Search Documents

By F M. Weir, M Fowler

A discrete fracture network (DFN) approach involves numerical modelling that explicitly represents how defects may be spatially distributed through a rock mass. A DFN is a 3D realisation of the ‘smaller scale’, non-deterministic defects; it is not an attempt to model larger, deterministic structures that should be identified as part of an engineering geology model. The approach utilises structural data in stochastic analyses to give a range of possible models that provides a tool for visualisation and analysis of a rock mass and indicates the potential large-scale slope or tunnel performance and stability.Stochastic fracture modelling for rock mass characterisation has significantly advanced over the past 25 years. With recent improvements to field data collection and computational power, it has become recognised internationally as a valuable tool for modelling some geomechanical problems encountered when designing excavations in fractured rock masses.This paper provides an introduction to the DFN approach, particularly the necessary input parameters and derivation of these from typical structural data sources, such as boreholes or scan line mapping. Of particular importance for engineering applications is validation of the simulated fracture network and techniques for doing so are discussed here.CITATION:Weir, F M and Fowler, M, 2014. An introduction to discrete fracture network modelling and its geotechnical applications, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 435–444 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

Salaries for mining professionals have gone up substantially in the last two years across most vocations and there has never been a better time to enter the industry, in terms of career opportunities and salary packages. With so many offers on the table and companies outbidding each other to attract the best talent, many new professionals are being lured in by the big money, sometimes at the expense of a satisfying career and a sustainable lifestyle. What should we consider when accepting a new position? What are our values, and how do these drive our decision making? This paper examines our core values as people and makes some observations about what it takes to really succeed in the mining industry.

Jan 1, 2006

By M Korte, J McMaster, C Brent

The Barrick Osborne concentrator has gone through a number of upgrades since commissioning and has increased production from the original 119 t/h design capacity to a milling throughput of 265 t/h in 2008. This was achieved incrementally over several years, by maximising operating efficiencies, in order to minimise capital expenditure, and take advantages of economies of scale; but more importantly it was reached with no measurable loss of recovery. Osborne currently processes a blend of underground and open pit material from the nearby Trekelano deposit. Following primary/secondary crushing, the material is processed through a rod/ball mill grinding circuit ahead of rougher/scavenger flotation that produces a copper concentrate. Osborne was seeking a further increase in plant throughput of the order of 15 per cent, but at more sustainable levels of secondary crusher plant utilisation. In early 2008, Osborne contracted Metso Process Technology and Innovation (PTI) to review the entire process from run-of-mine feed to final copper concentrate. This review would be done concurrently with surveys of both the crushing/grinding and flotation circuits being performed at the same time. The outcome would be a steady-state model of the complete flow sheet allowing the crushing/grinding model to interact with the flotation circuit model, such that overall process optimisation was possible. This was to apply both by exploring the operating limits of the currently installed plant, as well as looking at the logical next stage of capital plant expansions. Surveys of the crushing and grinding circuits were conducted at the Osborne concentrator in May 2008. The main objective of the surveys was to review the potential of increasing grinding throughput whilst maintaining the flotation feed 80 per cent passing size. This would also require improving the efficiency of the crushing circuit which was already operating in excess of 80 per cent of the time. Steady-state simulations were performed using the developed circuit models to identify opportunities to increase throughput and alleviate high circulating loads in both the secondary crushing and grinding circuits. Due to operational changes, the recommendations resulting from this project were considered by Osborne but have as yet only been partially implemented.  This paper covers part A or the crushing and grinding component of the project. A separate paper discussing part B or flotation is also being presented at this conference. The results of interactive simulations between the flotation and grinding circuit models are included in part B of this paper.

Jan 1, 2009

By B Hayter, M Carr, K Williams, C Wheeler, W Chen

Current trends into mining iron ore have seen an increase in the exploitation of problematic orebodies that would typically be disregarded. These bulk materials cause problems within all facets of the material handling stream, from remains left in train wagons to transfer chute blockages, which can cause costly downtime to mining operations (Roberts, 1998). These problematic bulk materials are referred to as wet and sticky material (WSM) due to the adhesive and cohesive nature they possess. Their characteristics can be computationally expensive to model. With the development of discrete element modelling (DEM), in conjunction with advancement in computational power over the past decade, it is now more feasible to model WSMs into the DEM technique.This research will couple two different contact models that can represent the characteristics of a WSM. These models include the Simplified Johnson-Kendall-Roberts (SJKR) and the Easo liquid bridging contact models. The SJKR contact model is an expanded form of the classic Hertz model. This model includes the tensile forces that are in the contact zone between two bodies when they are separated, which the Hertz model failed to capture (Johnson, Kendall and Roberts, 1971). The Easo liquid bridging contact model accounts for the capillary effects and surface tension that will form between two bodies, such as that of a WSM (Soulié et al, 2006). Both of these models were coupled to give the best representation of a WSM, which was simulated using MoleculeX™ (Chen and Williams, 2017) as the software platform.Additionally, this research also investigated the adhesion of problematic iron ore samples onto impact plates under dynamic conditions. An experimental set-up consisting of an apron feeder and inclined impact plate was utilised, to gain an understanding of the way the material builds-up and the possible modes of failure that could be experienced. This was undertaken for different wall liner materials, wall liner angles and moisture contents of the iron ore samples. From this, a series of DEM calibration simulations were conducted on the experimental set-up and particle size distributions (PSD) of the iron ore samples. This enabled forming of a database of parameters, which can be scaled for on-site applications in relation to geometry of the plant and PSDs that would represent run-of-mine ores.CITATION:Carr, M, Williams, K, Chen, W, Hayter, B, Roberts, A and Wheeler, C, 2017. The dynamic adhesion of wet and sticky iron ores onto impact plates, in Proceedings Iron Ore 2017, pp 511–518 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

The criterion for assessing the accuracy of coal reserve estimates proposed by Philip and Watson (1982) is criticized.Following Royle (1977), it is suggested that the global estimation variance found by geostatistical methods is more appropriate.This method is applied to coal data from the Bowen Basin. This shows that two factors (the inherent variability of the variable under study and the total number of drill holes) have more influence over the accuracy of the reserve estimate than the form of the drilling pattern. Comparisons between the relative errors for different sized regions demonstrate that the spacing between drill holes is of secondary importance. The dominant factor is the total number of holes.Comparisons between the relative errors show that some variables such as sulphur need a much denser sampling than the others to obtain the same level of precision.

Jan 1, 1983

By L Mottola

Three decades ago mining companies, principally in North America, aided by machine and explosive manufacturers, started significant attempts to develop and implement automated mining systems, mainly underground. These tended to be motivated by decreasing cost, increasing productivity, reducing labour requirements, and improving safety. These are important business drivers, however, little attention was given to the underlying goal of mining automation, namely to bring upstream processes in control and reducing variation, as seen in downstream mineral processing plants.This paper first reviews the nature of Lean Thinking and its application in the context of the growing commitments by industry to develop future automated mine production systems. The paper then makes reference to prior and current experiences in open pit blasthole drill and shovel performance monitoring, to demonstrate the principle that machine performance data offers as a means, not only to characterise the dynamic geological and working environment, but also to provide a foundation for automation. In this case, drill and shovel monitoring was originally motivated as a means to optimise blast fragmentation through more effective drill and blast designs that are based on an accurate determination of the bench geological and geotechnical characteristics, hence managing variation in the drilling and blasting process. This paper considers how automating and integrating such components of the mine production system would bring processes into a controlled state, creating value at the face, within a framework of Lean mining.

Nov 22, 2011

Coagulation-Neutralisation Technology to Treat Wastewater from Lead-Zinc Concentrator

Sep 13, 2010

By M S. Powell

In this paper it is argued that we are entering a new mining era, based on considerably more challenging orebodies as we rapidly expand minerals production by exploiting previously uneconomic deposits. Rapidly increasing production costs cannot be sustained by continually increasing commodity prices, as illustrated by the recent downturn in the industry.Driven by reduction in grade, requiring the processing of 50 to 100 per cent more ore to recover the same amount of metal, often accompanied by finer grain structure - necessitating a finer product size and more challenging recovery - the productivity of the mining industry is dropping in real terms. The author suggests that tweaking current technologies and relying on economies of scale will not turn the industry around, but rather a switch to considerably more efficient processing is required.It is imperative to utilise the properties of the orebody, especially in terms of variability, in revolutionising our processing techniques. Our new mantra may be æselective mass mining with flexible processingÆ. This paper explores how this may be implemented using current technology and equipment in order to change the cost profile of the new mining industry. Orebody knowledge, based on the underlying process drivers, rather than proxies, is required. These properties and their variability will need to be propagated into the orebody through utilising the geological data rather than smoothing block averages, which destroys information on variability.Novel flexible circuit designs are presented that can respond to a wide variability in ore properties and throughput requirements in order to slash processing costs and energy utilisation, while enhancing overall recovery. The success of these circuits will be based on an ability to predict at both design stage and in everyday processing the variable ore properties, which is dependent upon reliable orebody knowledge that caries variability and underlying processing properties.CITATION:Powell, M S, 2013. Utilising orebody knowledge to improve comminution circuit design and energy utilisation, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 27-36 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

The hematite deposits of Quadrilßtero Ferrffero (QF) are hosted by the Proterozoic itabirites of the Itabira iron formation (Harder and Chamberlin, 1915). These deposits are widely distributed at QF and include the hard hematite ore bodies. However, considerable variations in ore structure and texture can be observed. A preserved banding and lamination in the thin bedded, compact hematite ore, apparently reflects the original layering and/or the prominent foliation of the partly or completely replaced itabirite. The structure of the hematite ore deposits varies from almond shaped, rootless, to bedded bodies, both concordant with the main foliation, and to mesoscopic veins and irregular bodies. Hematite ore textures, which depends on the structural characteristics of the deposit, may be grouped into four main types:thin bedded, laminated and banded; micaceous, foliated and schistose; brecciated; and compact/massive. Thin bedded ores occur in the western, central and subordinately eastern portions of QF, while submicaceous, micaceous and schistose ores are predominant at the eastern part. Brecciated ores exist mainly at the western part and subordinately in central QF. Structureless, compact hematite ores may be either related to the brecciated hematite or occur as isolated bodies at central QF. It is suggested that a synkinematic, acid and oxidant, metasomatism during metamorphism, under a ductile regime, was responsible for the hard hematite ores of the types 1 and 2, and a static, subsequent, hydrothermal, regional metasomatism, under brittle regime resulted in the formation of the types 3 and 4. The common texture present in the all ores is the ubiquitous magnetite porphyroclasts replacement by hematite. Quartz and other silicate minerals are also substituted by hematite. Muscovite, tourmaline, talc, chlorite, apatite and kaolinite have been recognised in the hard hematitic ores. Apparently that mineral association denotes different equilibrium conditions of formation.

Jan 1, 2002

By D M. Aranha, M A. Fonseca, M Echtern

The regional syndeformational metamorphism affecting the Itabira Iron Formation (IIF) at Quadrilßtero Ferrffero (QF) was formerly discussed by Dorr (1965), who proposed that quartz grain size could monitor the metamorphism, according to James (1955), and that the formation of haematite could be the result of the synchronous metasomatic process. Herz (1979) suggested the existence of three metamorphic zones, not mentioning the haematite formation. It could be observed that the primary oxide phase in the IIF is magnetite and most of the hard haematite was derived from the metamorphic replacement of magnetite, forming micaceous or schistose haematite. Differently from most iron formations in the world, the formation of haematite deposits at QF occurred under high oxygen fugacity during metamorphism. The haematite microlaths display a strong preferred orientation, which determines the alongated shapes of the fragments. The terms foliated and unfoliated haematite have been applied by Dorr to the micaceous or schistose haematite, and to the isotropic, hydrothermally derived haematite. Under the microcope, the haematite exhibits a strong crystallographic or lattice orientation encircling the magnetite and martite porphyroclasts. The strain rate determined and defined the textural variation, size and economic importance of the deposits and the ore grade. Metamorphism at QF increases eastward and resulted in the formation of a gruneritic Fe-Mg amphibole, at the western portion, followed by a cummingtonitic amphibole at the central-western part, succeeded by the actinolite zone at the central-eastern part, and finally to the tremolite-anthophyllite zone to the east. These zones, arranged in a north-south pattern, can be followed in the pelitic units, whereas appear sericite-chlorite, kyanite-chloritoid and garnet-staurolite respectively. Carbonate geothermometry in IIF also may support the metamorphic variations. At the western zone the haematite forms small lenses within the itabirite, P-contents are slightly higher than in the remaining IIF, haematite grain size is minute, resulting in a submicaceous texture and the amount and dimension of relict magnetite within haematite is greater than in the other parts of QF. Jangada and Serra Azul deposits are examples of this zone. The central-western zone is characterised by significant haematite deposits, in considerable quantity and size, haematite grain size increased, in order to produce a micaceous texture, the P-contents and the amount of magnetite decreased. Pico do Itabirito, Cappo Xavier, Capitpo do Mato and Tamanduß correspond to the deposit type of this zone. At the eastern-central portion the amount of the hard haematite deposits decreases, increasing the soft haematite ore due to higher strain rates. However, it can be perceived that the relict magnetite almost disappeared and the haematite grain size became coarser than the haematite from the western zones. At the eastern zone, the haematite deposits exhibit typical schistose texture, the magnetite porphyroclasts are absent and the lowest P-grades in the haematitic iron formation. The haematite bodies characteristic from this zone are Andrade, Morro Agudo and the deposits at the Itabira District. The hydrothermally derived compact and isotropic haematite deposits, formed subsequently to the micaceous haematite bodies, were generated after deformation ceased, but under very high fluid pressure. The metamorphic reactions magnetite + quartz + H2O = grunerite + haematite and magnetite + quartz + H2O = grunerite + O2 were decisive in the formation of the metamorphic haematite deposits.

Jan 1, 2007

Australian coals tend to be young in geological age and high in ash by world standards; preparation of the coal before marketing is almost universal. On the basis of float and sink data from 39 locations in the Eastern Australian coalfields, the coals are placed in four categories representing increasing difliculty in their washability characteristics. These seem to be related neither to the geological age nor the geographical position of the deposit and Hunter Valley coals, for example, span all categories. The influence of crushing on the washability of Australian coals is briefly considered and from limited data it is concluded to be appreciably smaller than for British or North American coals. A strategy for the float and sink analysis of Australian coals is proposed and the influence of washability characteristics on current trends in the selection of separating processes for coking and steaming products is discussed.

Jan 1, 1979

By T N. Little

The grade control process undertaken at mines aims to maximise the value of the ore (valuable product) mined and fed downstream for processing or sale. The full range of grade control activities includes: reserve estimating, drilling/sampling, assaying, modelling, ore block design, blasting, ore mark out, excavating, stockpiling, processing and reconciling. Over the last 25 years, the grade control process has undergone significant improvements and this is in part due to the developments in grade control blasting. This paper discusses the development and classification of grade control blasting applications in surface mining. A review by the author in 1988 (Little and van Rooyen, 1988) is used as a benchmark for discussing the very significant progress that has been made.Two major technology initiatives have enabled this development. The first was the development of a method for the measurement and analysis of total displacement during the blasting process. Currently, the Blast Movement Monitor (BMM®) is a practical tool that has been used around the world to improve the industry’s understanding of three-dimensional blast movement dynamics. The second technological enabler was the development of electronic detonator systems. The unique aspects of electronic detonating systems are their higher accuracy and that all detonators are activated at time zero (initiation). From a grade control blasting perspective these features and other improvements allow experimentation and, ultimately, more complex, multiobjective blasts to be designed and implemented.This paper reports on a classification and review study undertaken by the author. In all, five selective blasting methods and nine bulk blasting methods are classified and reviewed. Five important observations are made: there is value in classifying the range of grade control blasting strategies, and the blasting objective framework presented is helpful in this regard the range of strategies available to designers is increasing as enabling technology develops, so too do the ambitions of blast designers and the expectations of downstream customersgrade control blasting and Mine to Mill concepts are merging, and this paper caters for this trend using multiple blasting objectiveshaving a technical primary blasting objectives framework, combined with the classification system presented here, should assist practitioners and stakeholders with lateral thinking in regards to future technological innovations, grade control blasting and Mine to Mill initiatives.CITATION:Little, T N, 2015. Classification and development in grade control blasting for surface mines, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 343–354 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

THOSE who dabble in mining are no exception to the general rule that persons who know a little of a subject are apt to think that they know all about it. Some colour may be lent to the belief that anyone may succeed in mining when we hear stories ofsuccessful diggers and others who have accidentally dropped on to something good through no foresight on their part; but we seldom hear the contra account of the far larger number who fail. Those who go more thoroughly into the subject, and take up mining as a profession, know very well that it is not one that can be carried out successfully by rule of thumb, but when they point this out to the public they are credited with trying to make it a closed profession; and outsiders are for ever trying to find out the "trade secrets," at the same time spurning the main one, which is hard study, experience, and the ability to apply their knowledge. The average mining man is not rich. When he amasses a fortune it is generally through speculation rather than professional work, thought no doubt his technical knowledge may have assisted...

Jan 1, 1910

The principal source of funding the working capital requirements of gold miners has traditionally been equity. However in the 1980s, with a substantial increase in activity in the exploration for, and the production of, gold the traditional sources of equity finance became no longer sufficient to meet demand. With the often high cost of raising equity, the need for developing alternative financing structures became critical, especially since the stockmarket crash of 1987 which at least until recently, adversely affected the amount of equity capital available for investment in mining.

Jan 1, 1994

For its Hellyer project, Aberfoyle sought to establish a high degree of confidence in all aspects of the feasibility study. Accurate capital and operating cost estimates were an integral and essential part of the study. They were crucial to the evaluation of investment returns and competitive cost position. Both the capital and operating cost estimates were based on the comprehensive data available from exploratory mine development, pilot plant operation, detailed engineering design, and Aberfoyle's experience in the area. One of the principal project objectives was to maximise operating productivity and efficiencies and this created capital cost alternatives which needed thorough cost-benefit assessment. The estimated capital cost for construction and development was $90 million, and the project was completed virtually on time for $80 million. The first year's experience indicated that operating costs would settle to well within 10% of the estimates.

Jan 1, 1990

By L Edwards, M Haest, D Mittrup

The focus in the iron ore industry has shifted from increasing production volumes with less regard for cost, to efficient production of quality tonnes. BHP Billiton iron ore geoscience and exploration has embedded infrared spectroscopic sensing of drill hole samples to help meet this challenge.Infrared spectroscopy is delivering mineral predictions that are used for (automated) geology logging and modelling. The spectra are processed together with other available data sets to predict geometallurgical and geotechnical variables that include lump per cent and uniaxial compressive strength.Trials are ongoing to test the benefit of infrared spectroscopy during mining, including the analysis of grade control samples and remote sensing of mine faces. Results show great benefits in the fields of short-term geology modelling, better understanding of material (handling) properties, identification of geotechnical risk areas and high resolution ore-waste delineation.These trials are bringing BHP Billiton iron ore closer to its ultimate goal of having infrared spectroscopic data collected across the mining value chain. Once such data are available everywhere, regression models can be trained at one point (eg iron grade model trained on exploration samples) and be applied elsewhere (eg iron grade predicted on mine faces). Such predictive analytics will enable not only high precision mining, but also provide maximum time to tailor plant design to the ore in the ground, based on learnings from ores processed in other plants. This will improve planning outputs that will eventually increase mining efficiency, processing capability and product quality.CITATION:Haest, M, Mittrup, D and Edwards, L, 2017. Infrared spectroscopy in BHP Billiton iron ore with a focus on in-mine infrared sensing, in Proceedings Iron Ore 2017, pp 549–556 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

Mechanism Responsible for Flocculation in Poly (N-Isopropylacrylamide) Temperature Responsive Dewatering - Attractive Interaction Forces Induced by Surface Hydrophobicity

Sep 13, 2010

Casing or lining pipe is used in boreholes for the following reasons:1. To preserve the hole while drilling and after it is finished.2. To shut water out of the hole or to isolate any particular water, gas, or oil-bearing stratum.Deep holes can seldom be drilled without casing, and only when in firm strata. If caving from the walls is at all likely while drilling, casing is necessary in order to prevent the tools horn being buried...

Jan 1, 1924

By Greaves M. C, Amos M. D

A study was made of the instrumentation and technique of atomic absorption spectroscopy developed by Walsh of the Commonwealth Scientific and Industrial Research Organisation (C.S.I.R.O.), Australia.The method was evaluated for the determination of silver in lead sulphide concentrate. The precision of the procedure developed is equal to that of the uncorrected fire assay method and the accuracy is greater.Brief mention is made of the use of this technique for the determination of silver and other elements in ores and concentrator products.INTRODUCTIONThe fire assay method, although accepted on a world-wide basis as the umpire method for the determination of silver in ores and concentrates, is freely recognized as yielding results which are lower than actual due to unavoidable losses.King (1934) investigated the influence of the cupelshape, size and material on silver losses during cupellation. Using 100 mg silver prills he recorded silver losses ranging between l. and 10 per cent under extreme conditions and averaging approximately 2 percent under conditions which might be considered normal. Guerin (1957) made a detailed study, under carefully controlled conditions in a furnace similar to that described by Esdaile (1952), of the effect of temperature on silver losses during cupellation. He concluded that if cupellation were carried out at 840°C., then the amount of lead retained by the silver prill was insignificant and that the silver losses were governed by the equation: Y = 0·055 XO.74where X = the final weight of the silver priIl (mg)and Y = the silver lost (mg)

Jan 1, 1961

This paper is an outline of the developmental practices now in use at North Broken Hill Limited, N.S.W. The description will be given under the following headings.I. General.......opening up of a new level.II. Driving.III. Winzing.IV. Rising.V. Auxiliary Ventilation.VI. Notes on the Introduction of Mechanical Appliances.VII. Office Records and Routine.I. GENERALThe lode, for purposes of description, may be said to be divided into two portions which are usually referred to as the Southern and Northern Orebodies.The southern ore-body is the larger and in places attains a width of 200 feet. The northern ore-body is, generally speaking, comparatively narrow. These ore-bodies have a northerly pitch of approximately 45' and a westerly dip of 60. In the southern ore-body a grid of ore chutes is provided at 31 ft. 8 in. (5 square set) intervals and this necessitates an elaborate arrangement of cross-cuts, portion of which have to be driven through the foot-wall. Crushed country rock adjacent to the foot-wall makes it necessary for drives to be placed at least 60 feet from the lode.In the northern ore-body the ore chutes are arranged along a longitudinal drive, thus making a much simpler layout. These layouts were described in detail by A. R. West (Proceedings A.I.M.M. No. 117). In opening up a new level from the shaft plat, a heading is extended in a westerly direction until a point approximately 60 feet from the footwall of the lode is reached.At this point the direction of the cross-cut is altered to a bearing approximately 90 to the general strike of the ore-body, and the cross-cut continued until the hanging-wall is intersected. From the information obtained together with that from diamond drilling, the outline of the ore-body is plotted as closely as possible, and this serves as a basis for the layout of the level. Drives south and north from the main cross-cut are made in order to determine the southern and northern extremity of the southern ore-body. The former is usually driven in the centre of the ore-body and serves as a permanent gangway and ventilation drive for the new level.From the northern extremity of the southern ore-body, the drive north is...

Jan 1, 1944