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By Yang RL, Bailey ML

During overburden blasting operations in dragline pits, coal edge losses along the lowwall edge of the new pit are often experienced. In tonnage terms, losses can be significant. With the thick seams at Callide Mine, 20,000 tonnes of coal can be lost along a 600 metre pit. In addition to the immediate dollar value of the coal, replacement of this coal (from which overburden has been removed) will be from higher ratio and higher cost pits in the future. Unit costs of production for the remainder of the coal uncovered in the current pit increase. Experiments involving variation of blasthole inclination and/or amount of standoff on the front row of blastholes have given no significant improvement in the coal edge loss control.

Jan 1, 1988

The complexities of mining in current economic conditions, where ore extraction schedules are varied on a weekly basis so as to ensure constant supply to the process plant, can result in a number of scenarios that pose geotechnical challenges. This paper presents a case study where alterations in the mining schedule of a particular mine resulted in the necessity to mine under a large uncompacted embankment, ie integrated tailings and mine waste land form. To effectively ensure that ore recovery was maximised, a well-designed slope monitoring system to evaluate design performance and to provide timely warning of impending failures was imperative. In order for an appropriate slope monitoring strategy to be developed, a thorough understanding of the potential slope failure mechanisms, capabilities and limitations of available monitoring techniques is required. Communication of the monitoring results and response strategy to alarms generated by monitoring systems must also be carefully considered to maximise effectiveness. The results of preliminary stability modelling can be used to guide the design of a monitoring system, which in turn can then generate data which can be used to iteratively refine the geotechnical model. This paper illustrates the development and implementation of a slope monitoring system and associated communication system, using the Daydream embankment at Fortescue Metals Group's (FMG's) Cloudbreak Operations as a case study.

May 1, 2010

By Gillies A. D S

A device has been developed for modelling the behaviour of coal under conditions which may lead to spontaneous combustion. It is designed to model the behaviour of a stockpile of large mass. The apparatus can test coal samples taken from the flow stream from mine through washing, stockpiling and transportation to the point of utilisation. It tests samples in an as received' condition and so takes into account the effect of aspects such as particle size and moisture content on propensity for spontaneous combustion to occur. Results of the preliminary tests undertaken are given and future applications of the apparatus are Discussed.

Jan 1, 1995

Underground mechanized excavation in New Zealand has become more commonplace in civil and mining applications during the last three years. At one stage up to seven Dosco Road- header machines were being used on different projects around the country. The Huntly West Mine Drifts inclined at one in four were by far the most severe grade conditions that the machines were subjected to; however, other operations posed their own particular problems for the machines. Two major interrelated factors became evident as soon as the machines commenced at Huntly. These were traction problems on the grade and control of water, particularly on the invert.

Jan 1, 1978

By Komosa T, Muir D. M

Mixtures of ammonia and cyanide at low concentrations leach gold selectively from copper-gold ores. The effects of various reagent compositions on three different ore types containing between 0.3 - 1.5 per cent Cu are reported. It is shown that the results and optimum compositions vary according to the ore, which is attributed in part to the mineralogy and adsorption of solution species on the mineral surfaces. The solution chemistry of the Cu-NH3-CN system indicates that Cu(CN)a - and Cu(CN)3 species are involved in the leaching mechanism. Rotating disc studies on pure gold and copper are reported which show that the Cu(CN)32- species leach gold at about half the rate of CN but leach copper at the same rate. The presence of ammonia retards the leaching rate further. Mixtures of Cu(CN)a3- and NH3 effectively leach gold from Telfer tailing without leaching copper. The role of ammonia appears to be to control the precipitation of copper rather than the kinetics of leaching.

Jan 1, 1991

By J L. Edwards

High resolution, acoustic scanning technology has emerged in recent years as a powerful wireline tool for identifying the occurrence and orientation of structures and borehole breakout û the latter being a strong indicator of horizontal stress directions. While other wireline techniques such as dip metre and calliper logging can provide some of these data in a fairly rudimentary way, the quality and ease of interpretation of acoustic scanner logs provides a level of detail that significantly enhances the risk profile of the analysis which more than compensates for their additional upfront cost (MacGregor, 2002). As is often the case with such technology it is one thing to generate a data set that describes the attributes of the various features apparent in a log, and another to be able to analyse those data in such a way that their individual and collective impact on mine planning issues can be readily assessed (MacGregor, 2003). This paper describes a process for the interactive manipulation and visualisation of joint and breakout data to enable them to be effectively included in the mine design process.

Jan 1, 2009

Lower Silesia Coal Basin/SW Poland/ is adjacent to highly gas saturated igneous massiv and since the beginning of this century more than 1500 outbursts have occurred in four existing mines, including 1295 in the most hazardous mine Nowa Ruda. Prevailing part of these are carbon dioxide/coal outbursts of ejected masses 50-5000 tonnes/av.200/t and gas volume released from 200 m3 to 800,000 m3 Magnitude of these phenomena is growing with the depth and for present extraction levels/ 375-753 m/ may be expressed by a formula: M = 4.25/H-400/, where M-masses ejected, t and H - depth of extraction, m. Regulations obligatory hitherto call for gas pressure measurements to be made in 3 m long and 42 mm dia. boreholes spaces not more than 25 m along the longwall face and taking sample of drillings for desorption testing. Criteria of a hazard are following: pressure higher than 30 kPa /for C02/ or 80 kPa /for CH4/ and desorption more than 1,44 cm3/g. These criteria are not satisfactory because many outbursts occurred in spite of low values of parameters measured and for several times no hazard was evident after very high values were obtained. Moreover, observations show that a huge majority of case outbursts occurred in coal weakened by local geological distortion.

Jan 1, 1980

By Ueki S

Underground coal gasification (UCG) is a promising process for obtai- ning energy from coal, which is either unmineable with current mining techno- logy or uneconomic to recover, using conventional methods, in the present energy market situation. There are several coal fields, which could become new coal reserves, if the UCG process were successfully applied. In the 1960's Japanese researchers made a number of basic studies and field tests into UCG, although not all of them produced favourable results. This paper reviews Japanese research on UCG. This includs basic studies into coal gasification using a small, tube reactor fed by air and oxygen, and also large scale model stu- dies(reactor size of 8.Om x 2.4m x 1.5 m). Field test results from Akabira colliery in Hokkaido and a feasibility study of power generation using UCG from a coal field in Hokkaido are also Presented.

Jan 1, 1987

By L D. Redden, M G. Nelson

Mechanical flotation machine design is typically based on hydrodynamic analysis, with scale-up calculated by geometric proportionality. End users often specify and purchase machines on the basis of retention time, characterised by the æ$/m3Æ approach; they may also consider the manufacturerÆs installed base. In some applications, end users also consider specific energy and the impact of energy consumption on operational costs. In other cases, a decision may be based on machine type (forced-air versus self-aspirating) and perceived metallurgical or operational advantages of one machine type over the other. With regard to metallurgical performance efficient bubble-particle contact is very important and is primarily influenced by two factors:the concentration and size distribution of bubbles in the machineÆs contact zone (the volume enclosed by the disperser); and the number of times that slurry is pumped through the contact zone. The second factor is a function of the machineÆs pumping rate and its retention time. Field data show that pumping efficiency is independent of aeration rate. In this paper, a new dimensionless number for the characterisation of flotation efficiency is presented. The contact frequency number (CFN) is defined as the number of times a given volume of slurry passes through a machineÆs active contact region, and is given by: CFN Qp/Qf, where:Qpis the pumping rate through the contact regionQfis the volumetric feed rate to the machine

Jan 1, 2005

By Bin H

East Guangdong tin province overlaps the southmost part of the mesozoic magmatic arcof continental margin type in Southeast China and is dominated by mesozoic syntectic magmatism,which associated to tin mineralization. It is distinguished from Nanling tin province but quite close to NW Bolivian tin province in both tectonic and magmatic relations.Tin deposit's mostly of cassiterite-sulfide, cassiterite-silicate formations are localized along exsocontact zone of granitoid batholith or stock, boundary area of volcanic depression, or, within volcanic edifice. Petrochemistry studies show tin was concentrated as intermediate-acidic magma evolved by fractional crystallization. Xiling tin deposit of vein type related to extrusive... the lava dome was formed at T C 221-301 and at very shellow depth,seems to correspond to type A in classification for Bolivia tin deposits by J.N.Grant. Tashan tin deposit of dissemination type related to hypergene intrusive facies,with mineralization occured in endocontact zone of granite porphyry dykes is considered as porphyry type,which spported by H-0 isotope and gas-liquid inclusion evidences. It formed at T C 250-430, comparable to Bolivia porphyry tin deposits,but at a greater depth 1.3 3.0km.A model for known tin deposits in East Guangdong was worked out. A good prospecting perspective was revealed for the potential type of tin deposit in East Guangdong--subvolcanic porphyry tin deposit.

Jan 1, 1990

In 1976, The Zinc Corporation Limited Broken Hill set up a plant to re-process a hill of tailing (Mt. Keast) from the original treatment operations. With the likely disappearance of this source of feed in 1985, an investigation was initiated to determine what other feed sources might be available. This involved searching through old records and photographs as well as a subsequent drilling campaign. The paper briefly covers the history of treatment operations and describes, as a result of the information obtained, the likely future sources of feed.

Jan 1, 1983

The Directional Drill Monitor (DDM) is an advanced instrument for real time in hole surveying. It was developed by Du Pont (Australia) to suit Australian gassy coal mining conditions. The instrument consists of three units: i. Down hole transmitter ii. Acoustic transducer iii. Data receiver processor unit (i.e. up hole unit). This paper describes the function of each unit in detail and highlights the importance of the DDM in long hole drilling efficiency. Surveying is carried out independent of hole depth. Each survey takes 2-3 minutes to complete, the frequency of surveying to control borehole trajectory is determined by the accuracy required for a particular hole.

Jan 1, 1992

By Kagl J, Publlier M, Nekitel S, Arumba J, Rangin C, Mosusu N

Since the advent of plate tectonic modelling, the Ramu-Markham valley has been thought the site of a classical island-arc/conti- nent collision zone. In this interpretation the units south of the Markham Valley are held to be island are / micrcontinental mate- rial accreted to Australia and those north of the valley are thought to represent a separate Finisterre island-arc terrane. Recent remapping by the Geological Survey of Papua New Guinea shows: (1) there is no terrane boundary along the Ramu-Markham valley (2) the Finisterre Volcanics are probably part of either a fore-arc sequence or oceanic plateau obducted onto a microcontinent/ volcanic-arc composite terrane, accreted to the continental Australian plate. A new tectonic model is proposed for northern PNG and involves: (I) Eocene to Late Oligocene subduction below a microcontinent remote from Australia to produce the Sepik are and related intrusives, the Finisterre Volcanics (fore-arc or possible oce- anic plateau), together with the Alife blueschist. (2) obduction of the Sepik arc in Late Oligocene-Early Miocene times over the advancing Australian plate. This resulted in crustal melting, some of the products of which are the Mid- dle to Late Miocene Akuna and Bismarck intrusive complexes of the Maramuni arc. (3) obduction of the Finisterre Volcanics began in Early Pliocene times and continues today. (4) post-Middle Miocene mineralisation is the result of melting after obduction of the Sepik microcontinent.

Jan 1, 1997

By Bhattacharyya AK

A two-dimensional finite element modelling technique is applied to predict the subsidence movements on a sloping ground surface above a completely mined panel. The modelling is carried out for the surface both directly and using a combination of an equivalent horizontal surface and a rays projection method and the result compared. The rays projection method provides the subsidence components on a sloping surface from the corresponding ones on an assumed equivalent horizontal surface through the point of mean elevation of the relevant part of the sloping surface. This method is used next to compare the subsidences, horizontal displacements and horizontal strains from the mining of a given panel at the surface for different inclinations. The results show that the magnitudes of the subsidence components are greater on the dip side of the slope from the point of the mean elevation, than the corresponding ones on the rise side and the asymmetry increases with the inclination of the surface. The findings are also compared with those of other research Workers.

Jan 1, 1992

By Yu H, Wan B

40 percent of the coal reserves and 40 percent of the ouput of coal in China is of thick coal seams. The sub-level caving in Yangguan has evolved together with the hydraulic supports, to provide recovery rates today of 80 to 85 percent, waste ratios less than 10 percent and daily outputs exceeding 7,000 tonnes. Matching of rate of shearing bottom coal to caving of top coal is most important to achieve "simultaneous" operations. Spontaneous combustion in the goat, gas, including in the goal, and dust, are particular safety hazards which are combatted with various stringent measures.

Jan 1, 1991

By Thatcher R

In areas where land suitable for development is a scarce resource, an upgraded post-mining land use can result in economic benefits to both the mining company and to the community.A study undertaken at Aberdare Colliery near Ipswich during 198611987 assessed the costs and benefits of developing the site following mining for grazing, forestry and residential uses. The proposed fmal land use plan comprised a combination of these uses that can be upgraded to higher valued uses once subsidence monitoring of backfilled open-cut areas and dumps indicates that total settlement has reached acceptable levels for development to proceed.The study involved the documentation of existing site environmental parameters and the delineation of site opportunities and constraints. The unpredictable nature of settlement over backfilled open-cuts and overburden dumps represents the major constraint to urban development on mined areas.

Jan 1, 1990

Applications of chlorine metallurgy to the extraction of metals often result in the production of volatile metallic chlorides, most of which condense directly to a solid phase at one atmosphere pressure. A stirred bed condenser suitable for th

Jan 1, 1980

An airlift pump is fitted to the screw conveyor of a decanter type centrifuge in order to pump out soft cakes which are difficult to discharge from a standard decanter. The new patented2 design improves separation performance and allows more stable operation, particularly when operating the decanter as a thickener.

Jan 1, 1989

By Wright G. N

Curragh Queensland Mining Limited, a co-venture of Australian and overseas interests, operates an open cut coal mine 13 km north of the township of Blackwater in Central Queensland, refer attached location map.

Jan 1, 1992

Mining is a high risk, high capital and potentially high reward undertaking. A large proportion of the risk comes from a lack of definition of the orebody (which also provides some of the potential) and the unpredictable nature of the market. This makes the planning process difficult but encourages the development of a robust yet flexible mining system. The system should be capable of absorbing some deviation from the anticipated concept without a significant impact on profitability. The mine planning process tends to consist of a series of related but discrete stages. For instance, the pit shells are designed, a schedule for the pit shells is created, a plant fleet is chosen to achieve the schedule and a financial analysis is carried out on that scenario. It is likely a few iterations are carried out using various mill throughputs to produce a favoured financial result. The problem is that handing results from stage æBÆ for use in æCÆ doesnÆt encourage a flexible system. æCÆ is likely to be built for exactly æBÆ. Unfortunately, in mining, æAÆ (the orebody) has the highest potential for variability and impacts everything else downstream. æDÆ the market also has high potential for unplanned variability. These variations can spread and æreverberateÆ through the whole mine process. For example an unexpected increase in ore oversize impacts all downstream mine processes to the primary crusher which may in turn create problems back æupstreamÆ by restricting throughput rate. Also an unexpected drop in demand or price could require modifications to the planned production rates. This paper looks at how mining process simulation can be used to support the development of strategies to counteract unforseen circumstances or alter production to match fluctuations in demand and price.

Jan 1, 2003