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By D Craw

Sulphur-rich minerals such as authigenic pyrite (FeS2) are commonly associated with coal mine workings. Metallic elements such as arsenic (As), copper (Cu) and zinc (Zn) are enriched in the pyrite relative to their concentrations in the surrounding environment. Exposure of pyrite and coal to air and water results in a series of oxidation and hydrolysis reactions that are commonly catalysed by species of Thiobacillus bacteria. These reactions lead to a lowering of the pH in the drainage waters (acid mine drainage, AMD) and subsequent mobilisation of trace metals in environmentally significant concentrations. This study assesses the spatial distribution of As, Zn and Cu concentration in water in relation to pH and Eh (redox potential) downstream from the tailings at the Wangaloa opencast lignite mine in southeast Otago. This mine was abandoned in the late 1980s due to a decrease in the economic viability of mining the lignite. The area is showing the characteristic symptoms of AMD, which is detrimental to the health of several Pinus radiate growing on some of the tailings. The pH of the drainage waters can get as low as 2, and in some instances, lower, but it returns to near neutral (pH 6.5) up to 200 metres down stream from the base of mine waste piles. It is well documented that the atmospheric oxidation of pyrite is catalysed microbially, causing a substantial decrease in the pH of the drainage waters. Acidification is then counteracted predominantly by natural abiotic remediation processes occurring downstream.

Jan 1, 1999

The Porgera gold mine has made significant progress with the successful installation of a JK FrothCam image analysis system. The system is used to measure and control froth velocity on the scavenger circuit which has brought significant economical and operational benefits. The froth velocity signal, determined by analysis of the camera, is transmitted to the PLC that manipulates flotation cell airflow rate and cell level controllers to maintain a target froth velocity of 130 mm per second. Following on from a three-week trial installation in June 2000, a permanent installation was commissioned on the scavenger Outokumpu (OK150) tank cells. Further work is in progress on the rougher Wemco cells. This paper describes the evaluation of FrothCam Technology and its subsequent installation.

Jan 1, 2003

Kinetic Study on the Leaching of Vanadium from LD Converter Slag Using Sulfuric Acid In order to reduce the environmental impact due to land disposal of LD (Linz-Donawitz) converter slag from steelmaking plant and to valorise this waste material, an acid leaching study was carried out to assess the effect of several parameters on the kinetics of vanadium dissolution. The characterisation and morphology of the feed investigated using XRD, XRF. The factors influencing leaching vanadium such as particle size, temperature, slurry density and the concentration of sulfuric acid were investigated and optimised. The maximum vanadium recovery about 95 per cent achieved at 70¦C, S/L: 1/15, acid concentration: 3M and for 150 minutes of leaching time. The dissolution of vanadium in sulfuric acid shows that there are two stages in the kinetics of leaching. At the first 15 minutes, there is a sharp increase in the amount of vanadium extracted and at longer leaching time, the extraction increase slightly. In the present work, the shrinking core model (SCM) was used to describe the acid leaching of vanadium compounds. A summary of the controlling regimes in the SCM are examined below for short time (less than 12 min.) and long time (more than 30 min.) stages. So, it was found that the kinetics of leaching in both stages is controlled by solid product diffusion regime.

Sep 13, 2010

By J Chegwidden

Rare earths are a critical minor constituent of many advanced materials that are essential inputs to the manufacture of items such as mobile telephones, computers, televisions and autocatalysts. Although rare earths have a relatively high unit value, the impact of this cost has little, if any, impact on the selling price of the final item. Furthermore, as they are generally present in minute concentrations they are not recycled. It is for these reasons that rare earths are considered strategic materials. China dominates the market as it supplies over 85 per cent of world demand. It has recently taken steps to increase prices through the restriction of exports and support for minimum prices by an association of the major producers. This paper provides an overview of future opportunities for Australia in the context of the current dynamics of world supply and demand.

Jan 1, 2001

By G J. Lyman, S A. Tittlemier

International regulations exist to manage the concentrations of mycotoxins such as Ochratoxin A (OTA) and deoxynivalenol (DON) in grains and prevent health risks from excessive exposure to OTA and DON. Since the permitted levels of these mycotoxins are very low (existing maximum levels are in the range of 5 ppb for OTA and 1–2 ppm for DON), sampling for these mycotoxins is potentially challenging. Given that the distribution of infected kernels in a consignment of wheat can be highly heterogeneous, detection by current sampling methods is subject to a high variance. Furthermore, the concentrations of mycotoxins in individual kernels vary over orders of magnitude, intensifying the heterogeneity of the bulk grain.In these circumstances, there is much interest in developing sampling plans that inform regulatory agencies, and mitigate the risk of misclassifying grain shipments as compliant or non-compliant within the global grain trade, when correctly implemented.Experimental data from laboratory and field studies describing individual wheat kernel concentrations of OTA and DON were combined with experimental data describing the variance due to the analytical methods used for OTA and DON to calculate the sampling distribution for wheat having various levels of contamination. This work has focused on quantifying the heterogeneity of samples at the point of submission for analysis and within subsequent sample preparation to arrive at total sampling distributions that include uncertainties due to the intrinsic heterogeneity and the analytical uncertainties. The sampling uncertainty that relates to the difference between the primary sample analysis and the true lot analysis is not included as it has been dealt with elsewhere.CITATION:Lyman, G J and Tittlemier, S A, 2017. The sampling characteristics of grains contaminated by mycotoxins, in Proceedings Eighth World Conference on Sampling and Blending , pp 281–294 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By J Karlovšek, M Hafner, M Žibert

The transport network in Europe is probably one of the most important systems for the European economy and society. Trans-national transport routes play a vital role in the traffic of goods and the supply of the population. In this respect, critical road infrastructures, like bridges, tunnels or control centres, can have a bottleneck function. Any disturbance of these structures could lead to negative consequences for the population and the economy as a whole.Project SecMan – Security Manual – is a simple four-step procedure for the identification of critical road infrastructures; assessment of these infrastructures regarding various man-made threats and the determination of effective protection measures was developed. These methodologies are summarised and combined into a comprehensive best-practice manual that allows for a trans-national structured and holistic security-risk-management approach for owners and operators of road infrastructures in Europe.Currently no common processes, methodologies or standards exist in Europe regarding the consideration of security relevant events for critical road transport infrastructures, eg tunnels, control centres and bridges. Attacks on the former can have severe short- and long-term effects with high media attention. A trans-national risk management approach would increase the possibilities for prevention as well as mitigation. A trans-national emergency response strategy would increase preparedness, as well as facilitating and accelerating the reaction in the case of an event.The main objective of the project is to develop a practical process for the identification of critical road infrastructures based on generally accepted security aspects. The assessment of these infrastructures would be carried out in a structured and traceable way regarding security relevant risks and the determination of effective protection measures for prevention and mitigation.The project is implemented by the German Federal Highway Research Institute (BASt) together with project partners from Austria (ILF) and Slovenia (DARS, ELEA iC).CITATION:Hafner, M, Karlovšek, J and Žibert, M, 2014. Road infrastructure security assessment and measures selection methodology using secman – tunnel example, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 69–82 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By T Haskell, Y Joe, S Dickie

A current trend amongst producers is the increase in dewatering of iron ore fines (<0.5 mm), due to an increase in wet beneficiation processes used to upgrade lower quality ore deposits, increased water content in orebodies located below the water table, and increasing focus on transportable moisture limits (TML). Vacuum filtration is commonly used for dewatering of iron ore fines, and as with all filtration processes performance decreases with particle size. Significant improvements are possible with the use of filter aids, usually anionic surfactants and flocculants. Anionic surfactants reduce the surface tension of the associated water, which is then removed more readily leading to improved filtercake moistures. Anionic flocculants used correctly can improve cake permeability, in turn, decreasing cake formation times and increasing filtration rates. In addition to increased throughput, savings and benefits for producers can include: moisture limit penalties, improved handleability, along with energy and water savings.The effect of filter aids on two iron ore fines samples from the Pilbara region were evaluated using a lab scale vacuum filtration unit. The first sample showed a reduction in the filtercake moisture content by 2.3 per cent weight/weight (w/w) with the use of BASF’s Drimax® 1234. For the second sample a reduction in the filtercake moisture of 3.4 per cent w/w along with an increase in filtration rate of 20 per cent was achieved by using a combination of Magnafloc® 5250 and Drimax® 1239 NF, as both filter throughput and cake moisture were considered important by site.CITATION:Haskell, T, Dickie, S and Joe, Y, 2017. The use of filter aids on iron ore fines, in Proceedings Iron Ore 2017, pp 183–186 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

Thermodynamics of Non-Cyanide Gold Solvents The present status of the raw material base in the gold industry requires specific ways to recover gold and silver from ores. Most gold is closely associated with sulfides which require flotation followed by pressure or bacterial oxidation. The next stages of processing usually require using expensive operations for the preparation of leaching. A lot of researchers want to find a new alternative solvent for the extraction of precious metals from these products. According to the authors, one of the best ways is to use sulfur-based solvents (thiosulfate, sulfite, and their various mixtures). Thermodynamics of gold and silver thiosulfate dilution are calculated for conditions: the concentration of Au - 200 mg/L, oxygen - 3.2 mg/L, thiosulfate - 79 mg/L, OH- - 170 mg/L. the general result is the possibility of process remains under standard conditions. (erAu = = 0.035 V, ?G298 = - 29.18 kJ/g-atom ??). Silver with thiosulfate forms two strong complexes: [AgS203]- and [Ag(S203)2]3-. ?G0 = -1027 kJ/mol. The complex [AgS203]- is less stable: ?G0 = 486 kJ/mol. It should be noted that despite the high stability of gold complexes, the sodium thiosulfate may decompose to sulfite and elemental sulfur during the process, especially when heating. Gold is slightly soluble in the sodium sulfite solution, however it forms the strong complex [Au(SO3)2]3-. Depending on the concentration of free S2O32-ions, silver with sodium sulfite forms three complexes: [AgSO3]-, [Ag(SO3)2]3- and [Ag(SO3)3]5-. The dissolution speed of gold in sodium sulfite solution may be in the same range as it is during cyanidation. In this case, a practical application of sulfite process can be also used, especially for the products containing free elemental sulfur. In conclusion, sulfite-thiosulfate gold lixiviants can be used for concentrates after pressure oxidation of the cakes.

Sep 13, 2010

By I M. Platten, S C. Dominy

The evaluation of historical goldfields is currently topical, reflecting a high gold price, improvements in knowledge and technology. and lack of greenfield sites. Many goldfields comprise narrow gold-quartz veins which are structurally complex with an irregular distribution of gold; variable geometry and architecture; and display late deformational effects. The study of historical mine records can be an important tool during early and advanced project evaluation since it contributes to understanding the orebody, exploration target size and setting expectations. The historic Engineer Mine property is located 32 km west of Atlin, British Columbia on the east side of Tagish Lake. The economically important Engineer and Double Decker veins belong to a NNE-SSW vein set. These are narrow, commonly <2 m dilational veins with a minor sinistral strike component and of an epithermal type. Documented ore production between 1910 - 1952 is recorded as approximately 14 263 t at 39.4 g/t Au and 19.5 g/t Ag (for 18 000 oz Au and 8950 oz Ag). The underground workings consist of about 5500 m of tunnels, shafts, raises and stopes over eight levels. The mine is currently being re-evaluated. In 2011, an Inferred Mineral Resource of 41 000 t at 19 g/t Au for 25 000 oz Au (at a 5 g/t Au cut-off) was defined from historical data supported by modern drilling into the Engineer and Double Decker veins. A surface and underground bulk sampling and milling program was undertaken in 2011.CITATION:Dominy, S C and Platten, I M, 2012. Application of historical data to estimate a mineral resource at the Engineer gold mine, British Columbia, Canada, in Proceedings Narrow Vein Mining 2012 , pp 81-100 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By Kuzmitch O, Morozov A

The main direction in the mechanisation in the mines of the Donbas and the USSR is long-face technology with complexes on the base of hydraulic supports. On the base of the 30 year old experience of exploitation of the coal clearing systems the serious data about the behaviour of the contained rock, display of underground pressure 'on longwalls and preparatory workings have been accumulated. Exploitation works in mines of the USSR are carried out at different depths: from 1000m to 1200m. There are 26 mines in Donbas, which exceed the depth of 1000m. It is the mines of Donbas, where is a rich experience of the exploitation of coal seams in various conditions. Besides, there are wide variations on the factors of the extraction thickness, depth of seam, angle of dip, occurrence of gas dynamics and others. In many scientific establishments, and in Donetsk Polytechnical Institute also, there are scientific research/results, which can be of interest for the coal mining countries.The volume of coal mining from longwall system-mechanised walls in Donbas became stable at the end of the 70s at level of 70 percent. All the efforts to increase this level have not given any notable results, not saying about the technical-economical data, which gradually deteriorate. It shows that positive progress in using the technology for the long walls is over and it is necessary to find new ways of mechanisation of coal winning.

Jan 1, 1991

Gold was discovered at Waihi in 1878. In 1987 the modern Martha Mine opened in the middle of the town of Waihi. Newmont Waihi Gold as the current licence holder has been operating the mine since 2000. The current open pit was scheduled to stop production in mid 2006. An underground mine is currently being developed to the east of the town.   In 2001 serious subsidence issues from historical underground mine workings outside the mining licence and the forecast closure of the open pit acted as a catalyst for the development of new communication initiatives.   In this context Newmont Waihi Gold and the Hauraki District Council initiated a community consultation process with the people of Waihi. The Waihi Community Consultation Committee (WCCC) was established in May 2003. After an initial brief to act as a forum for community participation in closure and rehabilitation of the Martha Mine, the group quickly took on a much more proactive role working towards the long-term social, environmental, cultural, economic and spiritual sustainability of Waihi.   In the course of over three years of meetings all groups represented on the committee have presented their views, developed ideas and established an organisational structure to bring those ideas to fruition. The challenge now is to work together to consolidate likely options, seek sources of funding, produce business proposals and implement the plan for the future of Waihi.   This paper backgrounds the experience to date and describes the outcomes of the process. For more detail on process considerations this paper should be read in conjunction with Part C by process facilitators, T Clark and S Stewart. For more detail on progress towards the groupÆs goals and future possibilities, this paper should be read in conjunction with Part B by Vision Waihi Trust CEO, E Morrow.

Jan 1, 2006

By R G. Barker

The NZ Minerals Industry Association has continued to advance the interests of the minerals sector through leading the establishment of a Minerals Industry Advisory Committee, and the preparation of a technology strategy with funding assistance from the Foundation for Research, Science and Technology. The current moves mirror those of more than 30 years ago when a government initiative led to a resurgence of exploration through amending the mining legislation, redirecting Government research priorities and tax changes. The economic and political and commercial environment in 2001 is very different from that of the 1960s and success of these new initiatives depends on the continuing support and involvement of all sectors of the minerals industry, and building an improved relationship with the Government and the public.

Jan 1, 2001

Thermal method of diagnostic as a nondestructive monitoring is based on data logging of infrared radiation from heated surface or from the associated thermal field. Monitoring of gearcases and motors hidden faults, such as, bearing degradation (deep-seated wears and tears, fretting wear, spalling and jamming solids of revolution) is closely related to high variations in temperature. The use of portable thermal imaging devices provides considerable advantages due to: easy remote access to the unit under test even when it is operating; minimum time required to obtain information and an opportunity for a real-time diagnosis of the tested subject's condition.

Dec 6, 2010

By D J. Brake

There has been a strong trend over the past decade in hard rock mines towards the use of very high powered auxiliary (or secondary) fans; in many mines, the installed power for the secondary ventilation system now exceeds that of the primary ventilation system. This also reflects the trend to use two-stage auxiliary fans pushing air into a single ‘trunk’ duct that in turn splits into multiple branches with multiple outlets feeding multiple workplaces. This often produces a poor result in terms of face flows due to the high resistance, high leakage and badly managed duct outlets, as well as high fan capital and operating (power) costs, which in turn also results in a higher cost for the underground power reticulation/distribution systems. This paper explores the reasons why this trend exists and what ventilation practitioners can do to utilise less expensive systems that simultaneously deliver better workplace conditions. It includes a case study.CITATION:Brake, D J, 2017. Auxiliary ventilation design – why and how mines waste so much power on inferior systems, in Proceedings Australian Mine Vent Conference 2017, pp 27–34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By A S. Derrington

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

Jul 1, 2013

The Framework Convention on Climate Change (FCCC) places serious obligations on New Zealand as a signatory nation. This paper examines the nature of the FCCC, New Zealand 's proposed policy response, and the.implications for the minerals industry.

Jan 1, 1994

By J C. Carlile

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) mineralisation. 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 R G. Richards

The Australian glass sand industry produces some 2.8 million tonnes per annum of silica sand, of which about 2.0 million tonnes are exported and the rest is for the domestic market. Approximate production rates for each Australian state are listed. The variety of processing methods used in the currently exploited deposits reflects the size, location, and characteristics of the various deposits and the requirement of the end market/s. The industry uses to a large extent equipment developed for the separation of mineral sands, particularly as it applies to low grade heavy mineral deposits, where low cost, high capacity and metallurgically efficient equipment has proved eminently suitable for the production of the low value glass sands. The requirements of the domestic market, as well as those of the present and potential export markets are discussed covering quality requirements, distribution channels and other factors critical to success.

Jan 1, 1990

The Martha deposit is an economic giant epithermal gold deposit, with mined and unmined resources of more than 218 000 kg (7 Moz) Au. The Au-Ag, base metal sulphide-bearing quartz lodes in the Martha deposit form an extensive braided pattern within hydrothermally altered andesite wall rock. There are five main quartz lodes: 1.      Martha, 2.      Welcome, 3.      Edward, 4.      Empire, and 5.      Royal.   Information from historic mine plans and reports has been used to determine the depth distribution of economic ore within the Martha deposit. Economic ore (average of 10 g/t Au) in the Martha underground mine was at a maximum width and strike length between a vertical depth of 160 and 350 m. Below this depth the quartz-sulphide lodes continue, but the grade declined to sub-economic grades (< 4g/t Au) at about 575 m depth and economic ore shoots were localised, mainly on the hangingwall side of the lodes. Samples from exploration drill holes indicate that this decrease is associated with a depth zonation from electrum-bearing Zn-Pb-Cu-Ag sulphide ore (average 10 g/t Au) to sub-economic (< 2 g/t Au) electrum-poor Zn-Pb sulphide mineralisation.

Jan 1, 2006

Flotation of Composite Synthetic Particles

Sep 13, 2010