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By Jones JJ

A laboratory study of size segregation is described using a model of a Paul Wurth hopper industrailly employed for blast furnace charg- ing purposes. Experimental charge materials used in the study were glass ballotin.i (1-4mm dia.) and sinter fines (0.25-4mm). The tracer material employed consisted of coloured glass beads. The results of the study show that the discharge stream from a Paul Wurth hopper is characterised by an initial negative segregation followed by a positive segregation and that this segregation pattern is a property of the hopper geometry and the filling conditions. A simple computer model based on experimental tracer concentration results is proposed. The measured segregation results and those predicted by the model show close agreement. Application of the results with special reference to the effect of size segregation on charge permeability in blast furnaces is also included.

Jan 1, 1984

By Brown N. R

This paper attempts to highlight some of the problems encountered in the economic exploitation of the deeper coal seams by opencast mining methods. The major cost elements of three methods of overburden removal are examined in relation to the overall cost of winning coal from deeper-lying coal seams. The three overburden removal methods examined are dragline stripping and two systems combining dragline stripping with shovels and trucks at varying depths of overburden. A dragline is, undoubtedly, the most cost effective system of overburden removal for depths of up to 30 metres but it is suggested that, when dealing with incremental overburden depths in excess of 30 metres, engineers should consider carefully the possibility of using a shovel and truck operation, or other system, to augment the use of a dragline.

Jan 1, 1986

By J Sigda, T Jones, D Staggs, J Ewing, C Cheng, J Pickens, S Paulka

Mine-derived solutes from Energy Resources of Australia’s (ERA’s) Ranger uranium mine have been closely monitored for decades. Ranger is surrounded by the Northern Territory’s Kakadu National Park and is upstream of Ramsar convention wetlands. Modelling of groundwater flow and solute egress from mine wastes to surface waters has helped ERA successfully assess closure options and secure intermediate regulatory approvals during the site closure process. Potential environmental impacts were assessed using groundwater modelling in support of three ERA applications involving disposal of tailings-derived mine waste. Model results were an important part of the basis for obtaining regulatory approval. Three case studies are presented describing the three applications and how the groundwater modelling supported approval of the applications. For case study #1, INTERA supported ERA in addressing stakeholder concerns in 2017 regarding two aspects of tailings deposition in Pit 3. The first was the potential for flow of tailings fluid into the surrounding formations during tailings deposition. The second was the difference in post-closure magnesium (Mg) loading to surface water for two tailings deposition scenarios. INTERA developed a two-dimensional (2D) model that showed excess tailings pore pressures would not cause outflow and solute egress from the pit during deposition. INTERA’s three-dimensional (3D) models demonstrated that post-closure Mg loading to creeks for both tailings scenarios differed marginally and would be a small fraction of natural creek Mg loads. The modelling results helped avoid delays in completing tailings deposition driven by stakeholders’ environmental concerns. Case study #2 consisted of supporting ERA’s 2019 request for approval to change the tailings deposition method and final tailings level in Pit 3. INTERA’s model results for the permitted and proposed deposition methods showed minimal differences in post-closure Mg loading to creeks. The model results helped ERA obtain the needed approval for the tailings deposition method and water and tailings levels in Pit 3. For case study #3, INTERA modelled the comparative impacts from leaving the entire contaminant plume from the temporary tailings storage facility (TSF) in situ or excavating a portion of the contaminated material from beneath the TSF floor and placing it in Pit 3. The modelling results supported an approved TSF contaminated material application important for ERA to stay on schedule and minimise both closure costs and environmental impacts.

Jul 1, 2021

The lignites of Otago and Southland offer a potentially viable future feedstock for electricity production and possible conversion to petrochemicals or liquid fuels. The deposits, when combined, represent New ZealandÆs largest energy inventory; equivalent to about 74 000 petajoules û or approximately 35 times current natural gas reserves. Too often dismissed as irrelevant to New ZealandÆs energy future because of adverse perceptions of the value of low rank coals, the strategic value of this resource is in fact huge.   Investigations of the lignites extend back over more than 50 years (LFTB various, CRL Energy Ltd). Whilst it is not the intention of this paper to review this work, these investigations have confirmed the suitability of the resource as a feedstock for thermochemical conversion. Current estimates of South Island lignite mining costs are NZ$1.0 - 3.0/GJ (Natusch 2005), making these resources amongst the most competitively-priced energy sources available world-wide.   This value, however, will only be captured if we as a country begin to envisage a world-scale, long-life, integrated and multi-faceted development sized to supply world markets for chemicals or fuels. Recent CAE studies (Hooper and Riddolls, 2005) have emphasised the vital importance of ensuring that any exploitation of this resource maximises their value to New Zealand. The question that thus must be applied is how might large-scale utilisation of the resource fit with New ZealandÆs primary energy supply, and its potential for the export of high-value commodities.   From the broader perspective of New ZealandÆs total energy supply equation we need to examine other supply options beyond just the generation of electricity. We face in this country a situation wherein almost all our liquid fuels feedstock has to be imported with projections for an increasing dependence on imported oil. In addition NZ has a natural gas reserves-to-production ratio of less than ten years, and dwindling supply from local production. Without further natural gas discoveries, New Zealand has only a window of approximately five years before we will need to commit to imported LNG or some other thermal fuels option.   In other words, New Zealand is facing an uncertain future unless we can restore energy inventories to cover an adequate strategic reserve capacity as well as enable long-term investment in alternative sources. Within this context the South Island lignite resources are thus deserving of more attention. The extent of the resource is well known, its suitability for conversion reasonably assessed, and its magnitude such that there is little doubt that lignite conversion could adequately meet NZÆs future energy needs for many years out.   This paper reviews coal gasification technology, its application to lignite and the possibilities for future development of the lignite resources. It is argued that the strategic imperative for this country is to secure the lignite resources as a primary energy source for this country well into the latter half of this century.

Jan 1, 2005

By Laird CH

Large quantities of brown coal are excava ted from open cut mines in the Latrobe Valley to fire the base load thermal power stations of the Victorian Electricity System. Most of the coal is removed using bucketwheel excavators which have been modified or specially designed for the conditions encountered. The actual digging efficiency of the bucketwheel excavator is strongly influenced by such factors as wheel speed, slewing speed and tooth design and arrangement. The coal deposit, although not difficult to work, is not uniform and the operation of the machine is influenced by the stability re- quirements of the excavation face.

Jan 1, 1978

By B Broad

"Establishing ventilation in the early stages of a new mine is an essential step to achieve scheduled outcomes that ultimately drive the financial success of an operation. If the primary ventilation is not in place in time to support a contractorÆs work output, then the ore delivery is likely to be severely impacted. Options to increase ventilation in order to address shortfalls are limited. This in turn can lead to reduced revenue generation at a time when a mine is at its highest capital outlay. This can have implications for any company, but even more for an explorer moving to producer. The ventilation put in place to cover the start-up period is also unlikely to cover any extended or increased load required to meet schedule delays.The following paper examines two issues in relation to ventilation with a focus on small to medium projects where the company is establishing a mine using a mining contractor. The issues being: potential impacts on the contract and tender process when using a mining contractor key mine design considerations, such as æcrunch timeÆ, as they interact with ventilation achieving a successful ramp up.A recommendation is made for higher levels of detail around secondary ventilation leading up to the primary fan installation. The information should be included as part of the tendering process and preliminary project execution planning. Understanding the æcrunch timeÆ concept can lead to strategies, as well as back up plans, to minimise any negative impact.By understanding key risks around primary ventilation establishment for a new mine, detailed design work can be completed where it is needed most. Value is added by reducing uncertainty and a payback with better contract terms and a more robust ramp up plan. This will improve the economic return for the company and reduce the risk.CITATION:Broad, B, 2013. Contract considerations and other critical ventilation aspects in achieving a new mine ramp up, in Proceedings The Australian Mine Ventilation Conference, pp 207-214 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 1, 2013

By Wood CJ, Davis JJ, Askew H

A dynamic model of a dense medium circuit has been developed and tested against plant data. The model shows the response of the circuit to both controlled (changes in specific gravity set point or changes in circuit coal feed rate) and uncontrolled changes (changes in raw coal moisture, loss of raw coal feed) in operating conditions. The model is built up from dynamic models of the individual sumps, pumps, pipes, splitters, magnetic separators and automatic controllers in the circuit. The model can be used for design of automatic control loops and for investigation of possible process modifications such as changes in water addition points. This paper describes the model construction, the testing of the model against actual plant data and gives some examples of its use in investigating plant response to changes in operating conditions.

Jan 1, 1978

By Huleatt M, Perkin D, McLeod I, Mock C, Pratt R, Gourlay A, Timoney E, Knight N, Ward J

Generally speaking, Australia's reserves of its more important minerals (in terms of export earnings) are adequate to sustain forecast rates of production to the year 2000. The rate of forecast production increases of these commodities (aluminium - whether as bauxite, alumina or metal, black coal, iron ore and ferro-alloy minerals, base metals, tin, uranium, and mineral sands) reflects a well- ordered and sustained growth phase of Australia's mineral industry.

Jan 1, 1981

The Tom's Gully gold mine is located 90km ESE from Darwin, in the Northern Territory of Australia. The orebody is the auriferous portion of a large sulphide rich quartz reef, hosted in the Wildman Siltstone Formation of the Early Proterozoic Pine Creek Inlier, at the NH extremity of the Mount Bundey granite-syenite intrusion. It was discovered by Carpentaria Exploration Company Pty Ltd on November 17th, 1986, using stream sediment geochemistry.The reef is 800m long at surface, strikes E-H and dips approximately 300 to the south, becoming progressively less steep. Only the eastern half of the reef is auriferous, with gold grades averaging 9 g/t plus anomalous silver, base metals and arsenic.The enclosing siltstone is a dark grey banded carbonaceous and pyritic metapelite, showing areenschist regional metamorphism and thermal effects from the adjacent pluton. Local folding plunging gently SW is cut by a south dipping fault, probably a thrust, in which the reef was later formed at about the time of the granitic intrusion. The main sulphides in the reef are pyrite and arsenopyrite, with gold occurring as microscopic particles in...

Jan 1, 1990

By Y M. Wang, W Z. Liu, L F. Li, X L. Zhang

Based on the blasting crater theory, the equation between k under typical cases and burden line, charge height was obtained by open pit bench blasting analysis model. The model was calculated with mine production blasting. The blastability coefficient k and the best range of blasting burden line were specially emphasised on determination of lateral crater tests.CITATION:Wang, Y M, Liu, W Z, Zhang, X L and Li, L F, 2015. Application of lateral crater test in open pit blasting parameters optimisation, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 463–468 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Misra A

After review of the status of research on optirnisation of retreat longwall faces it is argued that an acceptable optimisation model must be based upon realistic cost data that take into account not only the face costs, but the total panel costs. These include the cost of development, face cost, removal and installation cost. The determined optimum length of a retreat longwall face is based upon a realistic model and actual costs.Parameters that influence the optimum face length have been varied over wide limits to allow determination of the sensitivity of the model and the effect of the parameters on the optimum face length. It is concluded that for medium production rates and medium system availability, the optimum face length of a retreat longwall face under Australian conditions lies between 180 and 220 metres.

Jan 1, 1995

Firedamp drainage has become an essential part of many mine environmental systems, and new applications are arising. Installations are evolving further to satisfy ever changing basic requirements, standards, and iniilny needs. In this paper, water seal, vacuum based installations are considered, as well as moni- toring, protective and control systems which have been developed for continuous, manless, and trouble free operation. Some factors affecting plant capacity and extractor per- formance are identified and assessed. INTRODUCTION Firedamp drainage applications are incr- easing world wide as mining engineers strive for improved safety and security, and further concentration of coal output. Fewer and fewer mines are able nowadays to satisfy coal prod- uction and firedamp control requirements solely by air dilution or by air dilution and underground firedamp extraction plants. As a result, dependence on surface extraction plants is increasing. This paper deals with som requirements and applications of such installations. I. DEVELOPMENT AND PRACTICE Firedamp drainage has existed for over 250 years following the early work of Carlisle Spedding at Whitehaven (1730). Some fundamentals of current firedamp drainage systems can be recognised in the

Jan 1, 1982

By S M. Gover

Estimating the probability of failure for embankments is not intuitive. It requires not only an appreciation of the strength of the embankment, but an understanding of the variability and uncertainty in the strength parameters as well. These additional aspects are, in themselves, relatively new to most practicing engineers, and therefore require some discussion.This paper discusses the concepts of probability and uncertainty, and presents a reliability-based numerical experiment, together with a literary study and collation of some of the author’s historical slope stability analyses, to investigate whether a direct relationship between safety factors and probabilities of failure exists for certain levels of uncertainty in strength parameters. In doing so, a useful tool is presented whereby knowing the safety factor of a simple slope or embankment with a consistent level of uncertainty, one can infer an approximate probability of failure.CITATION:Gover, S M, 2018. Linking safety factor to probability of failure, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 384–396 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

The Cannington silver lead zinc deposit is located near Mt Isa in North West Queensland. This world class orebody is owned by BHP World Minerals (BHP) and is estimated to contain 45 million tonnes of ore at an average grade of 11 per cent lead, four per cent zinc and 500 grams/tonne silver. At BHPÆs planned 1.5 Mtpa extraction rate, the mine life will exceed 20 years. Construction of the underground mine, which commenced in August 1993, was carried out by Peabody Resources Ltd (Mining Services Division) (PRL) for BHP Minerals Pty Limited (BHP) under contract packages totalling approximately $100 M using several innovative techniques to deliver safety, quality and time related project goals. Client/Contractor Partnering, resulting in harmonious working relationships, a combined commitment to the achievement of an excellent safety record, and a seamless transition from the construction phase to operation of the mine, has been a feature of the project.

Jan 1, 1998

By B Clements, R Dunne, J Dioses, S Hart

In April 2003 plant upgrades in the æLow GradeÆ Cadia Hill circuit were undertaken in order to improve concentrate quality and metal recoveries from the flotation circuit. The major changes involved: circuit reconfiguration to allow all concentrates to be reground to less than 38 ¦m prior to final cleaning; increasing ball charge in the regrind mill to fully utilise all of the installed power; desliming of the cleaner scavenger concentrate to improve the circuit water balance; and the inclusion of a gravity concentrator in the regrind circuit to recover more free gold to bullion.Once the flotation circuit had stabilised under the new operating conditions concentrate launder modifications and increased froth crowding on the scavenger flotation cells permitted the introduction of stronger collectors without compromising concentrate quality or circuit stability.Twelve months on, the copper concentrate grade has increased by two per cent and metal recoveries increased by three per cent and seven per cent for copper and gold respectively. The project capital outlay of approximately $2.0 million has been repaid in less than three months. This paper will review the project from the design, construction and commissioning perspective as well as the subsequent debottlenecking exercise that was required to eventually yield the full benefits of this upgrade.

Jan 1, 2005

By McNabb KE, Ward B, Dyer G

Roof conditions at Southern Colliery, the second longwall mine to be established at German Creek, were found to be much stronger and more massive than at the earlier longwall mine on the lease. Investigations were made to ascertain the level of face support required for longwall extraction under the changed geological conditions. Geotechnical information was provided from drillholes and highwall exposures. Downhole geophysical logs, notably the sonic velocity log, were used to obtain a distribution of the major lithological units over the mine area. A representative type section of the strata and geomechanical properties was compiled to form the basis for numerical modelling. Two-dimensional finite element methods were used to predict strata movements and chock loads under cantilevered roof conditions. The model incorporated a 6.3 in thick roof beam either bonded or detached, with either a 2 in or 5 in overhang. The solid rib, immediate roof, chock support and goaf were modelled as distinct parts, in addition a front abutment stress profile, derived from three-dimensional displacement-discontinuity analysis, was superimposed on the model.

Jan 1, 1992

By R F. Sandenbergh

Due to environmental considerations, mineral processing plants are increasingly recycling water to decrease the impacts of wastewater on environment and the depletion of fresh water resources. Industrial experience has shown that increasing recycling water in flotation typically negatively impacts the recovery and selectivity, especially in the selective flotation of minerals from complex sulfide ores. The major reason for the reduced selectivity is typically the inadvertent activation of sphalerite or pyrite by the heavy metal ions (HMI) in solution. These HMI are often produced during milling and flotation and absorbed by other minerals. In the normal flotation pH value range (8 - 10), these HMI are often in the form of precipitates or complex ions that may re-appear in solution or become active should conditions favour this. In this paper, microflotation, batch flotation and XPS surface measurement were used to investigate the use of HMI absorbents additions to the pulp to improve flotation selectivity of a complex sulfide ore. It has been demonstrated that HMI removal does improve flotation selectivity by facilitating more effective depression of the sphalerite. Microflotation and XPS surface measurements have shown that HMI absorbents compete with sphalerite to absorb HMI, and thus reduce the surface concentration of HMI on those sulfides. The practical use of HMI absorbents in complex sulfide ore flotation is also discussed.

Jan 1, 2005

An integrated mining equipment development organisation is typified by Deutsche Montsn Technologic of Essen, Germany. working on improvements in reliability, production and control in coal mines. Examples of recent mining advances are in mechanised roadheading, in different approaches to cutting technology, and in low height roof bolting.On the longwall face the mechanics of cutting are related to supplied energy as well as to dust make. In conveying both armoured face conveyors and conveyor belts are monitored. Roof support is not neglected and the continuous pumping of stowage slurries provides further options for longwall support. Surveying developments, particularly the gyro-theodolite, directional drilling. and shaft vehicle monitoring provide further examples of advances in control in coal mining activities.

Jan 1, 1991

By Brinkmann J. R

In the narrow stopes of South African gold mines, rockbreaking is carried out by drilling and blasting with safety fuse and igniter cord being used as the initiation system. The fuse/gniter cord system is used primarily because of its low cost, however several limitations of this method include: inaccurate delay time, unreliable firing, inflexible application to varied configurations, and the absence of dynamic interaction between holes. Alternative initiation systems that incorporate millisecond timing are being developed to overcome the limitations of fuse(tgniter cord systems. Current investigations by the Stoping Technology Division of the Chamber of Mines Research Organization (COMRO) into the effects of millisecond initiation are being conducted at a deep test site. Experimental blasts using various millisecond delays and the independent firing of holes with fuse/igniter cord are being studied in order to quantify the influence of delay time on the blasting process and to identify the best methods of applying millisecond initiation systems. The effect of design variables such as delay time, hole firing pattern, stemming, and panel layout are discussed. Blast results including throw distance and direction, muckpile profile and rock cleaning times are used in the discussion of different combinations of blasting variables.

Jan 1, 1990

By M Wagner, H Assimi, F Neumann, C Garcia, B Koch

Run-of-Mine (ROM) stockpiles are the inventory of valuable materials extracted from the mine. Depending on the customer requests, a selective addition of ore from stockyards should be selected at the required tonnage. In the stockyard, stackers and reclaimers are the machines which load and unload ore, respectively. Currently, humans determine the reclaiming/stacking planning sequence in the stockyard by rules of thumb. However, this is a complex task subject to multiple operational constraints, such as where undesirable mineral properties should not exceed certain limits in a request. Human planning can lead to limited decision support and lower ability to consider the upcoming blends and requests. This kind of decision making can cause perturbations in the assumed profit and unexpected loss in practice. Therefore, an intelligent decision-maker and sequence planner would be highly valuable to automate stacking and reclaiming operations in practice. The benefits are reducing variability in decision-making and operation costs. This paper considers a stockyard with available mineral information in the stockpiles using load and dump locations from GPS data feeds. We present an optimisation problem to find a solution which results in reclaiming more ore in a shorter time. To solve the problem, we develop an automatic search strategy based on the greedy search algorithm independent of the type of machine used in reclaiming. The proposed method plans a sequence for stockyard recovery blend optimisation to meet multiple customer demands in a timeframe. Blend optimisation is subject to various constraints such as the elemental composition of the valuable materials and penalty elements. We present three case studies using EKA’s simulator, to fulfil two to four requests from four stockpiles. We compare the obtained results with a pilgrim step reclaiming heuristic and we show how our proposed search strategy outperforms the current strategy used in practice.

Nov 10, 2020