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By L. Gutierrez, M. Pawlik

The rheology artificial mixtures of bitumen with fine quartz of varying bitumen content, as well as actual oil sand ores, was investigated under different physicochemical conditions (pH, temperature). All rheological measurements were conducted using a Haake Rotovisco VT550 rotational viscometer, connected to a fixture specifically designed to measure properties of settling suspensions. It was found that at low bitumen contents (1 %, wt.) the pH of the slurries was the most important parameter that controlled the rheology of quartz-bitumen slurries. At higher bitumen contents (10%, wt.), it was a combination of high temperature and high pH that gave the lowest apparent viscosities and yield stresses of the model mixtures. These model observations correlated well with the rheology data obtained for slurries of actual oil sand ores. The overall results were discussed in terms of aggregation-dispersion phenomena between bitumen and mineral particles.

Jan 1, 2009

By G. Anger, J. Enser, H. Antrekowitsch, S. Koch

Homogeneous chemical composition and microstructure are always necessary, but not always attained in practice. As-cast aluminium alloys tend to have a segregation microstructure. Features of the cast structure, which affect subsequent processing or properties, can be altered by the homogenization. The main task of the Department of Nonferrous Metallurgy was to investigate the effect of homogenization treatment on precipitation hardening of aluminium alloys 6061 and 6082. The effect of the solution heat treatment (SHT) temperature on the mechanical properties was also analyzed. The homogenized and non-homogenized rolling slabs were produced according to the usual conditions and methods. The metallographic investigations were carried out on the as-cast samples, after homogenization, after the hot and the cold rolling mill, and after natural and artificial ageing. Then, Brinell hardness measurements and tensile tests were conducted on both alloys in order to examine the influence of the homogenization.

Jan 1, 2006

The rate of liquid copper deoxidation during top blowing of reducing flames has been investigated using a high capacity thermogravimetric unit at 1200 °C. For 1 kg copper samples, it was observed that the rate of deoxidation was proportional to the flow rate of the reducing reagent (H2 or CO). Under similar experimental conditions, it was found that H2 is more effective than CO even though both have similar thermodynamic potential to deoxidize liquid copper. The rate of deoxidation of liquid copper with reducing 0 2/CH4 flames was measured for 0 2/CH4 molar ratios of 1.5 to 2. The deoxidation rate depends on the 0 2/CH4 ratio and decreases as it approaches the stoichiometric ratio (02/CH4 = 2). Estimation of the rate of deoxidation of liquid copper with top blowing flames based on the thermodynamic composition ofH2 and CO in the product gases, agrees well with measured values.

Jan 1, 2007

By Guoxiang Chi

This paper consists of two parts: the first part describes the principles and functionality of the BsnMod program, and the second part presents preliminary application of this program to paleo-fluid flow modeling in the Anticosti Basin. The BsnMod program simulates fluid flow and heat transfer during the evolution of sedimentary basins through numerical solution (finite difference method) of three partial differential equations, which describe sediment compaction, fluid continuity, and heat conservation. It can be used to estimate the evolution of fluid overpressure, flow rate, and temperature during the basin history. The program was written in C++, works under Windows environments, and has a user interface allowing inputs in dialogues and outputs in both tabular and graphic forms. The program was applied to the Lower Paleozoic Anticosti Basin in eastern Canada. The basin history consists of a passive margin stage and a foreland basin stage. Preliminary simulation results indicate that no significant fluid overpressures were developed in the passive margin stage and during the early period of the foreland basin stage, but strong overpressures were developed within the foreland basin succession during the middle and late periods of the foreland basin stage. Fluid flow rates were generally slow, and thermal profiles were not significantly disturbed by fluid movement throughout the basin history. Potential source rocks of hydrocarbons were found in the foreland basin succession. The strong overpressures in the foreland basin succession could have been a major driving force for hydrocarbon migration from the source rocks to the underlying potential reservoir rocks.

May 1, 2001

By Parissa Mirjafari, Ron Martel, Susan A. Baldwin, Luke Moger

Mine drainage contains metals and sulfate, which may be toxic to aquatic life at certain concentrations and should be removed to acceptable levels before release of any drainage to the environment. One method for treating mine drainage is passive treatment, which is increasing in popularity due to lower construction and operating costs. This method is based on the activity of sulfate reducing bacteria (SRB) respiring on sulfate while using fermentation products from decomposing complex organic materials. The product of this biological process is hydrogen sulfide, which reacts with metals in mine drainage and precipitates them as metal sulfides. However, in practice passive treatment systems are not always effective, reducing the reliability of this approach. In this study, a mixture of hay, cow manure and wood chips was tested in continuous flow experiments for efficacy at sustainable treatment of sulfate and selenium containing water from a mine tailings pond. Factors that contributed to a decline in performance included lowering of the pH due to acids leaching out of the organics, re-oxidation of sulfide back to sulfate and a reduction in dissolved organic compounds over time. In this paper methods are described to overcome these problems so that treatment is made more reliable.

Jan 1, 2011

By V. Aprahamian, G. B. Harris, C. W. White, M. Tangen

"In 2005, the Royal Canadian Mint (RCM) commissioned a new silver electrorefining circuit. This circuit was intended to operate with a minimal electrolyte bleed for the control of copper. However, by the time of start-up, the levels of copper-rich silver doré to electrorefining had increased, and despite partial pyro-conversion in a small Top Blown Rotary Converter (TBRC), copper concentration in the silver anode still averaged 7.5%. This necessitated frequent replenishment of the electrolyte with fresh silver nitrate since copper displaced dissolved silver during electrolysis, and therefore requiring a robust copper bleed treatment step in order to maintain cathode silver flake purity at 99.99%. The originally-installed bleed treatment system could not meet the RCM’s needs. A thorough review of known technologies, however, did not indicate one capable of handling the copper load, and resulted, therefore, in the development of a novel copper hydrolysis approach for removal of copper as an insoluble basic nitrate salt, and recovery of the associated nitric acid for re-use in the circuit. Laboratory-scale trials showed reproducible results, and existing equipment was subsequently modified.INTRODUCTIONIn 2005, the introduction of a new silver electrorefining circuit at the Royal Canadian Mint (RCM) initiated changes in the way customer silver, collected from the gold doré circuit, was processed. These circuit changes were discussed in a recent paper (Aprahamian, 2015). A wastewater treatment plant had not been budgeted at the time, and this represented a significant constraint when considering the introduction of a wet processing circuit. After a review of various options, a turnkey silver electrorefining circuit was purchased from a European firm. Initially, enough cells were ordered to produce 2 million oz of fine silver (999), with the option to increase to 5 million oz. The selected equipment was based on a Moebius cell design combined with a silver grain pressure dissolver to produce make-up silver nitrate solution. Additionally, an evaporator/hydrolysis unit included in the package appealed to the Mint Refinery, on the basis that it offered a simple way to bleed dissolved copper in electrolyte without generating effluent."

Jan 1, 2016

By Muhammad Zaka Emad

Cemented rockfill (CRF) is a mixture of rock aggregate and binder slurry. It is a stiff backfill, it is fast curing, its operation is simple, placement rate is reasonably high and no drainage is required. The main demerit of CRF is failure of exposed faces causing ore dilution, which can be associated with the fill placement method. This paper discusses the effects of two placement methods being practiced by mines and numerical modelling is used as a tool to evaluate stability of the backfill column. In the first method, practiced in longitudinal retreat mining of a narrow vein deposit, the rockfill is hauled and dumped into the stope with a LHD scooptram. Once dumped, cement slurry is sprayed into the stope. In the second method, a raise situated centrally above the mined stope is used to convey already mixed CRF into the stope. Stopes are mined out transversely in primary and secondary blocks in a sublevel stoping system. Problems of poor mixing in combination with both placement methods are discussed. The two backfill placement methods are analyzed for blast induced vibration damage using the dynamic Flac3D modelling technique accounting for rock mass and fill damping characteristics, and a pressure wave is used to simulate the blast vibrations. Fill heterogeneity has also been considered for the two cases and results are compared.

Jun 1, 2012

By Martin Lebeuf

The phenomena occurring in the cathode and at the cathode surface of aluminum electrolysis cells are very important in regards to cathode voltage drop and cathode wear. In the current study, laboratory-scale aluminum electrolysis cell cathodes were analyzed by X-ray microtomography. This technique allows an excellent visualization of the distribution of different substances, if their respective X-ray attenuation coefficients are different enough. In the current case, the important difference in the mean atomic number between cryolitic bath and graphitic carbon results in good contrasts. The volumetric bath penetration profile, porosity and impurities distribution in the cathode were thus obtained. Furthermore, metallic impurities and bath heterogeneities were observed at the cathode surface. Observations were also made with Scanning Electron Microscopy - Energy Dispersive Spectroscopy (SEM-EDS).

Jan 1, 2011

By A. Mortazavi, H. Nasab

"The storage of petroleum products on surface is associated with difficulties and limitations. Accordingly, a viable alternative is to excavate underground space in rock and provide a safe way for oil storage. Soft rocks such as salt domes provide good conditions from environmental and operational points of view. The potential for high-volume storage and low permeability are encouraging aspects for oil storage in salt domes. The complicated shape of oil storage caverns, the complicated behavior of salt rocks, and boundary conditions associated with large underground openings are important challenges in the design of oil storage caverns. The aim of this paper is to delve into the stability and deformation mechanisms of storage caverns created in salt domes. A parametric study of effect of the cavern size, orientation, and depth is carried out as a function of ground stress regime. The stress field and deformation mechanisms are calculated for each case aiming at providing design guideline.INTRODUCTIONOne of the most popular soft rock that is used for underground oil storage is salt rock (halite). Salt rock has particular characteristics which makes it suitable for oil storage. Salt rock has several advantages for oil storage, these are: high production rate, high degree of availability, short filling period, high level of safety and low permeability [1]. The low permeability is due to the fact that halite deforms in a plastic manner over a wide range of pressures, temperatures and rates of deformations. This property prevents joints or gaps opening up in the formation, thus preventing the escape of liquids and gases. The state of stresses around the cavern in salt domes depends on the depth of the cavern (initial stresses and rock mass temperatures are increasing with depth), the in-situ stress state within the rock mass, and the internal oil pressure in the cavern. Furthermore, the salt creep behavior and the cavern geometry are influencing stress redistributions during loading and unloading phases.Rock mass structure, cavern geometry, material behavior and cavern operation patterns require complex physical models to describe the load-bearing behavior of the geomechanical structure. The determination of stress, strain and deformation in the rock mass due to cavern construction and operation are complex problems which can be evaluated employing numerical tools such as the Finite Element Method (FEM) or Finite Difference Method (FDM). In this study, the finite difference method was used to evaluate the behavior of oil storage cavern in salt rock."

Jan 1, 2015

By C. -G. Berg, J. T. Tuominen

Since the beginning of the 20th century, energy efficiency in copper smelting has been improved by a factor of 30 as a result of adopting autogenous smelting processes with more and more efficient waste heat recovery systems, increasing use of oxygen enrichment and countless smaller improvements. Nevertheless, energy in the form of electricity and fuels continues to be the biggest contributor to smelter operating cost. Metallurgists around the world are under constant pressure to find ways to save those precious megajoules wherever they can. One area that is often neglected is the removal of water contained in concentrates. Copper flotation concentrates, as delivered to a smelter, typically contain some 8–12% moisture. This moisture must be removed and the only way to do this is by evaporation, which consumes a lot of energy. Several studies have shown that the most efficient way of removing this moisture is to use a steam- heated indirect dryer—the least efficient way being the feeding of wet concentrate directly into a smelting furnace. Even in the most efficient smelters that employ modern steam drying, the energy needed to remove the moisture from the concentrates constitutes over 15% of the total energy consumption of a smelter – acid plant complex. The major steps that have been taken in the past to lower the energy consumption of moisture removal are the use of drying in general and the adoption of steam drying. The energy efficiency of concentrate drying has been improved by 25% over the last 20 years. The latest giant leap in this area, the Kumera Heat Recovery Dryer, is the result of Kumera’s long-term development in improving the efficiency of concentrate drying. The Heat Recovery Dryer is a novel application of steam drying that uses the waste heat from dryer exhaust gas for drying concentrates, thus, cutting the energy consumption by a further 30%. This paper discusses energy consumption in copper smelting in general and analyzes the energy consumption of concentrate drying in detail. Different dryer types are compared especially from the perspectives of energy consumption and environmental emissions. Applicability of different energy sources for drying is evaluated and discussed. The principle of the Kumera Heat Recovery Dryer is presented along with results from extensive continuous pilot plant tests. Potential applications and the feasibility of Kumera Heat Recovery Drying technology are discussed.

Jan 1, 2019

By Oleg G. Tovmachenko

We have studied optical properties of fluorescent nanoparticles. These particles consist of a metal (gold/silver) core, an empty and a dye labelled silica shells. The different dye molecules with moderate quantum yields (about 0.3) has been used. Almost all of types of nanoparticles show fluorescence enhancement. This enhancement is strongly dependent on the degree of the overlap between the surface plasmon band of the metal and the absorption/emission band of the dye molecules. The results are interpreted in terms of competition between local field enhancement and quenching of fluorescence by the metal surface.

Oct 1, 2003

By Adrian E. Scheidegger

"AbstractThe possibilities of deriving pertinent information about fractures in an oil pay from data obtained by core analysis are investigated. It is shown that it is possible to obtain an estimate of the fractured area per unit volume of the pay, and that the size of the fractures can be estimated if their shape is known. A suggestion of a routine procedure for the analysis of fractures is given.1.-IntroductionMany oil fields are producing essentially from cracks or fractures. Where this is the case, it is important to be able to obtain a knowledge of the size and distribution of those fractures in the oil pay. This knowledge has to be derived from the analysis of cores taken from the fields, as it is generally impossible to follow a fracture through the pay by direct means. The necessity of using statistical methods to extrapolate the meagre information obtained from the cores of the wells is therefore indicated.It is known that the fractures are much bigger than the diameter of the cores; thus, if they strike a core, the latter will generally fall into two pieces. The angle of the fracture with the vertical can be measured and, if oriented cores are taken, the exact position of the surface element representing the intersection of the fracture with the drill stem can be determined. Sometimes the edge of a fracture can be seen in a core. The number of •Cores that show such an edge can be noted. Of course, one has to be careful to distinguish between original fractures in the pay and fractures in the core caused by drilling operations. Only the former are relevant."

Jan 1, 1955

By K. Lambrych

Hydrometallurgical equipment used to extract and refine copper and other metals is exposed to extremely corrosive chemical environments. These systems must be fabricated from materials that are durable against corrosion, meet exacting mechanical requirements, and perform economically over the life of the mineral processing plant. In several recent large hydromet projects, fiber reinforced plastic (FRP) has been shown to provide equal if not superior durability relative to alternative materials of construction. This paper will compare corrosion performance and cost of plant equipment fabricated with corrosion resistant alloys, rubber lined steel, and FRP made with Epoxy Vinyl Ester thermoset resins. Case histories for FRP piping, storage tanks, extraction vessels, and electrowinning cells combined with laboratory-based corrosion studies will be reviewed to demonstrate how FRP materials are selected for hydrometallurgical equipment. Specific examples from projects such as El Boleo, Long Harbour and others will be used to demonstrate how the versatility of FRP allows for remote fabrication of durable corrosion-resistant large-scale equipment for hydrometallurgical refinement of copper and other metals. INTRODUCTION Fiber reinforced plastic (FRP) began to emerge as a material of construction for corrosion service in many industrial processes in the late 1950s because of its ease of use and overall performance. Corrosion resistant (CR) FRP, as an alternative construction material to alloys, rubber and tile linings, grew steadily in following decades. The aggressive operating conditions associated with hydrometallurgical processes typically require materials of construction that can withstand acids and acid chlorides at temperatures up to 90°C, sometimes higher. Common metallic materials of construction, such as carbon steel, are not compatible with these conditions. High nickel alloys are capable of meeting performance requirements, but often at a high cost. In many cases FRP mining equipment based on epoxy vinyl ester resin (EVER) offers durability, long service life and lower maintenance costs. Through demonstrated performance and decades of case histories, more and more design engineers are confidently specifying FRP as the material of construction for new mineral processing equipment.

Jan 1, 2019

By K. Scholey, S. Marcuson

As high grade nickel sulphide ores are being depleted and with the continuing challenges experienced in economically processing nickel laterite ores, it is important to investigate technologies that can extract nickel from low grade ultramafic ores which are present in large quantities worldwide. In the Thompson Nickel Belt, there are some hundred million tonnes of mineralization that are potentially amenable to surface mining. Since the original discovery of the Thompson orebody, recovery of nickel from these ultramafic deposits has been an elusive goal. Research and development projects as well as commercial processing have been attempted. In the 2000's as other resources became scarcer, a major drilling, mine evaluation and research project was initiated at Vale. In 2007, Vale Base Metals Technology Development invited Cytec and potential academic partners to participate in an industry-university research consortium with the goal of developing new technologies and methods of processing the ultramafic deposits. Three university professors, J. Finch of McGill, P. Somasundaran of Columbia and R. Pelton of McMaster accepted, each group attacking the problem with a different approach. This paper describes the management of the research consortium and the significance of the results from Vale's perspective. The next four papers in this session will summarize the project and results from the partners' point of view. Vale is pleased to share the experience of the collaborative research and development with the mining industry.

Jan 1, 2011

By D. W. Duncan, A. Bruynesteyn

Acidic mine waters containing solubilized uranium have been observed in many uranium and some copper mines. In every case, the sulphide and iron oxidizing bacterium, Thiobacillus ferrooxidans, was also present. This bacterium provides the ferric iron required to oxidize u+4, both by oxidizing available ferrous iron and by oxidizing pyrite or other available sulphide minerals. This latter oxidation also provides sulphuric acid and may increase extraction by exposing more uranium. The enhancement of bacterial activity and the results of some field tests are discussed.

Jan 1, 1971

By P. Cleyle, J. H. Masliyah, R. S. Chow, Z. H. Xu, Z. A. Zhou

Bubble nucleation in water under dynamic conditions was investigated using an autoclave at an air saturation pressure of 7 atm. Agitation during air saturation of water was found to be crucial in enhancing tiny bubble formation. More bubbles nucleated on hydrophobic surfaces at a higher agitation rate, due to cavity formation by the more intense hydrodynamic conditions. Flotation recovery of bitumen from oil sands demonstrated a significant role of bubbles nucleated in water: more than 50-170% increase in bitumen recovery from different oil sands was obtained by using air supersaturated than the regular water.

Jan 1, 2009

By H. A. ?ye

The ISO TC 226 (Materials for the production of primary aluminium) has presently issued more than one hundred standards on the materials: alumina, pitch, petroleum coke, carbon anodes, carbon cathodes, ramming paste, fluorides and refractory). The object of the standardization work is to find methods that both material producers and smelters will accept. Methods that are specific for the operational conditions have been developed in addition to more traditional room temperature methods. Examples of important properties under operational conditions are: Air and C02 reactivity of anodes, Equivalent temperature for baked anodes, Sodium expansion of cathode blocks, Shrinkage and Rammability of paste, Penetration of electrolyte into refractories.

Jan 1, 2006

By B. D. Pandey, M. S. Kim, B. S. Kim

The recovery of Sn from used Pb-free solder (Sn, 3~4 % Ag, < 0.9 % Cu, < 1.2 % Pb) has been investigated by electrorefining in sulfuric acid solutions containing small amount of hydrochloric acid. This involved preparation of the anode material by melting and casting the used solder followed by refining. During electrorefining, dendritic tin was deposited on stainless steel cathode. Increasing the amount of hydrochloric acid up to 0.3 mol /L in the electrolyte enhanced the current efficiency to 92.2 % and the enrichment ratio of silver to 94.3 % in the anode slime which was otherwise 84.7% and 81.6 % in absence of HCl, respectively. The electrolyte containing hydrochloric acid has also prevented the precipitation of tin oxide in the bath. In the scale-up experiment using 1.6 kg anodes, 84.3 % current efficiency and close to 100 % Ag enrichment ratio were obtained, while the purity of electro-refined tin was over 99.9 %. The energy consumption of the winning process was found to be 0.151 kWh /kg-Sn which is competitive as compared to commercial tin electrorefining processes.

Jan 1, 2014

By Angus D. Campbell

Introduction Gowganda forms part of the general Cobalt area. Its rocks and ores are very similar to those of the other parts of the area. While its total production of silver is only 4 per cent of that of the famous Cobalt silver camp, its 1928 shipments contained 42 1/2 per cent as much silver as those of Cobalt for that year. During twenty years of production, 15,000,000 ounces of silver have been shipped from Gowganda. Of this, over 8,000,000 ounces have been shipped in the past five years. The area has thus made for several years a substantial contribution to the wealth of Ontario. Its future depends to a great extent on the priee of silver, which is now, unfortunately, at a record low price. This paper is a discussion of how the Gowganda ore-shoots occur, together with some notes on the milling of the ores at the Castle-Trethewey Mines. The first part is written in the hope of stimulating further study of the silver occurrences, which may lead to further discoveries. The second part, besides being a matter of record, may be of some use to operators of small mills. The drawings in the several Figures illustrating the text are by W. D. Stroud, mine superintendent of the Castle-Trethewey Mines, the benefit of whose opinions I have had in compiling these notes.

Jan 1, 1930

By Matej Petružálek, Tomáš Svitek, Tomáš Lokajícek

"Migmatite from the Skalka region (Czech Republic) was chosen as the experimental rock material. It has macroscopically visible plane parallel structure (foliation). The foliation was caused mainly by biotite grains arrangement. The cylindrical samples of migmatite with subhorizontal, subvertical and oblique foliation were uniaxially loaded up to the failure. Network of 8 broad band sensors was employed for acoustic emission monitoring and ultrasonic sounding. A grid search method with anisotropic velocity model was used for AE hypocenters localization. The source types of successfully localized events were determined from the average first arrival amplitude. Structural anisotropy of tested rock material caused the anisotropy of its mechanical properties (peak strength, Young’s modulus) as well as a different way of fracturing process in dependence on the angle between axial stress and foliation plane. The combination of splitting, shearing and sliding was found to control the fracturing of sample with subhorizontal foliation. The shearing and sliding was dominant in fracturing of samples with oblique foliation. With greater dip of foliation, the role of sliding increased at the expense of shearing. Due to the favorably oriented system of microcracks already present, the shearing and splitting was at the same level during fracturing of the sample with subvertical foliation before nucleation began.INTRODUCTIONThe process of failure of low porosity rocks depends on their mechanical properties and actual stress and temperature condition. At the low pressure and low temperature, the most common way is brittle failure, which is a progressive process requiring the initiation, growth and coalescence of cracks (Lockner, 1993). Stress strain behavior of low porosity crystalline rocks, during the laboratory compression experiments, is divided into four characteristic stages: crack closure, elastic region, stable crack growth and unstable crack growth which leads to the brittle failure, Brace et al. (1966) , Bieniawski (1967), Lajtai (1974), Cai et al. (2004), Nicksiar and Martin, 2012 and 2013.The fracturing process of stressed rock begins with the crack initiation (sci), which for low porosity rocks occurs approximately at 40-50% of peak strength (sp) (Cai et al., 2004; Nicksiar and Martin, 2013). After the sci, the dilatancy begins and stable crack growth follows up to the crack damage threshold (scd), which is approximately at 80% of sp (Cai et al., 2004). After crossing the crack damage level, there is an unstable crack growth accompanied with nucleation of fault plane (sn) at 97-100% of sp. (Rao et al., 2011). The stress drop accompanied with formation of macro scale shear failure plane follows after peak stress is crossed."

Jan 1, 2015