Search Documents

By Smith I. T

Mine operators have long recognised that the results achieved in primary blasting are critical to subsequent mining activities. With the introduction of "in the hole" drills under- ground and the advantages offered by the use of water gels in conjunction with ammonium nitrate-fuel oil (ANFO) explosives, new mining methods have been developed and enabled improvements in older methods. Pumpable water gels have been used with varying success underground. These gels allow a high loading density even in ragged bore- holes. The problems encountered with slumping in upholes is recognised so the current trend is to use these gels in downholes where wet holes are prevalent. Cartridged water gel technology has advanced to the point where it has allowed the replacement of nitroglycerin (NG) based explosives and pumpable water gels. Today, gels can be made as a tampable product for use in development headings or as a slump- ing product for downholes to give an effective coupling. With the introduction of the Tovex« pneumatic loaders, the problems associated with a pumpable gel were eliminated and gave the user the ability to alter his loading density.

Jan 1, 1977

By Kennerley P

A significant part of the reserves of the Southern Coalfield lie beneath major water storages and their impounding dam structures. One of the functions of the NSW Government's Dams Safety Committee is to specify the particular mine layouts which can be used beneath the stored waters according to certain guidelines. A study was made of examples of the two different methods of extraction used under the stored waters as proposed by the mining company according to the guidelines and approved by the Dams Safety Committee. Using both pillar monitoring and mathematical modelling approaches it was shown that the recovery of coal from these layouts could be improved while still ensuring the long term stability of both the underground support pillars and the body of the strata. The integrity of the water storages and their impounding structures would therefore not be Affected.

Jan 1, 1986

By Collins M. J, Ozberk E

A major advantage of the Sherritt Zinc Pressure Leach Process is the conversion of sulphide sulphur in zinc concentrate to elemental sulphur during pressure leaching. Elemental sulphur can be recovered as a marketable byproduct by flotation of the leach residue, and melting and filtration of the sulphur flotation concentrate. The behaviour and deportment of sulphur during pressure leaching, flotation, and melting and filtration are discussed in this paper using data obtained from the treatment of a wide variety of zinc concentrates in the laboratory miniplant at the Sherritt Research Centre. The quality of the elemental sulphur byproduct and a process for purifying the sulphur are also Presented.

Jan 1, 1993

By A V. Ozsever

The selectivity in flotation columns involving the separation of particles of varying degrees of floatability is based on differential flotation rates in the collection zone, reflux action between the froth and collection zones, and differential detachment rates in the froth zone. Using well known theoretical models describing the separation process and experimental data, froth zone and overall flotation recovery values were quantified for particles in an anthracite coal that have a wide range of floatability potential. For highly floatable particles, froth recovery had a very minimal impact on overall recovery while the recovery of weakly floatable material was decreased substantially by reductions in froth recovery values. In addition, under carrying-capacity limiting conditions, selectivity was enhanced by the preferential detachment of the weakly floatable material. Based on this concept, highly floatable material was added directly into the froth zone when treating the anthracite coal. The enriched froth phase reduced the product ash content of the anthracite product by five absolute percentage points while maintaining a constant recovery value.

Jan 1, 2005

By M Kizil

Mining Engineering Degree programs have traditionally had a practical emphasis and have been highly vocational in nature. However, over the years, there has been an increasing attention to the more scientific aspects of the discipline. More recently, the professional institutions, the industry and the community at large have placed increasing emphasis on the broader aspects of the professions: management, finance, humanity, environment and social issues. Notwithstanding this, there has been a continuing emphasis on the practicalities, and most Mining Engineering programs are still strongly vocational in nature. But employers of new graduates complain about the graduatesÆ lack of practicality and readiness for employment æat the sharp endÆ on the mine site.This paper briefly describes some of the more recent developments in the Mining Engineering Degree program at the University of Queensland that attempt to address the problem. Particular attention is paid to alternative learning programs, including applications of virtual reality, practical experience at the University Experimental Mine (UQEM), and the Undergraduate Site Learning Program (USLP).

Jan 1, 2002

By Keele R. A

The Cambrian structure in the Mt Read Volcanics was produced by four deformational events: obduction of forearc-derived mafic/ultramalic complexes in the early Middle Cambrian, a middle Middle Cambrian extensional phase related to the post-collisional Mt Read volcanism and VHMS mineralisation, Middle Cambrian E-W folding, and Late Cambrian N-S folding and basin inversion. The major phase of VHMS mineralisation in western Tasmania is restricted to the very brief period of extensional tectonics within the middle Middle Cambrian. Within this period a N-S graben was produced with a complex series of transfer zones, largely striking E-W. Most VHMS mineralisation is restricted to the top of massive volcanic successions, with several mines close to Cambrian transfer structures. Many of the transfer structures continued to be active until the Devonian. The later compressional Cambrian events are not significant in localising orc formation. Within the Rosebery mine a complex pattern of minor Cambrian normal faults has a second order control on the distribution of the mineralisation.

Jan 1, 1997

Recent and on-going studies on the leaching of gold, the properties and activity of carbon, developments in the elution of gold from carbon, and methods of recovering gold from solution are reviewed. Emphasis is placed on Australian contributions, and their impact on gold metallurgy. Consideration is given to the future development of selective solvent extractants, ion exchange resins or alternative reagents for cyanide.

Jan 1, 1987

This paper describes the new iron and steelmaking process recently commissioned at NZ Steel. Ironsand mined and concentrated at Waikato North head is slurry pumped 18 km to the company's Glenbrook works. Ironmaking includes the direct reduction process pioneered at Glenbrook in the 1970s and a new continuous electric melter. The molten, high carbon pig iron produced is then fed to a vanadium recovery unit and on to the KOBM oxygen steelmaking vessel. Steel is cast into billets or slabs. The new plant, which is the first stage of a fully integrated works at Glenbrook, raises New Zealand Steel's production capacity from 150 000 t/y to 750 000 t/y.

Jan 1, 1986

Biologically-mediated phenomena are involved in many of the natural processes by which mineral deposits are formed and ore bodies transformed and degraded. They may facilitate the environmentally-damaging effects of mining and mineral-processing operat- ions. Under contrived and controlled conditions, however, these phenomena can form the basis for economically- attractive processes for the recovery of metals from low-grade deposits by dump, heap or in situ leaching. They have application also in processes for the regeneration of leaching reagents and some potential for'-the recovery of metals from dilute solution. The micro- organisms concerned are potential sources for the production of novel flotation and solvent-extraction reag- ents. Perhaps the greatest opportunity for biotechnological processes in min- ing and metallurgy lies in the possib- ility of the evolving of novel proced- ures for the substantially complete recovery of metals from process tail- ings by the unlocking of recalcitrant and complex mineral assemblages, and for the beneficiation of some mineral materi,hls.

Jan 1, 1982

By M Chiquito, R Castedo, P Segarra, L M. López, J A. Sanchidrián, J Navarro

The aim of this work is to assess the performance of different constructive solutions against explosions on the strength of masonry walls. The solutions tested, namely an external metal mesh, a glass fibre film on the external face of the wall and a basalt fibre film located on the inner face of the wall, have low to medium cost and are originally designed for other purposes, like seismic protection. Four cubic boxes 3 × 3 × 3 m were built using each of the solutions and typical masonry blocks. In the tests, a spherical plastic explosive initiated in the centre was placed at scaled distance of 2.9 m/kg1/3, so that moderate damage would be caused on the wall. In order to assess the performance of the explosive, pressure gauges were placed at the wall and at different distances from the explosion. Additionally, vibrations were monitored with seismographs in the far field and a high-speed camera was used to estimate the shock wave velocity during the tests. The resulting damage has been evaluated on 13 points of the external wall of each box using a rebound hammer. Damage maps have been drawn for each wall based on these measurements and damage has been assessed inside the box considering the fragments mass launched during the test. The use of external metal mess leads to a decrease of 34 per cent on damage of the external wall and 38 per cent reduction of spalling. The use of a film in the inner wall provides a strong reduction on spalling.CITATION:López, L M, Segarra, P, Castedo, R, Sanchidrián, J A, Navarro, J, Santos, A P and Chiquito, M, 2015. Performance of different constructive solutions against explosions in full-scale masonry walls, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 819–824 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Excavation through fill material in underground metalliferous mines is usually avoided where possible, unlike in Civil Engineering application where excavation through soft ground is normally a matter of course. In the mining situation, where excavation is normally for access only, then excavation designs are engineered for mining in hard rock, except where previous lack of forward planning has made such excavation inevitable or a mining strategy sequence necessitates some mining through fill in order to achieve optimum recovery of ore. Historically, this has been the case, because of the lack of knowledge of the support characteristics of the fill material placed underground and the lack of knowledge of the composition of the fill material as placed. The expertise and experience available from mechanised excavation techniques in Civil Engineering application (shield jacking, forepoling, spiling, and soft tunnel boring, to name a few) are available for application to the underground mining situation if the need ever arises. This paper describes the situations in underground mining development where mining through fill material is required, the different types of fill material encountered and the types of support available

Jan 1, 1981

By I Gipps

The mining industry has come through a period of major change in community expectations regarding safety and environmental impact and these changes can be expected to continue in the future. These changes are ultimately reflected in Government regulations and industry safety standards and form the basis of the ælicense to operateÆ. Equally, advances in technology have made possible new equipment and processes either available now, or close to completion, that will allow mines to meet these more stringent expectations if properly introduced. Changes in technology provide opportunities for mine management to introduce new systems that will remove people from hazardous areas and lead to improvements in the ætriple bottom lineÆ. In a longer time frame of five to ten years, novel and advanced technologies that are currently being developed will deliver new mining methods and conversion of presently uneconomic resources to ore. This is consistent with the time frame required to develop a new mine from discovery. Strategic decisions can be taken now by mine designers to enable the introduction of these major technology changes. Examples of both practical and strategic opportunities are drawn from the integration of rock cutting/blasting, automation, electronic communications and new mining methods. This paper discusses emerging industry trends, changes to legislative framework and some practical choices for existing and imminent technology.

Jan 1, 2003

By M Yahyaei, M S. Powell

Mineral processing plants have become large and complex, generally through progressive expansions. Addition of a pre-crushing stage to conventional Semi-Autogenous-Grinding (SAG) and ball mill - crushing (SABC) circuits has introduced a complex materials handling system coping with +200 mm particles. Application of High Pressure Grinding Rolls (HPGRs) and implementing hybrid comminution circuits (ie, HPGR-SAG mill) requires proactive control of the feed size distribution to each unit. Application of Vertical Tower Mills (VTMs) and other fine grinding equipment to achieve a finer grind size, while maintaining the throughput, requires splitting the feed evenly between parallel units. Many of the conventional comminution circuits (ie, staged crushing and screening followed by staged ball milling) must deal with the transition from open pit ore, which is generally altered and soft, to underground ore, which is intact and hard, requiring existing crushers to produce a finer product to unload the ball mills.This paper presents common process improvement opportunities which have been identified during a number plant process reviews conducted by the authors in Australian and international operations. The operation of comminution circuits to known and accepted standards, which is explained in this paper, could improve the performance of circuits by between 5 and 10 per cent, generally at no capital cost and often at a lower operating cost. The performance improvement can be realised as throughput increase, a finer product size, or reduced operating costs (ie, energy saving, low maintenance, less consumables).Process optimisation opportunities presented in this paper include: enhancing materials handling and storage to avoid segregation; standard operation of screens to reduce misplaced materials; proper feeding arrangement and control of crushers to increase their utilisation; preparing proper feed for SAG mills to reduce grind size; splitting the feed evenly between parallel equipment to improve utilisation, and controlling operation of classification units to improve energy utilisation.CITATION:Yahyaei, M and Powell, M S, 2018. Production improvement opportunities in comminution circuits, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 233–248 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By S Hapugoda, A Edenton, L Lu

The blast furnace cohesive zone has a profound impact on hot metal productivity and quality, fuel consumption, operational stability and the lining life of the blast furnace. The high temperature properties of ferrous burden materials determine the configuration and location of the cohesive zone and have therefore attracted particular attention. While numerous standard testing methods are in use to assess the quality of ferrous burden materials for the blast furnace, these simple tests are generally conducted under fixed conditions, which often represent the extreme situations encountered by the burden materials in the blast furnace. Furthermore, none of these simple tests provides information on the high temperature properties of the burden materials, such as their softening and melting properties. CSIRO is equipped with a fully computerised testing facility to characterise the high temperature properties of ferrous burden materials under realistic conditions similar to those encountered in the blast furnace. This paper will first review the CSIRO softening and melting test method and then discuss the softening and melting properties of a variety of blast furnace burden materials, including sinter, pellets and lump ore, and their implications for blast furnace operation.

Nov 8, 2021

Surface and near surface particulate gold occurs sporadically over an area of some60 km2 between Vunda and Navilawa on the west coast of Viti Levu, Fiji.Background grades of 0.01 ppm can be found in the zone of weathering from 3 to ZQm but, at Vunda, attain significance within certain "localities" ranging from 1000 m2 to 35000 m2 in area. Intense and deep weathering renders geological interpretation difficult but the higher grades seem to relate to equally weathered dykes and apophyses which intrude the tuffaceous country rock.Both country rock (5.4 m.y.) and intru-sives (4.8 m.y.) are of shoshonitic composi-tion and all rocks are consanguineous. At Navilawa, on the eastern end of the zone, basic monzonite crops out as a sizeable stock carrying low grade porphyry-type copper and gold. Between Navilawa and Vunda intrusives are as large apophyses and dyke swarms, and at Vunda, on the western end, only the upper ends of dykes and small apophyses are exposed carry-ing various sulphides, magnetite and rutilein hair line fractures. The level of erosion is thus deeper to the east and shallower to-ward tha wPst_

Jan 1, 1984

By O Ignatenko, A van Schaik

Environmental legislation for the process and manufacturing industries is frequently formulated without considering the fundamental limits of physics, chemistry and thermodynamics within process technology. Recycling of end-of-life goods is used in this paper to show how the limits can be evaluated on the basis of the theory of minerals processing and metallurgical engineering. This theory has been applied on European Union level to re-examine the legislation for automobile recycling in a recent stakeholder discussion involving the automotive industry (http://www.assurre.org). This theory and our models are finding their way into the computer aided design (CAD) tools of the automotive industry, developments that form part of a project to design the super light car of the future (http://www.superlightcar.com). Only such fundamental approaches will in future be able to provide the basis to argue and define realistic and sensible environmental legislation.

Jan 1, 2006

We can look at the water treatment and management strategies at some recently commissioned mines and minerals processing sites to see the likely future of water in mining. The future of water in mining will be based on a holistic approach to understanding the site water balance, appropriate treatment, reuse where possible, and environmentally managed discharge where required. This paper describes advanced and innovative water treatment and reuse processes as used by mines and mineral processing operations from around the world. Underground mining can often require dewatering to prevent groundwater seeping into and flooding the mine workings. Mining and processing often accumulates wastewaters in a tailings dam. The mine water can contain contaminants such as dissolved salts, iron, arsenic, manganese, heavy metals and acidic and odorous sulfates. On-site reuse, environmental discharge requirements, as well as community needs for water, drive mine operators to consider the most appropriate water treatment process. Mining water treatment for the future is described using case studies of innovative processes. The case studies include treatment of mine dewatering water for beneficial application from Australian mines, Ballarat Goldfields and Bendigo mining, treatment of produced water from oil and gas projects, and treatment for arsenic removal of tailings water from mining and processing at Goldcorp mines in Canada. Advanced and innovative processes including membrane filtration, reverse osmosis at extreme conditions, advanced biological treatment and water management are all part of these case studies. This paper uses real case studies of advanced and innovative mine water treatment processes to explain and examine the technology and the reasons for designing specific processes. The focus is on innovative processes that may be more widely used in future mining û where the water is used for sustainable environmental discharge or treatment to a quality that can be beneficially used by the mine or the local community.

Jan 1, 2008

What is `environmental risk'? There are two possible perspectives: (a) The risk that mining activity will have an impact on the environment. (b) The risk that due to a perceived impact on the environment, the mining activity is at risk due to some legal consequence. This paper is concerned with the second of these perspectives, and particularly with the way in which mining companies can manage that risk. Environmental risk - possible legal consequences The risk is that the mining operation will be disrupted. Disruption may be: (a) Physical. The mining activity can be stopped, altered, or modified, or something additional can be required to be done. (b) Financial. Penalties (up to $1M) on corporations and in some states on both directors and managers. Land may also be included on a contaminated land register (significant impact on asset valuation).

Jan 1, 1994

By E Mofya, R Kaunda, P Lever

One of the fundamental requirements for being able to optimise blasting is the ability to predict fragmentation. An accurate blast fragmentation model allows a mine to adjust the fragmentation size for different downstream processes (mill processing versus leach, for instance), and to make real time adjustments in blasting parameters to account for changes in rock mass characteristics (hardness, fracture density, fracture orientation, etc). A number of blast fragmentation models have been developed in the past 40 years such as the Kuz-Ram model (Cunningham, 1983). Fragmentation models have a limited usefulness at the present time because:The input parameters are not the most useful for the engineer to determine and data for these parameters are not available throughout the rock mass. Even if the input parameters are known, the models still do not consistently predict the correct fragmentation. This is because the models capture some but not all of the important rock and blast phenomena. The models do not allow for ætuningÆ at a specific mine site. This paper describes studies that are being conducted to improve blast fragmentation models. The Split image processing software is used for these studies (Kemeny, 1994; Kemeny et al, 1999).

Jan 1, 2001

The mining. operations of Bougainville Copper Pty Limited are located at Panguna on the Island of Bougainville which is part of the Territory of Papua and New Guinea. Mineralisation in the Panguna area was first established by C.R.A. Exploration Pty Ltd in 1964. Exploration work since then has established ore reserves estimated to be 760,000,000 tons of.0.47% copper and 0.4 dwt./ton gold. An economic feasibility study completed in July of this year has enabled a decision to be made to proceed with a major mining operation. The ore will be mined by open cut methods and will be treated in a conventional concentrator with a nominal capacity of 90,000 short tons per day. The concentrate will be pumped as a slurry through a 15 mile long pipeline to a port established on the east coast where it will be filtered and dried ready for export. Other supporting facilities for the mine include two towns, a 135 megawatt steam power station, and access roads.

Jan 1, 1970