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By Shuai-Jun Li, Xia-Ting Feng, Xian-Jie Hao

"The anisotropy of rock is of great importance to the rock engineering. To investigate the anisotropic character of slate, the rock samples of slate under different confining pressures and bedding plane angles was conducted on the MTS. The results indicated that the relationship between bedding plane angle and elasticity modulus, friction angle, cohesion and strength was shown as U pattern. The minimum value of them is located from 30°to 45°.In addition, the elasticity modulus and Poisson's ratio increase with the increasing confining pressure. The slate behaves brittle failure both in the uniaxial and triaxial compression. The failure pattern of uniaxial compression is generally tension failure, and triaxial test usually shows shear failure. The failure angle decrease with the increasing of confining pressure.INTRODUCTIONThe anisotropy of rock is that loading in different orientations the rock has different mechanical properties. The anisotropic property of rock is always an important problem in rock engineering (Hoek E. & Brown E. T., 1980). J. C. Jaeger (1960) first presented that transverse strength criterion for sliding fracture on joint surface. Later he revised rock parameters to anisotropy empirically for isotropic Mohr- Coulomb criterion. His main idea is revising cohesion according to loading direction (J. C. Jaeger, 1971). Then, many scholars study a lot on transverse strength criterion. E. Z. Lajtai (1969) considered the influence of connecting rate in all directions in joint groups for shear strength in intact rock; R. Mclamore and K. E. Gray (1967) referenced the theory of J. C. Jaeger. They not only revised cohesion also revised friction coefficient. Y. M. Tien (2000, 2001) made further study on the influence of connecting rate in joint group to transverse strength. R. Nova (1980) studied on the variation of strength when rock specimens in triaxial pressure and complex stress paths. O. Cazacu(1998) put forwards a new anisotropic strength criterion for analyzing rock strength. S. Pietruszczak(2000) introduced fabric tensor for characterizing inner seismic structure and he built an anisotropic strength criterion containing the invariants of stress tensor and seismic fabric tensor."

Jan 1, 2015

By G. K. Livingstone

"This paper describes mining conditions in the Kaiser surface and underground coal mines in the Sparwood area of southeastern British Columbia. Mining methods are explained, major mining equipment is listed and production rates are given. Reclamation methods and results are described. Data are given on safety organization, safety practices, accident statistics, safety inspections and absenteeism. IntroductionThe coal mines of Kaiser Resources Ltd. are located in the southeast corner of British Columbia. All present mining is in the Sparwood area, where operations began in 1900 with the opening of the Michel underground mines. Production increased rapidly at first, then went through successive periods of depression and prosperity. Following are the highlights. Quantities are in clean, short tons. 1900 1910-Rapid rise in production to a peak of 512,000 tons in 1910.1911-1924-Reduced rate of production, averaging 238,000 tons per year, due to strikes, manpower shortage during World War 1 and post-war depression.1925-1929-Second prosperous era, with production climbing to 383,000 in 1929.1930-1933-Second depression-production falling to 231,000 in 1933.1934-1942-Third era of prosperity-production recovered and new production peak of 908,000 tons reached in 1942 during World War II.1943-1956-Corttinued prosperity, with production averaging 720,000 tons per year.1957-1959-Loss of markets to oil and gas; production dropping to 517,000 tons in 1959.1959-1969-Recovery due to new coal market in Japan; production climbing back to the 900,000-ton level.197D-Present-Jump in production reaching 6.6 million tons in 1975. This was the result of the purchase of the property by Kaiser Steel, who negotiated a large-volume, long-term contract with Japan, built the coal port of Westshore, reduced shipping costs by instituting unit trains, and reduced production costs by investing in large-scale mining machinery and a new preparation plant."

Jan 1, 1980

"The Schist Lake mine, owned and operated by the Hudson Bay Mining and Smelting Co., Limited, is situated on the northwest arm of Schist Lake, 4 miles southeast of Flin Flon, Manitoba.The deposit was discovered early in 1947, during a diamond drilling program exploring small copper showings along the west shore of the lake. The orebodies came to surface between the mainland and the north end of Stitt Island.Production began in August, 1954, at an initial rate of 300 tons per day. Underground workings have been carried to the 1,700-foot level, where exploration work is now being done.General GeologyRocks of the area are Precambrian lava flows, with associated pyroclastic breccias and tuffs, and related minor intrusions. Their general strike is northwest and their dip is nearly vertical. Shearing is common and is related to the activity which caused intense folding and much faulting in the area. The larger faults and the fold axes trend a few degrees west of north. The lavas are mainly andesitic but a layer of sericite-carbonate schist, which is probably derived from a fine-grained, grey quartz porphyry, occupies most of Stitt Island and extends into the mine area. It is within this layer of schist that the ore deposit occurs (Figure 1).The OrebodiesThe ore occurs as tabular to lens-shaped bodies which strike northwest, dip nearly vertically, and plunge at 60 degrees to the southeast. The ore zone is 800 feet long and has been traced for a distance of 2,000 feet along the plunge (Figure 2). The maximum length of continuous ore within this zone is 200 feet. Widths of individual ore lenses vary from a maximum of 35 feet to a minimum of 2 feet.The ore consists of three distinct types: massive sphalerite-pyrite, massive chalcopyrite-sphalerite, and disseminated chalcopyrite-pyrite. The No. 1, or eastern, orebody is predominantly massive sphalerite-pyrite. The western part of the No. 2 orebody is massive chalcopyrite-sphalerite. The disseminated ore forms the eastern part and the lower end of the No. 2 orebody. All three types of ore, with patchy distribution, are found in the smaller lenses below the 1, 100-foot level.Metallic minerals, in order of deposition, are pyrite, arsenopyrite, chalcopyrite and sphalerite, galena, enargite, and gold. Both massive types of ore exhibit banding in many places, probably as a result of the selective replacement of schist. The disseminated ore was formed as a filling of the interstices in a brittle chert rock which appears to have been crushed by the same forces which produced the schist."

Jan 1, 1949

By K. Blower

"Since there was no representative from Wesfrob Mines Limited, the information on their infra-red concentrate drying operation, which had been prepared by Mr. K. Blower, was presented by Mr, Dorland. Mr. Blower, in submitting the information, emphasized that their objectives in this operation were (a) to guarantee less than 90%, of flow-moisture in their copper concentrates and thus satisfy marine shipping regulation• and (b) to minimize capital costs, The infra-red dryers have satisfied these objectives.To control final moisture in the copper concentrate, current practice is to preheat the filter cake with steam in the disc filter hood and then conveyor-0r7 the concentrate with infra-red calrod heaters. The application of steam aids the system as follows:1) Improves vacuum pump efficiency.2) Lowers viscosity of filtrate (increased temperature},3) Preheats the cake prior to radiant heating. (150°F)The hot cake discharging from the filter ranges from 10.6 to 10.9% moisture. After radiant heating the moisture level is reduced to 8.5% - 9.7% depending on production rate. Further moisture loss occurs during conveying and transferring to the stockpile for a final shipment moisture ranging from 8.1% to 9.5%. Production rate is frail J to 5 dry short tons per hour.1) #23 Conveyor 18"" flat belt covered from filter discharge to transfer point with 7 heaters end-to-end. Drive - Reeves Vari-Speed, 31:4 ratio, type 332-10-18, class ""D"", driving through a 24:1 ratio Dodge reducer. Speed of Conveyor - 3,9 feet per minute to 19.6 feet per minute. (Speed has been established and is not changed as a rule from the present level of a1:out 15.)2) #23 Conveyor 24"" wide, 20° troughed belt covered with 21 heaters, end-to-end from loading point, Speed - Constant at 54,2 feet per minute."

Jan 1, 1972

By H. Wotruba, J. Heizmann

"The use of shotcrete is a mandatory means for rock support and therefore for safety in many underground mining operations. If shotcrete gets into the flotation feed though, it can negatively influence the flotation process. This especially occurs when sublevel stoping, cut-and-fill or room-and-pillar methods are applied because as the mining face moves on, formerly applied shotcrete layers are mined together with the ore.As shotcrete does not differ significantly from fluorspar ore in its physical properties it gets moved through the comminution process and is fed to the flotation plant like the ore. To prove the influence of shotcrete on the flotation process, a laboratory test series was conducted at the Unit of Mineral Processing (AMR) of the RWTH Aachen University. The shotcrete grade of the flotation feed was varied between 0 and 10% through addition of pure shotcrete. Flotation parameters and also reagent dosage were held constant apart from the addition of the pH regulator, which was dosed to reach a constant pH of 8 at the flotation start. Results showed that with increasing shotcrete grades in the flotation feed the fluorspar recovery as well as general mass recovery decreased. The enrichment factor of Fluorspar also decreased with increasing shotcrete grades in the feed.In an effort to eliminate the shotcrete contamination of the flotation feed, a feasibility study for use of sensor-based sorting prior to the comminution process was conducted. Rock sorting not only reduces the bad influence of shotcrete on the flotation process, but also reduces comminution costs. INTRODUCTIONShotcrete is used in underground mining on a regular basis. It is used for rock support and therefore to increase safety in the underground mining environment. In mineral processing the presence of shotcrete can cause difficulties for example in the concentration processes. In flotation the highly sensitive reagent mixtures can be disturbed by the chemical activity of shotcrete and therefore recovery rates and selectivity of the process can suffer.Shotcrete is a special form of concrete which is applied pneumatically with high velocities and is compressed by its impact energy. Since the process is especially suitable for work in difficult environments and overhead areas, it is established in underground mining for many years. Shotcrete is not only applied in pre-processing of the mines, but particularly of use for cut and fill, as well as room and pillar mining methods. There it is used to secure excavation chambers. When the mine face is secured with shotcrete and subsequently the mining continues, the applied shotcrete will automatically be mixed with the ore."

Jan 1, 2016

By Tobias Riedel, Peter Ay, University of Applied Sciences, Bianka Bade, Nicole Pausch, Bernhard Gemende, Florian Logsch, Matthias Leiker, Satyanarayana Narra, Claudia Glaser

This study focusses on the production of micro-structured agglomerates with high porosity from iron (III)-hydroxide-containing materials as adsorbent. A fractal-like structure of the agglomerates was created through a two-stage agglomeration process. Developing porous structures was necessary to increase the adsorption capacity. Various materials were used for the agglomeration experiments: i) filter cake (dry matter content 23 to 27 wt.-%); ii) FerroSorp®DGµ, a product which is already being used commercially for various applications in water cleaning. These materials in the pristine state have different characteristics such as dry matter content and particle size distribution. The desired optimised agglomerates can be achieved with the help of additives or binders, respectively. Additionally, the agglomeration process parameters play a vital role. In order to produce agglomerates with high porosity, the process was carried out in two steps. Firstly, FerroSorp®DGµ (d90 < 30 µm) was agglomerated jointly with the aforementioned filter cake in an Eirich intensive mixer (particle size range 125 µm < d90 < 500 µm). The second agglomeration step post drying was carried out in a pelletisation disc or in an Eirich intensive mixer with the addition of polymeric binders (up to particle sizes ranging from 2 to 4 mm). Agglomerates were characterised both in short and long term loading tests using phosphate as model ion. Contact times were less than 10 min, similar to practical application in percolation columns, or more than 7 days, respectively. The results show that the agglomerates produced in the two-stage pelletisation process have more advantageous properties like better accessibility of the active sites obtained by specificly influencing the particle size distribution during the two-stage pelletisation process.

Jan 1, 2016

By W. R. McQuarry, M. E. Wilson

"The structural relations of the ore deposits of the Staclacona mine are of considerable interest, for they not only illustrate the effect of a change in competence of the wall-rock, but also the effect of either the convergence together of two faults, or a change in the clip of a fault, or both of these factors, on ore deposition.The mine is in claim M.L. 1818 near the eastern end of Pelletier lake and lies about 2 miles south of the town of Rouyn. The Company was organized in 1926 to explore claims in Rouyn, Dufresnoy, and Beauchastel townships, but attention was directed mainly to those in Rouyn. Underground work began in 1928 with the sinking of the main shaft to a depth of 300 feet. Except for 1930 and 1931, the mine has been in operation continuously since that time. Production, which began in 1936, up to the end of 1946 has amounted to 1,381,422 tons of ore from which gold and silver having a total value of $7,861,860 were recovered. The average grade of the ore milled in 1946 was $6.68.GEOLOGYThe rocks in which the Stadacona ore deposits occur are mainly volcanics of the (Keewatin) Abitibi series intruded here and there by numerous dykes, sills, or masses of diorite. Single dykes of olivine diabase and lamprophyre are also present in the property and are intersected in the mine workings. The volcanic rocks are part of a wide belt of northward dipping lavas and pyroclastic rocks, having a thickness of over 16,000 feet, that extend from the east-west trending belt of Timiskaming sediments on the south northward to the Horne Creek fault and form the south limb of a large syncline. The volcanic rocks within the property consist of numerous, east-west trending, northward dipping flows of andesite and a few flows of rhyolite interbedded with rhyolite ruff and agglomerate. The angle of dip throughout most of the property is 60° to 80°N., but in the main cross-cut on the 850- and 975-foot levels stratification in rhyolite tuff was noted dipping 35°N. The tuff at this point lies above an intrusive mass of diorite and it is probable that the change in dip results from the way in which the tuff and agglomerate have been thrust aside by the intrusive."

Jan 1, 1954

By Törbjorn Naarttijärvi, Bengt Ludvig, Agne Rustan

"Falling rock is one of the major causes of serious injuries and deaths in Swedish mines. The research at the Division of Mining and Underground Construction was therefore directed toward controlled blasting in hard intense jointed rock.The project was started with an extensive literature review. Model tests with a new equivalent model material have been initiated to find ways of improving blasting techniques. The result showed that long cracks arise at the perimeter holes when there is a long time delay between adjacent holes. This led to the theoretical development of a new initiation method with ultra short delays (1,5 ms) f or controlled blasting, called ""Cutblasting"".Full-scale tests have been done at LKAB in Malmberget in hard intense jointed magnetite ore. Four different types of perimeter charges have been tested, namely: tube charges, ANFO mixed with plastic beads, detonating cord and linear shaped charges. Three types of initiation of the perimeter holes have been used, conventional (half-second delay detonators), instantaneous and ultra short ""cutblasting initiation"" (1,5 ms delay). The change in rock strength before and after blasting has been studied with bore hole periscope, vibration measurement and ocular observation of the rock surfaces.Thefull-scale tests showed that ""cutblasting"" with detonating cord in the perimeter holes gave the smallest damage to the surrounding rock. A combination of cutblasting initiation and tube charges are anticipated to give an even better result. A new method of controlled blasting using linear-shaped charges has also been tested, however, this charge type needs further development.The full- scale test also showed that the damage which can be seen on the rock surf ace is about the same for different controlled blasting methods but the not-visual-damage zone varies as much as from 0,1 to 0,7 m.A new classification system for controlled blasting regarding the damage to the surrounding rock has been devised."

Jan 1, 1985

By Staff

Introduction The Hedley mine, perhaps better known as- the Nickel Plate mine, is one of the outstanding properties of southern British Columbia. Discovered in 1898 by Woollison and Arundell, prospectors, the property was bonded in 1899 to M. K. Rodgers for the Marcus Daly Estate, of Butte, and development was started the same year. From the high grade of the ore outcrop, and its colour, due to oxidation of the arsenopyrite, it was not difficult to open up and trace the showing. The Nickel Plate ore-shoot, which apparently had been easy to follow on surface, was more difficult to trace underground. In 1903, prospecting on an adjoining property, the Sunnyside, showed commercial ore at surface, but it was only after two years&apos; work that the ore-body was defined and shipments started. From this property, $1,200,000 have been taken out. Prospecting was also carried on on the IXL, Climax, Copper Cliff, Mound, Bulldog, Exchange, Silver Plate, Gold Plate, and other properties, all of which had surface showings, but up to date only the Nickel Plate, Iron Duke, Morning, and Sunnyside have produced commercial ore. In 1904, the Bulldog looked like a very promising mine, but it failed to make good. In 1905, the Sunnyside No. 1 was in the limelight, but it also failed to make the grade. In 1906, an outcrop on the Sunnyside No. 3 looked interesting. Subsequent work. on this claim produced $840,000, and at the same time ore which yielded $400,000 was mined from the Sunnyside No. 4. In 1908, the Nickel Plate ore-body entered a lean zone and, as the diamond drill failed to give satisfactory results, the Daly Estate, after making a profit of $1,151,000, sold the property to the Hedley Gold Mining Company, Limited, for $760,000, retaining, however, a large interest.

Jan 1, 1929

By P. Henry

Hydrometal provides an adequate technology to reintroduce lost metal units into the industrial cycle, thereby saving resources and energy, while keeping the environment cleaner. Two case studies of our integrated hydrometallurgical recycling facility (Hydrométal) in Belgium are discussed.(I) Recycling of Cu-Co cement generated at the second purification step of zinc sulfate solution. (II) Recycling of lead complex materials from the lead industry.

Jan 1, 2008

By Robert B. Parsons

"The Department of Finance introduced draft amendments to the resource allowance regulations on July 23, 1992 that effectively nullify the decision in the Gulf Canada Limited case. Prior to the amendments it appeared that only ""directly"" related general and administrative, capital cost allowance and scientific research expenditures had to be deducted from resource profits. Now ancillary expenditures are required to be deducted. Consequently, the ability of taxpayers to claim the resource allowance is curtailed.IntroductionOn October 25, 1990 it was almost certain that taxable mines were going to get a break. The Federal Court-Trial Division had just decided in Gulf Canada Limited&apos;s favour to allow it to claim resource related tax benefits larger than what Revenue Canada evidently wished. Revenue Canada appealed first to the Federal Court of Appeal and then to the Supreme Court of Canada. On January 10, 1992 the Federal Court of Appeal agreed with the Federal Court decision and on July 2, 1992the Supreme Court declined to hear any further appeal. A mere three weeks later, on July 23, 1992, the Department of Finance issued draft ""clarifying"" measures to amend the calculation of the resource allowance. These measures effectively nullify the benefits that arose under the decisions of the Federal Court."

Jan 1, 1992

By P. W. A Severin

"The Sturgeon Lake deposit, a partly eroded lens of massive sulphides with an underlying sulphide stringer zone, is one of five orebodies that occur in the Sturgeon Lake area of northwestern Ontario within volcaniclastic rocks of the Archean Wabigoon Subprovince in the Superior Province of the Canadian Shield.The Sturgeon Lake Cu-Zn-Pb-A g-Au deposit was discovered in October 1970 as a result of an I.P. survey. Production from this open-pit mine began in March 1974 and continued until the ore was exhausted in March 1980.The Sturgeon Lake property is underlain by basaltic volcanics, minor amounts of mafic lapilli tuff and rhyolite volcaniclastics. A quartz crystal-bearing rhyolite occurs at the top of the felsic volcaniclastics and is ""capped"" by the Sturgeon Lake massive sulphide deposit. The felsic volcanics have been intruded by a crudely layered sill-like, carbonatized mafic intrusion. Recent work suggests that the felsic rocks that underlie the Sturgeon Lake deposit are lateral equivalents of those in the vicinity of the Mattabi Mine and are not correlative with the dacitic volcaniclastics that underlie the Lyon Lake and Creek Zone deposits. Hydrothermal processes that resulted in the formation of the Sturgeon Lake orebody have resulted in a depletion of Na2O, CaO and FeO and an increase in MgO, K2O, copper and zinc. In the vicinity of the sulphide stringer zone, the rhyolites are ""bleached"" due to silicification and sericitization. The rocks lying immediately below the massive sulphides are locally strongly chloritic.The Sturgeon Lake deposit may have formed on a top ographic high which prevented mafic flows and dacitic volcaniclastics that underlie the Lyon Lake and Creek Zone deposits from inundating the Sturgeon Lake fumarolic vent from the west. Continued or resurgent activity from the Sturgeon Lake fumarole may have resulted in the formation of the Lyon Lake and Creek Zones as more ""distal "" deposits in topographic lows. The Sturgeon Lake, Lyon Lake and Creek Zone deposits were subsequently overlain by mafic tuffs and flows."

Jan 1, 1982

By Julia Pflieger, Manfred Russ, Johannes Gediga

This paper shall show an economic feasible approach to implement Greenhouse Gas (GHG) reduction measures into the mining and metallurgy industry. The goal to improve energy consumption is directly linked to the reduction of GHG emissions and therefore directly in correlation with the economic viability. A baseline scenario of the considered reference system and of the respective reference year has to be defined, mapped and analysed. In a second step an analysis of the same operation using available and prospected Best Available Technology (BAT) processes is carried out to generate a basis for a benchmark system. The identified reduction potentials are reported and the GHG emission reductions are put into relation to the investment cost of the new process technologies / process adaption to be implemented. This economic feasibility calculation is necessary to realise a cost efficient GHG reduction roadmap implementation into the company&apos;s business operations. The GHG reduction roadmap is developed using ratios between GHG reduction and investment / operating cost to get an indication for a sequence for implementing carbon emission reductions measures.

Jan 1, 2010

By A. H. Lang

"The name Barkc:rville district is applied loosely to the gold-bearing area around the historic town of Barkerville; the first mining camp in western Canada. The region is partly in the Cariboo mining division and partly in the Quesnel mining division. It contains two producing lode gold mines; the Cariboo Gold Quartz and the Island Mountain; and numerous other deposits. The regional structural pattern is outlined in this paper; the structural details of the producing mines are described in the papers that follow.The discovery of rich placer deposits in this district in 1860 was followed by the Cariboo gold rush. Placer mining in the area flourished until 1875 and then declined as the shallow diggings were exhausted, but important operations are still active. The total placer production amounts to about $50,000,000. An extraordinary number of quartz veins outcrop in the district, but many have only a small gold content. The miners soon recognized that the placer gold must have been derived from the erosion of these veins, and some directed their attention to the possibility of quartz mining. The erection of a 4stamp mill in 1876 was the first attempt at ore reduction in British Columbia, exclusive of arrastras. Efforts to mine the Cariboo lodes on a large scale were not successful, however, until 1933, when, due to the pertinacity of F. M. Wells and to the increased price of gold, the Cariboo Gold Quartz mine commenced production, followed by the Island Mountain mine in 1934. This success led to development work at many properties in the district, but the only ones that have reached production to date are the Columbia Tungstens, where scheelite has been mined intermittently since 1937, and the Cariboo Hudson, from which gold was produced in 1938 and 1939."

Jan 1, 1954

By Julio E. Claudeville

Approaches and Lessons Learned ??Address business needs?local skills training and employment ?local procurement programs ?health and safety programs ??Ensure consultants/ advisors/ contractors apply Company standards ?especially in the field/ locally ?will not be differentiated from the Company itself

May 1, 2006

By M. Potesser

Higher prices for natural gas or oil have motivated the copper industry to reexamine the modes of oxygen and oxy-fuel burner usage at operating plants. With rising energy costs and the growing importance of environmental protection, burner usage and burner operations have become the focus of several investigations and optimization efforts. One possible approach to lower energy usage is through combustion using tonnage oxygen. When such oxygen is used, the flame temperature increases and operational efficiency is improved. As well, with the correct technology, due to the presence of lower levels of harmful substances such as NOx in the off gas, there is improved environmental performance. As regards copper production, furnaces are employed for both concentrate smelting or for melting and casting operations. The use of tonnage oxygen in concentrate burners for smelting provides for a higher thermal efficiency. For furnaces employed for melting, air-operated burners may in fact have an initial advantage because a long radiant flame is typically generated, thus providing for a higher degree of heat transmission. This paper describes the new experimental burner chamber of Messer Austria GmbH which provides for testing of the combustion of natural gas with oxygen or oxygen-enriched air and the use of special water cooling ducts that simulates a metal charge during melting, The operational effectiveness of the burner is determined from temperature and off-gas analysis data. The paper also discusses future trends in burner technologies including a new patented burner. Cu2007 - Volume III (Book 2) The Carlos Diaz Symposium ou Pyrometallurgy Edited by A.E.M. Warner, C.J. Newman, A. Vahed, D.B. George, P.J. Mackey, A. Warczok Toronto, Canada,

Jan 1, 2007

By Jacques Ouellet

Outline What is Microwave energy Investigation of transparency of 40 minerals Melting of Andesite in a MW oven Numerical modeling /Computer Simulations o FEM analysis ?? Some laboratory experiments o Particle Modelling Mw Application to Rock Breakage o A MW Rock Drill Prototype Conclusions What is Microwave energy Microwave energy is an electromagnetic wave consisting two electronic & magnetic wave traveling perpendicular to each other and transporting energy with the speed of light.

May 1, 2008

By Andreas Gaich

COMBINED 3D IMAGES _ Highly detailed 3D geometry _ Identification of fine fractures together with a general impression of the situation _ Dealing with unfavourable outcrop geometries

May 1, 2009

By D. Mraz

"In certain instances, rocks around underground excavations behave as a plastic mass. This paper offers several solutions to predicting the mode of plastic flow around cavities and designing mining pillars where plastic conditions exist.IntroductionWhen stresses around underground cavities exceed yield limits of the host rock, the material often behaves as a plastic mass. The best example of this phenomenon is the behaviour of salt rocks in deep salt and potash deposits (more than 500 m deep).However, many other soft rocks exhibit similar properties. For example, Jeremic(1) described certain types of coal yielding plastically under high pressure. Alder suggested that granulated rock behaves plastically.The object of this paper is to propose a de sign procedure for mining pillars exhibiting plastic flow due to the combination of rock properties and in-situ stresses.Prandtl(3) mathematically defined a concept of a generalized, perfectly plastic substance, not possessing the property of strain hardening (Fig. I). He had in mind, a solid with a quasi quasi-isotropic , polycrystalline structure having a well defined yield point, and he postulated that its material elements start and continue to deform plastically when the maximum shearing stress ""&apos;MAX"" reaches a sharp limit, dependent on the mean value of the sum of the major and minor principal stresses:"

Jan 1, 1984

By John (Jack) D. Young, Frank M. Wheeler

Metallurgical plants are typically large, complex facilities. Their design is a multidisciplinary activity with a wide range of inputs, based on: the business case; metallurgical and process requirements; and the main processing equipment selection. Many constraints limit what can be achieved. Appropriate phasing of the design and development, and clear go/no-go decision criteria, are critical to successful implementation of a plant design project. Risk management concepts are used as a framework for successful project development, working from the business case, through project development, to implementation and startup, paying constant attention to technology, safe design, and sustainability. 1.1 INTRODUCTION The subject of “Metallurgical Plant Design” is the design of metallurgical plant facilities in the broadest sense. Plant design represents the culmination of many multidisciplinary activities: knowledge of process metallurgy is applied to design facilities to manufacture useful, economical, metal-based products. In the field of metallurgy, plant design is often overlooked, and its unique requirements are commonly not well understood, let alone appreciated. This book is a contribution to remedying this situation. The focus is the specifics of the metals industries, because an extensive literature already exists on the general topic of plant design.

Jan 1, 2015