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The equity market is now very much within a global village environ- ment, with various exchanges acting as agencies for the big casino. In this predicament, mining companies, who provide the most extensive, but relevant risk assessment information, will be best placed for favoured treatment by potential international investors: But what risk assessment information in summary form can be provided to support a resource/reserve statement? Even more importantly, does "objective" data exist, whose trends will support a resource/reserve state- ment? A prime need of the informed mining investor is to determine whether or not the resource/reserve statement is believable? But more importantly will it be realised? While the implications within the text of the majority of reports on resource/reserves suggests that the estimates are conservative, the record indicates that very few estimates are. In fact, to date, reports claiming to be conservative in respect of the overall grade estimate at a specfic cutoff have not reflected the realised grade at the stated cutoff; it has been more common for the realised grade to be lower than implied by the resource/reserve statement. Further, it is not uncommon for penalty elements to be understated and these components are rarely incorporated within resource/reserve statements.

Jan 1, 1988

By Takiuchi T, Kurita M, Owada S

This paper describes the possibility of the application of flotation to the separation of monazite from xenotime and of columbite from ferberite, which have been said to be difficult with generally used physical beneficiation methods. For Malaysian monazite and xenotime samples, a great difference is observed between the flotation recoveries at pH 7.5 using 1.0 x 10-4mol/1 dodecylammonium chloride (DAC). The grade and recovery of columbite in the binary flotation with both minerals result in 85 per cent and 67 per cent in the cleaning froth and 91 per cent and 51 per cent in the re-cleaning froth, without adding any scavenging stages. For monazite samples from various localities, the flotability is dominated by the electrostatic interaction between mineral surface and collector ion using DAC as collector, but the singular decrease of flotation is observed in the sample of which the crystallinity is low and the surface structure is rugged and complex. Otherwise, ferric ion in the flotation system probably dissolved from mineral is found to activate the flotation using sodium dodecylsulfate as collector. For columbite and ferberite, the separation is judged possible at pH 3.0 using 1.0 x 10'3mo1/l sodium oleate (NaOl) from the single flotation results of each mineral. In the binary flotation, however, columbite recovery in the froth is greatly diminished below that expected. This would be because NaOl is prevented from adsorbing on the columbite surface of which the charge is transformed more negative side by the specific adsorption of the tungstate ion dissolved from ferberite.

Jan 1, 1993

By Denby B, Hollands R. Schofield D

Surface mines are in operation worldwide, the vast majority employ large haul trucks for the transfer of material both to the outside world and around the site. The sheer size of these trucks and the operating conditions means there is a high

Jan 1, 1998

By McDonough RJ

Mechanical agitation is the preferred system for Carbon-in-Pulp processes. Agitator design requires an understanding of the relationships between energy, shear and flow and the nature of shear rates and shear stress distribution in an agitated tank. Laser techniques are useful when studying these phenomena. The alternatives are open impeller agitation or draft tube circulation. Each has advantages and disadvantages but both require careful choice of impeller and system geometry. Overall the draft tube circulator is the more attractive in many cases. Open impeller agitators are designed in accordance with established procedures for mineral slurries taking due account of shear effects in tanks containing carbon. Preferred tank proportions are 1:1. Circulator design methods were developed in the alumina industry before being applied to CIP processes. Optimum draft tube diameter is critical to power requirements. The overall system must be designed as an axial flow pump operating in a closed circuit. Such a system exhibits quite characteristic behaviour which requires an impeller of varying pitch angle and aerofoil section for best stability and efficiency.' Tank height may be 2 or more times diameter. Resuspension of settled solids can be assisted by a series of slots in the draft tube. These slots have the secondary effect of stabilizing hydraulic behaviour and reducing installed power requirements.

Jan 1, 1982

By Morley C

The Mount Charlotte gold mine is located 0.75 km east of the General Post Office in Hannan Street, Kalgoorlie WA and about 3.5 km north of the Fimiston Operations on the famous Golden Mile.Mechanised underground bulk-mining at Mount Charlotte has been in continuous operation since 1963. For the 30-year period ending December 1992, the mine produced 22 million tonnes (Mt) of ore for a recovery of 2.73 million ounces. During 1991/92, the mine produced 1.53 Mt of ore at a head grade of 3.15 gramshonne (g/t) for a recovery of 135 822 ounces.The principal ore source at Mount Charlotte has been the Charlotte Orebody which is now largely mined out. Since 1990, approximately 75 per cent of production has been sourced from the Reward Orebodies. The Charlotte Orebody was a relatively homogeneous quartz stockwork with simple geometry and average bulked grades in the range of 4.0 to 5.5 g/t. This is in contrast to the Reward Orebodies and the more recently defined Charlotte Deeps and Maritana Stockworks, which have complex grade distribution and geometry with lower average bulked grades (2 to 4 g/t). The lower grades are principally due to the decreased density and volume of stockwork venation and related vein halo alteration. Typically, these stockworks comprise a patchy mosaic of quartz veins and vein swarms, with irregular distribution and geometry within the quartz gabbro host rock.

Jan 1, 1993

By Yaniuk DW

The sampling of non-ferrous concentrates from trucks and trains has long been carried out either manually or by automatic spears. Very little use has been made of conventional sampling systems for sampling concentrates at transfer points, or cross-belt samplers for sampling from the belt as the concentrate moves along the conveyor.Due to the high value of base metal concentrates and the often extremely heterogeneous nature of the material it is imperative that the sampling procedures adopted are accurate and precise. The basic principle that all particles in the stream have an equal opportunity to be included in the final sample is not fulfilled by accepted traditional concentrate sampling procedures such as the spearing of wagons, trucks or streams. This may lead to significant bias being introduced into the final sample.Consequently, the application of correct sampling procedures, either with conventional cross-stream samplers or the newer cross-belt samplers, is of prime importance.SGS Australia has recently installed a number of cross-belt samplers for the sampling of base metal concentrates both in Australia and overseas. The application of these samplers will be discussed with emphasis on the benefits of their use.

Jan 1, 1976

By Bedford D. J

The post pillar cut and fill stoping method has been adopted by King Island Scheelite for the extraction of the main Dolphin orebody. The orebody is a massive, tabular deposit varying from 10 to 50 metres in thickness, and dipping at approximately 30¦ towards and under the sea bed. The mining method was selected for 1. maintenance of hangingwall support under the sea bed; 2. maximisation of first stage ore extraction; 3. flexibility of mining, allowing maintenance of grade and selective mining around waste bands within the orebody, and 4. compatibility of existing equipment both with stoping and the on-going underground mine development programme. Stope parameters were established on the basis of initial rock stress analyses, and since the undercut phase of mining the stoping programme has been monitored with various types of deformation measuring devices installed in a series of large diameter boreholes.

Jan 1, 1977

Thermal Processing of Petroleum Fly Ash for Vanadium Recovery

Sep 13, 2010

By Hossaini SMF

After reviewing the various approach es,namely, empirical,analytical.observational and numerical, a logical systematic approach is proposed for the estimation of compressive strength of coal pillars. In this approach first,uniaxial compressive strength of coal in pillars is estimated,taking into account the size effect and the effect of discontinuities. Next,the compressive strength of coal pillars is estimated by determining the stress distribution in the pillar and the Bieniawski strength criterion. The results appear to be compatible to the ones obtained by Wilson's method. The traditional pillar design equations give improper answers for deep workings.

Jan 1, 1991

By Lyman GJ

Systems for the routine on-line determination of ash content of process streams in coal preparation plants and handling systems have been in use in Australia for over four years. More recently, monitors for on-line moisture measurement have been developed to complement the ash measurement function. The technology for these systems is reviewed briefly. The development of reliable ash and moisture monitors has made the implementation of automatic systems of coal quality control practical. The emerging philosophies of automatic control in Australian preparation plants are examined with particular emphasis on systems involving dense medium circuit regulation. Related developments in flotation control and coal sorting are noted to complete this overview.

Jan 1, 1987

By Svenson D

For fully effective information to be obtained from exploratory drilling for coal, drilling programs should be planned systemati- cally in successive stages, on the basis of existing geological criteria and information collated during each stage. In this way, drilling can be executed with optimum economy, aided by auxiliary geophysical techniques wherever these may be appropriate. The object- ives of the programs must ultimately include an adequate assessment of mining conditions as well as thorough evaluation of coal quality. The first of these objectives is not always appreciated by both geologists and mining engineers engaged in supervising drilling pro- grams, often resulting in the need for more additional drilling and more expense than would otherwise be required. To achieve all of these objectives as effectively as possible, the drilling should be supervised by well qualified personnel experienced in working in a multi- dicipline, professional mining, geological and engineering team.

Jan 1, 1977

Jarrah Decline is currently the only underground operation at the Boddington Gold Mine, (BGM). The mine is located 120 km SE from Perth in WA, with mineralisation hosted within deeply weathered felsic and intermediate intrusions and volcanic rocks of the Saddleback Greenstone Belt (Morley and McBride,1995). Open cut operations commenced in April 1987 with a mill throughout of 3.OMtpa. A number of upgrades have since taken place, with the oxide material throughput currently milled at a rate of 7Mtpa. In 1992 a separate circuit, the supergene mill, was commissioned to treat copper material from the open cut and now ore from the Jarrah Decline. Current throughput in the supergene plant is 30,000 tonne per month, with a varied blend according to mill requirements. Total gold production from the Jarrah Decline in 1994 was 60,000 ounces from 90,000 tonne of ore.

Jan 1, 1990

By Moore A. J

This paper describes the use of a wavefront reinforcement model which has been developed to supplement established charge mass scaling methods. The model allows for the time taken for blast vibration wavefronts to travel from each blasthole, and has been successfully used to explain the reason for directional increases in both air and ground vibration in certain situations. The model has been used to identify wavefront reinforcement due to the propagation of air vibration and ground vibrations in certain situations. The paper includes a throw (or cast) blasting case history which provides multi-station evidence of the strong directional nature of wavefront reinforcement.

Jan 1, 1995

By Aspinall T. O, Bell L. C

Increased awareness and stricter enforcement of regulatory requirements for adequate rehabilitation of surface mining sites has made environmental planning an essential part of strip mine planning. Rehabilitation is site specific and should be based on data which relate to that site. Cost-effective spoil pile design to minimise erosion is an important part of rehabilitation. Spoil pile design is an integral part of strip mine design. QCT Resources Limited has provided a postgraduate scholarship toward research in this area. The controlling factors of spoil pile design are post-mining land use, drainage requirements and degree and rate of erosion. The extent to which mine design is controlled by these factors is determined by regulatory requirements. To plan acceptable rehabilitation programs, erosion processes must be accurately modelled, and a range of erosion prediction models are available. Useful prediction models can be placed in two categories with the first category containing soil loss prediction models which can be used to predict the amount of soil lost from an area over a short or long term basis. Models in this category include the Universal Soil Loss Equation (USLE), Water Erosion Prediction Project (WEPP), Griffith University Erosion and Sedimentation System (GUESS) and Chemical, Runoff and Erosion from Agricultural Management Systems (CREAMS). The second category contains topographic evolution models which give an indication of the long term morphological development of a formed surface subjected to erosion processes. Models in this category include "Topog", Willgoose's Physically Based Catchment Evolution Model and Areal Nonpoint Source Watershed Environment Response Simulation (ANSWERS). The USLE has been used in the agricultural field for soil loss prediction. To apply the equation to mine sites in Central Queensland, it is necessary to understand the factors affecting erosion at the sites. This understanding should allow the variables of the equation to be quantified. The rainfall factor applied in the USLE is independent of engineering design or soil management techniques. The factor of spoil erodibility is dependent on the material's physical and chemical properties and can vary from site to site. In the equation, the topographic factor, cover and management factor and conservation practices factor can be varied by design to reduce erosion on rehabilitated areas.

Jan 1, 1991

By M Battersby, F Parra, S Sanchez-Pino

Pneumatic flotation, as developed by Dr Rainer Imhof, has been applied in commercial beneficiation operations since 1987. Over 85 flotation cells have been installed in more than 30 operations, successfully beneficiating a wide range of minerals. Pneumatic flotation is however still considered as a non-conventional flotation process. Due to its highly selective nature in operation it has generally found its market in difficult applications where conventional flotation equipment has struggled. Compa±fa Minera Huasco (CMH) operates an iron ore pellet plant in central Chile. CMH desired to produce a low silica pellet for the export market where the SiO2 grade should not exceed 1.5 per cent. It is common practice in other countries to float quartz from hematite with relative ease. However, the silicates contained in the magnetite ore of CMH are only present as quartz in small quantities and the major undesirable silicates are difficult to float. CMH spent considerable time on developing a reverse flotation process and a reagent suite to try and reduce the silica content to acceptable levels. However, extensive laboratory and pilot plant tests with conventional mechanical tank type cells and with column cells failed to produce the required reduction in impurities. A series of tests with pneumatic flotation cells indicated that this type of flotation technology could achieve the required silica target. A 500 tph Imhoflot pneumatic flotation plant was subsequently constructed and successfully commissioned by CMH, making it one of the largest iron ore flotation plants in the world. This paper details the background and testing that was undertaken by CMH which led them to choose pneumatic flotation as the preferred process and compares the test results with that achieved in the industrial plant.

Jan 1, 2005

By Coppock BW

Sintering of lead and zinc concentrates is practised by Sulphide Corporation Pty. Limited to provide both desuiphurised lump sinter feed, for simultaneous reduction to zinc and lead in the Imperial Smelting Process blast furnace, and sulphur dioxide gas for sulphuric acid manufacture. From November, 1969 a 20 percent increase in production rate has been obtained through improvements in operating technique. A gradual increase in bed permeability was achieved by modifications to the feed mix conditioning equipment and by improving moisture control. However advantage could not be taken of the higher permeability to increase sulphur elimination because the hardness of the lump sinter decreased. Higher throughput, better quality sinter and more stable sintering conditions were however made possible by simultaneously: 1. reducing segregation and compaction in the sinter bed, by narrowing the discharge opening of the main layer feed hopper, 2. reducing the sizing of sinter returns to give a closer size spectrum of particles in the feed mix, and 3. increasing the sulphide sulphur content of the feed mix to give higher bed Temperatures.

Jan 1, 1972

By Ellery B. I

Field investigations recently undertaken by Utah Development Company (U.D.C.) have been developed to allow the assessment of ground conditions relevant to the use of large bucket wheel excavators for pre-stripping overburden. "Bucketwheel diggability" predictions were made on the basis of a wedge test which was perform- -ed in the field on nominal 150 mm diameter drill core samples. Specific separation force (calculated from the wedge test results) for different rock horizons were theoretically related to the excavation rates of various sized bucketwheels, i.e., "bucketwheel diggability". The specific separation force was shown to vary with lithology, structure, weathering and moisture changes. By correlating these features between boreholes, an overall assessment of bucketwheel diggability was then made. The approach adopted to assess bucket- wheel diggability incorporated various levels of investigation. Initially, a reconnaissance stage provided information from widely spaced 150 mm cored holes to compare and contrast areas with differing bucketwheel digging char- -acteristics. The following stages progressive -ly added to this information, until finally, between hole correlations, allowed calculations to be made of volumes of materials of similar

Jan 1, 1981

By M Dohm, L Pretorius

This paper provides a brief historical background to the approximately 12-year project that led to the revision of rope selection factors in the South African regulations, thus providing the ability to hoist economical payloads from single lift ultra-deep shafts. The efforts over the past 20 years have led to the revision of the legislation pertaining to rope selection factors, the redesign of rope constructions to meet the required duties associated with ultra-deep shafts, codes of practice for the design, operation and maintenance of winding plants, and a code of practice for the condition assessment of winder ropes. As a consequence the Moab Khotsong ultra-deep hoisting system could be developed and installed, with the assurance of predictable performance. Access to deep orebodies by means of single lift, ultra-deep shafts has a critical impact on the life cycle costs and efficiencies of ultra-deep mining complexes. A brief description of the main components of the hoisting system at Moab Khotsong is presented. An in-depth review of the development process applied to ensure a stable, safe and cost-effective rope construction for the ultra-deep Moab Khotsong shaft follows. The paper concludes with an overview of the experiences gained during the installation and commissioning phases of the winder, as well as operational and maintenance issues.

Jan 1, 2005

Answers to the questions "which rocks contain diamonds?" and "which indicator minerals should diamond explorers look for?" are no longer so easily obtained, now that diamonds are known to occur in lamproites and various types of lamprophyres, as well as their traditional source of kimberlites. One way of isolating those factors (host-rock"geochemistry, geographical or tectonic location, xenolith minerals, etc.) which are most critical in determining the diamond potential of a given pipe, is a detailed and critical re-examination of the huge volumes of accumulated data on kimberlites, lamproites and related rocks. A large analytical database to this end has been set up on an Apple Macintosh II microcomputer using the quasi-relational database management system 4th Dimension. Currently, it contains data for up to 90 major and trace elements, isotopic ratios and contained mineral compositions for some 4,000 rock specimens from all over the world. Many experiences in setting up this database are probably relevant to other geologists setting up their own systems: they include determining the relationships between data items; the advantages of codes over free text in representing categorical variables such as rock types; the need for rigorous error trapping and data validation; and the problem of missing data values and ambiguities thereof. The working system is now being used in a rigorous statistical assessment of the criteria which distinguish diamondiferous from non-diamondiferous rocks.

Jan 1, 1989

By Miles M. J, Sandy D. A

It has long been known that drilling and blasting operations have a direct influence over productivity and costs of subsequent operations. If mine management is to effectively optimise blasting operations, good information is required on the operating costs of each of the affected operations, together with knowledge of how they are influenced by blasting. In practice it is not possible to do enough repeats of a full scale production blasting experiment to make a statistically significant analysis of the results. By monitoring each blast and subsequent operations in as much detail as possible, enough data will be available to effectively measure the effect of blasting on costs. This gives management an insight into the blast performance and is the first step towards optimisation. An Integrated Blast-related Cost Reporting System has been developed at the Rossing Mine Open Pit, which calculates the total mining cost for each blast. In assessing the total mining cost for each blast, use was made of an.integrated planning and management information system to collect relevant production variables, current operating costs and survey data. An automatic image analysis system was employed to measure the fragmentation of the blasted material in the back of haul trucks. A shovel monitoring system is also under development for use in assessing the muckpile diggability and, in conjunction with an appraisal of shovel component reliability, to estimate the maintenance cost under various digging conditions.

Jan 1, 1990