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By G Turner-Saad

An improvement to cut-off grade optimisation theory based on geometallurgy has been completed. The improvement fundamentally consisted of taking into account mineralogical and textural characteristics instead of grades. These characteristics are related to the spatial variability of mineral abundance, association, particle size and liberation properties. Additionally, the improve- ment considered the spatial variability of mineral processing liberation and selectivity properties associated with mineralogy and texture. The enhanced optimisation enables estimation of the economic value of mining operations based on an optimum cut-off policy attributed to liberated and selected ore minerals.The enhanced optimisation was developed as an essential component of a joint cut-and-fill mining and mineral processing methodology based on mixed integer mathematical programming. The formulation considers static and dynamic modifying factors that vary over the projected life of mining. The objective function of the mathematical formulation consists of maximising the realistic expected economic value of concentrates or products of liberated and selected ore minerals, whilst minimises liberated and selected gangue minerals. The optimal solution is obtained when the objective function is subject to geological, mining, processing, marketing, smelting, refining, environmental and financial constraints. The methodology accesses geometallurgical multivariate resource models, which integrate the spatial variability of mineralogical and textural characteristics and mineral processing liberation and selectivity properties.The geometallurgical process concurrently optimises stope geometries, ore reserves, mining sequences, and mining and mineral processing production based on the enhanced cut-off of liberated and selected ore minerals. In addition, the process considers additive and non-additive transfer functions associated to mutually exclusive geometallurgical spatial domains. The transfer functions also take into consideration the blending of mineralogical and textural characteristics with mineral processing liberation and selectivity properties.This contribution presents an example of cut-off grade optimisation via mineralogical and textural characteristic, and liberation and selectivity processing parameter optimisation for a spatially variable orebody.

Sep 5, 2011

By M Danišík

Two drill core samples of haematite/goethite from the Robe River (Western Australia) channel iron ore deposits (CID) were dated using (U-Th)/He methods in order to constrain the timing of iron oxide formation and thereby provide a temporal context for CID genesis. (U-Th)/He ages (He ages) from these samples range from the late Oligocene to Late Miocene and despite a high degree of scatter, they corroborate relationships expected from the internal ooidal stratigraphy: For individual ooids, the ages from haematitic core are older than or indistinguishable from the ages of the surrounding goethitic cortex. The goethitic cortices are, in turn, older than the ferruginised wood fragments recovered from the cementing goethitic matrix.The data suggest the following succession of ore formation phases:• Haematitic cores in ooids of both samples formed in the Early to Middle Miocene.• Goethitic cortices of both samples formed in the late Middle to early Late Miocene. This appears to be the age of goethite cortex formation regardless of depth in the core, which does not support the top-down infill model, genetic model proposed by Heim et al (2006).• Wood fragments form a prominent component of the matrix and were ferruginised during the Late Miocene. Thus the data suggest that the unique environmental conditions for the CID formation existed during the Miocene.A methodological implication of this study is that the temperature utilised for He-extraction from iron oxides has a critical impact on the mobility of parent nuclides. The typical ~1100°C laser heating used for crystalline minerals like apatite or zircon induces loss of U and Th and results in erroneously old ages.

Jul 11, 2011

By L Nienaber

Mines, after becoming operational, often retain the same support and reinforcement designs developed in the feasibility study. These designs are conceived from limited drilling data and regional experience, thus having an empirical flavour. Empirical designs are perceived to be conservative, catering for a variety of failure mechanisms, which are not always present in mine development drives.This begs the question: If you were to invest in the necessary resources to obtain sufficient data and complete the required analyses for the different development drives in the mine, to engineer a support and reinforcement scheme with the capacity to match the demand of the rock mass, what is the difference in cost when comparing an empirical design to an engineered design?To answer this question, mine tunnels with different geometries and orientations, where detailed structural data was available, were selected for a comparative design exercise. Material cost, development cost, cycle time and professional fees for engineered and empirical designs were estimated. The outcome is summarised in the following paper that discusses the process followed and the results of the design comparison.

Mar 8, 2011

By E McLean

The decision making check-list and hierarchy of information for process and plant design is generally wide-ranging and complex. The nature of grades, mineralisation and ore types in an ore body, its mine development sequence, and the body of results from metallurgical and physical test work present complex and competing influences on flowsheet development, values for design, equipment selection, plant efficiencies and operating strategy. The challenge is how to manage all these variables, to understand their impacts on performance, and how best to provide a cost-effective plant design and robust process that meets daily/weekly/monthly operating objectives. Throughput, production and grade or product specifications need to be met. The ore body is not average; its range of metallurgical and physical characteristics may be moderately to highly variable. This paper assesses some of the key competing influences and conflicting issues in design and equipment selection, and their effect on production and performance expectations.

Aug 8, 2011

By P Kittler

In the spectrum of mining-related disciplines, geometallurgy sits between resource geology and metallurgical engineering. Unlike its neighbours, it is a relatively young discipline and its concepts, procedures and techniques are still evolving. Relevant geometallurgical issues differ from one deposit to the next so there is no single template that can be used in all situations, meaning that geometallurgy programs are nearly always customised and tailored to the deposit and the situation.Over time, a number of key mistakes are seen to emerge regularly. The eventual impact of these mistakes can vary from suboptimal performance of mine and plant to complete failure of the operation. For instance, poor characterisation of ore lithologies and their spatial distribution can have negative impacts on processing plant throughput. However, when combined with failure to identify critical blending constraints it can result in a totally inoperable plant.A number of common mistakes committed during geometallurgical programs are discussed and some preferred alternative approaches are suggested

Sep 5, 2011

By K Schonert, K Eichas

Electrostatic separation of non-conductive materials can be accomplished by triboelectric charging. The efficiency of convential separators becomes worse in the size range below about 100 ¦m. These problems are solved by developing a new double-drum-separator. The investigations have shown the possibility of separating very fine mineral mixtures (eg quartz/calcite) in a strong electric field after tribo-charging in a special dust-feeder. The paper reports about the influence of particle size and field intensity on the separation and deals furthermore with the problem of desagglomeration.

Jan 1, 1993

By R R LARGE

In the past decade mineral deposit models have become an important tool for the exploration geoscientist. By combining genetic theories on the formation of particular deposit styles, with geological, geochemical and geophysical criteria relevant to ore location, it has been possible to more effectively focus exploration effort to the regions and local targets which have the best chance of success. However, such models have their limitations, and must be carefully and critically applied and continually updated as new technical and research information becomes available.

Jan 1, 1992

By White L. R, Boger D. V

The paper describes the surface chemistry and particle physics that control the fundamental flow properties (Theology) of mineral particle slurries. We further address, through a series of case studies, the design data that emerges from experimental studies of the flow properties of complex, high volume fraction mineral slurries. The case studies are drawn from mineral oxide concentrate processes, tailings dewatering operations and from filter cake production and management. The paper emphasises the essential links between design of process slurry handling systems and the control of the flow of such slurries by control of the pulp chemistry.

Jan 1, 1992

By T QUINLAN

A resource estimate uses data obtained by sampling an orebody. An example is described in which a random drilling pattern did not provide a representative set of assays, and the estimated resource was significantly less than the mine production. It is believed that a better estimate would have been made if the exploration holes had been drilled on a regular grid.

Jan 1, 1992

By Prince R. G H, Guerney P. J, Frew J. A, Vanderkruk C. R, Wanigasekara-Mohoti D. K

This computer-aided design system for mineral processing flowsheets which are based on froth flotation, size reduction and classification combines an expert system for generating flowsheet structures with numerical models for the physical processes and the economics. Design decisions, such as specification, size and placing of process units and the destination of recycle streams, are based on clear technical and economic criteria. These decisions are controlled by user-set parameters, which allow the incorporation of industry experience and preferences and the generation of sets of good designs, from which choices may be made by further criteria, such as controllability. Liberation is now fully modelled and the early results from this extension continue to suggest potential substantial increases in added value over conventional approaches.

Jan 1, 1997

By K J ROSENGREN

Underground rock mechanics was initiated as a formal discipline in Australia by early studies for underground structures for the Snowy Mountains Scheme in the 1950s. These techniques were quickly embraced by underground mining and there has been steady development to the present time. The paper reviews the status of current techniques for rock mechanics studies and discusses some important issues such as ground support, mine filling and caving. It concludes that a considerable degree of engineering judgement is still required for the practical application of rock mechanics to underground mine design.

Jan 1, 1992

By Fickera M. A, Marshall S, Burgeese F. L, Burgees J, Estrina H

A new high intensity flotation process FASTFLOT was deployed to recover residual zinc from the zinc circuit tailings at Pasminco Mining's Concentrator, Broken Hill. Performance of the FASTFLOT process is discussed with respect to various size fractions. Results suggest that the process has an affinity not only for fine particles but also for +200 ¦m particles which the conventional flotation cells failed to recover. Various strategies for FASTFLOT deployment are also discussed.

Jan 1, 1995

By AJ LYNCH

Broken Hill metallurgists have been responsible for some of the most important developments in mineral processing technology. These occurred mainly in two periods, 1902 - 15 and 1955 - 70. Mineral flotation was developed as an industrial process during the first period and this happened in two stages, the recovery of zinc minerals from the tailings dump accumulated during the gravity concentration of the oxidised ores and the selective recovery of galena and marmatite during flotation of the primary ores. During the second period fast accurate analytical procedures were developed to provide rapid assessment of process performance, and new means of controlling the process were devised which improved throughputs, grades and recoveries. These technological successes were due to the skills of the metallurgists and the commitment of the companies. They brought large financial returns. They were achieved under difficult circumstance. There are important lessons to be learnt from these successes.

Jan 1, 1992

By D H MACKENZIE

In common with several great orebodies and mineral camps around the world Broken Hill has been the subject of state-of-the-art technical and scientific scrutiny during its long working life. During the early years geological interest in Broken Hill tended to be directed at the body for its intrinsic scientific worth, mainly on account of its large size, high grade and wealth of mineral species. For much of the last 60 years the interest has had a more applied motivation, namely, to assist the search for either repetitions in the Broken Hill field or analogues in other terrains. This paper looks at the major changes in geological concepts and exploration techniques applied at Broken Hill and attempts to assess their impact.

Jan 1, 1992

By T O Aspinall

The Australian mineral industry involves a diverse range of expertise and skills. Within that, the mining industry, representing mine planning, mine management and equipment operation, has capital intensive, high productivity equipment and a small but skilled workforce. Continuing education for all personnel in the workforce after formal school courses will be an important contribution towards improving competitiveness. The non-tertiary sector represents a significant proportion of the workforce and requires as much attention as the tertiary educated group. Competency Based Training is now being developed for the mining industry in Australia under the National Training Board and the mining industry is well represented in establishing standards and curriculum. TAFE is a major source of accredited courses but some mining companies are also developing internal courses not necessarily for external accreditation. Articulation of such accredited courses to tertiary mining engineering courses has been considered. The education and training of equipment operators through continuing education requires attention to operating skills, an understanding of the productivity factors under the direct influence of the operator and providing product quality to the customer. The education and training of mining engineers has been widely covered and continuing close involvement of the mining industry is required to ensure well balanced courses in technical and interpersonal skills as well as motivation to continue learning for life. Postgraduate research is a part of continuing education but the mining industry has to continually address the adequate recognition of post-graduate qualifications for the increased technical or management expertise and the development of better analytical and problem solving skills which can be directed towards improving competitiveness. More attention has to be paid to providing adequate financial incentives to attract suitable students, particularly after attaining some experience, and to address their professional career path with a company so they are not significantly disadvantaged by undertaking post-graduate studies. The Chartered Professional Engineer status as provided by The Institution of Engineers, Australia to qualified candidates is being considered by The Australasian Institute of Mining and Metallurgy as a further recognition of a member's specific expertise and competence in mining and metallurgical engineering. Continuing education plays a major part in the maintenance of the expertise and competence required for a professional engineer to develop and also to retain chartered status. Continuing education will be a significant part of the education and training of all the mining workforce towards improving the competitiveness of the mining industry. The major challenges will be the motivation of all towards lifelong learning and the integration of the various programs towards providing the opportunity for a steady and satisfying career progression.

Jan 1, 1994

By J Y. C Lo

The construction of two drainage tunnels and the associated subvertical drain system at the Po Shan area in Hong Kong was completed in December 2009. This project is the first of its kind to utilise drainage tunnels and a network of subvertical drains to regulate the groundwater table to enhance the long-term stability of the hillside of Po Shan area.The groundwater levels, monitored by preinstalled piezometers, once exhibited dramatic drops during drilling of the subvertical drains; however, have recovered from natural replenishment after effectively plugging of the drains. The level of groundwater drawdown is in line with the design function of the subvertical drains. In order to understand the groundwater flow pattern in the Po Shan area during and after construction and to set out operation schemes for the subvertical drain system so as to control the groundwater table in the Po Shan area, a post-construction review has been carried out to examine the behaviour of the drainage system and its impact on the surrounding subsurface groundwater flow.This paper presents a review of the groundwater monitoring data during and after the construction of the drainage tunnel system covering a period of over 3.5 years. A simplified conceptual hydrological model is developed, which has been verified by the monitoring data, to capture the key elements with regard to groundwater variations in different stages of the construction. The performance of the tunnel and subvertical drain system as revealed from these field measurements is discussed.

Mar 8, 2011

By J D. Goldsworthy

The McPhee Creek bedded iron deposit is a recent discovery made by Giralia Resources NL (Giralia) in the northern Pilbara of Western Australia. The deposit lies 30 km north of the town of Nullagine along the southeastern margin of the East Pilbara Granite-Greenstone Terrane (EPGGT).The McPhee Creek area is located in the Kelly Greenstone Belt in the southeastern part of the EPGGT. The Archaean aged greenstone belt consists of volcanic and sedimentary sequences including the Warrawoona Group and the Gorge Creek Group. The McPhee Creek iron ore deposit lies within banded iron formation (BIF) rocks of the Gorge Creek Group. The structure of the McPhee Creek area is dominated by a northeast trending, upright synform (Sandy Creek Syncline) and associated folding that is truncated by northeast trending faults in the east. Iron ore mineralisation is predominantly stratabound and follows the dip of the bedding – however, in some areas, particularly in the southwest of the deposit, mapped steep to moderate dips of bedding planes are at odds with underlying fl at mineralised zones in drill sections. Zones within the deposit that contain substantial thickness of iron ore correspond to areas of complex folding suggesting structural control and iron enrichment in fold hinges. Petrographic analyses confirm mineralisation is goethite dominant and the deposit is strongly supergene enriched.Giralia initially identified iron ore potential in the McPhee Creek area through the presence of a small known channel iron deposit (CID) mesa. Giralia began exploration in 2008 by re-drilling a portion of the CID (subsequently named Crescent Moon) and reported a small low-grade Inferred Mineral Resource. Target generation in the wider area utilising Geological Society of Western Australia maps and Ikonos satellite images identifi ed strongly ferruginous outcrops associated with major structures along an 8 km long range located 2.5 km to the west north-west of the Crescent Moon CID deposit. In late July 2008, a total of 62 rock chip samples were collected during a helicopter supported sampling program conducted at McPhee Creek. Samples taken from haematite-goethite enriched BIF and canga zones outcropping intermittently over the 8 km length of the western and central areas of the prominent range assayed up to 63 per cent Fe. These zones represent the discovery outcrops and surface expression of the McPhee Creek main range iron ore deposit.Follow up sampling, geological mapping, bulldozing of access tracks and ramps and reverse circulation (RC) drilling commenced in September 2009. A maiden Inferred Mineral Resource was announced by Giralia to the Australasian Securities Exchange (ASX) on 15 December 2009.The current Indicated and Inferred Mineral Resource at December 2010 stands at 260 Mt grading 56.2 per cent Fe, 0.12 per cent P, 6.7 per cent SiO2, 2.3 per cent Al2O3 and 9.5 per cent LOI at a 50 per cent Fe cut-off. McPhee Creek is one of the largest iron deposits found in Archaean BIF in the northern Pilbara.

Jul 11, 2011

By M Z. Abzalov

Drilling mineral sand deposits has specific challenges, which are different from drilling hard rock deposits: Drilled sequences are represented by non-consolidated free-flowing sands to semi-consolidated clayey sands and indurated layers. Valuable heavy minerals (ilmenite, rutile, zircon, leucoxene) have an average density of 4.6 g/cm3, which is significantly heavier than the hosting sand matrix; mainly represented by quartz (density = 2.6 g/cm3). The large difference in the mineral densities can result in sample segregation in the drilling rods and capturing devices causing biased composition of the recovered samples. The drilled strata can contain beds of consolidated sediments, hard pan lenses and concretions. Therefore, chosen drilling equipment should be flexible and permit a switch from drilling the free-flowing sands to hard rock drilling. Thickness of the sand hosted mineralisation varies from several metres to more than 170 m. Mineralisation is distributed above and below the water table. Evaluation of the mineral sands deposits is based on hundreds of drill holes and many thousands of samples, therefore drilling methods should be fast and cost effective. The drilling methods commonly used for mineral sand deposit evaluation, include aircore, triple tube diamond and sonic; including its variants, such as vibrocore drilling technique. The ability of the studied drilling techniques to properly address the above listed challenges in mineral sand deposits, whilst maximising the quality of the obtained samples has been compared in three deposits: Corridor Sands (Mozambique), Richards Bay (Republic of South Africa) and Fort-Dauphin (Madagascar).This study has shown that aircore samples tend to be negatively grade biased, underestimating the heavy minerals content, in particular when drilled intervals are located below the water table. Triple tube diamond core method can produce non-biased samples. However, results can be marred by incorrectly chosen drilling mud. Sonic drilling is a relatively new technique based on a high frequency vibratory technology. It is the only production drilling technique that allows a continuous relatively undisturbed sample of unlithified sands to be obtained. The main limitations of this technology preventing its wider use for developing mineral sand resources are the relatively high drilling costs, in particular when the depth of drilling exceeds 100 m, and speed of drilling advance.

Oct 5, 2011

By A Buckley

Many policy issues facing the mining industry and affected communities are at a level of complexity that they can be called ‘wicked’ problems. The term ‘wicked’ in this context is used, not in the sense of iniquity, but rather as social and economic issues highly resistant to resolution. For the resource extraction sector and affected communities there are an array of challenges embedded in the industry’s production and profit paradigm, the remoteness of mineral reserves and affected communities’ expectations of economic benefit and a positive legacy. The mining industry as a whole is dominated by economic, political, legislative and market structures that influence and constrain interactions between mine operations and local communities. For communities, with particular reference to regional Western Australia, intractable problems include the uncertainty of, yet increasing dependence on, a mining economy. Questionable outcomes for local communities include the limited realisation of local employment and business development benefits, and low overall outcomes or low multiplier effects. ‘Wicked’ problems, according to the literature, are best addressed via collaboration. In the mid-west region of WA, with mining and infrastructure construction underway, alliances have formed between mining companies, the major port and rail infrastructure project (Oakajee Port and Rail) and regional and local governance stakeholders. The major impetus for these affiliations is to expedite planning and associated infrastructure development taking into account the lessons from other mineral-led regions. What has resulted is an array of innovative approaches to stubborn problems including planning well in advance of full-scale mining; regionally coordinated procurement; ‘mine ready’ local businesses; and strategic investments in social infrastructure; including community trust funds paid in advance of project delivery. This paper examines these innovative approaches/alliances and assesses their effectiveness in addressing long standing mining/community dilemmas.

Nov 22, 2011

By Mahyera A, Sakashita B, Ahmed U, Abou-Sayed AS

Gas in U.S. coals is primarily composed of 90 to 99 percent methane and up to 10 per- cent carbon dioxide. In composition and heat- ing value, this coal-bed gas is similar to natural gas and can be introduced directly into commercial pipelines after standard condition- ing. The high permeability cleat system in the virgin coal can be exploited in order to drain the coal gas well in advance of mining. Two premining drainage methods have been extensive- ly evaluated in the U.S.; they are 1) horizon- tal boreholes collared from within the mine, and 2) vertical drilling from the surface with fracturing. Limited-size fracture treatments are advocated in order to prevent potential roof damage and the need for added support. An engineering approach to predicting gas flow for different drainage techniques near mining locations is presented. Results can be used in design, i.e. pipeline, compressor. Coal gas drainage from a horizontal borehole and a treated (contained fracture) vertical well for a 6 foot seam have been evaluated. Based on these results, it was concluded that selection of gas drainage techniques will depend primar

Jan 1, 1982