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From the mid-1970s ZC Mines at Broken Hill had a policy to increase ore production rates at progressively lower head grades. In the mid-1980s the mine suffered crippling losses at a time of low metal prices. An important contributory factor was the inherent geological distribution of metal grades in the seven defined ore lenses. Grades are bimodal, and perhaps, trimodal, in each ore lens. There is a tonnage deficiency in the critical cut-off grade zone of 7-10% Pb+Zn. Lowering the cut-off grade introduced siliceous and pyrrhotitic material which resulted in significantly poorer metallurgical performance. This example shows that the mine geologist needs to know the grade distribution of the orebody and to convey clearly the downstream implications of changes in the head grade.

Jan 1, 1990

By Restarick C. J & Stewart P S B, Kelsall D. P

Over a four-hour period of steady plant operation samples were taken at regular intervals from points within the grinding and flotation circuits. Size fractions of each composite sample were analysed for lead and zinc values and a comparison made of the behaviour of the lead, zinc and gangue minerals, size by size throughout the whole circuit. Analysis of the breakage behaviour using dynamic mathematical models gave the rates of breakage of each size fraction of each main component. Simulated grinding experiments showed that the main grinding circuit had sane reserve capacity. In the lead flotation circuit all lead values between 150 mesh (Tyler) and 5 microns had excellent flotation characteristics, and a major proportion had a high rate of flotation which was practically the same for all sizes. Increase in overall lead recovery would require improvement of the flotation behaviour of ultra-fine lead minerals. These were slow floating and were responsible for approximately half the lead losses in the final zinc concentrate and one third of the lead losses in the final tails.

Jan 1, 1980

The Fosterville goldfield, situated 25 km east of Bendigo, Victoria was at its peak between 1894-1910 with some 47 600 ounces produced (Figure 1). Since that time intermittent mining and tailings retreatment was undertaken until Bendigo Gold Associates delineated a viable resource and commenced an open cut heap leaching operation in early 1991. Unfortunately they encountered financial difficulties and Perseverance Exploration purchased the mine in April 1992. Perseverance operated a successful heap leach operation nearby Nagambie, 100 km east of Fosterville. Based on its acquired heap leaching experience, Perseverance Exploration was able to instigate operational changes to create a successful small gold heap leach operation. The major change was the using of the original multi-use leach pad as a single-use leach pad. The available data allows for a comparison of the two operating systems.

Jan 1, 1994

By Arit I, Adisoma G

General Limit Equilibrium Method (GLE) and Janbu's Generalised Procedure of Slices (GPS) are two limit equilibrium methods in slope stability analysis which satisfy all equilibrium conditions. Numerical difficulties associated with these metho

Jan 1, 1998

By Johnson N. W, Munro P. D, Pease J. D

The Lead/Zinc Concentrator of Mount Isa Mines Limited processes complex fine grained ore from the Isa and Hilton silver-lead-zinc orebodies, producing lead concentrate, zinc concentrate and (until 1996) a low-grade middlings (LGM or bulk) conc

Jan 1, 1997

By Tagawa H

In Japan, geological condition do not only vary in a wide range of strata but are also extremely complex with the existence of faults and aquifers. With respect to rocks, in particular, it is very rare that homogeneous rocks are distributed uniformly. In general, geological conditions are distributed in a wide variety, ranging from earth, sand, soft and medium rocks to hard rocks. Under these geological conditions, when planning of the tunnel construction is to be made out, either blasting method or tunnel boring machines must be selected taking into consideration the geological structures along with the designed tunnel route,' possibility of encountering aquifers, hardness of rocks anticipated and also, the adjacent environ- mental conditions. In the process of select- ing an excavation method,, it is important to make a comparative investigation between the above two methods considering the advantages and disadvantages with regard to the respective operating efficiency, economical efficiency and the conditions and scope of application as well. Furthermore, in addition to these considerations, the recent environmental restriction, which does not allow the blasting in the surroundings of residential areas, must also be taken into account. Because of this, in some cases there is no alternative but to use a static excavation method or a tunneling machine even when these are less efficient than blasting.

Jan 1, 1987

By Jones J. P, Arriagada J, Scherpenisse C. R

A recently-developed model is used as a tool to optimise the design of blasts used to create final walls in large open pit mines. The use of this tool has allowed present blasting practice and proposed designs to be evaluated to predict the likely extent of rock damage behind the final wall. The evaluation of the damage is dependent on the predominant local geology. Modelling of damage using the software allows the potential zones of rock damage to be evaluated under the following criteria: I . the extent of new fractures formed in the intact rock mass; and 2. the distance to which dilation and extension of existing discontinuities and pre-existing fractures will likely occur. The computer model has been used to examine present blasting practice and to estimate the damage induced by final and intermediate rows of blastholes. The results of current practices are presented in a visual form that allows simple comparisons to be made for any proposed changes in design. To confirm the predictions of the modelling, physical measurements are being undertaken at selected mines to quantify damage behind blast patterns, and experimental programs are underway to measure near-field vibration, or shock, levels. The computer modelling software is being used to qualify and improve the design of final rock slopes in large surface mining excavations, and to provide site engineers with well-defined design criteria for consistency in design. The model is seen to be just one of many tools which are being used in large open cut mining operations to gain an improved understanding of blasting and blast control.

Jan 1, 1995

By Murray C. G

A database of over 1300 earthquakes has been used to investigate the relationship between seismicity and tectonics in two areas of eastern Queensland and NE New South Wales. These areas have been monitored by several networks that were installed primarily to monitor seismicity associated with the impounding of large reservoirs. Events that occurred prior to the installation of these networks have been excluded from the analysis because they have large uncertainties in location.Seismicity in SE Queensland and NE New South Wales is concentrated in the coastal regions. Activity also extends off the coast of Queensland and beyond the continental shelf. The coastal activity is mainly within the New England Fold Belt. An area of the fold belt overlain by the Clarence-Moreton Basin is also active. There is an area of activity near St. George that correlates to the Wunger Ridge. Fraser Island and the adjacent onshore area, near Maryborough, are notably aseismic.Within the New England Fold Belt there is a NNW trending zone of concentrated activity that includes the South D'Aguilar Block and the Esk Trough as far as Gayndah. The Nambour Basin, the Gympie Province, and the southern portion of the Yarrol Block are significantly less active.Composite focal mechanisms of several groups of accurately located earthquakes in SE Queensland indicate predominantly reverse faulting. This faulting is the result of the crust being compressed horizontally in a NE-SW direction.Activity in the Burdekin Falls Dam area of central eastern Queensland is confined to the Drummond and Bowen Basins. There is also significant activity offshore from Townsville and Bowen.

Jan 1, 1990

The light microscopic study of the physical structures of coal and associated mineral matter is an important technique in providing information on the characterisitics and possible behaviour of coals in industrial processes. However the ultrafine nature of coal and mineral particles together with the limits of resolution of the light microscope restrict such studies. Scanning electron microscopy (SEM)with its better resolution and higher magnifications is the means by which further information on coal properties can be obtained. An associated energy dispersive X-ray specrometry (EDS) method allows non-destructive in-situ chemical analyses to be carried out at the same time.

Jan 1, 1989

By Armstrong M, Kleingeld W. J

Current low prices for many metals mean that deposits have to be mined at high cut-offs (relative to their mean grade), which means that only a small percentage of mining blocks are above cut-off. Worse, at such high cut-offs, the blocks above cut-off are usually not grouped into convenient clumps for mining; they tend to be split into small isolated patches that are difficult to reach and hence expensive to extract. Companies wishing to acquire mineral properties have to be able to work out quickly what percentage of blocks are above cut-off and what can effectively be mined given the mining method envisaged. Moreover they need this information within a relatively short-time. The work presented here relates to typical South African gold mines (ie tabular orebodies) but the long-term objective is to develop tools for quantifying the impact of reserve breakup at high cut-offs for a wide range of underground mines including those that are not tabular. The mining method and the sampling procedure determine whether ore blocks can effectively be located and extracted economically. This project studied the impact of these two factors on the recoverable reserves for Witwatersrand gold mines. In order to be repeatable, the tests were done on numerical models of the deposit obtained by geostatistical simulations. To ensure realism, the orebody model and the mining scenarios were based on a specific mine. The recoverable reserves (ore tonnage above cut-off, the corresponding metal quantity and the average grade) were calculated for a wide range of cut-offs for four mining scenarios, as well as for the base case of free selection: ò Scenario 1: Blocks are taken if their true grade is above cut-off and if they are accessible from a raiseline (no information effect, no marginal blocks). ò Scenario 2: In addition to the accessible pay blocks, adjoining marginal blocks are taken (no information effect, + marginal blocks). ò Scenario 3: Blocks are taken if their estimated grade is above cut-off and if they are accessible from a raiseline. Here the estimator is the average of the face samples (information effect, no marginal blocks): ò Scenario 4: Accessible pay blocks are taken if their estimated grade is above cut-off. Adjoining marginal blocksare also taken (information effect, + marginal blocks). ò Free selection: All blocks whose true grade is above cut-off are taken irrespective of their accessibility. The results can be presented in different ways, for example by plotting ore tonnage above cut-off versus cut-off grade, or metal tonnage above cut-off versus cut-off grade etc. As expected, this shows the hierarchy between the five scenarios from the free selection base case to scenario No 2 (true accumulations, pay +

Jan 1, 1995

By Nott M. C

The oxidation of xanthate collectors to xanthate/dixanthogen results in a higher hydrophobicity of sulphide minerals surfaces due to the action of dixanthogen. This higher hydrophobicity can be proved on a fundamental level by examining the st

Jan 1, 1994

By Daniels E. J, Morgan W. A

In response to the increase in consumption of galvanised steel for automobiles in the last decade and the problems associated with remelting larger quantities of galvanised steel scrap, a process is being developed to separate and recover the steel and zinc from galvanised ferrous scrap. The zinc is dissolved from the scrap in hot caustic using anodic assistance and is recovered electrolytically as dendritic powder. The dezinced ferrous scrap is rinsed and used directly. The process is effective for zinc, lead, and aluminum removal on loose and baled scrap and on all types of galvanised steel. The process has been pilot tested for batch treatment of 900 tonnes of mostly baled scrap. A pilot plant to treat continuously loose scrap, with a design capacity of 48 000 tonnes annually, has been in operation in East Chicago, Indiana since early in 1993. The first 450 t of scrap degalvanised in the pilot plant have residual zinc below 0.01 per cent and sodium dragout below 0.01 per cent. Use of degalvanised steel scrap decreases raw materials, environmental compliance costs, and opportunity costs to steel- and iron-makers. Availability of clean degalvanised scrap may enable integrated steel producers to recycle furnace dusts to the sinter plant and EAF shops to produce flat products without the use of high quality scrap alternatives such as DRI, pig iron, or iron carbide. Recycling the components of galvanised steel scrap saves primary energy, decreases zinc imports, and adds value to the scrap. The quantities of zinc available by the year 2000 from prompt and obsolete automotive scrap will approach 25 per cent of zinc consumed in the major automotive production centres of the world. Zinc recycling from galvanised steel scrap, either before or after scrap melting, will have to be Implemented.

Jan 1, 1993

By Townsend IJ

The Upper Triassic Leigh Creek Coal Measures which include a number of seams of sub-bituminous black coal are preserved in four small intramontane basins. The largest is Telford Basin, 1,000 m in thickness. The coals, of variable thickness and quality, are mined by open cast mining methods and utilised for generation of electricity at Port Augusta. The combined proven and indicated reserves are about 100 million tonnes.

Jan 1, 1975

The basic methods to remove material from underground mines are to: convey continuously, batch in trucks, or batch in a shaft hoisting system. A critical aspect in shaft hoisting is accurately batch loading the conveyance or skip. During the 20th century, the almost universally accepted method of loading was via a measuring flask. A measured quantity of material was filled into the flask as the conveyance traveled through the shaft and then, when the conveyance arrived at the loading position, it was ædumpedÆ into the skip for hoisting. Two skip loading conveyor systems have been developed in Australia: BHP BillitonÆs Cannington Hoisting System, installed in 1996, is believed to be the first conveyor loading system designed for two skips. Two parallel conveyors were installed with a two-way gate controlling feed onto each belt. Cannington was ideally suited to conveyor loading as the very high ore density and relatively low production rate required a relatively small volumetric storage capacity on the weighed belt. Newcrest MiningÆs Telfer Hoisting System, which is to be commissioned in 2005, consists of a single slewing conveyor loading each skip with 32 tonnes of ore. The development of this system eliminates the two-way transfer, improves the accessibility and minimises the excavation required. While every hoisting system must be considered on its merits, conveyor loading offers significant advantages to the Mining Industry in the 21st century.

Jan 1, 2005

By H Utama, hi, A Suw

PT. Indo Muro Kencana (PT.IMK) is gold and silver mine located in Central Kalimantan province, Indonesia. Mining activities in PT.IMK is conducted in Bantian pit area by applying surface mining method and using combination of excavator and hauler (articulated dump truck and rigid haul truck) as the transportation for ore to the crushing plant and waste material to the waste dump. Current blasting practice is ore-waste blasting. Ore-waste blasting is the term where the ore and waste rock are blasted in the same blasting process. Blasting is conducted by using nonel initiation system. By multiple pits operation, monthly powder factor is varied from 0.23 kg/t to 0.27 kg/t. Emulsion blend with density 1.15 g/cc is used as bulk explosive. At this stage, the concept of geoblast is proposed as an engineering tool for Drill and Blast engineering practice in PT.IMK. In addition, there is a need to maintain rock fragmentation by blasting, to maintain monthly powder factor, and to maintain excavator’s productivity. Next, the concept of scaled depth of burial (Chiappetta and Treleven, 1997) and the concept of blastability index (Lilly, 1986) are proposed as geoblast’s tools to improve blasting practice in PT.IMK. It is expected that rock fragmentation by blasting, explosive consumption and excavator’s productivity will be maintained by integration of geoblast and drill and blast engineering. Furthermore, the objective of this paper is to integrate geoblast and drill and blast engineering in order to create an engineering guideline in PT.IMK. Additionally, blasting trials with air decking application is proposed in order to support the geoblast’s improvement. It is planned that these blasting trials will be conducted in 2022. In conclusion, it can be seen that integration of geoblast and D&B engineering in PT.IMK is relevant to improve current drill and blast current practice and applicable to maintain rock fragmentation by blasting.

Nov 29, 2022

By T Ireland, S Eratne, W Newns, P Spies

The approach to risk management during the procurement of major projects often has a significant outcome on the ultimate delivery of a project. The NZ$1.4 B Waterview Connection project is the largest and most complex project yet undertaken by the New Zealand Transport Agency (NZTA) and the procurement process for an alliance contract was refined to provide compliance with the International Tunnel Insurance Group (ITIG) Code of Practice for Risk Management of Tunnel Works (TCoP). The principle of shared risk within an alliance incentivises a common understanding of project risks prior to finalising the alliance agreement and therefore enables superior risk management through design, construction and beyond. Risk management practices need to be instigated well in advance of commercial phases, so that commercial competition does not lead to a significant elevation of project risk. In particular the practice of gaining commercial advantage by taking on a potentially unmanageable level of risk is one of the outcomes to be avoided by the TCoP.During the procurement phase the NZTA placed high value on design and construction mitigation measures proposed in order to address ground risks, as is appropriate for a major tunnel project. In order to achieve alignment on the level of geotechnical risks an Alliance Geotechnical Baseline Report (AGBR) process was developed.This paper describes the measures taken during the procurement process to achieve certainty with respect to outcomes and minimise project risks whilst also achieving value for money. Refinements to the procurement process to ensure compliance with the TCoP prepared by the International Tunnel Insurance Group (ITIG) are described along with the AGBR process applied as part of a suite of measures to achieve a successful procurement outcome.CITATION:Ireland, T, Spies, P, Eratne, S and Newns, W, 2014. Risk management and use of a geotechnical baseline report for a competitive alliance procurement?process, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 553–562 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

In Mount Isa voltage and frequency fluctuations caused. by haulage shaft operation gave considerable difficulties with the initial application of Atomic Absorption Spectro-photometry.The methods used to stabilise the various units ' have been described.- Some other difficulties and the means used to eliminate or reduce them together with a-modified burner design are also discussed.

Jan 1, 1963

By R Rankine

Backfilling with paste fill has been an integral component of open stoping at Cannington since commencement of operations. Efficient paste filling is critical to successful mining of the Cannington orebody. There has been a deliberate and ongoing effort into research and development of paste, with the focus being to optimise the performance and cost of paste. This paper describes the latest research and operational issues of Cannington paste fill.

Jan 1, 2005

By McNabb KE, Ward B, Dyer G

Roof conditions at Southern Colliery, the second longwall mine to be established at German Creek, were found to be much stronger and more massive than at the earlier longwall mine on the lease. Investigations were made to ascertain the level of face support required for longwall extraction under the changed geological conditions. Geotechnical information was provided from drillholes and highwall exposures. Downhole geophysical logs, notably the sonic velocity log, were used to obtain a distribution of the major lithological units over the mine area. A representative type section of the strata and geomechanical properties was compiled to form the basis for numerical modelling. Two-dimensional finite element methods were used to predict strata movements and chock loads under cantilevered roof conditions. The model incorporated a 6.3 in thick roof beam either bonded or detached, with either a 2 in or 5 in overhang. The solid rib, immediate roof, chock support and goaf were modelled as distinct parts, in addition a front abutment stress profile, derived from three-dimensional displacement-discontinuity analysis, was superimposed on the model.

Jan 1, 1992

The operation of quarries for the production of crushed stone and aggregates, depends heavily on rock blasting efficiency, which usually represents a major share of total production costs. After investigating the causes of this situation, a series of technical aspects have been detected, and they are described for the purpose of contributing to the minimization of costs, which also reduces the effects of blasting on the environment. Utilization of empirical design methods, of inadequate explosive types, and of erroneous drilling pauems with respect to rock properties, are the main factors to be corrected, as a consequence of poor engineering criteria, with scarce use of computational methods and field instrumentation. Several concepts of blasting optimization are pointed out, and their application to industrial operations in a Portuguese limestone quarry indicated clear trends for the reduction of production costs, as well as some of the deleterious consequences of blasting on the environment.

Jan 1, 1990