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By A. E. Lewis

The emphasis of this paper is on the characterization and testing of the slag produced by a secondary lead refinery. This work forms part of a broader investigation aimed at reducing loss of valuable product from the process as well as minimizing the environmental impact of the process wastes. It was this work that led to a critical examination of the standard waste classification tests. Characterization of the slag was carried out using a number of complementary techniques. In the broader context, the slag characterization aided in identifying process deficiencies and thus was a critical tool in suggesting potential for process optimization. For this study, the slag characterization provided a relatively comprehensive picture of the composition and properties of the slag, which facilitated understanding the behaviour of the slag under batch test conditions. On the basis of quantity of hazardous components alone, the slag is hazardous according to South African Acceptable Risk Limits (ARL). However, when both the quantity and the leach potential of the hazardous components is taken into account, standard waste tests carried out by three independent agencies indicate that the slag should not be classified as hazardous according to local regulations. Also, according to United States Environmental Protection Agency (US EPA) limits, which are independent of the quantity of the waste, the slag would not be classified as hazardous. The standard waste tests used by the independent agencies was the Toxicity Characteristic Leach Procedure (TCLP), a test which was developed by the US EPA to classify hazardous wastes. One of the requirements of this batch test is that it should be quick, simple to carry out and that the results should be reproducible. Previously, the applicability of the TCLP test to mineral processing and metallurgical wastes has been challenged on a number of points. Additional testing of the slag was carried out using both the TCLP and the Synthetic Precipitation Leach Procedure (SPLP) recommended by the American National Mining Association as being more appropriate for mineral processing wastes. The particular physical and chemical characteristics of the secondary lead slag highlighted additional limitations of both the TCLP and SPLP tests as standard laboratory batch procedures. Keywords: environmental protection, secondary lead processing, slag, leach testing, TCLP, SPLP, ARL, hazardous waste, batch tests

Jan 1, 2000

By G. V. R. Landman

It is self-evident that economic pressure demands that today?s mines stay ahead and stay competitive. The challenge, however, isto find fresh approaches to the pursuit of efficiency and operational effectiveness. Rather than focusing on individual activities in isolation, a process that can lead to poor investment decisions affecting other critical areas of operation, a key concept is optimization of the whole value-adding process of mining. This concept is often called ?mine to mill?. Whereas it is never easy to establish optimal conditions across a whole mining operation, the quality and consistency of the blasted rock strongly affects all operations. In many instances an inability to control rock breaking has been unchallenged, leading to significant investment in time and money to manage the consequences of poor and/or inconsistent rock breaking. This paper discusses how electronic initiation systems can play a major role in optimizing the whole mining operation. Electronically programmed detonators provide not only the ability to tightly control a key parameter, namely timing, but also the opportunity to extract blast data for a continuous improvement process. The ability to alter predictably, using feedback from the downstream processes, blasting variables such as fragmentation, throw, wall stability, and vibration, is a huge advantage. The current understanding of the effect of timing, accuracy, and scatter on rock fragmentation is reviewed and offers reasons why there is significant progress in controlling blast results. Two case studies are examined, which demonstrate the benefits of the technology on the economics of the operations under review.

Jan 1, 2010

By Vinay Kumar Agrawal, Rama Nath Praharaj

IMFA Group is the largest producer of Charge chrome not only in India but also in Asia. This Group has plants situated at Therubali and at Choudwar. They also have a Thermal power plant at Choudwar which not only caters to the power requirement of Choudwar plant but also supplies power to Therubali. The plants are fed for Chromite ore through the captive mines namely Nuasahi Chromite mines (40.47 Ha) , Bangur Chromite mines(37.34Ha), Sukinda chromite mines (116.76 Ha), Mahagiri Chromite Mine(73.777 Ha) and Chingudipal Chromite mines (26.62 Ha). Nuasahi Chromite Mine, which is situated in Keonjhar district, is an underground mine and is based upon best technological advancements in the industry. The underground mining operation is certified under ISO-9002, ISO-14001and OHSAS 18001. This not only shows the concern for the quality, environment but also for the health of the employees. The Nuashahi is the first chromite mine to backfill the opencast excavations created during the last 50 years and carry out the production from underground area below the opencast workings. This paper deals with the state of art technology of sub-level open stopping in thin ore bodies. The under-ground mine openings was started in the year 1997. In next four years the production of chromite from underground was started.(2001). At present the mine is in a good shape with several running stopes. Today it is producing around 10,000 Mt per month of chromite. The development of the mine is carried out with an average of 200 mtr per month of tunneling. The mine is having a mechanical ventilator having a capacity of24000 M3 per hour at 50mm water gauge, thus feeding sufficient air for the persons working in underground. The mine is being dewatered through a most modern positive suction sump, having a capacity of 500 cum and operated with 120 HP pumps. After commissioning of this sump in the year 2003, the mine has taken a quantum jump in production with remarkable saving in power consumption.

Jan 1, 2007

By B. G. Tarasov

This paper proposes the further development of a recently identified shear rupture mechanism (fan mechanism) that elucidates a paradoxical feature of hard rocks ? the possibility of shear rupture propagation through a highly confined intact rock mass at shear stresses that can be significantly less than frictional strength. In the fan mechanism, failure is associated with consecutive creation of small slabs (known as ?domino blocks?) from the intact rock in the rupture tip, driven by a fan-shaped domino structure representing the rupture head. The fan head combines such unique features as extremely low shear resistance, self-sustaining stress intensification, and self-unbalancing conditions. Consequently, the failure process caused by the mechanism is inevitably spontaneous and violent. Physical and mathematical models explain unique and paradoxical features of the mechanism, which can be generated in primary ruptures and segmented faults. The fan mechanism provides a novel point of view for understanding the nature of spontaneous failure processes, including shear rupture rockbursts. The process explains, in particular, features of shear rupture rockbursts such as activation at great depths, generation of new shear ruptures in intact rock mass, nucleation of hypocentres at significant distances from the excavation, shear rupture development at low shear stresses, and abnormal rupture violence.

Jan 1, 2014

By M. Paricheh, M. Rahmanpour

"The cost efficiency and high reliability of semi-mobile or combined in-pit crushing-conveying (IPCC) and truck systems, compared to conventional truck-shovel systems alone, make them more attractive for use in modern mining operations. Semi-mobile systems, which are the most common systems in open-pit mining, combine the advantages of both systems such that fewer trucks are required, operating costs are lowered, and the operation is environmentally sound. One major aspect of utilizing this system is determining the location of the in-pit crusher and the timing of relocations. Facility location models are rarely used in the mining sector, but these models may be used for solving the in-pit crusher location problem. To this end, the main parameters affecting the IPCC location in open pit mines are reviewed and examples given of how they are applied to a dynamic location-relocation problem. Subsequently, the model is implemented for Sungun copper mine in Iran and the number and the exact time of relocations of the IPCC units determined. IntroductionNowadays, compared to the last century, metal prices are more volatile, average and cut-off grades have decreased, and stripping ratios increased. From a mining engineering point of view, many ore deposits with simple access and low capital and operating costs have been exhausted. The remaining deposits are located at depth, with no easy access, which requires high initial capital costs (Osanloo, 2012). Mining at great depths and high tonnages is possible only through open pit mining. Today, more than 80% of open pit mines in the world use a shovel-truck system for loading-hauling operations (Osanloo, 2010).With increasing depth, haulage distances increase and the number of loads per truck decreases. As a result, fuel, tyre, and depreciation costs per ton increase. Owing to these factors, open pit mining at great depth (300 to 1000 m) using shovel-truck systems faces some technical and economic problems. In-pit crushing-conveying (IPCC) systems have been known in the mining industry for many decades. The idea was introduced in 1956 in Germany. Today, the cost efficiency and high reliability of IPCC make it more appealing than conventional shovel-truck operation, especially in longer life projects with lengthy transportation distances and high production rates (Koehler, 2003). Since 1956, different aspects of this system have been reviewed by many researchers. Barua and Lanergan (1985) developed a computer program that compares the tonnage aspects of various conveyor layouts. They believed that to maximize the economic benefit of lower haulage costs associated with in-pit conveying, one must first minimize the cost of the flatter slope, which is expressed in terms of additional stripping or tied-up ore. Dos Santos and Stanisic (1987) evaluated the design of a high-angle conveyor at the Majdanpek copper mine. Then, Sturgul (1987) applied GPSS (general purpose simulation system) to find the best location of an in-pit crusher."

Jan 1, 2017

By A. K. Anyimadu

Ongoing development work on ultra-fine grinding for various applications at the Group?s concentrators has been conducted by Anglo Platinum over the last few years. Current potential applications for mainstream grinding and concentrate grinding are the subject of a group-wide research and development programme. The first 10 000-litre 2.6 MW IsaMill was jointly developed by Anglo Platinum, Xstrata Technology and Netszch for installation at the Western Limb Tailings Re-treatment project in Rustenburg, South Africa. The unit was commissioned in late 2003/early 2004,and has operated in an intermediate concentrate regrind application successfully since. This paper describes the operational performance to date, as compared with the original duty specifications and objectives. The first mainstream M10 000 IsaMill with a 3 MW drive will be operational in November 2006 at the Potgietersrus Platinum (PPL) ?Platreef? Sandsloot Concentrator in South Africa?s Limpopo Province. Keywords: Western Limb Tailings Re-treatment Plant, IsaMilling, Platreef, platinum, palladium, PGMs, tailings.

Jan 1, 2007

By K. S. Rao, R. P. Tiwari, V. K. Shrivastava

ABSRACT: In this paper numerical simulation of jointed block mass behaviour obtained in an experimental study has been presented. Singh et al. (2002) conducted extensive tests on the jointed model materials with several joint configurations. The results of this experimental study were used to validate the strength behaviour of numerical block mass model developed using professionally available software. This software basically contains different kinds of material models. From the results of numerical simulation the existence of strength anisotropy was observed. The strength anisotropy so obtained has been compared with the experimental values reported by Singh et al. (2002). The anisotropic curves in both cases are U-shaped with flat base. They show good agreement in sliding mode of failure zone in which inclination ß (= 90° - ?) of joint set-I lie between 20° to 40° for all cases of interlocking. ZUSAMMENFASSUNG: In dieser numerischen Papiersimulation des verbundenen Blockmasse Verhaltens, das in einer experimentellen Studie erhalten wird, ist dargestellt worden. Singh et al. (2002) leiteten umfangreiche Tests auf den verbundenen vorbildlichen Materialien mit einigen gemeinsamen Konfigurationen. Die Resultate dieser experimentellen Studie wurden verwendet, um das Stärke Verhalten des numerischen Blockmasse Modells zu validieren, das mit professionell vorhandener Software entwickelt wurde. Diese Software enthält im Allgemeinen unterschiedliche Arten der materiellen Modelle. Von den Resultaten der numerischen Simulation wurde das Bestehen von Stärke Anisotrophie beobachtet. Die Stärke Anisotrophie also erreicht ist mit den experimentellen Werten verglichen worden, die von Singh et al. (2002) berichtet werden. Die anisotropen Kurven in beiden Fällen sind mit flacher Unterseite u-förmig. Sie zeigen gute Vereinbarung in gleitender Erscheinungsform des Ausfalls Zone, in der Neigung ß (= 90° - ?) von der Verbindung stellenSie Lüge zwischen 20° auf 40° für alle Fälle vom Ineinandergreifen ein. RESUME: Dans cette simulation numérique de papier du comportement joint de la masse de bloc obtenu en étude expérimentale a été présenté. Singh et autres (2002) ont effectué les essais étendus sur les matériaux modèles joints avec plusieurs configurations communes. Les résultats de cette étude expérimentale ont été employés pour valider le comportement de résistance du modèle numérique de la masse de bloc développé en utilisant le logiciel professionnellement disponible. Ce logiciel contient fondamentalement différents genres de modèles matériels. Des résultats de la simulation numérique on a observé l'existence de l'anisotropie de force. L'anisotropie de force ainsi obtenu a été comparée aux valeurs expérimentales rapportées par Singh et autres (2002). Les courbes anisotropes dans les deux cas sont en U avec la base plate. Elles montrent la bonne concordance dans le mode coulissant de la zone d'échec en lequel la inclination ß (= 90° - ?) du joint placez-Je le mensonge entre 20° à 40° pour tous les cas d'enclencher.

Jan 1, 2003

By J. C. Ion, O. Isaksson, J. Stjernberg

Iron ore pellets are a preferred feedstock for ironmaking. One method used for pelletizing is the grate-kiln process, first established in 1960.During the past decade, the establishment of new grate-kiln plants has increased rapidly, especially in China, and new constructors of pellet plants have started to operate in the market. It is well known that the grate-kiln method yields a superior and more consistent pellet quality compared with the straight-grate process. However, certain issues exist with the grate-kiln plant, which are discussed here, together with proposed practical solutions.

Jan 1, 2015

By A. K. Anyimadu

Ongoing development work on ultra-fine grinding for various applications at the Group?s concentrators has been conducted by Anglo Platinum over the last few years. Current potential applications for mainstream grinding and concentrate grinding are the subject of a group-wide research and development programme. The first 10 000-litre 2.6 MW IsaMill was jointly developed by Anglo Platinum, Xstrata Technology and Netszch for installation at the Western Limb Tailings Re-treatment project in Rustenburg, South Africa. The unit was commissioned in late 2003/early 2004, and has operated in an intermediate concentrate regrind application successfully since. This paper describes the operational performance to date, as compared with the original duty specifications and objectives. The first mainstream M10 000 IsaMill with a 3 MW drive will be operational in November 2006 at the Potgietersrus Platinum (PPL)?Platreef? Sandsloot Concentrator in South Africa?s Limpopo Province. Keywords: Western Limb Tailings Re-treatment Plant, IsaMilling, Platreef, platinum, palladium, PGMs, tailings.

Jan 1, 2007

By S. M. Spottiswoode

Much as one hopes to predict whether damaging seismicity might occur somewhere in the next shift, this is not possible at present. Recently, an analysis of seismicity at two mines has shown that a small increase in seismicity occasionally occurs before both large and small events. This analysis is extended here to five mines, with the same results. Earthquake seismologists forecast hazard in terms of the average incidence of earthquakes over the last 50 years, adjusted on an hourly basis according to the possibility of aftershocks of events that have happened. The rate of seismicity in any area remains approximately constant when expressed as seismicity per area mined, or better still, per unit of elastic strain energy released. It is suggested that seismic hazard in mines be estimated using historical seismicity and forward modelling, adjusted according to the possibility of aftershocks. In summary, medium-term forecasting of seismicity is viable; short-term prediction of large events is not.

Jan 1, 2010

By S. Khan, M. Auret

Due to the modernisation of mines, traditional training methods may be supplemented to support the upskilling of supervisors in mines. A project was initiated by the SAMERDI SATCAP programme to demonstrate the “art of possibility” through a modern training methodology. Two exemplar digital supervisory leadership development modules for underground gold and platinum-group metal conventional and modernising mines, were developed for potential uptake by the mining industry. These exemplar modules were exhibited on a digital platform, towards leading and driving mining modernisation. The research adopted a mixed method approach that included a literature review, a review of an existing supervisory leadership development programme, data gathering, a pilot study, and stakeholder validation workshops. The research supported the development of exemplar digitised modules. The two digitised modules were showcased to the industry for potential adoption. Training slides, a facilitator guide, and a training video were developed for ease of use by industry. The training modules are generic and not specific to a particular mine. They may be used by multi-commodity mines, including gold and platinum-group metals, as ‘stand-alone’ modules. They are customisable, through consultation with relevant service providers for specific working environments. The findings indicated that both the traditional classroom training and the new digitised online learning solution offer advantages for supervisory leadership development. Digital learning is not a new concept for supervisors at mines and modern training methods are well-supported by supervisors in the industry. A ‘modernised’ training solution may consider a ‘blended’ learning approach that combines traditional training with digital methods.

Jun 27, 2025

By T. Y. Yunsel

Estimation techniques such as polygonal, triangular prism, trapezoid, isopach maps, and inverse distance methods are often used in ore or industrial minerals deposit evaluation. These techniques do not express the variability of the deposit and do not allow a determination of the reliability of the estimates. However, geostatistical methods can express a measure of the error associated with the estimates, by finding weighting coefficients for a given mining block, and can also help with data configuration that minimizes the error. This work addresses an application study on the quality and reserve characteristics of the cement raw materials of the Adana Cement Factory in Adana, Turkey, based on the spatial distribution and variability of the chemical components (Si02, CaO, A1203, Fe203). The study has been carried out using a geostatistical procedure that is useful for site assessment, characterization, and monitoring situations where data are collected spatially. Directional and omnidirectional experimental variograms of the cement raw material variables showed that neither strong geometric nor severe zonal anisotropy exists in the data. The most evident spatial dependence structure expressing the continuity for omnidirectional experimental variograms were characterized by exponential and spherical variogram models. These models have been used in cross¬-validation analysis, which proved that these models, their parameters, and kriging parameters are applicable for the study area. Quality contour maps of the deposits at given levels underground were estimated using a kriging interpolation technique. Anomalies such as bullseyes and drift were not observed in the maps that were generated. Kriged maps showed the spatial distribution of quality continuity and variability of the deposits. Grade-tonnage curves and total tonnage estimates in the particular grade were determined using ordinary kriging in order to improve the mining operation and planning. Consequently, local uncertainty and the probability of extreme values occurring are tools of prime importance for the mine planning, the optimum mix of raw materials coming from different quarry stopes.

Jan 1, 2012

By K. Richardson

Although the De Beers group has a long history of placer mining on land, the group only became actively involved in deep water marine diamond exploration and mining in 1983 with the formation of DeBeers Marine. Full-scale commercial mining commenced around1991. Since then, the group marine mining capability has grown into a formidable fleet of 8 large deep water (>70 m) mining vessels, as well as other special purpose geosurvey platforms. Marine diamond production by the group is expected to be just short of 1 million carats in 2006. De Beers operates across the entire value-chain spectrum from geology and geosurvey, through sampling to mining, and finally ore processing into high value concentrate. Supporting these operations involves significant service activities such as maintenance, security, logistics and environmental management. Specific challenges exist in terms of developing or acquiring appropriate technology for marine mining. These challenges have resulted in De Beers operating extensive in-house R&D and projects departments, as well as drawing extensively from technology partners. An array of computational and test facilities is also available to support R&D and projects activities. Hydrotransport in various guises is key to the current approaches to marine mining and ore processing. Use is made of airlift and centrifugal pumping for hydraulic hoisting of very coarse gravel, while splitters, launders, dewatering, elutriators, jet pumps, centrifugal pumps, dense medium circuits, pipeline systems, and instrumentation for coarse abrasive particles are used extensively in the ore processing plant.

Jan 1, 2007

By Rajendra Singh

Underground depillaring of contiguous coal seams/sections is a difficult problem, which becomes even more complex if the interburden/parting between them is thin. Conventionally, the depillaring with caving of contiguous seams/sections is done in descending order. However, if the parting is thin, the influence of the top sections/seams working over the standing pillars of bottom the sections/seams becomes extremely important for the safety and optimal exploitation of coal. Field investigations were carried out at Nowrozabad East mine where superimposed pillars of the Johilla top section were depillared above the developed pillars of the Johilla bottom section with a 3 m thick parting between the two sections. The competency of the 3 m thick parting (which consists of alternate layers of shale, sandstone and shaly sandstone) was improved by reinforcement (underpinning). The strata control investigations did not show any considerable instability problem of the 3 m thick reinforced parting and pillars of the bottom section due to top section depillaring. On the basis of this field investigation and a laboratory study on simulated models, simultaneous extraction of both the sections, along with reinforcement of the parting, was suggested for the geomining conditions of the Johilla top and bottom sections. Adopting the suggested simultaneous depillaring process, two sub panels of Johilla top and bottom sections have successfully been extracted without any strata control problem. This paper presents this case study along with the results of the strata monitoring conducted to evaluate performance of the underground structures during the field trial.

Jan 1, 2004

By C. Sawmliana

Deep-hole blasting operations in opencast mines are always associated with some annoyance to the surrounding areas in terms of ground vibration, noise, flyrock, etc. These become more severe when underground mines run parallel to them. Blasting in opencast mines may pose danger to the underground mines in terms of roof/side failures, damage of water dams, isolation/ventilation stoppings and other underground installations. The paper discusses a case study in India on the impact of deep-hole blasting in Ramagundam Opencast Project ? III on the stability of various water dams of GDK-6B Incline coal mine operating in close proximity. The stability of underground water dams of GDK-6B Incline mine was endangered due to deep-hole blasting at OCP-III. There were 15 water dams in seam 3 and 16 dams in seam 4 of the underground mine. The physical strength tests using a Schmidt Hammer instrument were carried out in all the 15 water dams of No. 3 seam and 16 water dams of No. 4 seam. The test revealed that there is a decrease in compressive strength values of three dams of seam 3, namely 6A, 6B and 7. Theose three dams were also directly connected to the water source. Water seepage was also observed from the surfaces of the three dams. However, they were found to be stable in accordance with their design parameters and damage point of view while considering a threshold value of ground vibration as 25 mm/s. It was found that the value of tensile stress generated by a vibration of 25 mm/s was much lower (i.e. 0.171N/mm2) than the tensile strength of the two weakest concrete dams (1.85 N/mm2). Ten experimental blasts were conducted at different working benches of the opencast mine and the ground vibration data were recorded in roof and pillars near various underground water dams. The maximum value of vibration data recorded was 5.9 mm/s in roof near dam no. 1 in seam 3 with the dominant peak frequency of 22 Hz. No adverse effect on either of the dams was observed after that blast. During the period of study, no deterioration/adverse impact was found in any dam of the mine. Based on the results of the study and the analyses of the data, optimized blast design parameters and explosives weight per delay were suggested for the opencast mine to maintain the safety of the underground water dams. Keywords: Opencast blasting, damage, water dams, underground mine, ground vibration

Jan 1, 2009

By A. Bothma

The Impala No. 1A ventilation shaft is located approximately 15 kms north of Rustenburg and is accessed via the R510road from Rustenburg to Northam/Thabazimbi. This situation is shown on the location plan in Figure 1. The geology at the site consists of an upper layer of black turf of about 1 metre in thickness, grading into weathered norite. The depth of weathering is generally less than 5 metres. Zones of deeper weathering may occur along fracture zones associated with faults and dykes. Groundwater occurs mainly within the weathered/fractured aquifer system. The ventilation shaft is a 5.1 m diameter upcast shaft ,and forms part of a system of ventilation shafts to complement the existing infrastructure as mining progresses down the new twin decline extension of Impala 1 shaft. The principal reason for these shafts is to lessen the risk of an extended RAW and also to counter the effects of the heat build-up as the mining goes deeper, with the resultant effect that the existing cooling centre (fridge plant) becomes more remote from activities. The No. 1A shaft (upcast) is positioned approximately 1,2 km on down dip from the main shaft and the No. 1Bshaft (downcast) approximately 1,2 km further. Geological information was used from a borehole 1,2 km away on strike from the upcast shaft. The first shaft (1A) is a 5,1 m diameter hole to be fitted with two 2,2 MW fans, whilst the second shaft (1B) is 4,1 m diameter to accommodate a 7MW fridge plant.

Jan 1, 2001

By H. E. Bartlett

In the operation of some flotation plants treating platinum ores it was found that there were imbalances between the inputs and outputs. The inputs and outputs were sampled as slurries and it was determined that the imbalances arose from biases in the sampling, despite the samplers having been designed according to well-established rules. The launders feeding the sample cutters, and the sample cutters themselves were redesigned using finite element analysis to model the flows. A new set of design rules were formulated. The application of a Components of Variance Analysis, to determine the variance of primary and secondary sampling and of analysis in the lab for a concentrate is presented to illustrate the need for frequent sampling of process streams.

Jan 1, 2002

The simple act of taking a sample implies that someone will use the information contained in the analytical result to make a decision about a course of action. In the mining industry, the decisions may involve huge capital commitments for opening or closing a mine, or marginal tactical costs that involve deciding if a truckload of mineralized rock should be sent to the mill for processing, or the waste dump. Sampling is among the most fundamental activities in a mining operation, and this paper aims to examine some of the technical issues that can assist in ensuring that samples are representative and correct. Insights into the scale of variability require that we disaggregate sampling variance into its component parts and evaluate each one individually. The work of Pierre Gy in understanding the different sampling errors is the first step in establishing an optimal protocol. This must be followed by the appropriate measures to ensure the protocol is implemented such that minimal bias is introduced in the sampling process. Even with these insights the possibility exists for large unseen and hidden costs can accumulate in a mineral development because of sampling errors. These hidden costs arise due to misunderstanding of the principle factors that affect the size of sampling errors, such as the mass of the sample, the effects of splitting a sample to reduce the mass, and the influence of the nominal particle size. The handling of sample material without due regard to the sampling characteristics of the material being sampled is also a major source of sampling errors. The most significant problem is due to the influence of the so-called volume-variance effect. This effect is a consequence of the support effect and the information effect both of which relate to the difference in size at which samples are collected and mining blocks are extracted. The information effect is a function of the availability of data at the time that decisions are made about the destinations of mineralized rock, namely the mill or the waste dump. Implementation of appropriate sampling protocols in the mineral value chain remains a challenge throughout the industry. The growing understanding and deepening appreciation of sampling theory and methods means we stand on the threshold of a new era for implementing and understanding appropriate sampling procedures and protocols. In the interests of optimal development of the national patrimony it is suggested that standardization through the identification of structural problems and continuous improvement of mining processes be instituted at a national level.

Jan 1, 2007

By N. Reddy

The influence of local geology and rock mass characteristics on deformations during a rockburst caused by a controlled blast was studied. This was done by means of visual examination, mapping and photography both before and after the blast. We found that the ejected material was bounded mostly by fractures associated with the bow-wave fracturing and bedding surfaces and that existed prior to the blast. Most of the damage was caused by shake-out. This information is important input for the design of rockburst resistant support systems under conditions of moderate stress.

Jan 1, 2001

By G. R. Lane

A large opencast gold mining company in Africa had just completed a feasibility study for an expansion of the operations. A traditional net present value project valuation methodology had been used that showed a very positive net present value (NPV). The project team had conducted a qualitative risk assessment that identified and logged all potential project risks and had subjectively incorporated 'risk' via the discount rate and other assumption contingencies around gold price expectations, operating parameters, etc. Management requested that an independent quantitative risk modelling approach be adopted to obtain a better understanding of the impact of risk on the overall project valuation and confidence level in the final valuation. A detailed project valuation model was configured in the Cyest Carbon Modelling Technology platform, and the stochastic modelling module used to perform the Monte Carlo simulations. Analysis of historical operational performance data relating to actual achievements versus planned and budget determined the historical variability of the underlying parameters as well as variance to budget. This was done at a detailed level for mining rates and costs, processing rate, costs and recovery, and other operational efficiency measures. External market assumptions relating to gold price, exchange rate, and inflation were modelled and the dependency between them modelled using a copula. This case study will demonstrate the approach taken to building and populating the quantitative risk model and the overall results of the Monte Carlo simulation. The final valuation demonstrated that the project had a 44 percent probability of an NPV less than zero i.e. a 44 percent chance of project finance loss.

Jan 1, 2013