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By J D. Pease, J M. I Tuppurainen, P D. Munro

This paper examines how legislation and regulation can be external drivers of technical change in mineral processing and extractive metallurgy and how the industry can respond. Two examples are considered; the production of copper metal from concentrates and the cyanide process for gold production.The Clean Air Act (1970) in the USA initiated a wave of attempted innovations in the extractive metallurgy of processing copper sulfide concentrates to meet forthcoming standards on sulfur dioxide emissions. Interestingly, a satisfactory technical solution existed (flash smelting and gas capture) but had not been widely adopted.Nearly fifty years later the primary copper industry finds itself with new challenges. One major challenge is how to deal with the increasing level of arsenic in copper concentrates. Most countries impose an upper limit on arsenic in imported concentrate; typically, 0.5% As or less. Higher arsenic concentrates can be blended with cleaner ones to meet the limit, but this tactic cannot be used indefinitely as the average arsenic level of global concentrates rises inexorably. Further, smelters (often in urban locations) cannot be expected to deal with both ever-increasing arsenic in the feed and stricter restrictions on emissions and disposal. A rising “inventory” of primary copper deposits are already constrained from development by high arsenic concentrate. These deposits will need to be developed if future copper demand is to be met. An economic and technical solution to arsenic is needed. The gold industry may also face challenges in the use of cyanide, by far the dominant lixiviant used in gold and silver production. Public perception has driven restrictions on the use or transport of cyanide in some jurisdictions. History suggests that such pressure is only likely to increase. While there are several alternative lixiviants, none can yet match the utility and economics of cyanide.Such important issues will not be resolved by incremental change or new equipment items. They require development of new process technology - a tectonic event rather than an incremental change. It requires sustained effort (and expenditure) over decades and is very unlikely to result from “business as usual” for producers, suppliers or academics. Past major process developments were driven by a dire need for economic survival or by legislative change. What will drive the future changes?CITATION:Munro, P D, Pease, J D and Tuppurainen, J M I, 2017. Technology change by regulation – a cresting wave?, in Proceedings MetPlant 2017, pp 45–58 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By L Dzinza, K C. Corin, M Tadie

The recycling of process water comes with increased electrolyte concentrations that affect water quality, which may in turn affect the flotation performance of valuable minerals (Hirajima et al, 2016). Electrolytes such as Ca2+, SO4 2- , Mg2+ and S2O3 2- have been surmised to have an impact on the action of flotation reagents such as collectors (Ikumapayi et al, 2012). Xanthate collectors are known to play a significant role in imparting hydrophobicity on mineral surfaces to enhance their flotation. The interaction between minerals and xanthates is well known to be electrochemical in nature. Such redox processes may be elucidated by electrochemical techniques. Since the mechanisms involving the interactions between electrolytes in process water with sulfide minerals and the subsequent adsorption kinetics of collectors are not well understood, this study therefore aims to provide fundamental knowledge to unpack the mechanisms involved when electrolytes interact with Platinum Group Minerals (PGMs) and how these interactions may affect xanthate adsorption. The interaction of sodium iso-butyl xanthate (SIBX) in the presence of electrolytes at increasing ionic strength was investigated by rest potential measurements, to explain the impact of electrolytes on the adsorption of SIBX on PGMs in the flotation process. Rest potential measurements for PdTe2 and PdS were conducted in an air saturated 0.05 M di-sodium tetraborate decahydrate solution, in the absence and presence of SIBX and electrolytes. It was found that the existence of sulfide and telluride on palladium affects the mechanisms in which electrolytes interact with Pd mineral surfaces. An increase in the ionic strength of Na2S2O3, CaCl2 and MgCl2, increased the interaction between the salts and PdS, thus decreasing the extent to which SIBX interacted with PdS. An increase in ionic strength for Na2S2O3 increased the interaction between Na2S2O3 and PdTe2 and therefore decreased the extent to which SIBX interacted with PdTe2. Other salts investigated in this study increased the rate of oxidation of PdTe2 with an increase in ionic strength thereby enhancing the interaction of SIBX and PdTe2. This study has shown that mineral type, electrolyte type and concentration all have an impact on the mechanisms that result in the adsorption of SIBX on PGMs.

Aug 24, 2022

By Gordon A. R

The effect of various types of solid carbonaceOlls reductants on the rate of fuming of zinc from lead blast furnace slag was investigated at I250°C.The results of the laboratory experiments indicated that the rate of removal of zinc from slag depended primarily on the volatile matter contents of the reduclants. The effects of fixed carbon, moisture and ash contents were less significant.

Jan 1, 1992

By Klenowski G, Gilmour G. A

The Metropolitan Water Supply, Sewerage and Drainage Board, Perth, has recently con- structed two major sewerage tunnels in the metropolitan area and a further one is under construction. These tunnels were constructed in sand, sandstone and limestone. The Tamala Limestone is a Pleistocene calcareous dune sand which now varies in com position from loose sand to cemented rock. Investigation techniques included surface mapping, auger and diamond core drilling, seismic refraction geophysics and mechanical testing. The variable nature of the ground caused difficulties in all aspects of the investigation, particularly in core recovery and seismic work. The Beenyup Tunnel, 2.25m in diameter and 3440m long was excavated with a Dosco TBM 1800 machine and shield with precast concrete Charcon Universal bolted segment lining. The Burns Beach Sewer Tunnel, 1.27m in diameter and 860m long was hand excavated with precast reinforced concrete lining pipes jacked continuously behind an excavation

Jan 1, 1981

By Lauricella P. F, Hendri D

In the Mesel sediment-hosted disseminated gold deposit, the spatial distribution of hydrothermal alteration is controlled by steeply dipping faults and shallowly dipping lithologies. Hydrothermal alteration of carbonate rock is characterised by decalcification, dolomitisation and silicification. Intense argillic alteration occurs in a laccolithic andesite intrusion adjacent to decalcified and silicified carbonate units. Sulphide minerals (pyrite, realgar, orpiment, stibnite and cinnabar) accompany hydrothermal alteration and precious metal mineralisation. The trace elements Ag, As, Sb and Hg are zoned spatially throughout the deposit. Mesel contains a mineable gold reserve of 7.8 million tonnes at 7.3 g/t Au. Gold mineralisation is preferentially localised in carbonate rocks adjacent to and beneath the andesite intrusion. The ore body consists of a central, near-vertical, high grade "feeder" system flanked by tabular, inward dipping, moderate grade "ouflow" zones. Mineralisation is controlled predominantly by two steeply dipping faults with high grade (>10 g/t) gold zones centred about structural intersections and fault splays. Gold is submicron size and locked in very fine grained (

Jan 1, 1995

By A Bennett, S Arndt

Minerals and Metals Group Pty Ltd (Golden Grove Mine) commissioned a comprehensive study of the life of mine using advanced 3D stress modelling. Essential input into the modelling was the proposed mining sequence, itself the culmination of years of planning and geotechnical experience gained in comparing actual performance to predictions. The modelling approach addressed the whole of mine at a scale of 5 km. There were however several magnitudes of scale to address, from the scale of laboratory testing (0.05 m), to drive size (5 m), extraction size (50 m) and stope size (500 m). Scaling was therefore an integral part of the procedure. The constitutive rock properties in terms of peak and post-peak behaviour varied with the scale. At the laboratory scale, the constitutive relationships for all the main rock units were determined in 3D as well as recovering the in situ stress using the rock memory technique, deformation rate analysis (DRA), whereas at the larger scale the properties were varied to match observations.The modelling, using non-linear analysis to account for rock mass yield and peak-residual strength, demonstrated that if the planned extraction sequence and stope geometry had been pursued there was a high probability of large volumes of excess shear stress being released. However, it was not possible to identify whether the excess shear stress (ESS) will release as one large event or many smaller events. The mining approach was to modify the extraction sequence/stope geometry to manage the hazard. This is where the economic advantage can be realised.Alternatively or in combination with further modelling, the volume identified with the predicted high ESS or energy release could be intensively explored for structures having adverse orientation to the stress change and with sufficient areal extent to release the ESS. The microseismic data can be interrogated for the likelihood of a large event to support the hypothesis of a singular release versus multiple releases of smaller events. If the initial planned extraction sequence had to proceed as designed, changes to dimensioned stopes would be recommended for risk mitigation. Mine planning could as an option, modify the sequence and the extraction could then be remodelled.CITATION:Bennett, A, Arndt, S and Dight, P M, 2014. The economic advantages of detailed geotechnical assessments for extraction sequencing, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 243–250 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By N Cann

In the 10 years from 1998 to 2008 the annual number of fatalities in the Australian mining industry has plateaued (MCA, 2007-08 and abc.net.au website). Despite significant efforts to eliminate fatalities, this is not a comfortable statistic in this very public performance indicator.GHD has been working with the mining and minerals processing industry to identify the key risks that lead to fatalities utilising a semi quantitative risk assessment technique (SQRA®), initially developed to assist Major Hazards Facilities prepare Safety Cases (OH&S, 2007-08) in response to the Longford Incident in 1998 (Dawson and Brooks, 1999).Workshop cross functional teams are assembled from the sites and led by the GHD facilitators to identify the incident types that can have fatal consequences, the causes of those incidents and the controls that are utilised (or could be utilised) to reduce the risk. The risks for each incident type are quantified to produce a risk profile for the facility and the critical controls – the controls that have the greatest impact at reducing the risk of fatality – are selected. These controls are assessed for their adequacy and improvement actions are identified. Prioritisation of the actions is achieved by re-estimating the incident risk profiles.A review has been undertaken using a small sample from the more than 100 individual studies that GHD has completed at mining and minerals processing sites. The five most significant risks reported by sites are:1. Fall from Heights,2. Vehicle/ Vehicle and Vehicle/Pedestrian interactions,3. Entanglement,4. Molten Metals and Materials, and5. Electricity.The most significant reductions in risk identified were found to be by implementing engineering controls. Examples include:1. Chutes to contain splashes and spills of molten materials,2. Redesigning instrument and equipment layouts to take personnel away form high risk areas,3. Designing remotely operated equipment to remove personnel away from high risk areas,4. Proper fire fighting equipment provisions such as deluges around flammable materials, and5. Adequate risk assessment to ensure equipment is designed to handle the real situations and not a design case to meet an arbitrary specification.All of these cases and many of the actions identified in the studies could have been handled through better design and construction early in the life of a project rather than retrospectively fitted after operations have begun.

Aug 8, 2011

By M Lee, J F. Carswell, G Reitsema

"The increased costs of underground mining have continually challenged engineers to identify opportunities for alternatives to common approaches to underground development. Considerations to the design of horizontal and vertical development at the Dugald River mine targeted inclined raise boring to reduce horizontal development, not only to reduce cost, but to allow development activities to focus on other areas of the mine.The mine plan consists of 50 raise bored ventilation shafts, of which 17 have been mined to date with diameters ranging from 3.1 m to 5 m and lengths from 30 m to 200 m. The expected performance and stability of these shafts has been determined using methodologies proposed by McCracken and Stacey (1989) and further refined by Peck, Coombes and Lee (2011). Actual raise performances have been collated and compared to a database of raise bore performances across Australia as presented by Coombes, Lee and Peck (2011), and form a database of raise bore performance specific to Dugald River.Opportunities to further optimise the mine plan and reduce costs have seen the introduction of large diameter-inclined raise bored ventilation shafts to minimise the required lateral development to connect the ventilation circuits. Large diameter inclined shafts ranging between 3.1 m and 4.5 m in diameter have been successfully mined with dips down to 70°, reducing the cost of lateral development by more than $1 million over the next two years.Both technical and operational challenges were overcome in the mining of large diameter-inclined raise bores, including modification of: existing methodologies of assessing shaft wall stability for inclined raises. These included variations of the McCracken and Stacey method and the utilisation of the modified stability number (N’) previously developed for stope performance (Potvin, 1988). both the collar and toe development profiles, including the general set-up of the raise bore drill rig to reduce the operational risks associated with angled raises.Due to their success, inclined raises have been designed for subsequent stages of the life-of-mine ventilation system at Dugald River. This has resulted in significant capital cost savings for the mine.CITATION:Carswell, J F, Reitsema, G and Lee, M, 2017. Vertical and inclined raise bore performance at Dugald River mine, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 313–320 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 16, 2017

Ilmenite (FeTiO3) is the primary global source of titaniumdioxide which is commonly used as a whitening agent in papermanufacture and a pigment in paint manufacture. In WesternAustralia ilmenite is processed by the Becher process (Becher,1963, Becher et al, 1965) where ilmenite particles are feddirectly into the furnace with coal and heated to form acomposite of elemental iron and TiO2. The mechanism of thecarbothermic reduction of ilmenite has been extensively studied(Grey, Jones and Reid, 1973; Jones, 1973; Grey and Reid, 1974;El-Tawil, Morse and Francis, 1993) and is reasonably wellaccepted.

Jan 1, 1997

By R Wynn, T J. Akroyd, C Costa

In an environment of lower zinc prices, falling revenues and reducing zinc feed grades, Century mine implemented a fast-tracked capital upgrade program in less than 15 months. The program was designed to increase ore milling throughput capacity by 20 per cent and optimise the capacity of the flotation plant to increase zinc recovery by approximately 2.5 per cent whilst maintaining final zinc concentrate grade.A key aspect of this program was minimising capital expenditure by better utilising existing capacity and only adding capacity where absolutely required to address critical processing bottlenecks. By gaining an understanding of plant process bottlenecks and future ore blends, and by carefully selecting appropriate technologies for particular specific flotation applications, maximum return on minimal capital investment was achieved.The close collaborative work achieved between the metallurgy processing department and other operational departments on-site was also critical to the success of this project. This work increased the mining and processing capacity of the mine and port site respectively, such that the full value of the process plant modification could be achieved.Capital payback on this investment was achieved in approximately three and a half months.This case study demonstrates the extra value to a mining business that can be achieved through fully understanding the mining/processing value chain and by careful targeted action to address critical bottlenecks in the processing chain from the mine through to the port site.CITATION:Akroyd, T J, Wynn, R and Costa, C, 2014. MMG Century Mine, a case study – maximising project net present value through targeted capital expenditure and process optimisation against a backdrop of falling metal prices and feed grades, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 417–426 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By J Hartog, V Beehan, D Beeson

Treating an ore blend from five different deposits at Newgold’s Peak Gold Mine (PGM) has always been a challenge due to the inherent variability between each of the orebodies.Operating the processing plant at PGM with a ‘normal’ level of process control and a good operations and metallurgical team has allowed the processing plant to achieve above the name plate design at 102 t/h and recoveries in the order of 92.8 per cent for gold and 88.4 per cent for copper.With a company value and culture of striving for continuous improvement, PGM implemented the Manta Cube® system, an advanced process control system, for the semi-autogenous grinding (SAG) mill, gold leach circuit and tailings thickener over a 12-month period throughout 2012 and 2013.The overall benefits of implementing the Manta Cube® system has led to an increase in mill throughput of at least two per cent, improved SAG mill liner life, a ten per cent decrease in cyanide consumption and a reduction in flocculant of at least 30 per cent with no detriment to the gold and copper recoveries.The entire project had a payback period of less than two months, and the combined benefits resulted in an overall increase in revenue of at least $5 million per annum. This is quite significant for a processing plant the size of PGM.This paper describes the methodology, overall results and economic benefit of applying the Manta Cube® system on-site at Newgold’s PGM.CITATION:Hartog, J, Beehan, V, Karageorgos, J and Beeson, D, 2014. Optimisation of the Peak Gold Mine’s processing plant through advanced process control, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 335–344 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

The Newmont Waihi Operations are centred on the Martha mine at Waihi, New Zealand. The mine has produced over 6.6 million ounces of gold from both openpit and underground sources since operations began in 1878. The current open pit operations commenced in 1988 and in the year to 30 June 2002 produced 129,790 ounces of gold at a cash cost of USD122 per ounce. This paper provides an overview of current operations and future directions.

Jan 1, 2002

The Mount Isa mine in North West Queens- land produces a total of nearly 10 million t/yr from separate copper and silver lead zinc orebodies. Sampling information is mainly obtained from diamond drilling on 30 to 40 metre centers in both types of orebodies. For the copper orebodies the majority of the core is analysed for copper content using a non-destructive bulk analyser developed by the Australian Atomic Energy Commission. The diamond drill core in the silver lead zinc orebodies is usually sam- pled as sawn half core and assayed in the com- pany laboratory using a variety of methods dependent upon the level of metal content and/or the elements required. Underground development is sampled where additional information is required to improve the ore reserve estimate. The copper areas are sampled using a standard 2.0 m by 2.0 m chip sample of the wall. The chips are taken on a 250 mm spacing. Lead areas are sampled using a 100 mm wide by 4 mm deep channel over intervals determined by the area geologists. The massive, irregularly shaped copper ore bodies are mined as large sublevel open stopes and pillars. Ore reserve estimation on both a production unit and global scale is routinely carried out using a geostatistical system developed in-house and running on a Sperry 1100 mainframe computer. Copper grade, tonnes and the Kriging var- iance are estimated at points on a user defined grid. The Kriging program uses 10 m assay composites from diamond drill core and underground chip samples. One average (rela- tive) variogram is used throughout the main copper orebodies. The validity of using an average variogram was verified by the original geostatistical study undertaken in the late 1970's.

Jan 1, 1987

By D Rattray, D Macfarlane, I Robb, N Halpin, G T. Dale

Mining faces many environmental, social and regulatory liabilities of which water management is just one. Others include site rehabilitation, carbon emissions, biodiversity offsets, strategic cropping land, subsidence, and noise and dust generation. Management of these liabilities is commonly seen as a cost of doing business and each is often independently addressed, bypassing the opportunity to reduce costs through integrated approaches. Furthermore, approaches to dealing with these liabilities tend to be constrained by a prevailing culture of engineered solutions and lack of appreciation of risk associated with alternative and hybrid alternative-engineered solutions. Suboptimal outcomes can also be reinforced by rigid regulatory constraints. While the cost of addressing operational liabilities may be a small proportion of overall mine management costs, failure to do so effectively may influence social licence to operate and, as recently demonstrated by the decision of the NSW Land and Environment Court to block expansion of the Warkworth Mine near Singleton, absolute licence to operate.Integration of environmental, social and regulatory liabilities with value-creating and risk-reduction opportunities such as beneficial water use, carbon bio-sequestration, habitat connectivity, keyline farming, improved grazing design and management systems, windbreaks and visual screens, presents opportunities to reduce risk and create value. This potential may achieve overall improved outcomes in both economic and non-economic mine performance criteria.Two case studies in beneficial use of waste water from the mining and coal seam gas (CSG) sectors (which operate under different legislation) will be used to illustrate the potential to address mine development, operational and closure liabilities by understanding opportunities to reduce risk and create value through a holistic water management framework. The technical requirements and alternative approaches to beneficial use of mine water are addressed, along with the direct economic benefits for mine operational costs and opportunities to positively engage communities and build resilience into social licence to operate. Regulatory barriers to achieving improved outcomes will be discussed.CITATION:Dale, G T, Robb, I, Halpin, N, Macfarlane, D and Rattray, D, 2013. Opportunities for integrated mine management to minimise risk and create value, in Proceedings Water in Mining 2013 , pp 227-234 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

The Tom, East and West zone, stratiform Zn-Pb-Ag deposits at Macmillan Pass, Yukon, Canada were discovered by Hudson Bay Mining and Smelting Co Ltd prospectors in 1951. Further exploration, including two phases of underground exploration produced an HBM&S calculated reserve of 9.28 Mt of 7.5 per cent Pb, 6.2 per cent Zn and 69.4 g/T Ag for these zones. Cominco Ltd optioned the property in 1988. Deep, surface drilling extended the West and Southeast zones downward 200 - 300 m, indicating an additional potential resource of several million tonnes of good grade. The magnitude of the controlling syndepositional setting suggests that mineralisation continues to greater depth but with increased drilling and possibly mining costs. The 30 x 60 km Macmillan Fold belt trends WNW across the NW Selwyn Basin and Cordilleran trend. Within the fold belt, the Central Block - a complex, rift controlled basin of Devonian siliciclastics, hosts seven zones of Pb-Zn-Ag mineralisation clustered about four hydrothermal centres. The centres, distributed over 24 km, are coincident with small syndepositionally active structural sub-basins. The Tom deposits, in one such sub-basin, are localised by a third order structure consisting of two palaeobathymetric troughs flanking a syndepositional horst. This structure caused drastic facies and thickness changes over 600 metres of strata and focussed the venting of hydrothermal fluids through permeable conglomerates in the horst and its flanking growth faults. Mineral facies are zoned, with Pb-Ag contents rapidly diminishing outward from the vent resulting in restricted areas of high grade Pb-Zn-Ag-Ba ore within more extensive, sub-economic, Ba-Zn mineralisation. Widespread iron carbonate alteration of the footwall and high Si, B and Zn values in the hangingwall 'fingerprint' the deposit and along with the distinct facies variations provide aids to exploring the Tom and like deposits.

Jan 1, 1993

By S Basu, P M. Midhun

Electro-Slag Remelting (ESR) is a process capable of producing ingots with much lower centre-line segregation and better internal soundness than conventional ingot casting processes, as well as lower inclusion and sulfur concentrations. This process is commonly used for alloyed steels intended for critical applications like components of marine turbines, supercritical powerplants and rocket motor casings. It involves melting a metal electrode using electrical resistive heating in a slag pool and re-solidification of the resulting metal droplets beneath the slag layer, forming an ingot. Conventional ESR fluxes consist primarily of CaF2, Al2O3 and CaO, along with minor concentrations of SiO2, MgO etc. The emission of fluoride vapour from the molten slag causes several environmental and health problems, triggering a need to develop and reduce the fluoride content in the ESR flux. The present study aims to develop low-CaF2 alternatives to commercial ESR fluxes without compromising on productivity and the surface quality of the refined ingot. Thus, the modification in chemical composition needs to satisfy properties like electrical resistivity, viscosity and liquidus temperature, essential for efficient ESR operation. Since electrical resistivity and viscosity are highly dependent on the ionic structure of the molten slag, it is important to understand the effect of compositional modification on the structure of the flux. The present study employs Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy to investigate the structural variations in the modified fluxes, especially the effect of changing SiO2 concentration, in comparison with conventional CaF2-rich fluxes. Additionally, thermal analysis (Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA)) has been carried out to characterise the melting behaviour of the fluxes. The findings are compared with simulations carried out using the FactSage™ software, ver 8.3 (GTT Technologies, Aachen, Germany). Simultaneous analysis of liquidus temperature and the structure is expected to help in identifying the practical suitability of modified ESR flux compositions for industrial implementation.

Jun 19, 2024

By R Huntley, D Sims

Pajingo gold mine produces over 240 000 oz Au per year from underground mining using longitudinal bench stoping methods with a 15 m sublevel interval. Average mine head grade is around 12 g/t Au, contained within quartz veins between 0.5 to 16 m wide. The veins dip steeply (>60¦) and exhibit strike variations which lead to many curved and meandering drive/stope geometries. Unplanned dilution at Pajingo is predominantly controlled by fault planes that subparallel the vein and commonly lead to slabbing failure from the stope walls. Initial efforts at determining maximum spans were based on using the Stability Graph method of stope stability. However the method had a number of shortcomings that did not address mine site observations, including previous mining, interaction of different joint sets and the presence of discrete shears which resulted in poor prediction of stability. A method was developed to rate the risk of dilution for a stope based on observations made in the ore drives. The method utilises profile mapping of the ore drive, structural features observed and the orebody itself, on 10 m spaced sections along the ore drive. A matrix of factors determines the dilution risk for stoping at the time of mapping and the rating is transferred to longsection plots in the office. The dilution risk rating is used to determine the position and density of cable bolt support aimed at lessening the risk, and can be used to review blasthole designs prior to finalisation. The method has been used for more than two years and has proven to be a good indicator of potential unplanned dilution (ie waste outside of ring design). A recent review of the dilution risk mapping process has indicated it is assisting in reducing the impact of dilution at the operation and has the scope to be utilised further in the design process.

Jan 1, 2002

By S H. Algie, E J. Knoblauch, I A. Lovatt, S G. Doig

Mill operating teams are expected to engage in a perpetual quest for process improvement – pushing the boundaries of practical process limits and testing new technology to achieve the next step-change in plant performance. Often the barrier to improvement lies in gaining management approval for process changes.Getting approval for investment in novel technology carries an added degree of difficulty, particularly in risk-averse operations, when it challenges conventional wisdom. A case in point is a new technology for controlling variability in slurry distribution. There is a widely held view that less-than-specified classification efficiency and spraying and roping of individual units in a hydrocyclone cluster, must be accepted as unavoidable. That these are wholly correctable deficiencies resulting from unequal loading of the individual units seems a bold claim. Wouldn’t the high turbulence of pumped slurries overcome all potential for segregation of solids? This paper discusses how the task of developing confidence in a new technology can be approached by a combination of physical modelling at small scale, and full-scale operating experience. Proving efficacy then leads to the next task: demonstrating value. Again, the particular technology serves as an example that could be of value to others developing relatively low-cost technologies. A high-pay-off as an investment may be achieved with improvements in metallurgical performance that are small in relation to normal process variations. This has led to an exploration of how process simulation modelling could be used, in conjunction with production data, to provide a benchmark for the expected change, which could be expressed in monetary terms.The next goal, which is currently being achieved in operating plants, is to realise the greater value now available through the optimisation of cyclone configuration, which becomes practical when the confounding effects of cluster instability are removed through equal loading.CITATION:Doig, S G, Algie, S H, Lovatt, I A and Knoblauch, E J, 2018. Investing in new process improvement technology: reducing the risk of implementation – a way forward, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 571–584 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

The design, construction and operation of a 500,000 tonne per year Carbon-In-Pulp (C.I.P.) plant at Kambalda embracing the period from 1980 to 1982 has been previously discussed (Sceresini, 1982).Since that time the annual throughput rate has increased to 780,000 tpy.This paper discusses the changes and improve-ment made to allow this increased production to occur with minimal capital expenditure.

Jan 1, 1984

By B Jones, M Chappell

Permanent rock bolts used to support rock tunnels are required to perform for the design life of the structure as a minimum. Quality of installation is critical to the performance over the life of the rock bolt.This paper will present the findings from an in investigation into the integrity of rock bolts installed in an underground hydroelectric power station cavern and access tunnel. The 25?mm diameter rock bolts were installed 50 years ago, tensioned and post cement grouted. Due to a major machine upgrade the whole facility was subject to an asset survey. The owners are responsible for managing the risks associated with the failure of these rock bolts and ensuring the structural integrity of the tunnels and caverns is maintained to continue operations, protect machinery, assure production and more importantly maintain a safe working environment for all employees and visitors.To help manage risk a proactive approach is desired. To this end a test schedule using a non-destructive testing (NDT) system was carried out by Independent Integrity Testing Pty Ltd (i2t). The system used in this application was RokTel™. The system operates by applying a small axial impact to the rock bolt end and measuring the resultant acceleration response. The rock bolt characteristics affect the acceleration response.The data output from the system is analysed principally using Fourier Analysis (FFT) and sinusoidal waves. The energy generated in the bar, the rate of damping and changes in frequency are all assessed. Testing was carried out on 70 rock bolts within the tunnel and cavern. A selection were then over cored, photographed and documented. The data gathered from the testing is then correlated with physical evidence to establish a calibration for the remainder of the rock bolts and assess if this is a viable method for identifying defective elements, and what degree of accuracy can be achieved. The findings will assist with the future assessment of similar hard rock underground?facilities.CITATION:Jones, B and Chappell, M, 2014. The use of non-destructive testing to identify defective rock bolts – a case study, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 275–280 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014