Scielo RSS <![CDATA[Journal of the Southern African Institute of Mining and Metallurgy]]> http://www.scielo.org.za/rss.php?pid=0038-223X20120003&lang=en vol. 112 num. 3 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Physical beneficiation</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300001&lng=en&nrm=iso&tlng=en http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300002&lng=en&nrm=iso&tlng=en <![CDATA[<b>The update of the South African Mineral Asset Valuation Code (SAMVAL)</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300003&lng=en&nrm=iso&tlng=en <![CDATA[<b>Mine planning and design qualifications</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300004&lng=en&nrm=iso&tlng=en <![CDATA[<b>CEEC, the Future</b>: <b>Johannesburg Branch meeting </b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300005&lng=en&nrm=iso&tlng=en <![CDATA[<b>Spotlight</b>: <b>Iron Ore and Manganese Ore Metallurgy 2011</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300006&lng=en&nrm=iso&tlng=en <![CDATA[<b>Novel size and shape measurements applied to jig plant performance analysis</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300007&lng=en&nrm=iso&tlng=en Iron ore samples representing the input and output of several jigging experiments were analysed to determine the effect of particle size, shape, and density on jigging performance. Traditionally, the manual measurement of the size and shape of individual particles is very tedious and prone to inaccuracies and inconsistencies. Using a novel multi-view imaging technique the 3-dimensional representations of each particle in the sample was determined. From this representation several size and shape measurements were extracted, and these were correlated with the individual particle density measurements. A rigorous investigation into the confidence associated with density and the size and shape features as a function of sample size was conducted, thus allowing the significance of correlations in the data to be determined. The jig's performance was seen to be clearly sensitive to density and markedly so to particle size, while the results for shape indicated the need for continued work in the definition of particle shape. <![CDATA[<b>Development of a prototype X-ray transmission washability monitor</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300008&lng=en&nrm=iso&tlng=en The design and efficient operation of density-based mineral processing units requires regular densimetric analysis to be carried out on the various associated process streams. The results obtained from such analyses can have wide application, including the generation of washability and partition curves, which are critical for process design, control, and simulation. This paper describes some of the collaborative efforts that Kumba Iron Ore, in partnership with Springer New Technology and Anglo Technical Solutions Research, is pursuing in developing a novel density determination technique exploiting X-ray transmission (XRT) and optical imaging. This technique is being developed with the aim to determine sample density distributions that apply to washability characterisation of ores. This technique is aimed to be an alternative to the traditional sink and float method. For certain applications sink and float has required the use of tetrabromoethane (TBE) solution-a chemical that has been classified as harmful and environmentally unfriendly. This paper therefore presents some achievements in developing this novel technique which seems to be very promising. <![CDATA[<b>Evaluation of the batch press as a laboratory tool to simulate medium-pressure roller crushers</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300009&lng=en&nrm=iso&tlng=en In this study the applicability of a batch press to predict the energy consumption and particle size distributions for medium-pressure roller presses was investigated. The relationships between energy consumption, feed size and product size are discussed with reference to Hukki's interpretation of Bond's and Rittinger's laws, as well as the particle size parameter used. It was found that the comminution laws have limited utility for the characterization of the performance of the medium-pressure roller crushers or the batch press used, and also depend on the particle size distribution indicator used. It was also found that the batch press is not a suitable simulator for medium-pressure roller mills as it was not able to predict the energy requirements, or to predict the size distributions that would be obtained for the ores evaluated. <![CDATA[<b>Maximizing the recovery of fine iron ore using magnetic separation</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300010&lng=en&nrm=iso&tlng=en The beneficiation of fine iron ore will increase in importance in the future because most new iron ore resources will be in the form of lower grade ore deposits that will require liberation of iron ore minerals at finer sizes. Generally this fine iron ore will be benefi-ciated to produce a pelletizing concentrate with very strict chemical and physical specifications. In addition, because of the increasing demand for iron ore there are now more opportunities to produce by-product iron ore from mining operations producing other commodities. In the past the associated iron ore minerals would report to final tailings but now there is potential value to be realised from by-product revenue. These by-product iron ore opportunities are almost all centred on producing pelletizing concentrate. Currently pelletizing concentrates are produced mainly by various combinations of flotation and magnetic separation. The selection of the beneficiation route will depend on ore mineralogy and considerations around plant capacity and final concentrate quality. The main economic iron minerals are magnetic, haematite being paramagnetic and magnetite being ferromagnetic. This, therefore, means that magnetic separation can be applied, in principle, to all fine iron-ore beneficiation plants. While flotation has a considerable capacity advantage over magnetic separation, the real advantage of magnetic separation over flotation in fine iron-ore beneficiation is that treatment of -10 µm iron ore is possible-in flotation, the feed is deslimed at 10 µm and the -10 µm stream is considered to be final tailings, even though there is often a significant amount of contained iron ore. This paper describes a study around the recovery of fine magnetite in the form of a pelletizing concentrate. The study is based on an evaluation of an iron ore by-product opportunity from an iron oxide copper-gold (IOCG) deposit. Experiments were conducted to quantify the differences in magnetic separation performance with decrease in particle size treated. A mineralogical evaluation of all the test work products was undertaken to facilitate the interpretation of the test work results. These results were then used to propose an economically viable flowsheet for maximizing fine magnetite recovery using magnetic separation. <![CDATA[<b>Performance improvements provided by Mintek's FloatStar™ advanced control system on reverse flotation of iron ore</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300011&lng=en&nrm=iso&tlng=en In November 2009 Mintek installed the FloatStar™ advanced flotation stabilization system on Vale's Cauê iron ore beneficiation plant in Brazil. In September 2010 the system was upgraded to include flotation optimization. The circuit consisted of two parallel cleaner circuits producing final concentrate. The tailings from the cleaner section passed through a scavenger circuit. Large, well-instrumented feed sumps played an important role in circuit stability, presenting a good opportunity for advanced control. Previously the plant was controlled using distributed control system (DCS) level control only. The flotation circuit processes roughly 30kt/day. The FloatStar system provided advanced control of the flotation circuit as well as of the sumps feeding the circuit. The system underwent a lengthy trial to assess the benefit that it provided. Two data sets were analysed, showing performance under advanced stabilization and optimization respectively. Several validation and consistency criteria were employed to ensure the quality of the analysis. Iron recovery and iron tailings grade were used to measure system performance. The analysis showed that the system increased recovery by up to 2.7%. In addition, the system decreased the iron tailings grade by between 1.2% (from 23.5% to 22.3%) and 4.3% (from 31.3% to 27.0%) during different test campaigns. The analysis also showed that the entire FloatStar stabilization system was active for 72.7% of the time from first activation to the end of the first data set (approximately 200 days). From the analysis it was concluded that under similar conditions for 'ON' and 'OFF' tests, the system provides a clear benefit. It was also found that over the longer term, the system continues to provide a benefit. This finding suggests that the results were not simply due to a short-term advantage. The size of the data set, as well as the magnitude of the recovery improvements, lends considerable confidence to these results. Therefore, it can be concluded that the FloatStar control system provides substantial benefit to operations at this site. <![CDATA[<b>Khumani Iron Ore Mine paste disposal and water recovery system</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300012&lng=en&nrm=iso&tlng=en Traditional iron ore beneficiation plants using washing, screening, and jigging processes require large volumes of process water. However, when a suitable large iron ore deposit is found in a location where rainfall is erratic and raw water sources are limited, innovative process designs are required to minimize water losses, maximize re-use of process water, and minimize raw water intake to ensure the project viability. This case study provides an overview of the Khumani paste disposal facility (PDF) located in the Northern Cape Province of South Africa. The plant uses a central ring main water reticulation circuit combined with a two-stage thickening system to maximize water recovery. At the process plant there are two large 90 m diameter traction thickeners and at the PDF two 18 m paste thickeners. The net raw water usage has been minimized, and water losses on the PDF are at levels of between 0.43 to 0.69 m³/t deposited.S <![CDATA[<b>Pelletizing of Sishen concentrate</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300013&lng=en&nrm=iso&tlng=en Iron ore concentrate is not easily transported to, or processed in, ironmaking plants, therefore it is necessary to agglomerate. This paper will determine the possibility of agglomerating Sishen concentrate into suitable ironmaking feedstock. Pelletizing is one of the conventional and preferred agglomeration processes for iron ore concentrate investigated at Kumba Value-In-Use Laboratories. Sishen concentrate was mixed with binder, and then pelletized using a laboratory pelletizing disc; afterwards the green pellets were indurated at high temperatures to give strength high enough to survive handling and lessen disintegration in the shaft during ironmaking. Sishen pellets have satisfactory physical and metallurgical properties which make them suitable feedstock for the direct reduction processes. These were tested under Midrex shaft operational conditions and performed well, with a metallization of 94.47% being attained. <![CDATA[<b>Correlation between <i>P</i>-wave velocity and some mechanical properties for sedimentary rocks</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300014&lng=en&nrm=iso&tlng=en Engineers and researchers need to estimate the mechanical properties of rocks from P-wave velocity. In previous studies, the researchers have investigated either the limited values or all the data belonging to sedimentary, igneous, and metamorphic rocks together in the same statistical analysis. In this study, the raw data pertaining to only sedimentary rocks was taken from previous studies and evaluated. For this purpose, a total of 97 samples of sedimentary rock types were subjected to statistical analysis. First, the relationships between P-wave velocity and physical-mechanical properties were investigated by simple regression analysis. All the data were then subjected to multi-regression analysis. Some empirical equations with high correlation coefficients were derived for rock engineers. The equations obtained from the analyses are compared with previous equations found in literature. <![CDATA[<b>A practical application of geostatistical methods to quality and mineral reserve modelling of cement raw materials</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300015&lng=en&nrm=iso&tlng=en Estimation techniques such as polygonal, triangular prism, trapezoid, isopach maps, and inverse distance methods are often used in ore or industrial minerals deposit evaluation. These techniques do not express the variability of the deposit and do not allow a determination of the reliability of the estimates. However, geostatistical methods can express a measure of the error associated with the estimates, by finding weighting coefficients for a given mining block, and can also help with data configuration that minimizes the error. This work addresses an application study on the quality and reserve characteristics of the cement raw materials of the Adana Cement Factory in Adana, Turkey, based on the spatial distribution and variability of the chemical components (SiO2, CaO, Al2O3, Fe2O3). The study has been carried out using a geostatistical procedure that is useful for site assessment, characterization, and monitoring situations where data are collected spatially. Directional and omnidirectional experimental variograms of the cement raw material variables showed that neither strong geometric nor severe zonal anisotropy exists in the data. The most evident spatial dependence structure expressing the continuity for omnidirectional experimental variograms were characterized by exponential and spherical variogram models. These models have been used in cross-validation analysis, which proved that these models, their parameters, and kriging parameters are applicable for the study area. Quality contour maps of the deposits at given levels underground were estimated using a kriging interpolation technique. Anomalies such as bullseyes and drift were not observed in the maps that were generated. Kriged maps showed the spatial distribution of quality continuity and variability of the deposits. Grade-tonnage curves and total tonnage estimates in the particular grade were determined using ordinary kriging in order to improve the mining operation and planning. Consequently, local uncertainty and the probability of extreme values occurring are tools of prime importance for the mine planning, the optimum mix of raw materials coming from different quarry stopes <![CDATA[<b>Classifying quarries vis-à-vis prospects of profitability</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2012000300016&lng=en&nrm=iso&tlng=en Similar to the case of any other business venture, the activities of mining industries are profit-oriented. Nothing will stop successful businesses in their quest for new localities to be prospected for minerals of their choice, because the useful economic life of any mine is limited. Before starting the process of land acquisition, it is important for any mining company to be able to forecast the profitability of the venture. The focus of this paper has been on the prospects of success, concerning the case of the opencast extraction of aggregates for construction. A set of 70 successful and loss-making quarries was subjected to investigation. An international company owns the quarries, which are located in seven European countries. The method of discriminate analysis provided the criteria for assessing future economic performance. The same criteria served the purpose of classifying other quarries belonging to the company