Search Documents

By L. W. Burger

The need to establish and harmonise methodologies to quantify air emissions, atmospheric dispersion and the consequences of air pollutants (especially hexavalent chromium) from the ferrochrome industry became important aspects with the increasing demands for comprehensive impact assessments. The paper includes a synthesis of current knowledge on the following aspects: ? Locally and internationally accepted methodologies for the quantification of chromium emissions, including sampling methods and emission factors; ? A compilation of recognised and accepted air quality sampling and laboratory analysing techniques; and, ? Dispersion modelling and impact assessment tools. Depositing and removing materials from the chromium ore stockpile and wind erosion of exposed stockpiles result in mainly chromite emissions unlikely to contain significant amounts of hexavalent chromium. Pre-treatment processes such as drying, crushing and screening also produces chromium emissions, but mainly as trivalent chromium. The smelting of chromium is the major source of chromium emissions - open furnaces have the highest uncontrolled chromium emissions, followed by semi-closed and closed furnaces, respectively. Based on the current knowledge on emission rates, interim emission factors for particulate, total chromium and hexavalent chromium releases are provided. Ambient sampling and analytical methods to determine environmental exposure of the general public require that hexavalent chromium needs to be quantified in very low concentrations. Suggested sampling and analytical methods for both source characterisation and ambient monitoring are provided. The selection between dispersion models needs to be based on the size of the modelling domain and the complexity of the terrain. The discussion on dispersion models includes the US EPA?s Industrial Source Complex Model (Version 3), the AERMET/AERMOD suite of models and the CALMET/CALPUFF suite of models. Guidelines are also proposed for environmental exposure assessments including cancer and non-cancer health effects.

Jan 1, 2004

By P. Perruzza, R. Grandori, A. De Biase, A. Ciamei, A. Busillo

The Turin metro alluvium soil is mainly made of large boulders, cobbles and gravel , few sand and almost no fines. This grain size curve is out of the range of application for EPB and Slurry TBMs. In order to bore 5 of the total 7,5 kms of Line 1 tunnel, two specially designed Lovat EPB TBMs were utilised in combination with a systematic non structural pre-grouting of a small volume rectangular slab just above the tunnel section. The same pre-grouting was not however applicable for lack of access on surface in some sections of the remaining 2,5 km of tunnel that had to be bored below important buildings/structures, with under ground water pressure up to 1,5 bar, with curves radius of 180 m only. For these more critical sections it was necessary to study and implement a new technical solution and improve the capacity of the TBM to work efficiently in EPB mode even in this unsuitable ground and overall conditions. After months of studies the selected and adopted solution has been to inject inside the cutterhead chamber, in addition to the almost standard foams & polymers additive mixes, a suspension of limestone powders. This with the scope of compensating the lack of fines of the natural ground with rock powders.

Jan 1, 2005

It is crucial to reestablish a domestic rare earths minerals production industry to help secure the Nation's clean energy future, reduce the U.S. vulnerability to material shortages related to national defense, and to maintain our global technical and economic competitiveness. Given that the Chinese dominance of the rare earths market has adversely impacted supply stability and endangers the United States and its allies' assured access to key materials, rare earths should qualify as materials either strategic or critical to national security. Further, the U.S. government should facilitate the reintroduction of a globally competitive rare earth industry in the U.S. Realization of this objective requires: ? Developing domestic processing capability so that the U.S. is not primarily dependent on China as a source of rare earth ore, and almost exclusively dependent of China for processing of the ores. ? Providing a mechanism where access to Federal lands for rare earth exploration and extraction is possible, and ? Training engineers to design and operate rare earth ore processing facilities

Jan 1, 2011

By D Chappell

Coromandel Peninsula gold mineralisation has an epithermal style which involves extensive alteration of host rocks and addition of pyrite over large volumes of rock. These altered rocks therefore have high potential for generating acid rock drainage. Natural acid groundwater discharges occur in altered rocks, but not in propylitically altered rock. There is little calcite available in mineralised rocks to neutralise this acid. In contrast, the mesothermal veins of the Otago Schist cause little alteration of the host rock, and that alteration has similar mineralogy to the host rock. Calcite is a common mineral in host and mineralised zones, and sulphides are generally subordinate. Hence acidification of Otago rocks is unlikely. This lack of acidification in Otago facilitates arsenic mobility in solution, up to hundreds of ppm. Arsenic is insoluble under acidic conditions in the Coromandel. Base metals are soluble under acidic conditions of the Coromandel, but they are immobilised by adsorption on to the widespread clay minerals where the solutions are neutralised. Base metals are generally immobile in Otago, but when they are mobilised, adsorption is less effectiveas an attenuation mechanism because clay minerals are rare.

Jan 1, 1998

By H Bibby

Initial analysis of Long Offset Time Domain Electromagnetic (LOTEM) data has traditionally been made in terms of early and late time apparent resistivities. By using more than one grounded bipole as a source, a tensor analysis technique analogous to the method used to analyse DC resistivity multiple-source bipole-dipole surveying may be formulated. We define the æinstantaneous apparent resistivity tensorÆ as the tensor that relates the total electric field vectors at each instant to the steady state (DC) uniform half space current density vectors due to each source. Instantaneous apparent resistivity tensors calculated for a 3D resistivity model suggest that profiles of LOTEM measurements across simple 3D structures can be used to create an image that reproduces the main features of the subsurface resistivity. Where measurements are distributed over an area, maps of the tensor invariants or the tensor ellipses at different times can be made into a sequence of images which provide a way of ætime slicingÆ down through the target structure.

Jan 1, 1996

By Thomas Gregor, Brian Garrod

As the popularity of precast concrete segmental linings for tunnels is growing in North America, some problems related to grouting of, and near, these linings are starting to appear. The installation of a segmental lining behind a TBM requires that the annular space around the lining be quickly filled with grout to prevent collapse of the ground. In practice, the filling of the annulus is frequently delayed and takes place a distance behind the machine typically via grout ports centrally located in the segments. If partial collapse of the annulus has occurred, it may become necessary to use higher grouting pressures in an attempt to distribute the grout. There have been several occasions where these increased pressures have caused damage to the tunnel linings. Similarly, compaction grouting adjacent to a tunnel lining can cause damage. This paper quantifies the effects of such grouting on a typical precast lining.

Jan 1, 2005

Over the past few years, there has been an emerging relationship between business and civil society, especially NGOs. This relationship has the potential to bring about significant change, identifying common ground between commercial and societal interests. The mining industry has been a leader in acknowledging the need for community consultation and engagement. This paper argues that partnerships can make a very significant contribution to the industry as it comes to terms with the dilemma of an open economic system pushing against a closed ecological system.The paper will pose a number of questions: where is the locus for debate about sustainability in the mining sector?; how well embedded within companies are the new competencies that Leon Davis first identified in 1995 for the mining sector?; how has education for mining engineers or exploration geologists changed to prepare people for what are very different expectations within the working environment?; how well is the industry doing in managing its own environmental impact and what is its responsibility to an agenda for sustainability which extends beyond its own operations?;and how can NGO partnerships contribute to more sustainable outcomes? The paper does not aim to answer these questions, but to explore them in the hope that the issues and possibilities raised will contribute to advancing progress towards sustainability within the industry.

Jan 1, 2002

By J Kelly, C Kelsey

The Autogenous Kelsey Axial Displacement (KAD) mill is essentially a short retention time centrifugal mill, designed to effectively harness extraordinarily high concentrations of input energy for efficient particle size reduction. The mill which has an operating duty band extending from primary to ultra-fine also has the unique capacity to generate fine and ultra-fine products from single stage size reductions of either coarse or fine mineral feeds, in both wet or dry operating modes. This paper covers developments following a recent optimisation programme which confirmed that mill shell speed and the velocity differential between the shell and the rotating internal disc assembly tips could be optimised in relation to specific energy for a given feed rate and feed size providing the product size remains constant. Subsequent test-work further demonstrated the versatility of the mill with duties ranging from the removal of surface contamination associated with heavy mineral concentrate particles to the production of premium ultra-fine talc, from a single stage of size reduction. Open circuit grinding of a rougher gravity concentrate to liberate gold ahead of leaching also highlighted the scope for the application of low cost KAD milling for a range of hydrometallurgical feed preparation duties, which involve fine and ultra-fine grinding.CITATION:Kelly, J and Kelsey, C, 2013. Advanced media-free fine and ultra-fine grinding - The Kelsey axial displacement mill, in Proceedings MetPlant 2013 , pp 152-161 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By McLean E. J

Background The resources of the Gippsland Basin include not only the coal and oil for which it is well known, but also the tourism resource and the quality of life which it offers its residents and visitors. To manage this group of resources requires an understanding and ability to predict the consequences of possible developments. The water of the streams and estuaries as a key component as it is both a resource and the means for transporting wastes from one area to another. To aid in the resource planning process there is a need for models of the estuarine hydraulic processes. This paper describes an appropriate modelling technique. Resource use conflicts may arise from developments in the catchment upstream of the estuarine reach. For example the diversion of water for domestic and industrial use will change the velocity and salinity structure of the downstream estuary. In turn these changes will affect sediment distribution and deposition patterns and may impose stress on the biological communities and ultimately on the fisheries resources and water quality. The manager of an estuarine system may have expertise in ecology, hydraulics or another of the specialist disciplines involved, but commonly will not. The manager will identify needs for resource and development and the broad options required to satisfy them. The manager will use these studies as the basis for his/her selection of the option for execution. Thus a model for'use by the manager of an estuarine system must have the following properties: (i) The model must be sufficiently accurate to throw up all the likely options. (ii) The model must be capable of being run by the manager, interactively, to answer `what if' questions. This requirement implies a simple code andhardware limited to a personal computer or possibly a desk top work station. (iii) The model must be robust so that unrealistic input oes not generate apparently useful output, and no output is generated for cases where the model is not designed to give results. (iv) The model must be capable of being used as part of a modelling system comprising models of all the geographic and demographic components

Jan 1, 1992

Kalgoorlie is the main mining centre of the Western Australian Goldfields. Its famous Golden Mile' has been noted for the exceptional width and richness of its goldtelluride lodes. Since the mid-1890s production on the major mines has been maintained practically continuously.Rich ore, though not as plentiful or as rich as formerly, is still (1948) being mined in places. Unexplored areas still remain within the main auriferous belt which offer reasonable chances of success with intensive exploration.Much detailed information has accumulated in recent years through the geological mapping of underground workings by some of the larger mining companies. The purpose of this paper is to correlate observations made in most of the accessible old and recent workings in the mines of the Lake View and Star group and elsewhere.GENERAL GEOLOGYRock TypesThe rock formations are:-1. Fine-grained (older) greenstones, locally referred to as calc schists. There were originally pillow lavas and other flow rocks of basic composition, now extensively chloritised and/or carbonated. Pillows and fragmental flow- tops are recognisable. Intercalated with flows near the top of the series are several beds of sediments.2. Graphitic slates and other more arenaceous sediments.Although referred to as slates, they are rarely more than well-bedded shales with poorly developed fracture cleavage:Thick bands of felsitic rock are found in places.

Jan 1, 1952

By Karsten Beckhaus

"Abstract Tremie concrete for special geotechnical works needs special properties, especially during the casting process. Today’s execution standards for bored piles and diaphragm walls, EN 1536 and EN 1538, as well as the draft version of concrete standard EN 206, all comprise regulations for deep foundation concrete which have not been changed for decades. Considering the recent development in concrete technology at the same time and its actual state-of-the-art, it is essential to develop new normative specifications and specification requirements.GeneralTo allow the required integrity and quality after placing and hardening, concrete for structural elements like bored piles or diaphragm walls, used as foundations of high-rise buildings or as retaining structures for large and deep building pits, must have adequate workability and stability.In addition to requirements on mechanical properties and on durability, both of which have increased within the last decades, concrete must be suitable for being cast in deep or extremely deep excavations, see figure 1. Today’s specialist foundation engineering machinery makes it possible to drill or cut down to in excess of100 m depth. Concrete technology has developed and allows the use of high performance concrete for deep foundations. But is this capability represented by actual regulations?It has become very common for the industry to supply or use concrete with low water cement ratios, nevertheless highly flowable and set-retarded for several hours if needed. Very low water cement ratios allow design strength of 60 MPa or higher (Larisch, 2011), and a very low porosity which is required for a long service life in aggressive conditions, e.g. by chlorides.To achieve best performance, it is obvious that the concrete must completely fill the excavation and fully embed the reinforcement. As vibration of deep foundation concrete is (usually) not allowed and was anyway inefficient, deep foundation concrete must be designed to self-compact under hydrostatic pressure. Generally, it must be considered that after placement the concrete’s quality cannot be influenced anymore. Therefore, both the pouring procedure and the concrete quality must be adequate."

Jan 1, 2014

When xanthates or dithiophosphates are used as collectors in sulphide ore flotation, adsorbed species may be identified by gas chromatography of the volatile products formed during low temperature pyrolysis. For collector additions ,as low as 20 g/tonne of ore, pyrolysis of the flotation products usually gives' an olefin directly related to the particular xanthate or Aerofloat reagent used. The method is able to provide valuable qualitative and quantitative data relating to the extent of collector adsorption and the resulting changes in the hydrophilic or hydrophobic nature of the mineral surface.

Jan 1, 1974

By A. L. Edwards

A two-year study focused on current noise exposure levels in the South African mining industry, aimed at helping the Mine Health and Safety Council of South Africa meet its milestones for eliminating noise-induced hearing loss (NIHL). Methods A multi-task methodology was adapted from international baseline studies to determine the exposure to noise in both large-scale and small- to medium-scale mines. Results On average, 66.7 per cent of the employees sampled in year 1 and 78.4 per cent in year 2 were exposed to noise levels of above the 85 dB A legislated occupational exposure level. Conclusions Information obtained through the study could be developed into a national personal noise exposure database, including audiometric results, equipment noise emission levels and initiatives for noise engineering control by mines and equipment manufacturers to facilitate targets of eliminating NIHL. Keywords Noise exposure levels, mining industry, noise-induced hearing loss

Jan 1, 2011

By W Taylor, S Chen, R Haywood, M White, R West, J Ranasinghe

In March 2012 a combined BHP Billiton and Hatch team embarked on a program to improve the concentrate burner efficiency of BHP Billiton’s Olympic Dam copper flash smelting furnace. A multi-faceted approach including an analysis of the furnace using operational knowledge and first principles engineering led to the design and supply of a new central-lance (disperser). A new, patented, swirl method of introducing the copper concentrate into the furnace was developed to integrate with the existing concentrate burner. Plant trials in 2014 demonstrated an increase of nearly 10 percent in the oxygen efficiency of the furnace. The improved efficiency is expected to provide savings in operating costs and asset life extension of downstream gas and dust handling equipment.CITATION:White, M, Haywood, R, Taylor, W, Chen, S, Ranasinghe, J and West, R, 2015. Improved copper flash smelting at Olympic Dam, in Proceedings MetPlant 2015, pp 382–395 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

Reduce accidents associated with handling of the electrical trailing cable and the water hose on mining equipment. Approach Two reels were mounted on a loading machine to store and release the lines as required during face operations. How It Works A hydraulic motor, which is actuated by a treadle valve in the operator's cab, controls the reel on which 50 feet of electrical power cable is stored. A spring motor resists unwinding of the other reel on which 50 feet of water hose is stored. Both reels are mounted on the right rear of the loading machine. See Figure 1. Following common mining practice, the cable and hose are anchored to fixed points at the first intersection outby the face. Tramming forward causes the cable and hose to be pulled from the reels. Depressing the treadle valve causes the electric cable reel to turn and wind-in any slack in the cable. The spring tension on the water hose reel automatically rewinds the water hose when the loader is trammed in reverse.

Jan 1, 1978

By R Adofo

Underpinning the mining process is a continuum of prediction, specifically of tonnes, grade and recovery from exploration to grade control, through short-term mine design, to mining and processing. The interdependence of one activity on the other is so strong that it can be difficult to partition the activities and determine where there are issues, if any. Reconciliation is the process that compares the predictions of the various estimates to the actual product produced at the end of the production chain. Quite often, an attempt to understand the variances from one measuring point to the other creates a ‘wicked problem’.This study outlines the benefits of incorporating the principles of ‘systems thinking’ into the mining reconciliation process, by constructing a framework within which reconciliation is effectively managed. The philosophical base for any variances between successive links in the reconciliation chain cannot be attributed purely to the statistical variance between the predicted and the actual grades achieved, but should include the interrelationships between the technical and managerial professionals involved. Systems thinking, as an interdisciplinary approach, draws its ideas and concepts from a variety of disciplines, and in so doing can exploit their different strengths.The study described in this paper offers methodologies to analyse the task, in advance of developing a technical solution. Two systems thinking methodologies, Grounded Theory (GT) and Soft Systems Methodology (SSM) were employed. These methodologies, are geared towards dealing with relationships and interactions between individual parts and the whole. The GT coding in the study specified that the key activity that would drive the reconciliation process is through an effective reconciliation meeting, and the competencies of a ‘reconciliation team member’ This team member should be a good communicator and enjoy challenges, be open-minded and transparent, and have a broad perspective of the mining process and relationships across the different activities.CITATION:Adofo, R, 2017. A systemic approach to managing the Mine to Mill reconciliation process, in Proceedings Tenth International Mining Geology Conference 2017, pp 95–102 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

The only significant iron ore deposit in Hungary could be found in Rudabánya. The mine was closed in 1986. The area of Rudabánya was always the home of heavy mining activity. In former times, mainly silver and other non -ferrous metals were excavated.

Jan 1, 2011

By Y Miyoshi, J Ishibashi

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Sea floor hydrothermal activity in the Okinawa Trough is considered a modern analog to ancient Kuroko-type volcanogenic massive sulfide (VMS) deposits. Recent scientific drilling projects at active hydrothermal fields have enabled us to conduct comparative studies on hydrothermal clay minerals between ancient and modern systems. Zonal distributions of clay minerals below the sea floor of an active hydrothermal field have been revealed, which is represented by the distinctive assemblage of clay minerals. Zone 1 consists mainly of montmorillonite and sometimes of kaolinite; Zone 2 consists of chlorite and chlorite-smectite mixed-layer mineral; and Zone 3 is represented by the co-occurrence of illite and chlorite, from shallow to deep. This zonal distribution is likely to be in accordance with that reported previously for the Kuroko-type ore deposit. Similarities are also recognised in chemical compositions of illite and chlorite, which are both abundant clay minerals in the vicinity of the ore deposit. While illite would be formed by interaction with the hydrothermal ore fluid, the formation of Mg-rich chlorite is attributed to Mg metasomatism caused by the involvement of sea water. Further studies, especially focusing on interactions between fluid and solid phases, would significantly promote our understanding of dynamic processes for the formation of VMS depositsCITATION:Ishibashi, J and Miyoshi, Y, 2015. Hydrothermal alteration process in active sea floor hydrothermal systems in the Okinawa trough, from a viewpoint of a modern analogue for the Kuroko-type volcanogenic massive sulfide deposits , in Proceedings PACRIM 2015 Congress, pp 481–486 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By I. Ocak

Initial investment for mechanical boring of tunnels is found to be high in most cases. Conventional drilling and blasting is not the possible especially in urban area. In these conditions impact hammer offers many advantages over conventional drill and blast techniques and boring tunnels. These include improved safety, minimal ground disturbances, elimination of blast vibration, reduced ventilation requirements, reduced cost etc. Therefore, hydraulic impact hammers have been used widely in metro tunnelling projects in Istanbul since 1992. Accumulated and published data from various tunnelling projects serve to improve predicting the machine performance and scheduling of job duration. This paper is prepared under this objective. Machine utilization time of impact hammer was evaluated in this study. The main rock formation named Kartal formation arepaleozoic aged sedimentary rocks, shale, sandstone, siltstone, andesite dykes and sediment fillings. The first stage of the project is commissioned to Yapi Merkezi- Yuksel- Dogus- Yenigun- Belen consortium.

Jan 1, 2011

By F. Dai

Due to difficulties associated with gripping in direct tension, indirect methods are commonly used to measure rock tensile strength. In this work, we adopt an innovative indirect tensile test method: Semi-Circular Bend (SCB) to measure the tensile/flexural strength of Laurentian granite (LG). The static tests are carried out with a servo-controlled material testing machine and the dynamic tests are conduced with a Split Hopkinson Pressure Bar (SHPB) system. Pulse shaping technique is adopted to achieve dynamic force equilibrium in SHPB to facilitate data regression. Finite element method is used to relate the failure load to the tensile strength. Strong rate dependence of the tensile strength is observed. The flexural strength is higher than the tensile strength measured using Brazilian Disc (BD). This difference is rationalized using the non-local theory. To further validate the method, a coupled Finite element/Discrete element method (Fem/Dem) in conjunction with the smeared crack model is utilized to simulate the fracture process during dynamic SCB tests. The resulting fracture patterns are qualitatively consistent with those from recovered samples. Both the experimental and numerical methods have validated the results and this new method is readily to be used for other rocks and other brittle materials.

May 1, 2009