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By Matsushita Y, Maeda M, Sano N

The present study was carried out to explore the possible separate recovery of iron and phosphorus (as gas) from BOF slag using graphite crucibles or graphite powders in the presence of a tin bath. The last is consider- ed to enhance the activity of phosphorus in iron reduced from slag or not to absorb the phosphorus vapour readily. When the slag was reduced in a graphite crucible in contact with a tin bath, the phosphorus reduced from the slag was carried away in CO explosively generated by the reduc- tion of iron oxide. When graphite powder was used as the reductant instead, 78% of the phosphorus was removed from slag, only 3% of which was absorb- ed into the tin bath. The rest left the system as gas. Gaseous dephosphorization depends on the area of contact between slag and reductant as cll n.u the amount of the latter. the reduction behaviour was directly observed, using an X ray transmission technique, to conlirm the reaction mechanism.

Jan 1, 1980

By Pinter R

Several major routes connecting Northern and Southern Europe or Asia run through Austria. These highways have to surmount the alpine range which traverses Austria from west to east. In order to ensure safe driving conditions even in winter, tunnels, at times quite long ones, are necessary. Austria now has tunnels totalling 160 km in length. These tunnels are either already in use or just about completed. The Plabutsch tunnel near Graz will be one of the longest tunnels in the world: approximately 10 kilometers in length. It will be put into operation in the summer of 1987. Before construction could begin, soil and rock conditions had to be investigated by means of a test tunnel. Afterwards, excavation was begun to the full 100 m' cross section. The new Austrian tunnelling method with conventional blasting was used for the major part of the tunnel. It was necessary to have such a large tunnel cross section because a fully transverse ventilation system is installed for environmental reasons. In order to avoid air pollution from the tunnel, exhaust fumes are not allowed to escape from the tunnel portals but from two shafts, each with a diameter of 8.5 m. In this way, exhaust fumes must rise 90 meters or 240 meters before they reach the open air and will thus not affect the city. The ventilation system influences the size of the excavation, and especially the size of the ventilation caverns and the air shafts. All these factors directly influence construction and maintenance costs, and an economical optimisation leads to the appropriate dimensions for the excavation.

Jan 1, 1987

The main aim of the conference is to work towards improved useage of steelplant slags which have largely been considered waste mater- ials, This paper summarised investigations carried out on the suitability of air cooled blast furnace slag, blast furnace granulated slag and basic oxygen steelmaking slag as road base materials. All slag samples were obtained from the PortòKembla Works of Australian-Iron and Steel Pty Ltd. Since road making materials are increas- ingly being characterised by use of resilient moduli, the compressive strengths and resilient moduli were determined for road base of the following slags. 1 Air cooled crushed blast furnace slag 2 mixes of air cooled blast furnace slag, granulated slag, and lime 3 mixes of air cooled blast furnace slag,-granulated slag and basic oxygen steelmaking slag. Evaluation of a local dacite (dense medium grained igneous rock, classification rhyolite), generally considered an excellent road base course material, was carried out for use as a reference material.

Jan 1, 1979

By F F. Pitard

Observation from attending many conferences around the world reveals that many people are constantly shifting from the word ‘error’ to the word ‘uncertainty’ without a clear vision of what the subtle difference is. The same applies to a large swath of the scientific literature, in which these two concepts are unfortunately often used synonymously, which is a scientific flaw of the first order. In practice, as demonstrated in the Theory of Sampling (TOS), there are both sampling errors and sampling uncertainties. Sampling errors can easily be preventively minimised, while sampling uncertainty for a preselected sampling protocol is inevitable. P M Gy’s work, supported by G Matheron’s critical reviews, demonstrates beyond any possible doubt that sampling uncertainty cannot be achieved if sampling errors are not preventively minimised by applying very stringent rules that are too often ignored by sampling practitioners. A clarification, in line with the TOS, is presented to mitigate the confusion created by circles favouring the use of uncertainty versus the use of the word error. Both words are very different in nature and scope and they are both necessary in their due place and time.CITATION:Pitard, F F, 2017. From errors to uncertainty – a clarification for proper use by the Theory of Sampling, in Proceedings Eighth World Conference on Sampling and Blending , pp 355–358 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By P M. Dight

Shotcrete usage in declines and developments has become pervasive as operators strive to achieve production improvements. Issues of mix control, fibreload, thickness control, temperature and curing conditions all play a part in the quality control. Often to overcome some of the quality control issues designers over specify the strength requirements in order to meet their operational constraints. Adherence to the standard civil testing requirements of 28 days moist cured at 21ºC without properly calibrating these results to the changing environment underground leads to contractual disputes. There are a number of standard tests specified including cylinder tests, cored tests, beam tests and round determinate panel (RDP) panel tests. The logistics of storing these samples and then transporting them to concrete testing laboratories without due regard to temperature changes with time can influence the results. All the samples can be readily handled by personnel except the RDP panel. The standard RDP panel is 800 mm diameter by 75 mm thick and requires an ITH machine at the mine and a fork lift at the laboratory to move it around. This paper will examine the possibility of a panel which provides scalable results to the standard RDP panel but can be easily handled by personnel and/or tested on site with suitable equipment. This allows for faster turn around and better quality control for the sample prior to testing. This enhances the identification of quality control issues at the mine and improves safety.

Mar 21, 2011

By H Wang, D Wang

Mine dust is the most serious occupation hazard in coalmines. And many coal workers suffer from pneumoconiosis because of long-term inhalation of respirable dust. Reducing the dust concentration of workplaces by effective technical means is an important way to prevent coal worker’s pneumoconiosis (CWP). In order to overcome deficiencies in existing dust control technology for underground mining, especially the disadvantage of water spray technology mounted on roadheaders or continuous miners, the authors developed an integrated dust suppression technology utilising foam for fully mechanised heading faces. This paper presents an overview of the principles, materials, equipment and application of this technology. Among these, a jet type foaming device and a green foaming agent were developed, which can realise the goal of efficient preparation of foam. In addition, an arc fan nozzle used for foam spraying was invented, which can effectively cover and enwrap the dust produced by the roadheader at the cutting point and achieve the goal of efficient utilisation of foam. This dust suppression application of the proposed foam technology was investigated on fully mechanised heading faces. The results show that the dust concentration was cut down significantly with a dust suppression efficiency of greater than 85 per cent, an increase of over 30 percentage points compared to the water spray system. This study demonstrates that this foam technology can play an important role in dust suppression on fully mechanised heading faces, which provides an important method to improve the working environment and protect coal workers’ health.CITATION:Wang, D and Wang, H, 2015. Technology of dust suppression by foam for fully mechanised heading face, in Proceedings The Australian Mine Ventilation Conference, pp 177–182 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By B Young

Variable bench heights, interaction with underground workings and a steeply dipping orebody are challenges faced daily by geologists at Xstrata Zinc’s Black Star Open Cut (BSOC) Zinc/Lead/Silver mine in Mount Isa, Queensland.BSOC has been in operation since late 2004 and was developed to extract the surface extents of the Zn/Pb/Ag mineralisation mined in the underground lead mine. To date many large scale stopes and extensive development drives have been intersected and successfully mined. The stratigraphically hosted orebodies strike in a north-north westerly direction, dipping ~75° west. Ore production from the pit is currently at 4.5 Mt/a.Historically, sampling was conducted using a multiple spear technique from blasthole cuttings. This method proved to be relatively reliable when blasting benches at a consistent height, but a requirement to vary bench heights to safely collapse and then mine through underground workings reduced sample representivity to unacceptable levels.The purchase and commissioning of a production rig which had been converted for reverse circulation (RC) has allowed for the flexibility of a small rig, with the capacity to easily drill 48 m holes while ensuring sample quality. Sample quality is not the only benefit of introducing RC grade control. By collecting grade control data well in advance, informed decisions can be made by planning, drill and blast and mining departments weeks beforehand, rather than hours before firing. Additionally, seeking operational value to offset higher drilling costs has proved positive with benefits including increased confidence in orebody wireframes, accurate tonnage and grade for proceeding five benches along with the ability to representatively test metallurgical response on a tight grid spacing.

Aug 22, 2011

By J Krahn

In designing climate exposed soil structures such as caps and covers over mine waste it is necessary to include the wetting and drying influences of the local climate in order to accurately predict the net water, vapour and oxygen fluxes across the ground surface and through the base of the covers. The most advanced evaporative flux modelling tools currently available to practitioners have been limited to rigorous one-dimensional models (ie SoilCover) or semi-empirical two-dimensional models (ie Hydrus-2D). It is common practice to use the rigorous one-dimensional evaporative flux model results to develop a surface boundary function that can then be applied within a saturated/unsaturated two-dimensional model. However, this is not an ideal situation and results in a further approximation of the real system being modelled. This paper will highlight the use of a new modelling tool, VADOSE/W, which brings existing, rigorously formulated evaporative flux theory into the familiar setting of a two-dimensional model. The model is enhanced for simultaneous two-dimensional oxygen gas transport analysis, which has direct application in the mine waste industry. A key focus of the paper will be addressing the limitations of one-dimensional analysis for cover systems on sloping and hummocky terrain.

Jan 1, 2003

The original and most basic relationship between mining company and explosive supplier was a simple one of consumer and product supplier. The divide between the two was quite clear-cut with neither taking much interest in the activities of the other. The explosive supplier had little understanding or share in the outcome, efficient rock breakage and therefore impact on mining and milling. Likewise, the mining company did not encourage the improvement or development of products. The transactions were limited to product and funds. This environment does not encourage any form of knowledge sharing, trust or optimisation of the mining process.Conversely, there are now a variety of relationships to the point that the mining company may simply be an asset manager whereby all æoperationalÆ aspects are contracted out. For the drill and blast aspect this takes the form of a æRock-On-GroundÆ contract whereby the explosives company takes on design, drill, load and fire responsibilities and is paid a rate per volume of broken rock. This removes the majority of risk to the mining company derived from having to produce broken rock and guarantees the cost of a portion of the overall unit cost of mining. The onus is now on the explosives supplier to break rock to a specification as efficiently as possible.There exist a number of variations between the æbasic supplyÆ and æRock-On-GroundÆ. These contracts may also include value sharing to encourage the explosive supplier to optimise the mining operation to maximise profit.This paper looks at some of the drivers for the change in explosive supplierûconsumer relationships and examines the æprosÆ and æconsÆ of a few of the options.

Jan 1, 2004

By G Hart

As the iron ore/magnetite boom gains momentum, it is particularly important to question established past trends and explore the potential of alternative design options. Traditionally, ‘rule of thumb’ methods have been used to size dewatering equipment. Greater consideration needs to be given to technological advancements and specific throughput testing of each ore body type based on innovative developments.This paper will describe how an innovative approach resulted not only in significant savings in capital cost and site work hours but also delivered a truly optimised design for the thickener duty at Karara. Test work also played a crucial role and a comprehensive test work program on the ore samples showed the scale-up benefi ts of new technology in thickener designs. Working closely with the Karara team during the laboratory testing proved the old sizing theories for iron ore/magnetite processing have been superseded with the knowledge and results of the industry’s newest feedwell technology. Increased solids flux and rise rates in the testing process proved very successful, resulting in signifi cantly reduced thickener sizes and lower capital expense.Mechanical design considerations such as removal of underflow and pump access led to a preference for an above-ground thickener confi guration, and the economics of a completefabrication and installation package favoured steel construction for the thickener units.The ultimate choice of the bolted/fl anged tank methodology provides both economic and timely solutions for the site installation including reduced man power and quick and safe site-work. A benefits comparison between this design and other fabrication and installation procedures will also be analysed in the paper.

Jul 11, 2011

By T Goswami, M Edmondson

Henry Walker Eltin (HWE) are the mining contractors for Gloucester Coal at Stratford mine, which is in an environmentally sensitive area in the Avon Valley, NSW, Australia. Normal blasting at Stratford is done in a æstand upÆ or æbox cutÆ mode to suit the truck and shovel operations. Recently an opportunity of doing a throw blast became available when part of a ramp had to be blasted to accommodate changes to the pit design while not damaging the remainder of the ramp. The objective was to maximise throw into the void in order to minimise excavation costs by reducing the amount of overburden to be moved by the excavation fleet. It was necessary that the best result be achieved while staying within the vibration and airblast limits at a neighbouring property and nearby township. Both objectives were achieved through the application of OricaÆs knowledge of blast design, modelling and i-konTM electronic detonators. The i-kon system was used because of its known benefits in cast blasting and environmental control. The i-kon system provides the blaster with much greater accuracy, control and the flexibility to tailor blast designs. It has been found previously to enhance blast throw and provide cleaner high walls (Brent, 2002). The blast was a success, producing a muckpile with a high degree of looseness and consistent fragmentation, with an average throw to final spoil position of 37.5 per cent. This was achieved without any environmental exceedance. In addition, high speed filming showed that the coal edge had remained largely in place, indicating minimal coal loss. The results exceeded the expectations of HWE Stratford and the overall cost savings to HWE Stratford from this blast were recognised to be substantial. Further throw blasting opportunities at Stratford have been followed using the i-kon system to maximise benefits.

Jan 1, 2003

Gold mineralisation at the Kerimenge-Lemenge prospects is a classical example of myltiple, overprinting events, associated with intrusive-related hydrothermal systems. Repeated emplacement of high level dacitic porphyry bodies (Edie Porphyry; 2.4 - 3.8 Ma) was accompanied by a phreatomagmatic eruption which formed a diatreme-maar complex. Later hydrothermal fluids utilised permeable fault zones and diatreme contacts. Mineralisation took place during two main events. Stage I consists of early quartz - illite/sericite - carbonate phase with associated pyrite-arsenopyrite mineralisation. This phase is zoned from quartz - sericite-pyrite/arsenopyrite in the south at depth, to dominantly manganocarbonate - illitic clay - arsenopyrite- pyrite_s significant base metals in the north and at shallow levels. The majority of known gold (18.1 Mt @ 2.0 g/t Au) at Kerimenge is associated with Stage I activity. The gold occurs primary within the lattice of the sulphides and is metallurgically refractory. Fluid inclusion studies indicate early boiling and progressive cooling and dilution of hydrothermal fluids during the evolution of the Stage I event. Near paleosurface condensation of gases, which evolved off the boiling system at depth, produced abundant low pH bicarbonate fluids. During the waning phases of Stage I activity, these bicarbonate condensate fluids descended down permeable structures and formed banded manganocarbonate veins. High grade non-refractory gold mineralisation during Stage II event is restricted to favourable structures at relatively shallow levels and in the northern regions of the prospect area. Gold in this event exhibits a distinctive Au - Ag - Te -Cu geochemical signature, and is associated with hessite - tennantite - chalcopyrite mineralisation within quartz veining. Alteration and fluid inclusion studies indicate that this style of mineralisation is a result of the quenching of pulses of hot, late magmatic mineralised fluids by the cold condensate waters.

Jan 1, 1997

By Bensley C. N

In June 1995, BHP announced that it would build a Hot Briquetted Iron (HBI) plant and associated beneficiation, materials handling and infrastructure facilities at Port Hedland, Western Australia. This plant, the first direct reduction plant in Australia, will convert beneficiated iron ore fines into metallic iron for briquetting into HBI. The reduction plant will be based on the FINMET fluid bed technology jointly developed by Fior de Venezuela and Voest-Alpine Industrienlagenbau. Electric Arc Furnace steelmakers in the Asia Pacific region will be the principal customers for the product. This paper presents an overview of the facilities to be constructed by the project as well as discussing some particular technology and design engineering issues associated with the project.

Jan 1, 1996

By P F. Hodkiewicz

"Our understanding of mineral resources relies on three basic steps: data capture data interpretation model construction. Until recently, all three of these steps required significant time and manual effort to produce a single resource model for mine planning, typically taking more than a year to progress from drilling to the final block model. Over the past several years, BHP Billiton has been developing innovative workflows in rapid resource modelling projects to significantly reduce these time constraints and make the process more productive by replacing manual activities with automated ones. Rapid resource modelling is the process of combining recently developed off-the-shelf technology with internal technology developments to fundamentally change the way we collect, interpret, model and evaluate geoscience data. Initiatives include automated systems and standardised workflows to make it safer, faster and cheaper to continuously update multidiscipline resource models. Specifically, rapid resource modelling workflows combine: real-time analysis of drill holes and drill samples with downhole tools and hyperspectral scanning systemsautomated interpretation of drill hole intervals based on pattern-recognition algorithmscontinuous modelling workflows using implicit modelling software. This paper outlines technology developments and workflows that provide a more thorough understanding of mineral resources to support faster and more informed strategic, planning and production decisions.CITATION:Hodkiewicz, P F, 2014. Rapid resource modelling – a vision for faster and better mining decisions, in Proceedings Ninth International Mining Geology Conference 2014 , pp 183–188 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 18, 2014

By M Thompson

"The Jaguar concentrator, 60 km north of Leonora, Western Australia (WA), consists of a standard closed circuit semi-autogenous grinding (SAG) and ball mill producing a float feed of approximately 60 micron at 70 t/h. Following comminution, separate copper and zinc concentrates are produced by differential flotation. These concentrates are subsequently dewatered by thickening and then filtration.Separate audits of the Jaguar Operation’s copper and zinc concentrate thickeners were conducted to evaluate their performance, following occasions where site personnel had identified unnecessary loss of copper and zinc concentrate to the thickener overflow. The feedwells were identified as the source of the observed problems due to the following issues with their design/duty:lack of retention time in the feedwell as current design is completely opennot conducive to effective mixing required for efficient flocculationdiameter of the zinc concentrate thickener feedwell was undersize for its duty.To improve the performance of the thickeners, it is planned to replace both concentrate thickener feedwells with a high rate design for their respective duties in February 2016. The audits also identified that the feed system requires modifications with particular importance placed on minimising air entrainment of slurry into the thickener feedwell. Minimisation of air entrainment is hoped to be achieved by providing constant head pressure through installation of weir arrangements in the feedboxes and redirecting each feed pipe so that it feeds tangentially into the feedwell. In addition, improvements to the control philosophy of both thickeners will be made with the installation of an ultrasonic bed level probe and bed mass sensor, in order to make real-time adjustments to the underflow pump speed to maintain steady state operation.Following the feedwell replacement and modifications to both thickeners it is expected that losses of recovered copper and zinc will decrease to undetectable levels. Subsequently it is anticipated that a more consistent, homogenous underflow can be produced for downstream filtration.Citation:Thompson, M, 2016. Concentrate Thickeners Feedwell Replacement, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 273–278 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By D Carroll

Mining of the zinc, lead and silver deposit at the Broken Hill Southern Operations site has been occurring for over 100 years. As a result of this, a significant amount of high-grade ore is now taken from narrow remnant pillars left between old stopes and zones of previously mined ground. Stopes have been filled with either hydraulic fill (also known as ‘sandfill’), cemented hydraulic fill (cemented sandfill), waste rock backfill or a mixture of these fill types.In the last ten years, there has been considerable success mining through narrow pillars where sandfill is exposed in the development face and/or walls using a ‘shell’ support regime, wherein a layer of bolted mesh is sandwiched between two layers of sprayed fibrecrete (25 mm fibrecrete, then mesh and bolt, followed by a final 50 mm layer of fibrecrete). Shell support is also used in very poor, broken, relaxed ground conditions and in areas filled with cemented fill (sandfill with a minimum four per cent cement content).The next stage of innovation has been to develop a technique for mining through old stope voids filled with uncemented sandfill, known locally as ‘contours’ (old cut-and-fill working), an activity where unconsolidated sandfill can run at the face and from the backs. The challenge is to prevent exposed sandfill in the face and the backs from failing before it can be supported.To achieve this, the Southern Operations mine has implemented a technique in which 6 m long spiling bars are used to strengthen and stabilise the sandfill in front of the face. The hollow steel bars are driven in around the heading perimeter in a closely spaced pattern then pumped full of grout. The bars and the grout stabilise the sandfill in front of the face, preventing it from failing into the drive during excavation and prior to further support being installed.A final support system consisting of shotcrete, mesh, bolts and steel girders is installed as excavation progresses. Both the initial and final support systems are essentially passive support systems designed for a low-stress environment (as the stress originates mostly from the mass of unconsolidated sandfill).This process is slow and labour intensive. Fifteen separate cycles of people/machinery are needed to progress one equivalent heading cut (compared to six for a standard fibrecrete- and bolt pattern-supported rock face heading). This slow pace introduces scheduling challenges, but the process opens up parts of the orebody that were previously uneconomical to mine.CITATION:Carroll, D, 2014. Mining through sandfill using spiling bars, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 95–100 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By S Viviers, G Ratner

Ventilation is part of all underground mine operations and is undertaken in order to introduce fresh, cool air to the workings and to remove stale, affected air. It is problematic to obtain efficient and accurate estimates of volume flow and static pressure in the installed operational configuration for the auxiliary axial flow fans.An empirical method was developed to estimate the static pressure and volume flow through a calibrated differential pressure port on axial flow fans. Prior to shipping, each fan is performance tested according to BS 848 (ISO 5801) to establish the fan performance curves. In addition to the standard required parameters captured to fully describe the performance, the differential pressure is measured across the fan rotor to enable correlation with the characteristic fan curve.The method was implemented on a ruggedised tablet PC platform. This compact platform is then used to calculate the volume flow rate from the differential pressure sensor measurement input via a USB port. The result is a real-time measurement of volume flow and operating point of the fan system. This can be used effectively in overall modelling of the mine auxiliary ventilation systems and calculation of system resistance could provide a health indication of the fan and duct system.CITATION:Ratner, G and Viviers, S, 2013. Underground auxiliary ventilation monitoring and diagnostic system, in Proceedings The Australian Mine Ventilation Conference , pp 57-62 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By B Belle

"Mines around the world are inherently and operationally diverse. Current methodologies for the design of mine ventilation and cooling infrastructure involve controlling major safety and health hazards. Globally, it can be estimated that mine ventilation systems from various commoditiescirculate over 150 000 m3/s of exhaust air through shafts. Additionally, over 2 000 000 workersare transported every day through shafts in labour-intensive mining countries like China, India,Southern Africa, and the Americas. A key objective of this paper is to share experiences and provide a case for the revision of ætime-honouredÆ ventilation design parameters based on a benchmarking exercise on design exhaust shaft velocity from various global operations (gold, diamond, platinum, coal and base metals). An active fi eld observation on exhaust shaft velocity has indicated that, regardless of the commodity or continent where the mine operates, almost all life-of-mine (LOM) design parameters provided are in the same range of 20 m/s to 22 m/s, which is not convincing considering signifi cant variations exist in shaft depths, geography, commodity, operating and capital costs. From a due diligence perspective, there are no documented views that are available on the most widely used design exhaust air velocity. Based on the global exhaust shaft velocity data, it is noted that a significant portion of shaft velocities are outside the current design velocity of 20 m/s (some operating up to 30 m/s) and other signifi cant portions of the exhaust shafts operate in the critical velocity range. In the case of Australian coal mines, limited data suggests that none of the mines have ever reached the LOM design exhaust shaft velocity. It is self-evident that when the shafts are not operating at their design quantities either the mine system resistance is low or the ventilation and main fan is operating ineffi ciently. The most common reasons given for not reviewing the shaft system were, ætime-honouredÆ design parameter are being used and cannot be changed, mine fan pressure limits, possible fan blade damage, possible spontaneous combustion risks, leakage or simply did not consider such a possibility. In conclusion, the study has reiterated the historic lessons that a safe and expensive airway should not be utilised uneconomically by circulating too litt le air through it."

Jun 1, 2012

By J Greberg

This paper discusses the use of simulation in the mine planning process. A case study on the Newcrest Cadia East project is presented, and the challenges and possibilities for using simulation as a tool for mine planning and scheduling is discussed.The simulation study presented in this paper was performed during the project’s prefeasibility stage, and focused on the planning and scheduling of the development of panels in the future mine. The Cadia East project will be the largest underground operation in Australia and the first using panel caving. Simulation was used in order to optimise the development of panels; it was mainly used in order to verify the plans for the development process and allocate resources in an optimal way. The work was performed as an iterative process and adjustments to the plans were made according to simulation results. Bottlenecks were identified and different scenarios were tested.The results from the simulation study shows how different operational constraints affect the planned development process and how changes in priorities can be necessary in order to maintain a high development speed. Furthermore the study shows how changes in planned mine layout requires changed strategies, and how this was solved using the simulation tool.In this paper the authors critically discusses the use of simulation in mining operations: what are the limitations and challenges of using simulation as a tool for mine planning and scheduling, what are the benefits, and what do we aim for in the future?

Nov 22, 2011

A new lead refinery with a. capacity of 230,000 tons per year com-menced operation at*Port'Plsie in October, 1959. This plant' superseded the refinery which had operated from 1933 with the advent of thecontinuous lead refining process. The incorporation of new equipment following local metallurgical developments, together with the overseas demand for lead of extremely low antimony content, created difficulties in operating the original plant. The new refinery project was under-taken to cover this disability and to gain the full advantage of the new processes.Desilverising and softening are carried out in units identical in size to those used previously. Metallic'zinc is now recovered from the entire output of desilverised bullion by vacuum distillation. Final refining is then carried out by batch'treatinent with caustic soda yield-ing lead of purity previously unattainable at Port Pirie.These two processes have replaced continuous dezincing by oxidation, a high temperature process which caused large quantities of lead and antimony to be recirculated. As the final stage is a .batch process the product composition can be.checked before casting. Individual batches can be adjusted to produce special alloys to,consumer's specification.Improved casting equipment has allowed the quantity production of pigs of good physical characteristics either as 56 lb bars or 2000 lb pigs. This, together with the high purity of the lead, has assured the B.H.A.S. position in world markets.Automatic control systems have been extensively employed particularly on the vacuum dezincing unit.The anticipated financial benefits have been achieved mainly by a reduction in the tonnage of recirculated materials, a smaller labour force, and reduced maintenance requirements.

Jan 1, 1963