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By L. Li

The rock quality designation (RQD) was initially introduced by Deere (1963) for civil engineering. But, its application has been largely extended to rock mechanics and has become a fundamental parameter in geotechnical engineering (e.g., Hoek & Brown 1980; Milne et al. 1998). The success of this definition is due, in great part, to its simplicity. However, this index includes a number of limitations. Among these limitations, a critical one is associated with the arbitrarily selected threshold value (e.g., Priest & Hudson 1976). Consequently, the RQD value would vary with different threshold length for the same core. Also, using the customarily and universally adopted but very arbitrarily selected threshold value of 10 cm (for NX cores) in the assessment of RQD, the RQD values usually tend to be either high or low in most rock engineering. Some intermediate values (50%) are less frequently encountered (Harrison 1999). The original definition of RQD does not well represent the actual quality of rock masses. In this paper, an improved definition of rock quality designation (RQDc) is given.

May 1, 2009

By K. V. Konigsmann

"The results of Mr. Klymowsky's research confirm the essential role played by oxidation products in the flotation of base metal sulphides. They invite a discussion on the subject of aeration which I may open by a brief description of the development and current practice of aeration. The first installation of pre-flotation aeration in Canadian milling practice was undertaken during the years 1928 and 29 at the then new Noranda Mill. C.G. McLachlan and his collaborators demonstrated that the flotation differential between chalcopyrite and iron sulphides was enhanced by aeration in soda ash alkaline pulps. The ores treated contained more than 80 per cent sulphides. It was proposed already then that the products of mineral oxidation assisted copper and retarded iron sulphides, at least pyrrhotite flotation. The concentration of thiosulphates was used as a measure of the progress of oxidation. Several papers by C.G. McLachlan elaborate on this subject.The aerator was also used as classifier since it was held that aeration, i.e. controlled oxidation, should go hand in hand with creation of new mineral surfaces. Grinding mills and aerators were placed in closed circuit. Figure 1. This aeration was essential for successful separation at Noranda.Following the application of aeration at Noranda the technique was applied to existing mills in N.W. Quebec. Impressive improvements in concentrate grades and recoveries were obtained. It was observedthat the zinc flotation benefitted from aeration as much as the preceding copper float. In the late forties and fifties the aerator classifier was installed in new mills associated with the Noranda group. A diagrammatic sketch of the Quemont flow-sheet (figure 2) may serve as a typical example."

Jan 1, 1973

By R. J. Allan

"CANADA HAS A GREATER LAKE AREA than any other country. Discountin the Great Lakes, this fresh-water area, mainly in the Canadian Shield, is listed as approximately 300,000 sq. mi. Densities of lakes range up to 7,500 in a 5,294-sq. mi. area of the Shield, southwest of Reindeer Lake, Saskatchewan. Five areas chosen randomly from the Shield (Figure 1) contained sufficient lakes to provide samples at a density of at least one per 10 sq. mi. Regional geochemical surveys in the Appalachian area (Nova Scotia, Boyle et al., 1958; New Brunswick, Boyle et al., 1966) and in the Cordilleran area (Yukon, Gleeson, 1965) of Canada and in many other areas of the world have relied heavily on analyses of stream sediments. These surveys show that sampling of material related to the drainage system reflects the over-all trace element content of the rocks and surficial deposits in the drainage basin. In the Shield, the classic types of dendritic (and other) stream systems found elsewhere in the world are very rare. However, impeded and disorganized stream systems that abound with lakes can provide the exploration geochemist with an ideal composite drainage system sample in the form of lake sediment. This paper attempts to demonstrate the feasibility of, and review the theory and problems involved in, the use of lake sediment as a regional geochemical exploration medium. Most of the references to field examples are taken from a regional survey using lake bottom sediment as the sample medium over 1,500 sq. mi of the Coppermine basalt group and adjacent rocks (Figure 2). During this regional survey, detailed sampling of several lakes was carried out and the results are referred to at appropriate places in the text."

Jan 1, 1971

By Christoph Müller

Information exchange for mine process optimization is essential. Today, modern mining equipment uses the IREDES standard to exchange production plans and reports for easy management and storage. To gain further benefits from process optimization, a mine wide access to real-time information is needed as e.g.: The current status of a machine, operational details etc. Presently, real-time data exchange systems are developed by machine producers. Each machine producer uses its own way of gathering, managing, and storing production data. These proprietary mining processes increase the complexity of cross platform data exchange and management for mines which involves machines produced by different vendors. Casting and unifying the data requires much effort. For this purpose, ?IREDES On-line? currently is being introduced. The standard defines an open, web based method for the exchange of volatile real time machine information. Two different principles are used: Web Services for cross platform information exchange within the IT world and the optional OPC UA for use with automation and process control systems. With such a standard information from machines of different vendors may be managed by using one common platform without spending the effort for dedicated interface development. Additionally, information management and storage will become straight forward since all the data are of the same format. The IREDES On-line standard utilizes the latest IT technologies as well as the knowledge and experiences gained from the previous IREDES standard. The paper explains the benefits, the use, as well as the technical design of the standard and gives application examples from the practice.

Oct 1, 2009

By R. J. McLeod

"CONTROL STRATEGYThe Lake Dufault Division of Falconbridge Copper Limited has been concentrating a complex copper zinc ore since late 1964. An ARL X-ray on stream analyzer was installed in 1966 for process control. A Digital Equip-ment Corporation PDP8 was added in 1968 for more complete control. To improve the system the computer was exchanged for a Moded PDP-81 in 1971.The new computer is time sharing with 8K core memory and 32K disc storage. A new interface was installed to accommodate 14 X-ray streams and additional analog signals for process control. The system gave us additional capacity and flexibility to make changes in operating programs and control strategy while on line. As the computer is used for process control a modified focal language was chosen as the operating language for ease of operation. This language is more suitable for process control than for statistical work.The main components of the control system are(a) Computer(b) Interface(c) Production Control X-ray Quantometer(d) Teletype terminals(e)Reagent feeders(f) Sample SystemThe operation of the system consists in the computer selecting the various streams to be analyzed by a PCXQ Quantometer. When the flowing sample is presented to the X-ray the intensities of the various elements are read by the computer from analog to digital converter, the assays are then computed. From the tonnage and assays the computer is programmed to determine the amount of reagent added to various parts of the circuit. The computer drives the feeders via the interface for the required amount of reagent. After following a certain sequence the computer prints out the performance and control data on an ASR35 Teletype. The data is printed out approximately every seven minutes. Any des¬ired changes in the program or strategy can be made during operation via an ASR33 Teletype connected to the computer."

Jan 1, 1973

By Michael Drozd

"The operation of an activated charcoal system has five separate unit operations. These unit operations have common points for CIP, CIL and CIS system, which vary widely in application.The unit operations are:a. Absorptionb. Desorption (Stripping)c. Acid Washingd. Reactivatione. Carbon Handling (carbon transportation, sizing, dewatering, etc.)Cost optimization starts with the basic operating parameters (design philosophy) set down at the time of engineering design. These parameters undergo almost immediate change due to site specific ore requirements, throughput changes, operator requirements or reagent availability.Activated charcoal is sometimes viewed as simple, uncomplicated reagent that requires not optimization. To some extent, this statement is true, but under most circumstances, if the time necessary to optimize the use of activated charcoal is available, the effort is rewarded with significant savings. CPL-Carbon Link has embarked upon a program of supplying technical support with its activated charcoal. Several operations in the United States have undertaken to have CPL-Carbon Link do an operational survey to determine if potential savings are possible. CPL-Carbon Link has offered to do these surveys for projects that are clients or simply would like to have CPL-Carbon Link review their operation. The information accumulated by CPLCarbon Link is being used to attempt to fashion industry standards so that a common reference point can be established for activated charcoal usage."

Jan 1, 2008

By Anand Raman, Steve Dixon

"Industry practice for defining acid consumption is based on column tests. Freeport-McMoRan (FCX) has adopted a practice of leach operation using a defined pH or gpl acid in the raffinate based on the column test program. The acid consumption can be easily calculated using the leach operating parameters of SX-EW efficiency, lift height, bulk density, irrigation rate, primary leach cycle time, acid cure dose and acid concentration in the raffinate. The column leach test results and a column to heap efficiency factor are used to define the copper extraction. The maximum acid consumption will occur when zero acid is contained in the raffinate. The term Net Extracted Value (NEV) is to define the maximum extracted value relative to acid consumed.This paper presents the operating logic and method used to calculate acid consumption based on column tests and operating parameters.INTRODUCTIONIndustry practice for defining acid consumption is based on column tests. This may result in lower economic value if the tests are not designed to account for operating variables. A test program is described to assist in defining lift height and the influence of gangue on solution chemistry. A simple spreadsheet is presented that will use the leach operating parameters of SXEW efficiency, lift height, bulk density, irrigation rate, primary leach cycle time, acid cure dose and acid concentration in the raffinate to calculate the acid consumption for a proposed operation.A review of current leach operations solution chemistry will help to define acid consumption. This is recommended for all current leach operations.DISCUSSIONThe current practice at Freeport-McMoRan (FCX) is the use of column test results to define operating parameters. The monitoring of operational solution chemistry and copper production addresses any changes needed in operational parameters. This practice maximizes the value extracted from each tonne of ore leached."

Jan 1, 2008

By S. Caron, P. Radziszewski

Industrial practice in mineral processing shows that an important problem in understanding and monitoring in-mill parameters is due to the lack of fundamental knowledge and appropriate sensors. However, over the last decade, Discrete Element Method (DEM) modelling has shown an interesting potential in describing the fundamentals of grinding mill behaviour, in improving the understanding of internal grinding mill dynamics, and in developing solutions to industrial practice. With the objective of bringing this modelling technology into the concentrator control room to assist operators, this paper aims to describe the main elements needed to apply this emerging and developing technology to on-line mill performance monitoring.

Jan 1, 2004

By Don A. Toth

Until recently, the fire protection systems used to protect mining equipment were based on generically designed, off the- shelf concepts. These systems were reliant on single agent approaches and were generally comprised of a series of small twenty or thirty pound chemical canisters that would discharge their contents when triggered by thermal detection means. As the equipment grew in capacity, the logic used to increase the protection was to add more chemical canisters to the system. Hydraulic excavators and large-scale mining trucks grew dramatically in size into the 1990?s and beyond; with this growth came the increase in major losses due to fire. This was evidenced throughout this period, and continues to be of great concern today. During this presentation you will learn of the significant changes that have come about as a result of this history. Today, dual-agent products, infrared detection and unit-specific, engineered systems are the primary phrases used when discussing how to best protect this equipment from fire loss. This session is a must for anybody looking to optimally protect their equipment assets and for those looking to renew and/or secure new insurance for high value equipment in the future.

Apr 1, 2005

By R. Grimard, M. Gamache, L. -P. Bigras, P. Cohen

This paper describes a real-time fleet management system for an undergroun mine. Dispatching, routing and scheduling are handled simultaneously, taking into account the mine status, operational constraints and vehicle location information. Each assignment decision takes into account the traffic on the road segments of the mine network, whether road segments are bi-directional or uni-directional, and ensures that each LHD (load-haul-dump) vehicle arrives at loading and dumping points with the correct orientation. Such a system can be used either as a simulation tool for strategic planning or as a real-time managing and optimizing system for operations. In the simulation mode, the system can accurately estimate the impact on productivity of decisions such as the development of waiting areas (bays, sidings), or the addition (elimination) of vehicles to the fleet in operation. When used for real-time dispatching, routing and scheduling of vehicles, the system can optimize production with respect to various assignment criteria such as cycle-time minimization or deviation from a target production plan.

Jan 1, 2004

By Yannis Faitakis, Simon Bergeron

"This paper describes the implementation of model-based predictive control (MPC) on a vacuum heat exchange network at Alcan's Jonquière Complex. The plant produces alumina from bauxite ore using the Bayer Process.The MPC system was commissioned in 2000, by Alcan personnel and an Advanced Control Engineer from Matrikon. The application has achieved an uptime of about 97%.The benefits were:• Energy savings : 0.5% - live steam reduction• Reduced variation: standard deviation of key temperatures reduced by 50%• Plant throughput increase: via the automated use of surge tanks• Decreased supervision time: by plant operations• Faster and easier diagnosis of problems and plant constraintsThe benefits were higher than expected with a payback time around 12 months.The purpose of the vacuum heat exchange network is to recover energy from a hot stream (pregnant liquor) by transferring it to a cold stream (spent liquor). The system is very tightly coupled, and the main constraints of the multivariable control system are: • to control the many tank levels involved in the process (8 tanks)• to maximize the temperature of the heated streams (spent liquor)• to prevent cooled streams (pregnant liquor) from cooling to below a minimum temperatureThe system includes 9 manipulated, 14 controlled and 2 feedforward variables.The advanced control implementation runs under an expert system environment and provides added flexibility to the overall control strategy."

Jan 1, 2003

By B. S. Fee, R. R. Klimpel

"Froth flotation is the most widely used and economic means of concentrating metal sulfide ores such as those containing copper, lead, zinc, nickel, molybdenum, and pyrite. Also recoverable are other metal species that are often associated with sulfide ores such as cobalt, platinum, gold, silver, etc. Most of the initial developments made with the process of froth flotation in the early 20th century were based on the processing of metal sulfide ores. It is the relative technical and economic ease of floating metal sulfide minerals with small amounts of appropriate frothers and sulfur containing (thio) collectors that has been a major economic driving force behind the rapid expansion in the supply of metals such as copper, lead, zinc, and nickel that has occurred in the world's economy in the last 50 years. This author estimates that 1.6 billion tons of sulfide ores are processed each year (1980) in the free world based on the froth flotation process.While there has been a tendency for the quality of metal sulfide ores in any one geographic location to deteriorate over time due to mining intensity, the overall global supply of sulfide minerals is still very large. Thus, the physical supply side of sulfide ore concentrates has not been under strong technology improvement pressure with increasing metal demands. Part of this is due to the ability of capital to consistently move to new geographic locations having suitable grade sulfide ores. In these moves, the actual froth flotation technology used (including collector chemicals) has had to change little. As an illustration of this trend, of the approximately 80,000 metric tons of thio collectors used commercially (1980) in the free world, almost 98% were known and manufactured in some form 25 years ago (1). This is clearly not typical of reagent development in other process related industries. In addition, the industrial scale practice of froth flotation applied to sulfide ores has proceeded since the 1920 s with often little direct (predictive) scientific explanation due to the extreme complexity of the flotation process. Empirical testing has been a mainstay of industrial flotation reagent development and use. Even today there is often strong disagreement between researchers as to the mechanisms of chemical flotation practices that have been performed successfully at an industrial scale for many years."

Jan 1, 1987

By L. Parthasarathy, S. K. Pan, M. P. Srivastava

"Total iron ore reserves in India, as reported by the Indian Bureau of mines, are 23.6 billion tons. Hematite iron ore reserves constitute about 45 % of the total reserve. If we go by the National Steel Policy-2005 projections, India’s supply of hematite iron ore would not last more than 40 years. Laboratory investigations were carried out for the development of a process flow sheet for treating low grade as well as Banded Hematite Quartzite (BHQ) iron ore. The purpose of these investigations was to aim for better resource utilization.Beneficiation studies were conducted on samples of low grade and siliceous iron ore from the Dalli mines, a captive mine of the Bhilai Steel Plant and BHQ ore from Southern states of India. The process flowsheet, developed for upgrading of low grade iron ore, incorporates wet screening of the ore at 0.5 mm, followed by grinding of the +0.5 mm fraction to below 0.5 mm. The whole –0.5 mm fraction, after grinding, was treated in a conventional hydro-cyclone and stub cyclone followed by treatment in Wet High Intensity Magnetic Separator (WHIMS). This resulted in a concentrate product having >66% Fe content from a feed containing 55.5% Fe with an iron recovery of 48 %. The process flowsheet developed for treating BHQ ore in the laboratory resulted in an increase in iron grade in the concentrate from 43.4 to 61.3 Fe % with a yield of 51.7 % .INTRODUCTIONThe classification of Indian iron ore resources have been made compatible with United Nations Framework Classification (UNFC), which is more scientific and has been adopted in most countries in the world. Iron ore reserves and resources estimated using the UNFC classification system, as of April 01,2000 are about 12,906 million tons of hematite ore and 10,628 million tons of magnetite ore. The Indian Bureau of Mines (IBM) has given a breakdown of these reserves by designation as either lumps or fines of hematite iron ore (Table 1). The percentage of the reserves reported lumps and fines are 42 and 34% of the total reserves respectively. High grade iron ore is less than 10% of the total reserve."

Jan 1, 2008

By J. R. Gordon

I-Introduction The possibility of adapting low-temperature reduction methods to the treatment of iron ores has been suggested on numerous occasions. Papers published on the subject include, notably, Bulletin 270 of the United States Bureau of Mines on The Production of Sponge Iron, the Symposium of the American Electrochemical Society (1927) on The Gaseous Reduction of Ores and Other Metallic Compounds, and Les Procédés Actuels de Traitement Direct du Minerai de Fer, by A. Mayer (Revue de l'Industrie Minerale, Nov. 15th, 1932) (1). The present paper contains the results of an investigation of the reducibility of some Ontario ores. The concentration of these ores and of the products of reduction has also been investigated.

Jan 1, 1933

By J. M. Menacho, J. M. Reyes

"Batch and continuous regrind tests were conducted in 3 kW and 15 kW tower mill units, respectively. Single particle size classes of a chilean copper sulphide concentrate were employed in the batch tests, while a fraction of the plant stream was deviated to the continuous unit operated under different conditions.Results are interpreted in terms of the simplified grinding kinetic model energy-based and conveniently adapted to this application. Based on the above figures plus some industrial data supplied by MPSI Inc., a scale-up relationship was developed for the apparent specific rate of breakage siE, as a function of the net power draw P, i.e.siE = siE text (P/P test) 0.089This equation fit very well the available data at the three scales and its application to regrind 4400 t/day of rougher copper concentrate from 70% below 325 Tyler mesh to 95% below same mesh, involves around 30% energy-saving compared to standard ball mill for same grinding task.INTRODUCTIONImpact and abrasion-attrition breakage are two extreme mechanisms present in any grinding system in a proportion defined by specific design and operating conditions. Impact breakage is generally efficient for coarse grinding, while abrasion-attrition is adequate to produce fine particles. Efficiency of conventional tumbling mills decreases as fineness of the product increases, even though distribution of applied stresses is always much stronger than internal force distribution in the particles. On the other hand.in a vertically stirred ball mill like the tower mill, distribution of applied stresses and particle strengths are in the same order of magnitude, making possible nearly ideal abrasion conditions (1).Tower mill configuration includes a cylindrical body vertically mounted and provided with a central screw with flights to produce circulation of balls moved up through the inner region to return down by the external space. Fresh material can be fed into the top , center or bottom in order to assure appropriate agitation of suspended particles. Size reduction and evacuation rates should compensate settling of coarse particles to avoid sanding of the screw. Detailed description of the tower mill and its operation have been given elsewhere (2),(3)."

Jan 1, 1989

By C. O. Aksoy

There is a long history of coal production in Turkey with electric energy generated from power plants since the 1950s. However, the cost of power generation is high. Therefore, it has become necessary to find a means of decreasing production costs to become more competitive in a global market. This paper attempts to economically minimize the overall operating costs of a dragline-shovel-truck system applied at an open pit mine that has fed the Yatagan power plant since 1979, lowering the lignite production cost, and indirectly, the overall electricity generation unit cost. Systems currently in place, as a result of former optimization studies, are time-consuming and expensive to re-implement to comply with today’s very different geometric and economic conditions affecting mining operations. In such cases, rather than re-optimization, it is more viable to identify the parameters that affect the minimum unit cost, via a cost minimization study, allowing present mine equipment to be utilized more efficiently. Unit cost minimization analyses are subject to the capacity of the pool of mining equipment available, combined with the mining block geometry from pre-stripping onwards. In this overall unit cost minimization study, P&H shovels and CAT 777 trucks with capacities of 15 yd3 and 77 tons, respectively, were used in truck-shovel pre-stripping operations. A 65 yd3 Marion 8050 dragline was used to expose the overburden immediately over the coal seam. Pre-stripping bench heights varied from 8 m to 20 m and dragline bench heights from 20 m and 25 m were evaluated to minimize the unit cost of field operations. Total overburden extended to a depth of 60 m (35 m to 40 m for pre-stripping). Minimization analyses performed on the pre-stripping truck-shovel operation, prior to dragline operations, determined that the shovel bench height should be 15 m requiring a dragline bench height of 25 m.

Jan 1, 2005

By Norman O. Lotter, Simon Yu, Tony Deng, Antonio Di Feo

"Xstrata Nickel’s Raglan operation, northern Québec, achieved paymetal recovery gains in 2007 by switching the collector from potassium amyl xanthate to sodium isobutyl xanthate. To follow on from that position, Xstrata Process Support (XPS) and A. Di Feo of Raglan proposed that a mixed xanthate system be formulated and tested towards further performance gains. This work selected ethyl and isobutyl xanthates as the candidates. An optimized ratio of these was to be determined by a designed experiment. This suggestion was based on an abundance of published literature that reported mixed collector systems outperformed single ones. A partial factorial design was used to configure four test conditions and a mid-square for the flotation work. The testwork was conducted using High Confidence Flotation Testing. The raw data were analyzed and modelled by Design-Expert software. An optimum ratio of 1.6:1.0 by mass (1.32:1.0 in molar terms) of isobutyl:ethyl xanthate was determined. Without this modelling, the optimum ratio would have been missed. Results obtained with the new baseline flotation test using this optimized mixture showed a 3.3% Ni recovery gain in the bypass concentrate and more than 1% recovery gain for PGM over the single PIBX system. This system has been proposed for and accepted as a plant scale trial in the first half of 2010.INTRODUCTIONConcentrator OperationsMilling and flotation of sulphide ores ahead of smelting and refining is a common practice. This choice results in the larger and more variable paymetal loss in the production of saleable metal [Cramer, 2001]. For this reason, it is common to see an ongoing performance improvement programme at the operations level. When successfully performed, these e"

Jan 1, 2010

By A. C. T. Bigg

"The mineral potential of the Nanisivik area was discovered as far back as 1910 when a prospector of the Geological Survey of Canada, on an expedition under Captain J. G.Bernier, recorded a deposit of pyrite with minor sphalerite and galena. An outcrop of the present orebody was discovered by Texas Gulf Company in 1957. Subsequent drilling outlined the orebody consisting of 6,000,000 tonnes of ore containing 13 % Zinc and 1.5 % Lead. The orebody appears to have been formed by the filling of a limestone cavern with sulphides. The sulphide minerals consist of pyrite, sphalerite and galena. The limestone bedrock is mostly dolomite with some calcite and magnesite. A cutoff grade of about 6% Zinc has been calculated.In 1972 Mineral Resources International Limited took an option on the property. Upon completion of the feasibility study by Watts, Griffiths and McOuat, the then new independent project management group of Strathcona Mineral Services Ltd. were engaged to develop the project through the financing, construction and operating phases. Strathcona Mineral Services still manage the project from their head office in Toronto and through the Mine Manager and Department Superintendents at the Mine site. The interest for the project is presently split five ways: Mineral Resources International Ltd. 53.5 %, Government of Canada 18 %, Metallgesellschaft A.G. of Germany 11.25 %, Billiton B. V. of Holland 11.25 % and Texas Gulf Co. 6 %."

Jan 1, 1980

By Victor Dolmage

Introduction Although gold production in British Columbia began in 1859, lode gold was not produced till 1893. Since 1900, the annual production of lode gold has fluctuated between $3,000,000 and $6,000,000. About twenty per cent of this production may be regarded as by-product gold from base metal mining. The remainder comes from a few isolated but important mines, such as the Rossland mines, Nickel Plate, Surf Inlet, Premier, Pioneer, Bralorne, Reno, and Cariboo Gold Quartz, and from several less important mines. All of the above, except Pioneer, Bralorne, Reno, and Cariboo, are approaching or have reached the point of exhaustion, but all are now receiving, under the stimulus of the. present gold-mining boom, drastic resuscitative treatment, with, in some cases, signs of resurrection. Notwithstanding this, however, the main interest at the present time is focussed on the Bridge River and Cariboo fields. Both these fields were discovered in the early 'sixties' and, apart from the Cariboo placer production, both have from time to time contributed small amounts of lode gold; but it is only during the last two years that the real possibilities of these areas were discovered. and that they began to assume the appearance of goldfields of major importance. The two fields are sorme three hundred miles distant from one another and contain deposits of distinctly different types, so that the only reason for including them in one article is the fact that they came into prominence more or less simultaneously and at a time coinciding with, but not otherwise related to, the present gold-mining boom.

Jan 1, 1934

By Xie Qiang

It is known that the stress state inside rock discs under Brazilian tests is neither simple compression nor tension, but a complex combination of both stress types, as well as for a beam subjected to bending, where compressive and tensile stresses are separated by the neutral axis. In this study, AE generation was obtained on pure white marbles from south Portugal that were submitted to both Brazilian and bending tests. Main questions to be answered were: (1) Does Kaiser effect exist in tests which create complex distributions of tension and compression? (2) Are there any meaningful differences in AE behavior of marble under Brazilian and bending tests?

May 1, 2009