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By Z U Bajwah

During the Palaeoproterozoic, a large number of granitic intrusions were emplaced in the various parts of the Pine Creek Geosyncline (PCG). In the central region, the granitic magmatism is represented either by the coalesced mass, eg the Cullen Batholith, or individual plutons such as the Mount Bundey Granite which together with the Mount Goyder Syenite intrude the metasedimentary strata, causing wide spread contact aureoles. Some of these granitic intrusions are temporally and genetically related to gold (and less commonly base-metals) mineralisation present in the adjacent metasediments. These plutons are characterised by the presence of biotite and homblende which appear late in the paragenetic sequence. Electron microprobe analyses of biotite and homblende show that these minerals are poorly to moderately zoned. Biotites are characterised by a decrease in Fe/(Fe + Mg) ratios when plotted against AIVI. Similarly a modest decrease in Ti from centre to the margins of the biotite crystals has also been observed. Furthermore, an increase in Mg/(Mg + EFe) ratios from centre to the margins as well as in mafic to felsic rocks is also apparent. On the other hand, homblendes from the granitic bodies display less well marked trends and are poorly zoned. However, they show systematic increases in Mg/(Mg + EFe) ratios, and decreases in Fe, Al"' and Fe/(Fe + Mg) ratios, when plotted against Si. Magnetic susceptibility measurements on powdered samples of the plutons give results characterised by high values ranging from 0.8 x 10-4 to 2.0 x 10-3 emu/g which place the granites in magnetite- series field. This indicates that the oxidation state of the magma was high during crystallisation. The range of chemical compositions of the mafic phases indicates a rise in the oxidation state of the magma as it progressively became saturated in H20-volatiles and other metals, not partitioned into the earlier crystallised phases in the final stages of magma consolidation. These variations in chemical compositions also indicate that initially fOz was high and became progressively higher during fractional crystallisation of magmas; this subsequently led to the emanation of hydrothermal fluids responsible for the mineralisation in the adjacent metasediments.

Jan 1, 1994

By R Williams, P Kohout, J Comins

The Northside Storage Tunnel (NST) is the largest tunnelling project ever undertaken in Sydney. The tunnel extends deep underground from the western bank of the Lane Cove river to the North Head sewage treatment plant (STP), with a branch tunnel from Scotts Creek connecting to the main tunnel under Tunks Park. The aim of the tunnel is to intercept wet weather overflows from four key points along the northernsuburbs ocean outfall sewer (NSOOS) and provide short-term storage and transfer of sewage to NorthHead STP for treatment prior to discharge to the ocean through the deep ocean outfall. The project was an ambitious undertaking by an alliance between the client Sydney WaterCorporationand the engineering firms of Montgomery Watson, Connell Wagner and Transfield to design andconstruct approximately 20 kilometres of tunnel, tunnel declines and shafts in just over three years. In order to achieve this tight timeframe construction of the NST has been undertaken simultaneously at seven construction sites located across the northern suburbs of Sydney. As with most tunnelling operations, tunnel boring machines (TBMÆs) and roadheaders dominated the excavation activities. Tunks Park and North Head STP are the major tunnelling sites. An access decline was excavated using roadheaders at both of these sites to facilitate tunnelling using TBMÆs. Three TBMÆs 3.8 m, 6.0 m and 6.3 m diameter) were launched from Tunks Park and one TBM (6.5 m diameter) was launched from North Head. At the overflow interception sites of Scotts Creek, Lane Cove River and Quakers Hat Bay two vertical shafts known as drop and access/ventilation shafts were constructed. These shafts would provide the linkage between the existing sewer and the tunnel. As their names suggest the drop shaft would convey the wet weather sewage overflows to the tunnel while the access/ventilation shaft would provide access during dry weather and ventilation during a filling event. The fourth overflow site of Tunks Park would use the tunnel decline as its link to the tunnel. Originally these shafts were to be excavated using the raise bore method. This technique however, is entirely dependent on the TBMÆs reaching the shaft locations at the specified time. This was not the case at two of the three shaft excavation locations and top down methods of excavation such as, a percussive cone fracturing (PCF), blind bore, mechanical excavation and drill and blast were investigated to ensure the project met its completion schedule. Traditionally project decisions are dominated by cost and schedule objectives. The contractual arrangement of the Alliance however, required that the objectives of safety, community and environment also be considered in any decision making process. Thus each of these top down methods of excavation were assessed against these five objectives. On considering all of these factors the use of explosives was considered to be the superior technique.

Jan 1, 2001

By Mauro Martins Machado

As misturadoras da UPG têm como finalidade produzir uma mistura de gases denominada HN, combinando proporcionalmente o Hidrogênio e Nitrogênio (75/25 e 5/95) para gerar a atmosfera de proteção para os fornos das linhas de zincagem, linhas de recozimento de chapas, forno de caixa e linha de recozimento contínuo de chapas. Os antigos analisadores Hidros 100 (Fisher Rosemount) e Thermomat (Fuji) que operavam nas misturadoras foram fabricados na década de 90 e apresentava baixa confiabilidade operacional, dificuldades de ajustes, falhas intermitentes de difícil diagnóstico e risco de misturas não controladas de Hidrogênio com Nitrogênio. Além disso, não possuíam mais suporte técnico do fabricante e nem sobressalentes para manutenção. Nesse cenário, este trabalho tem como objetivo apresentar a modernização desses equipamentos por analisadores atuais de fácil operação e configuração, manutenção simples e diagnóstico de falhas integrado e com maior confiabilidade, fator imprescindível para garantir a disponibilidade de produção. Os novos analisadores implantados fornecem análises mais precisas e confiáveis em tempo real, para o sistema de controle de correção da mistura do HN. Os resultados obtidos foram significativos para as atuais condições de funcionamento. Representando aumento da segurança operacional, redução dos custos de manutenção com o equipamento e gerando ganhos de produtividade e de competitividade para as áreas consumidoras na UPV.

Sep 25, 2017

By Juan Ayza

La permanente exposición y concentración de polvo en la zona minera, han sido materia de múltiples enfermedades mortales para el personal que labora en ella. Tal ese así que el polvo de sílice libre es la causa fundamental de la alteración pulmonar llamada silicosis. Por tal motivo, el objetivo del trabajo revisa las propiedades de los polvos, los medios para detectarlos, indemnizaciones y los sistemas eliminadores de los mismos. En cuanto al sistema de producción, el polvo se extiende a través de laventilación, humedad, cargas eléctricas, entre otros, influenciando en el muestreo cuantitativo y en la creación de un método cualitativo de estudio, para complementarlo.Asimismo, se determina que el desarrollo de la silicosis se relaciona en el cuarzo como causa principal de dicha anomalía, aumentando el peligro de infección y la capacidad pulmonar. Para contrarrestar dicha enfermedad se busca soluciones alternativas como el uso del agua, aceita, una ventilación adecuada, los buenos hábitos en el trabajo, la floculación, el método porofliáctico de aluminio, concluyendo que el Hematocímetro es el más exacto y práctico de los anteriormente usados, dado su costo como su requerimento de instrumental menos complicado.

Jul 20, 1955

By R. H. Jefferson

An electrochemical method to selectively determine sulfur dioxide in the presence of sulfur trioxide was investigated. A hydrophobic gas-permeable membrane separates the gas sample solution from an internal filling solution containing a fixed quantity of chloride ion and a sufficiently large excess of sodium bisulfite so that its concentration may be considered constant. Sulfur dioxide diffuses through the membrane to dissolve in the internal filling solution and liberates an equivalent quantity of hydrogen ions. The electromotive force between a precision-ground, flat-ended pH electrode, which acts as the sensing element, and a chloride sensing electrode, which acts as the reference element, gives a direct measure of S02 in the gas sample solution. Calibration curves in water, tetrachloromercurate (TCM) , and citrate buffer absorption solutions were closely parallel with slopes in their linear segments, ranging from 57 to 52 mv/decade of S02 concentration. The slopes compare reasonably well with the theoretically expected slope of 58 millivolts at 21° C. The water standard curve was linear with respect to the logarithm of S02 concentration from 1 to 1,000 ppm S02; the TCM standard curve was linear from 10 to 2,000 ppm S02; and the citrate standard curve was linear from 30 to 5,000 ppm S02' The high efficiency and nontoxicity of citrate favor it as a substitute for the conventionally used TCM in the absorption solution.

Jan 1, 1976

By R. Hogg, T. F. Dumm, L. G. Austin, M. Yekeler

"Dedicated to Professor Kurt Leschonski on the occasion of his 60th birthdayAbstractThe kinetics of batch grinding quartz from a feed of 600 by 425 Jim to a product of 80% less than 10 µm have been determined using screening and laser diffractometer sizing for size analysis. The specific rates of breakage decreased by a factor of about three when the material became less than about 100 µm in size, but the primary breakage distribution function also changed to give proponionately more fine material, so that the grinding efficiency expressed as the development of surface area (B.E:T.) per unit of energy input did not decrease. Analysis of the shape of the particles in the 2S x 38 µm size range showed that particles of this size produced by roll crushing or by 8 minutes of grinding of a 42S x 600 µm feed were not different but at long grinding times the particles were rounded. This suggests that the breakage mechanism changes to give more chipping and abrasion and less disintegrative fracture. As the material approached the ultrafine size range it adhered to the mill case and there was no further size reduction. However, a technique for striking the mill case to dislodge the particles was successful in allowing further grinding to 400Jo by weight less than 2 µm.1 IntroductionIt has long been known that it is difficult to accomplish ultrafme grinding in a tumbling ball mill. It has been reported [12, 13] that there is no further size reduction after some hours of grinding cement clinker in laboratory ball mills. Austin and Bagga (1] and Shah and Austin [16] have given an analysis of the kinetics of dry grinding in a laboratory ball mill, introducing the concept of a slowing-down factor K, which is the ratio of the specific rates of breakage at some long time of grinding to the normal specific rates of breakage. They showed that this factor decreased as fine material accumulated in the mill charge. Cottaar and co-workers [8-10] showed that the movement of solid in a dry laboratory ball mill was influenced by the fineness of the solid and by the presence of air, and that evacuation of air from the mill caused particle sedimentation and low rates of breakage.The concept of the slowing-down factor has also been used in wet grinding [17, 18]. At very .high slurry concentrations it appears to be correlated with a steady decrease of mill power caused by the build up of a layer of deposit sticking to the mill case. This reduces the effective mill diameter and, eventually, the balls start to adhere in the layer and centrifuge. A decrease of mill power always indicates less lifting and tumbling of the media and, hence, less breakage. However, slowing-down of breakage rates was also observed at lower slurry concentrations where there was no change in mill power."

Jan 1, 1990

By H. P. Holmes

Tonnage quantities of hafnium metal have been prepared in Kroll-process equipment designed for producing zirconium. Some slight process modifications have been necessary, but overall operation is the same as for zirconium. Hafnium oxide is chlorinated in the presence of carbon and the resultant hafnium tetrachloride reduced by magnesium metal. Byproduct magnesium chloride is removed in a high-vacuum distillation step and the hafnium sponge metal crushed for further use. Arc-melted metal can be forged and rolled to sheet, but the best material produced to date would not be considered cold ductile. INTRODUCTION This investigation is part of the program for the production of pure metals from domestic and foreign ores that has been underway at the Bureau of Mines for several years. It was done in cooperation with the Atomic Energy Commission and the Bureau of Ships.

Jan 1, 1955

By M. M. Fine

Normally the U. S. produces less than 10 pct of its annual manganese requirement. About 95 pct of domestic consumption is used by the steel industry.' The strategic and critical nature of manganese has been recognized by its inclusion in the national stockpile and by intensified research directed toward cataloging and evaluating domestic manganiferous deposits. The USBM has participated in these activities for many years with field and laboratory studies to assess the extent and potential utilization of domestic manganese ores. One area of particular interest is in the vinicity of Batesville, Ark., where deposits have been mined since 1849 for both manganese and ferruginous manganese ores. Production is centered in Independence County, but deposits are also found in Sharp, Izard, and Stone counties in north-central Arkansas. Miser has described the geology and manganese mineralization in some detail.'. * "he rocks of the area are sedimentary, consisting of sandstone, limestone, shale, and chert. The two formations of greatest importance,' Fernvale limestone and Cason shale, are host rocks of the primary manganese mineralization. Through 1955 the district produced some 230,000 long tons of manganese ore (35 pct Mn or more) and 236,000 tons of ferruginous manganese (10 to 35 pct Mn).5 Most of the ore has been mined from deposits of manganese oxides in residual clays resulting from weathering of the two formations noted above. Concentration methods have been primitive, consisting for the most part of washing. hand picking, and jigging. A significant accomplishment in the district in recent years was the USBM recognition and investigation of the huge manganese potential represented by unaltered Fernvale limestone. systematic reconnaissance of manganiferous limestone and other occurrences has been in progress since 1953 to delineate the extent and tonnage of manganiferous materials. Results of that survey have appeared in two recent publications,1-5 which ascribe to the district an inferred reserve of 166 million long dry tons at a grade of 5 to 6 pct Mn. Most of this was mancaniferous limestone with an estimated content of 5 pct Mn. Specifications: Beneficiation was carried out on a group of manganiferous limestones to develop a way to recover commercial-grade concentrate from this extensive resource. The following chemical specifications were established by the GSA for metallurgical manganese ore acceptable for delivery to the national stockpile: Size specifications were not considered, as it was assumed that the concentrates could be pelletized or sintered. Manganiferous Limestones: Of the 11 samples tested to date, six were taken by cutting vertical channels across beds of limestone outcrops. Diamond drilling through overlying barren chert into unex-posed limestone provided four samples, and the last was a churn drill sample. In general, the samples were dlrk, fossiliferous limestone containing small amounts of braunite, hausmannite, rhodochrosite, massive and micaceous iron and manganese silicates, quartz, barite, and glauconite. The braunite and other manganese oxides partly to completely replaced some of the calcite and fossil material. The calcite was generously stained with mangenese and iron oxides. Phosphorus was present in all samples as collophanite grains, calcium phosphate fossil replacements. or an unidentified manganese-bearing carbonate. The difficulty in separating this complex array of minerals was further complicated by a very intimate association. Although some manganese grains as large as Ik in. were noted, grinding to subsieve sizes would have been necessary to liberate the components. Figs. 1 and 2 are micrographs, at X100, of typical polished sections in which white areas are manganese. gray is gangue, and black areas are surface depressions. By comparison with the 100 mesh opening, it is seen that some of the grains are coarse enough to respond, perhaps to tabling or flotation, but many are obviously beyond the scope of ohysical processing. Partial chemical analyses of the eight samples that were ultimately amenable to concentration are presented in Table 1. BENEFlClATlON RESEARCH Tabling: To take advantage of the presence of sand-size grains, both jigging and tabling were considered at the outset. Jigging was largely ineffective, but tabling achieved a partial recovery from most samples. As an example, the surface material from Baxter Hill was crushed to —28 mesh, hydraulically classified, and the coarsest spigot fraction was tabled to yield a concentrate, middling. and tailing. The latter two were reground to pass 48 mesh, combined with the primary fines, re-classified, and retabled. The middling and tailing were again ground, this time to pass 150 mesh, and deslimed at 20µ in a 3-in. hydraulic cyclone. The cyclone underflow was returned to the table to reclaim a small amount of high-grade manganese. An interesting facet of the gravity concentration developed on certain samples in which braunite was the principal manganese constituent. Since braunite has a Mohs hardness of 6 to 6.5, while the host rock, limestone. is only 3, a differential size reduction took place during crushing, and the

Jan 1, 1960

By R. L. Stephenson

The effect of fabrication variables on the creep-rupture properties of TZM (Mo-0.5 pct Ti-0.08 pct Zr-0.03 pct C), Cb-TZM [columbium-modified TZM (7140-1.5 pct Nb-0.5 pct Ti-0.8 pct Zr-0.05 pct C)], and TZC (Mo-1.2 pct Ti-0.25 pct Zr-0.15 pct C) has been studied at 982º. 1093º, 1204º, and 1315°C for rupture times up to 1000 hr. The creep tests were performed in vacuum creep furnaces, employing cold-trapped oil-diffusion pumps, operating at pressures 2 X 10-7 tory. After-test chemical analyses showed no significant changes in interstitial content. The creep-rupture properties of TZM, fabricated according to current mill practice, were determined in the stress-relieved and in the re crystallized conditions to provide control data. Specimens of TZM, Cb-TZM, and TZC fabricated according to each of two experimental fabrication schedules were then tested. The schedules differed in terms of in-process annealing temperatures and warm -working temperatures. The data make several conclusions evident. Fabrication variables do indeed have a profound effect on the long-time creep-rupture properties of molybdenum alloys. Strengths of these alloys compare very favorably with those of other refractory metal alloys in the temperature range studied. FOR several years we have been engaged in the evaluation of the creep-rupture properties of promising refractory metal alloys. We consider the determination of these properties to 1000 hr at several temperatures necessary for a valid comparison. Such an evaluation indicated that the creep strengths of Mo-0.5 pct Ti and TZM (Mo-0.5 pct Ti-0.08 pct Zr-0.03 pct C) compare favorably with those of other refractory metal alloys. Tensile and recrystallization data of other investigators1,2 show an effect of fabrication variables. More specifically, those fabrication schedules which produce high strength through work hardening exhibit the least thermal stability. A similar conclusion was reported by perkins3 for Cb-TZM. This would lead one to expect that, in terms of creep, those materials showing higher strength at short times and low temperatures would exhibit lower strength at long times and high temperatures. If these expectations were fact, a substantial improvement could be made in these alloys by optimizing their fabrication schedule in terms of their anticipated service temperature. We therefore undertook a study of the effect of fabrication variables on the long-time creep properties of TZM, Cb-TZM (Mo-1.5 pct Cb-0.5 pct Ti-0.08 pct Zr-0.05pct C) and TZC (Mo-1.2 pct Ti-0.25 pct Zr-0.15 pct C). MATERIALS All materials used were supplied by the Climax Molybdenum Co. of Mich. Our original intention was to test the same heat of each alloy in different conditions. Fabrication difficulties prevented this; however, heats with nearly identical analysis were selected. The compositions of the materials used are listed in Table I. All materials were supplied in the

Jan 1, 1970

By L. S. Darken

It has long been recognized that the driving force in an isothermal diffusion process may be regarded as the negative gradient of the chemical potential (partial molal free energy) of the diffusing substance. This equivalence is exactly analogous to the fact that a mechanical force is the negative gradient of the potential energy. Nernstl in 1888 expressed these driving forces in terms of osmotic pressure, which is directly related to the chemical potential and free energy. The relationship between the diffusivity, mobility and activity coefficient of electrolytes in aqueous solution has been developed in great detail by Onsager and FuossZ with results which have recently been confirmed experimentally by Harned and Nuttall. This interpretation of the driving force in isothermal diffusion has been discussed earlier by the author,4,5 who pointed out4 that "for a system of more than two components it.is no longer necessarily true that a given element tends to diffuse toward a region of lower concentration even within a single phase region"; departure from the behavior of an ideal solution may be so great that the concentration gradient and the chemical potential gradient, or activity gradient, may be of different sign, thus giving rise to "up hill" diffusion. Since, in the discussion of that paper,4 some skepti- cism as to the validity of this conclusion was expressed, it seemed desirable to adduce experimental evidence to support it. Evidence of such diffusion in nonmetallic systems has already been reported. For example, it was observed by Hartley" in a series of experiments in which sodium chloride diffused from a saturated solution in about 5 pct acetone in water into a solution virtually free of salt but with essentially the same acetone concentration. Specifically, a wine glass containing crystalline salt and saturated solution was totally immersed in a large glass cylinder containing the acetone-water solution without salt; the difference in specific gravity was such as to prevent convection. Diffusion of salt was accompanied by a marked depletion of acetone in the wine glass; after 3 days the acetone concentration decreased from 5.37 pct at the top of the glass, where the salt concentration was low (0.93 pct), to 1.84 pct at the bottom where the salt concentration was high (21.64 pct). This "uphill" diffusion was found to be such that the partial pressure (activity) of acetone was essentially equalized throughout the system when a steady state gradient of sodium chloride was maintained. In order to demonstrate the existence of such diffusion in metals, a series of four weld-diffusion experiments was made. In these measurements pairs of steel of virtually the same carbon content, but differing markedly in alloy content, were welded at the end and held at 10500 C for about two weeks. Subsequent analysis showed that carbon had diffused so as to produce an inequality

Jan 1, 1949

By Jonathan G. Price

Silver-copper-lead deposits In Precambrian, Permian, and Cretaceous red-bed sequences near Van Horn, Texas, have the following features In common: (1) mineralization controlled by steeply dipping fractures in sandstones, (2) lack of ore in overlying and interbedded limestones, (3) absence of igneous intrusions, (4) sulflide ores without typical hydrothermal gangue minerals, and (5) associated arsenic, molybdenum, zinc, and cadmium but not gold. Ore was probably deposited along fractures by reaction between low-temperature, oxidizing, metal-rich ground waters and sulfide-bearing waters or rocks. Detailed mapping and studies of fracture patterns indicate that mineralization occurred during Basin and Range extensional deformation, thereby postdating major Trans-Pecos igneous activity.

Jan 1, 1984

By Morgan B. D

Since the mid 1950s, limonite deposits of a new type have been found in the northwest of Western Australia. The deposits consist of extensive fossil valley fillings up to several hundred feet in depth, of medium to high grade limonite, frequently containing limonitized fossil wood, and of Mesozoic or Tertiary age. The distribution of the deposits is closely linked with hilly outcrops of Archaean and Proterozoic jaspilite in the headwaters of the old valleys, from which the iron has been derived by leaching, and presumably re-precipitated by a process not unlike that which operates in forming bog iron deposits. Due to the relative resistance of tlie limonite to erosion, the rejuvenation of streams in the area in recent times has left limonitic remnants as mesas up to· several hundred feet above the levels of the present creeks, the courses of which generally are adjacent to or within a few miles of those of the old limonite filled valleys.The Robe River limonite deposits are the largest of this type known and can be traced for approximately 130 miles along the old stream, over 30 sq. miles of limonite remnants remaining at the present time.The present quantity of limonite in this system alone is probably in excess of 5,000,000,000 tons, and the original quantity must have exceeded four times this tonnage when allowance is made for erosion.Some thousands of millions of tons of this material contain in excess of 54 per cent Fe, with approximately 10 per cent combined water. The chief impurities are SiO2 and Al2O3, and minor elements are not present in objectionable amounts. A portion of these deposits was extensively tested by The Broken Hill Proprietary Company Limited (the B.H.P. Co. Ltd.) during 1962-1964. Most of the data presented in this paper are based on the work done on these deposits which are typical of those discussed. The overall problem of the origin of the limonite is discussed. It is apparent that the limonite originates from the jaspilitesof Archaean and Proterozoic age which form the highlands at the upstream ends of the deposits. The iron oxide has been chemically and/or mechanically derived from these jaspilites and deposited by one or more of the following mechanisms.A.-Chemical-sedimentary mainly by biological agenciesB.-Replacement of fluviatile sediments by iron-charged watersC.-Clastic sedimentary processesD.-Lateritization of fluviatile sediments.These various mechanisms are discussed; the authors favour machanismA.Manuscript received' at The Institute, 14th July, 1964.

Jan 1, 1964

By A. Sainato, S. J. Kravits, G. L. Finfinger

This report describes a project conducted by the Bureau of Mines in which the accurate directional drilling of a borehole was demonstrated with the objective of intercepting a designated target. The project was conducted at Navajo Dam in northern New Mexico at the request of the Bureau of Reclamation. Borehole survey and drill logs are provided in an appendix. The trajectory of the demonstration borehole was designed to intercept a 5-ft-radius target at the final or "punchout" distance of 885 ft. The elevation of the borehole at this distance was within the target; the borehole punchout coordinates were 8.81 ft southwest of the target. As a result of the demonstrated accuracy, the Bureau of Reclamation has contracted the accurate drilling of boreholes as long as 600 ft from the inside of a short tunnel, to control water seepage in the right abut- ment. This resulted in a substantial cost savings compared to the orig- inal plan of constructing a longer tunnel and drilling 150-ft boreholes.

Jan 1, 1987

By I. Gaballah

Decontamination of synthetic solutions of copper acetate, chloride, nitrate and sulfate containing 10, 100 and 1000 ppm of copper, using chemically treated barks has been studied. Metal percent removal from solutions depends on the pH and the initial concentration and to some extent on the salt used. It varies from 40 to 99 % of the solution initial metallic ion's content. The maximum retention capacity of the treated bark varies from 31 to 43 mg of Cu per gram of dry modified bark. Bark loaded with copper had been analysed by Scanning Electron Microscopy and lnfra Red spectroscopy. Cu is uniformally distributed in the bulk of the bark. No copper segregation is observed. It seems that copper is bound to the acidic sites of the bark. Anions are not detected on the copper loaded bark neither with the SEM or with the IR spectroscopy.

Jan 1, 1993

By C. C. Stevenson, Thomas Varley, E. P. Barrett, ROBERT H. BRADFORD

The art of treating ores by the chloride volatilization process is still in the experimental stage. The process has not been sufficiently developed along metallurgical lines to warrant a definite statement as to the exact place it will occupy in the industry. The basic theory of the process has received the attention of prominent metallurgists for 20 years, and considerable research and experimental work have been carried on. Much of the experimental work done has never been published; if the accumulated results were made known, they would greatly aid,. the further development of the process. This bulletin aim~ to bring the salient features of the process to the attention of metallurgists for the purpose of furnishing information to and receiving comments from interested parties with the ultimate hope that the process will be a commercial success. If commercially utilized, the process will fill a long-felt want in metallurgy, especially in the treatment of oxidized and semioxidized or" carbonate" ores of copper, lead, and silver. Such ores are difficult to treat by gravity concentration or by flotation: in the former their tendency to slime upon crushing and their being of lower specific gravity than the sulphide minerals cause serious losses; in the latter much has been done in sulphidizing oxidized ores and subsequently recovering the artificial sulphides by flotation. Difficulties in proper sulphidizing and the low recoveries obtained have not balanced the cost of the treatment in many plants and in very few has it proved successful. Evidently there is a big void to fill in the treatment of these ores. No radical changes in present methods are forecast, but it is obvious that chloride volatilization can have a distinct place as a method of treatment for ores that are not readily amenable to present methods. In many plants it might replace concentration methods, especially where part of the mineral content in the ores exists in forms other than sulphides.

Jan 1, 1923

By A. L. Engel

[This report presents results of investigations of problems assigned as ore-testing projects to the Ore-Dressing Section, Metallurgical Division, of the Bureau of Mines at the Mississippi Valley Experiment Station in Rolla, Mo., during the fiscal year ended June 30, 1940.]

Jan 1, 1941

By S. F. Shaw

Tars paper is a review of the principal details of cyanide practice in several of the modern plants in America, mainly during the year 1908. Two of the mills, the Goldfield Consolidated and the Vets, Colorado, are not yet prepared to give data, the former having started about Jan. 1, 1909, and the latter not yet being completed. These two mills embody most of the latest methods and are therefore described as far as possible. I. CRUSHING. The principal methods of crushing ores for treatment by the cyanide process are with gyratory and jaw-crushers, stamps, Bryan and Huntington mills, and tube-mills. The first stage is usually done by gyratory or jaw-crushers, in a few cases sup-\

Jul 1, 1909

By K. L. Paciorek

The aim of this program was to develop a reliable and meaning-ful basis for assessing certain safety aspects, namely fire and, in particular, toxicity hazards of articles employed in underground coal mining operations. The present investigation was concentrated on the thermal oxidative degradation of representative hydraulic fluids. To achieve this goal all products formed on thermal oxidative degradation of the fluids studied were analyzed, identified I and the amount of each individual species present was determined quantitatively on a weight of product per weight of material basis. The weight/weight data thus obtained can then be factorized to reflect the relative toxicity of each individual species present, using for example the Threshold Limit Values adopted by the American Conference of Governmental and Industrial Hygienists, whereby an overall "toxicity index" can be arrived at which makes it possible to compare the different fluids and/or classes of fluids in a quantitative manner insofar as their toxicity is concerned.

Jan 1, 1976

By M. Tanaji

Over the last many decades, a significant amount of research has gone into the domain of slurry transport. However, design engineers still face many challenges with respect to prediction of pressure drop, critical velocity and other design parameters as a function of Solids % and Particle Size Distribution (PSD). The industry requirement is to transfer the slurry at the maximum concentration as possible (above 30% (volume %)) to make slurry transport more economically viable and to reduce water consumption. To facilitate the design and scale-up of slurry transport in pipelines and in process plants, there is a need for a correlation that can predict slurry pressure drops over a wide range of operating conditions and physical properties of different slurries. The objective of this study is to overcome the limited range of applicability and validity of existing correlations and to develop a generalized but more rigorous correlation applicable to a wider range of slurry sys-tems. The existing Wasp et al. (1977) method is based on multi-phase flow modeling approach. This study attempts to modify this approach by considering material-specific values of Durand?s equation co-efficient and by defining flow regimes based on particle Reynolds number. When compared with experimental data, the modified Wasp method proposed in this study predicts the pressure drop for slurry flows more accurately than other available correlations. Also, the pro-posed method requires minimal test/experimental data for a particular slurry system and can be extended over different input conditions. An iterative computer algorithm is developed to calculate the criti-cal settling velocity and pressure drop in a pipe as a function of Solids % and PSD. The solution method can easily be implemented in de-signing slurry pipes, design validation, and studying the different slurry transport scenarios. The modified method can also be extended to accurately predict pressure drops in dynamic pressure flow networks used in commercial process simulators.

Feb 23, 2014

CHARLES H. MACDOWELL F. V. DESLOGE CHAIRMAN OF CHICAGO CHAIRMAN OF ST. Louis SECTION SECTION R. J. GRANT F. W. BRADLEY CHAIRMAN OF COLORADO CHAIRMAN OF SAN FRANCISCO SECTION SECTION

Jan 7, 1919