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By M J. Daniel

The diamond industry is no newcomer to High Pressure Grinding Rolls (HPGR) as it has used the technology for more than 20 years, predominantly in secondary crushing and recrushing roles. In fact it could be argued that the diamond industry has led the way for the wider minerals industry to consider its application. In existing conventional secondary cone crushing applications, large valuable diamonds are" won" through meticulously managing the recovery process within defined particle size ranges. Conventional crushers operate with relatively large closed side settings, but have the potential to damage diamonds by making direct contact with the sides of the crusher. Cone crushers also result in steep product size distributions that run a high risk of losing many of the smaller, unliberated but more abundant diamonds from the rock. This current comminution paradigm of particle size reduction management results in recrushing processing applications or plants where HPGRs are often used.

Jan 1, 2010

By L. C. Woollacott, A. K. Tripathy, J. H. Potgieter

This paper presents the second of a two part study on density stratification in a laboratory batch jig. The first study, reported elsewhere, investigated the effect of operating conditions on the stratification profile achieved at equilibrium. The study reported in this paper investigated their effect on the kinetics of density stratification under 18 different sets of operating conditions - five for binary systems with different particle densities; and 13 for a ternary system with different configurations of the jig cycle. Although the study was academic in nature (it involved simple systems of 8 mm glass beads) it has a number of practical implications. It found that the most influential operating variables affecting stratification kinetics are the amplitude of water displacement, the pulsion hold time, and, to a lesser extent, the pulsion time. It also found that reasonable rates of stratification can be expected in systems with density differences as low as 237 kg/m3 but below this the kinetics deteriorate significantly. The two studies together suggest that, within a broad range of operating conditions, the equilibrium stratification profile is independent of control variables and it is the control of stratification kinetics that has the primary influence on the quality of density separations in a jig. Keywords: Jigging kinetics, stratification, equilibrium stratification, batch jig

Jan 1, 2020

By L. Robles-Stefoni

"Multiple-point simulation (MPS) methods have been developed over the last decade as a means of reproducing complex geological patterns while generating stochastic simulations. Some geological spatial configurations are complex, such as the spatial geometries and patterns of diamondbearing kimberlite pipes and their internal facies controlling diamond quality and distribution.Two MPS methods were tested for modelling the geology of a diamond pipe located at the Ekati mine, NT, Canada. These are the single normal equation simulation algorithm SNESIM, which captures different patterns from a training image (TI), and the filter simulation algorithm FILTERSIM, which classifies the patterns founded on the TI. Both methods were tested in the stochastic simulation of a four-category geology model: crater, diatreme, xenoliths, and host rock. Soft information about the location of host rock was also used. The validation of the simulation results shows a reasonable reproduction of the geometry and data proportions for all geological units considered; the validation of spatial statistics, however, shows that although simulated realizations from both methods reasonably reproduce the fourth-order spatial statistics of the TI, they do not reproduce well the same spatial statistics of the available data (when this differs from the TI). An interesting observation is that SNESIM better imitated the shape of the pipe, while FILTERSIM yielded a better reproduction of the xenolith bodies. IntroductionThe simulation of geological units poses several technical problems that challenge the capabilities of available geostatistical simulation approaches and their ability to deal with spatial complexity of categorical variables. The spatial geometry of diamondbearing pipes and their internal facies controlling diamond distributions are a specific and well-known difficult modelling problem. The geometry of a kimberlite pipe is typically like an inverted cone (Figure 1); the wider part is known as the crater and is located near the surface, and the narrower, deeper part is known as the diatreme. Xenolith bodies can also be found inside the pipe. A very important contribution to the geological modelling of the contours of the pipe is the measure of uncertainty about the location of the contact between the kimberlite pipe and the host rock."

Jan 1, 2016

By A. Yañez, J. Yianatos, P. Vallejos, R. Grau

This paper presents an evaluation of the effect that the mineral feed characteristics have on the metallurgical performance in an industrial flotation circuit. Variables such as mineralogy, particle size, solid content and mineral grade were evaluated using a flotation simulator, which was previously developed and validated using industrial data from different concentrators. The metallurgical performance was evaluated not only from the point of view of recovery and concentrate grade, but also by analysing less common variables such as froth carrying rate, froth and collection recovery, water recovery and others. Then, new data from the industrial flotation circuit was used to complement this analysis and evaluate the simulator predictability by comparing simulated and measured data. The results allowed for the quantification of the significant effect that mineralogy and particle size have on recovery and/or concentrate grade. Therefore, the grinding stage and flotation cells design become important factors to avoid a significant loss in metallurgical performance when feed mineral characteristics change in an industrial operation. In this context, an evaluation of cells design and arrangement should be performed to compensate the loss in recovery and concentrate grade in order to find an optimal operating condition. Keywords: Flotation circuits, mineral feed, modelling, particle size, liberation, mineralogy

Jan 1, 2020

By and Z. S. Abisheva, Z. B. Karshigina, Ye. G. Bochevskay, A. S. Sharipova

The production of precipitated silica in the United States is about 145,000 tons of SiO2 and its prices vary significantly (from $ 1 to $ 4.5 per kg) depending on the area of its application. One of the most important parameters is its specific surface characterising dispersion (particle size and shape, presence or absence of pores), at a certain value of which the material acquires new properties and quality. At present, a technology has been developed for processing slag from phosphorus production to produce precipitated silica (‘white soot’) with a high specific surface and the possibility of extracting valuable components such as rare-earth metals (REMs) into a product enriched with them has been shown. However, the content of impurities in the deposited silicon dioxide, such as aluminum and iron, is above acceptable limits and may affect the quality of the final products. Therefore, along with the structure and specific surface, a very important characteristic of ‘white soot’ is the chemical purity of the material. In turn, calcium oxide occupies a significant share in the concentrate of rare-earth metals, which affects the content of ΣREMs oxides, which does not exceed 17.3 %. The low content of a valuable component may affect the feasibility of further processing. For the most complete utilisation of phosphorus slag, the authors propose a method for their acid processing, which allows for minimising the conversion of impurities to finely divided silica and collective concentrate, which will improve the quality of these products. Keywords: Phosphorus slag, precipitated silicon dioxide, rare earth metals, leaching, white soot, specific surface, technology

Jan 1, 2020

By I. Y. Motovilov, S. A. Telkov, M. B. Barmenshinova, Z. S. Abisheva

As a rule, removing waste rock at the beginning of the process improves the conditions for the flotation of minerals, and also reduces the operating costs of crushing, grinding and flotation. Lead-zinc ores in the Shalkiya deposit of the Republic of Kazakhstan are classified as difficult for enrichment, but taking into account their significant reserves, they are one of the main potential ores for the production of lead and zinc. Under industrial conditions, for processing ores of the Shalkiya deposit, a selective flotation concentration scheme with the production of lead and zinc concentrates is recommended. However, according to the recommended scheme, it is not possible to obtain high-quality concentrates of lead and zinc, with high metal recovery. The paper presents the results of studies of preliminary gravitational enrichment of lead-zinc ore in the Shalkiya deposit. Based on the fractional analysis for the particle size range of -40+8 mm, Henri- Reingard enrichment curves were constructed, separation density (2730 kg /m3) was established to isolate the light fraction with the lowest possible lead and zinc content, and gravity enrichment indices (0.7-0.71) were determined. It was found out that when using gravitational enrichment of the original large-sized ore in the Shalkiya deposit, tails are released at the beginning of the technological process with a yield of up to 20% with the extraction of silica up to 30%, calcite up to 11% and carbonaceous matter up to 12%. As a result of the studies, it was found that the beneficiation of crushed lump ore could be conducted in heavy suspensions. One of the positive aspects of the use of gravitational enrichment is the reduction of energy costs for grinding the heavy fraction, which was experimentally proved in this article. Keywords: Lead-zinc ores, Shalkiya deposit, fractional analysis, gravitational enrichment, floating fraction, sunken fraction, separation density

Jan 1, 2020

By Z. Botha

Sheryl Sandberg, the COO of Facebook, published a book titled 'Lean In', where she invites women to sit at the table. In summary, to 'sit at the table' entails not only embracing opportunity, but to actively seek out opportunities in leadership positions. Sandberg points out that, unfortunately, apart from institutional obstacles, a woman's own perceived limitations have a negative impact on her leadership ambitions. To create an environment where diversity will flourish, where everyone has a seat at the table and everyone has a voice, safety must be established first. To establish safety within a diverse team, there is power in relationships and connections. This study will first and foremost review theories in literature as to why diversity and inclusion are so important and the value that diversity brings to our industry. The study also recommends a few focus areas for improving diversity and inclusion in the industry.

Sep 1, 2022

By M. S. Moholwa, J. D. Steenkamp, H. L. Rutto

Manganese ores are the major source of manganese for the production of manganese ferroalloys. There is a gap in the knowledge of the decrepitation behaviour of manganese ores, which presents a problem in the operation of smelters. Decrepitation, which is the breakage of the ore particles upon heating, is an important quality parameter for these ores. The purpose of this investigation was to determine the extent to which South African manganese ores decrepitate during preheating in a rotary kiln. The effects of temperature, rotational speed, and particle size decrepitation were investigated. Manganese ores were heated in a laboratory-scale rotary kiln at temperatures of 600, 800, and 1000°C, and rotational speeds of 3, 6, and 12 r/min. The size ranges were +6-20, +20-40, and +40-75 mm and the residence time was constant at 30 minutes. The decrepitation index (DI) is quantified as the ratio of the mass of <6 mm particles after pre-heating to the total mass of the sample. It was found that the DIs for all ores used were proportional to the temperature and the rotational speed and inversely proportional to the particle size range with temperature being the most important parameter. Ore A was the most susceptible to decrepitation followed by ore C and ore B; this was mainly to the decomposition of kutnohorite, the content of which was the highest in ore A and the lowest in ore B.

Nov 30, 2022

By A. Buncombe

In March 1984, two years&apos; work by senior metallurgical personnel from the six major mining groups culminated in the formation of the Mine Metallurgical Managers&apos; Association of South Africa. This Association has joined a group of specialist Associations operating within the South African mining industry whose aims are to uphold the standards and promote the interests of their various professions.

Jan 1, 1987

By Z. Leng

"After detonation of the explosive, the final blast-induced damage area around the blast-hole falls into three categories, namely crushed zone, fractured zone, and elastic deformation zone. This paper presents a modified model to calculate the size of crushed zone around a blast-hole in drill-and-blast, with the hoop compressive stress and cavity expansion effect taken into account. The material in the crushed zone was assumed to be a granular medium without cohesion, but with internal friction. On this basis, the formula for crushing zone radius was derived. The proposed approach was verified with tests reported in the literature and the simulated results from SPH-FEM coupled models. A full statistical analysis was also carried out, and the predicted values were found to be in better agreement with the test results compared with other models. A sensitivity analysis of the modified model showed that the size of the blast-induced damage area is mainly affected by the following factors: rock mass properties, in situ stress, and borehole pressure. In particular, the roles of borehole pressure and in situ stress are discussed. Finally, suggestions are made on how the size of the crushing zones can be decreased. IntroductionOver the past decades, drill-and-blast has become the most commonly used technology in rock excavation. It is well known that in rock mass fragmentation with explosives, the annular rocks around the blast-hole are converted into fines. The formation of these fines consumes a significant part of the energy of the detonation, which in general is ignored in the determination of the efficiency of detonation (Glatolenkov and Ivanov, 1992; Furtney et al., 2012). Many studies show that only 20–30% of the total explosive energy is effectively used in fragmenting the rock, and up to 50% of the energy generated by conventional charges is wasted in overcrushing of the crushed zone and the inner part of the fractured zone (Ouchterlony et al., 2004; Sanchidrian et al., 2007). How to control the crushed zone to enhance the effective utilization of explosive energy, reducing the unit explosive consumption and the engineering cost, is therefore of great significance."

Jan 1, 2016

By O. K. H. Sheff

An editorial in the April 1990 edition of Mining Magazine is worth a wider audience in South Africa, particularly as the SAIMM enters its own centenary decade and the process of change in the minerals industry world-wide makes increasing demands on the professionalism of its leaders. The editorial considers the changing status of engineers, who up to the 1880s had been held in high regard by society. Alumina and bauxite Economists forecast a slower economic growth rate in 1990, but expect continued increase in demand for aluminum at a 3 per cent annual rate during the decade. Structural and numerical analysis Struceng & Femcad (structural analysis and finiteelement method) is a conference and exhibition that is to be held in Grenoble (France) on 17th and 18th October, 1990. It is sponsored by the Institute for Industrial Technology Transfer (ITT-International).

Jan 1, 1990

By C. J. Lenz

The results of prospecting operations involving geological data and a large number of geochemical determinations of the metal content of soil samples are plotted and evaluated by computer. Anomalous areas are identified in each type of environment by selecting probability or population boundary values from frequency distributions. The anomalies are plotted to permit correlation with geographical or geological features. Ranking of prospecting targets is made using geographic pattern, geology, absolute value and metal ratios. Three short case histories are presented.

Jan 1, 2014

By A. W. S. Schumann

A. W. S. Schumann The first reason for todays success lies in the very high standard which was set by our speakers today and I think that we owe a very special vote of thanks to Messrs P. M. C. Wilson, A. A. Oakes, M. J. Deats, A. C. Coetzee, R. E. Burnton and J. G. Ferguson. This, however, cannot account for the fact that there was a tremendous response even before anyone knew who was going to speak or what they were going to speak about. I suggest that the response was enthusiastic because people expected a more informal gathering with a greater opportunity for feedback, for an exchange of views and for questions and answers. The very popularity of the idea has defeated its own ends to some extent. This gathering is too big and many people must have been left with questions unanswered. Possibly one should arrange for a number of meeting places-there are many in the Chamber and the surrounding mining houses-and then have separate meetings in the morning with joint reporting session in the afternoon. Alternatively, we could have a symposium after the colloquium, using Webster&apos;s definition of a symposium as as &apos;a drinking party of merry fellows&apos;. We all know that it is easy to discuss mining into the small hours. Obviously one cannot summarise todays papers and discussions, but I would like to make a few comments on technical matters and after that I would like to speak for a moment about what I see as major trends or tendencies which arise from discussions of this nature. Regarding the question of placing a village on a mine or away from a mine, I would mention that there is quite a body of literature on the adverse sociological effects on the development of children in any community in which the great majority of parents share the same occupation. It is something to be avoided if possible. We discussed the concept of the moving stockpile. If this is proved to be successful, it could save a considerable amount of money for Escom who could then avoid the construction of very large and costly staithes which are now regarded as parts of power stations. One does not see why both a moving stockpile and a staith should be necessary. By the way, speaking of Escom, I see that Mr Bob Scott is here; he has stopped pulling my leg by saying that we sell stone to Escom; perhaps someone has told him that if this is true, it must be the cheapest stone you can buy in this country. My next point relates to the use of epidiascope. It struck me again that this instrument which provides a visual image to accompany your message, can be very effective if it is properly used. These papers speak of a great deal of hard work which went into their preparation, and one really feels that the authors should have taken a few minutes more to prepare their drawings specifically for the epidiascope. There should be nothing on the drawing which is not necessary to illustrate a particular point and there should be nothing on the drawing which is not visible from the back of the hall. In particular, if one cannot read the figures along the sides, then one

By Mr P. W. J. van Rensburg

SOUTH AFRICAN NATIONAL COMMITTEE ON TUNNELLING In 1970, the South African Institution of Civil Engineers, the South African Institute of Mining and Metallurgy, the South African Institute of Mechanical Engineers, and the Geological Society of South Africa held an international conference on tunnelling, known as Tuncon 1970. SUID-AFRIKAANSE NASIONALE TONNELBOUKOMITEE In 1970 het die Suid-Afrikaanse Instituut van Siviele Ingenieurs, die Suid-Afrikaanse Instituut vir Mynbou en Metallurgie, die Suid-Afrikaanse Instituut van Meganiese Ingenieurs en Die Geologiese Vereniging van Suid-Afrika &apos;n internasionale konferensie in verband met tonnelbou gehou, wat bekend gestaan het as Tonkon 1970.

Jan 5, 1974

AFRICAN NATIONAL COMMITTEE ON TUNNELLING In 1970, the South African Institution of Civil Engineers, the South African Institute of Mining and Metallurgy, the South African Institute of Mechanical Engineers, and the Geological Society of South Africa held an international conference on tunnelling, known as Tuncon 1970. SUID-AFRIKAANSE NASIONALE TONNELBOUKOMITEE In 1970 het die Suid-Afrikaanse Instituut van Siviele Ingenieurs, die Suid-Afrikaanse Instituut vir Mynbou en Metallurgie, die Suid-Afrikaanse Instituut van Meganiese Ingenieurs en Die Geologiese Vereniging van Suid-Afrika &apos;n internasionale konferensie in verband met tonnelbou gehou, wat bekend gestaan het as Tonkon 1970.

Jan 5, 1974

By A. Y. Senchenkoa, Y. V. Kulikov

The relationships revealed between ore hardness and specific energy consumed by crushing and grinding are described in the paper. A comparison of key technical and economical parameters of SAG and HPGR circuits is made, based on testing of several ore types for greenfield projects. The comparison of results make it possible to estimate efficiency of the technologies application, depending on ore hardness and taking into account potential risks for a circuit under design. Keywords: Comminution circuits, SAG, HPGR, test results

Jan 1, 2020

By D. W. Dean, J. A. Ryder

"A computer system designed to assist in maintenance scheduling and costing, and in monitoring the performance of equipment, is described. The emphasis is on the information retrieval and implementation aspects of the system.INTRODUCTIONThe cost of the maintenance of equipment can account for a substantial proportion of the total costs of any large industry. These costs are made up of the following elements:(i) capital expenditure,(ii) maintenance labour,(iii) maintenance spares,(iv) maintenance overheads,(v) production losses.Control of these cost elements cannot be achieved without a system which maintains and retrieves the necessary infor¬mation efficiently.The system should provide engineering management with the information necessary to:(i) establish the cost of maintaining items of equipment,(ii)establish the economic life of equipment,(iii) determine breakdown patterns for the establishment of optimum inspection, service and overhaul frequencies,(iv) establish work schedules for those responsible for the maintenance of equipment,(v) establish the optimum maintenance labour complement,(vi) establish the optimum stockholding of maintenance stores items,(vii) improve the performance of equipment,(viii) justify the selection of a particular type and make of equipment,(ix) establish the reasons for any abnormal usage of materials and labour, and to(x)reduce the dependence on the human element for the control of equipment maintenance activities.Many industries have comprehensive and numerous equipment maintenance records but they experience great difficulty in retrieving the required information in the time available and with the labour available. Many industries do not bother to maintain meaningful records, because of this difficulty."

Jan 1, 2014

By U. Atici, R. Comakli

"Understanding rock properties is of vital importance in mining and civil engineering. Rock properties are generally determined through laboratory tests, which require a large number of uniformly shaped samples and technicians who use indirect methods to determine rock properties. The texture coefficient (TC), which represents various textural parameters including the size, shape, orientation, and relative proportions of grains and the matrix, is an efficient means for indirectly evaluating the mechanical behaviour of rocks. In this study, 12 different rocks (ten granites, one diorite, and one gabbro) were collected and their engineering properties. including specific gravity, porosity, P- and S-wave velocities, Schmidt rebound hardness, uniaxial compressive strength, and elasticity modulus, were investigated. Relationships between TC and these measured properties were assessed. Statistically significant (at the 95% confidence level) correlations were found between the TC and compressive strength, elasticity modulus, sound velocity (both compression and shear waves for dry and saturated samples), but no significant correlation was found with Schmidt rebound hardness. The results suggest that it is possible to use the relationships between TC and the mechanical properties of rocks in rock classification. IntroductionIn every aspect of rock engineering, knowing rock properties is essential for determining and predicting the behaviour of rocks and rock masses. Mechanical properties of rocks are important parameters in mining, geology, and engineering, and they are affected by textural characteristics such as grain size, grain shape, cement type, degree of cementation, mineral content, and the ratio of the grain area to the matrix area. The effects of textural properties on the physical and mechanical properties of rocks have been investigated for a long time, and previous studies revealed close relationships between single parameters related to rock texture and mechanical properties of rocks (Akesson et al. 2001; Gunsallus and Kulhawy 1984; Merriam, Rieke, and Kim, 1970: Onodera and Kumara 1980; Prikryl 2006; Ulusay, Tureli, and Bider, 1994; Tugrul and Zarif 1998). Rock properties are usually determined using mechanical tests, which require uniformly shaped and relatively large samples. However, it is not always possible to obtain such samples. Furthermore, rocks with similar textural and structural properties may exhibit different mechanical behaviour. Howarth and Rowlands (1987) developed a texture coefficient (TC) that expresses all the main textural parameters of a rock in a single dimensionless quantity based primarily on statistical assessment. The TC makes it possible to understand the effects of a rock’s textural properties on its mechanical properties using thin sections instead of large, uniform samples. Ersoy and Waller (1995) investigated the relationship between strength and TC for limestone, sandstone, and siltstone; they also examined the effect of rock properties and TC on drilling performance. Ozturk, Nasuf, and Bilgin (2004) explored the relationship between rock quality and TC by evaluating the uniaxial compressive strength (UCS) values of limestone, basaltic andesite, and tuff. Gupta and Sharma (2012) evaluated TCs as well as the petrophysical and mechanical properties of quartzite from the lower and higher Himalayas and found a strong relationship between TC and UCS. Similarly, Ozcelik, Bayram, and Yasitli (2013) investigated the relationship between TC and various parameters in marble by applying the statistical analyses developed by Ozturk, Nasuf, and Kahraman (2014)."

Jan 1, 2019

By J. Petersen, T. Moyo, J. Dinga

The leaching of chalcopyrite in ferric sulfate media is notorious for its slow and inhibited kinetics. Different methods have been proposed to improve the kinetics, including the use of organic compounds as additives to the leaching media. In this study, the enhancing effect of methanol, ethanol, 1-propanol, and 2-propanol on the leaching of chalcopyrite in aerated acid ferric sulfate solutions using different reactor systems was investigated. The results revealed a clear improvement of copper dissolution by methanol and 1-propanol relative to tests with no additives under similar conditions. Operating a continuous-flow mini-column reactor yields surprisingly good results, potentially related to the maintaining of a consistent leaching micro-environment on the mineral surface. Scanning electron microscopy studies showed that the alcohols result in the removal of surface deposits formed during the anodic dissolution, potentially thus facilitating improved cathodic reduction of the ferric ion to drive the anodic dissolution.

Jan 1, 2023

By Y. J. Cao

The purpose of this study was to investigate the flotation behaviour of unburned carbon in a cyclonic-static microbubble flotation column (FCSMC). The ash sample, collected from a power station in Guangdong province of China, was characterized by size analysis, X-ray diffraction, contact angle measurements, and X-ray fluorescence. The effect of the column flotation operating variables on the removal of unburned carbon from the fly ash was systematically studied. The feasibility of separating unburned carbon and ash was determined from the removal rate of unburned carbon (RUC) and loss on ignition (LOI). Within the range studied, the optimum diesel oil dosage was 1200 g/t, abies oil dosage was 600 g/t, pulp density was 20 per cent, superficial gas velocity was 1.4 cm/s, and circulating pressure was 0.20 MPa. The results indicate that the FCSMC technique is effective in removing the unburned carbon from the fly ash, which can be attributed to the generation of microbubbles and the continuous cyclonic circulation method. Under the optimized conditions, a cleaning ash with 2.13 per cent LOI and 94.21 per cent RUC was obtained.

Jan 1, 2012