Abstract: Decision-making in mining is a challenging task Optimal decisions regarding shovel and truck allocations, in consideration to the short-term production schedule, are very important to keep the operations inline with the planned objectives of the company in long term This paper presents a mixed integer linear goal programming (MILGP) model to optimise the operations based on four desired goals of the company: (a) maximise production, (b) minimise deviations in head grade, (c) minimise deviations in tonnage feed to the processing plants from the desired feed, and (d) minimise operating cost The model provides shovel assignments and the target productions; as an input to the dispatching system while meeting the desired goals and constraints of the mining operation The model implementation with an iron ore mine case study provided average plant utilisation above 99%, average truck utilisation above 92% and average shovel utilisation above 95%

Abstract: The authors provide their assessment of current challenges in strategic mine planning and some approaches for addressing them. Challenges covered are quantification of downstream processes and their integration into orebody models; spatial characterisation of geometallurgical variables and their integration into block models, scheduling and mine optimisation; spatial characterisation of new variables for new types of mining; flexibility in planning and design to manage risk and minimise its impact; IT infrastructure for rapid on-line data collection and processing. Most of these challenges require new types of data, variables, modelling and estimation methods. Foremost among new variable types are geometallurgical and dynamic rock mass characterisation variables. New types of data and data collection include rapid generation of very large amounts of on-line sensor data and the consequent need for rapid processing and modelling of these data. The paper includes examples of models and outputs to illustrate ...

Abstract: With decreasing profits, optimising the size of stopes to minimise dilution is a step towards achieving a productive and profitable mining operation. The stability graph was developed for the determination of stope sizes in wide orebodies to control dilution in bulk mining. Unfortunately, this graph is qualitative and stopes can only be described as stable, unstable or cave. The equivalent linear overbreak slough stability graph is quantitative but only gives average depths of failure. The graph is also only applicable to narrow vein orebodies. This paper presents a generalised quantitative dilution-based stability graph independent of orebody width. Data were collected from six underground metalliferous mines across Australia and statistically analysed using logistic regression and the Bayesian likelihood discrimination methods. The graphs provide the mining engineer the flexibility to design open stope sizes based on acceptable dilution to a given operation. More data could improve the reliabili...

Abstract: The flow of information and consequently the decision-making along the chain of mining from exploration to beneficiation typically occurs in a discontinuous fashion over long time spans. In addition, due to the uncertain nature of the knowledge about the deposit and its inherent spatial distribution of material characteristics, actual production performance in terms of produced ore grades and quantity and extraction process efficiency often deviate from expectations. Reconciliation exercises to adjust mineral resource models and planning assumptions are performed with timely lags of weeks, months or even years. With the development of modern Information and Communication Technology over the last decade, literally a flood of data about different aspects of the production process is available in a real-time manner. For example, sensor technology enables online characterisation of geochemical, mineralogical and physical material characteristics on conveyor belts or at working faces. The ability to utilise th...

Abstract: A mine landform progression plan can provide a clear outlook of the entire mining operation. To produce such an output requires detailed placement schedule of the mined material, including the volume (or tonnage) and the allocated dumping location. However, current practices mainly focus on the ore production, over-simplifying the waste material scheduling. As a result, a rock dump is often treated as a single point in long-term planning, making it difficult to predict the progression pattern over the life of mine. Without such a guidance, it is almost impossible to carry out progressively rehabilitate of the waste rock dumps. The lack of detailed waste material dumping schedule could cause delay in development construction, i.e. tailing storage facility and Run of Mine-pad. Other downstream effect due to the over-simplification is an inaccurate estimation of required truck, which could have huge financial impact on the operation. In this paper, mixed integer programming models of different objective func...

Abstract: Determination of the sampling constant is an important step when applying the Fundamental Sampling Error equation to optimise sampling protocols. The classic method for its determination is based on the heterogeneity test (HT). In coarse gold-dominated mineralisation, the HT sometimes provides an evaluation of the fine-gold background grade population heterogeneity, but understates that of the important high-grade coarse-gold component. This is because the total mass of fragments is too small to represent the full gold particle size distribution of the mineralisation. Despite this, single heterogeneity tests (SHT) are often undertaken on deposits where the presence of coarse gold is ignored, not realised or understated. Resultant sampling and assaying protocols are frequently of poor quality and do not match the mineralisation characteristics. For coarse gold-dominated mineralisation, an empirical approach for sampling constant determination is recommended via direct estimation of the liberation diameter.

Abstract: :Many types of mining machines use pointed style picks in the excavation of weak and medium strength rock ranging from coal and evaporates to shales and sandstones. This paper explores the effect of the initial onset of pick wear on changes in the cutting performance as reflected by an increase in pick tip angle at varying depths of cut using two different rock types. Rock cutting tests were performed in Gambier limestone and Gosford sandstone at depths ranging from 5 mm to 20 mm using a pointed pick having tip angles of 70°, 90° 100° and 110°. The results reveal an increase in tool angle has a more pronounced effect on normal force with a three to four-fold increase compared to less than a two-fold increase in cutting force. Forces and specific energy were also found to increase with depth of cut over the range of tip angles.

Abstract: Coupon testing has been used extensively to understand the effects of general corrosion on engineering materials within their operational environment. This study examined the use of various coupon specimens to examine stress corrosion cracking (SCC) of rockbolts in the underground mining environment. The standard ASTM G39 bend beam SCC specimen, as well as a pin-loaded slotted specimen, was used in this investigation. It was identified that the critical stress threshold for HSAC 840 rockbolt steel is approximately 580 MPa, slightly lower than the material’s yield strength. It was shown that the higher toughness HSAC 840 grade rockbolt steel performed better than AISI 1355 grade rockbolt steel, emphasising the importance of steel chemistry. It was also found that galvanising improved SCC resistance but shot peening reduced SCC resistance.

Abstract: In most surface mining, overburden removal operations require haulage over short distances. This is a key operation for companies using the strip mining method, because of the large amounts of waste to be removed. Other methods and operations also adopt this type of transport, using dozers, excavators, front-end loaders and haul trucks. A comparison of different haulage options for short distances with respect to energy efficiency in open-pit mining is needed, but only a limited number of recent studies have considered energy efficiency as a key variable in mining projects. This study therefore seeks to develop a mine design that is able to achieve greater energy efficiency without affecting the performance of mining operations. For this purpose, simulation tools and comparative analysis among several equipment options are used. After implementation, a 14% reduction in specific fuel consumption and a 16% increase in productivity are found.

Abstract: Perfluoromethylcyclohexane (PMCH) was released in a Midwestern underground longwall mine in the United States using a PMCH permeation plug release vessel (PPRV). The operators of this mine graciously allowed full access to an active longwall panel at two points in time to perform the test. This paper presents a study designed to determine the feasibility of using a PPRV in an underground mine environment for tracer gas studies. The results of this study showed that the PPRV is a feasible tracer delivery system for releasing PMCH at mine scale. Some of the advantages afforded by the PPRV over traditional release techniques are also highlighted.

Abstract: This paper discusses the strategic mine planning process at Newmont’s Twin Creeks Operation. A multi-period Mixed Integer Liner Programming (MILP) model is utilised to optimise a large scale, complex operation with multiple open pits and underground mine sources under tight process blending constraints with the option to stockpile. In addition to life-of-mine production scheduling optimisation using MILP, the strategic planning process includes cost analysis, phase design validations and sensitivity to constraints such as mining rates, mill blending or throughput. Through this planning approach, Twin Creeks Operation is realising significant value from cost reductions and higher near term free cash flow resulting in increases to life-of-mine net present value.

Abstract: Consolidated backfill mining technology has been widely popularised in China. However, the complicated backfilling and mining processes as well as low productivity of the backfilling and mining workface has made it more difficult for collieries to survive during the downturn of coal industry. In this condition, this paper introduces an innovative mining method based on consolidated backfill mining technology, namely, mixed mining technology involving solid backfilling and caving methods, and presents its underlying technical principles. In addition, the paper describes the controlling mechanism of strata movement and its three main systems: underground separation system for coal and gangue, underground crushing system for gangue, and fully mechanised mixed system involving mining and backfilling. An engineering application of this method at the Pingdingshan No. 12 colliery shows that during a 2-month period in the Ji15-31010 workface, 142 thousand metric tons of coal resources were extracted, with 73 thou...

Abstract: This paper investigates readily incorporable improvements to the identification of squeezing ground conditions and the determination of the depth of movement for Mount Isa Copper Operations’ Northern 3500 (MICO N3500) orebody. Numerical modelling using the boundary element method (BEM) indicated that the current use of elastic material properties to calculate the rockwall condition factor and predict tunnel squeezing is appropriate, as no apparent benefit was gained by employing elastoplastic material properties or including the tunnel void geometry. Further analysis using the finite element method indicated that complex, large-scale models would be required to make meaningful improvement on the elastic BEM model. However, due to large time and computational overheads such models are not practical within the site’s engineering workflow. In conjunction with numerical modelling, a prototype monitoring device was also developed to address the problem of rigid instrument shear and inspection camera obstructio...

Abstract: When designing large-scale blasting operations, great consideration should be given to tailor the fragment size distribution in order to fulfil production requirements, while ensuring at the same time efficient and economical downstream operations such as loading, hauling, crushing and grinding. The selection of an optimum inter-hole delay time has been found to have beneficial effects in controlling fragmentation and face movement. The minimum response time Tmin is reported in the literature as a key parameter for the selection of the appropriate inter-hole delay time. In this paper, data collected from 10 monitored full-scale blasts are used to investigate bivariate correlations between various design parameters. Further processing of the data using dimensional analysis resulted in the derivation of a mathematical relation that can estimate Tmin as a function of blast design parameters and the desired size reduction ratio of blasting.

Abstract: The Centinela sulphide mine (formerly known as Esperanza Mine) is an open pit sulphide deposit located in Chile's Antofagasta Region, 1350 km North of Santiago. One of the strategic objectives of the mine is to implement productivity improvement projects that can be monitored, adequately quantified and adhere to strict geotechnical requirements. This paper describes the implementation of leading practices to evaluate geotechnical and blasting performance. An approach based on direct measurements was developed and implemented at the mine site. The process involved measurements of near-field accelerations and gas penetration behind pre-split-lines; run of mine (ROM) fragmentation analysis and geotechnical evaluations based on the reconciliation of key geotechnical design parameters, such as bench face angle, berm width, inter-ramp angles and final slope characteristics. A geotechnical evaluation matrix was introduced to rank final results at each monitored location. From a geotechnical perspective, the best...

Abstract: The third international symposium on Orebody Modelling and Strategic Mine Planning was held in Perth, Australia 24–26 November 2014. It followed the previous highly successful symposia in 2004 and ...

Abstract: This paper presents results on detecting large rock fragments in rock piles using ground penetrating radar (GPR). The authors are researching sensors to augment the image provided to the remote operator, assisting with detection of oversized fragments beneath the surface. The attenuation of the GPR signal was calculated over the band 0–3 GHz from the signal energy in the frequency domain. The results show that attenuation measurement allowed the samples which included a large fragment to be differentiated from samples only containing smaller rock fragments. By combining velocity analysis with attenuation the rock samples can be further differentiated from samples containing air pockets or irregular surfaces. The combination of attenuation and signal velocity allowed prediction rates to detect the presence of large rock fragments over 93% correctly in laboratory testing.

Abstract: Strategic planning at BHP Billiton Western Australia Iron Ore (WAIO) aims at sustainable value maximisation of its large, long-life, low-cost, expandable mineral inventory and supply chain infrastructure. This requires a whole of business approach and optimisation of the full value chain, beyond mine plans alone. Only through a system view can the value proposition of a set of plans be truly optimised. Fundamental system components include: mineral inventory information with intrinsic uncertainty; full supply chain optimisation utilising throughput accounting; a marketing view of future quality premiums based on overall market quality load; alternative sequences of capital decisions; and closure costs including optimisation of total material movement. An annual, structured Life of Asset planning process optimises maximum value through a nondeterministic scenario-based optimisation approach, while also identifying the activities that will resolve key uncertainties and steadily improve confidence in...

Abstract: Pre-split techniques are routinely used to minimise rock mass damage from production blasting. Design parameters rely on site-specific guidelines and in order to improve designs, it is important to be able to measure its performance. One criterion is related to the pre-split ability to adequately filter blast-induced stresses and explosion gases. This paper presents the results of a monitoring program implemented to evaluate the performance of pre-split practices. Triaxial accelerometers and pressure sensors were installed behind pre-split lines and a site-specific criterion was established to determine whether or not filtering effects were occurring. The recorded maximum peak particle velocity (PPV) vector sum behind pre-splits in all blasts monitored was below the threshold of damage of intact rock and rock mass discontinuities. With regards to the recorded gas pressure, measurements from production blasts showed fluctuations of low pressure levels, indicating that pre-split parameters were effectively ...

Abstract: The mining industry routinely collects samples to assist with decision making, whether for exploration, resource estimation, grade control, or plant design and balances. Poorly designed sampling protocols can result in elevated project risk by increasing variability. Critically, such variability produces both financial and intangible losses. Sample collection, preparation and assay or test work protocols that are optimised to suit the ore type, together with QAQC systems will reduce variability. Many gold deposits display a high natural variability, where the in situ variability can be enhanced by poor sampling practice to yield a high-nugget effect. In this case, specialised protocols are often required. Reporting codes require the Competent Person to consider the quality and implication of sampling programmes. Despite its importance, sampling often does not receive the attention it deserves. In this paper, the importance of good sampling practice is exemplified through a series of case studies, which sh...

Abstract: Fully mechanized solid backfilling mining (FMSBM) is a mining technology that combines strata movement control and solid waste disposal. This technology can effectively reduce the damage to surface...

Abstract: In the future a larger proportion of underground mines will operate in deep, high stress environments where excavations may be exposed to very high loading demands. This case study has examined a violent structurally controlled failure occurring in a deep hardrock underground mine at a depth of 1055 metres below surface. On the basis of the damage observations the back analysis of this event concludes that the surface support system was ejected from the wall of the excavation with an initial velocity of 10.7 m s−1. Estimates of the mechanical demand imparted to the ground support scheme during failure were also calculated. These estimates carry several assumptions in order to simplify complex uncertainties concerning the loading mass of rock and transfer of kinetic energy between the rock and ground support. However, the demand may be conservatively assumed to be at least 150 kJ m−2. These results may reflect future mining conditions at great depth.

Abstract: A mining complex may be comprised of multiple components, including open-pit and underground operations. Traditional approaches in mine planning do not account for the various components simultaneously leading to under-value solutions. Over the last decade, some methods have been developed to incorporate multiple components of the mining value chain during optimisation. Even though these new methods incorporate more decisions and flexibility to the optimisation of a mining complex, they may either ignore uncertainties associated with the mining project or consider decisions taken before optimisation. This paper presents a method that optimises mining complexes comprised of multiple open-pits, underground operations and processing destinations. Mining, blending, processing and transportation decision variables are simultaneously optimised while accounting for geological uncertainty. The method uses a simulated annealing algorithm at different decision levels in order to generate a stochastic-based extracti...

Abstract: This paper proposes a new multi-resource multi-stage mine production timetabling problem for optimising the open-pit drilling, blasting and excavating operations under equipment capacity constraints. The flow process is analysed based on the real-life data from an Australian iron ore mine site. The objective of the model is to maximise the throughput and minimise the total idle times of equipment at each stage. The following comprehensive mining attributes and constraints are considered: types of equipment; operating capacities of equipment; ready times of equipment; speeds of equipment; block-sequence-dependent movement times; equipment-assignment-dependent operational times; etc. The model also provides the availability and usage of equipment units at multiple operational stages such as drilling, blasting and excavating stages. The problem is formulated by mixed integer programming and solved by ILOG-CPLEX optimiser. The proposed model is validated with extensive computational experiments to improve min...