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By Luke K. A

Pressure on production at New Zealand China Clays has led to the development of a dewatering control loop for fine halloysite china clay. The development was based on the analysis of data from the automation of plate and frame filter presses. The analysis of the data has led to process changes, and the ability to quickly solve dewatering problems. As a result of control in the dewatering circuit press times have reduced on average 117% and output has increased proportionally.

Jan 1, 1989

By G Gosson

An important requirement in every geological quality control program is that the identity and grades of the control samples (duplicates, certified reference materials (CRMs), and blanks) must remain æblindÆ to the analytical laboratory. Once the entity to be controlled is aware of relevant details of the control process, such as the identity of the control samples, the objectivity may be lost and the control may no longer be completely valid. Whereas the blind insertion of field duplicates and coarse blanks can be easily conducted at site, simultaneously with the sampling process, the rest of the control samples should be inserted into the batches during or after sample preparation and prior to assaying, in order to ensure a proper assessment of precision, accuracy and assay contamination, independent of the internal quality control of the laboratory. Such a procedure raises the concern that blind insertion of crushed or pulverised material in sample batches prior to assaying could represent a breach in the chain of custody principle, as samples would have to be temporarily returned to the custody of a non-laboratory person in charge of the insertions. In this seemingly conflict scenario, what should we give up? Do we maintain the strict chain of custody, knowing that the laboratory will be aware of the identity of some of the control samples, or that some duplicates will not be true same-batch duplicates? Do we ignore chain of custody issues to maintain the anonymity of the control samples and insert blind same-batch duplicates, CRMs and blanks? Is it possible to do blind insertions without breaching the chain of custody? Current NI 43-101 and JORC requirements, as well as real-world QA/QC and sample security practices, are discussed in light of AMECÆs approach to the solution of this apparent dilemma.

Jan 1, 2008

According to the data provided by the most recent European Survey on Working Conditions, roughly 25 per cent of the European working population is exposed to mechanical vibrations for no less than one quarter of the work shift duration, while around ten per cent are exposed for the entire work shift. The occupational exposure to whole-body vibration (WBV), in particular, represents a major health risk in mining, quarrying and civil excavation activities. In accordance with European Directive 2002/44/EC, the latest version of the Italian law on physical risks has recently confirmed the possibility of using relevant literature data on vibration magnitude in order to evaluate personal occupational exposure (vibration database or data provided by the manufacturer). Still the alternative option, based on field measurements, represents the most appropriated method of risk assessment, as it accounts for the actual operating condition at the workplace; actual operator and vehicle under investigation and specific working cycle. The article discusses the vibration measurements taken on a number of heavy machinery (excavators, loaders, trucks, dumpers, etc) employed for talc extraction in a mine located in Sardinia and the resulting personal exposure for the drivers. The assessment was carried out in accordance with the specifications of ISO 2631-1 and EN 14253.

Dec 6, 2010

By S Hapugoda, J R. Manuel, M J. Peterson, A Poliakov, E Donskoi

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Aug 12, 2013

The material presented in this paper describes experimental work to determine the effect of variations in suction nozzle design upon inlet flow conditions. Four entrance profile shapes were examined under controlled conditions of slurry flow and it was found that the straight ended nozzles had consistently higher entrance losses than the straight taper or the ellipse, and that the circular arc profile nozzles were the most efficient. Subordinate considerations were the measurement of the quantities and the forces involved.As the work progressed, three distinct phases in the pattern of flow were apparent and the static pressures in each were carefully examined. An inlet zone was found to be unstable in changing boundary conditions, a transition zone was largely independent of slurry density and in a zone of stability the pressures were found to be directly related to the characteristics of the flowing pulp. In this zone pressure measurements were reproducible within ± 2 per cent regardless of changing boundary conditions.The effect of varying the "1" parameter of nozzles with a part circular entrance profile was examined and it was found that flow conditions approaching the ideal were obtained when the radius of curvature was between 0·40 and 0·550.

Jan 1, 1966

By J H. J Holtzhausen

Never has there been more focus on the health, safety, and well-being of our employees at the workplace. Ever evolving expectations of individuals, companies and clients are shaping regulatory reviews and advancing standards across the world in the drive to zero harm. The technology is advancing at a rapid pace, which is now allowing continuous real-time monitoring of contaminants to take place in the harshest of environments.

Oct 12, 2022

By Kelsall D. F, Trahar W. J

The size by size batch flotation behaviour of copper activated sphalerite from synthetic mixtures with quartz was determined. In terms of recovery of sphalerite, the size fractions could be grouped into coarse, intermediate, and fine ranges. The behaviour of the coarse and fine ranges was significantly poorer than that of the intermediate range in both the extent and rate of flotation.Each size fraction had a fast and a slow floating component.The main effect of changing the copper sulphate addition was to alter the proportion of any size fraction which was fast floating. No correlation could be found, between the amount of copper on the spha:lerite andeither the flotation rate of the mineral or the amount of copper added to the system. It was found that fine particles did not appear to consume greatly disproportionate amounts of copper sulphate during conditioning. A modified conditioning procedure was found to lead to a higher rate of flotation and recovery of coarse sphalerite and to make poss1ble substantial savings of copper sulphate.

Jan 1, 1975

By Moore A. J

Control of blast vibration requires that its nature and causes be understood, and that effective control procedures be implemented to ensure compliance with limits related to the probability of damage to buildings/structures and human discomfort. This paper covers measurement equipment, assessment and prediction techniques, blast vibration control procedures and applicable statutory limits. It reviews current practice, and provides information on recent developments in blast vibration measurement equipment and control techniques, using examples based on Hunter Valley mining practice.

Jan 1, 1995

Python Underground Processing Plant Critical Design The use of continuous gravity recovery in combination with a controlled breakage fine crushing and screening system followed by flash flotation has been incorporated into the Python processing plant. This provides miners with a flexible, robust, low cost, low energy pre-concentration process for the recovery of gold and/or heavy minerals. The Python plant incorporates fine crushing utilizing either High Pressure Grinding Rolls or Vertical Shaft Impactors in combination with the InLine Pressure Jig and Flash Flotation to continuously liberate and recover the valuable minerals. The use of these technologies has enabled a narrow, transportable pre-concentration plant to be produced which can easily be installed and operated in underground drifts and tunnels.

Sep 13, 2010

The early records of hydraulic elevator and bucket ladder dredging in the Clutha River system indicate the success of that era of alluvial gold mining in Otago. This paper briefly reviews parameters of depth and gold grade for alluvial operations. The application of dragline technology is proposed for the economic removal of overburden to target the deeper alluvial gold areas which remain in the Otago region.

Jan 1, 1992

By Mwaba CC

Ok Tedi Mining Ltd has been using flotation for the production of copper/gold concentrates from a complex copper sulphide ore for several years. During this period, much effort has been devoted to metall- urgical treatment of the ore. This paper examines some of the mineralogical aspects of the sulphide minerals in the ore using the electron microprobe analyser. Results have revealed the complexity of the copper sulphide minerals and in particular, chalcocite. Analysis of both plant and laboratory flotation products has provided further insight into the effects of mineralogy on the flotation of copper and iron sulphides. A significant observation is that some of the pyrite minerals apparently exhibit natural floatability. The implications of the mineralogical characteristics of the sulphide minerals on the flotation of the ore are also discussed.

Jan 1, 1991

By S Vianna, K Caldwell, R Silva, T Olson, D Bell

Studies to enhance the FLSmidth forced air machine through changes in the design, showed important improvements through changes in the number of Rotor blades, stator designs, rotor air distribution and other designs features. The main outcomes from this study highlighted that increasing the number of rotor blades increased the selectivity while decreasing power requirements while stators with slots have better results in terms of recovery, flotation efficiency and selectivity than without slots.Also the rotor air distribution makes a difference in the design when comparing different distribution criteria whilst keeping all features of shape and number of blades etc constant. At the most efficient rotor air distribution design, copper recovery reached one of the highest values while keeping good selectivity. The possible explanation for that is the increase in the pump capacity indicated by the increase in the specific power.It was seen as significant that reduction in specific power for some designs tested compared with the then current standard design had an average of 30% less power consumption.As a result, FLSmidth was able to identify new designs that decreased power and improved recovery, as well as, identifying some designs that specifically improved fine and/or coarse particle recovery.CITATION:Silva, R, Caldwell, K, Bell, D, Olson, T and Vianna, S, 2013. FLSmidth flotation developments - Dorr Oliver machines, in Proceedings MetPlant 2013 , pp 413-430 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

The mmmg of alluvial gold involves many deposits of theMesozoic, Tertiary, and Quaternary Ages in processing. Majorfeatures of the composition of such alluvial deposits are the lowcontent of gold and the small size of the gold particles. Atpresent, the gold-miners treat alluvial deposits in which a portionof fme gold (0.25 mm) exceeds 45 per cent. It is expected that by2000 these resources will be the main deposits mined (Zamyatinet aI, 1991).Under real industrial conditions the losses of minus 0.25 mmmetal are 50 per cent and more. The low level of recovery of finegold is observed not only at concentrators equipped with sluices,but also at concentrators equipped with modern diaphragm andpistonless jigs (Table 1).

Jan 1, 1993

A belt of serpentinized ultrabasic rocks intrudes a moderately folded geosynclinal sequence of fine to coarse sediments, acid, intermediate, and basic volcanics as well as a batholithic mass of granitic rocks. The ultrabasic body contains small included masses of melanocratic and leucocratic rocks, together with chromium, copper, zinc, and nickel mineralization.

Jan 1, 1969

The steps for the beneficiation of iron ores differ from ore to ore, depending on the mineralogical phases of the particular iron ore and the nature of the association of the gangue minerals with iron oxide in that ore. The extent to which the beneficiation can be undertaken economically depends both on the amount and the nature of the gangue. The analysis of the phases present in an orebody optimises the mining and process operations (separation, beneficiation, sintering, etc).X-ray diffraction (XRD) provides qualitative and quantitative information about the main ore phases as well as the gangue mineralogy and the amorphous content present in a sample. In addition, modern quantification methods such as Rietveld refinement allow the calculation of the distribution of elements in solid solutions such the substitution of Fe with Al in goethite or hematite.The use of high speed detectors has made XRD an important tool for grade and process control. Finger printing of XRD data can facilitate multi-dimensional mapping of ore deposits and drill cores, identifying regions of favourable mineral compositions. Grade control using XRD can be completely automated and controlled remotely.The two case studies in this paper demonstrate how XRD and finger printing can be used for grade control, process optimisation and quality control of a goethitic and a magnetitic iron ore. The enormous potential of XRD as an inexpensive, reliable tool, useful in the characterisation of iron ores will be demonstrated.CITATION:K÷nig, U, 2013. Application of x-ray diffraction to iron ores - potential implications for grade control and downstream processing, in Proceedings Iron Ore 2013 , pp 275-280 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By R Cowen

Past successes of low impact mineral exploration and rehabilitation of mined areas in developed land of subdued contour provide little guidance for similar activity in more sensitive high country or mountain environments. Land management agencies and environmental pressure groups have expressed considerable concern about mineral development in these areas by land especially where the land involved has high environmental or productive values. Mineral explorers are responding with detailed proposals for integration of environmental assessment and mineral exploration at an early stage. A model programme for Fiordland National Park presented in this paper illustrates this approach.

Jan 1, 1981

By J L. Mauk

The Sovereign, Jubilee, Scotia and Jasper Creek prospects occur in an area of ~3.0 km by 2.5 km (~7.5 km2) in the Hauraki goldfield. The prospects are hosted by andesitic to dacitic flows, autoclastic breccias and localised pyroclastic and air fall deposits. Jubilee and Sovereign prospects lie along the northern and southern parts of the Waitekauri Fault, respectively, whereas Scotia is located ~1 km to the E, and Jasper Creek a further ~1.2 km to the ENE. Wall rocks are typically intensely altered, although the degree of alteration becomes more variable east of Scotia and at Jasper Creek. Alteration minerals include quartz, adularia, albite, chlorite, pyrite, illite, interstratified illite-smectite, smectite and calcite. Several of these minerals have distributions that show distinct zonation with adularia most abundant at Sovereign and Jasper Creek, but restricted to shallow levels at Scotia. Illite occurs throughout Sovereign and Jubilee plus the western margin of Scotia where it grades into interstratified illite-smectite; smectite predominates at Jasper Creek. Veins are uncommon and typically narrow, but show distinct zonations. Quartz veins are more abundant at Sovereign and Jubilee, whereas calcite veins are more abundant at Scotia and Jasper Creek. Laumontite veins occur at Scotia, and rare clinoptilolite, mordenite and stilbite veinlets with calcite occur at Jasper Creek. Fluid inclusion in quartz and calcite homogenised between 141¦ to 272¦C and trapped a dilute solution with an apparent salinity of less than 2.6 weight percent NaCl equivalent. Homogenisation temperatures are hottest at Sovereign (average 241¦C) and Jubilee (average 239¦C), cooler at Scotia (average 204¦C) and coolest at Jasper Creek (average 162¦C). Calculated paleowater table elevations suggest the water table was 680 m to 750 m above sea level at Sovereign and Jubilee, 450 m at Scotia and 225 m at Jasper Creek. The current data suggest three scenarios that can explain why Sovereign and Jubilee are deep and hot, whereas Jasper Creek is cool, shallow and marginal; 1.   some or all of the prospects may represent separate overlapping hydrothermal system, 2.   a high-relief hydrothermal system on the side of volcano with an inclined water table and outflow towards Jasper Creek, and 3.   a low-relief hydrothermal system that has been either tilted or block faulted with greatest uplift and erosion to the west.

Jan 1, 2005

Triboelectric Separation - Beneficiation of Coal The performance of triboelectric separators is highly sensitive to the selectivity of the particle charging process. This paper presents a quantitative study on triboelectric coal beneficiation. The performance of different charging media was studied. Stainless steel was identified as having a work function between that of coal and silicate gangue and found to be the optimum charging medium for coal beneficiation. Recent results from separation tests were performed where silicate gangue was separated from crude coal using a parallel plate free-fall separator are illustrated.

Sep 13, 2010

The prospect of utilisation of phosphate ores which contain high P2O5 values associated with Al and Fe has produced a great deal of interest over many years. Processing options have generally been based on the utilisation of by-products which were required to offset the processing costs.   This paper presents a range of processing options which have been investigated at laboratory or technical scale on phosphate ores which predominantly consist of crandallite, CaAl3(PO4)2(OH)5.3H2O and millisite, Ca(NaK)Al6(PO4)4(OH)9.3H2O. Christmas Island (Indian Ocean) and Mt Weld (Western Australia) phosphate ores are good examples of such feedstocks. It is expected that these processes may also be applicable to such phosphate ores from other locations.

Jan 1, 1990

WHILE in the employ of the Broken Hill Associated Smelters and the Electrolytic Zinc Oompanies at their South Melbourne Research Station, the writer was detailed to investigate the principles underlying the Parkes Process with a view of determining:1. The Interdependence of the variables:(a) Quantity of zinc required per charge,(b) Temperature of stirring of each zincing,(c) Silver content of the bullion after first zinculg,(d) Silver content of the bullion after second zincing,(e) Silver grade of the crusts produced for retorting, with reference to the method of working the Parkes Process then in operation at Port Pirie.2. The possibility of effecting improvements in the Port Pirie practice of desilverising, especially with respect to:(a) Silver grade of the crusts produced for retorting.(b) Quantity of zinc required per charge.The method of desilverising in practice at Port Pirie was a two-stage zincing.In both zincings the bullion was cooled to its solidification temperature and the silver crusts which separated from the lead were completely removed.The crusts from the first zincing were retorted, and the crusts from the second zincing were returned to the first zincing of the next charge.

Jan 1, 1925