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By F. B. Foley

IT is with an unusual degree of personal satisfaction that I find myself in a position to pay tribute to the memory of Henry Marion Howe. One could not have spent any length of time in the presence of Dr. Howe without profiting intellectually. I do not hesitate to say that my years of association with him were the most stimulating of all my years of metallurgical study. He always impressed one with his own eager search for knowledge. Never dependent on the written word alone he sought information from anyone whose opinion he valued. His ability to piece together bits of apparently conflicting data from various sources so as to build up a logical hypothesis was unique. A small slight man with the intellect of genius he would have gone to the top in any endeavor he undertook and it was fortunate for metallurgy that its study attracted him as it did. Howe was a modest man. I like to recall an incident which left a lasting impression with me. The lab- oratory in his home, "Green Peace," was in the basement and access was by way of stairs leading down from his secretary's room. In using these stairs my attention was attracted many times to an ordinary cardboard shoe box which reposed on the shelf above the landing. It was crudely labeled on its side in black ink "Vanity Box." My curiosity was aroused to the point that I finally asked his secretary what it was. With some amusement she took the box from its shelf on the stairway, opened it and showed me its contents—numerous letters, from the foremost men of science of every civilized country throughout the world, commending his "Metallography of Steel and Cast Iron." I recall that in reply to one who thought there was not enough of Howe's own researches in his book he wrote, "Primarily I am a writer, secondarily an investigator." Howe wrote to make his readers think. No one ever strove harder than he to be right but above all, whether his viewpoint proved ultimately to be right or wrong, he was always content if by his stand, he provoked a reader to take the next step along the path to greater knowledge. I doubt that he was ever afraid to be wrong for he was always secure in the thought that his effort was guided by a sincere search for the truth. One continually searching for truth is entitled to occasional excursions up the wrong alley. A glance backward to the metallurgical confusion of some thirty to forty years ago, or need one go back so far, provides convincing proof of what a host of companions one may have in a common acceptance of ideas which the future will prove to be wholly untenable. Well over a hundred years have passed since investigators have interested themselves in the effect of increasing the temperature of iron and steel on their mechanical properties. We are told by Charles Walrandl in "Industrial Annals" for June 11, 1822, that bend tests, conducted in a Russian steel works of Prince Demidoff, on steel bars "highly heated" and bent during cooling became brittle when bent at an iris blue color. He concluded, "That when steel is heated to a temperature between 473°F and 662°F the mettle was more brittle between these limits than at a much lower or at a much higher temperature." It was a curious bit of information recognized as true to this day and still not explained satisfactorily. In 1878 Charles Houston in Annales de Mines associated this brittleness with an increase in tensile strength at 572°F. When this relatively low temperature is exceeded it is recognized that steel becomes weaker as temperature is increased up to the melting point, where no strength of practical importance remains. It is easy to believe, in fact it goes without saying, that this weakening as the temperature of a metal is increased is the result of the motion of the atoms making up the metal, a motion which itself is evidence of the temperature increase. However, if we are considering iron or steel we find that this decrease in strength is not a steady one, for, besides the increase in strength just referred to, one comes to a temperature, the critical temperature, where results of tests indicate the metal to be extremely weak and then as temperature increases to become sensibly stronger again. This apparent anomaly was made the subject of the first Howe Memorial Lecture, delivered by Albert Sauveur in 1924. It may be of interest to review these findings of Sauveur. He used two methods of investigation. One involved the twisting of bars. The bars were heated in an

Jan 1, 1951

The development of information concerning mesothelioma in South Africa started with the 1959 finding of Dr. J. Christopher Wagner of cases of mesothelioma in persons living in the vicinity or working in crocidolite mines in Cape Province. After more than 40 years, the data from South Africa now provide important insights into the differences in mesothelioma risk associated with different asbestos fiber-types. Three case series reports and one analytical report were reviewed in this session. In total, information on 504 proven cases was presented. There were 28% of cases arising from occupational exposure in mining, 35% from non-mining occupations, 23% from environmental exposures; 14% where no exposure was established and 9% where the exposure was unknown. Among the 129 cases for which occupational exposure and asbestos fiber-type were established, 115 cases were associated with occupational exposure to Cape crocidolite; 1 case associated with occupational exposure to Transvaal crocidolite and 9 cases with occupational exposure to amosite (grunerite asbestos) and 4 cases with occupational exposure to mixed fiber-types. There were no cases associated with chrysotile asbestos. There were 33 cases of environmental mesothelioma linked to Cape crocidolite exposure and 2 to exposure to amosite and crocidolite but none to Transvaal amosite alone or to chrysotile. The evidence shows that amosite is capable of causing mesothelioma but that the major risk in South Africa is associated with Cape crocidolite.

Jan 1, 2008

By Thomas H. Dubaniewicz

Thirteen miners died as a result of 2 explosions in the Jim Walter Resources No. 5 mine near Brookwood AL in September 2001. Both explosions were ignited in intake air entries, and both were probably ignited by electrical equipment. With few exceptions, permissible equipment is not required in intake air entries of US underground coal mines Researchers with the National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory. studied the electrical equipment ignition sources for the Brookwood and other w disasters to develop recommendations for preventing similar disasters Adherence to National Electrical code® requirements for flexible cords installed in hazardous (classified) locations may have prevented the second massive Brookwood explosion. The 30 CFR Part 7 requirements for battery assemblies should be reevaluated, taking into consideration United Mine Workers of America recommendations and the Zone 1"increased safety" standard requirements for battery assemblies, Class 1 Division 2 or Zone 2 explosion protection techniques are recommended for intake air equipment so that they do not present a methane air ignition source under normal operation before mine power is shut down during emergencies Battery powered circuits intake air that are likely to remain energized during emergencies should be protected by more stringent protection techniques, to protect rescue/recovery personnel. Index Terms -Class 1 hazardous location, mine explosion, flexible cord, battery assembly, permissible equipment

By Tadashi Aiura, Yasuhiro Miura

"A small amount(0.2mass%) of Scandium(Sc) was added to the 7.NOl and 5083 Al alloys as a refiner and stabilizer of microstructure, and the resulting microstructures were discussed in comparison with the effects of the conventional additives. The followings are summarized: 1) in the as-solidified structure, a ·decreased tendency of constitutional supercooling and increased solubility of Mg were recognized for the Sc-added 5083 alloy. Sc is a -better microstructure refiner for the 7N01 alloy than Zr, in a sense that it does not suppress the favorable effect of· coexisting Ti. 2) Sc effectively suppresses recrystallization both in the 5083 and 7N01 alloys. 3) The rod like primary Al3Sc crystals formed during solidification, as well as the fine dispersion of Al3Sc precipitates formed by subsequent heat treatment, can act as a strong recrystallization suppresser. IntroductionThe 7N01 and 5083 alloys are the most popular industrial Al alloys and they are widely' used for various structures because of their superior properties. Fine macro and micro structures of the materials are required for obtaining acceptable sec resistance,consistent appearance of anodized surface and good weldability, as well as good mechanical properties. In order to produce fine grain structures, transition metals, such as Cr, Zr, and Mn, have been conventionally added.It has been reported that Sc is an efficient refiner [l, 2] and can be an alternative for the conventional and also suppresses recrystallization in Al alloys [3,4]. Scandium is the lightest transition element and forms an equilibrium intermetallic phase. The equilibrium phase, Ll2-Al3Sc, is coherent with the matrix, and of _spherical shape. A fine dispersion of the spherical precipitates is obtained by quenching and aging after solutionizing annealing. The authors have already reported a part of the experimental results on the effect of Sc on the as homogenized microstructure of the 5083 alloy [5]. In the present study, the effects of Sc on the macro and micro structures of the industrial high strength Al alloys(7N01 and 5083) for extrusion are investigated, and the superior role of Sc as a grain refiner is shown"

Jan 1, 2000

By G. R. Hopkins

[A new record in fuel efficiency at petroleum refineries was established in 1939, when a the average B.t.u. requirements per barrel of crude oil processed declined to a new low of 557,000 B.t.u. (see fig. 1). The average fuel requirement per barrel of crude oil refined has remained virtually stationary for the past 3 years. Thus in 1937 the average was 562,000 B.t.u., in is it rose to 567,000 B.t.u., and in 1939 it declined to 557,000 B.t.u. she largest gains in fuel economy cane a decade or so ago on the widespread introduction of heat exchanges and pipe stills. In recent years many successful innovations in heat saving have been adopted, but the combined effect of those is completely masked by the degree to which the capacity is utilized. Some heat requirements are relatively inelastic, so the average consumption per barrel of crude oil refined tends s to increase when the operating ratio (crude runs divided by capacity) declines and vice versa. In 1939 crude runs to stills increased 6 percent (from 1,165,015,000 barrels in 1938 to 1,237,840,000 in 1939) compared with a decline of about 2 percent in 1938. The operating ratio in 1939 was 82 percent compared it's 78 percent in 1938.]

Jan 1, 1941

By Xu Lin Sheng

During the mining course, when the roof above coal seams is constituted by thick and hard sandstone (conglomerate), sudden roof movements often take place with great force and de¬struction which is the biggest danger to the safety and production. Such sever movements of the roof in mining directly relate to the rock mechanical properties which are the main fac¬tors that influences the regularity of hard roof movement and its destruction form. A significient work and important technical way for applying rock mechanics into mining en¬gineering is studying the rock mechanics of the hard roof and altering some of the rock me¬chanic parameters which induce the improvement of the rock properties in order to efficiently control the movement of the hard roof.

Jan 1, 1989

By J Graaf, R A. Murrell

Gold Fields Australia is constructing two major ventilation shafts at the Wallaby gold mine in Western Australia. The new ventilation shafts are required to facilitate the long term ventilation strategy for the mine, thereby allowing continued extraction of ore beyond 1000 m below the surface. The construction work has involved all of the challenges that shaft construction can throw up, including challenging geotechnical conditions, unexpected high water inflows and major circulation loss during pilot hole drilling for raise boring. An extensive geotechnical and hydrological investigation program was undertaken prior to awarding the shaft construction contracts. While most of the risks were identified, several proved to be much more challenging than expected. The shaft construction methods included conventional sinking into the fresh rock profile in each shaft, followed by raise bore pilot hole drilling and reaming. A headframe was constructed for the first shaft, which was sunk to 92 m with a stage suspended in the shaft to facilitate the concrete lining and provide rope guides for the kibble winding. Drawing from experience when sinking the first shaft, additional ground pre-conditioning was implemented for the second shaft, which was pre-supported with continuous piles to 28 m followed by sinking to 50 m using a crane instead of winders and a headframe. Following the conventional sinking through the weathered zone in each shaft, the shafts were completed using a raise bore. The first shaft utilised a riser pipe and rotary vertical drilling system (RVDS) with the second shaft having utilised a dual rotary rig for pilot hole drilling. This paper reviews the site investigations undertaken, construction methodologies applied, the results achieved and the lessons learnt.CITATION:Murrell, R A and Graaf, J, 2017. Shaft construction at the Gold Fields Wallaby mine, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 321–334 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By E. J. Jacques

A typical problem in ventilation networks with multiple fan systems is the possibility of them interacting. Multiple fan systems are no exceptions in complex tunnels, and may also be met in mines where underground fans are installed. When aiming at controlling a multiple fan system in a ventilation network, e.g. with a view to maintaining an acceptable air quality level, yet at minimum power consumption, transient flow conditions frequently occur. Although in most applications these transients are short compared to the time needed to achieve the planned actions on the ventilation, one should, however, keep in mind that it is important to avoid any bouncing effect between different (adjacent or distant) fan systems. Therefore a simulation of the unsteady-state flows could allow us to learn more about the propagation of transients within the network, and their possible secondary effects Among others, one question that often is raised, is to find out in which sequence and at what time schedule each of the fans in a network should e.g. be started up? Another typical problem, into which an unsteady-state simulation could provide some insight is the following: how should the facilities of variable pitch angle and/or changeable RPM of several fans operating in parallel be handled and combined in order to obtain a flow rate that changes gradually from zero to its maximum value i.e. the sum of the individual throughput flows of all the fans. The literature is not very abundant on the topic of simulating transient flows in networks. There is no doubt that numerical models have been developed (Pollak, Christensen, 1987), most of the time for particular applications (Wala, Kim, 1985), (Tanaskovic et al., 1984), (Schultz, Sockel, 1991), etc. The aim of this paper is to present a model that also simulates one-dimensional compressible flows in unsteady-state conditions with, however, the specific intent to handle networks with more than one fan. PROBLEM STATEMENT The mathematical model chosen to describe the unsteady flows in a ventilation network is based on the dynamic and continuity equations applied to each of its airways. The following basic assumptions are made : - the flow in the airway is considered to be one- dimensional, - - the flow is assumed to be fully turbulent, and hence the ATKINSON equation for calculating the friction losses will be applied. Whether this equation remains valid for transient state flows remains an open question. However, this may reasonably be assumed since the interesting flow frequencies are low. A discussion may be found in (Kämpf, 1987) ; - the airways are assumed to have a constant cross- sectional area along their length. If obviously this would not be the case, it is always possible to subdivide the concerned airway into sections for which the previous assumption holds. Applying the basic equations of mass and energy conservation, the flow in each branch may be described by the Euler equation for Newtonian flows.

Jan 1, 1995

By Jun Xiao, Xiaodong Li, Chunming He, Daixiong Chen

"Benzohydroxamic acid with double dentate can react with copper to form cyclic hydroxyl oxime acid copper chelate, indicating a good selectivity for copper oxide minerals flotation, especially for malachite. The flotation results of the pure malachite mineral show a strong synergistic collecting effect between hydroximic acid and xanthate at a ratio of 3.5:1, achieving a malachite recovery of 95.5% when certain sodium sulphide is used as a sulphidizing agent in the optimal pH range. Thanks to the synergistic collecting effect, the flotation recovery of malachite of a real refractory ore flotation ,can reach over 92% under the optimum condition, a 12% higher than the recovery achieved with the conventional collectors. In industrial application, the flotation of the copper oxide minerals is improved , leading to a high efficiency utilization of copper oxide resources.INTRODUCTIONBeneficiation of copper oxide ore is one of the recognized challenges in mineral processing industry. Copper oxide ore is a vital component of copper resource in the world, which has abundant reserves. Majority of sulphide deposits has oxidized zone on the top, and some deposits are oxidized to become the large and medium-sized oxide deposits (Willam & Chavez, 2001). Most copper oxide ores have problems in processing such as high slime consumption, poor floatability, complex ore property and low flotation recovery, so it is of great significance in beneficiation of copper oxide ores to develop an efficient collector, especially for malachite (Fu & Gu, 1997; Wen, 2010; Riet, Kier & Elford, 1980). At present, sulphidization-xanthate flotation is the most important method for treating copper oxide ore. In recent years, due to the decreasing ore grade, the utilization of refractory copper oxide ore draws more and more attention (Zhou, 2003), except for sulphidization-xanthate method, chelating flotation method (Lu, 2009), chemical beneficiation method (Lenormed, Salman & Yoon, 1979), microwave radiation flotation method, hydrothermal sulphidization-flotation method (Mao, Wen & Fang, 2014) and ammonia leaching of sulphide precipitation-flotation method (Lekang, Stevik & Bomo, 2003) have occurred."

Jan 1, 2016

By L. Andrews, G. Smits, M. D. Adams, E. A. Viljoen

A new approach has been developed that is capable of ascertaining the ore component that is responsible for the preg­robbing of pregnant pulps. Many gold mines are currently treating ores containing a component that is detrimental to the recovery of gold, in that they "preg-rob" the pregnant pulp by adsorption of some of the dissolved gold. The identity of the preg-robbing component in this type of ore has been the subject of considerable debate over a lengthy period, th various suggestions including amorphous carbon, chlonte, chalcopyrite and layered silicates, such as the phyllosilicate minerals pyrophyllite, kaolinite, phlogopite and illite. A means is now available to identify and characterize the preg-robber in gold ores. This new approach consists of contacting the ore with a synthetic aurocyanide solution, identifying the mineral grains by optical microscopy and analysing each grain individually using high-sensitivity electron microprobe analysis. The approach is exemplified in this initial study by identifying the preg-robbing component in an active sample of gold-bearing shale to be an amorphous carbonaceous phase consisting of discrete particles of about 5 µm diameter interspersed with shale particles and agglomerated into grains of up to 100 µm diameter. Microanalysis of these grains as well as other mineral particles revealed that the gold content of some of the carbonaceous grains was close to 7000 g,lt, with no gold being detected in any of the other mineral phases that were found to be present (e.g. quartz, chlorite, muscovite, pyrophyllite, etc). Bulk analysis of the sample for carbon and gold confirmed that gold loadings of around 7000 g,/t would be expected if all of the gold were adsorbed onto the carbonaceous component. The carbonaceous constituent is probably also responsible for the anomalously high surface area measured for the material. It probably acts in a similar fashion to activated carbon, and the correct choice of organic blinding agent will decrease the extent of preg-robbing by lowering the activity of the material for gold, without causing any downstream problems such as fouling of the activated carbon used for gold recovery

Jan 1, 1993

By Ryan Sullivan, Lisa Smiley, Jewels Stover

The Westerly Storage Tunnel (WST) Project is part of Project Clean lake, the North East Ohio Regional Sewer Dist years. When completed in 2020, WST will be nearly 2 miles of 25-ft diameter tunnel 200-250 ft below ground. The storage tunnel will manage higher flow volumes, keeping stormwater out of the combined sewer system reducing overflow occurrences. Three deep shafts provide access to the tunnel at the tunnel boring machine (TBM) launch and retrieval sites, as well as a vent shaft. Support of excavation for the access shafts was constructed utilizing unreinforced concrete diaphragm walls. This innovative, value-engineered alternate design significantly reduced risks associated with conventional secant piles combined with a rib and liner plate system. Implementation of the diaphragm wall technology resulted in a water tight, continuous shaft keyed into rock. This case study examines the design, methodology, and installation challenges unique to each shaft, as well as the benefits of the final product to the overall project.

By Tracy Brettmann, Will Bohlen

An innovative retaining wall design consisting of tangent drilled shafts with supplementary seal piles was used to limit continuing bank erosion along the Brazos River in Southeast Texas. The riverbank erosion had progressed to where it was threatening the stability of both the bridge abutment and corresponding approach embankment of the heavily travelled Highway 99 bridge at this location. A tangent pile design was selected because it was both much faster to install and more cost effective than a secant pile system. The design included both 5.5-ft and 10-ft diameter shafts with depths up to 130-ft and comprised both anchored and cantilevered sections. Supplementary seal shafts were also installed between the structural tangent drilled shafts to help plug any gaps between the tangent shafts. The plumbness and diameter of the shafts were tested using a sonic caliper to make sure the shafts were installed within the specified tolerance. The initial design had to be revised when a record flood from Hurricane Harvey impacted the site during construction. Introduction The Fort Bend Grand Parkway Toll Road Authority (Owner) needed to protect the north bridge abutment with a retaining wall system due to rapidly eroding conditions of the Brazos River banks within the 300- feet-right-of-way of the State Highway 99 Jodie Stavinoha Bridge. The extent of the local scour and erosion along the north bank of the Brazos River has caused concern for the structural integrity of the bridge. The magnitude of the erosion along the north bank at the location of the bridge has been measured at about 120 feet over three recent hydrologic flood events locally referred to as Memorial Day 2015, Memorial Day 2016, and Tax Day 2016. During construction, a new record flood level occurred due to Hurricane Harvey in August of 2017 that resulted in a portion of the retaining wall needing to be redesigned due to even more erosion occurring. The Brazos River is an actively eroding and meandering alluvial river plain that naturally meanders and migrates over time. The processes of bank erosion and meander migration were ongoing before the bridge was constructed and will continue in the future. These recurring major flood events, however, rapidly increased the rate of erosion in just a few years. Background. Due to the need to protect the bridge as soon as possible, the Owner selected a project team consisting of the designer, general contractor and specialty deep foundation contractor prior to final design to work together in developing a cost-effective design that could be implemented rapidly. The project team initially considered both a secant pile and tangent pile retaining wall system using drilled shafts. After reviewing various alternative designs, a tangent pile wall with seal piles was selected based on both cost effectiveness and speed of installation. The tangent pile with seal pile option was approximately 20 percent lower in cost and 50 percent faster to install.

Jan 1, 2018

By J. Philip Bromberg

Any effectuation of a viable program of air pollution control will' require a basic understanding of the chemistry of atmospheric processes, the fate and migration of SO2, and the ultimate health effects of the sulfur oxides themselves. The migration and ultimate fate of Sop discharged into the atmosphere will be discussed with particular emphasis on the various conflicting views and how these relate to our present emission control regulations. Our present lack of knowledge is a severe detriment, and consideration will be given to those particular areas where future research may best be directed to provide the answers to a number of perplexing questions.

Jan 1, 1976

By Floyd Kelley

THERE is an ever-increasing demand for furnaces with controlled atmosphere, due to the large quantities of steel being used in the automotive industry, such as the .high-chromium stainless irons, the 18 Cr, 8 Ni stainless iron and low-carbon steel sheets. The difficulties involved in the annealing of such materials, if they are to be kept absolutely free from oxidation, are many. It is possible to bright-anneal these steels in small laboratory hydrogen furnaces, using specially purified hydrogen and taking some additional precautions. In the first place, the insulation, usually of alumina or magnesia, holds small amounts of water vapor, which it is almost impossible to remove completely. Secondly, there is always condensation of water vapor in the cooling chambers of such furnaces, and with the continuous circulation of the hydrogen gas in the furnace, the water vapor is carried from the cooling chamber back into the heating chamber. This water vapor oxidizes the charge. Lastly, the supply of moisture is made sure by the diffusion of small amounts of air from the atmosphere into the furnace against the pressure of the hydrogen. The oxygen combines with the hydrogen and forms more water. Under such conditions there is, little gained by using specially purified gas, because it becomes contaminated after reaching the furnace.

Jan 1, 1931

By David Heyl

"El presente texto señala la evolución de los modelos genéticos de geología económica del yacimiento minero Tres Cruces. Dicho yacimiento se encuentra localizado en el noreste del Perú, adyacente al distrito minero de Quiruvilca. A partir del año 1995 se le reconoció como el mayor productor de oro a través de un programa de exploración en la Formación volcánica Calipuy. Posteriormente, el yacimiento fue visitado por variosgeólogos que postularon diferentes modelos genéticos del yacimiento para así estimar su potencial económico -en tanto se incrementaron los datos geológicos del yacimiento. Por ello, el texto presenta el modelo genético de Tres Cruces, como el más adecuado, aunque la evaluación de su potencial econornica está aún en progreso."

Apr 26, 1999

By Richard H. Singleton

Native asphalt was produced in 1978-79 by six companies in four States. Leading States were Texas and Utah. Output in-creased 37% in 1978 to 1.7 million tons and decreased 5% in 1979 to 1.6 million tons while value increased 39% in 1978 to $19.3 million and 33% in 1979 to $25.6 million. Bituminous limestone was produced by Whites Uvalde Mines and by Uvalde Rock Asphalt Co. in Uvalde County, Tex.; by Southern Stone Co. in Colbert. Ala.; and by Barton County Rock Asphalt Co. in Barton County, Mo. The product was used mainly in street and road repair. Gilsonite was produced by American Gilsonite Co. in Uinta County, Utah, and by Ziegler Chemical and Mineral Corp. in Weber County, Utah. This material was used for purposes other than road repair.

Jan 1, 1980

By Jr. Reed

Cassiterite was discovered in Coosa County, Ala. in 1880 by Judge John S. Bentley. Since that time intensive surface prospecting has revealed the presence of cassiterite in pegmatite bodies that occur in a zone about 20 miles long and 3 miles wide. Numerous trenches and test pits and several shafts were sunk, and one attempt was made to nine and concentrate the cassiterite commercially. The problem of a domestic tin industry and the question of the extent of the Alabama tin deposits have long been of public interest and concern. The deposits have been examined by numerous geologists and several governmental agencies, including the Geological Survey of Alabama, the Geological Survey and the Bureau of, Mines. of the Department of Interior, and others. The Bureau of Mines and the owners of the properties, Charles A. Dean and Robert A. Russell, investigated the Coosa County tin deposits under a cooperative agreement from October 1, 1948, to June 10, 1949. Sixteen hand trenches totaling 527 linear feet and 33 machine trenches totaling 6,780 linear feet were dug. Two shafts wore sunk for a total of 72 feet, and 44.4 feet of drifting was done. Thirty-one diamond-drill holes totaling 2,776 feet were drilled.. Four hundred thirty samples, representing 1,192.6 linear feet, were taken for assay and wore analyzed by the Southern Experiment Station at Tuscaloosa, Ala.

Jan 1, 1950

By R. W. Pugh, S. L. Ma

"High carbon rods are typically used as the grinding media in rod mills. Usually an AISI I 090 grade of steel is used which provides the high hardness needed for abrasion resistance and sufficient toughness to prevent rod breakage.Work to improve performance in the past has mainly concentrated on increasing the hardness for improved abrasion resistance. This has been accomplished by adding alloys to the steel which uniformly increase the hardness across the rod section.However uniformly increasing the hardness of the rod produces a more brittle product and at high hardness l1evels can lead to rod breakage problems. Heat treatment processes can be used to selectively increase the surface hardness to high levels while maintaining the core at lower hardness levels to give a product that wears slower without breakage. AltaSteel has developed and mill tested a higher hardness heat treated grinding rodThis paper describes the development of a simple model to predict performance improvement with different hardness profiles and the AltaSteel heat-treated grinding rod process. Mill characteristics of the Endako operation are summarized and predicted performance improvements based on hardmess are compared to the approximate 25% achieved in trials running since July, 1991 at this mill. Early results of other mill trials are also presented.INTRODUCTIONAltaSteel, in Edmonton is a major supplier of grinding media. We have a strong desire to continually increase the quality and performance of our products and thereby improve the efficiency of our customers' processes. In the area of grinding rods, we wanted to produce a product with a significant improvement in wear rate. Second to energy, rod consumption usually represents the next highest cost in processing. This paper presents our development of a heattreated grinding rod that has reduced consumption by about 25% in trials to date."

Jan 1, 1993

By T. McCallum, C. Cooper, B. Hutzler

"In copper solvent extraction, managing the quality of the organic phase is a key parameter to ensure optimal physical and metallurgical performance in the plant. Increased throughput as a result of declining ore grades coupled with advances in plant design and practice, resulting in reduced organic losses, has pushed the limits of the status quo with respect to organic quality. Clay treatment of plant and recovered organic at the optimal dosage is critical in maintaining quality, however, achieving the optimal dosage through existing filtration capacity and practice can be difficult. Cytec has developed a process aid that increases efficiency of existing filtration equipment that has been successfully implemented at two commercial SX operations. ACORGA® CB1000 enables higher dosages of clay while allowing for more efficient use of existing filtration capacity. This study analyzes results from commercial trials and demonstrates that improved organic quality and clarity is achievable through optimization of current treatment practices. INTRODUCTION Decreasing ore grades have prompted copper solvent extraction operations to raise PLS flow rates, increasing plant throughput to maintain production1. The ability to process higher flow rates through existing mixer-settlers historically came at the expense of increased entrainments2. However, advances in mixer-settler design, practices and improvements in organic recovery processes have enabled operations to maintain, and in some cases reduce organic losses while achieving higher flow rates through existing equipment. Based on the increased demand on the SX equipment and reduced losses (or more efficient recovery) maintenance of the circuit organic quality through efficient clay treatment is now more important than ever. This paper discusses common industry practices and related issues in organic clay treatment, and presents benefits achieved in commercial operations through the use of ACORGA® CB1000 Clay Binder. IMPROVEMENTS IN DESIGN AND PLANT PRACTICE Mixer-settler design has improved since the first commercial copper SX operation in the late 1960s. Advanced designs in mixer, settler, and settler internals have contributed to reductions in entrainments. For example, improved impeller designs have been reported to decrease organic in aqueous entrainment from the ‘old designs’ of 50-200 ppm3 to as low as 4 – 10 ppm confirmed via diluent and reagent consumptions . Similarly, operations are reporting a 20-50% decrease in reagent consumption when compared to the original design criteria3. Operations have optimized settler internals to increase coalescence and have improved settler operating practices which have been shown to reduce entrainments7. Comparison of the SX world operating data from 1999 and 2007 shows reductions in organic entrainment losses with increases in flow rates."

Jan 1, 2015

By F. Vasilikou

Commercial deployment of Carbon Capture Utilization and Storage (CCUS) requires field testing of a scale that can stress the geologic reservoirs. One such reservoir of interest consists of unminable coal seams that exhibit favorable characteristics and depositional environments and lower pressure and temperature than other, deeper, reservoirs. Such conditions can reduce compression costs while utilizing the action of adsorption that offers a more effective carbon dioxide (CO2) bonding than free storage or solution. To ensure the success of such tests, a number of parameters should be accurately determined, such as the seam geometry and stratigraphy, coal porosity and permeability parameters as well as optimum injection conditions. In essence the CO2 injection model should be calibrated for the reservoir characteristics using all available data. History matching calibrations are based on gas and water production from existing wells prior to injection. This paper will present reservoir models that were developed for a pilot--scale 907 tonnes (1000 tons) CO2 injection test that was performed in 2009 through one legacy coalbed methane production well in Russell County, Virginia, USA. The model incorporates a number of individual coal seams about 0.3 m (1ft) in thickness located at depths ranging from 300 to 700 m (1,000 to 2,200 feet). Model calibration was performed through history matching to prior production data, and subsequently the model was utilized to develop different injection scenarios. The developed model was used after injection to calculate CO2 plume distribution patterns that were monitored at the injection test. The paper will present model data and assumptions with a special emphasis on the effect of hydraulic fractures and the skin factor to the coalbed methane (CBM) production model.

Aug 1, 2013