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By M. Izadi Yazdan-Abadi, S. H. Amiri, M. Ramezanizadeh, M. Bazmandeh

Iron ore concentrate is used as the fresh feed of pelletising plants. The green pellet properties depend on iron concentrate characteristics such as particle size distribution (PSD), specific surface area (Blaine value), iron grade, moisture content and grinding methods. The grinding methods affects particle size distribution and Blaine value. To find out the effects of grinding methods on pelletising process, green pellets were produced with concentrates that were reground by means of HPGR (high pressure grinding rolls) and ball mill. The Blaine values of ground concentrates in both types of milling were approximately 1400, 1600 and 1800 cm2/gr. The results of green pelletising tests on a pilot plant scale showed that at the same Blaine values, drop numbers of green pellets produced by ground concentrate inside HPGR were higher than the green pellets produced by ground concentrate inside a ball mill. Also, reground concentrates by means of HPGR, in comparison with ball mill, caused the production of green pellets, at higher wet and dry compression strengths. As a result, it was found that preparing the pelletising feed by means of HPGR led to more positive effects on the properties of green pellets. Keywords: Ball mill, HPGR, green pellet, drop number, wet and dry compression strengths

Jan 1, 2020

COUNCIL The following served on Council during the year under review: Office bearers: Messrs V. C. Robinson (President), Prof D. D. Howat and Dr J. P. Hugo (Vice-Presidents), J. K. E. Douglas (Immediate Past President) and D. G. Maxwell (Honorary Treasurer). Ordinary Members of Council: Dr M. G. Atmore, Dr J. M. Bereza, H. P. Carlisle, W. W. Malan, C. E. Mavrocordatos, Prof R. P. Plewman, Dr R. E. Robinson, Dr M. D. G. Salamon, P. W. J. van Rensburg, L. W. P. van den Bosch, P. A. von Wielligh. Branch Chairmen: J. Meintjes, J. M. Meyer (Acting), J. N. Saunders (Retired). Past Presidents serving on Council: R. J. Adamson, M. Barcza, H. Britten, R. C. J. Goode, P. Lambooy, Prof J. de V. Lambrechts, Dr J. T. Mclntyre, J. F. Reid, H. Simon. Ten Council meetings were held during the year with an average attendance of eighteen and the standing committees held forty-six meetings. FINANCE The annual accounts, which are attached to this report, show an excess of income over expenditure of R5 051 compared with an excess of expenditure over income last year of R4 608. This major reversal of fortunes is due in the first instance, of course, to the increased subscriptions. There were, however, other important contributors, particularly sales of the Proceedings of the Symposium on Open Pit Mining and profits on the operation of symposia and colloquia. It would appear from a study of the accounts that there has been a substantial drop in expenditure on secretarial fees. In actual fact, however, our total expenditure on secretarial fees was higher. A portion of this expenditure was charged against the administration of the Symposium on Open Pit Mining and, in addition, the charge against the Journal accounts for secretarial fees was increased. It will be recalled that in last year's annual report it was mentioned that subsequent to the new arrangement for publication of the Journal, the expected improvement in the finances of the Journal had been slow in materialising. After a total period of 18 months there was still no sign of improvement and it was accordingly decided to end the arrangement. As a result, the drain on the finances of the Institute was considerably lessened in the second half of the year. During the course of the year Council became concerned about the rapid depletion of our accumulated funds and gave careful and detailed attention to all aspects of the Institute's financial affairs. Particular attention was given to: 1. The fact that the Institute does not have a solid financial backing and must appeal for funds every time any special event such as a symposium is held. 2. The responsibilities of the Institute to the profession and the community, with particular reference to the desirability of establishing Institute bursaries and participating in other educational activities. 3. The rapidly rising cost of living. 4. The immediate financial position of the Institute. 5. The rapidly increasing cost of publishing the Journal due to the increasing number of papers available. In the meantime the immediate financial position of the Institute has improved but as this is due largely to non-recurring or irregular items of revenue, it should not be given undue weight. After careful consideration it was decided that an appeal should be made to industry for financial assistance, which would be used to cover the cost of symposia and other unusual expenditure and also, if possible, to build up the capital resources of the Institute so that there is a solid foundation for the future. Before appealing to industry, Council wished to be quite certain that there could be no criticism of the Institute for not having done our best in a personal capacity. Furthermore, Council examined many comparative statistics, including those circulated to members, which showed that, while expenditure per member has risen at an average annual rate of 7,5% over the last fifteen years, subscription revenue per member has risen at only 3,4% per annum. It was with this background that your Council decided to raise the subscriptions. Initial approaches have been made to the big mining groups and there has been a very generous response, although the details of how financial assistance will be provided have not yet been worked out. It seems likely that some form of affiliated company membership will be the most suitable method of achieving this. When these details have been fixed, it is the intention to extend the appeal to all corners of the mining industry as well as manufacturing and metallurgical industries. It is believed that these measures will ensure that the finances of the Institute are placed on a firm foundation on which the expanding activities can be planned. The MacArthur Forrest Memorial Fund shows an excess of income over expenditure of R73 and the total fund was, therefore, increased by this amount to R4 411. The balance sheet shows that the market value of quoted shares and debentures increased during the year fron R6 540 to R9 160. The market value is now almost exactly the same as the book value. Accumulated funds now amount to R23 010 compared with R17 959 a year ago.

By I. Mc Dougall

Water-cooled copper tap-hole blocks provide an effective means of extending the life of tap-hole refractories, as the lower temperature of the refractory material inhibits wear and other damage and promotes the formation of a protective frozen slag layer. This is particularly beneficial during prolonged tapping cycles. The copper block forms an integral part of the lining, and provides mechanical support to the refractory, facilitating rapid replacement of tapping channel bricks without disturbing the surrounding lining. Safety considerations are an important design factor, and the positioning of the water channels is optimized to prevent leaks although the copper is not in direct contact with the molten fluids during normal operation. Water-cooled copper blocks designed by Tenova Pyromet have successfully been utilized on metal, matte, and slag tap-holes for a number of processes, including nickel, platinum group metals, and mineral wool.

Jan 1, 2014

By Anders Erlandsson

"The crude ores from the LKAB mines are sorted and refined into a number of products. As there are a number of different plants the flow of material is often complex.in connection with studies of a proposed extensive investment program it was necessary to get a good measure of the changes which would be caused in the total profit by the different possible investments. A linear programming model was set up to accomplish this, and to cover the consequential effects on the production system. The objective function of the model maximized the total profit, taking into account restrictions in materials balances, blending conditions, production capacities and market. The changes in total profit resulting from the different investment alternatives, together with investment and fixed costs, were used in a series of investment analyses. The application has proved to be very successful and the results come very near to what was expected."

Jan 1, 2014

By A. G. Royle

The reasons for constructing a model of an orebody for which both the parent population and the sampling distribution are known are discussed and details of the model are given. A brief summary of Matheron's theory of regionalized variables is included, with particular reference to his kriging estimators and their variances. Using the model, a comparison is then made between these kriging estimators and other commonly-used estimators. These are compared to find the one with the minimum variance, and an analysis is included to investigate whether any of the estimators is biased. Also included is a comparison between theoretical and experimental variances for some of the estimators.

Jan 1, 2014

By A. Golder, I. Roy

The Jayant opencast operation is one of the largest opencast coal mines in India. Prior to 2008 the mine experienced a number of dragline dump failures, which was a major hindrance in sustaining production. Northern Coalfields Limited (NCL) and the mine management engaged several design, research, and academic institutions to carry out dump slope stability studies, particularly of dragline dumps. BirlaInstitute of Technology prepared a report on the investigations in May 2009. In this paper we review the findings of the report and the measures taken to tackle the safety aspects of dragline dumps.

Jan 2, 2022

By Y. Yang, M. Zhang, X. Xia, S Shi, Z. Shen

A stepwise arrangement of flotation cells is the most common layout of a flotation circuit in the mineral processing industry. In such a design, slurry flows from upstream to downstream by means of gravity, and the middling products are returned to previous stages by pumps. This paper will introduce an alternative solution in which the forced-air and slurry-induced flotation cells are adopted so that all the flotation cells can be placed on the same horizontal platform and no pumps will be needed for middling product transferring. The technology of the forced-air and slurry-induced flotation cell will be described in detail, including unique features, the working principle and the related fundamental problems. The comparison of capital investment, operating cost and metallurgical performance will be made between the conventional stepwise arrangement and the samelevel arrangement technology based on industrial practice. Keywords: Forced-air and slurry-induced flotation cell, same-level arrangement, stepwise

Jan 1, 2020

By S. Kauvosaari, M. Olofsson, O. Haavisto, M. Kosonen, J. Martikainen

The target in grinding circuit operation is usually to maximise the throughput and energy efficiency while keeping the product particle size on an optimal level for downstream operations. Furthermore, feed ore variations in size and hardness need to be compensated in order to stabilise the process. This is a challenging task for any circuit and requires good instrumentation, combined with careful control design. This study investigates the control of a two-stage iron ore grinding circuit with an AG and pebble mill at LKAB Kiruna KA3 concentrator in northern Sweden. A new control approach based on multivariable model predictive control (MPC) is designed, implemented and evaluated for the circuit. Additionally, advanced instrumentation including a volumetric charge measurement for grinding mills is utilised. The MPC control approach starts with step tests that are used to model the effect of manipulated variables (MVs) like feed rate, water addition and primary mill speed on controlled variables (CVs) such as final product particle size, power consumption and volumetric charge of the mills. In the control implementation phase, the models are then utilissed together with current process measurements and known operating limits to predict optimal future changes for the manipulated variables in order to reach the desired process output values. It is shown that the new control approach improves the stability of the circuit and reduces energy consumption. Keywords: Model predictive control, grinding, optimisation

Jan 1, 2020

By Huanhuan SU, Jianqiang Zhang, Zhongyuan Liu, Junwei Ma

The high-sulfur bauxite in Henan Province was used as raw material. The grinding fineness, pH value and collector dosage on its desulfurization performance, and industrial flotation desulfurization process were studied. The best flotation desulfurization conditions were grinding fineness of 75%, pH of 8.5, and collector of 600 g/t. “One coarse, one cleaning and one sweep” closed-circuit flotation was established as the industrial flotation desulfurization process. After the closed circuit test, the sulfur content of aluminum concentrate with the yield of 93% was 0.23%, and the sulfur removal rate was 83.16%, and the sulfur content of tailings (sulfur concentrate) was 15.09%. Keywords：High-sulfur bauxite under coal mines, flotation, desulfurization

Jan 1, 2020

By V. Sheikhzadeh, M. R. Sheikhzadeh, A. Haratian, M. Zare

High Pressure Grinding Roll (HPGR) as an efficient grinding technology plays a major role in mineral processing plants. Investigating the effects of this technology on different parts of mineral processing circuits reveals this technology’s capability. In this paper, HPGR grinding effects on an iron ore beneficiation circuit, in comparison with conventional crushing systems were studied. A representative feed sample was taken from an iron ore beneficiation plant, then crushed to minus 6 mm in a laboratory by two methods: HPGR and cone crusher, and finally a concentrate plant circuit was simulated. Plant simulation was performed by doing laboratory tests consisting of grinding, magnetic separation, flotation and filtration on HPGR and cone crusher products, respectively. According to comminution tests results, in particle sizes smaller than 6 mm, a cone crusher product is coarser than an HPGR product. Also, the Bond ball mill work index of the HPGR product was 10% less than the crusher product. Therefore, based on the Bond formula in applying HPGR, ball mill power consumption decreased by 12%. After ball milling to minus 100 microns, magnetic separation tests results showed that the recovery of the cone crusher circuit output was 90.8% and the product Fe grade was 66.4%. For the HPGR circuit these figures were 87.6% and 67.3%, respectively. Therefore, by using an HPGR, a higher Fe grade of the final concentrate was achieved. A flotation test was then performed on the magnetic separation concentrate, where the results showed that the crusher circuit recovery and the sulfur grade of the product were 96.5% and 0.192%, respectively; whereas the HPGR circuit recovery was 97.2% with a sulfur content of 0.185%. Findings revealed that flotation performance in the HPGR circuit was more efficient than the crusher circuit. Vacuum filtration tests on concentrate produced through the HPGR circuit resulted in a moisture content of 12% that was 2% higher than the crusher circuit’s concentrate in the same condition. Keywords: High pressure grinding roll, power consumption, magnetic separation, flotation, filtration

Jan 1, 2020

By M. Mbonami, R. Pretorius, J. Miller, P. Kyony, B. Nel, N. Mautsa

Challenges due to the formation of stable froth in acid leach systems is common at many copper and Ccbalt producers. Stable froth affects downstream process, critical equipment, and operational parameters. In severe cases the froth present safety and environmental risks and increased operational costs. Solids reports in the pregnant leach solution, accumulates, and clogs launders resulting in a potential costly safety and environmental risk. Solvent extraction is operationally affected by crud formation, organic solvent and extractant losses, reduced mass transfer due to the solids carried downstream. This article reviews the generally inadequate mechanical and hydraulic solutions of froth elimination employed over the years. The recent introduction of a chemically based solution able to eliminate froth problems that can potentially turn around the situation for those who adopt the technology.

Jan 1, 2023

By P. O. Osifo, K. Premlall, X. Goso, R. H. Matjie, M. R. Mulaudzi, J. R. Bunt, K. Mphahlele

This study investigates the transformation of pyrolytic spent tyre-derived char and crumb rubber into high-performance activated carbon chars for industrial wastewater remediation. Utilising an in-house macro-thermogravimetric analysis system under an argon atmosphere, spent tyre-derived activated carbon char were synthesised via physical temperature activation and aqua regia demineralisation. Comprehensive characterisation using x-ray diffraction, Raman spectroscopy, and scanning electron microscopy, revealed a predominantly amorphous structure with nanoscale crystallites (~1 nm) and active surface functional groups. Proximate analysis confirmed that both crumb rubber and leached tyre crumb rubber with aqua regia derivatives achieved favourable compositions (ash ≈ 9.6%; fixed carbon ≈ 84%), comparable to commercial activated carbon (AC). At an optimal activation temperature of 850°C, the char of tyre crumb leached with aqua regia variant exhibited a significant surface area of 300 m²/g. Crucially, the tyre crumb char produced at 850°C variant developed a pore volume of 0.8 cm³/g—effectively doubling that of commercial activated carbon (0.4 cm³/g)—facilitating the sequestration of large organic molecules. In application tests using high-strength starch wastewater, char of tyre crumb leached with aqua regia and tyre crumb char, both produced at 850°C, achieved total organic carbon removal efficiencies of 60% and 50%, respectively, bridging the performance gap between waste-derived and commercial adsorbents. These findings validate waste tyres as a viable, low-cost precursor for industrial-grade adsorbents, offering a sustainable circular economy route for tyre valorisation and reduced industrial disposal costs. Future research will focus on kinetic modelling and the recovery of zinc from spent tyre-derived activated carbon char residues.

Mar 30, 2026

1. Book reviews ? Second International Conference on Hydrocyclones. Cranfield (Bedford, MK43 OAT, England), BHRA Fluid Engineering Centre, 1984. £33. Reviewer: R.P. King This volume contains the 28 papers presented at the Second International Conference on Hydrocyclones, which was held in Bath (England) in September 1984. The format and presentation of the papers are similar to those of the first volume in the series, and this volume con¬tinues the series as an authoritative account of much of the research work associated with hydrocyclones that is being undertaken throughout the world. The volume was produced from camera-ready copy supplied by the authors, but the quality of reproduction is very high and both text and figures are legible throughout the volume. Although most of the work reported deals with the hydrocyclone as a classification device, important sections are devoted to liquid-liquid separations and heavy¬medium separations.

Jan 1, 1985

By R. H. Steel

Ingot casting and wire drawing In Iron Age Southern Africa by R. H. STEEL (Visitor) This paper describes the experiments that were conducted in 1974/1975 on two related aspects of Iron Age copper technology in Southern Africa: ingot casting and wire drawing. Three types of ingot were successfully cast: the St Andrew's Cross ingot, the marale ingot, and the musuku. It is suggested that the 'studs' on the musuku are not the remains of broken-off rods as previously proposed by other investigators, but that the ridged pattern is an ornamental feature. Copper wire was successfully drawn with similar tools and according to the procedures described in the literature on African Iron Age wire drawing. It is concluded that these accounts are generally accurate and that the pre-European metal workers are worthy of respect for the results they achieved with primitive methods.

Jan 11, 1975

By L. A. Vermeulen

A simple argument shows that it is impossible for the flight of a rod in contact with a litter bar in a rotary mill to be initiated at that point on the upside of mill rotation when all the forces acting on the rod are in equilibrium. The argument was confirmed experimentally in a study showing that the lift of litter bars is a function of their height, that the rod velocity at the point of departure has a significant radial component, and that the subsequent flight of a rod is along a parabolic trajectory as predicted by elementary mechanics. A quantitative account of the observed effects, which is based on a dynamic theory of the sliding interaction between rods and litter bars, revealed interesting properties of the motions of rods down the surfaces of litter bars when the latter are in uniform circular motion during the rotation of a mill.

Jan 1, 1985

By K. R. Vost

Most theoretical methods for the prediction of air-temperature gradients in underground airways always assume that the temperature of the entering air either remains constant or has only a slow seasonal variation. Large changes of temperature, caused by variations in atmospheric conditions on the surface, were measured in a fourteen-day period in air entering a horizontal airway. The changes in wet-bulb temperature were damped along the airway less uniformly than the dry-bulb changes; significant variations occurred in the wet-bulb temperature of the air leaving the airway. The damping was .associated with large variations in air-temperature gradients. Other causes of rapid changes In temperature are discussed. These changes must be taken into account in predictions of the frequency with which undesirable conditions can be exceeded at critical points in the ventilation circuit of a mine to allow proper planning of ventilation and refrigeration requirements.

Jan 1, 1977

By J. M. Stewart

Although the incidence of heat stroke in South African gold mines is small, work continues on its reduction. This paper proposes limits of heat stress that are applicable to South African underground conditions, with the warning that they should not be extrapolated to other situations without careful consideration having first been given to their limitations. These limits of heat stress take physical and physiological considerations into account, and they correspond to there being a 10-6 risk of an essentially nude man developing a rectal temperature in excess of 40°C. It is recommended that further work should be undertaken on the development of equations for the calculation of the heat transfer from clothed men, the derivation of equations that quantify the physiological conductance and sweat rate response of humans, and on establishing the frequency distributions that describe variations in rectal temperature response between individuals in different types of environment.

Jan 1, 1981

By L. Marais

The development of a post-mining economy is generally framed as accessible and desirable and something that mining companies, consultants, and the government can, and should, plan for. It is indeed possible. Yet, most mining regions, other than the big metropolitan municipalities, find economic diversification after mining challenging, despite their grand plans, consultant reports, and company intentions. Their efforts blind them to other ideas that are often prerequisites to diversification. This paper highlights some economic and social misconceptions about economic diversification and explains where planning goes wrong. Mistakes typically stem from ignorance and misunderstandings. Planners and policy makers fail to grasp the essential requirements for economic diversification. They underestimate the structural constraints created by mining. They do not see how mine rehabilitation is linked to economic diversification. They generally do not understand the South African space economy or the nature of new economies. The paper also proposes a more careful consideration of those economic aspects that mining cities have control over, such as land use management and infrastructure. The paper further explains how understanding long-term dependencies can help prevent governance failures. The social disruption that accompanies mine decline and closure must be recognised and dealt with. The mines must plan for decline as a way to resuscitate the economy. It concludes with a framework for assessing and developing a post-mining economy.

Apr 25, 2025

By K. Barani, S. M. S. Ganji

Creatine was used as a lixiviant for gold dissolution from gold ore. The effects of creatine concentration, temperature, leach time, and pH were examined for their influence on extent of gold dissolution. The results show that at a temperature of 75°C and pH 11.5, gold dissolution increased from 51% to 88% on increasing creatine concentration from 25 to 50 g/t. Further increase in creatine concentration showed a negative effect on the gold dissolution. Gold dissolution increased from 47% to 87% by increasing the temperature from 25°C to 55°C, and from 61% to 89% by increasing pH from 10 to 11.5. Under the optimum conditions of solids’ content of 30%, pH 11.5, creatine concentration of 100 g/t, temperature of 75°C, and hydrogen peroxide addition of 2%, about 90% of the gold could be dissolved from the ore after 24 h. A comparison between creatine and cyanide leaching showed that 90% gold dissolution was achieved at a cyanide concentration of 300 g/t, which is three times higher than the creatine concentration under optimal conditions.

Apr 14, 2024

By Y. G. Zhu, G. B. Zheng, X. X. Hu

Reverse flotation by cationic collectors is the classical method to reduce the silicon content in magnesite. But because of the low selectivity, there is a large loss of magnesite in the reverse flotation froth. To improve the efficiency of the collector, a novel collector named BK433 was developed in this paper. In order to determine the performance of the BK433 collector, a systematic experimental study was carried out with a high silicon magnesite in China. The suitable pH environment of slurry was confirmed, the depression effect of different depressants was investigated, and the flotation effect was compared with commonly used traditional collectors. The results show that the BK433 shows remarkable good selectivity and collection ability. After the 4 stages reverse flotation, the SiO2 content decreased from 3.76% to 0.25%, SiO2 impurity removal rate reached 94.69%. Meanwhile, the MgO content increased from 45.06% to 46.73%，the recovery of obtained concentrate (calculated by MgO) was 82.79%. Keywords: Magnesite, Desilicication, Reverse flotation, Collector

Jan 1, 2020