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By J Green, R Bartlett, A Goldstone, D Ferguson

Solid Energy New Zealand is developing an extension of its Rotowaro open cast coal mine near Huntly. This large 8 year, 11 million tonne opencast coal mine, referred to as the Awaroa Project, is fundamental to Solid Energy's medium term business strategy and meets its open pit coal resource needs while further resources are developed for the long term. Equally importantly the project is also fundamental to meeting New Zealand's energy requirements in the face of growing demands, a dwindling gas resource, and dry winters creating hydropower shortages. This project with its national significance in the current energy climate, its significance to Solid Energy as a business and its significant size has been consented against a backdrop of criticism of the Resource Management Act and the introduction of the 2003 amendment to the Act. As is common practice for this type of project Solid Energy conducted a significant technical programme in order to complete a comprehensive assessment of environmental effects. Solid Energy also has an active programme of community and interested party consultation and this programme formed the basis for project based consultation with local residents, regulatory bodies and iwi. As a result of the approach taken the environmental effects of the project were shown to be no more than minor and Environment Waikato considered that the project should be processed under the limited notification provisions of the RMA amendment. The project was processed under RMA quickly and efficiently and consents were granted within 6 months of lodgement. The RMA and its 2003 amendment provided a good framework for dealing with this project and did not impede the process of development of this important energy resource.

Jan 1, 2004

The advent and easy availability of fast and powerful digital computers has marked a transition from one era to another in the field of process control in many industries. Mineral processing is no exception. Aims, practices and problems associated with process control of mineral beneficiation plants in the 'old days' are compared with those available at present. Although basic processes remain generally the same, there have been simultaneous social and economic developments, which directly relate to the development and present value of process control. Lower head grades are now treated, plant capacities have increased, and a large proportion of future capital in the mineral industry will be associated with large capacity plant, treating still lower grades. Environmental considerations have pressurised moves to better control in some areas. With these changes, economic operating incentives have changed, and process control has, in many plants, become more critical. Finally, while computer technology has developed recently at a very rapid rate, developments in the fields of instrumentation, basic on-line measurement and sampling have in general lagged behind, limiting the progress possible in process control. Hence, the benefits of computer control vary depending on

Jan 1, 1977

By Keys NJ

The so-called COMAT process provides a method for leaching low grade sulphide mattes in an acidic ferric sulphate medium in such a way that non ferrous base metals such as Ni,Cu and Co are substantially all dissolved; the concentration of residual acid and dissolved iron remaining in the leaching solution is low, and a large portion of the sulphide sulphur is converted to elemental sulphur. Thus the quantity of neutralising agents required to remove residual acid and dissolved iron from the leach solution prior to subsequent recovery of the dissolved base metals is greatly reduced. The leach residue and iron precip- itate report in a readily filterable form. In this paper results obtained on a pilot plant scale are presented for the leaching of a typical low grade matte in the manner describ- ed above; for the solvent extraction and elec- trowinning of copper, and for the removal of residual acid, copper and iron from the copper solvent extraction raffinate. Processes tested on a laboratory scale for the further recovery of cobalt and nickel by solvent extraction and electrowinning, and for the recovery of sulphuric acid and ammonium hydr- oxide from the dissolved ammonium sulphate salt contained in the final plant effluent, are also briefly described.

Jan 1, 1986

Change is inevitable but learning from change is an option. Willingness to learn is one of the first lessons that a leader must learn. Get comfortable and get left behind. I propose to outline the main social changes which are taking place and their impact on the Minerals Industry. Also the changing way we do business and what are the skills needed to manage that change and diversity. How are Associations and Institutes responding to this ever changing environment? More specifically, what is my Vision for the Institute to assist professionals to achieve greater and continuing professional excellence in their chosen professions?

Jan 1, 2000

By Weller KR

Completely dry or completely wet materials are comparatively easy to screen, but materials with moisture contents between these two extremes can present varying degrees of difficulty. The presence of moisture can impair the performance of a dry screening plant in a number of ways: ò agglomeration of fine undersize particles onto larger oversize particles, resulting in the fine particles being misplaced to the oversize; ò increasing attractive forces between particles that hinder stratification and particle presentation to the screen; and ò blinding of the screen apertures caused by fine moist particles clinging to the screen which reduces the effective aperture size and the open area of the screen. Test work on full-scale screens has shown that the agglomeration of fine particles onto larger particles only occurs once the equilibrium moisture content of the ore is exceeded, and that the quantity of adhering fines present is proportional to the surface area of the larger particles. An -adhering fines screen model has been developed from this work, and by using relationships derived between the model parameters and feed moisture content, the effect of changes in feed moisture on both product quality and operation of iron ore dry screening plants is predicted.

Jan 1, 1993

By A Scott

Long before a modern mine commences operations it has already become a wealth of information. After start up, it can generate enormous quantities of data û especially with semi-automated data acquisition by instrumented mine equipment. However, much of this data is of limited use for evaluation of (potential) performance unless it links in some way to the site business model. An underlying reason for this waste of data is that the different cultures, financial, technical, community, environmental, etc not only have many areas of interest but also have very different conceptual models by which they evaluate performance. It is too ambitious to attempt to bring all of these cultures together û in a single step. However, the success of the Mine to MillTM project has demonstrated that substantial operational value can be added by using a more integrated approach to comminution. The next logical step is to integrate measurement and then to track performance from orebody model to saleable product and waste disposal. From resource to product also represents a path from very sparse, highly variable data to much more detailed measurement and more representative sampling. However, in both cases the data collected is strongly focused on the technical requirements û not on the business model. This paper considers how to define at least some of the key decision points in terms of some case studies. Performance data from many areas might be used to derive simple models which can then be used for forecasting and optimisation of planning.

Jan 1, 2002

In-pit crushing systems have been known in the mining industry for many decades. The question whether in-pit crushing is a viable option has often been asked. More than 200 mobile and semi mobile crushing systems have been installed worldwide at various locations and applications. Economic pressures have forced mine operators to reconsider the use of a conventional truck-shovel operation and have contributed enormously to the development of in-pit crushing and conveying systems. The in-pit crushing concepts have varying mobility capabilities. These range from fixed, stationary crushing plants to semi-mobile and fully mobile crushing plants. All these systems are operated in connection with a conveying system. In general in-pit crushing systems have technical and economical cost advantages over truck-shovel operation, particularly as mine capacities increase and mines become deeper. The integration of an in-pit crushing system represents a significant up-front capital investment and the mine is only able to depreciate the capital investment over a sufficient mine life including plant capacity to realise the benefit of the much lower operating cost.

Jan 1, 2003

By C MacDonald

There are many technologies available today in terms of fire and life safety in road tunnels. So many in fact that it is becoming more and more difficult for clients and contractors alike to determine what they want and what they need. From a clientÆs perspective, fire and life safety is about protection to its infrastructure and to the public at large. Conversely, the contractor is looking to meet its æfit for purposeÆ or ædeem to complyÆ requirements in the most economic and practicable way. Practices regarding fire and life safety in road tunnels have undergone a degree of transformation during the last decade or more throughout the world. This transformation has largely been driven by a series of catastrophic accidents such as the major fires in Europe including the Mont Blanc Tunnel, Tauern Tunnel, Saint-Gothard Tunnel, and now most recently in the CityLink Tunnels in Melbourne. International guidelines produced by organisations such as the Permanent International Association of Road Congresses (PIARC), the European Union, the International Tunnelling Association (ITA) and the US National Fire Protection Authority (NFPA) now provide clients, owners and designers with the tools required to define and specify the required fire and life safety systems in road tunnels. The majority of these tools are based on risk assessment and risk management. Recent road tunnel projects within Australia, however, have not referred solely to such guidelines. Clients have opted to prescribe different or additional fire and life safety requirements within the projectÆs technical specification documentation (project requirements), leaving designers and contractors with little room to implement alternatives or substitutions. Further, these project requirements are largely dictated by practice established on previous road tunnel projects within Australia. This paper looks at the current international guidelines and practices and undertakes a comparison with the EastLink tunnels in Melbourne and other road tunnels within Australia and makes assessment on whether Australian methods are the most appropriate for clients and contractors alike. Focus is directed to the key elements of fire and life safety such as:traffic envelope, barrier arrangements and emergency walkway provisions;deluge systems;drainage systems;fire rating requirements;tunnel ventilation systems;cross passage provisions;fire safety assessment;critical intelligence systems including help phones, CCTV, incident detection, tunnel signage, etc; andexternal tunnel control systems.

Jan 1, 2008

The aspect ratio (mill diameter/mill length) of autogenous and semi autogenous mills varies widely and can be as high as three or as low as 0.5. The literature on the subject of what effect aspect ratio has on grinding mill performance or energy efficiency is almost non-existent. However, at the design stage of many grinding circuits the subject is often vigorously debated amongst metallurgists. In this paper the performance characteristics of mills with different aspect ratios are examined to determine whether process performance characteristics are a function of aspect ratio and whether high aspect ratio mills are any more or less energy efficient than low aspect ratio units. Data from both pilot and full-scale mills are used for this purpose in open and closed circuit configurations.

Jan 1, 2007

By N S. Rauert

The Barrick Gold Granny Smith underground operation located at the Wallaby deposit is currently in a transition period from a near surface operation in ramp up mode to a fully operational deep mining operation with annual production exceeding 1 Mt/a. A key element in this process has been the project execution of the Wallaby Deeps project from initial scoping study in 2007 to the major production component of the Wallaby operation by 2013.The Wallaby Deeps project serves as an example of how an ongoing detailed study program can be integrated into a day to day mining operation assessing risk and mining application in a perceived challenging narrow vein geotechnical environment prior to mining. A detailed study phase to feasibility level is carried out prior to the mining each zone of Wallaby with mining approval only granted on study completion with full justification.A central element in this process is an optimisation study that utilising the Mineable Shape Optimiser (MSO) and Schedule Optimisation Tool (SOT) software tools developed by AMIRA Ltd PRIMO research project is used to carry out an NPV value based option study. This optimisation process being then tempered to reality by a predefined practicality assessment process utilising extensive peer review by operational and study team members as well as industry experts.Other challenges facing the Wallaby Deeps project include the requirement to maintain the ramp up production profile to full production by 2012 without disruption but with pressures of an ongoing geological resource to reserve conversion program essential for the study process and mining approvals and also development rate achievement.To date these challenges are being met with integrated planning and the value of the study program itself. Production in 2012 year to date is well on the way to annual production rate exceeding 1 Mt/a.CITATION:Rauert, N S, 2012. Wallaby Deeps - from the optimal opportunity to reality, in Proceedings Narrow Vein Mining 2012 , pp 207-214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By M L. Habner, S D. Munro

In a gold CIP/CIL circuit, adding new circuit water to a final tails thickener and then directing the thickener overflow to the head of the circuit significantly reduces the cyanide concentration at the TSF discharge spigot. The new water is used to dilute the final tails. The dilution and recycle of the tails in this manner may have the added benefit of reducing reagent consumption, in some cases to the point where the reagent savings justify the expenditure and Cyanide Code compliance is achieved at no extra cost. Potential circuit configurations and water recycles can be modelled by splicing a flowsheeting and thermodynamics package, such that changes to the composition of the water can be reduced to chemical speciation with a Gibbs free energy minimisation enabling a complete understanding of the circuit water chemistry.

Jan 1, 2007

It is often assumed that geotechnical investigations or studies for open pit mines are confined to providing a slope design. However in an operating mine, the design is only one component of a mine geotechnical program. Reviews of slope designs are ongoing throughout the mine life. The concept of Pit Slope Management has been formulated because the design only entails one component of a total program that contributes to a safe, efficient mining operation. Risk is a normal part of mining. Effective management allows the risk to be contained or controlled. If the slopes are not effectively managed there will be increased risk for the operation. Experience has shown that utilisation of Pit Slope Management coupled with a broad base of experience to define the key controls on stability, provides a pro-active, objective approach. The reasoning is deductive and relies on the behaviour of the ærocksÆ. Once the key aspects are defined, studies are well focused, implemented as required and the risks can be effectively managed. When the key controls on stability are poorly understood reasoning is typically more ægut feelÆ. Under such circumstances studies, if carried out, may meet short-term objectives but often ignore the long-term objectives. Hence the risk to the project is greatly increased. This paper presents several case studies highlighting the above aspects and present elements of the Pit Slope Management Program approach which have been successfully utilised by the author to manage risk in mining projects.

Jan 1, 2003

Atlas Copco Construction and Mining Australia identified a number of issues in regard to the skill levels, labour turnover and productivity of our service technicians. In 1994 we were experiencing a labour turnover rate of 42 per cent per annum amongst our technicians. Exit interviews were held with each individual and one of the major areas of dissatisfaction was the degree of product training provided on our equipment, compared to what is required to be competent across the range of our products. These tradespersons were prepared to accept the reduced remuneration that an OEM offers, for the benefit of comprehensive, professional training that, in theory, could be provided. The truth is that we were achieving approximately 40 per cent of our target for training hours because of the demands of field service, pre-deliveries, etc. So, the summary was the same as the industry was experiencing at that time because of skilled labour shortages, production demands, etc people were employed and thrown in at the deep end. A recipe for failure that will be successful every time.

Jan 1, 1998

Fission track thermochronology is a well established method for reconstructing the thermal histories of rocks with particularly important applications in tectonic studies, detecting low-grade thermal events, sedimentary basin analysis and resource exploration. These applications take advantage of the limited stability of fission tracks, especially in apatite, when exposed to the temperatures found in the upper 3-4 km of the crust. Apparent fission track ages in apatites can define an invisible 'stratigraphy' in otherwise homogeneous rock masses that can give valuable information on thermal, tectonic and erosional events. Quantitative modelling of the thermal annealing of tracks in apatite shows that distinctive profiles of apparent fission track age can be related to a number of simple thermal history styles. The main types of profile observed tend to be either an essentially linear decrease of apparent age with increasing depth, which relates to continuous uplift and denudation, or a concave-upwards profile produced by partial annealing in environments of tectonic stability or burial. More complex thermal histories produce compound profiles which are essentially just combinations of these two elements. Track length information allows the apparent age profiles to be interpreted in much greater detail. Examples of the major profile types have now been identified in various geological environments and can be analysed to give information about, for example, uplift and denudation rates, the timing of uplift or low-grade thermal events and maximum palaeotemperatures experienced during burial.

Jan 1, 1990

Zinc enters into solution on aeration of sphalerite in deionised water. It has been observed that less zinc dissolves in a copper vessel than when the same operation is carried out in a glass vessel of similar shape and size.

Jan 1, 1980

By Armstrong ME

The gas bubble energy generated by an explosive plays a major part. in the fragmentation, muckpile movement and damage produced. Previously, the interaction between gas pressure and the rock has been interpreted from a theoretical basis or a qualitative study of breakage mechanisms. A method to measure the fluctuations in gas pressure in rock adjacent to the blast has been developed. This peak pressure will vary with structure, as well as with distance and explosive type. The technique is simple to apply and can be used to observe the flow rate of gas at. varying distances. The apparent velocity of penetration is an indication of whether gas has travelled through pre-existing or blast induced cracks. The technique provides a ?n:eans of determining the suitability of an explosive for a given rock type, depending on the amount of displacement desired. The technique has application in optimir.irig throw blasting and predicting and controlling damage, particularly in highly structured rock masses.

Jan 1, 1986

By P S. Datta, V N. Misra

Higher bed height up to 680 mm, including 30 mm hearth layer of sized return sinter and high suction below the grate bars up to 1400 mm WG have resulted in increasing the productivity to a level of 33 t/m2/day and reduced coke rate to a level of 46 kg/tonne sinter. The ferro-wastes like blue dust, flue dust, mill scale, collection from dust catcher and gas cleaning plant, etc have been successfully added in charge mix to produce quality sinters. In this paper, brief description of the work done at Regional Research Laboratory (CSIR) in last few years and two case studies are discussed including the successful development of pan sintering units.

Jan 1, 2002

By D K. Miller, L W. Armstrong

In April 2006, Orica Quarry Services undertook an investigation to determine the likely vibration and frequency response of three water storage tanks to quarry blasting, immediately adjacent to the tanks. Of the three tanks that were studied, two are relatively tall with a æwineglassÆ shape; one is constructed of steel (4 ML storage capacity) while the other is constructed of concrete (2 ML storage capacity). The third is a ground-embedded concrete tank that is relatively squat and broad in shape (38 ML storage capacity). A vibration limit of 25 mm/s and an acceleration limit of 0.16 g were imposed on the tanks. However, this report shows that this acceleration limit, whilst having relevance to low frequency earthquake motions, is quite inappropriate for the high frequency blast vibrations that are typical in a quarry blasting environment. The investigation involved firing 11 single blastholes of known charge weights and distances from the tanks, and measuring the tank vibration response using blast monitors placed on and around each tank. Analysis of the data collected from the cement tanks showed resonant responses over a broad range of frequencies, with dominant and lesser responses in vertical and lateral motion recorded at 9.8 Hz, 12 Hz, 16.8 Hz, 17 Hz, 31.3 Hz and 38.1 Hz. Unfortunately, most of the data collected on the steel tank was corrupted by noise due to electrical sources and/or mechanical sources such as the water agitator inside the tank. Advanced Monte Carlo vibration models were then constructed using the single blasthole information. Knowing the resonant frequencies enabled the modelling of electronic delay sequences for the reduction of resonant vibrations. Ultimately programmable and accurate electronic delay detonators were deemed essential to allow blasting in relatively close proximity to the tanks while avoiding resonant frequencies. Three blast designs were modelled, ranging in maximum instantaneous charge (MIC) from 4 kg to 22 kg, and 60 holes to 160 holes. The modelling showed that two of the designs (using small charge weights) could be used no closer than 71 m from the storage tanks. This is based on a 90 per cent confidence level of achieving vibration levels within the 0.16 g acceleration limit, even though the velocity levels predicted to be generated at this distance were significantly less than the 25 mm/s limit. The third design incorporated larger charge weights and could be used for blasting at distances no closer than 220 m from the tanks. The present work, conducted in an operating quarry, demonstrates the usefulness of Monte Carlo waveform superposition techniques for the control and reduction of ground vibration (either velocity or acceleration) under restrictive environmental constraints. However, a discussion is also presented to demonstrate that it is somewhat restrictive to impose an acceleration limit based on the motion produced by low frequency earthquakes rather than the motion produced by high frequency blast vibrations.

Jan 1, 2007

Mineral Processing Education in China

Sep 13, 2010

The Hishikari gold deposit, discovered by the Metal Mining Agency of Japan, has become a giant class epithermal gold deposit with the highest grade of gold yet recorded in the world through detailed exploration and development by the Sumitomo Metal Mining Co Ltd. The exploration strategy involved a regional approach combining geological and gravity surveys over a 900 km2 area which had historically produced over 120 t of gold. These surveys were carried out to grasp the common geologic features of epithermal gold deposits in the survey area. A genetic model for epithermal gold deposits in the area under regional survey was also considered based on detailed research of the Kushikino epithermal gold deposit which was in operation at that time. This model was applied to the targeted areas, and important relationships between mineralisation, host lithology, intensive propylitic alteration and gravity highs became apparent. The Hishikari block was selected in this way and bonanza gold was discovered during drilling. Since the development of the Hishikari mine, information useful for further exploration for the same type of deposit has been accumulated.

Jan 1, 1995