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By B. Fang

Electrochemical behavior of an X-80 pipeline steel, including frequency-sweep electrochemical-impedance spectroscopy (EIS), time-sweep EIS at a constant frequency and open-circuit potential (OCP) monitor, was investigated using four-point bending specimens subjected to a stress-corrosion cracking (SCC) test in a near-neutral pH environment, The capacitive loop became smaller with test duration, revealing an increase in the corrosion rate, The resistance obtained in the constant-frequency EIS test showed two regions, of which the region with a remarkable decrease in resistance transformed into a region of slow decrease, whereas the capacitance increased with test time indicating that iron dissolution was fast at first, and then a corrosion product or film formed and covered the surface, leading to the pitting formation.

Jan 1, 2005

By E. Gaucher, M. St-Amant

"Among the electromagnetic surveys performed by SOQUEM in the last three years, a certain number of the more instructive cases have been chosen to illustrate the theory of electromagnetism by field examples of: (a) The depth penetration of the TURAM as compared to the SLINGRAM (Ronka) method. (b) The limitations of the TURAM as compared to the SLINGRAM method when a conductor dips the wrong way, or when it is small in size. (c) The expression of a shallow-dipping conductor in a SLINGRAM survey. (d) The effect on the SLINGRAM survey of deep ditches or reef structures.(e) A comparison between the CRONE and the SLING-RAM method in the Abitibi clay belt, by means of field and model studies, indicating a usually better signal-to-noise ratio for the SLINGRAM method. From the above and from other experiments, different electromagnetic methods are now being used by SOQUEM, depending on field conditions."

Jan 1, 1970

By M. Tsesarsky, M. Hazan, E. Gal

"Rock masses comprised of stiff inclusions in softer matrix are common in various geological environments. The heterogeneity and multi-scale nature of these materials make the evaluation of their mechanical properties a challenging task, which cannot be accomplished using conventional laboratory tests and composite mixture rules. We employ the homogenization method to estimate the mechanical properties of geological materials with inclusions. The homogenization method solves the equations of elasticity on the material (microscopic) scale for a unit cell subjected to unit strains under periodic boundary condition. The micro-scale elasticity equations are solved using the Finite Elements Method, and are in turn used to obtain the structure scale (macroscopic) material matrix.In this research, Finite Element models for unit cells with spherical and ellipsoidal inclusions were developed. Using the unit cells, a parametric study of the geometrical and statistical microscopic properties of the material composites was performed. The following parameters were studied: volumetric ratio, Young’s modulus ratio, size-distribution of inclusion and inclination angle of inclusions. The main purpose of the parametric study was to study the deviation from isotropy as a function of the aforementioned parameters.It was found that for volumetric ratio of 5%-40%, the deviation from isotropy increases, as the volumetric ratio of inclusions increases. For spherical inclusions, most of the cases studied exhibit quasiisotropic behaviour; whereas ellipsoidal inclusions exhibit considerable deviation from isotropy. The inclination of the ellipsoidal inclusions enlarges the deviation from isotropy (9% at random orientation and 26% at 0°)."

Jan 1, 2015

By Raymond S. Suglo

Increasing depths of mining coupled with the mechanization of most underground mining operations have led to growing complexities in the mine environments with the production of large amounts of gaseous and particulate contaminants. Over 100,000 lives have been lost due methane gas and dust explosions in coal mine workings in both the US and Canada since 1900 when the methane concentrations exceeded stipulated levels in some workings. There is therefore the need to constantly assess and evaluate the performance of the existing mine ventilation systems to maintain safe and acceptable mine environmental conditions in workings to meet the requirements of federal, state or provincial laws. This paper uses the results of continuous monitoring of methane concentrations conducted in selected development headings in coal mines in North America to assess the effectiveness of existing auxiliary ventilation systems in the control of methane gas concentrations in the headings. The results show that the average quantities of fresh air required to dilute, disperse and remove methane concentrations within set levels of one minute varied from 5.43 m3/s in Heading #11 (Condition 2) to 27.97 m3/s in Heading #10 (Condition 1) and this represented about 12 to 26% of the quantities required to dilute methane concentrations to safe levels within one minute under Condition 1 and 32 to 139% under Condition 2. The average dilution times in the headings studied were less than 8 minutes. The forcing efficiencies of the auxiliary systems in the headings studied ranged from poor to excellent implying that the auxiliary ventilation systems were capable of controlling the methane concentrations below statutory levels but may not be able to cope with large and unusual methane concentrations in the headings. This study is important to prevent methane gas and coal dust explosions in coal mines and thus avoid any loss of lives and property.

May 1, 2001

By Karina Forster

Open stope design depends on the ore body geometry, loading conditions and rock mass properties to estimate stope dilution and ground support requirements. Rock mass conditions for design primarily rely upon estimates of well established rock classification systems. Many sources of data exist for obtaining estimates for these rock mass classification values which include core logging, geotechnical mapping, geological mapping as well as linking one classification system to another through the use of empirically derived equations. The extent of mapping coverage can also vary significantly based on the data collection technique. This paper proposes an approach where individual components of rock mass classification systems are collected by the different available data collection techniques. Data from different rock types are also considered separately based on their alteration characteristics and general observation products. Data from the Cameco Corporation Eagle Point Mine is presented and an approach is outlined for obtaining average representative classification values for stope hanging wall characterization. The effectiveness of this approach is demonstrated through the analysis of a data base of hanging wall dilution information.

Jun 1, 2012

By C. H. Lee, T. T. Wang

"Exampling of the tunneling task in the Tsengwen Reservoir Transbasin Diversion (TRTD) in southern Taiwan, this study investigates the application of the Drilling Survey System (DRISS) in both Drilling and Blasting (D&B)- and Tunnel Boring Machine (TBM)-excavated sections. In the D&B section, a nonlinear relationship exists between drilling energy and uniaxial compressive strength of rock mass, in which a reasonable coefficient of determination can be analyzed statistically. Additionally, the DRISS accurately predicted an unfavorable section with a valuable position. The magnitude of uniaxial compressive strength back calculated using DRISS data also matches those acquired from geological investigations with different approaches. Study results indicate that the DRISS is an effective tool for fore-probing of both D&B- and TBM-excavated tunnels. INTRODUCTIONModern advancements in geological and geophysical investigations, and drilling techniques, have provided valuable information for detecting and interpreting geological conditions of rock tunnels with a resolution of several to ten of meters (Brückl et al., 2001, 2008, Lorang et al., 2005). Nevertheless, construction risks remain considerable during tunnel excavation, especially when a tunnel was excavated by a Tunnel Boring Machine (TBM). Predictions of the local fault, shear zone, and other minor geological features, which may cause moderate collapse or excessive deformation of rocks surrounding the tunnel, before tunnel excavation is highly desirable for high-quality tunnel construction and economically efficient project management.Rather than conventional geophysical prospection methodologies, which always favor large-scale investigation with moderate precision, this study focuses on the drilling method probing ahead of a tunnel. The goal of such an investigation is not only to prevent catastrophic collapse, but also to provide quantitative or semi-quantitative information for estimation of the mechanical parameters of rock mass.For the tunneling task in the Tsengwen Reservoir Transbasin Diversion (TRTD) in southern Taiwan, a drilling survey system is adopted for fore probing. Data collected from both drilling and blasting (D&B) and TBM-excavated sections are analyzed statistically and discussed. The applications of the Drilling Survey System (DRISS) are addressed accordingly."

Jan 1, 2015

By R. E. Evans

This paper contains an analysis of the geography and geology of the Black Lake area, Eastern Townships of Quebec, an outline of the work to be performed, an explanation of the design concept and how it was developed, and a discussion of the actual stripping operation, including details of the machinery being used, etc.

Jan 1, 1967

By A. Allaire, J. Torrealba-Vargas, R. Welyhorsky

Early testwork was carried out to select the plant process design criteria and flowsheet selection. Additional testwork was carried out during the feasibility study to support the optimization of the plant design criteria. The test results showed that the recovery of gold was not very sensitive to grind size in the range of 75 to 105 microns. An additional result was that the presence of lead nitrate did not improve the kinetics of gold leaching. This conclusion was supported by the low content of sulphides in the ore. It was also found that the presence of lead nitrate increased copper dissolution, producing the potential for an increase of copper reporting to electrowinning, which is detrimental to the overall gold recovery process. The use of oxygen in leaching was investigated to increase leach kinetics. The results of leaching tests to compare using oxygen instead of air indicated that, due to the improved leach time, it was possible to reduce the number of leaching tanks from twenty four (24) to twenty (20).

Jan 1, 2011

By Andrew Barnes

The adsorption capacity of peat collected from a proposed mine development in northern Sweden has been determined using laboratory column experiments in which peat was irrigated with a simulated (acidic) waste rock dump leachate. The simulated leachate was made using a hydrogen peroxide leach of composite waste rock from the proposed mine development. The waste rock samples were composited in proportion to their predicted extractable tonnage for the mine development in order to generate a more representative leachate solution for the waste rock facility. As expected the test revealed that the peat material shows a very high affinity for attenuation with greater than 70% of Co, 90% of Ni and 95% of Cu removed from influent solutions through the majority of the tests demonstrating the potential benefits in mine water treatment. In contrast, it was found that Fe is initially released from the peat at concentrations up to 100 mg/L and can mean potential problems for the water released depending on the receiving environment. The exact mechanisms for Fe release is uncertain, though it is suspected that ion exchange / competitive desorption is responsible. Inspection of the laboratory results and drainage data from the natural peat wetland receiving drainage during overburden prestriping and mine development at the mine site are comparable, confirm the validity of the experiments, and further emphasize the potential for future use of pre-stripped peat material in managing water quality.

Aug 1, 2013

By M. Sanchez

In the last decades, the Chilean copper mining and metallurgical industry have had to modify their technological processes to meet the environmental regulations implemented by the Chilean government, and also to support the pressure of the public opinion. Thus, air quality standards for sulfur dioxide and particulate matter (primary and secondary), plans for reducing emission of arsenic by the Chilean copper smelters, effluents discharge limits, among others regulations were applied by the environmental agency. Additionally, agreements on cleaner production were carried out by mining sector and government. Now, a draft law on mine closure, and another on environmental mining wastes (abandoned mines) are being discussed by the authorities and the mining sector. In the context, production and environmental impacts in different ways to produce copper in the Chilean mining industry are reviewed and regulatory tendencies as well as abatement technologies today used are exposed and discussed in this presentation. Pyro, hydro and electrometallurgical processes employed and their current effluent and contaminants are presented showing various alternatives of treatment in the copper industry. An update of regulations established in Chile vis a vis copper production, with an especial attention to mine closure are also presented.

Jan 1, 2007

By T. Y. Chong, J. A. Folinsbee

Since milling began in 1909, the PJV Dome mill has been expanded several times, to the current throughput of 11,500 tonnes per day. PJV recovers free gold using crushing and grinding followed by gravity concentration. The remaining gold in the gravity tails is recovered by cyanide leaching followed by Carbon-In -Pulp processing. Prior to 1993, cyanide tailings were impounded in the tailings pond where cyanide was allowed to degrade naturally. Effluent was discharged seasonally during the summer and early autumn to maintain the water balance. In 1993, an Effluent Treatment Plant (ETP) was designed and constructed for the purpose of removing dissolved metals and suspended solids. In 1997, an INCO SO2/Air cyanide destruction process was added to the ETP. Even though the ETP was successful in meeting the cyanide, metals and total suspended solids (TSS) discharge limits, often the treated effluent failed to pass toxicity tests. Following successful laboratory and plant scale testing, the addition of the chelant EDTA (ethylene diamine-tetra-acetic-acid) was commenced in the 1999 operating season. To date, discharged effluent has passed all toxicity tests. This paper describes the evolution of the ETP from its early conception to the various phases of upgrade needed to meet the MISA discharge limits.

Jan 1, 2005

By T. Krumins, F. C. Ruff, M. Eichhorn, L. Zunti

Hatch Ltd. has recently completed a project to increase refractory gold ore processing capacity at Newmont Mining Corporation’s Twin Creeks facility. The objective of the project was to increase throughput by approximately 10% by adding a third autoclave feed pump to each of the two autoclave circuits. To minimize project capital cost, autoclave feed pumps from Newmont’s decommissioned Lone Tree facility were evaluated and found to be suitable for this new service. The existing pressure oxidation circuit was reviewed in a debottlenecking study to determine other upgrades required to facilitate the increased throughput. Interruption to operations was minimized with a detailed construction plan, supplemented with detailed 3D layout model sequencing studies. The focus of this paper is project development, multi-discipline design considerations, and implementation results.

Jan 1, 2014

By G. P. Gu, B. Fang, R. W. Revie, M. Elboujdaini

Stress-corrosion cracking (SCC) tests were conducted in the near-neutral pH standard solution, NS4, and in an actual soil solution, using four-point bending at high a stress ratio and low frequency conditions very similar to those of operational pipelines. Pitting incubation appeared first and then pitting initiated and grew in both solutions although there were many more pits on the specimen tested in soil purged with 5% CO2 + 95% N2 than in the specimen tested in NS4 solution purged with the same gas. These observations show that samples in soil solution are more susceptible to pitting than those in NS4 solution. When the pit reached a critical size, the increased stress concentration around the pits, resulted in the transition to a crack.

Jan 1, 2005

By H. Itou

A mechanism of scorodite formation at ambient pressure was investigated using transmission electron microscopy (TEM). Several types of iron arsenate were obtained from Fe/As solutions (Fe/As = 1.0 and 1.5) at pH values of 1.0, 1.25 and 1.5 at 95°C. Amorphous FeAsO4.xH2O was precipitated from solutions having a higher mole ratio of Fe/As at pH l.5, even after 9 hours. A few micron sized particles were observed by SEM, but these proved to be agglomerates of 10-50 nm amorphous FeAsarxH2O particles when observed by TEM. This means that supersaturation of the solution causes the acceleration of nucleation of iron arsenate hydrate. Crystalline scorodite was obtained from a solution in which the Fe/As mole ratio was unity, at pH l.0 and pH 1.5, after 3 hours. Almond-type crystalline scorodite particles were observed by TEM and most of them showed high crystallinity. The addition of scorodite seed material enhanced the crystallization. Amorphous FeAsO4.xH2O, however, was observed at the surface of the seeds during the early stages of precipitation. It is postulated that crystalline scorodite is not directly precipitated even on crystalline scorodite seeds, but requires a certain time to crystallize on the seed material.

Jan 1, 2006

By J. P. Nicoud

"The Frog's Leg project is located in the Kundana mining centre 22 kms West of Kalgoorlie, in Western Australia. The Mines and Resources Australia (MRA) Dioro Exploration Joint Venture has had considerable exploration success centred on the high grade Frog's Leg discovery. A gold resource of 930,000 ounces has been defined. At Frog's Leg there have been three discrete resource domains recognised - Supergene, Contact, and Quartz Lodes. This paper describes the metallurgical test work undertaken.The selection of the drill core was a joint effort by the MRA Senior Geologist and Mineral Engineering Technical Services (METS) to ensure the samples were representative of the ore body. Optimisation of gold recovery was essential as both the Contact and Quartz Lodes have exceptionally high percentages of free gold as well as significantly higher grades than the typical open pit ores found in Western Australia. The metallurgical scope of work included documenting all of the metallurgical test results, establishing the comminution characteristics, determining the percentage of gravity recoverable gold, evaluating the cyanide leach characteristics and determining the tailings characteristics. These studies were used as the basis of flow sheet design to treat both ores and to discuss the advantages and disadvantages of alternative flowsheets. Investigations also included toll milling options at various plants as well as second hand and transportable plants. Considerable technical effort has been put into ore characterisation by way of test work aimed at managing the process risk at each stage of project development, including mitigation. MRA also carried out detailed mineralogical analysis of the ores."

Jan 1, 2005

By Gwenaële Petit, Ulan Massimkhanov, Gilles Joubert

For its Zuuvch Ovoo uranium deposit in Mongolia, Badrakh Energy (partly owned by Orano Mining) is working on the prefeasibility study for exploitation by ISR (in situ recovery). As part of this project, Orano built a 2-cell (each cell is constituted of one producer well located in the center and surrounded by six injection wells in an hexagonal pattern) and a processing pilot plant that will be used to demonstrate the operability and economic viability of an ISR process. Another main objective of this pilot trial is to demonstrate the ability of Orano’s modeling tools to predict the ore behavior under given leaching conditions. To model uranium production by ISR, Orano uses HYTEC, a reactive transport computational software, which was adapted for its existing operation in Kazakhstan (Katco) to predict uranium recovery and reagent usage based on operating conditions. In order to perform similar simulations for this new deposit, Orano engaged in a comprehensive program including ore sampling, detailed characterization, and metallurgical testwork. The mineralogical conclusions were used to prepare a simplified geochemistry for the ore, in particular carbonate and reactive clay grades, uranium mineralization and penalizing elements such as pyrite. Then, bottle roll leach tests were used to characterize dissolution kinetics for smectite clays. Eventually, column leach test results such as pH, free acid, and uranium recovery were modeled on HYTEC to improve the fit of some of the dissolution kinetic parameters. Parameters fitted using metallurgical test work results will now be used as inputs for predictive model at the pilot scale, in order to anticipate operational results and help with operating decisions for production ramp up.

Jan 1, 2020

By Ashley Tews

In 2005, we automated a forklift-based Hot Metal Carrier to be capable of typical metal transfer operations around a smelter. The project was highly successful and the vehicle has demonstrated hundreds of hours of live autonomous operations to thousands of people from industry and the public. As a result of the exposure and success of the project, we have expanded its focus to demonstrate how various technology components can be utilised to gain benefits in other areas of industrial operations. These include asset tracking, vehicle usage analysis, pedestrian detection and infrastructure profiling. Each of these components was derived from the core autonomous vehicle technology suite and has shown a high potential for improving safety and efficiency of vehicle-related operations, and improved diagnostic processes for measuring deformations of bakes and furnaces. The autonomous vehicle project and its extended technologies are described in this paper.

Aug 1, 2013

By H. Yoshida, H. Hatta, T. Suzuki

"The effect of the copper and magnesium contents and quenching rate during quenching on the age hardening behavior of 2000 series aluminum alloys was investigated. For the higher copper-containing specimens as conventional alloys, like AA2024, precipitation of the stable phases increased as the quenching rate decreased under the as-quenched conditions. The maximum hardness after the artificial aging of air cooled(AC) specimens was much lower than that of the water quenched(WQ)specimens. On the other hand, for the lower copper-containing specimens, coarse precipitation did not increase even in the case of the AC. The age hardening behaviors of the WQ and AC were very similar such that the maximum hardness and aging rate were almost the same. Many parts of the fine precipitates that increased the hardness were thought to be the GPB zone or fine S’ phase for the WQ and relatively coarse S’ phase for the AC. From the calculated CCT(continuous cooling transformation)diagrams, the lower copper-containing specimens could maintain the copper and magnesium in the solid solution state during the AC, so they could be quenched at a rather slower quenching rate like the AC.INTRODUCTIONThe 2000 series aluminum alloys, containing copper and magnesium as the major chemical components, are some of the well-known heat treatable aluminum alloys. These alloys have a high quenching sensitivity, thus the age hardening ability of these alloys decreases with as low quenching rate. To prevent the decrease of the age hardening ability, quenching is done by a method such as water quenching, which is not very efficient in an industrial situation, because the method requires such large equipment. For these alloys, reducing the quenching sensitivity helps them to be produced in a rather convenient way. For example, 6000 series alloys such as A6063 have low quenching sensitivity, thus they could be quenched by only air cooling just after extrusion and they do not need water quenching. Based on these reasons, investigations of these alloys with high copper and magnesium contents have been conducted in the past to find a way to lower the quenching sensitivity by adding transition elements such as manganese, chromium and zirconium (Kanno, Suzuki, & Itoh, 1986; Suzuki & Itoh, 1986; Kanno, Sakuma, Muromachi, & Watanabe, 1988). However, very few studies have focused on the quenching sensitivity of the lower copper and magnesium containing alloys because of their usage for structural components with high strength, and most of the past studies have used only the fast quenching method like water quenching. On the other hand, from our recent results, there is a possibility to lower the quenching sensitivity of 2000 series alloys with lower alloying elements. In this paper, the effect of the copper and magnesium contents with lower alloying elements and quenching rate, especially in case of slower quenching rate than conventional quenching method, on the age hardening behavior of the 2000 series alloys is investigated by the hardness measurement, structure observation and thermal analysis."

Jan 1, 2018

By PAULL. BROUGHTON

Commercial deposits of sodium sulphate are harvested from alkaline lakes that are widespread throughout semi-arid southern Saskatchewan and adjacent southeastern A lberta. Concentration of sodium sulphate occurs in undrained basins under semi-arid conditions. Precipitation runoff from land adjacen1 to 1hese basins leaches 1he mineral from the soils and carries it in solu1ion 10 the basins. The process may be largely subsurface, wherein spring seeps feed basins associated with buried (preg/acial) river valleys. Evapora1ion during summer concentrates salts in the brines, and chilling of water below sa/Uration poin1 during win1er resu//s in deposi1ion of sodium sulpha1e (mirabili1e) crystals on lake bo//oms. Sodium su/pha1e, commercially known as sa/1 cake, ranks second only 10 po1ash in cen1ral-wes1ern Canada's nonme1allic mineral production. // is recovered from su,face brines, directly from intermittenl salt beds, and, until recently, by solution mining of shallow subswface deposits. Sodium sulphate is extrac1ed from seven alkaline lakes and sail f/a1s in Saska1chewan and one in Alberta. Annual produc1ion is approxima1e/y a halfmillion tonnes. Manufacture of kraft paper is the mos1 significanl marke1 for salt cake, but addi1ional quantifies are used in the glass and detergent manufac1uring indus1ries.

Jan 1, 1984

By Simon C. Dominy, Alwyn E. Annels, Paul Wheeler, Suzanne P. Barr, G. Simon Camm

Narrow veins are an important world-wide source of silver, tin, uranium and particularly gold. To potential ?nanciers, this style of mineralization is viewed as high risk because of the often relatively small resource involved and high cost of estimation. In many cases diamond core drilling will not enable resource estimation beyond the inferred and indicated categories. Exploratory under-ground development is required to de?ne measured resources. The de?nition of geological and grade continuity are major factors in narrow vein assessment. A measured resource must be based on strong geological and grade continuities. Narrow veins, generally less than 3 m wide, are complex geological phenomena, which commonly display unpredictable geometry and grade distribution. Variations in structural continuity, dip, strike, width, mineralogy and speci?c gravity are common. Veins may be composite, with ore-grade mineralization restricted to a speci?c structural domain. Branches, intersections and braided zones are common features. Potentially high-grade zones are often localized within ore shoots, which are surrounded by barren/low-grade regions. Resources must be determined as closely as possible to reality and re?ect the distribution of the commodity in the rock. Estimation has three main requirements: (1) geological study to determine orebody nature;(2) estimation of tonnage and grade, and (3) the presentation of this information using a classi?cation that is clear, unambiguous and bankable. Estimation methods employed are either classical or geostatistical; however, classical methods are often used because of the dif?culties in applying geo-statistics. Grades generally show a strong positively skewed distribution testifying the presence of high-grade values. Problems exist in the applicability of cutting outlier values risking over- or under-estimation of grade. It is generally believed that where resource estimates are in error, poor geological control is usually the cause. Overestimation can lead to the closure of a mine through lost revenue and capital. An understated estimate can result in an opportunity missed for pro?t and/or greater economies of scale. De?nition of reserves involves the consideration of economic and engineering data, to decide which part of the resource is economically mineable. Geology plays a similarly important role at this stage in the assessment of likely mining method, dilution, recovery etc. Throughout resource/reserve estimation, it is crucial that the amount and quality of the data and the geologist’s experience are relevant. The impact of geological understanding on estimation is often undervalued or assumed to be of lesser importance than ?nding grades and tonnages. This paper discusses the geology of narrow vein deposits and the importance of geology in their evaluation.

Jan 1, 1997