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By A. J. Davidson

A Cu-conducting solid electrolyte was used to develop the sensor. Instead of measuring the potential across the electrolyte from the reference material to the Cu-containing phase, a potential was applied and the stable current measured. This gave reasonable readings for copper-tin alloys, which agreed with the theoretical calculations, but was less satisfactory in the case of mattes because the surface area of electrolyte presented to the matte phase varied from sensor to sensor. To overcome this problem the potential was applied, the current was measured and then reversed and remeasured and the ratio of the currents was calculated. The current ratio is shown to be independent of the resistance of the electrolyte and the surface area of the electrolyte offered to the melt, but strongly dependent on the activity of the copper

Jun 21, 1905

By Jochen Belz, Allan Henneker, Nod Clarke-Hackston

For the construction of tunnels and other underground structures, extraction of the exact amount of material is of paramount importance both economically and for engineering purposes. In the Sequential Support Method (NATM) immediate (sequential)and smooth support by means of shotcrete, steel arches, lattice girders and rockbolts, either singly or in combination are used; cutting of the precise (albeit sometimes of complex geometry) profile is an integral part of the method. In order to save unnecessary excavation and provide better information to the machine operator, VMT GmbH has developed a system to support precise excavation of the tunnel profile when using road headers or other partial face cutting machines. This paper outlines the principles of this system with examples from Australia, Ger-many, Sweden and Spain and will cite examples of typical savings achieved.

Jan 1, 2007

Syncrude Canada produces a large part of Canada’s crude oil supply. The company processes about 225,000 bbl/day. The oil produced is used for jet and automobile fuel, home heating oil, plastics and other consumer synthetics. Crude oil is produced through a process of mining, extracting and upgrading bitumen. A rich supply of bitumen is contained in the Athabasca oil sands deposit in northern Alberta. Tailings from the bitumen processing are sent to a settling basin.

Jan 1, 2000

By Silas C. Nichols

"Abstract Piling and deep foundations are a staple for transportation projects in the United States (US). Driven or bored piles have been used for everything from support of bridge foundations and retaining structures to support of culverts and embankments on soft ground. Deep foundations have been popular in the US transportation market to better handle large axial and lateral loads, extreme event loading, and to better control structure movement. However, there are challenges in the maintenance of design and construction codes in transportation for consistent and reliable structure foundation elements. A significant amount of effort continues in the US to maintain national codes and specifications at a level consistent with the state of practice, and identify and conduct research for providing safe and cost effective highway structures.IntroductionThe transportation sector in the United States has a hierarchy of design and construction codes that are used for the specification of piling and deep foundations. Any highway or bridge project on the National Highway System (NHS) must be designed and constructed in accordance with a national set of standards approved by the State Highway Departments, and that are acceptable to the Federal Highway Administration (FHWA). However, in any jurisdiction, exceptions are permitted with approval. Therefore, design may be governed by the national standard specification, a state standard specification and design manuals, special provisions, or guideline specifications. Any of these standards, or a combination, may be used depending on the needs of the owner agency.The FHWA and the American Association of Highway and Transportation Officials (AASHTO) have worked together in the development and maintenance of geotechnical design and construction guidance and codes that support the surface transportation community. General geotechnical engineering practice in the United States lacks a singular, national design and construction code that addresses all aspects of geotechnical engineering. As a result, the AASHTO specifications provide the most complete geotechnical specifications focusing on structure foundations, retaining walls, and buried structures for surface transportation applications. This includes piling and deep foundation types commonly used for support of bridges and transportation structures.The FHWA National Geotechnical Team has published several technical guidance documents that include guideline specifications for the design and construction of driven and bored deep foundations. Reference documents published by FHWA summarize the state of practice and provide recommended design and construction guidance. These reference documents have long served as a basis for provisions included in the AASHTO specifications. Maintenance of the design code and specification, and related guidance documents for consistent use on US transportation projects requires a collaborative effort between industry, FHWA, and the member state highway departments that make up AASHTO."

Jan 1, 2014

By Jocelyn Bouchard, Claude Bazin, Sami Makni, Rolando Quispe

"Finely disseminated minerals in ores require intensive size reduction to achieve sufficient liberation for the subsequent concentration process. The use of small grinding media in conventional ball mills as a replacement for the usual 2.5 to 3.8 cm balls (1.0 to 1.5 in) produces a finer size distribution at a lower power drawn by the mill motor. However, the conditions ensuring a successful application of using small media for fine grinding are still not fully understood and some plants faced issues to keep the newly introduced steel charge inside the mill during industrial trials. The retention conditions of small media are investigated in this paper using a continuously operated 40 x 40 cm laboratory grinding mill. The tests assess the effect of the steel charge level, the slurry solids concentration and the feed rate on the rate of ejection of the grinding media. The dominant variable is found to be the filling of the mill with the grinding media, followed by the mill feed rate. Results show that increasing the slurry solids concentration within a grinding mill may be favorable for the retention of the media inside the mill.IntroductionProcessing of complex ores often requires the use of fine grinding to liberate finely disseminated minerals. Grinding requirements for a P80 of less than 0.02 mm are not uncommon, and different grinding mills are available for such application (Leonida, 2014; Pease et al., 2006; Davey, 2006; Orford et al., 2006; Nesset et al., 2006). Even conventional horizontal ball mills charged with of 2.5 cm or larger grinding media can be used for fine grinding. However, simulation (Orford and al., 2006) and plant observations (Alves and L-Bouchet, 2005; Brisette, 2010; Brisette and Roman, 2012) demonstrated the advantages of using smaller grinding media in terms of size reduction and energy consumption."

Jan 1, 2015

By P S. Jaitawat, M Sarim, M P. Roy, P K. Singh, A Joshi

Mining is being carried out using the sublevel open stoping method at the Kayad underground mine. The mine will ultimately reach a depth of 390 m. Kayad village is only 100 m (horizontally) from the underground mining areas. As a result, blast-induced ground vibration is one of the major issues for the residents of the village. This paper deals with the process involved in optimising blast design parameters at the development face blast, slot raise blast and ring hole blast to control blast-induced vibration within safe limits while ensuring improved production, productivity and safety. In total, 1041 development face blasts, 110 slot raise blasts and 52 ring hole blasts were conducted, and 2612 vibration data were monitored in the village at different locations. Initially, electronic delay detonators were used, with an emphasis on controlling vibration in the surface structures. Subsequently, shock tube (Nonel) initiations were used as the blasting faces reached lower depths. A comparative study was also performed for both the initiation systems. The orebody width generally varied from 3.1 to 7 m, and ring hole designs were optimised accordingly. The number of holes in a ring was up to seven and the depth was up to 23 m, depending on the size/width of the orebody. The ring blasts were performed with 64–340 kg of emulsion cartridge explosive and detonated with explosive weight per delay of 10.92–17.16 kg. Extensive experiments were performed and blast-induced vibrations were controlled in the village. Deck blasting (ie up to four explosives decks) was used in a blasthole and the explosive charges were separated by delay detonators, which helped to control the vibration in the village. The actual detonation time of each deck was recorded by monitoring the in-hole velocity of detonation of the explosives, and the charging patterns were optimised accordingly to get the desired blast results.CITATION:Roy, M P, Singh, P K, Sarim, M, Jaitawat, P S and Joshi, A, 2015. Blast design and vibration control at Kayad lead-zinc underground mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 533–544 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Nathaniel Arbiter

Flotation’s earliest patent was issued in 1860. However, the process was first applied commercially in Australia until 1904, and in Montana in 1911. Major advances followed both in reagent treatment and in cell design, with resulting process improvements. Mechanical cells have seen the widest use and with the major increases in plant capacities (Fig. 1) their volumes have also increased (Fig. 2). In 1991, the principal use for the process was to produce copper concentrates for smelting. It was applied to 243 Mt (268 million st) of copper ore. The total of all ores floated that year was 426 Mt (470million st). In 1997, US mines produced 257 Mt (284 million st) of copper ores for flotation, yielding1.75 Mt (1.94 million st) of copper.

Jan 1, 2000

The Porgera Joint Venture commenced production during September 1990. A small tonnage underground mine extracts high grade gold ore using small scale stopes. Conventional drill and blast methods are used for development and production mining. Ground support is effected with Splitset anchors, grouted rebar bolts and grouted cable bolts. Splitsets and grouted rebar can be installed by mechanised means. Vertical crater retreat, slot and massfire, and modified VCR stoping tech- niques are used at Porgera. Stopes are backfilled with a relatively strong cemented rockf ill. Future stope sequences require recovery of pillars beside and under filled stopes.

Jan 1, 1991

By David C. Kraft

Helical piles and ground anchors were used to meet critical design and constructability requirements for an urban forest Canopy Walk at the Atlanta Botanical Garden, Atlanta, GA. The 12-foot wide pedestrian walkway path was to be nestled among the treetops of a forest, extending to 600 ft. in length, and soaring 40 ft. high above the forest floor. Of particular concern during construction was that the foundation system for the temporary steel shoring system had to be non-invasive to the subsoil, could not damage the forest floor, trees, root systems, or foliage, and upon completion of the concrete walkway pour, could be removed, again without disturbing the subsoil. Accubrace, Inc. designed and installed all the helical foundation types, as well as provided steel braces, typically used in Tilt-Up building construction, for the walkway project. The braces, some extending to 43 ft. in length, were used to provide lateral support against wind loads for the walkway form. In addition, the braces acted as secondary support for lateral loads during the placement of wet concrete along the 600 ft. length of the walkway. Helical foundation products installed included vertical compression piles, ground anchors for tension rods, and ground anchors for the braces. The installation of the piles and anchors was particularly challenging since the forest floor elevation varied as much as 50 ft. due to the presence of a ravine. Information is provided on the subsoil conditions, required loads, design, installation, and acceptance criteria for each helical product type installed for the project. The results of vertical and lateral load tests on the helical piles in the pre-construction phase, conducted in conformance to project specifications are presented. Photographs to illustrate the nature and complexity of the project are included. The concrete pour for the walkway was successfully completed on December 12, 2009, and the walkway was opened for visitors in May, 2010.

Jan 1, 2011

Models are used in engineering to reproduce reality as faithfully as possible so that the expected response of a system for given actions or inputs can be determined. In the field of rock engineering, both empirically based and numerical models are widely used to determine the likely response of the rock surrounding excavations. Many of the empirical models are developed from statistical analysis of case histories or from direct observation; however, empirical models are limited because they should be used only within the range of conditions of the observational database. Synergy exists between empirical and numerical models, because empirical models can be used to calibrate and validate numerical models. The empirical approach can benefit from the capability of numerical models to investigate specific mechanisms, which would not be possible using observations alone. Two cases are presented in which the synergy between empirical and numerical models is demonstrated. The first case examines the analysis of discontinuity effects on the strength of slender pillars in limestone mines, and the second case evaluates the effects of stress orientation on coal mine entry stability. It is concluded that numerical model calibration and verification comprises an important first stage in the successful application of models in rock engineering design. Application of numerical models allows mechanisms and interactions of various parameters to be analysed, greatly improving the understanding of the system. The improved understanding can be used to extend the application of empirical design methods, resulting in improved safety and efficiency of rock engineering designs.

Jan 1, 2014

A hard lump char containing only 4 to 5 per cent ash, 0·25-0·30 per cent sulphur and a trace of phosphorus has been produced from Latrobe Valley brown coal by slow drying and carbonization of ordinary industrial briquettes at temperatures between 7000 C and 14000 C. The briquette char can be made with a variety of reactivities by varying the maximum temperature of carbonization; the higher the temperature, the lower the reactivity. The strength of the fuel compares favourably with metallurgical coke made from black coal, though it may not be quite so resistant to abrasion. Experiments in a small experimental cupola indicate that it will make a satisfactory fuel for use in iron foundries. It may also find extensive application as a smokeless fuel in other branches of industry and in household heating appliances.INTRODUCTIONVictoria, like South Australia and Western Australia, is apparently without 'significant deposits of black coal of coking quality but there are huge reserves of brown coal of high moisture content (60-66 per cent) in the Latrobe Valley (well over 20,000 million tons have been proved) and there are other important deposits in the south central portion of the State (Herman, 1952).For three decades Victorian industries, including a few metallurgical firms, have been using the briquettes made at the Yallourn factory of the State Electricity Commission of Victoria (S.E.C.). These briquettes, having a moisture content of about 15 per cent and a calorific value of approximately 9,500 B.T.U. per pound, are satisfactory for certain grate-type furnaces but they are not suitable for use in cupolas of other shaft furnaces because they disintegrate badly on rapid heating.

Jan 1, 1956

By Miezitis Y

A weak airborne radiometric anomaly was examined in the field and the presence of uranium confirmed. Rotary-percussion drilling showed the presence of uranium but a subsequent programme of diamond and rotary percussion drilling indicated that the concentration of uranium was uneconomic. Within the tufts and volcanics of the prospect the uranium existed as uranyl phosphates within the oxidized zone. Geological mapping and the diamond drill core showed that the Stag Creek Volcanics are part of the Lower Proterozoic Masson Formation, probably with member status, rather than the expression of an Archaean basement ridge. This change in the interpretation of the fundamental structure of the Pine Creek Geosyncline has led to a reexamination of the stratigraphy and to suggestions which differ from the current concept.

Jan 1, 1977

By N. Fragen, H. H. Stroch

"INTRODUCTION A previous paper by H. H. Storch 4 described. three processes for the production of potassium sulphate from polyhalite (K2S01.MgSO1.2CaS04.2H2o), Since these processes depended upon calcination of polyhalite followed by leaching with water at 100°C., the fundamental reactions occurring in these steps were discussed in detail. This paper, which describes processes producing syngenite (K2S04.CaSO4.H2O) and potassium sulphate and gives data concerning the production of by-product magnesia, presents the results of work performed at the Non metallic Minerals Experiment Station of the U. S. Bureau of Mines, maintained at New Brunswick, N. J., in cooperation with Rutgers University.A study of the solubility relationships of the system 5 Ca++ -Mg++ -K+-SO4 = H20 at 25ºC. shows that syngenite is stable in the presence of a concentrated MgSO4 solution, the K2SO : equilibrium concentration being comparatively low (2.6 per cent), The processes described below, which involve the conversion of calcined polyhalite to syngenite, are based on the 25°C. equilibria. It has further been found that syngenite can be decomposed by water at 100ºC, yielding a 9 to 10 per cent K250 solution, the solid phase being potassium calcium pentasulphate (K2SO, 3CaSO.H2O, hereafter referred to as ""pentasulphate""). This latter compound is unstable in the presence of water at 25°C., its decomposition resulting in a solution containing about 3 per cent of K2SO4 and a solid phase consisting of gypsum. This behaviour of syngenite with water at 100°C. and of pentasulphate with water at 25ºC. constitutes the basis of processes for the production of K2SO4 by way of the conversion of calcined polyhalite to syngenite,Syngenite is a product which may be used as a fertilizer per se. As produced in the process to be described, it contains about 50 per cent of K2SO1, and will readily give up its potash content on treatment with water, although the limiting concentration at ordinary temperatures is approximately 3 per cent. This definite but limited solubility should make this product more desirable as a fertilizer then the more concentrated forms of potash salts which have higher solubilities and hence involve the danger or plant injury due to a high local concentration of potash."

Sep 1, 1931

By A. B. Hooker, L. C. IlsLey

"Observation of the use of trailing cables in ""mines shows that the chief limiting factor in the life of the cables and their safe use is the smashing or crushing of the cables in service, together with the effects of consequent splicing.Trailing cables are crushed when run over by cars, mining machines; and locomotives or when hit by falls of roof. Crushing damages the insulation and may cause failure at once or in later use. Failure may be either by short circuit between the conductors or by grounding to the track. The failure of a live cable causes electric arcs capable of igniting explosive mixtures of methane and air. Every cable failure in a gassy or dusty mine is, therefore, a real or potential hazard.Some mine operators do not allow the splicing of trailing cables for use in gassy mines, bet require that a damaged cable be immediately replaced and if repaired that it be used only in nongassy mines. Other operators allow the making of temporary splices to permit completion of the shift but require that such splices be remade and vulcanized before the cable is used again.Still other operators allow the continued use of temporary splices, which in general means that a cable is used until the splices give trouble in reeling, or overheat, or pull apart. Then the spliced sections are either cut out or the whole cable is replaced.Splices often determine the useful life of a cable. A splice poorly made may pull apart ueder mechanical strain and cause arcing that burn* the surrounding cable or ignites as or coal-dust. If it has lower conductivity a splice is the first part of the cable to heat; it may become so hot under load that it will burn apart and damage other parts of the cable, or, if it be a soldered splice, the solder may melt and allow parting of the cable. A poorly made splice often has insufficient insulation which may alloy short-circuiting between conductors or permit external contacts capable of giving an electric shock to one handling the cable. The splice is sometimes bulky from too much insulation and takes up too much room on the reel, causing uneven reeling; also by catching on the spooling device the oversized splice may receive expressive pulls and wear. Splicing is therefore a very important factor in the use of trailing cables."

Mar 1, 1932

IN this paper an attempt is made to describe the sluicing operations on the tin fields of north-eastern Tasmania. No claim is made to completeness, for much of the ground has already been covered, and nothing is to be gained by needless repetition. On this account some portions of the subject have obviously received but attention in order that others may be rather more fully dealt with; for instance, referring to the accuracy of various methods of valuing alluvial deposits, particulars of efficiencies, and water duties on both overburden and drift; also, the system of recording water distribution, &c. The plans of the tin-streaming shed, sluice and feed race, and overburden tail-race represent types of the most modern design.GEOLOGY. The principal alluvial dcposits being worked at the present time are situated either in the ancient or modern bed of the Ringarooma River or its tributaries. This river flowed in a north-easterly direction, receiving numerous tributaries on either bank...

Jan 1, 1910

Although the pattern of metamorphic zones south of the Thackaringa-Pinnacles Fault is much obscured by polymetamorphism, displacement of the orthopyroxene isograd by the fault agrees with the displacement of a horizon of "banded aplite" mapped by Andrews (1922). A dextral transcurrent component of 20,000 ft is indicated.INTRODUCTIONThe east-west Thackaringa-Pinnacles Fault (Andrews, 1922; King and Thomson, 1953), one of the major geological structures in the Broken Hill district, New South Wales, cuts across the general north-easterly strike of outcrops and fold structures of the Willyama Complex. The degree of shearing and recrystallization in its unusually wide crush zone and the manner in which adjacent rock units and structures have been dragged into conformity with its strike denote considerable movement on the fault. Information concerning the nature of this movement is of critical importance in the search for possible continuations or repetitions of lead-zinc mineralization south-west of Broken Hill.A transcurrent movement of 20,000 ft, with the southern block moving west, was estimated by Andrews (1922), who correlated prominent outcrops of "banded aplite" at The Pinnacles (north of the fault) and Big Hill (south of the fault). Displacement of this order, however, does not seem sufficient to explain the extent and character of the fault zone. Recent chemical and petrological studies of the banded aplites at The Pinnacles and Big Hill by Vernon (19B1) confirmed their similarity, but indicated an origin by metasomatic replacement of pre-existing folded and metamorphosed rocks. This raises the possibility that some...

Jan 1, 1965

By J. Dienenthal

Automatic Charging and Stoking Machines for use at ferroalloy furnaces are in operation for more than 20years. Dango & Dienenthal Maschinenbau GmbH (short: DDS) has developed several machine generations. Today advanced solutions help to achieve better charging and stoking results to minimize cost and to improve the working environment around the furnaces. Three different alternatives can be considered: Rail-mounted solution The machine(s) travel(s) on an overhead monorail to one or several furnaces and is locked in the desired working position from where charging and stoking is performed. Mobile solution This machine travels on the charging platform and is also locked at the respective working position to perform charging and stoking. Automation of a standard mobile charging and stoking machine A standard charging and stoking machine can be adapted for automation. A reliable navigation system is included. Charging and stoking is performed with the moving machine. Advantage versus other solutions: considerable lower investment cost and possibility to upgrade the mobile charging and stoking machine for later automation. Overall, automatic charging and stoking can save up to 10 per cent of the specific smelting energy. A better and more consistent furnace operation can be achieved. Different programs are used to cope with different furnace conditions and changing raw materials. All machine movements can be recorded and correlated to other furnace parameters. Working environment on the charging platform is greatly improved.

Jan 1, 2007

By S. Eck

In previous work the influence of the casting speed on the flow field and the shape of the solidification front in an industrial 0.82 x 0.25 x 0.8 m³ bronze caster had been investigated. Both numerical and experimental model represented 1:1 the real caster geometry. A comparison of the results of both numerical and experimental models for the flow during the casting process showed a good agreement in the qualitative velocity fields (flow direction and vortex formation). This work represents a parameter study of the numerical model with variations of the turbulence conditions at the inlet in order to clarify their influence on the flow field in the caster. In order to find the best boundary condition at the inlet, the numerical calculations for water have been compared with the measured flow fields in the water model. The new boundary conditions were then applied to the numerical model of the bronze casting process.

Jan 1, 2009

By R. L. Grant

[Detonators are used to explode permissible explosives, dynamites, or other high explosives. This explosion or detonation is brought about by the energy which is liberated as a combination of concussion and heat when the detonator is fired. In Other words; "The detonator is the key which unlocks the energy of a high explosive" (8)4. Being sensitive and latently dangerous, detonators must meet two primary requirements: They must be safe to handle and must detonate when desired, thereby imparting detonation to the explosive charge.]

Jan 1, 1941

By P. J. Rowsell, M. D. Waller

Paper presented at a meeting on: Artificial intelligence in the minerals sector, held in Nottingham, UK, 20 April 1993. The applications of artificial intelligence systems in the upstream petroleum industry are reviewed. Particular emphasis is placed on current and potential applications in drilling engineering. Several recent advances in drilling technology have led to a large increase in the quality and volume of data available. This combined with the escalating cost, particularly of off-shore operations, is testing the traditional reliance on the skill and judgement of rig operators. AI systems offer enormous scope in enhancing and aiding the performance of these operations

Apr 1, 1994