Search Documents

Titanium dioxide (TiG ) is produced 2 commercially by two methods generally referred to as the "sulfate" route and the "chloride" route. The SCM Corporation, in supplying 15% of the world's demand for TiO 2, uses both of these processes. Of the two processes the sulfate route is generally regarded as the older and more established technology. Worldwide the sulfate route accounts for some 70% of total Ti02 production. However, in the U.S.A. the chloride process accounts for 80% of production. The processes vary in chemistry and raw material requirements. In the "sulfate" process finely ground ilmenite or titanium slag is digested with sulfuric acid to produce a porous "cake" vrnich is extracted with water and recovered liquor. The solution is treated with scrap iron to reduce any ferric ions to the ferrous state which is then crystallised and removed as ferrous sulfate heptahydrate. The liquor is concentrated by evaporation and hydrolysed to form the insoluble hydroxide which is filtered and washed free of impurities. This is converted to the dioxide by calcination at 800 - 1000¦C and milled to break up any aggregates. The "chloride" process uses a higher quality feedstock of natural or synthetic rutile and/or high grade titania slag. The feedstock is mixed with ground high-purity coke and chlorinated at 950¦C in a fluidised bed. The resulting crude titanium tetrachloride is purified by distillation and chemical treatment. The purified titanium tetrachloride is burned with oxygen or oxygen enriched air to give titanium dioxide and chlorine, which is recovered and recycled to chlorination. Titanium dioxide pigment from both processing routes undergoes similar finishing techniques. It is subjected to further stages of wet and dry milling, then coated with layers of inorganic oxides in order to enhance its properties for specialist applications.

Jan 1, 1986

Proposals for engineering works in the River Dement in recent years have been made in the context of very little geological informat- ion. Breakage of the Tasman Bridge, forced a complete re-appraisal and collection of inform- ation in order to select a new site and predict problems. Seismic, magnetic and gravity methods foll- owed by drilling have allowed an assessment of the nature, thickness and distribution of mater- ials underlying the river bed. Key discoveries included recognition of low seismic velocity silts (1100 m/s) and a separate channel for the river since the Late Tertiary.

Jan 1, 1977

By Li YQ, Yoon RH

The photoresponse of natural mineral pyrite and galena electrodes has been studied in aqueous solutions on freshly fractured surfaces (some fractured in situ) using moderate overvoltages. When fractured in situ, the electrode potential of both minerals instantly drops several tenths of a volt. Pyrite exhibits a spontaneous anodic photocurrent at fracture, which indicates upward band bending (depletion layer) on the n-type electrodes. The negative surface charge responsible for the depletion layer is believed to arise from a surface state that is intrinsic to pyrite surfaces, possibly modified by hydroxide ion adsorption. The flat band potential, Vty, of pyrite is at approximately -1.0 V (SCE) at pH 9.2 but to reach V(b, pyrite has to be cathodically decomposed. In contrast, galena assumes the flat band potential at fracture. Subsequent polarisation of galena at potentials positive of Vth produces an anodic photocurrent (upward band bending) and polarisation negative of Vro a cathodic photocurrent. Most of the galena electrodes studied were degenerate n-type and at potentials negative of Vtb, no cathodic photocurrents are observed, indicating the bands cannot be bent downward, consistent with the Fermi level at the surface merging with the conduction band edge near Vn,. Several were close to intrinsic, with the photocurrent changing sign near Vn,.

Jan 1, 1993

By Isaac AK

The combination of shot-firing and stage loader, and a prop and bar support system is an accepted drivage method. The support configuration is based on the final prop density, and assumes relitively uniform load sharing between the props. During the development of a longwall faceline at a medium depth (approximately 600m) British coal mine using such a drivage method, a fall occured overnight, effectively closing approximately 40m of the drivage. The severity and speed of the fall prompted an investigation into the performance of the temporary support system installed prior to chock installation. This paper deals with the investigation which disclosed some major contributory factors towards loss of strata control.

Jan 1, 1986

By S Van Duin, I Porter

This paper discusses how advanced manufacturing technology (AMT), which is fundamentally reliant on and developed via multi-disciplinary skills, has benefitted non-mining industries, and what lessons can be derived from this experience to benefit the mining industry, particularly underground coal mining. Examples of AMT use in æconventionalÆ industry, some drawn from the more than 25 years experience in many different industries of the Automation and Robotics team at the University of Wollongong, are described to show typical benefits, risks and opportunities expected in using AMT. Applying AMT to mining brings many unique challenges and this paper expands on these and then provides practical examples of how a multi-disciplinary team can develop new processes and systems leading to productivity, safety and other benefits for underground coal mining.

Sep 26, 2011

By C B. Valentin

It is acknowledged that the analysis of iron ores using X-ray fluorescence (XRF) for major and minor elements is best carried out on fusion discs. This method of sample preparation eliminates mineral and particle size effects which can lead to biased results when using pressed powder pellets. However, the fusion disc method is costly as it requires a high capital investment in platinumware, requires experienced operators and uses expensive fluxes. Also, the dilution effect complicates the analysis of trace elements. For many applications, such as exploration and mining control, the method of XRF analysis of iron ores by pressed powder pellet probably provides data of adequate quality. Kumba Iron Ore, an iron ore producer in South Africa, recognises this and carries out most analyses of iron ore by pressed powder pellet and uses the automated fusion method mainly for certification of in-house calibration standards and quality control (QC) samples that are used for validation of pressed powder pellet method purposes. Automated fusion is also used for analysing the composite export shipping samples. All the other exploration, production, despatching and plant operation samples are done by the pressed powder pellet method. Automation of sample preparation procedures should improve the quality of data for pressed powder pellets. To compare the precision of the three methods of sample preparation and XRF analysis, 20 aliquots of a QC standard were prepared and analysed by each procedure/preparation method. The results and statistical data on the most important elements, Fe, K2O and P, are as shown later in Table 2.Clearly the precision is best for the auto prepared fusion discs, as expected, and worst for the manually prepared pressed powder pellets. However, the data generated from the auto prepared pressed powder pellets compare remarkably well against those from the auto prepared fusion discs.

Jan 1, 2007

By Riley S. J

The basic aim of mine planning is to design mine layouts and schedules that achieve optimisation of operations, minimum cost and maximum resource recovery. Successful accomplishment of this aim is facilitated by timely and comprehensive rehabilitation planning commencing at the pre-feasibility stage and continuing until the end of mining. Incorporation of a final landfomt design for waste rock dumps in a mine plan requires a prediction of surface stability, which may be achieved through erosion modelling. Erosion prediction models can be placed in two broad categories: soil loss prediction models eg USLE and CREAMS, and geomorphic models such as SIBERIA. A waste rock dump landform design based on selected slope form and grade and drainage systems should be developed as part of planning. A digital terrain model (DTM) of the landfonn should then be produced which can be modelled for long-term erosional stability using pre-determined parameter values. If acceptable standards of stability are not achieved, the landform should be redesigned and remodelled until the desired result is obtained. The planning process incorporating models requires knowledge of spoil or waste rock properties and model parameter values. This information is site specific and can be obtained from drill cores or costeans at the pre-mining stage and from spoil or waste rock during the mining stage. Realistic model parameter values are critical in post-mining landfonn design and can be obtained by several methods, including rainfall simulation, monitoring, geochemical analyses and grain size analysis.

Jan 1, 1994

By W A. van der Westhuizen

Selective mining played a major role in saving a mine and a communityÆs existence as well as creating a working culture that is the model for all KumbaÆs mines. The successes that resulted from selective mining led to receiving KumbaÆs highest award (it was the Gold Medal Breakthrough project of 2003) as well as the productivity award at the National Productivity Institute award ceremony in 2004. Kumba was established in November 2001 (previously Iscor Mining). The new company identified Mineral Resource Management (MRM) as one of its key drivers and an initiative was launched to define MRM in the Kumba way. Best MRM practices at the Kumba mines were included in the definition. Selective mining was born out of this initiative. One of the key principles of good MRM practice was identified as: æThere must be a balance in the operational processÆ. This principle was applied with great success at Thabazimbi Iron Ore mine in the Limpopo province, South Africa. The emphasis of this paper will be to show how value can be unlocked throughout the whole mining value chain. In the past (up to 2001) the mine went through a number of crisis situations: planned production performances were not reached, the stripping ratio was extremely high with two new pits, the product beds were not of constant quality, slope failures were big risks, flooding could and did cut off half of the ore supply, and restructuring demoralised staff.This paper focuses on: selective mining throughput drivers, and selective mining and its role in achieving this balance.The results were dramatic, with huge improvements in production results, stockpiles, plant yields and product bed specifications. The mine was brought into balance and a self feeding loop was created with positive spin-offs up to this day.

Jan 1, 2005

By Case JE

Complete Bouguer and isostatic anomaly maps compiled for Costa Rica provide new insights into the crustal structure and mineralization. Terrain corrections were approximated from the station to a radial distance of 167 km by computer using a 3- minute digital elevation model of Costa Rica and surrounding areas. Isostatic corrections, based on Airy-Heiskanen compensation, were also calculated from 0 to 167 km using the 3- minute elevation model and from 167 km to 180 degrees using combined topographic and isostatic reduction maps. Costa Rica can be divided into four main terranes based on gravity data: a Pacific coastal region, a Pacific inland area, a central region, and a Caribbean coastal region. Negative gravity anomalies along the Pacific coastal margin correlate with an offshore sedimentary basin, and large positive anomalies correlate with mafic and ultramafic igneous rocks on the Santa Elena, Nicoya, and Osa Peninsulas, and at Puerto Quepos. Pacific inland anomalies are separated from the Pacific coastal region by a steep gravity gradient, and over the Coast Ranges a major gravity low overlies a thick section of low- density sedimentary rocks. In the central region, a major gravity low occurs over a thick low-density Quaternary volcanic complex in the Cordillera Central, north of San Jose. A prominent feature of the Caribbean coastal region is an interrupted gravity low over the Limon Basin that reflects a thickening of low-density sedimentary rocks. A conspicuous gravity lineament, trending northeast separates northern and southern Costa Rica. The lineament is defined by the termination of several major gravity anomalies including those over the Coast Ranges, Cordillera Central, Puerto Quepos, and Limon Basin. In addition, the lineament correlates with other geological and geophysical data including: northeast-trending faults, the southern limit of large Quaternary volcanoes, the segmentation of the middle America volcanic belt, and a seismicity gap. This lineament may be the expression of a previously unrecognized major northeast- trending fracture zone in central Costa Rica. An important economic implication of the gravity lineament is a correlation with the termination of gold and porphyry copper deposits in Costa Rica.

Jan 1, 1987

At the beginning of the seventies pre- drainage of methane was introduced in West German coal mining in order to reduce the gas emission from the worked seam. After three pilot tests on the "Rheinland" Colliery (86 boreholes in seam "Prasident"), "Bergmannsgluck/ Westerholt" Colliery (23 boreholes in seam "Gustav") and "General Blumenthal" Colliery (27 boreholes in seam "Hugo" and 170 boreholes in seam "Karl") systematic large scale tests with extended investigations were carried out un the "Rheinland" Colliery (127 boreholes in the seams "Anna", "Blucher", Prasident"). During this time an analogous test was carried out on the "Consolidation" Colliery (21 bore- holes in seam "B"). In these studies and tests the technical feasibility, efficiency and economy could be proved, so that pre-drainage of methane starts spreading. On the "Rheinland" Colliery pre-drainage has become common practice in gassy seams. Mainly two points impede a faster spreading of method: 1. in many cases the necessary requirement, that one or both of the gate roads should ire driven 6 to 12 months before the face is worked, is missing. This is mainly due to the difficulty of retreat mining in passe seams.

Jan 1, 1982

By Moore A. J

Blasting in mines in an urban environment can be conducted safely and within regulatory vibration limits by careful attention to detail and the application of correct techniques. Factors affecting blast vibration are described using surface and underground mining examples. An understanding of these factors provides an essential base for effective planning and operational control. Techniques are described for assessing and predicting vibration levels and the presentation of data for planning purposes such as environmental impact statements for new projects and the protection of buffer zones around existing operations.

Jan 1, 1997

From August 1962 to June 1976 Peko Mines Ltd. produced Gold Bullion at the Peko Control Mill using 18x24 Denver Mineral Jigs and strake tables. Gold ores treated during this period were obtained from Orlando, Juno and Ivanhoe Mines and from the Warrego Mine after 1974, all in the Tennant Creek Area of the Northern Territory. With the downturn in copper prices Warrego Copper ore mining ceased and the copper Smelter closed down in February 1974, Warrego gold ore continued to be treated in the Peko Concentrator.

Jan 1, 1978

By Waters JC

Pseudoclastic hydrothermal alteration textures occur within quenched coherent dykes forming part of a subaqueous dome complex (-4 Ma) on Ponza Island, Italy. These textures are similar to those observed in considerably older (-500 Ma) subaqueous volcanic rocks at a number of localities throughout the Mount Read Volcanics in Tasmania and elsewhere in ancient volcanic sequences of this type in Australia. This is significant because the processes of formation, hydrothermal alteration and secondary mineralisation of ancient volcanic sequences may be better understood if we can make comparisons with modern analogues. Observations at Ponza imply that these pseudoclastic alteration features form synvolcanically or immediately after dyke emplacement and lava extrusion. This is compatible with scenarios presented for their formation in ancient sequences in the Mount Read Volcanics, Tasmania.

Jan 1, 1995

By Fiedler VA, Threadingham GM, Leckenby DF, Clarkson CJ

The Utah Development Company Research and Development Laboratory has embarked upon a programme of optimisation of the company's coal preparation plants. This goal is being accomplished in a three-fold manner - use of pilot plant equipment for optimisation and modelling of the various unit operations, evaluation or development of on-stream ash analysis for process control, and evaluation or development of alternative processes. In each of these areas, digital data acquisition- and at a later stage, process control feedback, is being extensively utilised, based largely upon the use of the HP85 and HP9915 desktop computers. A variety of input/output configurations such as HPIB, BCD, GPIO are used, and at times supplemented by microprocessors such as the Intel 80/05 to assist in data transfer. This paper will discuss a number of specific projects, especially in relation to the manner in which the variables are monitored, and the data later retrieved and analysed.

Jan 1, 1983

PAPERS : 1 COMPUTER AIDED DESIGN OF MINE WATER MANAGEMENT - Z KESSERU 2 THE HYDROGEOLOGICAL PROBLEMS OF GROUNDWATER PROTECTION IN MINING REGIONS - V A MIRONENKO 3 WATER MANAGEMENT OF THE MAE MOH PROJECT -òò SIRI CHITCHOB 4 WATER MANAGEMENT AND WATER TREATMENT AT GOLDPN CROSS - M P A WILLIAMS

Jan 1, 1988

Optimisation and sensitivity analysis of final pit limits is now an accepted procedure for open pit planning studies. Tools to assist the design engineer in an underground metalliferous mine to make optimal choices for the selection of major development, stope geometry and cut-off grade analysis have not been available. The engineer has had to rely on experience and a limited analysis of design alternatives. A new tool called the `floating stope' has been developed to define the optimal (boundary) limit for material that can be economically extracted by underground stoping methods. The method is analogous to the `floating cone' method of open pit optimisation. The geology and mineralisation are modelled as a regular or subcell block model. Included in the model are structural and geotechnical features, and any previously mined out areas. Inputs to the procedure include the minimum stope dimensions, cut-off grade, stope head grade, and the way in which dilution is to be calculated. The optimisation procedure can be directed to maximise ore tonnes, grade, contained metal or the economic (dollar) value of material mined. The procedure can be applied at each stage of mine evaluation and design to assist with preliminary resource appraisal, selection of stoping methods, and detailed mine design. As with open pit optimisation procedures, manual intervention by an experienced engineer is required to produce practical and detailed designs. This practical design should follow the optimised design as closely as possible. The paper outlines the algorithms used in the definition of the stope envelope, and describes the analysis and results of several case studies where the optimisation procedure has been applied.

Jan 1, 1995

By Gupta A, Hall ST

The grinding characteristics of quartz which is normally associated with gold bearing ores in Kalgoorlie area was examined in a stainless steel laboratory size ball-mill in the presence of inorganic and organic surface active reagents. The cationic species considered were Fe3+, Cu2+ and Ca2+, and the anions were CO? and S2 as these are normally present during the process of grinding of gold ores in the region. The organic surfactants examined were K-amyl- xanthate, dodecylamine-hydrochloride and the Grinding Aid XFS-4272 manufactured by Dow Chemical The study was primarily based on an examination of the electrokinetic properties of quartz surface in the presence of the grinding reagents. Zeta potential at different reagent additions and pH values in the presence of individual reagents were examined and the corresponding grinding charcteristics determined. A correlation has been indicated between the grinding characteristics, as measured by the -53um size fraction produced, and the surface energy of quartz. It was observed that an

Jan 1, 1978

The Northland Peninsula of northern North Island, New Zealand contains a complex and diverse record of volcanism which reflects rapid tectonic changes during the late Cenozoic. The main volcanic associations observed on the peninsula are late Cretaceous- early oceanic crust obducted onto Northland at the end of the Oligocene, Miocene arc-type rocks and Pliocene-Quaternary intraplate basalts. This sucession of volcanic successions can be related to tectonic convergence developing into subduction and followed by a an environment of tectonic tension. While the volcanic activity is ultimately linked to specific tectonic regimes, because of rapid change magmatism was decoupled from the specific tectonic event. This decoupling of magmatism and tectonism appears to be a feature of the zones of plate interaction in the southwest Pacific region.

Jan 1, 1990

By Takagi T, Seetharam R, Sie SH, Naito K

Tin-polymetallic vein type deposits are one of the major source of metal producers in the Circum Pacific Belt. This type of deposit is of great importance for the modem electronics and medical industries because of their high content of rare metals (especially indium and bismuth). We have studied two representatives, Tosham of India (Cu-In-Bi-Sn-W-Ag-Au), and Mount Pleasant of Canada (Zn-Cu-In-Bi-Sn-W), using proton and electron microprobes in order to delineate the distribution of medical/high-tech rare metals. The electron microprobe study showed that major indium carrier in such type of deposit are roquesite (CulnSZ), sphalerite, stannite and a Cu-Zn-Fe-In-Sn-S mineral; and that indium is incorporated in sulfides by coupled substitution like Cu + In = 2(Zn + Fe). The proton microprobe showed that indium at trace levels is also present in chalcopyrite and pyrite. In addition, zinc, copper, arsenic, antimony, selenium, tin, and bismuth are common in chalcopyrite and pyrite. Arsenopyrite contains nickel, copper, zinc, silver, tin, antimony and bismuth. In chalcopyrite and pyrite, zinc, arsenic, indium, bismuth and lead are higher in Mount Pleasant ore, but silver is higher at Tosham. Also thallium and gold were found only in Tosham pyrite. The Tosham deposit is genetically related to S-type magma, while the Mount Pleasant deposit is related to A-type granite. Tosham ore contains zinc-bearing biotites that coexist with chalcopyrite in ore bodies but Mount Pleasant ore lacks such biotite. We propose that the difference in elemental abundance between the two deposits are caused by the different character of source magma and different mineral associations of the ore body.

Jan 1, 1995

By Wilson CJN

The central Taupo Volcanic Zone is a region of intense Quaternary silicic volcanism accompanying rapid crustal extension. Modem central TVZ is the most frequently active and productive silicic volcanic system on Earth, erupting rhyolite at c. 0.28 m' s'. The rhyolites show no major compositional changes with time, but the total extent of magma chamber zonation has changed with the advent of rifting and crustal extension at c.0.7 Ma. At least 34 caldera-forming ignimbrite eruptions have formed a complex sequence of relatively short-lived, nested and/or overlapping volcanic centres in central TVZ. Taupo contrasts with other large silicic magmatic systems in the exceptionally high frequency, but small size, of caldera- forming eruptions. This contrast reflects the thin, rifted nature of the TVZ crust, that precludes the development of long- term magmatic cycles at Taupo.Within central TVZ, non-rhyolitic compositions have been erupted apparently irregularly in time and space; in particular there is no evidence for a geographic separation of basalts from andesites. TVZ is a rifted arc, but its segmented nature, high thermal flux and voluminous rhyolitic volcanism make it unique on Earth.

Jan 1, 1995