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By P. G. Kovalchik

Overexposure to noise remains a widespread, serious health hazard in the US mining and other industries despite 25 years of regulation. Most categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. The drilling of rock in a confined work environment contributes to high levels of noise exposure in mining. The National Institute for Occupational Safety and Health (NIOSH) is conducting research to reduce the noise exposures of jackleg drill operators and to prevent additional cases of noise induced hearing loss (NIHL) by developing and evaluating low-cost retrofit noise controls for equipment. This report describes the procedure for the measurement and reporting of noise from portable pneumatic tools such as jackleg drills. The technique used in this research allows for the determination of the source A-weighted sound power levels and the radiation patterns in octave and 1/3 octave bands. Overall sound power level is also determined. This paper also reports the results obtained by using this procedure to evaluate a SECO S215 standard production drill and a CSIR Miningtek prototype rock drill incorporating engineering noise control measures. It was found that by using the manufacture?s recommended operating pressure of 496 kPa (72 psi) that the CSIR prototype?s sound power was 10 dB(A) less then that of the SECO S215.

Jan 1, 2009

By S. Konetschnik, E. Dreyer, A. Filzwieser

"More intense furnace operations require effective cooling in order to achieve low refractory wear and good furnace lifetimes, making cooling technology an important aspect of furnace operations. However, the use of water - today’s standard cooling medium - has some disadvantages, as it can cause problems both during furnace start-up and operation, namely hydration problems, corrosion, and explosions. Apart from these aspects, the energy that is removed by extensive cooling cannot be recovered and is normally lost in the cooling towers.With METTOP’s new patented cooling technology it is possible to overcome the disadvantages of water by using an alternative cooling medium, namely ionic liquids (ILs). The main advantage of ILs is the fact that there is no risk of explosion should this liquid come in contact with molten metal. Furthermore, ILs can be used at higher temperatures than water - up to 200°C. This relatively high cooling medium temperature avoids hydration and corrosion problems and allows recovery of the energy by combining the ILTEC system and the organic Rankine Cycle (ORC) technology, for example.Due to the removal of the explosion risk, much higher safety standards can be achieved, particularly in critical areas such as tap-holes"

Jan 1, 2014

By W. Bendaikha, S. Larbi, A. Ramdane

An oolitic iron ore from Gara Djebilet, Algeria was characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrosopy and the phosphorus distribution between various phases studied. Two ore types were identified – a haematite-dominated, oolitic type and a more massive, magnetite-dominated type. The haematite-dominated ore had a higher phosphorus content, up to 0.6% in the iron oxide minerals, than the magnetite-dominated type (0.3% P). Owing to the very fine-grained texture of the gangue minerals, reducing the phosphorus content to levels suitable for steelmaking (below 0.05% P) by conventiobal means would entail an energyintensive process with a high carbon footprint. Preliminary leaching test work using a sulphurous geothermal water as lixiviant, assisted by solar thermal acceleration, gave very promising results, removing 0.13% of the residual P (or 21.7% removal of total P) from the high-phosphorus oolitic ore.

Mar 14, 2024

By Y. M. Zhao

The separating performance of a pilot dry beneficiation system using a gas-solid fluidized bed was investigated with coal from South Africa. The coal used for the study has a low inherent moisture content, a moderate ash content, a moderate volatile content, a low sulphur content and a high calorific value. Its washability is moderate. Experimental results show that the separating quality of the fluidized bed drops gradually as the feed-coal particle size decreases. The probable error, E, values for 50?25mm, 25?13 mm and 13?6 mm coals were 0.04 g/cm3, 0.06 g/cm3 and 0.09 g/cm3, respectively. The cause of the differences in separating characteristics was analysed by particle dynamics and numerical modelling. Furthermore, the pilot fluidized bed was employed to separate 50-6mm coal. In this experiment the coal ash content was reduced from 23.74% to 11.79%, with a probable error, E, value of 0.07 g/cm3and a recovery efficiency of 98.26%. This indicates that the fluidized bed is applicable to the separation of coal from South Africa and has good separating performance and wide applicability. Keywords: feed-coal particle size; gas-solid fluidized bed; dry coal beneficiation; numerical simulation.

Jan 1, 2010

By T. A. Muhlare

The use of electrolyte additives to smoothen cathode deposits during copper deposition is practised worldwide. These additives absorb on the cathode surface and take part in the electrochemical crystallization process. However, these additives also affect the quality of the cathodes when they are inadequately controlled. Electrolyte additives used by Palabora are glue, thiourea, Avitone and chloride. Their effects were determined on cathode quality, the size of the current density region that gives the desired compact morphology, and current efficiency. This was done in a small-scale cell. Small cells have different hydrodynamics from industrial-scale cells, which makes it difficult to simulate the operation of industrial cells in a laboratory. The approach used here was to use a rotating cylinder cathode to attain controlled hydrodynamics. The rotation speed was chosen to give a diffusion layer thickness that is similar to that of an industrial-scale cell. It was shown that even fairly small changes in the additive levels can significantly affect the cathode morphology, and the current density range over which this morphology can be obtained. Keywords Copper, electrorefining, glue, thiourea, avitone and chloride.

Jan 1, 2011

By N. Singh

Merensky Reef is mined extensively within the Bushveld Complex. In previously mined-out areas on the Merensky Reef horizon there are pillars, potholes and remnants that have not been mined. These unmined blocks of ground on the Merensky Reef horizon can influence the mining of the underlying UG2 Reef. The extent of the influence will depend on the size of unmined ground and the middling between the two reef horizons. This paper quantifies the influence of partially extracted Merensky Reef on mining of the UG2 Reef, and aims to provide recommendations for mining strategies, as well as regional and local support to achieve efficient and safe extraction of the UG2 Reef, for various middlings beneath the Merensky Reef horizon. In some cases it was found that relatively shallow UG2 Reef mining could encounter conditions similar to those experienced in deep and ultra-deep mining environments.

Jan 1, 2005

By D. J. Steynfaard

Sishen Iron Ore Mine is situated 280 km north-west of Kimberley in the Northern Cape Province of South Africa. The mine produces and sells high quality iron ore of various specifications to various national and international clients. The saleable product is derived from the blending and beneficiation of different types and qualities of hematite iron ore. This paper documents the new developments which were implemented (or are in the process of being implemented) on the mine in the long-term planning, medium-term planning, grade control and material tracking in the beneficiation plant with special attention being paid to the quality of the final, saleable product. The process starts with the long-term planning where the pit shell and pit optimization is determined by Whittle 4X. New developments include the introduction of a linear programming based scheduling system to enhance the long-term schedule generated by Whittle 4X. The LP route was decided on in order to take into account all the constraining factors of the final product that could not be configured in Whittle. To complement this the XPAC Auto Scheduler scheduling package was introduced to do the medium-term mine scheduling. This 18-month rolling plan includes cost parameters to enable the planner to extract a detailed operational budget from the scheduling while ensuring that production standards are maintained and grade constraints are met. The existing grade control system was enhanced with GPS capabilities and a computer system to do material tracking. The high precision GPS system introduced on the shovels allows for the accurate control of the loading procedures at the mining face. Because of the complicated geology and grade composition of blasting blocks it is imperative to accurately differentiate between different materials in the same blasting block and being able to excavate that with the loading equipment. The GPS system on the trucks allows for accurate location monitoring of dumping in order to keep track of specific material types. The state-of-the-art material tracking system developed for Sishen will enable the grade control officer to keep track and record various parameters of the material from its in situ position in the blasting blocks, through the crusher and onto different stockpiles, in various stages of the beneficiation process and onto the blending beds, into the dispatching trains and eventually into the ships for international distribution. These developments elevate the Sishen planning and grade control systems to a new level of service excellence from which management can obtain accurate and timely information on product status. It also enables Sishen to maximize resource utilization while still complying with the tough market constraints.

Jan 1, 2003

By J. Petersen, H. Naderi, M. H. Nikzad, M. Karimi

In this research, the thermodynamic study of sodium persulfate (Na2S2O8) solution in the presence and absence of H2SO4 and Fe3(SO4)3 was done. Eh-pH and equilibrium distribution diagrams were constructed using Outotec HSC Chemistry Software and the main stable ionic species were determined. Also, the mean activity coefficient and Pitzer model coefficients were evaluated. Effects of system composition, sodium persulfate concentration and temperature were investigated. According to the results, HS2O7 -, HS2O8 -, S5O3 2-, S4O3 2-, S3O3 2-, HS- and NaSO4 - are the main stable species in these three systems. Increasing of sodium persulfate concentration resulted in disappearing of SO4 2- and the appearance of NaSO4 -. The main effect of increasing the temperature from 25 to 75oC, is changing the stability regions of HS2O7 -, NaSO4 -, SO4 2- and S2-. From equilibrium studies, it was concluded that at 25 and 50oC, increasing the persulfate concentration results in a 55-60% decrease for HS2O7 - and an 20- 30% increase for HS2O8 -. At 75oC, HS2O8 - becomes the main species and its percentage decreases with increasing the persulfate concentration. Keywords: Thermodynamic, sodium persulfate, activity coefficient

Jan 1, 2020

By Jean Michel Marino, Jean-Pierre Slama

"The computer methods used by the French Commissariat a l'Energie Atomique, which are applicable to any type of ore deposits, are:(i) Ore reserve estimation. The data are either the core analyses or gamma leggings. To determine the spatial distribution of the ore, three different methods of interpolation are used. Two of these are based on the least-squares theory and the third one is an application of the regionalized variable theory. The interpretations of the orebody by the geologists are introduced in the computer program as often as possible.(ii) Optimal open pit design. From the spatial distribution of ore, the three-dimensional outlines of the optimal pit are determined by a geometrical algorithm which allows different slopes varying with the azimuth.Finally, the optimization of annual successive plans arc discussed."

Jan 1, 2014

By J. van Deventer

Testwork was done with two different adsorbents, Dowex-Minix gold-selective resin and activated carbon, to detemine their relative performances with regard to gold recovery from clarified low-grade solution employing a fixed-bed operation. The mill discharge from the milling-in-cyanide operation at a Witwatersrand gold mine was used as feed to the adsorption columns. A small amount of gold was leached during the milling process, so that this solution simulates, to a certain extent, a low-grade solution representative of a heap-leach operation. A speciation of the feed solution was done to establish which metal complexes were present in the milling-in-cyanide solution. This information was necessary to interpret metal loadings on the resin, as base metal cyanide species and their respective charges have an effect on the final gold loading capacity of the resin. Equilibrium isotherms were established for both adsorbents to estimate the rate of adsorbent flow anticipated for this specific feed solution. Breakthrough profiles were obtained at two different superficial linear velocities for each adsorbent. Mass transfer zone heights determined from the test work and the elution/regeneration time requirements were used to size a 150 m3/h full-scale plant for both adsorbents. A counter current configuration of adsorption columns, using three columns, should be suitable to recover gold effectively and to produce an effluent with a gold concentration below 0.01 mg/l. Based on the results obtained from the breakthrough tests, a preliminary techno-economic comparison was done between the resin-in-solution and carbon-in-solution options for the recovery of gold from low-grade solutions. This study indicated that the capital expenditure for a carbon-in-solution plant would be about 33 percent higher than that of a resin-in-solution plant. The operating expenditure for a resin-in-solution plant is expected to be only 60per cent of that for a carbon-in-solution plant. Keywords: resin-in-solution, carbon-in-solution, heap leach.

Jan 1, 2000

By E. Pezennec

A voluntary comprehensive environmental Risk Assessment was launched at the end of 2004 by the International Chromium Development Association. The completion is scheduled for mid 2006.EURAS, a leading environmental consultancy, was commissioned for this project, as this firm wrote in particular the Metals Environmental Risk Assessment Guidelines, the reference document for the metals and metals compounds, in particular for the forthcoming European new Chemical Policy and the Globally Harmonized System for the Classification and Labelling of Chemicals (GHS). This project follows a stepwise approach, comprising 3 distinct steps: - Initial Risk Assessment: compilation, evaluation of the existing effects and exposure data for chromium III compounds and chromium metal. This information will be used for the compilation of an initial Risk Assessment Report. - Data gap analysis: which type of additional effects data should be collected and/or which exposure scenarios merit a more detailed targeted risk assessment? Recommendations and/or suggestions for further research will be formulated. - Road map: prioritization and ranking of the different proposed research programs. The presentation will mainly focus on the results and recommendations of the initial environmental Risk Assessment from an International perspective and not from an European point of view. - Hazard assessment ? definition of the Predicted Non effect Concentration (PNEC) for each environmental compartment (water, sediment, soil) - Exposure assessment ? definition of the Predicted Environmental Concentrations (PEC) for each environ-mental compartment - Comparison of the local PEC with PNEC for the chromium III compounds and chromium metal EU industry sectors covered in the project: mining of chromite, metallurgical production of chromium metal, chromium containing alloys production, production of trivalent chromium chemicals and the main applications (pigments, leather tanning, etc..). The current status on the environmental Classification and Ranking for chromium III compounds, Chromium metal and its alloys in the GHS will also be covered.

Jan 1, 2007

By Z. Jin, Q. Yun, C. Lu

This paper presents a quantitative assessment model for the assessment of environmental load in gold production, which is based on environmental ecology, Life-Cycle Assessment and technical conditions of gold production in China. This model can make environmental assessment in terms of a set of indexes and quantitative approach by means of artificial neural network, which also improves the theory of Life-Cycle Assessment. Keywords: Artificial neural networks, Environmental load, Assessment, Utility function, Gold production

Jan 1, 2003

By C. Musingwini, A. S. Nhleko, M. J. Mahase

"In an environment like the mining industry, which is characterized by different stakeholders with multiple objectives, multi-criteria decision analysis (MCDA) is a useful approach for optimal decision-making. The application of MCDA techniques in the mining industry has predominantly been in mine planning and related problems, although no comprehensive survey has previously been undertaken to establish the application trends. A survey of the use of MCDA techniques was therefore conducted using case studies from the literature. It was noted that often two or more methods are applied to the same problem in order to increase confidence in the solution derived. As the number of criteria and alternatives increases, some methods become inefficient. A combination of the analytic hierarchy process (AHP) method with other MCDA techniques was the most frequently used approach, indicating the efficiency of the AHP method, especially when evaluating problems with more criteria and fewer alternatives. A combination of fuzzy theory with AHP or other methods incorporates uncertainty. The findings from the survey will benefit users applying MCDA techniques to solve mine planning and related problems.IntroductionA country’s natural resources serve the needs of different groups of people within the country. These different groups are collectively known as stakeholders (Herath and Prato, 2006). Stakeholders have different needs, preferences, and expectations, which describe and define the criteria to be considered in decision-making. The options available as solutions describe the alternatives in decisionmaking theory. The criteria and alternatives have to be evaluated simultaneously when making decisions, and this is when multicriteria decision analysis (MCDA) techniques become invaluable (Herath and Prato, 2006) because the human mind is considered to be limited when solving complex and intangible problems with several criteria and alternatives (Saaty, 2007). MCDA techniques belong to a broad group of techniques called multi-criteria decision-making (MCDM) techniques. The other group of techniques within MCDM comprises the multi-objective decision-making (MODM) techniques. MODM techniques are generally used to solve problems with an infinite number of alternatives, while MCDA techniques are generally used to solve problems with a finite number of alternatives (Musingwini, 2010)."

Jan 1, 2016

By H. H. Bird

The crux of reliable estimates of ore reserves lies in a comprehension of the related geological events and their controls on the formation and distribution of the economic mineralization, and on the rock types, lithology, and structures. Furthermore, mine geometry is based on the shape of the ore body, the types and distribution of the economic minerals, and the ground conditions. Asian mining The Institution of Mining and Metallurgy has been invited to organize an international conference on the occasion of the Asian mining 81 international exhibition.

Jan 1, 1980

By S. D. Viljoen

The use of ceramics to protect equipment subjected to wear in abrasive and corrosive applications has been accepted by most plants as the industry norm. Little is, however, known about alternative special ceramic based products which are available for the protection of plant assets. With careful engineering, impact resistant ceramics can be used in high impact zones using modern ceramic technology. Properly selected and properly installed, ceramics will provide a tough wear resistant lining for protection against abrasion and impact. Basalt, on the other hand, is widely used in coal washing plant process pipes with varying degrees of success. Basalt is normally not used for the lining of bends, ?T? pieces or reducers due to the reduced wear resistance compared to alumina ceramic. The advantage is a much reduced initial capital cost. A patented ceramic composite non-return valve solved an old problem encountered in the operation of medium sumps. The design approach overcomes the lack of functionality of alternative designs and reduces valve wear while preventing medium settlement during plant shutdown periods. Direct bonded ceramic pulley lagging is becoming the industry norm, eliminating most of the problems encountered with conventional pulley lagging systems.

Jan 1, 2010

By D. Grobbelaar, A. Cichowicz, D. J. Birch

The Q-coda method for estimating the quality factor Q(f)= Qo(f)n was used to characterize seismic wave attenuation in a region of the Kaapvaal Craton that includes the mining areas of the Bushveld Complex and Witwatersrand Basin. Seismic waveform data, collected by locally distant stations of the South African National Seismograph Network (SANSN), consisted of mining-related events with magnitudes ranging from ML 1.8 to ML 4. Q was calculated for nine different source-receiver pairs spanning the study region. A weighted average Q based on the number of available data gave an estimated attenuation relation for the study region of Q(f) = 327 f 0.81.

Jan 1, 2015

This paper pays tribute to the pioneers in geomechanics, and addresses some of the most pressing issues of our time related to deep mining, and how to mitigate these issues. Solutions developed by our predecessors seem to have reached their limits as mines continue to go deeper. The International Society for Rock Mechanics (ISRM) guidelines for rock mass characterization for excavation design also require re-thinking to reflect current knowledge and experience. Thus, a whole new approach is urgently required to increase mine safety and productivity. The paper will draw on the challenges and experiences in medicine and science that have been overcome through genuine collaboration, advances in technology, and impressive funding, which can be adopted to provide solutions to contemporary geomechanics challenges for increased safety and productivity as mines continue to go deeper.

Jan 1, 2014

By C. Ringas

Pipelines are used extensively in industry to convey various products. Internal corrosion of pipelines can lead to perforation and leakage of the product. A growing problem, not often accurately recognized, is internal corrosion of pipelines caused by bacteria. Microbiologically-induced corrosion (MIC) refers to corrosion caused by a variety of micro-organisms. This form of corrosion is not widely recognized in many industries, although it is widespread and causes many corrosion problems in pipelines, both internal and external. Sulphate-reducing bacteria (SRB) are responsible for the bulk of the corrosion problems caused by MIC. Corrosion caused by SRB is found extensively in water pipelines conveying raw, potable and waste water, as well as in pipelines conveying slurries. This problem also occurs in pipelines conveying crude oil. This paper describes internal corrosion problems of slurry pipelines caused by bacteria and outlines mitigation methods to improve slurry pipeline integrity, thereby extending the life of such pipelines.

Jan 1, 2007

By D. Nag, J. Fernando

Hazelwood Power Mine is one of the largest open pit brown coal mines in Australia. The removal of overburden is the first step in coal winning operation. The primary aim of construction of overburden dump is to provide an effective stable working surface for stacker. The paper discusses site investigation techniques used to determine dump soil properties, stability analysis method using GALENA and GWEDGEM, results of stability analysis. The paper concludes with recommendation for a safe dumping strategy for level 2 stacker dumping.

Jan 1, 2003

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