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By R R. Lovel, G J. Sparrow

Currently there are large reserves of good quality iron ore near to existing infrastructure that are not being developed because the phosphorous levels are above acceptable market specifications. Since the high phosphorous content is considered to be mainly associated with the goethite fractions of the ore, attempts were made to leach the phosphorous from the ore after a heat treatment to dehydroxylate the goethite. Heating the ore and leaching with 40 g/L NaOH lowered the phosphorous levels from 0.145 wt per cent P to 0.075 wt per cent P or lower, but a heating temperature over 800¦C was required to achieve this reduction in phosphorous levels. However, when sodium hydroxide was added to the iron ore before the heat treatment, similar phosphorous removal was achieved with a heating temperature of 300 - 350¦C. It was considered that dehydroxylation of the goethite in the presence of the hydroxide makes the phosphorous available for removal with a water leach. As well, 50 per cent of the silica and 60 per cent of the alumina in the ore were also removed in the leach, but some sodium remained in the leach product. Further work is required to remove the residual sodium to produce a marketable product.

Jan 1, 2009

By Parrington PJ, Bailey A

Serious exploration for carbonate-hosted lead/zinc deposits in the Pillara district commenced in 1971 when Trend Exploration acquired exploration tenements covering stream sediment anomalies in the Limestone Billy Hills area. Shell Minerals managed the project from 1974 to 1976, and BHP Minerals Limited assumed management during 1976. Carbonate-hosted 'Mississippi-Valley- type' Pb-Zn deposits most commonly occur in Palaeozoic shallow marine carbonate complexes. At Pillara upper Devonian (Givetian/Frasnian) reef complexes are preserved on the flanks of Precambrian basement 'highs'. Within platform and atoll facies limestones sphalerite-galena- marcasite-calcite mineralisation occurs as disseminations, veins and breccia matrix, mostly associated with fractures and fault zones. Early exploration concentrated on detailed surface geochemistry and IP geophysical surveys, with geological mapping and shallow target percussion and diamond drilling. Results were discouraging and did not indicate potential for a shallow base metal resource. During 1976-77 BHP adopted a grid diamond drilling exploration technique and commenced testing an area of approximately 50 sq. km, initially using an 800 m square grid. In 1978 high grade mineralisation was intersected in an area subsequently named Blendevale. This was in the seventh diamond drill hole in the 800 m grid drilling programme, and to date more than 400 holes have been cored in the Pillara area. Detailed drilling at Blendevale has defined a number of mineralised breccia zones within an area of 2.4 km x 0.5 km, at depths of 100 m to 600 m below surface. The breccia bodies are associated with a series of north-south trending normal fault zones, forming a graben structure. The mineralisation occurs as breccia matrix surrounding unaltered limestone clasts, as veins filling steep fracture zones, and as

Jan 1, 1986

By M Nehring, M Kizil, P Knights, A Mousavi, F Sotoudeh

A cut-off grade is used to distinguish an economically viable block of ore from non-economical ones in mining operations. In order to obtain a high Net Present Value (NPV), a strategic and precise determination of cut-off grades (mill feed/marginal, marginal/waste) is required. In recent years, the significant depletion of feed grades and increasing mining operating costs have affected the viability of new and existing mining operations. Hence, the introduction of a pre-concentration system to process ore before sending it the main processing plant has gained increasing attention for its potential improvements in resource exploitation processes, mineral processing, energy consumption and environmental impacts. The primary potential advantage of implementing a pre-concentration system is the improvement of resource utilisation and increased reserves as a result of a reduction in cut-off grade. The objective of this paper is to present a new cut-off grade method, which can be used in the presence of a pre-concentration system for underground metalliferous mining operations. The results of this study illustrate the potential economic benefits of using a pre-concertation system prior to a mineral processing operation as a result of the reduced cut-off grade and increased NPV.

Nov 10, 2020

By C MacRae, N Wilson

CSIRO Minerals has recently developed an electron microprobe (EMP) based imaging (or mapping) method for characterising ilmenite concentrates. The method requires an electron microprobe analyser to collect elemental X-ray maps which are then processed via an in-house developed software module (CHIMAGE). The type of information readily available from EMP mapping includes; primary phase identification, modal analysis of phases, chemical analysis of individual phases, textural information (eg the alteration stages in the formation of leucoxene or pseudorutile from primary ilmenite and the development of macro-porosity), and the identification of coatings or pore-fill material. All of these parameters will impact on the choice of future downstream processing options considered for any particular ilmenite concentrate. The method has been demonstrated to be a sensitive analytical tool for assessing the distribution of aluminosilicate minor impurities in ilmenite feedstocks from the West Coast of Australia and also for characterising the complex chrome-spinel gangue phases common in East Coast ilmenite concentrates from the Murray Basin.

Jan 1, 2001

The Bureau of Mineral Resources has been engaged in regional geological and geophysical field work in the Alligator River and Cobourg Peninsula area since 1971, following the discovery of major uranium deposits. Geophysical work commenced with a regional airborne magnetic and radiometric survey which was followed up by some helicopter and ground work in August 1973. The interpretation of the earlier radiometric work is presented in conjunction with the results obtained from the follow-up work. Analyses of 100 outcrop and drill core samples collected have provided basic information on the physical properties and concentrations of uranium and thorium in various rock types. The uranium determinations were made by X-ray fluorescence and delayed neutron analysis, good agreement being obtained between the two methods. X-ray fluorescence was the main analytical technique used because of its ability to produce both uranium and thorium determinations.

Jan 1, 1975

By Savage E. N

The porphyry copper minerals of Melanesia occur within a host of narrow veinlets in predominantly quartz diorite stocks or as contact metasomatic masses in skarns adjacent to the intrusion. Some 90 per cent of the constituent minerals comprise pyrite or marcasite, chalcopyrite, and magnetite with the remainder mainly bornite and hematite with accessory rutile and chalcocite together with several trace minerals. Gold is found mainly as inclusions in chalcopyrite, and minor molybdenite occurs likewise.Of particular significance is the persistent occurrence of accessory rutile of hydrothermal origin intimately intergrown with chalcopyrite. The rutile occurs relatively late in the hydrothermal sequence and upon weathering of the deposit may be released on a cumulative basis possibly in sufficient amounts to constitute a particulate pathfinder mineral which may aid in prospecting.Rutile is present in all the Melanesian occurrences studied and is also prominent in several American deposits.The porphyry copper mineralogy is characterized by the presence of accessory hydrothermal rutile intergrown with chalcopyrite.

Jan 1, 1975

By M L. Cramer, N P. Wines

"On 9 February 2014, bushfire embers landing on exposed coal in a disused pit at the Hazelwood mine in Victoria’s Latrobe Valley ignited a coal fire that burned for 45 days. The fire was the largest and longest burning mine fire to occur in the Latrobe Valley (Hazelwood Mine Fire Board of Inquiry, 2016). Two Victorian Government Boards of Inquiry have been held into the Hazelwood mine fire. The most recent, in 2015, included consideration of the regulation and implementation of rehabilitation practice at Hazelwood and the other two brown coalmines of the Latrobe Valley (Loy Yang and Yallourn; Government Gazette, 2015).The 2015 Hazelwood Mine Fire Board of Inquiry commissioned Accent Environmental Pty Ltd (Accent) to undertake a review of the financial mechanisms for mine rehabilitation and closure adopted in Australia and overseas (Accent, 2015). Specifically, Accent was engaged to identify ‘any practical, sustainable, efficient and effective alternative mechanisms to ensure rehabilitation of the mines as required by the [Victorian] Mineral Resources (Sustainable Development) Act 1990’ in accordance with Terms of Reference 10 (c) (Government Gazette, 2015).The review by Accent included consideration of a range of financial instruments such as bank guarantees, trust funds and insurance. It considered a number of financial assurance systems in operation in Australia, New Zealand, the European Union, Canada and the United States. These systems included: full and discount financial assurance systems predefined liability proportion systems pooled fund systems the use of post-closure financial mechanisms such as trust funds (Accent, 2015).What lessons can be learnt from other jurisdictions? Are there financial mechanisms already in place that could allow the Victorian Government and the mine operators to manage the risk of rehabilitation default3, lower rehabilitation liability, attain site rehabilitation objectives and allow eventual site relinquishment?CITATION:Cramer, M L and Wines, N P, 2016. Global lessons for a local problem – rehabilitation bonds and Victoria’s Latrobe Valley coalmines, in Proceedings Life-of-Mine 2016 Conference , pp 24–27 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 28, 2016

This study is to compare reinforcement of rebar and spiral bolts using laboratory pull-out test. For this purpose, the pull-out test was performed in laboratory for a curing period of 7- and 28-days. Based on the results of the laboratory pull-out test, the pull-out load of two support members rapidly increased with displacement until the breakpoint and then gently increased with displacement. The maximum pull-out load of spiral bolt was larger than that of rebar bolt. This implies that a spiral bolt is more stable than a rebar bolt for securing the stability of a ground or rock mass when a support was installed in a ground or rock mass under the same condition. In addition, the maximum external pressure of two support members increased with pull-out load and with displacement and the distribution of external pressure was commonly larger at the upper part than at the lower part of specimen. This indicates that the bond failure location by pull-out load should be mainly occurred at the surface portion of specimen. In conclusion, the reinforcing effect of a support depends on a curing period and a type of support member, and reinforcement of a spiral bolt is more effective than that of a rebar bolt.

Dec 6, 2010

By Leahey T. A

The variability of gold mineralization in the Warrego Gold Pod is described by classical statistical techniques using sample distrib- utions and analysis of variance; and by the use of geostatistical variogram analysis to define the spatial variability and anisotropy of the mineralization. Comparison is made between declared mine production from the Nineteen Stope and a series of ore reserve estimates derived by manual, numerical and disjunctive kriging methods.

Jan 1, 1979

Since the 1950's drilling has been rapidly mechanised. First from hand held drills with air legs to pneumatic jumbos, then to more effective hydraulic jumbos. Development of underground drilling equipment naturally could not have stopped here. Hydraulic drilling saw an improvement in drilling capacity and efficiency after the introduction of second generation drifters in the early 1980's. Also in the early 1980's a few equipment suppliers started to study how to improve the efficiency in operating the rigs. The first computerised rigs for tunnelling were delivered to work sites in mid 1980's. At the same time a few computerised longhole drills started drilling in mines.

Jan 1, 1988

I The South Platform of the Gippsland Basin is an extensive area of shallow basement covered by a relatively-thin Late Mesozoic-Cainozoic section. Although the sporadic exploration to-date has not resulted in any hydrocarbon discoveries, the area is under-explored and its taste potential has not yet been fully evaluated. The best potential appears to be in areas underlain by the Golden Beach Megasequence where structures are mainly related to basement fault blocks.

Jan 1, 1992

By Ramani R. V

There are many important physical phenomena in mine ventilation which involve transient mass and heat transfer processes. These processes have been modeled using differential equations often solved with close form solution. Within the last two decades, many numerical schemes have been devised to solve these mass-transfer problems. Much of this effort has focused on variants of the finite element and finite difference methods. In this paper, the solution of mass transfer models in mine ventilation by finite difference technique is discussed. Specifically, the computational effort and the accuracy of the solution are presented.

Jan 1, 1988

By Heath E, van Calsteren P, Turner S, McDermott F

U-Th isotope studies of recent volcanic rocks may be used to evaluate the depths and rates of melt generation beneath mid- ocean ridges and ocean islands. Island arc rocks exhibit a similar range in Th isotopes to that seen in both MORB and OIB, but while those with high (230Th/232Th) tend to have excess 238U, many of those with low (230Th/232Th) are in isotope equilibrium. The excess 238U is attributed to the preferential mobilisation of U in hydrous fluids from the subducted slab within the last 100,000 years, whereas the low Th isotope ratios in the higher-K arcs are primarily due to the introduction of subducted sediment. Preliminary results from mineral separates from lavas on Soufriere on the island of St. Vincent indicate that some of the minerals crystallised up to 50,000 years prior to eruption.

Jan 1, 1995

By M J. Nugus

The structural models developed by exploration and mining geologists are most commonly concerned with the ‘main structures’ or key constituents that pertain to the associated mineralisation. To this end, it is recognised that the geological and exploration models, which are developed, are essentially ‘fit for task’ and the scale-related variances are not always realised at an early stage. In fact, in many cases anomalous intercepts along different trends and of variable apparent continuity have often been neglected as ‘back scatter’ and not important. Recognition of the importance of subordinate structures as mineralising hosts suggests that additional opportunities exist outside the primary and main structures. History shows that opportunities are often not realised where gold is hosted in orientations not parallel to the predominant trend of the schistosity, main fault or shear zone.Another reason for the importance of subordinate structures can be understood from their roles in a percolation network. Subordinate structures can access the large fluid fluxes provided by backbone elements, but, as dangling elements, they provide greater opportunities for gold precipitation mechanisms and hence may constitute essential parts of the resource. Therefore, the role, understanding and consideration of the smaller-scale and orthogonal structures should be considered during all facets of exploration, resource development, delineation and mining.

Aug 22, 2011

British Coal's Selby Complex is the newest producing mine in the United Kingdom. The reasons behind its origins, planning and design are explained. Some detail is given of equipment used, with the emphasis being placed on the unique features of its layout. The entire project has been planned and constructed over many years and the design has consequently changed, principally in response to the geology of the coalfield and improving technology. In spite of many totally unexpected difficulties, the mine, which is not yet in full production, has the highest productivity in the United Kingdom.

Jan 1, 1991

By Jarvensivu M, Ylinen R, Jamsa-Jounela S-L

The paper presents a new integrated system for control of concentration processes. The system is based on cluster-based modelling taking the ore quality into account and a new on-line particle size analyser capable also for reliable measuring of particle size distribution of concentrate. A metallurgical precontrol audit was performed at the Hitura concentrator in order to design the control strategy of the integrated grinding and flotation control. A new analyser PSI-200, was used to the measurement and control of the distribution of nickel in the total particle size range. An expert control system using the cluster model together with a new control strategy for decision of necessary control actions is outlined. The method has been tested to real data from mineral processes. The results are in good correspondence with empirical process knowledge. KEYWORDS: Cluster analysis, expert control, flotation control, mineral processes, modelling, particle size.

Jan 1, 1993

By Sans H

The geostatistical Discrete Gaussian (DG) model is demonstrated to be capable of providing an effective means of implementing change of support for Enterprise-style mineralisation and thus providing reliable global recoverable resource estimates. At Enterprise, sample grade distribution proves to be highly positively skewed, therefore significant deskewing of the histogram and reduction of variance occurs when going from sample to block support. The DG model was experimentally tested in'the Southern Primary Zone (SPZ) at Enterprise, where high anisotropy ratios and pronounced short range structures are observed in variograms. The experimental test was run for a change of support for which the variance reduction was. approximately 60 per cent. This reduction is similar to that predicted by Krige's Relationship ('the volume-variance relationship') for the practical situation of a change of support from 5 m vertical blasthole samples to 3 m x 8 m x 5 m selective mining unit (SMU) blocks. The DG model was found to correctly predict the grade tonnage relationships for a wide range of cut off grades. The experimental test indicated that, given a representative histogram and variogram, the DG change of support provides a computationally efficient and practical means of reliably assessing global mineable resources at the early stages of a mining project. Further, it allows a range of selectivity strategies to be meaningfully and comparatively considered prior to mining.

Jan 1, 1995

By Kirkhouse C. B

Soon after the Broken Hill Limited started operations at their Iron and Steel Works at Newcastle, NSW, it was found necessary to install a mill for rolling small merchant bars, rounds, etc.An arrangement of the first mill laid down is shown on Plate 1., Fig. 1. This mill commenced operations on the 18th July, 1917.The feed for this mill was rolled in the existing 18-in. mill and sheared to the lengths required before being delivered to the billet storage yard. The billet storage yard is 90 ft. span, and is served by one 10-ton electric overhead travelling crane. Billets were placed on the billet bed preparatory to being charged into the heating furnace.The heating furnace was of the continuous recuperative with end discharge and had a hearth 40 ft. long by 10 ft. wide. The billets were pushed through the furnace by means of two hydraulic rams, which could either act together and push one row of billets, or act singly and push two rows of billets. This furnace was fired by producer gas from the producers shown on Plate I., Fig. l.The gas was conveyed to the furnace by means of a brick underground flue.

Jan 1, 1935

By Morley I. W

In the year 1926, Edie Creek, in the Morobe District of the Mandated Territory of New Guinea, saw the greatest gold rush of recent years. Situated 35 miles inland from the coast, and at an altitude of over 6000 feet, Edie Creek presented to the original prospectors a wet, jungle-clad uninhabited, and inhospitable region. There were no roads; and the only means of approach from the equally inhospitable coast was by an eight to ten days' tramp through coastal swamps and gorge-scarred mountains. All food supplies and equipment had to be carried on the backs of "kanakas," and in many cases through country occupied by hostile natives.Since the first discovery of payable gold at Edie Creek, mining on the Morobe Goldfield has shown remarkable progress, and in spite of the tremendous natural difficulties, the field today ranks as one of the most important in Australasia.Aeroplanes, more than any other factor, have been responsible for this rapid development. They provide the only means of transport from the coast, and at present serve the needs of over 600 Europeans and 3000 indentured native labourers engaged in the industry.

Jan 1, 1933

By Taylor GP

Mt Kasi in Fiji is a high sulphidation style of gold deposit exposed at a high crustal level. Individual alteration centres are localised at the intersection of cross structures within a through-going structural corridor, the Mt Kasi Fault System. A two stage alteration/ mineralisation model suggests that much of the high sulphidation alteration is derived from the initial rapidly moving gas-rich portion of the hydrothermal fluid. The gradual cooling and neut-ralisation of hot acid fluids by mixing with oxygenated ground waters forms the characteristic zoned alteration assem-blages which grade from cores of residual silica through silica-alunite to peripheral clays. The liquid-dominated phase of the hydrothermal fluid brecciates the competent, altered rocks and deposits sulphide mineralise-ation within the breccia matrix. High gold grades occur in the matrix-rich breccias and decline from the hydro-thermal fluid upflow to outflow zones.CSAMT (controlled-source audio magneto-tellurics) geophysics has been used to define the geometry of the alteration centres while strike slip movement on the major structures accounts for the dilational structural environment in which the ore hosting breccias form.

Jan 1, 1994