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By X. B. Zhao, J. G. Cai

When stress wave propagates through fractured rock masses, the wave will be slowed and attenuated due to the presence of these fractures. If the amplitude of stress wave is large enough to mobilize nonlinear deformation of these fractures, they will present different effects on one-dimensional P-wave propagation compared with those of linear deformational fractures. The static BB model is adopted to describe the nonlinear deformational behavior. Method of characteristics combined with displacement discontinuity theory is used to build analytical solutions of wave particle velocities and wave stresses. These equations are numerically solved with sufficient accuracy.

Jan 1, 2003

By C. G. Anderson

Throughout the world, there are many orebodies or materials which have significant value but also contain arsenic, antimony, and mercury. As regulations on the transport, exposure, disposition and emission of these elements have become more stringent; it has become increasingly more difficult to derive the values from the resources. This paper outlines the fundamentals of alkaline sulfide hydrometallurgy and its successful application to arsenic, antimony and mercury bearing ores, concentrates, by-products, and other materials.

Jan 1, 2008

By E. Matinde

Poor phase separation and fine dissemination of the desired components within congruous slag phases are key challenges limiting the recoverability of values from slags by conventional beneficiation methods. Slag microstructure conditioning is a pragmatic approach to increasing themvalue-in-use of discard slags, especially when integrated with the broader smelter infrastructure. Although not yet tested on oxide slag systems, this paper explores the potential application of magnetohydrodynamic principles to the crystallization behaviour of bulk slags. Integrating the slag microstructure conditioning infrastructure to the existing smelter infrastructure is key to unlocking the economic value of slags because it is most economic to condition the properties of molten slag directly after tapping. A new business model that integrates smelting units to transversalmeconomic activities, such as cement production and suppliers of construction aggregates, canmsignificantly increase the circularity of metallurgical slags.

Oct 9, 2024

By K. C. Naidoo

There are two main types of densifying cyclones currently available in the market, namely polyeurethane (PU) and ceramic. The PU densifying cyclones are currently used throughout the Grootegeluk complex and coal beneficiation in general. It has been identified that PU densifiers wear relatively fast depending on the operating pressure and need to be replaced frequently as a result. The motivation for this paper is to achieve an increase in the densifying cyclone lifetime through less wear and an increase in efficiency resulting in the ability to build higher relative densities (RD) more quickly. This will allow for a reduction in downtimes due to replacing densifying cyclones as well as building RD and a reduction in the operating costs associated with replacing worn densifying cyclones. Some of the major findings of the study indicated that the ceramic cyclone theoretically undergoes less wear than the PU cyclone, but since wear is application-specific and was evaluated, the wear on the polyurethane cyclone was found to be minimal. The RD differential is higher on the PU cyclones than the ceramic cyclones, showing that the PU cyclones perform better in a densifying application. This is the first test conducted on this application and type of cyclones. It should therefore be noted that having the PU cyclone significantly outperform the ceramic cyclone was not expected, due to the only change being the material of construction. This is an indication to take the material of construction into account when selecting cyclones as it can have a significant impact on the cyclone performance in specific applications. Keywords: Ceramic, cyclone, densifying, density, dense medium, polyurethane, wear

Jan 1, 2020

By S. Yaw Amponsah, E. Ben-Awuah, P. M. Takouda, P. Eme

Mining production scheduling is the process of determining the sequence of block extraction over a period of time that will yield the maximum net present value for a mining operation. The block extraction sequence needs to occur under certain resource constraints which presents an NP-hard problem that is computationally intractable and complex to solve for large scale problems using exact mathematical models such as Mixed Integer Linear Programming (MILP). In this paper, we used a metaheuristic optimisation model based on a Genetic Algorithm (GA) to solve the production scheduling problem. The problem definition and resource constraints are formulated using a mining specific GA that enforces block extraction precedence and mining capacity constraints through a normalisation method. A case study is implemented with the GA model, and the results and computational time are compared with that of a MILP model with CPLEX solver which is based on a branch-and-cut algorithm.

Sep 1, 2021

The Annual General Meeting of The South African Institute of Mining and Metallurgy was held in Kelvin House on Wednesday, 18th August, 1982. Mr G. Y. Nisbet (President) was in the chair and declared the meeting open at 16h05. Obituaries President: It is my sad duty to announce the deaths of the following members of the Institute: Honorary Life Fellow J. A. Taylor ; Life Fellows J. Watt and J. J. Cairns ; Fellows J. H. Mortimer, R. R. M. Cousens, H. Clark, S. W. Hill, Dr A. Whillier, and Dr C. M. van H. van Staden; Members F. W. McElroy, V. J. Irsigler, B. J. R. Botha, and E. J. Jackson; and Associate B. V. Robertson. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, please rise and ob¬serve a few minutes of silence.

Jan 1, 1982

By Y. F. Bulgakov, Y. V. Melnikova, V. S. Zakharov

A new technology of atmosphere in inertization of fire section with the help of gazeous nitrogen is presented in the report. This technology is based on membrane air subdivision into two streams, concentrated with nitrogen (up to 99%) and with oxygen correspondently with subsequent giving them into the place of fire. This technology belongs to environmentally friendly ones and it has a great number of technical, mobile and economic advantages comparing with the rest of well-known methods of fire extinguishing. This technology application in Ukrainian coal mines allowed to reduce the member of isolated places of fire at the expense of their extinguishing efficiency.

Jan 1, 2003

By Simon Mundike, Muwindwa Lipalile

A scraper based block cave method has been successfully applied to extract the Lower Ore Body at Nchanga since the 1950?s. Since inception, scraper drifts and service ways have been supported using steel arch sets fabricated to a specific design from high strength manganese steel To reduce costs and to improve productivity, trials commenced in 2002 using fibre reinforced shotcrete as an alternative support method. One of the areas; the 2420 8E 1C trial drift was subjected to abutment loading for several months prior to undercutting and cave mining. Shotcrete installed exhibited minor cracking shortly after application but very little deterioration thereafter. Following the success of the trial, the application of fibre reinforced shotcrete was extended to other drifts. This paper describes the application of fibre reinforced shotcrete at Nchanga and outlines design and quality assurance methods employed.

Jan 1, 2005

By A. M. Ghodgaonkar, P. J. Bhonde, R. D. Angal

Primarily ferrochrome is used to introduce chromium into steels and alloys. Chromium enhances hardness, hardenability, corrosion, abrasion and wear resistance of the steel. High carbon ferrochrome is one the cheapest sources of chromium, which finds large consumption in foundries and steel plants. However, carbon leads to problems viz. weld decay and sensitization of steels at elevated temperature causing catastrophic failure. Thus high carbon ferrochrome which otherwise enjoys financial edge over its low carbon grade is not suitable for final alloying or adjustment of chromium content. Subsequently, its addition burdens a steel maker. Hence, metallurgists around the globe have researched on finding out suitable technique for refining of ferrochrome. Traditional production methods of low carbon ferrochrome have drawbacks i.e. high refractory consumption, losses of chromium in slag and fumes etc-. Later these were overcome by adopting relatively new methods namely, metallothermic reduction, triplex process, vacuum technique to directly produce extra low carbon ferrochrome. Authors have carried SWOT analysis of the aforementioned techniques in the literature. Key Words: Ferrochrome, carbon content, low carbon grade, chromite, sensitization

Jan 1, 2007

By E. Saari, B. Musuku, K. Jansson

The quality of the concentrator plant process water is crucial for high performing mineral flotation circuits. Significant metal recovery and concentrate grade losses have been noticed particularly in more closed water loops. The recovery and quality losses have started to emerge mainly with decreased freshwater usage and because of changes in tailings management towards tailings thickening, paste, or dry stacking. These changes result in shorter, closed water loops with a rapid build-up of harmful components with negative impact on the beneficiation process. Consequently, water quality has a direct link to decreased product value and sales returns. Complete cleaning or water blending might not be the right way to achieve high recovery and high-quality products. Instead, the key is to understand what kind of water qualities are needed for the flotation of specific minerals. In this study harmful substances in various plant water streams were removed and/or modified by pilot-scale dissolved air flotation. Batch-scale mineral flotation tests with the untreated and treated water were then performed by using fresh ore samples and the plant’s own laboratory flotation procedure. The results indicate that because of dissolved air flotation, the mineral flotation recoveries were enhanced by 1‒3.3%. Keywords: Mineral recovery, metal recovery, mineral quality, process water, concentrator, beneficiation, mineral processing, flotation, process water treatment

Jan 1, 2020

By S. Burks

This paper develops the themes explained at the previous SAIMM Platinum conference by Whittle and Burks1. Optimization techniques can be used to significantly increase the value of mining businesses by enabling better long- term planning decisions. Open pit and underground mine design, mine scheduling, cut-off grade and blending, stockpiling, and the linking of these to flexible elements of the metallurgical recovery processes are all evaluated together. Transport or sale of intermediate products and the requirements of the product metal markets can also be considered. Experience shows that net present value (NPV) can potentially be increased by 5-35 per cent or more, usually even before the expenditure of significant amounts of project capital. The case studies presented include: ? An existing operation with multiple open pits and PGM concentrators linked to offsite downstream processing facilities, and with infrastructure constraints for which the scheduling of current operations and the potential for expansion were investigated ? An existing operation with an integrated portfolio of mines, concentrators, smelter and refinery, for which the various possible sources of ore for processing were prioritized to match the downstream process plant constraints and the product markets ? An underground operation in Zimbabwe for which the optimum mining width was calculated and expansion plans were evaluated ? An underground mine with many separate mining sections, for which a revised schedule was developed aiming to keep the shaft system and processing plant at capacity with the highest net value material available at any time throughout the life of mine. In the concluding section of the paper, a few brief notes are included suggesting how the strategic recommendations from enterprise optimization studies may be implemented by the Owner?s team.

Jan 1, 2012

By M. Kannenberg

When coal properties are estimated geostatistically for mine planning in the hardcoal industry, there is one important supposition which influences the reliability of prediction of economically profitable parts of the deposit. This is the fact that activities in hardcoal exploration and mine planning are characterized by distinct levels of information and knowledge upon which decisions of economic import must be based, for example, whether exploration should proceed or not, or which methods and strategies should be used to maximize search efficiency. To get more reliable results for mine planning, in particular, advanced kriging methods (e.g. conditional simulation) have to be introduced and checked for their reliability in historical analyses (post-mortem studies). By using this feedback, kriging results from underground samples or production data can be compared with results gained by advanced geostatistical methods from exploration boreholes.

Jan 1, 1987

By S. G. Hardcastle, C. K. Kocsis

In Canada’s metal mines, ventilation, which requires electricity to operate the fans and fossil fuel for heating, accounts for a significant portion of the overall mine’s underground power consumption. Mine ventilation systems are usually designed near the end of the mine design process and often designed for the ‘worst-case-scenario’ with respect to ventilation demand. In Canada’s metal mines this is commonly dictated by either diesel equipment usage or heat management considerations. Once designed, mine ventilation systems tend to operate at this peak level throughout the operating life of the mine. This is despite there being significant periods when this quantity is not required this is done mainly due to lack of appropriate ventilation controls. Consequently, such systems are inefficient and wasteful and this must be changed if mining operations are to remain competitive while meeting increasingly more stringent regulations of underground environmental conditions. The advances in computing power and modelling software now make it possible to design, model and schedule a mine from opening to closure. The tools used for this include several disparate types of software. A developing trend is to design and plan the mine using orebody modelling software, followed by using discrete event simulation to predict production and evaluate various operating scenarios. It seems that again ventilation design is not being integrated into this process. Although, several modelling packages exist for ventilation design, little work has been done on integrating ventilation modelling into the overall life cycle plan of the mine. This paper will present a discussion of the work where the authors are attempting to integrate discrete event simulation for mine planning with ventilation modelling to predict the ventilation requirements for the operating life of the mine.

Jan 1, 2003

By X. Chen, F. An, H. Chen, Z. Wang

The bottom drainage roadway plays a crucial role in preventing coal and gas outbursts by using underground gas drainage methods. Therefore, it is essential to select the ideal position of the bottom drainage roadway. In this paper use a combination of geological data and numerical simulation to study the ideal position of the bottom drainage roadway, we taking the gas drainage of the first workface of No. 3 coal seam in the Yuxi coal mine in China as an example. The geological study showed a limestone marker layer at an average vertical distance of 14 m from the first mining face. Using this marker layer, the bottom drainage roadway could be excavated without the risk of accidentally exposing the coal seam, and less crosscutting borehole drilling from the bottom drainage roadway would be required. Based on the needs of gas control, the layout of the bottom drainage roadway was selected as an external stagger type. Combined with the numerical simulation results, when located 20 m outside of the mining workface ‘footprint’ on the horizontal projection, the bottom drainage roadway was a sufficient distance from the stress concentration area during mining of workface 1301, which facilitated roadway maintenance. Furthermore, the length of the crosscutting boreholes is also relatively short, which reduces the amount and cost of drilling. The results of this study are expected to provide a reference for the selection of an ideal position of the bottom drainage roadway in field engineering.

May 2, 2022

By M. N. James

The Fracture Research Group has been operating at the University of the Witwatersrand for some ten years and, in that period, has achieved a significant profile, both nationally and internationally, through its research publications, industrially-based technical reports, continuing short courses in engineering education, and co1Jferences. This paper outlines the activities of the Group over the past few years, emphasizing the research thrusts and the results that have been obtained, as well as highlighting areas of current and future research interest The capabilities of the Group in terms of equipment and expertise are also discussed briefly.

Jan 1, 1995

By P. Malíková, I. Osičková, R. Sousedíková, P. Rys, J. Dvořáček, S. Heviánková

Each mining project goes through the same life-cycle, from prospecting and exploration to closure and post-closure periods. This prompts the question whether the closure of a mine constitutes the end of its life-cycle or whether the decommissioned mine can be employed for some other purpose. Best-practice references indicate that there are many viable options. In our opinion, the production of service water is one such option. Laboratory research was carried out on the water from a flooded underground coal mine in Ostrava- Karviná coal district, Czech Republic, concerning the production of service water from pumped minewater. The research proved the practical feasibility of service or process water production. Given the effect of global climate change with regard to water resources, good prospects for this additional resource can be assumed since the water has to be pumped in any case for safety reasons.

Oct 1, 2022

By G. M. Wright

We are only as good as we are perceived to be by others and, whilst there is every opportunity to revise and polish our written works, there are no second chances with a spoken presentation. At every level, conferences and seminars have been metaphorical graveyards for many an academic reputation.

Jan 1, 1990

The paper discusses the improvements achieved after an external sparger flotation column was installed as a final cleaner at the Northam Platinum Ltd. UG 2 concentrator in South Africa. It further discusses the improvements achieved after the conversion of a conventional flotation column, utilized as cleaner in the Merensky concentrator, to an external sparger flotation column. Finally, the application of the above knowledge in the design and commissioning of an external sparger flotation column as final cleaner in the furnace slag concentrator, is also discussed. 1. FINAL CLEANER AT THE UG 2 CONCENTRATOR The MF2 designed UG 2 concentrator is processing 75 000 tonnes run of mine ore at a head grade of 4.0 g/t 3PGM+Au and a feed Cr2O3 concentration of 28 %. Since commissioning of the plant in 2001, Cr2O3 in final concentrate amounted to approximately 5 % of the total mass. Although final concentrate produced from the UG 2 concentrator is blended with final concentrate obtained from the Merensky concentrator before smelting, blended Cr2O3 values in excess of 1.6% lead to difficulties in the subsequent smelting process. Several options for reducing the amount of Cr2O3 in final concentrate have been evaluated namely:- ? Differing types of depressants at various dosing rates. This test work did not reduce the amount of Cr2O3 reporting to final concentrate by any significant extent. ? Reduction in mass pull to minimize the entrainment of Cr2O3 in the concentrate stream.. This process change had a detrimental effect on PGM recovery. Conclusions were drawn that conventional mechanically agitated flotation cells could not achieve the required selectivity without sacrificing PGM recovery. As a consequence an alternative mechanism needed to be incorporated for the final cleaning of PGM concentrate.

Jan 1, 2007

By A. Santana, J. Jankolovits, G. S. Reyes

The flotation of sulfide ores that contain carbonaceous gangue requires significant operational and chemical intervention to achieve suitable metallurgical outcomes. Carbonaceous gangue dilutes concentrate grades, alters the froth behaviour, reduces operational stability, adsorbs reagents, and reduces value recovery. Carbon management processing strategies like preflotation and depression are often presented as point solutions. Moreover, oversimplified mechanisms of carbon depressants belie their complex and nuanced impact on flotation behaviour. Optimising the flotation of carbonaceous sulfide ores requires a holistic consideration of interactions between the carbon management reagents and the processing strategy, ore mineralogy, flotation behaviour, flowsheet, and all other aspects of the flotation system. Examples are shown where conventional, simplistic mechanisms of carbon depressants fail to explain the observed flotation behaviour. The multifaceted impacts of carbon depressants on froth behaviour, collector performance, and value recovery highlight the need for a holistic approach to carbon management. Keywords: Carbon management, carbonaceous ores, sulfide flotation, carbon depressant

Jan 1, 2020

By C. Dorfling, M. Tadie, M. Tucker

Electrowinning is the final step in the hydrometallurgical production of high purity copper, involving the passage of electric current through an electrolyte and consequent plating of solid copper to form cathode sheets. Key electrowinning performance indicators are the current efficiency, specific energy consumption, yield, and quality of the metal. The high energy demand and associated cost mean that determination of performance indicators is critical during operation, but ‘online’ measurement is impractical due to the nature of the measurements and corrosive environment brought about by acid mist. This research considered the development of a predictive electrowinning model as a shift towards a pre-emptive approach to attaining plant performance data. A steady-state model was created from input variables available in the industry, using a first-principles approach combining mass balances, electrochemical and thermodynamic equations, and property correlations. A circuit diagram equivalent of an electrowinning cell, containing multiple pairs of electrodes, was used as the backbone of the model. The kinetics of each electrochemical reaction were modelled including iron as a major impurity. Losses in current efficiency due to ineffective electrode contact, short circuits, and stray currents were also incorporated. The model was used to predict the current efficiencies for tests performed at varying conditions in a bench-scale electrowinning cell; the average absolute error between the measured and predicted current efficiencies was 3.2%. The model requires a unique parameter fitting approach for each industrial operation; if parameters are customised for specific plants, the model will be a useful tool to predict performance and can aid the development of effective process control systems in copper electrowinning tank houses. Keywords: Copper; current efficiency; electrowinning; modelling; plating rate

Jan 1, 2020