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By S J. Neethling and, S J. R Simons

In this paper the effect of humic substances (natural surfactants), electrolytes and solid particles on bubble coalescence, and as a consequence on froth stability, have been investigated. In this study two bubbles of equal size were formed and forced to collide using a novel experimental apparatus. The interactions were recorded by a high-speed camera, the images of which helped to determine the coalescence frequency and the coalescence time, as well as the mechanisms of the interactions. Two types of humic substances were used, along with three different electrolytes. Humic substances appeared to have a considerable effect on bubble coalescence, while the effect of electrolytes was minimal. Moderate and high hydrophobic glass spheres were used between two bubbles. Very hydrophobic spheres promoted fast bubble coalescence, while moderate hydrophobic spheres had no effect. Data of coalescence frequency and time is presented, as well as images of the coalescence events. The coalescence frequency was used to validate a parameter, Pf, known as the film failure frequency, used in a simulation model to predict foam height in a gas-sparged vessel. Predictions determined using Pf were then validated by experimentation.

Jan 1, 2005

By Robert Merritt

Approximately 2,500 tons of low-grade uranium ore were used to conduct a field-scale heap leaching test as well as throe column leach tests. The ore used to construct the field-scale heap leaching test had a grade 0.023% U308 while the ore used fur column leach tests had a grade of 0.027% U308. The ore was crushed to minus 4 in. The field-scale heap was constructed on a clay base with parallel effluent lines running under the heap spaced 7.5 ft apart. The heap was leached for 45 days, drained, washed, and dismantled. Based on residue analysis, approximately 205 tons of ore were leached with a final U308 extraction of 96%. The heap was 17.9 ft in height and leached in a near-vertical pattern down to approximately 1 ft, at which point the leached zone become bell-shaped. Two 8-ft column charges and one 18-ft column charge were leached for 36 and 45 days, respectively. Based on residue analyses, all U308 extractions were greater than 96%. The conclusions generated by the studies showed that (1) flow rates were similar for column leaching and field-scale leaching, (2) final U308 extractions were the same for both types of leaching; however, the deeper ore beds tended to require longer leaching times, and (3) the reagent requirements were reduced with increased bed depth.

Jan 1, 1980

By Tatiana Salviano Gadelha

Rejeitos de mineração descartados na forma de polpa possuem, geralmente, grande quantidade de água e reutilizá-la no processo, por meio de operações de desaguamento mais eficientes é de grande importância para a implementação de projetos de menor impacto ambiental. O presente trabalho visa estudar as operações envolvidas no desaguamento de um rejeito de níquel, com o objetivo de principalmente a maximizar a recuperação de água de processo. Para tanto, foram avaliados: a influência da concentração de sólidos, uso e dosagem de floculante, pressão no filtro, o processo de filtração com e sem prensagem e a influência destas variáveis na umidade da torta e na recuperação de água. Os resultados mostraram que quanto maior a dosagem de floculante menor é a recuperação de água na filtragem; por outro lado, quanto maiores a concentração de sólidos e a pressão, maior a recuperação de água. Verificou-se a importância do uso da prensagem para maximizar a recuperação da água contida no sedimento, sendo possível comprovar que o rejeito de níquel floculado e filtrado com ?P de 6 bar com o uso de prensagem promoveu a recuperação de até 77% de água.

Aug 17, 2017

By J. A. Kosek

Work has been conducted under Bureau of Mines Contract Number HO 357078 to develop instruments for detecting CO, NO and NO2 in a mine atmosphere, using fuel cell technology. The approach has been to optimize the fuel cell sensor configuration for the specific detection of CO, NO and NO2 in the presence of other mine gases utilizing recent advances in catalyst, electrode and solid polymer electrolyte membrane technology. Para-metric testing has been conducted on three electrode sensor cells to define performance and life characteristics as a function of temperature, feed flow and applied sensor voltage. Extended life testing has been performed on sensor cell configurations exhibiting favorable characteristics. Reliable, efficient gas sampling and electronic control circuitry has been fabricated for use with the sensor cells, and integrated into devices to meet the performance and design specifications for portable, battery-powered, hand held direct indicating gas detectors for use underground. Twenty of the production-type, direct indicating CO detectors have been tested and delivered to the Bureau of Mines under the present contract. Three prototype diffusion head CO monitors have also been delivered for evaluation under the pre-sent contract. The gas sampling pump and related parts have been replaced by a diffusion tube assembly in which CO reaches the sensing electrode surface by diffusion alone. In addition, delivery will be made of ten direct-indicating nitric oxide detectors and ten direct-indicating nitrogen dioxide detectors. These instruments are very similar in design to the direct indicating CO detector.

Jan 1, 1979

By S Arai

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Podiform chromitites are commonly found in the Moho transition zone to the mantle section of ophiolites, but have been very rarely found from the current ocean floor, even though some ophiolites are considered as a slice of oceanic lithosphere. One of the factors controlling podiform chromitite formation is the chemistry of host mantle peridotite; an intermediately refractory harzburgite is the optimum host for chromitites. This harzburgite represents the most common lithology of the oceanic lithosphere, where the peridotite-melt reaction, which is another condition, is possibly common there. The oceanic lithosphere mantle is thus a good host for podiform chromitites. The apparent rarity of documented oceanic chromitites is solely due to under-sampling of mantle materials from the fast-spreading ridge and the segment centre of slow-spreading ridges. Some ophiolitic chromitites formed not from genuine mid-ocean-ridge basalt (MORB) but from wet MORB due to the situation of typical ophiolites, which formed not at ordinary mid-ocean ridges but at supra-subduction zone spreading centres.CITATION:Arai, S, 2015. Podiform chromitites do form beneath mid-ocean ridges , in Proceedings PACRIM 2015 Congress, pp 465–468 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Robert R. Walden, LeMont West

K ENTUCKY'S first acid-grade fluorspar flotation Kmill, shown in Fig. 1, was placed in operation Aug. 1, 1952, by the Pennsylvania Salt Manufacturing Co. at Mexico, Ky. During 1951 a critical shortage of acid-grade fluorspar developed and it became necessary for the company to produce part of its fluorspar requirements. In 1951 the company purchased the Crider and Lennen metallurgical fluorspar mill and an adjacent stockpile of tailing at Mexico, Ky. The tailing, assaying about 26 pct calcium fluoride, originated from log washer and jig mill concentrators in the area. As the mill did not have a fluorspar dryer or convenient rail facilities, the company leased the Burleson concentrator at Marion, Ky., where these facilities were available. At Marion, Ky., on the Illinois Central Railroad, dry acid-grade fluorspar is transported direct to the company's Calvert City, Ky., hydrofluoric acid plant. The Mexico flotation plant was reconditioned and designed to produce acid-grade fluorspar from the jig tailing stockpile. The new plant flowsheet is shown in Fig. 2. The ore feed, old tailing, which contains 10 pct of waste rock and coarse gravel assaying approximately 8 pct CaF,, is bound together by sticky clay

Jan 1, 1955

By Roger Storry, Arnaud Hochart, David Harris, Olivier Martin

"INTRODUCTIONThe Port of Miami Tunnel (POMT), designed and constructed by Bouygues Civil Works Florida between 2009 and 2014, was a Public Private Partnership between the Miami Access Tunnel Concessionaire, Florida Department of Transport, Miami-Dade County and the City of Miami. The project comprises dual 11.3m internal diameter, 1.27km long, twin lane road tunnels running between Watson and Dodge islands under the main shipping channel in Biscayne Bay. Five cross passages (CPs), spaced at 200m centre to centre, provide emergency access between the two tunnels, as shown in Figure 1.The CPs were constructed by open-face excavation methods but the particular geological conditions at the project site (loose and variable carbonate sedimentary strata with very high permeability) required specific ground treatment solutions to provide safe excavation conditions and to ensure the long term serviceability of the permanent works construction. Where access allowed, ground treatment was performed from the ground surface using deep-mixing techniques; however, at two locations (CP2 and CP3) surface access was restricted and ground treatment by freezing, performed from the tunnels, was required. The CPs are 12.3m long with an excavation diameter of 5.8m and are located up to 30m below the water table partly or wholly within the Key Largo limestone (termed Layer S7 in the ground model). Layer S7 is a coralline limestone having a metastable honeycomb structure and high variable porosity. At CP2 the upper portion of the excavation was within the overlying Anastasia Formation limestone (Layer S6), comprising a highly permeable coquina. The geological profile along the project is shown in Figure 2.This paper presents aspects of the freeze design and the risk mitigation necessary to successfully achieve the construction of the CPs in the unique geological conditions."

Jan 1, 2016

By C. Melvin Lepper

The Bureau of Mines has developed an improved earth resistivity field system which employs a novel technique for obtaining null measurements. The instrument is designed to operate reliably in high-noise environments such as those found in the vicinity of operating mines. The system consists of a low-frequency transmitter, a sensitive receiver and an external battery pack, each in its own case to provide protection from the elements. The receiver and transmitter units have self-contained recharge-able batteries to supply power to the circuitry and separate built-in battery chargers that operate on standard 115 Vac power. The system is portable and simple to operate. Measurement accuracy, reliability, and dynamic range are superior to most commercially available equipment even though less time and effort is required to make null readings. Unlike some commercial systems, long integration times are not required to enhance signal-to-noise ratio in areas of high background noise.

Jan 1, 1974

By D. R. Boyle

"The Murray Brook precious metal (Au, Ag) gossan deposit is one of nine supergene mineral deposits that have developed over polymetallic massive sulfide deposits in the Bathurst Camp of New Brunswick. Reserves consist of 1.9 Mt of gossan containing 1.53 g/t Au and 65.9 g/t Ag. The supergene zone at Murray Brook consists of six distinct units: a) altered massive sulfide, b) pyrite-quartz sand, c) massive sulfide gossan, d) disseminated sulfide gossan, e) ferruginized wallrock, and f) leached bedrock. The massive sulfide gossan constitutes the main body of economic mineralization and consists of goethite, primary quartz, secondary amorphous silica, K-Fe-Pb-As- Sb-Ag hydrated sulfate and oxide minerals (beudantite, plumbojarosite, jarosite, bindheimite, scorodite), trace cinnabar, and cassiterite of primary origin. The order of stability of sulfide minerals during oxidation was pyrite _ arsenopyrite _ galena _ Bi-Sb sulfosalts _ chalcopyrite _ tetrahedrite group _ sphalerite.Two mass balance techniques (isovolumetric and conservative element) indicate elemental depletion in gossan relative to primary ore in the order: S>Cd=Zn>Cu=Mn>Na=Ca>Fe=Al=V> Mg= K=Se=Hg>Pb>Ti>Ag>Mo=P>Ba; and enrichment in the order Au>As>Sb>Si>Bi. Tin, as cassiterite, is conservative.Mineralogic and paleomagnetic data suggest that the gossan deposit formed under a warm temperate climate throughout the Pliocene. The rate of oxidation and the compositional nature of the ore was significantly influenced by: a) the position of the primary sulfide zone in a downward moving hydrological system, b) primary sulfide composition and zonation that promoted the development of a strong electrochemical oxidation system, and c) pronounced intercalation of carbonate and sphalerite mineralization in sulfide zones, which promoted rapid development of secondary porosity, permeability and downward flow of oxygenated groundwater.During progressive oxidation and physico-chemical erosion of the gossan zone, Au was transported downward in groundwaters, probably as a Auo colloid complex, to be concentrated in the lower horizons of the gossan profile. The precipitation of Au was greatly increased in the pyrite/arsenopyrite zones. Gold concentration was multi-cyclic with continual dissolution and nucleation of the metal until final concentration in the void structures of the gossan. Leaching experiments and microprobe analyses indicate that Au is present in the gossan as submicron composite sols of Au-Ag-silica."

Jan 1, 1995

By D. R. Boyle

"Abstract - The Murray Brook precious metal (Au, Ag) gossan deposit is one of nine supergene mineral deposits that have developed over polymetallic massive sulfide deposits in the Bathurst Camp of New Brunswick. Reserves consist of 1.9 Mt of gossan containing 1.53 g/t Au and 65.9 g/t Ag. The supergene zone at Murray Brook consists of six distinct units: a) altered massive sulfide, b) pyrite-quartz sand, c) massive sulfide gossan, d) disseminated sulfide gossan, e) ferruginized wallrock, and f) leached bedrock. The massive sulfide gossan constitutes the main body of economic mineralization and consists of goethite, primary quartz, secondary amorphous silica, K-Fe-Pb-As- Sb-Ag hydrated sulfate and oxide minerals (beudantite, plumbojarosite, jarosite, bindheimite, scorodite), trace cinnabar, and cassiterite of primary origin. The order of stability of sulfide minerals during oxidation was pyrite > arsenopyrite > galena > Bi-Sb sulfosalts > chalcopyrite > tetrahedrite group > sphalerite.Two mass balance techniques (isovolumetric and conservative element) indicate elemental depletion in gossan relative to primary ore in the order: S>Cd=Zn>Cu=Mn>Na=Ca>Fe=Al=V> Mg= K=Se=Hg>Pb>Ti>Ag>Mo=P>Ba; and enrichment in the order Au>As>Sb>Si>Bi. Tin, as cassiterite, is conservative.Mineralogic and paleomagnetic data suggest that the gossan deposit formed under a warm temperate climate throughout the Pliocene. The rate of oxidation and the compositional nature of the ore was significantly influenced by: a) the position of the primary sulfide zone in a downward moving hydrological system, b) primary sulfide composition and zonation that promoted the development of a strong electrochemical oxidation system, and c) pronounced intercalation of carbonate and sphalerite mineralization in sulfide zones, which promoted rapid development of secondary porosity, permeability and downward flow of oxygenated groundwater.During progressive oxidation and physico-chemical erosion of the gossan zone, Au was trans- ported downward in groundwaters, probably as a Auo colloid complex, to be concentrated in the lower horizons of the gossan profile. The precipitation of Au was greatly increased in the pyrite/arsenopyrite zones. Gold concentration was multi-cyclic with continual dissolution and nucleation of the metal until final concentration in the void structures of the gossan. Leaching experiments and microprobe analyses indicate that Au is present in the gossan as submicron composite sols of Au-Ag-silica."

Jan 1, 1995

By S Piercey, M Doublier, B Eglington, D L. Huston, S Pehrsson

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The distribution of volcanic-hosted massive sulfide deposits through time is episodic, involving relatively short time intervals of apparent high productivity and long intervals of low productivity. This distribution is principally related to the geodynamic evolution of the Earth. The vast majority of these deposits is associated with the assembly of supercontinents and form along convergent margins, generally in back-arc basins or rifted arcs. This contrasts with the distribution of black smoker deposits, which presently form along both convergent margins, particularly in the western Pacific, and divergent margins at mid-ocean ridges. However, the latter environment is rarely preserved deep into the geological past.There also appear to be systematic patterns in a number of other features of volcanic-hosted massive deposits through time. Deposits hosted by mafic-dominated successions are dominant in Archean to Proterozoic rocks, whereas deposits hosted by felsic-dominated successions are most common in Phanerozoic rocks. Geochemical characteristics of felsic rocks within the host successions and ore lead and sulfur isotope data of the ores have also changed with time. This suggests changes in the process of subduction and/or changes in the characteristics of the over-riding plate with time, consistent with isotopic and geologic evidence for greater reworking of pre-existing crust during the Phanerozoic.Other secular changes that are reflected in characteristics of volcanic-hosted massive sulfide deposits include the redox state and salinity of coeval oceans. As an example, both the abundance of sulfate minerals and sulfur isotope patterns reflect the development of periods of anoxic conditions over time, with major intervals of anoxia reflected by a virtual lack or low abundance of sulfate minerals in volcanic-hosted massive sulfide deposits in the Mesoarchean to the Palaeoproterozoic, and shorter intervals since.CITATION:Huston, D L, Eglington, B, Pehrsson, S, Piercey, S and Doublier, M, 2015. Secular variations in the abundance and characteristics of volcanic-hosted massive sulfide deposits – implications for evolution of convergent tectonics and ocean geochemistry , in Proceedings PACRIM 2015 Congress, pp 475–480 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By A. G. Starliper, H. Kenworthy

A procedure was developed for the separation of lead and sulfur in industrial concentrates of galena by a combination of chlorination and fused - salt electrolysis . Galena could not be satisfactorily electrolyzed in the various media tried ; however , when it was treated with chlorine the resulting lead chloride could be effectively separated electrically into lead and chlorine . An apparatus was designed and constructed to chlorinate galena and to volatilize simultaneously most of the chloridized impurities . By electrolyzing the chlorinated concentrate , a high percentage of lead was recovered . Anodic chlorine was drawn from the cell and was used to chlorinate new feed . In many runs , the recovered metal analyzed from 99.8 to 99.9 percent lead . Lead was also distributed as a chloride in the bath , and a small portion was in the volatile fraction produced during the chlorination step . During a tinuous operation , only 0.1 percent of the total lead was discarded ; 99.9 percent was accounted for in the metal , electrolytic bath , and washed or leached chlorination condensate which was essentially lead chloride . About 95 percent of the sulfur from the galena was recovered as a byproduct of over 90 - percent grade .

Jan 1, 1964

By Paul L. Michael

Roof warring signals from eleven underground coal mines (principally in the Pittsburgh seam) were studied and analyzed. The character of individual acoustic warning signals is shown to be dependent on spectral distribution of energy. Reverberation tires (pulse decay rates) were found to be usually between 0.1 and 0.5 seconds. Listening tests were conducted to assess the miner's ability to discriminate speech and roof talk signals in noise and in quiet, with and without ear protectors and with various levels of hearing loss. The ability to detect roof talk is shown to be generally degraded while wearing car protection in quiet, although, if car protectors are worn only when required by high noise levels, the ability to detect roof talk will be preserved at its maximum.

Jan 1, 1972

By F. Kongoli

Viscosity is an important parameter of copper smelting and converting processes. It affects the settling of matte or metal droplets in the slag, distribution of elements etc, Despite this importance, confusion exists on the viscosity of copper smelting slags as a result of disagreements found among the measured viscosity data of several authors especially in the slags of high ferric iron content and close to magnetite precipitation. In this work a critical review of the existing data on the viscosity of copper smelting slags has been first carried out and the effect of oxygen potential on the viscosity of copper smelting slags has been clarified through a coupled quantification of viscosity and liquidus temperature. The confusion in the literature has been clarified and the importance of the relation between the viscosity and the liquidus temperature is discussed,

Jan 1, 2003

By Vinit Mody

The belt conveyor is one of the major pieces of equipment for transferring bulk material in mining operations. However, considerable amount of respirable dust may be generated whenever the bulk material is loaded, dumped, or transferred. This report identifies and evaluates various dust control technolgies applicable to belt conveyors, and describes how an integrated systems approach can reduce dust emissions at a transfer point. Phase I of the program consisted of literature search and a critical evaluation of various dust control technologies. The work established that a comprehensive approach to calculating exhaust volumes for dust collection system does not exist. The parameters that affect the wet dust suppression efficiency were also reviewed. Based on the Phase I work, bulk material handling system and dry dust collection or wet dust suppression systems were designed and installed at a number of transfer points in a limestone processing facility, a surface mine selected as a field test site. Field test data were used to determine the validity of various exhaust volume calculations at the different transfer points. The field test data also formed the basis for the evaluations of the relative effectiveness of commercially available and wet dust suppression systems in controlling respirable dust emissions.

Jan 1, 1984

By G. L. Oldright

This paper is the fourth of a series of preliminary papers on smelting in the lead blast furnace.4 The objects of this investigation are to determine the conditions obtaining within the blast furnace by direct experimentation and to correlate these conditions with operating factors, furnace behavior, and metallurgical losses. ACKNOWLEDGMENTS The authors wish to express their appreciation to the management of the International Smelting Co. at Tooele, Utah, for their whole-hearted cooperation in this investigation.

Jan 1, 1929

THE purpose of this chapter is to present a general outline of the basic open-hearth process for the benefit of students, practicing open-hearth operators, and metallurgists who wish to review the subject. The discussion is limited to a description of the sequence and purpose of the operations, illustrated by data and examples. Subsequent chapters deal with more detailed and fundamental studies of the subject. The function of the basic open-hearth furnace is to convert various types of ferrous material into finished steel of given com- position and quality. In comparison with other steelmaking methods, the basic open-hearth process is one of the most versa- tile, both from the standpoint of the raw materials that can be used and the types of steel that can be produced. The process can be considered as a sequence involving melting, refining, and deoxidation. With some types of liquid-metal charges, the melting stage is not present, but refining and deoxidation in varying degrees are fundamental features of the process. GENERAL DISCUSSION OF BASIC OPEN-HEARTH PROCESS The first consideration in open-hearth practice is the type of charge on which the operation is based. This consists of three components-fluxing, oxidizing, and metallic materials. Fluxes. In the basic process the fluxing material is primarily lime, added in the form of either limestone (CaC03) or burnt lime (CaO) . This is supplemented by magnesia (MgO) and lime from the furnace bottom and banks. The function of these fluxes is to form a slag with the silica (SiO2) , manganese oxide (MnO), iron oxides (FeO and Fe203), and phosphorus oxide (P205) that are produced by the oxidation of varying amounts of the silicon, manganese, iron, and phosphorus in the charge during melting and refining. The slag, composed of the basic fluxes and the neutral and acid oxides, floats on top of the steel bath when the charge is melted. The composition of this slag depends on the amount of each slag-forming element present in the charge and on the extent of oxidation of these elements during the course

Jan 1, 1964

By Steve J. Czehura

The Butte quartz monzonite is the host rock for early porphyry copper style mineralization and subsequent mesothermal-epithermal, enargite-gold style veining that transects the district. The east-west Anaconda system veins sustained mining for over a century. They include the Emma, Anaconda-Original, Syndicate, Badger-State and Alice-Rainbow veins, each with strike lengths of more than 3,660-m (12,000-ft) and vertical continuity in excess of 1,370-m (4,500-ft) with mining widths from 1.5- to 15-m (5- to 50-ft). These characteristics are unique to Butte. The incredible dimensions and tenor of these veins have yet to be surpassed and Butte is still touted as being the “Richest Hill on Earth.” The Anaconda Company was formed in 1895 to develop underground copper reserves in the district. It eventually consolidated all operations under one company. Production from underground mining continued through the mid-1970s. Openpit mining in the Berkeley pit began in 1955 with the extraction of supergene ores, along with the remnants of deeper horsetail zones inaccessible to the underground mines.

Jan 1, 2006

By M. J. Michaud, M. J. Lavigne

"A cornerstone of any successful mining project is an understanding of the mineral assemblage and metal distribution comprising the deposit. Knowledge of the precise mineral/ metal zoning enables an operation to utilize different mining and processing methods optimized for different parts of the deposit. The Lac des Iles mine, located in northwestern Ontario, is one operation that depends on a good understanding of these issues. Current resources for the Roby Zone total 94.1 Mt grading 1.66 g/t Pd, 0.18 g/t Pt, 0.14 g/t Au, 0.062% Cu, and 0.053% Ni.The Roby Zone occurs within the gabbroic portion of the Lac des Iles intrusive complex and consists of three compositionally and texturally different ore types with variable PGE, base and precious metal contents. PGE occur as sulphides and bismuthotellurides in net-textured sulphides, coarse sulphide blebs and as finegrained inclusions within secondary silicates.Knowledge of the precise mineral/metal zoning has directly and indirectly improved several operational aspects, including resource modelling, mining, and processing. For example, metallurgical recoveries have been increased by up to 3% to 5% and concentrate grades have increased by up to 100%. IntroductionLac des Iles Mines Ltd., a wholly owned subsidiary of North American Palladium Ltd., owns and operates a 3000 t/d open pit mine and concentrate facility, located 100 km north of Thunder Bay in northwestern Ontario. The Lac des Iles PGE-gold-copper-nickel mine has been in commercial production since 1993 and in 1997, produced 1.8 million grams of palladium, 127 000 g of platinum, 114 000 g of gold, 438 000 kg of copper and 354 000 kg of nickel (North American Palladium Ltd., 1998).Under the Industrial Research Assistance Program (IRAP), a two-year study of the mineralogy of the Roby Zone was undertaken with a goal of improving the profitability of the mine. Geological mapping, petrography and geochemistry of the Roby Zone were completed during this study. Utilization of the detailed mineral/metal zoning identified as part of this study was implemented at the mine and shown to positively impact many operational aspects including mining and processing."

Jan 1, 2003

By B. M. England, M. V. Swain, N. Bristow, R. D. Dukino

The toughness and fracture mechanisms of ores with significantly different microstructures from Yandi, Koolan and Mount Whaleback were studied with a view to understanding their degradation behaviour. Bulk fracture toughness was determined by the 3-point single-edge notch beam test and the results interpreted using Weibull statistical analysis; indentation fracture mechanics was also used to measure fracture toughness of the different mineral forms and to understand their response to contact fracture

Apr 1, 1995