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By A. Sariisik

This study analyses the results of a pilot trial of a newly developed armed-chained stone-cutting machine. The machine was developed in Turkey and trialed at the Kaklik/Kocaba travertine quarries in the Denizli District. An armed-chained cutting machine is an alternative to the diamond wire cutting method more frequently used in the production of natural stone quarry blocks, and increases production efficiency and quality. Since there is no need to collapse the blocks using the armed-chained cutting production process, there is no risk of the block developing cracks. This results in a considerable increase in the efficiency of natural stone block production. The armed-chained cutting machine is easier both to assemble and run when compared to other block cutting methods. This process resulted in the production of a larger number of blocks at a lower cost within the same time frame, particularly in travertine quarries and in all other natural stone quarries. The block efficiency in travertine quarries was calculated as 65?80%using the armed-chained cutting machine, compared with 7?14% using the normal diamond wire cutting method.

Jan 1, 2010

By B. Solar Menéndez, M. B. Díaz Aguado, I. Á. Fernández, C. González Nicieza

The analysis of subsidence due to the opening of an underground void (mining, water exploitation or civil works hole) is a problem usually hard to solve. First of all, it requires a predictive model, in order to define both the displacement magnitude and area affected by subsidence. Such model should be validated with measurements of the actual movements sustained on the surface, in order to adjust it properly and enable influence of future behaviour in a reliable way. Two different kinds of problems might arise. On one side, it is necessary to control and measure surface movements in a very exhaustive way during a long period of time, beginning before underground works take place and finishing years after they are over. Furthermore, three factors bring in errors, some times of magnitudes higher than the displacement magnitudes measured. These include: the fact that reliable and long-term information cannot always be achieved; the precision of measuring devices; and the design of the topographical network itself. In addition, the predictive models more widely used only apply to certain excavation geometries, mainly to horizontal holes. In light of this background, the Group of Rock Engineering, of the University of Oviedo Mining Department, has developed a working methodology and a specific software tool, Subsidence 3D, to estimate ground displacements and strains. The program will allow for predictive models to be defined and also allows the treatment of data related with topographical marks and its comparative analysis with calculated results. The software has been programmed using Visual C++. Graphical outputs however are generated using AutoCAD 2000. This paper mainly refers to a practical situation, an underground coalmine, remarking the main difficulties arisen during the study of the available information and proposing how to solve them. A predictive model in subsidence 3D was established and validated. The actual behaviour of the ground was that in the model.

Jan 1, 2003

By C. -T. Mutale, A. S. Tuling

Titanium can exist in three different oxidation states. Its oxides are numerous and in presence of iron and oxygen, iron-titanium oxide compounds can also form. Some of the oxides are non-stoichiometric, making the determination of the thermodynamic properties of titanium and its oxides in molten steel and in slag difficult. Therefore, for the assessment of titanium activity in molten steel using the electrochemical measurements of oxygen partial pressure, the identification of oxides in equilibrium with titanium is important. This paper reports on an investigation of solid titanium oxide inclusions, which have been identified by combining different methods of analysis on quenched samples. These samples were taken from a Fe-Ti-melt at 1600°C, quenched in cold water then mounted and polished for optical microscopy. The oxide inclusions were analysed using transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS). Both single crystal and polycrystalline diffraction patterns were used to identify the oxides by comparing the d spacings with those in the ICDD X-Ray Diffraction (XRD) database. XRD was used to analyse the oxide particles on the top of slow cooled samples. It was found in the TEM study that the similarity of the diffraction patterns of the various phases meant that unique identification was difficult to achieve in some of the diffraction patterns. However, TiO, Ti2O3, Ti3O5, Ti4O7were identified in quenched samples, while TiO2, FeO.TiO2and iron oxides were seen in slow cooled samples. It was also confirmed that the type of oxides is related to titanium content of the samples. Keywords: Titanium, Titanium Oxides, Iron, TEM, XRD, thermodynamic.

Jan 1, 2004

By P. Falcão Neves

A detailed analysis of the geomechanical behaviour in rock cutting with a diamond saw is provided to obtain a better understanding of the mechanisms involved in the process. The energy of elastic deformation (before failure) and plastic deformation (post failure) was determined in uniaxial compression tests as well as the energy consumed per unit volume in the cutting process. The test samples are White and Ruivina marbles from Borba - Vila Viçosa in Portugal. Correlations between total deformation specific energy and cutting specific energy, normal and tangential forces and diamond indentation are analysed, and some conclusions are presented.

Jan 1, 2012

By W. I. van Drunick

AngloGold Ashanti Metallurgy has recently been involved in the successful installation of intelligent, expert control systems on the milling circuits. The benefits of expert systems in these highly interactive circuits are obvious. Existing comminution tools, which have been developed and can now be incorporated into online control, include improved modelling techniques and understanding, robust and competent simulation methods, sampling techniques, and optimization methods. The minerals processing industry has seen the benefits of predominantly research-based centres turning their focus to commercial applications of comminution circuit modelling packages, which in turn can be utilized within expert control systems. Expert mill control has been successfully installed at AngloGold Ashanti South Africa?s Mponeng and Kopanang Gold Plants. Expert control has also been installed at AngloGold Ashanti?s West African Sadiola Mine operation. The implementation of the systems has produced a number of positive outcomes. Plant surveys usually result in the identification of sub-optimal areas, and the control philosophy is then configured to ensure that these areas (along with the entire circuit) are optimized and maintained. Outdated PID loops have generally resulted in oscillatory control with large amplitude deviations from set-point. Significant improvements in SAR Metallurgy operations have been realized, firstly through achieving stability in the load and cyclone control, and secondly through online identification and implementation of optimized set-point conditions for mill mass, discharge density, etc. Soft sensors are configured to accurately estimate parameters that were historically not measurable, viz. breakage rate, mill load condition, onlinekWh/t-75 microns, mill discharge density and cyclone overflow grading. The Mponeng Plant system achieved circuit stability and improved overall grind. The Plant was able to pay back the control installation after 3 months, based on the additional recovery obtained from the finer grind. The system at Kopanang Plant has also resulted in enhanced plant recovery as a result of a finer grind and a lower residue gold content. The payback for this system was calculated at approximately 6 months. AngloGold Ashanti Metallurgy is currently expanding the installation of expert control to its other operations. It is also evaluating the performance of various suppliers of advanced control systems.

Jan 1, 2005

By W. P. Johnstone

The computer assisted generation of geological models to represent the geometry of, and grade distribution within, orebodies is a rapidly growing area of the geological profession. Such models are increasingly used as a necessary starting point in determining the mineability of mineral deposits in terms of practical mine design and economic considerations. The transition from traditional techniques such as field or underground mapping and the manual calculation of grade and tonnage estimates, as well as related activities such as the interpolation of cross-sections, the use of stereographic projections, core logging and hand contouring, to computerized applications, is by no means complete. In fact, many geological professionals deliberately avoid the use of computer simulations based on the perception that the resulting models are simplistic and that their construction is not founded on sound geological principles. The purpose of this paper is to assess current thinking on this topic by considering; (a) an overview of advances in the drafting of geological maps, (b) the theoretical basis for multi-dimensional geological modelling, (c) the case for combining traditional and modern techniques, and (d) the benefits to the mining value chain.

Jan 1, 2003

By F. Peer

In most coal preparation processes, water is a necessary medium, but the presence of water in coal after it has been cleaned has a negative impact on transportation costs, handling and specific energy values. The utilization of super absorbent polymers (SAP) in the nappy application is well known. The concept of utilizing these polymers was investigated for the purposes of dewatering coal and other fines, generated by preparation processes such as flotation. SAPs are granular highly cross-linked synthetic copolymers with excellent water-absorbing properties. The dewatering process is characterized by three main stages: (a) contact of super absorbent polymer with high-moisture fine coal; (b) separation of dewatered fine coal from super absorbent polymer; and (c) regeneration of used super absorbent polymer, by exploiting its response to changes in conditions such as pH or temperature. Preliminary tests showed the separation step to be very difficult. The novel idea of encasing a given amount of polymer in a water permeable cloth solved this problem (of separating the swollen polymer from the dewatered coal). Preliminary tests investigating the effectiveness of the sachets of polymer showed a drastic decrease in the moisture contents of slurries. Furthermore, it was shown that it was possible to regenerate the polymer (still within the sachets) through thermal drying. A full-scale experimental programme was then followed to accurately determine the feasibility of using sachets of SAP. The experimental variables were initial slurry moisture content and polymer dosage. It was observed that the sachets seemed to work fastest and most effectively at high moistures and also at higher dosages of SAP. Regeneration of the polymer was also investigated, using two methods: thermal regeneration and pH-induced regeneration. The experimental variables, for investigating the regeneration process, were method of regeneration and grade of water used. Thermal regeneration at 70°C seemed to work successfully. Although the cost of using thermal energy is still a problem, the safety aspect (fire hazards) has been addressed since the polymer does not ignite when heated, unlike fine coal particles that may do so. The alternative method of regeneration, which exploits the pH-sensitivity of the polymer, was less successful, and further work needs to be conducted.

Jan 1, 2003

By W. P. Roux

Owing to decreasing high-grade ore reserves, there is a need for better understanding of the jigging process to improve the recovery efficiency of finer, lower grade material. The use of positron emission particle tracking (PEPT) was examined as a technique to study the motion of iron ore particles inside a laboratory batch jig. PEPT is a non-invasive method that can provide three-dimensional kinetic data on a particle in laboratory-scale processing units and has been successfully used to study mills, hydrocyclones, and flotation. Experiments were conducted to determine whether PEPT would be a viable technique to study iron ore jigging and what valuable information could be obtained. The results indicated that detailed information on the stratification rate of a particle could be obtained, with adequate resolution to track the particle?s movement through an individual jig pulse.

Jan 1, 2014

By H. Dong

This paper presents a heat conduction model to determine the erosion profile of freeze linings in a ferronickel submerged arc furnace. Kirchhoff transformation was adopted to simplify the nonlinear equation governing heat conduction. The boundary element method (BEM) and Nelder-Mead simplex optimization method were employed to solve an inverse heat conduction problem. Erosion profiles could be obtained when calculated temperatures at sensor locations agreed well with measured temperatures. The model was validated by comparing the heat loss through the linings, which was calculated by BEM and integral operation after erosion profiles were obtained, with the value calculated from industrial data such as actual power consumption, tap-to-tap time, and ferronickel output. The optimal solution for the erosion profile could be acquired when the difference in heat losses calculated by these two methods is at a minimum.

Jan 1, 2014

By A. Sandberg, M. Nzotta, Du Sichen, N. N. Tripathi, K. Beskow

The present study was carried out to investigate the impact of slag refractory lining reactions on the formation of inclusions during ladle treatment of steel. The experiments were conducted on an industrial scale in the ladle at Uddeholm Tooling AB in Hagfors, Sweden. The inclusion chemistry and population during ladle treatment were studied along with the composition of the ladle glaze, taken from the ladle lining. The inclusions in the steel were classified into four groups according to the Swedish standard SS 111116. SEM/EDS analyses were carried out to identify the phases present in both the inclusions and the ladle glaze. The number of inclusions in the steel before deoxidation was found to increase with the ladle age, i.e. the number of times the ladle had been in use. A similar increase was also found after vacuum degassing and before casting. A great portion of inclusions before casting was found to be supplied by ladle glaze. This observation was further confirmed and explained by thermodynamic analysis. The present results show that ladle glaze is a major source of inclusions in the ladle at Uddeholm Tooling. Keywords: Slag/ refractory/ lining?reactions, ladle glaze, inclusions, inclusion chemistry, ladle treatment

Jan 1, 2004

By C. Musingwini

The subject of optimal planning of level and raise spacing for inclined narrow reef deposits has received intermittent attention over the years because the subject matter is inherently complex. Previous work has approached the problem as simply that of simultaneously minimizing the total excavation and haulage cost associated with the development workings. However, when level and raise spacing are altered, other factors such as productivity are negatively affected, thus requiring a delicate trade-off of contradicting planning or optimization criteria. The paper concludes that the problem is actually of the multi-criteria decision analysis (MCDA) type, contrary to traditional thinking that the planning problem is achieved solely by minimizing waste development.

Jan 1, 2010

By J. H. Maritz, Uludag. S.

"*Paper written on project work carried out in partial fulfilment of B.Eng(Mining Engineering) degreeAfriTin Mining Limited plans to reopen the Uis tin mine in Namibia and establish a pilot processing plant for phase 1 of the Uis tin project, which is scheduled to commence in the last quarter of 2018 . A mining plan is required for phase 1 to supply the new pilot processing plant with 500 kt of run-of-mine ore per annum, for a period of 5 years. New geological mapping and three-dimensional modelling of the mining area were utilized to identify the most optimal mining locations that require low initial waste stripping. An open-pit mining method was selected to target the surface outcrops of the pegmatite orebodies. The mine design criteria were determined and used as input to generate the mine design by utilizing professional engineering software. The mine design was optimized and an overall stripping ratio of 0.81 was achieved. A 5-year production schedule was developed for the mine design according to quarterly periods of three months. A fixed production target of 125 kt of ore was assigned to the quarterly periods, and a ramp-up production target of 65 kt of ore was assigned for the first period. The mobile mining equipment requirements were calculated, and recommendations were made for implementing the 5-year mining plan. IntroductionAfriTin Mining Limited is the owner of the Uis tin project in Namibia and plans to reopen the Uis tin mine, which is located near the town of Uis, approximately 164 km north of Swakopmund. The Uis tin mine was owned and operated by Imkor Tin, a subsidiary of Iscor South Africa. Mining commenced in 1958, and the operation was closed in 1991. Steffen Robertson & Kirsten (SRK) defined the life of mine (LOM) plan for the historical Uis mine in 1989. The SRK report estimated the historical resources and reserves, which consisted of sixteen cassiterite-bearing pegmatite orebodies. SRK developed the most economical pit designs to provide the highest average tin grade at the lowest practical waste stripping ratio. Exploration data from the SRK report of 1989 was used extensively throughout this study, since no new exploration drilling has been conducted. The pegmatites are present as large, subvertical and outcropping veins up to 100 m in thickness. Once phase 1 is operational, mining will be conducted using conventional open pit mining methods. Initial production will be from exposed pegmatite veins in the old mine workings. AfriTin plans to establish a pilot processing plant by the end of 2018 to beneficiate run-of-mine ore at a rate of 500 kt per annum."

Jul 1, 2019

By M. J. King, A. Weissenberger, W. G. Davenport

Keywords: Pyrometallurgy, sulphuric acid, sulphur dioxide The raw material for sulphuric acid manufacture is clean SO2 gas. It comes from (i) burning molten by-product sulphur; (ii) roasting or smelting metal sulphide concentrates, and (iii) decomposing contaminated organic chemical process sulphuric acid catalyst. Efficient gas cleaning is required for metallurgical and contaminated acid decomposition gases, especially the former. Sulphuric acid is made from SO2 gas by (i) oxidizing the SO2(g) to SO3(g) in contact with supported liquid-phase catalyst then (ii) reacting the resulting SO3(g) with the water component of 98.5 mass% H2SO4, 1.5 mass% H2O acid. This paper discusses the reasons for these process steps and indicates how acidmaking can be controlled and optimized. Special emphasis is placed on SO2(g) oxidation efficiency and how it is influenced by feed gas composition, feed gas temperature, catalyst composition, catalyst bed pressure, number of catalyst beds, and double versus single contact acidmaking. In addition, a review of various other treatment methods for SO2-bearing gases is provided. A brief description of each process is included along with commentary on their technical and economic applicability for use at metallurgical facilities.

Jan 1, 2006

By I. C. Spangenberg

The status of sampling practices in the gold mining industry in Africa was determined as an initial step in a process to standardize sampling practices in the mining industry. Twenty-one gold mines, twenty metallurgical plants, and thirteen laboratories were rated for the potential influence of the relevant sampling errors on each component of the particular sampling system. The findings of the study on the status of equipment, standards, procedures, and management principles were presented in a dissertation (Spangenberg, 20121) and are now used by AngloGold Ashanti?s mines in the quest for correct sampling practices. The information is also used to compile a guideline on leading practice procedures for sampling methods in gold mining. This article is an overview of sampling best practice found in African mining Keywords theory of sampling, best practise, sampling errors, sampling standards.

Jan 1, 2014

By P. Share

As part of JAGUARS (JApanese-German Underground Acoustic emission Research in South Africa), high-resolution tiltmeters were installed during 2007 at Mponeng gold mine, South Africa, in an attempt to study and understand the risks posed by in-mine seismic events and to subsequently use the knowledge gained to mitigate these risks. In December 2007, an M2.2 event occurred at Mponeng and was detected by the tiltmeters installed. The tilt expected for the M2.2 event is modelled through the use of numerical and analytical tools and utilizing, as input parameters, characteristics of the event such as the rupture area, the amount of slip, elastic properties of the rock, the state of stress before the event occurred, and frictional parameters of the rupture. The calculated tilt values are correlated and compared with the recorded data, and are found to be of the same order. Certain input parameters, such as the initial rupture point, are further constrained by varying them, during modelling, until the calculated and observed tilt values are approximately equal. From modelling, it can be concluded that the rupture point had to be closer to the location of the tiltmeters. In addition, possible locations acting as source areas for the observed aftertilt are determined. Further modelling still needs to be done to quantify the effects of the tunnel close to the tiltmeters and plastic deformation of the rock mass. Keywords high-resolution tilt data, Mponeng gold mine, M 2.2 seismic event, analytical modeling, numerical modeling, rupture plane.

Oct 1, 2013

By D. Limpitlaw

The origins of mine closure practice have influenced the way in which it is implemented by companies and regulators. Mine closure practices essentially started developing in the 1970s in countries with advanced economies and mature mining industries. In these settings, the emphasis was justifiably placed on restoration of the landscape and an attempt was made to return to the ?natural? pre-mining land cover. These practices continued to evolve and incorporated socio-economic and cultural aspects, especially after the Brundtland Report in 1987 and the subsequent Earth Summit in 1992. Today mining is increasingly occurring in remote parts of developing countries where there may be significant need for infrastructure such as roads, clinics, and schools. The costs of returning land to low (economic) value pre-mining use may be far greater than establishing a viable postmining land use that could potentially add value to the community and take pressure off sites for greenfield development elsewhere. Furthermore, natural resource limitations (such as topsoil availability) may limit the degree to which the historical land cover can be re-established. Establishing post-mining land uses may aid in mitigating the loss of employment that is inevitable when mines close. Stakeholder participation in establishing post-mining land cover and land use options is critical for long-term success. Similarly, third parties must be identified to support the development of the post-mining land use This paper draws on the experience of the authors in several developing countries and presents a case for maximizing re-use of mining infrastructure. The paper does not advocate the adoption of poor rehabilitation standards, nor or the wholesale destruction of land capability, but rather leaving key infrastructure in place for post-mining use that may support sustainable development.

Jan 1, 2014

By André de Jager, Henk Ludik

Navachab Mine experiences difficulties with pit wall stability in certain areas of the mine. The main reason for the instability is the fact that the geology comprises many joints and faults. Blasting, without impacting negatively on the stability of the pit walls, poses a major challenge. The mine has installed a technologically advanced seismic monitoring system with monitoring sensors positioned at various locations and depths throughout the pit. The electronic data recording system records all relevant information on a continuous basis with early warning signals in cases of potential danger. From the information recorded by this micro-seismic system it was established that the energy release into the high-wall is predominantly influenced by the mining rate, water content and mining tempo and to a lesser extent by the blasting operations. To limit the negative effects of blast vibrations, the use of Electronic Delay Detonators (EDDs) was introduced. The optimal delays were determined through signature trace analysis. The vibrations obtained during blasts initiated by means of electronic delay detonators were monitored and compared to those traditionally obtained when standard pyrotechnic delay detonators had been used. The measured vibration data indicated an improvement of 25% to 100% drop in vibration amplitude compared. The accuracy and programmability of EDDs presented huge potential for blast optimization in terms of limiting the vibrations without compromising fragmentation. The whole project was conducted over a twelve week period with some 4000 EDDs. The average size of a blast was in the order of 350 holes using about 40kg explosives per hole, which equates to 14,000 kg explosives over 12 different blasts. The paper deals in detail with the blast optimization process with regard to: - determining the rock response time; - establishing the signature traces; - analyzing the wave interference patterns; - predicting the direction of constructive and destructive wave interferences; - optimizing of the inter-hole and inter-row delay periods; - measuring the ground vibrations. The results obtained during electronic blasting are compared to those obtained during pyrotechnic blasting. Comparisons are being made with regard to the following: - ground vibration measurements; - pit wall stability measurements; - blast safety.

Jan 1, 2006

By M. K. Pelser

The purpose of this paper is not so much to provide a scientific study of the selection process for the perusal of other psychometrists or industrial psychologists?the purpose is to provide line management with a practical, relatively user-friendly guide to fair and scientific selection. The main areas that are to be covered are: ? Why fair and scientific selection? ? Job analysis ? The job requirement?selection technique circle ? Assessment centres in the mining industry?the Tavistock Collieries Ltd experience. Why fair and scientific selection? Seen from a line manager?s perspective, fair and scientific selection should be pursued for two main reasons: ? to remain within the ambits of the law ? to maximize the probability of selecting the potentially most productive and efficient candidate for the job.

Jan 1, 1997

By R. G. Votteler, A. C. Brent

"The business performance of mining corporations in South Africa is adversely affected by the constantly increasing electricity costs. The most commonly used power sources are the national utility supplier via a grid connection, and on-site diesel generators. Previous research has identified the renewable sources of solar photovoltaic (PV), onshore wind, and geothermal energy in hybrid versions with current sources as possible opportunities to counteract rising electricity costs. To provide a clear understanding of the new, developing market of renewable energy sources, this research is divided into two papers. This first paper investigates the internal business structure of mining corporations in order to evaluate electricity generating sources. The multi-criteria decision analysis (MCDA) method is selected as the most suitable approach for this. The paper identifies the criteria used by mining corporations to evaluate possible electricity generation sources for self-generation by means of the corporations’ own investment. Four mining corporations with several mining locations were interviewed. The interviews revealed both new and identical evaluation criteria when the findings were compared to earlier MCDA adaptations analysed in the literature review. The second paper (Part 2) combines current knowledge about the external macroeconomic environment with the findings about the internal environment described here. MCDA is adapted in Part 2 and implemented to analyse and compare current to hybrid renewable sources from the perspective of mines. IntroductionMining corporations in South Africa are currently adversely affected by increasing electricity prices. Electricity is supplied mainly by Eskom1 and, especially in remote locations, by on-site diesel generators (Boyse et al., 2014). Electricity price increases, emanating from diesel price hikes and Eskom, have escalated the total operational expenditure on electricity by the largest mining corporations from 8% to 20% of total operating costs in the past seven years (EIUG, 2015). The reliability of electricity supplied by Eskom has decreased drastically (Govender, 2008), and the prices will increase annually by at least 13% until 2018 (Numbi et al., 2014; Eskom, 2015b). In addition, the South African government plans to introduce a carbon tax on greenhouse gas emissions (Alton et al., 2014)."

Jan 1, 2017

In ilmenite smelting, the FeO content of the feed material (nominally FeO.TiO2) is decreased by reduction with carbon. In a parallel reaction, a significant amount of the TiO2 is reduced toTi2O3. One of the striking features of these reactions is a consistent relationship between the extents of FeO and TiO2 reduction; this relationship is independent of furnace size. It was recently proposed that this relationship follows from the solidification behaviour of the slag, where the final slag composition corresponds to the minimum melting point (?eutectic groove?) in the FeO-TiO2-Ti2O3 phase system; the hypothesis is that solidification equilibrium with the freeze lining stabilizes the slag composition. If this is the case, the system of slag and freeze lining must be capable of correcting two types of disturbances: thermal and compositional. Thermal disturbances result from incorrect power input, for the feed rates of ilmenite and reductant. For example, excessive power input will tend to overheat the slag, causing the freeze lining to melt partially, establishing a new steady-state heat loss from the furnace. Compositional disturbances result from an incorrect reductant input for the given power and ilmenite input. In this work, the dynamic response of the slag and freeze lining to different inputs (flow rates of ilmenite and reductant, and power input) is modelled. The model is based on solidification equilibria, and quantified heat loss through the freeze lining. The conclusion is that the solidification equilibrium cannot constrain the composition to the eutectic groove for typical operating conditions. Keywords: ilmenite smelting, freeze lining, solidification, high-titanium slag

Jan 1, 2004