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As a result of the world depression and the consequent heavy fall in the price of tin, Malaya joined with other great tin producing: countries of the world in a restriction scheme that heavily restricted production from its individual mines. This condition, together with the knowledge that it was becoming more and more difficult in, Malaya to acquire further areas and so prolong the existence of a specific company's activities, induced Mr. H. G. Scott, managing director for the Siamese Tin Syndicate Ltd., to consider other possible sources of production. Mainly because of the conditions that obtained in Tasmania, he turned his attention to that country, where, not only could mining be carried on without restriction as to output, but where the incidence of the exchange position created favourable conditions for operation. The district selected for examination was that of St. Helens, on the East Coast of Tasmania, which district had behind it a long record of successful tin mining operations.PRELIMINARY OPERATIONS OF SIAMESE TIN SYNDICATE LTD. AT ST. HELENS.First of all the district was examined, and there was no lack of evidence to show that tin existed, although it was impossible to get down to quantities and values without an extensive prospecting campaign. For one thing, the physical features of the country seemed to be all wrong. There were no extensive alluvial flats such as a mining engineer...

Jan 1, 1934

By P. Chiotti, J. T. Mason

Metallographic, thermal, X-ray, and vapor-pressure data were employed in establishing the Ce-Zn phase diagram. Nine compounds and three eutectics were observed. The eutectic compositions in weight percent zinc and temperatures are 10 pct and 495"C, 37 pct and 795°C, and 56 pct and 810°C. Three of the compounds, CeZn, CeZnn, and CeZne.5, melt congru-ently at 825°, 87.505°, and 980°C, respectively; the other six compounds, CeZns, CeZns.67, CeZn4.5, CeZn5.25, CeZn,, and CeZnll, decompose peritectically at 820°, 840°, 870°, 885", 960°, and 795"C, respectively. The compound CeZn5.25 is an AB5 type with a small range of composition which lies on the zinc-rich side of the 1 to 5 stoichiometry. Zinc vapor-pressure data obtained by the dewpoint method were employed in calczilating the thermodynamic properties of both the liquid alloys and solid compounds. The data for the A critical review of the information available on the Ce-Zn system up to 1960 has been given by K. Gschneidner, Jr.' Of particular interest is the work by J. schramm2 who investigated the region between 55 and 100 wt pct Zn and reported a CeZn,, compound which decomposes peritectically at 785"C, a CeZn, compound which melts congruently at 972"C, and five temperature horizontals at 79@, 817", 840", liquid alloys were fitted to the relation from which the relation was obtained by integration. In these relations F XS is the excess partial molal free energy, N is atom fraction, and the constants c and d have the values c = (-22,000 + 7.0T) and d = 6171,000 + 74.0T). Relations for the standard free energy of formation for the solid compounds were derived from the data. At 973°K the enthalpy in kilocalories per gram-atom z)aries from —11.3 for CeZnz to —8.21 for CeZn~l and the free energy in the same units varies from —7.1 joy CeZn, to -3.82 for CeZn11. and 942°C in the region between 55 and 75 wt pct Zn. No attempt was made to identify other features of the system. I. Johnson and R. yonko3 used a fused-salt cell to measure the electromotive force between pure cerium and an alloy consisting of zinc-rich liquid in equilibrium with CeZnll. Solubility data for cerium in zinc has been reported by J. Knighton et u1 .4 Johnson and Yonko give the following equa-. tions for the mole fraction of cerium in zinc and the standard free energy of formation of CeZnll:

Jan 1, 1965

By Penrose E. K

With the exception of occasional periods, when up to 80% of oxidized ore was treated, the G.M.K. plant treated all sulphide ore until October, 1939. The treatment was, briefly, as follows:The ore was ground to approximately 17% plus 200 mesh Tyler and agitated in cyanide solution, after straking. After agitation, the pulp passed through two stages of counter-current decantation washing in Dorr thickeners and was filtered once, to complete the precyanidation stage.The precyanide filter cake was repulped with flotation circuit solution and floated in a Denver Sub A flotation machine, consisting of twelve cells. The concentrates were roasted, cyanided and filtered four times before disposal to the' dam. The flotation tailings were thickened to conserve water and pumped away to a separate dam.The average results of flotation operations for the six months before October, 1939, are shown in Table 1.

Jan 1, 1942

By X. Yu

Although many investigations of the deformation behaviour of rocks have been carried out, most of them are carried out in compression. In all rock engineering practice it is usually assumed that the deformation of rocks in tension is the same as that in compression. However, data from numerous researchers have shown that this assumption is not correct for some rocks. A new loading frame for testing rocks in compression and direct tension has recently been developed by the authors, with the capacity to conduct both compression and tensile tests on the same rock sample. The results obtained show that the ratios between the average Young?s modulus in compression (ECA) and in direct tension (ETA) are 1, 1.16, 2 and 6 respectively in four rock types tested. For Poisson?s ratios, analogous relations were obtained. It was observed that, in all cases, the tangent Young?s modulus intension reduces with an increase in the applied tensile stress, while the behaviour of Poisson?s ratio is similar, but shows greater variability. The difference between the Young?s modulus of rocks in tension and that in compression could lead, large errors in calculating induced stresses around underground openings, as well as in determining the Brazilian tensile strength of rocks. This may have a significant influence in rock engineering and therefore more investigation is necessary into the tensile deformation behaviour of rocks and its influence.

Jan 1, 2005

By Tianjiao Luo

The electroless copper plating process for continuous carbon fiber using CuSO4?5H2O as the main salt and formaldehyde as reducing agent was experimentally studied, including the effects of pH values and concentration of chelating agents, stabilizing agents and reducing agent on the electroless plating process. The surface morphology and the composition of coating were investigated by means of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), and deposited the coating thickness was measured by way of dissolution. The results indicated that the pretreatment of carbon fiber before plating was so important. This pretreatment could prevent the formation of the black cores, furthermore, it could form many active absorption cores with Ag as the center on the carbon fiber surface. Used the optimized parameters in this process, which led to a stable solution for plating, a homogeneous copper coating was conducted with the carbon fiber plated with favorable mechanical performance and high adhesion strength.

Jan 1, 2006

By Beatriz Lemos Clemente

A maneira com que acontece a nucleação interfere diretamente na forma dos contornos de grão e também nas propriedades do material em questão. Para visualizar melhor, pode-se utilizar uma célula cúbica, na qual é possível notar que em cada eixo há diferença de textura e densidade entre os grãos já desenvolvidos. Neste trabalho, foram empregadas duas vias de estudo a fim de obter os resultados desejados. A primeira delas é a nucleação homogênea dos grãos e a outra, a nucleação não homogênea, ambas com velocidade constante. Esse fenômeno pode ser visto durante a recristalização de grãos. Rios e Villa [6] criaram um método efetivo para analisar a cinética das transformações homogêneas e não homogêneas a partir do método de JMAK[1-5]. Para comparar método analítico foi desenvolvida uma simulação computacional com base no modelo analítico Rios e Villa [6], foi utilizado a metodologia do Cone Causal (método estocástico). Os gráficos gerados confirmam a teoria de Rios e Villa [6] para esses casos particulares e comparam os resultados obtidos com o conceito de JMAK [1-5].

Oct 30, 2017

By P. Zhang

A multiyear, comprehensive study of flotation reagents used in phosphate beneficiation was conducted. The study involved the evaluation of pure fatty acid compounds, comparison of various anionic collectors and testing of iso-acids. Various C12 to C22 fatty acids were tested as Florida phosphate collectors. The saturated fatty acids were found to be very poor collectors when using the standard conditioning procedure, whereas the unsaturated C16 to C22 fatty acids showed fair to good phosphate collecting ability. The C18 fatty acids oleic, impure oleic and linoleic and the C20 eicosenoic acid were shown to be the best phosphate collectors. The best flotation results were obtained using Liqro GA tall oil and oleic acid. Four isostearic/iso oleic acid type fatty acid collectors were compared with a commercial grade oleic acid and with Liqro GA tall oil as phosphate collectors using standard laboratory conditioning and flotation procedures. The most selective collector evaluated was Century 1108, a high isostearic acid-type reagent. However, it was concluded that this excellent-performing reagent was too expensive for commercial use. Overall, the most promising reagent was probably Century MO-5. This collector is essentially an iso-oleic acid/stearic acid mixture (not isostearic acid), and it costs much less. This program laid a sound foundation for developing single collector, all anionic flotation processes.

Jan 1, 2009

By Roger A. Bullivant

As the UK's foremost domestic foundation underpinning contractor over the last 25 years it has become abundantly clear that the size of the repair market, some £500m per annum is a significant waste of resource and cost. To experience this scale of foundation failure in mainly new construction less than 20 years old is unacceptable. This is being further endorsed by our contracting experience in the USA over the last 10 years. Our foundation repair systems are mainly based upon the use of driven mini piles and it was considered appropriate that this type of pile should be upgraded and used on new build construction where the ground was marginal or bad.

Jan 1, 1995

By Keet B. A, Waid J. S

The Gippsland Basin is one of Australia's most important producers of petroleum products. An inevitable byproduct of the production, refinement and transport of the millions of barrels of oil is thousands of tonnes of waste. These wastes are generated from the wellhead through to the petrol bowser and range from oily brines and coal tars to oil and petrol contaminated soils. The vast majority of these wastes are of a relatively low toxicity and most importantly are carbon-based and biodegradable. Current disposal practices tend to ignore the latter characteristic and inappropriate and/or expensive waste disposal solutions such as landfilling (tipping), incineration or ocean outfalls are the result. A very cost effective and environmentally friendly alternative is land treatment of such wastes. Landfarming, as it is called, has been successfully practiced in Europe for over a decade. Essential features of the system are: ò Application of a predetermined quantity of biodegradable waste in liquid, sludge or highly contaminated soil form, to pre-ploughed soil with concurrent addition of nutrients (N, P and trace elements) and lime to encourage bacterial activity. ò Harmless bacteria already present within the soil break down the carbon-based compounds into carbon dioxide, water and waste heat, WHILE concurrently generating new cells. The breakdown occurs over a period of weeks to months and continues with time with the extremely low levels of the more difficult waste types being the last to disappear. ò Further waste is applied to the soil at regular intervals. The treatment area may be dedicated to landfarming or may be used alternatively for agricultural purposes. Application rates vary but may be as high as 800 tonnes per hectare per year for wastes such as refinery sludges.

Jan 1, 1992

By B. J. Schat, A. W. O. Bots, O. S. Langhorst

Amsterdam City Council is building a new metro line, the North–South Line. The line passes under Amsterdam Central Station (a listed building) about 18m below street level. The retaining wall that has to be built underneath the existing building is an innovative construction consisting of two rows of steel piles interspersed with a solid mass of overlapping jet grout columns: a composite ‘sandwich’ wall. This paper gives an overview of the approach taken to designing (computational models) and building the retaining wall. Special attention is paid to the observational method used for the construction of the jet grout columns.

Jan 1, 2007

Mining companies in order to compete and succeed in being viable business propositions must look to the future and select mining methods which guarantee improved efficiency and productivity as well as lower costs. A mining company in adopting a method of mining must now select the equipment most compatible. To some mines compatible equipment may mean the use of drilling jumbos to replace hand held rock drills or the use of load haul dump units to replace scrapers. To other more mechanised mines compatible equipment may mean the use of raise borers and road heading machines. The right decision will be where equipment compliments method in such a way that the working environment is improved, productivity is maximised, cost if reduced and all profit opportunities are optimised. An example of such is where the use of improved mining techniques in underground operations may see cut off grades reduced. By selectively mining these lower grade orebodies, smaller operation's ore reserves improve and the capacity for continued growth is enhanced.

Jan 1, 1990

A detailed study of the capital investment and production cost for copper electrowinning plants shows that significant savings in both can be achieved by increasing the current density. From the economic analysis it is determined that the optimum current density which will result in lowest capital investment and lowest operating cost is between 60 A/sq. ft. and 70 A/sq. ft., or at least three times as high as the Conventionally employed current density. The specific investment, expressed as $/ton-year, is found to be a function of both the current density and plant capacity and has a minimum value at the optimum current density. Empirical equations are developed for the purpose of estimating the capital investment and operating cost for plants of any production capacity operating at any current density.

Jan 1, 1972

By Lifeng Zhang

Printed circuited boards contain considerable quantities of valuable metal, while also containing many environmental pollutants making them unsuitable for landfill. In this study the decomposition of common plastics used in printed circuit boards were studied. Polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC) and polyethylene (PE) were heated in both C02 and argon atmospheres using a thermo-gravimetric furnace (TG) coupled to a mass spectrometer (MS). Soda ash Na2C03 and baking soda NaHC03 were used as reactants. The degradation temperatures and evolved gases are presented for single plastics and mixtures. Mixed plastics are shown to behave as a sum of the individual plastics. The mass loss temperature is the same in CO2 and argon. However, less residue is formed when heated in CO2.

Jan 1, 2008

The Peelwood district of New South Wales is located some 65 miles south of Bathutst on the Tuena-Crookwell road. A number of occurrences of lead-zinc-copper ore are known from this district but only three mines, Peelwood, Cordillera and Mt. Costigan, have achieved any significant production. The purpose of the paper is to describe the mineral composition of sulphide ores from these three localities.HISTORYNo published information on the geology of the Peelwood area is available. Came (1899) reports that, at the time of cessation of mining operations in 1888, the Peelwood mine had produced some 600 tons of copper metal and regulus, the Cordillera mine had yielded 9000 tons of ore at the recoverable grade of 2·5 per cent Pb, 2·5 per cent Cu, 90z/ton Ag and 1 dwtjto:p. Au, but that no production figures were available from Mt. Costigan. No further work was carried out on these properties until 1951 when the Electrolytic Zinc Company of Australasia instigated a programme of geological mapping and exploratory diamond drilling (Whitten, unpublished data, 1953). The Peelwood district was recently mapped by Mutton (unpublished thesis, 1960) from whom the following geological summary account was taken.GENERAL GEOLOGYAll rocks in the Peelwood area belong to a series of interbedded fine grained sediments and volcanics that are thought...

Jan 1, 1961

By Tae-kyeong Yeu, Jong-Choi, Cheon-Hong Min, Hyung-woo Kim, Jae- Won Oh, Sup Hong, Minuk Lee, Sung-Soon Kim, Chang-Ho Lee, Ki-Young Seong

"Collecting mineral resources from the seabed using a seafloor crawling robot is the firststep in the mining operation. The second-step is lifting the collected ore up to the water surface. For lifting through a riser pipe, prevention of pipe clogging (flow assurance) and economic and eco-friendly up-transferring is of the utmost concern.During collection of mineral ores, the production rate can be highly variable because of the variability in the distribution of the mineral deposit, variations in seafloor topography, fluctuations robot speed, and variations in performance of the mining robot, etc. Direct transfer of the collected ore to the riser pipe might cause unpredictable and serious problems such as over-loading of the lift pump, reduction in the life of the equipment, pipe clogging, severe increase of down-time, critical damage of equipment, further propagation of damages, and total failure after all.As a counter measure to these potential problems, a buffer station has been adopted, which is capable of storing the collected ore for a certain time and simultaneously regulating the transfer of the ore into the riser pipe. A pilot buffer has been developed by KRISO/KIOST (see Fig. 1)."

Sep 1, 2014

By Daniel W. H. Su

The importance of incorporating fundamental principles of rock material response and failure mechanics into a pillar strength design model has been demonstrated. To accurately assess pillar strength, a model should account not only for the characteristics of the coal, but also for those of the surrounding strata. The interactions between the pillar and the surrounding roof and floor dictate ultimate pillar strength. Confinement, or the lack thereof, provided by roof and floor frictional end-constraint is one of the most significant factors in the strength of very wide pillars. The best conditions for end-constraint occur with ideally strong roof and floor. In this paper, it will be shown that weak roof and floor may decrease the ultimate pillar strength by as much as 30% compared to ideal conditions. Field observations confirm this pillar strength reduction in the presence of weak roof and floor. Furthermore, rock partings within the coal have a variable effect on pillar strength, depending on the parting strength. A competent shale parting within the coal reduces the effective pillar height, thus increasing the ultimate pillar strength; a weak claystone parting slightly decreases the strength. Imposed load distribution also has a significant effect on pillar strength, such that asymmetric pillar loading, similar to that observed in pillars adjacent to high extraction mining, reduces the ultimate pillar strength below that of equivalent pillars subject to uniform load distributions.

Jan 1, 1997

By W. Tom Witherspoon

Many Engineers are skeptical and cautious about skin friction factors for the portion of drilled piers where temporary casing is used. This has led Texas engineers in many cases to eliminate skin friction values for the cased section, which necessitates deepening the drilled shaft to compensate for the loss in the cased section. This paper has provided field test data that supports inclusion of skin friction in the temporarily cased hole section as a contributing factor in total axial capacity as comparable to open hole shafts of the same diameter. Reasons for the resultant friction values are provided including; remolding of the cased clay section and the increased pier circumference necessitated by the oversized casing required for adherence to the engineers shaft diameter specification.

Jan 1, 2009

By K. Moxham, R. G. B. Pickering

Over the last few years Lonmin Platinum and Sandvik have embarked on a unique partnership of collaboration through a systematic approach to developing equipment to mechanize and automate narrow reef platinum mining. After the initial design and manufacture of the equipment the key aspect is the integrating equipment, people and method into a mining system. Another key a spec of mechanization is the optimization of equipment utilization and this philosophy has ensured continual evolvement of mining methods. This paper describes the trials and development that have resulted in the mining method described as Lonmin mechanized breast.

Jan 1, 2006

Development of a permanent human base on the Moon for exploration requires a self sustaining system. This entails production and processing of limited amounts of raw material on the Moon. Any mining and construction activities on the Moon can only be performed by a robust excavation machine that can excavate a variety of material from loose surface regolith to consolidated (frozen) regolith with embedded rocks in the mixture. Meanwhile, limited amount of information on lunar regolith is available to develop and optimize a machine for given lunar ground conditions. Therefore, any excavator designed for use on the lunar surface should have the ability to adapt to a wide range of operating conditions. A prototype cutterhead for the lunar excavator was built and tested at the Kennametal facility in Latrobe PA A. This paper discusses the results of initial material characterization as well as full scale tests of a prototype cutterhead inrelevent material. A brief review of anticipated production rates under various assumed ground conditions will also be presented.

Jan 1, 2009

By J. R. Hoskins

Method - A direct approach to instrument users, initially by letter and later by telephone or personal contact was made. The resultant data was compiled to give specific use information on the seven instruments. During the course of the study attempts to evaluate the Griswold Gage were abandoned when it became apparent that the gage was not being commercially produced. One company is developing the gage for its own use. The information presented is the result of over 1200 inquiries.

Jan 1, 1973