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By A Goldstone, M Fitzpatrick

Contemporary mine wastewater flows are subject to stringent water quality standards before discharge to local waterways. Strict criteria are often applied as a result of fears of extensive acid mine drainage; a feature of the many abandoned mine adits around the Coromandel, Central Otago, and the West Coast. In most cases the USEPA water quality criteria have been used to set treated wastewater discharge water quality standards. In future it is possible that the recently published ANZECC water quality criteria guidelines will be used for this purpose. The ANZECC guidelines also provide for the establishment of discharge criteria at specific sites, rather than accept the trigger values. The use of site-specific criteria for treated wastewater mine discharges was pioneered at the Golden Cross gold mine, near Waihi, in the late 1980s. The procedure used to derive water quality criteria was based on USEPA guidelines. In developing the Golden Cross criteria, only species that occur, or are similar to those that occur in the Waitekauri River were used. The mine commenced discharge of treated wastewater in 1991, and macroinvertebrate communities in the vicinity of the discharge point have been regularly monitored twice a year for the past 12 years. Despite fluctuations in community composition and abundance over that period, no permanent significant changes in the macroinvertebrate communities occurred between sites above and below the treated wastewater discharge. The success of the site-specific criteria at Golden Cross has shown how the application of this methodology can result in the protection of aquatic life while allowing for the discharge of treated mine wastewater.

Jan 1, 2003

In both exploration and mining, the laboratory is often seen as a cost rather than a profit centre. The aim in most mining companies is to increase profits by reducing costs, so the budget for the laboratory is under constant pressure.There is another option; to see the laboratory as the brain of the operation. By lifting the status of the laboratory and treating it as a profit centre, mine costs may be reduced in other ways, e.g. reduction in milling costs. This change of status will require investing more capital in better equipment, more training for employees and more employees to carry out project research.There are many examples of major costs being incurred because of inadequate laboratory work. Conversely, by spending more money on laboratories and their activities, overall costs can be reduced or profits enhanced.

Jan 1, 2002

By Nickelsen J, Theisen KG, Hansen PH

The use of stationary calciners in the processing of aluminium hydroxide has emphas- ized the importance of Bayer hydrate properties with respect to particle breakdown during calcination and subsequent treatment. Test results from calcination of several Bayer hydrates to sandy alumina in the FLS Gas Suspension Calciner (GSC) were obtained in a 250 kg/h pilot plant unit. Particle breakdown during calcination was influenced by content of solid sodium oxalate, trapped in the hydrate particles and operating gas velocities. Owing to the design and operational principles of the GSC it is possible to reduce particle breakdown to at least the same as what is found in long rotary kilns. Other major advantages reviewed are obtained through simplifications in plant design and operation, pointing to low specific power and heat consumption, and generally low production costs, thereby providing an attractive alternative to fluid-bed calciners.

Jan 1, 1981

By M Lellis

During the last decades, maintenance has changed from an ordinary repair activity to a complex function that plays an essential role contributing for the companyÆs results. The increasing level of complexity of modern equipment motivates maintenance personnel to improve both techniques, and management systems, in order to face the new challenges. Managing properly those modern means of production requires knowledge of methods and planning systems, controlling and performing maintenance tasks, in such a way that two objectives are achieved at the same time: system efficiency and cost-effectiveness. This paper shows CVRDÆs experience on evolving and implementing a model to plan and manage maintenance activities in order to achieve a higher level of performance on its operations.

Jan 1, 2003

By Kandemir H, Stafford G

The Croydon Gold Mine is located in northwest Queensland and is a joint venture between Central Coast Exploration N.L. and Pancontinental Mining Ltd. The mining operation commenced in 1987 and consists of satellite open pit mines feeding a central Carbon-In-Pulp gold Treatment Plant. The gold mineralisation is hosted by quartz veins within the Croydon Volcanic Group and the Esmeralda Granite, a cogenetic igneous suite of Middle Proterozoic age. The mineralisation comprises gold and silver with associated basemetals. The gold and silver electrum occurs as extremely fine free grains. The gold distribution is heterogenous occuring across the full vein width, or restricted to the footwall or hangingwall. The average mineral resource grade is 3.5 g/t. The deposits are all hard rock and mining is carried out by drill and blast technique. All mining activity is carried out by a mining contractor. Mining is by a selective mining method which entails the drilling, blasting and extraction of the hangingwall waste prior to orebody extraction.

Jan 1, 1989

The paper re-visits an old and proven concept of winzing, a method widely used in the past to gather exploration data for accurate definition of the orebody. It is proposed to use a mobile Supersucker (a giant vacuum cleaner also known as vacuum lift), to carry out winzing activities underground. A brief description of conventional underground winzing used in the past is provided, together with a discussion on other underground bulk exploration methods used in Australia to date. Historical background, principles of the proposed system, Supersucker construction details and productivities, and benefits and advantages of the proposed system in comparison with other exploration methods, are outlined. Other relevant applications of the mobile Supersucker, including surface winzing, are also briefly discussed in the paper. With a view of using the mobile Supersucker to recover all broken ore stocks underground, included are also results of floor sampling conducted recently in the in-stope decline excavated in a coarse gold type, high-grade orebody.

Jan 1, 2002

ADDRESS BY THE PRESIDENT OF THE INSTITUTE (MR. J. G. SYMONS) IN PRESENTING THE CERTIFICATE TO ROBERT COLVILLE BRADSHAW, O.B.E.Today it is my privilege and pleasure to introduce to you, Robert Colville Bradshaw. O.B.E., the third New Zealander to be honoured with Honorary Membership of The Institute. Sir William Hudson and Mr. C. H. Benney were the others.Mr. Bradshaw has been an Affiliate Member of The Institute since the formation of the New Zealand Branch in 1966. Like his friend Matt Benney. Bob Bradshaw is an accountant by training. Last June he retired as senior partner of the firm of chartered accountants, now known as Wilkinson Wilberfoss, with which he served from January 1929.Mr. Bradshaw grew up in New Zealand attending the Terrace School in Wellington, the New Plymouth Boys' High School where he was a boarder, and completing a Bachelor of Commerce at the university now known as the Victoria University of Wellington. He is an elected Fellow of the New Zealand Society of Accountants and an Associate of the United Kingdom Institute of Cost and Works Accountants.

Jan 1, 1977

By E Werner, B R. Leavitt

The chemistry of acidic mine drainage discharging from flooded coal mines is commonly reported to improve with time after flooding. This investigation describes a 18-year dataset of post-flooding water chemistry for a below-drainage underground coal mine within the northern Pittsburgh coal basin (Pennsylvania, USA). The Montour mine is a 5650-hectare below-drainage coal mine of maximum 260 metres depth. Montour was closed in 1980 and flooded to within 38 metres of land surface within 4.8 years. Pumping averaging 210 L/s was then employed to maintain water levels at this elevation. The flooded proportion of the mine (by volume) at full flooding was 56 per cent. The shaft where water was pumped from Montour for water control is located about 70 per cent of the distance between the mine water table and the back of the mine ù that is, it is close to the back of the mine. The residence time (total water volume at flooding divided by pumping rate for control) is estimated at 5.6 years. Time series of chemical analyses show three phases of chemical behavior in post-flooding discharge. In Phase I (zero to two years after flooding), iron concentrations were high and reached their maximum (1100 mg/L). In Phase II (two to four years after flooding), a transition was begun to alkaline conditions, with decline in iron and other solutes. In Phase III (>4 years), net alkaline conditions began, with iron concentrations declining exponentially to 50 per cent of mined volume. This attainment of net alkalinity in this case may have also depended on abundant calcite in overburden extended up to 30 m above the mine floor.

Jan 1, 2003

The processes most likely to be adopted for beneficiating ores or concentrator streams containing a large proportion of particles finer than 10 um are froth flotation, selective flocculation, wet magnetic separation and selective leaching. Flotation will be made more efficient for very fine particles if ways can be found to selectively flocculate the valuable mineral beforehand (floc-flotation), to produce smaller bubbles and to reduce entrainment of ultrafine gangue. Schemes for selective flocculation have proved difficult to implement because of the delicate balance between surface forces (electrostatic, dispersion, hydrophobic) and hydrodynamic forces, that determines flocculation, and the changes which occur to particle surfaces through hydrolysis, oxidation-reduction and cross-contamination between minerals in aqueous suspensions. The search for a better understanding of selective adsorption of flotation collectors and flocculants continues and will be particularly important for the practical success of selective flocculation and selective magnetic coating.

Jan 1, 1986

By Sloan GJ, Lysnar RD

Since the of Bergstrand's Geo-dimeter in 1946, and Wadley's Tellurometer in 1956, there have been numerous Electromagnetic Distance Measurement (EDM) instruments produced throughout the world by a variety of companies.This form of measurement has not merely replaced other methods of measurement, but has caused considerable change of emphasis in survey techniques. Major control surveys are now being accomplished using trilateration instead of triangulation. The surveying of open cuts or engineering work may be done in a fraction of the time and, in the majority of cases, to a greater degree of accuracy than with older methods.It is surprising that with this new tech-nology and development of EDM equipment which is compact, easy to use and no longer so expen-sive, no advance has been made in underground surveying. If we look at equipment being used by the majority of mining companies, we see that there have been very few changes since the Second World War. Very little research has been carried out to enable the surveyor to do his work more easily in conditions which, at the very least. are hazardous.

Jan 1, 1984

Probabilistic seismic hazard analyses (PSHA) have now gained wide acceptance in the development of design criteria for major projects. When used with regional criteria the procedures have also allowed the preparation of more rational seismic zoning maps. Seismic zoning maps using various levels of results from PSHA studies around the Pacific Rim now include Canada, Indonesia, New Zealand and the United States. Some Pacific Rim countries such as Chile where the seismic exposure is dominated by subduction events have no subdivision into separate zones.Approaches to risk based zoning are being considered in several Pacific Rim countries including Australia. Australian studies must face problems similar to parts of the Eastern United States where seismic activity is low with irregular and infrequent occurrences of moderately large earthquakes. The perception of the seismic exposure by both regulatory agencies and the public at large is different when considering areas of low seismicity. There is therefore a need to make different interpretations of the results of PSHA studies in these areas of low seismicity. The aim of this paper is to explore some of these differences by comparing the results from two site specific studies from areas with widely differing seismic activity rates.

Jan 1, 1990

By F Melcher, M Wiedicke, A Wittenberg

Ferromanganese nodules form a specific category of widespread marine mineral deposits. The tremendous increase in metal prices during the last decade raised new economic interest in their exploration. The German Federal Institute for Geosciences and Natural Resources (BGR), which had been engaged in nodule research in the 1970s and 1980s, renewed its activities on this subject based on an exploration contract with the International Seabed Authority, signed in 2006. BGRÆs licence area û comprising 75 000 km2 û is located between the Clarion and the Clipperton Fracture Zones. In this so-called nodule belt north of the equator the sea floor reaches water depths of >4000 m. About 900 million tonnes of manganese nodules are expected there. In this study the fine-scale distribution of important elements in manganese nodules and crusts from a variety of locations was investigated. Besides 11 samples from the RV SONNE cruise SO-25, numerous samples from additional locations were included in this study for comparison. In general, the sample suite includes two genetic types of precipitates, manganese nodules and Co-rich crusts. A detailed characterisation of the distribution of major, minor and important trace elements in manganese nodules based on in situ microenergy dispersive X-ray fluorescence (¦-EDXRF) analysis is presented here. The data are compared with bulk major, minor and trace element data as well as with quantitative electron probe microanalysis (EMPA) data sets. The element distribution maps and profiles produced by ¦-EDXRF analysis with short or extended (in case of profiles) counting times, allow precise selection of æregions of interestÆ for further detailed investigation using high spatial resolution techniques (eg scanning electron microscope (SEM)-EDAX; laser ablation-inductively coupled plasma mass spectroscopy (LA-ICPMS); isotopic studies).

Jan 1, 2008

The Western New South Wales Electric Power Proprietary Limited is the central generating authority for distribution of power to the majority of the Broken Hill mining companies and the Broken Hill Water Board. This station supplies the whole of the power to North Broken Hill Ltd and Broken Hill South Ltd. It also supplies, power to the Southern Power Corporation for distribution to the Zinc Corporation Ltd. The Southern Power Corporation has a generating station which is tied in with the central generating authority.

Jan 1, 1957

By Duniam P

Sequencing of large underground firings is a critical aspect of blast performance. Using theory developed in open cut operations, where blast results are easier to quantify, a new technique for sequencing underground mass blasts has been developed. The basis for the technique is to identify timing regimes to control fragmentation and relief then apply non-electrics to fit these criteria. The use of computer software to graphically interpret delay statistics enables the evaluation of designs in a realistic manner.

Jan 1, 1995

The relationship between the permeability of coal to a mixture of methane and carbon dioxide, and the permeability to methane and carbon dioxide separately is described in this paper, along with the analysis of the differences in permeabilities of coal to methane and carbon dioxide.

Jan 1, 1989

Mine geologists have access to an economic mineral deposit, production parameters and secure exploitation title. They are well placed to understand ore formation and should contribute to the effective exploration of company mine property. Application of their special skills has been curbed by pre-occupation with production duties and by company re-engineering, including staff reductions. Contributions to exploration have been diminished and personal development inhibited. Modified management is required. Participation in mineral system studies and in exploration research comprise part of the basis for the re-emergence of mine geologists on the exploration scene. Changes in investment strategies in the minerals industry may create new employment opportunities. With regard to estimation of resources and reserves, the competence of practitioners who are incapable of disclosing their methods in transparent terms is under question. Ethical standards are also under public scrutiny because of some notable malpractice. Independent auditing may hecome more intrusive. While understandable in a market context, it reflects poorly on the profession. More substantial effort in public communications can improve the credihility ofthe industry and equip practising mine ceolouists for snider responsihility.

Jan 1, 1997

By G W. Wilson, P Ritchie, N A. Currey

The design and rehabilitation of potentially acid forming (PAF) waste rock dumps is site specific, being a function, among other factors, of the rock types, the dumping and storage method employed, and the climatic setting. The æstore and releaseÆ cover system developed to manage acid rock drainage (ARD) from mineralised waste rock dumps at Kidston Gold MinesÆ open pit operations in the semi-arid climate of North Queensland, Australia, has been monitored for seven years. The paper describes the philosophy behind the design of the PAF dump and æstore and releaseÆ cover system and the adaptation of the cover system over time to suit KidstonÆs conditions. The results of monitoring over the seven years since the first cover was constructed are presented, and the approach being taken at Kidston to ensure that the risk of impacts from any residual ARD is accommodated and to facilitate lease surrender are described. The Kidston story is a valuable case study of a successful approach to remediating an identified source of ARD in a semi-arid climate, which has actively engaged all Stakeholders.

Jan 1, 2003

By Ren T. X, Jozefowicz R

In many branches of engineering, there has to be an understanding of the motion of fluids in order to solve problems. Many safety and health problems in the mining industry are typical examples that involve the understanding and analysis of fluid flow, such as explosions, the spread of fires, dispersion of gas and dust, and ventilation patterns. Computational Fluid Dynamics (CFD) is concerned with the use of computers to produce information about the ways in which fluids flow in given situations. Until recently CFD has been widely applied to a variety of industrial sectors and increasingly to problems in the health and safety areas. With the arrival of more powerful computers and CFD packages, CFD techniques are no longer practised solely in a research environment, but can be used by engineers in many industrial fields. This paper introduces the basic concepts and general procedures involved in the use of CFD technology. A comparison is given as a guide to the major features of a number of widely used commercial CFD codes. Areas of potential CFD applications are identified in a range of safety and health problems in mining industry. An example is presented to illustrate the use of this technology. It is believed that the exploitation of these areas using CFD approach will contribute significantly to the solution of today's many mine health and safety problems.

Jan 1, 1995

By G D RICHMOND, Campbell J. J

Aberfoyle Limited has developed the Hellyer complex base metal sulphide deposit located in North West Tasmania. As part of exploration and feasibility study, the ore was extensively tested, including trial milling, and was found to be very fine grained and to have poor flotation selectivity. Substantial innovation was required to produce saleable concentrates at acceptable recoveries and costs. Efforts were made to reduce operating costs, to improve metallurgical performance and to improve work organisation. These efforts were pursued both in design and in subsequent plant operation. This work has resulted in a very competitive operation with production costs in the lowest quartile of the industry. Examples of the measures taken are presented and the results are evidenced by improved plant performance since commissioning.

Jan 1, 1992

A simulation of the fluid flow, minera- logical and chemical aspects of in situ leaching is being developed for application to the recovery of metals from unbroken, naturally jointed rock. The fluid flow aspect has been developed. The rock is assumed to have a double-fracture property. A major joint set is responsible for bulk flow of solution, while a minor joint set, intersecting with the major set, allows the solution to contact the reactive minerals. The two-dimensional fluid flow through the major joint set is analysed by a streamline model for a particular well pattern. The other important components of the model are described briefly.

Jan 1, 1984