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By S. P. Pereira

The mechanized mining cycle using loaders and shuttle cars had its peak in terms of usage in the mining industry during 1950 through 1960. In Brazil, this system is still used at underground coal mines in southern Santa Catarina coal basin. With the aim of investigating the benefits of a new mining scheme using the room and pillar method for these local mines, a computational simulator model was developed in order to investigate the mining cycle. This paper presents the methodology used to develop the simulator and the results that the simulation shows regarding impact of the proposed new scheme on mining productivity.

Jan 1, 2012

By C. van Tonder

Paper written on project work carried out in partial fulfilment of B Tech (Engineering Metallurgy) degree This investigation relates to a multi-purpose electrolytic system. Its primary purpose is to electrowin gold from high or low concentration gold cyanide solutions and/or from gold sludge, and to convert the recovered gold into a gold (alloy) electroform or electrode at the gold mine itself. These operations are carried out sequentially and in situ in the same electrolytic cell. Electrorefining of the gold recovered may also be done in the cell. The system applies to silver as well, and may be adaptable to base and platinum group metals. It could also be used in environmental applications, to remove undesirable metals present in aqueous solution at very low concentration. The work to be discussed forms part of recently filed patent applications. Subsequent and future developments of the system are briefly outlined. This paper, in part or in full, has been published by the Metallurgical Mine Managers Association (MMMA), with permission from the authors.

Jan 1, 2006

By D. M. Mubita

Dilution reduction is one of the areas that offer metal mines an opportunity to increase revenue and reduce costs, resulting in enhanced profits. Effective dilution control programmes require interaction on a multi-disciplinary level. This paper outlines recent initiatives undertaken at Konkola Mine to reduce dilution and increase revenue. The increase in revenue arising from reduced dilution and high factors between in situ and delivered to mill grades were quantified and amount to close to U$ 1.0 million per one per cent improvement in grade factor at a 75c/lb copper price. Sources of dilution from open and in?stope mining methods practised at the mine were identified and a multi-disciplinary dilution control forum set up to control these. Among the major achievements were the introduction of low dilution in-stope mining methods; the introduction of Gemcom geological and mining planning software to replace traditional pencil and paper methods, leading to better in situ estimation and production planning; enhanced control in open stopes through dilution awareness among mining production personnel; location of critical secondary development ends in correct positions; enhanced blast hole control; tracking of development waste by metal tracers and monthly tally; implementation of a cavity monitoring system to check over-breaks in open stopes; and setting up of a stope history database. The results from the cavity monitoring system showed that stopes with over-breaks of 5 metres or less could be controlled to break along the hangingwall contact.

Jan 1, 2005

By A. Bothma

The Impala No. 1A ventilation shaft is located approximately 15 kms north of Rustenburg and is accessed via the R510road from Rustenburg to Northam/Thabazimbi. This situation is shown on the location plan in Figure 1. The geology at the site consists of an upper layer of black turf of about 1 metre in thickness, grading into weathered norite. The depth of weathering is generally less than 5 metres. Zones of deeper weathering may occur along fracture zones associated with faults and dykes. Groundwater occurs mainly within the weathered/fractured aquifer system. The ventilation shaft is a 5.1 m diameter upcast shaft ,and forms part of a system of ventilation shafts to complement the existing infrastructure as mining progresses down the new twin decline extension of Impala 1 shaft. The principal reason for these shafts is to lessen the risk of an extended RAW and also to counter the effects of the heat build-up as the mining goes deeper, with the resultant effect that the existing cooling centre (fridge plant) becomes more remote from activities. The No. 1A shaft (upcast) is positioned approximately 1,2 km on down dip from the main shaft and the No. 1Bshaft (downcast) approximately 1,2 km further. Geological information was used from a borehole 1,2 km away on strike from the upcast shaft. The first shaft (1A) is a 5,1 m diameter hole to be fitted with two 2,2 MW fans, whilst the second shaft (1B) is 4,1 m diameter to accommodate a 7MW fridge plant.

Jan 1, 2001

By T. Gerritsen, R. C. Delgado, J. Janzen, E. R. Veloza

The paper describes the components of an Integrated Furnace Control system for covered-arc (shielded arc) smelting with results from the recently started 75 MW Cerro Matoso Line 2 Furnace. The paper starts with a review of the mechanisms of power and feed input and heat losses in the shielded-arc smelting process, and describes how the details of the control system are tailored to the process. The control modules of a covered-arc smelting furnace are described including measured results and screen captures. This paper focuses on Integrated Furnace Controls tailored to shielded-arc smelting, but similar approaches have been recently applied to other furnace processes including immersed-arc smelting.

Jan 1, 2004

By A. Kostin

GIS and multivariate geometric distribution have been used to predict the association of high-level intrusives with hydrothermal alteration related to iron oxide Cu-Au (IOCG) mineralizing systems. Several examples in the Russian northeast are presented in this paper. IOCG ore deposits can have enormous geological resources containing significant reserves of base, precious, and strategic metals, and hence are economically attractive targets for mineral exploration. To date, examples of this type of mineralization have not been reported from the northeastern area of Russia. The Tarinskiy ore cluster, located in Eastern Yakutia, shows brecciated altered rocks with sulphide and iron oxide cement, which is typical for IOCG mineralization of the iron oxide Cu-Au±U type. This cluster was formed near surface and is linked with the Rep- Yuruinskiy pluton. It has potential to host new world-class precious metal deposits in northeastern Russia

Jan 1, 2014

By B. Tiryaki

Performance prediction models for partial face mechanical excavators, when developed in laboratory conditions, depend on relating the results of a set of rock property tests and indices to specific cutting energy (SE) for various rock types. There exist some studies in the literature aiming to correlate the geotechnical properties of intact rocks with the SE, especially for massive and widely jointed rock environments. However, those including direct and/or indirect measures of rock fracture parameters such as rock brittleness and fracture toughness, along with the other rock parameters expressing different aspects of rock behavior under drag tools (picks), are rather limited. With this study, it was aimed to investigate the relationships between the indirect measures of rock brittleness and fracture toughness and the SE depending on the results of a new and two previous linear rock cutting programmes. Relationships between the SE, rock strength parameters, and the rock index tests have also been investigated in this study. Sandstone samples taken from the different fields around Ankara, Turkey were used in the new testing programme. Detailed mineralogical analyses, petrographic studies, and rock mechanics and rock cutting tests were performed on these selected sandstone specimens. The assessment of rock cuttability was based on the SE. Three different brittleness indices (B1, B2, andB4) were calculated for sandstones samples, whereas a toughness index (Ti), being developed by Atkinson et al.1, was employed to represent the indirect rock fracture toughness. The relationships between the SE and the large amounts of new data obtained from the mineralogical analyses, petrographic studies, rock mechanics, and linear rock cutting tests were evaluated by using bivariate correlation and curve fitting techniques, variance analysis, and Student?s t-test. Rock cutting and rock property testing data that came from well-known studies of McFeat-Smith and Fowell2andRoxborough and Philips3have also been employed in statistical analyses together with the new data. Laboratory tests and subsequent analyses revealed that there were close correlations between the SE and B4 whereas no statistically significant correlation has been found between the SE and Ti. Uniaxial compressive and Brazilian tensile strengths and Shore scleroscope hardness of sandstones also exhibited strong relationships with the SE. NCB cone indenter test had the greatest influence on the SE among the other engineering properties of rocks, confirming the previous studies in rock cutting and mechanical excavation. Therefore, it was recommended to employ easy-to-use index tests of NCB cone indenter and Shore scleroscope in the estimation of laboratory SE of sandstones ranging from very low to high strengths in the absence of a rock cutting rig to measure it until the easy-to-use universal measures of the rock brittleness and especially the rock fracture toughness, being an intrinsic rock property, are developed.

Jan 1, 2006

By A. M. Milev

A simulated rockburst was conducted underground at Kopanang Mine, previously called Vaal Reefs No. 9 Shaft. The rockburst was simulated by means of a large blast detonated in solid rock close to a crosscut sidewall. The simulated rockburst involved the design of the seismic source, seismic observations in the near and far field, high-speed video filming, a study of rock mass conditions such as fractures, joints, rock strength etc. Knowledge of the site conditions before and after the simulated rockburst was also gained. Some of the important findings are listed below: ?Two areas of damage were identified on the blasting wall: (i) an area of high-intensity damage in which ground velocities of 3.3 m/s were recorded by an accelerometer, which was subsequently ejected in a block of rock, (ii) an area of low-intensity damage where ground velocities of 1.6 m/s were recorded by an accelerometer which remained on the tunnel wall. ?High-speed filming revealed rock fragments being ejected from the wall at velocities in the range of 0.6 m/s to 2.5 m/s. The measurements were taken in the area of low-intensity damage. As planned, no gas pressure was directly involved in damaging the wall of the tunnel. ?The attenuation of peak particle velocities for the main blast in the near field (6 m to 30 m), as a function of distance R, was found to be proportional to R-1.7. ?The simulated rockburst was recorded as a local magnitude ML= 1.3 by the Klerksdorp regional seismic network. ?Peak particle velocities from nearby blasting, recorded on the tunnel wall after the simulated rockburst, were about six times greater then peak particle velocities recorded from the same source area before the simulated rockburst.

Jan 1, 2001

By A. P. Squelch

The question of what stress condition exists in the hangingwall of tabular stopes remains topical and largely unanswered. Limited field data exist to quantify the situation and provide calibration for investigative computer modelling exercises. Work conducted in1989 and 1990 under a Chamber of Mines Research Organization (now the CSIR: Division of Mining Technology) programme of research into the behaviour and benefits of backfill may assist with this situation. The original work was motivated by the premise that the improved hangingwall stability in backfilled panels (identified by rockfall accident analyses) is due to a change in the hangingwall stress regime. Current, largely theoretical, studies into mechanisms of stope hangingwall behaviour and support interaction could benefit from considering these data. Keywords: Backfill, horizontal stress, stope hangingwall, hangingwall stability, support interaction.

Jan 1, 2002

By J. M. Benson

Titanium is an exciting structural material that can offer significant strength-to-weight advantages over currently used alloys. However, its Achilles? heel is its costly, energy-intensive production process that effectively eliminates it from competing with aluminium and high-strength steels, apart from critical applications where titanium forms only a small component of the total cost. Current attempts are being made to reduce the cost of titanium products and these recognize the importance of minimizing the costs over the total production chain. Powder metallurgy (PM) technologies play a crucial role within this, as the output of the existing and potential primary metal production methods is in the form of sponge or powder. By using PM, costly remelting and forming operations can then be avoided, except in the manufacture of large components. Metal injection moulding (MIM) is an effective process for producing complex net-shape components in large volumes from metal powders. Nevertheless, the commercial use of titanium powders in this process is still in its infancy. The only major supplier of feedstock utilizes a polyacetal-based binder. This gives good green strength but requires a catalytic nitric acid process to remove most of the binder prior to thermal treatment. As this involves additional and expensive equipment and is a potentially hazardous process, there is interest in finding an alternative binder system that can be debound either purely thermally or that involves a less hazardous, more environmentally friendly solvent. This paper describes the use of capillary rheometry to characterize the influence of temperature and shear rates on the flow behaviour of potential binder systems for titanium MIM feedstock. Keywords Titanium, metal injection moulding, capillary rheology, feedstocks, powder loading.

Jan 1, 2011

By N. J. Castilla, R. Giglio

"Circulating fluidized-bed (CFB) combustion technology has been around for over 40 years, but over the last 6 years it has been commercially demonstrated at the 500 MWe scale at the Lagisza plant located in Bedzin, Poland. The CFB at the Lagisza plant has unique first-of-a-kind design features, such as vertical-tube supercritical steam technology and a lowtemperature flue-gas heat extraction that allows the plant to achieve high plant efficiencies of over 43% (net lower heating value). Another unusual feature for a coal power plant is that this plant meets all its atmospheric emission permit levels without any post-combustion de-NOx or de-SOx equipment such as selective catalytic reduction (SCR) or flue-gas desulphurization (FGD).CFB clean coal power technology is entering the utility power sector just in time to help deal with declining quality in internationally traded coals and to promote the large-scale use of economic, low-quality domestic fuels. Owing to the very attractive price discounts, growing supplies of low-quality Indonesian coals are outpacing the supply of high-quality Australian, Russian, and US coals. In Germany and Turkey, the use of domestic lignites for power production provides a secure and economic energy solution while creating domestic jobs.Conventional pulverized coal (PC) boilers will have trouble accepting these off-specification coals because of their narrow fuel specifications; they typically call for heating values above 5500 kcal/kg. This limitation is not an issue for CFB technology because of its ability to burn the worst and best of coals with heating values ranging from 3900 to 8000 kcal/kg.This paper provides an outlook for future coal supply, quality, and price, as well as a review of the technical and economic benefits of CFB technology firing low-quality fuels for utility power generation."

Jan 1, 2015

Novel flotation reagents were developed to improve the flotation of coarse particles. Laboratory tests conducted on an anthracite coal sample from Kyung-Dong Coal Company, Korea, showed that the reagents can successfully clean 2?3 mm top-size materials. Pilot-scale tests conducted on a 1.41 mm x0 coal gave substantially better results than those obtained using kerosene as collector. The pilot-scale test results were used to develop a flowsheet, in which the 1.41 mm x0 fraction is cleaned by flotation and the 4 x1.41 mm coal is cleaned by single-stage spirals. The performance of this circuit was compared with another flowsheet, in which the 0.5 mm x0coal is floated using the conventional flotation reagent, with the 4 x0.5 mm material being cleaned using two separate spiral circuits. The performance of the two flowsheets was compared by computer simulation. The results showed that the flowsheet consisting of the coarse particle flotation circuit can give substantially higher yield sat a given product grade. Keywords: coal flotation, coarse particle flotation, collector, spirals, computer simulation.

Jan 1, 2002

By Ernie Holden, Chris Ringas

In the last 20 years, In Line Inspection (ILI) using intelligent pigs has become the principal tool used by pipeline operators to assess the condition of their pipelines. New pipelines are normally designed to take intelligent pigs, but many older pipelines require some modifications and special procedures for their inspection. This paper is aimed at practicing engineers and managers of pipelines, or people aspiring to those positions. The paper describes the benefits of ILI and some of the practical issues regarding pipeline preparation and cleaning, choice of inspection tool, running pigs in pipelines, and what to do with the data collected. What are the responsibilities of the Pipeline Engineer ? ? Maintain reliable and acceptable performance of the pipeline in terms of safety and product delivery at economical cost. ? Provide a defined margin of safety for operating the pipeline at its designated pressure. ? Provide timely information on all pipeline defects such that repairs can be carried out according to a managed schedule. What Defects does the Pipeline Operator have to cope with ? A useful record of actual incidents seen in pipelines can be obtained from the web site of the US Office of Pipeline Safety (OPS) - http://ops.dot.gov/stats/stats.htm. US pipeline Operators are obliged by Law to report all pipeline incidents exceeding certain threshold criteria (e.g loss of life, escape of product, cost of incident etc). These OPS statistics show that corrosion and third party damage have remained consistently the prime causes of reportable incidents in the US, with similar experience elsewhere. There are several kinds of flaws and defects in pipelines that can lead to failure, the main families being :- ? Metal loss ? Cracks or crack-like defects ? Laminations and other mid-wall defects ? Geometric anomalies

Jan 1, 2006

By P. Mokwena

Paper written on project work carried out in partial fulfilment of BSc (Hons) in Chemical Engineering Diamond synthesis has attracted a great deal of interest because of its exceptional properties and various applications. In this study, the chemical catalytic vapour deposition (CCVD) method was used to synthesize diamond films using acetylene as carbon source and hydrogen as carrier gas at a temperature of 1000°C, and their thermodynamic stability was studied. Photographic analysis revealed that these products are diamond films, Ramman spectroscopy confirmed that they are graphitic while confocal laser scanning microscopic image analyses proved that these diamonds films have structural defects due to iron impurity from the catalyst precursor. The quantity of diamonds films produced is also proportional to the acetylene to hydrogen ratio but these films are larger in size at lower acetylene to hydrogen ratio. Thermogravimetric analyses showed that transformation of these materials begins at 25°C but could not be used to determine if a temperature range below 25°C exists. The stability of these CCVD-synthesized diamonds also increases below 25°C when stored at different temperatures.

Jan 1, 2007

By J. F. Papp

In the United States, chromium has been consumed in three major markets: chemical, metallurgical, and refractory. The predominant end use for chromium in the United States is in the metallurgical market as an alloying element in the production of stainless steel. In addition to being a major stainless steel-producing country, the United States is a major world producer of chromium-containing chemicals and has used substantial amounts of chromite ore for refractory applications. Chromium use is not easily further subdivided within the chemical and refractory industries because there is insufficient publicly available information to do so; however, chromium use can be subdivided among metallurgical industry uses based on the American Iron and Steel Institute (AISI) reported shipments of stainless steel by market classification (agricultural, aircraft, automotive, etc.). It is the goal of this study to determine the distribution of U.S. chromium apparent consumption among major markets in the United States. The distribution is expressed in the form of dimensionless fractions that are computed based on documented chromium consumption by major market. The distribution of chromium among markets within the metallurgical market is computed in a similar manner. Distribution factors are first computed for the major markets, then for markets that are subdivisions of the metallurgical market. The distribution of chromium among major markets has changed substantially over the time period of analysis. The fraction of chromium consumed by the metallurgical market has increased while that of the chemical and refractory markets has declined. Within the metallurgical market, the service industry market accounts for the greatest fraction of chromium consumption followed by transportation. Electrical, machinery, and fabricated products markets account for a substantial share of the metallurgical chromium consumption.

Jan 1, 2004

By A. Nel

The gold mining industry in South Africa stands to benefit much from the implementation of the self-directed work team concept. Its introduction implies flatter hierarchical structures, empowerment of the workforce and increased participation. Research indicates that half of the initiatives to implement self-directed work teams, however, fail, and it is therefore imperative for companies to be aware of the factors impacting on the effectiveness of self-directed work teams in order to focus on these early in the implementation phase. The objective of the study was to qualitatively determine these factors. Semi-structured interviews based on the phenomenological method were carried out. The sample included members of, and individuals involved with, self-directed work teams (N= 26) from a large gold mining company in South Africa. Results show that most respondents rated the availability of resources to do their work as the most important factor affecting their effectiveness.

Jan 1, 2006

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Jan 1, 2009

By A. N. Clay

In recent times, there has been criticism of the minerals industry over the lack of quantifiable boundaries between inferred, indicated, and Measured resources. A recent initiative through the United Nations aims to try to converge the mineral resource classification systems. Since the oil and gas industry uses a probabilistic approach to defining reserve boundaries, it is appropriate to introduce a similar statistical methodology for minerals. The Venmyn Variance Tower has been developed based upon traditional statistics to utilize historical and ongoing information in order to quantify variance of geological and chemical parameters and the boundaries and logic for quantitative mineral resource classification. It is proposed that a less than 50% variance from the mean of all sample parameters is required to achieve the classification threshold to define an inferred Resource whereas between 20-10% is needed for an indicated Resource and less than 10% variance from the mean is needed to declare a Measured Resource. These limits are similar to those used by the oil and gas industry, and it is suggested that these thresholds be adopted as an industry standard to ensure consistent quantitative reporting. While this process is intended to use statistics of an orebody to provide quantifiable and defendable boundaries, it cannot be carried out unless the geology of the mineral deposit is understood and the borehole samples can be categorized into appropriate populations for which the statistics are valid. This means that competent geologists are always required to work with and understand the implications of the Variance Tower results. This paper is intended to form the basis of a series of publications that establish a process to take mineral projects along a quantifiable and logical development path. Hence, no specific field example of the practical application of this process is given here.

Jan 1, 2012

By J. C. van Dyk

The objectives of this study were firstly to characterize and quantify the inorganic material in the Secunda gasification feedstock. Secondly, the effect of washing on coal properties and sulphur content was investigated. Coal from a single source and a coal blend from 6 different mines were tested. Composite samples were visually sorted by a geologist in the groups containing roof, floor, C-shale, pyrite, carbonates and siltstone material. Inorganic mineral types from the single source and coal blends were characterized separately. Characterization results indicate that the average mineral matter distribution (mass %) of the coal tested was as follows: carbonates (6%), carbon-shale (19%), pyrite (12%), roof (18%), floor (46%) and siltstone (22%). The roof, floor, pyrite, carbon-shale, carbonates and siltstone in the single source and coal blend have similar chemical properties and characteristics, except for the ash melting temperatures of pyrite and kaolinite in the siltstone. By implementing selective mining and increasing mining management practices, the percentage discard in the run of mine coal can be significantly reduced, by up to 45%, if the mining of roof and floor material can be avoided. No significant impact of mining practices on sulphur content is expected in this case due to the low concentrations of sulphur in the roof and floor material. In summary, selective mining practices will probably result in almost45% decrease in the discard content in the run of mine to gasification, an increase in the carbon content from 55.0% to 58% (air dry basis) and a decrease in sulphur content from 1.1% to 0.9% (air dry basis). It is clear from this study that the main source of sulphur is not in the high ash-content mineral types (e.g. floor and roof), but in situ in the coal structure. Keywords: inorganic material, effect of washing, roof, floor, pyrite, C-shale, carbonates and siltstone

Jan 1, 2005

By S. Ganguly

Slag samples taken from adjacent to the furnace wall of a submerged arc ferromanganese smelting furnace have been found to contain high concentrations of K2O. To characterize the phase equilibria relevant to these slags experimental studies have been carried out to determine pseudo-ternary sections of the form ?MnO?-CaO-(SiO2+Al2O3) with a fixed Al2O3/SiO2 weight ratio of 0.65 and 6.0 wt% K2O for temperatures in the range 1523-1673 K. In the pseudo-ternary section investigated the primary phase fields are found to be mullite, 3Al2O3?2SiO2; corundum, Al2O3; spinel, MnO?Al2O3; manganosite solid solution, (Mn,Ca)O; dicalcium silicate,2CaO?SiO2; gehlenite 2CaO?Al2O3?SiO2; anorthite CaO?Al2O3?2SiO2; kalsilite KAlSiO4 and leuciteKAlSi2O6. It was found that the presence of K2O in the slag decreases liquidus temperature in the anorthite and gehlenite primary phase fields. The manganosite primary phase field is expanded in the direction of increased (Al2O3+SiO2) and the liquidus temperatures in the manganosite primary phase field are increased significantly with the presence of K2O in the slag.

Jan 1, 2007