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By C. Van Rhee

In dredging practice sand is eroded at very high flow velocities using water jets. The existing pick-up functions overestimate erosion. By taking the permeability into account conventional pick-up functions can be made suitable for high velocity erosion. This can be achieved by modifying the critical Shields parameter. The procedure is demonstrated using the pick-up function of Van Rijn. The theory is compared with experiments and agreement is good.

Jan 1, 2007

By B. Matsetela, S. Amos, V. Nkuna

"The Kamoa-Kakula copper project—a joint venture between Ivanhoe Mines, Zijin Mining Group Co. Ltd, and the government of the Democratic Republic of Congo—has been independently ranked as the world's largest undeveloped high-grade copper discovery by international mining consultant Wood Mackenzie. It is a very large, near-surface stratiform copper deposit with adjacent prospective exploration areas within the Central African Copperbelt, approximately 25 km west of the town of Kolwezi and about 270 km west of the provincial capital of Lubumbashi. A phased development approach is currently envisaged. The first phase of the project involves the development of a 6 Mt/a underground mine and surface processing complex (dual stream concentrator) at the Kakula deposit, a discovery announced in early 2016. The second phase involves an integrated 12 Mt/a two-stage development, beginning with initial production from the Kakula mine, to be followed by a subsequent, separate underground mining operation at the nearby Kansoko mine, along with the construction of a smelter. Project description and locationThe Kamoa–Kakula project comprises a newly discovered, very large stratiform copper deposit with adjacent prospective exploration areas, located within the Central African Copperbelt in Lualaba Province, Democratic Republic of Congo (DRC). The Kamoa–Kakula project lies approximately 25 km west of the town of Kolwezi and about 270 km west of Lubumbashi. Ivanhoe owns a 49.5% share interest in Kamoa Holding, an Ivanhoe subsidiary that currently owns 80% of the project. Zijin Mining owns a 49.5% share interest in Kamoa Holding, which it acquired from Ivanhoe in December 2015 for an aggregate cash consideration of US$412 million. The remaining 1% interest in Kamoa Holding is held by privately-owned Crystal River.The Kamoa–Kakula project consists of the Kamoa exploitation licences (exploitation permits 12873, 13025, and 13026, which cover an area of 397.4 km2) and one exploration licence (exploration permit 703 covering an area of 12.74 km2). The Kamoa exploitation licences, approved 20 August 2012, grant Kamoa Copper the right to explore for, develop, and exploit copper and other minerals, for an initial 30-year term, expiring on 19 August 2042. The permits can then be extended for 15-year periods until the end of the mine’s life."

Nov 1, 2018

The Annual General Meeting of the South African Institute of Mining and Metallurgy was held in Kelvin House, Johannesburg, on Wednesday, 19th August, 1981. Dr P. R. Jochens (President) was in the chair and declared the meeting open at 4.05 p.m. This account of the proceedings includes only those matters that are not reported under the heading `Annual report and accounts' elsewhere in this issue. Confirmation of the Minutes The minutes of the last Annual General Meeting, which was held on 27th August, 1980, were confirmed as pub¬lished in the September issue of the Journal. Welcome President: I extend a sincere welcome to you all, especially to the following distinguished guests: Mr L. W. P. van den Bosch, President of the Chamber of Mines, and Mrs van den Bosch; Mr J. G. Kirchner, Government Mining Engineer, and Mrs Kirchner; Dr William Ble¬loch; Dr L. Alberts, President of the National Institute for Metallurgy, and Mrs Alberts; Dr C. F. Habis, Presi¬dent of the CSIR, and Mrs Habis; Dr P. J. Hugo, Chief Director of the Minerals Bureau, and Mrs Hugo; Mr D. N. Stuart, General Manager of the Chamber of Mines, and Mrs. Stuart; the Presidents and representatives of other Institutes and their wives; and Honorary Life Fellows of our Institute and their wives.

Jan 1, 1981

By G. H. Morton

The tenth international symposium on the application of computer methods in the mineral industry (APCOM) was held in Johannesburg in April; the first time it had taken place outside North America. In the technical sessions fifty-seven papers were presented, providing a review of current work and including some important original contributions. These papers and a full account of the discussion at the symposium will soon be published in a single volume. The Technical Programme The first session of the symposium included an opening address given by Mr J. W. Shilling, President of the Chamber of Mines of South Africa, and a keynote address by Mr K. F. Lane of the Rio Tinto Corporation Limited. Mr Shilling spoke about the history of the South African mining industry and about some of the work of the Chamber of Mines. He stressed the importance of the symposium in familiarising those in mining with computer applications, and expressed his hope that it would stimulate and inspire scientists and engineers in the effort to develop safer and more economic methods of mining. Mr Lane, talking about economic and financial modelling, gave a fascinating account of the experience of RTZ over the last twelve years. In a very honest appraisal of the substantial progress that had been made, he confessed some disappointment not only in the cost and

By A. M. Garbers-Craig, T. Coetsee, T. M. Nemavhola

Accretions often form in furnaces when slag and charge materials attach to the refractory wall and build up over time. Accretion formation is usually unwanted because it reduces the working volume of the reactor and hinders material flow through the reactor. However, in some instances a thin, stable accretion layer may be desirable to protect the underlying refractory material. In order to prevent and/or manage accretion formation, it is important to understand the underlying principles of this phenomenon in the particular reactor. Excessive accretion formation hampered production at the Exxaro FerroAlloys ferrosilicon melting and atomization plant. This plant uses induction furnaces in which a 15% silicon-iron alloy is produced by batch smelting a mixture of ferrosilicon of 75%Si grade and low-carbon steel. The molten ferrosilicon alloy is then gas-atomized to a powdered product for use as a dense medium in mineral processing plants. The objective of this study was to investigate the effect of different impurity levels in the ferrosilicon feed material on the extent of accretion formation as well as the effect on the accretion properties, which influence the ease of accretion removal upon furnace shut-down. Refractory and accretion samples were collected after a furnace shut-down and characterized using X-ray diffraction and scanning electron microscopy–energy dispersive spectroscopy. It was concluded that the trace elements in the FeSi-75 feed material (Al, Ca, Mn) were mostly responsible for accretion formation, but that rust on the low-carbon steel and oxidation of the steel contributed to accretion attachment to the lining. The total contaminant content, calcium to aluminium ratio in the FeSi-75 feed material, and thereby the liquid to solids ratio in the accretion at temperature determine the strength of attachment as well as growth of the accretion.

Feb 2, 2021

By B. McFadzean, M. Tadie, T. Dzingai, M. Becker

Ores from a single deposit may exhibit extensive variability in their mineralogy and texture. The ability to quantify this variability and link it to mineral processing performance is one of the primary goals of process mineralogy. This study focuses on the effect of alteration in three platinum group element ore samples from the Great Dyke in Zimbabwe – two of which were more pristine compared to the third, which was locally classified as ‘oxidized’ ore. These ores are known to be characterized by varying degrees of alteration, resulting in numerous challenges in flotation and affecting both grade and recovery. Alteration, by near-surface oxidation, of the valuable base metal sulphides and platinum group minerals resulted in lower flotation recoveries of Cu, Ni, Pt, and Pd. Evidence of incipient oxidation was more readily observed in the base metal sulphide assemblage than the platinum group mineral assemblage, even though the loss in recovery (because of oxidation) was most significant for Pd. Alteration through hydration resulted in a significant increase in mass pull and dilution of concentrate grade through the inadvertent recovery of naturally floating gangue comprising composite orthopyroxene and talc particles. In this study, the amount of naturally floating gangue was more strongly correlated with the talc grain size distribution than the grade of talc in the flotation feed. The oxidation and hydration alteration reactions are not necessarily mutually exclusive, although one may be more dominant than the other, giving rise to ore variability.

Sep 1, 2021

By W. H. Holtzhausen

The purpose of this project was to compare two underground, batch coal haulers ? battery haulers and shuttle cars ? in order to determine the more viable machine to implement. The specific standards for battery haulers were investigated and compared to the requirements of shuttle cars in order to identify the unnecessary expenses related to the legal requirements that are attached to the machines. Costs such as running costs, capital costs, and maintenance costs were researched and compared over a typical life of machine. Average production rates and breakdown times were obtained and used to determine which machine would be more reliable in achieving the required annual production.

Jan 1, 2014

By K. Gharibi, A. Dehghani, S. Farrokhpay, M. Aghajanloo, M. Ostadrahimi

The effect of flotation operational parameters on froth stability and froth recovery was studied. Froth stability was measured using a special column. To determine the froth recovery, the froth height change model and froth height exponential model were used. It was found that since the interactions between the pulp and froth zones affect the time of froth formation, the exponential model is more suitable than the froth height change method for determining the froth recovery. The results showed that superficial air velocity and collector dosage have, respectively, the highest and lowest effect on the froth recovery, while froth recovery decreases sharply with increasing froth height.

Jan 1, 2021

By M. A. Mahboob, T. Celik, B. Genc

Mineral Resources estimation plays a crucial role in the profitability of the future of mining operations. The conventional geostatistical methods used for grade estimation require expertise, understanding and knowledge of the spatial statistics, resource modelling, geology, mining engineering as well as clean validated data to build accurate block models. However, the geostatistical models are sensitive to changes in data and would have to be rebuilt on newly acquired data with different characteristics, which has proved to be a time-consuming process. Machine learning methods have in recent years been proposed as an alternative to the geostatistical methods to alleviate the problems these might suffer from in Mineral Resource estimation. In this paper, a systematic literature review of machine learning methods used in Mineral Resource estimation is presented. This has been conducted on such studies published during the period 1990 to 2019. The types, performances, and capabilities, of several machine learning methods have been evaluated and compared against each other, and against the conventional geostatistical methods. The results, based on 31 research studies, show that the machine learningbased methods have outperformed the conventional grade estimation modelling methods. The review also shows there is active research on applying machine learning to grade estimation from exploration through to exploitation. Further improvements can be expected if advanced machine learning techniques are to be used.

Nov 30, 2022

By Z. Xingrong, L. Jiongtian, Z. Yangge, C. Yijun, L. Liang, H. Yangjia, H. Long

In this present research, a polymer poly (acrylamide-allyl thiourea) (PAM-ATU) with an average molecular weight 1.66 × 104 g/mol was used as a depressant in the flotation separation of molybdenite from chalcopyrite and galena. The micro-flotation experimental results showed that PAM-ATU exhibited a strong influence on the flotation performances of chalcopyrite and galena, but had little effect on that of molybdenite within a pH range of 9.0~11.0 at a dosage of lower than 6.0 mg/L. The flotation results of bulk flotation tests illustrated that PAM-ATU showed a stronger depression power than sodium thioglycollate (TGA) and sodium sulfide. The comparison results demonstrated that PAM-ATU and TGA had an advantage in reducing galena and chalcopyrite impurities in the molybdenum concentrate, respectively. With the combination of PAM-ATU and TGA, a good flotation separation result was achieved through one roughing operation where the recovery of molybdenum in the froth product was over 75.0%, while the recovery of copper and lead were less than 22.0% and 15.0%, individually. It was also found that a molybdenum concentrate with Mo grade of 46.32%, Cu grade of 0.16%, Pb grade of 0.06%, was obtained by a closed circuit flotation flowsheet of one roughing-three scavenging-five cleaning with a Mo recovery of 77.67%. Keywords: PAM-ATU, molybdenite, depressant, chalcopyrite, galena

Jan 1, 2020

By A. J. H. Newell, K. Doherty

A copper-gold project has required a number of trade-off studies underpinned by test work to settle on pragmatic flowsheets and throughputs to support a pre-feasibility study that provides a compelling financial case. The primary trade-off studies were based on the mine schedule, ore type feed-grade recovery relationships, likely concentrate grades and typical marketing terms as well as the estimated capital and operating costs for a range of throughputs and mining strategies. Secondary trade-off studies were conducted for specific circuits and additional processing options. Although the details of these studies are not presented, the technical options and subsequent flowsheets are discussed. While the flowsheets will be optimised during the feasibility study stage, the basis is now fixed for the four ore types that would be mined from the copper-gold orebody. The ore types, resulting from a strong weathering profile, exhibit a wide range of copper mineralisation and gold associations, as well as gangue types. They display a range of characteristics that necessitated a nuanced approach to flowsheet development. The primary separation techniques that have been employed include gravity, classification, flotation and leaching while a range of comminution methods have been selected to suit the properties of the ore types. While technical issues are important factors in terms of maximising the quality of separations, recoveries and revenues, attention to material handling, equipment characteristics, the mine schedule, and capital and operating costs are equally important considerations for settling upon a suitable and robust flowsheet. Keywords: Flowsheet, testwork, studies, saprolite gold, native copper, chalcocite, chalcopyrite

Jan 1, 2020

By T. Marin, J. E. Seccatore, M. Cardu

The most energy-intensive process in the mining industry is particle size reduction – comminution. The first phase of this process is blasting to fragment the rock from the initial Boussinesq’s halfspace size. Scientific literature demonstrates that the output of a blast in terms of fragment size distribution can be manipulated by varying the specific charge (powder factor) and charge distribution. This study focuses on the influence of blasting on the internal resistance of the blasted fragments; in particular the influence of the spatial distribution of charges. Small-scale blasts were performed on 14 marble blocks using different powder factors and charge distributions. Three control blocks were fragmented by mechanical means for comparison. The results show the correlations between charge distributions and the specific energy of mechanical comminution. Opportunities for adjusting charge diameter and distribution in opencast blasts to improve the performancet of comminution circuits are discussed.

Aug 8, 2024

By A. N. Brown

The Eighteenth International Symposium on the Appli¬cation of Computers and Mathematics in the Mineral Industries was held in London from 26th to 30th March, 1984. The Symposium was organized by the Institution of Mining and Metallurgy under the leadership of Mr M.J. Cahalan, Chairman of the Organizing Committee. The venue chosen was the Royal School of Mines, Imperial College of Science and Technology, in South Kensington. Some 300 delegates from all parts of the world attended, which included a delegation from South Africa that numbered about 20 persons. This extremely successful series of international meet¬ings was begun in 1961 in Tucson, Arizona, and has grown in strength and importance over the years. The arrange¬ment of the symposia is regulated by the International Council for APCOM under the Chairmanship of Professor R.V. Ramani (U.S.A.), the other current members being Professor J. Elbrond (Canada), Dr Thys B. Johnson (U.S.A.), Professor Young C. Kim (U.S.A.), Professor D.G. Krige (R.S.A.), Professor A.J. Lynch (Australia), Professor C.T. Shaw (U.K.), Dr A. Weiss (U.S.A.), and Professor F.L. Wilke (F.R.G.). There is no doubt that the enthusiasm and dedication of this small group of people and the excellent working relationship that exists between them are responsible for the continued success of APCOM meetings.

Jan 1, 1984

By D. B. Swanepoel

Hulamin Rolled Products (Ltd) developed a high Mn and Si containing alloy, EN 4017 as a scrap consuming alloy from the waste generated in producing their range of clad products for brazing of inter alia automotive heat exchangers. The multifaceted composition of this alloy (Al -1.2 wt% Si -1.1 wt% Mn -0.2 wt% Mg-0.26 wt% Cu) suggested that it might display some degree of strengthening via precipitate formation of the Mg2 Si-types. The aging isotherms constructed showed that EN 4017 with 0.19% Mg reached a lower peak strength (YS~210 MPa and UTS~260 MPa)compared to the EN 4017 material with 0.43% Mg (YS~270 MPa and UTS~325 MPa). The higher Mg variant of EN 4017 was comparable with the age-hardenable reference alloy EN 6061. Selected area electron diffraction (SAED) studies proved that the microstructure of age hardened EN 4017 contained a combination of ß', ß" and U2 phase after being aged at 175ºC for 65 h. The general microstructure contained precipitate free zones as well as grain boundary Si films, although these did not lead to significant embrittlement. The role of Mn dispersoids in the fracture mechanism of 4017 is also discussed. The article will compare the behaviour of EN 4017 with that EN6061. Keywords: Age-hardening, dispersoids, magnesium silicide, precipitate free zones

Jan 1, 2009

By HORNICKA OSTRAVA

The Czechoslovak Scientific-Technical Institute has arranged the international conference 'Hornicka Ostrava' for four or five days at the end of October, 1969, as part of the preparation for the international 'Miners' Congress' on deep coalextraction in 1970. The keynote of the conference is 'New Techniques in coal mining,' and will be covered by five groups dealing mainly with: 1. New trends in the opening of mines, optimal parameters, projections, equipment, utilization of computers for economic analyses, etc. 2. Increase in efficiency of coal extraction in deep mines, technology, concentration, pressure control, optimization of material and coal transport. 3. Modernization of devices for increased safety and working conditions, new trends in explosives, new techniques for reducing environmental diseases. 4. Innovations in deep level coal extraction, mechanization, rationalization, automation, etc. 5. Other topics about modern techniques in mining. Address your enquiries to: Ing. Karel Kalas (Secretary of the Conference), Dum Techniky Cs YTS, Ostrava 1, Jesenkiho 7-9, Czechoslovakia.

By A. Kijko, C. W. Funk

Methods for the analysis of seismic hazards in mines are reviewed as illustrations of the techniques that are being used in some South African mines. The classical parameters that describe a hazard are the seismic activity rate, ?, the Gutenberg-Richter value, b, and, occasionally, the maximum regional magnitude, mmax The activity rate is calculated readily owing to the inherent simplicity of its definition. The evaluation method presented for the Gutenberg-Richter b value takes into account the presence of mmax Three statistical procedures are described for the assessment of mmax which the maximum observed magnitude, Xmax a crucial role. Often, the configuration of mine seismic networks is changed, or the networks are improved, which inevitably gives rise to changes in the completeness of the seismic catalogues. The routine analysis of seismic hazards must account for these time dependent changes. A method for the evaluation of hazards is reviewed that accommodates varying levels of quality in the catalogues. Finally, the concept of the volume of ground motion (VGM) is presented. This is a technique that allows for most aspects of seismic hazards in mines. The advantage of the VGM is that a hazard can be described by one physically significant value: the volume of rock (cumulated over a time period) in which the ground motion exceeds some critical particle velocity. Data from the gold mining region in South Africa known as the Far West Rand is used in a demonstration of the discussed methods of hazard analysis.

Jan 1, 1994

By E. -U. Reuther

To improve the climatic environment underground the German coal mining industry has installed refrigerators with a capacity of 300 MW cooling power. One third of this total is accounted for by central refrigeration plants with more than 5 MW capacity. The central refrigeration comprises three stages: mechanical cooling, transport and distribution of chilled water via pipelines and exchange of heat in the air coolers. Of these three stages only the mechanical generation of chilled water has been resolved satisfactorily. Transport (including distribution) and exchange require further technical research. The Mining Institute of the Aachen University of Technology has done extensive studies on this subject, concentrating on controlling the flow of chilled water according to demand in the mine. Additionally, the favourable exchange in the air coolers is taken into account. The studies are based on a model mine which simulates the conditions in deep coal mines in Germany. The simulation program represents firstly the condition of the mine air at the location of the air being cooled, then the heat exchange in the air cooler itself, and finally the transport of the chilled water from the central refrigerator to the consumer. The program also reproduces the seasonal and operational changes in conditions of mine air as well as different air cooler designs. A regulated distribution of chilled water is also suggested. Finally, estimations of costs can be made as an aid for further planning.

Jan 1, 1987

To the members of The South African Institute of Mining and Metallurgy I have audited the annual financial statements of The South African Institute of Mining and Metallurgy set out on pages 641 to 644 for the year ended 30 June 2006. These annual financial statements are the responsibility of the Institute?s Council members. My responsibility is to express an opinion on these annual financial statements based on my audit. Scope I conducted my audit in accordance with International Standards on Auditing. Those standards require that I plan and perform the audit to obtain reasonable assurance about whether the annual financial statements are free of material misstatement. An audit includes: ?examining, on a test basis, evidence supporting the amounts and disclosures in the annual financial statements, ?assessing the accounting policies used and significant estimates made by management, and ?evaluating the overall financial statement presentation. I believe that my audit provides a reasonable basis for my opinion. Audit opinion In my opinion, the annual financial statements present fairly, in all material respects, the financial position of the Institute at 30 June 2006 and the results of its operations and cash flows for the year then ended in accordance with generally accepted accounting practice appropriate to the Institute. Supplementary information The supplementary schedule does not form part of the annual financial statements and is presented as additional information. I have not audited this schedule and accordingly do not express an opinion on it.

Jan 1, 2006

By A. Tekin

In almost all branches of industry, machinery and equipment in operation cause vibration. Some sources of vibration affect only the operator’s hands, fingers, and arms, while others have adverse effects on the entire -body. Various types and numbers of machines are utilized in the mining sector, and operators with them are exposed to mechanical vibrations caused by the mining machinery they use. A field study was conducted to evaluate the vibration risks to the operators using mining machines in open pit mines. Vibration levels and whole-body vibration (WBV) measurements using various types brands, and models of construction equipment were evaluated in three different mines in the west of Turkey and compared to the the criteria specified in the EU 2002/44/EC directive and ISO 2631-1 (1997) standards. The results showed that operators using mining machinery for 8 hours were exposed to WBV levels below the EU limit (1.15 m/s2), while 44% of these operators were exposed to levels above the EU action limit (0.5 m/s2). Measurement data collected from the working environment and the recommended improvements that need to be made to reduce WBV exposures are presented.

May 2, 2022

By M. Shamsi, M. Nehring

One of the most challenging aspects in semi-mobile in-pit crushing and conveying (SMIPCC) system design is determining the optimum depth at which to change from a purely truck-based haulage system to a conveyor-based haulage system. We used scenario analysis to determine the optimum transition depth between a truck and shovel (TS) system and a SMIPCC system. Traditional pit-limit algorithms were used to generate the final pit limit on a copper deposit, which was then divided into four pushbacks. The final operating pushbacks (phases) were designed for both TS and SMIPCC. The end depths for each phase are viewed as candidate transition points to switch from the TS to SMIPCC haulage system. Economic calculations were applied for five different scenarios, including adopting SMIPCC from the outset (pure SMIPCC), after the first, second, and third phases, and finally not using the SMIPCC system (pure TS) at all. The analysis indicates that the second scenario, at a depth of 335 m, results in the lowest cumulative discounted cost (CDC). In this case, the CDC is 17.6% lower than that for the pure TS scenario and 10.7% lower than for the pure SMIPCC system scenario.

Sep 1, 2021