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Consents Required for Overseas Persons Overseas Investment Regulations 1974 Foreign investment proposals must be reviewed by the Overseas Investment Commission to ensure that these are in accord with national interests. Consent must be obtained from the Commission for: 1. New investment proposals which include: a. An overseas person acquiring 25 per cent or more of any class of share in a company. b. A New Zealand company issuing shares to an overseas person where this will result in that person owning 25 per cent or more of the company. c. An overseas person acquiring business assets for consideration in excess of $100 000. d. An overseas person commencing business in New Zealand. 2. Borrowing in New Zealand: An overseas person must obtain consent to raise funds in excess of $300 000 in New Zealand. 3. Borrowing Overseas: New Zealand incorporated companies must obtain consent to borrow overseas. Current policy is borrowing will be approved where the loan is for a specified fixed term of one year or more.

Jan 1, 1982

By J. H. Morris, G. M. Steed

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. Oxygen isotope analysis indicates that quartz, carbonates and muscovite could all have formed in near-isotopic equilibrium with the mildly saline H2O-CO2 ore fluid at 330 degrees C. Calculated values for O, C and S in the ore fluids imply derivation from a deep, homogeneous source region and are consistent with formation either as a direct or an indirect result of igneous processes. Values for delta-O18 plot a little outside the accepted magmatic range, but have almost certainly been modified by exchange reactions with wall rocks. These reactions were also the most likely cause of deposition of the ore constituents. The chemical and isotopic character of the fluid was similar to that in many Archaean and later mesothermal auriferous vein systems, especially the Mother Lode region of California. If the Southern Uplands-Longford Down accretionary complex conceals an Ordovician arc, the tectonic setting was also broadly comparable

Jun 19, 1905

By S. Assemi

Interaction forces between a hydrophilic silica particle and an air bubble were measured by atomic force microscopy using simplified model systems with deionized water and dilute KCl solutions. Contributions from the hydrodynamic force were minimized by using a low piezo speed. Particle-bubble separation distance and the bubble spring constant were calculated from linear regression of the piezo extension versus cantilever deflection. The bubble surface potential was then estimated from fitting the AFM-measured forces to the Hogg-Healy-Fuerstenau (HHF) model, using the surface element integration (SEI) method. Surface potentials obtained for the bubble at a low applied force were comparable with the literature data, suggesting that the simplified model used here can give a reasonable estimation of the bubble surface potential under moderate applied forces. Interaction forces between a silica particle and an air bubble were also measured at different locations on the air bubble surface. The force curves obtained at the edges of the bubble fitted very well to the theoretical force curves regardless of the applied force, while curves obtained at the center and halfway to the center, were more difficult to fit, in particular at higher applied forces (> 13 nN), suggesting that force curves obtained at the edges of the air bubble might be less prone to deformation effects.

Jan 1, 2008

By Zeljka Pokrajcic

Crushing and grinding, or comminution, circuits are the most energy intensive process of a mineral processing plant. Comminution involves the physical size reduction of an orebody to a particle size sufficient for recovery of the mineral values. However, the comminution process remains inherently inefficient. The inefficiency is a result of the operating nature of comminution devices such as grinding mills, where transfer of energy between grinding media and particles in unconstrained and completely random. New comminution circuit design strategies are presented in this paper. The aim of the new strategies is to improve the overall efficiency of the comminution process and reduce the total energy consumption of a comminution circuit. The energy efficient strategies include the: ? rejection of coarse size liberated gangue from the comminution circuit and further downstream size reduction ? use of more efficient grinding and crushing equipment ? the selection of coarser particle product sizes to alleviate the increased energy intensity required to achieve finer product sizes Singularly and when combined, these energy efficient strategies can significantly decrease the overall energy consumption of a comminution circuit. This paper also explores the financial impact of certain energy efficient strategies using an analysis tool called EcoNomics?. It shows that substantial financial gains can be made by including more efficient technologies and methods in comminution circuit design.

Jan 1, 2010

By Paul Zinner

Efforts to win an enriched manganiferous product from the Missouri Valley deposits of South Dakota have included an application of most known ore-dressing devices and have been largely unsuccessful. At least two methods showed some promise of success and were the subjects of detailed Investigation by the Bureau of Mines during the period from July 1945 to August 1947. A series of mining and beneficiation tests were undertaken to determine conditions under which the most feasible concentration methods could be employed and to define the limits of such applications in terms of the character of the final beneficiated product. In the absence of a significant current market for any conceivable product of beneficiation, the extent to which applied methods might be considered successful was measured in terms of ratios of recoveries to grade, regardless of the adaptability of such beneficiated products to further metallurgical or direct usage. The results of all investigations show that production of a shale-free, concretionary, manganese-bearing product by any known method requires great sacrifices in manganese recovery. Products of beneficiation, with specifications permitting some inclusion of shale, can probably be most effectively produced by methods employing specialized jigging equipment as the principal functional unit of a process.

Jan 1, 1949

By James J. Scott

Research and development has been carried out on the patented Dynamic Rock Anchor, tradenamed DYNA-ROK and DYNA-ROK PLUS Anchors, which are manufactured and marketed by Ingersoll-Rand Company. This paper will present the results of field testing of this revolutionary new concept in ground control. Geologic conditions will be described where the plastic sleeve of the DYWA-ROK anchor alone is sufficient to provide anchorage and also, where in softer ground conditions, the DYWA-ROK PLUS is applied. The rationale for making the decision as to the type of fixture to be employed, the length of plastic tube to be used and the quantity of resin are explained. Pull test data will be shown from eight different coal seams in the Eastern United States where the product has been installed.

Jan 1, 1990

By J. Brent Hiskey

Thiourea is a reagent capable of complexing gold and silver. With the proper oxidant, thiourea can effectively dissolve metallic gold and silver. A thiourea leaching system possesses potential advantages over conventional cyanidation including acidic solutions instead of alkaline, cationic complexes in contrast to metal-cyanide anoionic complexes, and faster leaching rates with acidic solutions of thiourea. Generally, the rate of metal dissolution in thiourea solution is fastest when ferric ion is employed as an oxidant. Acidic thiourea solutions for certain applications could offer a nontoxic and noncorrosive option for processing gold and silver. This paper provides information regarding the fundamental chemistry of the acidic thiourea system, and reviews the dissolution of both silver and gold in acidic solutions of thiourea. The recovery of gold and silver from acidic thiourea solution is discussed.

Jan 1, 1981

By V. A. Akinbinua

This work is intended to examine the relationship between rock fragments produced during compression tests using a soft testing machine, e.g. hydraulic press (the machine used in this work is Amlser rock testing machine), and the rock fragments size distribution produced by fragmentation of the same rock through application of explosive. The rocks tested are fine grained marble, medium grained tonalite and fine-medium grained granite, medium grained norite and medium grained gabbro. The rocks types are prepared according to ISRM methods to be tested for strength determination. The rocks are loaded at constant load until failure. The fragments resulting from the failure of each of the rocks types are collected for size characterization by sieve analysis. The same rocks tested under soft testing machine are also prepared into blocks of dimension 150 mm length x 100 mm width x 100 mm height for blasting by explosive application. Each block of the different rocks are drilled through with an 8 mm diameter drill to a depth of 80 mm. Each of the holes on the blocks is spaced from each other at 44.7 mm and with a burden of 28 mm. The holes therefore formed a rectangular blasting pattern. Each of the holes was charged with a 720 mg electronic detonator and fired instantaneously inside a cylindrical blasting chamber. After each shot, the fragments are collected for size characterization. The sizes distributions from blasting are compared with sizes distributions resulting from rock testing using the parameter Xc of the Rosin-Rammler distribution function (RR) and 75% cumulative percentage passing. The analysis and finding from this work is presented in this paper.

Jan 1, 2014

By Gary B. Petersen

The author has developed a seven-step process called the Applied Rock Mechanics (ARM) Protocol that the author has used to solve numerous roof stability problems in mines throughout North America since 1975. It is a practical evaluation process using trained observation, innovative data collection instrumentation, video borehole cameras, analytical processes, and controlled testing methods that have become highly effective in solving ground control problems in every type of underground mine. This paper will describe each of the steps of the protocol and how the rock mechanics engineer applies them to resolve a typical ground control problem.

Jan 1, 2012

By Robert J. Timko, Charles D. Taylor, Edward D. Thimons, Tom Mal

A test system was developed for measuring airflow in the National Institute for Occupational Safety and Health (NIOSH) ventilation gallery using a three-axis ultrasonic anemometer. The gallery was used to simulate face airflow conditions in underground mines having a blowing curtain. Airflow data collected at multiple sampling locations between the face and the end of the curtain were used to draw airflow profiles for different curtain setback distances, intake flow quantities and entry widths. In addition, methane was released at the face, measured at the sampling locations, and displayed as methane distribution in the area between the curtain and the face. Entry geometry had a significant effect on airflow patterns, and the flow patterns affected the distribution of methane in the entry. Flow measured at and parallel to the face was a good predictor of methane dilution and removal within two feet of the face.

By H. Krogerus, P. Jokinen, T. Lintumaa

The energy consumption and recovery of chromium are important economic factors in ferrochrome production. Outokumpu has a lot of experience of the reduction behavior of the sintered pellets in industrial-scale furnaces and also on the grounds of numerous laboratory and pilot-scale investigations. Sintered pellets have shown a superiority over lumpy ore and briquettes made of the same chromite grade. The good performance of the pellets has also resulted in investigations on the reasons for such a performance. In this study, the factors affecting pellet behavior in smelting furnace were investigated. This study is divided into two sections, i.e. the investigations were on the factors affecting solid state reduction and on the factors affecting reduction under melting. These tests were performed by means of thermo gravimetry and by smelting tests. The correlation between the pellet characteristics and reduction behavior was shown and its influence on industrial-scale furnaces was discussed. Factors worth of consideration are for instance, the extent of oxidation during sintering, slag formation and chemistry in respect of molten state reduction, and the grain size of the chromite mineral in the raw material in respect of kinetic reasons (retention time in smelting).

Jan 1, 2007

By Vinay Kumar

The present investigation describes R & D studies carried out for recovery of copper from the sulfate solution expected from the leaching of e-wastes in presence of minor constituents such as cadmium, zinc and nickel using solvent extraction process. In order to extract copper in continuous mode in mixer settler unit (MSU), basic studies have been made to optimize the experimental condition using 5%LIX84 in kerosene. Subsequently, the solvent extraction of copper was made in MSU maintaining leach solution flow rate 4.0 L/h and A/O ratio 1. The results showed complete extraction (~97%) of copper in three stages at A/O ratio 1 from the aqueous solution containing 1.98g/L Cu at pH 1.91 in presence of impurities. Loaded metal was completely stripped after scrubbing with 10% sulfuric acid in two stages. The stripped solution could be used for metal/ salt recovery by electrolysis/ crystallization.

Jan 1, 2010

By S. Underwood

The tracer gas method of conducting ventilation surveys is a means of determining air quantity in underground mines with knowledge of the concentration of the tracer in the atmosphere and the flow rate at which the tracer is being released. The technique is useful in inaccessible areas of underground mines and areas where traditional point measurement of velocity is not practical. Sulfur hexafluoride (SF6) is the industry standard tracer(Kennedy 1987) used in underground mines because it is safe, stable, and not naturally occurring in the mine environment. The implementation of a second tracer will increase the versatility of the tracer gas technique allowing for simultaneous releases for the study of interrelated ventilation circuits, and for conducting multiple experiments in less time. This paper will detail the selection of perfluoromethylcyclohexane (PMCH) as a novel tracer with sensitivity, physical properties, and analysis characteristics similar to SF6. Methods for the release of liquid PMCH into underground mines will be recommended, and the vulnerabilities of sample loss due to condensation of vapor PMCH will be explored. Finally, the benefits and implications of using PMCH as a second tracer will be discussed.

Jan 1, 2012

By R. M. Waterstrat

X-ray diffraction and metallographic examination of binary Mn-rich alloys with Ti revealed the presence of intermediate phases in this system. A binary R phase has been identified and also a phase having an a-Mn type structure. The X-ray pattern of the phase TiMn3 is presented and a tentative phase diagram for the Mn-rich portion of this binary system has been constndcted. MANGANESE-rich alloys with titanium have been subjected to thermal analysis at temperatures down to 1100°C by Hellawell and Hume-Rothery.1 Their results indicate the existence of an intermediate phase TiMn3 in this binary system. This phase appears to coexist with the Laves phase TiMn2, and with terminal solid solutions based on the allotropes of manganese, at least down to 1100°C. The above investigators did not attempt to determine the crystal structure of this phase, however. Since, by analogy to the binary systems Mn-V and Mn-Cr3 one might expect to find a phase in this region of the diagram, it seemed desirable to obtain X-ray diffraction patterns of alloys in the concentration range in question, in order to ascertain whether the sigma phase or related structures occur. EXPERIMENTAL PROCEDURES Alloys were prepared by arc-melting electrolytic manganese and iodide titanium in a water-cooled copper crucible under a helium atmosphere. Excess manganese was added to each melt in order to allow for losses incurred during melting. The alloys were then wrapped in molybdenum foil and sealed in evacuated quartz tubes for annealing at various temperatures, as shown in Table I, followed by quenching in cold water. Although the inside of the tubes showed evidence for some loss of manganese from the specimen during annealing, there was no evidence of any reaction between the specimen and either the molybdenum foil or the quartz tube at these temperatures. It was later found that the manganese loss was considerably reduced by annealing these alloys in sealed quartz tubes containing one atmosphere of purified argon. As an added precaution the surface of each specimen was ground off before crushing the alloys to -270 mesh powder, using a hardened steel mortar and pestle. X-ray powder patterns were obtained using either FeKa or CrKa radiation in an asymmetrical focusing camera, which gave excellent dispersion of the closely spaced lines. Pictures were also obtained using a Debye camera of 5-cm radius which provided data in the angular region not covered by the focusing camera. The alloy specimens were polished and examined metallographically, using an etchant consisting of 60 pct glycerine, 20 pct nitric acid, and 20 pct hydrofluoric acid. The 10-g buttons were in each case broken in half and found to be well-melted and free of any gross segregation. One half of certain alloy buttons was submitted to chemical analysis in the "as-cast" condition. No appreciable change in composition seemed to occur during annealing . RESULTS The X-ray pattern of alloy Ti1.17Mn0.83 was found to agree well with that of the ternary R phase which was first found in the Mo-Cr-Co system,' and re-

Jan 1, 1962

By G. Bourque

One of the design criteria for the Mount Wright facilities was to incorporate the latest proven automation techniques and devices for the new crushing, grinding and concentrating plant. The heart of the centralized control system is a Fox 1 process computer, located in the central control room in the administration building. The entire operation, i.e. crushing, conveying, storing, grinding and concentrating, is monitored and controlled, through the process computer , by one operator via a CRT console. In case of computer failure, the control is automatically, and without process interruption, transferred to manual back-up panels. One of the newest management tools, the process computer is programmed to collect and automatically print out shift. daily and monthly reports on tonnage, metallurgy and equipment operating time, for better planning of operations and preventative maintenance.

Jan 1, 1977

By D. Nutakor

Rock joint stiffness is not only a poorly known parameter, but also has no established laboratory measurement procedure. This paper presents methods used to determine the normal and shear stiffnesses of healed joints filled with vapor-altered minerals obtained from the Yucca Mountain site in Nevada. Results show that these joints behave linearly up to 85% of their loading history and are stiff with strengths very close to the strength of the intact rock. Factors that might have contributed to the linear behavior of these joints are discussed and areas requiring further investigation are provided. Joint normal stiffness ranges from 7.16 to 64.77 GPa/mm with an average value of 26.93 GPa/mm, while joint shear stiffness averages 11.41 GPa/mm and ranges from 3.09 to 28.41 GPa/mm. Young?s modulus of the vapor-altered joint infilling was calculated from the stiffness of the healed joint. Young?s modulus of the vapor-altered joint filling material averages 7.89 GPa and ranges from 2.15 to 19.43 GPa. Given the pervasive presence of such altered rock, usually in the form of sub-spheroidal 3-D pockets, this property should be of value in any numerical modeling attempting to describe the mechanical behavior of these tuff formations at the level of detail where inclusions might be a factor.

Jan 1, 2008

By R. Flatabø, K-E. Johansen, L. Hunsbedt, P. M. Cowx, J. A. Bustnes

Eramet and Tinfos are two producers of manganese alloys in Norway, which have worked hard for several decades to improve both the internal and external environment. Furnaces producing ferro- and silico- manganese alloys generate large amounts of off-gas that contains substantial amounts of dust, heavy metals and organic by-products. The dust is separated from the gas in venturi scrubbers by washing with water. The water is cleaned and recirculated, and the surplus water coming from moisture in the raw materials, is discharged to the adjacent fjords after further treatment. Emission figures show that the discharge of suspended solids, manganese, zinc and PAH (polycyclic aromatic hydrocarbons) have been reduced substantially over the last three decades as a result of process improvements and installation of state of the art environmental control measures. The two plants were the first world wide to install mercury cleaning of the off-gases from the furnaces. Mercury emission reduction has exceeded 90%. Concerning other environmental issues, such as utilisation of off-gases for energy recovery and chemical purposes, both plants have achieved good results. Major effort in the environmental work has come from the plants themselves, but other players like FFF, The Norwegian Ferroalloy Producers Research Association, and SFT, The Norwegian Pollution Control Authority, have contributed to the achieved results.

Jan 1, 2007

By Javier Rodriguez

Adaptive re-use of existing structures in urban environments has become very common due to lack of available space in our cities and requirements for increased structural capacity. Often, it involves retrofitting existing foundations to support increased loading. In such cases, Engineers face the need to review existing deep or shallow foundations for their true load carrying capacities in order to determine the required magnitude of retrofit work, if any. To accomplish this, the engineer must track down and cull through the existing construction documentation to determine what was actually constructed, complete an investigation to confirm these conclusions, possibly sample the foundation elements for strength properties, and on occasions complete non destructive or full scale load testing of indicator elements. This paper describes the typical procedure followed by the authors for design of retrofit schemes for existing buildings in the Washington DC metropolitan area. Three case histories are presented that illustrate various issues encountered during design.

Jan 1, 2006

Cyclone Process for Heavy Metals Decontamination of Sediments

Sep 13, 2010

By N. Jayaraman, V. Srikant, A. Radhakrishna

Addition of a 500 MW unit to the existing units at Ramagundum Thermal Power Station requires blasting of large volumes of rock very close to sensitive installations like Turbo generator, Generator transformer and Power cycle equipments. Levelling of the areas and excavations for footings are, therefore, to be carried out cautiously. The existing sensitive installations should be protected against ground vibrations and flyrock. The paper describes the details of a few of the many blasts carried out successfully wherein the ground vibrations were restricted and flyrock was avoided.

Jan 1, 2003