Search Documents

By T Roberts

The transition of mechanical cooling refrigerants from their inception in the 1800s through to the current day has been driven by several factors. Original refrigerants such as sulfur and carbon dioxide, chloromethane and ammonia, whilst effective came with toxicity and/or flammability issues. In 1930 DuPont trademarked a new synthetic refrigerant known as Freon® 12, this development was the introduction of ‘chlorofluorocarbons’ (CFCs).Throughout the 1930s and 1940s additional synthetic refrigerants were developed, namely Freon® 11 and Freon® 22. Due to their non-toxic and non-flammable characteristics, synthetic refrigerants were extensively used for domestic, commercial and industrial applications for the next 60 years.In 1985, one of the first scientific papers suggested a potential mechanism linking CFCs and areduction in the density of the ozone layer. In 1987 the Montreal protocol is ratified; it is the first UN treaty to be ratified by every country on earth. Due to CFC’s ozone depletion potential (ODP), the treaty required the consumption of CFC’s to be reduced by 50 per cent over the next ten years. By 1996 the phase out of CFC’s (Freon® 12) is completed, the phase out of HCFC (Freon® 22) refrigerants comes into effect.On 1 January 2018 the phase down of HFC’s begins. Whilst having zero impact on the ozone layer HFC refrigerants have high global warming potential (GWP). As we transition through the HFC phase down (2018–2035) we are beginning to see the emergence of what some consider to be the fourth synthetic wave, hydrofluoro-olefins (HFO’s). HFO’s and their blends have zero ODP and low GWP’s, ranging from 150 to less than 1. The reduction in GWP with HFO’s typically comes at the expense of flammability, which is not ideal. Each refrigerant has its optimal application, therefor when considering refrigerant choices for mining systems, a complete assessment of the environmental, health and safety, efficiency and commercial impacts should be considered now more than ever.

Oct 12, 2022

By D Bradshaw, R Dunne, S Farrokhpay

It is well known that clays affect the flotation performance, and many of the refractory gold ores around the world contain clay minerals. Therefore, an ore sample from the Carlin Trend was selected for this study as these ores contain large quantities of clays. The presence of clay minerals in an ore makes it susceptible to a range of variables, such as the solution chemistry determined by pH and the chemistry of the rheology modifiers. The viscosity of the ore slurry was measured as a function of solid concentration and particle size distribution, in addition to using different rheology modifiers and pH regulators. The results were correlated with the ore flotation performance. It was found that various reagents known commonly as dispersants or rheology modifiers have different effects on the ore slurry viscosity. This study revealed that the gold flotation recovery can be improved by changing the pulp rheology.CITATION:Farrokhpay, S, Bradshaw, D and Dunne, R, 2013. Rheological investigation of the flotation performance of a high clay containing gold ore from Carlin Trend, in Proceedings World Gold 2013, pp 333-340 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

I have chosen this subject in view of the fact that, while there are many and ample opportuuities of getting reliable assays made, there are but few who are in a position to obtain reliable data on the sampling of minerals and metals my long experience at Port Pirie, where, for five years, I had charge of the Refining and Sampling Mill, showed me how important it was that a correct sample should be taken.Weighing; This, to the ordinary layman, seems so simple that no expert knowledge is needed, but in actual practice there are hundreds of pounds to be lost by the lack of knowledge in this department.(1.) There is the matter of weighing in large or small quantities.(2.) The class of weighing machine used.(3.) The accuracy of weights used.We all know that, say, 1000 tons of ore cannot be weighed in one parcel; but the fewer the weighings the less loss to the seller (and usually wishes it weighed in small lots carefully) for it is a well known fact that the most sensitive scales take a certain weight to show distinctly the indication of the balance, or, in other words, what is known as "the pull of the scales." As for instance, 1000 tons weighed in lots of 1 c. each, taking the pull of the scale as being equal to 1 lb., would give a result of 9 tons loss to tbe seller, and as most of the ore sent to Customs works is worth 5. -£20 per ton-this would mean £180 loss to the careful man.

Jan 1, 1901

By R Munoz, R González, J Vallejos, A Delonca

In panel caving in underground mines, it is essential to characterise and monitor the stress and stability state of production level pillars to ensure the extraction of the mineralised ore column and the safety of workers. Pilar Norte is a sector in the El Teniente mine that forms a pillar between the undercut fronts of the adjacent Esmeralda and Reservas Norte sectors. It exists in a high-stress environment, which may induce damage to the rock mass production pillars. Generally, numerical models are calibrated using observed damage in galleries. This procedure does not discriminate between the structural condition and/or the blasting damage effects. This paper proposes a technique that uses borehole cameras to measure stress-induced damage. This has the advantage of being at the intact rock scale, meaning that the effect of geological structures is negligible and the blasting damage factor is eliminated. Comprehensive geotechnical characterisation and tomography monitoring has been undertaken at Pilar Norte to describe and determine the rock mass behaviour of the production pillars. By combining analytical, empirical and numerical models, a correlation between the measured overbreak recorded by the borehole cameras and the stress level of the pillar was developed. The methodology can be routinely applied to estimate the stress state in the production pillars.CITATION:González, R, Munoz, R, Vallejos, J and Delonca, A, 2016. Characterisation and monitoring of the stress state of production pillars at El Teniente Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 197–202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By I Elias, E Moya, S Chaffer

This paper is based on a case study from a mine site that operates two gyratory primary crushers. These crushers were encountering problems, which included inconsistent P80, reduced liner life tonnage and, on some occasions, catastrophic failure of the liners.As part of an evaluation process, both crushers were ‘mapped’ using a technology for condition monitoring and modelling of the crusher’s wear components. The technology provides comprehensive coverage of the crusher’s concaves and mantle at 100 mm intervals. It also automatically assesses wear rate between inspections and determines the highest wear areas. Outcomes include projected optimum reline dates at target replacement thicknesses, the identification of asymmetrical wear patterns, and the accurate measurement of open and closed (OSS/CSS) side settings.A comprehensive study was performed to optimise the performance of both these crushers at site. Over a period of seven liner service lives, the strategies to improved performance included liner analysis (concaves and mantle profile analysis), tonnes per day (t/d) and tonnes per hour (t/h) analysis, mantle reutilisation, detection and control of loose concaves, and detection and control of uneven wear and hot spots.These strategies resulted in the improved mechanical and operational performance of both crushers through concave and mantle redesign, OSS/CSS control, accurate wear forecasting plus other initiatives.As a result of these initiatives, the site now experiences benefits which include consistent product size, increased tonnes per hour (t/h) for both crushers and the liner life tonnage has doubled. Additionally, further benefits include less downtime for crusher liner maintenance and the reduced cost of inventories by mantle reutilisation.CITATION:Elias, I, Chaffer, S and Moya, E, 2015. Improvements in service life and cost reduction for gyratory primary crushers through mantle and concaves optimisation – a case study, in Proceedings Iron Ore 2015, pp 115–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By G B. Arehart, S J. Mathews, J L. Mauk

The banded nature of the quartz veins which form the Empire lode at the Golden Cross mine, is perhaps their most striking feature. Petrographic studies show that significant differences occur between the bands in terms of textures, quartz grain size, calcite, adularia and kaolinite content, and the form, concentration and mineralogy of sulfide phases.   The d18Oquartz values of individual bands within the vein material range from 7.3-10.9ë. Calculations show that the d18Oquartz values can be adequately explained by temporal variations in the system temperature, boiling and/or variations in the systems fluid/rock ratios.

Jan 1, 1995

In the extraction of level bridge pillars in the South Mine by square-setting methods the general practice is to work transversely from the hanging wall in narrow sections three or four sets wide to the depth of the bridge-usually three sets. When the working block attains an area of twelve square sets, sand filling is run in, either by pneumatic (Proceedings No. 123, 1941) or hydraulic methods, in order to control the settlement of the general area and prevent the development of undue weight in the stope. Upon completion of the filling operations, or coincident with them, ore breaking is resumed and the transverse section of the bridge pillar gradually reduced. A number of these parallel sections may be working at the same time.In preparing a block of sets for filling a great deal of paddocking is required, both to contain the filling and to preserve access to ladderways and ore chutes which may be situated at some horizontal distance. Stope paddocking until recently was constructed of 10 in. x 2 in. boards nailed...

Jan 1, 1942

By R Domotor

Brisbane’s Airport Link is Australia’s largest road infrastructure project, worth a total value of A$4.8 billion. The project is using surface and underground blasting to excavate hard volcanic rock, Brisbane Tuff. This paper tells the story of the most challenging and difficult blast of the whole project: the removal of a remnant pillar of rock (approximately 2250 m3) next to a major arterial road and within 100 m of existing infrastructure including a number of heritage listed buildings, residences and privately owned sensitive receivers. The pillar consisted of a hard rock wall (Brisbane Tuff) between 2 m and 6 m thick, 15 m high and 35 m wide; with in situ precast concrete piles embedded within 1 m of the boundary of the pillar. Orica Australia Pty Limited was contracted by Thiess John Holland, to perform the work in this area, including design, modelling, drilling and loading of the explosives, as well as blast clearance and shotfiring. Access to the area was limited so all explosives and equipment, including the 20 t drill rig, had to be lifted in and out by crane. Due to the nature of the blast, with infrastructure 5 m directly in front of the 15 m high face, there was only ever going to be one chance to get this blast right. This was an extremely complex blast which required the use of a number of different types of packaged explosives, as well as special timing techniques only made possible by using electronic initiating systems. This type of blast is high risk, and is more typical of a building demolition in the urban environment. The blast was fired on the 25 September 2010, and was highly successful. The environmental results for vibration and overpressure were well under the imposed limits, and the embedded concrete piles remained undamaged.

Nov 8, 2011

Early in 1940 the development and sampling programmes in hand on the North and British Sections of North Broken Hill Limited were such as to necessitate the drilling of a large number of drill holes ranging up to about thirty feet in length. On the British Section, one purpose was to test the existence, width, and value of narrow lodes believed, for geological reasons, to occur in the walls of the existing workings. Another object was to definitely disprove the existence of payable shoots of ore in certain largerhodonite and quartz-garnet ("garnet sandstone") pillars which had been formerly left as unpayable.On the North Section, the main purpose of the short holes was to delineate the ore-body boundaries by drilling laterally from drives in ore, and thus enable level layout to be planned in advance of sill stoping. It was also desired to test the walls of stopes in those portions of the mine where the economic limit of mining is not rendered obvious by a clear-cut wall, but should be determined by assay. In these latter cases it was hoped to eliminate "prospecting by stoping," a procedure by which any doubts as to the existence of further good ore behind the low-grade walls were settled by continuing to stope laterally until all chance of such an occurrence was removed.LONG HOLE ROCK DRILLINGFollowing an investigation of recorded instances of similar practice elsewhere it was decided to use the rock drill for a series of trial sample holes. A 3-in. drifter was used. This was selected from those in use underground, and was given a special overhaul; had a new machine been purchased, a 4-in. type would probably have been obtained as being more suited to the work. The rods were H in. hollow round steel with a type "1" Jackrod thread. Couplings were of chrome steel, and were H in. in diameter, and 2 in. long. Jackbits (type "1" thread) in sizes from 2 in. to 4 in., with 1-in. gauge changes, gave a range of nine bit sizes. They were resharpened by hot milling, and were not milled to a definite gauge size.After sharpening, bits were sent underground without sorting into sizes, the drillers selecting the next bit with callipers. In view of the small scale of operations, it was not considered worth while to adopt special measures, such as the cold grinding of bits, which might have given a better product. Later, however, new bits were used exclusively, the idea being to accumulate enough blunt Jackbits to warrant a thorough treatment of the sharpening...

Jan 1, 1941

By W Valery, A Jankovic

The ball mill in closed circuit with hydrocyclones is an industry standard, and well known methodologies exist for equipment sizing, selection and design. However, the potential to improve the capacity of ball mill circuits by replacing cyclones with screens has been recognised for many years and recently has been successfully realised, thanks to developments in fine screening technology. Proper methodology for equipment sizing and selection is required to capitalise on this opportunity, but there is currently insufficient information and few guidelines available on how to design such a circuit. This paper discusses the differences between ball mill circuits closed with cyclones and with screens. A methodology is described for equipment sizing and selection for a circuit closed with screens, and the laboratory testing requirements are described for low grade base metal ores and magnetite ores. An economic evaluation is also presented for a case study demonstrating the potential benefits of closing a ball mill circuit with screens.CITATION:Jankovic, A and Valery, W, 2013. Energy efficient ball mill circuit - Equipment sizing considerations, in Proceedings MetPlant 2013 , pp 285-295 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By A Kitchen

For the past decade, demand for Australian resources has reached unprecedented levels, thanks mainly to the emerging superpowers of China and India. Meeting demand has meant miners and governments alike have ploughed billions into capital expenditure projects for logistics infrastructure such as roads, rail and ports, to support the ever expanding number of mines and mineral volumes. In more recent times, however, the effect of the global economic crisis has led to a decline in demand for Australian minerals. The downturn has seen companies lay off workers in droves, and delay or cancel expansion projects, in an attempt to preserve cash flow. Whilst the current economic cycle has hit the mining sector hard, it is an opportunity for companies to take stock of their existing operations and plan for the future. As mining companies grapple for scarce capital resources, it is inevitable that industry consolidation will ensue. This presents challenges and opportunities for both buyers and sellers alike, looking to expand operations, or sell off assets to raise cash.

Jan 1, 2009

By Whiten W. J

A simulation model was used to study the performance of various types of screen cloth on industrial vibrating screens. The model takes into account the effect of loading upon screen performance and predicts both themass flow rate and size distribution of the screen products.It was found that the use of the simulation model allowed the reconstruction of data for identical conditions and hence has simplified the analysis of the comparative performance of the screens. The dependence of performance upon operating conditions was found to vary markedly with screen cloth type.

Jan 1, 1977

I was delighted to be invited to be patron of this Joint Conference, but the challenging task you have set yourselves, and your speakers' depth of expertise, deny anyone, even the patron, the opportunity to be patronizing. Australia's history has been inextricably link- ed with the fortunes of our great mining industry. That link will remain. Just as the gold rushes of the last century, and the discoveries at Kalgoorlie and Broken Hill changed the lives of generations, so the more recent development activity in iron ore, bauxite, nickel, coal, and uranium are having a significant impact on the lives of Australians today. The minerals industry has contributed to Aust- ralia's jobs and prosperity. Mining is not free of problems, but so long as safeguards are strong and appropriate the net benefits the mining in- dustry brings Australia will continue to be enor- mous. We rely on our mining industry to find, prove, develop and sell our minerals profitably, and my Government is committed to maintaining a healthy mining industry.

Jan 1, 1978

By Madgwick J. C

Leaching column techniques and microbiological methods have been described in detail in Madgwick and Ralph (1980) and Madgwick, Ralph and Sadler (1981).Sixty-nine kilograms of copper porphyry ore (0.4 per cent Cu, 2.7 per cent Fe) (particle size 2.4-11.2 mm; 60 The effect of sodium chloride (O.6M) irrigation on bacterial leaching of Bougainville copper porphyry ore was studied.Viability of suspended Thiobacillus ferrooxidants was reduced to less than 10 cells/ml in NaCI (O.6M) compared with 10' eells/ml in dilute II,SO, (0.01 M, pll 2). Salt irrigation had no significant effect on heterotrophic and sulphur oxidizing bacteria. Increascd short term recovery of copper (145 g/tonne/ 15 days) was followed by a marked decrease in tenors to less than 20 mg/litre/day compared with an acid leach, steady release, of 110 mg/litre/day. Resumption of acid leaching restored average solution copper to 46 mg/litre/day and the viability of suspended T Ierrooxidates to 10 cells/ml.Quantitative removal of sodium ehloride from ore particles was difficult and t races of NaCI remained for more than 200 days.

Jan 1, 1982

By J Say, M Hawtin, L Carlon, P Cann

Historically, production from sublevels of the Ernest Henry Mine (EHM) started from blind uphole rises at the end of slot drives. Where previous investigations considered removing these slot drives and starting production with independent ore drives, any development savings were consumed when drives were extended to minimise ore loss. Since 2017, EHM and Orica have been investigating opportunities to optimise drill and blast practices by implementing Orica’s Wireless Electronic Blasting System (WEBS). To reduce ore drive development metres, a novel design was proposed utilising the WebGen™ 100 system to combine a rise with pre-charged widening firings. Initially these new rise and widening firings achieved results similar to previous EHM designs, achieving on average 81 per cent of design height and width. Due to poor performance of the fourth trial a significant re-design was required. Modifications included drill hole re-positioning, in-hole primer relocation and initiation delay adjustments. Since the re-design a step change in rise performance has been observed with rise and pre-charged widening shots averaging 95 per cent of design height and width. With rise and widening performance exceeding expectations, the removal of slot drives has allowed a substantial reduction in lateral development. Development savings of 165 m and 169 m from the RL1325 and RL1300 levels have been achieved. Primary draw and ore recovery has also increased due to the later addition of pre charged forward stripping rings. Level design changes have also significantly improved the mining cycle by allowing for a reduction in required ground support, improved secondary ventilation, a reduction of critical path development, simpler production scheduling and less wear and tear on machinery. Future mine level designs now incorporate key learnings and are proving beneficial to a variety of scenarios including changing orebody boundaries at depth.

Mar 15, 2021

By Song Yongxue

During the design and operation stages of a block caving project, a large amount of research and development work has been undertaken in the Tongkuangyu Copper Mine. This paper presents the research achievements from these studies, including a rock mass quality evaluation method, cavability prediction, fragmentation evaluation, caving mechanisms, a computerised production scheduling model and the optimised draw control system. The main features of the block caving system in the Tongkuangyu Copper Mine are also discussed.

Jan 1, 2000

The concept of æsustainabilityÆ can largely be defined as development that will not compromise the ælivabilityÆ of the planet for future generations. It has multiple dimensions, such as the triple bottom line û environmental, economic and social. And it also includes temporal (now and the future) and spatial (local and global) aspects that have to be taken into consideration to achieve true sustainability.Energy sustainability might be defined as û having the light turn on when you push the switch. It has, of course many more dimensions than this simplistic definition. Coal in Australia has an important role in keeping our lights on, but has its problems that need to be tackled head on to maintain a role in sustainable development.An overriding issue in terms of sustainability for coal is its major contribution to our greenhouse gas emissions. Whilst we have one of the most effective energy sectors in the developed world, based on well-managed, abundant fossil fuels, our greenhouse gas emissions are one of the highest per GDP in the developed world. We have to reduce our ægreenhouse gas signatureÆ.This paper explores the issues of coal utilisation greenhouse gas emissions as an indicator of the fuelÆs sustainability and the potential lower emissions pathways we will have to follow in a future carbon-constrained world.The technology changes will have significant implications for the minerals industry and it is argued that forward-looking coal/greenhouse emissions strategies need to be developed in alliance with the coal (and energy) sector for the minerals industry to maintain its global competitiveness.

Jan 1, 2004

Thallous chloride and cadmium metal were recovered from a thallium-cadmium concentrate by a method suited to the treatment of small batches. Differences in oxide solubility and control of pH were employed to separate the thallium and cadmium. The cadmium metal produced by zinc reduction analysed better than 99.95 per cent Cd and thallous chloride of high purity was precipitated from solution.

Jan 1, 1969

By P Phelan

This paper presents the general background and development of raiseboring followed by case histories of circumstances where raiseboring equipment was used in a different manner to normal. Each project has been summarised for this paper as described below: Case 1: Retrieval of a 40 tonne truck from a stope at Peak Gold Mines. Case 2: Slot raising - Conventional, Uphole and Downhole Reaming at Peak Gold Mines. Case 3: Reamer recovery by Downreaming at Tower Colliery. Case 4: The importance of Mucking Raisebore Holes û Thalanga Project. Case 5: Pilot Drilling Dewatering Holes at Beaconsfield Gold Mines. Case 6: Low angle æcut offsÆ in vein at Telfer Gold Mine.

Jan 1, 1998

By P L. McCarthy

To design and operate a successful mine the technical specialists must agree on what is ore, what is not ore, and how quickly the orebody is to be mined and processed. These seemingly simple questions defy easy analysis and can push mining engineers, geologists, metallurgists and others to the limit of their capabilities. The questions are rarely addressed adequately in feasibility studies or in operational planning. To optimise the mine and processing plant requires proper determination of cut-off grades or values, prediction of feed variability on an hourly, daily or longer basis, right-sizing the mining rate for optimum product quality, understanding the cost of capital and the expectations of investors, and many other considerations that involve geology, geotechnical engineering, mining, metallurgy, environmental effects and economics. This paper addresses the key matters that should be considered as inputs to the practical issues of metallurgical plant design and operation.CITATION:McCarthy, P L, 2015. Integrated mining and metallurgical planning and operation, in Proceedings MetPlant 2015, pp 35–45 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015