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The resistance of lead to chemical attack and the ease of its fabrication has made it one of the most useful of the metals available to the chemical engineer and the electrometallurgist. It has proved to be of particular value in the manufacture of sulphuric acid, and since the conversion of the sulphur of pyritic ores into sulphuric acid is becoming the duty of the metallurgist, the corrosion resistance of this metal will be a matter of considerable interest to him from the standpoints of both producer and user. He realises that there is little to be gained in carrying the process of purification past the ordinary economic limit if little or nothing is to be added to its corrosion resistance, and he as user would not be willing to pay a premium for such purification if it can be shown that its reputed value has no scientific foundation.The metallurgist is well acquainted with the trouble and expense of meeting demands which have nothing torecommend them but prejudice and fancy. The valuable anti-corrosive properties of lead are very commonly ascribed to its forming insoluble compounds with the acids sulphuric, hydrochloric, carbonic, etc. If we trusted superficial visual evidence alone, such a view would receive strong support, but in the light of what we know of the mechanism of corrosion we must attribute its resistance to other factors much less obvious to casual inspection. Certainly there may be some mechanical obstruction set up to diffusion of the liquids towards the surface of the metal.

Jan 1, 1932

By C McInnes

The key to successful flotation plant design, production planning and mine/mill optimisation is a solid understanding of the resource to be processed. As advocated by the authors of this paper, the main components of geometallurgical modelling of an orebody and its associated flotation plant are: an ore sampling program and subsequent laboratory testing of these samples in order to extract process model parameters; geostatistical distribution throughout the resource model of the process parameters; calibration of the plant via benchmarking (for existing operations); and plant simulation using a system of process models and the distributed metallurgical parameters (from step two) as the data set.It is important that the grinding and flotation models are linked. For example, a laboratory test conducted on a drill core sample, intended to represent a portion of the orebody, is conducted at a specific grind (represented by a P80). However, when that ore is actually processed through the plant it may well be (and in many cases most likely will be) at another P80. Additionally, the flotation plant residence time will often be determined solely by the grinding circuit capacity and feed slurry density. In the case of SAG mill û ball mill circuits, the fluctuations in tonnage and grind are known to be high. The modelling approach described in this paper allows for changes in the measured flotation kinetic parameters in order to reflect the expected grind as determined by the comminution process.

Jan 1, 2005

The accuracy with which block values are known can have a fundamental effect on the success of an operation.From a geostatistical study the variance of the error in extending sample values to block values can be determined and the engineer must ensure that this is sufficiently small by adjusting the size of blocks or moreintensive sampling. A study is given for a deposit showing a high degree of anisotropy and it is shown that the shape of the block is not important in determining the estimates.

Jan 1, 1976

A significant resource of uranium has been discovered within a buried palaeochannel located in the south western corner of the Officer Basin of Western Australia by PNC Exploration (Australia) Pty. Ltd. The mineral- isation is redox controlled and is hosted by Eocene organic rich paludal sediments. Prob- able insitu reserves are 13,000 t of contained uranium with an average ore grade of 0.12% at a cutoff grade of 0.03% U. The Mulga Rock palaeochannel has been traced for at least 100 km beneath the Quaternary surficial cover. The main channel is horseshoe shaped with the channel arms vary- ing from 5 to 15 km in width. The western arm connects to the Lake Raeside-Ponton Creek drainage system, whilst the eastern arm'is open to the south. The headwaters of the palaeo- channel are thought to have been the Lake Minigwal drainage system, prior to its capture by the Lake Rason system. Differential.erosion of the basement rocks during the Late Cretac- eous to Early Tertiary strongly influenced channel shape and resulted in the main channel being confined to a Permian,mudstone filled valley. Upwards of 100 m of fluviatile sediments accumulated within the palaeovalley during a period of subsidence in the Early Tertiary. Three broad stratigraphic units have been re- cognised within the channel: 1. An upper unit of fluviatile sands with interbedded lacustrine sediments, which have subsequently been wholly oxidised and variably silicified and ferruginised. 2. A middle unit of lacustrine to paludal sediments, which host the main mineral- isation. 3. A basal unit of fluviatile gravels and sand. The presence of excellently preserved Nothofagidites in organic rich paludal sediments from the middle unit, suggest that unit was laid down in a non-marine, fluviatile, humid environ- ment during the Middle Eocene.

Jan 1, 1988

By J J. Cilliers, E Ventura-Medina

Mineral froth flotation is used to separate particles of valuable mineral from its associated gangue. It involves the selective separation of the hydrophobic particles from the slurry into the froth. As air is blown into the slurry, the hydrophobic particles attach to the air bubbles, while the waste particles remain in suspension. While the froth rises up, bubbles start to coalesce and burst, allowing the entrained liquid surrounding the bubbles to drain and return part of the gangue to the pulp. Mineral separation is therefore a function of the amount of valuable material loaded on the bubble shells, as well as the amount of gangue material entrained in the liquid channels separating the bubbles (Plateau borders). As a result, the separation performance of the process is affected by mineral attachment and drainage or bursting in the froth. This study aims to establish the relationship between solids loading, froth stability and separation performance. For this purpose, a series of industrial experiments were carried out to measure mineral attachment as well as bubble bursting by combining direct sampling of the bubble films and video image analysis of the froth surface. This work suggests that the solids loading on bubbles strongly affects the separation performance. The results generally showed that solids loading and concentrate grade are closely related, while froth bursting rate can be linked to the drainage of gangue from the Plateau borders and also to the overall recovery of valuable mineral. It was shown in particular that higher loadings, usually associated with higher froth bursting rates, are indicative of more selectivity in attachment and therefore a higher mineral grade in the concentrate. Additionally, this work suggests that bubble solids loading and froth stability are essential parameters to include in froth flotation models as they allow control and optimisation of the flotation performance.

Jan 1, 2005

By Finlayson J. F

The advantages of rapid and accurate analyses are becoming appreciated in many industries today and have resulted in a great increase in the number of samples received by their laboratories. This has caused some firms to consider the installation of one or more of the instruments available for analytical chemistry. In this country there are relatively few people with experience of instrumental methods and it is difficult for a firm considering the installation of such equipment to assess the advantages which instruments may give them, and to decide which instruments, if any, will be of most use to them. The object of this paper is to give a brief survey of instrumental methods in the field of inorganic analysis. Instrumental methods of analysis have numerous advantages when used correctly. They enable extremely rapid analyses to be made in many cases, e.g., analysis of refined lead by purely chemical means takes about two days whereas spectographically the analysis can be completed in approximately one and a half hours. The accuracy ofinstrumental methods, generally between 1 and 5%, is higher than most chemical methods for small percentages of impurities. Furthermore, if the instrument can be calibrated against absolute standards the errors are usually random and not biased to one side of the correct result. The sensitivity is high, enabling in many cases the detection and determination of smaller percentages than can be detected chemically. This high sensitivity enables and, in some cases, requires the use of very small samples, and results in considerable savings in reagents, allowing the analysis of considerably more samples without undue loss...

Jan 1, 1951

By G D. Price

The Golden Blocks Goldfield is located in the Slaty Creek area,North West Nelson, about 20 km west of Collingwood. Alluvial gold was discovered in Slaty Creek in 1861. Gold was mined from quartz veins up to 1.5 m thick at nine mines from the 1890s until the closure of the Aorangi Mine in 1911. Total production from the Golden Blocks Goldfield is estimated at 46 000 ounces of gold. The Aorangi Mine was the largest mine, with a recorded production of 27 978 ounces of gold at an average grade of 36 g/t. Quartz veins containing gold and sparse sulphide mineralisation occur in a slightly metamorphosed, complexly deformed over-turned sequence of Lower Ordovician sandstones and shales. Primary gold mineralisation is associated with intensely deformed zones that occur near or at carbonaceous shale and sandstone contacts. Some eighty-five percent of all gold production (39 000 ounces) came from four mines confined to the stratigraphically lowest, most widespread shale unit. The quartz veins exhibit textures consistent with a hydraulic fracturing mode of vein formation with fissure infill vein types predominating over replacement textures. Stylolites of carbonaceous material and recrystallization features within the veins suggest multiple phases of deformation. The lack of wall rock alteration, and low primary fluid inclusion temperatures of 200¦ - 265¦ indicate that the ore fluids were associated with a low temperature epithermal system. A model consistent with similar mineralisation styles observed in Ordovician sediments from Pacific Rim occurrences is presented. The high grades (up to 100 g/t) mined from the upper levels of several mines suggests supergene enrichment processes associated with the Upper Cretaceous weathering surface. The Golden Blocks Goldfield has had no modern exploration. The most recent exploration was undertaken in the early 1980s. There are known acid intrusives in the area, with potential for the application of new models of intrusive-related gold mineralisation.

Jan 1, 2004

By R Berthelsen

The Peak Gold Mines Pty Ltd (PGM) operations are located approximately 9 km south of Cobar, NSW. PGM currently mines and treats ore from three separate orebodies within 5 km of the original plant. Production from the original Peak orebody ceased in April 2002, with ore currently sourced from underground at New Occidental and Perseverance, while New Cobar supplies ore from an open cut mine. In March 2003, Wheaton Minerals Asia Pacific purchased the operation from Rio Tinto who operated the mine for around ten years. The Perseverance deposit is situated between 600 and 1000 m south of the Peak orebody. Access is via shaft from Peak to 630 m below surface and then by decline to the northern end of the deposit locally known as Zone A. Development of the resource commenced mid 2002 to set up for a long hole open stoping operation at 25 m level spacing. The first production stope was successfully brought on line December 2003. The Perseverance deposit is hosted by sediments and volcanics along the eastern margin of the Devonian Cobar basin and is one of many deposits with the Cobar Gold Field. The Cobar Gold Field has produced approximately 2.5 million ounces of gold since 1880. The Perseverance area had long been considered prospective due to the presence of old workings at the southern extensions of Peak line of lode. Significant mineralisation was first discovered at Perseverance in 1994 when PGM drilled a hole targeted 950 m below the historic workings. The target was based on an apparent plunge to the stratigraphic controls to the Peak Orebody. Subsequent exploration within and around the ægreaterÆ Perseverance area has been significantly aided through the use of downhole electro-magnetic surveys due to the close spatial association between gold and sulfide mineralisation.

Jan 1, 2004

By J Garritsen, P F. Wells, M Xu

IncoÆs Clarabelle mill currently processes ores from eight mines in the Sudbury basin area in Ontario, Canada. The ore from the Garson mine contains a much higher concentration of arsenic than the other ores. Adding this ore into the feed to the mill has resulted in an increase in arsenic content of the Cu-Ni bulk concentrate to a level that significantly affects the smelter operation, and more importantly the efficiency of Cu-Ni separation in the Matte separation plant. The arsenic occurs mainly as gersdorffite (NiAsS), with a small amount being in the form of cobaltite (CoAsS). Extensive laboratory tests on depressing arsenic in Garson ore flotation have been conducted and two reagent suites have been identified as effective arsenic depressants. One is the so called MAA depressant which is a mixture of magnesium chloride, ammonium chloride, and ammonium hydroxide. This reagent combination was reported to depress other arsenide minerals such as arsenopyrite (FeAsS) and enargite (Cu3AsS4). However, in this study for the first time it has been shown to have a depressing effect on gersdorffite. The other reagent suite, a mixture of triethylenetetramine (TETA) and sodium sulfite, that has been reported as an effective pyrrhotite (Fe1-xS) depressant in pentlandite ((NiFe)9S8) flotation, has not been reported as gersdorffite depressant before. The effectiveness of both reagent suites is more pronounced when the arsenic minerals are oxidised through pulp aeration or the addition of hydrogen peroxide. With a flow sheet consisting of a magnetic separation, rougher- scavenger flotation, followed by regrinding and cleaning of combined magnetic and scavenger concentrate, the arsenic recovery to the final Cu-Ni bulk concentrate was reduced from 73 per cent in baseline test to less than 30 per cent with either reagent suite at no decrease in nickel recovery. The TETA/sulfite reagent combination has the advantage over the MAA suite in that pyrrhotite is also depressed, rather than being activated, and the copper and nickel concentrate grades are therefore increased.

Jan 1, 2005

HAPPENING to be in Cue recently the writer was unexpectedly called upon to make surveys of some diamond drill bores on the Big Bell mine on the Murchison goldfield. The owner of the mine Mr Herman Mandelstam. had brought such apparatus with himas he could lay his hands on. and no other was available without prohibitive delay.The usual method of making these surveys as is well known is by putting a glass tube half filled with gelatine or glue in a melted state down the hole with a small magnet freely suspended in the glue and having it there till the glue sets solid. When this tubeis withdrawn (its depth down the bore being noted) the bearing and inclination of the borehole at this particular point can be read - the bearing by the compass and the inclination by the angle between the tube and the surface of the glue which of course ishorizontal. By taking a number of these observations according to the degree of accuracy required the course of the bore can be fairly accurately plotted.In dealing with dry holes there is little trouble but when the holes are full of water great difficulty is experienced. In the case in point the first observation was made in water 300 ft. deep, corresponding to a pressure of 130 lb. per sq. in. The tube containing the gelatine and glue (a mixture was used) was found, when hauled to the surface, to be completely filled with a weak mixture of water, gelatine, and glue and there was no horizontal surface from which to measure the angle of inclination of the bore. The water had been forced through the corks and sealing wax with which the tube had been closed. After several attempts it became obvious that no method available would keep the water from getting into the air-space in the tube, and to a pressure-proof metal container was impossible, nothing remained but to do away with the air-space and this was accomplished by using two liquids of different specific gravity - mercury and melted glue. The tube...

Jan 1, 1930

Case Study: Dragline Swing to Dump Automation By Peter Corke, CSIRO Manufacturing Technology/CRC for Mining Technology and Equipment (CMTE) Peter Corke presented a case study of a project to automate the dragline swing to dump operation. The project is funded by ACARP, BHP Coal, Pacific Coal and the CMTE and is being carried out on a dragline at Pacific Coal's Meandu mine near Brisbane. Corke began by highlighting that the minerals industry makes extensive use of large, mechanised machines. However, unlike other industries, mining has not adopted automation and most machines are controlled by human operators on board the machine itself. Choosing an automation target The dragline automation was chosen because: ò draglines are one of the biggest capital assets in a mine; ò performance between operators vary significantly, so improved capital utilisation is possible; ò the dragline is often the bottleneck in production; ò a large part of the operation cycle is spent swinging from dig to dump; and ò it is technically feasible. There has been a history of drag line automation projects, none with great success.

Jan 1, 1997

Some thirty ore minerals occur in the Mount Morgan orebody. Pyrite is the dominant mineral with chalcopyrite, magnetite and pyrrhotite major components. Gold and gold tellurides, in accessory amounts, are economic- ally important. The prevalence of volcanic rocks in the mine area and the presence of trace amounts of such minerals as cassiterite, gold, native bismuth and rutile suggest a voicanogenetic origin for the ore. The ore occurs in a breccia pipe which cuts through the volcanic and associated strata but the former existence of a syngenetic stratiform ore bed is evidenced by the presence of occasional masses of perfectly banded sulphide ore including a barite-rich "black shale" with sulphide layers exhibiting slump structures. Mineralization is thus both _ syngenetic and epigenetic. The orebody (breccia pipe) is intruded by small stock-like bodies of quartz latite which is believed to have been the upward rising magma invading the orebody of which it is the parent. This has resulted in the annealing recrystallization of the ore minerals and the quartzose gangue with a low strain rate due to magma drag and dilation during intrusion.

Jan 1, 1974

Pulverised coal firing was pioneered in the cement industry prior to the turn of the century. Ash from the coal is absorbed into the mix in the kiln and replaces secondary materials. With high purity limestone coal with high ash content can be used. Fuel cost is a major part of the total manufacturing cost. Cement plants are thus quick to respond to fuel price changes and will use low grade fuels if there is a price advantage. Combustion conditions in a cement kiln differ markedly from a boiler. Flame length is determined by air/fuel mixing but because of fixed secondary air conditions this depends on primary air momentum. Volatile content has some effect on flame length but this can be offset by coal fineness. Much of the heat for cement production is for limestone calcination which is a low grade energy requirement. By allowing long residence time in separate direct fired vessels which then feed the high temperature kiln the energy of materials such as oil shale, tyres and lump lignite can be utilised.

Jan 1, 1987

By R L. Koenig

Previous papers at Metplant conferences have covered the options for crushing and grinding circuit selection. High Pressure Grinding Rolls (HPGR) may have considerable advantages over autogenous milling circuits but test work and evaluating different grinding circuits must be done to establish which circuit provides the best option. The Hawsons low grade magnetite project provides a specific example in using thorough test work, careful simulations and detail in design to allow the evaluation of grinding circuit performance. Fortunately tools are available for this evaluation and the test work for the Hawsons iron ore is detailed in this paper. The results of the test work and simulation indicates that although the Hawsons iron ore is competent in terms of autogenous milling given the medium hardness of the ore in the Drop Tests, the HPGR testing indicates that the use of HPGR is likely to use half the energy requirement. This is a characteristic of the Hawsons iron ore and is likely to be valid for other iron ores in the Braemer Iron Formation which stretches from the Hawsons lease in New South Wales to Razor Back and South Dam in South Australia. The Hawsons magnetite iron ore resource has been known from the early 1960s when CRA explored the area. However, the Pilbara region was discovered in this era and this led to development of high grade direct shipping grade hematite ores. Carpentaria Exploration (Capex) rediscovered the magnetite whilst undertaking multi-commodity exploration in the Broken Hill district during 2009. The magnetite grade was found to be low at around 16% Davis Tube mass recovery (DTR) but despite this, the project provides a positive business case as a result of the following key factors:• The mineralisation is particularly soft for crushing and grinding with a Bond Work Index of 6.3.• The mineralised rock fractures easily preferentially along grain boundaries.• The location is close to mining infrastructure and a skilled workforce in Broken Hill, 60km to the North East.• It is close to road and rail infrastructure for access to the resource.• The only contaminant in concentrate is silica.• The resource contains many billions of tonnes of magnetite mineralisation.The low Bond Work index is a key characteristic of the Hawsons iron ore and the use of autogenous milling and HPGR circuits is compared to other iron ores indicating why the plant energy requirement may be just as important as iron ore grades.

Aug 8, 2011

Hindustan Zinc Limited (HZL) is one of the leading base metal producers in India. It operates a two-smelter Complex at Visakhapatnam, Andhra Pradesh. At this zinc-lead smelter zinc is manufactured by the conventional hydrometallurgical route and lead is produced by Blast furnace technology generating residues or wastes which contain substantial quantities of metal values. Disposal of such wastes is a problem in any non-ferrous industry. Both the stringent environmental regulations and the changing industrial scenario emphasise the need for industrial research to find economically viable and environmentally friendly technologies to recover the metal values from these waste materials. The in-house R&D Centre at Vizag Zinc Smelter (VZS) thinking globally re-engineered its activities and major thrust was given for converting waste to valuable metals and metal compounds. Basic analytical chemistry with the hydrometallurgical concepts has been adopted in developing these innovative technologies. In this paper attempts are made to provide a clear history of the different waste raw material, the process developed for each raw material and their superiority of over other parallel work. Most of the processes described here are pilot plant tested and under patenting. The process flowsheet, results obtained and advantages of each process are presented. This paper provides a consolidated approach through which the varied smelter waste materials can be processed with cost effective and eco-friendly innovative technologies. In-house R&D efforts at VZS with its contribution and achievement in converting æwastes into wealthÆ technologies are presented in this paper on the following the major thrust areas:recovery of zinc from liquid effluent; recovery of zinc from effluent treatment plant (ETP) gypsum sludge; production of highly pure electrolytic zinc metal powder from zinc bearing gypsum residue/sludge generated at the effluent treatment plant; hydrometallurgical recovery of copper as copper sulphate solution which can be used for CuSO4.5H2O, copper cathode/copper metal powder from copper-cadmium cement; recovery of manganese, lead and silver from anode mud generated at Zinc Cell House and 4-metal extraction/recovery of manganese, cobalt, copper and nickel from Indian ocean bed manganese nodules; recovery of zinc, lead, silver and sulphur values from silver concentrate residue generated at the froth flotation process; recovery of silver and lead as lead-silver sponge/lead-silver sulphide concentrate from lead bearing residues; recovery of lead, silver and copper from copper matte; recovery of antimony as antimony metal or lead-antimony master alloy from antimony bearing dross; and recovery of nickel and dimethylglyoxime from Ni-DMG complex.

Jan 1, 2000

By G Solly, P J. Leevers

Day-to-day operating practices at existing operations need provide high quality data for decisions that will impact directly on the potential value of the available resource, in addition to meeting standards of quality expected of data used in feasibility studies that will be completed to obtain additional capital required to finance operational improvements. Drill hole location, down hole survey and assay data standards of accuracy and precision have received considerable attention in recent years. The authors propose that geological descriptions of both cored and non-cored drilling warrant at least equal attention, considering their fundamental role in establishing the framework used for geological modeling and resource estimation. The iron ore deposits of the Middleback Ranges have been a major source of iron ore for almost a century. High-grade hematite-dominant ore is currently mined by OneSteel from three open pit operations supplying ore to the companyÆs integrated steelworks at Whyalla. A review of OneSteelÆs future iron ore resources, commenced in 2002, highlighted the need for more flexible and comprehensive management of all forms of geological data used in resource evaluation. Driving this program was the information needs of feasibility studies of the Iron Magnet deposit, located beneath the existing Iron Duke and Iron Duchess mines. Prior to the beginning of 2003, resource evaluation drilling data collected by OneSteel was managed using an in-house system based on industry standard relational database software. The system was demonstrably effective in ensuring the fundamental integrity of basic drilling data, but lacked necessary capabilities for the acquisition and management of geological descriptions, geotechnical and geophysical data obtained by down-hole logging. OneSteelÆs existing system for the management and interpretation of geological descriptions was restricted to storage of a single three digit code for each lithological description interval. The original logs for a large number of older drill holes could not be located, having been either poorly archived or culled from the database in the belief that they did not contribute to the understanding of the resources currently being mined. The three digit codes represented a combination of lithological and stratigraphic descriptions, including many subtle variations in iron ore colour and texture believed to be associated with variations in geochemistry, but subsequently demonstrated to be either incorrect or inconsistently applied. This resulted in the establishment of a plethora of codes for a relatively small number of distinct lithologies. Improvements implemented by OneSteel geologists addressed these shortcomings by ensuring the new data management system: facilitated the objective description of lithological characteristics; distinguished between obsevations and interpretations (eg lithology versus stratigraphy); promoted consistency between descriptions provided by different geologists; and helped to ensure data integrity by developing an audit trail for alterations made to data subsequent to its acquisition. The data used to develop interpretations of mineralisation distribution and characteristics are fundamental to the effective utilisation of a mineral resource: any mineÆs most important asset. Resource related risk is widely recognised as the principal source of technical risks affecting resource development projects, whether they are new mines or expansions of existing operations. A key lesson from this work is that most commercial or æin-houseÆ developed geological data management systems are able to handle basic data validation tasks effectively. Geologists, however, need to ensure that the data management system is appropriately structured to help promote the acquisition of objective and consistent data for interpretation.

Jan 1, 2003

By P Gy

When it comes to sampling theory, a bad sampler is a bad sampler, no matter what, and a sampler is either bad or good. It also is of critical economic importance to tell and understand the difference, especially in a metallurgical plant. In this paper, the grand principles of Sampling Theory are first recalled, then the most popular types of sample cutters for plants are critically reviewed. It is concluded that the industry has a lot of progress to make in that direction, although improvements usually pay for themselves very quickly.

Jan 1, 2002

Mine planning for ore recovery by open stoping and pillar recovery is becoming more sophisticated, but there are basic operating constraints which must be imposed if this planning is to realise the production results on which the mine is dependant. The production reliability of an open stope is usually a high priority and common design problems can be identified. A range of practical considerations which should be considered at the mine planning stage are reviewed including equipment performance, blasting technology, ventilation requirements, development layouts, lead time, ground conditions, support, backfilling and ore recovery.

Jan 1, 1982

R F Johnston 1 ABSTRACT The possibilities for bacterial leaching of refractory gold ores found in the Central Victorian region of Australia are examined. The behaviour of bacteria, especially 77iobacillus ferroaridans is outlined and the effects of these when they are exposed to pyrite, arsenopyrite and stibnite are examined. The factors which are particular to Central Victoria are outlined and the possibility of adapting a bacterial culture to suit the conditions is discussed. It is concluded that a bacterial leaching system is a feasible proposition and that it could enhance leaching rates and yields.

Jan 1, 1994

The undeniable fact of life in the next 25 years will be the increasing difficulty of the physical conditions of Australian orebodies facing future miners. We are all familiar with names such as the 3000 orebody at Mt Isa, Hilton, Century, Macarthur River, Cannington, and Ernest Henry. These projects represent a significant. proportion of the planned underground mine development in Australia. Moreover, many of these new orebodies are an order of magnitude more difficult to mine and process than their predecessors. Extraction will be from deeper and potentially more hazardous working environments. Occupational health and safety considerations will place unprecedented demands upon mine operators and technology providers of the future.

Jan 1, 1994