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By A J. Tucker, L Bottomley

The principle objective of development mining is to create thoroughfares that can be accessed by personnel and machinery for the entire life of an underground mine. The drill and blast process, being the primary method used when creating these thoroughfares, needs to be able to adequately fracture the rock to be removed whilst at the same time minimising any damage that may be sustained to the rock surface that remains. This process of damage prevention is known by a variety of different names including smooth blasting, sculpture blasting, contour blasting and controlled blasting. Whilst the terms are different, the objective is the same and that is to reduce and better distribute the explosive charges to minimise stressing and fracturing of the rock beyond the neat excavation line. The process in this report will be referred to as perimeter control blasting. This paper will discuss the benefits of using perimeter control blasting in a development mining operation and the theories that govern how these blasting techniques work. The methods that are used to implement perimeter control blasting will also be addressed, paying particular attention to how these blasting techniques have evolved, spawning new and improved perimeter control products. Finally some attention will be given to the process of optimising perimeter control blasting in any underground mining operation.

Jan 1, 2005

By Young D. R, Webb I. D

The hydro-chlorination of Fe2O3 and Fe304 has been investigated in the range 850-950¦C in order to elucidate the role of iron in the segregation process for nickeliferous laterites. The kinetics of Fe203 chlorination using 20% HC1 - 80% N2 gas mixtures is consistent with a single-stage structure control model, whereas Fe3O 4 exhibits a two-stage reaction mechanism. Oxygen potential measurements using a CSZ probe located above the bed and X-ray powder diffraction results confirm the proposed reaction scheme. When a serpentine nickeliferous laterite (1.03% Ni - 11.7% Fe) was chlorinated at 900¦C with a 20% HCl - 80% N2 gas mixture it was found that the iron oxide in the ore was extracted in a similar manner to the synthetic iron oxides. Also, it was found that the nickel extraction from the ore paralleled that of the iron and the tests indicated that for the major part of the extraction, the solid nickel species were in equilibrium with the gas phase. The recovery of nickel from laterite ores by the segregation process has been investigated by a number of workers and several extensive reviews of the literature associated with this field have been published (Iwasaki, 1972; Canterford, 1975; Wright, 1973).

Jan 1, 1987

SOME notes on the works of the Electrolytic Refining and Smelting Company of Australia will no doubt be of interest to members of the Institute, more especially as much of the work is new to Australasia.As many of the members who may read this paper have not been in a position to visit works of this kind, and are consequently not thoroughly acquainted with all the operations carried on, the author has taken the liberty, in some cases, to enter into explanation which would otherwise be unnecessary.The works are situated at Port Kembla (New SouthWales), about fifty miles south of Sydney, and are approachable both by rail and water. The Government has recently built a low-level jetty upwards of five hundred feet long, and intends installing at an early date an electrically operated portable crane to facilitate the handling of material to and from the boats. Thi.s will mean a considerable reduction in the length of time that boats are laid up at the jetty. There are also under construction two breakwaters, which, when complete, will materially assist shipping operations. The works as they exist are capable of turning out 1200 long tons of refined copper per month. It is gratifying here to note the unqualified success with whichthe E.S.A. refined copper met with on first being put on the market.

Jan 1, 1911

By Thompson AG, Cadby GW

The New Austrian Tunnelling Method (NATM) is a proven concept for the safe and economic construction of underground facilities. This is especially true for tunnelling activity where changing ground conditions are often encountered. However, the principles central to the NATM have gained only limited use within Australia, presumably due to the measurement process inter- fering with tunnel driving and the cost associated with instrumentation and interpre- tation expertise. The design and operating principles of two basic instruments are explained together with laboratory simulated test results and suggest- ions for use in an integrated NATM style approach to underground excavation and construc- tion. The two instruments monitor load in rock reinforcement and deformation in rock or primary and secondary linings. The instruments may be fitted with a miniature display module which outputs the measured parameter in engineering units directly. The design of the sensing components allows the instruments to be installed in various configurations suitable for routine performance monitoring, quality control, support element testing or detailed investigations. The display module which reduces the need for instrumenta- tion expertise should suit contractors and allow performance data to be obtained which quickly may be used to modify support procedures to suit ground conditions. When complemented by convergence measurements the devices enable most facets of the NATM to be implemented.

Jan 1, 1987

A laminar-flow furnace technique was used to study the combustion of 37-53 µm size fraction of Woodlawn copper concentrate containing 7.4 per cent zinc, 5.0 per cent lead and 22.5 per cent copper. Factors studied included the effect of time, temperature and the distribution of volatile elements between the panicles and the fume. Air was used for most of the work but a few tests were carried out using 1 per cent oxygen in nitrogen. Chemical analysis, X-ray diffraction, and scanning electron and optical microscopy of polished sections were used to characterize the reaction products.When the concentrate was combusted at low temperatures (800-900°C), the fume was rich in lead. At higher temperatures, this was diluled by increasing amounts of zinc and copper. 70 per cent of the zinc, 60 per cent of the lead and 40 per cent of the copper were found in the fume after oxidation at 1400°C. Lead, zinc and copper were present in the fume as anglesite (PbSO4), zincite (ZnO) and cuprite (Cu2O) respectively. The major phases present in the panicles were magnetite (Fe3O4) and/or cuprospinel (CuFe2O4), with some zincite and cuprite.Elemental copper was found in the particles oxidized in 1 per cent oxygen. Possible vapour species responsible for the vaporization are discussed.

Jan 1, 1985

By Chappel R. A, Fishburn B. R

The Eastern Distributor Tunnels - the first major road tunnel project in Australia - are the preferred solution to traffic congestion problems, when compared with alternatives, in this inner urban environment. This is because of the reduced impact on residential housing, the improvement of the existing environment, less restrictions on future developments, and a reduction in noise and pollution. Developments leading to a tunnelled solution, traffic needs and reasons for route location are discussed. Criteria for design of tunnel alignments and geometry are described, including the restraints imposed by surface connections on profiles and grades resulting in low rock cover at tunnel portals. The main geotechnical restraints are a major weathered dyke at the shallow large span underground fork and the weathered Ashfield Shale capping the Hawkesbury Sandstone at a portal. Rock cuttability and excavation methods are discussed. Roadheader machines are the most suitable for the varying shallow arched cross sections required and the tunnel lengths involved but the use of blasting in special situations cannot be ruled out. Initial support for the major tunnel lengths will be provided by rock reinforcement in conjunction with shotcrete. Steel ribs are proposed in areas of low cover and weak ground. Final support will comprise an insitu concrete lining. Construction concepts and special tunnelling methods required at the shallow underground forks and tunnels are described.

Jan 1, 1987

By Sen G

An amount of explosives, whether it be cylindrical, spherical, etc in configuration, with a hollow cavity in one face or end is known as a hollow or shaped charge. When this charge is initiated, a focussing of explosive energy will occur within this cavity. This focussing, or concentration of detonation products creates an intense localised force greater than just the simple detonation of a conventional explosive, (without a hollow cavity). If this hollow cavity explosive is directed against a target material this concentrated force is capable of creating a deeper penetration than the same amount of explosive without the hollow cavity. If a metallic liner material is used in the hollow cavity, upon detonation of the explosive this liner will form into a high velocity penetrating jet. Depending on the explosive type and the liner material's configuration the jet tip can travel up to 10 km/s. Linear shaped charges were developed using the abovementioned shaped charge concept but instead of being formed about an axis, they are elongated and constructed along the principal axis. Therefore instead of creating a narrow circular penetration jet, it forms a thicker planar cutting jet ideal for linear cutting purposes. Using Linear Shaped Charges (LSC) for pre-splitting is expected to result in more accurate directional fracture propagation, while minimising lateral micro fractures in the surrounding rock mass which is required to remain undamaged.

Jan 1, 1995

By Chaves AP

This paper describes an investigation on the surface properties and mechanisms involved in the agglomeration of iron ore. For this purpose, an organic binder (carboxyl-methyl-cellulose (CMC)) was used in substitution of bentonite, the classic binder in iron ore concentrate agglomeration. Recently, a renewed interest of the iron ore producers in Brazil to replace bentonite for an organic binder, because of the economy that can be achieved in the, blast furnace operation. These savings are mainly due to the lower aluminum silicate addition which decreases slag volume and the improved pellet metallurgical properties which have the potential for lowering hot-metal production costs. Also organic binders are effective at lower addition levels, which results in lower storage and transportation costs. It is very important in Brazil because of the vast geographical area since transportation is made mainly by truck. Another advantage of organic binders is that they have low ash contents, and therefore most of the binders bum. off during the pellet firing operation. Previous studies have demonstrated the possibilities of the use of CIVIC, but in addition to its high cost, the pellets presented improper behavior at high temperatures or when prepared with high moisture levels. In the investigation here described, these problems have been solved through the addition of other reagents to CMC.

Jan 1, 1993

By Sans H

The geostatistical Discrete Gaussian (DG) model is demonstrated to be capable of providing an effective means of implementing change of support for Enterprise-style mineralisation and thus providing reliable global recoverable resource estimates. At Enterprise, sample grade distribution proves to be highly positively skewed, therefore significant deskewing of the histogram and reduction of variance occurs when going from sample to block support. The DG model was experimentally tested in'the Southern Primary Zone (SPZ) at Enterprise, where high anisotropy ratios and pronounced short range structures are observed in variograms. The experimental test was run for a change of support for which the variance reduction was. approximately 60 per cent. This reduction is similar to that predicted by Krige's Relationship ('the volume-variance relationship') for the practical situation of a change of support from 5 m vertical blasthole samples to 3 m x 8 m x 5 m selective mining unit (SMU) blocks. The DG model was found to correctly predict the grade tonnage relationships for a wide range of cut off grades. The experimental test indicated that, given a representative histogram and variogram, the DG change of support provides a computationally efficient and practical means of reliably assessing global mineable resources at the early stages of a mining project. Further, it allows a range of selectivity strategies to be meaningfully and comparatively considered prior to mining.

Jan 1, 1995

As this district is so far distant from the other mining centres and its mode of approach so circuitous, I am afraid that many residents of other portions of the Commonwealth never think of paying this" Australia's Silver City" a visit, to learn personally the many and various lessons everywhere available, and to become familiar with the really wonderful and interesting features and deposits (which pature has so lavishly bestowed in the mineralogical world) yet seemed to almost ignore or overlook when disposing of topogr,aphical beauties of landscape and vegetation) unless professional or business duties require their presence here. So it is to those whose life is necessarily spent in other parts of the States where they answer their call of duty, and yet feel an interest, either for business or other reasons, that my paper is specially addressed and prepared, and for that reason I witl endeavour to make my remarks more of an explanatory than a dictatorial nature. I feel sure that there. are many members of our Institute who are much more familiar, and have had many more years' experience in the various methods of timbering, filling, and ore extraction, etc., than myself, but I hope that over I6 years' experience in connection with mines and engineering works, the last six of which have been spent in Broken Hill, where, I have been very closely connected.

Jan 1, 1903

By Jones M

The concept of precise, accurate timing with Electronic Delay Detonators (EDDs) was first seriously addressed in the mid-1980s and much was made of the cheapness and profusion of digital watches in terms of the likelihood of EDDs also being cheap and easy to produce. Ten years later, with every major explosives company and many electronics groups having instituted projects to capitalise on the promise of these devices, production devices are still to come into general use. In South Africa, Expert Explosives units have been used in most applications during proving trials and more recently for production blasting in underground ring stoping and open cast coal. The outcome has been valuable learning both as to the benefits and technical requirements for electronic delay blasting, and especially, safety aspects. Examples are shown of production blasts which utilised the power of EDDs. It is evident that it is not delay accuracy alone which determines the value of these systems, but the whole robustness, flexibility and ease of delay allocation when harnessing blast engineering knowledge. Muckpile movement and shape, fragmentation and vibration frequencies have shown to be greatly influenced by designs which can be implemented no other way. The flexibility of a system and the power of the software controlling it are crucial in capitalising on blasting potential, which lies in integrating control of blast timing with other developing electronic Technologies.

Jan 1, 1995

Bureau of Medical Inspection, Broken Hill, New South Wales.INTRODUCTIONFor a considerable time it has be3n realised that the pathological changes produced in human lungs by the inhalation of free silica varied, not only according to the amount of silica inhaled, its particle size and the period during which it was inhaled, but also according to other mineral elements which might be admixed with the fine silica dust and inhaled along with it, or inhaled subsequently to the silica containing dust. It was observed that, in many instances, these admixed dusts tended to inhibit the action of the free silica in causing injury to the lungs, as well as the development of certain complications, whilst in other cases it was felt that certain substances could actually accelerate the tissue damage caused by the silica.A fresh impetus to the problem of the prevention of the development of silicosis was given when, in 1937 and 1939, Denny, Robson and Irwin published papers entitled "The Prevention of Silicosis by Metallic Aluminum." Working at the same time at the Saranac La.boratory, and quite independently, and using a colloidal aluminum hydroxide, Gardner arrived at the same conclusions as Denny, Robson and Irwin, namely, that in experimental animals the development of silicotic changes could be prevented if eithertogether with the silica, or subsequent to its inhalation...

Jan 1, 1946

Mathematical modelling of continuous rotary vacuum filtration has been limited by the wide range of variables and the absence of connecting equations linking the variables. The filter type and size, mechanical design and predicted performance are generally determined by laboratory leaf tests on representative samples of slurry, or plant samples from an operating filter. A model has been developed which includes the major process variables such as slurry feed rate and concentration, cake thickness, wash water and air flow rates, to predict the filter production throughput, cake moisture and residual solubles. Where possible the model incorporates well established equations relating form filtration, washing and drying rates of the filter cake. Where an equation has not been formulated, standard curve fitting programs have been used to establish an algorithm. The theoretical equations and the derived algorithms are defined in the text. A major feature of the model is that operators, metallurgists, process, mechanical and instrumentation engineers become more aware of the interaction of process variables, the principles of the equipment design and its limitations when operating at peak performance. The model has specific application in the alumina industry where a high moisture content of the filter cake can increase chemical losses and energy costs, and in the coal industry where overseas companies are insisting on lower export coal moistures.

Jan 1, 1989

By Regan R

Appin Colliery mines the Bulli Seam with a gas composition of 98.5% methane and 1.5% carbon dioxide. Relaxation of the strata generally occurs to below the base of the Wongawilli Seam, some 40 m below the Bulli Seam, and approxim- ately 125 m above the Bulli Seam, for longwall face widths of 135 m or more. Previous exper- ience showed that when longwall faces were mined for a distance approximately equal to the face width, the mine ventilation could not provide sufficient dilution due to methane emissions from the underlying measures. Postdraining downholes were drilled to intersect the Wongawilli Seam below the operat- ng longwall. These holes were connected to an underground to surface gas range and various suction levels were applied to improve gas drainage. The resulting gas flow rates and purity from all the downholes were regularly monitored and peak flows in some holes exceeded 160 1/sec. The surface plant drained almost 20 million m3 of gas for the period July 1981 to January 1982 at an average methane purity of approximately 70%. Distinct patterns emerged for different downholes from curves illustrat- ing their variations in flow rate with distance subsequent to passage of the longwall face. The difference between free flow characteristics and those obtained with the application of

Jan 1, 1982

By Dierling D. H

The paper briefly describes the mining system employed on Western Deep Levels for the past 20 years. The negative aspects which gave rise to a new mechanized method of mining are discussed. The sequence of events leading from the Mine's first attempt at trackless mining in 1980 to the present day in-stope project is presented. The original justification for this project and the in-stope trackless mining method is described in detail. The results to date are evaluated and the original rationale for going in-stope trackless mining questioned. A totally new mining philosophy for Western Deep Levels, whereby major geological disturbances are left in situ and longwalls re-established and mined using trackless mining machinery is described. The economics of this mining method are discussed. Trackless mining machinery can also be put to good use within the conventional longwalls in a new method of mining using Load Haul Dumpers (LHD) in reef drives. When the instope trackless mining project commenced in 1983, it was stated that expansion to any significant degree with diesel powered vehicles could be ruled out and electrically driven alternatives would have to be developed. This issue is discussed and the Mine's decision to expand with diesel powered vehicles explained. Finally, the extent to which trackless mining is likely to be seen in the 1990 s at Western Deep Levels is discussed.

Jan 1, 1986

By Bothe C

Froth flotation processes use different surface properties of the minerals to be sorted. In an aqueous environment the hydrophobic mineral attaches selectively to air bubbles and is lifted to the surface of a separation vessel, while the tailings settle towards its bottom. Besides the surface properties, the hydrodynamic conditions play an important role. With respect to the hydrodynamics the flotation process can be divided, for simplicity, in two sub-processes. The attachment of hydrophobic particles to air bubbles, the so-called mineralisation, demands a large number of collisions and therefore high turbulences. The phase separation however needs a deterministic movement of both the particle-bubbles-aggregates and the tailings particles and therefore a quiescent flow field. The optimisation of the overall process requires a separation of both sub-processes, especially when fine particles have to be sorted. In conventional mechanically agitated flotation cells both sub-processes take place in the same turbulent volume. For this reason they suffer from a decreasing selectivity with decreasing particle size. In flotation columns the mineralisation of air bubbles and the phase separation are performed in a quiescent environment. This results in high concentrate grades and at the same time in a very slow attachment kinetics, which must, especially for fine particles, be counterbalanced by a long residence time of the slurry.

Jan 1, 1993

By J K. Claflin, S R. La Brooy, A M. Claflin

Rotary kilns have been in service in the gold industry to regenerate carbon for 65 years. At the time oxide ores with gold head grades of 8 to 10 g/t were being treated. Carbon could be regenerated adequately at 650°C and solution losses were less than 1%. Forty years ago, research indicated that heavily fouled carbon from flotation circuits had to be held at 750 to 850°C for ten to twenty minutes for full reactivation (Avraamides and La Brooy, 1987), gold head grades were typically 5 g/t and solution losses typically 0.02 ppm – still less than 1%. In 2017 it was determined (Claflin et al., 2017) that a residence time of less than 1 minute at 750°C can be adequate to reactivate carbon fouled with organics sufficiently to achieve 0.005 ppm solution losses in a flotation tailings leach plant.With the potential for discovery head grades to drop below 0.6 g/t, solution losses of 0.02 ppm represent over 3% loss. Tight operation of the whole carbon circuit is required to keep gold solution losses below 1% going forward.There are alternatives to a rotary carbon kiln, e.g. vertical kilns of which the Minfurn, Rintoul and Combustion Air kilns are examples. The alternative kilns can be heated using electrical heating elements, induction, and microwave. These kilns can operate successfully under the right conditions, however, they are almost exclusively for small carbon throughputs and are not suitable for the large carbon advance rates that are required to process low head grade ore deposits. Large throughput carbon kilns are are almost exclusively fossil fuel fired rotary kilns and the subject of this paper. In the view of the principal author, a fossil fuel fired vertical carbon kiln is preferred to a rotary kiln, however, it is not currently used in the industry.Thermal regeneration of activated carbon has a major impact on gold recovery in the carbon circuit. The carbon kiln and associated equipment constitute 3 to 5% of the capital cost for an oxide processing plant and up to 10% of the capital cost if flotation tails are leached. Despite the capital cost and impact on recovery, the carbon kiln is often poorly selected, operated and maintained.Six years ago Ausenco embarked on the Carbon Kiln Initiative to reduce solution gold losses. This body of knowledge has been published in a series of papers culminating in this paper on how to:1. Select a kiln appropriate for the flowsheet;2. Maintain the kiln to achieve design operation; and3. Operate the kiln to minimise costs and maximise reactivation.CITATION:Claflin, J K, La Brooy, S R and Claflin, A M, 2018. Carbon kiln selection, operation and maintenance, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 251–274 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Budden J. R, Rhodes M. K

Bacterial oxidation technology was successfully applied in a mine site pilot plant for the treatment of refractory gold concentrates. The bacterial culture was proven capable of selectively breaking down the refractory sulphide minerals to release the gold. Gold extractions greater than 90 per cent were possible when oxidised concentrate was leached with cyanide solution. The pilot plant was designed using data scaled up from laboratory testing and sized for transport by standard vehicles. The bacterial culture used to break down the refractory gold-bearing mineral was a natural mixed culture able to withstand temperatures up to 55¦C, thus making the technology particularly suitable for use in Australian and in some North American gold mining regions. The pilot plant was operated at the mine site over a six month period. Performance of the bacterial oxidation technology under site conditions was as predicted from the laboratory testing. It was demonstrated that the culture was robust under normal site condi- tions and that the culture could withstand wide variations in the feed and the operating conditions, while still achieving satisfactory oxidation levels. The technology was able to be utilised by site operators and supervisors with minimum intervention. Design data for a commercial facility was collected for a number of different concentrate samples and a feasibility study completed. Estimated capital and operating cost have been obtained.

Jan 1, 1991

By P Moynagh

"A plan is critical but on its own it is a bit one dimensional, the three dimensions critical to success over the long-term, through changing economic, geological and management conditions are:the quality of your planning an ability to see and adapt to change a disciplined continual improvement/learning system.This paper will examine how a number of major Australian resource companies have used a commitment management system to connect the ‘theory’ embodied in plans (whether mine, project, maintenance or training plans) and immediate reality ‘practice’ as experienced by supervisors and their crews in the workplace. This paper draws on management theory embodied in management operating systems (MOS), Lean, Theory of Constraints and Six Sigma approaches to continuous improvement and a good dose of real world experience. It is embodied in the statement: ‘successful organisations are driven by a series of commitments that people make to each other and deliver on’.Citation:Moynagh, P, 2016. Everyone Has a Plan Until They Get Punched in the Mouth – Creating Trust, Commitment and Results in Tough Times, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 293–299 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By Weller KR, Lim IL

The high pressure grinding rolls is one of the few new comminution devices that offer substantial savings when compared with traditional crushing and grinding circuits and with SAG milling. The machine has been well accepted in the cement industry, but mining companies have been more cautious in adopting this technology, partly because of wear and availability problems, and partly because of uncertainties in designing circuits which will deliver the power savings without complicating downstream processing. This paper addresses the latter problem by providing a model structure for predicting power draft and throughput from measurements made with small pilot scale high pressure rolls. Three existing models for predicting product size distributions are assessed and suggestions made for future work. The model structure comprises a power equation, incorporating measurements of torque and rolls speed previously used by the authors. Transport through the mill is assumed to be plug flow. Throughput is governed by the equilibrium gap between the rolls, which is determined both by machine settings and the physical properties of the feed material, including its size distribution. Therefore some form of physical testing in a model machine is required to determine throughput parameters. Results from copper and nickel ore experiments covering a wide range of machine conditions are presented and compared with model predictions. Model assumptions are discussed and directions for future work Suggested.

Jan 1, 1993