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By D Baas, Y Atasoy

With increased pressure for companies to cut costs during design of new mineral processing plants, overall plant design has changed over the last decade with less design for feed blending and less installed surge capacity. This has changed the operability of new mineral processing plants, where disturbances due to variable ore types have resulted in the evolution of new control techniques. These techniques are necessary to maintain stability and optimise the performance of these new plants. This paper describes the benefit of applying these new control techniques in a new mineral processing plant in Australia utilising RockwellÆs ControlLogix system architecture.

Jan 1, 2008

The writer had the pleasure of several months' laboratory tests on a metallurgical process for copper ores devised by Mr. W. H. Corbould, Consulting Engineer, North Queensland. Mr. Corbould's research work in this direction commenced somesix years ago, and he eventually succeeded in obtaining a good extraction of copper and a resulting solution practically free from iron and other impurities. The commercial operation of the process was investigated and special machines with novel features were designed. OUTLINE OF THE PROCESS.The process described in detail in the following pages, required for successful application that the ores contain at least the minimum ratio of sulphur to copper, consistent with the production of sulphadising roasting conditions.

Jan 1, 1921

By M Forbes, R Jeuken

Brownfields geoscience measurement such as drilling and surface geophysics can be costly and it is often difficult to weigh the cost of data collection and processing against the value it unlocks at the time of extraction. This makes it difficult to prioritise geoscience expenditure and find the optimum intensity of geoscience activity across competing assets. There are multiple options for managing resource uncertainty and spatial variability through mine planning and resource engineering such as varying marketing strategy, adjusting stockpile or other infrastructure design and product blending. Consideration of these alongside increased data collection further complicates finding a comparable value of geoscience programs to determine the right blend of geoscience measurement and engineering controls. Concepts similar to Value of Information (VOI) analysis which is applied to strategic planning can be used to estimate the value of geoscience measurement and pit sequencing at tactical planning and operational timescales. This involves the quantification of resource uncertainty and prediction of how it will affect resource extraction. This paper outlines this process and demonstrates its use to prioritise geoscience at BHP Coal Assets. The value of infill drill programs in enabling operational stability is quantified and compared the value of engineering controls like increased stockpile capacity. This study supports that idea that the application of VOI methods to bulk mining at tactical time horizons has potential to inform geoscience planning and resource engineering not just separately, but as part of a unified strategy for managing resource uncertainty.

Mar 22, 2022

By M E. Webb

Safety is a key value in most leading mining companies. Despite years of effort, and significant expense in ‘programs’, operating sites seem to have been left with no real improvement in either the elimination of fatalities or sustained reduction in injuries.Safety systems and processes have grown and evolved, often to the point where they have become overly complicated and marginally useful.MMG Limited, following the consolidation of its Australian operations under a single management structure, undertook a program to effect real and sustained change in its approach to managing safety. The program aimed at improving safety by better engaging its workforce and by making safety processes simple, useful and effective. It defined the role of the supervisor in creating safe work, the role of the people doing work and the role of safe work methods.A safety diagnostic tool was developed to assess site against safety-critical mindsets, behaviours, cultures and systems. The outcome of the diagnostic is considered by the organisation to be the true lead indicator of safety performance.While still a work-in-progress, the program at the Australian Operations of MMG Limited shows that challenging common paradigms in safety management can create real change in safety performance.CITATION:Webb, M E, 2016. Making safety simple, useful and effective, in Proceedings International Mine Management Conference, pp 217-223 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By N Murphy and, S Santomartino, M Cramer

Acid rock drainage (ARD) can have detrimental effects on mining infrastructure, water reuse options and environmental discharge. As a result, some form of short- or long-term treatment is required at many mine sites. Successful treatment depends on a number of factors including the selection of an appropriate treatment technology and its correct implementation. A variety of passive and active technologies are available for dealing with ARD. Passive treatment solutions do not require continuous chemical inputs but take advantage of naturally occurring chemical and biological processes. They are often low cost, site specific approaches and are predominantly used in post-closure situations. Passive systems are well suited to drainage with low acid loads and low soluble aluminium concentrations, and are more effective with highly reduced (ie low oxygen) water. While they are often regarded as permanent fixes, most require some form of ongoing maintenance and all have an engineered life expectancy (ie finite carbonate and organic matter budgets). Passive treatments include, oxic limestone drains, anoxic limestone drains, limestone diversion wells, various reducing and alkalinity producing systems, pyrolusite limestone beds, aerobic and anaerobic wetlands, permeable reactive barriers (organic ¦ carbonate and zero valent iron), slag leach beds, and gas redox and displacement systems (GaRDS). Active treatment solutions require a continuous or semi-continuous activity (eg reagent dosing) to correct water quality issues. They can be engineered to treat virtually any type of drainage or site specific ARD issue, and have no set acid load or redox limitations. Tasks handled by active treatment systems are almost invariably larger and more costly than for passive systems. Active treatment approaches include; pH control, adsorption/absorption, ion-exchange, electrochemical concentration, biological mediation/redox control, flocculation/filtration and crystallisation. A range of generally available and proprietary technologies has been developed around these approaches. Active treatment involving pH correction with alkaline amendments is the most common and cost-effective form of ARD treatment. A variety of fixed plant and portable treatment systems are available. Calcium-based reagents, including quicklime (CaO), hydrated lime (Ca(OH)2) and limestone (CaCO3) remain the reagents of choice for the majority of active ARD treatment worldwide. This is principally due to their widespread availability, non-proprietary nature, and variety of proven dispensing technologies and cost-effectiveness. Limestone, in particular, is a very low cost reagent. However, due to æefficiency of useÆ problems with limestone in passive treatment systems, combined with its very low cost, there has been a recent emphasis on developing active treatment systems that use limestone efficiently. As the requirement for treatment increases, there is a growing emphasis on treatment sludge management and sludge stability. The final choice of a suitable treatment technology is dependent upon water chemistry (eg pH, type of metal contamination, acidity), flow rates, acid load, local natural resources (neutralising materials, topography), climate, site logistics, environmental risk and economics. The benefits and limitations of both passive and active treatment technologies are summarised.

Jan 1, 2003

By H Holmstr÷m, A Widerlund, M Lindvall

At the Kristineberg mine in northern Sweden sulfide-rich, poorly buffered tailings have been deposited in five impoundments located along a valley. The tailings area has been remediated by applying a combination of till cover and flooding. A new method that has been applied to parts of the tailings area is to raise the groundwater table to saturate the tailings. By increasing pH by liming, thereby reducing metal mobility, a water-covered downstream impoundment is functioning as a trap for metals released from the till-covered impoundments upstream. In this paper the efficiency of the system approach used at Kristineberg is evaluated. Progressive changes of water quality from groundwater in the upstream till-covered impoundments via surface streams within the pond system to the water in the flooded downstream pond and its outlet are described. The results show that the system approach used in the design of the remediation programme of the tailings works as planned. The sulfide oxidation rate has decreased in the till-covered impoundments, and, as predicted, there is an out-flush of old weathering products which will continue for at least five years before equilibrium is reached. The groundwater in the till-covered impoundments has high concentrations of Fe, S, Mg and Zn, but the concentrations of metals such as Cu, Cd and Pb are much lower than before the till cover was applied. The limed pond is an efficient metal trap, with concentrations as high as 2.76 per cent Zn and 0.28 per cent Cu in the calcite-gypsum sludge developed on the tailings. The outlet from the flooded pond, and thus from the whole mining area, releases small amounts of metals to the recipient in comparison to the amounts that are in movement within the mining area. During the period May to November, 13 kg dissolved Zn and 111 kg particulate Zn was released to the recipient, whereas a total of 27 000 kg was transported by surface water within the impoundment system during the same period. The results from Kristineberg show that when planning remediation of complex mining areas, it is useful to adopt a system approach in which different methods are used on different parts of the area along the flow path of the drainage water, whereas flooding of the downstream pond is the key to the performance of the entire system.

Jan 1, 2003

By D Brett

The Paper presents the authors thoughts on how the mining industry should be improving the education of site personnel so they can provide a greater level of effective control of tailings dam safety including empowerment to develop their own documentation, monitoring and surveillance systems and to better liaise with specialist external technical staff or consultants.

Jul 1, 2021

By B Chapman, B Gaida, L Drowley

The 372 MW Ulu Jelai Hydroelectric Project is a peaking power scheme located in the Cameron Highlands, Malaysia. The main features of the project include an 84 m high roller compacted concrete dam; two weirs which divert flows from adjacent catchments via transfer tunnels into the main reservoir; an underground power waterway; and an underground power station complex comprising three large caverns with connecting tunnels approximately 240 m below surface level. The project includes approximately 25 km of tunnels excavated in fresh granite rock mass with some distinct shear zones of weaker material. The majority of the tunnels are being excavated using drill and blast, with the two transfer tunnels being excavated with a tunnel boring machine (TBM).This paper focuses on the design and construction of the Telanok underground power station complex and also some aspects of the design for the headrace tunnel. Topics covered include geological site investigations including in situ measurements of rock stresses; development of a geological model and parameters for rock support design; three-dimensional modelling to assess interactions between the caverns to optimise rock support; design of a rock anchored crane beam; construction of the caverns and design of the unlined headrace tunnel taking into account hydraulic jacking and operational pressure fluctuations.CITATION:Drowley, L, Gaida, B and Chapman, B, 2014. Design and construction of large caverns in granite – Ulu Jelai Hydroelectric Project, Malaysia, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 361–368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By R Talebi

A research project to better understand the rock mass behaviour and the seismic response has been conducted during the design and construction of the 9215 level at the E-Block sector of the Northern Star Kanowna Belle Mine. The research program was undertaken at a tunnel located 1100 m below the surface with the results applicable to feasibility studies on underground mining projects in highstress conditions, where failure can occur very soon after tunnel construction. Semi-circular excavation shapes coupled with the use of de-stress blasting techniques were designed to monitor the excavation in conditions of very high stress. The ground support was designed considering high energy dissipation ground support schemes (HED) as described by Arcaro et al (2021). The results indicate a decreased rock mass demand due to the change of excavation shape. Also, localised reduction in rock mass stiffness was achieved due to the implementation of de-stress blasting. Finally, increased ground support capacity was gained by the implementation of the high energy dissipation ground support schemes. The Kanowna Belle Mine has significant ore reserves at depths exceeding 1000 m below the surface. The results of this research will be used to optimise the extraction of the remaining E Stoping Block at depths exceeding 1350 m.

Mar 29, 2023

By B Beale

Bow-tie analysis is a commonly used tool to identify and display risks that have the potential for an undesired hazardous event. The output of the analysis are bow-tie diagrams, which are an effective and versatile communication format that can be applied to any type of risk. Contrary to their simplicity, a proper bow-tie diagram that maintains its usefulness and clear communication is difficult to build. Over two decades assisting Major Hazard Facilities with bow-tie analysis for Safety Cases, several common mistakes have been identified. This paper aims to highlight those issues with examples and provide improvement strategies. A sample of the most common mistakes are: - overly complicated risk analysis - poorly scoped and defined terms - poor descriptions and justifications - identifying too many dependent controls. Overly complicated risk analysis leads to wasted time in obtaining data for little gain. The bow-tie diagram is only a model. Effort should be redirected into identifying and managing controls that will make a tangible difference to site risk. Broad scopes lead to enormous and confusing bow-tie diagrams for both the user and the workshop team. Defining the scope of the study, the consequence severity of interest and critical control characteristics creates focused workshops and targeted analysis. With more definitive scope, there may be more bow-tie diagrams, however, they are succinct and specific. Well described causes are imperative for clear communication to users, regulators and future bowtie review workshop groups. It is best to use common wording structures and explain the event stepby- step. Also, clearly document any likelihood calculations and use data references where applicable. Identifying all possible controls creates a false sense of security that there are many layers of protection. In reality, most controls are dependent on a single system or person and could all be compromised from a single failure. A definition of a ‘bow-tie’ control is required whereby it must be independent from other controls. Improving the bow-tie analysis process will assist operators in developing meaningful and ‘operational’ bow-tie diagrams to support risk management systems and practices.

Apr 16, 2024

By A S. Derrington

This paper describes a hybrid ventilation system, which uses secondary fans that also act as de-facto primary fans to extract fresh airflow from the mine intake raise system. Also discussed are the associated problems such as uncontrolled recirculation, inadequate decline airflow, fire safety issues, prolonged blast fume clearance times, high air temperatures in main access routes, neutralisation of mine air cooling by heat from secondary distribution fans, increased ventilation system complexity, reduced flexibility and high pressure differentials (which cause safety issues with personnel access and reduce secondary ventilation system performance).Practical suggestions are provided on options to avoid these problems listed.CITATION:Derrington, A S, 2013. A critique of the push-pull hybrid ventilation system, in Proceedings The Australian Mine Ventilation Conference , pp 73-78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By T Leach, I Pringle

The Bowdens Silver Deposit is a low sulfidation epithermal silver-base metal deposit that has formed on the northern margin of a hydrothermal system within air-fall breccias, ignimbrites and crystal tuffs of rhyolitic composition. The deposit lies near the north-eastern margin of the Lachlan Fold Belt and the rhyolitic host rocks are of Early Permian age. The silver mineralisation occurs as flat-lying zones of disseminations and silicic fracture-filling within the Rylstone Volcanics and is closely associated with sulfides of iron, arsenic, lead and zinc. High-grade silver mineralisation is also found in steeply-dipping fracture zones which host banded sulfide veins. Studies of the alteration products indicate that high temperature fluids, flowing from south of the current project area, resulted in quartz (¦adularia) û illite/sericite alteration. Cool, low pH steam-heated waters on the northern and eastern margins of the prospect area resulted in siderite û smectite-illite clay û Fe-carbonate û marcasite û kaolinite alteration. Mixing of the two fluid types resulted in the deposition of iron and base metal sulfides, a decrease in both sulfur activity and pH of the mineralising fluid, and subsequent silver mineralisation.

Jan 1, 2004

By Bhattacharyya A. K

In this paper, the current methods for predicting surface subsidence due to underground coal mining are evaluated first. A single index, called a strata parameter (P), is then proposed to describe the overall character of the undermined strata in the context of surface subsidence. Based on the strata parameter, a method for predicting the maximum surface subsidence for various panel width (w)/depth (h) ratios is presented, which has been tested against specific empirical curves or data from several coalfields in different countries. From the data relating to several coalfields, a linear relationship between the reported average angle of draw and the strata parameter has been established. It has also been found that the strata parameter can be used for studying the locations of the inflection points and the shapes of transverse subsidence profiles.

Jan 1, 1995

By J J. Grobler

The George Fisher Underground Mine at Mount Isa applies the long hole open stoping methodology. During the reconciliation process of transverse stopes in the George Fisher North mine it was identified that excessive underbreak was regularly experienced, with the major contribution coming from the toe area inside the stope.While over break and the resultant dilution was well investigated and well understood, limited work was done on underbreak improvement. It was decided that a re-engineering process would be followed in an attempt to improve results. The prevailing stoping practices were scrutinised and the possible causes were listed.Some of the identified causes were design, drilling accuracy, equipment condition, mucking practices and direction of firing. It was identified that in most instances the underbreak was initiated in the slot area of the stope during the first firings. Once this happened, it was impossible to get good recoveries on the rest of the stope. The slot area was carefully scrutinised and the blasting practices were changed individually.During the following two years several different strategies were trialled to increase the toe recoveries. The results indicated an overall improvement of six per cent reduction in underbreak on average, by ensuring drilling accuracy and changing the direction of firing. The economic significance of these results outweighed the time and additional work load expended to establish the cause of the problem. This paper outlines the continuous improvement process undertaken to identify and rectify the major contributing factors to the problem. It also presents a set of recommendations to be followed in order to achieve positive results.

Mar 21, 2011

By A Manfrino

The Iron Bridge magnetite mine and infrastructure project is currently in development as a joint venture between Fortescue Metals Group, Formosa and Baosteel. It is supported by an extensive database of reverse circulation drill hole samples analysed by X-ray fluorescence (XRF), with a large subset tested for concentrate mass recovery, concentrate and tail grades by Davis tube recovery (DTR) testing. A limited number of rock physical testing results, including unconfined/uniaxial compressive strength and crushing work index, completes the database.By combining all available information – assays, DTR results, geology, stratigraphy, mineralogy and rock physical results – and using multivariate statistical analysis techniques, the impact of the critical factors that control concentrate quality, mass recovery and grindability characteristics have been outlined. A set of geochemical groups was created by using a cluster analysis technique from the combined XRF-DTR data. These groups allow optimal separation of material with consistently high concentrate Fe grades and mass recovery. This approach is superior to domaining based on stratigraphic logging or mass recovery as it is commonly used in standard magnetite estimation models. Using the results of a normative mineralogy study, the main geochemical groups were given a mineralogical profile fitting their geochemical characteristics. These findings further refined the understanding of the link between the process characteristics of the samples and their geochemical signature and mineralogy.The geochemical grouping defined on head grades and DTR concentrate mass recovery was generalised into a ‘geomet’ code based solely on the routinely assayed head grades, thus bypassing the need for systematic DTR testing. The geomet code identifies spatial domains with homogeneous geochemistry, mineralogy and process characteristics in both oxide and fresh material that form the basis of the current Iron Bridge resource model. The allocation of geometallurgical characteristics in terms of concentration amenability and concentrate characteristics on a block-by-block basis over the whole project allows for an optimum mine schedule and plant feed. This ensures that the desired concentrate characteristics and mass recovery can be better predicted over the life-of-mine, thereby improving the mine’s economics and stability by derisking the mine schedule and optimising the performance of the concentrators. A key benefit of the geomet code devised for the Iron Bridge mine is that it can be attributed in an automated manner to all samples analysed for a routine XRF analytical suite, from exploration to blasthole drilling. This allows each sample to be allocated to a geometallurgical material type with predictable process response in terms of concentrate mass recovery and concentrate quality without the need to complete systematic DTR testing.A standard multivariate analysis coupled with a cluster analysis has allowed the linking of interdisciplinary results between geology, mineralogy, geochemistry, process and metallurgy to better understand, predict and ultimately mine and process the Iron Bridge deposits. This allows plant operations and product quality to be optimised through each stage thanks to the predictable ore characteristics embedded in the mining model.CITATION:Manfrino, A, 2015. Unravelling the factors impacting on concentrate quality by geometallurgical data analysis at Fortescue Metals Group’s Iron Bridge magnetite mine, in Proceedings Iron Ore 2015, pp 567–578 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By J Rutter, D La Rosa, P Walters, M Scott, L Keeney

Bulk ore sorting technologies, whether surfaced based or penetrative, have seen an increased uptake by the mining industry for preconcentration application. As with all technologies, going through the technology validation process is key to de-risking the operationalisation of the technologies and to demonstrate and confirm predicted value propositions. The ability to laboratory calibrate cross-belt bulk sensors is standard practise for sensor vendors, however transitioning the technology from laboratory to real-world application is a non-trivial process. The industry has taken two main approaches to trialling and validating bulk sensing technologies in operational environments, namely:  Construct an off-line pilot facility at scale, or  Install bulk sensing systems on production conveyors Each of these two approaches have significant advantages and disadvantages and require different experimental design programs and analysis methodologies. Consideration of material movement, heterogeneity degradation, logistical requirements, and financial investment all factor into which approach is most suitable for an evaluation scenario. CRC ORE in partnership with mining companies, have conducted several bulk sensor pilot trials utilising different sensor technologies employing each of the two main approaches outlined above. This paper describes the challenges faced, learnings obtained and outlines a position on how to transition bulk sensing technologies from the laboratory into the operating environment. The case studies presented cover a range of commodity types in both open pit and underground operations.

Nov 10, 2020

By D Martin

The Rio Tinto (Mount Bruce Mining Pty Ltd) Koodaideri Iron Ore Project is located approximately 110 km north-west of Newman in the Pilbara region of Western Australia. During detailed ecological studies of the project area, a significant maternity roost (containing around 430 individuals) of the Orange Leaf-nosed Bat (OLNB) (Rhinonicteris aurantius) was discovered within the boundaries of the proposed mining area. The OLNB is listed as Vulnerable under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 and is listed as a Schedule 1 species under the Western Australian Wildlife Conservation Act 1950.With a good understanding of blast vibration attenuation in the Pilbara’s different geologies and in the absence of other known studies, it was considered that appropriate buffer distances between mining and bat colonies were not scientifically determined. Therefore, to inform the environmental approvals process that was underway, a series of seismic blasts was planned to assess and measure the sensitivity of the OLNB to trial-sized seismic blasting activities to develop a more scientifically based buffer zone for the protection of the OLNB. This was to be achieved by testing ground attenuation of the site and measuring any response from the OLNB to the firing of seismic charges. Rio Tinto sought the independent expertise of ecological consultants to evaluate and participate in the work to quantify the level of sensitivity of the bat colony and to outline the proposal to government authorities.After detailed risk assessment and project mapping, the seismic blasts were implemented, with the aim of firing individual charged and measured vector peak particle velocity (VPPV) at the OLNB roost cave, combined with monitoring OLNB disturbance activity within the roost that was invoked by the blasts. A series of six charges were fired with the VPPV ranging from 0.66 mms-1 to 18.70 mms-1. The OLNB activity was monitored using high frequency microphones, which detect bat calls emitted during flight. Under daytime conditions, the bats would normally be dormant, so the null hypothesis was for no calls to be detected if the bats displayed no disturbance behaviour. This work has improved understanding of mining activities (blasting) on the OLNB species, assisting in establishing mining exclusion zones that are based on scientific data, contributing to a sustainable future for both the environment and the mining industry.CITATION:Martin, D, 2015. Scientific evaluation of fauna sensitivity to blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 519–526 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By R Shaw

There are many small to medium carbonate hosted complex zinc containing deposits where the zinc is not economically recoverable either as concentrate or metal. High grade (>20% Zn) run of mine ore can be processed but even this material gives relatively poor returns. Considerable effort has gone into developing new technology for either upgrading the ore and/or recovering zinc metal hydrometallurgically but there has been limited success. Minetometal has developed a process capable of economically treating these deposits to give marketable lead and zinc products. This paper reviews alternative processes for these ores and gives a detailed description of the Minetometal Process. CITATION: Shaw, R, 2018. Processing carbonate hosted zinc-lead ores, in Proceedings Complex Orebodies Conference 2018, pp 130–131 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By Rowe P, Rogers D, Warren M

Pressure cyanidation of the minus 10 micron slimes fraction of the Fimiston flotation concentrates for the recovery of gold values has been evaluated as an alternative processing route to the roasting and atmospheric cyanide leaching of the calcine. Laboratory and pilot trials have demonstrated that gold extractions of greater than 94 per cent can be achieved at cyanide consumptions of 12-24 kg/t and oxygen consumptions of 0.1-0.3 Nm3/t with total pressures of 1000-2000 kPa. Economic and operational assessment of several reactor configurations suggests autoclaves may be preferred over pipe reactors at treatment rates of 10 t concentrate/h.

Jan 1, 1996

By S C. Bhowmik, R Gupta

This paper presents the ventilation problem faced by Jaduguda uranium mine, operated up to a depth of 905 m. The first two stages of the mine workings are up to 555 m, which are nearly exhausted. The third stage of the mine is from 555 m to 905 m and presently most of the stopping and development activities of the mine are carried out in the third stage. The total available intake quantity in the third stage was only 21 m3/s. As a result, the mine was facing a radiation hazard. The different instruments and the methods used for monitoring of radiation levels are also presented in the paper. It was observed that the average individual effective dose (external + internal) of radiation workers in Jaduguda mine increased from 6.93 mSv/y in 1995 to 9.5 mSv/y in 2001 and during this period the average individual effective dose of mine workers of the world was less than 5 mSv/y. Keeping this problem in view, a detailed ventilation investigation has been carried out in this mine. Initially the requirements of intake air quantity have been assessed by carrying out field investigation in different stopes and it was found that the third stage workings require nearly 100 m3/s. A detailed ventilation survey has been carried out in the total ventilation network and a basic ventilation model of the mine has been prepared. Different alternative schemes for effectively ventilating the third stage workings of the mine were simulated and a set of recommendations were made for implementation. The recommendations were partially implemented in 2002. As a result the total intake quantity to third stage workings increased to nearly 70 m3/s and the average individual effective dose (internal + external) of mine workers came down from 9.5 mSv/y in 2001 to 6.65 mSv/y and 6.60 mSv/y in 2002 and 2003 respectively. The implementation of remaining recommendations is in progress. Finally, a mathematical model has been formulated from the first principle for predicting air quantity requirements in cut and fill stopes in uranium mines and this model is being validated for further use.

Jan 1, 2005