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By Amelunxen R, Finch JA

Flotation columns represent an important addition to flotation practice. Columns have largely replaced. conventional machines in molybdenum cleaning in Canada. Columns have been successfully tested on bulk copper/molybdenum cleaning at Gibraltar Mines Ltd. A rougher cleaner/scavenger cleanercombination was shown to be capable of giving higher grades and recoveries compared with three stages of conventional cleaning. A control strategy for the columns has been developed. An interaction between gas hgldup and wash water rate has been exploited to control performance.

Jan 1, 1985

Placer Dome Asia Pacific operates eight mines in the region and has two closed operations that are either under rehabilitation or at the latter stage of care, monitoring and maintenance. All operating mines are scheduled to close within the next ten years based on current proven reserves. Mine closure planning and associated risk assessments are integrated into both strategic planning and day-to-day operations within the Placer Dome group. Mine closure is all about predicting the potential risks and Placer DomeÆs knowledge has improved following the planned closure at Kidston Gold mine in North Queensland. Planning for closure commenced in earnest in 1994, and focused on identifying the issues and associated potential risk to the environment, and ensuring that the most suitable control measures were implemented leading up to and following closure in July 2001. At all times during the process of planning, implementation, safety contractor management and post closure, the identification of risk and potential threats to the business have been identified and managed. Post closure risk assessment of rehabilitation strategies potential to fail has been completed in conjunction with URS and opportunities to manage these potential failures in perpetuity will be discussed along with lease surrender. Misima Mines is currently processing low-grade ore and plans to close in 2004. Planning for closure has been ongoing for several years with a focus on the social aspects and the impact of the mine closing on a remote island community. Misima Mines has assessed the risk profiles using a community closure focus group, to identify both the biophysical and social aspects for closure.

Jan 1, 2003

By F Pothitos, S Hewson

The geological and geotechnical conditions at the Cadia Hill Open Pit are very complex. This complexity coupled with high mining rates has required significant technical input into the design and optimisations of the pit slopes, accesses, cutbacks and scheduling. A multi-discipline team of NML engineers, geologists and external consultants has been conducting comprehensive geological and geotechnical programs in order to achieve an optimum design of the pit slopes. Extensive data collection, analysis and interpretation has led to the formation of working geotechnical models of large structures, rock masses, and back-analysed slope performance charts. The current Cadia Pit Optimisation Project focuses on the risk-and-return principle for pit design and on the integration of geotechnical, hydrogeological, mining engineering and scheduling. The risk management for pit design has also been incorporated into the short term and long-term operation of the pit mining to ensure safety and production.

Jan 1, 2003

The cost-effectiveness of blasts involving radiating blastholes is cur- rently restricted in the following ways. (a) Significant percentages of potential explosion energy are not being liberated; the collar sections of some charges are being dislocated and/or desensitised by the detonations of adjacent earlier-firing charges. (b) If the minimum charge spacing is too small, detonation of an early- firing charge can initiate an adjacent charge sympathetically, thereby eliminating the benefit of any intended inter-charge delay. (c) The overall distribution of energy is poor. Appreciably better fragmentation would be achieved if current drill- ing patterns were to be replaced by staggered fans/rings having a toe spac- ing : burden ratio of about 4 : 1. This wide-spaced pattern would enable a higher percentage of the potential energy to be released, would reduce the incidence of sympathetic detonation and would provide a superior overall distribution of this liberated energy. If improved fragmentation is not required, the proposed fan/ring design should allow a significant expansion of the blasthole pattern with consequential cost savings in drill- ing, explosives and initiation.

Jan 1, 1988

Australis Mining N.L. operates a continuous mode carbon-in-pulp (CIP) gold plant, processing sand and slime tailings from previous gold mining operations in the Norseman area. Plant design is that of conventional countercurrent contact between pregnant pulp and activated carbon. Gold desorption is achieved by the Zadra process using near boiling tempera- tures and atmospheric pressure. Process water is drawn from nearby Lake Cowan (saline). The plant operates at, or above, design specification of 400 dry tonnes per day. This paper describes the plant design and operating processes utilised in optimising throughput and gold recovery. TNTDnPTTnmTnM Favourable world gold prices and substantial reserves of sand and slime tailings prompted Australis Mining N.L. to construct a gold extraction plant during 1981. The projected plant throughput was set so as to complete treatment of available tailings over a three year period. Metal- lurgical tests indicated that, with a regrind facility satisfactory gold recovery could be achieved using a countercurrent CIP process. Reflecting the entry of Australis Mining N.L. into its first large scale treatment operation, the plant design emphasised simplicity but effectiveness of Operation.

Jan 1, 1982

By Carrucan M. J

Costain Resources Limited operates two open cut coal mines in the Hunter Valley coalfields of New South Wales, Ravensworth Mine and Warkworth Mine. The location of the Ravensworth operation is shown in Figure 1. In the case of the Ravensworth Mine, Costain Australia is essentially a contract miner and is contracted to supply coal to Pacific Power (previously The Electricity Commission of New South Wales), on contracts won through a tender system. Due to the existing infrastructure and the lease area that associated with the contract, the mining strips at Ravensworth South have a maximum strike length of 1500 metres. This paper deals with the methods of scheduling used to overcome the challenge of mining the short strike length, multi-seam deposit at Ravensworth South.

Jan 1, 1992

Production of refined zinc (99.95 per cent) at the minesite without increasing greenhouse gas emissions is considered. As an example, exploitation of the full reserve of the McArthur River orebody is proposed, using the existing concentrator, whilst introducing radically innovative smelting technology. Bulk flotation of all the sulphide minerals is followed by smelting in a melt circulation reactor with tonnage oxygen. By smelting the high-energy pyritic concentrate and reacting the evolved sulphur dioxide with near-mine dolomite, a large amount of electricity can be generated. This is enough to supply all the requirements for the smelter itself, an air separation plant and a facility for compressing and liquefying carbon dioxide. Carbon dioxide is disposed of off-shore for enhanced oil recovery or by other means. The reacted dolomite fixes sulphur as an inert and environmentally acceptable solid residue. Treatment by these means leads to virtually zero gas emission smelting. The paper concludes with a vision for the future in which expansion of zinc smelting capacity is seen to be definitely needed.

Jan 1, 1998

By R Fleming, G Jones

An ocean outfall is currently under construction in Christchurch, New Zealand to transfer treated wastewater from the existing treatment ponds at the city wastewater treatment plant to diffusers located 3 km offshore. The New Zealand $85 million project comprises a new pump station and 5 km of 1800 mm diameter pipeline with a design capacity of 6.0 cumecs. The pipeline comprises 2.3 km of concrete pipe installed by microtunnelling and 2.7 km of polyethene marine pipe installed by dredge and lay. This paper describes the consent process, key environmental and community constraints, the tender process, risk provisions included in the contract, the type of contract, partnering provisions, geotechnical design issues and the pipejacking construction activities and issues.

Jan 1, 2008

By G Harbort, C Sola

The rapid development of geometallurgy in the mining industry has occurred in relatively recent times. Its importance as an independent discipline in the mineral processing world has been emphasised and recognised. To a large degree, this is the result of a growing understanding of the ore type being processed and their application to provide better metallurgical responses in different mineral processing techniques. The development has matured from early progress through to geological knowledge and into the realm of the metallurgist and mining engineer. Working together, they have developed a powerful framework that will interpret a body of mineralisation into measurable properties.The integration of geometallurgy and operations has become of increasingly important due to improvement in understanding of an orebody as a natural system formed by a number of processes and with a definite fabric of mineralisation within different geological domain. These have to be taken into account when creating techniques that will enable operations to extract the valuable components from a distinct type of ore. Incorporation of such knowledge at an early stage of development, such as the feasibility stage significantly reduces the project risk.This paper is written from the unique perspective of a process engineer embedded within a geological team. It discusses issues such cross discipline communications and misconceptions and details the numerous tricks, traps and treasures of geometallurgy encountered during defining of the Seminco and Taysan resources.CITATION:Sola, C and Harbort, G, 2012. Geometallurgy - Tricks, traps and treasures, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 187-196 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

THIS paper is not intended to be more than a mere outline of the economic geology of Tasmania. It is desired to present in a condensed form the present state of our knowledge in regard to the distribution of the ore, coal, and oil-shale deposits of Tasmania in time and space.Tasmania is exceptionally well endowed with mineral wealth, particularly in the north-western and western districts. In the enthusiasm resulting from the first discoveries of mineral deposits at a great number of localities in those districts, it became a generally accepted belief that the whole of that portion of Tasmania constituted a continuous metalliferous province. As geological research in these, areas has progressed, however, it has become increasingly clear that ore-deposition has been confined on an economic scale to definite well-defined areas or belts which have a genetic relationship to certain tectonic and petrologic phases of the general geology. These areas or belts have recently been defined by the writer, and...

Jan 1, 1923

At Yucca Mountain, USA, a tunnel is being built according to nuclear quality standards. It has proved possible to meet very high quality demands while at the same time achieving high advance rates. To be able to do this, routines on how to record and store quality related information have been established. This has meant that a new philosophy has entered the tunnelling industry. Especially for nuclear waste projects, of which Yucca Mountain is one of the first ones to be built, the experiences made and the quality assurance program established will be of great importance for future projects. The paper gives examples of what the Nuclear Quality Assurance system has meant in practice for the tunnelling at Yucca Mountain. And, it also explains why a non-grouted bolt, Super Swellex-, was chosen for long-term reinforcement in the tunnels which might host nuclear waste for thousands of years.

Jan 1, 1999

By B Brattli

The dispersion pattern of heavy metals in soil and water is a consequence of complex geophysical and geochemical processes. Metal release from mining sites and subsequent migration occur primarily through acid mine drainage and erosion of waste and tailings dumps. Water plays a significant role in heavy metal mobilisation. Whilst it acts as a storage buffer for the pollutants, it is also the medium in which most of the reactions take place, and is undoubtedly the most significant transport vector in the pollution process. The intrinsic properties of the acidic drainage such as chemical composition, speciation of key mineral components, redox potential and pH are master variables controlling metal release, transport, deposition, reactivity and availability to biota. The mobility of heavy metals is strongly increased by acidification from acid mine drainage, and the discharge of these metals into the receiving waters results in numerous physical, chemical and biological responses in which the environment can affect the metal and vice versa. The result is an overwhelming number of association/dissociation, substitution, adsorption/desorption reactions, giving rise to a complex migration pattern. The attempt to understand and describe the dispersion pattern of heavy metals is complicated by the nature and level of interaction between the geochemical and hydrodynamic processes that generate and control the movement of the pollutants in the geosphere. Transport models which can be used to predict the behaviour of metal pollutants in a natural environment are still in the initial phases of development and their application to real life situations is limited. The Biochemical Cycle adds another dimension to the mobility of heavy metals. Metals form an important component of the food chain for man and plants. Biological uptake of metals from the bedrock and soil by organisms can result in migration paths very difficult to follow. Biodegradation or assimilation is just a tip of the iceberg.

Jan 1, 2003

By D R. Swinbourne, Y H. Yang

Calcium ferrite slag has gained prominence in the copper smelting industry over the last decade due to the emergence of continuous converting as an established technology. As smelters move towards processing which is higher in intensity, more efficient and more environmentally acceptable, its use is likely to increase because it has technical advantages over conventional iron silicate slag, which include a higher magnetite-holding capacity, lower copper losses to slag and a lower viscosity. Calcium ferrite is currently the converting slag of choice in the Mitsubishi process at operations in Japan, South Korea, Indonesia, Canada and Australia, and in the Kennecott/Outokumpu flash converting process in USA. However, users of this slag have experienced problems in containment due to its highly corrosive nature and low viscosity. As use of this slag becomes more widespread the containment problem will assume greater importance. Consequently, work has recently been carried out to establish the mechanism of refractory attack and devise means to retard it. This work will be critically reviewed in this paper.

Jan 1, 2000

By G Steward

Gravity Leaching of high-grade gravity gold concentrates, such as Knelson Concentrates, with the ACACIA Reactor represents a new generation of concentrate treatment methods. The ACACIA Reactor is a complete packaged plant for the maximising of gold recoveries from gravity gold concentrates. This paper will introduce the process technology and provide process results from the Porgera ACACIA Reactor installation. The advantages of the ACACIA Reactor are many, and justification for installation has been varied. The typical advantages of the process include: increased recovery of gold from the Knelson Concentrate; no return of high-grade table tails, often grading several thousand g/t, into the mill circuit; reduction in tails grades of slow leaching gold; reduction in the requirement for operating staff by the removal of the manual tabling process and replacing with a fully automated treatment system; improved security by removing the tabling step where operating staff come into direct contact with visible gold; improved health and safety, by the removal of the treatment steps for the table concentrate, which often include operators handling corrosive chemicals and the production of sulphur and arsenic compound fumes; and improved metallurgical accounting, by allowing daily head grade calculations. The ACACIA Reactor was developed by Anglogold for Union ReefÆs Gold Plant and has been in production for over two years, and has proven to be a low cost, high recovery, mechanically reliable method for the processing of gold concentrates. Such has been the success of the plant, there are now four full installations of the processing plant, including Anglogold Union ReefÆs, Anglogold Sunrise Dam, PACMIN Carosue Dam and Porgera Joint Venture.

Jan 1, 2002

Mining companies around the world are seeking methods to coordinate operations between the mine and the concentrator to achieve an overall improvement in enterprise performance. In several instances very significant increases in productivity (more than 20 per cent) and profitability (more than $US 10M per annum) have resulted from such efforts. The key to realising these large benefits has for the most part arisen from improved communication between mining operations and plant operations personnel and the judicious use of new tools to evaluate alternatives for improvement and to minimise the risk of implementation. This paper presents a systematic approach to mine-to-mill optimisation . The importance of systemic thinking and systems optimisation methodologies is emphasised. New tools for evaluating operational performance are discussed. Recently reported benefits are summarised. Finally current research is discussed and projections for the future are given.

Jan 1, 2000

This paper gives a first-hand account of what a graduate mining engineer can learn by visiting Atlas Copco in Sweden and gives reasons why all mining engineering students should apply for this excellent scholarship. It will also (attempt to) refute the authorÆs mine managerÆs claim that the trip was a huge junket.

Jan 1, 2006

By Muir D

A review of the various methods of degrad- ing cyanide either from gold processing liquors or electroplating baths is presented with some discussion on their relative merits or problems. Whilst alkaline chlorination is common practice in many U.S. and Canadian plants it poses particular problems for certain plants. Alter- native methods include electrolysis, hydrolysis and air oxidation with activated carbon as catalyst which are also integral steps in the carbon-in-pulp process. A basic study of the degradation of cyanide ion has been carried out therefore to determine the effect of temperature, oxygen and carbon. It is shown that carbon is an excellent catalyst for degradation by air and likely to lead to higher losses of cyanide in a C.I.L. circuit. Degradation by hydrolysis is important at high temperatures and high pH such as employed in the Pressure Zadra or Anglo elution processes. Carbon catalysed degradation of cyanide by oxygen in effluent streams may be an environmentally acceptable alternative to conventional chlorine degradation.

Jan 1, 1987

A simple method of designing effective fill drainage systems for slurry backfill is presented. By using the proposed method, it is easy to calculate and predict the expected fill drainage rates or to provide additional drainage systems to accelerate the fill drainage. The fundamentals of hydraulic fill and an efficient method to determine its permeability is also explained. The safety in hydraulic filling and bulkhead stability depends totally on achieving effective drainage regime for the fill. This paper provides the basis for creating such efficient drainage regimes. The recent fatal fill bulkhead failures in Australia were the result of poor drainage from the respective fill masses, and therefore it is more important to provide suitable drainage arrangements to continue using hydraulic fill to the benefit of the mining industry. At present there is no procedure available to mine operators to estimate the expected bulkhead pressures to design a satisfactory bulkhead. Some mines are constructing bulkheads after their initial investigations carried out years ago. Other mines have simply borrowed the ideas from the pioneer mines and using in their areas. It is high time that we develop a rational approach to estimate the expected bulkhead pressures for the design of bulkheads. We need a simple model that could be understood and used by the mine operators on a day-to-day basis. This paper also presents a model to predict the bulkhead pressures for designing safe bulkheads.

Jan 1, 2002

By L Soares, W T. Hennies, F Fujimura

A methodology of environmental performance evaluation in mining developments is proposed, as well as guidelines and procedures for obtaining information to improve their environmental performance. Environmental performance is the results of the mining activities and their relation to environmental issues. If this evaluation is carried out on an on-going basis, it is possible to anticipate or to identify the formation and development of an environmental impact in its early stages. Evidence or trends identified by environmental evaluation provide valuable information to prevent further damage. The proposed methodology is based on the significant environmental aspects of a selected monitored job site by environmental indicators which are then compared with previously defined environmental criteria and targets or goals. The methodology procedures also take into account the environmental accounting of the investments and expenditures.

Jan 1, 2003

By H Kundapen, B Bolton, S Miller

The Ok Tedi porphyry copper and gold mine is an open-pit operation located within the Star Mountains in the Western Province of Papua New Guinea and is situated near the headwaters of the Ok Tedi-Fly River system. The climate is equatorial sub-alpine with rainfall ranging from five to ten metres per year. Mining commenced in 1984 and to-date approximately 500 Mt of waste rock has been produced. A failing waste rock dump system operates whereby the dumps are eroded by tributary creeks of the Ok Tedi. It is estimated that approximately 250 Mt of waste is retained within the upper reaches of the river system. The waste rock comprises both potentially acid forming rock and limestone and to-date the overall waste has been acid consuming. However, the long-term mine plan identifies declining limestone production and hence an increasing risk of acid generation over the remaining years of the operation. A program was initiated to determine the net acid producing potential (NAPP) required (ie target NAPP) to minimise the risk of acid generation within the waste rock dumps. The results from this program provide guidelines for an operational target NAPP strategy to provide sufficient acid buffering across all size fractions in the waste rock dump for long-term ARD control. Implementation of this plan requires additional limestone to be mined and co-disposed with ROM waste rock.

Jan 1, 2003