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By Canning RG, Uusna S, Goodheart BA

The paper outlines the development of"a process for removal of iron oxides from ilmenite, thereby upgrading the TiO2 content of Western Australian ilmenites, from 55 to approximately 90 per cent. In the first stage, the iron oxides are reduced with solid carbon (coal) to metallic iron. Experimental reduc- tions were carried out in crucibles,, a fluidised bed and a small pilot plant rotary kiln. The reduced'ilmenite is,then agitated in aerated water, in the presence of catalysts, so that the iron "rusts" away from the ilmenite'grains and the precipitated iron oxide is easily separable by decantation. The influence of variables on the rates. of reduction and oxidation are discussed, The oxidation rate was exam- ined for both - the' physical oxygen-transfer characteristics and electrochemically by reference to Peurbaix diagrams, which plot redox potential against solution 'PH, The upgraded ilmenite is expected to be an attractive material. for pigment -manufacture,, and the iron oxide has prospects of being a marketable by-product. The process may possibly be. applied, to .other..ores.

Jan 1, 1964

By Ballantyne GH

The Ladolam gold deposit on Lihir Island, in Papua New Guinea, is a large disseminated gold deposit hosted by hydrothermal breccias. The deposit occurs in the cupola zone of a 350,000 year old monzonite stock which is emplaced in the collapsed caldera of a shosho- nitic stratovolcano.

Jan 1, 1987

By P D. Williams

The Phoenix mine is one of NewmontÆs open-pit operations located in Nevada. Mining started in 2005, with the mine producing gold, copper and silver. The mine life is about 20 years. The gold grade estimation uses the Newmont in-house indicator kriging approach to handle the high variability in drill hole composite grades and support mining selectivity. Each block contains up to 200 subblocks with different gold grades. A flotation mill is designed to process oxide and sulfide ores, recovering gold, copper, and silver. An additional copper leach process is currently under study to process low gold and high copper oxide material with low copper recovery in the mill. The metallurgical recoveries and processing costs are dependent on many variables including rock formation, metallurgical domain, cyanide soluble copper and sulfide contents. This paper describes the Newmont in-house indicator kriging procedures and the revenue based mine planning software system implemented at Phoenix mine to address the complexity resulting from multi-process, multi-metal and indicator kriging model.

Jan 1, 2007

By M B. McKevitt, W J. Shaw

The main task of grade control on a daily basis is to define the material that should be mined to a destination under various categories. This can be determined by grade, lithology, quality and blending criteria. In the case of multi-element deposits or deposits with various blending or other processing criteria the optimum selection of ore block boundaries can be quite complex. In every case the balance between ore loss and dilution must be considered when designing the ore block boundaries and this becomes a risk-based decision when using the conditional simulation model. The use of such systems allows grade control to meet specific targets, such as budget tonnages and grades and blended product specifications. Two case studies are presented: the Prominent Hill copper/gold mine and the Rapu Rapu zinc/copper mine. Mining is based on a rational grade control strategy involving a number of factors, including strong geological control, advanced geostatistical approaches, such as conditional simulation, and optimisation of the ore blocking to meet production requirements. This provides an objective, transparent and repeatable grade control strategy.

Jan 1, 2009

The impulsive loading tests under confining pressure were performed to investigate the dynamic fracture properties of rocks in a triaxial stress state. The apparatus in this study consists of the Split Hopkinson pressure bar, a pressure vessel and hydraulic actuator. Magnetite-quartzite and limestone were selected for the test. The stress-strain curves and fracture strength under confining pressure obtaind in the tests were compared with those of the conventional triaxial tests. Finally it is concluded that on the effect of dynamic that on the effect of dynamic compressive strength of rock, dynamic elastic coefficient of rock and confining pressure etc. on the blasting result

Jan 1, 1990

By Hayes P. C

The kinetics of reduction of PbO-silicate melts in CO-N gas mixtures at 900¦C have been studied. Rea~tion rates were measured by moni- toring the CO2 content of the product gas. A wide range of gas and melt compositions and gas flowrates have been investigated. The overall reaction rates in heterogen- eous systems are typically characterised by a steady increase as the gas flowrate is in- creased. At low flowrates the processes are limited by gas film mass transfer. At high flowrates it is expected that the rates will tend to maximum values determined by either the rate limiting chemical reaction or diffusion in the condensed phase. In the present series of experiments it has been found that for any given gas composition the overall reduction rate goes through a maximum with increasing gas flow. The maxima, which occur at relatively low gas flows, are more than an order of magni- tude greater than those observed at high gas flowrates. The results of these and other experiments are presented and analysed. Possible rate limiting mechanisms in the reaction system and their implications regarding commercial reactors are discussed.

Jan 1, 1987

The patented "Epytensic" pump of Minnovation Ltd, a multiple piston pump, is used widely on shearer loaders and by partial high pressure watcr jet cutting strategically in relation to cutter picks not only improves cutting rates, but saves power and increases the life of gearboxes and picks, as well as improving dust suppression. The "Face Side Pump", also a piston pump, located on the ranging arm gearhead has advantages over gateroad pumps and shearer body pumps. The "Extraction Drum", hydraulic air mover system, linked with the above innovations and high pressure water, have further advantages in methane and dust removal. Some modifications providing these systems need workshop applications but most are possible underground with minimal changes to shearer profiles and advantages of minimising hosing, along with the other advantages stated.

Jan 1, 1991

Around no subject of technical )uterest have prejudice and wrong-thinking in the past so wrapped a web of obscurity as that of the corrosion of metals.It is a matter which has primarily concerned the engineer, but the paucity of his training in chemistry and electrochemistry has been the stumbling block to a better understanding of its mechanism.Now that the more important conditions controlling corrosion have been scientifically.established, it can be seen that, with the exception of but a few of the minor points, the electrochemical laws enunciated by Faraday, Helmholtz; Nernst, and others, are sufficient to include all the facts of the process.The word corrosion (derived from the Latin rodere-to gnaw) is so often wrongly applied that a definition at this stage would be useful. As now understood, it means the dispersion and waste of the useful solid metal by conversion into a useless compound which mayor may not be retained on or near the metal remaining.Commonly the presence of these compounds is regarded as evidence of corrosion, but the converse is not necessarily true; the lack of visible corrosion products on a clean surface of metal is no criterion of the absence of this change. It may be difficult to prove that the erosion of such a surface has been caused by chemical and not by mechanical effects alone.

Jan 1, 1932

By Bhaskara Sarma P V R

Solvent extraction of cobalt from an ammoniacal ammonium sulphate medium was carried out using Di(2-Ethyl Hexyl) phosphoric acid in kerosene as diluent. The effect of ammonium chloride and ammonium sulphate on the extraction efficiency was studied. The extracted species in the ammonium chloride and sulphate systems were CoAz2HA.NH4CI and CoA3.HA.2(NH4)2SO4, respectively. Ammonia scrubbing and cobalt stripping studies were carried out from loaded and ammonia free organic Respectively.

Jan 1, 1992

The paper describes the preparation of new rail guides, removing existing rails, and replacing with new rails in a vertical winding shaft.INTRODUCTIONThe general practice in coal winding shafts is the use of two cages, with one or more decks in which men and materials are raised or lowered. Winding speeds vary according to depth, the type of winding gear, and whether winding is done in downcast or upcast shafts. Each cage occupies a position between the centre and side of the shaft, with a clearance depending on the type of guides used. The function of the guides is to keep the cage in position throughout the entire depth of the shaft. There are three types of guides, two of which are in general use.1. Selected wood of about 6 in. square section, fixed to the side of buntons.2. Solid strand steel made up similarly to that of an ordinary wire rope, suspended from the head frame with weights attached to the lower end.3. Standard T-rail sections fixed to end or side buntons. Of the three types, 2 and 3 are in general use. The type used in the particular case, the subject of this paper, is T-rails of the standard section used in railway work.GENERAL DESCRIPTION OF SHAFTDetails of the shaft are as follow: Diameter of shaft: 22 ft. inside lining.Depth of shaft: 900 ft., including sump.Concrete lined throughout.VENTILATIONThe ventilation shaft is used for the upcast, through which all vitiated air passes to the main ventilation fan. Quantity of air passing up the shaft is 400,000 cu. ft. per minute. The air is highly saturated during the summer weather and slightly less...

Jan 1, 1947

By G J. Sparrow, M J. Fisher-White

A mineral and chemical characterisation study was conducted on ilmenite-rich heavy mineral concentrates sourced from the western sector of the Eucla Basin in southern Australia. Test work involved using X-ray diffraction (XRD), scanning electron microscope (SEM) and electron microprobe-based characterisation methods. Results showed considerable variability in the degree of ilmenite alteration between deposits with TiO2 contents varying from 53 - 63 wt per cent TiO2. Notwithstanding variability between individual deposits, the samples all had [Ti]/[Ti+Fe] ratios >0.5 consistent with a mineral assemblage of hydrated ilmenite or the hydrated, Ti-rich alteration phase pseudorutile (Fe3+2-x Ti3O9-3x (OH)3x). Accessory phases consisted of rutile (primary and secondary), zircon, aluminosilicates, quartz, Fe oxyhydroxides and spinels. Results for the most altered material are broadly comparable with data for ilmenite concentrates from the eastern margin of the basin. The mineralogy of the western Eucla Basin concentrates and the minor element composition of the ilmenite grains suggest they could be upgraded to synthetic rutile by a modified Becher process.

Jan 1, 2008

By Thompson D, Burgess G. C

Subsequent to large scale trials in 1987, the installation of a submerged lance Sirosmelt furnace system was approved in late-1988 for the cupellation of retort bullion to dore silver. Commissioning work commenced in June 1990. During the process air is lanced into a molten slag bath contained in a cylindrical vessel to rapidly oxidise the granulated feed bullion from 15 - 25 per cent silver to rough dore grade. The process is now an integral part of the Precious Metals operation replacing the first stage reverberatory cupellation furnaces to achieve productivity improvements, lower silver inventory and increased silver Recovery.

Jan 1, 1992

Having worked as a consultant for most of his 40-year working life, mostly as a mineral property valuer, the author has seen many poor valuations. Most were valuations of exploration tenements where the selection of the rather subjective, but necessary, geological inputs raised the main concerns. Those valuations involving iron ore prospects raise particular problems due to the special characteristics of such deposits. Iron ore is more like an industrial mineral rather than precious or base metals and Reserves are determined not by a traditional cut-off grade but by customer specifications. This is intended to be an overview/keynote paper on the current state of the growing (yet consolidating) Australian Iron Ore industry. It has now moved beyond Western AustraliaÆs æPilbara Big TwoÆ of Rio/BHPB (with the emergence of the irrepressible FMG and Hancock Prospecting) to include the YilgarnÆs æMidwest ManyÆ (including US re-entrant Cleveland Cliffs through Portman) and projects in other States. Ore types have moved from haematite Brockman to martite-goethite Marra Mamba (including the RobeÆs mesas and below water table Yandicoogina CIDs) and magnetite ore types. There are DSOs and secondary process feed. Mineral valuers have to reflect today upon these and many other determinants of value when choosing the most appropriate methodologies to adopt when technically assessing and valuing exploration tenements containing iron ore. Set against a frame work of the JORC Code (2004) and VALMIN Code (2005), the general valuation issues involved in using the cost methods (eg multiple of exploration expenditure), market methods (eg comparable sales, rules-of-thumb and joint venture terms) and income methods (eg synthetic discounted cash flow (DCF)/net present value (NPV) modelling) are discussed. Relevant factors when valuing iron ore properties are discussed, eg ore type, lump/fines ratio, stripping ratio, water table, impurities and grade, particularly the JORC confidence category of the identified mineralisation. Remoteness and access to existing rail infrastructure is a key consideration.

Jan 1, 2007

Many problems result when coal mine shafts are built in complicated geological conditions and serious shaft lining ruptures have often occurred in the eastern part of China since 1987. Grouting is applied as one of the major measurements for shaft lining ruptures. However, as the general location of reinforcement grouting for shaft lining is deep in or near the bottom aquifer, while using cement grout as the grouting material, the grouting mostly belongs to fracturing grouting in deep alluvium. In these conditions, the mechanism and behavior of fracturing grouting has not yet been understood. From these points of view, this paper describes the mechanism of shaft lining rupture and fracturing grouting and then discusses the effect of grout injection on the stability of shaft lining by means of numerical analysis and field data obtained so far.

Dec 6, 2010

In current mining practices it is desirable to bring about a substantial increase in both rate of face advance and productivity, thus compelling the mine engineer to consider better and more productive ways of mining. Transportation plays a vital role in achieving improved productivity. This paper focuses on horizontal transportation systems. Horizontal transportation is defined from the shaft station area to the end of the stope cross-cut. Traditionally, horizontal transportation is inefficient in comparison to vertical transportation efficiencies and accounts for a high proportion of South African mine accidents. Thus, the role of horizontal transportation has been investigated in detail, as it offers the greatest chance for improvement. The purpose of the paper is to provide a best practice guideline for the design of horizontal underground transport systems. It is intended that the document be used by mine designers and planners as an aide memoir during the design process and benefit may well be gained from retrofit and reorganisation activity. The paper looks at transport systems suitable for deep level gold mining in South Africa and evaluates such items as management, scheduling, and haulage systems. Current transportation systems for personnel, material and rock transportation are evaluated, gaps in technology highlighted, and recommendations made.

Jan 1, 2003

Autocompression and virgin rock tempera ture have a marked influence on the ventilation of the lower levels at North Broken Hill Limited N.S.W. To maintain comfortable working temp- eratures without penalty to working hours, increase in airflow or the cooling of the work area is necessary. The use of refrigerated air cooling is discussed. Ventilation of underground mining opera tions at North Broken Hill Limited is accomplished by downcasting air through No.3 shaft, the main operating shaft, 1581 m deep, with additional air through No.1 shaft (542 m) 2 and No.2 shaft (978 m), both no longer opera- tional shafts. Air is upcasted through No.3 ventilation shaft which is 4.9 m diameter and concrete lined, from the No.28 level (1140 m) to the surface. On the surface level of this shaft is a horizontally mounted Richardson 4800 mm diameter single stage axial flow fan with adjustable pitch rotor blades.

Jan 1, 1977

The Olympic Dam deposit is located some 600 km north of Adelaide in South Australia. It was discovered in 1975 by Western Mining Corporation and in 1979 a joint venture was formed with British Petroleum for the evaluation and development of the project. Studies were completed and construction started in 1986 with the plant being commissioned progressively between April and August of 1988. In 1993 Western Mining acquired BP's interest and are now owners of the whole deposit. The scale of the initial development was 1.5 Mtpa of ore for the production of 45 000 tpa of copper cathode, 900 tpa of uranium oxide and some gold and silver. Two expansion programs have occurred in 1992 and 1995 and current performance is at the rate of 3 Mtpa of ore for the production of 84 000 tpa of copper cathode, 1500 tpa of uranium oxide, 24 000 oz per year of confined gold and 380 000 oz per year of confined silver (Table 1). An aerial view of the plant is shown in Figure 1. The benefit of diversifying into the production of more than one product is undoubted and the flexibility of being able to produce variable quantities of copper and uranium also allows advantage to be taken of a change in market conditions.

Jan 1, 1996

By Fairhurst RM

High pressure abrasive water jets have been shown capable of cutting a wide range of materials including steel, stone, rock and concrete. Acceptable performance can be achieved using relatively low pressures and expendable abrasives. The cutting head can be made small and abrasive feed systems have been developed that allow reliable pumping of slurries over long distances to supply such cutting heads. These features make abrasive water jets ideally suited to automated control in remote areas.Another major advantage of abrasive entraining water jet cutting heads is that they may be operated safely in potentially explosive environments due to their cold cutting ability. Therefore there are many possible applications for such equipment in mining.This paper gives an introduction to the abrasive water jet process and includes results of trials carried out at BHRA on a range of hard materials. Work is also described which investigated the operational safety of abrasive water jets in explosive environ-ments. In a special environmental chamber, cuts were made on steel and sandstone with atmospheres of methane/air and hydrogen/air, without caypsing ignition.

Jan 1, 1985

Pyrite is a significant gangue sulphide mineral in the Ok Tedi copper ore. Its presence in the flotation concentrate is not entirely desirable since it lowers the grade of the final copper concentrate. Lime depression of the pyrite has been practiced with some success. However, it has been observed that at the pH for pyrite depression a significant amount of the pyrite particles still float. To obtain further insight into the problem this work has been conducted to determine the composition, natural floatability and xanthate flotation behaviour of the various types of pyrite in the ore. The flotation results show that while some types of pyrite float well at high pH values, others are readily depressed. The implications of these results for Ok Tedi flotation plant have been Considered.

Jan 1, 1997

By C M. Hill

This paper aims to provide a brief overview of the Australian Coal Bed Methane (CBM) industry and more importantly the challenges to sustainable management of the industryÆs by-product, groundwater. In a country where water is scarce and having gone through one of the worst recorded droughts it is vital that this important industry be seen to be managing water in a responsible manner with the greatest environmental and social benefit. Benefits of the water from CBM wells can be enhanced through treatment to produce potable water for domestic or stock purposes, water for irrigation or aquaculture or lower quality or untreated water for industrial or mining purposes. Other options are re-injection of raw water or waste from the treatment processes or discharge to surface waterways. The critical change and difference between CBM projects and traditional oil and gas operations should be that where possible water is no longer disposed of via evaporation ponds with the dual legacy of waste of the water resource and an environmental contamination problem with the remaining salt and brine product.

Jan 1, 2003