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"SAMPLING: THE IMPACT ON COSTS AND DECISION MAKING1. INTRODUCTIONFor years those in the minerals industry have been taking samples to assist them in making decisions; whether they be about investing billions of rand in a new mining operation, or simply whether a truck load of mineralised material should go to the mill or the waste dump, - we need a sample to help us make our decisions. This paper emphasises the importance and significance of sampling as a process, some of the associated technical problems and some of the advantages, especially in the light of traditional approaches that has usually left mine sampling to the least educated and lowest paid individuals on the mine. Perhaps the most important aspect that requires attention is the variability, usually measured in terms of precision, that tends to infect the sampling procedures. Francis Pitard 12 has stated: ""There is no such thing as reliable feasibility studies, unbiased ore grade control, accurate environmental assessments or effective process control, if you cannot identify and minimize the seven (ten) major sources of sampling variability. "" It is these ten sources of sampling variability and the way they arise that are briefly investigated. Variability is measured in terms of variances and rather than being self-compensating, there is good evidence to indicate that they are in fact additive at every step in the sampling and analytical process."

Jan 1, 2014

By A. Chuma, K. J. Nyembwe, H. Simonsen, J. H. Potgieter

Different concentration techniques were evaluated for preconcentration of a mineral ore at a coarser size to avoid energy and resource wastage. Specifically, the aim was to reduce milling costs and energy required in the beneficiation of tin. In this study, cassiterite (0.17% Sn) was the mineral of interest in a pegmatite ore body associated with quartz (SiO₂ > 60%) and alumina (Al₂O3 > 20%). Three concentration techniques, namely dense media, shaking table, and flotation, coupled with characterization analysis, were used to assess the concentration response. The results confirmed that particle size and mineral liberation impact the separation process. High recovery and grade were obtained with gravity concentration methods (dense media and shaking table) for coarser (+300 to +212 μm) and intermediate (+150 to +53 μm) particle sizes. Lower recovery and grade were identified for much finer sizes (−53 to −38 μm). Flotation produced a high-grade product at a relatively low recovery and appeared to be only applicable to finer grains. Separation efficiency based on Schulz’s equation measured a segregation performance of 74.8% for dense medium separation and 60.7% for the shaking table for the coarse and intermediate particle sizes. Flotation only achieved a separation of 30%–40%. The results suggest that use of dense media separation as a rough preconcentration method prior to further grinding, and the utilization of a more advanced concentration technique for mineral recovery and upgrade, constitute a successful approach to improve process economics.

Apr 14, 2024

By P. C. Pistorius, D. Kruger, Y. Kacar

Because of its superior properties, stainless steel has been widely used for many applications. Nonmetallic inclusions can influence the quality of stainless steel products. A set of samples was used to track the response of inclusion composition during processing of a heat of titanium-bearing 18% chromium steel, from deoxidation after decarburization, to the solidified slab. The oxide inclusions responded as expected to additions of deoxidizers and calcium treatment, changing from silica to alumina and spinels, and then to calcium aluminates. The samples confirmed that titanium nitride can nucleate on liquid calcium aluminate during steel solidification.

Aug 1, 2021

By R. Castro, R. Gómez, F. Betancourt, M. Moncada

In block cave mining, rock fragmentation is a key parameter that influences the production level design and mine planning. Fragmentation occurs mainly by natural breakage during the caving process and in the draw column. The breakage that occurs within the column is known as secondary fragmentation. Secondary fragmentation has been successfully described using the block caving comminution model, which replicates the fragmentation mechanics between particles under drawn and vertical loads in a draw column. This model is based on a kinetic and population balance approach, in which non-normalized and normalized assumptions can be used depending on material and comminution system behaviour. In this paper, the non-normalized and normalized approaches are applied and compared to laboratory data to determine which assumption should be used for secondary breakage in block caving. Approaches are compared graphically, with the mean square error and the Fisher test with a false-rejection probability of 0.05. Based on a statistical analysis, the results show that the normalized model can be applied to all the rock types tested.

Nov 1, 2021

By M. Steyn

The coordination compound tetrakis(1,3-diphenyl-1,3-propanediona to)zirconium(IV), [Zr(DBM)4], (DBM = dibenzoyl methane/1,3- diphenyl-1,3-propanedionol) was synthesized and characterized by single-crystal X-ray diffraction. [Zr(DBM)4] crystallizes in the monoclinic space group P21/c (a = 24.769(4) Å, b = 10.216(5) Å, c = 19.314(4) Å, and = 101.541(5)°). The coordination geometry around the zirconium atom, formed by the eight O-donating atoms of the four -diketonates, is found to be a near-perfect square antiprism. Crystal packing is stabilized by C?H... interactions throughout the crystal lattice. This structure is a noteworthy example of the application of ambient condition synthesis of zirconium compounds in N,N'-dimethylformamide (DMF) as reaction and crystallization solvent, highlighting the possibilities of aerobic condition metal purification through chelation.

Jan 1, 2014

By D. Skelton

The Renard kimberlite cluster is located in the Monts Otish region of Quebec, Canada. A Canadian National Instrument (NI) 43-101 compliant resource statement for the Renard kimberlites 2, 3, 4 and 9 and the Lynx kimberlite dyke was first issued in 2008 followed by a Preliminary Economic Assessment and the development of a conceptual mine plan. Following a successful drill program in 2009 that greatly expanded the amount of kimberlite in Renard 2, a revised resource statement was issued in December 2009 comprising 23 million carats of Indicated Mineral Resources and 13 million carats of Inferred Mineral Resources, a threefold increase on the previous estimate. The project is currently the focus of a second Preliminary Economic Assessment and it is expected that a full feasibility and permitting program will commence in 2010 leading to the creation of Quebec's first diamond mine by 2013.

Jan 1, 2010

By F. Nakhaei, M. Le Roux, Q. P. Campbell, S. Botlhoko

The results of coal sink and float tests are plotted as washability curves. Analysis of these curves indicates the most effective method by which the coal can be cleaned. Sink and float experiments are samplingdependent, destructive, and use toxic chemicals. The present research introduces an alternative method based on a 3D imaging system called RhoVol, in which the density of individual particles is determined from mass and volume measurements. A quantitative error analysis was conducted on coal sample density measurements obtained by RhoVol, and the main factors influencing the errors identified and investigated. The results show that the drawback of this technique is related to its not being able to detect hidden concavities in the particle, resulting in an overestimation of particle volume. Furthermore, it is difficult to capture the impact of porosity and cracks on the volume of coal particles obtained from 3D silhouette images. This mismatch between the RhoVol data and sink and float test results has led to attempts to apply neural network (NN) and linear regression techniques to produce a fully reliable model for correction and estimation of coal density. The NN approach offers superior predictive capability over linear regression, and the estimated density distribution is in line with the sink and float analysis. The root mean square error in estimation of density using the NN model was less than 0.05 g/cm³.

Aug 2, 2022

By N. Naudé, J. de Villiers, C. P. Bergmann

It is proposed that the physical and chemical composition of individual mineral particles are an appropriate basis from which to model the performance of minerals processing equipment. Such a particle-based approach enables modelling across disciplines such as comminution, classification and flotation and automatically generates the traditional mass and chemistry balances. The general approach followed is to generate full grade-recovery curves for a separator by sampling product and tailings at varying mass yields. AutoSEM characterisation of each sample provides particle data that is used to reconcile mineral deportment and liberation to the measured size and assay data. In this way, partition surfaces can be generated and modelled. In this paper, an empirical model for the performance of a gravity spiral concentrator treating fine chromite ore is proposed. The model is based on the combination of two partition surfaces and is able to accommodate both forward and reverse gravity concentration effects per size fraction. The results show that this approach is well suited to represent spiral performance for the cases evaluated. The effect of two feed particle size distributions on the performance of the Multotec SC21 and SC25 spirals is demonstrated. Simulations are run in an Excel environment, linked to Python-enabled routines for enhanced data management and calculation speed. Keywords: Spiral concentrator, gravity separation, particle-based modelling

Jan 1, 2020

By A. Golder, S. P. Dandapat, I. Roy

One of the consequences of large-scale opencast mining for coal is the disposal of an enormous volume of overburden material that needs to be removed. With the enlargement of opencast mines and associated high stripping ratios, the volume of overburden extraction is rising. Overburden from the initial mine cut has to be necessarily dumped outside the mining area until enough void is created inside the mine for back-filling operations. The quantity of overburden placed outside the mining area normally varies from 10% to 30% of the total overburden removal. The stability of these dumps placed outside the mining area is of prime importance from the point of view of smooth operations of the mines and safety of persons in and around the dumping area. Owing to increasing pressure on land use, mine operators do not have any other option other than to place the waste dumps very near to the surface edge of the pit, which may lead to failure of the topsoil benches of the working pit. This study identified major controlling parameters that influence a stable but economic combination of height and slope angle of external dumps located close to the edge of an open coal pit.

Nov 27, 2024

By S. Durapraj, R. T. Masethe, U. Maqina, A. C. Adoko

This study investigates seismicity and rockburst control within the Merensky Reef and UG2 orebody of an intermediate-depth platinum mine located in South Africa's Bushveld Complex. Utilising a mine-wide seismic monitoring system, over 1,900 seismic events were recorded between April 2023 and May 2024, revealing complex seismic patterns driven by mining-induced stress changes. The largest event, with a magnitude of ML 2.0, underscores the seismic risks associated with mining at increasing depths. Key findings include the spatial and temporal variability of seismic events, with high seismic activity observed near pillars and geological structures. A significant portion of events correlated with pillar and foundation failures. Moment tensor analysis identified dominant failure modes, such as stress-driven fracture closures and dynamic pillar failures. To mitigate risks, the study emphasises advanced support system redesign and rockburst risk assessment using the rockburst damage potential (RDP) method. The research highlights the importance of monitoring, geotechnical compliance, and adaptive designs in enhancing safety and reducing seismic hazards in underground mining operations. The study applied the RDP framework, classifying damage across R1 to R5 scales, where most instances fell into low-risk categories (R1 and R3), indicating minor to moderate damage. However, data limitations and the tabular stoping method's complexity led to inconclusive results, highlighting the need for more robust data and customised risk assessment tools. Despite these challenges, the RDP approach provided valuable insights into rockburst mechanisms and the effectiveness of existing support systems.

Jan 12, 2025

By G. T. G. Emere

The Johannesburg Branch of The South African Institute of Mining and Metallurgy was officially inaugurated at a General Meeting held in Kelvin House on Monday, 18th January, 1988. In addition to nominating committee members, Mr G. T.G. Emere delivered a presentation on the Barbrook gold-mining project, which is currently in the development phase some 40 km east of Barberton.

Jan 1, 1988

By H. M. Friede

Discussion of the above paper by A. SIFF The steely nature of the Iron Age objects mentioned in Dr Friede's paper point to two hypotheses. (1) The African iron workers were conversant with the art of direct steel manufacture. (2) They were less knowledgeable of the art of the production of carbonless iron. In this context I cannot but quote T. A. Wertime.

Jan 1, 1980

By M. J. Nicol

On page 51, the equation numbered.... On page 52, the equation numbered .... On page 53, the arrangement of the equation.... Canadian reports Asbestos by G.O. Vagt.l0 pp. Chromium by D. G. Law-West. 6 pp. Iron and Steel by T. R. Mclnnis. 15 pp. Titanium and Titanium Dioxide by M. A. Boucher. 7 pp. Vanadium by D. Shaw. 7 pp.

Jan 1, 1984

By K. Wu, L. Li, D. W. Zhou, J. W. Yu

The presence of a fractured water-conducting zone (FWCZ) is of significant importance for the safety of underground mining under water bodies. When a coal mining area is covered with a thick layer of alluvial soil, the height, width, and distribution pattern of the FWCZ in the area shows unique features. The internal mechanism by which thick alluvial soil affects the FWCZ is still unknown. Using the Huainan coal mining area (HCMA) in China as a case study, we investigated the impact of thick alluvial soil on the height, width, and distribution pattern of the FWCZ through numerical simulation using the distinct element method, theoretical derivation, and data validation. The results indicate that a thick layer of alluvial soil inhibits the FWCZ height and increases the FWCZ lateral width. When the soil-to-rock ratio is greater than a certain value (the numerical result in this study is 15:18), the FWCZ height and width are affected by the thick alluvium significantly, and the thick alluvial soil alters the shape of the FWCZ from tall and thin to short and wide. The load exerted by the alluvial soil transfers downward to influence the FWCZ; however, this process is obstructed by the hard strata in the bedrock. Therefore, the vertical and lateral change trends show a similar step pattern. Our results can provide a basis for accurate calculation of the FWCZ height in mining areas with thick alluvial soil, to mitigate mine water hazards and increase the safety of underground mining in coal mines covered with a thick alluvium layer. Moreover, reducing the FWCZ height can help extend the upper extraction limit in coal mines covered with a thick alluvium layer, which reduces the thickness of the impermeable coal pillar and increases coal production.

Jan 1, 2016

By E. Govender-Opitz, L. Lelia

The South African mining industry plays a significant role in the economy of the country. Nonetheless, the negative impacts on the environment continue to prevail. In regions where mining exists in proximity to communities, mining activities have led to the disruption of modality. Rural communities are mostly affected as they depend on land use for agriculture to sustain their livelihoods. The conversion of land for mining activities often leaves the communities vulnerable when mines close because of the limited life span of mines. An ongoing discourse focuses on how the mining industry can contribute to sustainable development of the communities in which they operate. Post-mining transformation offers an approach for the mining companies to contribute to sustainable livelihoods post-mine closure by strengthening rural-urban linkages, which ensures inclusive development of both rural and urban areas. The paper employs a case study approach to Richards Bay Minerals and the adjacent rural communities of Sokhulu and Mbonambi. It sets out to understand the post-mining transformation employed by RBM and explore the rural-urban linkages that manifest as a result. Findings show that sand dune rehabilitation employed by RBM is successful in restoring soil fertility and establishing the natural ecosystem. The casuarina planted to rehabilitate the dunes is used to spur an alternative charcoal industry post-closure. The main rural-urban linkages that manifest are flows of people due to job opportunities and flows of goods from the sale of charcoal produced. However, there is a lack of communication and lack of authority to ensure responsible management of the casuarina plantation and equitable sharing of benefits. The paper recommends that other post-mining transformation strategies such as eco-tourism should be explored and that the government, at both national and local level, the community and the mine should be involved to ensure overall success and sustainability of the strategy. Keywords Post-mining transformation, rural-urban linkages, alternative land use

Jan 1, 2020

By D. Nardini

The need to move towards faster and safer mine development is a key priority in mining houses globally. In addition to this, South Africa faces an array of challenges introduced by labour-intensive operations; hence a study was conducted to look into improving development rates and labour productivity, specifically in the areas where trackbound flat-end development is required. The aim of the study was to propose a method to deliver fit-for-purpose tracked tunnels that advanced at a rate of one blast per end every single working day. A major part of the study was to optimize the selection of an appropriate trackless fleet and mitigate any constraints introduced with the mechanization. This was done by creating scenarios, based on a typical case study, looking into the aspects around safety, mine design, mine activity cycling, men and machine requirements, service installations, and trackless-trackbound interfaces. The case study was based on a deep-level gold mine developing twin headings with connectings; however, with the move to extend and deepen platinum operations it is foreseen that twin end development will become more prevalent due to ventilation, logistical, and other requirements. With the introduction of the trackless mechanized system suggested, development rates of 56 m of system advance are expected (189 m total development), with on an average of three headings and fixed blast times. Scenarios run with multi-blast conditions yield expectations of 75 m/month advance of the system, significantly higher than the conventional performance seen today.

Jan 1, 2012

By G. L. Dyer, R. D. Alorro, R. E. Browner

A potential new rare earth extraction process has been suggested (Lazo, et al., 2017) (Lazo, et al., 2018) based on converting the rare earth elements to solid phase rare earth oxalates in an oxalic acid leach. Oxalic acid consumption is a significant issue in the process, therefore to improve the viability of this proposed new extraction method, a process to recover oxalate from the leach solution and recycle oxalic acid is required. A review of the literature and confirmation through thermodynamic analysis of the potential options identified precipitation of calcium or ferrous oxalate as the best potential options. The use of metallic iron to both provide ferrous ions as a precipitant and reduce ferric ions in solution would provide the most economical option, however slow kinetics and unreacted iron created significant issues with this process. The direct use of ferrous ions, while faster and more efficient, produced a precipitate with relatively poor solid/liquid handling characteristics and would require an intermediate stage utilising calcium in regenerating the oxalate. Utilising calcium chloride and oxide created very similar precipitates with better physical properties than the ferrous oxalate and that a reasonable proportion of the oxalate could be recovered before neutralisation of the solution induced precipitation of other phases such as iron oxy-hydroxides and calcium phosphate. The produced calcium oxalate was easily converted to oxalic acid and gypsum via immersion in sulphuric acid. It was also found that there is a significant loss of oxalic acid due to factors other than rare earth oxalate precipitation during leaching. This leads to a maximum oxalate recovery in the range of 50 %.

Jan 1, 2020

By F. L. D. Cloete, A. K. Haines, T. D. Sampson, T. H. Tunley, W. A. M. te Riele

The recovery of zinc from pickle liquors by ion exchange A. K. HAINES. Ph.D. (Visitor) T. H. TUNLEY. B.Sc;.(Chem.Eng.)(Visitor), W. A. M. TE RIELE. pr, Eng.. Ph. D. (Visitor), F. L. D. CLOETE. M.Sc. (Chem..Eng.)(Visitor), and T. P. SAMPSON. Pr. Eng.. BSc, (Chem.Eng,). B. Econ. (Visitor) Picklers and galvanizers in and around Johannesburg are encountering an ever-increasing problem in disposing of spent liquors from their hydrochloric acid pickling baths. Particularly troublesome is the zinc-contaminated liquor that is produced as a result of the clean-up of rejects from the galvanizing operation. Because of the volatility of zinc chloride. this liquor presents difficulties when processed in a conventional pyrohydrolysis acid-recovery unit. The paper describes the Metsep Process. developed by the National Institute for Metallurgy and Woodall-Duckham S.A. (Pty) Ltd. which involves the use of continuous ion exchange for the separation of the zinc from the pickle liquor. and the use of liquid-liquid extraction for the conversion of zinc chloride eluate to salable zinc sulphate. A description of laboratory and pilot-plant tests is given. and the approach used in the design of a full-scale continuous- ionexchange plant is outlined.

Jan 11, 1973

By R. E. Gürtunca, D. J. Adams

Writen contribution by J.F.Curtls The subject mater of the paper is interesting in that, instead of 'numerical modeling based on elastic theory' being used for the prediction of energy release rate (ERR) in relation to various types of stope support, including backfil, use is made of stresses in the backfil in an atempt to corect the numerical modeling. Authors' reply to J. F. Curtis We thank Mr Curtis for his contribution to our paper. First of al, it should be emphasized that the object of the paper is not to address the validity of ERR as a tool for the assessment of seismic events or rockbursts, but to determine an in situ modulus for the rockmass with the aid of backfil measurements. Writen contribution by T.R. Stacey Although the authors of the above-mentioned paper have presented some good and interesting information, the title of the paper, and the recommendation that such an in situ modulis should be used for calculations of energy release rate (ERR), are viewed with some concern. The reasons for this concern are as follows. Authors' reply to T.R. Stacey Dr Stacey's comments on our paper are appreciated; we should like to address his concerns as follows.

Jan 1, 1991

The Annual General Meeting of the South African Institute of Mining and Metallurgy was held in Kelvin House on Wednesday, 22nd August, 1979. Dr M. G. Atmore (President) was in the chair and declared the meeting open at 16h00. Obituaries President: It is my sad duty to announce the death of the following Members of the Institute : Brigadier R. S. G. Stokes, Honorary Life Fellow and Past President ; J. A. Arthur, C. L. Cartwright, R. B. Greaves, A. A. Haynes, G. Ross, M. W. Richards, W. T. Stobart, E. Veres, G. V. White, and A. G. Williams, Life Fellows; A. J. H. Pole, D. T. McMurray, P. G. O. Pretorius, A. E. D. Rubidge, A. M. Seccombe, and R. R. Uren, Fellows; R. E. Oltman, R. B. Richardson, and G. P. Rundle, Members; S. F. Dench and S. van Wyk, Associates. As a mark of respect to the memory of the deceased, and in sympathy with the bereaved, please rise and observe a few moments' silence. Minutes President: May we confirm the minutes of our last Annual General Meeting, which was held on 23rd August, 1978, as published in the November issue of the Journal? Agreed.

Jan 1, 1979