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This paper first describes the essentials of the slurry shield method and its achievements, then problems encountered during driving tunnels and their countermeasures, and finally shows problems to be solved in the future. The author works at Tekken Construction Co., Ltd. as a director. All the data cited are based on material gained from the slurry shield tunneling works undertaken by the said company. The mark, viz*, indicates that Tekken Construction Co., Ltd. has obtained or is applying for a patent in the U.S., Europe and Japan. 1. CONSTRUCTION RECORDS BY SLURRY SHIELD METHOD AND ITS PROBLEMS (1) Shield machines in the future should have the following characteristics; a. to be able to drive less cohesive soil b. to make no change to the ground water table level c. to make it possible to let people work in normal air pressure d. to cause less settlement at the surface To meet the above conditions various kinds of mechanical shields have been are tried, viz. limited air pressure type, rotary cutter with slit regulator, screw-discharge type, blind shield, etc. As far as the author knows, however, they are not 100% successful. Tunnels need their own accuracy in accordance to the usage. Both ease of driving

Jan 1, 1976

By K B. Barnard, M D. Urbani

A synergistic solvent extraction (SX) system for nickel and cobalt recovery using Versatic 10 and decyl-4-pyridinecarboxylate was tested with BHP Billiton pilot plant leach solution. Another synergistic SX system for cobalt and zinc recovery was successfully tested using Baja MiningÆs pilot plant leach solutions. Synergistic SX systems have also been developed to separate iron, zinc and copper from nickel and cobalt for Minara Resources and to separate manganese from magnesium and calcium in waste stream for HiTec Energy. The gypsum precipitation problem at the former Bulong operation could have been alleviated using a Versatic 10 and CLX50 synergistic SX system. These synergistic systems have shown high selectivity for target metals over impurity metals and would largely improve SX plant operation. Maintaining a æhealthyÆ organic is very important for efficient plant operation. Careful analysis of plant organic at CSIRO has been used as a tool to pre-empt and/or solve problems in operating circuits. Work performed to assist operators has included assessing plant organic solutions to highlight impurity build-up with time, assessing reagent stability under prescribed operating conditions, correlating organic composition with impurity transfer and crud analysis. An independent estimate has determined that work in this area by CSIRO has provided over $50 M in benefits to the industry.

Jan 1, 2005

The application of modern sciences prior to nineteenseventies have resulted in the placing of Continental Drift theory into broader concept of Plate Tectonics. The concept is applied to explain the Cenozoic Tectonics of North Sumatera.Oceanic crust flooring the Indian Ocean is moving northeasterly and being obliquely subducted at a Benioff zone along the western margin of Asian Plate, marked by the Sunda Trench in the west coast of Sumatera. This phenomenon was generated since late Mesozoic, continued during Cenozoic era up to present day, resulted an exellent example of arc-trench system which can be traced along SW - NE transect of North Sumatera.The oblique-subducting plate of Indian Ocean beneath Asian Plate, together with spreading of Andaman seafloor beginning in Pliocen epoch, have led to the origin of Sumateran Fault System; the System extends throughout the length of Sumatera island. In the region under review it comprises almost contiguous set of broadly SE-trending. Evidences for transcurent-dextral displacement have been observed.

Jan 1, 1990

Cataclysmic or flood-like release of gas-charged brines, hydrocarbons and slurries accompanied widespread mineralisation of Upper Devonian environments. These are well represented in the Canning and Burdekin Basins of Western Australia and Queensland respectively.The Burdekin Basin provides particularly instructive vein structural sequences. These fall into organic residue to carbonate paragenetic sequences which are known elsewhere to record progressive decarboxylation. Fibrous veins indicate overpressure in fractures with organic residues, acids and gas derivatives driven to overlying groundwater flows. This combination of large flow rates and potent organic mineralisers led to extensive arsenical rare-metal mineralisation which is similar to that concentrated in Upper Devonian extinction horizons of the Canning Basin. Organic-residue mineralisation appears concentrated by certain hvdrostructures and targeted upon particular species. These controls need to be understood to guide modern management stragegies for mineralised organic and nitrogenous wastes.

Jan 1, 1990

By Paton T. P

In the technical sense, as well as in the professional sense, the word 'model' can have many meanings. More than 23 000 references were uncovered by a simple literature search on keywords ' MO D EL#. and. (META LLURG#. or. M I NERAL#)' . For the purpose of this paper, 'models' will be considered to be mathematical formulations which attempt to represent or approximate a process. The model may be purely, or a combination of: ò fundamental models, based on the laws of physics, chemistry and thermodynamics; ò semi-empirical or phenomenological models, where an intuitive concept of the process is formulated and found by testwork to fit observed behaviour; and ò empirical or 'black-box' models (including neural networks), where a mathematically convenient form is proposed and fitted. Even under this more restricted definition, which eliminates heuristic and statistical 'models', it is clear that the efforts expended in devising and using models have exploded during the years since the first APCOM Conference in 1961, benefiting from the dramatic decrease in the cost of computer power. This paper reviews the areas of usage of computer modelling in the metallurgical and mineral processing industries, from plant design, through off-line support, to on-line modelling and automatic control. In each area, frontiers of new development of the technology are mentioned. It is noted that, while modelling is now standard practice in design, it is not yet the norm in operating and controlling plants. The reasons for this partial acceptance are, it is argued, less related to the limitations of the technology than to the human and organisational factors involved in transferring technology to implementation.

Jan 1, 1995

By Takiuchi T, Kurita M, Owada S

This paper describes the possibility of the application of flotation to the separation of monazite from xenotime and of columbite from ferberite, which have been said to be difficult with generally used physical beneficiation methods. For Malaysian monazite and xenotime samples, a great difference is observed between the flotation recoveries at pH 7.5 using 1.0 x 10-4mol/1 dodecylammonium chloride (DAC). The grade and recovery of columbite in the binary flotation with both minerals result in 85 per cent and 67 per cent in the cleaning froth and 91 per cent and 51 per cent in the re-cleaning froth, without adding any scavenging stages. For monazite samples from various localities, the flotability is dominated by the electrostatic interaction between mineral surface and collector ion using DAC as collector, but the singular decrease of flotation is observed in the sample of which the crystallinity is low and the surface structure is rugged and complex. Otherwise, ferric ion in the flotation system probably dissolved from mineral is found to activate the flotation using sodium dodecylsulfate as collector. For columbite and ferberite, the separation is judged possible at pH 3.0 using 1.0 x 10'3mo1/l sodium oleate (NaOl) from the single flotation results of each mineral. In the binary flotation, however, columbite recovery in the froth is greatly diminished below that expected. This would be because NaOl is prevented from adsorbing on the columbite surface of which the charge is transformed more negative side by the specific adsorption of the tungstate ion dissolved from ferberite.

Jan 1, 1993

Increasing demands on quality of metallurgical grade alumina and for lower production costs led to the development of a new fluid bed calcining process. The process, jointly developed in Germany by Vereinigte Aluminium Werke A.G. and Lurgi Gesellschaften m.b.H., takes advantage of modern chemical engineering methods such as counter-current flow of combustion air and solids, direct heat-exchange between combustion air and fine solids and near stoichiometric combustion of oil in a fluid bed. Using a two-stage Venturi-type suspension preheater for heat-recovery from combustion flue- gases, the circulating fluid bed technique with internal oil combustion at 2.2000 F for the calcining step and 'a five-stage fluidized bed cooler for heat recovery from calcines, the process gives an outstanding heat- efficiency. In a first industrial plant for 560 sh. t. alumina per day heat consumption figures of less than 1.400 BTU/lb A12O3 were achieved.

Jan 1, 1971

A major tool in the search for petroleum is reflection seismic mapping. The period which has seen most of the exploration in Victoria is also one which has seen major advances in this technology, from 1963 try present day. Seismic mapping can be divided into three interlinked areas - acquisition, processing, and interpretation. In acquisition the major changes have been from an explosive energy source in 1963 to gas exploders in 1968 and airguns in 1970. The number of recording channels has increased from 24 to 192, with digital recording introduced in 1966, and floating point recording in 1976.

Jan 1, 1982

By Veal FL

Technological changes in Portland cement manufacturing during past years have reflected changes in the economics and availability of various types of fuel such as coal, fuel oil and natural gas. The industry consumes a sig- nificant quantity of both thermal and electric- al energy. The nature of the process and its chemical constraints does however permit the use of comparatively low grade fuels such as high ash coal and high sulphur oil. In striving for increased daily kiln outputs and conservation of energy, there is a worldwide trend towards the use of dry process plants. Wet process kilns of about 2 500 tonnes per day assume massive component sizes which present difficulties in manufacture, and transport to plant sites. Large capacity dry process units in excess of 8 000 tonnes per day are now in operation using precalcination techniques in which part of the fuel is introduced in the static preheater section ahead of the kiln while the balance is added to the kiln in a conventional manner. This technique has virtually doubled the potential output of any given single kiln.

Jan 1, 1976

In-situ leaching of gold deposits has not become an option largely as a result the lack of suitability of cyanide as a lixiviant due to sluggish kinetics and high dependence on the availability of oxygen. A second problem area is the excessive cost of drilling the required number of injection and production wells needed to service a wellfield capable of maintaining any significant throughput or providing and acceptable level of gold production. Well spacing in in-situ leaching operations is limited by solution life, dissolution rate, and the need for solution control. With cyanide the life of an active solution capable of dissolving significant gold is severely limited by the availability of oxygen which cannot be readily replaced while the solution remains underground. The extremely slow gold dissolution rate also necessitates excessive contact periods in order to dissolve coarse gold.

Jan 1, 1991

By Xueqiu H

Since the hypothesis of coal and methane outburst mechanisms based on elastic mechanics gives no consideration to time, it cannot give satisfactory explanation of the outburst occurrence and its development. A creep mathematical model of coal containing gas has been set up through creep tests and analysis under a condition of triaxial compression. Such a model can explain the phenomenon of coal and methane outbursts successfully. The tests proved that there is no essential difference between the rheological properties of prone outburst coal and non-prone outburst coal. Outburst can take place in any kind of coal if the rheological conditions of coal containing gas are met. The creep mathematical model provides a basis for establishing a comprehensive index of coal and methane outburst potential.

Jan 1, 1992

By Cornwell P. J

The Pajingo ore bodies consist mainly of auriferous quartz veins hosted by a suite of hydrothermally altered andesitic pyroclastics, volcanics and epiclastic sediments. Scott lode, the main economic deposit in the area, lies in a zone of major structural disruption and contortion. High grade gold and silver mineralisation is selectively mined by open pit methods. Standard grade control techniques and extraction methods were adapted to minimise mining dilution and to maximise metal recovery. Basic blending of grade ranges at the crusher has produced an average 10 gram/tonne gold head grade. The estimation of ore reserves calculated by both standard polygonal and geostatistical methods proved acceptable. Mineable reserves when compared to in pit reserves defined by blast hole drilling, indicate a decrease in tonnes and an increase in the grade resulting in an acceptable comparison of the total ounces of contained gold. The ore reconciliation of mined against milled ounces indicates that both ore reserve and grade control models underestimate the metal content in the orebody. Sampling techniques are being examined in an attempt to reduce this discrepancy.

Jan 1, 1989

Many of the large refrigeration plants used in, the cooling systems on deep South African gold mines are situated on surface where they are exposed to seasonally and diurnally varying climatic conditions, and to a diurnally varying demand for cooling made by the mine. It has been traditional to accommodate the seasonal variation in climate by manual control applied to the plants at appropriate times of the year, and the plants have normally been specified to conform passively to the diurnal variations. This paper introduces new strategies for the active automatic control of the plants on a diurnal cycle, and shows that attractive benefits in energy and chilled water resource management can be accrued through the use of these strategies. The results have been derived through the modelling and simulation of a representative refrigeration plant.

Jan 1, 1985

By Smele J. S, Dawes W. D

In recent years there has been a trend among mining companies to diversify exploration and development away from the countries that have dominated mining activity for the latter half of this century. With some exceptions, this trend is accelerating and is a function of the recognition that many parts of the world, with no previous exposure to modern exploration, are endowed with considerable mineral potential. In addition coincident with changing political and economic circumstances, many countries have recognised the benefits of attracting international mining investment and have radically changed policies, fiscal and legal regimes so as to encourage exploration and mining. Some countries, however, have not readily accepted mining for cultural or social reasons and have yet to make effective changes to mining legislation. For historical reasons, other countries may have little or no direct experience of western economics, nor may they fully recognise the need for stability and competitive fiscal and legal systems to attract foreign investment. Not all ventures in new countries have been commercial successes and there have been some lamentable and recent lapses from grace. Company strategies, company standards and management objectives can also vary widely from company to company. What may be an acceptable risk or rate of return for one may be completely

Jan 1, 1997

LESLIE BRADFORD GOLDEN JUBILEE ORATION "Not only a metallurgist but a scientist of the highest order" Leslie Bradford and the Australian Metallurgical Industry

Jan 1, 1987

By Roberts C

The satisfactory testing and characterisation of mineralisation amenable to heap leaching, is of prime importance to successful operation of a project. This paper outlines a methodology for assessing material suitability. A general model is used for classing material types for suitability for treatment and for economic analysis. The four levels of these are overburden, oxide, transitional and unoxidised materials. During exploration, reverse circulation (RC) drilling can be used effectively to define these zones by a combination of logging, analysis and provision of cuttings for column leach and bottle roll trials. RC cuttings can he used effectively for column leach trials, when calibrated against conventional processing-sized samples, obtained from surface. Tbis allows metallurgical testing to depth and definition of transitional ore types and the base of oxidation, accurately and economically with an acceptable density of samples. The accurate prediction of base of oxidation and variations in recovery with depth and ore types can be used to develop 'economic' pit designs with zones of variable recovery. Petrological studies of leaching results and examination of mineralisation types carried out on concentrates, provide information on gold distribution and physical and chemical constraints. The examination of concentrates can be particularly useful for types of mineralisation when overall gold content is frequently at or below one pan per million. Explanation of anomalous recovery of gold grains in dense goethite and solution-robbing by carbonaceous material can be identified by use of petrological and scanning electron microscope. An understanding of the role of the host rock in leaching characteristics can also he provided by petrology where siliceous or clayey materials can require significantly different treatment.

Jan 1, 1994

This paper briefly reviews the history of mine haulage trucks. It reviews producti- vity limitations with respect to size or speed. Changing haul requirements once again create the need for more flexible mechanical drive power transmission equipment. The new equip- ment however is designed to provide extended life between overhauls as compared with previous mechanical transmissions.

Jan 1, 1981

By Richards BG, Komdeur W

Instability in spoil piles and in high wall slopes in natural overburden has been ex- perienced at Utah's Goonyella Mine since com- mencement of operations in early 1971. Annual production targets, although gener- ally met since the commencement of operations, required modifications to stripping and mining techniques and the rapid re-scheduling of oper- ations around unstable areas, but culminated in the earlier than planned acquisition of addit- ional stripping equipment. An understanding of failure mechanisms was developed within a collaborative study of pitwall instability between Utah Development Company and the C.S.I.R.O. Division of Applied Geomechanics. Results showed that pitwall instability occurs as structurally controlled deformations along planar failure surfaces; spoil pile failures are precipitated by moist- ure ingress and subsequent loss of strength of base layer materials; highwall failures de- velop over areally extensive bedding planes in conjunction with inclined and subvertical fractures caused by overburden blast damage.

Jan 1, 1978

By Le V, Nguyen Ngoc Quynh, R H. Murfitt

The Truong Son Fold belt in Indochina hosts the significant Sepon gold-copper district (Laos) and the similar gold-basemetal districts of Phuoc Son and Bong Mieu (Vietnam). With over seven years of exploration, Toronto-listed Olympus Pacific Minerals Inc, is one of few foreign companies that have to date made a substantial investment in mineral exploration in Vietnam.Much of this work has been conducted along the Phuoc Son û Tam Ky Suture, on the south-eastern limb of the Truong Son Fold belt on the Vietnamese side of the border with Laos. These programs have produced a significant number of gold prospects at varying stages of exploration development. The Phuoc Son û Tam Ky Suture is a major Paleozoic subduction zone that extends from northern Laos, through Central Vietnam and out into the South China Sea.It represents a Lower Mesozoic collision zone between the Paleozoic-age Truong Son fold-belt terrain to the north, with the crystalline terrain of the Pre-Cambrian Kontum Block to the south. Since its formation, it has been a locus of deep faulting, continental accretion, intensive intrusive activity and mineralisation. This paper briefly discusses the geological setting, structure, metamorphism, mineralisation, exploration history, and proposed mining development of the Olympus Phuoc Son Gold Project, with particular reference to the Phuoc Son û Tam Ky suture.

Jan 1, 2004

By Quast K. B

Samples of limestone and micaceous hematite have been ground in a laboratory batch mill using equal weights of either rods or balls. Values of the Schuhmann distribution modulus, a, have been shown to depend on grind time and do not remain constant as often reported. The linear reduction in a with grind time was attributed to a change in grinding mechanisms with time. The product sizing from ball milling limestone showed a bimodal distribution, but rod milling produced a unimodal size distribution. The product sizing from milling micaceous hematite was difficult to interpret due to the major influence of the shape factor on the transition from screen sizing to cyclosizing.

Jan 1, 1995