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By Knut H. Hubert

The GRATE-KILN System plant at Svappavaara, Sweden, was constructed for LKAB by Allis-Chalmers under a turnkey contract and commissioned in 1969. The plant was designed to produce iron ore pellets from magnetite concentrate at 6100 mtpd using imported fuel oil. It represented the state of the art for plants of its type at the time. Fuel rated capacity was attained within one week of start-up. Product quality, power usage, fuel consumption and machine wear were within warranty limits during sustained production thereafter. As operator skills improved and gas handling system reserve capability was utilized, the plant frequently produced acceptable product at up to 115% of design capacity. During the period 1969 to 1976, market demands increased for high-quality pellets while energy costs rose steadily. At the same time, important advances in the design of GRATE-KILN Systems were being made in other plants constructed by Allis-Chalmers.

Jan 1, 1980

By Dan Witkowsky

Beginning on June 11, 2007, as many as 36, kindergarten-to-grade-12 (K-12) teachers will participate in a program designed to educate them all about the mining industry. The 39th Annual A Total Concept of the Mining Industry – All About Mining, will be conducted by the Colorado Mining Association Education Foundation, Inc. (CMAEF) and the Office of Special Programs and Continuing Education (SPACE) at the Colorado School of Mines. This flagship program includes four intensive weeks at the Colorado School of Mines. During that time, more than 75 volunteer lecturers will “educate the educators” about mining and its importance to the United States and the world. During the learning process associated with obtaining a basic understanding of mining and all its aspects, the teachers will be hosted by hundreds of other industry professionals at 10 Colorado mining operations. Also visited will be a government earthquake center, a museum of mining and industry, an earth mechanics laboratory, a metallurgical research center, a metallurgical concentrator, an electric power plant and a steel mill. Questions before, during and after visits will be answered by another select group of volunteers who will travel with the teachers to the various sites.

Jan 1, 2007

By W. A. Dunkley

During the past year and a half the Western United Corporation of Aurora , Illinois , has been distributing carburetted water ges from its Lockport , Ill . , plant , to an extensive territory , under an initial pressure ranging up to 90 lb.. per sq. in . The most distant distributing point on the system is at Harvard , Ill . , about 35 miles from the plant.. The territory supplied is approximately 85 miles long and 35 miles wide , the total mileage of rains being 1223 , or approximately 24 per cent of all the gas trains in Illinois outside the city of Chicago .

Feb 1, 1923

By L. H. Michaud

An existing mining company plans to extend their surface coal mining operations in central Pennsylvania. Although the proposed site contains pyritic material, the results of the acid-base accounting for the site show an overall NP:MPA ratio of 4.26:1 for the entire site. The pyritic material is, however, associated with the lower of the three seams to? be mined. If traditional dragline mining methods were used, this would result in the acidic material being placed at the top of the spoil piles, exposing it to air and water, and therefore to the formation of Acid Mine Drainage (AMD). Further concerns are associated with the fact that the alkaline material is not distributed evenly over the mine site. In order to prevent the formation of AMD, the company has proposed to mine the area using Truck/Shovel mining methods. This technique offers a more flexible alternative for cut sequencing and for the selective placement of waste material. Working with the Department of Mineral Engineering at The Pennsylvania State University, a mine plan was developed for this site. This plan results in the layering of the alkaline and acidic spoil in order to achieve an overall net alkalinity in all spoil areas. Mining of this site should therefore not result in the formation of AMD.

Jan 1, 1994

By Dean S. Rogers

"In February 1980, Dome Mines Limited announced a $50 million expansion program which would result in a 50% increase in mill capacity from the present 1,815 tonnes per day to an eventual production rate of 2, 720 tonnes per day in the year 1984. As an integral and necessary part of this planned expansion, a new vertical production shaft, No. 8 Shaft, would be sunk from surface to a depth of 1,645 metres.Throughout the seventy-year history of mining at the Dome, gold has been found in a number of different rock types and in association with a number of different structural settings. However, the key to successfully locating ore deposits lies in the recognition of the favourable environments in which they generally occur. First and foremost, the exercise of locating the No. 8 shaft became an exercise in geological deduction based on the projection of these favourable lithologic environments.In November 1980, after detailed engineering work was completed, the total cost of the project was estimated at $75.5 million 1980 dollars or $91 million dollars allowing for inflation over a four-year construction period. These estimates include the shaft, significant replacement and alterations to the milling process, and an upgrading of the plant."

Jan 1, 1982

By Richard H. Bares

One criterion central to most definitions of reclamation is the restoration of mined lands to their original productive potential. This is often difficult to achieve on mined lands in the Northern Great Plains because of the rigorous climate (Bares 19;2) and various soil related problems including sodicity, salinity, soil permeability, low organic matter and plant nutrient deficiencies (Malakondaiah and Safaya 1982). Field study sites were established on recontotured mined areas during the early 1970's (prior to the topsoil mandate) in which several amendments were tested for their ability to improve spoil/topsoil conditions and, hence, increase plant production. Physical and chemical properties of these control (untreated) and amended spoils and topsoils have been summarized (Safaya et al. 1982). A number of grass and legume species combinations were studied. The general effects of one time (prior to seeding), single rate (approximately 100 mT ha-1) application of leonardite and/or slack coal to spoils and topsoils was the reduction of grass dry matter yields (NB 1 test site: dry matter yield (DMY) without slack was 110 g m 2 yr I ; DMY with slack was 80 g m -2 yr 1 I and the promotion of legume establishment and yield (SB test site: DMY without leonardite was 13 g m 2 yr -1; DMY with leonardite was 93 g m 2 yr 1). On South Beulah topsoil, treated with leonardite, production of weedy species was remarkably lower than that without leonardite (SB test site: DMY without leonardite was 252 g m - yr -1; DMY with leonardite was 177 g m 2 yr 1). The general effect of commercial fertilizer applied one time prior to seeding (rates ranging from 9-13-0 to 44-1 12-28 kg ha-1 of N-P-K) was to increase plant production during the first two to three years after which the effect disappeared. This effect was much more pronounced on spoils (NB I test site: DMY on spoils without fertilizer was 53 g m -2 yr -1; DMY on spoils with fertiliser was 132 gm -2 yr -1). Weedy species accounted for most of the biomas, production during the first growing season. Three of the test sites were designed to study plant production on topsoils and spoils. Establishment and production of grass species were comparatively better on topsoils (30 cm in depth) than on spoils while legumes were most successful on the soils (Center test site, 1979; DMY of grasses on topsoil was 170 g m 2 yr -1 DMY of grasses on spoils was 52 g m -2 yr -1; DMY of legumes on topsoil was 20 g m -2 yr -1; DMY of legumes on spoil was 191 g m 2 yr -1). Total plant production on topsoiled (302 m thickness) plots at the South Beulah site (DMY in 1979 of 269 g m 2 yr 1) was comparable to that of native western wheatgrass prairie (DMY of 262 g m -2 yr -1). An experiment was conducted to find out if time of planting would have any effect on establishment of grasses on spoils. It was fund that late fall seeding was superior to spring planting for establishment of wheatgrasses at NB 3 test site (Control Plot, 1975: DMY on spring-seeded was 1 g m -2 yr - 1; DMY on fall-seeded was 55 g m -2 yr -1). In general, wheatgrasses (slender, streambank, thickspike and western) yielded the most aboveground biomass of all the grass species tested; yellow sweetclover was the most successful legume. Yellow sweetclover established and was productive on both spoils and topsoils but only where competition with grasses was apparently minimal. Durar hard fescue established and thrived on topsoil but dry matter production was low compared to that of wheatgrasses. Emerald crown-vetch demonstrated a potential for growth on spoils where water conditions were adequate, whereas side-oats grama, prairie sand-reed, alkali sacaton, and bird's -foot trefoil demonstrated only sporadic success. Little bluestem did not become established at any of the test sites. Peak production of the planted species, especially grasses, was generally reached by the second week of July. Legume and weed production continued to increase into late August.

Jan 1, 1982

By Richard Dahl, Richard P. Taylor, David H. Watkinson

"Abstract - Detailed mapping of the Eastern Gabbro, Coldwell Complex, Ontario, revealed that the copper and platinum-group-element deposit on the Marathon property is confined to a coarsegrained to pegmatitic gabbro-diorite intrusion, the Two Duck Lake intrusion (TDLI). Exposed along the eastern boundary of the Coldwell Complex, the TDLI was emplaced as a sill whose orientation is slightly oblique to the general structure of the Eastern Gabbro. The TDLI has been subdivided into lower, middle and upper sub-units on the bases of lithological, textural, mineralogical, and geochemical criteria. Both border sub-units are sulfide-, base- and precious metal-enriched, and exhibit abundant evidence of host-rock assimilation. The primary mineral assemblage in the TDLI is plagioclase, olivine, clinopyroxene, Fe-Ti oxides, with accessory orthopyroxene, biotite, apatite; this primary mineral assemblage is essentially preserved in the core of the intrusion (i.e., the middle subunit). The Cu-PGE Marathon deposit, delineated mainly in the upper sub-unit of the intrusion, consists of disseminated Fe-Cu-Ni sulfides, and platinum-group-minerals derived by hydrothermal remobilization from primary magmatic sulfides. Enrichment in Cu and PGE resulted from partial replacement of original Fe-Ti oxides and pyrrhotite in the primary mineral assemblage by reaction with (a) residual magmatic fluid, and (b) fluids derived from the breakdown of host rock xenoliths and hydrothermal alteration along the lower contact of the TDLI. Résumé - La cartographie détaillée de l’Eastern Gabbro, Complexe Coldwell, en Ontario, révèle que le gisement de cuivre et éléments du groupe du platine de Marathon est confiné à une intrusion gabbro-dioritique, de grain grossier à pegmatitique, l’intrusion Two Duck Lake (TDLI). Cette intrusion s’est mise en place sous la forme d’un filon-couche légèrement discordant sur la structure de la bordure orientale de l’Eastern Gabbro. On y distingue trois sous-unités, inférieure, centrale et supérieure, sur la base de zonations lithologique, minéralogique et géochimique. Les sous-unités marginales sont enrichies en sulfures, métaux usuels et précieux, et montrent de nombreux indices d’assimilation des roches hôtes. La paragenèse minérale primaire inclut le plagioclase, l’olivine, le clinopyroxène, les oxydes ferro-titanés et accessoirement et localement, l’orthopyroxène, la biotite et l’apatite : cet assemblage est surtout préservé au coeur de l’intrusion (sous-unité centrale). Le gisement de Cu-EGP de Marathon, situé principalement dans la sous-unité supérieure, comprend une minéralisation disséminées à sulfures de fer, cuivre, nickel, et minéraux du groupe du platine, dérivés de sulfures magmatiques primaires par remobilisation hydrothermale. L’enrichissement en Cu et EGP résulte du remplacement d’oxydes ferro-titanés primaires par réaction avec des fluides tardi-magmatiques, et des fluides assimilés le long de la bordure inférieure de l’intrusion, dérivés de la fusion partielle des xénolites et de remobilisations hydrothermales."

Jan 1, 2001

It is possible to divide industrial minerals into four general categories: 1. fuels, 2. construction materials, 4. agricultural minerals, and 4. industrial minerals. It is proposed to ignore the fuels in the context of this paper and deal in general terms with the others. Mining companies have often considered getting into the industrial mineral business because they can see a resource development with good growth and consistent profits. However, many mining companies being conversant with the metallic side of the industry have spent sleepless nights determining which industrial minerals are most suited for their particular situation. Some have got into the business for the wrong reasons and wished they had never heard of it. Others have successfully adapted to the industrial minerals philosophy and now operate in both metallic and industrial mineral arenas. There is a large difference between firstly, the philosophy and secondly, the functions of being in the industrial minerals business as opposed to metallicÆs. The philosophies can be considered in parallel but it is necessary to clearly have an appreciation of the dominant influences that affect industrial minerals.

Jan 1, 1984

By William H. Waggaman

CURTAILMENT of the mineral industry as a whole undoubtedly will follow world peace, but the output of certain minerals should pursue a course well above the average on any curve of probable output projected beyond the trends exhibited through 1939. Without speculating on industrial conditions in the pending recomversion period, demand for fluorspar should be greater than before the war because of these factors, introduced by or resulting directly from military necessity: (1) Discovery and development of new deposits. (2) Improved technology in benefication. (3) New and expanded uses for fluorspar and its derivatives. The steel industry has been and continues to be the greatest consumer of fluorspar, and it wag largely to meet the wartime needs for steel that the domestic fluorspar industry has been expanded so greatly. Not only were the search for and development of new deposits of this mineral considered esstinal but the marginal nature of some of the,c- domestic deposits made it necessary to improve mineral dressinc and processing techniques to utilize them

Jan 1, 1945

By A. Eftimie, M. Stanley

The World Bank Group (WBG) believes that extractive industries can make significant contribution to sustainable development and poverty reduction, providing that environmental, social, and corporate governance issues are properly managed. The WBG recognizes that stakeholders have legitimate concerns about the impact of extractive industries, and management proposals are built around the central theme that investments and policy advice in the extractive industries should lead to poverty reduction. To help governments create appropriate policy and regulatory frameworks, this paper focuses on the linkages between overarching policies and laws and the management / governance of extractive industries at the local communities. It encourages the use of new instruments designed to help ensure that local communities benefit from extractive industries.

Jan 1, 2005

By R. N. Tempel, M. Lengke

Arsenic sulfide [orpiment, realgar, amorphous AsS and As2S3] oxidation rates were measured in mixed flow reactors at pH~2 and temperature of 25-30oC. The measured oxidation rates for arsenic sulfide solids by dissolved oxygen are in the range of 10-11 to 10-10 mole m-2 s-1 after being normalized to final surface area. The order of arsenic sulfide oxidation rates decreases at pH~2 from amorphous AsS > realgar > orpiment > amorphous As2S3. In comparison to pyrite, arsenic sulfide oxidation rates are approximately 1.5 to 15 times slower than pyrite oxidation rates at pH~2.

Jan 1, 2002

Shaft sinking through an amphibolite-granite rock mass experienced rock bursts on the shaft walls and benches. However, rock burst phenomena was exhibited only in granite, which is e1asto-brittle with ability to store strain energy caused by orogenic and man made stresses. To improve ground conditions, blasting of destressing holes at shaft corners was carried out. By this technique rock burst during shaft sinking was minimized, but not eliminated.

Jan 1, 1982

By A. B. Kinzel

IT is with sincere appreciation and a deep sense of responsibility that I accept the honor of delivering the Howe Memorial Lecture. In our time metallurgical research has delved into phenomena ever more complex in character, so that much of this work must be done by organized teams. We, of the Union Carbide and Carbon Research Laboratories and the Electro Metallurgical Co., are truly a team and the lecture which is to follow is due largely to a few of the outstanding members of that team here cited and well known to you in their own right: John Lamont, whose work deserves special recognition, Walter Crafts, William Forgeng, William Binder, Robert Fowler, and David Swan. Thus it is a fitting pleasure to accept this honor for the research institution which I represent. Henry Marion Howe was truly inspirational and his breadth of view was such that he could use either the method of rigid proof or implied mechanism to further the broad understanding. But perhaps his outstanding characteristic was his sound judgment and his ability to weigh observations. The following is replete with observations and judgment as to their implication. We would like to feel that it is the type of dissertation which Howe, himself, would have enjoyed. Chromium carbides in stainless steel have, in a sense, been a key to the progress of the stainless steel industry. Brearley's first stainless steel, containing approximately 0.30 pct C, was successful because it differed from previous Fe-Cr alloys in that the carbides were present in such amount and form as to provide the stainless and cutting properties. Again, the 12 pct Cr die steels with a carbon content of 1.5 pct or more achieved their properties by virtue of the form and distribution of the chromium carbides. In the straight chromium steels with from 12 to 25 pct Cr, chromium carbide amount and distribution are once more the determinants with respect to physical properties and corrosion resistance. In each of the cases just cited the role of the carbide is in essence similar to that of iron carbide in carbon steel and this story is so well known that we need not dwell on it. In the austenitic stainless steels, the chromium carbide plays only a minor positive role with respect to mechanical properties, and for corrosion resistance the objective is to achieve maximum homogeneity. Thus the tendency has been to ever lower the carbon and correlatively the chromium carbide content of the austenitic steels. Today stainless steels with carbon less than 0.03 pct are beginning to find their true place, and this is being aided in major degree by our Company's introduction of a new type of ferrochromium having negligible carbon. The role of carbon in these austenitic steels has long been recognized, and a truly enormous amount of research has been devoted to the subject. Much has been learned about corrosion resistance, but the attack on the problem from the point of view of carbide precipitation and the nature thereof has left much to be understood. Because of its fundamental importance to the future of stainless steels, further study of the mechanism of carbide formation in austenitic steels is of interest. In the 18-8 Cr-Ni steels, which are typical of the austenitic class of steel, carbon is soluble in the aus-tenite to the extent of approximately 0.15 pct at 1832°F (1000°C). The solubility becomes less with decreasing temperature, so that at 1652°F (900°C) the solubility limit is approximately 0.06 pct, at 1472°F (800°C) it is about 0.03 pct, and at 932°F (500°C) it is approximately 0.01 pct. Obviously this is the ideal situation for the classical precipitation phenomenon. It is true that, in a sense, 18-8 austenite resulting from annealing is in a metastable state, and the phenomenon of ferritic precipitation from this austenite should be considered. However, in a so-called fully austenitic 18-8 steel this is secondary with respect to the carbides and can be neglected. A wide variety of chromium carbides is known. Only one chromium carbide, Cr,,C,,, frequently referred to as Cr,C, has been found in unmodified low carbon 18-8 steel. This, fortunately, simplifies the study of the precipitation phenomena. For this study an A.I.S.I. type 304 stainless steel of commercial quality was selected. Analysis showed C 0.07 pct, Mn 0.49 pct, Si 0.33 pct, Ni 9.34 pct, Cr 18.91 pct, and N 0.033 pct. As expected with this composition the steel was homogeneous after annealing except for a few pools of ferrite, which were disregarded in that their location was not coincident with subsequent carbide precipitation areas. On corrosion testing the steel was normal and typical of good commercial quality. Specimens 1/2xlx4 in. were annealed and subjected to precipitation heat treatment for 100 hr at 100" temperature intervals from 1000° to 1500°F and for ten selected intervals ranging from 5 min to 64 hr at 1300°F. These blocks were then cut into small pieces for metallographic studies. The first problem

Jan 1, 1953

By J Law, S Jahanshahi, R Holmes

Iron ore is AustraliaÆs largest commodity export and is vitally important to AustraliaÆs current and future prosperity. However, while major expansions are currently in progress to satisfy demand, the industry is also undergoing major transformations. Reserves of traditional high-grade Brockman ores that have underpinned the Australian iron ore industry since its inception are slowly being depleted and alternative ore types such as Marra Mamba bedded iron deposits, Yandi and Pannawonica channel iron deposits and magnetite deposits are now being developed. However, the impurity levels in some of these alternative ores are higher and they require blending and/or upgrading as well as an advanced knowledge of their downstream processing characteristics to facilitate cost-effective utilisation by overseas customers. The research challenge is to use advanced techniques for mineral exploration, ore characterisation, mineral beneficiation, agglomeration and sustainable processing to identify and develop innovative and breakthrough options for locating, unlocking and enhancing the value of AustraliaÆs iron ore resources. Furthermore, to sustain the steel industry and hence secure the demand for iron ore, there is a growing need to enhance the environmental and business performance of the industry through reductions in wastes and emissions. Therefore, cost-effective breakthrough and enabling technologies that massively cut waste generation, CO2 emissions and water consumption are also being developed. These include the use of renewable fuels and reductants, waste heat recovery and conversion of by-product slag into a saleable substitute for Portland cement. A number of examples of recent developments in the above areas are provided in this paper.CITATION:Holmes, R, Jahanshahi, S and Law, J, 2013. Research and innovation for the iron ore to carbon steel value chain, in Proceedings Iron Ore 2013 , pp 3-6 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By Robert Stefanko

This report, rather than attempting to replace previous annual reports, supplements, and more importantly, coordinates and summarizes the entire effort. Even with such restrictions, the report is voluminous and, therefore, a decision has been made to divide it into two parts. The first volume is basically narrative and includes tabular results and analyses. The second volume is in appendix form giving detailed information. Together, they permit a logical discussion of all aspects of the project (Volume I) without cumbersome distractions but, at the same time, provide all the details to permit others to evaluate and explain the results or develop similar research programs (Volume II). The aim of the original proposal was basically to develop instruments and techniques and then make measurements of suitable power parameters, ground fault currents and ground resistance beds. With such information available, it was possible to develop a meaningful simulator which would permit investigating electrical systems and components on paper without costly trial and error procedures in the third year, a cable splice testing program was added to the project. While there were the usual delays attendant in such original research, these objectives were achieved.

Jan 1, 1973

By Tom Retka

This three volume final report summarizes the activities and conclusions of this contract. The objective of the contract was to develop noise control modifications on a retrofit basis, for auger miner coal-cutting systems. Manuals were prepared to assist mine shop personnel in retrofitting the auger miner with these noise controls. Final Report Volume I - Details all vibration and acoustical tests conducted in development of the noise controls. Final Report Volume II - Noise Control Modification Manual for the Jeffrey 100-L Auger Miner describes the various noise control modifications to the auger miner, along with fabrication procedures, cost and vendor information. Final Report Volume III - Noise Control Modification Manual for the Jeffrey 94-l Bridge Conveyor describes the various noise control modifications to the bridge conveyor, along with fabrication procedures, cost and vendor information.

Jan 1, 1978

By D Craw

Sulphur-rich minerals such as authigenic pyrite (FeS2) are commonly associated with coal mine workings. Metallic elements such as arsenic (As), copper (Cu) and zinc (Zn) are enriched in the pyrite relative to their concentrations in the surrounding environment. Exposure of pyrite and coal to air and water results in a series of oxidation and hydrolysis reactions that are commonly catalysed by species of Thiobacillus bacteria. These reactions lead to a lowering of the pH in the drainage waters (acid mine drainage, AMD) and subsequent mobilisation of trace metals in environmentally significant concentrations. This study assesses the spatial distribution of As, Zn and Cu concentration in water in relation to pH and Eh (redox potential) downstream from the tailings at the Wangaloa opencast lignite mine in southeast Otago. This mine was abandoned in the late 1980s due to a decrease in the economic viability of mining the lignite. The area is showing the characteristic symptoms of AMD, which is detrimental to the health of several Pinus radiate growing on some of the tailings. The pH of the drainage waters can get as low as 2, and in some instances, lower, but it returns to near neutral (pH 6.5) up to 200 metres down stream from the base of mine waste piles. It is well documented that the atmospheric oxidation of pyrite is catalysed microbially, causing a substantial decrease in the pH of the drainage waters. Acidification is then counteracted predominantly by natural abiotic remediation processes occurring downstream.

Jan 1, 1999

By T. J. Fee

Introduction The International Nickel Company have been pioneers in mine rescue work in Ontario. Following the fire in the Hollinger mine in the spring of 1928, the Company purchased ten self-contained oxygen breathing outfits, ten all-service gas masks, an oxygen high-pressure pump, life line, inhalator, ten cap-lamps with batteries, and a complete stock of spare and accessory parts. An instructor from the U.S. Bureau of Mines, Pittsburgh, came to the Creighton mine for one week and trained twenty men in the use and limitations of all equipment. Monthly training courses were commenced in the fall, and have continued to the present time. Of the original twenty men trained, ten are still on the Creighton mine rescue teams. In the meantime, and as an aftermath of the Hollinger fire, the Work-men's Compensation Board of Ontario and the Ontario Department of Mines established a central mine rescue station at Timmins. This was completed in the spring of 1930. It was then decided, in view of the great expansion in mine development in the Sudbury district, to build and equip a similar station to serve all the mines there, namely, Creighton, Frood, Garson, Falconbridge, Sudbury Basin, and Errington. An extensive survey was made and a central location selected opposite the Frood mine. The International Nickel Company donated a site, and the station was completed in the fall of 1930. The station is a two-storey brick building, 27 ft. by 47 ft., with a large garage adjoining it. The ground floor is used for equipment and for training the crews. On the second floor are living quarters for the superintendent and his family. The garage houses a closed truck, in which all necessary equipment can be taken to any desired point for training purposes or for actual mine rescue work, if and when necessary. The garage is also used as a gas room, where the men are trained in an irrespirable atmosphere. A gas-tight observation window between it and the training room enables the superintendent to see and direct the men undergoing training, weight exercisers and other devices being used.

Jan 1, 1935

By T Atkinson, A Cobb, R AJIington

Risk management is concerned with the whole spectrum of financial, geological, engineering, legal, governmental, social and occasionally ethnic issues, concerned with mining projects. The inherent risks in mining operations are well publicised, but new issues and hazards arrive on the scene and lake precedence, but the older risks still remain, while insurance cover may not he ‘full cover’ in the future. It has long been recognised that quantitative approaches to risk analysis can play a major role, but although these methods are capable of considerable theoretical precision, the lack of sound risk input data and experienced personnel limits the usefulness of theoretical analysis. It can, however, greatly assist in comparing cases, in identifying areas of risk and help in the investment decision process. Its major contribution to a mining project is that it imposes an investigative discipline that also assists in improving the quantitative approach to risk analysis and hence risk management. Risk analysis and risk management also requires sound common sense and major inputs from experienced geologists, mining, mechanical, electrical and mineral processing engineers. The Engineering Council, in 1992, issued a ten point code of professional practice entitled ‘Engineers and Risk Issues’ (The Engineering Council. 1992), covering our professional responsibilities, the law, our conduct, the need for a systematic approach to risk issues, the use of professional judgement, communications, risk management, evaluation of risk, our professional development in this field and the encouragement of public awareness of risk issues. This is a specific area of training perhaps long neglected by our industry and academic institutions (Atkinson. 1983).

Jan 5, 1996

By T. G. Joseph

A strain-softening constitutive relationship is introduced that describes the post-failure stress-strain curve for rock regardless of whether the rock is intact or broken. The core of this relationship is an ?apparent friction? concept that relates the post-failure apparent cohesive and frictional characteristics of the rock to the strain. The relationship can be determined for a given rock via a series of tri-axial strength tests establishing the peak strength and corresponding strain for a range of confining pressures, together with the determination of the base angle of friction via a simple tilt test. The postulates and assumptions used in deriving this relationship are verified from results of tri-axial tests on both intact and broken rock.

May 1, 2002