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By A S. Leitch

This paper is based on the accident prevention pro-gram carried out in the coal mines of Alberta. It defines the role of the Alberta Mines Branch and of The Work-men's Compensation Board, and relates how a safety pro-gram was initiated. The formation of the Alberta Class 1 Mining Safety Council is also described. The responsibilities of both management and the individual worker are then outlined, and the main features of a successful accident prevention program are delineated. T HE purpose of this paper is not to repeat generalities and platitudes about industrial safety, but rather to relate the experience of Alberta coal mines during the past number of years in their efforts to keep accidents to a minimum. It has been learned from experience that many basic principles are as sound today as they were 20 years ago. How-ever the complexities of modern mining methods and the modern man or miner have created problems that did not exist then.

Jan 1, 1964

By R. Carrier

"There has been a continuous evolution with the use of pre-cast concrete elements in the construction of aluminum smelters. In 1990, Phase I of Alouette was built using cast-in-place concrete exclusively. Whereas, other AP 30 technology plants such as Hillside 2 in the mid-1990s used pre-cast concrete beams with cast-in-place floors. Mozal 2, in 2002, used pre-cast concrete beams with pre-cast partial-slab operating floors. Alouette Phase II went further. Not only were the potroom building beams and floors pre-cast, but the entire pot support system, insulating walls and basement jersey walls were pre-cast. Once the techniques for bending and welding the reinforcement bars and the design for attaching electrical insulating plates to the concrete was perfected, the challenge for the project remained only in the logistics of transporting the pieces to site and simple erection. The overall impact on the project was dramatic. Using prefabricated concrete not only allowed advancement of the schedule, but totally eliminated formwork, re-bar installation, and form removal activities along with the handling of all the materials involved with these activities. With the elimination of these labour and material-intensive portions of the job, exposure to work injuries was dramatically reduced. The most prevalent activity for lost time accidents is during the rough work associated with concrete formwork, placing concrete and form removal. Another area where prefabricated elements were successfully used on Alouette Phase II was for the insulating walls enclosing the pot area, known as the ""claustra walls"". Usually these walls are constructed in-situ using mortar and breeze block. Success was also achieved with prefabrication of the perimetric walls that are installed at the lower floor of the potroom. A big advantage of using prefabricated concrete in the electrolysis area is in assuring electrical isolation for the operating floors. Poured concrete requires a meticulous clean-up effort before commissioning to establish the electrically ""floating"" characteristics of the operating floors. Poured concrete results in ""wash"", stray wood,"

Jan 1, 2006

By M. H. Haycock

Introduction The property of Rouyn Merger Gold Mines, Limited, is in Rouyn and Joannès townships, Western Quebec, seven miles east of the town of Rouyn. Traversing it is the east-west trending Cadillac-Bouzan fault. Diamond drilling in 1944 and 1945 along a shear zone south of the fault indicated an ore deposit lying at the contact between sedimentary and volcanic rocks and dipping approximately 60° to the northwest. In the summer of 1945 it was decided to sink a shaft to investigate the indicated ore zone. In the immediate vicinity of the deposit, bed-rock is overlain by clay beds, in some places as much as 70 feet thick. Consequently, possible shaft sites were limited to those locations where overburden would not be excessive. The most favourable site was about 125 feet to the south of the ore zone as projected vertically from bed-rock to the surface. Accordingly, it was decided to sink the shaft at this point, with an inclination of 60° N. W., paralleling the dip of the ore zone.

Jan 1, 1948

By Timo Heikkinen

We have read, with great interest, Mr. Crocker's article on "Recent Trends in Autogenous Grinding," published in the October issue of The Canadian Mining and Metallurgical Bulletin. Referring to our paper, "Two-Stage Autogenous Grinding Investigations at Outokumpu," we can now report that last August we changed to this method at the Keretti concentrator. Prior to the conversion, the Keretti plant (see flow-sheet, Figure 1) had two primary rod mills, 6 ft. in diameter and 12ft. in length, in open circuit, followed by four secondary 9-by 12-ft. pebble grate mills in closed circuit with rake classifiers. Last summer, wl1en the Since August, grinding has been successfully carried out autogenously in two stages, with two mills being employed in the primary stage and four in the secondary. The size of the pebbles in the secondary mills is about the same as earlier -l V: i to 3 inches (Figures 4 and 5). Also, we generally prefer two-stage grinding to single-stage grinding because, in the former,

Jan 1, 1964

By Moatassem Abdallah

Buildings in the United States account for 72% of electricity consumption, 40% of energy consumption, 13% of water consumption, 39% of carbon footprint, and 30% of waste output. In order to minimize these negative environmental impacts, many public and private owners are requesting that their buildings be more sustainable and certified under the widely known programs such as leadership in energy and environmental design for existing buildings (LEED-EB). To accomplish this, buildings are increasingly integrating green building measures including energy efficient lighting, motion sensors, thermal pane glass, geothermal heat pumps, EnergyStar rated HVAC systems, photovoltaic systems, and wind turbines. This research paper presents the development of an automated decision support system (DSS) that is designed to optimize the selection of green building measures which can be used to upgrade existing buildings. The developed DSS incorporates two optimization models that are capable of (i) minimizing the total upgrade costs required to accomplish a specified LEED-EB certification level such as silver or gold; and (ii) maximizing the number of accredited LEED-EB points within a specified budget of upgrade costs. The DSS is designed to identify a set of optimal upgrade decisions that accomplishes these two optimization objectives. An application example is used to illustrate the capabilities of the DSS and to validate its result.

Aug 1, 2013

By G. E. Bogin, C. Strebinger, J. F. Brune

"Evidence shows that methane gas emanates from the mined-out area or gob of a longwall coal mine and can travel towards the working face, posing an explosion risk. Since the gob consists of varying levels of compacted rock, many researchers have modeled fluid flow through the gob as a Darcy-type porous media with a specified porosity and permeability. When studying methane gas explosions near the gob fringe, the Darcy flow assumption may not be applicable to describe the methane flame interaction with the gob. Computational fluid dynamic studies were performed modeling methane flame propagation across a simulated gob which was modeled as both a Darcy porous medium and as discrete rock objects with varying sphericity. Modeling the gob as a Darcy porous medium results in unrealistic methane flame propagation since the porous media assumption does not consider any differences in rock size and/or distribution. Additionally, the porous media model does not allow for ignition within and subsequent flame propagation through the porous medium, which must be modeled to understand the potential for methane gas explosions in the gob area. Modeling the gob as discrete rock objects produces more realistic methane flame dynamics and agrees with experimental observations. Modeling results show flame propagation across circles, hexagons, and squares, meant to represent rock rubble in the gob, produce different levels of turbulence which affects methane flame propagation velocity. This research demonstrates that modeling methane gas explosions in a longwall coal mine environment, specifically near the gob area, requires modeling obstacles, such as rock rubble, as discrete physical objects to capture the complex coupling of fluid dynamics, thermodynamics, and heat transfer. INTRODUCTION Although there are methods to mitigating methane accumulations in a longwall coal mine, explosive gas zones (EGZs) of methane and air may exist and pose an explosion risk to nearby miners and equipment (Brune, 2014) (Karacan, Ruiz, Cote, & Phipps, 2011). In the event of an explosion, the resulting methane flame and pressure wave can be catastrophic as evidenced by the Upper Big Branch explosion in 2010 that killed 29 miners (Page, et al., 2011). Since the mining process is transient, it is difficult to determine exactly where these EGZs exist, but investigative reports show in many cases, these EGZs can be near the working face, behind the shields, or within the gob area (Brune, 2014) (McKinney, et al., 2001). Additionally, miners have recounted seeing flames moving back and forth within the gob and under the roof supports (McKinney, et al., 2001) and in other cases, anecdotal evidence of hearing small pressure pops deep within the gob area (Brune, 2014)."

Jan 1, 2019

By I. Pérez-Rey, J. Arzúa, L. R. Alejano

"The decrease in strength with increasing rock specimen size is usually associated to the increase in the number of defects inside the specimens at small scale (centimeters) but also to the role of the rock mass structure at the rock mass scale (meters to decimeters).This matter of concern was particularly focused when determining the size of pillars in underground mines. Some formulae regarding strength of pillars have been proposed but they usually consider only the size and shape of the pillars and the strength of the intact rock. The structure tends to be overlooked or hidden behind the scale, but it is probably very relevant. For standard tunnel design, the approach by Hoek and Brown (1997), taking the structure into account in terms of the GSI, is commonly used. However, this approach does not specifically consider the size of the tunnel. Thus, a size larger than the so-called representative elementary volume is implicitly contemplated.The authors have recently performed a lab study on the effect of the structure in the strength, deformability and post-failure characteristics of granite at lab scale (NX size) extended here. This experimental program included intact and artificially jointed rock specimens. Obtained results permit to observe the changes in strength, deformability and post-failure behavior of this “small scale rock masses”, associating the role of the structure to the observed complete stress-strain response of the specimen, which can improve our understanding of the actual complete mechanical response of rock masses."

Jan 1, 2015

By C. C. Li

Traditionally, strong and stiff devices, such as fully encapsulated rebar bolts and concrete lining and arches, are preferred for underground rock support. The attention is paid to the strength of the devices in such support designs. It has been observed in engineering practice that support systems composed of stiff devices are often subjected to premature failure in high stress rock conditions. In the past decade, yield support devices have been employed to improve the performance of rock support systems. A rock support system usually consists of both internal and external devices that are installed within the rock mass and on the free surface of the rock, respectively. Great efforts have been made to make support devices yieldable in the past years, but the efforts are focused on different aspects in the tunneling and mining branches. In the tunneling branch, the focus has been put on the development of external yield devices, such as Lining Stress Controller (LSC), Honeycomb element and compressible concrete, which are embedded in shotcrete liners, while in the mining industry the efforts has been on the development of yield rockbolts, such as the cone bolt and the D-Bolt. The internal and external support devices are not compatible in their deformation capacities in the current rock support systems even though yield devices have been employed. All the devices in a support system should be deformable and compatible in deformation capacity. With such a support system, premature failure of individual support devices could be avoided and the service life of the support system is prolonged. It is a trend at present to take into account the energy absorption capacity, instead of simply the strength, of support devices in rock support design.

Jan 1, 2015

By N. E. Nelson

"The Hidden Creek mine is about l~ miles north of the north end of Granby bay; a nearly landlocked body of water on the west side of Observatory inlet; 90 miles north of Prince Rupert; British Columbia.The main haulage way of the mine at 385 feet above sea-level has been driven north into the somewhat precipitous end of a north-south ridge that rises from the tide flats between the east and west forks of Hidden creek. The outcrops of the principal orebodies, two prominent bluffs of stained rocks and sulphides, were higher on the face of the ridge and extended from about 530 to 850 feet elevation. North from the bluff tops, the ridge comb rose gradually to about 1,200 feet elevation. The name of the discoverer and the date of discovery of the Hidden Creek orebodies are probably unknown, but the discoverer is believed to have been an Indian from one of the reservations along Observatory inlet. The deposit was brought to the attention of John Flewin, Government Agent at Post Simpson, near the beginning of the present century. Mr. M. K. Rodgers, developer of the Nickel Plate mine at Hedley, did the first organized work on the deposits. Next the Hidden Creek Copper Company prospected the property. Rodgers acquired the prospect a second time, did more work, and finally in 1910 optioned the property to the Granby Consolidated Mining, Smelting and Power Company, Limited, at that time operating at Phoenix and Grand Forks in the Boundary district of British Columbia. The optionees stepped up the development work and brought the property to production in 1914. The ores were direct smelted until 1924. In that year a mill was built. From 1930 until the end of the productive life of the properties in 1935, all of the ore was milled and the concentrate smelted. From March 17, 1914, until July 31, 1935, the production from the Hidden Creek mine was, in round numbers, 18,000,000 tons of 1.70 per cent copper ore and 6,000,000 tons of low grade dilution rock. The Hidden Creek mine ""died with its boots on"". During 1934 the average monthly production was 146,377 tons of 1.06 per cent copper ore. For 7 months of 1935 the average was 161,750 tons of 1.03 per cent ore, and for the final month, July 1935, the production was 156,950 tons."

Jan 1, 1954

By K. J. Fair, G. Van Weert, J. E. Schneider

"IntroductionCyanidation is the principal process for extracting gold from ores . Many primary gold ores, however, are partially or totally refractory in the conventional cyanidation process.Considerable success has been achieved with new gold leaching techniques, such as intensive cyanidation, pressure cyanidation, carbon-in-leach cyanidation, etc. These techniques however, do not offer substantial gains in gold extraction from refractory pyrites.The more drastic pretreatment processes such as roasting, chemical oxidation, autoclave oxidation, and bacterial oxidation all utilize oxidation to break down the structures of pyrite and arsenopyrite. This generally renders the gold amenable to cyanidation.Comparative cost studies indicate that the oldest commercial pretreatment method, i.e. high temperature roasting, is currently the least expensive option if the sulphuric acid can be sold. It operates with air at atmospheric pressure and is characterized by fast reaction rates. For an alternative hydrometallurgical con centrate treatment method to be competitive, it too should operate with air at atmospheric pressure and with fast reaction rates. The NITROX process meets these conditions."

Jan 1, 1986

By H. Houali

Corrosion is an electrochemical process that causes degradation and deterioration of various steel works (pipelines, drains, cisterns) whether they are buried, immersed, or not. Worldwide, we estimate that corrosion destroys a quarter of the annual production of steel at a rate of 5 tons per second. Several techniques are used to protect against corrosion. Among these processes, Cathodic protection, which is regarded as the best technique to assure the protection of steel, works against this phenomenon. This is achieved either by a system of reactive anodes, or by the technique of impressed current protection or other techniques. Before any installation of cathodic protection, a preliminary study and pre-evaluation of certain parameters must be made. In the present work, we will present an example of dimensioning of an installation of cathodic protection by imposed current of a pipeline using solar energy, where we discuss the following items: ? Evolutions of the potential as well as current along the pipeline and their respective expressions deduced from the laws known as telegraphists; ? Range of protection (potential of protection along the pipeline); ? Influence of the isolation resistance of the coating on the range of protection; Effect of the aging of the coating and its influence on the current of protection

Jan 1, 2005

By K. Niboucha, M. Zergoug, S. Brick-Chaouch, H. Houali

"Corrosion is an electrochemical process that causes degradation and deterioration of various steel works (pipelines, drains, cisterns) whether they are buried, immersed, or not. Worldwide, we estimate that corrosion destroys a quarter of the annual production of steel at a rate of 5 tons per second. Several techniques are used to protect against corrosion. Among these processes, Cathodic protection, which is regarded as the best technique to assure the protection of steel, works against this phenomenon. This is achieved either by a system of reactive anodes, or by the technique of impressed current protection or other techniques. Before any installation of cathodic protection, a preliminary study and pre-evaluation of certain parameters must be made. In the present work, we will present an example of dimensioning of an installation of cathodic protection by imposed current of a pipeline using solar energy, where we discuss the following items:•,Evolutions of the potential as well as current along the pipeline and their respective expressions deduced from the laws known as telegraphists;•,Range of protection (potential of protection along the pipeline);•,Influence of the isolation resistance of the coating on the range of protection;•,Effect of the aging of the coating and its influence on the current of protection."

Jan 1, 2005

By S. Banisi, M. Maleki-Moghaddam

Direct observation of charge shape and its motion in industrial mills is not possible; therefore, a combination of analytical and physical studies is used to determine charge trajectory. Software packages, which predict charge motion consider only the outermost layer of charge (single ball) and ignore the charge and the interactions of grinding elements. In the new version of the GMT (Grinding Media Trajectory) software, the effect of liners specification and bulk load on charge shape and trajectory are considered. The charge trajectory was measured in a laboratory mill with the diameter of 100 cm and length of 21.5 cm with the transparent end and compared with that of the old version of GMT. Four types of polyurethane rings were accurately machined to scale down the liners arrangements at two industrial mills. The model mill was operated at 55, 70 and 85% of the critical speed for five levels of mill filling (10, 15, 20, 25% and 30% by volume). The experiments indicated that the end walls effect was negligible for the model mill with the length of 10.8 cm and beyond. The proposed relationships to correct the trajectory and charge shape were validated by using the new liner of the Gol-E-Gohar iron ore company AG mill. The positions of shoulder, toe, toe departure and impact points were predicted with the relative errors of 5, 0.7, 2 and 0.2%, respectively. The GMT software was updated with the new relationships. The results of GMT simulation indicated that when the lifter face angle increased from 7 to 30°, the distance between the charge impact point and the toe decreased from 40.1 to 11.2° for 30% filling. The change in the position of the impact point meant increasing the probability of charge impacting the toe, not the liner which favored more efficient comminution practice.

Jan 1, 2016

Adaptive processing is often related to the mineral composition of the mining block currently processed. The portions of waste, ore and secondary product minerals considered are always positive and typically sum to 100% (i.e. a composition). A typical solution to predict block averages of spatially dependent quantities would be block kriging. However, kriging is based on spatial correlations and it has been repeatedly shown that correlations of compositional data are spurious and blurred by the constant sum constraint. Aitchison (1982) proposed a general solution for compositional problems, based on transforming the compositional data to a set of logarithms of ratios of components, and analysing the transformed scores. The transform is chosen to be invertible to ensure that no information is lost in the process. This methodology avoids spurious correlation problems and ensures coherence between results obtained with different subcompositions. Pawlowsky-Glahn and Olea (2004) adapted the approach for point-support geostatistics, allowing the prediction of point compositions from spatially neighbouring data, without the artefacts induced by standard multivariate cokriging. Unfortunately upscaling the results of this approach with block cokriging is not straightforward, because of the nonlinearity of logratio transforms. Furthermore, we have to consider those nonlinearities created by the dependence on the block composition of extraction efficiency and processing costs of the possible processing choices. This paper proposes a solution for predicting the conditional expectations of the benefit of processing the block with each processing choice using geostatistical simulations of the local values of the composition and the resulting block integrals. The computation for a large number of blocks can be done efficiently using Cholesky decomposition. The approach also allows the calculation of prediction errors for expected compositions and expected benefit at almost no additional computational cost. Such compositional approach is necessary, for example when processing choices depend on proportions of certain minerals after other components have been removed; or if processing alters the composition in a multiplicative way, by partially removing a portion of some components.

Aug 1, 2013

By Joël P. T. Kapusta

Back in 1995, Air Liquide and Union Minière presented a joint paper at the Copper 95 – Cobre 95 Conference in Santiago, Chile, describing the first full scale plant trials of shrouded sonic injection in a Hoboken converter at the Hoboken smelter in Belgium. Almost a quarter of a century later, the technology known as ALSI, or Air Liquide Shrouded Injection, has been tested or commercially implemented in several copper and nickel smelters. Despite these successes, the copper industry did not adopt it widely in the same manner the steel industry adopted the Savard-Lee tuyere in the 1970s and beyond, not even in the way the lead industry adopted it with the Queneau-Schuhmann-Lurgi, or QSL, process. The development and implementation of bottom-blowing smelting and converting technologies in China in the last ten years, however, changed the industry’s perception that high- and ultra-high oxygen injection in copper smelting and converting was indeed possible under specific process conditions. In this paper, I retrace the key learnings of my journey with sonic injection over the twenty five years from my humble beginnings in my early years with Air Liquide, through plant trials and technology implementation in the late 1990s and into the first decade of the new millennium, and ultimately, to the most conclusive proof that the sonic injection design methodology I established is valid, and the calculation tools I developed are accurate. I conclude by sharing my thoughts about whether the deployment of the Savard and Lee legacy within the nonferrous industry was just a pipe dream or whether it will become a reality. INTRODUCTION In the context of lower quality ores and changing economic markets, copper smelters need to continuously innovate and improve to remain competitive and respect their corporate social responsibility engagements. One avenue towards this business, social, and environmental goal is to increase process intensity while lowering fossil fuel consumption to lower greenhouse gas emissions and reducing process off-gas volumes to better capture As and SO2–laden emissions. I believe high oxygen sonic injection for submerged tuyere copper bath smelting and converting is one technology that can help smelters achieve that goal of higher business, social, and environmental performance. Twenty five years ago, when I discovered that the Savard-Lee tuyere had revolutionized the steel industry (Savard & Lee, 1966; Knuppel, Brotzmann, Fassbieder, Savard, & Lee, 1972), I had a dream — or was it a vision? — that within the first decade of the new millennium, modern copper smelters operating submerged tuyere bath smelting and converting vessels will have implemented high oxygen sonic injection and will be reaping the financial and environmental benefits that the steel industry enjoyed in the 1970s. As we approach the end of the second decade of the new millennium, I have to admit that my dream has been all but shattered as the majority of copper bath smelting and converting vessels today continue to operate under bubbling regime conditions. This mode of operation is archaic, still requires tuyere punching and blows at inherently low enrichment levels, particularly in converting, producing large volumes of process off-gases. Under such operating conditions, regulations and emission quotas for As, SO2, and particulate matter oblige smelters to use not just primary or secondary hoods, but sometimes even tertiary hoods. I vividly recall being told, fifteen or twenty years ago when visiting smelters to promote the application of the Savard-Lee tuyere in nonferrous processes, that implementing sonic injection was not economically viable due to the high cost of compressing air and oxygen. Some of the smelters I visited back then have since mandated their engineering partners to design and build secondary or even tertiary hoods. I cannot fathom how secondary and particularly tertiary hoods, with all of their auxiliary equipment and added ducting, could be more economically viable than purchasing and installing a few compressors, expanding the pipeline network for compressed air and oxygen, and installing a new control valve train to feed sonic tuyeres. Besides, adding hoods does not address the problem of As and SO2-laden fugitive emissions at its source but merely provides a costly mitigation for it by capturing larger volumes of process off-gases rather than reducing these large volumes in the first place. Moreover, hooding does not reduce energy consumption nor does it increase process intensity, two aspects that I believe are critical for smelters to remain competitive and sustainable in a deeply changing market environment.

Jan 1, 2019

By H. E. Lake

VERY EARLY in the initial stages of underground development work at Eldorado's Beaverlodge operation, the decision was made to use mill tailings as a backfill product. Mining and milling commenced in June, 1953, using locally available sand as backfill, while test work and installation of a plant was carried out to prepare ?and deliver the tailings to the mining areas. The first use of tailings was made in February, 1954, a sandslime separation being carried out with hydraulic cyclones. To date (January. 1956), approximately l 40,000 tons of fill have been used in the stoping areas, providing very effective support in a 50 deg. Vein system of cut-and-fill mining. The recoverable portion of the mill tailings amounts to 40 to 45 per cent, which has resulted in a product giving a percolation rate of 6 to 10 inches per hour. Owing to the fact that Eldorado has milled from 15 to 2 5 per cent more ore than it has mined, through the purchase of custom ore, the degree of control on the sand-slime separation has not been as critical as it might normally be when the filling operation must depend only on the tailings from ore mined. A description of the conditions involved and of the plant as finally installed is given below. It might be mentioned here that, with the impending increase in milling capacity from 700 tons to 2,000 tons p.er day, the present plant will be considerably altered within the ensuing year to handle the increased tonnage and distribution.

Jan 1, 1956

By R. D. Brown

Ever since British Columbia started the ball rolling in 1974 with the introduction of its now-defunct Mineral Royalties Act, all Canada's resource-based provinces have significantly altered their mining tax systems. The last resource-based province to abandon its pre -1974 mining tax structure is New Brunswick, which introduced a new mining tax regime in the summer of 1977 to take effect from April 1 1977. The new structure, which represents the outcome of considerable study and discussions with industry representatives, contains some intriguing concepts which make Nero Brunswick's new mining tax system unique among the Canadian provinces.

Jan 1, 1977

By R. W. Thompkins

MINE operators are concerned with temperature conditions in their mines, particularly the effects of high temperatures on the l1ealth and efficiency of tl1eir employees. This paper is written to focus attention on the variables of heat transfer between rock and air. It illustrates the difficulties of predicting the manner, and the extent, of heat transfer from theoretical concepts, prior to actual operation of a mine airway. There are ~1any sources of heat in mines. The most important is that of the rock surrounding the airway. This heat, in turn, is a product of the age of the rock, faulting, proximity to recent igneous activity, oxidation of sulphides, hot ground waters, etc. The sources of heat may be constant for any one mine, but they are far from constant when dealing with various mining districts or e1•en with a number of mines in the same district. A second source of heat is that produced by machinery in operation. Practically all the waste

Jan 1, 1962

By E. You

The concentrator at Kennecott Utah Copper currently has 4 lines with a configuration of one SAG mill feeding two ball mills. The slurry that reports to each ball mill will vary resulting in an unequal load of material. This configuration contains two separate sumps that receive material from a distribution box relying solely on natural slurry flow to feed each sump. The unequal split to each mill results in one mill receiving a greater amount of material. This will result in the equipment on one mill reaching limitations that may affect product quality and the operation of the equipment near maximum. The parallel mill in this condition will often have additional capacity that can be used but cannot be utilized due to the unequal split. The major consequences of this issue result in reduced throughputs and metal recovery. To resolve this condition an advanced control strategy was implemented to control the split in April of 2002 using equipment that was in place.

Jan 1, 2007

By G. Mousavian, R. Bagheri, N. Dalili

Polypropylene (PP) and its composites have an increasing use in automobile and domestic industries. Since the published results on strain rate effect on yield behavior do not match, and there is a high attention paid for effect of nanometeric fillers on deformation behavior of composites, in this research the strain rate effect on yield behavior of PP and the effect of nanometeric fillers on deformation behavior of PP have been studied. Microscopic observations and tensile tests in different strain rates on neat PP samples and on samples filled with 5, 10 and 15 %wt have been used. A dramatic change in behavior for the modulus and post-yield slope curves when the strain rate is between 0.0433-0.05 s-1 has been observed. Microscopic observations on PP indicate a change in deformation mechanism from shear yield to crazing at the same strain rate that the change in behavior of curves occurs. It has been observed that in PP nanocomposites with higher amount of calcium carbonate, fracture in early stages of deformation occurs in lower strain rates. In other words for a fixed stain rate there is a critical filler percentage such that if the filler percentage is higher then early-stage fracture will occur. Similarly for a fixed filler percentage there is a critical strain rate and in higher strain rates early fracture will occur. The critical stain rate will decrease as the filler percentage increases and vice versa.

Jan 1, 2006