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By J. M. Goris

"Researchers at the U.S. Bureau of Mines are conducting research on cable-type ground supports to assess their material and support properties and to provide design criteria for implementing cable supports as a workable roof control system under various underground mining conditions. Much of this work involves laboratory assessment of the material and support properties of cable supports using both conventional and birdcage steel cables. Included in this assessment are single and double cables, effects of changes in embedment length on support strengths, water-cement ratios, use of breather tubes, and pumpability and water-bleeding properties of grouts.IntroductionSince cable supports were introduced in the early 1970s, considerable research has been conducted in laboratories and at mine sites to understand their behaviour. The U.S. Bureau of Mines began a laboratory evaluation project in 1985 at the Spokane Research Center (SRC) to study the behaviour of cables supports under uniaxial loads so that the effects of various cable support components, such as grout and breather tubes, could be identified. Other objectives were to compare the behaviour of various types of cables and grouts and to collect meaningful data for numerical analyses. Pull tests were conducted to determine how cables supports reacted under uniaxial loads and how they failed when ultimate loads were exceeded. Such data are essential for the development of numerical models for analyzing rock mass behaviour when the rock is supported with cables.Test ProgramBecause each cable support can be composed of either single or double cables as well as a breather tube, pull tests were designed to include a variety of samples containing these components. A series of samples containing a single conventional cable, a neat cement grout having a water-cement ratio of 0.45, and no chemical additives was selected as a standard (Table I). Then one component in the system, such as the presence of a breather tube, was changed, and results of tests compared to results obtained for the standard samples to determine what influence that component might have on the behaviour of the support system. If significant changes in test data occurred, they could be attributed to that one component. To control the quality of the samples, the physical condition of the cables and tubes were monitored closely, and compressive and tensile strengths as well as flow properties were determined for the grout used in each test series."

Jan 1, 1991

By Y. Prevost, D. Verhelst

"A computer-assisted process control system for the Noranda Process Reactor Wa5 installed at the Home smelter in 1991. Operating as an advisory tool for the furnace operators, and using a flexible oxygen balance as the basic building block of the computer program, the new control system has helped to reduce the variability in the grade of the matte produced by 50% . The smelter is currently operating at a 72% copper matte, with a standard deviation of between 1.0 and 1.3, while treating a wide range of concentrates, secondary materials and scrap. Enhanced process control has allowed for longer reactor campaigns, and improved stability of the converting operation.This paper reviews the feed classification and blending practice used at the smelter, outlines the strategy of the new computer control system, and summarizes the benefits realized since the implementation of the system in early 1990.IntroductionUntil 1989 the Noranda Home smelter operated as a multi furnace smelter, at one time having three hot-charge reverberatory furnaces, and finally operating with one wet-charge reverberatory furnace and one Noranda Process Reactor. In 1989 the final reverberatory furnace was closed and the Reactor became the sole smelting vessel, treating around 750 000 tonnes of concentrate, secondary materials, and scrap per year. At the time of the start-up of theNoranda Reactor in 1973, the vessel was capable of treating 750tonnes per day of a heterogeneous mixture of copper concentrates, fluxes and secondary materials to produce copper in one operation. Through process improvements, and the introduction of additional oxygen in 1982(pannell and Mackey, 1988), the daily tonnage increased to 1800 tonnes by 1988. The operation had also been changed to produce a high-grade matte instead of copper. Figure1 illustrates the main features of the reactor, a cylindrical vessel which is charged at one end and tapped at the other. The matteis subsequently processed through Peirce-Smith converters and anode furnaces before being cast into copper anodes. Figure 2 outlines the progressive increase in the furnace smelting capacity. Over this period the percentage of secondary materials, and scrap feeds also increased to approximately 110 000 tonnes per year, or 15% of the total new feed input (Bedard et al., 1991). Now operating wholly as a custom feed operation, the Home smelter can treat over 2200tonnes per day of new metal-bearing material."

Jan 1, 1993

By Stanley W. Holmes

"The discovery of extensive uranium mineralization on the Pronto property in April 1953 initiated a program of staking, exploration, and development unparalleled in Canadian mining history. Within twelve months of the discovery hole, sufficient ore had been blocked out to merit a 55-million-dollar contract with Eldorado Mining & Refining Co. On October 15, 1955, two years and four months after discovery, Pronto went into production with a mill rated at 1,000 to 1,500 tons per day. The property is on the southern edge of the Algoma uranium district, 10 miles east of the town of Blind River and close to the Canadian Pacific Railway and Highway 17. Docking facilities for Great Lakes steamers are avail-able at Spragge, 4 miles to the east.The data and conclusions presented in this paper are based on field studies, drill hole information, and underground development. The ideas of ore genesis are those of the writer, and will undoubtedly be modified as more detailed studies and research are carried out. Because of security regulations, information pertaining to grade and tonnage will not be discussed.GeologyThe general geology of the Algoma basin has been outlined in a pre-ceding paper (Joubin and James). The description below is concerned essentially with the rocks most closely associated with the Pronto deposit. They may be grouped in three structural and lithological units: (1) the pre-Huronian basement, (2) the Mississagi formation, the lowest member of the Huronian sediments lying unconformably on the basement, and (3) a series of basic intrusives cutting (I) and (2). Most of the uranium mineralization occurs in a quartz-pebble conglomerate forming the basal member of the Mississagi quartzite."

Jan 1, 1949

By M. Krasowska, K. Malysa, M. Krzan

The paper presents fascinating, in our opinion, observations on mechanism and course of processes occurring during bubble collision with hydrophobic and hydrophilic solid surface. Hydrophobicity of particle surface is a necessary condition for the particle attachment to bubble. We have observed that even in the case of such hydrophobic solid surface as Teflon, the bubble attachment didn't occur at first collision. In distilled water the bubble bounced a few times without attachment. Influence of a-terpineol and n¬pentanol on bubble local and terminal velocity and the phenomena occurring during bubble collisions with hydrophobic and hydrophilic solid surfaces was studied. Bubble collisions with the solid surfaces were monitored and recorded using the high-speed (1182 frames per second) camera. It was found that in distilled water the velocity variations of the "approach-bounce" cycles were identical for Teflon and glass. Four distinct "approach-bounce" cycles were detected both at Teflon and glass surfaces. Moreover, the amplitude and frequency of the velocity variations were identical on collisions with the hydrophobic (polished) and hydrophilic surface. There was no immediate three phase contact formation, with the hydrophobic Teflon surface, what we found really astonishing. Roughness of Teflon surface seems to be important parameter, which affects probability of the bubble attachment as a result of a presence of micro-and/or nano-bubbles at the surface. It was detected that the presence of the micro-bubble affected attachment of the colliding bubble even in distilled water. Presence of a small amount of a-terpineol or n-pentanol affects dramatically the bubble velocity, but their role in mechanism of the bubble attachment needs further study.

Jan 1, 2004

By Duanyou Li, Qing Xiao, Zhiwang Wang, Xiaoqing Gan

"Seepage is a major cause of earth-rockfill dam failure. Numerical simulation of infiltration process, distribution of drift, flow velocity and direction after the impoundment can guide seepage control and evaluate its effects. A double field coupling model is established based on soil consolidation theory and the interaction between the seepage field and the temperature field. The simulation is implemented under the situation of core wall setted, core wall not setted, and core wall setted with concentrated leakage. The results indicated that the saturation line height was significantly reduced due to impervious core wall, and the temperature distribution is uniform above the saturation line. If concentrated leakage occurs, temperature distribution of dam was significantly changed, which is consistent with theoretical inference.INTRODUCTIONEngineering seepage field distribution must be calculated in seepage control design, optimization, and correction of new engineering construction of earth dams, as well as in seepage monitoring and evaluation of existing earth-rockfill dams. The aim of calculation is to identify the important parameters in seepage field, such as the coefficient of permeability, seepage flow, pressure, head, and allowable seepage slope, for effectively implementing seepage control design, correction, safety assessment, and anti-seepage reinforcement. These seepage parameters usually can be obtained by in-situ test and back-analysis based on reliable monitoring data.In order to obtain reliable monitoring data and reflect the earth-rockfill dam seepage state and change process, appropriate monitoring technology and monitoring method is necessary. The traditional seepage monitoring method is through site inspection and sensors (e.g., osmometer, piezometric tube and measuring weir) that buried in the structure and its foundation. However, there are still some disadvantages:"

Jan 1, 2015

By W. H. Moore

It seems necessary, at times, that we should reconsider some of the more obscure causes that lead to explosions of gas and coal-dust in mines, in the hope that a recapitulation will keep before us that old and true saying "eternal vigilance is the price of safety". This explosion, while not extensive (resulting in only two much to be regretted deaths) enlarged our vision as to the possibility and probability of other explosions with more disastrous results. As this is only a partial report I shall have to omit many things that are generally included in describing a mine explosion. The mine was worked exclusively with electric cap-lamps -only firebosses and other officials carried safety-lamps. All shots were examined and fired by firebosses with a small hand-battery. Monobel was used exclusively for blasting, and clay for tamping. The system of haulage iri use was main-rope and winches, horses being employed for gathering. Compressed-air was the motive power for all winches and pumps, excepting the pumps at the shaft-bottom which were steam-driven. The mine was wet with practically no dust anywhere, except what was being made at the coal-face in the getting of the coal. Gas was found occasionally, generally in the brushing, especially where the brushing was carried up to a small seam, 2 to 6 feet above the main seam. The place where the explosion took place was known as Leigh's heading, which was being driven to the rise, immediately inbye of the siding (off No. 1 left, off the new slope) and was about 90 feet up from the level.

Jan 1, 1926

By A. V. Tarasov

There are still a number of copper smelters in the world using the roasting and smelting process flow diagram for treating sulphide raw materials. The technical, economic and environmental performance indicators of such operations are inferior to the respective indicators of advanced processes. First of all with respect to copper and sulphur recovery: 95% and 75% as compared with 98% and over 90%, respectively. Based on the studies of the single-stage smelting process to produce white metal and blister copper conducted during recent years an analysis of the feasibility of roastingsmelting technology improvement was carried out in the Gintsvetmet Institute to substantially increase the copper and sulphur recoveries. On the basis of this analysis, it was proposed to modernize the technology and equipment within the framework of the existing process flow-sheet. The proposed modernization implies an increase in the roasting temperature; higher desulphurization degree in the process of roasting; a number of modifications in the roaster design depending on the particular conditions of a given operation; addition of lime flux to the feed charge to roasting; and transition to combined calcium-silicate smelting slags. The metallurgical and energy computations made have indicated that the proposed modifications of the technology will improve the copper and sulphur recovery up to 98% and 90%, respectively. The required capital investments have been estimated using as an example a particular copper smelter, the payback period determined taking into consideration additional output, fuel saving and a reduction in fines for sulphur emissions. For comparison, the capital cost of a smelter modernization is given for change-over to basically new autogenous Ausmelt, Outokumpu and V anyukov smelting technologies.

Jan 1, 2007

By C. Jay Hodgson, P. J. MacGeehan, T. Sanders

"The orebodies of the Campbell and Dickenson mines are localized within an anomalously fissile and deformed zone that transects the eastern margin of a dominantly mafic volcanic complex close to its contact with a synchronously formed sedimentary basin containing clastic and chemical sedimentary rocks. The ore zones are mainly quartz-carbonate fissure veins and siliceous replacement zones formed during deformation and metamorphism, although there are some syn-volcanic exhalative ore zones in the mines. On a regional scale, the volcanic rocks have been affected by syn-volcanic spilitic alteration which has involved the leaching of Fe, Mg, Au and As from, and the addition of Na and variable amounts of Si to bleached zones enveloping primary permeable structures in the rocks. The leached constituents were deposited on the contemporaneous sea floor as iron-rich chemical sedimentary rocks. Although this alteration is not closely related, spatially, to the ore zones, it is characteristic of the general environment, and may serve to distinguish gold-prospective from gold-barren areas on a mining-camp scale.Closely associated spatially with gold deposits is a zone of feldspar-destructive alteration within which the volcanic rocks are characteristically feldspar-free, enriched in As, Au and to a variable degree in Si, and depleted in Na, Ca and to a variable degree in Mg, Fe and K. The alteration zone is also characterized by abundant, variably transposed, small quartz-dolomite to ferrodolomite veinlets formed during deformation and metamorphism, and includes, but extends outside of, the anomalously fissile zone hosting the orebodies. The alteration zone is interpreted to have formed syn-volcanically within the upper part of a major submarine hydrothermal discharge zone."

Jan 1, 1982

By J. Aiello

"A brief history of previous mining activity on Coal Mountain, near Corbin, British Columbia, is followed by a description of the steps leading up to the resumption of mining in /974 by Byron Creek Collieries. New developments, including a preparation plant, a rail spur and a totally enclosed facility, as well as operating techniques, are also discussed. IntroductionThe Corbin Mine of Byron Creek Collieries Limited is located in southeastern British Columbia, approximately 110 air miles southwest of Calgary (Fig. I), 15 miles south of Highway 3 via a newly constructed provincial road (Fig. 2). Development of the area began on July 30, 1905, when D.C. Corbin, a prominent businessman from the northwestern U.S., and his associate E.J . Robert s, first visited the site of Coal Mountain on horseback. Coal was in great demand by railways and other industrial users, so the Corbin Coal and Coke Co. , after acquiring 15,000 acres of land in the area , began to develop a mine.F.J. Roberts was responsible for the construction of the 14-mile rail spur, the Eastern British Columbia Railway, which joined the mine to the CPR main line at the McGillivray Loop. Rail access to the mine and its developing community, Corbin, B.C., was completed in September 1908, the same year that the first underground mine began production.The Corbin Coal and Coke Co. operated six mines on Coal Mountain (Fig. 3), and production from 1908 to 1930 inclusive totalled 2,337,800 tons. This production was allocated to the mines as shown in Table 1. No.3, 4 and 6 mines were operated intermittently from 1931 to 1935."

Jan 1, 1980

By S. M. Bulatovic, D. M. Wyslouzil, K. R. Rawlings

"The suitability of a new organic reagent DS20 as a depressant for oxidized and carbonaceous pyritic lead-zinc ore from Nanisivik Mines Ltd. has been evaluated in the laboratory and in the plant.The depressant DS20 is a mixture of Lignosulphonate-Dextrin-Quebracho and was developed specifically for depression of highly oxidized and carbonaceous pyrite.The laboratory test work indicated that the poor metallurgy resulting from the oxidized ore could be improved to normal plant performance by the addition of the DS20 depressant with the existing plant reagents. The laboratory data suggested that lime consumption could be reduced when using DS20.In this paper, the development work and the plant trials with DS20 are described.INTRODUCTIONNanisivik Mines Ltd. treats approximately 2000 tonnes per day of lead-zinc massive sulphide ore, containing currently 1% Pb and 9% Zn. The concentrator operations have been described previously (1,2) and typical metallurgical performance is detailed in Table I.The concentrator flowsheet (Figure No. 1) and the standard reagent scheme (Table No. 2) demonstrate the relative simplicity of treatment of this coarse grained ore.A recently discovered satellite orebody - Area 14 - containing 2% Pb and 12% Zn was brought into production in October 1983. This ore had been oxidized to varying degrees by ground water; the pyrite mineralization was found to be very fast floating and a carbonaceous constituent present in higher than normal proportion also affected flotation. The simple high lime addition could not control the pyrite, and very low grade lead concentrates resulted; zinc metallurgy was also affected by this oxidized condition (Table 3)."

Jan 1, 1986

By Mark Richards

Highland Valley Copper is a large, open-pit copper mine in the southern interior of British Columbia. Reclamation has been in progress on the site since 1987. Some 6,300 hectares will have been disturbed at the end of the mine?s life, the majority of which will eventually be reclaimed. The establishment of vegetation and the development of a self-sustaining vegetative cover are the central components of the mine?s reclamation plan. The present vegetation-monitoring program for the reclaimed area represents a significant commitment of resources and only addresses a small portion of the site each year. In an effort to expand the area surveyed while improving the efficiency of the monitoring, the use of remote sensing is being investigated. Airborne multispectral imagery was acquired in the summer of 2001, and the results of the multispectral classification were compared to ground observations made during the routine 2000 and 2001 monitoring program. A thematic map with 17 vegetation classes was produced. Within the vegetation classes, there was a strong spectral separation between ? dry grasses? and ?legumes? with further separation according to their density. Green biomass could also be quantified remotely across a wide variety of vegetation types. During summer 2002, further aerial imagery was acquired in combination with a targeted ground-truthing program to determine characteristic vegetation types associated with recognized spectral signatures, which can be used in a supervised classification. It is anticipated that after some fine-tuning, it will be possible to shift the ground-sampling effort from areas where the aerial classification confidence is high to more complex areas.

May 1, 2003

By Jun Shan

The preparation of poly(N-isopropylacrylamide)-monolayer-protected clusters (PNIPAM-MPC) of gold nanoparticles was carried out in a homogeneous phase using three ways, in which three types of PNIPAM ligands were employed. The first type comprised of PNIPAMs with narrow molar mass distributions, synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and thus, bearing a dithiobenzoate at the chain end. These polymers were used directly to passivate the gold nanoparticles upon the Schiffrin reaction in a one-pot synthesis. The second type of ligands was derived from the first one through hydrazinolysis, and they therefore contained a thiol end group. The third type of ligands was PNIPAMs obtained through conventional radical polymerization, post-modified to contain thiol end groups. The PNIPAM-MPCs were characterized by high-resolution transmission electron microscopy, and by dynamic light scattering. The one-pot synthesis utilizing the ligands of the first type turned out to be a simple and facile method, compared with the other two ways, with which the size of the gold nanoparticles can be easily manipulated mainly by adjusting the molar ratios of PNIPAM / HAuCl4. PNIPAM is a more efficient ligand to stabilize the gold nanoparticles in water and in organic solvents than alkanethiols. The surface density of PNIPAM chains ranged from 1.8 to 3.6 chain/nm2, which is much lower than that typical for alkanethiols. The thickness of a PNIPAM monolayer bound to the gold core is somewhat larger than the size of the random coil of corresponding free PNIPAM in aqueous solution, which suggests that the conformation of a PNIPAM chain bound to the gold core is to extended.

Oct 1, 2003

By M. Phylli Bray

"Mining has the reputation of being a very ""macho"" industry. Recently, wider educational opportunities for women in nontraditional occupations and changes in mine technology have combined to make mining a viable career choice for women also. To benefit from this new resource, the mining industry faces the challenge of developing a different work environment from the one now burdened with sexism. Management supported initiatives are needed to facilitate such a transformation. The same rethinking of gender attitudes might also be extended to mining women in their traditional role as ""wife of"". The assumption that the male worker's wife is an unpaid adjunct is being questioned. It is suggested that women's separate concerns both as helpmate and as part of the mining workforce should be considered when planning for mining into the 21st century.IntroductionI must confess that, during the preparation of this paper, there have been many moments when I questioned my temerity. After all, I am not male, I am not an engineer, and I have never had a position in mine management. But as the wife of a mining engineer and a long-time resident of Northern Ontario mining towns, I do have an interest in the mining industry. This interest has had little to do with the technical and management aspects of the industry. Instead my research has been concerned with the impact the mining industry has on the people involved, particularly women, whether directly as employees or indirectly as wives. As I look toward the 21st century, I believe that the whole question of gender relations in the mining industry is one of the critical management issues smouldering below the surface."

Jan 1, 1995

By A. Ghahremaninezhad, E. Jorjani, A. Riahi, Islamic Azad University, B. Nazari, H. Hani, Z. Manafi

The presence of a high iron concentration, 9.1 g/L, in the raffinate of the Sarcheshmeh copper heap bioleach process led to the formation of various types of jarosite, (K,Na,NH4,H3O)Fe3(SO4)2(OH)6, on the heap mineral surfaces. This study probes iron removal from the raffinate using a bio-oxidation process based on A. ferrooxidans bacteria in the presence and absence of jarosite seed. The jarosite seed was biologically synthesized using A. ferrooxidans bacteria. The effect of solution pH (1.5 to 2.5) and jarosite seed dosage (0 to 15 wt.%) on iron removal was examined. It was demonstrated that the concentration of iron ions present in the raffinate decreased from 9.1 g/L to 2.5 g/L with the addition of 10 wt.% jarosite seed at pH 2 and 130 rpm mixing rate at 32°C. Three different types of raffinate including (1) native raffinate containing 9.1, 3.4, 5.7 g/L of total, ferric and ferrous iron, respectively, (2) bio-oxidized raffinate in the absence of the jarosite seed containing 8.5 g/L total iron (mainly ferric with negligible ferrous), (3) bio-oxidized raffinate in the presence of jarosite seed containing 2.55 g/L total iron (mainly ferric with negligible ferrous) were used in mesophilic, moderate thermophilic and thermophilic bioleaching processes. The results of the flask tests showed that the highest copper bioleaching recoveries of 9.4, 49.4 and 90.8 % were achieved using raffinate (3) with mesophilic, moderate thermophilic and thermophilic bioleaching processes, respectively.

Jan 1, 2016

By Keith C. Hendrick

"Metal prices are frequently the most critical and least predictable element in determining the profitability of mining operations. Short -term fluctuations can be offset in varying degrees by hedging or other market actions. Such solutions are not practical for the longer term, The paper investigates the nature and extent of metal price risks and evaluates methods to reduce them.IntroductionIt is management's responsibility to improve the odds by managing the-risks by identifying them clearly, assessing them accurately, minimizing them where possible-and, then, timing decision s success fully.In determining the profitability of current operations, preparing forward plan s or developing feasibility studies for new projects or expansions, pr ices are usually the most critical input. Being market determined rather than cost based, they can also be the most unpredictable As a result, commodity prices are frequently the greatest of all risk factors.Nature of Commodity PricesThe cyclical nature of commodity prices is well known. They are stable only when supply is in balance with demand and forecast to remain that way. An imbalance on either side of the equation can lead to a price reaction completely out of proportion to the actual or perceived surplus or shortage.This exaggeration arises through the cumulative effect of market forces. When the market senses an uptrend, consumers buy for the expected increase in activity. They also seek additional quantities for inventory before price s rise. Merchants defer spot sales anticipating higher price s, speculators go along for the same reason, and producers raise prices in response to demand. Events tend to confirm the expectation of each party and strengthen their reaction causing prices to move higher."

Jan 1, 1983

By J. Lebl, S. Bharti, D. J. Cornett

"This paper presents the design and application of blasthole mining to an area at Strathcona Mine previously employing post pillar cut-and-fill. Extensive mining in the area had led to gradually deteriorating ground conditions and post pillar stoping was no longer considered acceptable. Alternative methods had to be investigated.Conventional methods for mining in poor ground were rejected because of the high cost. Blasthole mining was selected because iI offered good productivity and safety with acceptable costs. The design of this approach involved field investigations and the use of numerical modelling to simulate the different blasthole options and their impact on ground stability. The blasthole design incorporated reinforcement with cablebolts, use of a radio-controlled remote LHD unit, large-diameter holes, blast design and wall control. Potentially unstable areas were outlined during mining with ground monitoring instruments and the results used to modify mining plans during the production phase.IntroductionIn underground metal mines there is a need to improve safety and productivity and lower mining costs in order to maintain reasonable rates of return on investment. This requires the application of good engineering design to both mine planning and ground control in order to optimize production and costs and to forecast potential problems during mining. The task becomes more important when extensive mining leads to gradually deteriorating ground conditions, making existing mining methods and techniques no longer acceptable from a safety point of view. Alternative mining methods must, however, be sufficiently productive to ensure profitability. This paper presents an example of the engineering design and operating approach used by Falconbridge in dealing with such a situation at Strathcona Mine."

Jan 1, 1983

By Laszlo Imreh, Pierre Trudel, André C. Tessier

"The Siscoe gold mine is ranked as the fourth largest mine in the history of the Val d' Or mining district with a total production of 27.4 tAufrom1929 to 1949. Most of the gold mineralization occurred in quartz veins, hosted in a small (.69 km2) intrusion of altered quartz gabbro known as the Siscoe stock. The southern contact of the Siscoe stock is crosscut by a major shear zone (the ""K"" zone) trending 295/80 NE and from which gold mineralization was also exploited within the limits of the stock. Field and petrographic observations of the Siscoe stock combined with chemical analyses of major, trace and rare earth elements of the stock and its volcanic host rocks (Dubuisson Formation) suggest that:The Siscoe stock comprises four alteration facies formed from a homogeneous precursor: 1) the actinolite - Mg-chlorite facies, characterized by low FeOt,Na2O andTiO2 , and highAlp3 and MgO; 2) the albite- Fe-chlorite facies, containing high concentrations of FeOt and Nap; 3) the Mg + Fe-chloritefacies, which is transitional between the actinolite- Mg-chlorite and albite- Fe-chloritefacies; 4) the carbonate-chlorite facies, which consists of rocks that were subjected to extreme hydrothermal alteration, is spatially associated with mineralized veins and part of the K-zone. The first three facies are depleted in SiO 2, CaO and Au, and enriched in MgO, relative to fresh rocks of the Siscoe stock and the equivalent rocks of the Dubuisson Formation.Hydrothermal fluids introduced mainly along the K-zone ""channelway"" induced three types of element remobilization, resulting in the various alteration facies: 1) redistribution of elements within the stock from one facies to another (e .g., FeOt, Nap, Ti02 migrated from the actinolite- Mg-chlorite facies to the albite- F e-chlorite and Mg + Fe-chlorite facies); 2) remobilization of elements from the intrusive rocks into veins (e.g ., SiO 2 and CaO ); 3) introduction of elements by hydrothermal fluids in rocks of the Siscoe stock (e .g., Al2O3, MgO, H2O, CO2 and FeOt).The Siscoe stock and the Dubuisson Formation form part of the same tholeiitic suite. Similarly, the Bourlamaque batholith and the Val d'Or Formation belong to a single calc-alkaline suite. In view of this relationship, dissimilarities between the petrochemistry of the Siscoe stock and the Bourlamaque batholith suggest that the two intrusions are not co-magmatic.Finally, gold may have been leached from rocks of the Siscoe stock and remobilized into the quartz-carbonate mineralized veins. In order to account for the total production at the Siscoe mine, approximately 1.2 km3 of the Siscoe stock is thought to have been partially leached of its gold."

Jan 1, 1990

By V. I. Ryaboy, S. A. Kondratyev

"The paper describes influence of desorbed species (DS) of a number of xanthates and higher dialkyldithiophosphates on the collective ability of these reagents. Adsorbed on mineral DS of the reagents in the form of products of non-stoichiometric interaction between xanthates and heavy metal salts can pass to the gas–liquid interface and remove liquid from the layer between mineral particle and water surface. A high-speed video recording displays the process of spreading of DS of xanthates and dialkyldithiophosphates over water at the moment of local rupture of the water layer. Expansion of “dry” spot on the mineral surface after DS of xanthate capture and displace liquid from the layer has been proved with video images. The comparative analysis of collecting ability and dynamic surface activity of dialkyldithiophosphates shows that these characteristics are in good correlation. The forces exerted by spreading film of the reagent’s DS on liquid in the water layer are evaluated, and the water flow rate from the layer is determined. The line of the reduction in thickness of the water layer behind the front of spreading film of DS of dialkyldithiophosphates and xanthates coincides with the line of the increase in their dynamic surface activity. Their force on the liquid volume in the water layer characterizes collecting ability of the DS film of xanthates and dialkyldithiophosphates. It has been supposed that the collecting ability of DS of a reagent is a part of its overall flotation activity, conditioned by surface tension of solution and, thus, defined by the structure of hydrocarbon fragment of the reagent.INTRODUCTIONIt is believed that collecting ability and selectivity of collecting reagents is mainly governed by adsorption of a reagent at the solid–liquid interface. A few studies have shown that activity of collecting reagents at the gas–liquid interface may have deep influence on their collecting capacity and selectivity. Experimental researches have revealed correlation between surface pressure in a carboxylic acid film on liquid’s free surface and floatability of useful components (Kulkarni & Somasundaran, 1975; 1980; Quast, 2006). According to Quast (2006), it is not always that surface pressure of a reagent film influences collecting ability of carboxylic acid. For instance, pH range of adsorption of tetradecanoic acid on hematite does not coincide with pH range of high surface pressure. So, surface properties of this acid contribute little to flotation efficiency.The correlation between reagent film surface pressure and mineral floatability has been reveled for quartz and cationic reagents, too (Bleier, Goddard, & Kulkarni, 1977). Finch & Smith (1973) showed that combination of adsorption of ion–molecular amine complexes on mineral surface and high surface tension of “fresh bubbles” was favorable for flotation performance. The use of bubbles with reduced surface tension resulted in a decrease in quartz floatability."

Jan 1, 2016

By Q. Shi, Q. Feng

"The influence mechanism of chlorite on the flotation of pyrrhotite was investigated through flotation tests, Zeta potential measurements, optical microscope photos, solution ion measurements and absorption measurements. It is observed that, the addition of chlorite influences the flotation of pyrrhotite seriously. The IEP (isoelectric point) of pyrrhotite and chlorite is 7.6 and 4.3 respectively, in the condition of slight alkalinity, both pyrrhotite and chlorite are negatively charged, and the hetero-aggregation will not occur. With the existence of oxygen in solution, the iron ions are dissolved from pyrrhotite surface because of the oxidation of pyrrhotite during pulp conditioning. The dissolved iron ions adsorb onto the surface of chlorite in the forms of iron hydroxyl and iron hydroxide, and the adsorption results in the opposite charge of chlorite surface. As a result, the hetero-aggregation between pyrrhotite and chlorite occurs. The adsorption of chlorite changes the surface property of pyrrhotite and restricts the adsorption of amyl xanthate onto pyrrhotite surface, and then decreases the flotability of pyrrhotite.INTRODUCTIONIn sulfide ores processing, magnesium silicate bearing gangue minerals often report to the concentrate causing downstream processing problems as well as increased smelting costs. Talc,chlorite and serpentine are gangue minerals commonly encountered in complex sulfide ores (Engel, Middlebrook, & Jameson, 1997; Pietrobon et al., 1997; Witney & Yan, 1997; Chen, Grano, Sobieraj, & Ralston, 1999a, 1999b; Bremmell, Fornasiero & Ralston, 2005; Senior & Thomas, 2005; Wang, Somasundaran, & Nagaraj, 2005; WieseHarris & Bradshaw, 2007). All of them are characterized with uniform crystal structures consisting of silicon-oxygen tetrahedron and magnesium-oxygen octahedron. The magnesium-oxygen octahedron layers are broken during the liberation of serpentine to expose the magnesium-oxygen bonds with strong ionicity and hydration, which results in natural hydrophilicity of serpentine. In water, the hydroxyl on serpentine surface ruptures and dissolves into the aqueous phase while the Mg2+ remains, resulting in surface positive charge (Tao, 2012). As serpentine has a positive potential at alkaline condition, it is therefore likely that it will attach through electrostatic attraction to the negatively charged mineral surface and reduce both the flotation rate and recovery of target minerals (Lu et al., 2011). For talc, characterized as good natural hydrophobicity, the liberation comes from the interlaminar fracture to remain molecular bonds on surface with weak hydration. Being naturally hydrophobic, talc easily reports to flotation concentrates, thus reducing concentrate grade (Shortridge, Harris, Bradshaw, & Koopal, 2000; Beattie, Huynh, Kaggwa, & Ralston, 2006). Meanwhile, both molecular bonds and magnesium-oxygen bonds are exposed on chlorite surface when liberation occurs, resulting in moderate natural hydrophobicity between serpentine and talc (Tao, 2012). And thus the mechanisms of influence of chlorite on sulfide ores are more difficult to study."

Jan 1, 2016

By K. Thuro, S. Schneider, H. Kasling, P. Ellecosta

"One of the most important methods for material testing is the characterization of the hardness, which is defined as the resistance of a material to the penetration of another one. The methods according to Brinell, Vickers, Rockwell and Knoop are today the most common and standardized tests for metal. As they are developed for predominantly ductile materials like steel, they can’t easily be applied to rocks which react much more brittle under indentation. But just as steel, rock is composed of different minerals and has a specific microstructure. Its mechanical parameters are connected with the particular grains, their cohesion and interlocking, just like steel.The abrasivity of rocks and the accompanied wear of drilling tools today are mainly determined by simple and fast laboratory tests such as the Cerchar abrasivity test or the rubber wheel test. Such laboratory tests are good tribological tests, but there are limits. The Cerchar abrasivity test for example has weaknesses in extreme cases, that mean soft or very hard rock types. This leads to an underestimation of abrasivity, e.g. in poorly lithified sandstones or very hard, fine grained and extremely abrasive rocks. As mentioned, hardness characterizes, depending on the type of deformation, predominantly plastic (metal) or elastic properties (rubber). Rocks are in the range between these two extremes. Since the rock drilling process can be seen as a kind of penetration process on macroscopic and microscopic scales, we picked up the idea to characterize the interaction of rock materials and TBM-disc-cutters with hardness tests. In addition, this supports for a better understanding of the wear process on disc cutters. We used the hardnessdisparity concept after Cardu & Giraudi (2012) because wear can be understood as the interaction between the wear part and the material which causes the wear (tribological system). Several rock-forming minerals and some fine to coarse-grained monomineralic and polymineralic rocks were tested. In contrast to Cardu & Giraudi, we used in the first step of investigations the method after Vickers with loads up to 294.2 N (HV 30), depending on the estimated hardness to get bigger indentations and therefore as well information about the cohesion and interlocking of the minerals/grains. We also tested several associated disc cutters. First results show that with higher loads (HV 5 - 30) and at least 15 indentations, we get a structural hardness in fine-grained rock samples, which allows a good characterization of the elasticity and brittleness. Nevertheless, for the coarse-grained rock samples we need up to 40 indentations for a good characterization. Using this method, a prediction of disc cutter wear is feasible taking into account the hardness of the disc cutter steel. In this paper, we would like to present this approved method in material sciences to derive an additional parameter for the characterization of rock abrasivity and wear."

Jan 1, 2015