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By L Tolmay, L Nair

Investor confidence can be compromised when one observes large discrepancies between the SAMREC reserves and the mining plan. It is therefore up to the responsible persons to ensure that all contributing factors get taken into account when determining a reserve declaration. Confounding factors could be further aggravated by large oscillations in the commodity price thus resulting in major changes to the mining plan, if the accepted price was either too optimistic or pessimistic. Additional factors that must receive our attention are, uncertainty in geological facies type, mining practices, geology and grade estimation. The paper outlines (in the authors? opinion) some of the important factors that need to be taken into account, in order to ensure proper alignment between the estimates of the life of mine (LOM) reserve grades, and the corresponding actualisation of the mining plan. These parameters provide an historical insight into what actually happens when attempts are made to implement the mining envisaged in the LOM plan. In turn these allow judicious application of discount factors that enable a realistic estimate of SAMREC reserve classification and declaration. Some of the factors that will be covered are: - 1) Flexibility of developed reserves and the ability to maintain this. 2) Mining control mechanisms and their overall efficacy. 3) The ability to extrapolate facies types and its effect on grade control. 4) The ability to control the mining mix and value variation. 5) Finding a happy medium between optimism and pragmatism.

Jan 1, 2007

By E. P. Preis, R. C. W. Webber-Youngman

The real cost of any mining incident has, empirically, proven to be estimation-driven, rather than factdriven. One of the main reasons for this lies with the complexity of the cost composition of any given mining incident. Incident costs comprise both direct and indirect cost factors, and in many cases the costs associated with these factors are incurred during different time periods following the incident. In this paper we aim to identify the various cost factors arising from mining incidents, provide a thorough understanding of all the potential cost factors identified, and draw general conclusions on the knowledge obtained. Furthermore, recommendations are made on how mining companies could use the results, in order to assist them in calculating the costs of mining incidents. The paper also provides suggestions for further research, with the emphasis on the most significant immeasurable cost factors, namely the costs of implementing job accommodations following an incident, the harm to company reputation, and the decreased productivity due to low worker morale/psychological factors following an incident. If mining companies are aware of and understand which factors could contribute to the cost of any given incident, future planning and incident cost estimations could be easier. It should, however, be noted that although this study provides a comprehensive list of cost factors (and detailed explanations), other unknown cost factors relating to mine incidents could prevail in extreme cases.

Jan 1, 2021

By R. G. B. Pickering

Resue mining was practiced extensively in the East Rand in the first half of this century. The obvious benefits were that a higher grade of ore was trammed to the surface. The disadvantages were slow rates of face advance and an extremely labour-intensive method of mining. A collaborative effort by personnel from Avgold?s Target Gold Mine and Sandvik Tamrock has resulted in the design of a method of resue mining which can be totally mechanized. The purpose of this paper is to describe the methodology used and the proposed new mechanized resue mining method.

Jan 1, 2000

By P. C. Schutte

The objective of ergonomics is to enhance the effectiveness and efficiency with which human tasks are carried out. Furthermore, the objective is to improve desirable human values. This can be achieved by enhancing safety, reducing fatigue and stress, increasing comfort, increasing job satisfaction, having greater user acceptance and thereby improving the quality of life. Mechanization has influenced the prevalence of injury, mainly due to the application of human physical effort as the power source. With mechanization, the operator?s function is now essentially one of control rather than being an energy source, however, the risk of injury has not diminished. Mechanization in itself has introduced inefficiencies, health risks and physiological stress. The major objectives of ergonomics are discussed through examples of acceptable and less successful implementation of ergonomics within mechanized mining. The influence of the machine system on the human is addressed and practical solutions to improve and optimize the interaction of the human and the machine are outlined. Furthermore, practical examples of control and display integration, anthropometric and biomechanic influences on design, orientation, posture and stereotypes are used to accentuate the advantages of the application of sound ergonomics principles to the specialized area of mechanized mining.

Jan 1, 2002

Published experimental data on thermodynamic behaviour of cobalt-containing slags have been reviewed and used in validating a recently developed thermodynamic model. The results from the exercise show that the model provides a reasonably good description of behaviour of cobalt in multi-component slag systems. The models for cobalt containing slags, matte and oxide solid solution phases were incorporated into CSIRO?s multi-phase equilibrium (MPE) package, which was used to calculate the equilibrium distribution of cobalt between matte and slag phases under various conditions. The results agreed well with the experimental data. Furthermore, the good agreement between the calculation and the plant data indicates that the operating conditions of industrial smelting and converting processes are close to equilibrium. Two diagrams showing the effects of slag chemistry and SO2and O2partial pressures on the distribution of cobalt between phases were generated for conditions similar to smelting and converting processes. These diagrams provide some useful guidelines for developing new strategies to improve cobalt recovery.

Jan 1, 2004

By P. M. Solozhenkin, O. I. Solozhenkin

Currently lead nitrate is used as the recommended activator in Au-Sb flotation. However, due to high levels of hazard, the application of lead nitrate constitutes a potential risk for human health and ecosystems. To mitigate the harmful impact of activators on the environment, further research on activation by alternative reagents has been launched to promote the efficiency of antimony ores. In the present study, adsorption of lead, copper and zinc cations has been investigated by nuclear quadrupole resonance (NQR), which has revealed copper and zinc cations penetration into the mineral lattice, although lead cations remain adsorbed on the mineral surface. However, the combination of zinc and copper cations leads to preferential volumetric adsorption of zinc in the mineral lattice and further surface adsorption of copper which positively affects the activation process. It has been established that activation of stibnite can be achieved effectively with the mixture of Cu2+:Zn2+=1:1 as much as with lead cations in antimony ore flotation. As a part of this work, the computational modelling has been used in prognosis of reagent activity evaluation (PRAE) for stibnite and aurostibite flotation by sulfhydryl collectors. The lower PRAE value the stronger the ability of a collector to form a stable complex with a mineral. PRAE has shown a strong negative trend to complex formation on the mineral surface of aurostibite and stibnite. Based on these studies, several collectors have been proposed for effective flotation. To verify the feasibility of proposed collectors tetramethyl (ethyl) thiuram disulfides (TMTD and TETD) have been used for flotation of stibnite, sphalerite, pyrite and arsenopyrite. Flotation performance has been improved significantly with TMTD that allows the avoidance of lead nitrate application and increases the recovery of antimony by 8,16%. Keywords: Stibnite, aurostibite, activation, lead, copper, flotation reagents

Jan 1, 2020

By G. A. Bezuidenhout, S. Bradshaw, W. Malan

"Currently, the matted-based collection process is most widely used for platinum group metal (PGM) recovery. However, because PGM-containing concentrates are becoming more enriched with UG2 (Upper Group 2) low-grade concentrates, this is expected to be integrated or replaced with an alloy collection process.The reduction LG (low-grade) concentrates with silicon carbide (SiC) was investigated. The purpose of the study was to ascertain the feasibility of using SiC as reductant with regard to metal fall, PGM grade in the alloy, slag composition, and overall PGM recovery, and if possible, the integration of such a process in the current matte-based collection process. Rowland and Easterns LG concentrate samples from Lonmin were analysed by Xray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). It was found that SiO2 and MgO are the most abundant oxides and Pd is the most abundant of the PGMs. Sulphide-bearing minerals such as chalcopyrite were detected in low concentrations (below 1%), and Cr2O3 concentrations are between 2-4%. SiC reduction of Rowland and Easterns concentrate were conducted at 1600°C with reductant to concentrate ratios ranging from 2.5 to 3.5 kg SiC per 100 kg concentrate.The reduction experiments revealed that PGM recoveries from Rowland concentrate were poor. SEM images showed entrained metal prills in the slag phase. The slag viscosity at the end of the melt was calculated by using FactSage, and the results indicated that the viscosity was higher than 4 poise, which is above that of Easterns slag. PGM recoveries for Easterns concentrate were significantly better. More than 85% of the Ir and Pd and almost 60% of the Pt were recovered in a test with a reductant to concentrate ratio of 3.5 kg SiC per 100 kg Easterns concentrate. At this reductant to concentrate ratio, Fe recovery was also the highest, at 66%. SEM imaging of a slag sample revealed few or no metal prills entrained. The FeO content in the initial concentrate charge was then increased by adding Peirce-Smith converter slag in order to decrease the slag viscosity and further increase PGM recovery. A test was conducted with the addition of 10 kg converter slag per 100 kg Easterns concentrate. The reductant to concentrate ratio was kept at 3.5 kg SiC per 100 kg Easterns concentrate. The Ir and Pd recoveries were more than 95%, while Pt recovery was almost 70%. Fe recovery increased to 76%. On the basis of these results an optimum feed ratio between Easterns and Rowland concentrates and Peirce-Smith converter slag were calculated. FactSage predicted that the concentrate charge should consist of 70-80% Easterns concentrate with 20-30 kg converter slag per 100 kg LG concentrate. SiC reduction of this optimum LG concentrate charge is expected to recover more than 90% of all PGMs. Cr and Si concentrations in the alloy will be below 1% in total.The effectiveness of SiC as reductant was also compared to carbon reduction. Carbon reduction of an optimum concentrate charge at the same reductant to concentrate ratio resulted in a marginally higher metal fall than SiC reduction. However, gas emissions and energy requirements are higher for carbon reduction.The study has shown that base metals and PGMs can be recovered in an iron alloy by SiC reduction of LG concentrate with converter slag additions. Integration of such a process into the matte-based collection process could be considered as a future alternative for smelting UG2 LG concentrates."

Jan 1, 2014

By J. Petersen, H. Naderi, H. Zare, M. H. Nikzad, M. Karimi

In the copper electrorefining process, the dissolution of anodes is significantly reduced or even stopped when the passivation phenomenon occurs. The results of this phenomenon are increasing energy consumption, residual formatting, and voltage levels in the cell. In this study, the electrochemical behaviour of blister copper in the presence of sodium persulfate (PDS) was studied. The electrochemical methods of LPR, Tafel, and Electrochemical Impedance Spectroscopy (EIS) were used. The results showed that the addition of sodium persulfate activates the electrode surface and increases the open circuit potential. In the presence of PDS, the polarisation resistance of the electrode shows an increasing or decreasing tendency, based on the PDS concentration. This tendency is probably due to the formation of surface layers (such as slime layer or copper sulfate) and dissolution of this layer at various concentrations of PDS. The lowest polarisation resistance of 1.8 ohms and the highest corrosion current of 60.6×10-3 and 36.6×10-3 A/cm2 from LPR and Tafel techniques respectively were obtained at the concentration of 40 g/l PDS. Based on the results of potentiodynamic and electrochemical impedance spectroscopy tests, the addition of sodium persulfate to the solution reduces the corrosion resistance, therefore the passivation time of the blister copper anode increases. Keywords: Blister copper, electrorefining, sodium persulfate, anodic passivation

Jan 1, 2020

Application of Gy?s formula is appropriate for calculation of the Fundamental Error (FE) prior to samples being collected at any stage of the minerals process, provided that sampling parameters K and a (alpha) have been determined by calibration of the ores. Two types of calibration procedure are well established in the industry, the Hetrogeneity test and the 32-piece sampling tree experiment. The sampling tree experiment uses the variance and average grade of metal analyses from four series of samples at different nominal fragment size, as the basic input data. Pierre Gy suggested the cube as an appropriate exponent of the nominal fragment size for use in his equation. More recent work suggests that this exponent is variable and characteristic of specific ores and therefore requires calibration. The method described here explains the experimental procedure of the calibration. It is then possible to calculate a sampling nomogram using the sampling parameters K and a. This allows the sampler to determine a suitable protocol for the sampling event that will ensure that the FE does not exceed a predetermined precision at any point in the sampling procedure.

Jan 1, 2007

By L. K. Witika, J. H. Masinja

"Investigations of flotation characteristics of Lumwana and Kansanshi ores using formulated frothers were carried out. Of the six frothers tested, two came from the alcohol family, two from the glycol family and last two were formulated products. The initial work involved determining the optimum mesh of grind and frother dosage for Lumwana and Kansanshi ores. Further work involved carrying out surface tension, bubble size and froth stability measurements. Finally, water recovery tests were conducted at Lumwana and Kansanshi mine sites. For froth stability tests, six frothers were tested on a two-phase (water–air) system using the Bikerman column flotation cell, while water recovery tests were conducted using a total of seven frothers, including the standards for each plant. The results of the testwork showed that (i) although a stable froth is essential for optimum recovery of valuable minerals, a higher molecular weight frother, like Dowfroth 250, caused poor selectivity when used on fine ores and (ii) a lower molecular weight frother was suited for Lumwana ore, while a mid to higher molecular weight formulated product was suitable for Kansanshi sulphide ore. INTRODUCTION Investigations of flotation characteristics of Lumwana and Kansanshi ores using formulated frothers were carried out. The initial work of this project involved determining the optimum mesh of grind and frother dosage for Lumwana and Kansanshi ores. Further work involved carrying out surface tension, bubble size and froth stability measurements. Finally, water recovery tests were conducted at Lumwana and Kansanshi mine sites. In order to investigate the gangue entrainment levels in the Lumwana and Kansanshi sulphide ores, two well-known methods (froth stability and water recovery) were used. Firstly, froth stability tests were conducted using six frothers, two from the glycol family (Dowfroth 200 and Dowfroth 250), two from alcohol family (MIBC and pine oil) and other two from the formulated family (Betafroth 20 and Betafroth 245), at the University of Cape Town’s Centre for Mineral Research (CMR) laboratories. Froth formation and stability measurements were conducted using the Bikerman column flotation cell."

Jan 1, 2015

By D. Tesh

The mining industry worldwide is facing a tremendous shortage of minerals engineers in all fields of specialization. For instance, in Australia the skills shortage in the mining industry has been identified as one of the top risks facing the mining industry. In Namibia most minerals engineers employed are expatriates, with some being Namibians who studied abroad. The minerals engineering programmes at the Polytechnic of Namibia are still in their infancy. These programmes were designed to meet the mining industry skills needs. Being young has its advantages in that lessons can be learnt from older minerals education institutions that went through similar challenges. However, this does not imply just copying and implementing their approaches, since the context differs and, to ensure sustainability of the minerals education programmes, curricula have to be customized to the local context. This paper reviews the interventions made by the Polytechnic of Namibia in order to ensure the sustainability of its minerals education programmes. The methodology consisted of an extensive literature review, a status quo analysis of the mining and process engineering department, identifying the gaps between the current state and desired state, and mapping the goals and strategic actions required to progress to the desired state. The following factors were identified as major threats to the sustainability of minerals education at the Polytechnic of Namibia: the quality of students, low student enrolment rates, low pass rates in science and mathematics, shortage of academic staff, dwindling government funding, and limited involvement of the mining industry. The major outcomes of this research comprise the detailed strategic actions employed by the Polytechnic of Namibia to address the threats to sustainability of its minerals education programmes.

Jan 1, 2014

The coal-based power generation industry faces increased pressure from all sectors to improve its environmental performance. This is due to increased awareness of and concerns regarding greenhouse-and acid-gas emissions, toxic metal releases (to both air and water) and water availability. A methodology to assess this industry?s environmental performance is needed. Such a methodology should assess all environmental impacts accurately, recognizing the irspatial and temporal dependence, and taking into account the social acceptability of technologies employed. Here, we develop a methodology to determine the environ-mental impact associated with solid wastes generated by this industry, and apply this to the specific case of ash management. More specifically, the case study compares the environmental footprint of an ash deposit for a number of operational water management scenarios. The methodology considers leachate generation processes from ash impoundments to obtain a time-dependent concentration profile of mobile constituents at the interface between the ash impoundment and the surrounding environment. This leachate prediction modelling is subsequently linked to plume dispersion modelling tools to determine the fate and transport of leached components, predominantly salts, into groundwater. Together, these provide a measure of the extent to which a land mass is affected by leachate migration from the deposit. To determine the exact boundary between regions of acceptable and unacceptable risk to the environment, we use Ecological Risk Assessment concepts. In this way it is possible to obtain a time dependent affected land footprint which could be used as an indicator of the environmental impact of solid waste management practices. This information can be included in a set of environmental criteria which form the basis of an overall environ-mental impact assessment, using tools such as Life Cycle Assessment (LCA). The value of LCA is that its structure is consistent with accepted models of environmental decision making, where different approaches to valuation in impact assessment assist in prioritizing impacts on the basis of their perceived significance. The proposed ?affected land footprint? metric represents a significant improvement over current LCA impact indicators for solid waste management practices. Keywords: Environmental Impact Assessment, Environmental Risk Assessment; Life Cycle Assessment; coal ash; leachability; salinity

Jan 1, 2002

By W. M. Jansen

In many mineral processing operations, the reported production figures for an accounting period may not make the best use of available data. While most of the mathematical approaches, such as check-in/check-out, mass balancing, used in effective metallurgical accounting strategies are well understood, the sources and magnitude of measurement errors generally are not. As part of the 'AMIRA P754-Metal Accounting and Reconciliation' project, a study was undertaken at the Northparkes copper/gold concentrator near Parkes, New South Wales to examine the data used in their concentrator metallurgical accounting system. This paper summarises the results of a detailed examination of the mass measurement systems around the concentrator as well as the primary sampling system used for grade estimation. The goal of this work was to develop practical techniques to quantify the error (ie both accuracy and precision) of the measured metal accounting information. With this information, statistical confidence levels for this data can then be calculated. If the errors are small, the effect of error in each piece of measured data can then be propagated to other calculated production figures such as recovery and feed grade using a statistical technique called `the propagation of error'.

Jan 1, 2007

By N September, R Abate

Bateman Modular (previously Van Eck and Lurie) has been building and supplying the mining industry with modular DMS plants for the last 30 years. These DMS modules range in capacity from 1 tph to 200 tph. The most popular unit produced by Bateman Modular over the years has been the 50 tph module. Development In the last 7 years a need has arisen from the industry to provide Modular DMS plants that can treat higher tonnages (150 to 200 tph). The first DMS provided to the mining industry based on the modular concept was a 150 tph DMS Module to MIBA in the DRC. Since then Bateman Modular has provided some 14 Mega DMS modules over the last 7 years with the latest two orders from Debswana (Damtshaa double up project) and Namdeb. Ever since the first Mega Module was supplied Bateman Modular has been improving the Modules. Implementation The modules can be supplied in different configurations so as to improve the overall availability of the plant. Two off 150 tph DMS modules were supplied for a Transhex operation. This allowed the client to still operate one DMS module while maintenance is being performed on the other DMS module. The client also has the option of choosing a single module. Successes The following list of projects provides the base for the success of the Mega Modules.

Jan 1, 2006

By P. T. L. Koh, M. P. Schwarz

A series of parametric studies were carried out for a flotation cell using computational fluid dynamic (CFD) modelling to determine the local response of hydrodynamic performance measures to change in operating conditions. As an example, an Outotec cell was used to carry out the response analysis. The hydrodynamics of the flotation cell has been previously investigated by laboratory measurements presented by Schwarz et al (2019), and a CFD model of the cell was developed and validated using these measurement data (Schwarz et al., 2019). In this work, parametric studies have been performed by modelling the flotation cell at different stirring speeds and gas flowrates, varying above and below standard conditions. Predictions of void fraction, bubble size, bubble surface area flux and particle–bubble collision rate are presented showing the effects of increasing and decreasing stirring speed and gas flowrate around the base case. Generally, the total gas holdup in the flotation cell was found to increase with increasing gas flowrate. The bubble diameter was found to decrease with increasing stirring speed and increase with increasing gas flowrate. The collision rate increased with both stirring speed and gas flowrate. The parametric results show that there is a correlation between the bubble surface area flux Sb which is affected by stirring speed and gas flowrate, and the particle–bubble collision rate. With the collision rate as an indication of flotation collection, it is also possible to show that cell performance can improve more by increasing stirring speed than by increasing gas flowrate in a situation where everything else remains constant. The CFD results can form the basis for a Response Surface Method (RSM) analysis which can then be used for automated optimization of cell performance. Keywords: Flotation kinetics, computational fluid dynamics, bubble surface area flux, particle-bubble collision rate

Jan 1, 2020

By F. T. Cawood

One of the consequences of globalizing mine finance is a necessity to apply uniform accountancy and valuation standards that are clearly understood and consistently applied by the global investment community. However, each country has unique circumstances, which sometimes make it difficult to align domestic practice with international requirements. South Africa is no exception and issues such as its political history, a taxation regime enforcing different rules on different mineral producers and a unique mineral rights ownership distribution, are barriers to internationalization. The economy is in a transitional phase as a result of the many and diverse policy documents following the change in political dispensation in 1994. Many of these documents have recently been implemented through new legislation and, in the case of mining, negotiations are continuing in order to ensure an acceptable outcome. This paper discusses the challenges that the South African minerals industry faces in the field of mineral property valuation. It draws on international experience and includes a discussion on the unique considerations that the South African mineral property market must take into account in establishing a code for this purpose, as such a code could later be aligned with international practice.

Jan 1, 2004

By P. E. Venteer

The Grootegeluk coal-processing plant treats 3 kt of raw coal per hour to produce a middlings fuel coal and a coking coal fraction with ash contents of 35 and 10 per cent respectively. The plus 0,5 mm fraction is treated by heavy-medium processes, the final top size of the coal being 15 mm. About 400 t of minus 0,5 mm coal per hour is subjected to froth flotation. The routes originally considered for the processing of this fine coal were froth flotation, shaking tables, heavy-medium cyclones, and water only cyclones in combination with froth flotation. The results from tests on the fines arising from a small-trial open-cast mine are discussed. When the froth flotation route was decided upon, further tests were conducted on the selection of the equipment most suited to the particular requirements of this coal and the rest of the plant. Tests using different types of flotation cells and dewatering equipment are discussed. During the commissioning, several operational problems were encountered, and the work done to find the best solutions is discussed.

Jan 1, 1984

By B. Elevli

This paper deals with the selection of alternative accesses to a podiform chromite orebody in Turkey. The most important alternatives studied in a related project have been stated as a new vertical shaft and a ramp system. The comparison of these alternatives have been carried out on the basis of total investment costs, ore transport unit cost and net present value (NPV) of overall project for various depth. The results show that up to the depth of 700 m, the total investment cost and NPV favours the ramp access while unit ore transport cost make the shaft access preferable.

Jan 1, 2002

By J. B. Oosthuizen

Mechanical rock breakers are used in block caving operations to reduce the size of ore fragments which are too large to pass through grizzlys at the load-haul-dumper tipping points. Several layouts of grizzly, rock breaker and ore pass are possible. The authors evaluated three different layouts at the Premier Mine Division of De Beers Consolidated Mines. The first layout consisted of a 15m surge bin before the breaker, which was located 15 m below the production level. The second layout had a 43 m longs urge bin, with the breaker located 43 m below the production level. The third layout did not have a surge bin, the breaker was located on the production level and operated at the tip. The ore throughput, availability and utilisation, delays, costs and operational experience with each system are discussed. It was found that the rock breakers did not represent a bottleneck in the ore transfer system and a surge bin did not significantly improve the production capacity. The mine has decided to make use of rock breakers situated on the production level, breaking rocks at the tip.

Jan 1, 1997

By R Kroukamp

Horizontal belt filters are typically used for separation of relatively free filtering solids where good post treatment is required. He horizontal belt filter is a continuous filter with an endless cloth supported on a grooved carrier belt. The belt and cloth are driven around two rollers across a series of evacuated suction boxes. The feed suspension is introduced at one end of the filter and deliquored to produce a cake at the other end. The benefits of using horizontal belt filters are good cake washing, continuous and visible processing, fully automatic operation, flexibility, high capacity and relative high speeds of operation. If required, horizontal belt filters enable efficient counter-current washings to minimize the usage of wash liquid. The horizontal belt filter has applications in the following: [? Metal concentrates ? Mineral sands ? Tailings ? Coal ? Iron ore ? Alumina ? Chloride processing ? Nickel and Cobalt refining ? Platinum group metals ? Zinc processing ? Many other applications in the Mining and Metallurgy industries ] 2. Operating Principle of a Horizontal Vacuum Belt Filter 2.1 Cake Forming The slurry to be dewatered is evenly distributed onto the filtering surface. Gravity assists the cake formation and the feed can be introduced in multiple stages. 2.2 Cake Washing Once the cake is formed, wash liquor/water can be introduced onto the top of the cake via a wash launder or sprays. Multiple wash stages, co-current, counter-current or direct washing can be added by increasing the length of the filter.

Jan 1, 2007