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THIS instrument, depends on the principle that, over a short period, the surfaee of a porous substance from which a liquid is evaporating receives the same amount of heat by conduction, convection, and radiation as it loses in the latent heat of the evaporating liquid. If, then, the amount of heat being received by a surface can be measured, the rate of evaporation can also be obtained. The Kata thermometer is also based on this principle differently applied.The instrument, as shown in Fig. 1, consists essentially of a thermometer with a sliding which is divided by three pointers into two equal parts which may be spaced so as to cover a distance of, for example, 5° of the thermometer scale. The instrument is calibrated so that the amount of heat required per unit area of the bulb to raise the menissus is known. The method of using the instrument is as follows:The slide is first set so that thc central pointer is at the temperature of the evaporating surface.The thermometer is cooled by any convenient means so that the meniscus is several below the lowest pointer. The thermometer is then placed near the evaporating surface, when the Ineniscus begins to rise and the time taken for it to rise from the lowest to the top pointer is measured. From this and the calibration results the amount of heat retained per unit area of the bulb at the mean temperature...

Jan 1, 1928

By D Curry, M F. Young

æConventional wisdomÆ believes that fine particles have low flotation recoveries. Plant size û recovery graphs often have the classic æhillÆ shape û high recovery in the mid sizes and low recovery at the fine and coarse ends. Yet if mineral liberation is poor, low fines recovery may be because you don't grind fine enough! This apparent paradox is explained by the old concept of æsand/slimesÆ circuits, which recognises the different flotation needs of fine and coarse particles. This concept is overlooked in the push for simpler circuits and larger equipment. Most plants now treat all particles together in a wide size-distribution. Reagent conditions are set for the dominant coarser particles, so fines are starved of collector. Worse still if there are significant midsized composites û often these have to be rejected in cleaning to achieve target concentrate grade. But the conditions which reject mid-size composites û collector starvation and high depressants û also reject fine liberated particles. In fact, fines flotation can be excellent when flotation chemistry is tailored to fines.

Jan 1, 2004

By Reilly SY, Green TH, O&apos

Alkali feldspar meggacrysts are commonly found (with aluminous clinopyroxene, kaersutitic amphibole, titanomagnetite, ilmenite and apatite, and more rarely with zircon and corundum) in alkalic basalts and their derivatives as discrete crystals and fragments. They are commonly euhedral or subhedral and may be up to 15 cm in size. Their occurrence has been reported from many localities around the world, e.g., Africa, Antarctica, eastern Australia, eastern China, East Fife (Scotland), Eifel (Germany), Massif Central (France), Mongolia, New Zealand, New Mexico (USA) and Siberia (USSR). These megacrysts are relatively homogeneous and belong to the Na-rich anorthoclase group, although Kutolin and Frolova (1970) called them sanidine due to their monoclinic nature. The majority of megacrysts have a molar orthoclase content (Or%) between 20 and 30 (Fig.1). These anorthoclase megacrysts possess a high degree of disorder, with the structural state belonging to the high albite-high sanidine series (Hoffer and Hoffer, 1973; Chapman, 1976).Published interpretations of the origin of anorthoclase megacrysts fall into the following two categories: either (1) Anorthoclase together with the associated pyroxene and amphibole crystallized from basaltic magmas as phenocrysts (cumulate phases) at high pressure and the present host basaltic rocks are the parent magmas for the anorthoclase megacrysts (Binns,l969; Binns et al. 1970; Kutolin and Frolova, 1970; Hoffer and Hoffer, 1973; Laughlin et al. 1974); or (2) Anorthoclase probably crystallized from a more evolved liquid at relatively lower pressure and was then picked up and carried to the surface by a later

Jan 1, 1990

When a joint venture is established between a major and a minor, the co-venturers often have a number of divergent interests; the major may have put up significantly more capital into the project and will want to protect its investement; the major may have more financial resources and be more readily to commit capital to the project; the major may have more technical resources and expertise to provide to the project; the major may have other competing demands for its capital; the minor may be relying on rapid development of the project as its sole source of cash flow. Successful joint ventures arise when the co-venturers understand each others' interests and attempt to satisfy these interests. This could be achived by having a clear process and timetable for development of the project coupled with clear rules for distribution of income, the commitment of capital to the project and the provision of inter-company services. If divergent interests are either regulated clearly or eliminated, both co-venturers are more likely to seek common objectives in the joint venture with less scope for conflict. This paper, written from the perspective of a major, examines means of establishing successful joint ventures between majors and minors.

Jan 1, 1997

By A Maurer, N Pereira

Low-density explosives have been developed with trials being conducted for over 20 years and yet have still only gained limited market acceptance despite producing some very promising results. The biggest concern with industry acceptance has been disbelief that a product with lower density than the ANFO benchmark could fragment anything but the weakest of strata. Trials have been carried out with products such as diluted ANFO, low-density ammonium nitrate (AN) and various other mixes, although it has been only recently that low-density explosives have been accepted as a serious alternative to traditional products such as ANFO and heavy ANFO. The recent uptake of low-density products has been the result of several key factors: the current resources boom forcing AN supply issues, the development of new handling techniques, and a far better understanding of the utilisation of such products. This paper highlights the benefits of low-density products available in the market and focuses on the situations where low-density explosives can provide the end user with benefits that would otherwise be achieved through more time consuming methods. Through correct implementation, low-density explosives can provide the blast designer with another option when looking at the optimum method of breaking the rock. This while still controlling the other limiting factors such as cost, environmental impacts (noise, vibration, dust and fumes), coal damage and safety (stable walls).

Jan 1, 2005

By Carlie JC

Many low sulphidation epizonal gold and zinc-lead vein deposits within magmatic arcs are situated on basement highs, and post-date both the main volcanic episode and porphyry copper (gold) mineralization. These features are best explained by emplacement of a flat batholith a few kilometres beneath each mineral district, as recently demonstrated by geophysical data in the Baia Mare district of Romania. The batholith provides heat for the hydrothermal system, and results in extensional faulting both through up-doming of the overlying rocks, and in some arcs through incipient collapse of the thermally weakened crust under regional extensional stress. More water-rich magmas emplaced at greater depths could explain some deep epizonal and mesothermal gold deposits situated outside magmatic arcs.

Jan 1, 1995

By M McCarthy

Attraction, recruitment and retention of quality mining engineers is becoming increasingly difficult for many mining companies. Part of the problem is attracting young professionals, especially given the decline in graduating engineer numbers, and the other is balancing the new engineerÆs development with business needs. The evolution of the graduate program at Olympic Dam over the last five years has resulted in substantial benefits for both the engineer and the company. The program has developed to provide structured exposure to key areas of the mine enabling new engineers to step into vacated roles as the need arises. The pool of quality engineers generated by the graduate program is a buffer against high industry turnover and helps reduce future recruitment expenditure. Olympic DamÆs program goes beyond conventional recruitment of graduate engineers. Innovations designed to improve intake include the employment of graduate engineers as well as final year students, retraining of existing personnel from other backgrounds and fast track recruitment for previous vacation students. By employing a cross-section of professionals to complement the generic university graduate, the company takes full advantage of the relevant lifestyle experience belonging to the individual, which is a substantial factor in turnover. Study assistance and a salary paid for final year students and mature age students often creates a loyalty that lasts beyond graduation. Careful selection of vacation students increases the ease of recruitment at a later stage and ensures that full advantage is taken of the relationship developed previously between the company and young professional. The evolution of recruitment at Olympic Dam has seen a decline in the turnover statistics of young mining professionals.

Jan 1, 2005

By A Buckingham, R M. Hancock

The underground Sunrise Dam gold mine commenced in October 2003 to extract ore from a series of orebodies with various dips, widths, and ore grades over a strike length of 1.5 km. To successfully operate flat stopes it was identified that a means to extract ore left behind after blasting in stopes with dips ranging from 15 to 40 degrees was needed. Various options were available, which included a bulk water cannon, hand held high-pressure water jet, remote controlled small dozer, several mini excavators and finally a specialised remote controlled excavator from the demolition industry. Trials were commenced for the bulk water cannon option in 2006 that proved that the concept worked, however, the system was too cumbersome to set up for use in cycle with production. Hand washing down using mine (low pressure) water with a two-inch bullhose proved of limited value. The small, one metre high remote controlled dozer as used in South Africa was reviewed, but the steepness of most of the stopes precluded this machine. The hand held high-pressure water jet option is still being investigated; with safety factors still being addressed. Several mini excavators were trialled to clean out the flat stopes with generally poor results, the machines being either too large to fit in the drives and pull ore down or too small with too short reach to effectively and efficiently pull ore out of the stope. In early 2007 a Brokk 330 remote controlled excavator was trialled on site with the low profile of the machine and unique arm configuration proving an effective tool for pulling ore from the footwall of short, flat stopes. A Brokk 330 remote controlled excavator was purchased in late 2007 and is currently in operation.

Jan 1, 2008

The most frequently applied project evaluation criteria are the Net Present Value, the Internal Rate of Return, and the Pay Back Period. Unfortunately, the Internal Rate of Return and the Pay Back Period, if interpreted according to their traditional definitions, easily produce results which contradict the Net Present Value. The reasons for the Net Present Value incompatibility of the two criteria are that these criteria have not been adequately defined and so new, complete definitions are recommended. The concept of the True Rate of Return is proposed as a substitute for the interest rate that the Internal Rate of Return has been believed to represent. The redefined Internal Rate of Return and Pay Back Period criteria, as well as the True Rate of Return are all Net Present Value compatible and can, therefore, serve as independent project evaluation criteria. Also, the correct approach to the evaluation of mutually exclusive alternatives and the status of the often neglected borrowing projects in project evaluation are found to be quite important.

Jan 1, 1991

By de Brodtkorb MK

Late Cenozoic ore deposits "Precious and base metal-rich" and " Sn-Ag-polymetallic"of Northern Puna are associated either with Middle Miocene dacitic volcanic-dome complexes or with Upper Miocene dacitic-andesitic volcanic centers. Ore mineralogies and their related volcanism are discussed. A strong link is observed between the Cenozoic Metallogenetic Province of Northern Puna and the Southern Bolivia Tin and Polymetallic provinces.

Jan 1, 1995

The Ausmelt Catalytic Waste Converter (CWC) has been developed for use in the treatment of industrial wastes and for the recycling of secondary materials. Ausmelt Technology uses a top submerged lance system within a versatile and efficient slag bath reactor. High temperature pyrometallurgical reactions are carefully controlled within an oxidised molten siliceous slag such that metals can be extracted from waste feedstock for recycling, with non-volatile elements reporting to the slag, usually as oxides. Modification of the slag chemistry results in a final slag product that is stable, vitrified and is able to pass standard leach tests such that it is safe to discard or be used in civil engineering applications. Toxic components in the wastes such as organohalides can be completely destroyed and are prevented from reforming. Waste to energy conversion is practiced by the addition of a heat exchanger/steam generator in the converter offgas system. The Ausmelt CWC has been used for recovering zinc from residues and slags, treating spent potliner (SPL) from the aluminium industry and a wide range of electronic and other potentially valuable waste materials. Methods of monitoring the exhaust gases at different stages in the CWC gas handling system are discussed. The assay of these gases prior to emission is used to assist in the control of the converter chemistry to ensure the complete oxidative breakdown of the feedstock.

Jan 1, 2002

As an environmental "pollutant", noise is different. For one thing, it is localised (as opposed to transfrontier) and, for another, relatively low levels can trigger very strong human reaction. The reactions, which are annoyance-based, range from mild to violent and do not always correlate well with the levels experienced. This paper draws on technical aspects of noise to consider control and control principles and balances them with the subjective nature of the perceptions and reactions. It is critical to bear in mind that health effects resulting from noise are secondary to the primary human reaction. It is also important to appreciate that annoying noise levels are usually well below those which cause hearing loss. Large mines tend to be remote from cities and towns and the country surrounding such mine sites is often inhospitable. In general, residences near large mines are committed for use by mine personnel and annoyance from mining noise would be rare. Noise problems at long term operations are often a result of secondary activity or land use. As a pioneer mining community develops, secondary and service industries may be established and a township created. With changes in way of life, the perception of problems also changes. Therefore, it is never too early to plan for noise abatement, particularly because noise is only one of a number of environmental and community concerns. Ihny environmental problems are associat- ed with development or expansion of smaller open cut facilities such as hardrock quarries. There is an ever-present need to reduce product cost by mining or quarrying deposits close to the end user and many local authorities have to operate quarries for undertaking their civil engineering responsibilities.

Jan 1, 1987

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

By B Cooper

During the design of a new production facility for a greenfields or significant brownfields expansion many design decisions are made driven by an unquestioning objective to achieve 'lowest cash-cost' production costs. In many cases this translates to a design and operating philosophy based on largest-available, single-line equipment. Although acknowledged as an approach that is efficient from an operating cost perspective does this approach always maximise shareholder value? There is an increasing awareness in the mining industry of the value of project flexibility, robustness and value options. The design of a new production facility creates a window of opportunity which should be structured to ensure that project value options and robustness are understood and exploited. This requires the use of emerging valuation methodologies, such as Value-at-Risk and Real Options, as well as tried and trusted NPV/IRR approaches. The paper provides an overview of the basis and application of these less well known techniques in the context of metallurgical plant design. Design guidelines that demonstrate how value options and flexibility can be quantified from both a risk and value perspective are presented. Issues such as use of single versus multiple line equipment, optimum cut-off grade and improved exploitation of the inherent variability of the orebody are also examined. Finally the management issues and approaches to achieving this will be briefly discussed; for example it is common during project development to drive towards increasing certainty as rapidly as possible to facilitate 'accurate' estimation of costs. Understanding and exploiting value options requires a project culture that tolerates, and revels in, ambiguity and uncertainty û something that would make many project teams uncomfortable!

Jan 1, 2008

By M Noppe, I Glacken

There are many critical nodes along the mine value chain, from orebody to mineral product, and inter-disciplinary input is required to analyse the variability and uncertainty at each node in order to identify and mitigate areas of risk. Mining differs from many other industries in that the variability in the product is dictated largely by the inherent nature of the input material (the orebody). The true characteristics, including the variability of the orebody, are never known exactly and are instead based on estimates derived from sample data. A further difference is that bottom-line gains are largely controlled by world commodity prices, which can vary with time, rather than by local supply and demand issues. Methods for identifying, reporting and responding to this inherently variable raw material are discussed. These include analytical and reporting methods, equipment and software, risk analysis and reality checks (eg reconciliation). Sampling results, mineral resource and ore reserve estimates and economic assumptions are a function of the variability of the orebody. Risk quantification should be expressed as a level of confidence, which takes into account the scale or period over which the risk is being assessed (life-of-mine, annual or shorter production periods) and should convey the likelihood, severity and consequence of occurrence of a given event. The future generation of mining specialists needs to understand the entire mine value chain to better manage risks and maximise mine dollar-value.

Jan 1, 2002

Low tonnage quartz vein-hosted stibnite lodes are widely distributed in rocks of the Tasman Fold Belt System in eastern Queensland, with particular concentrations in the Hodgkinson - Broken River Fold Belt and to a lesser extent in the Gympie Province of the New England Fold Belt: Higher grade deposits have been worked intermittently on a small scale since 1873, resulting in the production of about 5500 tonnes of antimony ore/concentrate with an estimated grade of about 55% Sb. Future production of antimony may be as a by-product from deposits, currently being explored/mined for gold in the Hodgkinson/Mitchell River area and the Amanda Bel goldfield. Establishment of an antimony processing plant in Queensland using the Quelar Process would provide a more reliable market for small producers and could stimulate future exploration and production.

Jan 1, 1990

I must tell you at the outset that I come to this conference deeply disturbed at the `role of Government in international dealings in mineral and energy resources'. I am disturbed by the confusion that now passes for policy. I am disturbed by the short- range view of critical problems taken by a majority of Governments. I am equally disturbed by the even shorter range of view taken by a growing army of industries. Many of them clamour for Governments to solve their problems in a specific way, with little regard for any other sector but their own-and with even less regard for the fact that every time a Government takes over some of their responsibilities they surrender some of their freedom. I would not say that longer range views don't exist. But I would say that they don't prevail at the present time. Instead, we are seeing the con- stant development of many policies for individual problems which don't tackle the fundamental causes. We must get back to basics without delay.

Jan 1, 1978

By R Dunne, D Yan

In flotation where a bulk flotation concentrate is produced or a gangue sulfide such as pyrite contaminates a concentrate, residual collector has to be removed from the sulfide surfaces to allow selective separation in a subsequent flotation step. Depending on the sulfide mineral, the main species that needs to be removed when using a xanthate collector is either a metal xanthate or dixanthogen. For the identification of surface species, specific solvents may be used to remove each species û metal xanthates are known to be soluble in acetone whilst dixanthogens are known to be soluble in non-polar solvents such as diethyl ether. Xanthates break down with time, temperature and pH into various decomposition products. The major decomposition product is dixanthogen which can aid flotation but other products such as perxanthate and carbon disulfide can have an adverse effect on flotation. Various analytical techniques can be employed to monitor the formation of decomposition products on the surface of the mineral and in solution. The best of these is ultraviolet spectroscopy as it has diagnostic peaks for decomposition product determination. In this work two approaches were taken to understand the relationship between the flotation of a chalcopyrite and pyrite from an ore containing these two minerals. One approach was to remove the xanthate species with an organic solvent and then use ultraviolet spectroscopy to determine the concentration of dissolved species. The second method involved measuring xanthate decomposition in solution by measuring the residual xanthate concentration using ultraviolet spectroscopy. These experiments confirmed the species adsorb at the surface of the mineral and how these species affect the recovery and grade of the valuable mineral. In both cases pH and temperature were varied and two xanthate collectors (SEX and PAX) were used to study these relationships. These relationships could be applied to industrial flotation systems and allow for more accurate determination of optimal xanthate dosage and hence save on reagent costs.

Jan 1, 2005

Education and Training for the minerals industry has been identified as one of the key priorities by the AusIMM and many closely related groups. The AusIMM Education Taskforce has been engaged, through a visioning exercise, in evaluating what minerals education and training should look like by 2025. A common recurring theme is that for minerals education and training to be efficient and effective into the future, it needs to be comprehensive and inclusive. Some previous attempts to achieve efficiency and effectiveness have had limited success, mainly due to approaching the issues involved from a narrow, singular perspective. This paper outlines that the achievement of the desired outcome may require an approach that parallels the same techniques that are used for multi-dimensional mine planning, treating tertiary minerals education and training in a similar way to the planning involved for a complex orebody. Just as efficient and effective mine planning requires engagement and understanding of many factors, so too does engagement with tertiary minerals education and training. The major factors that need to be considered are outlined in the paper, including: levels of tertiary education and training; Australian Qualifications Framework (AQF), Levels 1 to 13: systems of minerals education and training, such as higher education, (mainly universities), industry/professional associations and licencing requirements, vocational education, (mainly TAFE) and workplace programs; types of minerals or mining methods involved; volume of delivery; stage in the flow sheet, (geology, mining, beneficiation, extraction, refining). For comprehensive mine planning there is the need to develop links or roadways and openings between different levels of a mine. Similarly, to achieve a comprehensive tertiary minerals education and training model, there is a need to develop pathways, recognition and credit transfer between the various levels and components of minerals tertiary education and training.

Jan 1, 2005

By P S. R Reddy, V N. Misra

The iron ore deposits in India are rich in iron content but usually contains high alumina and silica. The current industrial practice results three products namely lump, fines and slimes. The lump and fines with or without beneficiation are directly fed to the blast furnace and sintering plant respectively while the super fines or slimes are presently discarded as tailings. Around eight million tonnes of iron ore slimes estimated as being 15 - 20 per cent by weight of run of mine ore containing ~48 - 62 per cent Fe, is discarded every year causing huge loss to the Indian iron ore industry. In addition, these slimes stored in massive tailing ponds pose enormous environmental and ecological problems. Extensive investigations have been carried out on three iron ore slimes generated at Barsua, Bolani and Meghahatuburu iron ore mines of India. The studies include physical, chemical, mineralogical characterisation and beneficiation studies adopting conventional hydroclyclone and wet high intensity magnetic separator. The characterisation studies have indicated that most of the gangue minerals are accumulated in finer fractions. The studies on hydrocyclone and magnetic separation had indicated that an iron concentrate of 61 - 65 per cent Fe could be obtained by recovering 59 - 78 per cent of the iron values present in the slimes. Depending on the nature of the slimes the alumina and silica levels have been brought down to 2.5 and 1.0 per cent respectively. The effects of different operating and design variables along with detailed characterisation studies have been highlighted.

Jan 1, 2002