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By D. Norval

Keywords: Pyrometallurgy, slag, metal, entrained, granulation, ferromanganese Water granulation of certain slags with high metal entrainment has customarily not been practised, not only due to the belief that such processes are too dangerous and unproven in the pyrometallurgical industry, but also that it might not be economically viable or environmentally acceptable. General slag granulation, on the other hand, is extensively applied, although in some cases crudely, with disastrous effects, as a result of not recognising the high heat capacities prevalent in slags. Thus, purpose-designed granulation and solidification processes are discussed, taking into account specific applications and the individual signatures of alloys and slags, emphasising that no slag, matte, or alloy responds in similar fashion to a granulation practice. This paper addresses three issues, namely: ? Water-granulation of BOF steel slag, without processing it to render it environmentally safe, physically and chemically acceptable for use by the construction industry, and the process economical ? Processing air-cooled BOF steel slag to change its physical and chemical properties to be acceptable for various uses and extracting metallic and bound iron ? Processing air-cooled or molten manganese slag to lower its manganese content to a level that is acceptable from an environmental and health point of view, and extracting FeMn-alloy of acceptable composition. The latter process culminated in a patented process to extract FeMn from air-cooled and molten manganese slag, and, at the same time, produce a hydraulic (cementitious) slag, thus transforming a possible hazardous by-product into virtually 100% saleable products.

Jan 1, 2011

With the increased variability of today's large-scale mining operations, consistent flotation performance is important to improving and sustaining overall recovery through the circuit. The Newcrest Telfer Mine has implemented advanced process control technology to obtain stable level operation and consistent mass pull in the copper rougher and scavenger flotation circuits. The final result has been an overall reduction in variability, which impacts on both copper and gold recovery. This paper describes the methodology and implementation of the improvements in control at the Newcrest Telfer Mine as being an essential part of the business for minerals processing.

Jan 1, 2007

1. Book reviews Quantitative texture analysis, edited by H. ,}. Bunge and C. Esling. Deutsche Gesellschaft fur Metallkunde, 1982. 551 pp. Reviewer: L. 1\'1.Matthews Boundary element methods in solid mechanics by S. L. Crouch and A. M. Starfield. Reviewer: J. A. C. Diering World mineral statistics 1976-1980. Produdion,' exports,' imports, by Institute of Geological Sciences. London, Her Majesty's Stationery Office, 1983. £18.00 Reviewer: R. P. King 2. New publications Canadian mines,. perspective from 1982. Mineral Bulletin MR 197. Supply and Services Canada, Hull, Quebec K1A 059, Canada. Copper' s changing cost structure, by Commodities Research Unit Ltd (31 Mount Pleasant, London, WClX OAD, England). Petrology of metamorphic rocks, by M. Suk. New York, Elsevier, 1983. 320 pp. U.S. $68.00. Applied geomorphology, by H. Th. Verstappen. New York, Elsevier, 1983.442 pp. U.S.$95.75. Tin and its uses, no. 137, by the International Tin Research Institute. Greenford, the Institute (Fraser Road, Greenford, Middlesex UB6 7AQ, England), 1983. 3. New journals Mining Science and Technology, edited by C. 0, Brawner and B. N. Whittaker, is to be published quarterly in one volume per year by Elsevier. Aluminium, published monthly by Aluminium -Verlag GmbH, P.O. Box 1207, D-4oo0 Diisseldorf 1, F.R. Germany. DM 690.00 per annum. Rock mechanics The South African Institute of Mining and Metallurgy is to hold two schools on 'Rock Mechanics in Mine Management' at the University of the Witwatersrand, Johannesburg, from 23rd to 27th January, 1984, and from 30th January to 3rd February, 1984. The Federation of Societies of Professional Engineers The Federation of Societies of Professional Engineers (FSPE) has been a member of the World Federation of Engineering Organisations (W FEO) for many years and has regularly sent delegates to the biennial conference of that organisation. Second progress report by ASRET The Professional Engineers Joint Council was estabislhed in 1960 and initially its main fWlction was to represent the interests of engineers. Explosives technology The Center for Explosives Technology Research (CETR) has been established at the New Mexico Institute of Mining and Technology (Tech) in Socorro, New Mexico. International Tunnelling Association A conference entitled 'Ita Tunnels 1984' will be held in Caracas, Venezuela, from 2nd to 7th June, 1984. Automation The IFAC Symposium on Automation for Mineral Resource Development is to he held in Brisbane (Australia) from 9th to nth July, 1985.

Jan 1, 1983

It is a great honour to officiate at the celebration of the centenary of the South African Institute of Mining and Metalurgy. Tonight's festivities bring back happy memories of my association with South Africa's mining industry during my tenure of office as Minister of Mineral and Energy Affairs. They also remind me of the illustrious personalities who have preceded me on this podium. The Pioneers They include Sir Percy Fitzpatrick, who spoke in 1909 on the eve of the Union, General Smuts, and, on many occasions during the 1920s and 1930, Jan H. Hofmeyr. The basic issues addressed by them continue to enjoy the Institute's attention today, namely the optimal and safe exploitation of our country's mineral resources and cost-effective extraction of minerals from their ores. Translated into the Institute's key objective it reads: To initiate and give effect to the means whereby the requirements for technology and scientific knowledge if the minerals and metals section if the South African economy is satisfied.

Jan 1, 1994

By P. R. Jochens

It is interesting to note that, when the Technical Programme Committee-Mining first decided on this particular topic for a colloquium, the proposed title was different in that it used the words 'rising price of gold'. The very fact that the title was reworded to use the words 'fluctuating gold price' highlights the problem that faces the South African gold-mining industry.

Jan 1, 1981

Iron ore pellets with or without additives are commonly used as alternate charge material in both conventional and newer ironmaking processes. The performance characteristics of these pellets are normally assessed on the basis of their reducibility values, reduction strength and resistance to clustering. These properties depend mainly on the type and amount of additives and on the sintering phenomena of the pellets during firing. In the case of composite pellets (ore-coal pellets), reduction and sintering of the iron ore fines occur simultaneously. The thermodynamic and reaction mechanisms of the processes involved in the reduction of iron ore pellets with and without reductants, additives, etc., may not necessarily be identical. The reduction and sintering characteristics of pellets greatly influence the reaction mechanism and the surface morphology of the reduced pellets. The approaches in the literature to the analysis of these reduction and sintering phenomena are broadly categorized as follows: (i) empirical models, (ii) models based on kinetics, and (ill) models based on morphological changes. The relative merits and de-merits of these models are illustrated by their application to the reduction of fluxed ore-coal composite pellets. A critical analysis of the investigations that have been conducted on the reduction and sintering behaviour of such pellets is given. It is shown that, although elegant empirical models and kinetic equations have theoretical significance and can be usefully employed in elucidating the reaction mechanisms of iron ore lumps, they are sometimes not directly applicable to fluxed ore-coal composite pellets. In studies of the latter, the approach should be to correlate the morphological changes with the reduction mechanism. The paper also gives a brief account of an investigation on the reduction and sintering aspects of fluxed composite reduced iron pellets.

Jan 1, 1996

By A. W. Bryson

Electrolytic precipitation of ammonium diuranate by A. W. BRYSON. Ph.D. (Member) Continuous precipitation of ammonium diuranate from a solution of uranyl sulphate and ammonium sulphate in the cathode compartment of an electrolytic cell has been investigated. It is found that the rate of precipitation and the settling rate of the precipitate can be correlated with the current consumed per unit volume of catholyte solution. The weight fraction of uranium in the dried solid product appears to be constant over the range of operating conditions used.

Jan 9, 1975

By W. K. Brinsden

The Australian Institute of Geoscientists (AIG) held their fifth successive annual seminar at Observation City, Scarborough, in Perth on 15th November, 1990. The title of the seminar was 'Strategies for Grade Control'. The Seminar attracted 158 delegates, including 10 speakers. In addition to geoscientists, the attendees included mining engineers, metallurgists, and mining analysts. The welcoming address was given by Rob Duncan, Chairman of the Westem Australian Branch of AIG, who said there is a strong demand for this type of seminar in Western Australia (WA). It helps geoscientists to keep up with former colleagues and to keep abreast of technical developments.

Jan 1, 1991

By I. E. Teymenson, N Fedunets

Mining-metallurgical complex is the base of any economics and influences directly on practically all branches of world economics. Therefore the task of estimation and selection of investment decisions in mining industry adequate to modern market conditions and the task of decreasing multidimensional alternatives selection uncertainty are very actual. An uncertainty of investment alternatives is explained by a number of reasons, main of which are a presence of several investors types, an unstable situation on the market and an absence of evident relations between appraisal criteria used. Maximum increasing of formalization and objectivity of information technologies applied for an estimation permits to reduce the uncertainty of investment variants estimation. A number of principled innovations, allowing to solve the task of decreasing of multidimensional alternatives selection uncertainty, are introduced into the information technology of estimating and selecting investment decisions in mining-metallurgical branch, developed by us. In the article the necessity of including a cognitive model into developed selection mechanism, which allows to take into consideration inter-influences of used critera, has been grounded. Besides, the forecasting model considering interconnected time rows has been applied for increasing the world conjuncture forecast quality. Further in the article main metrics types have been characterized and application of weighted Chebyshev’s metrics as the most compromised from all studied metrics for variants selecting has been proved, and also the developed procedure of directional search of effective compromise decisions has been described. Brief characteristic of designed instrumental means of multi-criteria variants estimation and selection finalizes the article. In conclusion expedience and efficiency of using the developed information technology for reduction of multidimensional alternatives selection uncertainty have been grounded.

Jan 1, 2003

By L. Andrews

Mineralogy, traditionally associated with concentrator studies, is being increasingly applied to problems in pyrometallurgy. Such investigations commonly make use of a number of techniques, and the results are combined for a meaningful interpretation, which can lead to a successful solution for the problem. Mineralogical techniques are described for various pyrometallurgical operations. Examples are given of studies and investigations involving mineralogy in chemical-looping combustion, feed monitoring to platinum-smelting furnaces, and losses to slag in base metal and platinum smelting.

Jan 1, 2011

By D. N. Ferguson

The separation of certain minerals by electrostatic techniques can be difficult due to their similar electrical conductivity, and any technique to improve this can be useful in certain difficult separation applications. Triboelectric differences between mineral scan result in certain minerals acquiring small positive or negative charges prior to inductive electrostatic separation. By changing the polarity of inductive separation, relative changes in mineral recovery can be observed, which may be beneficial. In this brief study a JKTech mineral liberation analyser (MLA) was used to evaluate the effect of polarity change on selected minerals present in the Richards Bay Minerals deposit, and an approximate triboelectric series based on this behaviour is presented.

Jan 1, 2010

By T. J. Goff, G. M. Denton

Mintek has developed the EnviroplasTM process for the treatment of solid wastes from the metallurgical industry, especially steel plant dusts, without requiring agglomeration to produce inert slag and at the same time recover metal values such as nickel, chromium and zinc. The products that are generated in the plasma-arc process are usually a metal and a non-toxic slag, which are tapped from the furnace in liquid form. The metal is mainly composed of chromium, nickel and manganese. During the production of stainless steel between 30 and 70 kg of dust and fine waste is generated per ton of steel. Mintek has successfully processed around 1000t of AOD/EAF dust on a toll treatment basis in order to recover the contained Cr and Ni. The metal produced contained 18.5 per cent Cr, and 5.5 per cent Ni. All slag samples tested conformed to US EPA regulations for disposal. The chromium and nickel recovery to metal was 90 and 98 per cent respectively, on a once through basis i.e. no baghouse dust recycle. Slag tapping temperatures varied between 1650°C and 1750°C. The average actual energy requirement excluding furnace heatlosses of smelting steel plant dust with anthracite as reductant was 1.36MWh/ ton of dust. The total mass of feed reporting to the off-gas stream was 10 per cent. The average ZnO content of the fume was 35.5 per cent.

Jan 1, 2004

By C. Kelley

For years urethane screen surfaces have been used in a wide range of wet screening applications where openings as fine as 75 microns and coarser have been used. In dry screening operations these same urethane screen surfaces have been relegated to only the coarser separation ranging from 1.0 mm and larger. The purpose of this paper is to expose the reader to new developments in both screen surface and screening equipment technologies, which allow an end user to consider urethane screen surfaces for dry screening operations where separations as fine as 75 microns are required. These technologies allow an end user to realize the inherent advantages of urethane in wear resistance while also realizing the benefits that a high open area urethane screen surface can bring. These benefits include non-blinding characteristics and feed capacities, which rival that of traditional stainless-steel woven wire mesh screen surfaces. The paper will highlight the features of this patented urethane screen surface technology and the screening machines in conjunction with which they are used. There will also be a presentation of several case studies of commercial installations where these technologies are utilized. These case studies are from the mineral sands industry; therefore relevance to the conference is direct and not inferred. Included in the paper will also be constraints, which must be taken into account when considering urethane screen surfaces such as temperature and chemical attack. This paper will expose potential end users to a possibility of using screens to achieve extremely accurate size separations in applications where screens were previously not considered. The paper will explain and demonstrate that prior concerns of screen surface blinding, high screen surface consumption rates and large screen surface area requirements can be eliminated by proper utilization of high open area urethane screen surfaces.

Jan 1, 2007

By N. X. Feng, S. G. Zhou, X. L. Wu, J. P. Peng, Y. Z. Di

"Szaibelyite–suanite type ore is rich in magnesium oxide and boron oxide. We propose a new method to extract both metallic magnesium and valuable residues rich in boron by reduction using metallic aluminium.Thermodynamic analysis of the reactions between aluminum and MgO, Mg2B2O5, and Mg3B2O6 was carried out. The effects of CaF2 addition, temperature, mass of Al, and pellet formation pressure on the extraction of magnesium were also investigated experimentally.The results indicate that the magnesium oxide phase can be displaced from 2MgO-B2O3 and 3MgO·B2O3 by CaO in the reduction system. The reduction ratio of magnesium oxide was 38% without calcium fluoride addition, increasing to 94% with 5.1% calcium fluoride. The reduction ratio increased with increasing temperature and mass of Al. To obtain a higher reduction ratio, the reduction pellet should be formed under a reasonable pressure.IntroductionBoron and its compounds are widely used in textiles, borosilicate glass, metallurgy, fertilizers, and nuclear shielding. Boron resources are mainly found in Turkey, the USA, Russia, and China. In Liaoning, China, there are abundant szaibelyite–suanite type ores that are rich in magnesium oxide and boron oxide. Szaibelyite and suanite ores are used to produce borax by a carbon dioxide– soda process. Annually, 2 Mt of waste materials containing 3–20% B2O3 and 2–25% MgO are produced during the process. It is necessary to make use of these waste materials containing high concentrations of boron oxide and magnesium oxide to avoid environmental problems as well as for economic reasons (Ozdemir and K1pcak, 2007)"

Jan 1, 2016

By A. Ndibalema

Blasting is one of the primary functions in any mining operation. Despite the fact that it generally constitutes between 30% to 40% of the mining cost, blasting also affects the cost-effectiveness of down steam activities such as load and haul, safety, tyre life for haul trucks, crushing and milling. Over the past three decades, significant progress has been made in the development of new technology in an attempt to reduce costs and increase efficiencies and productivities of blasting activities. Mine to mill project concepts have paved the way for such developments. Other advancements have included sophisticated computer modelling technologies for blast design and performance analysis. There are many factors that affect the cost of blasting. These can be divided into two categories; controllable and uncontrollable. The latter includes costs related to depreciation, exchange rates and government legislation with the former category including contractor versus owner blasting costs, efficiency and productivity issues and product quality. Controllable factors have one common denominator which can determine their outcome; direct site management influence. Excavator digging rates and final floor conditions give a good measure of blasting performance, and alternatively cost effectiveness. This paper is aimed at benchmarking against a blast optimisation database, understanding the relationship between costs and identifying opportunities for improvement. Understanding the cost drivers allowed a typical cost model to be developed for the current mining operation at Geita and this was used to drive continuous improvement with emphasis on closing the information loop.

Jan 1, 2008

By G. M. Brown, B. J. Ebacher, W. G. Koellner

Introduction There is a continual economic push to increase the productivity of mobile material handling equipment used in open pit mines. This includes the largest electrical machines: excavators (draglines and shovels) and haul trucks (Figure 1). Existing DC drive systems used on this type of equipment are a mature technology. They have no further economic potential to accommodate larger equipment be-cause of the high maintenance costs and the trade-off between power, speed and space limitations of their DC traction mo-tors. In recent years the large-scale introduction of AC drives in the rail transportation sector1,and the availability of poworful GTO and IGBT modules have led to the devolopment of compact, powerful, an drugged AC inverter drives specifically adapted to the mining market2,3. The major advantage of AC drives stems from the squirrel cage induction motor which eliminates the DC commutator. This leads directly to higher speed, increased power density, higher reliability, greater efficiency and lower maintenance of the traction motors. In the context of excavators and haul trucks, additional benofits driving the move to AC are (i) increased production rate due to higher machine speed, and power density, (ii) increased reliability and lower cost inverters using 3.3 kV IGBT's, (iii) active front-end (AFE) technology that improves compatibility with the mine power grid and an proved dynamic response,(iv) intelligent converter design that provides increased fault tolerance, (v) contextual maintenance software that facilitates trouble-shooting, and (vi) remote diagnostic capabilities. This paper describes how these and other features of AC drives lead to higher productivity in mining shovels, draglines, and haul trucks. Minimize the cost per ton of material moved The overall goal that drives design and sales of excavators and haul trucks is the constant requirement to reduce the cost per ton of material moved. Whether this involves blasting, loading trucks, or hauling material to the crusher or waste dump, equipment that reduces the cost per ton of material moved contributes to a more profitable operation. An accurate determination of the true cost per ton to move material must consider every aspect of the equipment and the circumstances under which it is used. Procurement and capital costs, fuel, operating, and maintenance costs over the useful life, and eventually the cost of scrapping should all be taken into account to determine the real cost per ton of moving material. We will focus on two broad areas that relate to the equipment itself; factors influencing the amount of material moved (Table I) and factors influencing the cost of material moved (Table II). Emphasis will be given to those elements in the tables that most influence the productivity of excavators and haul trucks due to the application of AC drive technology. Maximize the amount of material moved Maximize production rate he production rate refers to the quantity of material that can be loaded or moved per hour. This generally involves larger, faster, and more powerful equipment that operates more reliably to minimize down-time. AC motors Figure 2 compares the hoist motor speed-torque response of two 77 t (85 short ton) shovels, one AC the other DC. The absence of commutation limits on the AC motors enables the AC shovel to operate with a greater area under the speed-torque curve, resulting in faster lowering speeds and reduced times for the swing to return to the pit. This is especially important for short swing angles where the operator may have to wait for the dipper to lower. Reducing the cycle time by 6 to 8 seconds at the shovel translates into an increase in shovel production of about 20%. Larger equipment The bucket capacity of excavators has increased approximately 100-fold over the last century. Figure 3

Sep 1, 2001

By S. M. Brabyn

The wear in mild steel pipelines used to convey rod-milled waste backfill was determined and then compared with that obtained using a laboratory rig designed to simulate the wear condition in slurry pipelines. The relative importance of corrosion and abrasion was investigated under various conditions of water quality and particle size distribution. The laboratory rig was then used to evaluate other possible materials of construction for backfill pipelines. A preliminary assessment of the economic viability of pipelines made of alternative materials is included.

Jan 1, 1988

OFS Branch Committee Meeting held in the Committee Room at the Welkom Club at 4.15 p.m. on Wednesday, 5th March, 1975. Progress in mineral dressing The National Institute for Metallurgy and the South African Institute of Mining and Metallurgy are to hold a symposium on 17th and 18th September, 1975, entitled 'Recent Progress in Mineral Dressing'. INFACON 74 This book of over 300 pages is a record of the First International Ferro-alloys Congress, which was held in Johannesburg from 22nd to 26th April, 1974, under the auspices of the Ferro Alloy Producers' Association of South Africa, the National Institute for Metallurgy, and the South African Institute of Mining and Metallurgy. NIM reports Report no. 1595 Preliminary tests on low-grade brecciated fluorspar ore from the Ottoshoop district. (5th Nov., 1973, declassified April 1975). Report no. 1612 Flotation tests on sulphide-bearing high-grade brecciated and wad ores. (20th Mar., 1974, declasl>ified April 1975). Report no. 1643 Further tests on low-grade brecciated fluorspar ore from the Ottoshoop district. (12th Jul., 1974, declassified April 1975). Report no. 1654 The determination of osmium in platiniferous media. Report no. 1689 The determination, by atomicabsorption spectrophotometry, of arsenic, selenium, tellurium, antimony, and bismuth on ion-exchange restns. Report no. 1715 Flotation tests on various types of ore from the Ottoshoop district Report no. 1730 The chromitite from the Marico occurrence, western Transvaal, its alteration, and possible reasons for its refractory nature. Report no. 233 A chemical and mineralogical study of microlite from the N oumas pegmatite. 24th Geomechanics Colloquy The above Colloquy is to be held on 2nd and 3rd October, 1975, in the Salzburg Congress Hall. Rosenhain centenary The centenary of the birth of WaIter Rosenhain (1875-1934) will be celebrated by an international conference to consider how physical metallurgy has contributed to engineering practice. Iron and steelmaking The Centre de Recherches Metallurgiques (CRM) and the Verein Deutscher Eisenhiittenleute (VDEh) are jointly to hold the International Meeting on Iron and Steelmaking 1976 in Brussels from 17th to 18th May and in Diisseldorf from 20th to 21st May, 1976. International Symposium on Mine Surveying The III I.S.M. is being held in Leoben, Austria, from 28th June to 3rd July, 1976. Book review Tenth International Mineral Processing Congress. 1973. London, The Institution of Mining and Metallurgy. 1208 pp. £20. Particles A course on particle characterization and a symposium on experience in the applications of particlesize analysis will be held during the last week of July in Pretoria and Johannesburg. A.S. & T.S. Trust The A.S. & T.S. Trust was formed on 24th March, 1972, to mark the Golden Jubilee year ofthe Associated Scientific and Technical Societies, with the object of advancing science and technology in South Africa. Second International Congress of Engineering Geology The Proceedings of the above Congress, which was held in Sao Paulo, Brazil, from 18th to 24th August, 1974, are now available.

Jan 6, 1975

By P. H. S. W. Kulatilake

The paper introduces a computer simulation technique to estimate the target detection probabilities associated with search surveys. The technique takes into account the inherent randomness associated with the distributional properties of geologic targets. Use of the technique is illustrated through examples. The paper provides information as to how this technique can be used in obtaining the optimum sampling pattern and optimum spacing associated with target detection surveys.

Jan 1, 1987

By G. Dhakal, J. -I. Kodama, K. Neaupane, T. Yoneda

ABSTRACT Durability tests and evaluation of sub-zero temperature effects to some argillaceous clastic rocks were carried out. Welded tuff, limestone, sandstone and schist samples collected from different parts of Japan were tested and results are presented. Schist and dolomite from Ganesh Himal area along the higher Himalayas of Nepal were also tested, and the results are compared. The slaking tests were performed on all samples in pure water. The results reveal that the slaking index of schist from Japan is lower than that of schist from Nepal. Regarding carbonate rocks, the slaking index of limestone from Japan is higher than that of dolomite from Nepal. A tendency of decrease in slake durability with an increase in porosity is also observed. Freezing and thawing experiments conducted on welded tuff and schist reveal that crack initiates earlier but extends slower in schist than in welded tuff. It is also observed from the freeze-thaw experiment that the welded tuff deteriorates and wears faster than the schist. However, sandstone remains relatively intact for a long run of freeze-thaw cycles. Zusammenfassung Beständigkeitstests sowie die Bewertung der Auswirkungen von Minusgraden auf Tonschiefer Trümmergestein wurden durchgeführt. Dabei wurden geschweißter Tuff, Kalkstein, Sandstein und Schiefer aus verschiedenen Gebieten Japans sowie Schiefer und Dolomitgestein aus dem Ganesh Himal Gebiet, dem höheren Himalaya Nepals, untersucht und die Resultate verglichen. Für alle diese Gesteine wurden Slaking-Tests in reinem Wasser vorgenommen. Die Resultate zeigen, dass das Slaking von Schiefer aus Japan höher als das von Schiefer aus Nepal war, wohingegen bei kalkhaltigem Gestein das Slaking von Kalkstein aus Japan niedriger als das von Dolomitgestein aus Nepal ausfiel. Es wurde dabei auch eine Tendenz zur Löschbeständigkeitsverringerung bei gleichzeitig erhöhter Porosität beobachtet. Gefrier- und Tautests an geschweißtem Tuff und japanischem Schiefer zeigten, dass Risse in Schiefer schneller auftraten, aber sich langsamer ausweiteten als in geschweißtem Tuff. Bei Gefrier- und Tautests wurde ebenfalls beobachtet, dass geschweißter Tuff schneller verfällt und verschleißt als Schiefer. Sandstein hingegen blieb über lange Tau- und Gefrierzyklen intakt Résumé Des tests de solidités et l’évaluation de l’effet des températures en dessous de zéro sur les rocs argileux ont été effectués. Les rocs d’origine volcanique (cendre), les rocs calcaires, sableux et les schistes de différentes régions du Japon, ont été étudiés. Les schistes et les dolomites de la région de Ganesh Himal le long du haut Himalaya (Népal) ont été étudiés et comparés à ceux du Japon. Les tests de désintégration sur les rocs ont été effectués dans l’eau pure. Les résultats montrent que l’index de désintégration des schistes du Japon est inférieur aux schistes du Népal. En ce qui concerne les rocs carbonyles, l’index de désintégration des rocs calcaires du Japon est supérieur à ceux des dolomites du Népal. Une décroissance de la résistance à la durabilité est observée avec une plus grande porosité des rocs. Les tests de congélation-décongelation sur les schistes et les rocs d’origine volcanique (cendre) du Japon montrent une apparition précoce des fissures mais l’expansion des fissures est plus rapide dans les rocs volcaniques. Des tests similaires montrent que les rocs volcaniques (cendre) se désagrégent plus rapidement que les schistes. Cependant, les rocs sableux restent intacts après plusieurs cycles de congélation-décongélation.

Jan 1, 2003