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By S. K. Murphy

A partial shaft pillar extraction project was embarked on at a mine in the West Wits mining region in South Africa. Prior to the extraction, a rock engineering assessment was conducted with the main objective being to establish which areas of the shaft pillar could be extracted without unduly affecting the stability of major infrastructure within the shaft pillar. Standard numerical modelling methods were used to conduct this assessment and several areas were identified for extraction. However, during the extraction process, it was found that the infrastructure was affected more than was originally predicted by linear elastic modelling. In addition to this, several large events resulted in far more large aftershocks than would normally be predicted. In order to gain an understanding of this phenomenon, seismic data was integrated with numerical modelling as follows: > The seismic data in the form of displacements was integrated in 3D space within the model to assess the effect of static stress changes associated with seismic activity > Data from large events was integrated onto specific structures, where displacements associated with large events were integrated onto the plane of structure in question. This paper describes the methodology and results obtained from each of the above processes and include insights into the mining process that were previously unfathomable using standard linear elastic numerical modelling. The way forward for this rock engineering assessment of partial shaft pillar extraction is also discussed.

Jan 1, 2012

By A. Galibois, A. Dubé, H. Monette, J. L. Collins

"The start of mining operations often raises serious financial problems. In marginal cases promoters frequently demand financial aid from governments.In the past, the financial assistance has taken the form of gifts, procurement contracts, etc., but aid in such form has been severely criticized. A new formula has been developed to provide a more equitable distribution of the revenues accruing to the government and to private capital.The benefits to these two parties have been evaluated in an hypothetical case and compared in terms of internal rates of return on their investment, their shares of the undiscounted cash flows and their primary profits.The method based on the non-zero sum game theory provides a means for suggesting the lowest feasible annual production and the optimal sum contributed by the government in the form of outright gift, equity capital and convertible bonds. Other financial hypotheses can also be optimized by the computerized analysis."

Jan 1, 2014

By B. P. von der Heyden, T. Blenkinsop, A. Mamuse

Zimbabwe hosts a varied array of coloured gemstones. With the exception of emerald deposits and several world-class pegmatites, few of the gemstone occurrences have received detailed attention from the scientific or mineral exploration communities. In the present contribution we summarize the status of knowledge of the gemstone deposits and occurrences in Zimbabwe, paying particular attention to the geological settings in which they were formed. Synthesis of this regional geological approach reveals that there may be significant exploration potential for further gemstone occurrences, particularly in the extensive pegmatite fields and in Al-enriched orogenic belts that have undergone greenschist to granulite facies metamorphism. Further socio-economic and developmental initiatives will aid in optimizing the value generation from this important sub-sector.

Feb 12, 2024

By D. P. Roberts

This investigation aimed to simulate the experiments performed by Nic Gay (Gay, N.C.1976. Fracture growth around openings in large blocks of rock subjected to uniaxial and biaxial compression. International journal of Rock Mechanics and Minining Sciences and Geomechical Abstracts, vol. 13. pp. 231-243) on fracture growth around openings in blocks of rock subjected to uniaxial and biaxial compression, using the Elfen discrete element code. The results of the physical experiments indicated a number of trends that were successfully replicated in the numerical simulations, including crushing ahead of the face, the formation of a sub-vertical tensile fracture at centre-span, the formation of groups of fractures originating from the crushed face zone, the formation of large corner-to-corner fractures which precede sample failure, and linking of slot corner and sample corner fractures leading to sample failure. In addition, other features were apparent that were not reported by Gay. It is believed that these took the form of conjugate shear fractures (as reported by Gay in a previous paper) and other features that may have been altered or inhibited by the presence of pre-existing structure in the physical samples. It was found that the samples, though nominally made up of the same rock type, must have had significantly differing properties. The presence of pre-existing structures may have contributed to this discrepancy. Strain measurements from the physical experiments were reasonably well matched, except where the gauge lay directly in the path of advancing fractures.

Jan 1, 2012

By S. Lohmeier, D. Gallhofer, B. G. Lottermoser, T. Schirmer

At a time of resource consumption, it is important to study the chemical composition of mining and metallurgical wastes to prevent the dissipative loss of metals and metalloids from the mining value chain. In particular, the recovery of critical elements from wastes is an option to increase the resources of such materials that are economically significant and have an overall supply risk. In this paper we report on the chemical composition, in particular the critical element content, of granulated slag originating from historical smelting activities in the Tsumeb area, Namibia. Laboratory-based inductively coupled plasma–mass spectrometry (ICP-MS) and X-ray fluorescence (XRF) analyses as well as portable X-ray fluorescence (pXRF) demonstrate that the slags are on average enriched in base metals (Cu 0.7 wt%, Pb 2.7 wt%, Zn 4.7 wt%), trace metals and metalloids (Cd approx. 50 mg/kg, Mo approx. 910 mg/kg) as well as critical elements (As approx. 6300 mg/kg, Bi approx. 3 mg/kg, Co approx. 200 mg/kg, Ga approx. 100 mg/kg, In approx. 9 mg/kg, Sb approx. 470 mg/kg). While metals and metalloids such as As, Mo and Pb can be determined reliably using pXRF instruments, the technique has inherent limitations in evaluating the contents of certain critical elements (Ga, Sb). However, there are positive correlations between the As, Mo, and Pb contents determined by pXRF and the Ga and Sb contents obtained through ICP-MS and XRF. Thus, quantitative pXRF analysis for As, Mo, and Pb allows calculation of Ga and Sb abundances in the slags. This work demonstrates that pXRF analysers are a valuable tool to screen smelting slags for their chemical composition and to predict the likely contents of critical elements.

Mar 1, 2021

By B. F. Giyani, A. Salama

Tanzania is a country with a variety of mineral deposits, including metallic minerals, gemstones, mineral fuels, industrial minerals, and critical minerals. This study provides an overview of mining legal framework, mineral occurrence and production, challenges in the mining sector, and government initiatives. The aim is to demonstrate the development of the mining sector in Tanzania and explore the potential for further mining investment in the country. The mineral production data showed generally increasing trends over the years, for example, gold production increased from 42 tonnes in 2018/2019 to around 50 tonnes in 2023/2024. Despite the growth, the mining sector encounters several challenges, including a lack of detailed geological information on mineral deposits, inadequate infrastructures in some remote mining sites, the existence of informal artisanal miners, and mineral smuggling. The Tanzanian government has introduced several initiatives to address these challenges, including carrying out the highresolution airborne geophysical survey to increase geological information in some areas, the formalisation of artisanal and small-scale mining, establishing mineral markets to combat mineral smuggling, and encouraging mineral value addition within the country.

Oct 24, 2025

By P. M. Mashaba, S. O. Bada

An advanced high internal phase water-in-oil (HIP W/O) emulsion binder and flotation with an internal dispersed water phase of 95 vol% was used to beneficiate South African weathered coal from discard dumps. Five coal samples with calorific values ranged from 8.48 MJ/kg to 20.94 MJ/kg were utilized. The performance of the HIP W/O emulsion was compared to that of kerosene in terms of the physicochemical properties of the clean coal products. A 5 kg/t emulsion binder addition produced a high-quality coal concentrate with 11.76% ash and a heating value of 28.61 MJ/kg from a sample containing 29.34% ash. Using the same dose and coal sample, kerosene resulted in a clean coal concentrate with 17.47% ash and a calorific value of 26.42 MJ/kg. Further samples were also beneficiated using 5 kg/t of W/O emulsion. The highest increase in calorific value was achieved from the beneficiation of a sample containing 48.71% ash, from 8.48 MJ/kg to 18.16 MJ/kg. It has been established that emulsion binders can upgrade coal samples dumped many decades ago.

Aug 2, 2022

By C. M. G. Wortley, N. Randolph, I. Ralston, R. D. Beck

The ?AMIRA Metal Accounting Project? had its origin in a workshop held in Cape Town on 1 August 2001, with the title ?Challenges in Metal Accounting and Information Management?, which was organised by the Western Cape Branch of the South African Institute of Mining and Metallurgy. This workshop identified the lack of an accepted set of standard procedures for metallurgical accounting as an industry-wide problem. Discussions which followed this workshop led to the initiation of the AMIRA Project P754, ?Improving Metal Accounting?, in 2003. The primary objective of the project was to provide tools for improving the auditability and transparency of metal accounting from mine to product and to facilitate good corporate governance. The planned deliverables of the project were a series of research projects into aspects of metal balancing in different types of metallurgical operations, a Code of Practice on Metal Accounting, and a textbook on the subject which could serve as a guide for metal accounting practitioners and students studying the topic. An additional planned deliverable was the provision of a new variety of professional experts in metal accounting, through successful completion of the research projects. Researchers were engaged at the Universities of Cape Town, Queensland and Stellenbosch and the project was sponsored by five mining companies, including three of the largest global mining groups. Research Program Eight research projects were undertaken as part of the P754 project and these are described briefly here to indicate the scope of the project. University of Cape Town ?Development of a methodology for measurement network design for metallurgical accounting at Namakwa Sands?. This project was based on the Namakwa Sands Separation Plant, with a data rich environment, and involved the investigation of measurement network design through the use of heuristics and the analysis of complex processing circuits. An industry-wide survey of current practice to facilitate the development of an expert system for plant accounting measurements was carried out. ?Metallurgical accounting design at the Waterval UG-2 Concentrator?. The objective of this project is to develop a model for predicting metal recoveries from the different components of a blended ore feed to a plant. ?Optimal measurement network design for metallurgical accounting at Zincor?. This project provided a hydrometallurgical test case for the design and evaluation of a semi-automated optimal measurement network. University of Queensland ?Quantifying the relationship between mine and mill?. This project involved a case study at North Parkes Mine, in which copper and gold ore is tracked from the pit source to the product, as well as a stockpile modelling study. University of Stellenbosch

Jan 1, 2007

By V. Jokovic

Hydrocyclones are the most commonly used classifiers in the mining industry. The reason for this is their low operating cost and a small footprint. Data from plant trials where screens replaced hydrocyclones indicated that lower bypass of fines and sharper separation could improve breakage rates, with a positive effect on flotation circuit performance throughput. Despite the importance of classification, hydrocyclones have not received as much attention as more expensive comminution units, and their technological progress has been incremental. Noticeable water split (Rf) reductions of a semi-inverted hydrocyclone have been reported in the past. According to theory, the hydrocyclone with reduced Rf will improve classification of fines. A classification study using semi-inverted hydrocyclones was conducted to determine if a hydrocyclone could be operated in a way that would minimise misclassified fines. The classification performance of a semi-inverted hydrocyclone will be presented in this paper and other potential applications will be discussed. Keywords: Semi-inverted hydrocyclone, water split, misclassification of fines

Jan 1, 2020

By M. Rudman, L. Pullum, L. J. W. Graham

Centrifugal pumps are the workhorse of hydraulic conveying systems but their performance is derated when viscous non-Newtonian fluids, such as pastes and/or coarse solids are present. The reduced performance for purely viscous Newtonian fluids may be calculated using techniques such as the Hydraulic Institute method, but similar deration for non-Newtonian fluids is not so easy to apply. As part of the AMIRA P599 project investigating high concentration suspension pumping, centrifugal pump tests were systematically conducted on a wide range of non-Newtonian coarse particle suspensions. Suspension sup to 38% v/v of coarse particles with mean diameters in the range of 1.1 < d50< 3.4 mm suspended in carrier fluids with dynamic yield stresses of 0 < t?< 17.2 Pa and shear thinning indices in the range 0.35 < n< 0.79 were examined. Techniques such as the Hydraulic Institute de-ration method require a characteristic shear rate to be assigned before application with a non-Newtonian fluid, and a method based on pump geometry, fluid rheology and flow rate is proposed. This method predicts the dramatic characteristic reduction in head at low flow rates that is often observed and explains why larger pumps are relatively insensitive to this form of head deration. Head deration due to the presence of coarse particles in non-Newtonian carrier fluids is seen to follow similar trends to that of Newtonian suspensions and often dominates the total deration procedure.

Jan 1, 2007

Notices THE FEDERATION OF SOCIETIES OF PROFESSIONAL ENGINEERS It is expected that the National Institute of Personnel Research will be conducting a project, at the request of the Federation, to establish the relationship, if any, between the academic and professional achievements of engineers. co-operate with the researchers. INFACON 74 The National Institute for Metallurgy, the South African Institute of Mining and Metallurgy, and the Ferro Alloy Producers&apos; Association of South Africa will hold an International Ferro-alloys Congress in Johannesburg from 22nd to 26th April, 1974. INTERNATIONAL PLATINUM SYMPOSIUM OF THE SOCIETY OF ECONOMIC GEOLOGISTS The above symposium is to be held at the U.S. Geological Survey, Denver Federal Center, Denver, Colorado, from 13th to 17th October, 1975. Papers up to 40 doublespaced THIRD MEETING-CANADIAN HYDROMETALLURGYGROUP The Hydrometallurgy Group of the Metallurgical Society, Canadian Institute of Mining and Metallurgy, will hold its Third Annual Meeting, October 1 and 2, 1973, at Edmonton Alberta. COLLOQUIUM ON THE CONSTRUCTION OF SLIMES DAMS The Institute has arranged a two day colloquium on the above topic, to be held on November 14th and 15th, 1973, at Kelvin House. The following Programme has been arranged:

By X. W. Pan

It has been found that the MnO content of a slag decreases sharply when direct current is applied to a 1T1£tal-Slagsystem consisting of liquid Mn-Si-Ccsat metals and MnO-SiO2-CaO-AI203 slag in graphite crucibles. This paper reports a preliminary investigation into the electrochemical effects of direct current on the metal-slag system, the silicon content of the metals, and the MnO content of the slag. The results show that, when a direct current of 7 A is maintained, the MnO content of a metal containing 10 to 11 per cent silicon by weight is reduced rapidly from 26,5 to 17,2 per cent by weight. This reduction seems to proceed further when the process is continued. When the direct current and the voltage are kept constant at TA and 4 V respectively, the MnO content of a metal containing 1 to 2 per cent silicon by weight is reduced to 1 from 25 per cent by weight, which results in a manganese yield of 96 per cent.

Jan 1, 1995

By S. Heukelman

Zincor uses O2 enrichment (up to 26% O2 in the fluidizing air) to increase the processing rate of zinc concentrates in the fluidized bed roasters. The aim of this study is to determine whether O2 enrichment can be reduced by introducing micro-pelletized concentrate into the feed blend, while maintaining current roaster feed rates and calcine quality. It was found that, with a load of 20% micro-pellets introduced into the feed blend, that O2 enrichment could be reduced by 60%. It was determined that entrained particles spend on average between 0.46 hour and 2.44 hour in the roaster, compared to particles remaining between 3.93 hour and 4.00 hour in the bed overflow. This compares well with a radioactive tracer test performed by Spira. The required reaction time for micro-pellets was found to be less than the residence time inside a Zincor roaster. The result achieved indicated that the average particle residence time inside the roaster was increased successfully in order to compensate for the longer reaction time required to roast micro-pellets at lower levels of O2 in the fluidizing air.

Jan 1, 2011

By E. M. Sacris

The semi-autogenous grinding mill is the bottleneck whenever treating hard and finely fragmented ore at Benguet Corporation&apos;s Kaline Concentrator. Low milling rates result from very high and fluctuating mill power draw. Attempts to use a mill horsepower control loop to regulate feed rate were unsuccessful because of operational upsets caused by fluctuations in feed rate on downstream operations. The objective of the computer control was to maximize tonnage throughput by stabilizing the power draw at a high but safe level without upsetting subsequent operations. The semi-autogenous mill is operated in closed circuit with a stationary screen. Instrumentation consists of a feed weightometer, a power transmitter to measure mill load, a headwater flowmeter and an ultrasonic level sensor to measure the mill discharge sump level. A 64 k-byte FOX-3 Foxboro computer processes field data from various sensors and manipulates the input control variables. These variables are the fresh feed rate and the headwater flowrate. Feed rate is controlled through a supervisor-type computer program aimed at maximizing and stabilizing power draw. The control scheme was according to how the operators responded during an operator-directed automatic control mode. Mill dilution is similarly controlled. Results achieved reflect a 3% increase in tonnage milled because of the reduction in control variability that ensued.

Jan 1, 1987

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&apos;, 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 L. A. Jordan, D. van Vuuren

A two-dimensional finite difference model has been developed to describe the reduction of kilogram quantities of dehydrated phosphogypsum. The model’s scope has been limited to focus on the heat transfer and reactions that occur within a mass of material contained in a vessel inside a furnace rather than also including the effects of heat transfer to the vessel. Changes in the heat transfer properties (k, ρ, and Cp) are incorporated as the composition of the mass changes as the chemical reactions progress. The model is validated against experimental data, with samples heated to 1000°C at 3°C min−1 while purging with nitrogen gas. A sensitivity analysis of model predictions to the pre-exponential factor of the reaction rate constant of the main chemical reaction and the thermal conductivity of the powder bed indicated that, at the envisaged process conditions, the behaviour of the system depends much more on the rate of heat transfer than on the rate of the chemical reaction. The model demonstrated a significant increase in accuracy when the thermal conductivity was modelled to increase linearly with temperature compared to assuming a constant value.

Oct 1, 2022

By T. R. Curr, W. A. Gericke, J. Basson

South Africa is a leading player in the international ferro alloys industry. Historical factors that have contributed to this dominant position include an abundance of natural resources and relatively low cost electricity. A number of relatively recent developments are potentially threatening this position. These include new legislation affecting the mining and minerals industry, a shortage of some types of suitable reductants, depletion of surplus electricity generation capacity with resultant threat of real escalation of electricity prices and pressure resulting from the recent strengthening of the South African Rand. The industry is addressing these challenges in a number of ways to ensure long-term viability. Some of these measures include investments in more efficient technologies that have economy of scale benefits and are less dependent on expensive reductants and electricity. Local macro-economic impacts include new legislation regarding ownership of enter-prises, mineral rights and royalties on mineral sales, development plans for port and rail infrastructure, as well as initiatives to expand electricity generation and coke production capacity. The fundamentals for being a successful ferro alloy producer are still largely in place for South African producers. Therefore the South African ferro alloy industry will remain competitive and is well placed for continued growth in line with the international growth in ferro alloy demand. The industry should emerge leaner, more efficient and ready to respond to any future demands of the industry. This paper will cover the present status of the industry, the factors that are impacting thereon and a view on its future outlook.

Jan 1, 2007

By T. C. Huber

The southern African region has a high concentration of mineral resources and supplies much of the world?s platinum demand. As a result, the international community watches South Africa to understand the impact of supply on global markets. An analysis of supply certainty and risk plays a key role in the future of growing demand in various sectors. The southern African platinum industry experienced substantial growth in the early part of the 21st century, resulting in bullish forecasts for growth during the period of 2000?2006. However, southern African platinum producers saw a significant drop in production over the following three years as a result of many dynamic factors in operations and the global economy. Between 2006 and 2009 there was a million-ounce shortfall between forecast and actual production. This was raised as a concern at the Fourth International Platinum Conference in 2010 by Stephen Forrest during his keynote address, specifically regarding the lack of understanding in the market of the causes of this shortfall and any action that was being taken to address them. This paper reviews publicly available information in the media and corporate reports and communications for the period January 2006 to December 2009. In addition, several interviews were held with key stakeholders in the industry to provide further perspective. The paper then highlights the main reasons that are reported to have affected the loss in production over the period and discusses the possible implications of the information that the mining industry does and does not disclose regarding platinum supply.

Jan 1, 2012

Zincor operates four Lurgi fluidized-bed roasters at its roast-leach-electrowin refinery in Springs, South Africa. In 2006, Zincor?s four roasters had reached ages ranging between 26 and 38 years, while the expected life of this type of roaster is generally 20 to 25 years. Roaster 3 was the first to be rebuilt in 2006 because its condition had deteriorated the most. Roaster 4 is being rebuilt in 2007 and the last two roasters will be rebuilt over the next few years as necessary. The main damage to Roaster 3 was caused by buckling of the roaster steel shell. This caused the freeboard and dome areas to shift, resulting in cracks in the dome brick lining and crumbling of the bricks lining the freeboard. The steel shell buckled owing to the combined effects of excessively high operating temperatures and corrosion. These were caused by the following two main factors: ?Thicker external insulation was installed during a previous maintenance shut, which resulted in an increased steel shell temperature and exacerbated the normal metal fatigue ?SO2/SO3 containing gas that had permeated the brick lining passed through its dew point during frequent planned and unplanned shuts over the life of the roaster. This caused acid formation between the refractory brick lining and steel shell, resulting in corrosion of the shell. The initial plan was to replace only the damaged areas of Roaster 3, but when it was dismantled more damage was found, and the roaster was rebuilding from the tuyeres upwards. During there building the opportunity was taken to modify the design of some of the brickwork to extend its life and make future repairs easier. This paper discusses the mode of failure of Roaster 3 and the lessons learnt during its dismantling and rebuilding.

Jan 1, 2007

By B. Genc

Improving student success rates without compromising the quality of graduates is one of the biggest challenges expanding university programmes are facing in South Africa. By establishing a new Mine Design Laboratory (MDL) for higher learning in Mining Engineering, the School of Mining Engineering at the University of the Witwatersrand (Wits Mining) has achieved one of the important goals in its five-year strategic plan, i.e. to improve throughput in all years of study. Although the establishment of the laboratory has been a costly exercise, results so far have shown an improved success rate in most subjects taught in the facility. This paper outlines the design and equipment of the laboratory, the facilities incorporated, a comparison with the old laboratory, and the performance of students?all of which indicate how important it is to have proper facilities to improve the teaching of, and learning by, large classes. Through this initiative, Wits Mining has taken an important step that will contribute to addressing the skills shortages in the mining industry.

Jan 1, 2012