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By L. I. Kiss, S. Perron, D. Toulouse, S. Poncsák, A. Perron

Bubbles play an important role in many industrial processes. In a Hall-Heroult cell, used for aluminum production, bubbles contribute to induce flow in the cell. The induced flow is important for the thermal balance of the cell as well as for the distribution and dissolution of the alumina. The existence of the bubble layer does not have advantages only. It increases the voltage of the cell and causes deformation along the cryolite-molten aluminum interface. The role of the anode inclination in the behaviour of the bubble layer as well as in the hydrodynamics of the bath is not clearly understood. In this work, the effect of the anode inclination angle on the bubble driven flow is studied in an industrial scale air-water model. The inclination angle is varied up to 5° from the horizontal. The instantaneous flow field is captured by Particle Image Velocimetry (PIV) system. The mean velocity fields were calculated by ensembleaveraging the instantaneous velocity fields measured at different time. The existence of the counter-flow in the interpolar space and the vortex in the side channel has been confirmed. Furthermore it has been observed that the effect of anode slope on the velocity field is weak.

Jan 1, 2006

By J. Aguilar-Santillan, H. Balmori-Ramirez, R. C. Bradt, I. Vernet-Patiño, F. Cunha

Kyanite is an alumino-silicate mineral that has been widely used for the production of refractory products for industrial applications. Kyanite provides a high alumina content, it readily produces mullite during firing, good hot strength of products and can be adapted to produce dimensional stability of products during firing. This research addresses the application of kyanite in mixes to produce (0 dense mullite aggregates with the addition of alumina, (ii) dense composite refractory aggregates of forsterite / spinel with additions of magnesia, and (iii) dense cordierite aggregates with the addition of talc. Effects of attrition milling and conventional ceramic processing are addressed as they affect the properties of these unique aggregates.

Jan 1, 2004

By P. C. Holloway, A. Tshilombo, T. Xue, M. J. Collins, R. Lopetinsky, I. Mihaylov, I. M. Masters

The Voisey’s Bay deposit contains a trace amount of cadmium, which reports to solution during pressure leaching of the nickel concentrate at Vale’s Long Harbour Hydrometallurgy Plant, and must be removed to produce high quality nickel cathode. In 2006, Vale approached Sherritt Technologies to collaborate on the development of a process for removing cadmium to low levels (<1 mg/L) in the nickel raffinate. Following successful bench scale and pilot plant testing at Sherritt’s laboratories, the cadmium removal process was then moved through engineering and construction, culminating in the successful commissioning and startup of a cadmium removal circuit at the Long Harbour Hydrometallurgy Plant in 2017. This paper presents the results of this collaboration and the challenges that were encountered through each stage of development, as well as current results from operation of the commercial cadmium removal circuit. INTRODUCTION Vale’s Long Harbour Processing Plant, with a nameplate capacity of 50,000 t/y nickel, began operation in 2014. In addition to electrolytic nickel rounds, the plant also produces electrolytic cobalt rounds and copper cathode. The Long Harbour Processing Plant uses a unique hydrometallurgical process developed by Vale Base Metals Technology Centre, as shown in Figure 1, to treat a nickel sulphide concentrate produced at the Voisey’s Bay mine and mill located in northern Labrador (VBN concentrate) (Stevens et al., 2009).

Jan 1, 2019

By W. Basuki, B. Setyotomo, L. Hakim, R. Hendrajaya

Due to high crack sensitivity of slab product of gas and oil line pipe application, its steel making process and alloy composition were evaluated and then improved to overcome its critical solidification process and reduced surface defects. The study was conducted at Slab Steel Plant Krakatau Steel. The purpose was to improve slab surface quality by reducing surface defects so that the slab surface doesn&apos;t need to be totally repaired. The method applied was by performing plant trial process, which the secondary process parameters such as alloying method and the casting parameters such as casting powder selection, metallurgical cooling, mould level control, and superheat were continuously monitored and then adjusted to the surface quality of the product. Based on the calculation of Ferrite potential of the steel, the chemical composition was designed to achieve optimum casting parameters in order to avoid high shrinkage during solidification. The results of the study are decreased surface defect quantity, and smooth casting process. The quantity of crack decreased by almost 90%. The slab surface repairing was significantly reduced from 85. % to less than 10%. These new casting parameters and developed alloy composition are then used and standardized for the mass production of the steel.

Jan 1, 2005

By D. Imeson, T. Grammatikopoulos, M. Aghamirian, M. Oliazadeh

"More than 70% of potash is produced worldwide by froth flotation. Flotation of potash was developed in the early 1930s. Amines are widely used for flotation of sylvite (KCl) from halite (NaCl) and insoluble materials such as clays. Amine collector is also absorbed by clays. Therefore, clays are usually separated by scrubbing and de-sliming prior to flotation. Alternatively, slimes can be floated ahead of potash flotation. Flotation recoveries of sylvite are commonly in the range of 85%, while losses can occur in slimes, flotation tailings and make-up of process brine. Ores containing free coarse-grained sylvite are generally screened, whereas both fine and coarse fractions are conditioned and floated separately. The unique features of potash flotation include solubility of sylvite in water, the size of particles floated and fast kinetics. Particles up to 2.3 mm can be floated and about 50% of flotation feed can be removed in the rougher stage in few minutes. The main challenges in potash flotation are the recovery of potash from slimes, flotation efficiency in the presence of carnallite and recovery of coarse potash grains. A review of potash flotation shows that there is still room for improvement in both coarse and fine potash flotation. The present paper reviews the most significant flotation parameters including reagent type and dosage, flotation circuits, flotation equipment size and new developments in potash flotation. The latter include new reagents, flotation technologies (Hydrofloat, Jameson and column cells) larger flotation cells and slimes flotation.INTRODUCTION Potash is the common industrial term for potassium in various chemical combinations and minerals soluble in water. About 90% of potash produced worldwide is used as agricultural fertilizers. Flotation is the main treatment process of sylvinite (KCl-NaCl) ores for recovery of sylvite (KCl). Potash concentrate should contain a minimum of 95% KCl and be relatively free from 0.2 mm KCl fines. The flotation process for beneficiation of potash ores was developed in United States and Russia concurrently in the early 1930s. In 1934, Potash Corporation of America applied flotation process in a commercial scale (Tippin R.B. and Huiatt J.L). In the initial application, halite (NaCl) was selectively floated by employing lead chloride as an activator and soap as collector. The sylvite concentrate was reported in the cell underflow."

Jan 1, 2012

By Georgy A. Cherkashov, Andrey V. Efimov, Yury S. Borodaev, Nadezhda N. Mozgova, Sergey G. Krasnov, Tamara V. Stepanova, Alexander M. Ashadze

"Abstract - A horizontal mineralogical-geochemical ore zonation with a southeast to northwest trending succession of Cu and Fe (Zn) main zones has been discovered in the Logatchev hydrothermal field (14°45??N Mid-Atlantic Ridge). The major minerals are pyrite, chalcopyrite, bornite, isocubanite, digenite and chalcocite. Zn-sulfide, marcasite and covellite are less abundant. Rare minerals are native copper, zincian copper and cobalt pentlandite (first found in oceanic massive sulfides), Cu and Cu-Co-bearing Fe-disulfides. Two groups of the main sulfide assemblages with different copper contents are recognized: Group I comprises assemblages with primary sulfides (isocubanite, chalcopyrite, pyrite and Zn-sulfide; Cu up to 35 wt% in Cu-bearing minerals); Group II contains assemblages with secondary Cu-rich sulfides (bornite, digenite, chalcocite; Cu ~60 wt%) as well as rare minerals (cobalt pentlandite, native copper and zincian copper). The assemblages of Group I formed at a temperature of about 300°C; the sulfur fugacity (log fs2 atm) at 300°C is probably 9.9. Relations between minerals of this group are contradictory, attributed to non-equilibrium environments, and no unified sequence of crystallization of minerals has been determined. Minerals of Group II replace, rim or cross the assemblages of Group I. Group II minerals crystallized in a distinct sequence (cobalt pentlandite-bornite-digenite- chalcocite-native copper), with increasing copper content from the start to the end of the depositional sequence. This may correspond to pH from 7 to 8 near Eh = -0.2 at 250°C. Minerals of this group were generally formed under hypergene alteration processes. Compositions of ore minerals were studied by means of electron microprobe analysis (EMPA) (150 analyses). Narrow composition fields were revealed in all main sulfides, which comprised known experimental data. ZnS contains 6.0 to 28.0 mol.% FeS, which is close to data known for other hydrothermal massive sulfides from the Mid-Atlantic Ridge (MAR). A common admixture in ZnS is Cu (0.16 to 1.32 wt%). Rare grains of unusual anisotropic Fe-disulfides, (Fe0.95Cu0.05)S2 and Cu(Fe,Co)9S20, were found among the ore minerals."

Jan 1, 1999

By J. R. Levin, E. J. Schelter

"We present some of our recent efforts in the development of predictive, directed oxidation chemistry of cerium(III) complexes under non-aqueous conditions. The electrochemistry of cerium(III)- alkali metal heterobimetallic aryloxide complexes is reported and compared with cerium aryloxide complexes that are kinetically stabilized by hydrogen bonding cations that span between the complexed aryloxide ligands. Comparative electrochemical measurements reveal differences between the heterobimetallic complexes and the hydrogen-bonded complexes.INTRODUCTIONThe rare earth elements comprise the lanthanides, La–Lu, and the element yttrium (Aspinall, 2001). Rare earth ores such as monazite, LnPO4, and bastnäsite, LnFCO3, typically bear mixtures of light rare earths: La–Sm while monazite, LnPO4, contains mixtures of heavy rare earths (Eu–Lu) (Cotton, 2006). Pure rare earth elements typically are isolated using a liquid-liquid separations process.(Bautista, 1995) The hydrometallurgy of these elements is a difficult problem because the separation factors between neighboring rare earths, which are predicated on the small differences in the sizes of the trivalent ions, are quite small (Cox, 1992). The element cerium, with its 4f1 electronic configuration in the trivalent state, is unique among the rare earth elements due to a relatively accessible 4f0 electronic configuration. The accessibility of the 4f0 configuration underlies the chemistry of cerium(IV), the only rare earth ion with molecular chemistry in the tetravalent oxidation state (Cotton, 2006). Cerium is trivially separated from mixtures of light rare earths by making use of its unique oxidation chemistry. In an effort to extend separations chemistry by oxidation reactions to other rare earth elements such as terbium and praseodymium, the solution electrochemistry of well-defined cerium complexes is of interest."

Jan 1, 2012

By J. Guha, R. Kanwar, G. Archambault, A. Tremblay

The Copper Rand Cu-Au deposit lies within a shear zone which strikes N50-60W and dips steeply southward (50°-55°) and extends over 1. 5 km with a thickness which varies form 350 to 425 metres. Mineralization, inside the shear zone, is structurally controlled by a dilation mechanism which can be explained by a fracture dilatancy model. The principle of this model involves the mechanics of overriding of irregular planes and surfaces of faults and schistosities, These structures are characteristic features of the Copper Rand shear zone. A structural analysis of the shear zone has been carried out to establish relations between the different structures within the shear zone and their evolution with the development of the shear zone. A geomechanical interpretation of the Copper Rand shear zone explains the formation of internal structures such as faults, schistosities and microstructure during the shearing. This interpretation confirms Ramsay's theoretical model on the geomechanical evolutuion of shear zone development, and the experimental work of Morgenstern-Tchalenko on the simulation of shear zones in clay models. The geomechanical interpretation of the shear zone demonstrates that at the onset, subsidiary fracture patterns are developed in second order faults in the following sequence. At peak strength Riedel shears ( R and R') are formed which propagate outside the strength, restraint (P) shears are developed in the thrust attitude within the shear zones. Principal displacement shears (D) develop toward residual strength in the direction of movement. Shear lenses are formed by the interaction of these shear discontinuities and these facilitate the formation of schis tosi ties with the continuation of the shear displacement within the main shear zone. While the main shear zone and the P and D shears within the main shear zone were in continual movement, the Rand R' structures, once formed, retained a simple fracture pattern and moved little outside the shear limits in comparison to the main shear zone. Parts of these structures inside the shear zone were reactivated by subsequent movements and deformed into folds to account for the present attitudes of the HW-1 and HW-2 and HW-3 structures. This geomechanical model for the shear zone with its subsidiary structures (R, R', P and D shears) is also applied on a larger scale to the Dore Lake shear belt and explains the different structures accompanying it. The initial development of the WNW shears (most are ore deposits) was followed by the subsidiary structures of the Dore Lake shear in a north-south stress field and is well defined by the movements characteristic of the different structures. It is concluded that the Dore Lake shear cannot be the prolongation of the McKenzie Narrows shear but it seems that this prolongation relates to the Henderson-Portage shear zone.

Jan 1, 1984

By Brian Putland

Single stage semi-autogenous / autogenous (S/AG) milling has become a common design for a variety of ore types with the advantages of being comparatively low capital cost and flexible for future expansion. The single stage SAG/AG milling option is ideal for starter projects with significant exploration and expansion potential. Currently a number of the largest SAG mills designed are installed in single stage configuration. This paper discusses the challenges associated with the process design of single stage SAG/AG milling circuits, the design flexibility required to ensure a robust circuit and the operating techniques adopted at successful installations.

Jan 1, 2012

By H. C. Wade

"Description and UseDischarge liners or pulp lifters as they are sometimes called are a trough type liner used at the discharge end of the mill where ground ore passes to the trunnion.There are basically two methods of discharging pulp. The First and most common is the overflow method. Here ground ore travels from the feed to the discharge end where it exits through the discharge trunnion in an overflowing manner, hence the name ""overflow"". (See Figure I) The second method of discharging pulp is the grate method. With this method you block-off the trunnion and hold the ore inside the mill for a longer period of time. This allows only the desired size of ore out of the mill. Ore passes through the grate liners, into the Vibrathane Discharge liner, and finally down to the trunnion. Greater control of the ore size results wit1 this method as compared to the overflow method and it also eliminates reclassifying and regrinding. (See Figure 2)Types in UsePresently the majority of discharge liners in use today are rubber. (Metal insert and rubber covered) In some extremely course applications steel and nihard are used."

Jan 1, 1980

By K. E. Prince, S. Burling, R. J. Ring, M. K. Maley, W. R. Taylor

Vanadium occurs as a component of carnotite, which commonly occurs in calcrete type ores, and in association with uranium in some sandstone-hosted deposits. Increasing demand for vanadium, which is used in high-strength steel and Vanadium Redox Flow Batteries (VRFBs), is offering some uranium producers a potential option for by-product vanadium recovery to improve project economics at a time when uranium prices are low. This paper presents the results of recent optimisation studies on the Bigrlyi deposit for the recovery of both uranium and vanadium. The impact of carbonate leaching conditions on uranium and vanadium extraction from a range of carnotite-in-calcrete ores is also examined, with vanadium extraction limited by the proportion of non-carnotite vanadium present in the ores. The findings are particularly relevant to developing projects as results show that elevated vanadium content in ore does not necessarily equate to a high vanadium extraction in leach.

Jan 1, 2020

By W. Lin, Z. Z. Dong, C. L. Zhou, Y. C. Kuang

The inversion of rock mechanical properties based on well-logging data is a common method to drillbit selection in petroleum engineering, the basic principle of which is to use deep-well logging data and experimental regression model to calculate rock mechanical properties. The profile of rock mechanical properties can be established. According to the profile, the type of drillbit can be selected in different formations, which will improve the economic benefit of bit use indicators. Compressive strength of rock is one of the most important parameters. Conventional method to establish regression models of acoustic velocity and uniaxial compressive strength is on the basis of rock core sonic experiments and uniaxial compressive experiments. However, with the increase of deep drilling operation, triaxial compressive strength prediction model will play a more vital role in drillbit optimization selection in deep wells and improving ROP (Rate of Penetration). Triaxial compressive strength is an important parameter to evaluate the formation strength property. In this paper, to the sandstone commonly encountered in oil drilling, combined the rock mechanical experimental results with the changing porosity experimental results under confining pressure, a new interpretation model of triaxial compressive strength based on well logging data is proposed. Firstly, three types of sandstone samples are collected. Then measured components, uniaxial compressive strength, triaxial compressive strength and porosity. Experimental results show that: confining pressure has a significant influence on sandstone strength, with the increase of confining pressure, triaxial compressive strength increase; furthermore, the triaxial compressive strength of different porosity sandstones have different change rules when confining pressures changes; sandstone porosity decreases with the increase of confining pressure and it obeys logarithmic function. According to the results, regression models of sandstone, in-situ uniaxial compressive strength model and uniaxial compressive strength model under normal pressure are generated. Meanwhile, using well logging data in the acoustic velocity, density and gamma value can derive in-situ rock formations uniaxial compressive strength and in-situ porosity. Eventually, a new model established in this paper, containing in porosity, uniaxial compressive strength, lateral pressure and power exponent of regression, can predict triaxial compressive strength which will guide drillbit selection.

Jan 1, 2015

By R. L. J. Phillips

"The environmental impact of the Rabbit Lake project is presented. Baseline data for fish, water, air and radon collected in 1973, 1975, 1980and 1986, are compared with post-development environmental monitoring data. Predicted environmental impacts for the developed Rabbit Lake and B-zone deposits are compared to the actual impacts. INTRODUCTIONThe environmental impact of the Rabbit Lake project has been documented through the years in several submissions to the government agencies. In 1972, the environmental baseline study for the Rabbit Lake area was completed prior to any mining activity at the Rabbit Lake pit (Fig. 1).Sampling concentrated on Hidden Bay and Pow Bay, which received the treated effluent and the waters drained from Rabbit Lake respectively.A second baseline study was done on the Collins Bay area in 1980(Fig. I) in preparation for the mining of the B-zone pit. The detail in this study was considerably greater than the detail in the previous study. Collins Bay and Harrison Peninsula were the areas sampled. The B-zone deposit is being mined at present.With the discovery of the A-zone, D-zone and Eagle Point deposits, it was decided in 1986 to begin proceedings to obtain approval from Saskatchewan&apos;s Department of the Environment, and from the Atomic Energy Control Board to develop these deposits.In preparation, a third baseline study of both the Rabbit Lake and Collins Bay areas was done in 1986 and 1987. The emphasis was to establish the baseline at the three new deposits, to quantify the actual impacts of the existing Rabbit Lake operations and to confirm the Collins Bay B-zone (1980) impact predictions. The new deposits will allow us to continue to produce uranium into the future. In January 1988, Saskatchewan approval was received.Since 1975 in the Rabbit Lake area and 1980 in the Collins Bay area, routine environmental monitoring has been done. This has resulted in one of the largest and most comprehensive environmental data bases in North America in mining. By the time the Eagle Point deposit is mined to completion, there will have been data collected for approximately 40 years.Further discussions follow which describe the impacts of the past (1972 to 1984), the present (1985 to 1987) and the future. In addition, the past and present performances and the future plans of the .waste management systems will be discussed."

Jan 1, 1989

By S. Isaac

The networks of interdependencies between elements in building projects, referred to as the project topology, are often complex and difficult for project teams to comprehend. It is hypothesized that a graphbased model of the project topology can be based on existing data in Building Information Models (BIM), facilitating the application of graph-theoretic algorithms to analyze this topology. The objective of this study is to propose an outline for the synthesis of BIM and graph theory. This synthesis is expected to contribute to the development of new tools for representing, managing and analyzing the design of building projects.

Aug 1, 2013

By K. Jomoto, H. Majima

"Experimental work has been attempted to find a useful criterion of comminution which can be determined simply in a laboratory. The suitability of the ratio of the square of tensile strength to Young's modulus, St2/E, previously derived from the theory of elasticity as a criterion of comminution, was examined measuring tensile strength, Young's modulus and critical height for drop-weight impact of five different rocks. However, satisfactory correlation between St2 /E and critical height has not been obtained, suggesting the necessity of further experimental verification of the representative value of Young's modulus of rocks. The plot of St2 vs. critical height, however, shows one-to-one correspondence, and this finding suggests that St• may be a useful criterion of impact crushing. Also, a close relationship was observed between st• and the energy index for tumbling mill grinding of •the sample rocks. It is confirmed from these findings that the quantity St• is a useful criterion of comminution of rocks, not only for impact crushing but also for tumbling mill grinding. As shown in the experimental part of this paper, the determination ol St with irregularly shaped specimens is simple."

Jan 1, 1972

By J. T. Vehkala, S. S. Kerr, D. E. Robertson

"Since the late 1970s, extensive work has been carried out at Placer Dome Inc. &apos;s Dome Mine to develop new mining methods and equipment to improve the productivity of narrow vein mining (Mining Magazine, Oct. 1986, pp. 308-317; Mar. 1988, pp. 176-/79). This work has been focused on mining veintype deposits varying from 0.9 m to 1.5 m in width using open stoping and cut-and-fill mining methods.In 1989, the Dome Mine entered into a contract with Ram Raising Ltd., a joint venture company of Angus Martin and I.S. Redpath Ltd., to develop and mine a narrow vein test stope using an Alimak Raise Climber. Early results have been favourable, indicating that Alimak methods can be used successfully to mine narrow vein are.HistoryThe Dome Mine, which has been in continuous operation since 1910, is located in South Porcupine, part of the city of Timmins, Ontario. The mine is wholly-owned and operated by Placer Dome Inc. and is part of Placer Dome Inc.&apos;s international stable of of 19 mines."

Jan 1, 1990

By G. E. Joe

"This is a panel discussion on the milling experience with large volume flotation machines in Canada. Over the past ten years, the Canadian milling industry has been characterized by treatment of ever increasing tonnages of lower grade ores. In order to treat these ores efficiently, mineral processors have been employing increasingly larger volume flotation machines. In older established mills, standard flotation cells have been replaced by the larger volume models with very apparent savings in mill floor space as noted in the Opemiska copper mill.We are pleased to hear from four mill operators with extensive experience on large volume flotation machines. They are:1. I. E. Wahn, metallurgist with Falconbridge-Manibridge, who will describe their mill experiences with the Tank cell and the Maxwell cell.2. G. M. Hughes, mill superintendent of Sherritt Gordon-Ruttan, will detail recent experience with the Agitair cell.3. J. R. Maxwell, mill superintendent of Opemiska Copper, will report on their Maxwell cell installation and operation.4. A. H. Winckers, superintendent of Development and Technical Control, Sullivan Mill, will present a paper written by H. J. Chalmers describing Cominco's past experiences with large volume flotation machine installations including Denvers, Wemcos and Maxwells."

Jan 1, 1974

By J. -C. Parisien-La Salle, D. Blais, G. P. Demopoulos

"In this work the dissolution, precipitation and adsorption behaviour of gold in acidic iron sulphate media containing small amounts of chloride ions is investigated via batch laboratory tests and OLI thermodynamic calculations over the temperature range 25-250°C. Chloride ions may be present in industrial pressure oxidation/pressure leaching (POX/PL) operations due to elevated water salinity levels or due to intentional addition as is the case of the CESL Copper Pressure Leaching Process. Thermodynamic calculations show that AuCl4 - may form depending on the free Cl-/Au ratio and temperature, its stability increasing with increasing Cl- concentration and decreasing with increasing temperature. On the other hand during POX/PL, we know that massive precipitation of iron in various hydrolysis products and compounds occurs. Hence of interest is the question how AuCl4 - that may form during leaching interacts with the iron precipitation products. Gold(III) chloride was found to co-precipitate with iron(III) (oxy) hydroxides and arsenates forming in the autoclave but not with natrojarosite. Upon further investigation it was discovered that activated carbon added in the autoclave (as done in CIL) acts as preferential sink for the mobilized gold, hence opening the potential for the development of a direct cyanide-free gold recovery process in acidic sulphate leach reactors.INTRODUCTIONThe recovery of gold from ores and concentrates has evolved over the years with processing routes becoming increasingly complex. Given the high value of gold, any reduction in losses during recovery operations constitutes an important economic benefit. One such loss that needs to be addressed is the potential solubilisation of gold during pressure oxidation (POX) of refractory sulphidic gold feedstocks. For example, Agnico Eagle Mines reported a loss in gold recovery due to the formation of a gold chloride complex (Garofalo, 2009). Gold is known to form complexes in solution, such as gold(III) chloride, if an excess of chloride ions are present. The fate of such soluble gold chloride during pressure oxidation and the subsequent neutralization of the acidic discharge slurry will determine if gold is lost or recovered in the downstream cyanidation operation. Thus it is of interest to know under what conditions gold chloride may stay soluble or co-precipitate along primary (formed in the autoclave) or secondary (formed during neutralization) precipitates. Furthermore, the mode of co-precipitated gold, such as adsorption on iron compounds, like goethite and hematite (Machesky et al., 1990; Nachayev, 1984); substitution in one of the precipitated phases; or finally chemical reduction to metallic state would have consequences in terms of gold recovery."

Jan 1, 2012

By J. Ellis Thomson

For many years the value of qualitative microscopic investigation has been recognized in both of the fields of pure and applied science. In particular, its aid has been invoked in the determination of rock specimens in thin section, and some at least of the interrelations of minerals present in any one section have been observed and, to a limited extent, applied for the solution of different problems. During the past decade this form of research has also been diverted to the determination of ore minerals in polished section, with some observation of their structural relations. Microscopic research of a quantitative character, on the other hand, while started nearly one hundred years ago, has found but a limited application in petrography and has scarcely been used at all in the more modern science of mineragraphy. This is very largely due to the methods employed, since most of them consumed too much time and were, in addition, too laborious to encourage many workers in their use. The details of procedure for these earlier methods will be found in another paper by the writer, and will be omitted from this discussion as being of small interest to practical mining men.

Jan 1, 1930

By Daniel L. Cluff

The Canadian mining industry needs to find viable alternatives to the conventional cemented pastefill/hydraulic methods of backfilling open stopes for underground mines located within a permafrost zone. The harsh environment and the isolated location of a mine north of 60° impose additional challenges to standard backfill methods and opportunities to the technological and operational issues related to the use of frozen fill. Underground open stoping mining methods require the placement of fill material to enable the controlled recovery of ore from secondary and tertiary stopes. The typical design of the fill material requires the specification of inert material, water and binder. The permafrost conditions provide the additional parameter of subzero temperatures for backfill design and process control. The paper presents the results of an experimental field study, using large size samples, to determine the strength capacity of frozen backfill. The experimental work was performed utilizing rockfill and tailings material with moisture content consisting of water and ice crystals. Preliminary results indicate that the mixture of rockfill, tailings and moisture, develops strength that meet the demanded requirements for open stoping. A thermal equilibrium modelling analysis is presented in the paper.

May 1, 2008