Search Documents

By Wm. R. Webster

THIS is a contribution for the proposed new discussion on the physics of steel. The former discussion on the subject started with the consideration of five papers presented at the Chicago meeting in 1893, and continued for several years. The Suggested Lines of Discussion, prepared by Doctor Howe, covered a wide field and added greatly to the success of the work. Naturally, the first step in a new discussion will be to remodel and bring up to date the old Suggested Lines of Discussion so as to embody all the important advances in the metallurgy of steel that have a bearing on the physics of steel and keep the papers and discussions within the field of work undertaken. This paper will be devoted to the practical application, in rolling steel, of the effects of carbon, phosphorus, and manganese on its tensile strength, with some suggestions on further research work. Dr. J. E. Stead, in his paper Influence of Some Elements on the Mechanical Properties of Steel,1 gave a complete review of all that had been done during the past thirty years. He gave full credit to all investigators who worked on these lines, also their results, with his views on same, and in many cases his own results. All of this data and much new valuable information were put in convenient shape for reference and study. To do this required a great deal of work, which is fully appreciated by the steel manufacturers and investigators. The variations in the values given by the different investigators for the increase of the tensile strength of steel for each 0.01 per cent. of carbon, phosphorus, and manganese were largely due to the steels they worked on, the large or small variations in the amount of the elements present, and the omission to take into consideration all the factors, from the blast furnace through to finished rolled material, that affect the character of the steel. For instance, a poorly made dirty steel requires considerably more carbon to give the same ultimate strength than a well-made clean steel with the same phosphorus and manganese content.

Jan 3, 1921

By F. E. Griffith, C. H. SEELING

Cardox blasting is used widely in coal mines in the United States . A model of a Cardox blasting device was approved by the Bureau of Mines subject to certain conditions and limitations , and the approval was extended to other models from time to time . Certain special hazards are entailed in the use of Cardox as with explosives . One of these is flying shells . In some blasts , the Cardox shell is violently ejected from the borehole and flies like a projectile , frequently ricocheting off solid objects and striking points considerably off the line of its initial flight . Flying shells have been known to pierce the webs of structural - steel beams , to pass through both sides of allsteel mine cars , to be driven through stout hardwood timbers , to knock out timber sets , to damage loading equipment , and to break or short - circuit power lines . A considerable number of shot - firers and other workers have been struck by flying shells and killed or injured . Accidents from this cause , although not as frequent as other types of mine accidents , are usually serious , closely approximating accidents caused by blasting with ordinary explosives . The increasing number of such accidents prompted a Bureau of Mines field investigation of possible methods of preventing dangerously violent ejections of Cardox devices . This report contains pertinent data collected during the investigation and describes methods tested and discarded as well as the development and proof of an apparently satisfactory method .

Jun 1, 1943

By S. K. Kawatra, S. J. Ripke, T. C. Eisele

"An estimated 600,000 tons of bentonite clay are used annually in the U. S. as binder for production of iron ore concentrate pellets. Since this is a significant cost item for the plants, and the addition of bentonite to the pellets contributes undesirable silica into the finished pellets, there is considerable incentive for finding methods to reduce bentonite use. One way to reduce bentonite levels is to selectively use those bentonites that are most effective in this application, so that a lower dosage will still produce a sufficiently strong pellet. Unfortunately, there are no satisfactory methods available for accurately predicting which bentonites are actually most effective, short of using them to actually make pellets. One of the popular methods for attempting to evaluate bentonites is the “Plate Water Absorption” (PWA) test. While some plant operators accept the PWA results as indicating the relative quality of bentonites, others disagree and claim that, over a fairly broad range of values, PWA does not correlate with bentonite performance.Since both Ca+2 and Mg+2 ions are known to reduce the swelling and water absorption capacity of bentonite, it was believed that the presence of these ions in plant recycle water could be changing the bentonite performance. Since the standard PWA test uses only distilled water for its measurements, it could not detect these effects. Experiments were therefore carried out on a number of different bentonites using a modified PWA tests, with plant recycle water replacing the distilled water. These experiments showed little effect of the plant water on the PWA value, and chemical analysis of the water showed that the levels of dissolved salts were quite low.Water and accompanying salts were then extracted from a magnetite concentrate filter cake by rinsing with distilled water. Analysis of this water showed an extremely high level of dissolved salts, particularly salts of calcium and magnesium. When concentrations were compared with the recycle water from the plant filters, it was determined that levels of Ca+2 and Mg+2 retained in the filter cake were over 500 times higher than levels in the recycle water. This extreme elevation of soluble salts in the filter cake is believed to be due to adsorption of these ions into the electrical double layer of the magnetite particles."

Jan 1, 2003

By Leticia dos Santos Aguilera

Nanopartículas magnéticas são amplamente empregadas em diversas áreas devido as suas propriedades superparamagnéticas, e vem sendo estudadas por todo o mundo com potencial em campos como biomedicina e tratamento de efluentes. Nesse experimento as propriedades de ferritas mistas de manganês e zinco foram testadas e avaliadas com base na sua concentração de zinco em cada composto, usando como fator de comparação suas velocidades médias de arraste em um tanque de ondas graduado na presença de um campo magnético externo. O processo procura viabilizar um método de análise que sugira possível coerência com resultados observados em outro método de caracterização magnética, a magnetometria por amostra vibrante. Tais resultados apresentaram maior magnetização de saturação para as amostras de Mn0,5Zn0,5Fe2O4 assim como foi observado maior velocidade de arraste nas amostras de mesma estequiometria.

Oct 30, 2017

By Malcolm J. Robinson

Over 80% of Australia's population lives within 200 km of the coast, 70% in 10 major coastal cities. Potential cement raw materials are widely distributed but deposit size, quality, transport, market and environmental considerations are important in determining economic value. Major production locations are in a variety of geological environments ranging from Lower Paleozoic crystalline limestones to Tertiary and Recent polyzoal limestones and limesands, both onshore and offshore. Raw material transportation is by road, rail, sea, aerial ropeway and pipeline; road/rail transportation of the finished product is traditional but movement by sea of clinker and cement is increasingly a feature of the industry.

Jan 1, 1982

By Justus B. Deen, Randy Peterson

INTRODUCTION The General Chemical Soda Ash Operation located near Green River, Wyoming produces about 4.5 Mt of trona per year. In July 1989, Mine Ventilation Services Inc. performed a ventilation survey of this complex trona mine which had thirteen active panels spread over 36 square kilometers. The ventilation survey and subsequent study showed that the intake shaft air velocities were at their practical limits (Wallace and Rogers, 1987). The need for additional intake capacity was immediate. The ventilation network modeling delineated the best location for this new intake shaft as it applied to the 5 year ventilation plan. Unfortunately, this location, 6.5 kilometers from the soda ash processing plant, would make heating this intake air very costly. Presently, the intake air is heated by heat exchangers which use waste heat from the plant. Air heating during the winter months is necessary for miner comfort and to prevent potential freezing of water lines in the mine. It was decided to examine the feasibility of heating the air geothermally by coursing it through an old production panel. This method of air heating has been used in this region with good results at the Stauffer Chemical Operation (now Rhone-Poulenc) (Moore, 1985). In 1990, a geothermal heating study examined four different production shaft/panel configurations and a workable design was found. The operators at the General Chemical Soda Ash Operations acted on this design and began raise boring a ventilation shaft in the Spring of 1991. This paper describes the ventilation system, briefly, and the geothermal heating studies performed. Findings of the 1990 geothermal studies are then compared to field data acquired in the Winter of 1992. THE VENTILATION SYSTEM The ventilation system at General Chemical had four shafts serving the mining horizon in July 1989; three of these shafts are located at the Northwest end of the mine. The active work areas had progressed to the South over the past years and supplying ventilation has become increasingly difficult. The 6.1 meter diameter #3 Production shaft and the men and materials compartment of the 6.1 meter diameter #2 Split Shaft had reached their air velocity limits. Conversely, the 4.6 meter diameter #5 Exhaust Shaft was under utilized. Ventilation studies showed the conversion of the 3.7 meter diameter #1 Exhaust Shaft to an intake would provide adequate intake capacity for two years. The next option to improve ventilation was the addition of an intake shaft at the southeast part of the mine at the intersection of H Mains South(H-M-S)and J Mains East(J-M-E) (See Figure 1). A service shaft has been planned for the extreme Southeast end in the late 1990's. Ventilation network analyses showed this interim intake shaft would have to be at least 2.5 meters in diameter to postpone the service shaft construction beyond 1995. The greater the size of the borehole, the further the construction could be postponed. In October 1991, General Chemical commissioned the 4.57 meter diameter #4 Ventilation Shaft near the junction of H-M-S and J-M-E as shown in Figure 1. The L95 panel would be used for air heating as described in the geothermal heating section to follow. GEOTHERMAL STUDIES Geothermal heating studies were performed by MVS Inc. in May 1990. Using a modified code of CLIMSIM, an underground mine climatic simulation model, several different shaft/panel configurations were examined to see which would provide adequate air heating during the winter months. CLIMSIM simulates heat flow into a single underground airway. The program was used to evaluate the heat flow to and from the airway surface and to calculate the resulting change in dry bulb temperature of the ventilating air. CLIMSIM uses inlet air conditions, airway characteristics, and rock thermal properties input by the user to predict the variation of psychrometric and thermodynamic parameters along an underground airway.

Jan 1, 1993

By Akira Yoshida

Este trabalho apresenta o sistema de Nível 2 recentemente implementado nos Altos Fornos da TKCSA cujos principais objetivos foram: substituir o sistema antigo com problemas de instabilidade e falta de flexibilidade; auxiliar Operação e especialistas da Unidade Técnica fornecendo informações elaboradas a partir de dados obtidos nos demais sistemas (Nível 1 e Laboratório); enviar set-point ao Nível 1; enviar dados de consumo e produção ao sistema MES; etc. Com a implementação foi possível reduzir o tempo gasto pelos especialistas nas atividades de compilação de dados em planilhas, padronizar a forma de tratamento dos dados, bem como, elevar a confiabilidade das informações pela eliminação de erro de digitação. O sistema tem operado com elevada estabilidade e disponibilidade, atendendo perfeitamente o que foi proposto, de modo que a TKCSA planeja estender para demais plantas da área de Redução.

Aug 16, 2017

By Ravi Sahu

"In the global mining industry, there are those who seem resigned to the fact that the mining industry has always operated according to certain time-tested principles that don’t involve jumping on every new technological trend. Others expect that mines will soon have autonomous electric vehicles running around the clock. The truth lies somewhere in the middle. In business, as in life, that is usually the best path to follow.The instant access to people and information provided by 21st-century technology continues to push businesses in all industries toward greater efficiency and unheard-of levels of modernization. And in the world of mining, the embrace of advanced technology is all about managing risk.However, even in this age of digital information overload, some mine sites still require employees to physically download data from individual trucks to monitor payload data and inspect road conditions using a clipboard. What’s more baffling is that other mine sites still have no way of tracking tons moved at all.This isn’t due to a lack of innovation in the industry. Quite to the contrary, there is an abundance of new technology available that provides real-time monitoring of vehicle movements and tracks road conditions without the intervention of people. So why are owners reluctant to embrace advances in mining tech?Gauging the value of changeSurvey data has traditionally been captured by ground laser scans and LIDAR systems. A mine site surveyor would drive around the pit with a truck-mounted scanner to generate a point cloud. This process would be completed every few days and would take an entire day.The many cons of this method far outweigh the pros. First, it provides no visual data. If an operation has moved beyond the roller wheel and tape measure, visual pit models and LIDAR scans are typically completed once every six to 12 months by an aerial flyover, but such sporadic information gathering isn’t likely to result in the most actionable data. Moreover, given the high cost (in terms of both money and time), the numerous safety and liability issues, and the lack of flexibility in scheduling, manual processes are more trouble than they are worth.Overall, while miners are excellent operators who value innovation, their employers often try to outsource it or acquire innovators instead of investing in existing technology that can improve current operations. It is a never-ending dilemma:"

Jan 5, 2018

By Elena L. Chanturiya, Vladimir A. Bocharov, Roman A. Amosov

"In many volcanogenic base metal deposits of Russia the gold is closely associated with copper sulphides and pyrite. The recovery of gold associated with pyrite is especially difficult problem.Investigations of gold chemical state and mineral forms in copper-zinc sulphide ores of Gay and Barsuchiy Log deposits in the Urals have been made using EPMA, optic image-analysis, XRA, SEM, thermo-electrical force measurements and selective gold leaching experiments.Two gold varieties are determined: 1) free native gold particles (from 5 µm up to 0,25-1,0 mm), which can be liberated after grinding of ore up to 0,074 µm and named “free gold”; 2)”invisible” gold, including finely disseminated native gold and chemically bound gold. The second variety can’t be disclosed during grinding. Free gold can be recovered by gravitation and flotation while the processing behaviour of “invisible” gold is determined by properties of gold-bearing sulphides: pyrite and chalcopyrite. According to results of diagnostic leaching experiments in ores of deposits mentioned above the part by weight of free gold reaches 70%, the part by weight of the ”invisible” gold is up to 20%. About 10% of gold is enclosed in quartz and acid-soluble minerals.Theoretically (taking into account gold distribution data) it’s may anticipate gold recovery by gravitation up to 60%. However after grinding up to 50-60% of class –0,074 mm only about 40% of gold passes into oversize product including 30% of free gold and 8% of ”invisible” one. It can be recovered by gravitation. Remaining free gold and ”invisible” gold can be extracted by flotation – 25% in total. Inevitable gold losses in tailings may reach 8-10%."

Jan 1, 2003

Iron Concentrate Synthesised from Waste Ferrous Sulfate Produced in Titanium White Preparation

Sep 13, 2010

By Martin D. Conyac

A mineral resource survey of rock types and geologic structures indicates that the Mt. Henry RARE II area has low potential for the discovery of metallic minerals. Potential for coal and geothermal resources is negligible. Essentially, the Mt. Henry RARE II area has had no claim-staking activity, nor has any mine been developed in it. SETTING Size and Location The 23,000-acre (9,308 ha) "1t. Henry RARE II area (No. 1-666) lies within the Kootenai National Forest approximately 36 mi (58 km) north of Libby, Montana, in the Purcell Mountain; of Lincoln County. Irregularly shaped, the area measures roughly 5-1/2 mi (8.9 km) north-south by 8 mi (12.9 km) Past-west, and lies about 1-1/2 mi (7.2 km) south of the Canadian border.

Jan 1, 1982

By H. Matlock

Beam-columns with continuous or discontinuous transverse and angular loads and elastic restraints are represented mathematically in a manner corresponding to finite-element mechanical models. Solutions for linearly elastic cases are accomplished by direct recursion-equation elimination of unknowns, and for cases involving nonlinear loads and supports, by repeated trial-and-adjustment of complete elastic-type solutions. Five practical applications are presented by which various capabilities of the general method are illustrated. The examples include simulation of a pipeline launching and the bending and collapse of a conductor pipe in deep-water drilling operations. INTRODUCTION The diversified and complex operations being conducted in support of the production of offshore oil have produced a wide variety of new problems in structural mechanics. Many of these problems cannot be solved by conventional analytical or experimental approaches and have therefore stimulated inquiry into new methods of solution. It is the purpose of this paper to give a brief description of an analytical method for solving nonlinear beam-column problems and to illustrate the generality of the method by applying it to several problems related to offshore operations. Although the data for all of the examples are artificial, the cases discussed will be recognized as being based on actual situations. DESCRIPTION OF METHOD The analytical approach which is to be described stems from research on offshore foundations, in particular, the study of lateral-load behavior of foundation piles. The method represents a generalization of a technique which was suggested by Gleser' and extended by Focht and McClelland2 and Reese and Matlock." To maintain generality and therefore versatility in the method, a considerable variety of input data is considered. Fig. 1 illustrates the various types of loads and restraints which might be applied to a short segment of a beam. Each of the terms illustrated in the figure is shown acting in a positive sense. Capital letters are used to designate concentrated quantities whereas the corresponding lower-case symbols indicate effects which are distributed in some way along the length of the beam. The transverse loads and the elastic restraints may be divided into two classes: (1) loads Q and q and springs S and s, which act normal to the axis of the beam, and (2) couples T and t and rotational springs R and r, which act in an angular sense. In addition, there is an axial force P which may be constant or may vary along the length of the beam. The bending stiffness of the beam (the product EI of the modulus of elasticity and the moment of inertia) is designated by the symbol F. The assumptions of conventional elementary beam theory provide the basis for the present method. Among these are the neglect of shearing and axial deformations and the limiting of consideration to straight beams of symmetrical cross-section. Lateral deflections are considered to be small compared to original dimensions. A deformed element of such a beam is shown in Fig. 2a. The curvature of the beam is approximated by the second derivative of the deflection y with respect to distance x along the beam. It is assumed that the material of the beam is linearly elastic and therefore the relation of Eq. 1 between curvature and bending moment M is the ordinary expression from elementary beam theory. A generalized beam element is shown in Fig. 2b. The element has been deflected in a positive direction by an amount y and tilted through a small positive angle dy/dx. The various loads and elastic restraint reactions are detailed in the figure. Temporarily, only distributed effects are considered; provision for concentrated loads and restraints will be made subsequently. Eq. 2 in Fig. 2b is obtained by summing the forces and moments acting on

Within ten months of the first significant intersection on the Vera deposit, approval was given to proceed with a $28.3 M underground development of the Vera-Nancy gold mine. Contrary to what the timeframe suggests, the development of the underground mine was planned in a logical and methodical manner which enabled confirmation of the resource, evaluation of the orebody for mining and sufficient production to recommence milling operations at the Pajingo treatment plant. This paper describes the underlying factors on which the project was planned and developed. The approach has successfully enabled the mine to be in production 18 months after discovery without compromising any future production or potential expansion

Jan 1, 1998

By J. S. Heath

Many disputes related to environmental issues in mining are resolved through often-antagonistic negotiations in a regulatory context or through litigation. These approaches are certainly the best choices for resolving certain disputes. However, just as no single remediation technology is the right fit for every site, so no single dispute resolution process is the best choice for every situation. This paper introduces a range of dispute resolution alternatives (from collaborative decision making through mediation, arbitration, and litigation). Especially when money is tightest, cost-effective dispute resolution(and the outcomes that can accompany it) can have an impact on the bottom line.

Jan 1, 2000

By George D. Graffin

The first use of graphite is lost in the mists of time. It was used by primitive man to make drawings on the walls of caves and by the Egyptians to decorate pottery. As early as 1400 A.D. graphite crucibles were being made in the Haffnerzell district of Bavaria. Through the Middle Ages graphite was confused with other minerals, especially galena and molybdenite. Two common names that are still used for the mineral are "Plumbago," meaning leadlike, and "Black Lead." The latter name implied that graphite is either composed of lead or at least contains a large percentage of it. Gessner is credited with having recognized it as a separate mineral in 1565, but its composition was not determined until 1779, when Scheele demonstrated that graphite oxidized to carbon dioxide, thus proving its carbon constitution. In 1789, Werner named it "graphite" from the Greek word "graphein," meaning to write. The United States has long relied on foreign countries for its graphite supplies. This reliance has been due more to the lack of suitable domestic graphites than to any particular preference for buying minerals overseas. Ceylon (now Sri Lanka) graphites were imported as early as 1820, and Madagascar graphites have been imported since the properties on that island were opened up about a hundred years later. Mexico has long supplied the United States with most of its requirements for amorphous graphite. Physical Properties and Classification Graphite is found in laminated, flaky aggregates disseminated in schistose rocks. It also occurs in veins and exhibits a foliated or fibrous structure. Graphite is a black lustrous mineral that crystallizes in the hexagonal system, with rhombohedral symmetry. The crystals have tabular form and are six-sided; the faces are commonly striated. The flakes have perfect basal cleavage and are opaque. When well crystallized, the flakes have a black metallic luster while the amorphous material is black and earthy, with a microcrystalline compactness. The flakes feel greasy. Graphite is an excellent conductor of heat and electricity. It melts at approximately 3500°C and sublimes at about 4500°C. It is combustible in the presence of oxygen between 620° and 670°C, but is stable and chemically inert at ordinary temperatures.

Jan 1, 1975

By Ke Yang

Drilled shafts are widely used as foundation system for sound walls to resist lateral loads. The design method based on the ultimate lateral capacity, such as Broms method, is often used for sound wall foundation design. Allowable Stress Design (ASD) is currently used for deep foundation design. However, by October 2007, all states Department of Transportations are required to use the Load Resistance Factor Design (LRFD) approach for the design of foundation in highway projects. There is a need to develop a calibrated resistance factor in LRFD lateral design of drilled shafts supporting sound barrier walls. This paper provides resistance factors for design of laterally loaded drilled shafts supporting sound walls using Broms method based on the study using reliability based method and fitting to ASD method. Additionally, the resistance factors for static lateral load tests are recommended. Furthermore, a methodology to update the resistance factors using Bayesian approach by incorporating the on-site full-scale lateral load test results is presented. To illustrate the Bayesian update methodology, two lateral load tests in Colorado were employed to develop the updated resistance factors.

Jan 1, 2007

Why Innovate in Mining? ?Obvious, right? ?Increase productivity and profitability ?Improve safety and ergonomics ?Improve our environmental record and eliminate liabilities ?Implement process control methodology ?Introduce information systems technology to gain control ?Low hanging fruit ?Reference ?Heather Ednie, Innovation CIM Magazine Feb. 2006 ?Peck & Skinner, Getting better bang for your buck with technology

May 1, 2006

By J. Gordon Parr, D. H. Polonis

IN a previous study of hypereutectoid Ti-Ni alloys' a substructure was observed in quenched powder specimens when the constitution was 100 pet retained ß body-centered-cubic phase. The alloy powders were quenched from 1000°C by a blast of helium gas and precautions already described were observed throughout the work, to minimize contamination. Ogden et al.2 have previously observed subboundaries in the ß phase of a Ti-Mn-N alloy; but this structure was attributed to nitrogen-rich a precipitation. The nitrogen content of the Ti-Ni alloys does not exceed 0.02 pet and the quenching rate was sufficiently rapid to suppress precipitation reactions. Since X-ray diffraction results have confirmed the absence of any second phase which might account for this phenomenon, it seems unlikely that this substructure is explicable in terms of nitrogen content. Fig. 1 shows the substructure in adjacent grains of 100 pet ß phase in a quenched 6 atomic pet Ni alloy. Fig. 2 shows adjacent ß grains in a similarly treated alloy; one grain contains marked intracrys-talline boundaries and the other is completely free from any substructure. The suberystals appear to have fairly regular shapes, suggesting a regular orientation relationship among them. Tempering the retained ß structure at temperatures below the eutectoid eliminates the substructure at an early stage of ß decomposition. At the present time it is possible only to guess at an explanation for this subboundary phenomenon, since very little work has been reported on substructures resulting from phase changes. It is believed that the present phenomenon is due to poly-gonization resulting from unrelieved stresses set up

Jan 1, 1957

By Zoran M. Stevic, Mirjana M. Rajcic-Vujasinovic, Zvonimir D. Stankovic

"Huge electrochemical investigations have been performed on Technical faculty in Bor (Serbia) which main goal was the clarification of the copper sulfide minerals behaviour in hydrometallurgic and flotation processes. Modeling of these processes was a part of the effort for better understanding of the reaction mechanisms.The consideration of electrical analog circuit and mathematical model of processes at interfaces copper sulfide/electrolyte (CuS/(CuSO4+H2SO4), Cu2S/H2SO4 and CuFeS2/H2SO4), based on studies of the overvoltage – time transients, will be presented. The transients were obtained using single pulse galvanostatic method and electrochemical cell with standard three electrode assembly. In that goal it was developed an original system for computer measurements that enables the application of several methods for electrochemical investigations (galvanostatic, potentiostatic, cyclic voltammetry, electrochemical impedance spectrometry etc). The system was tested and adjusted using commercial electrochemical equipment made by AMEL, Milano.In the first stage of consideration the different equivalent electrical circuits have been tested by computer programme OrCAD 9.2 in order to identify the circuit with responses equivalent in shape to experimentally obtained ones. In that way it was established a configuration of an analog electrical circuit for investigated electrochemical system. That phase enabled only very rough determination of values of circuit components and their relative ratio.In the second stage the method for determination of all elements of electrical analog circuit is described. It is based on mathematical consideration of a given circuit on one hand, and valves of the overvoltages at selected times, obtained from charging and discharging parts of galvanostatic transients, on the other."

Jan 1, 2003

By M. Kobayashi, Y. Nishisu

"Fine multicomponent particles of yttrium and europium were synthesized through the precipitation from homogeneous solution, and the various characteristics related with the fluorescence were investigated. The morphology and the fluorescent characteristics of the synthesized particles were affected by ionic species in the stock solution. In the presence of sulfate ion, some parts of the precipitated particles were aggregated, and _the fluorescent characteristics were not good. On the other hand, in the presence of chloride ion or nitrate ion, the particles precipitated were almost monodispersed, and, the intensity of the fluorescent emission were strong after calcination. Further, these particles were also very attractive as the red phosphor in the mercury-free fluorescent systems.Introduction Eu doped Y oxide particles have been widely investigated for the application to the fluorescent lamps and displays: Recently, the fluorescent lamps are pointed as harmful electric equipments because of using mercury for excitation. Therefore, the use of the mercury in the fluorescent- system will be limited or prohibited worldwide in near future. Then, the development of the mercury-free fluorescent lamp is strongly required without delay. Inert gas such as neon and/or xenon seem to be applicable as new excitation element that replaces the mercury. However, in case xenon the excitation wavelength,' 146 and 172nm, is different from that of the mercury, 254nm, and then, the commercial phosphors which are used in the present fluorescent lamp system are not available. Therefore, the invention of the novel phosphors is essential for the development of the mercury-free fluorescent lamp. Further, the controls of the size and shape of the particles precipitated are also important, because the homogeneity of the size and the shape is very important for the fabrication of the layer of the phosphor particles. That is to say, the development of the phosphor particles with controlled components, size and shape is essential. The precise control of size and shape improves the packing density, and so, the screen performance of the lamp [1]. In addition, these phosphor particles should be also useful for the application of the flat-plane displays, for example, PDP, etc. [2,3]. In the present work, first, the particles including yttrium and europium for the precursor for red phosphor were prepared through precipitation from homogeneous solution. This process was precisely controlled for the control of the components, size and shape of the particles precipitated. Next, the particles precipitated were calcined, and then, their fluorescent properties were characterized. As a result, some of them showed the possibly available characteristics as the red phosphor for mercury-free fluorescent lamp system. These experimental results are presented in this paper."

Jan 1, 2000