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By R Razanatsimba, A Galli

A mining company has entered into contractual commitments to supply certain quantities of its product to clients in each time period. Failure to fulfil its obligations would damage its reputation as a reliable supplier. The planned production would normally be sufficient unless major problems such as highwall failures, roof falls, natural disaster, or strikes that interrupt production or delays in obtaining environmental permits, occur. To overcome these difficulties, the company may be able to obtain more of the commodity: from its strategic stockpile (if there is sufficient there); by buying it on the spot market; or for some commodities such as gold and uranium, by leasing it. Two sources of uncertainty, the spot price of the commodity and the occurrence of serious incidents that interrupt production, are considered. For simplicity it is assumed that the commodity price follows a geometric Brownian motion, that productions incidents have a binomial distribution, that they are independent from one time period to another and that they do not affect prices. A branching tree structure is used to model the joint evolution of prices and production incidents. The aim of this research project was to evaluate the companyÆs options for fulfilling its contractual commitments. When evaluating these options, multi-stage stochastic programming with recourse was used to solve this problem because in addition to providing the dollar value of the project, it gives decision-makers the æroadmapÆ to reach the optimal value. That is, how much material should be bought/sold on the spot market, how much to add to/subtract from the stockpile, how much to lease and in the worst case what the shortfall would be, for each time period as a function of the current spot price and breakdown status. A case-study over a five-year period is used to illustrate the proposed procedure. In this study the production would be sufficient to cover the companyÆs contractual commitments unless production incidents occur. Focus is on evaluating the impact of the quantity initially in the stockpile on the value of the project when the commodity market is tight, that is, when only small quantities can be bought on the spot market or by leasing.

Sep 26, 2011

This paper addresses, in particular, the influence of winding depth on the selection of head ropes for Koepe winders. Because this is just one aspect of winder design that affects the operational safety of the winding system, the paper starts by considering all the issues governing the life and safety of the winding ropes. Regulations from a variety of countries are reviewed and comparisons of the legislated rope factors of safety and their variation with winding depth are made. This is followed by a discussion of the typical observed mode of in-service deterioration of Koepe head ropes. This mode of deterioration is due to fatigue and is influenced by the load range occurring in the ropes. Parameters contributing to load range are discussed and the influence of winding depth is highlighted. Lessons learned from early experience with very deep Koepe winders in South Africa are recalled. Predictions of load range as a function of depth are made, from which general rope life predictions are made for ropes selected by conventional national factor of safety requirements. This is illustrated in graphs comparing rope life as a function of depth. Typically a reducing life with depth is predicted. A rope selection strategy is advocated, which is based on achieving a constant rope life irrespective of the depth of wind. A new factor of safety (or rope design factor) equation is prepared that has the trend of increasing with depth. This proposed equation is compared with other published proposals that promote an increasing rope factor of safety with depth. It is shown that smoother winder drive controls enhance winding rope life and this improvement is quantified. The paper concludes by pointing out the consistency in predicted and observed life of winding ropes selected in accordance with legislated factor of safety approaches. It recommends the adoption of a new rope design factor equation for rope selection, to be used in conjunction with appropriate codes of practice for winding rope condition assessment and for the design, installation, operation, maintenance and testing of Koepe winders. The new rope design factor equation approaches a limiting economic depth of wind at shallower depths than the existing Koepe factor of safety approaches. However these older approaches æbuild-inÆ a reducing rope life with depth. The new rope design factor is therefore a more consistent way to select Koepe ropes and to evaluate economic trade-offs between Koepe and conventional double-drum or Blair winding systems.

Jan 1, 2005

By A S. Derrington

There are several long-standing rules of thumb that are often quoted in mine ventilation studies. They include airway ‘carrying velocities’ and the critical upcast air velocity range that must be avoided to prevent a water blanket forming. Quoting these rules of thumb may lend an air of legitimacy to a ventilation design, and allow the design engineer to avoid having to study a problem from first principles. But how valid are these shortcuts in today’s rapidly changing world? This paper summarises research into the genesis of several commonly quoted rules of thumb. It finds that they were very specific to the local conditions, practices and economics at the time they were developed. It also presents examples where applying these rules of thumb outside of their original context can lead to unexpected and erroneous results.CITATION:Derrington, A S, 2017. Ventilation rules of thumb – friend or foe? Focusing on design upcast air velocities for shafts and raise bores, in Proceedings Australian Mine Vent Conference 2017, pp 253–260 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Q Zhou, H Nordberg, W Wang-Geissler

Efficiently controlling foam/froth within mineral processing continues to pose a challenge to the mining sector. The foaming characteristics of aqueous solutions for two-phase systems of air/liquid are well-studied with theories and mechanisms proposed to describe and predict foam formation and stability. The types and structures of reagents that either promote or prevent foaming/froth formation and stability are well-defined in these studies and practiced across various applications. Three-phase systems of air/liquid/solid, such as froth from mineral slurries, however, pose a challenge with the presence of a large quantity of relatively fine mineral particles. Theories and mechanisms that rationalise the effects of chemical additives as a defoamer or foaming agent in aqueous can be applied as a general rule, but do not provide the most effective solution for mineral slurry systems. Silicone-based defoamers, particularly their O/W emulsions, have been widely and successfully used at various stages of mineral processing to efficiently control the mineral slurry foaming properties. However, their foaming control ability could be significantly impacted by different processing aids used during the upstream process. In a zinc-rich mineral system, a silicone-based defoamer starts losing the properties necessary to effectively control foaming in the leaching circuit when throughput is increased. In this study, the synergistic defoaming/anti-foaming effects from surfactants and silicone-based defoamers are discussed to effectively control foaming/froth in the zinc leaching circuit, even with lower total defoamer dosage. Improvements during mineral processing can also lead to a cleaner mineral grade by reducing waste.

Aug 24, 2022

The known coal resources of South Australia are either of poor quality, or expensive to extract, or both. Export quality coal occurs only at great depth in the remote north of the State; the balance of the State's coal resources are suitable only for local electricity generation. Currently there is only one coal mine in the State, at Leigh Creek. This provides fuel for approximately 34% of the State's electricity generation, the balance being fuelled by natural gas. In the near future, new fuel sources must be developed to augment diminishing supplies of natural gas, and to cater for increasing demands for electricity. The South Australian Government has determined that future electricity generation will be based on the combustion of local coals. The geological and geographical environment of the known coal deposits and the quality of these coals are such that the most up to date and innovative technology must be applied to both extraction and combustion processes. The Government, the Electricity Trust of South Australia, and several Australian and overseas companies have embarked on an extensive research and development programme to ensure that these otherwise useless resources can be developed to the benefit of the State.

Jan 1, 1987

By D P. Blair

There are two major aspects to wall control blasting – the potential for any blasthole to cause wall damage and the potential for a delayed sequence of blastholes to cause damage. The damage potential of individual blastholes is governed by standoff distance and charge weight. However, for locations sufficiently close to a highwall, dynamic finite element models and field measurements show that there is also a critical nature to those blastholes very close to the wall, over and above standoff distance. At many mine sites, the charge weight/standoff-distance is set by trial and error. Thus, a significant aspect of the present work is the determination of dynamic stress radiating from a blasthole. Unfortunately, the modelling and measurement of this dynamic stress is still faced with many difficulties. Typical models have questionable aspects, which casts serious doubt over their predictions, and it is shown that the Hustrulid Bar experimental technique does not correctly account for stress wave attenuation in extended media. In an attempt to solve the dynamic stress problem, the present work describes a model based on an exact solution under the assumption of viscoelastic material. The model takes full account of the rock mass elastic/viscoelastic properties, the explosive type, geometry and primer location and predicts a dynamic stress for direct comparison with the unconfined compressive strength of the local rock mass. This model predicts the standoff distance required to avoid damage due to a single blasthole. The behaviour of a delayed sequence of blastholes is analysed using an upgraded waveform superposition model, covering a range of initiation delay combinations, which predicts the peak particle motion (PPM) induced in the wall for each combination. This approach shows that there is no need to fire dedicated trim shots close to walls; all that is required is a carefully modified production shot. The mechanism of vibration screening is discussed, and its use in a superposition model highlights the potential of reverse firing (shield blasting) to reduce wall PPM. A conceptual model is also introduced to give a further insight to vibration screening and damage (via ground heave). This model predicts that a centre-lift blast will have a central heave profile and that a reverse-fired shot will produce a smaller power trough than that produced by a standard shot. It is demonstrated that the mechanism of presplit formation is not well understood; nevertheless, experimental evidence shows that presplits can be an effective method for reducing wall vibrations.CITATION:Blair, D P, 2015. Wall control blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 13–26 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

The following is based on two examples of emission control with coal fired power stations as practised in Germany at Heilbronn Block 7 power station and the Rheinbraun coal combined power station with integrated high-temperature Winkler system (HTW). Heilbronn Block 7 demonstrates the successful emission control of sulphur and nitrogen oxides and the (HTW) system the reduction of the specific carbon dioxide emission. Both were sparked off by legislation which demanded certain emission control standards. Since the early eighties environment protection has been a matter of heated public debate in the European Community. A recent survey in Germany showed unemployment as being the only subject matter more frequently in the minds of people than environment protection. A new kind of forest devastation in areas away from industry has caused investigations by several government departments and private enterprise. Because of lack of conclusive evidence so far, the principle of PRECAUTION has replaced the CONCLUSIVE evidence as a base for new legislation concerning the environment. The new legislative standards for nitrogen oxide emissions in Germany for example have reduced NOx emissions of power stations from 1000 mg NOx per cubic metre of flue gas in the beginning of 1983 to 200 mg NOx per cubic metre of flue gas in April 1984. These new standards were enshrined in legislation when research provided some evidence linking nitrogen oxide emissions through photo-chemical reactions with forest devastation. Thirty European countries signed a treaty in 1983 expressing their concern about air pollution and their willingness to co-operate with each other in controlling large scale emissions.

Jan 1, 1991

By S J. Schafrik, Z Agioutantis, E C. Jong, K Luxbacher

Real-time monitoring of mine operating parameters is available at most mines. However, access to these data for an individual operation is typically underutilised by mine managers and technical personnel. Such monitoring systems are typically designed to provide data streams and alarms to a responsible person, but they are not utilised to extract underlying trends or correlate different data groups. Furthermore, multiple monitoring systems are usually implemented at a given site without interconnection between vendors’ systems or connection to any central management, and mine personnel are only exposed to a minimal subset of such data. Thus, it is not easy to analyse and correlate individual data streams and generate information to enhance day-to-day operational decision-making and improve safety and efficiency.This paper addresses the primary challenges associated with centralising data management and effecting greater utilisation of the vast amount of collected data, while at the same time reducing the time and effort required to manage such large data sets. Furthermore, it presents the conceptual design of a database application that can organise, present and analyse data collected by multiple sensors in different environments. The database is designed to operate in a passive manner so that active mine data management systems are not impacted. An example is given where this database is used for managing atmospheric data collected at an underground coalmine operation in the US. These techniques have a universal application and can be incorporated in a wide range of mining and construction projects.CITATION:Agioutantis, Z, Schafrik, S J, Jong, E C, Luxbacher, K and Karmis, M, 2015. A platform for managing and analysing atmospheric data in underground coalmines, in Proceedings Third International Future Mining Conference, pp 3–10 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By CorrOa de Araujo A, Salum MJG

The treatment of mining and metallurgical liquid effluents is becoming, everyday, a necessity felt by these industries. Physical-chemical and chemical methods for treating such effluents are generally necessary whenever heavy-metals and other toxic compounds such as cyanide are present. The present paper discusses the use of precipitate flotation as an alternative physical- chemical method that can be applied for the treatment of effluents containing heavy-metals (mainly zinc and cadmium) and cyanide. Examples of laboratorial scale applications on real effluents are given. In both cases precipitate flotation was able to reduce the concentration of toxic components of the effluents at a very high removal rate, generating a solid waste that can either be disposed, re-used or recycled. A cationic collector - dodecylamine hydrochloride - demonstrated to be the best choice of surfactant for the two systems investigated. Sodium sulphide and dithizone were selected for the precipitation of the zinc bearing effluent whereas a copper salt was preferentially used for precipitating cyanide in a form adequate for its recycling envisaging the use of an AVR (acidification - volatilisation - regeneration) technique.

Jan 1, 1993

By S Coward, J Vann, R Wolff, S Jackson, S Moayer, A Bye

Uncertainty about the future and orebody should significantly impact evaluation of mining projects. Scenario planning, widely used in other industries, for example in the petroleum industry, can provide organisations with an opportunity to explore the consequences of uncertainty on their future plans. By developing plausible scenarios, scenario planning assists decision makers by allowing them to make systematic and possibly effective decisions for the future. This paper reviews existing mine project evaluation in the context of a new framework called scenario-based project evaluation (SBPE) (Vann et al , 2012) that addresses many shortcomings of existing approaches. SBPE uses conditional simulations (CS) models as inputs which are evaluated against future alternative project pathways (æalternativesÆ). These alternatives are evaluated using multiple plausible images of the deposit (CS realisations) which capture realistic variability and as an ensemble, map uncertainty of various orebody attributes at fine scale. The alternatives can involve different mining, stockpiling, blending and processing strategies. The ultimate output is a (stochastic) set of cash flows for each alternative from which financial measures, such as NPV, can be derived. Alternatives can then be explored in the presence of against external scenarios such as changes in prices, costs, and taxation. The obvious problem with such data rich results is knowing which scenarios or group of scenarios are optimal.An innovative approach to robust stochastic optimisation (RSO) suited to the SBPE framework is presented here for the first time. This approach to RSO aims to deal with the large number of alternatives generated from SPBE. The goal of applying the RSO approach to SBPE is to identify robust strategic alternatives (project configurations) which have the flexibility to deal with variability and uncertainty of geological and processing inputs such as density, grade and process performance. By applying the proposed RSO method, it is possible to deal with uncertainty and identify the best project configuration in the face of a large number of envisaged scenarios. A case study is provided, in which we have tested the application of the proposed method and compared the result with conventional methods. An important conclusion from this research is that selecting the value of the penalty coefficients in the RSO approach proposed is (as is all optimisation) an exercise of trade-offs; a higher net present value (NPV) is generally associated with a higher risk and a lower risk is associated with a lower NPV. Indeed, this is a strong argument for considering the RSO approach outlined here over more conventional approaches.CITATION:Moayer, S, Vann, J, Coward, S, Jackson, S, Bye, A and Wolff, R, 2012. An innovative approach to robust optimisation for scenario-based mineral project evaluation, in Proceedings Project Evaluation 2012 , pp 141-148 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By K Saito, M Hasegawa

Removing sulfur and phosphorus from molten iron can be expressed by the following reactions, respectively. [S]Fe + (O2-)slag = (S2-)slag + [O]Fe [P]Fe + (3/2) (O2-)slag + (5/2) (FeO)slag = (PO43-)slag + (5/2) Fe(liquid) These equations indicate that desulfurisation and dephosphorisation have opposite oxygen potential conditions. If a small amount of desulfurisation slag not removed is carried over to dephosphorisation process, the reaction of sulfur mentioned above proceeds toward left hand resulting in increasing sulfur content in molten iron. For better understanding of such re-sulfurisation reaction in hot metal pre-treatments, the present study aimed at evaluating the effect of iron oxide on the sulfur distribution ratio between slag and hot metal. To measure sulfide capacities and FeO activities simultaneously at temperatures below the melting point of pure iron, CaO-SiO2-FeO and CaO-Al2O3-FeO ternary molten slags were brought into equilibria with copper-iron-sulfur liquid alloys, and the equilibrium oxygen partial pressures were determined with an electrochemical technique involving the stabilised zirconia solid electrolyte. The experimental results showed that the sulfide capacity increased with an increase in FeO content, and this trend was consistent with the fact that FeO was basic. Although the addition of FeO raised the FeO activity and oxygen potential, the calculated value for sulfur distribution ratio between slag and hot metal increased with increasing FeO content.

Jun 19, 2024

The Kaltails Project is situated close to the city of Kalgoorlie-Boulder in Western Australia. Located on the south-eastern fringe of the Golden Mile, Kaltails has been in operation since June 1989. The tailings forming the reserve for Kaltails have been derived from 100 years of underground mining on the Golden Mile, but, some of the re.;erve has been retreated in the past. A map of the tailings reserves and treatment plant site is presented as Figure 1. The gold project is a joint venture between Poseidon 90 per cent and Gold Corporation (ten per cent) and is managed by Poseidon Gold Kaltails.

Jan 1, 1992

Based on relative CO2, N2, and 3He contents, geothermal systems of the Taupo Volcanic Zone, TVZ, can be subdivided into two major groups: arc-type systems, associated with andesitic magmatism along the eastern boundary of the TVZ, and rift-type systems over its western parts. The highly increased N2/3He, CO2/3He and CO2/Cl ratios of the former are ascribed to entrainment of large proportions of volatiles of subducted, marine sedimentary origin. The largely rhyolitic, rift-type magmas are assumed to have formed from volatile-depleted, residual melts. Correlations of Cl and CO2 with heat contents suggest that formation of the two types of source magmas involves mixing of two end member components: a low-volatile melt with a heat/Cl ratio of 25 Ml/mol (0.7 MJ/g), and a low Cl vapor with a heat/CO2 ratio of 5 Ml/mol. On the basis of these values, the heat associated with andesitic magmas is found to be carried in close to equal parts by both vapor and melt; for the rhyolitic melts the proportion contributed from the vapor is only about 2%. The heat/He ratios of the rhyolitic source magmas for the rift-type geothermal discharges from the TVZ of 0.12¦0.05 Ml/pmol is within the range of 0.05 to 0.2 Ml/pmol of the upper mantle. The higher heat/3He ratios for the arc-related magmas of 0.4¦0.2 Ml/pmol are likely to be due to the high proportions of heat carried in the form of a separate, low 3He vapor phase derived largely from subducted sediments.

Jan 1, 1995

By J Seccatore, T Marin, M Cardu, G De Tomi, F Galvão, A Rezende, E Melo

Small-scale mining operations are characterised by a large variety of equipment availability and a high level of operational flexibility. Mine planning is usually scarce or absent in small quarries in Brazil, and mine management generally focuses on daily operations. As a result, analysis of the effects of unit operations, such as blasting, over the whole mining process is often neglected. The goal of the following project was to study the effect of production blasting on loading and hauling times, secondary breaking times and primary crushing times at the Experimental Mine of the Research Center for Responsible Mining of the University of São Paulo, Brazil. The operations analysed included blasts that performed:under the average operational standard, defined in this paper as Case 1according to quarry standards, defined in this paper as Case 2.In order to establish the effects of blasting on the downstream process, three key performance indictors were used:The time taken to load the truck, when there is the need for material selection. Due to the fact that we do not have an operational baseline, the increase in time cannot be established, meaning that we must content ourselves with comparing the mean time in each scenario.The average time used for secondary breaking machinery.The time required for the primary crusher to fully process the load of a single truck. The results obtained indicate correlations between the coarseness of the blasted material and these operational times. Solutions are suggested and evaluated for the improvement of the small-scale mining process.CITATION:Marin, T, Melo, E, Seccatore, J, Cardu, M, Galvão, F, Rezende, A, Bettencourt, J and De Tomi, G, 2015. The effect of drilling and blasting performance on fragmentation in a quarry and time for loading, secondary breakage and crushing, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 355–362 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Whilst employed by Dyno Nobel as the Technical Services Engineer û Brisbane, I was asked, as part of a contractual agreement, to look at optimising PioneerÆs blasting process to provide the most effective rock to the new crushing and screening plant. This paper details the preliminary blast designs and practices that have been in use at the quarry and the initial changes made to these designs, and the effect they have had on the excavation and crusher performance.

Jan 1, 1999

By T Baumgartl, L Zhou, D Mulligan, L Huang

The rapid production and accumulation of mineral processing wastes in the environment can present serious threats to environmental quality and human health. Phytostabilisation with native plant ecosystems is, in many cases, a preferred option for rehabilitation of mine waste storage facilities. However, much of the literature has focused on species selection in short-term experiments to test their suitability under the often extreme chemical conditions in the wastes without addressing the fundamental requirements – ie hydrogeochemical stabilisation and functional root zones. As a result, successful examples of phytostabilisation of mine wastes such as base metal tailings have been rare, especially if success is defined as meeting the completion criteria of non-polluting and sustainable land system at rehabilitated sites. Conventional capping options to isolate reactive tailings/wastes by using physical break and/or sealing layers are often not reliable in the long term (particularly under semi-arid climatic conditions) and, in many cases, they may not be feasible in the field due to the large areas to be covered and the lack of adequate suitable materials at mine sites. By using sulfidic tailings as an example, we have proposed a new paradigm for phytostabilising mine wastes – ecologically engineered pedogenesis in tailings involving accelerated physical, chemical and biological weathering of tailings minerals to achieve hydrogeochemical stabilisation and the development of soil functions, soil horizons and functional root zones.Ecologically engineering functional root zones firstly requires controlling geochemical reactivity in the wastes (ie hydrogeochemical stabilisation), which can cause polluting effects in the root zone and plant toxicity. By means of ecological engineering, in situ weathering of primary minerals (eg pyrites) in tailings may be accelerated by adding functional materials (eg functionalised biochars and organic matter) in the waste slurry during the process of deposition. This will remove or diminish key risk factors (eg potential acidity in tailings and elevated soluble heavy metals) in the solid phase, before placing growth media for reconstructing root zones and transplanting/sowing target plant species. However, much of the acidity, soluble metals/metalloids and other salts would be transported out of the solid phase into the wastewater, which can be addressed by on-site water treatment facilities during mine operation. The trajectory and state of engineered pedogenesis in the weathered tailings may be manipulated to provide specific soil horizons within future root zones that are dynamically evolved toward fully functional soil subsystem within rehabilitated plant ecosystems.CITATION:Huang, L, Baumgartl, T, Zhou, L and Mulligan, D, 2014. The new paradigm for phytostabilising mine wastes – ecologically engineered pedogenesis and functional root zones, in Proceedings Life-of-Mine 2014 , pp 663–674 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By H Wang, D Wang

Mine dust is the most serious occupation hazard in coalmines. And many coal workers suffer from pneumoconiosis because of long-term inhalation of respirable dust. Reducing the dust concentration of workplaces by effective technical means is an important way to prevent coal worker’s pneumoconiosis (CWP). In order to overcome deficiencies in existing dust control technology for underground mining, especially the disadvantage of water spray technology mounted on roadheaders or continuous miners, the authors developed an integrated dust suppression technology utilising foam for fully mechanised heading faces. This paper presents an overview of the principles, materials, equipment and application of this technology. Among these, a jet type foaming device and a green foaming agent were developed, which can realise the goal of efficient preparation of foam. In addition, an arc fan nozzle used for foam spraying was invented, which can effectively cover and enwrap the dust produced by the roadheader at the cutting point and achieve the goal of efficient utilisation of foam. This dust suppression application of the proposed foam technology was investigated on fully mechanised heading faces. The results show that the dust concentration was cut down significantly with a dust suppression efficiency of greater than 85 per cent, an increase of over 30 percentage points compared to the water spray system. This study demonstrates that this foam technology can play an important role in dust suppression on fully mechanised heading faces, which provides an important method to improve the working environment and protect coal workers’ health.CITATION:Wang, D and Wang, H, 2015. Technology of dust suppression by foam for fully mechanised heading face, in Proceedings The Australian Mine Ventilation Conference, pp 177–182 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By Bell I. F

In 1985, ZC Mines (now Pasminco South) had been unprofitable for some years due to a combination of high operating costs, low metal prices, low head grade and an aging and inadequate mining infrastructure. However, the resource of metal in the ground was still of world class, even after some 80 years of mining. A major study, which was to be of two years duration, was therefore commenced to establish a practical and profitable long term mining strategy and to cost the infrastructure options needed for its support and thus form the justification for a capital expenditure program to take the mine profitably into the 21st century and its second century of operation. This paper discusses the rationale behind the methodology adopted and the nature of the results achieved in one aspect of the study - the determination of the mineable resource and the relationship between the head grade/quantity of the economically mineable resource and the variables of cut-off grade, cost structure, annual production rate and metal prices/exchange rates. The basis of the study was the designing of some 5000 scopes to mine out the entire resource for a range of cut- off grades and the assembly of the detailed physical data thus obtained in a stope-by-stope data base for financial and other analysis. Those scopes which were shown to be economically mineable were then scheduled for two optimum annual production/cut-off grade/metal price combinations to provide life-of-mine cost and value of production cash flows.

Jan 1, 1992

The development of a robust belt sampling strategy and protocol inunderground gold mines is a fundamental requirement for effective grade quality control, ore accounting and mine-mill reconciliations. As part of the ore management system, a belt sampling system has been developed by the author, which is used to predict monthly gold grade and its error for underground/belt/mill reconciliation and grade control. This paper presents the step-by-step development of the belt samplingstrategy and sample preparation protocol at Target, an underground gold mine in South Africa. The belt sampling system at Target consists of an underground belt transporting run-of-mine material into an underground transfer point, a weightometer, a two stage crushing system, a tube splitter and a catchment device. The design allows run-of-mine ore on the belt to be sampled automatically by a go-belt sampler. GyÆs sampling theory of particulate materials forms the basicframework of the belt sampling strategy. The theory is used to quantify the optimum sample mass of broken material to be taken from the belt and to predict its reliability. It is also employed to determine the Fundamental Sampling Error (FSE), time interval between samples and particle size requirements of the final underground belt sample. Further, GyÆs sampling theory provides the means of analysing the crushing processes, splitting, segregation error, analytical variance, and the best sample preparation protocol. Although the belt sampling strategy developed in this study was forWitwaterstrand gold ore, the process is entirely general and may be very successfully used in any underground or surface mine.

Jan 1, 1999

By W R. Adamson

"Optimisation of drill and blast design and engineering can deliver a significant positive impact on the profitability of any mining operation; however, true engineering of the blasting process is less common than might be thought. The paper that follows explores this gap and suggests a process control-based approach to the challenge.The concept of applying modifications to drill and blast designs in order to achieve efficiency improvements in downstream mining processes is far from new. However, the author suggests that the practical application has become less than rigorous in a number of different sectors of the mining industry in a wide range of countries.There is a common tendency for the design process to become simplified to the point where the objective is merely the communication of instructions to field implementers (drillers, explosive suppliers, blasters, etc). In effect ‘design’ often degrades to ‘cut and paste’ with consequences that vary from mild to critical, with respect to the profitability of the business.Engineering of the drill and blast process involves the design function, not on a one-off basis but rather as a component of a more complete cyclical process that includes a statement of objectives, a design based on a suggested hypothesis, field measurement of results, comparison with the target ‘set point’ and the application of control measures followed by new measurement, including interpretation of the results in financial terms.When applied in this fashion, engineering provides practitioners with the means to optimise the drill and blast impact on the full spectrum business result of the mining activity.These concepts are discussed with reference to a surface gold mining operation applying run-of-mine heap leach extraction. Engineering optimisation by adapting process control and measurement techniques is demonstrated to be a key component of the solution set applied to generate enhanced operations productivity and stakeholder value. It is shown that a combination of rigorous measurement, model calibration and hands-on quality assurance/quality control facilitates the creation of a road map to profitability, stressing the need to consider economic trade-offs between operational expense (investment) and measurement of enhanced value (return on investment).The process, however, does not cease at this point. Implementation of true design practices, incorporating innovation and discipline in implementation or execution can drive the process to deliver demonstrable, technically validated outcomes. Furthermore, these technical results can be related to financially quantifiable impacts. However, this accomplishment does not guarantee that these gains or savings will reach the bottom line of those mining, quarrying and construction companies that begin the process with such high hopes.CITATION:Adamson, W R, 2015. Application of engineering discipline and a full-process optimisation focus – productivity to profitability without profuse pruning, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 3–12 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 24, 2015