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By J H. Heo, J H. Park, M J. Lee

In this paper, the challenging points regarding the high temperature physical chemistry of slags to achieve the improved and stable electric arc furnace (EAF) or electric smelting furnace (ESF) technology on the way to green steel will be reviewed, and the recent experimental and modelling research will be discussed. For example, the initial melting phenomena of hot briquetted iron (HBI) and the slag formation behaviour was observed using a high-frequency induction furnace. Main component of gangue oxides in HBI was SiO2, Al2O3, and CaO in conjunction with unreduced iron oxide. To increase the dephosphorisation efficiency, the distribution ratio of phosphorus between metal and slag was calculated using FactSage™ software, version 8.2 (CRCT ThermFact, Inc., Montreal, Canada) and was compared to the measured results. The optimisation of slag chemistry is required not only for maximum dephosphorisation efficiency with good slag foamability but also for minimum slag volume with less refractory corrosion in EAF process. The slag chemistry is also one of key parameters affecting the operation efficiency in ESF in view of FeO reduction behaviour, viscosity, sulfide capacity, etc.

Jun 19, 2024

Depletion of shallow ore reserves is forcing the South African gold mining industry to exploit reefs at ever-increasing depths. By 2010 around 30 per cent of South African gold production probably will come from depths greater than 3 km (Johnson and Schweitzer, 1996). At such depths, virgin stresses will rise significantly, producing complex rock engineering problems (Malan and Basson, 1998). Concern over structural instability at depth has led planners to seek a technology capable of ædetection of geological structures with a displacement of 2 m or greater (or as appropriate to the mining technique) 200 m ahead of mining at an acceptable costÆ. Borehole radar probably is such a technology. Cover holes are drilled routinely ahead of development. The evaluation of its candidacy for a tactical role in ultra-deep gold mining dependsùamong other thingsùupon establishing the electromagnetic characteristics of the environment hosting significant gold reefs. The Ventersdorp Contact Reef (VCR) is one such reef. Recent borehole radar field trials, presented here, suggest that the VCRÆs overburden is a remarkably translucent, clutter-free dielectric with a Q of ~35 and that the VCR itself is the dominant radar reflector.

Jan 1, 2002

The Ida Valley in Central Otago is one of series of parallel basins filled with freshwater sediments. The basins are in fact tectonic depressions superimposed on NE trending grabenlike structures which occur in the area and are the result of block faulting possibly initiated in Cretaceous times and concluded in late Tertiary and early Quaternary. In Central Otago this tectonic event affected metamorphosed rocks belonging to the eastern facies of the New Zealand Geosyncline and collectively known as the Haast Schist Group. These rocks constitute the basement and the shoulders of the tectonic depressions. The Ida Valley occupies the depression wedged in between the Raggedy Range to the NW and the North Rough Ridge in the SE. The valley is approximately 38 km long, 3 to 7.5 km wide and is drained by the NE flowing Pool Burn, which meets the SW flowing Ida Burn. The resulting unified stream flows into the Manuherikia river which drains the next door depression to the NW. The present work deals with the Ida Valley basin and more specifically with the geology studied within two Prospecting Licence areas held by Gold Mines of NZ Ltd on the southeastern flank of the valley.

Jan 1, 1977

The accurate determination of trace level gold in ores, metallurgical samples and process solutions is required because of the value of gold, the efficiency of the cyanide leach process and because of the high gold recovery from these cyanide solutions. It is thus necessary to routinely analyse geological and metallurgical samples with gold concentrations of 3 g tonne (ug g- 1ppm) and process solutions with a gold concentration of 0.01 mgL 1 (ppm) preferably with sufficient accuracy to quote at least two significant figures. Several techniques have been reviewed for their suitability for the routine gold analysis of these samples which also contain signif- icant concentrations of other ions. The classic fire assay technique has achieved the respect and confidence of mining personnel because of the results achieved by very experienced assayers. Other extraction and concentration techniques have now been shown to be equally effective. The use of instrumental analytical techniques particularly atomic absorption spectrometry have shown that cheaper procedures, which are as reliable, are now available to gold producers for the routine analysis required to maintain an efficient gold recovery process.

Jan 1, 1982

By E Jak

A viscosity model has been developed for both completely liquid and heterogeneous, partly crystallised slags in the Al2O3-CaO-æFeOÆ-SiO2 system in equilibrium with metallic iron. The Urbain formalism has been modified to describe the viscosities of the liquid slag phase over the complete range of compositions and a wide range of temperatures. The Roscoe equation has been used to describe the effect of presence of solid suspension (slurry effect) on the viscosity. The parameters of the viscosity model were optimised to describe large experimental data set in the low-order subsystems, as well as in the multi-component system. The computer package FACT was used for prediction of the proportion of solids and the composition of the remaining liquid phase. The model provides a good description of the experimental data (over four thousand experimental points) in liquid phase, and liquid + solid mixtures, over the complete range of compositions and a wide range of temperatures. This model can now be used for viscosity predictions in industrial slag systems. An example of the application of the new model to slag cleaning and reduction smelting processes is given in this paper.

Jan 1, 2000

Tokyo Metropolitan Government designs the stormwater storage plans in underground, as a measure of flood control in completed urban district and improvement of combined sewarage system. This time, introducing those plans, we report about IKEJIRI and SIN-KOMAZAWA STORAGE TRUNK LINEs design and construction. They are located in Meguro river basin of the Morigasaki drainage area. Both storage trunk lines have capacity to store 15O,000m3 of stormwater. They are in use for countermeasure of flood till Meguro river's strengthening (intensity 50 mm/h) is ended. And after the strengthening, they will be in use for improvement of river water quality, through the storage of combined sewage and first runoff, which, otherwise overflows weirs and flows to river in a rainy day. These storage trunk line's full length is about 5700m. Boring diameter 66140 mm (f = 2672m) and 47800 mm (I = 2866m) of these tunnels are constructed by Mechanical Shield tunnelling method. And boring diameter 3600 mm x 4000 mm (R = 180m) is constructed by NATM tunnelling method. We began works in 1983, and have a mind to complete in 1987.

Jan 1, 1987

By M A. Mular, T Akroyd

A fundamental model, which considers the subprocesses of particle collection by bubbles in flotation, is applied to two comprehensive flotation surveys in the rougher stages of C3 concentrator, PT Freeport Indonesia. The flotation surveys focused on the collection of: cell-by-cell and size-by-size metallurgical, cell hydrodynamic, and pulp and surface chemistry information.The two surveys were conducted at significantly different feed tonnages, giving rise to significantly different feed particle size distributions, pulp densities and mean pulp residence times. A series of model simulations are performed with the aim of quantifying changes in copper recovery, on both a size-by-size and unsized basis, with changes in values of the hydrodynamic parameters and hydrophobicity of the copper sulfide mineral. This was carried out in an effort to identify the most promising route to increase overall copper recovery in roughing. It was found that by increasing the hydrophobicity of the copper sulfide mineral surfaces it became possible to optimise cell hydrodynamics, which targeted increased fine (-12 ¦m) copper sulfide mineral recovery but without adversely affecting coarse (+150 ¦m) copper sulfide mineral recovery.

Jan 1, 2007

IN the course of his employment the Broken Hill Co. the writer has had occasion to use and instruct others in the use of the Shamrock rescue apparatus. This paper deals with the various types of apparatus tested. The common object of the various types of breathing apparatus is to enable the wearer to remain and work for varying periods of time in an atmosphere which is either deficient in oxygen or is poisonous that is, contains carbon monoxide or irritating and irrespirable vapours, such as the smoke from underground fires, sulphur dioxide or ammonia fumes. For any apparatus to be efficient as required in the above paragraph it must fulfil the following conditions;1. Air-tight as regards the passage of the air from the outside to the inside. In atmosphere containing carbon dioxide a slight leak would not render the apparatus useless; but where irritating vapours, such as the smoke from burning oregon and sulphides, are met with, even the slightest leak must be avoided.2. The oxygen supply must be ample, and so supplied that it is not checked by expiration.3. Expiration and inspiration must not be retarded.

Jan 1, 1911

By V S. T Ciminelli

This work aimed at evaluating the acid rock drainage (ARD) potential of five samples of a Brazilian gold sulfide mine in a decommissioning process. Three of the most traditional ARD prediction techniques, Standard Acid Base Accounting (Std ABA), Modified Acid Base Accounting (Modified ABA), as static methods, and humidity cells as a kinetic method were tested. Both the Std ABA and the Modified ABA results indicated an acid generation potential for some of the studied samples. In the other cases the results were inconclusive. The five samples were then submitted to humidity cell tests during 27 to 30 weeks. At the end of the period, the leachate pH was stabilised in a range from 3.4 - 4.1 (four samples) to 5 (one sample). The presence of relatively high levels of sulfate and dissolved metals was detected throughout the operation, specifically, Ni and Zn, and less frequently, As. These findings are discussed with the help of the samples mineralogy and Eh-pH diagrams. The results obtained in this investigation indicated potential environmental risks of this mining area. In this particular case, the kinetic tests were shown to be essential to the identification of the samples ARD potential.

Jan 1, 2003

By Bevilacqua P, Preti U

The basic separation phenomena taking place in film concentration processes are studied through a kinetic-probabilistic approach. This approach is based on the fact that the particle velocity in the film separation phenomena is a random variable and may be defined by frequency distributions and probability laws. The approach requires: 1. development of probabilistic models for describing the behaviour of particles having different specific gravity and size along selected trajectories in the separating devices; 2. setting up an experimental procedure for determining the relevant frequency distribution curves at the exit of the separators for the particles mentioned above; 3. estimation of model parameters and model validation. In the paper, the model equations are given for the mass distribution of particles on the surface of separators, the mass distribution at the exits of shaking tables and the residence time distribution in channel type devices. The relation between residence time distribution and particle velocity distribution is derived. The test procedure has been defined and results are reported for the exit or residence time distribution in channels. A comparison between experimental and calculated frequency distributions is reported.

Jan 1, 1993

By Bahsford A

The presence of coal in the Sydney area was confirmed in 1891 when Cremorne Bore No. I intersected cindered coal at 1 854 m. The decision to develop Sydney Harbour Colliery was based on the results of Cremorne Bore No. 2 (drilled in 1892) in which a 3.12 m. seam of unaltered coal was encountered at 889 m. Geologists from the New South Wales Department of Mineral Resources consider that this seam is probably equivalent to an upper split of the Bulli seam. Long Cove at Balmain was selected by Sydney Harbour Collieries Ltd. as the site for mine development in 1896. This was due to opposition to the proposed establishment of a colliery on the north shore of Port Jackson near Cremorne. Construction of the main access and ventilation shafts (termed Birth- day and Jubilee), other mine infrastructure and the quay wall occurred between 1897 and 1902. A fatal accident in which five men were killed occurred during the construction of the Birthday Shaft in 1900. This acci- dent resulted in amendments to the Mining Act providing for guide rails in shafts.

Jan 1, 1988

By Ngai WCT

Over 90 per cent of the explosives in Hong Kong are used in civil engineering works. The Hong Kong Government controls all explosives and delivers on a daily basis to each site which it has licensed. Such deliveries need to be arranged the day before actual delivery. With the vagaries of the traffic in Hong Kong, contractors do not necessarily know the time of arrival of explosives. Contractors in general would like to reduce their exposure to these potential delays and the high cost of explosives deliveries. The high population density and urbanisation means that rock blasting has to be carried out in close proximity to other property. In order to protect life, property and utilities, it is not only necessary to employ proper blasting techniques but also to adopt effective safety measures. The Route 3 Advance Earthworks project is located on the north-west corner of Tsing Yi Island, Hong Kong. It is one of the Airport Core Programme projects for the new Chek Lap Kok Airport. Secured by Leighton Contractors (Asia) Ltd in early-1992, the work commenced in May of the same year, with completion and handover to the Hong Kong Government in May 1995.

Jan 1, 1995

By Dixon CA

In the early 1970s, Jim Walter Resources, Inc. (JWR) embarked on a coal mine expansion program that was unparalleled in the history of the United States. With a small nucleus of people then operating two rapidly depleting captive mines, action was initiated to develop four of the deepest mines in the United States. Because of the depth of these mines, operational and technical problems were anticipated. However, because of the high quality of the coal (Blue Creek Seam), the financial risks involved were acceptable. The total investment to get the expansion program completed (to get the new mines to full capacity) would represent an investment of over US$ 500 million.By the end of the decade of the 1970s, the Company had grown to 2100 employees who were producing 1640,000 tonne of saleable coal per year, a productivity rate of 3.9 tonne per man-shift. This productivity rate was not sufficient to maintain a profitable, viable organisation. Therefore, if the operations were going to survive, it would be necessary to improve productivity tremendously, a task which would tax the resources and imagination of all employees.

Jan 1, 1991

By E U. Petersen, D R. Cooke

Hydrogen and oxygen isotopic constraints on hydrothermal fluid composition from the Pliocene Boyongan and Bayugo porphyry copper-gold deposits (southern Philippines ) reveal mixing of magmatic and sea water reservoirs as the hydrothermal system evolved. Magmatic-equilibrated fluids (d18O: +8.3ë to +9.1ë; dD: -61ë to -51ë) are represented by hypersaline brines implicated in copper-gold transport and deposition. These dominate the fluid inclusion assemblage in early comb-quartz (unidirectional solidification textures), miarolitic quartz, and in K-silicate-stage quartz-K-feldspar ¦ biotite veins. Fluids responsible for post-K-silicate alteration assemblages of pyrite-clay (illite, pyrophyllite and kaolinite), alunite and smectite are represented by low-moderate salinity two-phase inclusions in co-existing quartz. These are interpreted as mixtures of evolved magmatic fluids (d18O dD: -42ë to -20ë) with evolved Pliocene sea water (d18O: + 4.0ë; dD: +4ë). The isotopic evidence for sea water involvement in the hydrothermal system suggests that porphyry emplacement and associated diatreme formation could have occurred in a submarine setting. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

While South Africa is well endowed with mineral resources, it is generally accepted that its future will be determined more by the development of its human resources than its mineral wealth. The country has throughout its modern history suffered from an over-supply of unskilled labour and a shortage of skilled and professional manpower. There has furthermore always been an over-reliance on Whites as an internal source of professional manpower, supplemented by immigration wherever possible. Better utilisation of other population groups in professional positions has been hampered by the general lack of education and training among such groups. Although many problems still remain, there are emerging trends which are likely to positively affect the training of professional manpower in the future. The direct and indirect influences that are likely to affect professional training at the macro level include 1. government policy and objectives in respect of manpower education and training, 2. the emergence of technikons as fully- fledged tertiary education institutions, 3. demographic trends in South Africa as they pertain to education, 4. political and statutory developments in the country, 5. industry involvement in tertiary education, and 6. professional registration.

Jan 1, 1986

Estimation of operating costs in the nickel production industry requires a detailed analysis of material flows from mine to smelter to refinery. Despite the small number of nickel producers compared to other base metals, the existence of two very different ore types (sulphide and laterite) and a wide variety of mining and processing technologies make the identification of these flows of critical importance if an accurate global picture is to be obtained. Smelting and refining processes in nickel metallurgy have evolved with a high degree of adaptation to specific operating conditions in different locations. Overall costs are calculated by combining individual cost elements for each unit in production chains from mine to saleable metal product. The average cost of western world primary nickel production in 1995 was US$2.07/lb ($4560/tonne). Average operating costs remained virtually unchanged in the three years to 1995 after an 8.5 per cent fall in 1993, but a 3.9 per cent increase to $2.15/lb is expected for 1996. A major factor in this rise results from the lower prices of copper and cobalt this year, reducing the by-product credits available to major producers.

Jan 1, 1996

The introduction of rubber tyred diesel equipment underground in the early 1960's and subsequent design improvements to diesel haulage systems over the past 2 decades has meant that diesel truck haulage has often been the first choice when selecting a haulage system for a new underground mine. Even today only 9% of all vehicles underground are electric powered.However, with the development of more efficient electric haulage systems, the suc-cessful installation of low cost shaft hoisting systems and improvements in conveyor design, alternative haulage systems are appearing as viable alternatives to diesel truck hauling. In particular, the aspects of ergonomic and environmental operating conditions, maintenance and operating costs as well as productivity rates are becoming more and more important in the selection of underground haulage systems. Future develop-ment of existing diesel haulage systems will require that diesel haulage units become more productive, have considerably reduced exhaust emissions compared to existing units and remain the cheapest haulage method for under-ground one way haul distances up to a distance of 3 kilometres. Development of electric truck and associated fuel cell haulage systems

Jan 1, 1985

Expansion of the B.H.P. Co. Ltd. mater ials handling facilities, at their Newcastle Steelworks, began in 1964 and continued until 1970. The present complex handles the annual iron ore requirement of some three million tons for the Sinter Plant and Blast Furnaces. Iron ore is discharged from ore carriers and conveyed at rates up to 3,000 t.p.h. to either of two 180,000 ton capacity storage yards, where it is blended using boom stackers. Material is reclaimed from these yards at rates up to 1,000 t.p.h. using a slewing boom bucket-wheel reclaimer and fed to a screening station. Oversize material is scalped out and crushed in a closed circuit cone crusher. Undersize material is sized on double-deck vibratory screens which separate at 1/4in (6mm). The two fractions are blended in two of four 70,000 ton capacity blending yards using slewing boom travelling stackers. Bridge-mounted bucket-wheel reclaimers reclaim the blended piles at 1,000 t.p.h. Fine ore is conveyed to the Sinter Plant and lump ore to a second screening station, for rescreening, before passing to the Blast Furnace.

Jan 1, 1972

Syferfontein Colliery, part of the Sasol group of companies which specialises in the field of petro-chemical production, was established in 1990. The mine is situated about 150 km east of Johannesburg, South Africa. Two coal seams are mined, utilising two 75 m3 draglines, shovels and a fleet of 177 ton rear dump trucks. The mine will reach its full production capacity of seven million tonnes per annum in 1992. During the planning period, prior to the establishment of the mine, management were confronted with the unstable socio-political environment in South Africa which could jeopardise the eventual success of the mine. They consequently conducted a strategic planning exercise to determine guidelines for mine planning to improve the chances of success in this unstable third world environment.The strategic guidelines formed the basis for specific actions taken during the planning and commissioning of the mine. Specific actions were taken in the field of operating cost, labour relations, working environment, logistics and the general environment. First results indicate that these actions have played a major role in the success of the mine to-date. This process can be utilised by others facing similar or even totally different uncertainties.

Jan 1, 1992

The Nagambie heap leach gold mine commenced production of gold in September, 1989. The mine,120km north of Melbourne in Victoria, Australia, was developed by Perseverance Mining Cor- poration Ltd, a junior Australian mining company, with no other operating mines. Gold production to December 31, 1990 was 47,621 oz. The mine is now producing at the rate of about 45,000 oz per year. As of February 28, 1991, resources at the mine are 5.1 million tonnes measured, at 0.65g/t Au while reserves were 1.65 million tonnes at 0.86g/t Au of proven, heap leach ore, plus 0.37 million tonnes at 0.40g/t Au, of dump leach ore. Metallurgical recoveries expected are 80 per cent for the heap ore and 60 per cent for the dump ore. Perseverance Mining Corporation was listed on the Australian Stock Exchange on April 2, 1987, after a capital raising in March that year. At this time the company's issued capital was 4 million ordinary 25ó shares, 3 million of which were issued to the public to raise $0.75 million.

Jan 1, 1991