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By J Meinhart, J Rodler, I Katolicky

The ever increasing number of vehicles is leading to slow-moving and even stationary traffic sitting longer in traffic jams over extensive city areas. This traffic situation causes a sharp increase in pollutant emissions from vehicles, and high levels of pollution usually result throughout the built-up area. Reducing the pollution level by using traffic routing measures to speed up the flow of traffic in the existing street network is only possible in exceptional cases.In many cases the only option for achieving a significant improvement in traffic conditions is to shift the traffic underground using a road tunnel or underpass. Such tunnel routes suck off the traffic from large sections of the city, thereby easing the overall traffic flow. Thus on the one hand it produces a sharp reduction in pollution levels in the area of the tunnel route, but on the other hand it can result in locally increased exhaust pollution levels from longer tunnel systems that require mechanical ventilation. The air extracted by the ventilation system is blown out into the atmosphere either directly through the tunnel portal, or via a venting tower. Pollution can therefore occur in the area surrounding such exhaust air outlets.Thus if a tunnel is planned in a city, then closer investigation is required of both aspects: the reduction in pollution in the area of the tunnel route thanks to relocating the traffic and easing congestion, and the increased short-range pollution around the tunnel portals (shafts).

Jan 1, 1999

Hydraulic backfill is generally retained in slopes using permeable barricades. Mitchell et a! (1975), Mitchell (1992) and Grice (1989) have shown that under normal drainage conditions, barricades experience low levels of loading. Cowling et a! (1988) have also shown that barricades are susceptible to piping failures if excess water has ponded on the upper backfill surface and if leakage of backfill from the barricades has occurred. During 1997, six hydraulic backfill barricades failed in four different Australian mines. Fortunately, in each case, the quantity of backfill slurry released was small, and no injuries to personnel nor damage occurred. Detailed investigation of two of the incidents showed that the primary cause of failure could be attributed to the delivery of excess quantities of transport water from the low-density slurry. For each of the incidents investigated there was evidence of the development of piping failures, which resulted in hydrostatic loading conditions on the barricades from the ponded water on the upper backfill surface. The circular failure surfaces in the barricades were characteristic of the application of point loading Conditions.

Jan 1, 1998

By R Cox, S Pandey

The coal seam gas (CSG) industry is expanding rapidly in the Surat and Bowen basins. CSG production involves pumping water from the coal seams to release the gas adsorbed to coal particles. The reduction in water pressure in the coal seams will cause some reductions in water pressure in overlying and underlying aquifers because there will always be some interconnectivity between the formations. The Surat Basin is a sub-basin of the Great Artesian Basin, which contains aquifers of high economic, environmental and cultural value. The Condamine Alluvium is also an important water resource, which overlies parts of the eastern margin of the Surat Basin.Under the Queensland (Qld) regulatory framework, an area of intensive CSG development involving multiple CSG operators can be declared to be a cumulative management area. For such areas the Office of Groundwater Impact Assessment develops assessments of future impacts on aquifer water pressures and develops and manages arrangements. The results are published in underground water impact reports.The Surat underground water impact report (QWC, 2012) was approved in December 2012. This paper summarises the place of the report in the Queensland regulatory framework, the content of the report and progress in its implementation.CITATION:Cox, R and Pandey, S, 2013. Managing groundwater impacts in the Surat Basin, in Proceedings Water in Mining 2013 , pp 169-174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By ALAN J. HARGRAVES

It is normal that Shepherd and Rixon, in their contributed discussion (this issue) see differences with Hargraves (1983), as it exemplifies the present uncertain situation worldwide, a situation expected to remain until better understanding and wider agreement lead to the real goal of the prevention of instantaneous outbursts of coal and gas.

Jan 1, 1983

By D J. Williams, M S. Zbik, A Shokouhi

There is a considerable difference in the particle size distribution (PSD) of clay mineral-rich coarse coal reject with variations in the test moisture state and the chemistry of the water used for testing. The coarse coal reject tested were collected from Jeebropilly Mine, located in the Ipswich Coalfields of south-eastern Queensland. Differences between the results of dry and wet sieving analysis indicate a significant breakdown of the clay mineral-rich coarse coal reject on wetting-up. Wet sieving caused a breakdown of the gravel-sized fraction to silt and clay size without significant breakdown to sand size. There is also a considerable variation in the results of hydrometer analyses of the clay mineral-rich coarse coal reject with variations in the chemistry of the water used, particularly at the fine end of the particle size range. The waters used included tap water, coal processing water and deionised water. In addition, the method of dispersion applied prior to hydrometer analysis can have a significant effect on the PSD of clay mineral-rich coarse coal reject, with boiling and sonic vibration causing the most breakdown of the clay particles. This paper describes the testing methodology used and the test results obtained, and attempts to explain the results in terms of clay mineralogy and water chemistry.CITATION:Shokouhi, A, Williams, D J and Zbik, M S, 2015. Influence of water on particle size distribution of clay mineral-rich coarse coal reject, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 239–246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By M Stephens, T A. Sutra

Currently, there are several open pit mines with production rates of about 200 000 tpd of ore that are reaching the end of their economic lives. In most cases, the remaining orebody extends to depths greater than 300 m below the pit limit, leaving hundreds of millions of tons of reserves that can only be recovered by means of an underground mining method. One such method used for mass production is block caving. This paper presents a ventilation system for a four-zone block cave mine operation developed on a footprint 1000 m wide and 1200 m long. The system is designed for a mine with a nominal production rate of 120 000 tpd of ore using diesel powered units on the production and reduction levels. It discusses the air quantity requirements for the worst case scenario, which is anticipated to occur five years after the mine has reached its full production capacity. Finally, it summarises the results of computer modelling exercises that were carried out to determine an economic ventilation infrastructure that includes shafts, drifts, main fans, and ventilation control devices.

Jan 1, 2005

By G J. Halstead, R C. Steinhaus

The True Pipe® in-line sampler was developed in an attempt to address the need for a mechanically reliable and correctly designed sampler to suit one-dimensional pressurised slurry pipelines, often found in metallurgical process plants but for which no reliable and representative sampling solution as yet exists.The design, whose operation is based on the principle of symmetry, is described by Dominique François-Bongarçon (2005) with the synchronous opening and closing of relevant valves. It representatively isolates portions of the particulate material stream at predetermined intervals for effective extraction of primary increments for subsequent sample compositing.Theory of Sampling applicable solutions have proven elusive in flowing pressurised particulate material streams, with various attempts to date not having formulated a viable, mechanically reliable and acceptable design.Compliance to sampling theory is critical, and a number of tests were conducted where certain operating parameters were altered to determine their influence and sensitivity on sampling representativeness.The results of the initial series of tests performed on a carefully designed rig are presented, with additional work discussed for necessary investigation in the near future.Getting closer to a robust, economic and correct design for this challenging application in the minerals industry may now not be that far away. Plant management staff will see improved metallurgical mineral balances around their process plants and significantly reduced sampling discrepancies, particularly in tailings applications. Improved quality control is now possible where, due to plant head room constraints, classical cross stream sampling methods cannot be employed.CITATION:Steinhaus, R C and Halstead, G J, 2014. True pipe sampler – a correct design utilising the principle of symmetry in pressurised slurry particulate streams, in Proceedings Sampling 2014 , pp 127–134 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By C Claassen, R Balusu

Computational fluid dynamics (CFD) models have been developed based upon field data collected from a longwall mine in New South Wales, Australia to study the behaviour of goaf gas flow in both active and sealed goaf areas. A base CFD model was built to represent the goaf situations when the active longwall retreats near the finish-off line. Results from the base model were calibrated and compared against field goaf gas monitoring data. The base model was then used to carry out parametric studies to investigate a number of operational scenarios and their impact on goaf gas behaviour. CFD modelling results indicate that the overall goaf gas flow pattern changes as the operating longwall retreats towards finish-off line. In all cases, oxygen penetration into the active goaf remains high, reaching 15 per cent or higher, even at some 800 m behind the longwall face.The modelling results also indicated that it would be difficult for early detection of an active goaf heating (on the maingate side) based upon CO readings in the return airflow, as the main stream of the gaseous product will be flowing into the sealed deep goafs in adjacent longwall (LW) panels. Monitoring points (such as tube bundles and bag sampling points) should be selected at deep seated seals along the active goaf so that abnormal CO or C2H6 readings can be picked up for early detection and location of potential heating spots; goaf inertisation can be better achieved by injecting inert gas such as nitrogen at deeper points (>200 m) behind the operating longwall; the injection of in-seam drainage methane into the goaf areas will only have a limited impact on goaf inertisation as much of the injected methane will migrate towards deep and higher parts of the goaf due to its buoyancy effect.

Sep 26, 2011

By M K. Singh

Mining is nothing but an art - besides being a science - of extracting valuable minerals from the womb of the mother earth. In this gigantic task, a large number of machinery and equipment are employed judiciously. Wire ropes play a vital role in lifting or hoisting men and materials under hostile/adverse working conditions and constitute a major item of investment on machinery/equipment. The economy of using a wire rope is a concern for engineers, users and the planners. The economic use of wire ropes for mining purposes largely depends on the following factors;Mechanical design considerations - which include tensile strength of wires, elasticity, resistance to abrasion and crushing, fatigue values, static and dynamic loads on wire ropes, factor of safety, fleet angle, etc. Metallurgical consideration - Composition and heat treatment of wire materials, defects like inclusions and voids, surface quality factor, lubrications, micro structural parameters. Operational consideration - Seizing and cutting of rope, storage, care and maintenance, cutting back, etc. Environmental consideration - Temperature and humidity, pit condition, dust, corrosive atmosphere, etc. In the present paper, an attempt will be made to suggest steps for achieving optimum economy while using the wire ropes for extraction of precious minerals and coal keeping in view the points noted earlier. Once technical viability is established, economy is the ultimate consideration for an industry for safe hoisting of men and material.

Jan 1, 2000

By G R. Dickens, N H. S Oliver

The genesis of giant hematite ore deposits in northwest Australia remains a contentious topic in part because key evidence supporting a unifying genetic model has not been found at all deposits. In particular, several papers have proposed that carbonate replacement of silica layers in banded iron formation (BIF) by basinal brines is a requisite first step toward ore formation. This initial hypogene stage is inferred primarily from the presence of silica-poor, carbonate-rich rocks found below ore and along normal faults at the Mount Tom Price and Giles Mini deposits. However, until recently such rocks have not been identified at the largest martite-microplaty hematite deposit, Mount Whaleback. In this study, samples of the upper Mount McRae Shale are examined for their chemistry, mineralogy and petrography. These samples were collected from several key locations, including within drill core that penetrates an area immediately beneath ore along the Mount Whaleback fault at Mount Whaleback. Compared to unaltered black shale from Wittenoom Gorge in the north and altered black and red shale at Mount Whaleback, reddish-green shale below the Mount Whaleback deposit is significantly enriched in MgO and CaO and depleted in SiO2. Samples of this shale consist predominantly of fine- to medium-grained dolomite and ankerite cut by chlorite and carbonate veins, contrasting with unaltered equivalents that contain mostly stilpnomelane, K-feldspar and relatively minor carbonates. This alteration is distinct from assemblages developed during regional metamorphism, and possibly represents hydrothermal alteration after metamorphism. Although several questions remain unanswered, these results support models that invoke an early hypogene stage during the formation of the martite-microplaty hematite deposits in the Hamersley Province.

Jan 1, 2005

By H Zhang, Y Wang, S Sukenaga, H W. Ni, H Shibata, W Z. Mu

The crystallisation behaviour of low melting point CaO-SiO2-Al2O3-MgO inclusions greatly affect the deformability of inclusions during the rolling process. The crystallisation characteristics of CaO-SiO2- Al2O3-MgO melts representing the oxide inclusions in Si-Mn killed steel were systematically investigated. The effect of Al2O3 and MgO contents on the crystallisation change were analysed under a fixed CaO/SiO2 in the complex inclusions. The continuous-cooling-transformation (CCT) and time-temperature-transformation (TTT) experiments were conducted. The results showed that the increase of MgO content increases the crystallisation ability of CaO-SiO2-Al2O3-MgO inclusions, while the increase of Al2O3 content has the opposite effect. The viscosity, liquidus temperature of oxide melt and also the initial crystallisation potential might be the reasons for the change in crystallisation behaviour. Also, the crystallisation activation energy could semi-quantitatively characterise the crystal growth during the crystallisation of inclusions. To obtain low melting point plasticized CaO-SiO2-Al2O3-MgO (CaO/SiO2=1) system inclusions, the Al2O3 content of the system needs to be controlled larger than 15 wt per cent and the MgO content should be kept at a small amount.

Aug 21, 2024

By C Mpodozis

Central Andean (22¦S to 34¦S latitude) Miocene giant ore deposits share common features that reveal their origin. Tectonic and magmatic features include a relation to a shallow subduction zone, an association with the waning or initiation of a magmatic episode, emplacement at the time of uplift associated with crustal thickening and formation at times of major magmatic changes along the Andean margin. Rare Earth Element (REE) signatures in magmas erupted near the time of mineralisation indicate a progressive change from equilibration at depth with a hydrous, intermediate-pressure amphibole-bearing mineral residue to equilibration with an anhydrous high-pressure garnet-bearing assemblage. These features point to a common history. First, a relatively shallow subduction zone leads to hydration of a cool mantle wedge providing a source of fluids which builds up over at least several million years. Arc magmas formed at this time equilibrate with a hornblende-bearing residual mineralogy. Second, a compressive tectonic regime leads to crustal shortening and thickening that facilitates entrapment of arc magmas in the crust. Eventually, the magma-weakened crust yields to horizontal compression causing rapid crustal thickening. Fluids required for mineralisation are liberated as amphibole-bearing assemblages break down to garnet-bearing ones and over pressured fluids are released from plutons. Mineralisation subsequently ceases in the region unless continued dehydration of the slab and mechanical thinning of the continental lithosphere causes the previous conditions to repeat. The type of mineral deposit generated depends on the pre-existing continental lithosphere and the distance from the trench.

Jan 1, 1999

By Xianguo C, Baoqi S, Shaozhong Z, Huiling Z, Zhengbing C

Acidless and fluoless flotation is a new method for separating feldspar from quartz at the natural pH value of tap water in the absence of any acid and fluoride and other inorganic reagents. The paper introduces the production application of this method in plants and research results on the mechanism involved in the flotation method.

Jan 1, 1993

Gold deposits in Eastern China have characteristic of belted distribution. The concentrating belts of gold mineralization are about parallel to the island are belt in Western Pacific Ocean. Gold deposits are mainly concentrated in the aged metamorphic rock series on the upwarping zones and upwarping fault zones, and obviously controlled by the deep fractures and their deriva-tive secondary faults. Gold mineralization had genetic relation to the Mesozoic (especially Yanshan period) magmatic activity. The distribution and genesis of gold deposits can be explained by the assumption of wavy structure. The formation of wavy structure is related to the process of Pacific plate and India plate.

Jan 1, 1990

By C Li, K McDonald an, T Nicholson, C Brown

The relative reactivities of chars prepared from different coal samples at temperatures in the range 500 to 1150¦C were determined by measuring the rates of metallisation of a standard ilmenite concentrate. The results have been interpreted in relation to different measured physical and chemical properties of the chars. Char reactivities were found to correlate with the maximum specific surface area (SSA) of the chars, obtained from plots of SSA versus temperature. Weathering of coal samples gave higher reactivities which correlated with higher SSAs. Experiments using recycled chars showed that the high internal SSAs developed during earlier reduction reactions provide no benefit in terms of increased metallisations. The important role of char hydrogen contents in controlling low temperature metallisation rates was demonstrated. Chars prepared from different rank coals had the same hydrogen content when prepared at the same temperature. Ilmenite metallisation rates had a linear dependence on the hydrogen content of the chars. Large differences in the slopes of the metallisation versus H2 content curves for different chars were interpreted in terms of SSA variations and catalysis of the gas reactions by dispersed metallic iron particles in the chars. A simple test based on magnetic separation of the char was shown to give an indication of enhanced reactivity due to contained metallic iron.

Jan 1, 2001

By Y Peng, B Guo

In gold processing plants, the water from the cyanidation stages is treated to detoxify cyanide species and this recycle water becomes the main part of the process water. Despite the low concentration of free and weak acid dissociable (WAD) cyanides in process water, the recoveries of gold and silver is still affected during flotation, especially when gold and silver are associated with iron sulfide minerals. This is a case at the Hidden Valley (HV) Mine. In this study, the effect of free and WAD cyanides on gold and silver recoveries by flotation from the HV Mine was considered.WAD cyanide (WAD CN) was prepared by mixing sodium cyanide and copper sulfate at a cyanide to copper ratio of 3:1 dosed at different cyanide concentrations. It was found that both free and WAD CN depressed gold and silver and particularly iron sulfides in flotation. The depressed gold and silver recoveries were closely associated with the depressed recovery of iron sulfide minerals, suggesting that free and WAD CN may not depress the flotation of liberated gold and silver minerals significantly. It was also found that 10 ppm free cyanide completely depressed the flotation of iron sulfide minerals and WAD CN depression is probably through the WAD dissociation to free cyanide species (mainly aqueous HCN) during the grinding process, resulting from a decrease in pH. Thermodynamic calculation showed that 5.5 ppm free cyanide was released in the end of grinding at an initial WAD CN concentration of 50 ppm. This research provides a guideline to counteract the negative effect of WAD CN in the flotation of gold and silver minerals.CITATION:Guo, B, Peng, Y and Espinosa-Gomez, R, 2013. The effect of weak acid dissociable cyanide on gold and silver flotation in Hidden Valley Mine, in Proceedings World Gold 2013 , pp 341-346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By B Murphy, T Mattsson, R Crosbie, T Maksimainen

"An Outotec e500 TankCell, with 500 m³ of actual flotation volume, was commissioned at the Kevitsa Cu-Ni-PGE concentrator in northern Finland during 2014. This flotation cell was implemented at the head of the existing copper circuit as the first Cu rougher flotation cell. This was the first flotation cell of this size to be run under production conditions by any supplier anywhere in the world.The cell has been in continuous operation since start-up in October 2014 and has provided improvements in metallurgical performance at very low specific power consumption. On average, the cell has recovered 71 per cent of copper contained in the 0.37 per cent Cu flotation feed at a concentrate grade of 17 per cent Cu. The specific power consumption for the cell (excluding blower power) is typically around 0.4 kW/m³.After start-up, the impeller speed and superficial gas velocity were varied and the impact on metallurgical performance measured. In this paper a review of the cell operation at Kevitsa is given. Furthermore, the impact of mixing and gas dispersion on metallurgical performance is presented.Citation:Crosbie, R, Mattsson, T, Murphy, B and Maksimainen, T, 2016. Metallurgical Performance of Outotec's e500 TankCell at the Kevitsa Cu-Ni-PGE Concentrator, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 127–134 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By Casley G. E, Pritchard J

A single slurry fed fluosolids roaster was chosen to replace six multiple hearth roasters in the Copper Smelter at Mount Isa as part of the overall program to increase production from 100 000 to 155 000 tonnes blister copper per annum. The paper describes factors influencing the choice of the unit, problems encountered during the commissioning and details of the present roaster operation.

Jan 1, 1974

By R J. Hardy

The aim of this study is to examine the volumetric and mass movement characteristics of load and haul operations using statistical modelling of relatively large samples of bucket loads that are transported as small samples in the form of truck payloads. Generally, the factors influencing bucket load variability are random, difficult to predict and to control. In the process of loading trucks the underlying variability of individual bucket loads will determine the variability of truck payloads. Bucket loads of material prepared by drilling and blasting for loading into trucks are fundamental quantities in open pit mine production. A study of payload data from a large surface mining operation indicates that bucket loads and truck payloads that are a small sample of bucket loads are normally distributed. Truck payloads have a reduced dispersion compared with bucket loads that is an inverse 0.5 power function of the number of passes per truck payload. Comparison of statistical modelling results with the æ10/10/20Æ policy promoted by Caterpillar Global Mining Inc, indicate that compliance with the æ10/10Æ part of the policy, applying to truck overloading is facilitated, as the coefficient of variation of truck payloads decreases, as a result of the increasing number of loading passes. Compliance with the more stringent æ20Æ part of the policy, relating to safe steering and braking is also facilitated, albeit at lower coefficient of variation for similar reasons.

Sep 26, 2011

By Wencai X

The conversion relationship between the Bond Work Index W1, specific output of mill and the energy efficiency of grinding were developed using dimensional analysis. These relationships were validated and the value of the conversion coefficient ~ was also obtained using a new installed device for measuring grindability of ores. With the new simulating algorithm the mill specifications, output and size distribution of grinding products of industrial mills can be calculated based on laboratory measured results. This algorithm is more accurate and simpler than any of the other empirical relationships. KEYWORDS: Conversion coefficient method, grindability, grinding Constant.

Jan 1, 1993