Search Documents

By G Davies, D Dunn, C Mawdesley, O Bertoli

The coal industry in Australia has been actively working in recent years towards the (re)integration of geostatistical techniques to the process of coal resource estimation. The benefits of using geostatistical techniques, over the current interpolation algorithms in use in coal modelling packages used to generate the grid estimates, need to be illustrated for the methodology to gain a broader acceptance in the coal industry. This paper focuses on the benefits gained at BHP Billiton Mitsubishi AllianceÆs Saraji mine for the estimation of the total product yield value at a 9.7 per cent product ash cut-off of a particular seam of the Saraji deposit. In order to perform this comparison, the results of the alternative estimation methodologies need to be benchmarked, which in most situations is achieved through the reconciliation of the estimates against production and/or process plant reconciliation data. Unfortunately, this benchmarking was not possible as no reconciliation data for the area of interest in the chosen seam was available, as it has not been mined at the time of the study. Where no reconciliation data is available, an alternative method is to use conditional simulations as the benchmark for comparison. The simulated values can be regarded as ærealityÆ, and the alternative estimation methodologies, based on a sampling of the underlying ærealityÆ, can then be compared using the simulated ærealityÆ as the benchmark for comparison.

Jan 1, 2009

By Mayer TE

The Granites Goldfield is located 550 km northwest of Alice Springs. Mineralisation was discovered in 1900 and intermittently worked along nine km of strike until the early 1950's, yielding a recorded production of 470 kg of gold. The geological environ- ment, pre-existing exploration drilling results, and an optimistic view on gold, prompted acquisition of the property by North Flinders Mines Limited in 1975. An agreement was signed with the Central Land Council in August 1983 and drilling commenced in the same month. In the past, gold was won from alluvial deposits, rich quartz veins and lower grade, disseminated stratabound mineralisation. The last is contained within a distinctive unit in the Mt. Charles Beds, of the Early Proterozoic Tanami Complex. This informally named "Host Unit" is a metamorphosed, chemical- pelitic sediment. The schist contains variable proportions of amphibole, quartz, garnet, clinopyroxene, carbonate and sulphide, inter- calated with recrystallised chert beds. Free gold occurs in several mineralised horizons within the Host Unit, generally conformably distributed within lithologic bands or at lithologic contacts. The Host Unit occurs within a sequence of metamorphosed pelitic sediments and intermediate volcanics. Although mostly confined to the Host Unit, stratabound gold mineralisation also exists in both Footwall and Hanging Wall Schists, usually within zones displaying certain Host Unit characteristics. The deposits may be loosely categorised as being of banded iron formation (bif) type, although some important differences are noted between them and classical bif type orebodies.

Jan 1, 1984

THE Great Cobar Company Limited owns 1100 acres of freehold, which include the Great Cobar Oopper Mine and smelters, the Cobar Gold Mine, the Cobar-Ohesney Copper Mine, and the Great Peak Gold Mines.ORE OCCURRENCEThe ore-bodies in the first three mines-namely, Great Cobar Copper Mine, Cobar Gold Mine, and Cobar-Ohesney Oopper Mine are, speaking generally, lenticular deposits of evidently more or less complete metasomatic replacements of the country rock along a line of powerful faulting. These lenses vary from 150 ft. to 400 ft. in length, and from 20 ft. to 100 ft. in width.

Jan 1, 1919

By Dharmappa HB, Sivakumar M

This paper is concerned with two case histories of wastewater quality management in underground coal mines in the Illawarra region. The first investigation briefly presents an analysis of mine water discharge having an extremely high concentration of suspended solids and consistently high barium concentrations, averaging, 14.4 mg/I Barium, over the sampling period. A laboratory study of chemical precipitation processes has indicated that about 91% of barium could be removed by using ferric sulphate and lime. On the basis of the information obtained from the environmental audit process an alternative water treatment and reuse system incorporating 51% reduction in the water consumption with 32% less off-site discharge has been suggested (Thomas, 1995).The second case history is concerned with the storm water management at a mine situated in the Illawarra escarpment where only 20% of the wastewater generated in the colliery is discharged off-site. Computer modelling of the storm water system showed that 75% of the clean runoff becomes contaminated through poor management practices and causes the process wastewater treatment system to fail in wet weather. Suggested improvements include relatively simple alteration to the coal wash filtration dams which are expected to reduce the periods of inefficient operation of these dams by 95%. The use of storm water diversion channels and detention basins can reduce the overflow volumes by 70 - 100 % for a ten year ARI (Average Recurrence Interval) storm event (Wingrove 1996).

Jan 1, 1998

Downhole survey uncertainties observed at various De Beers operations prompted an investigation into their possible effect on deposit shape and volume. An accurately surveyed artificial æboreholeÆ was constructed and different downhole survey instruments tested. In this way an empirically determined error range of 0.1 per cent to ten per cent was derived for downhole survey data. These survey errors were applied to an orebody model at an existing mine. Visualising the sphere of uncertainty associated with a borehole trace using a general mining package (GMP) gives an indication of possible volume variance. The resulting orebody maximum and minimum volume scenarios for three different depths (200 m, 500 m and 800 m) are presented. For certain instruments and borehole angles, the 3D positional error can be as high as 100 m at 1000 m down the hole. At depths below 200 m the resulting volume deviations can become significant for borehole survey errors exceeding 0.35 per cent. At 800 m depth the volume difference can approach 25 per cent. These figures assume that the error is compounded. The impact of these downhole survey errors is greatest for pipe-like orebodies such as porphyries and kimberlite pipes. Subhorizontal sill-like orebodies (and coal seams) will not be significantly affected by these errors. The impact of this type of survey error needs to be stated (and quantified) and is significant in JORC classification.

Jan 1, 2009

By Morley C

The Mount Charlotte gold mine is located 0.75 km east of the General Post Office in Hannan Street, Kalgoorlie WA and about 3.5 km north of the Fimiston Operations on the famous Golden Mile.Mechanised underground bulk-mining at Mount Charlotte has been in continuous operation since 1963. For the 30-year period ending December 1992, the mine produced 22 million tonnes (Mt) of ore for a recovery of 2.73 million ounces. During 1991/92, the mine produced 1.53 Mt of ore at a head grade of 3.15 gramshonne (g/t) for a recovery of 135 822 ounces.The principal ore source at Mount Charlotte has been the Charlotte Orebody which is now largely mined out. Since 1990, approximately 75 per cent of production has been sourced from the Reward Orebodies. The Charlotte Orebody was a relatively homogeneous quartz stockwork with simple geometry and average bulked grades in the range of 4.0 to 5.5 g/t. This is in contrast to the Reward Orebodies and the more recently defined Charlotte Deeps and Maritana Stockworks, which have complex grade distribution and geometry with lower average bulked grades (2 to 4 g/t). The lower grades are principally due to the decreased density and volume of stockwork venation and related vein halo alteration. Typically, these stockworks comprise a patchy mosaic of quartz veins and vein swarms, with irregular distribution and geometry within the quartz gabbro host rock.

Jan 1, 1993

DESCRIPTION OF OREThe ore consists, in general, of a very finely grained mixture of sphalerite, galena, and pyrite, with a gangue of quartz and schistose material, and contains about one ounce of silver to the unit of lead.Minor minerals are chalcopyrite, tetrahedrite, and ruby silver. The amount of gangue within the ore-bodies themselves is usually less than 20% of the weight of the whole. The ore is banded in a way that corresponds to the structure of the original schists, and is by no means uniform in composition-at one point, for example, blende may predominate, and a few feet farther on the body may become highly pyritic.Owing to the intimate association of the mineral constituents of the ore, it is very difficult to separate them from one another.Although this remark applies to ore from all parts of the field, the difficulty is particularly noticeable with Rosebery ore, the minerals of which are more intimately mixed, and are of smaller grain size than are the minerals of the Hercules ore.To effect a reasonably clean separation, it is necessary to grind the ore so that 90% passes a 200-mesh I.M.M. screen. Microscopic examination of the crushed product shows that 85% of the minus 200-mesh material is less than 30 microns in diameter, or, in terms of screen sizing, is minus 400 mesh. Particles under 30 microns are found to consist, of one mineral only, but in particles over this size separation has not always been effected. For instance, it is known that part of the galena and of the pyrite in the zinc concentrate is associated with sphalerite, and that part of the galena in the mill residue is associated with pyrite. There is only slight association between the minerals in the lead concentrate.

Jan 1, 1927

By D Bush, F Goddard

The electrification of Australian mine sites will see a boom in the use of batteries of all chemistries. Lead acid batteries, a traditional mainstay of the mining industry, are expected to nearly double by 2030, however their use will be eclipsed by the explosive growth in lithium batteries. By 2030 the lithium battery market is forecast to be nearly four times the size of the lead acid battery market. Unfortunately, this will result in a corresponding avalanche of waste batteries to be disposed of. Barely a day goes by without battery generated fires being reported in the media and they have become an increasing nightmare for waste management companies and waste facilities. The safe recycling of batteries will also become increasingly important for mine sites to achieve their sustainability goals and reduce their environmental footprint. What are the risks posed by waste batteries, what are the regulatory requirements and how can you manage or eliminate these risks? What current practises does your mine site currently have for the safe management and disposal of batteries from your site? How prepared are you for the coming avalanche of waste batteries?

Apr 16, 2024

The 1981 Review: In the late 1970s there was an upsurge of interest in the prospecting and mining of this countryÆs mineral resources. That upsurge of interest was accompanied by a mounting public concern over the damage mining operations might do to the environment. Concern was also expressed about what some people perceived as inadequacies in the legislation which regulates mining and the grant of mining privileges, and inconsistencies in the relationship of that legislation to other legislation regulating land use and the use of resources.

Jan 1, 1984

By Y Mita, T Iwama, R Inoue, S Ueda

In the iron and steel manufacturing industries, efforts are being made to achieve carbon neutrality by 2050, and the transition from a coal-based steelmaking process to that utilising renewable energy is being pursued. An alternative process in which directly hydrogen-reduced iron is melted in an electric furnace is being investigated. It is known that foaming slag reduces heat loss from the steel bath in electric arc furnace, but iron loss due to the suspension of steel particles in the slag is indispensable. To improve the separation of steel particles from the slag, the control of the slag viscosity is important. Although the slag viscosity has been extensively studied, in those studies the slag was considered to be a simple liquid. However, in actual operations, slag is a multiphase fluid consisting of solid, gas and liquid phases. Therefore, in this study, by measuring the sedimentation velocity of titanium, stainless steel and glass spheres in an aqueous glycerin solution containing bubbles generated by the reaction between NaHCO3 and C2H2O4, the apparent viscosity of the gas-liquid fluid was evaluated based on Stoke’s law. It was found that the apparent viscosity of the gas-liquid fluid is larger than the viscosity of liquid phase and depends on both the bubble volume ratio in solution and the density of the falling solid sphere, and the apparent viscosity was different from that previously obtained by the rotation method. The apparent viscosity derived from the sedimentation velocity of solid spheres changed depending on the specific gravity of the ball. This is because the apparent viscosity is derived from the velocity of a ball falling in a static bubble in this method, whereas that is derived from the force applied by a stationary flow in the rotational method.

Aug 21, 2024

In simple terms, heap leaching means the removal in solution of valuable elements from a heap of material, and their recovery from that solution. The heap of material can consist of essentially unprocessed ore, sub-ore, low grade gangue and country rock, tailings from other upgrading processes, or artificial materials such as slags or furnace and flue products. The solvents can be solutions of acids (commonly sulphuric acid because of cost) or of other chemicals such as cyanides. Because of cost factors the solutions are aqueous; because of this, leaching operations may be curtailed in cold-climate areas. The guiding principle must surely be `large volume / low cost'. Since solutions are generally easier to manage than gases, there is a strong incentive for replacing roasting of materials by leaching, eg arsenical gold ores. Where sulphides are present in the material to be leached, these may provide the necessary acid, with or without the aid of bacteria, to dissolve and extract the recoverable metals. The mineralogical aspects of the operation relate to the nature of the `ore' and gangue minerals present in the heap, their textural relationships, and their effect on the process itself.

Jan 1, 1994

Computer programs for the storage, retrieval and use of basic thermodynamic and physical property data for chemical substances are described. Methods are presented for the collection, critical assessment and pre- processing of source data for files containing enthalpy, entropy and heat capacity data for 3000 compounds, enthalpy and excess entropy for 200 dilute solutions and critical propert- ies and vapour pressure for 600 compounds. Retrieval programs are discussed which allow the tabulation or plotting of many basic and derived thermodynamic properties for chemical substances or balanced reactions. Examples are given of the use of such data to infer the stability or corrosion resistance of materials and the feasibility, yield and heat release of reactions. A general purpose calculation program is discussed which allows the equilibrium compos- ition to be found for complex systems with many species and phases, using the method of Gibbs energy minimization. Methods of correction for non-ideal behaviour in these systems are discussed, as well as methods for fixing, maximizing or minimizing any desired property of the system. Examples are given of the simulation of various laboratory Experiments and industrial processes by this method.

Jan 1, 1977

In this paper is given a general description of the Black Star copper orebody, its relation to the lead orebodies and the controlling factors in the mineralisation.Copper ore, in the form of chalcopyrite, was first noted at Mount Isa in 1930 during the surface drilling campaign to prove the downward continuation of the silver-Iead-zinc orebodies.Details of the occurrence are set out in table 1.Other sub-commercial widths were also disclosed and examination of these occurrences showed that commercial mineralisation could not be expected within 800 ft. of the surface. It was therefore decided that further exploration was not warranted until underground workings had advanced to this horizon.Detailed surface mapping showed two small outcrops of the host rock of the copper orebody. One occurrence, 50 ft. x 75 ft., was of quartz, with leaching suggesting former dolomite. Another outcrop, further north and west of silicified shale, with low grade oxidised copper, has recently been found. Both occurrences were above the hangingwall of the main copper orebody.When the workings in the silver-Iead-zinc orebody reached No. 7 level (875 ft. below the surface) further...

Jan 1, 1953

By J E. Eberhardt

Ore sorting has long been used to raise the efficiency and thus lower the environmental impact of mineral processing operations. It was first instituted as hand sorting, according to a humanly perceived difference in the ore, but is now automated using large mechanical sorters in order to meet the high tonnage throughput required in most minerals processing applications. In the past, ore sorting was generally used as a niche processing route when other approaches failed, and in this context, consequential environmental benefits are often not the first consideration in adopting sorting. When applicable, ore sorting offers environmental benefits in reductions in fines waste, reagent usage and energy consumption in milling. Although there are significant opportunities for the use of ore sorting technology in many minerals processing operations, industry applications, to date, have been limited mainly to the processing of diamonds, magnesite, talc and uranium ores. This limitation has principally been due to a lack of suitable sensing technologies for a wide range of ore types. The authors report on a wide-ranging review of the automated sorting of mineral ores, and in particular, on methods for discrimination of ore characteristics prior to mechanical sorting.

Jan 1, 2002

The Mineral Resources Act 1989 was assented to on 25th October, 1989 after more than two years of consultation and negotiation between Government, the mining industry and other affected parties particularly the major rural organisations.The legislation proposes major conceptual changes in a number of areas and adopts a totally new approach to the definition of land and the mechanisms available to the mining industry for accessing such land.Unfortunately the passage of the legislation through Parliament coincided with the lead-up to the State election. Ultimately it became an election issue generating much adverse comment in the media particularly from rural and landholder groups. It was obvious that much of this anti-mining propaganda resulted from a lack of understanding of the legislation and the benefits that flow to the majority of landholders as well as the mining industry.It is essential that the contents of the Mineral Resources Act be thoroughly understood by all parties. Only then will all the State's resources be able to be developed in a multiple land use environment.This paper outlines the philosophy behind the new Act and the more important provisions contained therein.

Jan 1, 1990

By Kane, M O&apos

The mineralised members of the Brockman Iron Formation mined at Mt Whaleback are overlain and underlain by shale horizons. To maximise resource recovery, waste movement within the life of mine plan will total approximately 3.3 billion tonnes. Approximately 15 per cent of waste materials contain zones with varying amounts of sulfides and carbon and are referred to as æreactive shaleÆ. Reactive shale has the potential to self-heat and can react with some explosives, resulting in spontaneous explosion. Sulfide rich zones also have the potential to generate acid rock drainage (ARD). Successful mining of reactive shale requires constant co-ordination between the geology, mine planning, mining and environment departments. Safe storage of reactive shale is the focus of ongoing research. Since the mid-1990s, a number of trials have been undertaken at Mt Whaleback in order to further the understanding of the physical and chemical properties of reactive shale. This paper summarises some of these trials, and discusses key learnings arising from interpretation of results. Ultimately, the learnings from this research will provide the guidelines for successful storage of reactive shale.

Jan 1, 2003

By Kuruppu M

Geotechnical design plays a key role in mine design. A proper geotechnical design provides a safe working environment and facilitates efficient mining operation. There are mainly three design approaches: (i) judgmental, based on observational and experiential facts, (ii) empirical, based on empirical design formulae; and (iii) analytical, incorporating numerical analysis. Most design applications are based on the design methods one and two as mentioned earlier. However, complexities arise in deep underground mining operations and deep open pit mines. These complexities and difficult geological environment introduce more uncertainties and simple empirical formulae would not be adequate as a design tool. These situations require numerical modelling and analysis of the design problems including interpretation of the results obtained from the analysis. There are several tools available for performing the numerical modelling and analysis. A brief review of the available tools is provided. The authors selected ANSYS (a general purpose finite element analysis tool) for use in mining geomechanics and geotechnical design. This paper includes several examples demonstrating the applicability of this software in designing mining structures. The authors hope that the design examples will demonstrate the use of the numerical modelling and analysis applications in excavation design.

Jan 1, 1995

Gold mineralization like other low concentration high value commodities has gained the notoriety of being difficult to sample. This adversely affects the confidence that can be placed in resource estimates and ore reserves. As an example, it is not uncommon to find differences of the order of 30% between duplicates of a single sample sent to two different commercial laborartories. Two halves of drill core generally show marked differences in grade. Again differences of 50% are not uncommon in halved core. In the context of this type of "error" within the base data used for the resource estimate, many of the subtleties of computation methods and expert judgement of resource categories, are almost a case of shutting the gate after the horse has bolted. Managers, financiers and consultants must question the quality of the base data upon which resource estimates are made. They must insist that standard and duplicate samples are used to measure the accuracy and precision of commercial analytical laboratories, that sampling practices have been checked for possible bias and give tolerable repeatability. Further they must ensure there can be a realistic confidence in the estimates by correctly using these measures of data quality to quantify risk.

Jan 1, 1990

Syferfontein Colliery, part of the Sasol group of companies which specialises in the field of petro-chemical production, was established in 1990. The mine is situated about 150 km east of Johannesburg, South Africa. Two coal seams are mined, utilising two 75 m3 draglines, shovels and a fleet of 177 ton rear dump trucks. The mine will reach its full production capacity of seven million tonnes per annum in 1992. During the planning period, prior to the establishment of the mine, management were confronted with the unstable socio-political environment in South Africa which could jeopardise the eventual success of the mine. They consequently conducted a strategic planning exercise to determine guidelines for mine planning to improve the chances of success in this unstable third world environment.The strategic guidelines formed the basis for specific actions taken during the planning and commissioning of the mine. Specific actions were taken in the field of operating cost, labour relations, working environment, logistics and the general environment. First results indicate that these actions have played a major role in the success of the mine to-date. This process can be utilised by others facing similar or even totally different uncertainties.

Jan 1, 1992

Rajor intrusion-related Cu and Au dep- osits along the Cordilleran-type central Andean margin and in the western Pacific island arcs constitute a series of discrete, linear belts which correspond to limited (414 m.y.) metall- ogenic epochs. The most important metallogenic belts, all of Cenozoic age, are inferred to have been generated during relatively shallow subduction of oceanic lithosphere beneath con- vergent margins. Geological and isotopic evid- ence suggests that magmatic rocks and associated Cu and Au mineralization were derived from asthenospheric mantle sources, which were enriched in a variety of elements (metals, alkalis, S) by dehydration of subducting oceanic crust. Where exceptionally rapid, low-angle 3ubduction took place beneath very thick (>50 km) continental crust, as in the central Andean Altiplano in the Miocene and southwestern North America during the Laramide, ore-related magmas underwent wholesale crustal contamination. However, the associated Cu-Au mineralization is the same as that developed in primitive island- arc crust. In particular, the by-product Au and So contents of porphyry Cu deposits are inde- pendent of crustal thickness and the degree of crustal contamination as determined isotopic- Ally.

Jan 1, 1987