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By H Benzer, N A. Aydogan

It is well known that the high pressure grinding rolls (HPGR) can only be operated efficiently under choke feeding conditions in which a material bed is built up between the rollers to ensure interparticle breakage. By increasing the fines amount in the material bed up to a specific level with the recycling load, a uniform material bed is created and higher pressure gradient along the roller width is obtained which results in compact flakes including more fines. Extensive test work has been carried out with an industrial HPGR unit grinding cement clinker in a cement plant in Turkey. During the test work the recycling load of the circuit was changed to achieve different ratios to the fresh feed rate in order to identify the effect of the recycling load on the circuit performance. Six different tests were performed with the circuit at steady state. For each test, samples were collected from HPGR fresh feed and discharge, and total feed, then the particle size distributions of the samples were determined and mass balances around the circuit were calculated. The conclusion was that the reduction ratio of the HPGR increased with increase in recycling load. The flake densities showed the same trend with more compacted flakes being produced for higher recycling loads.

Jan 1, 2009

By M S. El Salmawy

In order to develop the HF-free flotation reagent system, the main objective of this investigation was to study the possibility of separation of quartz from feldspar using non-ionic surfactants as the collector. The non-ionic surfactants used were polyoxyethyl cethyl ether (PECE) and polyethylene glycol monocethyl ether (PGME). The flotation behaviour of quartz and microcline with PECE and PGME was investigated. Each surfactant was a good selective collector for quartz with its recovery being influenced by pH and surfactant concentration. Quartz is floated favourably by both types of polyoxyethylene non-ionic surfactant whereas microcline was not so much. The floatability of quartz increases as the oxyethylene length of surfactants increases. Zeta potential measurements in the system of PGME/mineral were also carried out. It was determined that in the absence of PGME the points of zero charge for quartz and microcline should be approximately at pH 2.5 and 1.8, respectively. The addition of PGME to the system causes both minerals to become less negatively charged. Differences in the zeta potential value between quartz and microcline, in the presence of PGME, were detected. It can be suggested that the interaction of the oxyethylene group to the microcline surface should not be as strong as that to the quartz surface. In the mixed surfactant system of PGME and dodecylamine acetate (DAA), a small addition of DAA causes drastic enhancement of quartz flotation in the wide pH range of 1 ~ 10. In the mixed surfactant system selective flotation of quartz from microcline would be anticipated at pH

Jan 1, 2005

High interest to basic-ultrabasic rocks is ex-plained by their specific, sutural, geotectonic po-sition and by deep level of generation of ultraba-sic magmas. These two factors allow us to treat this group of rocks as valuable source of informa-tion about the lower crust and upper mantle of the Earth. Basic-ultrabasic xenolith series is another source of information about the interior of the Earth. Detailed studies of the xenolith series give valuable material to geologists as to how endogenic deposits are fed and what is their source.Besides, the interest is explained by attempts to understand the relationship between basic-ultra-basic complexes and deposits of metalliferous and non-metalliferous mineral material.Absence of genetic boundaries in manifestation of metalliferous and non-metalliferous minerals, their temporal and spatial relationship allow us to treat the minerogenesis of ultrabasic complexes as a result of one ore-forming process manifested in Koryak-Kamchatsky, Sakhalin-Japanese, Ryukyu-Korean and Taiwan-Philippines island arc systems which re-present, in the opinion of the authors, one eastern Asian chain of the Pacific ore belt (Radkevich, 11)87).

Jan 1, 1990

By Staunton W. P

The presence of cyanide soluble copper in gold ores can give rise to serious operational and economical difficulties in CIP and CIL operations. Cyanide consumption can result in the ore being uneconomic to treat by conventional means. Loading of copper onto carbon can also have deleterious effects on gold recovery and subsequent stripping and bullion recovery. The recovery of gold from high copper ores has been previously reviewed by Muir, LaBrooy and Cao (1989). Work undertaken for Mt Gibson Gold Project by Australian Mining Advisors with the assistance of the Chemistry Centre (WA) resulted in the patenting of a process and subsequent construction of a plant at Mt Gibson to overcome some of the difficulties encountered with copper. This paper discusses some of the work which was undertaken during laboratory investigations prior to commissioning of the plant and some further considerations for the treatment of high copper gold ores.

Jan 1, 1991

By T Baard, A Pieters

This paper deals with the design and implementation of a 17 MW (nominal) surface cooling installation at Impala Platinum No 14 shaft located in Rustenburg, North West Province, South Africa.The cooling requirements included the installation of a surface ammonia refrigeration plant complete with the storage of hot and cold mine service water for underground use. It was also necessary to install a surface bulk air-cooling facility, which cools 400 kg/s of ventilation air going to the underground workings. Primary cooling is to the surface bulk air cooler. The cooling duty of a surface bulk air cooler is heavily dependent on the ambient wet-bulb temperature. Because of the daily wet-bulb temperature variation in this part of the world, use was made of a cold thermal storage facility of four million litres. The excess chilled water is stored during the night, for use by the main drilling shift during the day. This keeps the refrigeration machines as close as possible to full load during the summer, thus maximising the use of the capital expenditure. This paper discusses the control philosophy used to maximise the cooling output, as well as the thermal process. The project consisted of two phases resulting from the underground development phases of the mine. The first phase started in January 1999 and was commissioned by the end of the same year in record time. The final commissioning of the second phase took place at the end of 2002. The most difficult part of the construction phase was the tunnelling of a subsurface air duct from the bulk air cooler to the operating vertical shaft. This was done without disruption to the hoisting of men, material and ore in the shaft. Owing to the size of the refrigeration machines, the ammonia quantities involved and the application on a mine (no ammonia can go underground, either in the service water or in the mine air) special precautions had to be taken. South Africa has developed high standards for ammonia refrigeration plants used on mines, which will be partially dealt with in this paper.

Jan 1, 2005

The implementation, during recent years, of the concept of distributing chilled water to improve cooling at the working faces represents a very important innovation for the mining world. In a logical extension to that concept it has been recognized that distribution of the cooling water at high pressure would provide a potential source of energy for driving water powered hydraulic machinery such as rockdrills, water jets for moving rock, and support props, in the workings. With this in mind, the Research Organization of the Chamber of Mines of South Africa is pursuing the development of such a dual system that will provide cooling in a deep mine and, at the same time, drive hydraulic machinery. A comprehensive design of such a system has been completed and has shown the concept to be entirely feasible technically using technologies currently available. A pilot system is working in a mine shaft 2000 m deep giving a pressure of 20 MPa at the bottom of the shaft and distributing the cold water into the workings at a pressure of 17 MPa. The system shows considerable potential for improving existing mining methods and will open the way for the development of new mining methods for deep mining operations.

Jan 1, 1986

By A Murphy, D Lauder, J Miranda

Minera Alumbrera Limited operates the Alumbrera concentrator, treating a nominal 80 000 tpd of porphyry gold/copper ore. It is located in Argentina, 1200 km north-west of Buenos Aires in Catamarca Province, at an elevation of 2550 m above sea level. Treatment facilities consist of crushing, SAG and primary ball mill grinding circuits, rougher flotation, ball mill regrinding, gravity recovery and cleaner flotation. It is one of only a small number of concentrators in the world, which uses Jameson Cells alone for cleaner circuit flotation. Plant design was started in June 1995, with commissioning commencing in July 1997. Following a successful ramping up to design tonnages and recoveries, a number of options were reviewed to improve gold and copper recoveries. This paper concentrates on a detailed size by size flotation recovery project, commenced in May 1999. Utilising optical microscopy, scanning electron microscopy and analysis of surface chemistry it has allowed losses by size fraction to be quantified and options for enhanced recoveries to be developed. Coupled with extensive circuit surveys it has also provided an insight into previously unknown properties of Jameson Cell operation. Among these are unique residence time and bubble formation reactions to reagent and pulp flow variations, which has permitted a number of novel changes to the operation to maximise capacity and recovery.

Jan 1, 2000

By Kaleta S, McTavish LP, Turner RD

Primary production blasting at Hamers- ley Iron began with seven inch holes at Tom Price in 1966 and has developed since then to large multiple row shots of 381 mm holes at Tom Price and 311 mm at Paraburdoo. Up to 1.3 million tonnes are initiated in a single blast with the average around 300,000 tonnes. Development can be traced through Anfo, AlAnfo, slurries, various boosters, initiation and delay techniques, hole loading and daily operating practices. A standard practice could be developed for the two mines for normal pro- duction blasts; this would not apply to such common variations as low "paddy" shots, pre- splitting, tight corners necessitating single row drilling etc. Because of ground variation three or even four sizes of drill holes may well be economic- al for blasting, even though this would be off set by complications in operation, supervision, store stocking and maintenance, particularly in Drilling.

Jan 1, 1978

The interfaces between the Broken Hill ore lenses and the enclosing wallrocks are, on a broad scale, parallel to metamorphic layering in the wallrock gneisses and quartzites. In detail, however, the concordant contacts are interrupted by piercement structures, formed by plastic injection of ore into the wallrocks during metamorphism.These discordant bodies vary from minor projections measuring less than I m long, to major ore shoots ("droppers") as much as 60 m long. The intrusive bodies consist of fragmented ore and wallrock in amatrix of recrystallised sulphides. Wallrock fragments have been altered to manganese-rich and calcium-rich mineral assemblages. The injected ore is enriched in sulphides compared with the parent ore, and there has been enrichment in a number of minor elements.Piercement structures formed during the waning phase of high grade metamorphism, when incompetent ore was injected plastically under pressure into the wallrocks, particularly at fold crests. Adjacent to the "droppers", retrograde schists developed as a result of shearing along the ore-wallrock interface.

Jan 1, 1976

Geostatistical conditional simulation is a method to assess variability and risk in mineral deposits and the tool has wide potential applications in the iron ore industry. Correct reproduction of multivariate relationships is important in iron ore simulation, especially between Fe and impurities such as Al2O3, SiO2 and P. The turning bands simulation method, using a full model of coregionalisation for multiple attributes, is the main multivariate conditional simulation algorithm used in the Western Australian iron ore industry. This paper discusses the results of a more recent approach using minimum/maximum autocorrelation factors (MAF) to transform and decorrelate the multivariate data prior to independent sequential Gaussian simulation (SGS). MAF-SGS results are compared to those of the turning bands approach in the Yandicoogina channel iron ore deposit (CID), and both methods performed well in simulating Fe, SiO2, Al2O3 and P distributions. Extensive checking of simulations showed that both approaches could reproduce multivariate statistics and spatial continuity of the original conditioning data. Both approaches reproduced the histograms and variography of input sample composites. While the MAF-SGS approach requires additional transformations when compared with the single normal scores transformation required for the turning bands method, MAF requires only that the direct semivariograms be modelled. In contrast, using turning bands with multiple attributes requires modelling a full linear model of coregionalisation, which can be difficult to model because of the need to ensure the model is positive semi-definite. Turning bands may be preferred if there are a modest number of correlated variables allowing construction of a linear model of coregionalisation that adequately models the multivariate behaviour. MAF-SGS is preferable for larger numbers of correlated variables. Both MAF-SGS and turning bands methods performed well in conditional simulation of correlated variables at Yandicoogina.

Jan 1, 2007

By Blair J. R

A Train Performance Calculator (TPC) is an essential tool in railway operations, as a means of acquiring quickly a precise measure of the performance of the system. Traditionally the TPC was used in the form of program for a large computer. By employing an efficient integration algorithm and tailoring the program to suit the computer system it is shown that it is possible to devise a TPC for a mini computer. The resulting low running costs and flexibility of operation makes this a useful design tool. This TPC was developed to study problems associated with a single track railway operation. It was applied specifically to study the railway operated by the Mt. Newman Mining Co. Limited in the Pilbara region of W.A. to transport iron ore from the mine to the port. The TPC was used to calculate the effects of changes to locomotive power, to train size, to the track and to the amount of traffic. Its accuracy was checked by comparing its performance with that of the actual trains.

Jan 1, 1977

Aspiring to be excellent makes you a good leader as it shows a capability for strategic thought, defining and implementing a vision, making a job easier, more efficient and effective. Every great business leader can generate additional revenue or cost savings for their company. Becoming excellent requires the desire and action to follow it through. There are many established methods of excellence: benchmarking, target setting, supply chain and market analysis, employee suggestions and knowledge sharing forums. In BHP Billiton, practices benchmarking is a key tool in generating improvements for functional areas such as processing, mine operations and mine planning. Practices Benchmarking involves organisational and technical questions that allow the site to self-assess their maturity and generate a prioritised improvement path. Not only does it benchmark and identify gaps, but the approach also facilitates networking, education and team building. For new leaders it is important to remember that you are not alone. Chances are your problem has been solved before. Networks û internal, external, formal and informal can get you started and often save you time and effort. Any leader can achieve success in excellence through a proper process of problem formulation, data and analysis. Again, using key players can make the process more effective. It is important to remember that the people side of the solution is the key to success and that monitoring will ensure the solution will work. In the words of BHP BillitionÆs CEO, Chip Goodyear: Excellence is a mind set. ItÆs something that comes when people get rewarded forthinking outside the box and applying their skill and knowledge. It happens, not in$50 million chunks, but in hundred thousand and million and $2 million chunks.When you get 35 000 people thinking that way, then youÆve really got somethinggoing.

Jan 1, 2005

The Mammoth Mine is located some five kilometres from the town of Gunpowder which is approximately 120 km north-west of Mount Isa in Queensland.

Jan 1, 1993

By Terlich R. E, Finlayson J. M

A combination of high virgin rock temperatures, deep workings and extensive utilisation of heavy diesel equipment has presented North Mine (A Division of North Broken Hill Limited) with challenging ventilation problems. These problems have been addressed in a variety of ways which include in the order of 6000 kM of underground refrigeration. The future of North Mine depends on the successful development and extraction of ore in excess of 1100 m below the shaft collar using mechanised cut and fill mining. The success of this will depend on the installation of a complex chilled water reticulation circuit in this area. This will involve planning and constriction of a number of large dams, installation of pups and turbines, and the successful commissioning of several large water to air heat exchangers.

Jan 1, 1988

The progress of longhole open stoping (LHOS) at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited (ZC/NBHC) is described. The design of a novel sloped wall longhole stoping method at NBHC which should allow the cuplete extraction of the orebody without the formation of pillars and with minimal dilution of the ore with sandfill is reviewed.

Jan 1, 1983

Instantaneous outbursts have occurred at Metropolitan Colliery from the pick and shovel work of early days to the modern mining techniques of today. Developments have been the introduction of an emission index to measure the proneness of the coal to outbursts, drainage and destressing by large diameter holes, attempts at higher productivity by the introduction of pulsed infusion shotfiring and improvements in ventilation. The future plans and aims for the Colliery include prediction of outbursts, seam gas pre- drainage and longwall mining.

Jan 1, 1980

By Hedge AS

Mt Whaleback is one of the largest open-cut iron ore mines in the world. Haulage cost is the single largest component of operating costs at the mine. Past studies towards alternatives to truck haulage have recognised the potential viability of an in-pit crushing and conveying system, dependent on the proportion of uphill haulage. After seventeen years of mining Mt Whaleback still contains more than 1,000 million tonnes of ore, needing 1,800 million tonnes of waste removal to extract it. What was once a quarry has now turned into a large open pit. The increasing proportion of uphill haulage, the need to replace ageing 120 ton and 200 ton trucks and the necessity of achieving and maintaining a higher stripping ratio prompted, in 1984, the initiation of a new feasibility study into the viability of alternative material handling systems. A semi-mobile in-pit crushing and conveying system was found to be most suited to Mt Whaleback conditions. The East Pit was selected as the best location based on the analysis of haulage profiles measured on long term incremental mine plans. A capacity of 22 million tonnes per year was considered achievable by the proven technology currently available. A detailed estimation of capital and operating costs of two systems - one with trucks only and another with trucks, crusher and conveyor - for the removal of 22 million tonnes per year of waste rock, showed substantial cost savings achievable by the proposed system. An economic evaluation of the two systems established the advantages of constructing the in-pit crushing and conveying system. This is now under construction and will be commissioned in early 1987. Experience gained in constructing and operating this installation is expected to influence decisions on similar installations in future.

Jan 1, 1986

By G W. Wilson

Rehabilitation of tailings impoundments is one of the most challenging aspects in mine closure, as not only does the potential for producing leachate pose a challenge to the rehabilitation designer, but also other aspects such as stability and settlement must be considered. The water balance of a tailings impoundment is unique in the sense that it usually hosts a pond that in turn causes a phreatic surface in the impoundment. The position of the phreatic surface defines the saturated and unsaturated zones in the impoundment, which of course varies spatially and temporally. Predictive modelling for this hydrologic system becomes difficult, as numerical models capable of analysing the combined saturated/unsaturated zones are not adequately refined to accurately solve the flux boundary problem for infiltration at the surface of the tailings. This paper describes the development of a flux boundary model that enabled accurate modelling of the unsaturated zone in the tailings impoundment at Kidston Gold Mine, Queensland, Australia. The technique made it possible to accurately predict the spatial variation of infiltration to the tailings as a result of the presence of the phreatic table. The conceptual model defines the boundaries for the Kidston tailings dam, based on a generalised cross-section through the dam. Firstly the shape of the top boundary is described as a function of the particle size of the tailings associated with particle segregation that occurs due to the hydraulic placement of tailings. This function was rigorously tested using in situ infiltration tests and laboratory materials testing. Defining the bottom boundary of the section, ie the phreatic level was done by physically monitoring the phreatic level with 42 piezometers strategically located on the tailings dam. Analysis of this data led to the fixing of this bottom boundary through the introduction of a function that mimicked the shape of the phreatic level. The material properties of the surface layer, specifically the saturated permeability that would govern the infiltration/exfiltration rates of moisture through the top boundary layer were defined on the basis of extensive field and laboratory material testing. A function for the saturated permeability was developed on the principles of particle segregation. Finally a procedure is described for the application of the new conceptual model for the evaluation of the spatial infiltration to a tailings surface using the rigorous one dimensional surface flux boundary code SoilCover. The solution of the calculation described above was then used as the top boundary condition in conventional three dimensional saturated/ unsaturated flow codes, and verified against measured seepage rates from the tailings impoundment under drains. It was concluded that the developed spatial flux function was in deed a most rigorous representation of reality. Although the methodology presented here was applied to the Kidston tailings impoundment only, the authors believe that the principles are directly transferable to any tailings impoundment that has a varying phreatic zone thickness due to the presence of a pond. The mathematical equations describing the typical cross-section would be site specific, but the approach and ultimate solution methodology would be directly transferable.

Jan 1, 2003

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

By Cairncross A. A

Papers on technical aspects of the Melbourne Underground Rail Loop project are being presented at this conference or have been presented previously or will be presented at other forums. This paper provides the framework for these papers by presenting the overall engineering tasks. The conceptual design, the special investigations undertaken, the management of the project and the construction development are highlighted.

Jan 1, 1981