Search Documents

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 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 E Kasai, D Maruoka, Y Konno, T Murakami

The iron ore sintering process produces approximately three per cent of carbon dioxide emission in Japan because a large amount of coke breeze is used as the main agglomeration agent. Therefore, its suppression has been required. A promising method is to replace the coke breeze with biomass char and iron-bearing materials. In this study, the effect of the utilisation of metallic iron with coke or palm kernel shell char (PKS char) as an agglomeration agent on its oxidation behaviour was examined by a series of experiments using a sintering simulator. The use of PKS char leads to a larger decrease in the pressure drop difference of the sintering bed compared to the case using coke. Furthermore, the oxidation rate of metallic iron was larger in the case using PKS char together than that using coke. It was considered that the oxidation of metallic iron was promoted because the bed-temperature increased at a faster rate and achieved a higher temperature.

Nov 8, 2021

Gold and copper mineralization in the Parkes area is hosted by a meridional sequence of Late Ordovician to Early Silurian igneous and sedimentary rocks on the central northern edge of the exposed Lachlan Fold Belt. The mineralized area straddles two zones separated in part by the Parkes Thrust and exhibiting different styles of deformation and mineralization (Figure 1). The western zone is characterized by gently folded rocks, with shallow dips and weak to non-existent axial plane cleavage. Faulting is restricted to directions oblique to bedding. Numerous occurrences of minor copper mineralization are known, but of recent national importance is the discovery of the Coradgery- Goonumbla porphyry copper-gold deposits by Geopeko Ltd. A resource in excess of 250 million tonnes has been delineated (Jones, 1985), and this represents the first porphyry deposit of sufficient grade and tonnage to be potentially mineable in New South Wales. The eastern zone is much more strongly deformed. Folding is tight with strongly developed axial plane cleavage. Faulting is abundant both parallel and oblique to bedding. Quartz veining is also abundant, and a narrow belt of gold mineralization adjacent to the Parkes Thrust stretches from Forbes in the south, through Parkes and Peak Hill, to Tomingley in the north. Over 31 tonnes of gold have been produced from this gold belt, mostly before 1914, and now three deposits show good potential for redevelopment - Peak Hill, and the London-Victoria and Lachlan lines of lode.

Jan 1, 1987

Mining of copper ore is still the most important business in Chile. In order to mine ore with a copper content of less than one percent at Minera Los Pelambres in an economical way, opencast mining is mandatory. Due to the prevalence of avalanches at the mine, the concentrator was located in a stable area, some distance from the mine. As a consequence, the material has to be transported between mine and concentrator by conveyor. A downhill conveyor system has been implemented for more than ten years as the most suitable and most economical ore transport alternative. Due to the length (12.6 km) and inclination (1300 m drop) of the conveyor system, the stresses in the steel cord belt are the dominant design criterion, resulting in a belt quality of ST 7800. Additional dynamic belt stresses during transient operating conditions are avoided by the installation of high capacity adjustable frequency drives. The rating of a single drive unit is 2500 kW. During ten years of operation, several capacity increases have been implemented, from an initial 5800 t/h up to the current capacity of 9900 t/h. This presentation describes the engineering challenges of the implementation of the world's strongest belt conveyor system. Capacity increase measures like the development of new control and breaking strategy, proved by dynamic simulation of belt forces and belt speed scenarios are explained. During this long-term partnership of RWE Power International, the former Rheinbraun Engineering, with Minera Los Pelambres, RWE has been engaged continuously for development work, safety checks, expert opinions and maintenance audits, and giving new impulse to conveyor technology.

May 1, 2010

By P Chapman, B Moosapoor

The objective of this paper is to present the potential applications of geostatistical analyses in planning CPTu investigations, as well as interpolation of CPTu data. The paper presents a case study of a geostatistical analysis of CPTu data undertaken between 2004 and 2017 for an upstreamraised TSF located in the Goldfields region of Western Australia. An initial model is developed using the 2004, 2009 and 2017 CPTu data. The model is used to predict in situ cone tip resistance (qc) measurements, as the interested primary variable, at the selected locations where 2019 CPTu were undertaken, and the results of the prediction and the actual data are compared.

Jul 1, 2021

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

The epithermal silver-gold Red Rock Deposit is hosted in the Late Permian inter- mediate to silicic composition Drake Volcanics of New England, N.S.W. This deposit represents one of the few low sulfur epithermal precious metal systems in eastern Australia, and differ! from epithermal models in that the hydrotherma: system which produced mineralization was active in a shallow water marine environment. The Red Rock Deposit has a resource of 180,000 tonnes of 66g/t Ag and 0.9 g/t Au, and a Ag:Au ratio of 70:1. Mineralization is largely associated with hydrothermal brecciation, and occurs as disseminations, vein stockworks, and struc- turally controlled lodes. Ore minerals comprise acanthite (argentite), electrum, native Ag, Ag- sulfosalts and base metal sulfides, Alteration minerals associated with ore are quartz, cal- cite, adularia, pyrite, illite, illite-mont- morillonite, chlorite and sphene (leucoxene). Illitic and propylitic alteration zones sur- round the hydrothermal breccia. Bulk rock analyses indicate that alteration is character- ized by the addition of Si, K, Fe, Mg and the loss of Na and Ca. Ore was deposited from a boiling fluid in a temperature range of 222- 295¦C, and of 0.5-7 wt. Z NaCl equivalent sal- inity. An upper hydrostatic depth limit of about 800 m is implied for the boiling fluid ii an open vein. Sulfur isotopes indicate a mag- matic sulfur source, and oxygen isotopes imply a predominantly marine ore fluid. Modern analogs of the submarine hydrothermal system that formed the Red Rock Deposit occur in the Taupo Zone, New Zealand, and southern Kyushu, Japan.

Jan 1, 1987

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

Over the past 12 years screening of materials has undergone a dramatic change in both the types and materials used in screen mats and the quality requirements of the finished product. With the main thrust now on quality and a cleaner product a different approach was needed in the operation of sizing screens. New screen mats with many different aperture configurations have been developed using rubber and plastics.to replace the traditional screen mat of woven wire or punched plate.

Jan 1, 1984

By S Q. Zhao, J H. Wei

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Xitieshan lead-zinc deposit is located in the north margin of the Qaidam Basin, Qinghai Province, China. It is one of the largest massive sulfide deposits in China and is supposed to be of the sedimentation-exhalation (SEDEX) type. Based on the main ore mineral and sulfur isotopic compositions in sulfides found in the wall rock, the S of the deposit is considered to originate from the mantle, but the fluid potentially mixed with sea water during the hydrothermal circulation exchange. The study of lead isotopes shows that the metallogenic material is characterised by the mixture of orogenic and upper crust sources. The lead isotopic signature of the wall rock is similar to that of the ore, which shows synsedimentary characteristics. According to the composition of the rubidium and strontium isotopic signature, the value of 87Sr/86Sr is lower than the average value of that in the crustal rock, which is larger than that of the mantle. Hence, the metallogenic materials of this deposit mainly originate from the crust, which is related to materials of volcanic rocks activation and migration of the deep hot circulating water. The process of the metallogenic fluid circulation shows continuous interaction with crustal material and lead to continuous enrichment of the ore forming fluids. From the study of the fluid inclusion microthermometry of the ore and the associated minerals combined with the C, H-O, Si isotopes, it is believed that the metallogenic fluid is mainly coming from the mantle or the deep magma chambers. The rising deep fluid then mixes with the sea water. The carbon dioxide escaping and mixing with sea water during the hydrothermal exhalation process leads to the rapid precipitation of the hydrothermal fluid to deposit metal. That is proposed as the principal formation mechanism of the Xitieshan deposit. Further studies are proposed, including obtaining geochronology data from this deposit.CITATION:Zhao, Z X, Wei, J H, Liang, S N and Zhao, S Q, 2015. Advances in research on metallogenic mechanisms for the Xitieshan sedimentation-exhalation lead-zinc deposit, Qinghai Province, China, in Proceedings PACRIM 2015 Congress, pp 487–494 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By K Williams, T Donohue, W Chen, T Roessler, A Katterfeld

Wet sticky iron ore poses particular difficulties in every aspect of the material handling process. Material hang-ups in bins, pipes and chutes; carry-back and spillage due to insufficient belt cleaning; clogging of screens; malfunctioning of crushers as well as rat holing of gravity reclaimed stockpiles are all predominantly due to the inherent cohesion and adhesion characteristics of the wet, sticky ore (Roberts, 1993). Limited understanding and quantitative measures on the stickiness of such a material significantly lower the mining operation efficiency.This research aims to investigate the cohesion and adhesion characteristics of the wet, sticky ore on physical modelling, experimental techniques and numerical implementation. Initially, the suitable bridging mechanism that contributes to the cohesive and adhesive forces within the iron ore material was identified (Hering, Martin and Stohrer, 1989; Rumpf, 1958). A cohesion/adhesion energy density factor based contact model was then introduced to describe the stickiness of the material. Secondly, an experimental system was proposed to directly test the stickiness of the material. Such a system is able to obtain both the cohesive/adhesive shear force and tensile force of the material at a specific moisture content. Lastly, the implementation of the proposed cohesion/adhesion model into the discrete element modelling (DEM) software was also discussed. A cohesion/adhesion calibration for modelling wet sticky iron ore in DEM was then conducted to ensure the material modelled in the simulation is reflective of the reality.From the study, understanding of the cohesion/adhesion characteristics of the wet iron ore material is significantly enhanced. Experimental and numerical outcomes can be directly applied for better designing or optimising the material handling processes that involve wet sticky iron ore. Consequently, the mining operating costs can be greatly reduced.CITATION:Chen, W, Donohue, T, Williams, K, Katterfeld, A and Roessler, T, 2015. Modelling cohesion and adhesion of wet, sticky iron ores in discrete element modelling for material handling processes, in Proceedings Iron Ore 2015, pp 387–392 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Liu Wenyong, Huang Yucheng, Yang Ba

High-water rapid-solidifying material, called æhigh-water materialÆ, is a new material developed by the authors over many years. The material can solidify nine times its volume of water into solid. The material is a fine kind of binder with special properties. The solidifying body of high-water material with water has quite a high early strength. The compressive strength of the material within three days can reach the same strength as conventional Portland in 28 days. One ton of the material can replace three tons of conventional Portland cement as binder. Some important achievements have been made in application of high-water material. In metal mines, based on the material, a new full-tailing cemented backfill technology has been developed. The characteristic of the new technology is that high-water material is used as binder and full tailing or alluvial sand is used as backfill aggregate. Because of the application of the new technology, major technical problems in backfill technology such as classifying of tailing, dewatering, transportation of pulp, low strength of backfill body, environmental contamination and so on, have been solved.

Jan 1, 1998

By Wang J, Ma Y, Jia H

The Hedong Gold Mine is located in the Yan(ai area, tihandong hroo%ill, e. China. It is an underground mine with an annual gold output of some 700 0(H) grams. The orebody is located on the edge of the Wanger Shan metamorphism zone, and the hangingwall of orebodies is thus defined by a prominent set of fractures. The proximity of the metamorphism zone and the inclusion of the fracture set ensure that both the orebody and the country rocks are unstable. The main orebodies dip at an angle of between 40 to 45¦, with a strike length of 160 metres and a horizontal width of 50 metres. Surface subsidence in the area is not permitted. Cut and fill mining is usually practiced. As the mining operation proceeds to greater depths, the ore grade is diminishing and it is necessary to find a more efficient stoping method. Sublevel open stoping with sequential extraction and filling of each sublevel has been designed and applied in situ. This new mining method is called 'sublevel open and fill stoping method' in the mine. Experience to-date is that new mining method is Satisfactory.

Jan 1, 1998

By de Vries D, Wilson EG, Henderson GAM, Carter EK

Canberra is a planned city in which the natural environment, rather than existing development and land tenure, has until recent times at least, imposed the major constraints to development. Even redevelopment poses fewer problems than for most cities. Geological conditions have, therefore, played a significant role in determining its shape and layout. The Canberra experience has relevance for major new mining and engineering projects. The role of engineering geologists and geophysicists in Canberra's development is described, and the problems arising from the geological environment are illustrated by several case histories. Four aspects are addressed: pre-development urban geology; major engineering projects; resources evaluation, including groundwater; and post-development problem-solving. The Australian Capital Territory lies within the Palaeozoic Lachlan Fold Belt. Within the ACT the belt is composed of folded and faulted metasiltstones, metasandstones and acid volcanics, intruded by a major granitic pluton. Some limestone lenses occur. The region has been part of a land mass since Late Devonian times and landscape evolution has been very complex. Geological features of special geotechnical significance include deep but variable weathering, with slight to moderate weathering along faults to at least 70 metres depth in places, and consequential foundation problems; close jointing; weathered limestone lenses with solution cavities containing clay and water; confined aquifers containing artesian water in scree deposits flanking hills; the presence of pyrite; and poor quality and low volumes of groundwater.

Jan 1, 1986

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 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

The Late Permian intermediate to silicic talc-alkaline Drake Volcanics of New England, N.S.W., consist largely of shallow marine, redeposited volcaniclastic rocks which host epithermal Ag-Au deposits. Pervasive hydro- thermal alteration is widespread. The 200-300 m Cataract River Member includes several sedimen- tation cycles composed of massive pumice brec- cias, overlain by laminated sandstones and siltstones, interbedded with marine, fossil- iferous mudstones. Two distinct groups of cla- sts exist within the volcaniclastic beds: 1. Lithics of predominantly intermediate compos- ition lavas that have undergone subaerial epi- clastic erosion and transportation; 2.Pumice, quartz and plagioclase crystals which have not been reworked by epiclastic processes. The lithic clasts were derived locally in a sub- aerial environment within the Drake Volcanics, and pumice and crystal fragments from contem- poraneous centres of silicic volcanism else- where in New England, N.S.W. The latter group of clasts was transported to Drake by Plinian airfall or rafting, and fell and was washed on- to emergent portions of the Drake Volcanics, where reworked locally derived fragments occ- urred. Cold state subaqueous mass-flows, prod- uced by slumping, resedimented the mixed vol- caniclastic detritus into the marine basin in a series of cyclic units with massive lower parts, and laminated upper zones. Modern ana- logs of the palaeogeographic setting in New England, N.S.W., in the Late Permian are pro- vided by the Taupo Zone, New Zealand, and sou- thern Kyushu, Japan.

Jan 1, 1987

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

By Rowena C. Duckworth

The Ocean Drilling Program (ODP) is the largest international geoscience project in the world, and the state-of-the-art drill ship, the JOIDES Resolution, is permanently at sea. Each year there are six scientific cruises (legs) which each last approximately two months. These legs are designed by geoscientists from the nineteen countries that subscribe to ODP. Australia and Canada presently share ODP membership under the banner of the AUSCAN Consortium. The benefits of Australia's involvement in ODP include internationalisation of Australian geoscience, advanced graduate training, and unique scientific investigations of the ocean floors in the Australasian region. In addition, visits to Australian ports by the ODP drill ship, the JOIDES Resolution, contribute up to $2 million per visit to the local economy. Amongst the many other aspects of ten years of scientific drilling, ODP has significantly contributed to our understanding of hydrothermal processes on the seafloor. To date, three hydrothermal sites have been drilled to date by the ODP, Snakepit (MAR), Middle Valley (Juan de Fuca Ridge) and TAG (MAR). Two more hydrothermal sites are scheduled for 1996.

Jan 1, 1995