Search Documents

A Process for the Flotation of Chrysocolla

Sep 13, 2010

How to Evaluate Crushed Rocks for Concrete Production

Sep 13, 2010

By N M. Caira

The North Arm of Sulawesi hosts numerous gold and base metal occurrences. Compilation and analysis of geological, tectonic, geochemical and isotopic age date data collected over the past six years on the central part of this region have resulted in the definition of 184 prospects and mineral occurrences of various styles occurring in diverse geological settings representing varying tectonic environments and erosional levels. Mineralisation of the following styles have been recognised: porphyry Cu-Au; porphyry-related gold and base metal veins; high-sulphidation Cu-Au-As; low-sulphidation epithermal Au; hydrothermal breccias; and sediment-hosted Au mineralisation. Clusters of occurrences/prospects form mineralised districts representative of magmatic systems with characteristics determined by the tectonic environment prevailing during formation and the subsequent level of exposure by erosion. Distinctly different Miocene and Pliocene porphyry systems are now recognised whilst most of the remaining epithermal mineralisation is thought to be Pliocene or later. The central North Arm of Sulawesi is composed of a Miocene magmatic island arc that is built on an Early Tertiary basement of predominantly oceanic basaltic rocks and overprinted by a Pliocene magmatic arc. A structural fabric dominated by SSE arc-normal and ESE arc-parallel faults was established during the Miocene under a dextral wrench regime and intersections of these major fault sets are favoured sites for Miocene porphyry Cu-Au mineralisation. Strong dextral tension caused by the collision of the Sula Platform, at the close of the Miocene, led to arc-parallel rifting. Sinistral reactivation of the major Miocene structures in the Pliocene led to further rifting, and ENE-dilation. Pliocene intrusions and related mineralisation exploit these dilatant settings. Miocene porphyry Cu-Au mineralisation occurs where late-Miocene quartz diorite stocks have intruded the margins of earlier Miocene plutons of intermediate composition. Porphyry centres have associated peripheral base metal veins, and skarns. Overprinting of porphyry vein sets by epithermal veins is common. Sediment-hosted gold mineralisation occurs in calcareous sediments associated with the Miocene arc. Remnants of the Pliocene volcanic arc, comprised of dacite volcanics, intrusions and voluminous pyroclastics, dominate the south coast and host porphyry Cu-Au, high sulphidation Cu-Au-As deposits, low-sulphidation epithermal Au veins and disseminated gold mineralisation. In some prospects, mineralised sinters are preserved adjacent to vein systems and deeper mineralised stockworks. Diatremes are common and large caldera structures have been identified. Pliocene stocks and porphyry dyke swarms penetrate the main central and northern parts of the Miocene- arc introducing additional porphyry Cu-Au, base metal hydrothermal breccias and low-sulphidation gold veins. Rapid uplift and erosion has resulted in a highly variable preservation of styles of mineralisation adding further diversity within the mineralised districts and telescoping within deposits.

Jan 1, 1999

Authors have been conducting research on autonomous loading operation by wheel loader. Autonomous loading cycles has been demonstrated with real size experimental model. In V shape loading operation, travelling between scooping point and dumping point is dominant factor for cycle time of the operation. The positions of scooping point and dumping point changes with advancing the operation. In the developed system, path planning is performed at the beginning of every cycle. The path is formed by combination of curve and straight path elements. During travelling on the planned path, path following control is applied on the loader to keep position error in narrow range. Positioning of the loader is based on dead reckoning with correction by global positioning system (GPS) data. In a process of path following control, control value for steering angle is determined based on position error in lateral direction. Proposed method of path planning and position control is installed and tested in the real size experimental model. The detail and results will be described in the paper.

Dec 6, 2010

By K L. Brown, J L. Mauk

Sulfide-rich scale occurs in steam and water lines at the Ohaaki geothennal field,Taupo Volcanic Zone, New Zealand. Precious metals show very high concentrations around areas ofpressure reduction (Au 15500 ppm, Ag 68800 ppm). Pyrrhotite dominates at the orifice plate due to low PH2s1PH2 conditions. Sulfide mineralogy in the scales is consistent with alteration mineralogy of the reservoir rocks. Separated steam then produces a mainly pyrite/magnetite mineralogy, with lesser chalcopyrite, where textures reflect high flow rates and high levels of supersaturation. This study outlines the effect that pressure and subsequent temperature decreases have on the mineralogy, chemistry and textures of sulfide scales.

Jan 1, 1998

There are circumstances where the ordinary techniques of experimental variography in geostatistics û now in common use despite their recent origin û are not quite successful. This paper describes a new addition to the geostatisticians tool kit developed by one of the renowned leaders in the field to cope specifically with these circumstances. Possible application of this technique will be outlined when it will be seen that there are still problems remaining to be solved in its use for economic evaluation of deposits with irregular mineralisation.

Jan 1, 1984

By S McKinley

"The White Mountain sediment-hosted gold deposit is located in north-eastern China. Mineralisation is associated with silica–hematite–altered polymict breccias that occur within dolomite at or near the contact with overlying sandstone. Economic gold grades are controlled by the distribution of the polymict breccias and can transition rapidly to low or zero grade over short distances. This results in sharp and highly irregular ore contacts on whose accuracy proper stope design and ore control is reliant at this blasthole underground mine.Short-term planning and ore control utilise a grade control model created from infill drilling and grade control sampling (ie face and wall sampling). Typically, the grade control model was maintained by time-consuming manual editing of earlier made contacts to incorporate any new data. This approach also was quite error-prone due to: the complexity of the breccia and ore grade contacts irregularly oriented and/or insufficiently dense drill holes inconsistent incorporation of grade control sampling. These errors resulted in unplanned dilution and ore loss due to inaccurate interpretation of the ore contacts.The primary advantage to implicit geological models over conventional, manually-built wireframe models is that they can be updated very quickly and frequently. In a mine setting, the power and efficiency of using an implicit model is greatest where the use of manual inputs or editing can be minimised. Recently a workflow was set-up for the mine geology team to create an implicitly-modelled ore shape for short-term planning needs by using all data, especially all grade control samples. The resultant 3D shapes provided metre-scale accuracy and consistently reconciled complex ore geometries much faster and to a higher degree of quality relative to the wireframe model. The mine stakeholders can now obtain an accurate ore model that will always be in sync with available data.CITATION:McKinley, S, 2017. Application of implicit geological modelling to improve the grade control process at White Mountain gold mine, Jilin Province, China, in Proceedings Tenth International Mining Geology Conference 2017, pp 385–392 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 20, 2017

By I Hustwick

New Zealand Steel Mining Limited operates two independent sand mining operations on the West Coast of the North Island of New Zealand. Waikato North Head 30 km south of Auckland supplies ironsand concentrate as the raw feed for New Zealand Steel's works at Glenbrook and Taharoa 70 km further south, exports ironsand concentrate to Japan.   Taharoa uses two sets of six low pressure Warman centrifugal pumps in series to load bulk ore carriers 3 km off shore through two underwater pipelines. Waikato North Head delivers the ironsand to Glenbrook 18 km through a 200 mm ID buried pipeline using two stages of high pressure positive displacement (HPPD) pumping.   A high level of operating and maintenance expertise has been developed since commissioning the two systems which are proving to be reliable, efficient and of minimal impact environmentally.

Jan 1, 1990

By A F. Wilson

The use of stable isotopic measurements as a technique for elucidating the origin and history of the water in hydrothermal fluids is relatively new. Recent studies have emphasised the importance of meteoric water in the formation of many hydrothermal ore deposits including many epithermal gold-base metal deposits which occur in faulted volcanic terrane. Other vein-type gold ores are believed to have formed from fluids of magmatic or metamorphic origin and exhibit characteristic d180 values. These values also give information regarding temperatures and the degree of equilibrium. Preliminary oxygen data for some important gold deposits of eastern Australia are evaluated in the context of styles of mineralisation.

Jan 1, 1980

Effects of High Pressure Grinding Rolls on Platinum-Bearing Ores and the Flotation Response as Compared to the Conventional Ball Mill Three major PGM ore types from the Bushveld Complex of South Africa: Merensky, UG2 and Platreef were comminuted with the use of the high pressure grinding rolls (HPGR). The influence of the feed characteristics and the various operational and design features of the HPGR on energy consumption, throughput, mineral liberation and PGM flotation recovery were investigated. The test work variables included two feed top sizes of 12 mm and 6 mm, specific grinding forces ranging between 3 - 7.5N/ mm2 and zero gaps of 1.5 mm and 3 mm. The results show that the influence of the HPGR operational and design features on energy consumption, throughput, mineral liberation and PGM recovery are ore dependent. The size reduction-specific energy relationships show that the most energy efficient utilisation of the HPGR for Platreef ore was at the lower specific grinding force of 3N/mm2 and the zero gap at 3 mm. For Merensky and UG2 ore on the other hand, the most energy efficient operation was at the higher specific grinding force of 7.5N/mm2 and the zero gap of 1.5 mm. At a specific energy input of 3 kWh/t, reduction ratios (F50/P50) of 6.5, 3.8 and 10 were obtained for Merensky, UG2 and Platreef, respectively for feed top sizes of 12mm. Further application of the HPGR as a pregrinding stage to a ball mill showed a 25 - 30 per cent increase in throughput for Merensky and UG2 ore. Batch flotation tests performed on selected samples appear to indicate that ore comminuted with the ball mill had superior grades compared with that ground with the HPGR. However, Merensky and UG2 ore comminuted at different HPGR operating conditions showed distinctions in PGM recovery. Platreef on the other hand did not appear to show any differences. Therefore, this study highlights the significance of ore type and operating variables in HPGR applications with regards to energy efficiency, throughput and PGM recovery.

Sep 13, 2010

By B Kretschmer, G Bartel, B de Villiers, W Watt

"The Nyrstar Port Pirie Smelter, located on the eastern shore of the Upper Spencer Gulf in South Australia 230km north of Adelaide, began operation in 1889 to process lead concentrate from the Broken Hill lead and silver mines. The site still operates an updraft sinter machine, commissioned in 1955, with the product fed into a blast furnace. While sinter plant technology has changed and improved since 1955, development has reached the stage where further enhancements are not possible or economic. High purity lead concentrates command lower margins and for the smelter to remain economically viable a wider range of higher value materials must be treated. The current flowsheet cannot meet this demand. Additionally, community blood lead levels particularly in children below four years of age, are a critical indicator used to measure the site’s environmental performance. The smelter’s environmental licence to operate is dependent on meeting future community and regulatory expectations. To achieve this a major step change in the emission performance of the smelter is required. Since 2008 pre-feasibility work has been undertaken to develop a new flowsheet and business model to allow Port Pirie to operate sustainably into the future. The main requirements were for the smelter to reduce lead and sulfur dioxide emissions that impact on the local environment and community to meet current and future environmental expectations, as well as dramatically reducing current feed constraints and change the business case from a marginal business to a sustainable profitable business. After reviewing all practical options a decision was made to replace the sinter plant with an Outotec Top Submerged Lance (TSL) furnace. This paper describes how the new furnace technology was selected and how it will be integrated into the present flowsheet; the unique funding arrangements that are in place to deliver the redeveloped site; and future opportunities that are associated with the implementation of the new flowsheet. CITATION: De Villiers, B, Bartel, G, Watt, W and Kretschmer, B, 2015. Nyrstar Port Pirie redevelopment, in Proceedings MetPlant 2015, pp 325–337 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 7, 2015

By Probert D. H, Wright E. A, Taylor B. L

A general description of the geology of the Southern Coalfield is given. The relationship between the Illawarra Coal Measures, the overlying Triassic and the underlying Upper Marine Series, of Permian age as are the Coal Measures, is briefly explained and thestratigraphy of each is described. The eight coal seams are then treated in slightly more detail as to their thickness, quality, areas of distribution and best occurrences.In the last few years each of the authors has been concerned with one phase or other of the stTucture of the field in detail or in mining operations with the result that it is now possible to name a number of monoclines, anticlines, domes and synclines defined in detail. A minor quantitative study has been made of faults and dykes with regard to form, direction intensity and inter-relationship. It seems probable that with the further collection of data a more detailed study in these matters will be of considerable value to the economy of mining in the Southern Coalfield.

Jan 1, 1958

Removal of Arsenic in Fluorite Ore by Simultaneous Grinding-Leaching with NaHS Generally speaking, a high-grade fluorite ore is converted into hydrogen fluoride (HF), which is essential for the semiconductor manufacturing. With the continuous depletion of resources, novel technologies for processing low-grade fluorite ores are urgently needed, in order to lower the arsenic concentration to less than 100 mg/kg. In this study, a low-grade fluorite ore was upgraded by removing arsenic, which is difficult to remove by conventional method. The mechano-chemical leaching of fluorite ore (i.e. the sample was ground in presence of NaHS, using a beads mill) was carried out to investigate the removal of arsenic from the low-grade fluorite. Experimental results showed that the arsenic concentration was reduced to 73.2 mg/kg.

Sep 13, 2010

By H Thanasekaran, L Christodoulou, J Kohmuench

"Column flotation has been successfully applied to iron ore concentration since the 1980s with the goal of reducing silica content and allowing for the efficient production of pellet feed. Since then, columns have been widely used in iron ore processing due to: their lower capital and operational costs when compared to conventional cells their ability to generate higher concentrate grades and recoveries.Currently, more than 100 columns have been installed within Brazilian iron ore processing circuits for rougher, cleaner and scavenger duties. Despite it being a well-established approach, several technological advances have improved column design, accessories and performance. This work presents the performance of some iron ore columns in Brazil and the recent technological developments.CITATION:Thanasekaran, H, Kohmuench, J and Christodoulou, L, 2013. Column flotation of iron ore - status and advances, in Proceedings Iron Ore 2013, pp 479-484 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 12, 2013

By C E. Vidal

Geological exploration and mining development increased their intensity and rate of success during the last five years in Peru. Particularly relevant are the mining projects of Yanacocha and Pierina for epithermal Au and Ag. Also relevant are the new mining operations at Iscaycruz and Uchucchacua for limestone replacement Zn- or Ag-rich base metal skarn deposits. Miocene continental volcanics host the low-grade but near-surface orebodies of the Yanacocha mining district in Cajamarca. Several deposits have been mined since 1994 with open-pit and heap-leach gold production increasing from 300 000 ounces to 1 300 000 ounces in 1998. In a similar geological setting, but with three times the grade of Yanacocha, the Pierina valley-leach operation in Ancash is set to produce 800 000 ounces Au during 1999. At Iscaycruz in Lima, Cretaceous limestones host massive pyrite and sphalerite skarn deposits with 10 to 20 per cent Zn. Mining and milling were started in 1996 with last yearÆs production rising to 180 000 tonnes of Zn concentrates. At Uchucchacua, selective underground mining of fracture-controlled Ag skarns, with 400 to 420 g/t, has been recently increased from 1200 to 2000 tonnes per day to produce 5.5 million ounces Ag during 1998. Advanced exploration projects are located in the framework of nine Phanerozoic metallogenic provinces. Mineral deposits of preferred attention are precious metal disseminations and veins, base metal replacements and skarns, porphyry Cu (Mo-Au), Mississippi-Valley-type Zn and base metal volcanogenic massive sulphide deposits. Geological discovery of new orebodies enables a sustainable development of the mining industry in the country.

Jan 1, 1999

By D Matthews

With a brownfield project comes control integration challenges. The Khumani Iron Ore Mine’s second phase expansion posed a number of challenges as there was substantial brownfields work conducted. The fi rst phase was the compilation of the modifi ed process functional specifications for the project. The second phase was an audit on all of the operational sequences; this included a comparison between the SCADA sequences, sequential starts analysed from the historian data (with the potential for improvements made by the plant operators in manual start-ups) and what was proposed in the process functional specification. Differences, inclusions and missing equipment were highlighted. The third phase was the comparison of interlocking and control in the PLC with the updated process functional specification; this was done during the coding process. Running parallel to the three phases was the SCADA integration; tie-ins to the existing SCADA were conducted on maintenance days and shutdowns, in many instances with ‘dummy’ equipment to get the operational staff accustomed to the new interface. This paper details each of the phases, the success of this methodology as well as the pitfalls experienced.

Jul 11, 2011

Evaluation of Comminution Circuit Design for Sustainability Using EcoNomicsTM

Sep 13, 2010

The optimisation of a mining operation requires precise ore grade control, metallurgical accounting, and laboratory sampling protocols, which are implemented by using accurate and flawless sampling systems. Good sampling practices, and sampling technologies in these fields have been historically poor and too many existing sampling systems available on the market are flawed in many ways. This is mainly the result of a poor understanding of the Sampling Theory, and the natural result of international standards on sampling that fail to present the Sampling Theory in a logical way, that still promote non-probabilistic sampling, and that fail to address the important details that make a correct sampling system. Many standards barely mention the Sampling Theory in appendices when it should be clearly the main body of a reliable standard on sampling. As a result, many standards show only little expertise in the Sampling Theory. Conventional statistics should only be a scientific tool for the Sampling Theory to reach its height, which has always been well understood by its creators. Conventional statistics can indeed be addressed in appendices of standards in sampling, but not the other way around. Until the Sampling Theory is recognised as the main body of a standard on sampling, incorrect sampling technologies will plague the market, and make it impossible for mining operations to optimise their mining and metallurgical processes. This paper makes a short list of correct new sampling technologies that have been created with respect to the principles taught in the Sampling Theory. Also, suggestions are presented to create better international standards on sampling, which would provide a stronger incentive for manufacturers to build correct sampling systems, and for engineering firms to install only sampling systems that respect the rules of sampling correctness listed in the Sampling Theory.

Jan 1, 2004

By K A. Campbell, K A. Rodgers

The Plumduff sinter occurs at Whenuaroa, near Puhipuhi, approximately 30 km north of Whangarei. It is one of three residual sinters in the southern portion of a mid- to late-Pliocene geothermal system. The deposit consists of many large sinter breccia boulders, including rudrocks (coarse breccias), scattered around the flanks and summit of the small conical hill of Plumduff. Three types of sinter breccia occur: (i) rudrocks consisting of large, angular to sub-angular clasts of layered sinter up to 0.8 m across, as well as smaller clasts of sinter (20 - 100 mm dia), and fragments of stromatolitic structures; all clasts are supported in a matrix of microcrystalline, transparent to translucent to milky quartz; (ii) fragments of layered angular to irregularly mottled sinter of white to grey or bluish hue supported in a translucent to opaque silica matrix; (iii) smaller, matrix-supported breccias with clasts both partially surrounded and/or penetrated, by a clay-like weathering rind, and sinter conglomerates with rounded to oblate clasts. Three principal types of fabrics constitute the bulk of the sinter: (i) stromatolites, including columnar, palisade and filamentous networks, showing progressive silicification, in fenestral, tufted to clotted fabrics; (ii) peloids and pisoids; (iii) plant-rich facies in which various silicified plant species occur in a silica matrix. All fabrics have counterparts in hot spring deposits in the Taupo Volcanic Zone formed at temperatures from 75¦C to 35¦C. Also present is steam-condensate-produced alteration: kaolinite and alunite as well as boulders of quartz lattice texture. Cinnabar only occurs in sinter on the north and south central slopes of the hillside. No quartz veins or geyserite were recognised.

Jan 1, 2001

Despite technological improvements and better understanding of the hazards, coal dust explosions stilI occur. Experimental explosions in galleries in various countries extend knowledge with the constant aim of providing safer working conditions. The inadvertent ignition of an accumulation of methane is the traditional initiator of the coal dust explosion.There are specific parameters of coal dust explosibility and explosion propagation, including the important volatile matter in the coal, fineness and dispersibility of the dust and its concentration. Accepting that initiation cannot be absolutely prevented, it is necessary to consider explosion suppression. While both limestone dust and water are the chosen explosion suppressants, in practice water has more limitations to its efficacy when related to the degree of explosion violence. These data give rise to the criteria for explosion suppression, differences in favoured mining geometries, and using the same principles, to differences in suppression treatments.

Jan 1, 1988