Search Documents

By E. R. Morgan, J. C. Shyne, V. F. Zackay

NITROGEN used as an alloying element in steel has received increased attention in recent years. Its merit as an austenite stabilizer and hot strengthener has long been recojinized, particularly by European investigators.' Recent work' indicates that nitrogen contents of 1/2 pet or more allow the addition of several percent of ferrite-forming hot strengtheners, such as molybdenum, without subsequent austenite decomposition at elevated temperatures. The room temperature properties of such alloys are characterized by high yield and tensile strengths with excellent ductility, even after cold working, as shown in Tables I and 11. The 1350°F creep-rupture properties of Cr-Mn-Mo-N steels are comparable to those of commercial alloys such as Timken's 16-25-6, containing 16 pct Cr, 25 pct Ni, and 6 pct Mo, as shown in Table 111. Cr-Mn steel containing 1/2 pet N must be made under pressure if ingot gassing is to be avoided. However, there are difficulties attendant to this practice. Pressure melting restricts the ingot size, and the equipment required is costlier and more complicated than comparable air melting facilities. An effort was made, therefore, to determine more economical methods of adding nitrogen. The pressures generated in centrifugal casting usually range from 5 to 10 atm and are sufficient to prevent the gassing of high nitrogen Cr-Mn steels. A centrifugal casting was made of an alloy containing 16 pct Cr, 18 pct Mn, 2 pct Mo, and 0.73 pct N. A risk, 8 in. diam and 11/2 in. thick, was cast at 1000 rpm. It has been calculated that a pressure of 9 atm was developed at the periphery of the disk at this speed. Metallographic inspection of specimens taken from the disk revealed no gas holes or other defects. The elevated temperature properties of radial and circumferential specimens taken from this casting are given in Table IV. The creep-rupture life of this cast nickel-free austenitic steel was equivalent to that of the wrought Cr-Mn-Mo-N steels. Although centrifugal casting appears to lend itself to the manufacture of high nitrogen austenitic steels, its applicability is limited to relatively small sizes. A process applicable to the production of large ingots of high nitrogen steels is suggested by low carbon rimming steel practice. Gas holes formed during ingot solidification are not detrimental so long as they weld shut during hot rolling. An economic advantage of gassing ingots is the increased ingot-to-slab yield, especially if the ingots are mechanically capped. Also, it is probable that higher nitrogen levels can be achieved with mechanically capped ingots than with hot-topped ingots. A series of gassy heats was made under both atmospheric and higher pressures, as indicated in Table V. Several of the air melted ingots were mechanically capped by chilling the molten ingot tops with a steel plate. The ingots were allowed to freeze in steel molds without hot-tops unless otherwise indicated. A comparison of Table 111 with Table V shows no significant difference in the creep-rupture properties of the gassy and the nongassy ingots after hot work- ing nor between the gassy ingots produced under different conditions. References 1 F. Rapatz: Application of Stainless and Heat Resisting Steels Alloyed with Nitrogen. Sinhl and Eisen ( 1941) 61, pp. 1073-1078. 'V. I?. Zackay, J. F. Carlson, and P. L. Jackson: High Nitrogen Austenltlc Cr-Mn Steels. Trans. ASM 119551 48, PP. 509-523.

Jan 1, 1957

By Walter Estrada, Fernando Valencia, Jaime Luyo

La gasificación por plasma es un proceso térmico a alta temperatura en el que los desechos se descomponen en elementos fundamentales y compuestos simples en un entorno anaeróbico. El sistema presentado en este artículo actúa como un digestor al transformar las moléculas de carbono y otras sustancias en compuestos menos contaminantes. Se utilizó una mezcla de cianuro disuelto en agua como muestra de ensayo —procedente de aguas de una mina—, que se sometió al componente radiante de plasma, y se estudió la energía generada actuando sobre la purificación y transformación de las muestras.

Sep 30, 2019

By J. -C. Sztuke, M. Cao

ABSTRACT Wash water and polyethylene oxide (PEO) were used in the flotation of quartz and coal. Wash water decreased entrainment of –15 µm quartz. The optimum superficial wash water rate was 0.05 cm/s. PEO also lowered entrainment. The combination of wash water and PEO led to a slight further reduction in entrainment. For 1:1 mixtures of –15 µm quartz and –300 µm oxidized coal, the combined use of wash water (0.05 cm/s) and PEO increased the separation efficiency from approximately 30% to > 70%, whereas wash water alone at 0.05 cm/s did not lead to a discernible increase.

Jan 1, 2014

Application of Gy?s formula is appropriate for calculation of the Fundamental Error (FE) prior to samples being collected at any stage of the minerals process, provided that sampling parameters K and a (alpha) have been determined by calibration of the ores. Two types of calibration procedure are well established in the industry, the Hetrogeneity test and the 32-piece sampling tree experiment. The sampling tree experiment uses the variance and average grade of metal analyses from four series of samples at different nominal fragment size, as the basic input data. Pierre Gy suggested the cube as an appropriate exponent of the nominal fragment size for use in his equation. More recent work suggests that this exponent is variable and characteristic of specific ores and therefore requires calibration. The method described here explains the experimental procedure of the calibration. It is then possible to calculate a sampling nomogram using the sampling parameters K and a. This allows the sampler to determine a suitable protocol for the sampling event that will ensure that the FE does not exceed a predetermined precision at any point in the sampling procedure.

Jan 1, 2007

By C J. Moran

All mines face water management challenges. Adopting leading practice water management strategies can help reduce both operational and strategic risks. While many of the water issues faced by underground mines are the same as other operations, underground mining presents some unique water management challenges. In this paper we review trends in underground mining, water use and associated water issues. We then compile a structured set of strategic and operational risks that are pertinent to underground operations. The causes, threats, opportunities and measures for controlling or mitigating the risks are summarised. The risk compilation could provide an addendum for underground operations to the Australian governments leading practice water management handbook.

Mar 21, 2011

The Reefton Goldfield on the West Coast of the South Island of New Zealand was a significant gold producing area between 1860 and 1951. During this period it produced approximately 2.1 million ounces (67 tonnes) of gold. The largest single producer on the goldfield and the deepest mine in New Zealand, was the Blackwater Mine at Waiuta which produced 21 tonnes of gold. The Prolubition Shaft reached a depth of 878 metres (317 metres below sea level). The mine closed suddenly in 1951 with about 66 000 tonnes of are remaining in the stapes. Since closure there has been no attempt to determine the ore potential of the mine at depth. This paper summarises the geology, history and resource potential of the mine and sets out two options for evaluating the remaining resource. The options are either deep drilling from surface or recovery of the Prohibition Shaft and underground development and drilling. A schedule for each option is presented and discussed.

Jan 1, 1992

The title of my presentation is `Nursing One's Resources', words that fit a young organisation like Ross Mining and words we had to apply to reach our current level as a company. To get to where we are, we had to nurse, foster and treat carefully all our available resources in the widest sense of the word, namely: ò a stock or supply that can be drawn upon (funds, mineral resources, human resources); ò the means available to achieve an end; ò skills in devising expedients; and ò practical ingenuity. I do not claim that Ross Mining is now the perfect mining company. However, we have become a profitable, dividend- paying, gold mining and exploration company which is to our knowledge, currently the cheapest gold producer on the Australian continent. Nursing our resources got us where we are and will guide us in our future development. The words `nursing one's resources' are I feel particularly applicable to mining-as I like to argue that the extractive mining industry has a social responsibility to optimise the metal output and value from each orebody which is being exploited, and preferably leave no metal behind. Likewise, a modem company cannot survive into the future without maximising and optimising its human resource potential. In this presentation I would like to present a number of actual examples of nursing one's physical and human resources. Before I do that, I will give a brief background to Ross Mining. Ross Mining NL is a young Queensland-based company that gained its stock exchange listing in September 1987 and that poured its first gold in 1989 from its own developed Belyando Mine, located in Central Queensland. We have now reached the stage of a medium-size gold producer, producing approximately 70 000 ounces of gold per year, mainly from the Yandan Gold Mine, also in Central Queensland. Our production is set to increase to over 100 000 ounces in the near future. Recent increases in our resource base have secured us a future of ten to 15 years. As a young, newly listed company, we faced all the dangers that most new small floats do as a new entrant into an established industry. However, one advantage of being young and perhaps naive, is summed up by the following Zen Buddist saying: In the beginner's mind there are many possibilities, in the expert's mind there are few. A mining company's main assets are the sum of its resource base and the skills and talents of its people. Attempting to optimise both the physical and human resources within the company has been to-date the key to our success. The first example I would like to present is linked to the exploitation of the Belyando Gold Mine in Central Queensland.

Jan 1, 1995

By B. Samanta

This paper highlights the use of an innovative mine production scheduling scheme for grade-control planning tasks that take into consideration grade-model uncertainty. The scheduling exercise has been carried out with the help of a multiobjective genetic algorithm (MOGa) for the production scheduling operations. The underlying motive behind the use of MOGa has been the generation of a set of pareto optimal solutions to meet the goals of the target-grade specifications for the considered multiple grade attributes. Several new concepts related to MOGa formulation, in particular the mutation operation and the convergence criteria of this algorithm, are proposed in this paper. The modeling of grade uncertainty into the scheduling outputs has also been incorporated through a set of conditional simulated grade maps. The proposed scheme of production scheduling operations has been applied for the grade-control planning operations in an iron ore mine to meet the targeted grade specifications of iron, silica and alumina, and a risk analysis has been performed to this end.

Jan 1, 2013

Frank L. Bader has been appointed to the sales staff of Lehigh Navigation Coal Co. in the Philadelphia territory. H. C. Burrell, former coordinator of raw materials, Pittsburgh, Penna., has been made manager of raw materials for Columbia-Geneva Div. of U. S. Steel Co., San Francisco. J. H. Cazier has resigned as general superintendent of Bagdad Copper Corp., Bagdad, Ariz., to devote full time with E. A. Scholz to the operation of the Copper King, Phillips and Black Pearl Mines near Bagdad. They have operated the Copper King zinc mine for more than two years.. Production started from the Black Pearl and Phillips tungsten mines during the past year. Robert T. Chapman has resigned from Reynolds Mining Corp. to join Westmoreland Manganese Corp. as general superintendent. Annan Cook, with Kennecott Copper Corp.'s exploration dept. for the past three years, has been appointed district geologist for the eastern states.

Jan 1, 1952

By C. WIFLARD HAYES

(New Haven Meeting, February, 1909.) I DESIRE to make it perfectly clear at the outset that I fully realize the hazardous nature of any attempt to estimate the quantity of iron-ore or any other mineral in the ground. I should not have had the temerity to venture upon an inventory of the iron-ore supplies of the United States except for the requirements of the Conservation Commission. During the preparation of this inventory I have been impressed by the wide diversity in estimates of those best qualified to. hold an opinion, and I am therefore prepared in advance for criticism of my figures. Inasmuch as this report was prepared in large part for unprofessional readers, I considered it necessary to classify and describe the commercial iron-ores in a somewhat elementary manner, in order to explain the reasons for the large element of uncertainty in the estimates. I have therefore given a chemical and a geological classification of iron-ores, which place the commercial deposits in six classes: (1) magmatic segregations in basic igneous rocks; (2) contact-deposits formed in connection with igneous intrusions; (3) concentration-deposits; (4) replacement-deposits; (5) bedded-deposits, and (6) gossan-deposits. The iron-ores are further distinguished under two classes available and not available. This classification is in large measure arbitrary, and it, is evident that it will vary front time to time. In the available class are placed those ores which can be worked at a profit under conditions essentially as they exist at present. Since it depends wholly on the question of costs, the various factors which affect cost will determine the classification of any particular deposit. Actual production, * Abstract of Report prepared for the Conservation Commission. t Chief Geologist, United States Geological Survey. .

Apr 1, 1909

By Lester G. Morrell

AGAIN in 1963, as in nearly every year since 1946, the Canadian mineral industry has established a new national record in value of mineral production. The 1963 estimated total value of $2,976 million is 5 percent higher than the 1962 value of $2,845 million.2 As in previous years, metals made up more than half the value of total production. For selected years since 1949 the category percentages and total value are as follows: [ ] Crude petroleum, Canada's most valuable mineral product, accounted for 21 percent of the total value of minerals in 1963. In descending order came nickel 12 percent, iron ore 10 percent, copper 10 percent, gold 5 percent, and uranium 5 percent. Asbestos accounted for 5 percent, sand and gravel 4 percent, and cement 4 percent. The complete list of Canada's mineral products includes more than 50 basic commodities.

Jan 1, 1964

By Ludwig Schmidt

[The use of vapor-tight tanks has proved so effective in reducing the evaporation losses of petroleum that today practically all operators are using this typo of equipment. It has boon shown, however, that vapor-tight tanks should be supplemented with additional measures which will further reduce evaporation. Probably the most effective use of the supplemental measures are found on the small producing leases where the breathing losses from vapor-tight stock tanks materially affect the volume and gravity of the stored oil. The breathing loss from a vapor-tight stock tank that is filled and emptied daily is a negligible quantity. Also, the filling loss, which on the average varies between 0.1 and 0.2 per cent, usually is not of a sufficient quantity to affect materially the value of the crude. However, the combined breathing and filling losses from a vapor-tight tank requiring several days to fill are of sufficient importance to warrant the use of measures in addition to the vapor-tight tanks. The breathing losses are caused by atmospheric variations. Probably the greatest are the changes in atmospheric temperature which cause changes in temperature of the vapors in the tank. During the day, as the temperature increases, the gasoline-saturated vapors in the tank expand and are forced out into the atmosphere. At night the vapors are cooled and contract, drawing into the tank fresh air, which becomes saturated with gasoline vapor and is forced out of the tank during the following day. In Addition to the maximum and minimums temperature variations there are many smaller variations throughout a twenty-four period caused by showers, clouds, winds, and other atmospheric conditions which likewise cause the tank to breathe. The two mist common measures used by lease operators for reducing breathing losses in vapor-tight tanks are, first, operating; lease tanks under pressure, and second, the use of light colored paints anti tank houses. In this report these two methods are discussed together with their adaptability to lease operation. Results of experimental observations are given which show the reduction of evaporation looses where these supplemental measures have been used.]

Jan 1, 1927

By E. P. Youngman

In the Unfederated Malay States, with the exception of Johore, the rights of suzerainty, protection, and administration were transferred by giam to the British Government in 1909. In the States of Kelantan, Trengganu, Kedah, and Perlis, the rulers are assisted by State Councils and by British advisers appointed by the British Government.3 With respect to Johore, the largest, richest, and most highly organized of the Malay States not in the Federation, the treaty of December 11, 1885, with Great Britain, defined the relations of the State to the British Govern- ment and allowed the Maharaja to assume the title of "Sultan"; an amendment to this treaty (May 12, 1914) provided that the Sultan should be advised by a British officer, the General Adviser. ...... The political organization of the States is reflected in the mining legis- lation, Johore being the only one having a comprehensive code. The mining enactments now in force, according to the High Commissioner for the Malay States, are as follows:

Jun 1, 1932

By A. M. Gaudin

The recent study by R. M. Hays(l) prompted the study summarized in this paper. In his Interesting paper, Mr. Hays shows fine results to be attainable by a relatively complex flowsheet on a semi-taconite, a manifestly difficult ore to treat. We obtained a semi -taconite from Minnesota, and treated this sample by wet magnetic separation alone. The device in which the separation was accomplished is the standard pilot-plant, laboratory separator in use at Magnetic Engineering Associates' laboratory (MEA) in Cambridge, Massachusetts. It consists of a cylindrical space which can be magnetized by turning on the magnet of the separator. In this cylindrical space, there is a canister which provides the special configuration of the magnetic field and magnetic field gradients that MEA considers to be required. The ore pulp is made to flow through the canister while the current is on. A portion of the pulp is retained in the canister, and the rest is evolved as a non-magnetic fraction. The laboratory device is cyclic, but it accurately predicts the results obtainable by an Industrial unit of either cyclic or continuous type (moving matrix). The ore tested was 99.5°%o -325 mesh, and approximately 75% -500 mesh. The concentrate from this ore was, therefore, eminently suitable for pelletizing. In passing the ore through the magnet, we had the choice of repeatedly passing the concentrate from the first step through the operation, or of repeatedly passing the non-magnetics. In our experiments, the first method was clearly superior from the stand¬point of the cleanliness of concentrate. Of the many tests which we have made, we think that we have to retain two which

Jan 1, 1971

By George W. Riter

(Canal zone meeting, November, 1910.) A DISTINGUISHED engineer, the active head of a large mining company, has said that surveying attains the dignity of a profession only in the hands of a few men-the few who know how to keep notes that will be understood by even a novice without further word of explanation. Of all mine-records, survey notes are perhaps the most important. The maps made from them serve as a working-guide, and as framework for other data ; and when, from any cause, access to underground workings is shut off, the surveyor's record often becomes invaluable. So seldom does a surveyor have a chance to check underground surveys by making a closure, that he is compelled to rely on the precision of each step of his work for the accuracy of the final result. When data are fully recorded on the spot, the notes, even in the hands of second parties, become evidence of the care and precision with which the surveying was done. It is worth a great deal to be able to pick up the work of a former surveyor where it was left o$; and to be able to carry it forward without retracing from the beginning. The purpose of this paper is to describe the survey-note system of a mine now under my direction, in which underground surveys had to be relied upon entirely for the proper division of rich ore-bodies between neighbors, thereby placing a premium on accurate surveying and permanent records. In survey-work, it soon turns out that paper is the least item of expense, and that little is gained by trying to economize note-book space. For many purposes it is best to record notes on cards or loose-leaves, which may be left in the office at the end of the day's work, and need not be carried into the mine again, there to become smeared with grime and grease. With the loose-leaf or card system, all notes relating to the same local-

Apr 1, 1911

By Harold R. Kokal, Madhu G. Ranade

A metallurgical/flux is a substance that is added to combine with gangue (unwanted minerals) during ore smelting, with impurities in a molten metal, or with other additives in metal refining processes to form a slag that can be separated from the metal. Because slags are immiscible with the metallic melt and are of lower density, a separation of the slag and metal occurs if the viscosity and surface tension are of the proper values. The chemistries of slags are adjusted to provide the proper melting point, viscosity, surface tension, conductivity, specific heat, density, or chemical properties to effect the desired task. In addition to absorbing impurities from the metal, the purposes of the slag are to thermally insulate the metal bath, protect the molten metal from the atmosphere, and control the chemical potential of the system. Several excellent references on slags and metallurgical fluxes are available (Boynton, 1980, Lankford, Jr., et al., 1985, Turkdogan, 1983, Rosenqvist, 1974, Fine and Gaskell, 1984). The function of the slag might vary at different stages within a process prior to final melting. For example, the slag composition and behavior will change as materials descend in the iron blast furnace, or as they melt in the early stages of formation of steel- making slags. Selection of the chemistry for a slag might be influenced by factors outside the primary function as when blast furnace slags are used to make cement, rock wool insulation, or fertilizer supplements. Sometimes slags contain a sufficient amount of valuable recoverable elements to be sold as raw materials for other processes. Fluxes are often referred to as acid, basic, or neutral. Acid fluxes are those that generally form acids in water and bases are those that would generally form bases in water. Typical acid fluxes are silica, alumina, and phosphorus, although alumina can function as either an acid or base. Typical basic fluxes are lime and magnesia. Fluorspar, or calcium fluoride, is a neutral substance because it can be viewed as the reaction product of a base and an acid. The degree of acidity (ratio of acids to bases) or basicity (ratio of bases to acids) is often specified to characterize the slag chemistry for a particular system. The system might also be referred to as acid or basic depending on the choice of slag, for example, basic steelmaking uses slags with more bases (lime and magnesia) than acids (silica and alumina). Many forms of minerals and compounds have been used as fluxes depending on the process requirements, availability, costs, requirements for recycling of intermediate products, and environmental concerns. Because slags are most often mixtures of oxides and silicates, fluxes are usually oxides, carbonates (which decompose to oxides) and silicates. Slags comprising phosphates, borates, sulfides, carbides, or halides have also been used (Rosenqvist, 1974, Moore, 1981, Szekely et al., 1989). In ironmaking and steelmaking, some acidic components are sometimes added. In nonferrous processes slags and fluxes are acidic with silica as the primary component, and although the use of basic flux such as limestone or lime is not extensive, some amount is used to modify slag properties and some refining slags are lime based. The production of iron is accomplished by smelting of ores, pellets, and sinter in blast furnaces with subsequent refining of molten iron and scrap in oxygen-blown processes. The electric furnace is used to make steel, stainless steels, ferroalloys, and special alloys, whereas ferromanganese is often made in blast furnaces. Fluxes are used in all of these processes, and either limestone or lime is the major flux component with some dolomite, dolomitic lime, silica, alumina, and fluorspar being used. In ironmaking, the flux is added either by direct charging or through sinter and fluxed pellets. In steel refining by the basic oxygen process, flux is added as lime and dolomitic lime that are either charged as lumps or injected as fines. Some small amount of limestone is sometimes used. Fluorspar is often added as lumps or mixed with other fine materials in briquettes. Alumina is sometimes added to blast furnaces either by direct charging of sized lumps or through sinter. Typical acid fluxes are sand, gravel, quartz rock, used silica brick, or raw siliceous ore (Lankford, Jr., et al., 1985). Olivine, which is a magnesium-silicate mineral, has been added to iron blast furnaces to enhance removal of alkalis (Lankford, Jr., et al., 1985). Alumina in the form of bauxite, aluminiferous clay, and recycled alumina brick has been used as flux. Alumina can function amphoterically as either an acid or base, for example it can form aluminum silicate in high silica slags or calcium aluminate in lime-bearing slags (Lankford, Jr., et al., 1985). Limestone (calcium carbonate) and dolomite (magnesium-calcium carbonate), or fluxstones as they are sometimes called (Boynton, 1980), and their calcined forms, lime and dolomitic lime are the major basic fluxes. In the latter cases, the carbonates are de- composed in a kiln-type process to drive off carbon dioxide that might otherwise interfere with the subsequent smelting or refining process or require expensive forms of energy to effect the decomposition (e.g., by combustion of coke in the iron blast furnace). Limestone is considerably less expensive than lime because it is not calcined; however, lime is far more difficult to handle and reacts readily with water. Dolomite and dolomitic lime are used for their magnesia content. Fluorspar is a neutral flux often used as an additive in steel- making slags to improve fluidity, but it has also been used in combination with lime as a primary slag in electroslag refining (Duckworth and Hoyle, 1969). Fluorspar is available in several grades, with the lowest grade often used for steelmaking. When the price of fluorspar has risen, substitutes including aluminum smelting dross, borax, manganese ore, titania, iron oxides, silica sand, and

Jan 1, 1994

By G. Van Weert, A. van Sandwijk, O. W. J. S. Rutten

"Cathodic and anodic reactions in an acidic nitrate medium were studied in reference to the production of electrolytic manganese dioxide from pyrolusite' (Mn02) ores by reductive leaching. Two USA ores were investigated. The reductant for the pyrolusite ore is produced cathodically in an electrolytic cell and can either be nitrous acid (HN02) or nitric oxide gas (NO). In this work emphasis was placed on the nitrous acid leach. In a high-temperature leach in a nitrous/nitric acid medium, manganese and silver are solubilized and iron is not. Anodic electrowinning of manganese dioxide from the acidic manganese nitrate electrolyte yields flaky y-Mn02, similar to that produced from sulfate and chloride electrolytes. Cathodic regeneration of nitrorts acid was studied in a membrane cell in 1.0 M nitric acid and 0.0 to 0.1 M nitrous acid on a' platinized titanium cathode. At cathode potentials ranging from +950 to +700 mV (SHE), cathodic reduction to nitrous acid takes place, at cathode potentials < +700 mV, cathodic reduction of nitrous acid to nitric oxide takes place. A conceptual process is presented and discussed.IntroductionManganiferous-silver oresLarge reserves of manganiferous-silver ores are present in the Southwestern United States and Latin America. These ores are generally refractory to hydrometallurgical methods of treatment, due to the insolubility of the higher oxides of manganese (Mn 4+) in all common lixiviants such as cyanide solutions, dilute sulfuric acid, nitric acid, ammonia, salt solution, thiosulfates, etc. The silver is either bound by the insoluble manganese, or is rendered inaccessible to cyanide leach solution by the surrounding manganese mineralization.Higher oxides of manganese will dissolve if they are first reduced pyrometallurgically to manganous oxide (Mn2+). This is a widely used pretreatment for manganese dioxide ores and subsequent dissolution in sulfuric acid is common. In order to avoid the pyrometallurgical pretreatment with its large energy requirements and gaseous emissions, fully hydrometallurgical processes have been proposed. These processes are based on the presence of a reductant in solution, in order to reduce the insoluble higher oxides of manganese to soluble lower oxides. Aqueous S02 has been proposed and tested on industrial scale by the U.S. Bureau of Mines. After washing, silver could be extracted by cyanidation. The neutralization of the pulp prior to cyanidation however causes problems in filtration and the reagent consumptions are high [1]. More recently, acidified thiourea and bacteria were proposed for the solubilization of both manganese and silver in a single leach step. High extractions were obtained, but drawbacks of these methods are high reagent consumption or slow kinetics [2,3]. For the options of manganese recovery from the leach filtrate, precipitation with persulfate or ammonium carbonate and ion exchange have been proposed. The proposed options for silver reclaim are precipitation with either zinc or Na2S and adsorption onto activated carbon."

Jan 1, 1997

By Neha Shukla, Nikhil Dhawan

The current study examines the extraction of rare-earth elements from trichromatic phosphor of discarded tube lights via baking processes. The Y2O3: Eu3+ (YOX) and BaMgAl10O17: Eu2+ (BAM) phases completely decomposed during acid and alkali baking with > 90% Eu and Y extraction. Prior, selective acid leaching of the YOX phase enhanced the acid baking process at a lower temperature (< 230 ℃). Feed acid baking showed a maximum 87% Tb, 36% La, and 17% Ce extraction at 500 °C, 0.5 h, 1 ml/g H2SO4, and alkali baking yielded 16.1% Tb, 86% La, and 73% Ce at 300 ℃, 0.5 h, 50 wt.% NaOH. The acid baking of the acid-leached phosphor yielded 72% Tb, 95% La, 63% Ce, ~ 95% Y, and Eu extraction at 300 °C, 0.5 h, 1.05 mL/g H2SO4. Lower Tb extraction during the acid baking of acid-leached phosphor can be attributed to the formation of Ba3Tb( PO4)3 and BaTbO3 phases. Insoluble Si3Tb5 phase formation and partial decomposition of CeMgAl11O19: Tb3+ (CMAT) phase in the alkali baking route leads to lower Tb extraction. The acid baking process is suitable for extracting Tb, Eu, and Y, whereas the alkali baking process is suitable for La and Ce. The thermal analysis of phosphor and flux interaction depicts that alkali baking is less energy-intensive than acid baking. In comparison, the one-step acid baking process and the two-step alkali baking process yielded desirable extraction results (87% Tb, total RE (rare earth) 78.5% and 50.4% Tb, total RE 59.3%). The product yield in the acid and alkali baking route of feed, acid-leach phosphor is 36%, 29%, and 39%, 28.2%, respectively, with ~ 98% mixed rare-earth oxide purity.

May 5, 2022

By C. E. M. Meskers

End-of-life Electronic and Electrical Equipment, o_cially called WEEE, is unjustly regarded as mainly a waste management problem. What is structurally overlooked is the enormous resource impact of these devices. EEE rep- resents a tremendous metal resource, which should be uti- lized through e_ective recycling, which has a much lower environmental footprint than primary production. The actual amount of end-of-life EEE recycled today is embar- rassingly low since insu_cient EEE is collected and part of the collected EEE is exported to developing countries, where it is largely not entering o_cial recycling systems. To achieve a global recycling society issues like technol- ogy, economics, life cycle structure, stakeholder aware- ness and legislation have to be addressed in a global, co-operative manner so that sustainable closed product cycles can be obtained. Requirements for a "global re- cycling society" are de_ned to address today&apos;s reality of global ows of used consumer products, taking into ac- count the likely needs of the future.

Jan 1, 2009

I had the opportunity recently to visit a magazine site of a major explosives company. It was fun to see the storage areas again and it was really interesting to see one of the old magazines that probably dated back before my time. Now that’s an old one. As son Tom says, “When Dad was young the Dead Sea was just sick.” While the magazine has been upgraded with a modern lock to match today’s standards it still has the old tumbler lock that is opened with the large bronze key. Those old tumbler locks were just about standard on magazines years ago. Those bronze keys were heavy and would make a good display item today or maybe a substitute for a blackjack. I don’t think the old locks would stop the modern criminal but then in those days we were all less sophisticated. And maybe I shouldn’t say this but honesty was a bit more prevalent then. Maybe ‘cause old fashioned police brutality still prevailed.

Jan 1, 2004