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By J C. Furness, F S. Cannon

Metal casting operations are a significant source of hazardous air pollutants. In particular, high production iron foundries emit significant quantities of volatile organic compounds (VOCs) during pouring, cooling and shakeout of iron castings made in green sand molds. End-of-the-pipeline capture and destruction methods to reduce VOC emissions add crippling costs to foundries. Alternately, the incorporation of advanced oxidants (AO) into metal casting green sand systems has been shown to reduce emissions from high production iron foundries in the US, and at the same time reduce operating costs. Cost savings are driven by the benefits of AO in clay recovery systems. Emissions reductions are the direct result of cascading AO-based reactions taking place in green sand molds. This sustainable greening of the metal casting process is a prototype for the development of other AO and non-AO process-based solutions for sustainable high temperature processing of materials. Fundamentals of AO technologies will be discussed along with the performance characteristics of AO processing systems in the metal casting industry and the breadth of other processing and remediation applications for which AO technologies have the potential to be successfully employed.

Jan 1, 2002

By A J. MacDonald, M P. Raffield

The South Deep massive orebody consists of 20 to 30 m of payable conglomerates ranging in dip from 11¦ to 20¦ and at depths of between 2400 m and 3400 m. The mine design process selected a mining method with a proven record of application that could be adapted to overcome the inherent difficulties associated with the depth, thickness and structural influences of the South Deep orebody. A modified cut and fill mining method provides a concentrated and highly flexible method of extraction. An integrated destressing cut will enable the modification of the stress environment such that it is suitable for massive mining operations. The choice of backfill type and stoping width in the destressing cut ultimately determines the characteristics of the stress modification and, as such, is critical to the success of the cut and fill operation. This paper discusses the decision process undertaken to determine the optimum backfill type and stoping width combination in terms of, conditions in the destressing cut faces and in the massive mining environment. Numerical modelling has been extensively used to analyse various scenarios to aid in the decision process.

Jan 1, 1998

By J Austin, R Bitencourt

Differences between the long-term model (LTM) and mine geology system (MGS) grade control block-outs on a blast block scale can impose difficulties to planning crusher feed grade and tonnes on a monthly to weekly blend basis. Detailed geological input to short-term planning has been integral to improve the performance and reduce risk in six-week to three-month production schedules and local variability in tonnage and grades is often not accurately represented in the LTM. The challenge of producing to combined target specifications from different mine sites in an integrated mine to ship business has been reduced with the creation of blast blockout-based short-term model. These short-term blast block models (STBBM or STM) are robust predictive tools created for upcoming benches of current mining areas by firstly collecting data from the pit in the form of bench and face mapping and projecting the structure and stratigraphy down to the next bench. A wire-frame of the projected contacts based on material destination from production blockouts is created and then checked against the LTM. Blast block data from the bench above including assay results and material logging is extracted and validated according to the projected wire-frames (geozones). Individual blast blocks and a full block model are created for each bench production defined by the STP (bench plans). Data output from the STM is in a compatible format for import into scheduling specific software packages. Additional information is incorporated into the STM to allow querying of drill penetration rates, predicted powder factors, material hardness and feed type to further aid in the production planning process and cost forecasting. To date, reconciliation of the STM has been pleasing and certainly an improvement on the LTM, especially in areas where variability is higher due to geological complexity. Short-term predictions derived from in-pit geological observations allow mine planners to more confidently decide on mining block sizes and schedule tonnages and grades, reducing the risk component attached to developing production schedules based directly upon long-term orebody models and mine plans.

Jan 1, 2005

By Konishi Y, Morioka Y, Okabe K

A part of the results of dissection survey of Chiba No.1 blast furnace, Kawasaki Steel Corporat- ion, is presented. Distributions of coke size and of slag and metal holdup are shown in the region of the dropping zone. A similar relation to the irri- gated packed bed is obtained. The distribution of coke size, coke temperature and liquid holdup are measured in and around the raceway. The shape of raceway in the horizontal and vertical sections indicates that each raceway worked individually. Liquid flow in the dropping zone and around the raceway on the basis of holdup measurements is Discussed.

Jan 1, 1981

Radioisotope X-ray and neutron techniques of analysis can be used for the determination of a wide range of elements in minerals. The most important applications of these techniques to the mineral industry are for on-stream analysis of slurries and solids, and for geological assay. The radioisotope X-ray techniques are the more developed ones and two installations for on-stream analysis are in routine use in mineral processing plants in Australia. Neutron techniques are being developed, and should prove valuable for geological assay of large numbers of mineral samples, for borehole logging, and for specific on-stream analysis when the cost of the equipment is warranted.

Jan 1, 1969

By J van Niekerk

The BIOX« process for the treatment of refractory gold ores and concentrates has been commercially in operation for 18 years. A total of six BIOX« operations have been successfully commissioned since the commercialisation of the process. Four of these BIOX« plants are still in operation today. There has been a renewed interest in the process the past few years with two BIOX« plants, the Suzdal plant in Kazakhstan and the Fosterville plant in Australia, scheduled for commissioning during 2004. Four new projects are also in various stages of development and are currently scheduled to be commissioned during 2005 and 2006. Research into the process are currently focussed on the two highest operating cost items for the commercial operations, namely power for agitation and air dispersion and cyanide consumption during leaching. Laboratory aeration and agitation testwork using the A340 up-pumping agitation system has shown that similar mass transfer rates can be achieved at slightly higher agitator power. The up-pumping system, however, eliminates the need for a separate blower and sparger system as air is introduced into the slurry from the slurry surface. The use of the thermophile bacteria as the final oxidation step during biooxidation has shown great promise. Reductions in cyanide consumption of up to 50 per cent were achieved when using the combination mesophile and thermophile process compared to standard BIOX« product solids. The combined process takes advantage of the milder oxidising conditions of the well known BIOX« process for the bulk of the oxidation and then uses the high temperature thermophile bacteria to complete the oxidation. The ASTERÖ process for the biological degradation of cyanide and thiocyanate containing effluent solutions has been proven to be efficient and stable. The process uses an activated sludge system with a residence time of approximately six hours in the sludge reactor. Heavy metals and metal cyanide species have also been shown to be removed successfully from solution.

Jan 1, 2004

By Woods PW

Consulting Engineers have been used in the mining and metallurgical industries for many years. The traditional role of the consultant overseas has been one of assisting with conceptual design right through to con- struction and commissioning as well as on occasion acting solely in specialist fields. This role developed because mining companies wished to concentrate on building up the permanent organisation they require to operate their mines and treatment plants without the traumas of increasing staff for the design and construction period and reducing it on completion. In Australia where there have been few individual minerals projects of magnitude (until recently) companies have looked after their own detailed engineering and construct- ion management employing consultants mainly in specialised fields.

Jan 1, 1975

By A Benedictus, A Butcher, J Wikstr÷m, B Lindblom, E Rutqvist

LKAB is a mining company situated in northern Scandinavia, manufacturing blast furnace- and direct-reduction pellets and sinter fines. Pellet development at LKAB comprises testing at laboratory and pilot scale. The LKAB Experimental Blast Furnace (EBF) is a unique test facility and an important tool in terms of product development and process research. For a better understanding of pellet behaviour in the blast furnace process, LKAB has started to use automated mineralogy for the characterisation and quantification of its iron ore products and pellets. A mineralogical evaluation of iron ore olivine pellets, taken from a test campaign in the EBF, has been performed. The studied materials were samples from excavated pellet layers through the entire EBF at different positions. A large number of iron ore pellets was analysed using a combination of automated mineralogy, using QEMSCAN«, and chemical analysis. Important information about the performance of pellets in the blast furnace process, such as a quantitative description of mineral and iron oxide alterations at different temperatures, Fe-reduction and alkali deposition, was obtained.

Jan 1, 2008

By J M. Palin

Hydrothermal scheelite precipitated in fault-veins at Paradise, Bonnie Jean, Davidson's and Glenorchy mines display chemical variability involving REE patterns that are transitional between two end-member types. Type I is a MREE-enriched pattern with no or a small positive Eu anomaly. Type II is a flat to MREE-depleted pattern with a strong positive Eu anomaly. The chemical inhomogeneity of these scheelites can be explained by a model of fractional precipitation of REE, with preferential removal of MREE from the fluid during precipitation of scheelite. Irrespective of the mechanism responsible for scheelite precipitation, the source of dissolved constituents is different for scheelites from the Paradise Mine. Bonnie Jean, Davidson's and Glenorchy scheelites formed from LREE-enriched fluids whereas Paradise scheelites precipitated from fluids that were lower in LREE. These inferred fluid characteristics cannot be linked unambiguously to specific source rocks in the region, but could suggest that scheelite deposited in the Paradise fault-vein reflects a more mafic source of REE possibly greenschists, whereas the REE in scheelite from the other mines suggest a more felsic source.

Jan 1, 2003

By Stanton RL

Stratiform lead-zinc mineralization in the Soldiers Cap Group and Kuridala Formation of the Mount Isa Inlier is closely associated with iron-rich sedimentary units or "iron formation", and has many similarities to the Broken Hill deposit in New South Wales. Both the Soldiers Cap Group and the Kuridala Formation have been intensively explored for deposits of this type since the early nineteen- seventies. A mineralized belt of at least eight significant prospects has been identified, of which the Pegmont deposit is the largest and best known example. In most cases the mineralized horizons contain banded galena and sphalerite within a gangue of predominantly quartz-garnet- pyroxene-amphibole rock, sometimes containing a variety of other metamorphic silicates, and apatite. Chemically, the mineralized horizons are distinguished by higher than usual levels of one or more of total Fe, MnO, CaO and P205. Interpretation of patterns of mineral- ization within the belt is based on the Pegmont deposit, where a model of base metal sulphide deposition within restricted basins of iron-rich chemical sediment has been developed (Stanton and Vaughan, 1979). Broadly, the model envisages the deposition of higher grade lead-rich mineralization in the basin centre position, lower grade zinc- rich mineralization in a basin intermediate position, and much weaker copper-rich mineralization in a basin edge position. These three positions reflect a laterally continuous arrangement of silicate microfacies within the original iron-rich sediment.

Jan 1, 1984

By Salehi M. R

Although inherent mineral matter appears to have no effect of the reflectivity of inertinite in the reflecting light microscope, it has a marked effect on the grey levels resulting from the backscattered electron response in the scanning electron microscope. Inertinite with a high inherent mineral matter content has a high grey level response but not as high as that of mineral matter. The highest grey level response is with inertodetrinite which at times could be mistaken for mineral matter. Fusinite has a higher grey level response than semi-fusinite. The backscattered electron grey level response corresponds to average atomic number and hence approximately to density. If a porous structure develops and becomes filled with mineral matter such as S, Cl, Ca, Si, and Al the grey level will be higher. Micrinite has an unusual response in that it behaves like an exinite maceral in the SEM rather than an inertinite maceral. It either has a low grey level when relatively free of inherent mineral matter, or a low grey level background with high level granules corresponding to Si and Al dominantly. Similar structures have been found in exsudatinite and resinite. It is thought that micrinite results from the migration of hydrocarbons out of exinite giving a porous structure which usually accommodates inorganic matter.

Jan 1, 1991

By S Basu, P M. Midhun

Electro-Slag Remelting (ESR) is a process capable of producing ingots with much lower centre-line segregation and better internal soundness than conventional ingot casting processes, as well as lower inclusion and sulfur concentrations. This process is commonly used for alloyed steels intended for critical applications like components of marine turbines, supercritical powerplants and rocket motor casings. It involves melting a metal electrode using electrical resistive heating in a slag pool and re-solidification of the resulting metal droplets beneath the slag layer, forming an ingot. Conventional ESR fluxes consist primarily of CaF2, Al2O3 and CaO, along with minor concentrations of SiO2, MgO etc. The emission of fluoride vapour from the molten slag causes several environmental and health problems, triggering a need to develop and reduce the fluoride content in the ESR flux. The present study aims to develop low-CaF2 alternatives to commercial ESR fluxes without compromising on productivity and the surface quality of the refined ingot. Thus, the modification in chemical composition needs to satisfy properties like electrical resistivity, viscosity and liquidus temperature, essential for efficient ESR operation. Since electrical resistivity and viscosity are highly dependent on the ionic structure of the molten slag, it is important to understand the effect of compositional modification on the structure of the flux. The present study employs Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy to investigate the structural variations in the modified fluxes, especially the effect of changing SiO2 concentration, in comparison with conventional CaF2-rich fluxes. Additionally, thermal analysis (Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA)) has been carried out to characterise the melting behaviour of the fluxes. The findings are compared with simulations carried out using the FactSage™ software, ver 8.3 (GTT Technologies, Aachen, Germany). Simultaneous analysis of liquidus temperature and the structure is expected to help in identifying the practical suitability of modified ESR flux compositions for industrial implementation.

Jun 19, 2024

A Presidential Commission of Enquiry into the conservation of South Africa's coal resources was appointed in 1970. This Commission, in co-operation with the Chamber of Mines of South Africa, established a national inventory of South Africa's in situ and extractable resources and reserves of coal of various types and grades by several mining methods. South Africa's future demand for coal by all market sectors and the specifications of coal required, were also established by means of econometric models. A comparison of potential supply and anticipated demand indicated serious defi- ciencies of certain types of coal and the need for the conservation of others. This paper describes recommendations for alternate strategies for the optimum utilization of available resources. Con- sideration was given to various policies relating to pricing, exports, taxation and incentives, and to the possibility of the substitution of higher grades of coal by lower grades. The steps so far taken to develop a national coal policy in South Africa are described.

Jan 1, 1977

By Seymour D

The disagregation and privatisation of the mining and power gene ration operations of the former State Electricity Commission of Victoria has being taking place over the past five years. This has transformed the service provision to the new organisations and has resulted in major change to the working lives and professional relationships of thousands of Australians. The authors wish to take this opportunity to explore the issues arising as the program of privatisation of public assets continues. Changes within the workplace which resulted from the outsourcing of the 'investigation and design' functions and more lately as a result of privatisation of the operating, generating and distribution businesses are discussed. The responsibility of managers retaining the services of design engineers has changed. There is an added responsibility of contract administration and an increased focus on intellectual property and strategic issues. The way in which the sectors are adapting is discussed and future directions are explored. We welcome this opportunity to explore the changes in professional life which have taken place over the last five years in the Latrobe Valley Power industry. Engineers and earth scientists have a pivotal role in the continuing successful operation of the three Latrobe Valley Mines of the generation companies. The Mines' collectively excavate annually over 13 million cubic metres of overburden and 48 million tonnes of coal for delivery to mine-mouth power stations and for briquette manufacture.

Jan 1, 1997

By Larkings RH

The high gas emissions associated with the depth of mining and very high coal extraction at some Australian Collieries have provided a need to investigate the influence of geological and mining conditions on levels of gassiness. The introduction of longwall extraction in particular is associated with complex strata control problems and quick changes in gassiness. To this stage of Australian coal mining, no standard method has been developed to predict the different levels of gassiness associated with the various geological and mining conditions; and the relationship between coal output and total methane make has not been established. For local conditions, with a large number of coal seams lying in close proximity to the working seam, the significant contribution of gas emissions from adjacent strata was expected, especially as strata relaxation occurred during longwall mining. This depends mainly on geological conditions, strata control and coal production. For the deepest of the B.H.P. Collieries in the Newcastle region, the relationship between coal output and total methane make has been investigated by systematic gas balance measurement during longwall extraction. The computer method of iteration was used to approximate the mathematical equation from the initial graphs of coal production versus quantity of methane in the ventilation system for various strata conditions. The angle of caving was established for local geological and mining conditions, for planning and design of the positions of cross measure boreholes.

Jan 1, 1986

By S F. Wang, J J. Yin

Dust pollution poses a persistent challenge within mining processes, giving rise to a spectrum of concerns, including occupational diseases, mechanical degradation, diminished visibility, and the potential for dust explosion incidents. Existing dust detection and monitoring methodologies face limitations, including insufficient measurement accuracy and intricate processing procedures. Consequently, a comprehensive identification and evaluation system rooted in image processing technology is proposed to facilitate real-time measurements of dust pollution in mining worksites. The study primarily employs grey scale average and fractal dimensions to characterise particle features evident in collected dust images. As a result, the data processing platform can dynamically process data and present dust pollution conditions. Notably, this research integrates the monitoring and assessment of dust pollution with the systematic adjustment of mining parameters, ventilation parameters, and strategies for dust reduction. Through statistical analysis of dust concentration and particle size during mining processes, rock properties such as components and cuttability can inform mining parameters. This information, in turn, guides detailed excavation strategies, including cutterhead speeds, torque, and excavation speed. Similarly, analysing dust characteristics derived from images is a valuable resource for gaining deeper insights into the efficacy of implemented ventilation strategies. By harnessing vision-based information detailing dust concentration and distribution, a wealth of direct guidance becomes available for refining ventilation parameters. This encompasses crucial aspects such as the selection of appropriate ventilation systems tailored to the specific mining environment and the optimisation of operational conditions for ventilation fans. Additionally, the detailed information derived from the visual data allows for strategic decisions on factors like the spatial arrangement of ventilation outlets and the calibration of airflow rates. Moreover, precise choices for dust reduction measures and parameters can be made based on the prevailing dust conditions. Upon real-time monitoring of dust pollution using the proposed method, corresponding measures such as spraying and foaming can be promptly implemented. Crucial parameters, such as spray angles and volume, are integral to these application processes. In essence, the proposed method assumes a pivotal role in not only dust monitoring but also the formulation of preventative and control measures within mining processes.

Sep 1, 2024

Host minerals for gold have been of great interest to exploration geologists and metallurgists for a variety of reasons. The depletion of high grade ores in many parts of the world requires that greater attention be given to the study of host min-erals for gold. Some host minerals have been employed in exploration as traces for gold. They are also essential in the design of extraction processes for treating gold ores.This paper reviews the mineralogy of important gold deposits of Papua New Guinea (PNG), Indonesia and New Zealand and focuses attention on the ore minerals and rock-forming minerals that host gold.

Jan 1, 1994

Transport infrastructure constitutes, since always, an essential link between regions, countries and continents, for economical, commercial and human purposes. Permanently growing mobility needs, which are encountered in the whole world, lead to a more and more clear necessity to increase and modernise these transport infrastructures, as well in quantity as in quality, for all transport modes, and for all what is able to be transported, from people to consumption goods and energy. With only very few exceptions, transport infrastructure achievements have for long been the concern of the sole public authorities, at the various levels, which put them, mostly free of charge or at very low cost, at the disposition of the user or the customer.

Jan 1, 1999

By Hunter TC

Metals Refining Operations Pty. Ltd. (NMO), PNG's only gold and silver refinery is operated by Golden West Refining Corporation Ltd (GWR), a member of the Rothschilds group and has a strong PNG ownership link through statutory shareholders. Located in Waigani, MRO has been successful in substantially increasing production through toll refining for Porgera, Misima, Tolukuma, Wapolu and, more recently, at Lihir as well as treatment of alluvial gold from smaller operations. This increased throughput has resulted in the need to constantly upgrade equipment, techniques and practices, particularly to continue quality improvements and meet market demands. The evolution of these changes are documented and discussed and the probable future development plans are detailed.

Jan 1, 1997

By Locke CA

Geophysical signatures of the Taranaki and Tongariro volcanoes reflect similarities in their age, composition and hydrothermal histories, but also reflect differences in host rock settings and edifice evolution. The Taranaki volcanoes have strong positive gravity anomalies showing that their edifices largely consist of dense andesite which reflects substantial lava production or dyke injection during construction and that large sub-edifice dykelstock complexes occur. In contrast, the Tongariro volcanoes have strong negative gravity anomalies indicating low density edifices of volcaniclastic material; no sub-edifice intrusions can be identified, probably because of the lack of density contrast with host basement rocks. Strong positive magnetic anomalies over the younger cones can mainly be attributed to near-surface andesite lavas or dykes whereas subdued magnetic effects are associated with hydrothermally altered zones within both edifices and sub-edifice intrusions.

Jan 1, 1995