Search Documents

There are significant Mineral Resource and Reserve reporting challenges facing a mining company operating in the global arena. This paper specifically examines the Mineral Resource and Reserve reporting challenge facing BHP Billiton. The changing regulatory environment creates a significant challenge for global mining companies when reporting Mineral Resources and Reserves. The development and implementation of internal policies and standards for collecting and collating resource and reserve information is required for corporate governance, however the challenge is then to report this information publicly in such a way as to comply with the various codes and requirements in the many jurisdictions in which the company is required to report. The move to an International Code is not only desirable but is an essential requirement in todayÆs global market. The agreement to report using a single code internationally is however only the first step. A truly practical international reporting system must have common definitions and guidelines for interpretation as well as an international approach to the definition of a Competent Person, and even more importantly a common acceptance of that code by the relevant investment regulatory bodies. Without the universal acceptance of the concept of an international reporting code by the major regulatory bodies, implementation of such a code will be limited. With the major global mining companies seeking to raise capital in the USA, the worldÆs largest capital market, the Securities and Exchange Commission (SEC) and its approach to reserve reporting is becoming increasingly important. The development and implementation of an International Code must gain the support and acceptance of the SEC if it is to be successful.

Jan 1, 2002

Pulverised coal firing was pioneered in the cement industry prior to the turn of the century. Ash from the coal is absorbed into the mix in the kiln and replaces secondary materials. With high purity limestone coal with high ash content can be used. Fuel cost is a major part of the total manufacturing cost. Cement plants are thus quick to respond to fuel price changes and will use low grade fuels if there is a price advantage. Combustion conditions in a cement kiln differ markedly from a boiler. Flame length is determined by air/fuel mixing but because of fixed secondary air conditions this depends on primary air momentum. Volatile content has some effect on flame length but this can be offset by coal fineness. Much of the heat for cement production is for limestone calcination which is a low grade energy requirement. By allowing long residence time in separate direct fired vessels which then feed the high temperature kiln the energy of materials such as oil shale, tyres and lump lignite can be utilised.

Jan 1, 1987

By K McNabb, M H. Turner, P A. Jenkin

Mining of the Agnew nickel deposit commenced in 1970 using a variety of underground mining methods, though with mixed success due to the difficult ground conditions. WMC Resources Ltd acquired the operation in 1989, and commenced nickel production with an open pit. In 1995 all production reverted to the rejuvenated underground mine, using exclusively SLC (sublevel caving) methods. Currently the mine produces 1.4 Mt per annum, at an average grade of 1.74 per cent Ni. Underground mining of the Perseverance orebody has always presented significant challenges due to the difficult ground conditions in the weak and altered ultramafic rocks. The range of problems include areas of swelling minerals, intense and extremely weak shear zones, relatively high in situ stress, and in other areas very brittle rocks. Under these conditions rock mechanics input has been and remains a critical element of the mining strategy. Severe ground behaviour difficulties down to a depth of 500 m below surface prompted a review of the mining strategy for the large disseminated nickel orebody, including evaluation of alternative mining methods. However, sublevel caving was ultimately selected as the preferred method, and a re-design of the SLC cross-cut layout followed. A selection of rock mechanics investigations of interest are described, including complex virgin stress measurements, detailed ground behaviour monitoring, and the use of non-linear stress analyses to re-design the mine layout. Subsequent ground behaviour, support design and production scheduling are also described.

Jan 1, 2000

To the south and west of Broken Hill lies the Thackaringa silver-lead district, about 25 miles, and is the locality really of the first silver find in the country long before Broken Hill, the geological fomations of which it much resembles. The Iocks and their structure are identical, except that in this area they are  more irregularly foliated and apparently much more faulted and expose in places quick successions of complete anticlines and synclines, even in a single lease. Saddles of ore respectively are found coinciding with the flexures of the rock but many minor veins otherwise and branches exist and make connections which render the whole a mining problem. It follows then that the surface.of the ground after some denudation in dotted with croppings of all the series, and in such a confusing way that the actual strike of a vein may be even confounded with the dip and readily mistaken for it at a few places. The main character of the outcrops are those usual in the district consisting almost wholly of argentiferous and silicious ironstone, sometimes gossan, which at a depth in a few feet changes to a gangue of very silicious carbonate of iron (crystallised), which occurrence is uniform through this district.The exploration of the lodes has not been extensive as it has not been well understood. Shallow shafts and drives have comprised nearly all the mining at present, which is evident on first sight by the numerous shafts and small excavations dotted 'about, as in an alluvial field. The depth of exploration underground in one place had gone several hundreds of feet, never more than 150 feet vertical from the surface in depth and irregular. The undulations of the most continuous work in this direction is such that it presents at different places successively either a tunnel, shaft, underlay winze, level, or Tise, and is on ore all the time, and where the rocks are faulted (which occurs as much as 30 feet and more) these changes are very abrupt, but for working on are suitably connected by the management.

By S Grano, M Fordham, H Manouchehri, J Curral

This paper focuses on the impact of high pulp temperature on sphalerite flotation after the zinc regrind circuit in the Zinc Plant of Somincor, owned and operated by Lundin Mining Corporation. In the zinc circuit, the zinc rougher concentrate is reground with forged steel media before flotation with one stage of roughing and scavenging, and three stages of cleaning to obtain a zinc final concentrate (zinc grade >50 per cent). After regrinding, sphalerite flotation has been found to be seriously affected by high pulp temperature which may occur during the summer months. Mineral recoveries were found to be seriously reduced at pulp temperatures above 60¦C. At this high pulp temperature, neither elevated copper sulfate concentration nor a decreased pH alone appreciably increased Zn recovery. However, a combination of these two (eg a decrease in pH from 11.5 to 10.8, and an increase in copper sulfate dosage from 400 g/t to 800 g/t) was found to reduce Zn depression at high pulp temperature. At pulp temperatures below 45¦C, the negative influence of pulp temperature on mineral recoveries was minimal. A systematic series of flotation tests and solution/surface analyses were performed to reveal causes for poor sphalerite flotation at high pulp temperature after regrinding. The decrease in mineral recovery was shown to be associated with variations in the surface species on mineral particles in response to the increased pulp temperature. These variations in the surface species include collector desorption and superficial oxidation to form lead/zinc oxide/hydroxides on mineral particles. The influence of the type of regrinding media on sphalerite flotation at high pulp temperature was also addressed in this work.

Jan 1, 2008

By M Thomas, S Lambert

The Tugun Bypass Tunnel in Gold Coast, Australia was constructed using diaphragm walls with the top-down cut-and-cover method to allow simultaneous construction of an airport runway extension above the tunnel, whilst excavation of the tunnel continued underneath. The tunnel was built in an environment of high groundwater table and deep deposits of alluvial and estuarine soils with the toes of the walls founded in soil deposits. There was a potential risk for differential settlements to occur between the diaphragm wall panels, caused by the runway fill placed over the tunnel roof during excavation. Dewatering within the diaphragm walls was required to facilitate the construction of the tunnel. The tunnel was also built in an area where environmental considerations were of great importance. Three-dimensional numerical modelling was undertaken to predict the differential settlements of the tunnel with considerations of varying subsurface profile, staged excavation and dewatering, non- uniform surface loading and complex soil-structure interaction. Field instrumentation and monitoring was implemented to confirm numerical predictions.  

Jan 1, 2008

The intent of this address is to look forward into the 21st Century and present certain thoughts as to how underground coal mining might be conducted. The views in this talk are based principally on the author's experience with mining practices in the United States. It may be difficult to accept, but the 21st Century is a mere 12 years away. What new techniques will be available? To develop an understanding of the way in which technology has been and could be changing, a two- stage analysis is made of mining technology for U.S. Coal. The first phase covers the period 1975 to the present, while the second includes 1960 to 1975. This historical perspective includes a view of underground production by mining methods, considerations of labour productivity, and a review of accident and fatality rates. Several topics are important features of this historical analysis. Among the most significant are: (1) the introduction of Ion-wall mining technology into U.S. underground coal mines, (2) the use of computers to assist in mine planning and design activities, (3) major efforts to improve health and safety performance, with emphasis on underground dust control, and (4) improvements in mining equipment with an eye towards increased reliability and up-time performance. Based on that historical perspective, projections are made in three increments. The first being immediately at the turn of the century, the second being a dozen or so years beyond that, and the third being at the quarter point of the 21st Century.

Jan 1, 1988

By S Vink, V Nanjappa, C J. Moran

Poor quality water resulting from interaction of surface run-off with saline mine spoil and soils can cause significant problems for water reuse on mine sites. Not only can this saline water lead to machine corrosion and increased maintenance costs, but may cause detrimental effects on the environment. Determining the geochemistry of mine spoil, and the likelihood of salt dissolution during rainfall events, may aid in more effective mine site management of water. Spoil samples were taken from three areas of the German Creek mine site, situated in the Bowen Basin coalfield, Queensland. Samples from two undisturbed areas on the lease were also collected for comparison. Analyses were performed using a variety of laboratory techniques: leaching tests, effective cation exchange capacity determination, X-ray diffraction, clay quantification, and total organic content determination. Results show that dissolution of surface (top 2 cm) salt minerals from spoil areas is an important contributor to surface run-off salinity during rainfall events. Equally, ion exchange with clay minerals appears to be a significant source of elevated ion concentrations in run-off waters. Findings from the undisturbed areas show undetectable quantities of salt mineral species, resulting in waters with low ion concentrations. More generally, monovalent cations (sodium, and to a lesser extent potassium) appear to be derived from dissolution of salt precipitated whereas divalent cations (calcium, magnesium) are more likely to be sourced from exchange reactions with clay minerals. Incorporating knowledge about the mechanism of cation mobilisation from spoil with the spatial distribution of spoil properties and understanding of the dynamics of water quality variations on the site will aid in development of integrated water quantity and quality management strategies.

Jan 1, 2009

By Boehme PW, Gregory OR

The results presented here show quite definitely that in the system investigated the intensity of dispersion is enhanced by switching the flow entry from bottom to sides of the packed trough. Since there is no reason to suppose that this would not be true generally then it is not surprising that the blast furnace dispersion data of Standish and Polthier lie above the data for packed columns with bottom fluid entry. In fact, on the basis of the present results, blast furnace dispersion results can never equal standard packed column behaviour but must always be above these. The result that the intensity of dispersion in the trough model is higher closer to the side ports than away from them is at variance with that of Standish and Polthier blast furnace results. Aside from the obvious structural differences between these two systems, it is thought that the presence of raceways and the tortuous path of the gas flow in the furnace may provide an answer. Clearly this is an important difference in the behaviour of the two systems and further investigations designed to clarify the position would have significant practical value. This would also give an indication of how the furnace D/ud values may be decreased along the whole height - assuming of course that this result gives the best overall performance of the furnace. However, there is to date no knowledge whatsoever about this aspect of blast furnace Technology.

Jan 1, 1975

By S Morrell, D Clark

æMine to MillÆ improvement involves optimising the chain of rock breakage processes from the in situ rock in the mine to the output of the concentrator. A growing number of paper studies and case histories from metalliferous mines (AusIMM, 1998; JKMRC, 1998; Clark and Scott, 2002) demonstrate that generating more breakage in the pit and the primary crusher can lead to benefits to milling that result in significant improvements to the economic performance of a mining project. However, unless the ævalueÆ of doing this (benefit over cost?) can be appropriately quantified, the approach cannot be effectively managed and the increases in blasting and monitoring costs cannot be justified.Mining operations have traditionally been organised into the separate departments of geology, mining and processing based on the specialist skills required and the different professional disciplines involved. Process optimisation across these boundaries has commonly been frustrated by management requirements to minimise the costs incurred by each department without adequate reference to the ævalueÆ being created. Companies have tended to discard positions that provide a technical over-view of the value chain, reducing the number of people with the opportunity to influence practices across these process boundaries.This paper discusses these issues and identifies measures required to quantify and manage the ævalueÆ provided by æMine to MillÆ improvement generated by the intense blasting of ore.

Jan 1, 2002

By P Waters, S Miller

BHPBilliton operates the Mt Whaleback Mine located in the semi-arid Pilbara Region of Western Australia. Approximately 200 Mt of net acid generating (NAG) material still remains to be mined. Acid Rock Drainage (ARD) was first identified at the site in 1995 following cyclonic storms. This resulted in the development of strategies that have allowed the mine to successfully manage ARD whilst continuing to operate. BHPBilliton Iron Ore is working toward prevention of ARD in its operations, however, historical practices have left residual areas that must be considered. Three significant sources of ARD have been identified that must be managed: stormwater run-off from exposed pyritic shales in pit surfaces; basal flows beneath overburden storage areas following rainfall events; and contaminated water from pit dewatering. The mine contains all ARD water onsite. This is achieved by: storage of all affected water in the ARD dam; evaporation of affected water from the ARD dam and the adjacent evaporation ponds; pumping from upstream dams to prevent stormwater from being affected; and emergency storage and treatment in-pit as a contingency. The site ARD management strategy is approved by senior management and endorsed by State Government regulatory authorities and relevant external stakeholders. Additional strategies are also under evaluation to effect long-term closure of the operation. Record rainfalls from 1998 - 2001 have tested the capabilities of the ARD strategy and management plan. Learnings from these events, coupled with recommendations from an extensive technical audit in 2000, have been incorporated into the strategy for ARD management. This paper presents the strategy and an overview of the ARD management plan that can be considered and applied by other affected sites in the management of ARD.

Jan 1, 2003

Bauxitic laterite of variable thickness and grade is best developed in the Darling Range but covers a large part of the southwest corner of Western Australia. Its limits are defined by the rainfall isohyets to which jarrah forest is confined. Within this broad belt there is an increase in arable land southwards concomitant with a thinning of the laterite layer.Bauxite quality and perhaps thickness as well are dependent on the type of source rock, and are influenced by topography. Economic deposits occur over a vertical range in altitude of about 1200 ft. Some bauxite orebodies appear shoot-like in character, and analogy is suggested with the ore shoots of syngenetic metalliferous deposits.The alumina is in the form of gibbsite enabling low temperature digestion in treatment.INTRODUCTIONAlthough the existence of bauxite in Australia has been known for many years it is only recently that exploitation has commenced of the two most important deposits, strangely at almost diagonally opposite tips of the continent (Fig. 1).Recognition of the importance of the bauxite in the southwest corner came about initially through the efforts of Western Aluminium N.L. which, with some outside financial help, tackled the early exploration with commendable foresight and courage. Subsequent investigations around the periphery of the original reserves (now held by Alcoa of Australia) were undertaken by several companies, including Bauxite Exploration Pty. Ltd.ORIGIN OF BAUXITEThe genesis of bauxite is stilI somewhat controversial.Owing to its common association with kaolin some investigators have been led to believe that it has been derived from the latter; others believe the process has been vice versa.From a recent study of the Arkansas bauxite region in the...

Jan 1, 1964

In current mining practices it is desirable to bring about a substantial increase in both rate of face advance and productivity, thus compelling the mine engineer to consider better and more productive ways of mining. Transportation plays a vital role in achieving improved productivity. This paper focuses on horizontal transportation systems. Horizontal transportation is defined from the shaft station area to the end of the stope cross-cut. Traditionally, horizontal transportation is inefficient in comparison to vertical transportation efficiencies and accounts for a high proportion of South African mine accidents. Thus, the role of horizontal transportation has been investigated in detail, as it offers the greatest chance for improvement. The purpose of the paper is to provide a best practice guideline for the design of horizontal underground transport systems. It is intended that the document be used by mine designers and planners as an aide memoir during the design process and benefit may well be gained from retrofit and reorganisation activity. The paper looks at transport systems suitable for deep level gold mining in South Africa and evaluates such items as management, scheduling, and haulage systems. Current transportation systems for personnel, material and rock transportation are evaluated, gaps in technology highlighted, and recommendations made.

Jan 1, 2003

Continuous processes must be shutdown and restarted regularly. Results from the study of operating plants showed potential value for computer simulation of the shutdown and startup of stirred tank leaching reactors. Simulation allows operational variables such as feedrate, and process variables such as the dissolution kinetics to be altered to establish trends in behaviour. Results are presented for the start- up of a cold, empty, single stirred tank reactor, in which three solids are leached at elevated temperature at steady state. Increasing the average temperature in the reactor during startup did not change the fraction of 'valuable' solid dissolved in the first product but it did increase the fraction of slow dissolving (impurity) solid dissolved.

Jan 1, 1984

By Dixon D. R, Sparrow G. J

Pressure leach liquors from the pressure oxidation of a bulk flotation concentrate prepared from a complex Cu-Pb-Zn sulphide ore were treated to remove iron, either by pressure oxidation (the Hematite process) or with particles of magnetite (the Magnetite process), followed by cementation of various metals with zinc dust to obtain a purified solution from which zinc was electrowon. Satisfactory iron removal was achieved by both processes after neutralisation to pH 4.5 or 5.5. Pressure oxidation of the liquor at 200¦C and 690 kPa oxygen overpressure, conditions similar to those of the Hematite process used in the zinc industry, resulted in the precipitation of the iron as hematite. With the Magnetite process, an iron hydroxide was precipitated onto magnetite at atmospheric pressure and ambient temperature and removed by a magnetic separation step. The performances of both these processes for the removal of iron are compared. It is concluded that the Magnetite process offers considerable cost savings. Other impurities, in particular arsenic, were also removed with the iron in both processes. Cementation at pH 5.2 and 85-90 ¦C with 3.5 g/L zinc dust reduced the levels of copper, cadmium, and nickel to a satisfactory level and subsequent electrolysis in a laboratory cell gave an acceptable deposit of zinc.

Jan 1, 1989

By P Lamberg, M Lyyr, S Heimala, J Liipo

Since the introduction of froth flotation for industrial practice, the process has long been developed and improved by making cultivated guesses or by using trial and error methods to a varying degree. Fresh possibilities have emerged after development of new surface sensitive analysing methods and in situ electrochemical methods. Having had the possibility to combine different findings between science and everyday plant practice, Outokumpu has been able to develop a catch-all procedure to manage a flotation process taking into account the specific requirements set by different minerals in a slurry. A number of these procedures are available and offered globally to clients as part of a Plant Audit service. The Outokumpu Plant Process Audit (Process ef-X) concept comprises of mineralogical determinations from process samples and plant data analysis together with electrochemical process measurements using mineral electrodes. Automatic control loop analysis can also be included. The objective is to combine the results for a basis of flotation process improvement. Since this methodology has earlier been an in-house practice, it follows that the results are also reflected in the development and design of the OutokumpuÆs processing equipment. An increasing number of ores have a very intimate fine-grained texture and it may be physically impossible to combine high grade with acceptable recovery by a flotation process alone. For such cases, combinations of different hydrometallurgical û mineral separation û pyrometallurgical processes are available. Mineral specific information and chemical expertise of flotation technology can be utilised in development of other processes, as well.

Jan 1, 2005

About 60 persons are admitted to the graduate course every year after passing the entrance examinations. The entire course of studies is free of charge and the universities provide accommodation for the students who need it. The five years of studies are divided into 10 semesters. One semester lasts 15 weeks. Automatics can be studied at three separate faculties. At the University of Mining and Metallurgy, it is offered by the Faculty of Electrical Engineering, Automatics and Electronics as well as the Faculty of Mining and Metallurgical Machines (metrology can also be studied there); at the Silesian Technical University in Gliwice, the Faculty of Mining offers the course. The educational plans and programmes comprise 3 groups of subjects: common for a given course of studies (foreign languages, political science and the basic technical knowledge) common for the speciality and subjects of diploma courses. The whole time of studies covers about 4400 hours excluding 3 periods of professional training and the physical training. The classes, laboratory classes, seminars and design classes are obligatory and the attendance is strictly checked. Students may extend their knowledge by participating and working in the Science Clubs. The students' work is checked not only during the classes but also by the examinations held at'the end of respective semesters. Those who fail the exams can repeat them only if very important reasons are presented. At the very end of the studies there is a diploma examination together with a discussion on the diploma thesis, written by the student. The successful result entitles the student to recieve the title of "magister inzynier",M.Sc. of his speciality. The graduates, after working for 2 years, can attend another course of studies lasting 2 semesters and called "Postgraduate Course", or start "Doctoral Studies" finished by the defence of a doctor's thesis. In'these cases the expenses are usually covered by the graduates' employers.

Jan 1, 1985

British Coal has always been a big mining company and its management has been beset with many of the problems one would associate with such an undertaking. These include its accountability to Government, its market vulnerability to competing fuels and to imported coal and its relationship with its workforce but also with its own history and size. As a fragmented private industry up to and including the Second World War, it was starved of capital and its management developed an historic relationship with its workforce which was often counter productive to success. Once nationalised, it contributed greatly to post-war industrial regeneration, investment was forthcoming to reconstruct existing mines, sink new ones and to mechanise production operations. British manufacturing companies contributed to this mechanisation drive, the very success of which drove up production and productivity and against a declining market, contributed to the reduction in size of the industry. Production machinery design evolved in the 1960s with close collaboration between manufacturers and users such that an inevitable proliferation of machinery types and specifications developed to meet local needs. Longwall mining internationally outside Western Europe only became significant in the 1970s. It became apparent that international operators demanded higher levels of plant performance from British manufacturers than British Coal did. This was the birth of the "heavy duty" plant concept. As international performances outstripped our own then British Coal moved in to invest in itself, in this heavy duty. This re-investment commenced in the mid 1970s but only gained real momentum in the 1980s when it became a virtual re-equipping exercise for the whole industry.

Jan 1, 1988

By S P, F Villanueva, R Palomo, D Meadows

During 2002, design and development of the worldÆs largest flotation cell was completed. The cell is the mineral industryÆs first 257 m3 flotation cell, and represents a major development in the design of larger flotation cells, with a 50 per cent increase in cell volume over the widely installed 160 m3 WEMCO« SmartCellTM flotation machine. It is anticipated, in the next few years, world-class copper sulfide concentrators will incorporate 257 m3 flotation cells in their rougher-scavenger flotation circuits. The prototype 257 m3 cell, No 250 SmartCellTM flotation machine is installed in Minera Los PelambresÆ existing rougher flotation circuit. The machine is located in front of the first cell in Row 1 and is followed by nine No 130 SmartCellTM flotation cells. The unit has been in operation since April 2004, and has proven itself in this duty. A key to the successful development of the equipment has been the emphasis placed on fundamental hydrodynamic scale-up criteria. Hydrodynamic factors include superficial gas velocity, water (pulp) circulation through the draft tube, and pulp mixing (distribution) characteristics. This paper will review the scale-up criteria of the No 250 flotation cell, and a case study will be presented on the in-plant testing of the equipment. The case study will document the metallurgical and hydrodynamic performance of the machine. It will also illustrate the economic benefits derived by incorporating larger flotation cells in a modern copper sulfide concentrator.

Jan 1, 2005

The cost-effectiveness of blasts involving radiating blastholes is cur- rently restricted in the following ways. (a) Significant percentages of potential explosion energy are not being liberated; the collar sections of some charges are being dislocated and/or desensitised by the detonations of adjacent earlier-firing charges. (b) If the minimum charge spacing is too small, detonation of an early- firing charge can initiate an adjacent charge sympathetically, thereby eliminating the benefit of any intended inter-charge delay. (c) The overall distribution of energy is poor. Appreciably better fragmentation would be achieved if current drill- ing patterns were to be replaced by staggered fans/rings having a toe spac- ing : burden ratio of about 4 : 1. This wide-spaced pattern would enable a higher percentage of the potential energy to be released, would reduce the incidence of sympathetic detonation and would provide a superior overall distribution of this liberated energy. If improved fragmentation is not required, the proposed fan/ring design should allow a significant expansion of the blasthole pattern with consequential cost savings in drill- ing, explosives and initiation.

Jan 1, 1988