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By M. Mohammadijoo, J. B. Wiskel, D. G. Ivey, S. Kenny, H. Henein

Cold-wire tandem submerged arc welding (CWTSAW) has recently been developed as a novel welding technique to replace the conventional tandem submerged arc welding (TSAW) process and improve the productivity of pipeline manufacturing. The process involves two electrodes with arcs and one electrically cold electrode. Since heat-input of the welding process is a key factor affecting the properties of the weld metal (WM) and the heat-affected zone (HAZ), and the additional cold-wire affects the heat introduced to the weldment, it is of interest to investigate property and geometry changes in the WM and HAZ when a cold-wire is added to the welding process. In the current research, the CWTSAW process is investigated and optimized by correlating the main welding parameters with the micro-hardness of the WM and HAZ and the geometry of the weld, i.e., the bead width (BW), penetration depth (PD), reinforcement area (RA) and coarse grained heat-affected zone (CGHAZ) area. Three statistical and mathematical methods are employed to optimize the CWTSAW process in terms of the mechanical properties and WM and HAZ geometry of a typical microalloyed steel used for pipeline manufacturing.

Jan 1, 2015

By Isabel C. B Rodrigues, Flávia D. Reis, Versiane A. Leão, Rosa M. F. Lima

Attention has been focused in recent decades upon the precipitation of metal sulphides from acid mine drainage (AMD) and pregnant leach solutions, due to the advantages of the sulphide precipitation process over traditional methods employing hydroxides. The aim of this work was thus to explore technologies for copper precipitation using either Na2S or biogenic sulphide. The recovery of copper sulphide was improved when the initial pH of the solution containing each metal was 4 or excess sulphide was employed. In such, a condition the removal efficiency was 99.9%, corresponding to a residual level of 0.1mg/L for copper in solution. Kinetic parameters for precipitation were determined from the particle size distributions using the method of moments, where the growth and nucleation rates, as well the agglomeration kernel, were calculated. The biogenic sulphide was a suitable alternative to sodium sulphide for copper removal as either sodium sulphide and biogenic sulphide can be utilized to precipitate such a metal allowing the effluent to be compliant with environmental legislation.

Jan 1, 2014

By Georges Croisé, Les-Lee Thompson, Adrien Debergé

Membrane filtration systems have regained focus in recent years as an effective means of liquid-liquid separation to increase the concentration of valuable elements, recover reagents or remove impurities. ORANO Mining (formerly AREVA) investigated this cost optimization process opportunity as early as 2011 for implementation at the Trekkopje project (Namibia). The key focus was to separate and recycle bicarbonate from the uranium bearing eluate solution. The performance targets were successfully achieved at lab- and pilot scale with an ultrafiltration and nano-filtration configuration system. Early 2015, ORANO Mining further launched an investigation into the use of membranes for acid recycling at the KATCO In Situ recovery mine in Kazakhstan based on the favorable results from the original bicarbonate application. KATCO is the world leader in ISR uranium mining with an eluate processing capacity of 80 000 m3/yr. This site consists of two processing plants namely, Muyumkum and Tortkuduk, located 40 kilometers apart, both operating under acidic conditions whereas precipitation and packaging are based in Tortkuduk only. This paper serves to present the results from the integration of a nano-filtration system at the Muyumkum satellite processing plant. The project consisted of screening laboratory bench studies conducted at ORANO-CIME followed by process validation at KATCO through further bench and pilot test work. The feasibility study assessments were successfully concluded which led to the implementation at an industrial scale in Muyumkum of a nano-filtration process to reduce eluate volumes being sent to the uranium precipitation section whilst achieving effective separation of uranium from sulfuric acid. Nano-filtration technology has drawn significant attention due to the efficiency and reproducibility of the process and its moderate capital cost relative to operational savings. The reliability of the previous results is a great opportunity to reduce operative expenditures within ORANO’s next ISR mining project in Mongolia.

Jan 1, 2020

By Fathi Habashi

A new era in pressure hydrometallurgy is marked when the roasting - leaching - electrowinning process in the zinc industry was replaced by direct pressure leaching of zinc concentrate. Since then, the technology has received recognition as the technology of the future. Large autoclaves of unprecedented size have been manufactured and installed in a number of metallurgical plants for recovering copper and nickel from their concentrates or liberating gold from its refractory ores. An attempt to recover alumina from clay using pressure technology is underway. Autoclaves lined with acid resisting bricks or with titanium clad may weigh as much as 800 tonnes were transported successfully from the manufacturing workshop to the mine site over long distances.

Jan 1, 2014

By Kaiwen Xia, Bibhu Mohanty, Per Svedensten, Sheng Huang

"The mechanics of crushing and grinding operations in mining and excavation processes has been investigated in a laboratory simulation study. It employs a multi-particle bedded rock target, which is subjected to multiple impacts. The impact set-up consists of a Hopkinson pressure bar and a Piston-holder system. The apparatus, employing a 38 mm diameter pressure bar, was used to apply varying but calibrated dynamic loading force on the rock particles. The energy consumed by the sample during fragmentation was determined by considering the energy carried by the incident wave and the reflected wave. The Pistonholder system is used to hold rock samples and to recycle fragments after each test for particle size analysis, for single as well as multiple impacts. The feed size selected was in the range of 9.5 to 12.7 mm for all rock samples, and the impact velocity was set at 14 m/s. Two strong granitic rocks and a relatively weak limestone were the target rocks. The resulting particle size distribution after each set of impacts, ranging from single to 10 consecutive impacts, were analyzed, and various size distribution functions (i.e. Rosin- Rammler, Swebrec, Grady and Gilvarry functions) were fitted to compare their suitability in predicting the fragment size distribution for each rock type. INTRODUCTIONCrushers are widely used in the mining industry all over the world. Understanding fragmentation behaviour of rock under crushing process is fundamental to improved productivity and efficiency in mining operations. This is particularly so as all subsequent size reduction processes such as crushing and grinding are far more energy intensive than the initial blasting process employed in breaking of in situ rock. A considerable body of experimental studies exists on the behaviour of rock crushers for specific rock types in order to aid in the design of various types of crushers. However, these studies are mainly site specific, that is, the results are largely empirical, and the fundamentals of fracture process that lead to size reduction have not been dealt with adequately. Most such studies have attempted to link the input parameters, such as feed size and crusher parameters, with output particle size, and global energy expended in the process. However the physical mechanism of crushing process is still not well understood. First of all, the energy consumed by the rock sample is hard to calculate during standard crushing or grinding tests; secondly, multi-particle test is hard to perform in the laboratory due to irregular shape of the subject rock sample. In This paper, describes a laboratory crushing apparatus for multi-particle rock samples, with sufficient control of the energy expended in the process, with a view to relate creation of new fracture surfaces in the size reduction process."

Jan 1, 2015

Lonmin RoM ball mills are treating two types of feed ore produced by conventional mining and mechanised mining methods. It was reported that reduction in mill throughput was observed when treating the mechanised mining ore. Detailed grinding surveys were conducted for troubleshooting. Ore samples were collected for breakage characterisation using a JKRBT based on different particle density components. XRD analysis was conducted to investigate the association of minerals with density components. The plant surveys and the breakage characterisation tests all suggested that the two mining methods did not significantly affect either the ore breakage properties or the RoM mill performance. Instead, the mill discharge open area exerted a remarkable influence on mill throughput. The RoM ball mill operated at Lonmin K4 Concentrator has been proven to be a versatile mill that performed stably with variations in feed size distribution and feed ore changes by different mining techniques. The reasons are elucidated by the multi-component breakage characterisation and the plant surveys data.

Jan 1, 2012

By S. B. Kang

Magnesium has poor ductility at temperatures lower than 225°C and, as a result, Mg alloy sheets are produced via fairly complex thermomechanical processes consisting of numerous sequential steps of hot (warm) rolling with low reduction and intermediate recrystallization annealing operations. In context of the present study, a simple technology for the fabrication of magnesium sheets by hot (warm) rolling was applied to various magnesium alloys. The misch metal addition in those AZ alloys was done to evaluate the deformation behavior. Tensile tests were carried out for those AZ alloys after applying different heat treatments. The precipitation of ß phase (Mg17Al12 phase) induced different microstructures with various cooling method from solution treatment temperature, and also with various annealing treatment temperatures.

Jan 1, 2006

By Eirik Sundvor, Hany Doss, Peter Vogt, Kathleen Crane

"Abstract - In 1989-1990, the SeaMARC II side-looking sonar (11 to 12 kHz) and swath bathymetric system imaged more than 80 000 km2 of the seafloor in the Norwegian-Greenland Sea and southern Arctic Ocean. One of our main goals was to investigate the highly oblique (115°) junction between the Mohns and Knipovich ridges, and to determine, using new morphotectonic data, whether or not this junction is stable or in a state of readjustment. These findings are presented in this paper.Along the northern Mohns Ridge, we observed a highly segmented rift valley undisturbed by transform faults. In contrast to the elevated Reykjanes Ridge, the Mohns Ridge is dominated by deep en echelon fault-bounded troughs, which are bordered by high rift valley volcanoes. These segment boundaries are interpreted to be sites of recent to present volcanic activity, based on their high acoustic reflectivity. The northwestern flank of the Mohns Ridge is marked by shallow quasi-linear ridges parallel to the present orientation of the Mohns Ridge. The orientation and geographic position of these ridges suggest that they were formed at the Mohns Ridge. Only in the northernmost cases are some of these off-axial ridges non-linear. The degree of the non-linearities increases slightly with proximity to the Mohns-Knipovich bend. In addition, because no transform fault was detected between the Mohns and Knipovich ridges, we conclude that the Knipovich Ridge must be obliquely spreading to the NW-SE."

Jan 1, 1999

By J. E. Danoczi

ABSTRACT A diamond processing plant is being designed for the Star–Orion South diamond project in central Saskatchewan. Key to the plant is diamond liberation, which occurs in the comminution section and is the process of breaking up kimberlite rock as gently as possible to minimize diamond damage, particularly in larger, high-value diamonds. Kimberlite from the crater area of a volcanic pipe is generally softer than kimberlite from the diatreme zone. Softer kimberlite, comprising the majority of Star– Orion South deposits, can be readily broken up using abrasion and attrition by autogenous grinding mills, the preferred comminution method for minimizing diamond damage.

Jan 1, 2013

By G. S. Hume

THE Plains of east-central Alberta herein described embrace an area from Viking east to the Saskatchewan boundary and from North Saskatchewan river south to Coronation and Monitor (Figure 1). By far the greater part of this area is deeply drift-covered, and .outcrops of bedrock are relatively few and often widely separated. Within the area there are large morainal hills and others of considerable extent that superficially have all the characters of morainal hills but contain a core of bedrock. These latter, then, were hills when the ice sheet traversed the country and only have been modified by glacial agencies. In many places on them, the drift is but a thin veneer, as is certainly the case in part of the Neutral hills (Figure 2) northeast of Coronation and north of Monitor. In other cases, however, as in the Blackfoot hills, southwest of Lloydminster, the drift is sufficiently thick to conceal practically all the bedrock and in many places no information is available as to whether a bedrock core, representing a pre-glacial hill, is present. There is no question, however, that the larger river valleys, as for example those of the North Saskatchewan and Battle rivers, are in part at least pre-glacial. Proof of this can be demonstrated in many places, because obviously the valleys must have been present in pre-glacial times to allow glacial deposits to have accumulated in them. It is also known that inter-glacial deposits occur. At one locality in Battle River valley, in sec. 30, tp. 45, range 2, west of the 4th mer., the following section occurs( l ): 15 feet of boulder clay with granite and other boulders. 56 feet of stratified sands, clays, and gravels containing pebbles of Precambrian rocks and fresh-water shells. From this it is apparent that the 56 feet of stratified sands, clays, and gravels must have derived their Precambrian pebbles from a previous glaciation of which the overlying boulder clay represents another ice advance in this area. Thus, although the river valleys contain glacial and interglacial deposits, they have not been filled by them to such an extent that the drainage has been diverted, and in many places, especially in the case of Battle river and some smaller streams, the size of the valley is altogether out of proportion to the size of the stream it now contains.

Jan 1, 1937

By I. A. Tinto

"Labrador City is located in the southwestern portion of Newfoundland-Labrador, approximately 965 kilometers north-east of Montreal. The mine and beneficiation complex of the Iron Ore Company of Canada, known as the Carol Project, is situated 535 metres above sea level in a climatic region characterized by cold winters and short, cool summers.HistoryThe Iron Ore Company of Canada commenced work in the area in 19 4 9' however, it was not until 1958 that the decision was made to proceed with mining operations. The ore body consists of Specular Hematite (Fe203) and Magnetite (Fe304) with small quantities of Limonite and Geothite. The average grade of the ore bodies is 39% iron.The mining facilities, crushing plant, and concentrator were in operation by the early part of 1962. In the summer of 1961, a decision was made to build a pelletizing plant adjacent to the concentrator. This plant was designed, erected and placed in operation during 1962 and the first half of 1963. Since the completion of the pelletizing plant, additional expansions to both the pellet plant and concentrator have taken place in 1967 and 1973. Today, the Carol Project has the capacity to produce 20 million tonnes of concentrate from which 10.5 million tonnes of pellets can be produced.The period 1980-85 spans a period of energy crisis, world-wide recession, and a consequent re-structuring of the North American steel industry as it struggles to survive in an arena of excess world steel making capacity, government subsidized industries, and the increasing competition from overseas and from developing countries.The media headlines over the past few years echo the woes of the industry and the strategy plans for survival of the fittest. Today's buzz words are foreign competition, steel import quotas, joint ventures, employee participation, work rules, quality, productivity, and state of the art technology."

Jan 1, 1986

By Frederic Benard

THE Ontario Refining Company, Limited, wholly-owned subsidiary of The International Nickel Company of Canada, refines the entire blister copper output of the latter's Copper Cliff smelter. Prior to 1936, the blister was cast in 460-lb. cakes at the smelter, loaded on open cars, and transported by rail to the refinery, a distance of approximately 1 1/4 miles. Here the cakes were transferred to the plant narrow-gauge system, charged to furnaces, and re-melted. This procedure necessitated the operation of holding furnaces and casting machines at the smelter -extensive re-handling-and melting down of a cold charge at the refinery. Transfer of the copper in molten form direct from converters to anode furnaces promised a considerable reduction in costs, and this possibility was investigated. As a result, a portable holding furnace, or hot-metal car, was designed and constructed. It was placed in operation in July, 1936, to be followed a year later by three additional units of slightly modified design. Figure 1 shows the original car, and Figure 2 the lacer type. With four cars in service, operations were placed on an all 'hot-metal' basis.

Jan 1, 1938

By N. Katsikaros, N. S. ‘ Yap, B. Adaszynski

"Cyanide is a well proven, effective lixiviant that has been utilised for centuries in gold extraction processes. Despite being used in close to 90% of gold processing plants, cyanide leaching is still being scrutinised due to its toxic nature. With governments tightening the regulations on cyanide management, and recently erected sites situated closer to community and environment, leach waste and tailings treatment has become increasingly important. Gekko Systems has worked with engineering companies and directly with gold producers to provide technical services and supply complete modular cyanide destruction (detox) systems for plants leaching both run-of-mine ore and high sulphide gravity and flotation concentrates. Although similar in principle, the different materials presented unique challenges in design and implementation. Similar to designing any section of a processing plant, the development of the cyanide destruction plant design began with laboratory test work to simulate the full scale operation. This paper focusses on the laboratory test work and how other critical factors such as geographical location, logistics, and local community play a role in the process design and construction. Two design and supply cases are discussed in this paper; one treating intensive cyanidation concentrate leach tails and one treating whole ore CIL tails. Although these plants both use the SO2/O2 process, each presented different challenges in laboratory testing and plant design, resulting in variations in final implementation including reagent choice, oxygen supply, and process control.INTRODUCTIONSince 1887, cyanide has played a large part in the beneficiation of gold from gold bearing ores. Cyanide is used to solubilise gold into solution, and is typically added in excess to maintain the leaching process. Some or all the excess cyanide can often be recovered and reused in the process however chemical destruction of cyanide is often necessary to manage cyanide levels in the tailings storage facility (TSF)."

Jan 1, 2016

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

Adsorption of guar gum was investigated on model minerals typically found in water-insoluble slimes of potash ores. The ionic strength of the adsorption mixtures was varied from distilled water to saturated NaC1 and KC1. The tests were also performed using a saturated brine. The adsorption density of guar gum on illite, dolomite, and kaolinite was found to be not only a function of total ionic strength but also of the type of electrolyte present in solution. Generally, the adsorption of the polymer on the clay minerals was higher in KC1 solutions than in NaCI, but the differences gradually disappeared when the electrolyte concentration approached saturation. The results were analyzed in terms of chaotropic (K ) or kosmotropic (Na') properties of background counter-ions and their different behaviors at the hydrated mineral-water interface. Guar gum adsorption on dolomite was related to the presence of calcium and magnesium sites on the mineral surface, and to the cis-configuration of OH groups of mannose units. Based on viscosity measurements, it was suggested that guar gum macromolecules form entanglements in NaCI solutions (and distilled water), but individual molecules exist in KC1 solutions thus creating different modes of adsorption of guar gum from concentrated NaCl and KCl solutions.

Jan 1, 2006

By E. Lehtila, J. J. Talja, R. Jahila

Kopar Oy is acknowledged for engineering and manufacturing of robust systems for bulk material handling, especially at power plants and non-ferrous smelters. We have over thirty years of experience with systems specifically designed for hot and abrasive conditions, aiming at low cost of ownership, low operational expenses and high availability. Although Kopar has numerous applications in mechanical conveying, there is an increasing number of pneumatic conveying applications at copper smelters. They relate to conveying of concentrate, and primary and secondary flue dusts. Challenges of pneumatic conveying for concentrate are mechanical and do relate to broad particle size distribution and high abrasivity of the concentrate and the silica. Therefore, special attention shall be paid to system design and ceramically lined bends in the pipeline. Challenges of pneumatic conveying of primary flue dust relate predominantly to material stickiness and poor flowability which are mainly due to fine particle size and formation of sulphates and furthermore, crystalline water. Additional challenges of secondary dust, the white converter dust, are primarily due to the extremely fine 0.1–1.5 µm particle size and problems which come with this. Effect of material characteristics like size distribution, morphology and chemical composition in pneumatic conveying are discussed in detail. INTRODUCTION Fine materials like concentrate, feed mix, flue dusts (from waste heat boiler and electrostatic precipitator) and secondary dusts need to be conveyed at smelters. Both horizontal and vertical conveying and combination of those are used. For the purpose, both mechanical and pneumatic conveying are applied. Most widely used equipment are drag chain conveyors and various combination of pneumatic systems, e.g. air lift, dense-phase and dilute phase pneumatic conveyors. Kopar has 30 years’ experience with multiple material handling systems. Furthermore, acquired companies like Elmomet Oy and SITE Oy (both currently fully merged and integrated into Kopar Oy) have even longer history, especially in pneumatic conveying. It is commonly known that the finer the dust the more difficult it is to be conveyed pneumatically. Sulfates with crystal water makes it all even more difficult, if not ineligible. Challenges related to pneumatic conveying of various fine materials is discussed in detail in the paper.

Jan 1, 2019

By J. N. Van der Merwe, M. Mathey

"We present an analysis of the mechanical properties of coal specimens from various coalfields and seams in South Africa. Our database comprises of 1800 test results from uniaxial and triaxial compression tests, as well as indirect tensile strength tests, which we collected from the various mining houses and research agencies in the country. We inspected the database for possible errors and present a brief description of the verification procedure in the paper.In the analysis, we reveal that the collected samples of strength and elastic properties of South African coals can be represented by single lognormal or normal distributions with only few outliers. This finding indicates that the samples realistically approximate the population of mechanical coal properties in the country and may suggest that the properties are randomly distributed. Significant coalfield- or seamspecific trends for the mechanical properties of coal are not clearly discernible from our data.Typical coefficients of variation for the individual mechanical properties range between 25-50 % on a country-wide and seam-specific level of analysis. Average uniaxial compressive strength values, however, are closely clustered for all seams. A comparison with data available from international coal strength studies show the distinct difference between South African coals and seams in countries of the Northern Hemisphere, where differences in the average coal seam strength are more pronounced.We observe that the number of specimens whose failure mode is influenced by the presence of natural discontinuities reduces drastically with the application of very small confining pressures to the specimens. Further, the strength-reducing influence of discontinuities diminishes with increasing confining pressures."

Jan 1, 2015

By R. J. Enright

Eight mines in canada and three in Australia were visited between September 1987 and Februacy 1988. All mines had encountered problems with sulphide dust explosions and had introduced defence mechanisms to prevent or limit the extent of these explosions. Techniques included dispersion of limestone by various methods, use of water foggers, placing of water and inert stenuning in blast holes, and removal of settled dust to prevent secondary explosions. The techniques were evaluated and it was concluded that certain practices should be modified or discontinued as they were of little value in preventing dust explosions.

May 11, 1988

By G. Goodall, D. Mercier, M. Brochu, C. Kaplin

A nanostructured CoNiCrAlY coating was obtained by thermally spraying cryomilled feedstock powder using the high-velocity oxy-fuel (HVOF) process. The oxidation behavior of the nanostructured powder and coating were compared to their conventional counterparts by performing static oxidation tests at 1000°C for durations ranging from 1 to 96 hours. It has been found that oxidation of the conventional powder yielded a duplex oxide scale composed of an inner layer of Al2O3 and an outer layer composed of Cr2O3, NiAl2O4 and other spinels. Interestingly, oxidation of the as-sprayed nanostructured coating yielded a similar duplex oxide scale while oxidation of the polished coating resulted in a single Al2O3 layer. These findings indicated that surface oxide seeds act as nucleation sites for the growth of the mixed oxide layer. Also, it was determined that nanostructuring of the coating promotes the nucleation and growth of a single and adherent a-Al2O3 layer by increasing both the number of diffusion channels and the aluminum concentration at grain boundaries.

Jan 1, 2010

By A. R. Laplante

Gold recovery early in the flowsheet, typically from the primary grinding circuit, has seen significant advances in the past three years. Some of the advances achieved under the auspices of the AMIRA P420B Gold Processing Technology project are reviewed. The areas covered are gravity-recoverable gold (GRG) characterization, GRG behaviour in classification, gravity recovery simulation and the link between gravity recovery and cyanidation.

Jan 1, 2005