Search Documents

In the process of mining the lower seam in a multi-seam operation, a lot of oblique fract- ures appeared in the upper seam which was in the equilibrium zone. These fractures closed soon after the lower face line passed. Despite the occurrance of some degree of undulations, and and step-like unevenness, the upper seam was subsequently extracted without difficulty. When attempting multi-seam extraction, from the height of the equilibrium zone, the minimum distance between seams in ascending mining should be predicted. By analysing roof con- vergences data and the geometrical configuration of subsidence profile, it was found that the minimum safe distance for ascending multi-seam mining depends on the mining height of the lower seam and the properties and structure of the inter-stratified rocks.

Jan 1, 1986

The Century zinc-lead-silver deposit has a geological resource of 118 million tonnes averaging 10.2% zinc, 1.5% lead and 36 g/t silver. It lies approximately 250 km NNW of Mt Isa in NW Queensland, Australia, and is hosted by middle Proterozoic age siltstones and shales of the Lawn Hill Formation. Within the orebody, most mineralisation occurs selectively within black shale units as fine grained sphalerite and galena lamellae with minor pyrite and siderite. The black shale units are separated by weakly mineralised sideritic siltstone horizons. The deposit is unmetamorphosed and only weakly deformed, displaying excellent lateral stratigraphic and grade continuity.

Jan 1, 1995

By Y Gu

The Mineral Liberation Analyser (MLA) employs the technologies of scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The use of backscattered electron images to define phase boundaries produces very high resolution image analysis and subsequently detailed and accurate particle images and data output. The mineralogy, elemental deportment, grain size, liberation characteristics and mineral associations of a large number of samples can be described. The MLA uses a comprehensive set of analysis methods to meet a wide range of applications. The data from ore characteristion projects completed during feasibility studies are important aids for effective plant design. The MLA can be used to establish variation in the mineralogy of an orebody, identify and quantify the deportment of deleterious elements, and provide valuable information to support comminution and flotation test work. In established plants the MLA data is an important component of plant survey work and monthly composite samples. Changes in feed characteristics and/or operating conditions can be monitored and solutions to any deterioration in recovery and grade performance found. The MLA has extensive applications in the minerals industry. Rare and precious metal samples can be accurately measured using high-resolution grey-scale images. Several new measurement techniques have been developed to perform rapid searches of a large number of samples to provide efficient and accurate analyses of fine-grain, low concentrate material. Quantifying the mineral variability in mineral sands operations is essential to maximising grades and recovery. The MLA produces particle-based data on density, mineralogy, size and shape and has developed measurement techniques to provide the elemental quantification required for the characterisation of these deposits. Nickel sulfide ores can be analysed to provide modal mineralogy, elemental deportment and liberation and locking data. The low-grade and variable nickel mineralogy of these deposits makes the use of quantitative mineralogy an essential component of maximising returns. Coarse particle measurements preserve the in situ textures of ores and support flotation and breakage test work for feasibility studies. The deportment of penalty and bonus elements can be quantified and the association and grain-size data can be used to identify potential separation issues.

Jan 1, 2006

By Ghose AK

Design and selection of support systems for longwall faces call for in-depth know- ledge of strata mechanics and in particular of strata-support interactions. The paper presents the results of field investigations and analysis of a difficult-to-cave roof using powered supports under a massive dolerite sill in Central India using a state- of-the-art datalogger system. The mechanised long wall face was equipped with 4/680 tons chockshields operated on the IFS mode using a 300 KW DERD shearer. The datalogger system was capable of storing data simulta- neously in 32 channels. The paper describes the monitoring system and the monitoring programme. The system provided useful information on support behaviour, build- up of leg pressures and face convergence during an intense dynamic periodic weighting phenomenon which destroyed the integrity of almost half of the face supports. At this point, the face had advanced by about 197 metres from the barrier. The paper outlines a post-mortem analysis of this dynamic event and provides a critical evaluation of the data collected for understanding strata support interaction and the behaviour of the massive sill in the overburden.

Jan 1, 1992

The Kangiara mine is located within the Middle to Upper Silurian Hawkins Volcanics of the Douro Group near Yass, New South Wales. The deposit is a po1ymetallic type within a rhyolitic tuff.The ore minerals comprise pyrite, sphalerite, botryoidal sphalerite, galena, chalcopyrite, marcasite, tetrahedrite, bismuthinite, bismuth, silver, electrum, chalcocite, covellite, and digenite. The gangue minerals are quartz, barite, calcite, and the host rock. Locally sericite occurs.Several distinct ore types can be recognized, mainly on the basis of their macroscopic textural appearance, and it is inferred from these general features that the mineralization had a submarine volcanic-sedimentary origin similar to that of the Kuroko deposits in Japan.

Jan 1, 1976

By Cooper P. G

I he Electrolytic Refining and Smelting Company (ER&S) has oper- ated a copper smelter at Port Kembla, NSW since 1908. The feasibility of modernising the smelter was recently studied and external influences were shown to have a substantial impact on the project economics. Profita- bility is determined by the relative magnitudes of treatment charge income earned from processing raw materials and the operating costs incurred. Treatment charges are usually denominated in U.S. dollars and are deter- mined by market forces in the world copper industry. ER&S is no different from other Australian manufacturing industries in that it must maintain its competitive position by controlling costs. The modernisation project seeks to achieve this through new technology and improved labour Productivity.

Jan 1, 1988

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

By Alwan M

At Binebase mineralisation is hosted within an andesitic Neogene volcaniclastic succession on Sangihe Island, Indonesia. Two major alteration types occur; an initial widespread phyllic assemblage of quartz -illite with chlorite, smectite, gypsum and pyrite, and a superimposed quartz - barite - sulphide assemblage. The phyllic alteration arose from a neutral to weakly acidic hydrothermal solution of greater than 200 degrees C, and the quartz - barite - sulphide assemblage arose from a cooler slightly more acidic fluid. This second alteration event is interpreted to have selectively replaced permeable volcaniclastic breccias and coarse lithic tuffs within the altered sequence. Gold and silver mineralisation is associated with the latter alteration, and is locally controlled by the degree of silicification and sulphide abundance. The sulphides present are pyrite, covellite and chalcopyrite. The sulphides are very fine grained with colloform and framboidal textures and were deposited contemporaneously with the bulk silicification of the coarse sediments. A large portion of the mineralised rock has been oxidised to a quartz - barite -limonite - goethite - jarosite assemblage.Coincident gold, silver and antimony geochemical soil anomalies gave the best correlation with anomalous gold and silver grades in bedrock as identified by drilling. Resistivity proved a reliable geophysical method for delineating zones of silicification.

Jan 1, 1990

Lightweight polymer grids have recently been introduced to the mining industry. They are currently being used for roof and rib control, longwall shield recovery, safety guarding or barricade, highwall screening, internal reinforcement of gunnite/shotcrete applications, sub-base reinforcement, construction of steepened slopes, retaining walls, mine reclamation (i.e. erosion control, turf reinforcement), and in numerous mining waste related projects. These polymer mining grids utilize a strong, lightweight polymer, usually special grades of polypropylene or polyethylene. High tensile strengths are achieved by molecular orientation of these polymers in the manufacturing process. The first step in the manufacturing process is to extrude the polymers into thick continuous sheets. These sheets are then punched, and drawn into open grid structures. Aperture size and configuration are controlled by the geometry of the punched hole and the degree to which the grids are stretched. The drawing process is the key to the molecular orientation required for the tensile strengths. These long chain polymer molecules in their natural state have a random orientation. When stretched, the molecules are pulled into a parallel alignment, thus creating a lightweight product with tensile strength comparable to Steel.

Jan 1, 1992

By Taylor R. N

Flow simulations have been performed on the flash-smelting burners currently used at KNS. This paper presents studies of the heat transfer between gas and particles at the burner exit. Gas and particle temperatures, velocity and concentration profiles of the two-phase flow are calculated by the mathematical model. The predicted gas temperatures have been favourably compared against values measured by thermocouples placed near the burners in the flash furnace. The predicted particle temperatures are also reasonable when compared with the measured temperatures.

Jan 1, 1992

An effective production control system should maximise recovery of economic material from the resource. To do this, internal waste must be accurately delineated and efficiently removed. Achieving this is most difficult in low grade blocks just above and just below the cut off grade, where ore:waste separation follows assay or statistical, rather than geological boundaries. Difficulties arise from sampling errors, configuration of the economic mineralisation, and local variations in geology. Mine bench parameters and mining equipment size apply further constraints to the actual field separation of the ore from the waste. At BCL, management of the resource starts with an effective orebody model for planning, scheduling and ore:waste prediction. Ore production from each mining location is reconciled with concentrator tonnage and grade, and the reconciled grades are compared with the planning orebody model to highlight any Differences.

Jan 1, 1986

By Pradhan GK

Blasting is one of the most important operations involved in surface coal mining. The removal of over-burden waste in surface coal mines of India had experienced many improvements in terms of blasting, explosives selection, blast design, equipment selection, deployment. etc. Two case studies of very large surface coal mines have particular importance in their blasting operations. Both these units have been equipped with large capacity excavating machines, hauling units and also have some difficult mining situations. Blasting is done in benches in close proximity to human dwellings and over coal seams developed by underground methods with problems of high wall stability etc, as well. The various steps taken to improve the blasting operations ensure smooth operation of the equipment to meet the targetted coal production.

Jan 1, 1991

In the late 1970's Western Mining Corporation, Exploration Division considered the purchase of a major multi-element spectrometer as an adjunct to our existing atomic absorption spectrophotometers. The analytical work proposed for the unit included barium, uranium and rare earth elements from Olympic Dam, uranium, sulphur, vanadium and strontium on Yeelirrie type deposits, major element and whole rock analysis, multi-element analysis of samples from the laterite, chromium and manganese exploration programmes and tin and arsenic analysis. These were all analyses that were not readily or easily performed by flame atomic absorption or were where we expected that a simultaneous multi-element instrument would be an advantage. Also the turnaround times for the commercial laboratories was considered unacceptably long for some determinations. Other factors, important when considering the spectrometer were the ability to ensure confidentiality of results and the ability to assign our own priorities and not to have to rely on commercial laboratories. The two techniques considered were X-ray Fluorescence Spectrometry and Inductively Coupled Plasma Optical Emission Spectrometry. The decision was made in favour of the ICP unit for several reasons. The ICP fitted in with our existing methodology, ie samples digested for atomic absorption or colorimetric techniques would also be suitable for ICP analysis and vice versa. The technique was suitable for water samples and for major element analyses and for rare earth elements. X-ray fluorescence spectrometers were installed at the Kambalda and Belmont laboratories and would be available to us for routine checking and for elements not suitable for ICP analysis. The final consideration was price. ICP was considerably cheaper than XRF.

Jan 1, 1987

The Indonesian province of Papua is a remote jungle-clad region covering the western half of the mountainous island of New Guinea. Despite being relatively under-explored to this day,Papua is home to the greatest mineral success story of the 20th century. The Grasberg/Ertsberg minerals district atop the central dividing range contains the worldÆs largest reserve of both copper and gold (Freeport-McMoRan Copper and Gold, 2002). With large mines at Ok Tedi,Por gera and Lihir,and many well-delineated resources such as Frieda River,Wafi and Hidden Valley, neighbouring Papua New Guinea,the eastern half of New Guinea has enjoyed sustained exploration campaigns for gold and copper since the mid 1960s. The combined Grasberg and PNG exploration successes can be measured in terms of ounces of gold produced over the last decade versus available landmass,conf irming the island of New Guinea and surrounding islands as a world-class destination for gold explorers. Yet despite this obvious regional prospectivity and the profitability of the Grasberg operation, a sustained exploration effort in the Papua province in Indonesia has not been achieved. Periodic political constraints, poor infrastructure, high costs, operational challenges, social and environmental concerns and lack of immediate exploration success often impact exploration investment decisions. Accordingly a lesser number of mineral occurrences have been documented in Papua compared to those seen along tectonic strike in geologically similar Papua New Guinea.

Jan 1, 2004

FOR some time past keen interest has been shown in both America and South Africa in the mining drill-steel problem. This interest has extended to Australian mining fields, and Australian drill users, ever desirous of increasing efficiency, are vigorously attacking the problem. The writer has recently been engaged in the investigation of the problem on two of ,the biggest mining fields in Australia, and has formed very definite conclusions concerning the causes of many drill-steel casualties. He puts these views forward in the hope that they may be of interest to, both drill manufacturers and drill users. The subject is here dealt with mainly from the aspect of the properties of the steel and the modifications of these properties whensubjected to various manipulations. It is generally admitted that the drilling machine has greatly increased in power and efficiency during recent years, and the consequence is that the machine is demanding better service from the steel. This is being impressed on the drill users by an increase in steel casualties. This fact has led many mining people to the view that the machine has developed so rapidly that the steel maker has not been able to keep pace, and that consequently the steel isfailing by fatigue 0:1; so-called crystallization. This view is rather depressing. The writer, on the other hand, is inclined to discountenance fatigue as a serious factor under good normal working conditions where the steel is carefully manufactured and supplied to the user under suitable structural and sound conditions, and has subsequently received kind treatment at the hands of the drill sharpener and the drill user.It is not reasonable to attribute failures to fatigue until it has definitely been proved that the steel is fundamentally sound and is in the best structural condition to resist the stresses it is called upon to withstand, and, this being so, that all fundamental principles of...

Jan 1, 1923

A contract for three 20 ft diameter vertically mounted axial flow fans of the same aerodynamic design, was placed by Mount ]sa Mines Limited in 1963. The hydraulic blade pitch changing mechanism, the method of blade fabrication, and the roll out centre casings are features of these fans. Protection devices and fan control are designed for unattended operation and remote control. The erection and commissioning of the fans during 1964-65 is described.

Jan 1, 1967

A new plant for grinding limestone was built at the Risdon Works of the Electrolytic Zinc Company of Australasia Limited to meet increasing process demands expected to reach 150 tonne/day of ground limestone. Plant specifications included open- circuit wet grinding, a single ball mill, a feed sizing of minus 6 Tyler mesh, a product sizing of 100 per cent minus 200 and 95 per cent minus 325 Tyler mesh and for the plant to be unmanned during normal running. Main features of plant and equipment are described; grinding performances given, as well as operating experience since commission- ing of the plant in March, 1976.

Jan 1, 1977

Answers to many questions arising in the different phases of exploration, estimation and production of a mineral deposit, can be found in the geostatistical theory of G. Matheron. It is shown that all these questions regarding sample size, number of samples, shape of drilling pattern can be answered as soon as the continuity of the mineralization is quantitatively characterized by means of a variogram. Next a formula which gives the variance of the error associated to any estimation procedure (i.e., any method and any sampling pattern) is given. Applications to the computation of the standard error of the'mean for various sampling patterns are shown, as well as how to use the formula to simulate several possible sampling strategies and choose the best one. Altogether it is shown how to answer the often heard question, "what happens if such and such sampling procedure is used?", rather than giving an hypothetical "optimal" solution.

Jan 1, 1976

By C Morley, B Costello

In 2002 the Argyle Diamond Mine upgraded the process plantÆs recrush circuit to include a High Pressure Grinding Roll (HPGR), or High Pressure Rolls Crushers (HPRC) as they are termed in the diamond industry. HPGR have generated considerable interest over the last decade, though there are still technical/processing unknowns to its effectiveness as a primary diamond ore crusher.The upgrade of the Recrush circuit at Argyle Diamonds has gone a long way to answering some of the key questions, and thus it has reduced the unknowns to a level more acceptable to the industry.This paper focuses on the results from the HPRC at Argyle, in particular the performance of the studded wear surfaces, comparison of energy efficiency against traditional quaternary cone crushers and the resultant increased liberation. Issues that have arisen, including edge wear of the studded surfaces, will be discussed and the steps taken to reduce this issue are presented.

Jan 1, 2004

By Kavetsky A, Scott A

As well as breaking and moving rock, blast energy sets up a seismic wave in the ground which can cause significant damage to rock structures and buildings and disturbance to human occupants. This seismic ground vibration is potentially most damaging when its dominant frequency coincides with the resonant frequency of a structure, leading to high amplification factors between the input ground vibration and the resulting structural response. This paper outlines methods of identifying the resonant frequency of structures. It also describes a practical numerical method for the modification of blast designs to reduce the ground vibration energy in critical frequency ranges. The method is illustrated with two recent case studies.

Jan 1, 1990