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By Stanley G. Butcher

Predictions of coal cleaning plant performance from the washability data are traditionally used at the conceptual design stage of a coal preparation plant to confirm process selection. The development of computer programs which simulate the operation of a plant facilitates the optimization of product yield and quality, and ultimately proceeds. It is shown that the optimum is sensitive to changes in mine operations and market price structure. A computerized review of operations is thus recommended as an on-going activity .

Jan 1, 1979

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 F. Kitzinger

Electromagnetic testing of wire rope has become more and more reliable over the past two decades. This improvement is partly a result of an unprecedented progress of electronic technology, which permitted the development of a new breed of testing instruments. There are two basic methods for the electromagnetic testing of wire ropes, the AC method and the DC method. Both methods rely on magnetic field disturbance caused by mechanical anomalies in the rope structure. The wire rope under test is passed through a magnetic excitation field, which can be a weak alternating field or a strong static field. Because the alternating field is produced by an alternating current, these instruments are of the AC type(l). In the early days of ND-testing, strong permanent magnets were not yet available; therefore, the static magnetic field was produced electromagnetically with direct current. Instruments based on static excitation are still called DC instruments(2), even though the field is now produced by a permanent magnet. Both these methods have certain characteristic features. The AC method can detect loss of metallic area caused by corrosion or other effects, whereas localized faults such as broken wires are better detected by the DC instruments . The basic principles of the wire rope testers have remained unchanged over the years and the improvements present in the new instruments usually reside in the signal processing and recording sections. The Instrumentation Department of the Noranda Research Centre* has been involved in a four-year development program which resulted in a new type of wire rope tester, the Magnographv** . This new instrument in many ways represents a considerable departure from the traditional wire rope testers. The Magnograph has already been patented in Canada and the U.S.A.(3), and patent applications are pending in other countries.

Jan 1, 1979

By Norman O. Lotter, André R. Laplante

"The pursuit of concentrator surveying for purposes of metal accounting or process optimization has not yet connected with the well-published realm of geostatistics. The reality of lognormality in time has seldom been discussed. One publication by Krige, 1962, examined such effects for a gold concentrator in South Africa, towards an information system that would provide feedback to the mining and surveying teams on grade control of ore mined.During present studies which are designing and testing a new survey model, called statistical benchmark surveying, it was found that the distributions of feed, concentrate and tailings bear significant residual signs of the parent lognormality in space. The multiple hosting of paymetals in different mineral species complicates the understanding of these distributions. These features have to be recognized and treated in order to perform appropriate quality control on the diagnostic sampling performed in the pursuit of statistical benchmark surveying.It is shown in this paper that the above two features can actually be used to advantage in the diagnosis of continuous periods of operations data ahead of such surveying, including the estimation of recoverable paymetals in flotation tailings from a graphical method.INTRODUCTIONAssessment of Concentrator PerformanceMilling and flotation, sometimes accompanied by gravity separation, are well-established unit processes, which have traditionally been used to treat ore that has been mined. This is because these processes liberate, then separate, the valuable minerals, which contain paymetals, from host gangue. This is often done by a combination of crushing and grinding processes, or autogenous grinding, to liberate the paymetal minerals, followed by gravity separation and/or flotation, to separate these valuable minerals into a concentrate, or several concentrates. These concentrate(s) have a lower bulk than the parent ore from which they are derived. Further, they contain a high percentage of the valuable minerals. Accordingly, they are more economically treated in subsequent beneficiation processes than the ore from which they were produced."

Jan 1, 2005

"HPGRs operate in a wide array of applications in mining and minerals. These range from relatively coarse crushing of copper and gold ores at one end of the spectrum to the processing of fine iron ore pellet feed and fine industrial mineral products at the other. Traditionally these circuits involve the treatment of relatively moist materials in pre-grinding circuits; using single stage HPGRs in open circuit or as a closed circuit operation with screening or partial product recycle. More recently, HPGR is increasingly deployed in dry grinding in combination with air classification. The high throughput demonstrated by larger HPGRs has stretched the application towards coarser size reduction duties for a number of new projects. At the same time, the basic principle of inter-particle crushing for generating a product with a high fines proportion gives ground to investigate applying the technology further towards finished product duties. The advantages that HPGR brings are clear. Multi Stage grinding enables energy efficient size reduction across more of the comminution circuit. Primary HPGR serves for a coarse grinding duty, whereas a secondary HPGR is geared towards generating a fine product for downstream processing or even a finished product. This publication summarizes some of the features of staged HPGR circuits and discusses some examples of operating and projected applications.INTRODUCTION In most HPGR applications, the grinding units are used as a single process stage, either in open circuit, such as for pebble crushing [Rose 2002, Westermeyer 2000, Van der Meer 2015] or in closed circuit with classification [Van der Meer 2009, 2012] or product recycling [Van der Meer 2010]. Where a higher plant capacity is required, the HPGRs are commonly installed in multiple lines in a parallel arrangement [Parker 2005, Koski 201, Vanderbeek 2006]. HPGRs can take a wide range of feed size distributions, and grind this down to a product with a high fines content. In general view, there is a limit on the size reduction range that even an HPGR can provide. Grinding down from a very coarse ore (e.g. 70-100 mm) to a very fine product (e.g. 100 microns range) is stretching the ability of a single stage HPGR circuit. Fine grinding generally requires a classification stage that returns the classifier oversize to the head of the HPGR circuit. From one point of view, it can be demonstrated that when recycling a large proportion of fines and middlings back to the HPGR feed results in an effective feed with an overrepresentation of middlings and fines, which will eventually reduce the grinding efficiency and consequently result in an increased recirculation mass flow [Van der Meer 2014]. From another point of view the large recycling mass puts a strain or even a limit on the capacity of present-day conveyor capacity."

Jan 1, 2018

By P. Brad Marchant

"To properly evaluate bioleaching as a commercial alternative for sulphide concentrate oxidation, to enhance cyanidation response, it was necessary to define and optimize critical operating variables outside of the laboratory under less than ideal conditions. A complete bioleach testing laboratory was installed at Equity Silver Mines to aid in pilot plant flowsheet development.A continuous pilot scale bioleach circuit was constructed to provide data for meaningful valuation of biotechnology on a plant scale. The important operating and design parameters for pilot plant testing are described. Plant scale feasibility and design considerations, to treat a refractory pyrite/arsenopyrite concentrate produced from flotation tailing, are discussed. 1.0 BACKGROUNDEquity Silver Mines Limited is located 37 km southeast of Houston in central British Columbia. A 70% owned subsidiary of Placer Development Limited, Equity is Canada's largest open pit silver producer. Ore reserves were estimated at 28 million tonnes grading 106 g Ag/t, 0.96 g Au/t, and 0.38% Cu from two pits, the Southern Tail and the Main Zone. Detailed geology and mineralogy has been described previously(1,2).The concentrator flowsheet consists of conventional crushing, grinding, flotation, and dewatering circuits processing 5 300 tonnes per day of new mill feed. The resultant Cu/Ag/Au concentrate is trucked to Prince Rupert for shipment to market. Mill tailing reports to a closed circuit pond from which mill process water is recycled. Details of the concentrator process have been reported( 2,3).Production in the Southern Tail pit, from July 1980 to March 1984, resulted in mill tailing averaging 0.9 g Au/t and slightly more than 20 g Ag/t. Historic data indicate that unrecovered gold is associated with arsenopyrite and silver losses with unliberated tetrahedrite or minor silve,, bearing sulphosalts. Main Zone mill tailing, which commenced production in March 1984, contains approximately 0.5 g Au/t which is probably associated by majority with silver bearing minerals and pyrite while silver losses, 30-40 g Ag/t, are associated with unliberated silver and antimony bearing minerals."

Jan 1, 1985

By Zhong Zhang, Xijia Wu, Prakash C. Patnaik

"The integrated vehicle health management (IVHM) aims to provide life cycle management decisions for military platforms and their propulsion systems with reduced life cycle cost and increased operational readiness and safety. Among all the issues of IVHM, understanding the physics of failure and predicting lifetimes of the critical components are at the core: the decision makers have to know when and how components may fail in order to plan ahead. The difficulties to tackle failure problems lie in determining the material response to cyclic and dwell loading in a hot and/or corrosive environment, which all combined to induce multiple deformation and damage mechanisms, resulting in mix-mode failures. Decisions on component replacement (material substitution) and mission planning must be based on quantitative knowledge of the failure physics to mitigating the risk. This paper addresses the critical failure issues including creep, low cycle fatigue (LCF), thermomechanical fatigue (TMF); and presents a mechanism-based approach to life prediction. The mechanism-based approach, by its physics, is widely applicable over the entire operational spectrum of both structures and engines, and therefore is suitable for IVHM purposes."

Jan 1, 2015

By P. Garritsen, J .. A. Blanco, M. C. Bell

"By 1994, Inco Limited will lower sulphur dioxide emissions from the Copper Cliffsmelter by 60% to 265 000 tonnes/year, primarily through implementing two key process changes. First, new milling technology will permit economic rejection of additonal pyrrhotite prior to smelting. Second, a bulk coppernickel concentrate will be oxygen flash-smelted, thereby eliminating the existing multi-hearth roasters and reverberatory furnaces . All copper will be recovered in the matte separation plant as a nickeliferous chalcocite, and will be oxygen flash-smelted for blister production. This paper outlines the development of the project and describes the process, including the flash furnaces, new sulphuric acid plant and additional oxygen plant.IntroductionInco 's SO2 Abatement Program will lower sulphur dioxide emissions at Sudbury from the current levels of 685 000 tonnes per year to 265 000 tonnes per year by 1994 as required by Ontario' s countdown on acid rain regulations.It is the high tonnage of sulphur mined that creates the magnitude of the SO2 emission problem at Sudbury. At a production rate of 240 million pounds of nickel per year, Inco mines 12 million tonnes of ore. At 10% sulphur it mines 1.2 million tonnes per year of sulphur. If Inco did not fix any of this sulphur it would be emitting 2.4 million tonnes per year of sulphur dioxide-about as much as all other Canadian emissions. Today, however, Inco is already fixing 70% of the SO2 in ore, in several ways : mostly as sulphur in pyrrhotite rejected to tailings in the milling operations; as acid from the roasting of pyrrhotite and some nickel concentrate at the Iron Ore Recovery Plant (lORP) and some as liquid S02 from the copper flash smelting furnace. By fixing 70% of the sulphur the current allowable SO2 emission levels of 685 000 tonnes per year is met. Total sulphuric acid production is currently 450 000 tonnes per year and in fact, the 10RP operation is being continued only to maintain established acid markets.Historically emissions have been reduced from the 2 000 000 tonne per year level to the current level of 685 000 tonnes per year by rejecting pyrrhotite from the smelter feed, and 70% of the SO2 containment problem at Sudbury has already been addressed.While Inco's profits are large at current nickel prices, most people have forgotten that back in 1982 Inco was losing a million dollars a day. Inco did make a dramatic response to this economic stimulus. The Ontario Division increased productivity by 65% and lowered costs to become the lowest cost nickel producer."

Jan 1, 1990

By J. M. Ortiz, J. Haas, W. Kracht, G. Pamparana

This work explores the effect of ore hardness variability on the design of a solar photovoltaic system with battery storage and grid backup, to operate a semi-autogenous grinding mill (SAG). First, a case of two synthetic ore populations was studied, without any consideration of spatial distribution. The mean and variance of the ore hardness (measured in specific energy consumption) of both populations were subjected to a sensitivity analysis. The operation was evaluated with one and two stockpiles. The latter allows classifying according to ore hardness to adapt the SAG energy consumption to the solar cycle. The results show that using two stockpiles allows achieving a larger autonomy (i.e., fewer energy imports) at lower total costs, especially when the difference of mean hardness between the two populations is large. The difference in variance (between the two populations) has a smaller impact on the design recommendations. Second, a case study was performed considering the spatial distribution of geometallurgical units. Two cases were considered: (a) brownfield, when there is historical information of the actual variability of the ore hardness; and (b) greenfield, when the system design relies mainly on geometallurgical modeling. Brownfield and greenfield planning result in similar sizing recommendations of the solar power plant if precise drill cores are available. In this case, geometallurgical modeling is an effective tool for forecasting the energy demand necessary for designing the power plant. INTRODUCTION Solar energy can help make mining more sustainable (Moreno-Leiva et al., 2017). With falling battery costs, an autonomous solar supply is soon to become an economical alternative in many parts of the world, even in the presence of a larger power grid (Child et al., 2017). Although this, places with high solar radiation such as the Atacama Desert in Chile, nowadays show a large potential of incorporating solar energy as a supply of energy. Many of the Chilean copper mines are in this zone making it interesting to study their compatibility and potential of integrating this renewable source to their operation. The power demand in a copper mineral processing plant is determined by the main power loads in grinding and flotation, with grinding typically the largest power consumer, especially the semi-autogenous grinding (SAG) mills (Wei and Craig, 2009). In Chile, it corresponds on average the 50% of the electrical energy consumption (COCHILCO, 2013). Solar energy production is determined by the irradiance perceived into the solar photovoltaic (PV) panels (which varies through the geographic location) and several other climatic parameters such as the current season, humidity, temperature, altitude, and others (Molina et al., 2017). Also, solar energy is only generated during the sun hours, getting to a maximum generation at a certain peak hour during midday, and finally dropping to zero during the night. This shows a cyclic parabolic profile as shown in Figure 1. Due to the SAG mill operated continuously, the power supply always must be available. During the night, to continue supplying the energy, it is necessary to complement the solar power generation with a battery energy storage system (BESS), which will act as a power backup and a buffer. For the optimal sizing of this PV- BESS system, information of the demand profile is needed (Pamparana et al., 2017). In the case of the SAG mill operation, the resulting demand relates to the ore-hardness for a specific throughput and grind size (Morrell, 2004). Therefore, for a given throughput and target grind size, a harder ore would require more power, and variable hardness results in more variable demand and a subsequent need for larger energy storage (Bueno et al., 2015). Due to the ore-hardness variability and the operation of the mill, the power demand profile in inherently variable.

Jan 1, 2019

By Hämäläinen M., O. Hyvärinen, E. Jääskeläinen

HydroCopperTM is a new hydrometallurgical process for the treatment of copper sulphide concentrates, which has been developed by Outokumpu. The process includes chloride leaching of copper concentrate, solution purification and precipitation of copper(I) oxide, an intermediate product, which is reduced and cast into copper products. The reduction can be carried out by pyrometallurgical methods or hydrometallurgically in an autoclave. This paper discusses the thermodynamic and kinetic aspects of the hydrogen reduction of copper(I) oxide in an autoclave. The results of the laboratory tests are presented and discussed. Finally, the autoclave method is compared with other options.

Jan 1, 2004

By P. Erskine

"Hyperaccumulator plants can be utilized as ‘metal crops’ in agromining operations. This emerging technology produces ‘bio-ore’ by growing ‘metal crops’ on sub-economic ore materials, such as natural ultramafic soils. In a typical application plant material is periodically harvested, followed by air-drying and incineration to produce the bio-ore intermediate. The bio-ore is of very high grade (>15 wt. % nickel), and of high purity, and may be processed into a number of different products (including nickel metal, nickelbased catalysts and pure nickel salts). Current research efforts from our team focus on Mediterranean climate field trials (Albania, Spain) and tropical climate field trials (Malaysia, Indonesia). Field-scale demonstrations are required to provide evidence of real-life performance and of economic viability. If the trials are successful, agromining may in the near future support local livelihoods with income opportunities as an alternative type of agriculture: to farm nickel.INTRODUCTION AND BACKGROUNDHyperaccumulators, plants with the exceptional ability to uptake and concentrate trace elements in their shoots, can be utilized as ‘metal crops’ in agromining operations (Van der Ent et al., 2013a; Chaney et al., 1998; 2007; Baker et al., 2010). Agromining produces ‘bio-ore’ from harvested ‘metal crops’ grown on unconventional resources such as natural ultramafic soils (Van der Ent et al., 2015a). The bio-ore is a high purity and very high-grade (>15 wt. % nickel) product intermediate that may be turned into a range of different nickel products (nickel metal, nickel-based catalysts and pure nickel salts). The potential for agromining is greatest in tropical regions (Asia-Pacific Region: Indonesia, Malaysia, Philippines, Papua New Guinea and New Caledonia) where very large expanses of ultramafic soils exist (Van der Ent et al., 2013b). Agromine operations may replace existing marginal agriculture on poor ultramafic soils, for example oil palm plantations that require high fertilizer inputs to be profitable, or take place under a cocropping regime. The ability of ‘metal crops’ to achieve high nickel concentrations in biomass (and hence in harvested bio-ore) from soils with just <0.5 wt. % nickel, makes it possible to access non-conventional resources, not accessible by traditional mining techniques. For example, agromining could be implemented both on the large ‘halo’ around the mine leases, and as part of the progressive rehabilitation process after conventional resource extraction. As with all methods for resource extraction, agromining will be finite due to the diminishing concentrations of nickel in the zone accessible by plant roots (Chaney et al., 2014). Nevertheless, considering soil materials with 0.2 wt. % nickel and ‘metal crops’ with a yield of 100 kg nickel ha-1 the agromining venture may be sustainable for decades (Van der Ent et al., 2015a)."

Jan 1, 2016

By A. T. Robles, L. Buckingham

"When certain gold ores containing pyrite, graphite, humates and fumates or other organic compounds which are possibly adsorbed on clay minerals are treated with aqueous solution of alkali metal cyanide, the aurocyanide complex which forms is adsorbed by these ""pregrobbing"" species in the ore. Dissolution of gold proceeds until chemical equilibrium is attained between the cyanide complex adsorbed by the ore and in solution.Sodium lauryl sulfate (SLS) may be used to decrease the adsorptive activity of the prerobbing species in the ore. It has successfully improved recovery at Holt-McDermott Mine and is highly biodegradable.INTRODUCTION Precious metal-bearing ores containing preg-robbing species are poorly amenable to standard cyanidation techniques. The ""preg-robbing"" impurities with which they are associated tend to adsorb the gold cyanide complexes and carry them through the circuit to the tailings. Also, gold may be associated with these impurities in the ore and not be leached by the cyanide complexing agents used in conventional cyanidation techniques.Methods for dealing with the problem of preg-robbinq impurities in gold ores are:Carbon-in-Leach (CIL), in which granular activated carbon is added to compete with preg-robbing species for the gold cyanide complexes. This process can improve gold recovery in mildly preg-robbing ores especially when fine carbons with very high activities are used. However, with severely graphitic ore, the carbon associated with the rock may outperform the granular activated charcoal.Chemical Oxidation, in which the ore is subjected to preliminary chemical oxidation techniques to oxidize carbonaceous materials using such diverse reagents including ozone, sodium hypochlorite, calcium hypochlorite, chlorine gas, permanganates, perchlorates, chlorates and oxygen prior to subjecting the oxidized ore to standard cyanidation treatment to extract gold. This is generally a costly method and will not prove economical on a low-grade ore."

Jan 1, 1992

By P. Chollet, A Constant

THE RESULTS of a previous investigation ( 1) on the work-softening of some heat-treated steels have led to the conclusion that the occurrence and intensity of the phenomenon is possibly governed by the work-hardening capacity of the material, and the relative amount of retained austenite. The first assumption is compatible with Polakowski's theory (2) that the absence of work-softening, in steels quenched and tempered at relatively low temperatures, may be attributed to the high rate of work-hardening which compensates for, and even out-weighs, the loss of internal energy associated with the simultaneous rearrangement of the original system of internal stresses. Indeed, Polakowski first considered the work-softening as a manifestation of a partial release (by cold-working) of the latent strain energy stored in

Jan 1, 1962

By Joël P. T. Kapusta, Liam J. Watt

The last extended copper smelting and converting survey dates back to the 2003 International Copper Conference held in Santiago, Chile. The following year, the Minerals, Metals, and Materials Society of AIME (TMS) started a new series in its Journal of Metals (JOM) called JOM World Nonferrous Smelters Survey devoting its first Part to Copper. The copper smelting landscape has significantly changed in the past 15 years, both in geographical terms with the shift of copper smelting production from the Americas to China and in technological terms with the growing adoption rate of Top-Submerged Lancing (TSL) technologies and the development and implementation of Bottom-Blowing technologies. A copper smelting survey update, even if not as in-depth as the 2003 Copper Smelting Survey, is therefore in order. The authors will review the latest trends in copper smelting technologies and production worldwide in comparison to the landscape of the early 2000s. INTRODUCTION This 2019 copper smelting survey is different from previous surveys as our data does not originate exclusively from responses to a questionnaire sent to all the copper smelters. Our data comes from several sources. We are therefore very thankful to the International Copper Study Group (ICSG) and Wood Mackenzie for sharing some of their information and to ENFI, Outotec, and Glencore Technologies for helping us cross-check our numbers for the Chinese smelters, flash smelting, Ausmelt, and Isasmelt technologies. Our survey presents data reporting from a total of 96 operating copper smelters from around the globe, which is significantly higher than the 50 surveyed in 2003. Although secondary smelting numbers have steadily increased over time, this paper focuses on primary smelting operations with copper concentrate as feed material. The list in this survey is still far from complete, with missing information from several known smelting operations. The total primary copper production tonnage of the smelters we surveyed amounts to 18.3 million metric tonnes from 29 countries representing 92% and 94% of total world primary production for 2018 estimated by ICSG and Wood Mackenzie, respectively. This representation has increased from 2003 when the total was 9.71 million metric tonnes from 23 countries accounting for 73% of world production. The trends presented and analyzed within this paper have stronger significance because of the increase in production accounted for. The Chinese and Russian smelter information collected is more detailed than years past. Our complete dataset is summarized in Table 1 at the end of our paper.

Jan 1, 2019

By E. F. Evoy

"The Gunnar uranium deposit was within metasedimentary rocks of the late Archaen Tazin Group. These rocks were intensely altered by albitization so that the immediate host to the ore consisted dominantly of albite, and by the subsequent introduction of calcite. The ore consisted of disseminated pitchblende and uranophane in a pipe-shaped breccia zone. Oxidation of the ore was more intense near surface than at depth, but there was no near-surface enrichment.IntroductionThe Gunnar Mine site is on the tip of Crackingstone Peninsula, on the north shore of Lake Athabasca, Province of Saskatchewan, Canada. The peninsula forms the southern part of the Beaverlodge mining area. The ore consisted of disseminated pitchblende and uranophane in brecciated metasedimentary rocks of the Tazin Group, and the deposit was characterized by extreme albitization and subsequent carbonatization of the host environment.Production from the mine began in 1954 and the ore was depleted by 1963. In that interval the deposit yielded about 5 million tonnes of ore containing about I. 75 kg/tonne U3O8. It was mined initially from an open-pit and subsequently from underground; the open-pit contributed about 55% of total tonnage. Uranium was recovered by atmospheric leaching in sulphuric acid, ion exchange concentration, and precipitation with magnesia.This paper is based on studies made during the productive life of the mine and is concerned primarily with pre-ore alteration of the rocks containing the deposit, and with the ore mineralogy."

Jan 1, 1986

By T. Belem

In-stope backfill will cure under effective stress, which develops due to a combination of mechanical consolidation (free draining material) and ??chemical consolidation?? (self-desiccation mechanism). A good knowledge of all the drainage and consolidation characteristics of cemented paste backfill is crucial for a better design of underground backfilling sequencing. From many of the existing results and studies done by various authors, as well as the availability of some in-stope backfill pressure data measurements during and after filling, it is possible of developing a procedure of backfilling sequencing. Hence, the objective of this study is to provide a guide for underground backfilling sequencing in the view of preventing the development of excess pore pressure that will affect both the stability of the barricades and the strength development of the backfill. This will be possible by considering the interaction between consolidation/drainage rate, filling rate and binder hydration rate.

Aug 1, 2013

By J. Baz-Dresch

"The most cost-effective method of placement of the high strength fill used in the Cannon Mine&apos; s overhand cut-and-f ill bench stopes was determined to be truck haulage. Constraint s imposed by the mine layout dictated the use of a truck which could dump its load in a fifteen-foot high drift. The Dux Teledumper truck was selected as the most suitable unit for this application based upon operational and maintenance parameters which included a telescoping, tilting dump box; large load capacity; and robust construction. Development of the truck continues through the cooperation between the manufacturer and user. INTRODUCTIONThe Cannon Mine is situated in the centre of Washington state, approximately midway between the cities of Spokane on the east and Seattle on the west. The mine complex is located three block s south of the Wenatchee city limits at the eastern base of the Cascade Mountain range.Asam era Minerals (U.S.) Inc., with 5I% ownership, operates the Cannon Mine. Breakwater Resources, Ltd. holds the remaining 49%.Annual paroduction is 520 000 tons per year, presently on a 21-shift per week operating schedule for both the mine and the mill.All production is presently won by overhand bench stoping with backfill. Stoping starts with 15-ft high by 24- or 30-ft wide sill cuts driven above and below a stope block . A drop rai se and slot are used to open a bench which is then slabbed toward the open slot. Truck-placed backfill is dumped into the mined - out stope from the upper sill cut. This stoping sequence is repeated until the top of the ore block is reached . The top sill cut is then tightly filled with backfill to minimize subsidence and to provide adequate roof support during extraction of the pillars.Mining equipment consists of hydraulic drills and rubber-tired, diesel scoops and trucks."

Jan 1, 1989

By D. A. Livingstone

"INTRODUCTORY REMARKS BY PANEL CHAIRMAN - D. A. LIVINGSTONEThe mining industry has progressed significantly from the dusty mines and mills of decades past to the modern processing complexes of today, and improved technology has made great strides in eliminating debilitating lung discuss. More recently, the public's environmental awareness is also working to enforce more stringent regulations and controls in tl1e matter of dust in working places.There are numerous excellent texts and handbooks outlining the principles of collection of dust produced in the various unit operations entailed in the crushing, screening and the transport of ore. However, it is painfully obvious that dust emanating from belt return idlers and scrapers, take-up pulleys, skirting, larger and deeper chutes, clean-up operations, etc., which I choose to refer to as fugitive dust, presents some seemingly unmanageable difficulties, or at least difficulties inordinately costly to correct. Possibly static electricity is adding to the difficulties. In my view, these problems are magnified in many of our B. C. operations where ore from open pit mines in cold climates is frequently crushed in unheated buildings, thereby precluding the simple and obvious use of water sprays for dust suppression.It is hoped that the presentations and discussion which follow will emphasize some of these unusual problerr.s and suggest corrective measures, either tried or planned."

Jan 1, 1976

By J. L. Collins

"This paper deals with the quantitative analysis of mine maintenance records. Based on a case study of dozer engine records, the author suggests an easy method of deriving useful information for managerial decisions in a step-by-step manner.More specifically, the paper deals with the following topics:• determination of the most economical replacement time,• determination of reliability characteristics,• determination of the number of replacements, and• determination of the number of spares.IntroductionThe mining industry collects a lot of information about every aspect of its activities, an example of which appears in Table I. In Table I , the distribution describes the operating hours at failure of 56 different dozer engines used in severe applications. Besides calculating an average and possibly a standard derivation from the data, little else is derived, at least from a statistical point-of-view.More information can be obtained from these records that could help management in the decision-making process.To illustrate this point, the sample data appearing in Table I will be analyzed in detail by making use of well-known concepts in reliability engineering.Distribution of DataTable I represents a distribution obtained from the recorded hours cumulated from the operators&apos; time cards. The operating hours have been divided into fourteen classes for each 1000 hours of engine running, e.g . all engines scoring an operating time of between 1001 and 2000 hours formed a class , those scoring between 2001 and 3000 hours another one, etc. Generally, the class interval should be a multiple of the equipment preventive maintenance check period.The minimum acceptable sample size should be large enough to ensure that the score in each class interval is at least one. Ideally, the score for each class interval should be at least five so that a chi-square test could be carried out if necessary.The average life of an engine can be found by adding the products of the frequency and the class mark (mid-point) values. Therefore:"

Jan 1, 1987

By Emile D. L. Rienks

We have studied the interaction of NO with the quasi-hexagonally reconstructed Au(100) surface. Using variable temperature scanning tunneling microscopy we have observed formation of the unreconstructed phase of Au(100) after NO exposure. This NO adsorption induced phase transition is observed in a window of temperatures around 170 K. Under the same conditions, CO and O2 cannot drive the phase transition, suggesting weaker interaction. Thermal desorption spectroscopy experiments provide an estimate for the strength of NO chemisorption on Au(100) of 57 ± 4 kJ mol-1.

Oct 1, 2003