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By L. J. Health

Synthetic rock with predictable porosity and permeability has been Prepared from mixtures of sand, cement and water. Three series of mixes were investigated primarily for the relation between porosity and permeability for certain grain sizes and proportions. Synthetic rock prepared of 65 per cent large grains, 27 per cent small grains and 8 per cent Portland cement, gave measurable results ranging in porosity from 22.5 to 40 per cent and in permeability from 0.1 darcies to 6 darcies. This variation in porosity and permeability was caused by varying the amount of blending water. Drainage-cycle relative permeability characteristics of the synthetic rock were similar to those of natural reservoir rock. INTRODUCTION The fundamental behavior characteristics of fluids flowing through porous media have been described in the literature. Practical application of these flow characteristics to field conditions is too complicated except where assumptions are overly simplified. The use of dimensionally scaled models to simulate oil reservoirs has been described in the literature. 1-3 These and other papers have presented the theoretical and experimental justification for model design. Others have presented elements of model construction and their operation. In most investigations the porous media have consisted of either u ncon soli da ted sand, glass beads, broken glass or plastic-impregnated granular substances—materials in which the flow behavior is not identical to that in natural reservoir rock. The relative permeability curves for unconsoli-dated sands differ from those for consolidated sandstone. The effect of saturation history on relative permeability measurements is discussed by Geffen, et a1.4 Wyga15 has shown quite conclusively that a process of artificial cementation can be used to render un consolidated packs into synthetic sandstones having properties similar to those of natural rock. Many theoretical and experimental studies have been made in attempts to determine the structure and properties of unconsolidated sand, the most notable being by Naar and Wygal.6 Others have theorized and experimented with the fundamental characteristics of reservoir rocks. This study was conducted to determine if some general relationship could be established between the size of sand grains and the porosity and permeability in consolidated binary packs. This paper presents the results obtained by changing some of the factors which affect the porosity and permeability of synthetically prepared sandstone. In addition, drainage relative permeability curves are presented. EXPERIMENTAL PROCEDURE Mixtures of Portland cement with water and aggregate generally are designed to have certain characteristics, but essentially all are planned to be impervious to water or other liquids. Synthetic sandstone simulating oil reservoir rock, however, must be designed to have a given permeability (sometimes several darcies), a porosity which is primarily the effective porosity but quantitatively similar to natural rock, and other characteristics comparable to reservoir rock, such as wettability, pore geometry, tortuosity, etc. Unconsolidated ternary mixtures of spheres gave both a theoretically computed and an experimentally observed minimum porosity of about 25 per cent.7 By using a particle-distribution system, one-size particle packs had reproducible porosities in the reproducible range of 35 to 37 per cent.6 For model reservoir studies of the prototype system, a synthetic rock having a porosity of 25 per cent or less and a permeability of 2 darcies was required. The rock had to be uniform and competent enough to handle. Synthetic sandstone cores were prepared utilizing the technique developed by Wygal.5 Some slight variations in the procedure were incorporated. The sand was sieved through U. S. Standard sieves. A 18-20 sand denotes that the sand passed the Number

Jan 1, 1966

By B. M. England, M. V. Swain, N. Bristow, R. D. Dukino

The toughness and fracture mechanisms of ores with significantly different microstructures from Yandi, Koolan and Mount Whaleback were studied with a view to understanding their degradation behaviour. Bulk fracture toughness was determined by the 3-point single-edge notch beam test and the results interpreted using Weibull statistical analysis; indentation fracture mechanics was also used to measure fracture toughness of the different mineral forms and to understand their response to contact fracture

Apr 1, 1995

By J. A. Elliot

Deep Mix-in-Place soil stabilisation is achieved by forming columns of soil/cement arranged to overlap by secant intersection. Alternate columns are constructed initially and infilled. The cementitious material injected is designed to retard the strength of the resulting mix thereby allowing satisfactory overlapping. Columns are constructed using a designed large diameter mixing auger mounted on a smaller diameter auger stem. This is firstly screwed to the design depth removing only such spoil as to enable penetration of the auger, and subsequently counter rotated and extracted in a predetermined mixing pattern and grout injection rate to ensure continuous and homogeneous treatment through each successive level. The process is performed whilst monitoring auger depth, grout flow and pressure. Cementation Piling and Foundations Limited used this technique to stabilise allu­vium and to facilitate the construction, by conventional techniques, of a circular pumping station pit of 10M diameter to 10M below ground level. The work was carried out within 3M of adjacent domestic properties, and on a very restricted site in Elland, West Yorkshire. Ground conditions consist of 2M of cohesive alluvium becoming water bearing and increasingly sandy and gravelly with cobbles which overlies the mudstones at 10.0m depth. Sandstones beneath formed an aquiclude to artesian ground water with the underside of the open excavation approxi­mately 1.0M from the top of this material. Peripheral treatment into the mudstone, coupled with pressure relief wells, proved successful and final excavation depth was achieved in "the dry".

Jan 1, 1989

By J. Luxford

The last decade has seen an enormous increase in the use of contractors right across the Australian mining industry. So much so that contractors now operate 33 of the 68 underground metalliferous mines around Australia and are making significant inroads into iron ore in the west and coal in the east. Safety used to be a low priority for many contractors. The picture has changed dramatically in recent years as most contractors take a far more professional approach to safety management. This paper examines the changes that have occurred and the requirements for effectively managing safety in a contracting environment.

Jan 1, 2000

By Stephen L. Chryssoulis, Stamen Dimov

"Preg-robbing has been known for many years, where increased losses are suffered because dissolved gold is removed from solution by adsorption onto carbonaceous matter. In direct cyanidation circuits it is reasonable to conclude that the preg-robbed gold is either in a gold cyanide [Au(CN) - 2, AuCN] or metallic [Au°] form. However, in circuits with a pre-oxidation step possibilities increase and multiply even further because of water recycle streams containing apparent and not-so-apparent gold ligands. It is in these circuits where speciation of sorbed gold, i.e. the identification of the gold compound, is useful. The importance arises from the fact that proper identification of the sorbed gold species can be used to determine how, when, where and why gold was removed from solution, thereby identifying the exact cause of the problem and providing clues as to how it may be rectified.INTRODUCTIONTo the best of our knowledge, this is the first attempt ever to speciate gold preg-robbed by carbonaceous matter using a surface sensitive microbeam technique. This approach enables the direct determination of gold species sorbed on carbonaceous particulates, opening an entirely new field in the understanding of the chemistry of gold sorption on carbon. The reasoning behind this effort was to add to the current knowledge of the detrimental effect chloride ions have on gold recovery by the pressure oxidation and in particular why in the ensuing CIL step, gold is not being desorbed from the surface of the carbonaceous particles (Table 1)."

Jan 1, 2004

By Paul D. Klipfel

Introduction Mineral exploration interest, principally for gold, in the south-western Pacific has surged to new proportions. This is primarily due to the application of epithermal exploration concepts in the Australian-Oceana region. Other factors that have contributed to the high level of exploration interest include governmental policies supportive of mineral exploration, along with relative ease of tenure access and a relatively short bureaucratic process. This paper highlights exploration and development activities in the North Island of New Zealand, Fiji, Vanuatu, the Solomon Islands, and Papua New Guinea (Fig. 1). It provides a framework to understand the overall recent enthusiasm that has been brought to the south Pacific by explorationists. Through these recent developments, it is clear that the south Pacific region will become a significant gold producing area and thereby worthy of attention and study. Papua New Guinea alone is the free world's seventh largest producer (Table 1). And, with the addition of production from deposits presently being developed, this status is likely to be raised. History Gold was first noted on various Pacific islands in the late 1500s by Spanish explorers. They thought they had reached the legendary King Solomon mines. Since then, the history of prospecting in the southwest Pacific has coincided with the colonization of the region. Settlers in New Zealand extensively mined alluvial and lode gold deposits starting in the 1850s. The spread of European colonization to the more remote Pacific islands from 1880-1940 was accompanied by varying degrees of prospecting activity by planters, traders, and settlers. Some were successful, others may have been successful, but never returned due to hostile indigenous peoples or disease. In general, records of such prospecting activity are meager and exploration leads are, in some cases, gained through local village folk memory. Most early discoveries were alluvial finds. These led to placer operations, particularly in New Zealand, the Solomon Islands, and Papua New Guinea. Continued prospecting located lode deposits such as the Morobe Gold-field of Papua New Guinea, the Coromandel Peninsula of New Zealand, and the Emperor of Fiji. Some areas were prospected thoroughly. Yet others, such as Vanuatu, remained relatively unexplored until the present exploration surge began. During World War II, interest in minerals was diverted. It was renewed significantly until the middle 1960s and early 1970s when regional porphyry copper exploration was conducted.

Jan 10, 1987

By V. A. Marple

At the Twin Cities "lining Research Center (TCMRC) a project is underway to determine how varying the parameters of a coal-cutting process would affect the amount and the size distribution of the generated dust. The cutting parameters being investigated are the cutting speed, depth of cut and shape of the cutting, tool. To accomplish this research ft is necessary to collect and transport the coal dust venerated at the cutting tool to measuring instruments for analysis. The purpose of this contract was to develop and deliver a system of instruments for measuring the size distributions of the generated coal dust. The instruments employed are essentially those developed for particulate air pollution measurements (1, 2). The instrument system covers a particle size range of 0.005 to 20 microns and is capable of performing in situ measurement and presenting data in real time.

Jan 1, 1974

By Matthew Janes

Statnamic load testing is becoming widely accepted as a method to quickly and economically determine the load-deflection behaviour and ultimate static resistance of high capacity deep foundations. Strain instrumented large diameter bored shafts were tested at four locations for the federal and state Departments of Transportation in the United States. Tests were conducted vertically (to 30 MN) and laterally on the shafts and, in some cases, testing was completed over water. Instrumented shaft test results provided shaft load distribution with depth and shaft shear transfer stress throughout the soil stratum. Shaft end bearing and ultimate end bearing stress values were provided. On two projects, Osterberg load cells provided comparative static data for skin friction and end bearing. Correlations between Statnamic derived static load-displacement results and Osterberg load-deflection results are very good. Statnamic lateral load test results were correlated with static lateral results in addition to providing useful dynamic response and damping data.

Jan 1, 1996

By C E. J de Ronde, I C. Wright

Oceanic subduction-related volcanic frontal arcs extend over 20 000 km within the western Pacific basin and over 21 500 km worldwide, yet they remain largely unexplored with respect to active seafloor mineralization. Systematic exploration of 26 major submarine volcanoes along ~840 km of the Kermadec arc northeast of New Zealand has documented ten (39 per cent) as being hydrothermally active. This frequency of venting is comparable to that on slow-to-moderate rate spreading mid-ocean ridges, which comprise ~80 per cent of the 60 000 km-long global system of spreading centers. The chemistry of fluids discharged from the Kermadec arc volcanoes is moderated by magmatic components in both the gaseous (CO2 + SO2-H2S) and liquid (Fe) phases at very high concentration.The high frequency of venting coupled with chemically rich discharge discovered during this first systematic survey of any arc system forecasts submarine arcs as being important sources of chemicals to the oceans and as potentially lucrative exploration sites for seafloor mineralization. The exploration protocols developed during these surveys include bathymetric mapping of mostly unknown volcanic edifices, followed by detailed water column profiling and sampling to detect and characterize volcanic fluid emission signatures. These procedures are being refined as the survey progresses, both for efficiency and as direct seafloor observations become available for predictive application of water column plume information to guide seafloor mineral exploration.

Jan 1, 2002

By Derek J. Penrice

A critical element of the Transbay Transit Center Program, the Caltrain Downtown Extension (DTX) will extend commuter rail service into downtown San Francisco and accommodate future statewide high-speed rail service. The DTX project includes 1.8 miles of underground construction, comprising significant sections of mined and cut-and-cover tunnel. At the request of stakeholders, an updated cost estimate was prepared early in the project?s preliminary engineering phase. Unsurprisingly, this yielded a cost substantially higher than the available budget. This paper provides a summary of the management processes and planning decisions taken to bring the project back to budget, resulting in a configuration which derives maximum value from available funding and retains maximum flexibility for future system expansion.

Jan 1, 2008

Process Options for Difficult Arid-Region Nickel Laterites In the absence of the discovery of significant nickel sulfide deposits, the future of Australia's nickel industry will increasingly depend on cost effect processes for low-grade nickel laterites. The problems encountered with the West Australian HPAL plants, resulting in three of the four plants being shut down, have caused the industry to revisit atmospheric leaching options, particularly heap leaching. West Australian laterites are characteristically very varied in grade, chemical composition and mineralogy with the result that, thus far, one process does not fit all laterites. In this paper the leaching of an especially refractory ore is compared using column leaching of whole ore and atmospheric leaching and HPAL processing of ground ore. The key characteristic is the resistance of the goethite phase to acid attack with low-to-moderate temperature leaching conditions. The refractory characteristic is attributed to the stabilising influence of chromium and aluminium and possibly manganese substitution in the goethite crystal structure and goethite morphology. A significant three-fold increase in both nickel and cobalt extractions under atmospheric leaching conditions was achieved by the relatively simple modification of bubbling sulfur dioxide into the reaction vessel to create a reducing environment. Recoveries increased from <30 per cent to 90 per cent nickel and 86 per cent cobalt after 10 hours of leaching at 95¦C. An even greater improvement was achieved under ambient conditions by heating the ore to temperatures above 250¦C for 30 minutes. Subsequent leaching at ambient temperature gave an eight-fold increase in both nickel and cobalt recoveries after 14 days bottle rolling. Both methods could be optimised and implemented in such a way as to increase laterite reserves in conjunction with a heap leach operation but may be better suited to vat or closed tank processing.

Sep 13, 2010

By K. Liddell

Current practice for the recovery of platinum group metals (PGM) from flotation concentrates is by energy-intensive smelting processes followed by separation and refining of the base and precious metals. Energy costs are rapidly increasing in South Africa and this trend is forecast to continue in future years. Moreover, the smelting operations are highly susceptible to deleterious constituents, particularly chromite; and the increasing tonnages of UG2 chromititic ore being mined results in an increasing chromite content of smelter feeds. Hence there is a substantial incentive to assess and implement alternative processes to smelting for the treatment of PGM concentrates. The Kell process is a patented hydrometallurgical alternative to smelting that is totally insensitive to the chromite content of the feed concentrate and comprises three commercially proven unit operations (pressure oxidation leaching of base metals and sulfur, roasting and chlorination of precious metals). The Kell process provides the opportunity for existing and new PGM producers to significantly reduce their energy consumption, and in particular their consumption of electricity, by removing the need to smelt PGM concentrates. Energy costs, greenhouse gas emissions and installed power requirements are also much reduced. Compared with smelting and refining these reductions are calculated as: ? Total energy consumption-50% reduction ? Electrical energy consumption-84% reduction ? Energy consumption costs-76% reduction ? C02 emissions-70% reduction ? Installed power requirement 92% reduction. The data obtained from simple laboratory batch amenability testing can be readily applied to the Simulus mass and energy balance simulation procedure to determine energy and reagent consumptions, equipment selection and process optimization. The applicability of Kell to treating low-grade 'dirty' concentrates with high UG2 content as well as to polymetallic concentrates containing base metals as the major payable metals with subordinate PGM means that these savings can also be expected when the process is used for treating a range of concentrate types and grades. Keywords PGM,UG2, Merensky, smelting, chromite, electricity, hydrometallurgy, Kell Process, Eskom.

Jan 1, 2011

By J. Lindenau

One of the significant benefits of electronic detonators is their safety, especially their relative insensitivity to extraneous electrical energy. The various brands of electronic detonators on the market have different resistance to electrical stimuli, but all have safety structures designed to afford a significant level of protection. A common source of extraneous electrical energy is lightning. This paper discusses the nature of the energy that occurs with a lightning strike and the resistance offered by electronic detonators. Four actual cases of exposure of electronic detonators to lightning strikes are considered. Electronic detonators, like other initiation systems, are vulnerable to very close or direct lightning strikes. The incidents are a reminder that all blast patterns need to be vacated on the approach and during the progress of a lightning storm. 1. Orica

Jan 1, 2008

By Avis W. Effinger

In conjunction with pilot steamflood tests in the Venango sands of Warren and Venango Counties, Pa., the Marx and Langenheim (4)3 calculations were adapted and programed for digital computer solution to predict test performance. The Monte Carlo technique was incorporated in the calculations to provide values of several variables which could not be adequately defined from available information. The computation methods are explained and the FORTRAN IV program listing is presented. Data and results of the prediction calculations for Venango oil sands are also shown.

Jan 1, 1969

By Kunihiko Takahashi, Gjergj Dodbiba, Hisayoshi Umeda, Toyohisa Fujita

"An increasing number of mobile phones is increasing the number of the discarded mobile phones. Many efforts are thus being made to collect and recycle these devices. This paper is a short introduction of the recycling system of precious metals from the discarded mobile phone, currently available in Japan. Moreover, an attempt has been made to compare the energy recovery and the mechanical recycling of plastic wastes from the discarded mobile phone. The assessment has been carried out in the context of the life cycle assessment methodology (LCA). The environmental impact of each option was assessed by calculating the following impact indicators: depletion of abiotic resources (ADP), and global warming potential (GWP). 1. Introduction In 2003, the demand for mobile phones was increased since the camera was included in a mobile phone and the 3rd generation of mobile phones was introduced. In turn, the number of discarded mobile phone is rising sharply. Generally speaking, all the metallic parts of mobile phones can be recovered and recycled by using smelting and purification techniques. The recycled materials are then used to fabricate other new products."

Jan 1, 2008

By M. W. Franklin, D. W. Hendriks

"Changing ore types, feed grades and c1rculat1ng loads are some of the many factors that can make flotation feed-back control difficult. To control a flotation circuit using conventional fixed-parameter control algorithms, one must either tune the controllers very often or tune the controllers to the middle of the normal operating range. The former approach is very time consuming, while the latter approach can lead to long periods of either very sluggish responses or highly reactive responses which can lead to instability. The problem becomes compounded if feed-forward variables are introduced, creating even more variables to tune. An alternative to a fixed-parameter control algorithm is an adaptive control algorithm. An adaptive control algorithm continuously retunes itself based on previous reactions to its changes. Feed-forward control also becomes much more viable because the algorithm will tune the feed-forward parameters and the feed-back parameters simultaneously. Using the combination of feed-forward and feed-back tuning is an effective way to decouple the loops needed in flotation circuits where one circuit feeds into another. The advantages of adaptive controllers over conventional controllers will be introduced through the use of a simulator. Also discussed will the be the implementation of adaptive controllers at Brunswick Mining and some of the modifications that are available to help solve more difficult control problems.Brunswick Mining is located just outside of Bathurst, New Brunswick. The concentrator processes approximately 10250 tonnes per day of ore that assays at approximately 8.9 %zn, 3.6 %Pb, 0.3 r.cu and I 00 gram/tonne of Ag. The four products produced are zinc concentrate assaying 51 %Zn, lead concentrate assaying 34 %Pb, copper concentrate assaying 21 %Cu, and a bulk concentrate assaying 32 %Zn and 18 %Pb."

Jan 1, 1986

By Michael W. Neill, O&apos

The engineering profession generally does not accept vibro-driven piles as bearing piles unless their capacities can be verified by restriking with an impact hammer, which significantly reduces the economic benefits of vibratory driving. In part, the concern for capacity development in piles driven by vibration arises out of observations that vibro-driven piles do not develop capacities equivalent to those driven by impact (e. g., Mosher, 1987). Nonetheless, if capacities are predictable, vibratory installation may be more cost effective than installation by impact, due to savings in time of installation, even if capacities are lower than those of impact-driven piles. Throughout the past few decades, a number of attempts have been made to develop capacity prediction methods for vibro-driven piles, mostly along the same lines as methods for impact-driven piles. That is, (1) totally empirical formulae, (2) power balance / power transfer formulae, and (3) "time domain-nonlinear" (TDN) computational procedures such as the wave equation. Some of the formulae have been based partly on field experience, but the majority have been developed from simple theoretical models with parameters evaluated from laboratory studies. Neither these formulae nor the TDN solutions have been systematically checked (or modified) by recording appropriate field data over a variety of site

Jan 1, 1989

By Edwin W. Meyer

The augered cast-in-place piling technique was used to install deep foundations 20 feet into weathered sandstone. The project involved the upgrading of the Air Quality Control System (AQCS) for a 560 megawatt coal fired power plant located in Stillwater, Minnesota. The site subsurface consisted of 20 feet of overburden overlying weak sandstone. The overburden consisted of sands and gravels with cobbles and boulders, and variable thicknesses of peat. Ground-water at the site was approximately 8 feet deep. Two foot diameter piers were selected to facilitate installation through the cobbles and boulders in the over-burden and to penetrate the sandstone 22 feet. During installation of the first pier, the weak sandstone broke down to sand-sized material that could not be cleaned from the pier hole without the use of slurry to hold the material in suspension. However, the use of slurry would significantly impact both schedule and cost. Since the sandstone could be easily drilled with the pier equipment, it was believed that 2 foot diameter deep foundations could be installed as designed using augered cast-in-place piling techniques. A brief test drilling pro-gram was conducted to evaluate the viability of 2 foot diameter continuous flight augers penetrating 22 feet into the weak sandstone. The test drilling indicated that augered cast-in-place installation techniques should be successful. Following a short delay to mobilize the additional required equipment, construction commenced. Installation of the 2 foot diameter augered cast-in-place piling to a depth of 22 feet into the weak sandstone was successfully performed.

Jan 1, 2006

The prospect of utilisation of phosphate ores which contain high P2O5 values associated with Al and Fe has produced a great deal of interest over many years. Processing options have generally been based on the utilisation of by-products which were required to offset the processing costs.   This paper presents a range of processing options which have been investigated at laboratory or technical scale on phosphate ores which predominantly consist of crandallite, CaAl3(PO4)2(OH)5.3H2O and millisite, Ca(NaK)Al6(PO4)4(OH)9.3H2O. Christmas Island (Indian Ocean) and Mt Weld (Western Australia) phosphate ores are good examples of such feedstocks. It is expected that these processes may also be applicable to such phosphate ores from other locations.

Jan 1, 1990

By D. C. Oldroyd

Western Coalfield?s Tandsi Mine, has difficult support conditions and a history of roof falls, resulting in mining roadway widths and depths being restricted for safety reasons. Rock Mechanics Technology Ltd was contracted to improve the support system to allow the introduction of mechanised room and pillar mining. The introduction of a ?world best practice? bolting system resulted in major improvement in roof stability, allowing mining restrictions to be lifted and Tandsi to become one of the first two Indian mines to introduce a mechanised continuous miner system. The first year?s production was some six times previous levels. Because of the improvement in the support system, RMT was also able to design a partial de-pillaring system suitable for the Tandsi continuous miner districts together with the introduction of monitoring procedures and guidelines to maintain safe roof support conditions. In situ monitoring of pillar and roof behaviour was undertaken as the first pillars were extracted to confirm the design. De-pillaring operations have also proved highly productive, and to date there has been no associated support related major injury or dangerous occurrence. The success of this project demonstrates the potential for mechanised room and pillar mining in India.

Jan 1, 2006