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By Arndt MB, Bamberg S

The evaluation of risk is becoming more important in the siting of mining operations in the United States as well as the rest of the world. The determination of environmental, economic, as well as health and safety risks is an important step in the planning of any mining operation. Hydrogeology plays an important role in pre-mine planning and in the determination of these risks. The mine operators must determine if ground water would inhibit mining in any way. Factors which are important to consider include mine dewatering economics, slope stability, and other adverse hydrologic impacts. This paper presents methodologies for the characterization of hydrogeological risks for a mining operation. First of all, the term risk analysis is defined and its utility is addressed. Then, stepwise methods for performing a typical risk analysis are presented. Finally, the application of risk analysis to hydrogeology in mining is given. With slight modification, it is believed that these methodologies can be used to evaluate the hydrogeological risks for any mining operation.

Jan 1, 1988

The term "joint venture" lacks any precise legal definition but is typically used to denote a form of legal relationship which is neither a partnership nor a corporation. Nbst joint ventures are contractual relationships which provide for the sharing of mining leases and production facilities and for the sharing of costs, but which enable each joint venturer to carry on his own separate business. The rationale for such relationships is that each participant: retains independent taxation status may independently grant direct security over his interest in the project assets for financing purposes Bankers prefer to lend to incorporated joint ventures (i.e. corporations in which all of the joint venturers are shareholders) but will lend to individual joint venturers provided the joint venture agreement does not imperil their security; i.e. provided there is a "bankable" joint venture. The carpeting objectives of joint venturers and their bankers may be reconciled and unnecessary conflict avoided by the timely inclusion of appropriate provisions in the joint venture agreement before financing negotiations commence.

Jan 1, 1983

By G Lind

Bridging of production stopes in narrow vein gold deposits contributes to significant financial losses and production delays. Bridging is caused when underbreak in the stope production blast occurs, resulting in less than the designed stope blast volume breaking out during blasting. Jundee Operations in the Northern Goldfields of Western Australia extracts ore from its expansive narrow vein orebodies utilising longhole open stoping. In 2006 it experienced bridging in ten panels, or 8.77 per cent of all panels, as well as multiple bridging in 30 per cent of these bridged panels. The Jundee orebodies are west dipping with the bridged panels dipping between 44¦ and 62¦. This paper examines some solutions from the drill and blast design perspective to minimise bridging occurrences. It was found that the then current drill patterns and number of holes were adequate from a longhole stope design perspective. However, changes to the blasting design, specifically modifications to the blast delay initiation sequencing, primer positioning and blasthole dump combined with timely stope surveying and back analysis, were implemented with the aim of preventing bridging in this narrow vein operation.

Jan 1, 2008

In-pit crushing systems have been known in the mining industry for many decades. The question whether in-pit crushing is a viable option has often been asked. More than 200 mobile and semi mobile crushing systems have been installed worldwide at various locations and applications. Economic pressures have forced mine operators to reconsider the use of a conventional truck-shovel operation and have contributed enormously to the development of in-pit crushing and conveying systems. The in-pit crushing concepts have varying mobility capabilities. These range from fixed, stationary crushing plants to semi-mobile and fully mobile crushing plants. All these systems are operated in connection with a conveying system. In general in-pit crushing systems have technical and economical cost advantages over truck-shovel operation, particularly as mine capacities increase and mines become deeper. The integration of an in-pit crushing system represents a significant up-front capital investment and the mine is only able to depreciate the capital investment over a sufficient mine life including plant capacity to realise the benefit of the much lower operating cost.

Jan 1, 2003

In this paper, a subtle, but important, difference has been drawn between responsibility and mandate. Responsibility has a connotation of financial involvement assigned to an organ- isation as a result of some action it takes, the ramifications of which can be ascribed directly to the organisation. In contrast mandate relates to the power and authority to act. The paper outlines the role of poli- ticians as community decision-makers and the need for Government policy to be flexible in an advanced industrial society so that decision- making options are kept open for as long as necessary. Further, broad community objectives need to be understood and defined so that plans and policies can be consistent. Co-ordination through communication at all levels, especially at the public administration interfaces and with the private sector,is essential for effective resource allocation and efficient implementation. The paper discusses several aspects of the infrastructure responsibility question and some considerations which might be viewed as important by the community decision-makers in considering what responsibility the "community" should accept in providing infrastructure.

Jan 1, 1974

Methods of measuring the frictional properties of rock surfaces, both by direct sliding and in triaxial apparatus, are described. It was found that for some rocks the coefficient of friction remains reasonably constant as sliding is continued but for others it increases considerably.The effect of fluid pressure in the surface of sliding was found in all cases to be adequately represented by the effective stress criterion. Some observations on sliding on two conjugate planes showed that the motion on the two planes may be very different, depending on small differences in the constraints.The coefficients of friction of natural open joints in bore core were found to lie in the comparatively narrow range 0.32 to O.68 although surface coatings were very diverse.A set of diagrams on the equal area projection is given which enables a rapid determination to be made of those planes on which sliding is possible in a given three-dimensional stress field. The influence of the intermediate principal stress on this is of considerable importance.

Jan 1, 1969

The Central Andes in Peru, Chile, Bolivia, and Argentina, contain two contiguous terranes which were accreted i, Gondwanaland between the end of the Devonian and the end of the Triassic. These terranes, Arequipa in the north, anni Chilenia in the south, differ from each other in the timing and style of their metallogenic development. However, they contain over 90% of the Central Andean porphyry copper resource. The copper porphyries in the Arequipa terrane are Paleocene to lower Oligocene in age, whereas the Chilenia deposits are mid-upper Cretaceous and mid-upper Miocene. Porphyry copper deposits occur outside these terranes, but are all Miocene in age. Miocene porphyry-style mineralisation also exists in the Arequipa terrane, but is copper-deficient and gold-rich. The accreted terranes may have favoured porphyry and other styles of copper mineralisation because they possessed relatively thin continental crust compared to adjacent parts of the Andes. Crustal thickening which commenced at about 30 Ma in the Arequipa terrane coincided with a major change to polymetallic, precious metal mineralisation which commonly displays high sulfidation charcteristics.

Jan 1, 1995

The drilling and evaluation of bore cores provides the best available statistical basis for characterizing a coal prospect. Important, long-term decisions by management frequently must be based on the results. The majority of coal mined presently is used for steam raising or the production of metallurgical coke. Common bore core tests and analyses appropriate to this usage can be cate- gorized as non-destructive, chemical, physical, petrographic, caking/plastometric and propert- ies of non-coal material. The major tests within each category are described. Certain specific information from the bore cores is required by the coal geologist, mining engineer, coal preparation engineer and the user, either individually or as a group. The optimal bore core evaluation test pro- gramme is the one which satisfies the needs of all the professional disciplines with the grtatest speed and at minimal cost. The principal steps in such a programme are listed. There is an urgent need for a bold new Australian standard to provide the necessary guidelines to an industry which at present lacks uniformity in its approach to the task.

Jan 1, 1977

By T Smith

The evaluation of a new mineral resource and its economic viability is critically dependant on the quality of the assay data as it is this data that defines the grade of the resource. However, all too often the procedures of sampling and chemical analyses used to generate such data are neglected or given little consideration until final modelling and evaluation are under way. This approach frequently requires large reassay and/or re-sampling programs to be undertaken to validate or to improve the integrity of the data base. This paper outlines a step by step approach to ensure quality data is achieved and then maintained throughout the entire exploration and resource development program. This involves the use of correct field sampling methods, assay methods designed to give the required levels of accuracy and precision and quality procedures in place to monitor the effectiveness of the overall process. Thorough documentation is an overriding and necessary part of the entire process. Practical examples are given to demonstrate the use and value of these methods.

Jan 1, 1998

One of the more recent developments within the mining industry has been the adoption of formal continuous improvement programs. A continuous improvement (CI) program was launched across Kalgoorlie Consolidated Gold Mines (KCGM) in early-2002. The purpose of this program was to identify further operating improvements within departments. The focus of the continuous improvement program was not only on the areas of the operation which were performing below expectations but also on areas of the operation which were performing well but could still be further improved.The effectiveness of a continuous improvement program depends on the stability of the processes in place and the participation of many employees from all levels of the business.Continuous improvement has had some successes and failures at KCGM and this paper will discuss both within the open pits department. Further improvements that could be made to the process will also be discussed. Kalgoorlie Consolidated Gold Mines Fimiston operation is located in the Kalgoorlie Goldfields and it the largest gold mine in Australia producing over 800 000 ounces of gold per annum.

Jan 1, 2004

By M Warren

The professional geologist or engineer on a mining operation has a particular view of their operation. This is based on the factors of the operation that have a direct impact on the daily work program of the professional, such as production rates and grades. The view that would be taken by a financier who is called upon to support the project may be somewhat different. The value of the operation to the financier is in its ability to generate surplus cash for its owners and thus repay the debts to the financiers, with as low risks profile as possible. A number of tools are used to test the sensitivity of the project to variations in the key cost/revenue drivers. The Financier may call on a team of technical specialists to assist with the assessment of the cash flow and risk profile and to monitor the development of the project. The ability to offset this risk, as all projects have some degree of risk, may be a key factor in determining the level of financial support to be offered.

Jan 1, 2002

Scheduling mine development and underground construction has been the bane of most mine managersÆ lives at one time or another. Even though scheduling software has developed significantly over the last 20 years, mining projects continue to take far longer than expected to complete. It would appear that possession of a gleaming 1000 activity bar chart generated by the latest project management software and plotted in multiple colours offers no guarantee at all that any of those 1000 activities will be completed on time, let alone the project as a whole. The author has earned his æmasters in disastersÆ with more than one project running over time and budget. This paper describes some of his experiences in scheduling major mine development and construction projects and the lessons he has learnt along the way. In particular, the paper examines a range of key issues that mine schedulers must take into account when planning mining projects. The paper also examines the development of scheduling software and particular advance rates used in scheduling mine development projects in Australia.

Jan 1, 2000

There is an established need for an inflow of foreign capital if New Zealand is to meet projected growth rates. The Government recognises this and encourages capital inflows especially where there are allied economic benefits such as the access to specialised know-how or export markets. The Government has promulgated certain Regulations which are administered by the Reserve Bank. Under the Capital Issues (Overseas) Regulations 1965, consent is required before any company incorporated overseas can commence business in New Zealand or before an overseas person can borrow or raise any money in New Zealand. A New Zealand company is deemed to be an overseas person if more than 25% of the voting power is held by non-residents. In terms of current policy, overseas companies are permitted to borrow in New Zealand only a limited amount of working capital and some longer term capital calculated on the ratio that their New Zealand owned equity capital bears to their overseas owned equity capital. Wholly owned overseas companies are expected to bring all of their Fixed term capital from overseas.

Jan 1, 1971

Bougainville Copper Limited (BCL) ships about 600,000 dry tonnes of copper concentrate per annum to Japan, Germany and Spain, with some spot sales to other countries. Concentrate sales value for 1984 was 335 million US$, representing almost half of PNG exports. Contained metal determination is based on physical and chemical measurements on representative samples. The entire procedure is subject to statistical uncertainties and possible systematic errors; losses as high as several percent of contained copper or gold are common and frequently are regarded as unavoidable. In this context, the function of the chemical laboratory is to identify and eliminate such errors and recommend correct technical procedures for possible inclusion in sales contracts. BCL's marketing management has encouraged this approach and the close buyer versus seller agreement is beneficial for all parties involved. BCL participates in the respective technical committees of the Standards Association of Australia (SAA) and the International Standards Organisation (ISO). Standard methods for sampling and analysis of copper, lead and zinc ores and concentrates are in course of preparation, some being due for publication shortly.

Jan 1, 1986

The ER&S Company operates a copper sinter plant, blast furnace and converter smelting complex at Port Kembla. Eighty percent of the smelter feed is dirty copper concentrates that contain some lead and zinc. The remaining twenty percent of the smelter feed is copper bearing secondary materials, some of which contain lead, zinc and tin. A predominately lead/zinc fume is produced during the smelting and converting of this feed mix. The composition and tonnage of fume produced at Port Kembla has varied over the years as the smelter feed sources have changed. The economic processing of the fume has always been dependent on the value of the metals contained in the fume and on the fume composition. Both pyrometallurgical and hydrometallurgical methods have been used to treat the fume for the recovery of some or all of the following metals - lead, zinc, tin, copper, cadmium, silver and bismuth. A detailed description of the treatment methods that have been investigated and used to process ER&S fume is given.

Jan 1, 1984

Deep lead mining by methods other thanconventional open-cut techniques has not been effectively employed in Australia in -the second half of this century. The reasons for this are essentially economic, and are related particularly to the labour intensive nature of the methods involved as well as the high consumption of support materials. These methods have been adapted in recent times to undertake bulk sampling programmes in deep leads. Although some consideration is given to surface-oriented hydraulic and solution mining applications, the prime function of this paper is to investigate the possible application of modern underground methods to deep lead exploitation. As deep leads are not currently being worked (with the exception of some minor operations on the Eastern seaboard), these applications remain essentially untested. They have, however, been conceptually developed following several years of small scale deep lead development. Current mineral economics, particularly with respect to gold, combined with the known extent of partially - or totally - unexploited mineralised leads demonstrates the necessity to investigate all possible means of ore extraction.

Jan 1, 1985

Since 1865 when Congress moved to create a Federal Mining Bureau, successive legislations have given rise to the current '!Federal Coal Mine Health and Safety Act, 1969. Coal beds from 22 feet to 20 feet thick are mined under covers from 50 to 2800 feet with full and partial pillar recovery equally popular and accounting for a total of 54% of the mines. Pillar recovery and roof support practices vary, and each operator must submit an overall roof control plan (within specific guidelines) for approval before undertaking any development. The guidelines relate to dimensions of openings, details of support, sequence of extraction, limits of extraction and caving details. Experienced and professional staff of M.E.S.A. provide roof control plans and make inspections and grant-approvals of principles of support and minimum support in pillar extraction, with provision for modifications with time. Guidance is given with training programmes and standards of supervision. All of these aspects are approached in the spirit of the Congress declaration that the first priority and concern must be the health and safety of the miner.

Jan 1, 1974

In the consideration of coal resources in this country one of the most neglected aspects and perhaps one of the most important is that of the geologic controls on coal formation. The composition, properties, thickness and distribution of the coal are all determined by geological factors. The extent and amounts of coal to be found in the South Auckland area have great economic significance, and are in the main considered here. Upheaval of the New Zealand geosyncline during the Rangitata Orogeny produced a system of parallel, north-south trending basement ridges and basins in the South Auckland area. A subtropical climate and relative tectonic stability allowed deep weathering of these mesozoic greywackes in the late Cretaceous and early Tertiary. Such weathering, markedly reduced the landscape relief, and provided vast supplied of very fine detritus for later sedimentation as the Waikato Coal Measures. This coal measure phase marked the beginnings of Tertiary  sedimentation in this region and represented a change from a sub-aerial weathering regime to a fresh water swamp environment.

Jan 1, 1976

Feasibility studies in the development of mining projects are fundamental to most investment decisions. It is important that the issues addressed and the degree of detail involved in feasibility studies are consistent with the investment decisions to be taken. Emphasis should be placed on a thorough analysis of critical project parameters prior to detailed investigations being undertaken into other activities which are not relevant to the decisions at hand. Therefore, the issues to be decided upon should be influenced significantly by the stage of development of the project and by the reliability of technical and financial information used in the study. Some of the more critical parameters of feasibility studies are commodity prices, inflation rates and discount rates. Advice is given on the selection of these inputs and also on their application in the feasibility study as the project progresses through its various development stages. The feasibility study should involve not only a formal evaluation of project economics but also an analysis of all project related risks and a comparative analysis of projects competing in

Jan 1, 1983

MR JOHN S Foxall wrote: Mr Clayton in his paper on the above subject (Proceedings, N.S. No. 34) made an assertion which should not be allowed to remain unchallenged. On the top of page 10 appears the following statement;- "By viewing the box at adepression angle of 45°, all the dimensions are disclosed and the box may be projected on isometric co-ordinates" and lower down on the same page:- "An isometric plan, being virtually a projection on a plane inclined at 45°, the nearer the dip approaches this figure so is the outline of the stoping more truly shown." Those statements embody an inaccuracy which would be misleading were an isometric plan to be constructed to suit a special case, ie the case of a mine whose lode dipped at 45°, or approximately 45° and it would be found that in such a plan the outline of the stoping would not be truly shown. The reason for this is that the depression angle at which an object is viewed in order to...

Jan 1, 1920