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Flotation Performance Improvement by Air Recovery Optimisation on Roughers and Scavengers

Sep 13, 2010

By M C. Evans

"Mine decommissioning is the final phase in a mining project. Planning for decommissioning must commence for a proposed mine even before the government approves it. Queensland mining approvals require proponents to commit to completion (or closure) criteria defining successful rehabilitation. Queensland mining project statutory environmental authorities must also specify how progressive rehabilitation is to occur throughout the mining project. Final landforms with graded banks together with creek and run-off diversions are often required and constructed early in the life of a mining project. At closure, mining projects must demonstrate that future medium-term risks are not significant, or failing this, a residual risk financial payment must be made to the state. CSIRO climate change projections indicate that Queensland is likely to become warmer this century with less rainfall in parts and with extreme rainfall events likely to occur more frequently. This project was undertaken to?determine: if current rehabilitation planning tools assist in determining the environmental risks from mining closure not adequately addressing climate change if these risks are addressed by current rehabilitation outcomes.The north-west Queensland mining region and the central Queensland coalfields were represented in this project by five study sites. Local data sets for temperature, rainfall and rainfall intensity were produced using conservative greenhouse gas emission scenarios representing likely future atmospheres, and using the SimCLIM climate model, Evaporation data sets were also derived from available climate parameters. These projected climate variables supported equations and models used in Queensland to determine mining project rehabilitation completion criteria. Storm intensities and return intervals were directly applied to assess the likelihood of failure of engineered structures such as stormwater diversions and banks. Plant cover change determined by an existing growth model together with rainfall intensity and changes in the R and C factors of the universal soil loss equation (USLE) erosion model enabled estimates of long-term erosion rates. Flood estimates were undertaken using regional rated catchments.The study found that stormwater diversions and banks on recontoured rehabilitated landforms, if constructed to currently accepted completion criteria, would likely fail within 30 years and with the likelihood of failure steadily increasing thereafter. The change in likelihood of failure was able to be estimated and could be applied to the determination of residual environmental risk for approval of a surrender application involving rehabilitation. The USLE model showed that long-term erosion rates increased as a consequence of climate change from north to south across the Queensland mining precincts. Because the growth model did not consider carbon dioxide fertilisation affects, results would likely be worse-case.Likely climate change outcomes have consequential residual environmental risks of mining project rehabilitation failure. This increased risk may result in increased payments to the state from mining projects where high consequences exist. The liability to the state and risk to the environment can be avoided if today’s completion criteria address tomorrow’s climate change impacts.CITATION:Evans, M C, 2014. Queensland mines should consider climate change impacts for decommissioning, in Proceedings Life-of-Mine 2014, pp 535–562 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 16, 2014

Electro-Flotation Research on Fine Cassiterite

Sep 13, 2010

Determination of Porosity and its Influence on Specific Surface

Sep 13, 2010

By Stitt P. H

In Australia, the term "heavy mineral deposits" is used to denote sands which contain variable but economic quantities of the minerals rutile, ilmenite and zircon, often with minor amounts of monazite and xenotime as co-products. Australia has been a significant producer of rutile, ilmenite and zircon from such sands for fifty years and has long been the leading producer of rutile and zircon. The industry had its beginnings with the mining of present day beaches in northern NSW in 1934. Early work was small scale and in some cases involved hand winning of naturally concen- trated mineral for direct export. During World War II and immediately after the industry became increasingly mechanised and by the 1970s on the east coast operated between Newcastle, NSW north to Fraser Island in Queensland. Deposits worked included present day beaches, fossil strand lines up to 5 km or more inland from the present coast and aeolian concentrations. In the mid 1950s, operations commenced on the west coast of WA, south of Perth. Western Australian mineral sands tend to be rich in ilmenite as compared to the east coast. However the WA ilmenites are lower in chrome oxide and make a better syn- thetic rutile feedstock.

Jan 1, 1988

By J P. Sykes, A Trench

"The common-held view of the future of copper mining is one of declining quality of mineral resources and increasingly limited long-term development options. This decline, in turn, is viewed as inevitably leading to increasing economic, socio-political and environmental costs. As a result, new technologies and innovations will be required to mitigate cost escalation. The future is therefore typically summarised as a battle of a ‘below-ground’ declining quality asset base pushing costs upward versus ‘above-ground’ technology and innovation driving costs downward. The role that high quality new mineral discoveries could play in mitigating industry cost pressures is typically understated, if considered at all. New high quality discoveries can be mined at lower cost than existing assets and potentially if discovered in the right locations within a more amenable contemporary environmental and socio-political setting. Such deposits, once discovered, would improve the overall quality of the industry asset base, as well as benefitting their owners substantially through higher margins. However, to target new high quality deposits explorers need some understanding of the nature of high quality copper mines in the long-term future. Conventional scientific and economic techniques for analysing the future of copper supply, generally by studying the project pipeline, ignore as yet undiscovered resources and also struggle to fully incorporate the multiple internal and external factors that could impact upon copper mining practices in the future.Scenario analysis is specifically designed to consider multiple factors interacting in the future, and is thus more creative than simply looking at the visible project pipeline. The use of scenarios is therefore potentially capable of providing insight into aspects of the future of copper mining about which little is currently known or that remains considerably uncertain. In this study, the Oxford University Scenarios methodology was employed to analyse different plausible futures for copper mining and the consequent implications for exploration targeting strategies. The scenario analysis highlights two key dimensions or axes that serve to map out potential industry futures: firstly the technical and economic optimisation of the existing industry; and secondly the generation of new prospects or ‘search space’ for the copper industry. These two axes in turn frame four different scenarios for the future of the copper mining industry. These copper mining scenarios are then compared to the 20 largest existing copper mines and projects, and their owners, to determine if any represent an appropriately robust exploration targeting proxy: none do. The paper therefore concludes that efforts by industry are required to generate mine concepts that would be viable across all scenarios, and thus act also as exploration targeting proxies. In the interim, companies will have to seek to build portfolios that create an overall robust asset base, out of individually less robust assets. Failure to do this implies that consequential, irreversible strategic decisions lie ahead for the copper mining industry, which may be a threat to both incumbents and the very industry itself. This situation makes strategic exploration targeting in the copper industry very difficult.CITATION:Sykes, J P and Trench, A, 2016. Using scenarios to investigate the long-term future of copper mining and guide exploration targeting strategies, in Proceedings International Mine Management Conference, pp 265-290 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 22, 2016

By Dodd SF

Valuation of mining companies and their underlying assets prepared by brokers' analysts are, by necessity, approximations. The reliability of the valuations is entirely proportional to the quality of available data, the reliability of forecasts and the nature of underlying commodity price assumptions. The latter is perhaps the greatest single cause of gross variations in company and asset earnings estimates and- valuations. Assumptions are often necessary regarding commodity price achievement based on commodity hedge positions. Public disclosure from listed companies provides a sound base from which to project earnings, cashflows and balance sheets. The uncommon disclosure of projected production and cost schedules often reduces the reliability of future estimates. The application of reserve and resource estimates is contentious with practitioners applying differing weightings to importance of resources in estimating mine lives (and therefore cashflow streams). Valuation methods applied in equity markets usually focus on relative value and the identification of pricing anomalies. The commonest ""rules of thumb"" applied in the valuation of mining companies (and therefore their underlying assets) is with the use of year specific price/earnings (P/E) and price/cashflow (P/CF) ratios, with low multiples suggesting undervalued assets, high multiples overvalued situations (but these rules can often be clouded by market expectations of underlying commodity price movements). Another simply applied valuation tool is to examine the examine the value placed on reserves and resources by the market. Inexpensive gold in the ground (expressed as $ of market capitalisation per ounce of reserves or resources) might indicate a buying opportunity, but the market does discount the value of gold in the ground prior to mine development and where development risk is perceived.

Jan 1, 1994

The Role of Mineral Processing in the Development of Cement with Low Carbon Emissions

Sep 13, 2010

In a modern economy there is a compelling case why governments should not own property rights to mineral deposits. Assuming they do, however, governments will use these constitutional rights to raise revenue. They have two basic instruments to achieve this; a royalty charge on price or a rent tax on income/profits. On the one hand, a royalty charge creates a 'deadweight loss' to society by increasing cut-off grades and decreasing the life-of-mine. They are also regressive. However, they are easy to administer. On the other hand, a rent tax avoids the problem of 'deadweight loss'; it does not impact on the life-of-mine because the tax structure is neutral. But, they are difficult to administer correctly, particularly in the determination of rents and the definition of mining per se. If rents are incorrectly determined capital markets are distorted. And, if mining activities are incorrectly defined, downstream activities could be adversely affected.

Jun 1, 2010

By J Robinson, D Herbert

Bench stoping operations at the Isa Lead mine have been underway for over 11 years. They were implemented to address safety, productivity and mining cost concerns noted with cut and fill mining operations which were then being used to extract ore from the Racecourse orebodies. This paper describes the main features of benching operations at the Isa Lead mine and identifies the key elements for the success of the method. Four case histories are presented which highlight several of these factors.

Jan 1, 1998

Bubble Load Measurements in Flotation - A Critical Review of Current Practice

Sep 13, 2010

By A G. Noble

Tunnelling for hydro-electric power projects can be a very challenging component of the overall development. In contrast to urban transportation tunnelling where the logistics for access and supply of power, water and other essentials are readily available, hydropower projects are usually in very remote locations and all necessary plant, equipment, spares and materials need to be brought in and the site must function as a self sufficient unit.For a large scheme the river diversion tunnel(s) are usually on the initial phase critical path in order to meet the non-negotiable deadline of river diversion before the onset of the wet season. A newly formed tunnelling crew, once mobilised to the site for the project, will face the first major learning curve of the project’s systems and logistics during this critical tunnelling activity.Power tunnels convey the water to the turbines in the powerhouse and are usually on the critical path for the main works, especially if the scheme comprises a powerhouse located within an underground cavern. A modern cavern arrangement requires a complex warren of various openings: access adits, ventilation/cable tunnels, shafts, surge tunnels, etc.Hydropower tunnel construction tends to be dominated by tunnel boring machine (TBMs) or drill-and-blast excavation techniques and each has its challenges in very remote locations. TBMs still have long lead times as for any type of project, but additionally require a thorough roads and bridges infrastructure assessment of the country from the port of entry to the site to ensure a problem-free delivery. In some cases the project also requires the establishment of a complete precast concrete segment production facility and the space for creation of laydown areas; there is no ‘just-in-time’ delivery mechanism applicable to typical remote hydropower sites.This paper highlights the technical and risk management considerations in the planning, design and construction of tunnels for hydropower projects. It contrasts the typical factors that govern the design of urban transportation tunnels with those for remote hydropower tunnels. The perspectives of stakeholders are provided including those of international lenders. With examples from large and small scale projects across the globe it provides an insight to all parties and in particular, those tunnellers that are working in the hydropower field for the first time.

Mar 8, 2011

A series of in situ pull tests has been conducted to determine the holding capacity of the standard SS46 Split Set Stabilisers. The experiments have been conducted in a wide range of geological conditions ranging from bedded rock to blocky ground. The results presented in this paper indicate that cement grouted split sets bolts are likely to provide up to three times the initial bond strength per metre of embedment length provided by the ungrouted bolts. The increased load transfer capacity of the grouted bolts provides an alternative for permanent excavation support using split set stabilisers.

Jan 1, 1997

By T Wootton

The Barrytown ilmenite pilot plant was commissioned in two stages using Westport Titanium Project heavy mineral concentrate. The wet concentrator was commissioned on the 17 December 1989 and produced magnetic concentrate from this date.   The Drymill was commissioned on the 27 January 1990 and produced product grade ilmenite successfully from the onset.   The commissioning period was exceptionally short by normal standards and few problems were encountered. This paper concludes with general observations of operations of the pilot plant.

Jan 1, 1990

Brunswick Mine, one of the largest underground zinc mines in the world, is scheduled to close in 2010 after almost half a century of production. All mines eventually close; some suddenly as a result of unsustainable economic or technical conditions and others, as in our case, as a result of the depletion of the orebody. When the mine is the most significant employer and an economic driver in the region, it is key that the closure is handled in a planned, communicated, well-executed fashion. The following paper documents strategies, plans and activities that are currently taking place in order to ensure a seamless closure that satisfies all stakeholders including employees, management, regulatory bodies and the public. It is an important deliverable for the company that the good will, credibility and reputation that has been built up over the years is sustained throughout the closure process and beyond. A life of mine labour agreement with the unionised workforce, staff retention and recruiting programs, regulatory closure plans, communications and transition adjustment activities will be discussed. The use of a stage-gate style project management tool analysing the risks and key deliverables will be highlighted. It is hoped that the concepts and approaches discussed here may be of value to other operations that will be faced with closure, and its inherent challenges, in the not too distant future.

Jan 1, 2006

The character of alluvial gold deposits presents severe difficulties, and sometimes limitations, on the extent to which metallurgical efficiency can be measured. Very little monitoring of metallurgical performance is practised. An indication of performance is often extracted from the comparison of production to the estimate. This is a dubious practice. The recovery efficiency of conventional practices, viz sluices, tables and jigs, falls off sharply below 0.2 mm. Field evaluation procedures tend to simulate these conventional practices. Thus the presence of fine gold may not be detected, particularly if obscured by clay. There is increasing evidence that fine gold could, in places, be present in sufficient concentrations to be economic. Most gold in paleoplacers is finer than 0.1 mm. There are established practices elsewhere in the mineral industry that may physically recover gold down to 5 microns in size and which could find application for fine alluvial gold.

Jan 1, 1984

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

Bendigo Mining operates a 600 000 t/a comminution, gravity, flotation and leaching processing plant for the recovery of gold from their Kangaroo Flat Operation, in the Bendigo goldfields. The free gold and gold bearing sulfi des present are typically coarse grained and hence are highly amenable to gravity recovery. Plant operating data is consistently showing that over 78 per cent of the feed gold is recovered in a circuit, consisting of inline pressure jigs, inline spinners followed by free gold tabling and intensive leaching of tabling tails. The circuit receives coarse crushed product from high pressure grinding rolls and the grinding mill discharge, which allows material to be re-circulated through the gravity process until the particles are small enough to enter the flotation circuit. A plant audit was completed on 26 November 2009 designed to give an indication of the overall operational characteristics of the gravity circuit including single pass efficiencies of associated equipment. The techniques, results and challenges of such a survey are discussed.

Aug 1, 2010

By J Sibbel, K Goh

A key issue facing mine managers in remote locations in Australia and overseas is that of managing a fly-in, fly-out (FIFO) workforce. Current Australian research (Sibbel, in prep) indicates that FIFO employees and their families do not differ from the general population in terms of their overall mental health and the well-being of their family relationships. However, they do face unique issues/pressures associated with the lifestyle, the impacts of which are dependent on the policies and practices of the company as well as individual coping and support mechanisms. Successful management of a FIFO site and its employees therefore requires specialist knowledge and skills beyond those of a solely residential operation. The well-being of the FIFO workforce depends on both site and individual employee characteristics, and has implications for productivity and turnover, as well as safety and health. In addition, although FIFO separates individuals and their families in time and space, the interaction between work and home must be acknowledged and taken into account. Drawing on findings from recent Australian and international FIFO research (eg Annear, Poot and Kingston, 2006; Beach, Brereton and Cliff, 2003; Brereton et al, 2006; Gallegos, 2006; Keown, 2005; Parkes, Carnell and Farmer, 2005; Sibbel, 2001, 2004, in prep; Shrimpton and Storey, 1996; Storey, 2001; Watts, 2004) this paper discusses key understandings of both the positive and negative impacts of FIFO employment on employees and their families, and provides practical management strategies as an aid to the development of best practice. Individual impacts including fatigue and loneliness, as well as family issues such as communication, continually changing roles and responsibilities and the impacts of regular parent absence are key areas which can be ameliorated by appropriate management understanding and action. A flexible framework approach is presented that is suitable for a diversity of operations, including principal and contractor workforces of different sized operations.

Jan 1, 2006

By A Vickerfält, J Huss, J Martinsson

The European Union has listed vanadium (V) as one of the critical raw materials for the transition to a future green society, as stated in the Critical Raw Material Act, written by Grohol and Veeh (2023). In the steelmaking industry based on V-containing iron ore, V is a possible by-product from the slag. A requirement for slags to be suitable for V extraction is a V content preferably above 8 wt per cent as V2O3 and a phosphorus (P) content below 0.1 wt per cent as P2O5. Hence, it is important to keep V in the slag phase while the P is moved to the metal phase during the steelmaking process.

Aug 21, 2024