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By W. K. Rankin

Achieving continued economic growth with social equity within the natural limits of the Earth's eco-systems is the major issue facing the world today. The material and energy needs of the world cannot be met with the current ways of addressing this issue. The need for metals, an important class of materials, will continue into the future because their unique properties make substitution by other materials impossible in many applications and this need will continue to be met from primary metal production and recycling. However, the recycling rate will increase and the usage pattern of metals will change to reflect the environmental impact of their production and use. Pyrometallurgy has an important role in meeting the metal needs of the future since some metals can only be produced pyrometallurgically; the energy required to produce some metals pyrometallurgically is significantly less than by other methods; most metals are most efficiently recycled pyrometallurgically; and the release of harmful and toxic elements into the biosphere can sometimes best be controlled through pyrometallurgical processing. The development of strategies for pyrometallurgical processing for the future lies in the recognition that sustainable development calls for large step improvements in value delivered per unit of environmental impact over the entire supply chain. Pyrometallurgists can respond to this challenge by contributing to reducing the environmental impact of meeting metal needs using three broad strategies: "end-of-pipe" approaches to convert emissions into benign materials for storage or disposal; flowsheet redesign to limit or eliminate emission production; and improved recycling technologies. A number of examples are discussed to illustrate how the sustainability driver is already influencing the technological development of pyrometallurgical processes, and how these will develop further as the sustainability driver strengthens.

Jan 1, 2003

By P. N. Anyalebechi

The effects of solidification rate (0.4-26.1 K/s) and alloying elements on the cast microstructures of aluminum alloy 5182 have been investigated with directionally cooled laboratory-size ingots. The alloying elements examined included Mg (3.6-4.7 wt.%), Mn (0.35-0.75 wt.%), Fe (0.11- 0.42 wt.%), Cu (0.03-0.25 wt.%), and Si (0.11-0.28 wt.%). These reflect the chemical compositions of AA 5182 end stocks with high recycled used beverage container (UBC) content. For a given chemical composition, the average dendrite cell and constituent phase particle size decreased with increase in average solidification rate. In general, within the level investigated, Mg did not have a significant effect on the types, volume fractions, and average sizes of the constituent phase particles. However, increase in Mn, Si, Fe, and Cu increased average sizes and volume fractions of the constituent phase particles.

Jan 1, 2010

By A. N. Baldwin

This report documents work performed under Bureau of Mines Contract J0265029 to study and develop two innovative mining systems: ? An underground auger capable of augering into the right and left ribs without repositioning the machine ? A conventional mining system employing recently developed innovative machinery. The report is separated into two volumes to document the two studies separately. Volume I describes work performed and the recommended concept for a bidirectional auger. Volume II describes the studies of mining equipment performance and mining plane developed to determine a conventional mining plan offering improved productivity.

Jan 1, 1977

By L. Alan Weakly

Global warming is a political reality in the United States today. The actual impact of the continued utilization of fossil fuels is not known and is open to debate. However, the growing concern about the continued use of these fuels is problematic. There are technologies available to us today that would permit America to meet its future energy demand and not contribute to global warming. The inconvenient reality is that fossil fuels cannot completely be replaced with energy conservation and the use of wind, solar, hydroelectric, geothermal and nuclear energy. The connection between the greenhouse effect and global climate change was first identified by physicist John Tyndall in the 1860s. To prove the greenhouse hypothesis, Roger Revelle and his research team started measuring carbon dioxide concentrations in the earth?s atmosphere in the early 1960s (Becker, 2007). With the rising concern about global warming, scientists throughout the world have been obtaining surface and air temperature data. Scientists have also been comparing CO2 concentrations found in glaciers throughout the world with theorized annual temperatures. Data for both dates back 1,000 years. Armed with this data, many nations of the world and the United Nations Intergovernmental Panel on Climate Change (IPCC) have concluded that climate change is a reality. The IPCC also concluded that this climate change is the result of mankind?s consumption of fossil fuels and that catastrophic consequences will occur on a

Jan 1, 2008

Newmont?s Twin Creeks Mine, located in northern Nevada, is producing gold ore from surface mining operations. The ore is currently processed at three different on site facilities depending on the ore type and the grade. The processing facilities operate under stringent geochemical blending constraints that must be met from mine ore deliveries and off site sourced ore. To analyze various strategic options, the technical team utilizes the mathematical optimization approach. However, due to the size and the complexity of the operation, there are unique challenges in optimizing life of mine production scheduling. This paper describes those challenges and the methodology developed to take advantage of different scheduling software systems that effectively compensate each other and result in reasonable guidance. The paper also describes how those scheduling results are reflected in detailed mine plan and cost estimate work.

Feb 27, 2013

ANNUAL meeting of the Woman's Auxiliary of the American Institute of Mining and Metal-lurgical Engineers convened on Tuesday morn-ing, Feb. 20, the president, Mrs. H. W. Hardinge, presiding. President Hardinge, in opening the meet-ing, said: "I have the honor and great pleasure to welcome you to our seventh annual meeting. It has been a happy year, though I started in fear and trembling. My fear is partly gone and my trembling becomes less as time goes on. Never has a chairman had such splendid cooperation and harmony in her work; no. matter how much was asked nor what the task, I have always received the same answer, `We are with you, of course we can do it.' Often the road has been untried and the way full of snares, but we have all pulled together. Is it any wonder we have had a prosperous year? I cannot thank the governing -board and officers enough for their help." Mrs. Hardinge described her trip through the West last summer, during which she visited many of the local sections of the Auxiliary. She also spoke of the work of the Rossiter Raymond memorial library which has been started as an activity of the Woman's Auxiliary. Mrs. Reynders read the minutes of the last annual meeting, and Mrs. Kemp read the treasurer's report. The latter showed that on Feb. 1, 1922, there was a bank balance of $683.61 and on Feb. 10, 1923, the bal-ance was $947.93. Mrs. Westervelt expressed the sorrow of the Auxiliary for the death -of Mrs. Florence Howe Hall and of Mrs. Levi P. Holbrook.

Jan 4, 1923

By B. W. Prof. Frazier

I PROPOSE in this paper to treat of the chimney merely as a heat engine, as one of the devices resorted to in practice for the conversion of heat into mechanical work. For the sake of simplicity and clearness in the discussion, let us consider the subject in its simplest form. Conceive a chamber, heated from without, in free communicatioH at one end with the external atmosphere, and at the other end opening into a vertical chimney. Let the. cross-section of the chamber be so great, relatively to that of the chimney, that we can neglect the actual energy of the air passing through the chamber. We will neglect, also, all passive resistances to the passage of the air. We will assume that the cross-section of the chimney is constant, and that the air in passing through it neither gains nor loses heat. The following symbols will be employed in the discussion : Po = the normal pressure of the atmosphere, which, it is assumed, is the pressure existing at the level of the chamber. Po = 10332.96 kilograms per square meter. P2 = the pressure of the external atmosphere at the top of the chimney. To = the, absolute temperature of melting ice by the centigrade scale. This is assumed to be the temperature of the external air at the level of the chamber. To = 273°. T2 =the absolute temperature of the air as it passes from the chamber to the chimney. T3 =the absolute temperature of the air as it issues from the chimney. to, t2, t3 are the temperatures, as recorded on the centigrade ther¬mometer, corresponding to the absolute temperatures To, T2, T3 re-spectively to = 0° C. In general, t = T- 273. Io, I2, I3, represent the intrinsic energy of the air at the temperatures To, T2, T3 respectively.

Jan 1, 1882

By Gae On Kim, Ki Baik Kim, Suk Hoon Kang, Tae Kyu Kim, Sanghoon Noh

"Advanced radiation resistant oxide dispersion strengthened steel (ARROS) is being developed as a fuel cladding tube material for future nuclear reactor system applications. The research activities consist of advanced radiation resistant ODS steel development and fabrication technology development of ODS steel structural components. One candidate material with a chemical composition of (in wt%) Fe-10Cr-1Mo-0.5Mn-0.1V-0.25Ti-0.35Y2O3and was selected as representative materials, and this material was named as the advanced radiation resistant ODS steel (ARROSTM).On the basis of this ODS steel composition, an optimized fabrication process of structural components such as plates, sheets and tubes has been established through various process conditions in mechanical alloying, hot/cold working, and heat treatment processes. These R&D activities are expected to contribute to the realization of ODS materials in the future.INTRODUCTIONA sodium-cooled fast reactor (SFR) is being developed at the Korea Atomic Energy Research Institute (KAERI) with a view to economics, safety, reliability, and sustainability. The prototype Gen-IV SFR with a capacity of 150 MWe is under design, and this prototype reactor is scheduled to operate from 2028. For a commercial SFR system application, it is necessary to develop an advanced structural material having both high creep strength and irradiation resistance at high temperatures (Jeong, 2014). Oxide dispersion strengthened (ODS)steel is one of the most promising structural materials because of its excellent creep and irradiation resistance on the basis of uniformly distributed nano-oxide particles with a high density, which is extremely stable at high temperatures under a neutron irradiation environment for a prolonged operating period(Kim, 2016). As the first step, several batches of ODS steel were designed and the candidate samples with a 2 kg scale each were fabricated by mechanical alloying, hot isostatic pressing and hot rolling processes. The mechanical properties of these samples were evaluated. Up to now, two candidate materials with chemical compositions of (in wt%) Fe-10Cr-1Mo-0.5Mn-0.1V-0.25Ti-0.35Y2O3 was selected as representative materials, and these materials were named as the advanced radiation resistant ODS steel (ARROSTM).The next step was to optimize the fabrication process of the ARROS compositions for in-core structural components such as the fuel cladding tubes of a SFR. An optimized fabrication process of fuel cladding tube with a composition of ARROS has been established through various process conditions in mechanical alloying, hot consolidation, hot/cold working and heat treatment processes. Joining technologies of the ODS steel tubes is being developed using solid-state welding such as magnetic pulse welding, friction stir welding and diffusion boding. It is expected that the development of ARROS will contribute to the realization of a commercial SFR with high economics and sufficient safety in the future. In this paper, the study of fabrication process of ARROS structural components is introduced."

Jan 1, 2017

By Alexander Blatt, Franz-Werner Gerressen

Power Point Presetation at DFI 2022

Sep 1, 2022

Massive sulfides discovered in 1991 and further explored in 1993 in the eastern Manus back-arc basin, north of Papua New Guinea, represent one of the few modem seafloor occurrences known to he associated solely with highly siliceous volcanic rocks. As such they are very close analogs of ancient volcanogenic massive sulfide (VMS) ore deposits, and hence an excellent natural laboratory for developing new approaches for land-based VMS exploration. The Manus Basin lies between the active New Britain subduction zone and volcanic arc to its south and the opposed inactive Manus subduction trench to its north. It is being extended in a complex pattern of short neovolcanic zones and oblique transform faults. In its western sector, relatively mature back-arc spreading has created predominantly basaltic segments with characteristics and mineralization generally similar to those of mid- ocean ridges. At its far east, however, the basin is distinctly immature. The East Manus Volcanic Zone lies between two members of the Manus transform set, and is an en-echelon series of neovolcanic edifices constructed on extensionally thinned island arc crust formed during the earlier manus subduction episode. Individual edifices range from predominantly basaltic to predominantly dacitic in composition. Two of the edifices are known to be hydrothermally active, and a particulate plume with unknown source occurs in the seawater column above a third.

Jan 1, 1993

By Fred H. Perfect

The thermite process, now approximately 80 years old, has heretofore been practiced in ceramic vessels. This paper outlines the successful production of several million pounds of alloy produced in zuater-cooled copper vessels. THE high temperatures necessary to produce fluid high-alumina slags have probably discouraged earlier workers from attempting to utilize water-cooled vessels. The following is a report of the successful application of this method, together with a report of the physical and chemical problems which had to be solved to make the process practical. About 1955, when Reading Alloys was more concerned with the production of ferrotungsten than with most other types of alloys, it was found to be exceedingly difficult to predict the reaction rate that one would experience from one tungsten ore to another . This difficulty was increased for two reasons: the physical state of the ore as received was seldom uniform, and the size of the mass to be reduced is a very important factor in developing the proper mix for the final reaction rate and temperature. For example, the reduction of ferric oxide with aluminum would theoretically produce temperatures of about 2600°C, and, in spite of the losses due to radiation, the energy is quite sufficient to produce a very fluid slag and iron effecting a very clean separation. On the other hand, the reduction of ferrous oxide with aluminum, while it is not as energetic as the first reaction, nevertheless should give temperatures above 2000"C, which should cause separation of alumina and iron, but, in practice, this is not the case and good fluid slag is not obtained. The heat of reaction, calculated from the thermo-dynamic heats of formation of the constituents of the reaction, offers a convenient guide to the feasibility of a thermite reaction. Thus, the values listed in Table I can be used as an approximate guide for estimating the results which may be expected in the reduction of various oxides and combinations of oxides using aluminum as the reducing agent. As a generalization, those reactions releasing approximately 600 cal per g of total mass represent the lower limit at which to expect separation of slag and metal. On the other hand, those reactions which release 1100 to 1200 cal per g are too violent to be used successfully without the addition of considerable inert material, such as lime, fluorspar, and so forth. Reaction rate is also a very important factor. This, of course, is governed very largely by the sizing and intermingling of the oxidant and reductant and by the starting temperature of the reactants. This is why those figures shown in Table I can only be a general guide. Further, it must be understood, that by adding powerful oxidizing agents, such as nitrates, chlorates or metallic oxides, such as molybdenum trioxide or chromium trioxide, certain problems respecting low temperatures are not necessarily solved. This is true in the addition of oxidants, such as sodium chlorate. By adding too high a concentration of sodium chlorate as a booster for a particular reduction, explosions are generated. Generally, they are of an intermittent type so as to give a Roman Candle effect to the reduction itself; with each surge resulting from a minor explosion more and more material is thrown

Jan 1, 1968

By J. M. Beck

Mineral property appraisers engaged in eminent domain actions on properties for which mining is the highest and best use must be fully competent in all phases of mineral resource estimation, mine project development, and mine operations (or retain the requisite competent assistance), as well as educated in eminent domain appraisal (USPAP Competency Rule). Failure to ensure such triggers the issue of appraisal competence and demonstrates a flagrant disregard of the myriad code(s) and guidelines to which the appraiser is subject. The cavalier assertion of some vague, undefined “latitude” in the valuation process does not exonerate the appraiser from a disregard of the USPAP Competency Rule. Lack of independence (i.e., “advocacy”) in mineral property appraisal is the usual result of a weak background in mining and/or appraisal theory. While it is readily apparent to those able to recognize it in reports and testimony, judges and juries cannot be expected to detect or recognize purposefully misleading (or even fraudulent) valuation concepts or testimony. Purposeful deception by the appraiser can lead to specious over-compensation of the property owner (thus victimizing the taxpayer); or, a failure to provide appropriate and just compensation to the property owner – yet, the purpose of an eminent domain proceeding is to leave the property owner no richer or poorer as a result of the taking. This paper highlights some of the deceptive practices encountered in litigation settings and raises issues of competency, professional ethics, and the effectiveness of the inherent enforcement capabilities within those institutions awarding professional certifications. INTRODUCTION The practice of eminent domain mineral property appraisal requires (particularly with respect to undeveloped mineral properties) that the appraiser possess the requisite level of competence in all phases of mineral resource estimation, mine project evaluation, mine development, and mine operation (through closure). To the extent the appraiser lacks such competence, it is incumbent on the appraiser not only to divulge this lack of expertise but also to seek competent assistance in the performance of the appraisal. This competence or expertise can only be obtained through a combination of appropriate and relevant technical education and direct mining industry experience. There exist a number of professional certification and/or credentialing authorities that speak to such competency. In a similar manner, eminent domain mineral property appraisal (as the term implies) also requires that the appraiser possess the requisite level of competence in the practice of eminent domain appraisal. This competence or expertise can only be obtained through appropriate and relevant education, direct knowledge of appraisal theory, particularly as it relates to the concept of eminent domain, and licensure.

Jan 1, 2019

By Y. Sasseville

"Niobec has been using vibrating screens and screw classifiers as a double stage classification in its grinding circuit since the very beginning of its operation in St-Honoré. Most of the other mineral processing plants around the world uses cyclones as the classification device in their grinding circuit. The difference between these two methods are well known in terms of capital cost and grinding efficiency but the differences in terms of the impact on the downstream processing stages are a lot harder to predict and are case specific. In the interest of lowering the capital cost of a future expansion project, Niobec decided to test the cyclones in its actual grinding circuit and evaluate their impact on the recovery of the downstream processing stages as well as the operating cost of the mill. We switched between cyclones and screens for 8 month in 2013 and early 2014 and we are now operating only with cyclones since march 2014.INTRODUCTIONThe Niobec mine and concentrator were built in the mid 70’s and at that time, the mill was processing 1 500 tons per day. Over the years, many expansion projects have brought the plant to 7 000 tons per day. Throughout the initial concentrator design and commissioning, screens have been chosen over cyclones because of their higher classification efficiency which is known to reduce variability and limit the fine generation especially due to a high undersize classification efficiency. Just like many other plants, fine particle generation is a major problem at Niobec because of its negative effect on downstream processing stages. In the interest of lowering the capital cost of a future expansion project, Niobec’s engineering team decided, 35 years later, to test the cyclones in its actual grinding circuit and evaluate their actual impact on the final recovery and the operating cost of the mill.The grinding circuit is separated in two lines which will be called Circuit #1 and Circuit #2 along this paper. Circuit #1 is, as you can see in Figure 1, composed of a rod mill and two parallel ball mills in closed circuit with screens and screw classifiers. The screens oversize are sent to the screw classifiers while the undersize are sent to the next processing stage. The screw classifiers overflow are both sent back to the pump box while their oversize streams return in their corresponding ball mills for further grinding. Circuit #2 is, as you can see in Figure 1, quite the same as Circuit #1 except it has only one set of screw classifier and ball mill. Figure 1 also shows the modification in arrangement each circuits went through to integrate the new cyclones. One of the ball mills in Circuit #1 now appears dotted because it can still be used but is not now"

Jan 1, 2015

By Sanjeeva Latchireddi

"Deteriorating ore grade and high demand of metals has tremendously influenced the unit capacity of SAG mills. Pebble circuits have been added to the existing SAG circuits to increase their unit capacity. To make the pebble circuits justifiable, the grate openings are increased almost to 4.5 inches to draw large quantity of pebbles. The inherent transportation problems associated with SAG mills in closed circuit with pebble fraction are more complicated than the single stage SAG mill operation, because the coarse pebbles behave significantly different to that of slurry in pulp lifters. In addition, operation of mills at higher speed, to take advantage of precise design of high release angled shell lifters significantly reduces the discharge efficiency of the conventional pulp dischargers. The presence of a sizable quantity of pebbles in the pulp lifter limits the space available and reduces the flow gradient through the grate thus increases the load inside the mill and hence the mill power-draw. This paper analyses all the problems associated in discharge of slurry and pebbles in SAG mills with pebble circuits. The Outokumpu patented Turbo Pulp Lifter (TPLTM) aims at eliminating the inherent material transport problems to ensure good grinding conditions. Recent installation of TPLTM in a 26-ft SAG mill has proven these claims by reducing the specific power consumption while increasing the mill capacity.INTRODUCTIONThe conventional wisdom is to look at the semi-autogenous grinding (SAG) mill as just another grinding mill in which ball charge, mill filling, and mill speed are varied to attain maximum throughput. Liner design for the SAG was also approached more from a wear perspective rather than a metallurgical and hydraulic-flow perspective. The extensive research work carried out by Latchireddi and Morrell (1997,2003a and 2003b) has demonstrated to think of the SAG as more of a pump in which the grates and pulp discharger end (“impeller”) were designed to efficiently discharge the product sized particles smaller than the grate size with minimal recirculation out of the mill.The rock load in the mill is essentially depends on ore characteristics and the discharge rate of broken particles. The discharge rate of the product material depends on how efficiently the discharge pump (grate and pulp lifters) is operating. Similar to the impeller design affecting the pump capacity, the pulp lifter design affects the discharge capacity (or mill throughput) of the SAG/AG grinding mills. The general arrangement of AG/SAG mills discharge system is shown in Figure 1."

Jan 1, 2007

By Jean Dugas, Roger Sirois

The Mineral Deposits Service of the Quebec Department of Natural Resources is engaged in the preparation of metallogenic maps as a contribution to the Canadian Sub-Committee of the Metallogenic Map of North America. The preliminary work is being done on large-scale maps. The main objective is to clearly represent information on ore deposits in a suggestive way. The design of the legend to meet these requirements is discussed. As these maps are still only descriptive, a further step will be the interpretation of data into metallogenic maps with Jess emphasis on the individual deposits and more on the metallogenic factors. Both types of map should prove useful in the search for ore deposits; the first by providing at once a large amount of information, the second by suggesting the ore controls.

Jan 1, 1967

By W. S. Dyer

Introduction In northern Ontario, refractory clay is found on four rivers of the James Bay watershed: the Abitibi, the Mattagami, the Missinaibi, and the Moose. The clay all belongs to the same geological formation ( the Mattagami of Lower Cretaceous age) , and occurs within a structural depression or 'basin', the boundaries of which have never been defined but which appears to cover at least 1,500 square miles of territory. The recently constructed James Bay extension of the Temiskaming and Northern Ontario railway crosses the northeast end of the basin at the Onakawana lignite field, which by rail is 126 miles north of Cochrane, 605 miles north of Toronto, and 60 miles southwest of Moose Factory. Smoky Falls, the northern terminus of the railway owned by the Spruce Falls Power & Paper Company, Limited, is 7 miles south of one other point in the basin, i.e., the outcrops of refractory clay, sand, and kaolin at the foot of Long rapids on the Mattagami river. Smoky Falls is 50 miles north of Kapuskasing. In a very early report(l) , Dr. Robert Bell, of the Geological Survey of Canada, described '"light coloured marl in horizontal beds" from the Missinaibi river, and noted that the lignite also occurring in the river was probably :associated with the marls. This was undoubtedly the Cretaceous refractory day. Other early writers noted the occurrence of fire-clays, but it was not until Joseph Keele(2), of the Geological Survey, visited thee region in 1919 and studied the clays that their real significance was known.

Jan 1, 1933

By Rita D. Sylvester

"THE BUREAU OF MINES was established in the public interest to conduct inquiries and scientific and technologic investigations concerning mining and the preparation, treatment, and utilization of mineral substances; to promote health and safety in the mineral industries; to conserve mineral resources and prevent their waste; to further economic development; to increase efficiency in the mining, metallurgical, quarrying, and other mineral industries; and to inquire into the economic conditions affecting these industries. The organic act of the Bureau, as amended by Congress and approved February 25, 1913, made it the province and duty of the Bureau to ""disseminate information concerning these subjects in such manner as will best carry out the purposes of this Act.""In accordance with that directive, the Bureau reports the findings of its research and investigations in its own series of publications and also in articles that appear in scientific, technical, and trade journals; in proceedings of conventions and seminars; in reference books; and in other non-Bureau sources. The number of these reports, the wide range of subjects they cover, and the variety of mediums in which they appear make the kind of list and index presented III this special publication both necessary and valuable. This issue describes Bureau reports and articles published during the period January 1, 1960 to December 31, 1964. It supplements the 50-year list of Bureau publications issued from July 1, 1910, to January 1, 1960,2 and the 50-year list of articles by Bureau authors published outside the Bureau from July 1, 1910, to January 1, 1960.3 It supersedes the annual lists of Bureau publications and articles from January 1 to December 31, 1960/ from January 1 to December 31, 1961,5 from January 1 to December 31, 1962,6 and from January 1 to December 31, 1963,1 The leading general and technical libraries of the United States maintain files of the Bureau's publications. A list of these libraries appears immediately following this introduction. BUREAU PUBLICATIONSBecause some series of Bureau reports contain both free and sales publications, and because the cost of sales publications varies, prices are indicated in the individual listings of all publications for which charges are made."

Jan 1, 1964

By Erle C. Donaldson

Subsurface injection of liquid and slurry-type industrial waste is being used as a means of waste disposal. This survey conducted by the Bureau of Mines shows that the method can be economically and environmentally attractive if the proper precautions are taken, especially when the alternative is cursory treatment and discharge at the surface. Attention is called to petroleum technology and experience that can be applied to subsurface waste injection. Part 1 of this report is a discussion of the general aspects of subsurface waste-injection systems. Part 2 is a general discussion and review of the literature concerning the geologic formations available for injection in the United States. Part 3 is a discussion if 15 case histories including information on the source and nature of the waste and the geology, surface equipment, well completion, and operation of the systems.

Jan 1, 1974

By Sergio N. Monteiro

Polymeric matrix composites reinforced with coir fibers are being used in many industrial applications such as automobile interior panels and cushions. These composites have relatively low mechanical strength due to the weak fiber/matrix interface. The objective of the present work was to investigate the effect of a surface alkali treatment of the curaua fiber on the mechanical behavior of polyester composites with different amounts of these fibers. The treatment, also known as mercerization, was performed with distinct concentrations, 0.1 and 10% of NaOH at 1 min and 1 hour, before incorporation of the coir fibers into the polyester composite. The results showed no significant change in comparison to similar untreated coir fiber composites. A microstructure analysis revealed that, in addition to reducing the hydrophilic characteristic of the fiber,the treatment also affects the surface morphology and impairs the fiber/matrix interfacial strength.

Jan 1, 2009

By Wade Edward Speer

The Hiddenite District of Alexander County, NC has produced some of the world?s finest large emeralds since the first one was discovered 134 years ago. In fact, North America?s largest emeralds come from the district, making this one of the continent?s most unique gem deposits. In addition to emeralds, the Hiddenite District is also famous as the discovery site for the rare spodumene mineral hiddenite, first identified in 1881. Nowhere else in the world do these two minerals naturally occur together. The emeralds are a unique color variety of beryl (Al2Be3Si6O18) with trace amounts of Cr+3 and V+3 substituting for Al+3. The hiddenite (LiAlSi2O6) crystals also exhibit emerald green color due to traces of chromium. Consisting of three large deposits and numerous prospects, the district encompasses an area of 10 km2 (4 sq miles) centered on the small town of Hiddenite. Operations at the Adams, Ellis and North American Emerald Mines properties have been productive at irregular intervals since the 1880s. Currently, only the North American Emerald Mines property is being mined on a regular basis. Recent activity there has exposed a 3-hm2 (7.4-acre) pit with depths of 25 m (82 ft) that provides the best exposures of unweathered bedrock seen in the district in more than 120 years. Although no official records exist, public and private data indicate that the production of the entire Hiddenite District from 1880 to 2007 is about 70,000 carats of emerald and 20,000 carats of hiddenite. The bulk of the emeralds came from the North American Emerald Mine property (NAEM, formerly known as the Rist Mine) where sustained mining replaced the previous sporadic prospecting in 2000.

Jan 1, 2009