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By Dan Martz, Bill Moler, David Young, Wally Chen, Matthew Crow, Steve Norris, Tolga Togan

Two 610 m (2000 ft) long tunnels were driven through water bearing silts, sands and clays beneath the Sacramento River using a 4.59 m (15.1 ft) diameter Earth Pressure Balance Tunnel Boring Machine (EPBM). Four sheet pile shored shafts were sunk with and without dewatering. The pre-cast concrete segmentally lined and grouted tunnels were driven down at 6% grades beneath the river flood protection levees, buildings, roads, a railroad and adjacent to a Freeway Viaduct. Details of the schedule, cost, shaft construction, TBM, tunnel construction, and installation methodology for the twin1.676 m (66 in) steel force main pipes and environmental constraints are provided.

Jan 1, 2007

By Donald Leroux, Martin Suichies, Andy Trusiak, Chris Dechert

"In modem concentrators, the operation of flotation machines is often stabilized by simple control loops. Froth level, slurry density and aeration rate are all physical parameters typically controlled through classical PID loops. Few concentrators, however make use of advanced computing technologies for controlling the grade of flotation product streams. Technical challenges such as long process delay and the long and uneven sampling interval of on-stream XRF analyzers often restrain their implementation. Model Predictive Control (MPC) is known to have better performance than PID for controlling processes with long delays (such as flotation circuits). This paper describes the implementation of a multi-input/single-output (MISO) MPC algorithm and an FIR model identification routine using an object-oriented graphical computing environment.The MPC module (controller and identification) was implemented on an industrial control system and applied to many sulfide flotation circuits in the Brunswick Mining concentrator (New Brunswick, Canada). In most cases, the manipulated variable was the collector addition. As long as it is provided with decent process models, the performance of the MPC controller is good on all the flotation circuits on which it was applied. Significant reductions of grade variance are reported and the controller responds well to set-point changes. The user-friendly, graphical nature of the computing environment led to a high degree of acceptance by both the process engineers and the flotation operators.1. INTRODUCTIONOver the past three decades, much instrumentation has been developed for flotation machines. The introduction of instruments such as pulp density gauges and cell level probes was particularly well received by the plants where pneumatic and electronic controllers were available for implementing PID control loops. In a way, these simple loops revolutionized the mineral industry. The operation of flotation circuits could then be stabilized through the use of automatic controllers."

Jan 1, 1999

As part or a programme to raise lead smelter capacity from 65.000 to 140.000 tons bullion per annum. one new 1000 sq. ft. updraught area sintering machine replaced eight small downdraught machines.The metallurgical specifications were based on and laboratory tests at Mount Isa. Existing practice filtering concentrate as part of the charge preparation system and discharging wet filter cake to mixing was retained. This dictated a hot return fines circuit to maintain the required feed moisture content at low return sinter ratios.The engineering specifications provided for cenlralized control of plant and process, minimum operating labour, high plant availabi;lity and highest standardsof hygeine. Crushing and conveying capacity was set to cater for the most optimistic level of sintering capacity.On start-up a number of major engineering and hygiene problems became apparent, in addition to normal teething troubles. These problems have largely been overcome and reliable operation. at less than optimum production rate is now being achieved.

Jan 1, 1968

By P Stone, J. M. Cook, P. R. Simpson, C Mcdermott

Paper presented at the conference Economic geology in Europe and beyond II, models for mineral deposits in sedimentary basins, held in Keyworth, UK, 13-14 April 1994. The SW part of the Southern Uplands is a back-arc section of an accretionary thrust system, divided into structural blocks by major NE-SW shear zones and NW-SE faults forming the margins of Permian half-grabens. The highest arsenic levels in stream sediments (over 65 ppm) are associated with those blocks carrying brittle-ductile transition fabrics. Three factors combine to recomend the area as having potential for gold mineralisation: As-rich greywackes as country rock, felsic intrusions and a major shear zone. Selected stream sediments were analysed for gold using lead fire assay with ultra-pure flux and ICP-MS finish. Several localities showed over 15 ppb Au, the three most significant being within the hanging wall of the Orlock Bridge Fault and each having distinct characteristics

Aug 1, 1995

By A. Mahmoudkhani

Primary cementing is the process of placing cement in the annulus between the casing and the formations exposed to the wellbore. Portland cement was first used in 1903 in the Lopoc Field in California for well cementing. Since then, the major objective of primary cementing has always been to provide zonal isolation in oil, gas and water wells, i.e. to exclude fluid(s) in one zone from another zone in the well. To achieve this objective a hydraulic seal must be created between the casing and cement and between the cement and the formations, while at the same time preventing fluid channels in the cement sheath. This requirement makes primary cementing the most important operation performed on a well. Without complete isolation in the wellbore, the well may never reach its full producing potential. The industry knowledge on cements relies heavily on empirical data, but the chemistry, physics and structure of cement are not fully understood yet. The strength of concrete can be increased essentially by reducing its porosity through optimizing the size distribution of its components and filling the residual porosity of the hydrated cement phase with inorganic fillers. This approach has successfully utilized in different ways and several technologies for placing high performance oil and gas well cements have been developed over the last few decades. There are reasons to believe that the next source of improvement will lie in the fine-tuning of the hydrates themselves and of the different parameters that drive short (ionic?covalent bonding) and long (ionic correlation) interactions.

Jan 1, 2012

By John C. Machisak

INJURY DATA and experience at coal mines in the United States for 1956 and 1956 are presented in this publication with a minimum of interpretation and comment because of the numerous tables required to afford detailed comparisons between the 2 years. Corresponding table., for 1955 and 1956 follow in consecutive order under the following general sections: (A) General injury experience: Tables I to II: contain current data on number of fatal and nonfatal injuries, frequency and severity rates, and average severity. (B) Selected injury data: Tables 12 to 77: Contain current data on causes of injuries, distribution of injuries by part of body injured, clays of disability, extent of hand and machine loading, experience by employment and production groups, and various other operating factors and physical conditions related to the occurrence of injuries at the Nation's coal mines. (C) Injury experience, by States: Tables 78 to 87: Contain data on injuries, injury rates, employment, cause of injuries, aid severity rates by States. (D) Major disasters: Table 88: Contains data on major disasters, 1947 -56. A major disaster is defined as a single accident in which, or as the result of which, five or more persons are killed instantly or died at any time thereafter. (E) Historical coal-mine-fatality experience: Tables 89 to 93: Contain data on fatalities and their causes at bituminous-coal and anthracite mines from the earliest records through 1956.

Jan 1, 1960

By Christopher J. Pacitto

This paper presents a case history of an engineered, monitored, and tested program that provided an effective and satisfactory basis for the completion of pile foundations for Twin Dolphins 1 at La Peninsula Condominiums located in the Isles of Capri in southwest Florida, U.S.A. An 8-story building (withl-story parking underneath) along with recreational facilities (such as a swimming pool and tennis courts) had been planned for final construction. Following an evaluation of various foundation alternatives, a precast prestressed concrete (PPC) pile-supported system was selected. The building foundations were designed for pile capacities of 445kN (50 tons) and 890kN (100 tons) in compression and 133kN (15 tons) in uplift. A test pile program was performed to provide site-specific pile driving data, verify design assumptions, determine production pile lengths, and evaluate pile driving criteria. A total of 24, 356 mm (14-in.) square, 19.8 m (65 ft) PPC concrete piles were driven and dynamically load tested utilizing a Pile Driving Analyzer (PDA) within the building limits. Dynamic monitoring during probe pile installation and restriking was performed to estimate the ultimate capacity of the piles and to evaluate driving stresses during installation. CAPWAP analyses were preformed on PDA data to better estimate pile capacity, resistance distribution, and predict pile freeze (increase in pile resistance with time) and thus optimized the production pile lengths. Upon completion of probe pile installation, 12 of the probe piles were tested using the Pile Echo Tester (PET) function of the Pile Integrity Sonic Analyzer (PISA). PET testing was performed to evaluate the integrity of piles which had exhibited high driving stresses during PDA testing. Information gathered during the probe pile driving program was effectively utilized as part of the overall quality control program to install a total of 539 PPC piles (including 24 probe piles) within the building limits at the project site to depths ranging from 9.1 to 19.8 m (30 to 65 ft) below the existing ground elevation as part of the foundation support system. Prior to installation of probe or production piles, a termination criterion was established using 1-dimensional wave equation analyses in addition to the design pile embedment requirement. The predicted pile capacities compared very well with the capacities from the CAPWAP analysis for probe piles. Use of geotechnical instrumentation and PDA assisted technology enabled each foundation support element to be constructed to its optimum capacity and at optimum cost. Furthermore, by using PDA the consultant was able to quantify a difficult to measure geotechnical phenomenon termed "pile freeze" which eliminated costly overdriving and unnecessary splicing of piles.

Jan 1, 2002

By Mostafa Benzaazoua

Les remblais en pâte cimentés sont de plus en plus utilisés dans les exploitations minières souterraines. Une autre alternative d?utilisation du remblai en pâte consiste à le pomper et à le stocker dans des empilements de surface. En plus d?avoir des avantages d?un point de vue de stabilité physique des ouvrages, le remblai en pâte cimenté en surface permettrait également de stabiliser les contaminants dans la matrice du remblai à l?aide du processus de solidification et de stabilisation. Dans cette étude, des remblais en pâte constitués d?un résidu minier sulfuré renfermant beaucoup d?arsenic et de différents liants ont été testés afin d?évaluer la stabilisation des contaminants dans la matrice de remblai. La méthode utilisée pour évaluer la stabilisation et la solidification des contaminants est le test de lixiviation en extracteur de Soxhlet. Les résultats géochimiques issus de ces essais ainsi que la caractérisation chimico-minéralogique des remblais lixiviés ont été analysés pour comprendre les phénomènes chimiques présents dans les remblais durant le temps de cure. Les résultats obtenus montrent que les sulfures présents dans les remblais étudiés (pyrite FeS2 et arsénopyrite FeAsS) s?oxydent et provoquent la dissolution des hydrates les plus vulnérables (dissolution de la portlandite Ca(OH)2 et/ou décalcification des gels CSH). Le calcium produit permet de précipiter les sulfates (essentiellement sous forme de gypse plus ou moins hydraté) et l?arsenic sous forme d?arséniates de calcium plus stables. Les différents liants utilisés donnent des résultats différents en termes de stabilisation et de solidification qui seront discutés dans cet article.

Nov 1, 2002

By Hugo Cabrera-Real

This work investigated the chemical and mineralogical properties of CaO-SiO2-CrOx-CaF2- MgO slags. Synthetic slags were prepared and the effect of the slag basicity (CaO/SiO2) and MgO contents on the stability of the mineralogical species formed was analyzed. The morphology and composition of the slags were analyzed by XRD and SEM-EDS, whilst their chemical stability was evaluated by leaching with an aqueous acetic acid solution. It was found that in slags with CaO/SiO2 = 1, the main Cr-compound was MgCr2O4 spinel, which forms octahedron crystals. Small amounts of CaCr2O4 and CaCrO4 were also observed. It was found that increasing the slag basicity from 1 to 2 the compounds MgCr2O4 and CaCr2O4 were formed together with the Cr(V)-containing compound complex Ca5(CrO4)3F which forms hexagonal crystals. The results showed that the highest chromium concentration levels in the leaching liquors corresponded to slags with CaO/SiO2 = 2, probably owing to the formation of Ca5(CrO4)3F.

Jan 1, 2010

By D N. B Skinner

Changes in the configuration of late Cenozoic volcanic arcs related to Pacific-Australian plate convergence in northern New Zealand may have localised large-scale epithermal gold-silver mineralisation to a particular part of the volcanic arc system, the Coromandel Volcanic Zone (CVZ). The history of arc-type volcanism in northern New Zealand began with the development of the continental margin Northland Volcanic Arc from early-mid Miocene (26-15 Ma). From 18-15 Ma the Northland Volcanic Arc extended south into the northern and western part of the CVZ where it is dominantly composed of andesite with lesser dacite and very minor rhyodacite. In the south, centre and east of the CVZ, younger andesite-dacite volcanism overlapped in space and time (14-5 Ma) with voluminous rhyolitic volcanism associated with rift-hosted calderas and minor basaltic eruptions. This change to bimodal rhyolitic-basaltic volcanism and extensional tectonics was a result of southwest (SW)-directed propagation of the Colville-Lau oceanic island+ arc into the north-northwest (NNW) trending Northland Volcanic Arc and its underlying continental crust. The extensional tectonic regime created in the collision zone between the two arcs is also the site of the 14-6 Ma Coromandel epithermal gold-silver province, which contains some 50 separate deposits and has a production (1862-1996) of about 300 t Au and 1150 t Ag. Extensional tectonics facilitated the emplacement of silicic magma at shallow crustal level and led to reactivation of deep basement faults. The resulting enhanced heat flow and fault-focused fluid flow localised large hydrothermal systems and associated extensive low-sulphidation epithermal gold-silver deposits in the southern part of the province, as at Waihi, Golden Cross and Karangahake.

Jan 1, 1997

Capture airborne respirable dust generated by an auger-type continuous mining machine to reduce workers' dust exposure. Approach Install a water-powered scrubber system, operating at 1,400 psi, on the sides of the conveyor. The scrubber draws the dusty air from the face area and discharges cleaned air into the face return. How It Works Auger-type continuous miners pose unique ventilation and dust control problems. To protect face workers from the dust, the end of the brattice is usually maintained close to the face to increase ventilation effectiveness. However, it is taken down as the machine cuts toward the exhaust side to allow the machine to complete its cut. Often, the brattice is not reinstalled in a position to most effectively control

Jan 1, 1989

By Charles Hardy, George D. Cremer

POWDER metallurgy has been established for some time as a novel method for manufacturing a great variety of articles generally specialties that could not be made conveniently by any other method. In this category are such parts as porous hearings cutting tools of sintered carbides, and electrical contacts in which the metallic constituents do not tend to alloy in the proportions employed. The industry, however, is now at a stage where it has begun to manufacture articles that can and have been made by other methods. Thus, powder metallurgy is now preferred technique for the production of numerous machine parts characterized by high strength, accuracy of configuration, and substantial lack of porosity. Manufacture of such machine parts from metal powders has no doubt been stimulated by the war, although the trend in this direction has been apparent for several years. In any case, quantity production of high-density precision pieces by ponder metallurgy is now in full suing in the United States, and such production can and should continue to expand during and after the war.

Jan 1, 1942

By S. Yerel

In a mineral processing plant, the determination of a preventive maintenance schedule is one of the most important maintenance policies. In this study, to determine the preventive maintenance schedule for the Emet Colemanite Mineral Processing Plant in Turkey, a mean quality control chart was constructed using the historical concentrate B2O3 grade data. The effect of preventive maintenance scheduling on B2O3 grades was monitored using the mean quality control chart. It was determined that recovery increased after each preventive maintenance scheduling. Close examination of the mean quality control charts indicated that there were three periods that showed different grade characteristics. These were identified as the period ?prior to preventive maintenance,? the period ?after preventive maintenance? and the period ?requiring preventive maintenance.? These periods were compared as two independent samples by using the Kolmogorov-Smirnov test. Application of this test for interpretation of the mean quality control chart enabled the authors to analyze the system effectively, and it showed that the preventive maintenance for this plant should be scheduled at four-month intervals.

Jan 1, 2007

By Nobuaki Sato

For the recovery of uranium from spent nuclear fuel, sulfide reprocessing process, which consists of voloxidation, selective sulfurization, and magnetic separation or selective dissolution steps, are proposed. In this paper selective sulfurization of rare-earth oxides in the presence of uranium oxides was studied by thermogravimetry and X-ray diffractometry. In case of the mixture with UO2, the rare earth oxides R2O3 (R=Nd, Eu, etc.) were preferentially sulfurized by CS2 formingoxysulfides and sulfides, while UO2 remained at temperatures lower than 500 °C. When R2O3was mixed with U3O8, first, the reduction of U3O8 to UO2 occurred at low temperatures followed by the sulfurization of R2O3. The separation of rare earth elements from UO2 in suspensionsolution by the use of permanent magnet was examined. The advantage of the proposed process was also discussed by compared with current process.

Jan 1, 2006

By A. Adu-Acheampong

A geotechnical study was conducted to identify the cause(s) of stope instability at the Ashanti Mine (Obuasi, Ghana). As part of the investigation, laboratory testing of rock was performed and the rock mass was classified according to the Q-System (Barton et al., 1974).Numerical analyses were performed using the computer program FLAC (Itasca, 2001). The observed failure zone around the stopes was simulated using both Mohr-Coulomb and Hoek-Brown (Sheorey,1997) models. Yielding along peripheral graphite bands and tensile failure were clearly identified to be the major contributors to stope instability.

Jan 1, 2003

By R. A. Wattenbarger, H. J. Ramey

The trend in gas well testing has been to rely more on the early-time flow data of drawdown and buildup tests than on stabilized flow tests. The stabilized testing methods often are not adequate for complicated modern gas reservoirs because many of these reservoirs have extremely low permeabilities and the transient flow period of a well test can last for days or weeks. It has become common to augment the flow capacity of gas wells by hydraulically fracturing their producing formations. In deep reservoirs the induced fractures are generally vertical and tend to follow a single plane of weakness. The presence of a vertical fracture at the wellbore complicates the transient flow behavior of a low permeability gas well. The flow is further complicated when turbulence occurs near the wellbore. Russell and Truittl published transient drawdown solutions for vertically-fractured liquid wells. They developed methods of drawdown and buildup testing utilizing these solutions, which were based on numerical simulation. Clark2 applied the basic Russell-Truitt solutions to analyze fractured water injection wells by falloff tests. Field examples were given to substantiate the method of analysis. The Russell-Truitt solutions and well testing methods can be extended to gas well flow. Millheim and Cichowicz3 presented the drawdown equations for *Now with Scientific Software Corp., Denver. ideal gas flow, including the effects of formation damage and turbulence. Two actual field cases were presented, both of which exhibited extensive fractures and turbulent flow. For the pressure range of these well tests, the use of ideal gas equations was acceptable. These field cases were significant in being the first published data showing the occurrence of turbulence in fractured gas wells. We, also, observed such cases in practice. Our purpose here is to extend the theory of fractured gas well testing to the flow of real gases. To determine the effects of wellbore storage and turbulence on well test interpretation, we developed a finite-difference model to simulate well test conditions. Since gas wells usually are widely spaced and have high compressibility, the emphasis has been put on the early transient behavior before the effects of the outer boundary are noticeable at the wellbore. The Mathematical Model The geometry of our mathematical model is similar to that used by Prats.4 The well is centered in a circular uniform reservoir. A vertical fracture of infinite flow capacity penetrates the formation and passes through the wellbore. The wellbore itself is not important. Fig. 1 shows a sketch of the problem. Fig. 2 shows the idealized model. The equation for the flow of real gas in a porous medium with uniform porosity, permeability and thickness is5-7

Jan 1, 1970

By J. O. Marsden

Part I in this series of papers considered the chemistry of medium-temperature pressure leaching of copper sulfide concentrates and reviewed the metallurgical testing and initial process development for this technology. This initial work resulted in the development of a process flowsheet utilizing superfine grinding (to a P98 of 12 to 15 µm and P80 of 6 to 7 µm), pressure leaching at 160° to 170ºC, followed by conventional solution extraction (SX) and electrowinning (EW) for the recovery of copper. However, this process required a significant amount of concentrated acid to be fed to the pressure leach vessel to meet the reaction requirements, representing a cost of between $0.03 and 0.05/lb copper (2006 basis) produced by the process. It was immediately recognized that the development of a process that did not require such a large acid addition would be advantageous. This paper, which is Part II in the series, describes the development of a process that incorporates medium-temperature pressure leaching and direct electrowinning (DEW) in a novel and innovative process flowsheet. Phelps Dodge (a subsidiary of Freeport-McMoRan Copper & Gold Inc.) refers to this as the ?MT-DEW-SX? process. Part III in this series covers the large-scale demonstration of the MT-DEW-SX process at Bagdad, Arizona; and Part IV addresses the development and design of a full-scale commercial application at Morenci, Arizona.

Jan 1, 2007

By B. Anameric, S. K. Kawatra, K. B. Rundman

The iron nugget process is an economical, environmentally friendly, cokeless, single-step pig iron making process. Residence time dependent process requirements for production of pig iron nuggets at a fixed furnace temperature (1425 C) were investigated. Three chemically and physically different products were produced after complete reduction to iron, depending on the residence time in the furnace. These products were direct reduced iron (DRI), transition direct reduced iron (TDRI), and pig iron nuggets (PIN). The increase in the carbon content of the system as a function of residence time was detected by optical microscopy and Microhardness measurements. Sufficient carbon dissolution for the production of pig iron nuggets was obtained after 40 minutes residence time. The pig iron nuggets produced had chemical and physical properties similar to blast furnace pig iron. They were liquid state products and slag was completely separated from the metal.

Jan 1, 2005

By Y X. Xue, J Pan, D Q. Zhu

In order to reveal the correlation between the fundamental sintering characteristics of iron ores and their real sintering behaviours, a comprehensive evaluation index is proposed based on the measurement of four high temperature indexes, ie assimilation temperature, liquid phase bonding strength, liquid fluidity and calcium ferrite formation percentage, and the sintering pot tests of single ore fines and their blends. The results show that both the lowest assimilation temperature and liquid fluidity of ore blends appear to be the linear superposition of those of single iron ores except for the liquid phase bonding strength and calcium ferrite formation percentage. Furthermore, the tumble index of the sinter product obtained from blended iron ores also corresponds to a linear superposition of that of single ores, but not for the solid fuel rate and productivity. The comprehensive strength index YT exhibits a credible linear positive correlation with the four high temperature reactivity indexes, whereas the comprehensive productivity index YP possesses a lower correlation with the four high temperature reactivity indexes. The comprehensive strength index YT developed can predict the tumble index of the sinter product quite well, but the comprehensive productivity index YP cannot be used to evaluate the productivity effectively.CITATION:Zhu, D Q, Xue, Y X, Pan, J and Shi, B J, 2017. Correlation between high temperature sintering characteristics and sintering behaviours of iron ore fines, in Proceedings Iron Ore 2017, pp 123–132 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Alain S. Kivava, Olawale K. Aromolaran, Charles Nzolang, Anthony T. Bolarinwa, Georges M. Kasay

Rare earth elements (REEs) are crucial in high-tech and green technologies. The Democratic Republic of Congo (DRC), rich in mineral resources, shows potential for REE deposits in carbonatites, pegmatites, and placers. This paper reviews global REE resources, highlights potential REE targets in Africa, and emphasizes the need for further research and exploration in the DRC to unlock its REE potential.

Feb 4, 2022