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By Roger A. Blais, Michel David

"Matheron's geoslalislical method for the estimation of ore reserves has been developed to the point at which real-life problem may be handled effectively. The steps involved in the method are:(i) obtalning the variogram,(ii) fitting a model, and(iii) producing block estimates.All three steps may cause difficulty, and would-be users need a deep understanding of the theory if failure is to be avoided.To illustrate these points, specific cause are considered:(i) two almost equidimensional porpbyry deposits, one drilled randomly and the other regularly; and(ii) two iron formation, one drilled extensively and being mined, while the other is still at the stage of early estimation."

Jan 1, 2014

By J. Sehata, J. Tshilongo, I. Govender, S. Pikinini, T. L. Moodley, M. Raedani

In the face of dwindling Merensky ore reserves in the early 1990s, Mintek developed the MF2 flotation circuit to economically recover platinum group metals from the shallow upper group-2 chromitite reef. By aligning the primary and secondary grind to the platinum group metal liberation kinetics, excessive fine chromite generation was avoided, and thus one could consistently produce high-grade concentrates (>200 g/t platinum group metals) with low chrome content (<3% Cr2O₃), well within smelter tolerances. This, coupled with upper group- 2's low-cost open-pit mining, made it particularly attractive to investors and mining houses alike. As a result, deeper lying reefs like middle group and lower group with lower platinum group metals grades and complex mineralogy, were primarily mined only for chromite using density-based separation processes (like spirals), of which the waste tailings are best classified as secondary platinum group metals resources. Today, with global platinum group metal demand rising and high grade upper ground-2 reserves rapidly diminishing, the industry must revisit these middle group and lower group tailings. Mineralogical analysis reveals several challenges: Middle group tailings feature platinum group metals locked within silicate matrices, while lower group tailings contain fine chromitite fragments, and are hosted within non-floating laurite grains, each presenting liberation and gangue issues. Smelter constraints still demand concentrates below 3% Cr₂O₃, requiring solutions that consider both platinum group metals recovery and chrome entrainment. To develop a solution, two lower group chrome spiral tailings samples were obtained from a large chrome mine: Sample A (+425 μm – 106 μm) and Sample B (−106 μm). Initial assays showed Sample B contained higher platinum group metal grades but also higher Cr₂O₃. As such, different blends of flotation feeds were evaluated using ratios of 90:10 (C1) and 80:20 (C2) of Sample A to Sample B, targeting the coarse fraction's lower chrome content while recovering valuable platinum group metals from the fines. This work proposes a practical route for mining houses to unlock additional platinum group metal value from lower group ore spiral tailings. By optimising blending ratios and reagent suites, it is possible to meet smelter chrome and platinum group metal grade thresholds, whilst still obtaining economically viable PGM recoveries.

Mar 6, 2026

By T. P. Chidakwa, T. R. Stacey

This study investigated the corrosion rates of various steel types and coatings used for friction rock stabilisers in a deep-level gold mine under diverse underground environmental conditions. Testing was conducted in situ within ramps, intake airways, and exhaust airways, and through simulated laboratory experiments. Results revealed that environmental variations significantly influence the corrosion performance of different materials and coatings. Duplex coatings, made up of galvanised steel with an organic paint layer, demonstrated the highest corrosion resistance. Zinc-based coatings provided moderate protection, while 3CR12 stainless steel and uncoated S420 carbon steel exhibited comparatively poor resistance under both aqueous and atmospheric conditions.

Mar 4, 2025

By M. Nicolle

The Tati Activox® Project will be the first full-scale implementation of the patented Activox® process (The Tati Activox® project was deferred in 2008. Please refer to the Norilsk Nickel press issue on the topic for more info). The process was developed by Norilsk Process Technology and has been tested on Tati mine sulphide concentrates in laboratory, pilot and demonstration plant scales and demonstrated its viability. There are inherent risks to the final scale-up of the process from the demo plant and one of them will be investigated in this paper. Compartment 1 is designed to leach approximately 77% of the total nickel leached. For this reason agitation requirements in the first compartment of the autoclave are reviewed. An attempt is made to minimize the process and mechanical risks associated in achieving oxygen mass transfer into the slurry solution. The agitator powers for oxygen mass transfer are calculated using empirical correlations and compared to demonstration plant testwork. The resulting gassed power per unit volume (P/V) is higher than most commercial autoclaves and raises uncertainty on the viability of using such high unit power inputs. Additionally, there is concern about the ability of the autoclave shell to withstand and support the higher loading of large agitators. An alternative solution to designing for the increased P/V is assessed in which the number of compartments within the autoclave is reduced from 5 to 4 by removing the compartment wall separating compartments 1 and 2. This results in an enlarged first compartment containing 3 agitators instead of 2. Therefore the compartment 1 oxygen demand is supplied through 3 agitators, which lowers the P/V per agitator. The reduction in the number of autoclave compartments raises the potential for short-circuiting the mean flow pattern by slurry particles. Short-circuiting and low velocity zones could result in a lower recovery of metal and localized hot spots, respectively. A computational fluid dynamic (CFD) analysis was conducted to quantify these concerns and also to evaluate further design considerations. The results indicate that the proposed design change to 4 compartments affects short-circuiting. The impact of increased short-circuiting on the overall autoclave recoveries is not quantified, however; it is expected to be negligible based on testwork done in the Tati Demonstration Plant and similar modifications made to another operating autoclave. The CFD analysis also suggests that there will be no low velocity zones within the compartment.

Jan 1, 2009

By M. B. Algeo

Discussion of the above paper M. B. ALGEO The management and staff of Buffelsfontein Gold Mining Company Limited are to be congratulated on the excellent performances described in the paper presented by Mr Christos. In this day and age, with the current economic and labour situation, the mining industry is being constantly pressed to increase the productivity of ever-diminishing quanta of resources. Stress in rock The ISRM Symposium, 1976 is to be held in Sydney from 9th to 13th August, 1976. It is being organized by The Australian Geo. mechanics Society as a regional symposium of the International Society for Rock Mechanics. Thermal analysis The First European Symposium on Thermal Analysis will be held at the University of Salford on 20th to 24th September, 1976.

Jan 12, 1975

By X. Zhang, Z. T. Yuan, C. Zhang, H. M. Zheng, X. M. Wang, L. X. Li, N. Li

In metal mines, comminution is commonly used to liberate minerals for subsequent mineral concentration processes, such as flotation, magnetic separation and gravity separation. However, ores are aggregates of valuable minerals and their disseminated gangue minerals, and these minerals exhibit diverse comminution behaviours. In carbonate-bearing iron ores, hematite, siderite, and quartz are the predominant minerals, of which hematite is the objective recoverable mineral. In this regard, the present study aimed to identify the imperfections in siderite minerals by X-ray computed tomography (XCT), and thus quantitatively characterise their size and shape in terms of Feret diameter and aspect ratio, as well as other parameters. XCT images indicated the protogenetic ubiquity of pores <5 μm in diameter and cracks of 7-8 μm inside siderite particles. In the ground product of artificially mixed siderite and hematite, siderite particles were smaller than hematite particles. Siderite particles had a larger surface area and greater surface roughness than hematite particles of the same volume, which was attributable to the intrinsic holes and cracks in siderite particles. This study provides an insight into the relationship between the inherent imperfections of minerals and their comminution properties. Keywords: Siderite; X-ray computed tomography; particle imperfections; grinding behaviour; sliming

Jan 1, 2020

By B. M. V. Baloyi, D. Mchabe, D. Chetty

South Africa accounts for the largest global manganese ore production share, primarily from its Kalahari Manganese Field deposit. Despite this, domestic smelting is beset by energy constraints, resulting in most ore being exported for smelting. Mintek is investigating energyefficient pathways for ore reduction, specifically undertaking prereduction tests to reduce energy consumption for manganese smelting. The present contribution considers the effect of methane, anthracite, and holding time, at a fixed temperature, on the extent of reduction of Mamatwan-type ore, primarily from a mineralogical perspective. In particular, the aim was to carburise the monoxide Mn phase to Mn carbide, as this is less energy intensive than producing metallic Mn from the monoxide. Based on thermogravimetric test results, the ore and products from three experiment sets were analysed using X-ray diffraction and scanning electron microscopy to assess the phases and textures present. The findings show that carburisation of manganese monoxide and its equivalents is most advanced under conditions of 8% anthracite, 10% methane, and 60 minutes of holding time, thus confirming with the thermogravimetric data. These results show promise for reducing energy consumption for Mn smelting in ferromanganese production.

Mar 4, 2025

By J .. F. Brownrigg

In the mining method used at O&apos;Okiep Copper Company (OCC), vertical crater retreat, the prime requirement for the fill is that it should be sufficiently strong to be free-standing to a height of 150 m. Other requirements are minimal decant and drainage water, and high pulp density to allow large tonnages to be placed quickly and alleviate transport problems. The excessively high cost of cement precluded the use of a cement-based fill, and after three years of extensive investigations a backfill based on the smelter slag was produced. Currently a fill with a uniaxial compressive strength of greater than 1 000 kPa after one month is being produced. This is in excess of the design specification of 850 kPa after 2 - 3 months. The research and development which went into the slagfill is briefly covered; the production of the fill from the various raw materials is described; and the design and control systems of the backfill plant, the reticulation system and its monitoring are examined. Finally, the implications of this high- quality fill for the mining programme are assessed.

Jan 1, 1988

By N. Steven

Published parameters from the Mufulira copper in situ leach (ISL) in Zambia are used for order-of-magnitude flow-rate calculations for an envisaged gold ISL in back-filled Witwatersrand stopes. A successful leach operation requires that the porous medium, usually a sand, has a hydraulic conductivity in excess of 5 x10-7m/second (i.e. a permeability >50 millidarcies).Empirical evidence suggests that average linear velocities would be of the order of 60 m/day if the backfill has the grain size of a fine sand. The proposed gold lixiviant would probably be an alkaline or ammonium thiosulphate, not cyanide. The resultant sulphate-rich ground and drainage waters could probably be processed using existing purification techniques to produce gypsum and magnesium/calcium carbonate. Within the next 100 years it is inevitable that solution mining will find widespread application on the Witwatersrand, if not for gold extraction, then certainly for water remediation purposes.

Jan 1, 2009

By T. V. Owen

This paper describes the flotation of cassiterite from fine slimes at Rooiberg Tin Limited, and gives an of the Amdel on-line analysis system that was instaled in 1984 to aid in the control of the concentrate The system, which is easy to install and maintain, and which uses X-ray-fluorescence analysis, has improved control, and therefore a better recovery of tin.

Jan 1, 1988

By C. Liu, F. Ye

"To extend the variety of lump ores that are used in the COREX shaft furnace and to optimize iron ore blending, the original evaluation method for iron ores that was proposed by Voestalpine AG has been improved. Physicochemical and metallurgical properties of iron ores, including Sishen lump ore and CVRD pellets, which are currently used in the COREX process, and three other lump ores, were assessed and compared. Ore matching principles were proposed and five optimized iron ore blending schemes designed and verified by laboratory experiments to prove the effectiveness of the improved evaluation method. The replacement of Sishen lump ore by the alternative L2 and L3 lump ores without varying the proportion of CVRD pellets could improve the degree of reduction and rate of metallization, and decrease the bonding index. Based on the results of laboratory test work and industrial- trials, an ore blending scheme of 60% CVRD, 20% L2, and 20% L3 is recommended for use in the COREX process. IntroductionIn recent years, problems such as environmental pollution and a shortage of coke and coal resources for blast-furnace ironmaking have become increasingly apparent. Based on sustainable developments in the iron- and steelmaking industries, the environmentally friendly COREX smelting-reduction process with low energy consumption was developed and introduced (Zhou and Du, 2013; Song, Lv, and Yin, 2015; Xu et al., 2016; Kurunov, 2010). The evaluation system for lump ore that was proposed by Voestalpine AG recommends that only Sishen lump ore from South Africa be used in the COREX process, because of the stringent physicochemical and metallurgical property requirements. This situation significantly hampers improvements to the technical and economic aspects of the COREX ironmaking process, especially in China (Eberle, Siuka, and Bohm, 2006). No theoretical or technical basis has been provided for the evaluation system, and the assessment approach for iron ores also presents problems that need to be discussed and resolved.The COREX process consists of two reactors: the prereduction shaft furnace and the melting gasifier as shown in Figure 1 (Wu et al., 2017). Pellets and lump ores which are charged to the prereduction shaft should have a good reducibility and metallization with a low degradation index (Li et al., 2016; Wu et al., 2011; Kumar et al., 2009; Kang, Gupta, and Sahajwalla, 2007). The properties and microstructure of the iron ore pellets which are required to achieve a high productivity and a lower fuel rate in the COREX process have been investigated (Umadevi et al., 2011). Some efforts have also been made to investigate the behaviour of lump ores in the COREX shaft furnace, including the disintegration characteristics and the reduction degradation (Umadevi et al., 2011; Zhou et al., 2015; Xu et al., 2013; Li, Feng, and Zou, 2013; Hou et al., 2014). However, few studies have focused on the optimization of ore blending for partial or total substitution of the expensive Sishen lump ore by other, cheaper lump ores to reduce the production cost. The technology for the utilization of blended lump ores in the COREX process is still in its early development stages (Zhou et al., 2017; You et al., 2017)."

May 1, 2019

1. Book reviews Stainless Steels &apos;84. London, Institute of Metals, 1985. £39 (U.K.), US$62 (elsewhere) Reviewer: J.B. Oalton Process engineering of size reduction: bal miling, by LG. Austin, R.R. Klimpel, andP.T. Luckie. New York, AIME, 1984. 561 pp. Reviewer: M.J. Lazer 2. Recent publications Hard and superhard materials. New York, Worltech Report Inc. (44 Woodbine Avenue, P.O. Box 212, Northport, 11768 U.S.A.), 1985. 270 pp. $1500.International comparison of standard materials-steel and cast iron, compiled by W. Oto and K. Schaning, and edited by DIN German Standards Institute e.V. Berlin, Beuth Verlag GmbH, 1985. 3rd edition, 416 pp. DM 158. Tin and its uses no. 146. Greenford (England), International Tin Research Institute, 1985. Write your own CV, by Max Kowen. Johannesburg, Legal Personnel Selections (404 Medical Centre, Cor Jeppe and Delvers Sts, Johannesburg 2001), Nov. 1985. 40 pp. R12,50 + GST.

Jan 1, 1986

1. Book review Assay and analytical practice in the South African mining industry, byW.C. Lenahan and R. de L. Muray- Smith. Johannesburg, The South African Institute of Mining and Metalurgy, 1986. RlOO (R80 to Members). Reviewer: N.G. Randolph 2. Canadian publications A market profile for industrial minerals in Canadian manufacturing sectors, by M. Prud&apos;homme and D. Francis. 1987. Micromedia Limited (144 Front Street, Toronto, M5J 1G2, Canada).The following three publications are available from the Centre for Resource Studies, Queen&apos;s University, Kingston, Ontario, Canada K7L 3N6. An analysis of Japanese coking coal procurement policies: The Canadian and Australian experience, by D.L. Anderson. Feb. 1987. $25. Technology policies in the Canadian mineral industry, edited by M.J. Wojciechowski. Sep. 1986. $20.Value-added taxation: Issues and impact for Canadian mines, by B.l. Dyack. Nov. 1986. $7.3. Mintek reports Report M295 A mineralogical investigation of refractory gold ores and their beneficiation, by P.M. Swash. Report M296 The determination, by distilation-spectrophotometry, of chlorine in apatite-type materials containing fluorine, by M. Solomons. Report M297 The interference of zirconium in atomic-emission spectroscopy using inductively coupled plasma, by P.l. Wright.

Jan 1, 1987

By S R Grano

A fundamental model, which considers the subprocesses of particle collection by bubbles in flotation, is applied to two comprehensive flotation surveys in the rougher stages of C3 concentrator, PT Freeport Indonesia. The flotation surveys focused on the collection of: ? cell-by-cell and size-by-size metallurgical, ? cell hydrodynamic, and ? pulp and surface chemistry information. The two surveys were conducted at significantly different feed tonnages, giving rise to significantly different feed particle size distributions, pulp densities and mean pulp residence times. A series of model simulations are performed with the aim of quantifying changes in copper recovery, on both a size-by-size and unsized basis, with changes in values of the hydrodynamic parameters and hydrophobicity of the copper sulfide mineral. This was carried out in an effort to identify the most promising route to increase overall copper recovery in roughing. It was found that by increasing the hydrophobicity of the copper sulfide mineral surfaces it became possible to optimise cell hydrodynamics, which targeted increased fine (-12 µm) copper sulfide mineral recovery but without adversely affecting coarse (+150 µm) copper sulfide mineral recovery.

Jan 1, 2007

By C. Snyman, M. Le Roux, Q. P. Campbell, S. Engelbrecht

Due to the ultrafine particle size required for effective processing of chromite ores, dewatering of the concentrates presents a challenge. It is not uncommon for the ore to have elevated moisture contents even after dewatering, which must be reduced to required levels of between 8% and 10% by mass for further processing. Contact sorption drying has shown promise in test work on fine coal. This method was used to study the dewatering of chromite on a laboratory scale using 3 mm spherical activated alumina ceramic beads as a sorbent. Three different sorbent-to-chromite mass ratios, namely 0.5:1, 1:1, and 2:1, were tested with different process conditions, including dewatering in a stationary and a rotatingl bed. The experimental work showed that it was possible to achieve the target moistures in less than 10 minutes, irrespective of the sorbent-to-chromite ratio used. Ratios of 1:1 or higher, however, proved to be the best. The sorbent reusability at mass ratios of 1:1 and 2:1 were therefore tested. With a 1:1 mass ratio, the sorbents could be reused for three cycles, while with 2:1 ratio, the number of cycles increased to six. The sorbent-to-chromite mass ratio used had a significant influence on the required contact time and the reusability of the sorbents.

Oct 3, 2023

By M. Arlandi-Rodríguez, and A. García-Berrocal, A. Alonso-Jiménez, C. Lopez-Jimeno

Spain is a major producer of dimension stone, which is one of the most important industrial sectors in the northwest of Spain. This justifies the maintenance of these industries, although the technical and environmental requirements for their continuity are increasingly demanding. The main target of this paper is to present a new methodology in order to obtain k-ratio stress values on the basis of flat jack measurements and finite element numerical back- analysis with Rocscience© RS2 software. Continuous iterations were performed to try to find a relationship between the k₀ and the measured stress in the tunnel roof and sidewalls. It focuses on technical aspects of the method for designing mine chambers in the slate industry that were previously mined by open pit methods. The size of the chambers impacts the operating cost, and the dimensioning of a correct support ensures better efficiency and safety. Correct knowledge of the k₀ therefore is critical for the design of the support. The proposed new method entails a simplification of the classical procedure for estimating the k-ratio.

Sep 1, 2022

By M. S. Janssen, J. L. Taylor, M. A. Ford, E. B. Viljoen, H. A. Simonsen

The Stilfontein and Buffelsfontein Gold Mines, near Klerksdorp in the Transvaal, had accumulated a large amount of uranium-containing residue and, when the price of uranium rose in the 1970s, consideration was given to the possible recovery of this uranium. Preliminary tests showed that concentration of the uranium prior to leaching would not be economic. However, the pyrite in the residue could be concentrated by flotation, and the flotation concentrate could be roasted to pro¬vide both enough acid for leaching the uranium and a calcine from which the gold could be recovered. The feasibility study showed that a uranium operation of 270 kt per month would be most economically attrac¬tive, and a plant of that size was accordingly designed and built. In the first six years of its existence, the plant treated over 20 Mt of residue and produced about 3,5 kt of uranium oxide. During that time, the plant was con¬tinually being improved to make it more reliable and cost-efficient. This paper analyses the operation of the plant during its first six years from the viewpoints of its mechanical, process, and economic performance. The criteria on which the selection of the process was based are reviewed and compared with the actual performance of the plant, emphasis being placed on the leaching, solid-liquid separation, recovery, and purification stages.

Jan 1, 1987

By A. C. Wingrove

The paper outlines the selection of a dewatered tailings backfill system for the Johannesburg Consolidated Investment Gold Division, and covers the following aspects: (i) 16 Shaft pilot testwork; (ii) engineering design problems relating to the Cooke 3 Shaft backfill operation; (iii) in-line mixing - applications with respect to the Randfontein Estates Gold Mine and Western Areas Gold Mine backfill operations; and (iv) pipeline friction losses.

Jan 1, 1988

This paper details the preliminary design work carried out before and during the implementation of an extensive backfilling programme on Cooke 3 Shaft, Randfontein Estates Gold Mining Company (Witwatersrand) Limited. The design work is of relevance to any system utilizing a cementitious binder, and the quality control aspects are of particular significance. Problems associated with correlating laboratory results to actual field results are also briefly discussed.

Jan 1, 1988

By J. Uys, P. J. Mokganya, J. Olwagen, R. C. W. Webber-Youngman

This article discusses the critical role of leadership in the technology adoption process within organizations, particularly in industries like mining, where innovation is essential for maintaining competitiveness and operational efficiency. It highlights the limitations of traditional technology adoption models, such as the Technology Acceptance Model (TAM), Diffusion of Innovations (DOI), and Unified Theory of Acceptance and Use of Technology (UTAUT), which focus on individual factors and overlook the strategic and organizational roles of leadership. The study proposes the Ambidextrous Leadership-Technology Adoption (ALTA) model, which integrates leadership styles such as transformational, transactional, adaptive, and ambidextrous leadership into the technology adoption process. The model emphasizes the balance between exploration (fostering innovation) and exploitation (ensuring operational efficiency). The findings suggest that transformational leadership fosters innovation by encouraging risk-taking and creativity, while transactional leadership ensures efficient technology integration. The article also identifies key barriers to technology adoption, such as organizational resistance to change, which can be mitigated through adaptive leadership that addresses employee concerns. The research emphasizes the importance of a supportive organizational culture and cross-functional collaboration, which are essential for successful technology adoption. The study concludes by offering practical recommendations for leaders to foster a culture of innovation, manage resistance, and balance short-term efficiency with long-term technological advancement.

Nov 27, 2024