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By A Logan, B Cuthbert

Brown and Chitombo (2007) indicated that during the last two decades, the international mining industry has been using mainly mass mining methods to extract safely and economically some of the important commodities such as copper, diamonds, gold, iron and nickel. Mass mining may be implemented either on the surface through large open pits or underground using mining methods such as sublevel, block and panel caving. Developments in the last ten years have demonstrated that caving methods can be applied successfully in strong orebodies at greater depths and in increasingly challenging geotechnical environments for which more traditional mining methods would be unsuitable, unsafe and/or uneconomic. These underground mass mining challenges require æfront endÆ investigation and analysis, robust engineering design and disciplined implementation and operation. Newcrest Mining Limited has focused its efforts on the development of gold/copper projects of substantial scale and margin. To help achieve this, the company is applying and further developing mass mining methods. These include large-scale open pits (OP) and underground mining methods such as sublevel (SLC), block (BC) and panel caving (PC). Block and panel caving now offer economies of scale opportunities for Newcrest to achieve high production rates at lower production costs; thus enabling the exploitation of mineral endowments at higher margins. This paper discusses the practical aspects of caving technologies that Newcrest continues to develop through its expertise at Telfer and Ridgeway SLC operations, Ridgeway Deeps BC and Cadia East PC projects.

Jan 1, 2008

By C A. Thomas, J C. Eardley, G V. Franks

As valuable minerals are more disseminated, there is a need for low-grade ores to be finely ground to liberate these valuable minerals. However, this has a negative impact on ultrafine mineral recovery as conventional separations processes such as gravity separation are no longer effective. Instead, fine particles can be recovered by froth flotation. Various novel reagents have been introduced along with development in flotation cell designs such as Jameson cell and column cells to improve performance and recovery of ultrafine valuables. This study, on the other hand, aims to recover the fines using a combination of commercially available reagents to selectively flocculate the valuables, so they are large enough to be recovered via conventional froth flotation cells. This technique if successful can be implemented in many existing industries that continue to use mechanical flotation cells that require particle sizes to be 50–150 μm for effective recovery (Ralston, 1992; Batterham and Moodie, 2005). Selective flocculation is not widely implemented in industries mainly due to the inability to float the aggregates ones they are formed and gangue entrapment within the aggregates which consequently affects the grade of concentrate recovered (Forbes, 2011). The major goal is to aggregate the minerals and float the aggregates unlike the more common industrial technique such as reverse flotation of hematite, where the aggregates itself is not recovered via flotation.

Aug 24, 2022

By Williams SR

Column Flotation cannot be used indiscriminately. Based on extensive pilot plant experience at Lakefield Research, a number of limiting parameters have been identified for the application of column cell flotation. Parameters of importance are the use of wash water, flotable mineral content, pulp viscosity, type of mineral selectivity being sodght and degree of mineral liberation. The paper discusses when wash water should be used and the positioning of a column within the circuit as this is important to maintain a sound water balance for the circuit and prevent excessive circulating loads. Other areas of debate are pulp chemistry, very low and high weight recovery, for which the conventional column is a poor selection of equipment, and treatment of complex ores, where the separation of valuable minerals is more difficult than non-sulphide, sulphide mineral separation. Based on these observations, the application of column flotation must be carefully considered or can be optimised.

Jan 1, 1993

A study is presented of the theoretically possible initiation systems for outbursts and the subsequent propagation mechanism.Previous occurrences of outbursts and their correlation to the theoretical system are described. An estimation of the energy release from two energy sources, gas strain energy and rock/coal strain energy, is presented and the relative importance of each source in the severity of outbursts. Summary: The description of mechanisms of outbursting follows the examination of these phenomena at Collinsville in Bowen No. 2 mine and at Leichhardt Colliery, Blackwater. Quantitative material contained in the paper refers to Leichhardt Colliery, Blackwater. Clearly from the work carried out to date gas release has a major part to play in the out- bursting at both of these collieries. In the case of the December 1 1978 outburst at Leichhardt Colliery energy release estimates place gas strain energy release contributing eight times the energy of that from rock/coal strain energy. Even the normal outbursts at Leichhardt Colliery appear to show this trend. Estimates of energy released are for comparative purposes between gas and rock strain energy and the values obtained may be regarded as approximate.

Jan 1, 1980

FaulIing west of the Mount Isa mine is described and is shown to be related to three groups of folds that have been recognized in the area. The first period of faulting postdates the first generation folding; these faulIs are regional faults (tectonic discontinuities) which are folded by second generation folds. The faulting accompanying the second generation folding divides the area west of the Mount Isa mine into four structurally and metamorphically identifiable blocks. The most prominent of these second generation faults is the Mount Isa Fault, which is characterized by a number of distinct zones of intense second generation folding and the presence of localized layers of mylonite. Only limited evidence for brittle deformation has been observed and the major movement appears to be associated with the plastic deformation of the rocks. Confined to the areas of second generation folding in the Mount Isa Fault are numerous third generation kink folds. A detailed description of the Mount Isa and other faulIs is presented together with evidence for their existence. The displacement accompanying this faulting cannot be established because of the complexity of the structure.Postdating these faults and all the folding of the area are minor cross faults.

Jan 1, 1973

Broken Hill South Limited's discovery of phosphate deposits in the northwest of Queensland in 1966 prompted intensive exploration which has proved phosphate rock in excess of 2,000 million tons at ten separate deposits. Systematic exploration for phosphate in Australia was initiated by the Company in 1964. Early in 1966, an investigation of oil wells in the Georgina Basin in the Northern Territory and Queensland revealed widespread anomalous phosphate in early Middle Cambrian Beetle Creek Formation and Thorntonia Lime- stone. Phosphorites recognised in oil wells in the southeastern part of the Basin, Queensland, led to the discovery of the Duchess deposits, Exploration of the Beetle Creek Formation since 1966 has disclosed nine other sizeable deposits north of Duchess around the eastern margin of the Basin. The Lady Annie and the adjoining Lady Jane deposits, by reason of their location, 160 miles south of the Gulf of Carpentaria, are expected to be the first to be brought into production. Beneficiation testing and engineering investigations commenced in 1967. Transport between the deposits and various port sites in the Gulf of Carpentaria has been extensively studied and a slurry pipeline as a means of transport to a deep water island port, is now being investigated.

Jan 1, 1971

By Grantham DL

ABS'TRACT For a number of years research efforts have been directed towards improving the efficiency of sampling and analysing coal mine roadway dusts. In the past decade the practicality of rapid, on site analysis of the incombustible content of these dusts using a radioactive technique has been receiving close attention both in Australia and overseas. Accurate measurement of the total incombustibles present is only possible by time consuming chemical methods. As the densities of the solid incombustible materials are greater than that of coal, they absorb a higher proportion of incident low energy gamma radiation than does coal. The amount of such radiation "back scattered" from mine dust samples is therefore inversely related to their average densities, and hence to their incombustible contents. This phenomenon can be used as a measure of incombustible content by employing an appropriately designed and calibrated instrument.

Jan 1, 1981

Sampling and analysis of mineral deposits need to be executed without fear or favour of financial or personal impacts. Examples are given to illustrate the effects of departures, witting and unwitting, from correct use of appropriate techniques and/or equipment with emphasis on exploration and mining of porphyry copper deposits of the Pacific Rim. Some of the results of errors on the low and high sides of true value in exploration, resource or reserve estimations and in production caused by sampling and/or sample preparation mistakes, faulty practices, equipment and/or analysis are considered.

Jan 1, 2004

Coal is of tremendous importance for the Czechoslovak econ- omy. The current annual primary energy demand being about 109 million tons of standard fuel (1 ton of standard fuel - 7,000 coal = 29,308 GJ), coal satisfies almost two thirds of our fuel consumption. If compared with the distribution of resources in the world's fuel and energy pattern, the situation in Czechos- lovakia is significantly different, as shown in Fig. I. One of the causes behind the difference is that the Czechoslo- vak oil and natural gas reserves and, hence, their production are insignificant, so that it is necessary to import them. Brown coal will continue to play an important role as a prin- cipal domestic source of primary energy even in the future. While the share of nuclear power is increasing, brown coal represents strategic reserves in the fuel and energy balance.

Jan 1, 1989

By E Werner, B R. Leavitt

The chemistry of acidic mine drainage discharging from flooded coal mines is commonly reported to improve with time after flooding. This investigation describes a 18-year dataset of post-flooding water chemistry for a below-drainage underground coal mine within the northern Pittsburgh coal basin (Pennsylvania, USA). The Montour mine is a 5650-hectare below-drainage coal mine of maximum 260 metres depth. Montour was closed in 1980 and flooded to within 38 metres of land surface within 4.8 years. Pumping averaging 210 L/s was then employed to maintain water levels at this elevation. The flooded proportion of the mine (by volume) at full flooding was 56 per cent. The shaft where water was pumped from Montour for water control is located about 70 per cent of the distance between the mine water table and the back of the mine ù that is, it is close to the back of the mine. The residence time (total water volume at flooding divided by pumping rate for control) is estimated at 5.6 years. Time series of chemical analyses show three phases of chemical behavior in post-flooding discharge. In Phase I (zero to two years after flooding), iron concentrations were high and reached their maximum (1100 mg/L). In Phase II (two to four years after flooding), a transition was begun to alkaline conditions, with decline in iron and other solutes. In Phase III (>4 years), net alkaline conditions began, with iron concentrations declining exponentially to 50 per cent of mined volume. This attainment of net alkalinity in this case may have also depended on abundant calcite in overburden extended up to 30 m above the mine floor.

Jan 1, 2003

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

By C F. Nichol, L Smith, R D. Beckie

A better understanding of the hydrogeology within mine waste rock and cover systems is essential for the quantification, prediction and prevention of metals loading to the environment surrounding waste rock piles. The effect of surface condition on the internal flow mechanisms within an intermediate-scale constructed waste rock pile is being investigated at the Cluff Lake Mine, Saskatchewan. Changes in the water balance, the outflow distribution and water residence time have been observed in the waste rock pile following successive modifications of the surface condition. The three year old, run of mine, free-dumped surface was ripped to a depth of 30 cm to 40 cm, and levelled in October of 2001. In August 2002, a 10 cm to 15 cm cover of compacted waste rock was placed on the pile. Outflow, precipitation and run-off data collected during natural and artificial rainfall events have been used to quantify the maximum infiltration rate, and the spatial pattern of discharge and cumulative volume of water that infiltrated into the waste rock under each surface condition. Infiltration data together with the outflow data provide a basis to address the residence time of water within waste rock and the dominant flow mechanisms for different surface conditions. With a free dump surface spatially distinct wetting fronts are observed at the base of the pile that vary in flow rate by an order of magnitude (measured at a 2 m by 2 m scale) and in time by up to a week. Following ripping and levelling, similar cumulative outflows were observed, but the magnitude and arrival time of wetting fronts changed across the pile. A decrease in outflow volume, a decrease in infiltration volume, a two-fold increase in the response time of wetting fronts and a more spatially uniform distribution was observed following placement of the compacted surface layer. Based on preliminary data, the internal structure appears to be the dominant factor controlling outflow variability.

Jan 1, 2003

Not so many years ago the reason for an inadequate result from a geophysical survey was insufficient data or poor quality data. In many instances such as gravity, magnetic and radiometric surveys, both these constraints are vanishing or have vanished. High quality sensors, improved data storage, accurate differential GPS and top quality interpretive software now enable the interpreter to understand not just the cause of the anomaly but the host environment in which it resides. Examples of potential field data and also data provided by the more complex electromagnetic systems, from Australia Ghana, West Africa, are used as illustrations.

Jan 1, 1997

By A J. Moore

Predictive assessment of surface blast vibration requires the identification and quantification of significant factors, and the summation of their combined effect. Methods available for the prediction of significant factors are described, and examples are given of the combined use of these methods to evaluate alternative proposals.

Jan 1, 1999

By G Solly, S Parsons, P Leevers, S Ni

Hematite ore has been mined in the Southern Middleback Ranges as blast furnace feed for the steelworks at Whyalla, by what was then BHP, since 1991. With the floating of BHP Integrated Steel as OneSteel in 2001 and the subsequent loss of key mining personnel, breakdowns in grade control methods and procedures occurred. These were compounded by changes in orebody characteristics and grade distribution leading to poor reserve recovery and poor grade control, both which resulted in loss of control of ore specification and severe deviation from the mining schedule. As a result, a total review of grade control, mining method and scheduling procedures was undertaken as well as a review of contractor quality assurance. It was found that sampling methods were poor and unrepresentative, grade control blocking processes were outdated and did not reflect the geology of the deposit, the ore mining method was outdated and did not respect the geometry of the orebody, reconciliation methods were being completed globally and were not reflective of individual areas of the deposit, and that deviations from the mine plan were occurring due to access to high-grade areas outside the schedule in order to bring stockpiles back on grade. Based on these findings, updated sample splitter systems were fitted to drill hole rigs, double bench sampling was implemented (2 + 4 m samples as opposed to 1 + 8 m sample) and a three-dimensional cellular grade control system introduced to better reflect the geology and orientation of the deposit. At the same time ore mining was changed from front end loaders mining on 8 m benches to excavator mining on three lifts on 8 m benches; this aided selectivity and respected the geometry of the orebodies aiding cleaner recovery. Reconciliation is now completed on a blast-by-blast basis, which allows for quick and easy identification of poorly performing areas of the resource model that can then be incorporated back into resource model updates. Regular daily and weekly meetings are also held with emphasis on the mining schedule to ensure no deviation from the schedule in the long term. These improvements have resulted in a lift in reserve recovery both globally and locally associated at the same time with improvement in grade.

Jan 1, 2005

Of all of the processes in the mining cycle, blasting has the greatest impact on the efficiency of both mining itself and the initial stages of ore processing. The cost of blasting can be readily accounted for, but the true benefits of an effective blasting operation are seldom measured or reported. This means that blasting is seldom optimised in terms of its overall economic impact on an operation. Blasting operations have evolved according to the environment provided by mine management. Most operations seek to minimise the unit cost of each component process (overburden removal, blasting, excavation and transport, crushing or grinding) without recognising the impact that blasting performance has on subsequent activities. The creation of æcost centresÆ or æmanagement unitsÆ that isolate blasting from its downstream impacts reinforce this trend. Modern blasting technology is regarded as sophisticated by virtue of the mechanical design of the drills, the chemistry of the explosives and the flexibility and reliability of modern blast initiation systems. However, blast performance is controlled by the nature of the rock mass and there is generally an inadequate appreciation of how blast designs should be tailored to suit different rock mass conditions or to meet different blasting objectives. Most operations utilise a limited suite of standard designs without routinely tailoring designs to suit the actual conditions at hand or the objectives of each blast. Mining operations would benefit from tackling the following specific challenges:What is the appropriate target performance for blasting operations to generate the maximum economic benefit for the operation as a whole? How should designs be configured to suit the changing rock mass conditions and operating constraints? What compromise (if any) should be allowed from the ideal to assist conflicting scheduling or other operational requirements? How can blast performance be measured and reported to provide appropriate guidance to future operations? These challenges can be tackled through the process of æblast engineeringÆ. This paper discusses the potential impact of blasting performance on the economics of mining operations and the author argues that very considerable benefits over and above those currently being achieved could be realised by improving the routine engineering of mine blasts. The paper then explores how the industryÆs failure to recognise the economic importance of blasting has resulted in the engineering of blasting operations receiving less management and technical support than is appropriate. Finally, a simple approach to the engineering of routine blasting operations is described as an example of how these challenges can be tackled.

Jan 1, 1999

By S Gannon, J Abols, T Hughes

In the past year, two very innovative gold ore processing plants have been designed, built and commissioned by Gekko Systems Pty Ltd. The first plant in Vietnam utilises conventional crushing and ball milling followed by gravity concentration (Inline Pressure Jig (IPJ) and Falcon concentrator), flotation, intensive leaching (GFIL), the first industrial scale use of AuRIX«100å ion exchange resin and a cyanide destruction circuit. The second plant, in Australia, uses a three-stage crushing circuit to crush the gold ore to minus 1 mm, followed by gravity concentration utilising a rougher, scavenger, cleaner circuit of IPJs and a Falcon concentrator. A direct smeltable gold concentrate is produced as well as a lower grade concentrate for future intensive leaching or sale. Both plants were designed and built within very tight time frames and budgetary constraints. The experience gained during the plantsÆ design, commissioning and operation are discussed.

Jan 1, 2006

By R Vleggaar

In addressing a short-term operational need for the relocation of a tailings storage facility reclaim pond, a mine has achieved a host of water management objectives. Through effective planning and adoption of a strategic æwhole of mine lifeÆ approach, the mine has achieved significant environmental, social and economic benefits. A review of all water management aspects across the site identified a host of other interrelated water issues and concerns which, if dealt with individually, would prove too costly for individual operational departments. When considered as a whole, however, the issues became opportunities and provided the stimulus for integration of the site water management system. The development of site water and solute balance models provided the tool by which a number of water management options/strategies could be evaluated. The conceptual design and costing of the proposed water infrastructure further facilitated the evaluation of the multiple benefits to be gained from each option. A business case could then be made to mine management for the preferred option. The recommended water management strategy finally recommended to the mine not only provided a tailings storage facility (TSF) reclaim pond, but also provided for:increased wastewater recovery from the TSF, the capture of all waste rock dump run-off, additional water harvesting from local creeks, increased wastewater reuse, improved environmental water management, infrastructure that could be used by the local community after mine closure, and overall cost savings. This paper illustrates how effective water management planning can provide both short-term economic and environmental benefits, as well as long-term social benefits.

Jan 1, 2006

By M Hudyma

Open stope mining is the most common mining method employed in underground, hard rock mines in Canada. It is characterised by relatively small, single lift stopes (20 000 to 100 000 tonnes), and fast stope turnaround times. Host wall rock mass conditions, which are typically poor to fair, are the controlling parameter in stope dimensioning. Rock mass stability is maintained by designing all stope surfaces at a stable dimension, and through extensive use of cablebolting for stope backs and frequently stope hanging walls. Dilution control is a high priority. The typically small, high-grade, deep and irregularly shaped orebodies are incrementally developed, usually in a bottom to top direction. In many cases, high stress is encountered due to the depth of the orebodies. Overstressing of pillars and hanging pillars are avoided through the use of pillarless or early pillar recovery mine sequencing strategies. Stopes are invariably filled, and in higher grade and wider orebodies, cemented fill is commonly used. This paper generalises many of the similarities found in Canadian open stope mines.

Jan 1, 2000

By Misra VN

The carbon-carbon dioxide reaction is the rate determining step in industrial processes such as the rotary kiln direct reduction process for iron ores. The use of brown coal as a reductant in the rotary kiln process has been shown to result in higher throughputs and lower kiln temperatures. No experimental data has been reported on the effect of coal type or the use of brown coal chars. Methods of carbon-carbon dioxide reacti- vity measurement are discussed. None of the methods have been related to direct reduction practice. No standard test has been developed to assess the reactivity of brown coal chars to carbon dioxide. For routine comparative work the gas analysis method of Okstad and Hoy appears to be the most suitable although some modification to the experimental conditions is required. For detailed kinetic studies direct weighing techniques are to be preferred. The factors affecting the reactivity of brown coal char to carbon dioxide are reviewed. Numerous factors such as the origin of the coal, pretreatment and ,physical and chemical differences have been found to affect the reactivity of brown coal chars but no data has been reported on the effect of coal type on reactivity to carbon dioxide.

Jan 1, 1980