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This paper presents the results of studying the influence of catastrophic failures arising in mines, on the behaviour of mine ventilation systems. It is very important to take account of this influence for the stable operation of the system and to ensure mine safety when mining underground coal and ore deposits.

Jan 1, 2003

It is suggested that if adequate knowledge is available about classifiers in closed grinding circuits, these units may be used as on-stream size analysers when equipped with suitable sensing devices. Research work which is at present in progress to enable a hydrocyclone to be used for this purpose is discussed.

Jan 1, 1967

More than in any other way, the community judges the minerals industry by its environmental performance. Minerals Council of Australia web site www.minerals.org.au/media/code Time is overtaking us. What was good enough yesterday is not good enough today. What may be acceptable today wonÆt be tomorrow. So we need to leap forward. We need to begin to move towards sustainability. Dick Zandee, Managing Director, Placer Dome Asia Pacific The competition for access to exploration and mining opportunities is intense. So is competition for the best people, capital and community support. Poor environmental performance damages a companyÆs ability to attract these. Quite simply, good environmental management is good business. Hugh M Morgan AO,Chief Executive Officer,WMC Limited. Decisions made by private industry and international corporations are increasingly determining the fate of the environment. ...Nothing could be more shortsighted than for todayÆs conservationists to neglect cooperation with business and industry as a means of moving company philosophy and public accountability ahead in favour of the environment. Dr Claude Martin,Director General,WWF International The four quotes above well illustrate the challenges faced by companies and conservationists in attempting to achieve the societal goal of sustainable development. That this aspirational goal itself is far from clearly defined, although it has been widely accepted and endorsed by governments, business and civil society, exacerbates the challenges. Sustainable development has as its central thesis the integration of environmental, social and economic policy. Its attainment by business has been described John Elkington (1998) as the pursuit of the ætriple bottom lineÆ - the achievement of social and environmental targets, in addition to the traditional economic bottom line. It is self-evident that business is both competent and comfortable defining and measuring economic performance and reporting that performance to internal and external audiences. As long as information has been prepared according to the established standards of measurement and reporting of economic performance, all audiences can have confidence in its accuracy. Business does not enjoy the same competence and comfort with regard to social and environmental performance. This is no startling condemnation of business, any more than it is a criticism of governments, non-government organisations (NGOs) or academia. It is a statement of fact that the tools to allow for credible definition and reporting against the other two components of the ætriple bottom lineÆ have yet to be fully developed and are, therefore, far from being widely accepted. Crucial to achieving sustainability is the ability to measure progress toward the goal. The task is to develop means to define appropriate performance standards and to credibly measure and report company environmental and social performance against those standards.

Jan 1, 2000

By M Kuruppu

The paper explores the sustainability of the Australian mining industry, and the potential for application of a substitute fuel into existing mining operations. This alternative fuel biodiesel is produced from biological oils and not from refined hydrocarbons like the transport fuel diesel (petrodiesel). The fuel is compatible with all current diesel equipment with little to no modification and has many superior properties. As biodiesel is derived from biological sources it is æcarbon neutralÆ meaning there is no net carbon addition to the atmosphere when the fuel is burned. The current fuel, petrodiesel releases long stored carbon dioxide (CO2) and is of concern to Australian government targets which seek to reduce these emissions. The mining industryÆs unique reliance on petrodiesel is of particular interest when assessing the substitution of biodiesel into underground and open cut operations. The underground benefits of biodiesel see a reduction in the noxious emissions of carbon monoxide and diesel particulate matter, both contaminants which require extensive diluting ventilation to ensure safe levels. As biodiesel is both safer to store due to its higher flash point and produces less exhaust emissions, its occupational health and safety benefits in underground mines is clear. The use of biodiesel in open cut mines benefits the environmental sustainability aspects of the project. The formulation of national targets relating to carbon dioxide emission reductions promotes any measure to reduce CO2 within the mining environment. As the diesel engine is one of the least emission efficient (kWh/tonne CO2) energy sources on-site, its potential for reduction in CO2 at minimal cost is the greatest. By substituting the fuel, significant quantities of site emissions are reduced, thereby achieving the goals of improved site sustainability and the governmentÆs targets to reduce emissions. This aspect of gauging mutually beneficial relationship regarding government interests and mining industry profitability is the underlying outcome for this paper.

Jan 1, 2009

By R M. Tosdal

Intrusion related ore deposits are widespread in the Central Peruvian Cordillera Occidental and adjacent high-plains to the east and include porphyry Cu (-Au, Mo; eg Morococha), Cu-Zn (Pb-) skarn (eg Antamina), Pb-Zn-Ag carbonate hosted vein deposits (eg Uchucchacua), cordilleran base metal (eg Cerro de Pasco) and epithermal deposits (eg Quicay). Geochronology and petrochemistry of intrusive rocks associated with mineralisation reveals that: most ore deposits were emplaced in the late middle to early late Miocene; and are related to calc-alkaline granodioritic igneous rocks with Sm/Yb >3, Sr/Y >40 and Y/Th <1.5. The largest deposits, including Antamina, Colquijirca and Cerro de Pasco are associated with intrusions with Sm/Yb >4 and which, as indicated by Pb and Sr isotopic data, have undergone relatively moderate middle and upper crustal assimilation. The chemical signature of igneous rocks related to mineralisation likely reflects melt equilibration in the lower crust at a crustal thickness of more than 45 km. Mineralisation was favoured by a change from normal to flat subduction, resulting in increased compression, crustal thickening and subsequent cessation of the magmatic arc. Premiocene ore deposits do occur, but are restricted to a broad E-W corridor between Uchucchacua and Milpo and probably were controlled by a crustal-scale structural discontinuity across the strike of theAndes. Not all igneous rocks with high Sm/Yb and Sr/Y ratios did acquire their trace element signature in the lower crust. Petrographic and Pb isotopic evidence indicates shallow crustal hornblende fractionation or assimilation of pelitic material as possible causes for high trace element ratios in some rocks. These are apparently unrelated to polymetallic mineralisation. Thus, critical evaluation of petrographic and geochemical data in metallogenetic studies, especially in areas with complex basement architecture such as Central Peru is critical and should not be reduced to simple trace element ratios. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Chile, which hosts around 30 per cent of the worldÆs copper resources, is now the largest producer and exporter of copper. Chilean copper output accounts for more than one-quarter of total worldwide production. An increase to around 40 per cent is forecast by the end of the century. In addition, Chile ranks eighth in silver production and 11th in gold output. In Chile, mining generates more than eight per cent of the countryÆs GDP and the total value of mineral exports is more than US $7.85 billion corresponding to more than 25 per cent of South AmericaÆs mineral production. The rate of growth of Chilean mineral production is indeed impressive. Table 1 shows that in the period 1969 - 1998, copper annual production increased 564 per cent from 667 000 t to 3 764 000 t. Gold production went up 27 times from 1827 to 49 770 kg. Silver output grew 1219 per cent from 95 650 kg produced in 1969 to 1 166 380 kg in 1998. Several facts explain this dramatic increase of production, but the most important was the success of exploration sustained over the same period. This resulted in the discovery of several world-class deposits which when developed into mines, account for much of the production increases. Therefore, this summary review shows the success of basic exploration carried out during the last 30 years in the Chilean territory. The review is based on data already published in different specialised mining books or magazines. It only includes those world-class discoveries not the lesser discoveries important at local scale. All figures were calculated using 1998 $US dollar and average estimated metal prices valid for 1999: copper $US 1653 per t ($US 0.75 per pound), gold $US 9452 per kg ($US 294 per ounce) and silver $US 177 per kg ($US 5.5 per ounce).

Jan 1, 1999

By G L. Simmons, K M. LeVier, R Kappes

The low potential hydrophobic state of pyrite in amyl xanthate (PAX) flotation with nitrogen is of particular interest with regard to the N2TEC flotation technology currently being used for the recovery of auriferous pyrite at NewmontÆs Lone Tree Plant in Nevada. Initially, the N2TEC system had been found to operate satisfactorily, but cyanide in the flotation mill water appeared to be responsible for a loss in pyrite recovery. This supposition was confirmed with laboratory experiments, and a program was initiated to study flotation chemistry variables by electrochemically controlled contact angle measurements. Experimental results show that activation of pyrite in such cyanide solutions can be achieved more effectively with lead than with copper. Subsequently, based on these fundamental studies, significant improvement at the Lone Tree Plant was achieved by lead activation, in which case the recovery increased to expected levels. The effect of activator is particularly significant not only with respect to pyrite depression by residual cyanide, but also with respect to collector (PAX) consumption and the initial state of the pyrite surface. Experimental results show the importance of the pyrite surface state and the rather interesting features of the activation process.

Jan 1, 2005

By Graham M

Longwall mining has been the dominant global coal mining method for decades. However, not until 1994 did longwall mining surpass continuous miner room and pillar extraction tonnage in the United States. This significant event, occurring in the most cost driven market in the world, confirms the efficiency and effectiveness of longwall mining.

Jan 1, 1998

By M Kuruppu

Large mining operations require a high percentage of the capital invested in mobile and fixed mining machinery. From an investment point of view this expenditure must be met by an equally high rate of return, thus the need for high plant and equipment reliability is of major importance. Equipment downtime is undesirable and very costly, resulting in lost production and revenue, which is of critical importance to successful mining operations. One of the solutions to this problem may be found in the form of competent computerised maintenance management software systems, which help to reduce the problem of breakdowns. These software assist the engineers for the management of service orders, resource allocation, progress monitoring as well as costing. They also facilitate the communication of targets and objectives among the service personnel. A computerised maintenance management software called MAINPAC was used to record and plan the activities of mobile equipment maintenance in a large mining operation in Western Australia. Among the details recorded were equipment data, service history, machine downtimes, previous maintenance, job planning and the resource required. This information further helped to analyse the maintenance efficiency, availability and the reliability of the equipment.

Jan 1, 2006

By R Espinosa-G=mez

Industrias Pe±oles, S A de C V (Pe±oles) in Mexico, is a major silver producer. The Pe±oles mining division has eight operations and the flotation process in seven of them to concentrate the metal and mineral values. Common metal and mineral values are: metallic gold and silver; gold-silver alloy (electrum); silver sulfide minerals (acanthite, pyrargyrite, freibergite, proustite); lead sulfide (galena); zinc sulfide (sphalerite); and copper sulfides (chalcopyrite and bornite). This paper aims to share Pe±olesÆs mineralogical and metallurgical information on the seven operations where the flotation process is used. Some basic conclusions are drawn from this analysis. Some of the information presented includes: types of orebodies, concentration processes, concentrator throughputs, head grades, concentrate grades and recoveries. Importantly, grind size and liberation values for the main mineral species are presented along with the relationships between sphalerite liberation and its recovery, and galena liberation and its recovery. Also included are three mineralogical case studies: maximisation of silver recovery at the Fresnillo mine producing a silver-zinc concentrate; options to improve gold recovery at the Tizapa mine; and sphalerite iron content for the different orebodies.

Jan 1, 2005

By D Lees

Safety is paramount in the underground mining environment. The mining industry has for many years focused on injury prevention in the workplace through procedures and training. In the area of control of major accident events that could result in single or multiple fatalities, and serious injuries, the mining industry approach has concentrated mainly on past experiences and lessons learnt. However, in the last 20 years, other high hazard industries, such as the chemical process industry and oil and gas industry have developed the Safety Case approach, using systems safety techniques and risk assessment as a means of identification and control of major accident events. The Safety Case approach is now being introduced into Australian underground mining. This paper describes the Safety Case approach and how this can be adapted to underground mining. This is a holistic approach and assists in ranking significant risk contributors and prioritising risk management efforts. The discussion includes how the Safety Management System interfaces with the Formal Safety Assessment in effectively controlling the hazards. It provides examples from actual case studies conducted by KBR, and suggests ways forward for the industry.

Jan 1, 2003

By McGregor GW

The Utah International group of companies has a wide geographic spread of operations, including a significant interest inAustralia's largest coking coal operation in Queensland, steaming and coking coal mines in USA, a copper mine in Canada, a half interest in an iron ore operation in Brazil, a number of smaller operations, and a significant portfolio of undeveloped properties in South America, South Africa and South East Asia.The opportunity to acquire this group of companies presented an immediate problem to BHP in that it was regarded as too large for BHP to absorb by itself. In addition, there was a concern that such an acquisition would increase BHP's coking coal exposures to unacceptable levels. Despite these dilemmas, BHP was keen to acquire Utah.A plan was therefore developed and agreed to by General Electric (GE) (the then owner of Utah) which would give BHP nine months in which to put together a consortium to share in the ownership of the Queensland coal assets (plus coal assets owned by BHP), and to arrange a project financing for use by BHP and the consortium. BHP would own 100% of the rest of the assets.

Jan 1, 1985

Risk management for resources and reserves includes examining the fundamental processes of data collection, interpretation, modelling and estimation. Newmont Australia has developed a procedures manual to assist mine sites to build Resource block models, estimate Ore Reserves, validate the outcome and report the results. An audit scheme has been developed to compliment the procedures manual by assessing the degree of site compliance with recommended practice. A score of between one and five stars is awarded to each site depending on its performance in the audit. Audits are undertaken by a team of three Newmont personnel over a three to five day period at each site. Scores are ultimately compared between sites and reviewed annually. The objective of the program is to encourage continuous improvement in the modelling, estimation, validation and reporting practices used at sites and in advanced projects. The scheme provides a method of risk management for the companyÆs biggest asset û its Ore Reserves. Newmont Mining Corporation is preparing to use the audit scheme internationally in part to conform with recent legislation requiring US companies to demonstrate that management systems and procedures are in place to monitor and verify the companyÆs assets.

Jan 1, 2003

By Borsaru M

The production of high-grade calcined bauxite is very dependent on the moisture content of the final product. Existing procedures rely on the ignition of small samples to monitor the effectiveness of the calcination process. The results obtained by this gravimetric technique are several hours behind production and do not permit regular adjustment of the furnace to optimize the control of the chemically bound water content (LOI).To provide rapid and hence more relevant results, a neutron moderation technique has been developed for measuring the LOI of bulk samples of calcined bauxite while they are still hot. The method uses fast neutrons from an 241 Am-Be neutron source to irradiate the samples, and the backscattered thermal neutrons detected are a measure of bound moisture content.The rms deviation between neutron and conventional determinations of LOI, in 15 calcined bauxite samples, was 0.08 per cent LOI over the range 0.1 to 0.9 per cent LOI. When allowance is made for the rms error in the ignition method, the error in the neutron method is found to be 0.07 per cent LOI.

Jan 1, 1985

The cement industry requires large quan- tities of limestone, its main raw material. It is the major consumer of this mineral. Limestone is widely distributed throughout Australia but location in relation to major markets, and transport considerations render most deposits of no economic value. Of those which are sufficiently close to the major me- tropolitan markets many are rejected as being unsuitable on grounds of quality, inadequate size for major development, or other reasons such as environmental considerations. Detailed geological investigations are necessary, not only to prove raw material sources prior to establishment of a cement works but also to permit planned extraction programmes and satisfactory grade control during subsequent development. Conventional field techniques have generally proved adequate for raw material exploration. Data assessment and reserves estimation also are by conventional methods although the specific requirements of the industry relating to raw material and cement quality, the type of manufacturing process and fuel used are relevant. A number of case studies from different geological environ- ments are examined and comparisons made bet- ween the predictions of the exploration stage and subsequent experience in quarrying prac- Tice.

Jan 1, 1979

Since 1975 two electric hydraulic drills, a Robbins 11ND and an Atlas Copco C0P1038, have been part of the production drilling fleet at Mount Isa Mines Limited's Isa Mine. As might be expected with innovative and technically more complex machines, breakdowns and mainten- ance problems have been greater than those experienced with pneumatic drifters. This has been especially so with the COP1038 but in co-operation with Atlas Copco, many modific- ations have been made to alleviate operating problems. The training and quality of the maintenance workforce is of great importance. The use of coloured pictorial diagrams for hydraulic trouble-shooting will aid in minimising maintenance downtime. Both machines have achieved good operator acceptance. This is the result of many factors, the major ones being the more acceptable environmental conditions, the relatively low amount of physical effort and the high degree of mechanisation. The drilling area is one in which there is great potential for cost savings and product- ivity gains. Because both machines are capable of a high drilling output, Isa Mine is confident of achieving these aims.

Jan 1, 1978

The scope, pace and depth of mining is creating a need for improved ground control strategies to meet mine safety standards. Ground control and associated conservation problems relating to subsidence and the disposal of mining and metallurgical wastes can be resolved by mine filling with selected reject materials. The lack of suitable criteria to evaluate the applicability of such materials and especially cemented forms of fill is considered. Sulphide wastes, which are prone to oxidize, and cement are inexpensive mine fills, but their incorrect use can give rise to problems which are briefly described. Research work concerned with the utilization of sulphide wastes such as mill tailings, to produce fill with self-cementing properties has shown that the development of cohesion and strength is attributable to natural oxidation processes controlled by the physical and chemical composition of the fill mass. The cementing is caused by a number of oxidation products, and is most effective when the mineral pyrrhotite is present. The concepts of fill design are outlined and various criteria for assessing durability and deformational properties are proposed. Specimens prepared in the laboratory are capable of attaining unconfined compressive strengths up to 28 MN/m2.

Jan 1, 1973

By G L. Simmons, K M. LeVier, R Kappes

The low potential hydrophobic state of pyrite in amyl xanthate (PAX) flotation with nitrogen is of particular interest with regard to the N2TEC flotation technology currently being used for the recovery of auriferous pyrite at NewmontÆs Lone Tree Plant in Nevada. Initially, the N2TEC system had been found to operate satisfactorily, but cyanide in the flotation mill water appeared to be responsible for a loss in pyrite recovery. This supposition was confirmed with laboratory experiments, and a program was initiated to study flotation chemistry variables by electrochemically controlled contact angle measurements. Experimental results show that activation of pyrite in such cyanide solutions can be achieved more effectively with lead than with copper. Subsequently, based on these fundamental studies, significant improvement at the Lone Tree Plant was achieved by lead activation, in which case the recovery increased to expected levels. The effect of activator is particularly significant not only with respect to pyrite depression by residual cyanide, but also with respect to collector (PAX) consumption and the initial state of the pyrite surface. Experimental results show the importance of the pyrite surface state and the rather interesting features of the activation process.

Jan 1, 2005

By Sturgul J. R

ZC Mines investigated a proposal to replace the present underground train haulage system with rear dump trucks. The number of rear dump trucks required to achieve target output and the required mix of trains and trucks during the changeover was of importance to the designers, and a GPSS computer simulation model of the operation was constructed using GPSS/PC, a recent form of the language for the personal computer. Three models were 'constructed to simulate initial and final configurations of underground haulage systems to transport ore from ore passes to the crusher and then to the skip for transport to the surface. The initial model simulated train operation on two levels and rear dump truck operation on a third level. The second model simulated rear dump truck operation on two levels with ore being loaded through the crusher to the skip as in the previous case. The third model replaced the rear dump trucks on the lower level with a train to establish the relative merits of the two methods of transport. The simulations identified equipment numbers, required operating hours and critical points in the operation which can then be addressed by the mine designers.

Jan 1, 1988

By O Ostrovski

Direct iron smelting reduction has been examined using a modified 50 kg induction furnace. The furnace was equipped with continuous raw material feeding, a top oxygen lance, argon bottom bubbling, and sensors for measurement of gas and bath temperatures, gas composition and other parameters. In the base case, iron ore was charged at the rate of 1.5 kg/h, coke flowrate was adjusted to maintain a char fraction in the slag at 30 wt per cent, the oxygen flowrate was 100 Nl/min and the post-combustion ratio (PCR) was 60 per cent. The PCR was varied from 45 to 75 per cent by changing the lance height relative to the bath surface. Smelting reduction of Whaleback iron ore was investigated at different post-combustion ratios and iron ore feedrates using coke and coals with different volatile matter. The rate of iron oxide reduction increased with increasing iron oxide concentration in the slag, with a slight deviation from a linear function. The post-combustion ratio affected iron ore reduction and partitioning of elements between phases in the smelting reduction furnace. The high volatile coal investigated was found to be unsuitable for iron smelting reduction in the laboratory furnace.

Jan 1, 2000