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By M. Kosugi, M. Kawata, J. V. Satur, K. Mitsuhashi, R. Kawarabuki, W. Kracht, Y. Ebisu

Copper concentration is becoming more difficult because remaining copper ores are more complex and of finer copper mineral grain size, making copper minerals harder to float because of the fine particle size required to liberate the valuable species. The purpose of this work was to study the flotation behavior of fine copper sulfide ores at different conditions of agitation and aeration. The experimental campaign was carried out in a laboratory Denvertype flotation cell of 1 L volume modified to be operated with forced air that allows decoupling air flow rate and agitation speed. Four ore samples from Chile were used, all of them containing copper sulfides such as chalcopyrite, bornite, chalcocite, and tennantite, but with varying grain sizes and compositions. Preliminary flotation tests for establishing the flotation conditions of grinding size and collector dosage were conducted before the kinetic flotation tests that were carried out at different agitation speeds varying from 900 to 1300 rpm for gas flow rate ranging from 1.6 to 7.2 L/min. The flotation products were analyzed by ICP-MS and MLA (Mineral Liberation Analyzer). The results showed that high agitation speeds with corresponding air flow rates resulted in better recovery than moderate agitation speed and air flow rate, and an excess in gas flow rate resulted in bad performances. The flotation rates of the fine copper minerals were improved despite the different improvement rates among the fine size fractions. The impact of these operational variables, however, was different when comparing the results for the four ore samples. While it was found that the order of floatability in the four samples was the same, that is, chalcocite > tennantite > bornite > chalcopyrite, the kinetic constants of the copper minerals in the samples were different, indicating that mineral composition in the sample affects the flotation kinetics.

Jan 1, 2018

By Melcher G

The challenge to the zinc industry is shifting from maximum metal recoveries to the environmentally safe processing of the ore concentrates. The main source of solid residues from hydrometallurgical zinc processing is the iron content of the concentrates. Unfortunately iron precipitates from leach liquors contain various compounds which cause them to be considered as environmentally unsafe, unless they have been cleaned in subsequent process steps. This calls for separating the iron from hydrometallurgical processing as early as possible. For this purpose a process has been designed to eliminate the iron directly after neutral leaching the calcine. This is being done by direct smelting the neutral leach residue with a cyclone/top blowing unit. The zinc is recovered from the neutral leach residue as a metal oxide to be recycled to the zinc process. The iron is converted to a slag, which is resistant to atmospheric attack. Key data of the integrated hydro-/pyrometallurgical process are presented as derived from pilot plant tests by cyclone smelting and top blowing the slag.

Jan 1, 1993

By G. D. Trump, F. L. Stanley

Spirals have become one of the most popular methods for treating fine coal. Unfortunately, spirals tend to produce an undesirably high specific gravity cut point and often misplace significant amounts of coal and/or rock. In the present study, a process-engineering tool known as linear circuit analysis was used to identify problems with traditional spiral circuits and to suggest alternative configurations. These analyses indicate that a modified rougher-cleaner circuit incorporating a middlings recycle stream offers the best option for improving performance while maintaining a reasonable circulating load. In light of this finding, a full-scale test circuit was installed and evaluated at an existing preparation plant. Data obtained from the plant tests indicate that the new spiral circuit can simultaneously reduce the cut point and improve separation efficiency. Preliminary economic analysis show that the new circuit provides an attractive payback on capital investment.

Jan 1, 1999

By Dugan K. J

Mine operators are currently in a situation where market forces are acting to reduce profit margins and at the same time, regulatory bodies are insisting on improved mine safety and stability. This means that ground support must be made more cost efficient while maximising operator and equipment safety.A key aspect of ground support efficiency is the 'in the ground' performance. This paper discusses the factors that influence the way rock bolts and cable bolts perform. It highlights the need to know how support efficiency varies in different ground conditions.

Jan 1, 1992

By C. R. Bopp, N. A. C. Smith

"For a period of several years, beginning with 1915, there has been a continuous change in the quality of motor gasoline. The average volatility has decreased, this to the fact that higher boiling fractions of the crude oil have been included in the gasoline. This change in quality was made necessary by the tremendous increase in the demand for motor fuel, caused by the development of the motor car, and during the war was an absolute necessity to avoid gasoline shortages. The Bureau of Mines has kept in close touch with this situation by making surveys from time to time of the gasolines sold throughout the country, as this information is of value to manufacturers and users of motor cars and also indicates when any changes are required in the Government specifications. The Bureau has just completed a gasoline survey and is in a position to make public the fact that there has been very little change in the quality of motor gasoline in recent months.During the period from January 17 to February 3, 1920, 81 samples of actor gasoline were collected by representatives of the Bureau of Mines in seven districts of the United States. The cities selected for this survey were New York, N. Y., including Brooklyn; Washington, D. C.; Pittsburgh, Pa.; Chicago, Ill.; New Orleans, La.; Salt Lake City, Utah; and San Francisco, Cal., including Berkeley. In every case the samples collected were taken in such a manner as to represent material actually being sold as motor fuel, and to include samples from each refinery marketing in the district."

Jan 1, 1920

By Yin J, Sun H

A new technology has been introduced - the use of the High-Water Solidifying Material for providing pumped roadside supports to maintain a roadway for re-use in longwall retreating. As a gob edge support, its initial use at Hebi No. 1 Colliery was successful, providing acceptable performances in support and control of convergences and lateral closures of the gob-edge roadways. This acceptability applied to both first use and re-use when the roadway became a gateroad for the adjoining longwall, remaining stable throughout the associated loadings and convergences. The technology promises economic and social benefits.

Jan 1, 1992

By Ira L. Wright

This paper describing the milling practice of the Black Hawk Consolidated Mines Co., is one of a series being prepared by the United States Bureau of Mines. ACKNOWLEDGMENTS Part of the information contained in this paper was furnished by I. H. Stanley, mill superintendent, Black Hawk Consolidated Mines Co., Hanover, M. M., and a part by the South-western Engineering Corporation, Los Angeles, Calif. The assistance of T. G. Chapman in arranging the paper for publication is also acknowledged.

Jan 1, 1930

The ore mined from the Lead Lode of The Zinc Corporation leases consists of a fairly granular mixture of galena, marmatite, chalcopyrite, tetrahedrite, pyrrhotite, pyrite, and lollingite with a gangue association of calcite, quartz, bustamite, rhodonite, mangan-hedenbergite, garnet, fluorite, mangano-calcite and apatite. The silver content of the ore occurs in three minerals tetrahedrite, dyscrasite, and pyrargyrite, the last two mentioned occurring in microscopic association only. Other metallic and gangue minerals are also present in this complex mineralogical association, but do not influence the milling operations.Fortunately, the silver minerals favour the galena and chalcopyrite as their host minerals, thus facilitating the recovery of both copper and silver in the lead concentrate. The ore from the Lead Lode assays from 14 - 18 per cent lead; 3.0 - 4.5 oz silver per tonne, and 9.5 - 12.0 per cent zinc.A parallel lode, known as the Zinc Lode, is well developed in The Zinc Corporation leases. This lode assays from six to eight per cent lead, 1.5 oz silver per ton, 18 - 25 per cent zinc with a siliceous gangue. The common Lead Lode gangue minerals, calcite, rhodonite, bustamite - are very rare in present underground exposures. No metallurgical work was done on this ore during the pilot plant operations.The aim in the milling process is to produce:1. A lead concentrate with the maximum economic recovery of lead, silver, gold, copper and antimony, and minimum zinc content.2. A zinc concentrate with the maximum economic recovery of zinc, cadmium, and cobalt, and minimum iron, arsenic and fluorine content.3. A waste residue containing sufftcient granular material to be utilised as underground fill.In considering the economics of the milling practice the above three requirements plus consideration of the tariffs submitted by the purchasers of concentrates were the deciding factors in the evolution of the present milling practice.Towards the end of 1924 The Zinc Corporation Limited added to and adapted the old zinc tailings plant for the treatment of 5000 tons of crude ore per week. This plant, which operated until January 1936, was in general principles similar to the standard Broken Hill methods of ore concentration, whereby the galena was recovered by the gravity concentration methods of jigging and tabling with selective flotation concentration of the residual galena and marmatite. One important difference from other Broken Hill plants was that the primary grinding of the jig tailing was performed with flint-loaded mills operating in closed circuit with revolving screens. Two primary grinding sections were installed, each consisting of two 5 ft diameter by 10ft long tube mills loaded with flint pebbles working in closed circuit with four 3 ft diameter by 3 ft wide revolving screens covered with 22mesh Toncap woven wire screen with 0.57 mm opening. Each section carried a circulating load of 28.3 tons per hour for a jig.

Jan 1, 1994

By Ramana G. Reddy, Yudong Li

Numerical modeling of the thermal plasma process was carried out based on the thermal plasma reactor in our lab and confirmed using experimental data. The inlet boundary conditions of a non-transferred DC arc thermal plasma reactor were used in modeling the temperature and fluid flow distribution in the reactor. Different mesh grid sizes were used to confirm the model is independent of grid size. Temperature profile and gas flow distribution in the thermal plasma reactor were developed by the computational fluid dynamics (CFD) with ANSYS Fluent. The predicted temperatures are in good agreement with the experimentally measured temperatures in the reactor. The influence of plasma torch input power as well as the plasma gas flux on the temperature distribution was investigated using this model. The influence of power input and gas flow rate on temperature and velocity distributions are not independent. Generally, higher power input and lower gas flow rate will give rise to the temperature increase in the reactor.

Mar 1, 2017

By L. B. McConville

The general term "tar sand" refers to sand that contains varying amounts of dense, viscous petroleum. Tar sand deposits have been found throughout the world, often in the same geographical area as conventional petroleum. The largest one by far is known as the Athabasca Tar Sands, in the province of Alberta, Canada. Actually a group of three deposits, these particular sands underlie an aggregate area of more than 12,000 sq miles. Current estimates place the contained raw petroleum at about 700 billion bbl; and via currently available technology, the amount of recoverable synthetic oil may be as much as 300 billion bbl-which is roughly equivalent to five times the combined US and Canadian total crude oil reserves. With the ever-widening gap between energy supply and demand, mining and petroleum companies are now evaluating all possible energy resources-both developed and underdeveloped-and, certainly, the Athabasca Tar Sand deposit is one of the more important ones to merit such attention. The first section in ME deals with the geology and historical developments; the other four sections, with mining methods, extraction technology, economics, and outlook.

Jan 1, 1975

By J. H. Richards, G. Derge, W. Peifer

A WIDE Variety of metallurgical defects in steel have commonly been attributed to the presence of excessive amounts of hydrogen. These defects include flakes in rails and forgings, cracks in welds, and blisters in enameled ware, They have been related to hydrogen largely by circumstantiat evidence because the proper sampling and analysis of steel for hydrogen has been known to be difficult and because no general agreement has existed with regard to the relative suitability and accuracy of available methods. The need for a direct approach to these problems has been widely recognized. This general situation has been well described in the publications of the British committee on the Heterogeneity of Steel Ingots,' and current approaches to the problem were reviewed in a recent symposium of the AIME.I2 The plans described by the present authors at that meeting have now matured satisfactorily and will form the basis of this paper. The principal object of this paper will be to describe the methods of sampling and analysis which have been developed and to illustrate the usefulness and limitations of these methods by citing their application to a specific problem, The first problem selected for investigation was the behavior of hydrogen in rail steel. This was chosen because the occurrence of shatter cracks in rails has received a great deal of study over a long period of time. The defect can be controlled by the expensive procedure of slow in However, it may be hoped that a better understanding of the factors influencing the hydrogen content of rails will lead to a more efficient control of this problem. Rails provide a good starting point for a more general study of hydrogen in steel because they provide a cross-section large enough to develop cracks, Yet small enough for convenient handling and sampling. Rails were also selected because they arc made from plain carbon steel and it was felt that the initial work should not be complicated by the effects introduced by alloying elements. The considerations which determined the original planning of this study should be reviewed. The inherently complex nature of most hydrogen problems requires that a large amount of data must be collected for any particular case. This in turn means that any analytical procedure should be as rapid and simple as possible. The same objective of speed is indicated by the fact that it may finally become desirable to use hydrogen analysis in process control. It is also known that hydrogen is highly fugitive and that any procedure which facilitat~s early analysis of the sample without prolonged or irregular storage has distinct advantages. The most important previously reported methods of analysis may be classified into three general groups: (I) Vacuum fusion, (2) Vacuum extraction (without melting), (3) Total combustion.

Jan 1, 1949

By G. Derge, W. Peifer, J. H. Richards

A WIDE Variety of metallurgical defects in steel have commonly been attributed to the presence of excessive amounts of hydrogen. These defects include flakes in rails and forgings, cracks in welds, and blisters in enameled ware, They have been related to hydrogen largely by circumstantiat evidence because the proper sampling and analysis of steel for hydrogen has been known to be difficult and because no general agreement has existed with regard to the relative suitability and accuracy of available methods. The need for a direct approach to these problems has been widely recognized. This general situation has been well described in the publications of the British committee on the Heterogeneity of Steel Ingots,' and current approaches to the problem were reviewed in a recent symposium of the AIME.I2 The plans described by the present authors at that meeting have now matured satisfactorily and will form the basis of this paper. The principal object of this paper will be to describe the methods of sampling and analysis which have been developed and to illustrate the usefulness and limitations of these methods by citing their application to a specific problem, The first problem selected for investigation was the behavior of hydrogen in rail steel. This was chosen because the occurrence of shatter cracks in rails has received a great deal of study over a long period of time. The defect can be controlled by the expensive procedure of slow in However, it may be hoped that a better understanding of the factors influencing the hydrogen content of rails will lead to a more efficient control of this problem. Rails provide a good starting point for a more general study of hydrogen in steel because they provide a cross-section large enough to develop cracks, Yet small enough for convenient handling and sampling. Rails were also selected because they arc made from plain carbon steel and it was felt that the initial work should not be complicated by the effects introduced by alloying elements. The considerations which determined the original planning of this study should be reviewed. The inherently complex nature of most hydrogen problems requires that a large amount of data must be collected for any particular case. This in turn means that any analytical procedure should be as rapid and simple as possible. The same objective of speed is indicated by the fact that it may finally become desirable to use hydrogen analysis in process control. It is also known that hydrogen is highly fugitive and that any procedure which facilitat~s early analysis of the sample without prolonged or irregular storage has distinct advantages. The most important previously reported methods of analysis may be classified into three general groups: (I) Vacuum fusion, (2) Vacuum extraction (without melting), (3) Total combustion.

Jan 1, 1949

By C. W. Sill

[In the original Norris and Fay method for determining selenium, selenious acid is reduced by an excess of standard thicsulfate in accordance with the following reaction: H2Se03 + 4Na2S203 + 4HC1 = Na2SeS406 + Na2S406 + 4NaC1 + X20. (1) The excess thiosutfate is then back-titrated with standard iodine solution. The disadvantages of ouch a method are obvious. On an unknown sample, the quantity of thiosutfate required would be difficult to determine; a definite excess is required, but large back titrations would be undesirable. Inasmuch as thiosulfate is decomposed by acid, considerable error may be introduced in this method, the amount depending on the acidity, temperature, concentration of excess thiosulfate, duration of contact between thiosulfate and acid, and other factors, In a critical study of the Norris and Fay method, Coleman and McCrosky3/ show that the method is accurate to less than .1 part per thousand if the excess of this sulfate Is not greater than 5 ml. of 0.1 N solution (in 1.0 ml. of 0.x4 N sulfuric acid) whether the titration is made at 0° or 20°C. A greater excess produced unsatisfactory values at either temperature. Coleman and McCrosky regulated the excess thiosulfate by adding 5-ml. portions of thiosulfate solution followed by the addition of 1 to 3 drops of 2.5 percent potassium iodide in the presence of starch. If a starch-iodine blue color formed locally around the drops of potassium Iodide, the reduction of selenious acid was not complete. On stirring the solution, the local blue color fades and another 5-ml. portion of thiosulfate is added. When addition of potassium iodide fails to produce a local blue color, reduction of selenious acid is complete, and the excess thiosulfate is then back-titrated with standard Iodine solution. The number of equivalents involved in the reduction of selenious acid by either thiosulfate or iodide is the same, and therefore no correction need be made for the potassium iodide. This procedure is much better than the original Norris-Fay titration, but acidity and time would stilt be rather critical factors subject to variation with individual technique. Also, the method still requires the lose of two standard solutions, a rather undesirable factor from the standpoint of routine application.]

Jan 1, 1954

By R. J. Gochin, P. Bevilacqua, G. D. Schena

This class of flowsheet-dependent simulators does not replace modular simulators, such as Modsim and Microsim, which are necessary for the assessment of different flowsheets before selection of the most desirable technical option and for investigation of the fine details of unit processes. The system presented here is regarded as complementary, serving in the early stages of feasibility studies as an aid to assessing the convenience and economics of preconcentration; the example used is of dense-medium preconcentration of a barytes-fluorite ore

Jun 13, 1905

By A. W. Laughlin, C. R. Mansfield, M. J. Ferris, D. A. Cremers

Laser-Induced Breakdown Spectroscopy or LIBS can be used to provide exploration companies with precise and accurate chemical analyses in the field, in real-time, resulting in major time and cost savings. Using a Field-Portable Analyzer(FPA), anomalies can be followed up immediately while crews are still in the field. Lower limits of detection (LLDs) are element dependent, but many are sufficiently low to be useful in exploration. LLDs in ppm for selected elements of interest are: Be-2, Cu-3, Zn-20, As-200, Sb-500, Pb-30, Ag4,Mo-100, B-33, Ti-500, V-350, and Cr-l. LIBS analyses require little or no sample preparation.

Jan 1, 1999

By F. R. Hutto Jr., F. L. Kady Jr., L. E. Weymouth

The behavior of particulate non-metallic materials in moving contact with smooth surfaces is of interest and concern to manufacturers and users of abrasives, of fillers, and of pigments alike. The theoretical aspects of the subject have been treated to considerable extent in the literature, and correlatic,ns are available that attempt to relate various methods of hardness determination." 2 The particle size and friability are characteristics of the abrasive that are not related to the smooth surface. The hardness, on the other hand, may be visualized as relative to that of the smooth surface. In a study of abrasive action, the role that hardness, per se, plays is a complicated one. For it is necessary to compare the "hardness" of the abrasive, usually a non-metallic, with that of the smooth surface, generally a metal. Hardness of non-metallics is defined as resistance to scratch and is almost universally described with respect to the Mohs scale.3 Minerals have been rated by Mohs numerically from the softest (talc = 1) to the hardest (diamond = 10). By definition, a mineral has a designated hardness when it is scratched by the standard that is numerically just above it on the scale; and conversely, when it scratches the standard that is just below it. Hardness of metals. however.. implies resistance to indentation, a property that has been measured by a number of methods. In fact, the indentation hardnesses of the standard minerals on the hlohs scale have been determined by the Rockwell tester. Reproduced below are two versions of this correlation. 'A conversion chart, prepared by Wilson Mechanical Instruments Division of American Chain and Cable Co., merely gives the conversion from Rockwell to Knoop hardness. The relation between Knoop indentation hardness and Mohs scale has been reported by G. S. Smith — A New Scale of Hardness, The Engineer, Aug. 26. 1949. G. F. Kinney in Engineerin Properties and Aplications of Plastics reports the Rockwell hardness of the minerals directly in the Mohs scale. The question immediately arises as to whether this relation is valid when applied in reverse; namely,

Jan 1, 1961

By A. K. Riihimäki

The description deals with duplex stainless cast steels and austenitic high molybdenum steels used in pumps for severe condition service. The main modem nitrogen alloyed duplex cast steels are presented in the ASTM standard A-890. Two grades of high molybdenum austenitic stainless steels there are presented in ASTM A-744 (-96) standard i.e. CN-3MN and CK-3MCuN. The latest and most corrosion- resistant stainless steel grade is AVESTA 654 SMO?. Avesta Sheffield the trademark owner has granted Ahlstrom Pumps license to produce the material. This new stainless steel as pump material for severe service has improved properties in the hydrometallurgy and electrorefining processes of metal and especially in the copper industry compared to duplex stainless steels. The paper deals briefly with the foundry process to manufacture high alloy stainless steel pump castings. The AOD-method (AOD= Argon Oxygen Decarburization) is an important prerequisite for the melting of low carbon, high chromium and molybdenum alloyed nitrogen steels. The properties of these steels are included. The main topic is the corrosion resistance of the above-mentioned pump materials in severe service. Results of short-time erosion and corrosion tests are discussed and compared with the results of plant tests. Practical results of pump materials performance in severe service for the copper industry are given. The new high alloyed cast stainless steel (main elements; Cr-24%, Ni-22%, Mo-7,3% and N-0,5%) has shown improved corrosion and erosion properties as process pump material in several severe service applications e.g. in the metal industry.

Jan 1, 1999

By R. E. Zimmerman

ALTHOUGH flotation of coal is considered relatively new in the United States by coal-preparation engineers, actually it has been practiced to some extent for the past 30 years, It is practiced much more widely in Europe than in the United States. Commercial plants are operating in nearly all major coal-producing countries of the world. A froth flotation plant has been operating since 1930 at the Champion No, 1 preparation plant of the Pittsburgh Coal Co. Unfortunately the term flotation is widely used in the United States by coal-preparation engineers to designate dense medium processes of coal cleaning. As used here, flotation means those processes for cleaning fine sizes of coal in which the coal is collected in a froth or matte at or near the surface of a pulp. The refuse particles remain in the pulp. Two distinct types of flotation are practiced: froth flotation and agglomeration. FORMS OF FLOTATION The theory of the principles of flotation and of the physicochemical foundations surrounding this process has become a complex and scientific field and coal-preparation engineers contemplating use of flotation processes would do well to study the works of Gaudin, 2, 5 Taggart, 3 Zimmerman, 4 Wark, 6 Ralston, 7 Petersen. 8 Bulk Oil Flotation.-In this process the separation of mineral from gangue is accomplished by virtue of the fact that minerals of metallic lustre, as sulphides, or hydrocarbons, as coal and graphite, are wetted preferentially by oil in the presence of water and consequently pass into the interface between oil and water; while gangue or rock is wetted by water and remains in the medium. Beginning in 1860 with Haynes and later between 1897 and 1907, at least 25 patents were granted for bulk oil flotation. Large quantities of oil are required, generally 3 to 25 per cent by weight of feed, and recovery of such oil is a major problem. The Elmore process 3 (1901 and 1902) is an example of a bulk oil process, The Trent process (1902-25) has been used for the cleaning of coal on a commercial scale, According to E. W, Davidson 9 there were five such plants operating in the United States by 1925. They have since been abandoned.

Jan 1, 1950

By Luis Enrique Vargas

Las técnicas estadísticas multivariantes (análisis factorial y el análisis cluster), permiten establecer el grado de interdependencia y la relevancia de las correlaciones múltiples entre las variables estudiadas (46 elementos traza), características que no se pueden determinar con los métodos descriptivos tradicionales. En ese sentido, el presente trabajo aborda la investigación realizada a la cuenca del río Huaura, Lima, donde se efectuó un muestreo de sedimentos activos de corriente en 393 estaciones representativamente distribuidas. Dichas muestras han sido tamizadas con la malla 200 y analizadas por el método ICP-MS, previa digestión con agua regia, con el objetivo de determinar elementos traza distintivos en sedimentos activos, de acuerdo al ambiente geológico del cual provienen, mediante su comportamiento multivariante, dispersión y distribución geoquímica secundaria y así identificar elementos traza de interés minero, relacionados a los elementos traza distintivos previamente definidos.

Sep 14, 2009

By By Staff

"Acid mine drainage can be controlled by water treatment, retardation of the pyrite oxidation reaction system, or enhanced prediction that allows preventive action to be taken. The Bureau of Mines is conducting research in each of these areas; the results of this research are summarized in the eight papers that comprise this volume. Field work to evaluate overburden analysis, alkaline injection, and bactericidal control of acid formation is described, along with two new inexpensive methods to treat acid mine water. These papers were prepared for an acid mine drainage technology transfer meeting held in Pittsburgh, PA, on April 3 and 4, 1985. INTRODUCTIONAcid drainage from coal mines is one of the most persistent industrial pollution problems in the United States. Over 5,000 miles of streams and rivers are adversely affected, primarily by underground mines that have been abandoned for decades. Meanwhile, at active mining operations and at sites where mining occurred after 1977, discharge water must be treated to meet fairly stringent regulatory limits--at a cost to the industry of over $1 million per day.The Bureau of Mines has a special responsibility to facilitate integration of mining and mineral processing with environmental safeguards. This responsibility is twofold: the development of techniques to reduce or eliminate environmental degradation, and the improvement of existing pollution control processes to make them more efficient and more cost effective. Research in acid mine drainage exemplifies the Bureau's concern for these environmental aspects of mining.This collection of papers summarizes much of the Bureau's recent research on acid mine drainage and will give the reader a sense of where the research is headed, in addition to providing details regarding new technology and recently acquired knowledge. The research papers address four basic objectives:"

Jan 1, 1985