in order to produce the ornamental stone blocks intended for further processing. Underground production of stone blocks requires special mining methods and so far it has not been a cost-effective excavation method for all types of rocks. Presently, this type of stone excavation is generally applied in sedimentary and marble deposits because the rock has small to no mineral quartz content. When starting a new underground dimensional stone mine, it is necessary to analyse the impact of all primary factors which are crucial to set up a technically and cost effective advanced underground dimensional stone mine. The role of physical and mechanical properties of the rock, geological conditions, mineralogical composition, micro-tectonic state of the site, rock mechanic conditions on the site, durability and saw ability of the stone are decisive factors in foreseeing the future methods of extraction. The laboratory research work as well as the field work, is very important in decision-making aimed to choose the future excavation method. Also of equal importance is the serious market research, because it renders the indication of selling price potential. Having obtained the results from both types of research, mining engineers can design the mining methods which optimize financial return to the mine. The practice approved by 15 years of testing in the underground limestone quarry of Kanfanar gives future producers very useful advice and general data to facilitate the process of exploration intended to establish new similar underground quarries.

Aug 1, 2013

By I. Westermann, K. Marthinsen, M. S. Remøe

"Al-Mg-Si alloys often add small additions of e.g. Mn or Cr, to form dispersoids, which may act as nucleation sites for Mg2Si particles after homogenization. The purpose is to ensure a high density of uniformly distributed small ?’-particles, which can be dissolved during further processing prior to the final age hardening step. However, their density and spatial distribution are critically dependent on the homogenization procedure. It is therefore important to have a robust and reliable method for assessing their spatial distribution. In the present work an existing methodology for assessing spatial uniformity, the Global Shannon Entropy (GSE), has been implemented and evaluated for different dispersoid structures characterized by scanning electron microscopy. This metric is highly dependent on the parameters used, but by careful selection of adequate parameters, it can be effective in detecting non-uniformity. An important weakness with the GSE was identified, and a modification to improve on the ability to differentiate degrees of non-uniformity is suggested. To evaluate the proposed methodology, the effect of heating rate on dispersoid precipitation behaviour during homogenisation of four Al-Mg-Si alloys with different Mn/Cr-content has been investigated. The metric with the new term has demonstrated promising results, and improved the ability to differentiate degrees of spatial uniformity.INTRODUCTION Al-Mg-Si series alloys are the most common aluminium extrusion alloys and are attractive for applications in a range of sectors (e.g. construction, automotive and recently also in consumer electronics), due to their generally good combination of strength, ductility and corrosion resistance. However, their extrudability and end properties depend critically on the alloy chemistry as well as prior processing conditions. Coarse ß-AlFeSi or Mg2Si-particles typically have a detrimental effect on extrudability, while small dispersoid particles may affect recrystallization, grain growth and precipitation of Mg and Si. The strengthening potential in the final age hardening step depends strongly on the amount of Mg and Si in solid solution after extrusion. The manner in which these particles are spatially distributed will decide whether the final product will exhibit uniform properties, and the number density and sizes will determine the extent of the effect. As such, these are important characteristics."

Jan 1, 2018

By John C. Robbins

A new technique for the determination of trace levels of uranium in solution has been developed. A compact laser emits short, but intense, ultraviolet pulses to excite the green fluorescence of a uranyl-complex formed by the addition of a proprietary reagent to the sample. Organic species present in most natural waters also fluoresce quite intensely, but their emission does not last appreciably longer than the excitation pulse, in contrast to the relatively long persistence of the uranyl fluorescence . Electronic 'gating' is employed to separate the long-lived contribution, rejecting substantially the organic emission. Results using the laser fluorescence method on many sets of natural waters of various origins have been compared against corresponding values generated by independent laboratories. Correlation has been generally good over a range from less than 0.1 to more than 100 ppb U. Solid samples have also been analyzed after extraction of the uranium into solution. Accuracies adequate for most exploration purposes have been achieved, but further work is required to determine effects of interferences in samples with complex matrices. The transport and deposition of uranium in natural waters is controlled by the organic and inorganic chemistry of the waters involved. It is suggested that interpretation of very low uranium levels will be aided by additional measurements of conductivity and organic content, with subsequent statistical treatment.

Jan 1, 1978

By J. Illescas, N. C. Murray

This paper provides an economic comparison and technical evaluation of different approaches for copper recovery from small-scale resources such as historic tails, dumps, pond and pit water as well as acid mine/rock drainage. Factors such as the location, the availability and cost of reagents, power availability and cost and a local market for end product alter the preferred processing technique. A number of scenarios are presented and technologies considered include; solvent extraction, ion exchange, sulphide precipitation, cementation, copper sulphate crystallization, membrane (RO) and copper cathode production.

Jan 1, 2014

By P. E. Walker, M. E. Reed, R. C. Sims, B. Snowdon, D. E. Fallas

An advanced Flash Furnace feed system is the key to improving furnace performance. Clyde-WorleyParsons has developed a revolutionary pulseless pneumatic injection feed system technology, capable of delivering a range of benefits to operators of Flash Furnaces. The solution was created by combining the pneumatic conveying and injection knowledge, expertise and technology of Clyde Materials Handling with WorleyParsons' flash furnace process and operating experience. Optimal furnace burner performance requires the feed material to be presented to the burner as a stable, pulseless and accurately controlled flow, distributed evenly around the burner tip circumference. These simple requirements appear obvious, but are extremely difficult to satisfy in industrial environments and are not achieved by conventional feed systems. Our analysis of existing operating furnaces has identified the link between pulses in concentrate feed rate caused by conventional drag chain conveyors and rapid fluctuations measured in the furnace pressure. These fluctuations occur at a timescale close to the reaction shaft residence time and lead to unwanted instability in the primary furnace reaction zone - the flame. Through the use of the solution created by Clyde-WorleyParsons, it is predicted that the much more accurate control of feed rates achieved can lead to substantial improvements in furnace output, increased oxygen efficiency and better control of the composition of furnace liquids, such as matte, blister or slag. All these improvements lead to significant increases in smelter output and efficiency, and deliver high economic value compared to the cost of the feed system. Clyde-WorleyParsons' solutions can be deployed on greenfield sites or retrofitted, and therefore, have the capability to improve feed control at both new and existing smelters. This paper will discuss the field test work undertaken to date, the impact of findings and the ongoing analysis of linkages between instabilities in the various components of conventional feed systems and furnace pressure stability.

Jan 1, 2007

By G. Clarkson, M. Hitch, R. Clarkson

"A novel reagent-free method of extracting gold from gravity middling concentrates in the Yukon placer fields is presented in this paper. This method exploits the malleability of gold by submitting concentrates to grinding in a rod mill. Brittle waste minerals are effectively reduced, whereas malleable gold particles are flattened and are then extracted by classification through sieves. Recoveries in the field using a laboratory-sized rod mill regularly exceeded 90%, whereas correlation laboratory tests indicated recovery to be most sensitive to the mill charge size. This method has broad potential, including application to the gravity circuits of large hard-rock processing circuits.RÉSUMÉ Cet article présente une nouvelle méthode sans agents réactifs d’extraction de l’or dans les concentrés gravimétriques mixtes que l’on trouve dans les districts placériens du Yukon. Cette méthode exploite la malléabilité de l’or en broyant des concentrés dans un broyeur à barres. Les déchets miniers cassants sont bien réduits, alors que les particules d’or malléables sont écrasées puis extraites par classification au travers de cribles. Si les récupérations sur le site à l’aide d’un broyeur à barres de laboratoire excèdent 90 %, les essais de concordance en laboratoire indiquent que la récupération est très sensible à la taille de la charge du broyeur. Cette méthode présente un grand potentiel, notamment une application possible aux circuits gravimétriques des grands circuits de traitement des roches dures.INTRODUCTIONExploiting the high density of gold to separate it from waste materials is the oldest known mineral processing technique. This basic technique is still widely used in gravity concentration circuits today; however, gravity processing invariably results in high-value middlings, especially in the Yukon placer gold fields. In addition to having a uniquely high density, gold is also the most malleable metal. This unique malleability can be exploited to extract gold from otherwise inaccessible gravity middlings.The Yukon placer gold industry has been continuously ongoing since the 1860s, and today produces approximately 60,000 oz t (1.87 million grams) of crude gold annually, most of which is from the Klondike region near Dawson City (Van Loon & Bond, 2014). It is important to note that Yukon placer miners do not use any chemical extraction methods; rather, gravity upgrading methods are the sole processing techniques used. Placer deposits are typically coarse, well liberated, and naturally gravity concentrated and recoverable, thus making more expensive chemical extraction unnecessary (Mitchell, Evans, & Styles, 1997). Furthermore, a strict permitting regime, environmental concerns, lack of expertise, and fear of repercussions from regulators prevent miners from attempting more advanced processing methods, such as flotation or cyanidation. Even simple chemical extractions like mercury amalgamation have not been implemented for decades, with one observer noting that, as many as 30 years ago, “the art of mercury for amalgamating appear[ed] to be dying [in the Yukon]” (Osler, 1983)."

Jan 1, 2017

By I. Donohue, M. Pearson, E. Barrette

"This paper presents the technique and benefits of the finite element approach for designing the refractory lining in pressure oxidation autoclaves. One-dimensional equations are used to develop an initial refractory design. ANSYS Parametric Design Language (APDL) scripts are then used to build and analyse a more accurate three-dimensional finite element model to verify the refractory thickness, determine weld overlay requirements, and assess mechanical stability. The APDL scripts provide a cost effective means to quickly evaluate various boundary conditions and multiple designs to determine the optimal lining configuration and nozzle layout.INTRODUCTIONNew ore processing facilities demand increased capacity, requiring hydrometallurgy processes that have larger reactor vessels operating at higher pressure and temperature. Many pressure hydrometallurgy operations require vessels with an impermeable membrane and one or more courses of refractory or ceramic brick. The membrane provides corrosion protection for the vessel shell and the brick provides thermal protection for the membrane. Designing a refractory lining with an economic service life as a thermal barrier requires the refractory to be erosion resistant, chemically compatible with the process fluid, and mechanically stable. A fundamental understanding of the factors affecting the lining system is essential as designs move further away from the industry’s experience base.During basic engineering the refractory lining design is developed using one dimensional cylindrical conduction equations for heat transfer and classical hoop stress-strain relationships for determining mechanical stability. The results of the thermal calculations specify the refractory thickness that should prevent the membrane temperature from exceeding the design limit. Mechanical stability of the lining is determined by examining the sensitivity of lining stability with respect to various parameters. There are three criteria that must be satisfied to conclude mechanical lining stability:"

Jan 1, 2012

By Jochen Petersen

This paper gives an overview of the various strands of postgraduate and undergraduate training offered in the Department of Chemical Engineering at UCT. Since 2003 the Department is offering a formal postgraduate MSc programme in hydrometallurgical engineering aimed especially at graduate work-based engineers, with 5 weeks of intensive course work plus a research dissertation on a work-related project. This programme has now run 5 times over the years and produced some 20 degrees. The paper reflects on the experiences with running the course, especially the difficulties experienced with supervising industry-based external students. Furthermore, through the Department a graduate training program is offered for all junior metallurgists at a major South African minerals company. This 2-year program, which is currently on its 12th cohort, offers 1 or 2 week intensive blocks of course work alternating with longer stints where the candidates are based at various operations. Although primarily focussed on minerals processing, it has a significant element of hydrometallurgy in it and in recent years an advanced hydrometallurgy stream has been introduced. The paper reflects on the development of the program over the years, the benefits it has provided to the company as well as some of the challenges that remain. Finally the paper gives an overview of hydrometallurgy related undergraduate and research-only postgraduate MSc and PhD projects at the university. Some emphasis is placed on the recently launched South African Minerals and Metals Research Initiative (SAMMRI), a joint government-industry programme to support university-based research in the area of applied metallurgy.

Jan 1, 2014

By G. S. Farnham

Abstract This paper lists the interests of the Physical Metallurgy and Chemical Research laboratories of the Metallgesellschaft, which were visited by the authors, members of a group of Canadian investigators sent to Germany by the Department of Reconstruction in 1945. The Physical Metallurgy Research Laboratory The following information was obtained from Professor E. Schmid, Chief of the laboratories. It is understood that Dr. Schmid is a former Nazi and was to be removed from his post in November (1945). Aluminium Research The laboratories investigated the corrosion resistance of the high-strength aluminium-magnesium-zinc alloys. The same test procedure as used by V.L.W. was followed and Dr. Schmid co-operated closely with Dr. Brenner on this project. Intercrystalline corrosion was combatted by additions of chromium, titanium, or vanadium, and the work in this field parallels that of Dr. Brenner of V.L.W. * Dr. Schmid reports that Bollenrath and Siebert believe that corrosion difficulties with these alloys can be overcome to some extent by heat treatment. He himself was of opinion that the correct answer lay not only in correct alloying but also in correct heat treatment. The heat treatment involved either interrupted quenching or a change in quenching rate from a solution temperature of 500°C. The procedure is either a slower cooling from solution temperature or an interrupted cooling with a holding period at l50°C. Work had been done on piston alloys, the 11-13% Si, 1% Ni, 1% Cu, and 1% Mg being the favoured material. This is called Lo-Ex and is similar to Mahle 124 or KS1275.

Jan 1, 1946

By J. B. Mitchell

Using digital image correlation the evolution of strain and strain at the onset of localisation resulting in a hot tear has been determined for alloys AA6111 and Al¬0.5wt% Cu during solidification. High resolution images of hot tear formation and growth were captured during a constrained bar test that incorporated a glass window above a central hot spot region. The images were analysed using digital image correlation software to measure the evolution of displacement and strain based on tracking the motion of discrete features on the as-cast surface of the sample. Temperature data was also acquired with a thermocouple cast into the sample in close proximity to the hot tear. The interval starting from the point immediately after solidification shrinkage ends (the metal pulls away from the glass) and finishing when the first sign of a crack or hot tear is visible to the eye was used to determine strain data. The minimum strain at which strain localisation occurs was found to be 0.0069 in AA6111 and 0.0021 for A1-0.5%Cu.

Jan 1, 2007

By R. B. Nourse, S. F. Gwynn-Jones, S. Nikolic, M. L. Bakker, I. McDougall, H. Joubert

"Tenova Pyromet’s core furnace knowhow and expertise has been built within the ferroalloy and nickel/platinum group metal (PGM) industries with the supply of electric furnaces for a number of nickel/PGM operators, including Eastplats, Lonmin, and Anglo-Platinum in South Africa, Mineraçào Serra Da Fortaleza in Brazil, and Norilsk Nickel in Russia. Tenova Pyromet has also supplied the electrode columns and associated electrode equipment – the heart of the electric furnace technology – for cobalt recovery in furnaces in Zambia and the Democratic Republic of the Congo. The quantity and size of projects undertaken by Tenova Pyromet has provided the opportunity to continuously improve furnace designs and the scope of supply, culminating in the most recent nickel/PGM project currently under construction at Northam Platinum. Through this innovative culture, the Tenova Pyromet Base Metals Initiative was formed in 2015 to develop the Novasmelt™ Furnace; a next generation optimised Top Submerged Lance (TSL) furnace design. The combination of Tenova Pyromet’s advanced Novasmelt™ product with our industry leading electric furnace technology are discussed with reference to applications for nickel and cobalt production. Flowsheet arrangements are compared summarising potential capital savings, operating requirements and achievement of downstream product quality.INTRODUCTION Tenova Pyromet is a leading player in the field of smelting technology development and equipment supply. Tenova Pyromet is the result of the union of three furnace suppliers under the Tenova banner: Techint Technologies (Tagliaferri), Core Furnace Systems Corp (Lectromelt) and Pyromet Technologies. The furnace experience of the combined groups dates back over a century with the earliest Lectromelt going into production in the early 1900s. Throughout the modern era, Tenova Pyromet has developed a reputation for providing dependable innovative smelting technology, high quality equipment and sound project execution to a worldwide client base with customer plants operating in Europe, Southern Africa, North America, South America, Russia, Kazakhstan, the Middle East, South Korea, and India. Tenova Pyromet’s core knowledge and expertise was developed in the South African ferroalloy, base metals, and platinum group metals (PGM) smelting industries. Tenova Pyromet has spent considerable effort on development and has contributed significantly to improve the state of the smelting industry. Tenova Pyromet’s electrode columns have become widely renowned and are now providing significant benefits, especially in increased furnace availability, to many smelting furnace operators. The electrode column is the heart of the furnace as it delivers a controlled amount of electrical energy, at an optimum depth in the burden/bath, to the smelting process. Every furnace is custom designed to the specific operating range and optimal operating point of that furnace and process"

Jan 1, 2017

By Juliana Parreira

The past decade shows record increases in global demand for minerals and metals with an accompanying significant decline in skilled personnel. Mining companies today are examining new technologies to maximize production, reduce costs, and create safer work conditions to deal with this shortfall. Automation of an open-pit mine haulage system is receiving attention as a beneficial option since it provides more consistent and efficient operation of mining equipment, it removes workers from potential danger, it reduces fuel consumption significantly reducing greenhouse gas (GHG) emissions, and it can help optimize vehicle repairs and equipment replacement because of more-predictable and better-controlled maintenance. This paper describes a simulation model under development using the EXTENDSIM software package to examine scale-up issues and constraints of autonomous vehicles in comparison to a manual system. The software can predict and manage Key Performance Indicators (KPIs), such as productivity, safety, cost, equipment failures, fuel consumption, and tire wear under different road and load conditions. By breaking-down the various systems of an autonomous haulage truck and simulating the overall haulage system using a Monte Carlo approach, the model becomes a flexible and powerful tool to use within a mining organization. Direct comparison to a manuallyrun system can be done to show the cost and operational benefits of automation. Project managers can use this tool to guide decision-making about possible application of autonomous haulage trucks at a specific mine site.

May 1, 2010

By Xiao min Zhou, Yan Xu, Hongzhen Liang, Xiaonan He

"With the increase of shaft excavation depth, the thickness of the shaft lining increases sharply. It is difficult to reduce thickness of lining effectively by improving high-strength concrete performance. The concept of the New Austrian Tunneling Method (NATM) is that surrounding rock plays a certain role in tunnel support. The solution should be to find the correct relationship between shaft lining thickness and rock strength, which is related with the interaction between the surrounding rock and concrete lining. The plane strain mechanics model is introduced to calculate lining thickness. Shaft lining design of Cixi Colliery in China is completed with the mechanics-based method proposed in this study. The lining design is verified through numerical simulation and field monitoring. The simulation results show that the maximum mises stress is located at the inner edge of the shaft lining. The increase of lining thickness cannot effectively reduce concrete grade. The monitoring results indicate that a lining design thickness of 900mm with C60 concrete, is safe and reliable in the shaft over 1000metres.This analytical design method can well be referenced in similar deep shaft projects.INTRODUCTION The New Austrian Tunneling Method (NATM), thought to have helped revolutionize the modern tunneling method, is the most extensive design philosophy and construction principle in today's tunnel engineering. It began to attract attention in the 1960s based on the work of Ladislaus von Rabcewicz, Leopold Müller, and Franz Pacher in Austria[1]. NATM was originally developed for tunneling in depth and in high situ-stress conditions in the Alps. The history of sequential excavation was reviewed, which highlights the progress of tunnel design and construction in Europe after NATM[2]. Structural conditions were introduced into the equilibrium of tunnels in NATM, and the additional force was estimated to stabilize the excavation of the tunnel[3].From the perspective of applied mechanics, there was no accuracy theory to explain the interaction between the tunnel structure and the surrounding ground. Numerical calculation is an effective means to study the basic mechanism of tunnel excavation[4].Based on two-dimensional modeling approaches in the past, such as NATM and other derivatives, a three-dimensional model was studied to"

Jan 1, 2019

By U. Storck

"Shaft sinking for exploitation of the deep potash beds in Saskatchewan involved great difficulties from the very first because of the need to exclude from the shaft the high-pressure water encountered in the overburden. Control of the troublesome Blairmore quicksands was achieved relatively quickly by use of the freezing method and by lining with cast iron tubbing. The unsolved problem remained, however, of sealing the water-bearing Devonian where the formations had extremely low permeability and were thus hard to grout. Long experience in German potash mines had shown that the permanency of the whole mine would be seriously endangered if large amounts of unsaturated salt water were allowed to flow in from the shaft wall and merely removed by pumping. The prevention of water movement and the resulting dissolution of salt in the overburden were known to be most important. In the Alwinsal shaft, water flow from the Devonian has been prevented by the use of a steel and concrete sandwich lining similar in principle to a kind of lining introduced a few years earlier, and for another reason, in German coal shafts. As its installation is neither more expensive nor more time consuming than that of cast iron tubbing lining, this same lining was also chosen as protection against the Blairmore quicksands. The great advantage of the steel lining, in addition to its relatively high strength, is the fact that it is possible to make the joints of the individual segments absolutely and permanently water-tight by means of tested welds. The virtual dryness of the Alwinsal shaft will also result in lower costs because significant corrosion of all its steel installations, including skips, cage and ropes, will be prevented."

Jan 1, 1968

By M. Pawlik, E. Arinaitwe, V. Ferrera

A series of flocculation tests were performed on dilute quartz suspensions with the use of five polyacrylamide-based flocculants of similar molecular weights but of different degrees of anionicity. The tests were performed as a function of ionic strength and pH. The macromolecular conformation of flocculants in solution was assessed through intrinsic viscosity measurements under the same physicochemical conditions as those of the flocculation tests. It was generally found that the flocculating efficiency of the polyacrylamides correlated with their ability to coil or stretch in solution. Polyacrylamides with the degrees of anionicity on the order of 10-18% showed the highest flocculating efficiency in terms of the settling rates of the flocculated solids and the residual turbidity of the resulting supernatant. At the same time, these most effective flocculants were also found to exhibit the greatest tendency to coil and stretch in solution. This result suggests that the flocculating power of a flocculant is determined not only by its ability to adsorb onto (and bridge) fine particles but also on its ability to conform to the size of the resulting floes.

Jan 1, 2009