Search Documents

By M J. Daniel

Mineral resources all over the world are often heterogeneous and have variable ore properties and ore grade. As a result the ore processed in concentrating plants varies over the life of mines. Consequently the circuits often suffer from bottlenecks typically at the stages of crushing, semi-autogeneous (SAG) and ball milling. Bottlenecks may be remedied with equipment retrofits, however, design engineers should consider a phased approach to the circuit design that delays initial capital expenditure over the life-of-mine. This paper deals with the debottlenecking of existing mineral processing plants by means of high pressure grinding roll (HPGR) applications. It also deals with the use of innovative flow sheet designs using HPGRs for the design of Greenfield plants by engineering or mining companies. In the case of Greenfield plant design an analysis with respect to energy efficiency and operating cost (OPEX) is presented. The analysis compares the performance of SAG based circuits against HPGR circuits that may be influenced by variable ore properties. Globally about 600 HPGRs are installed in various applications in the cement and minerals industries. In excess of 100 of these HPGRs are used since the mid 1980s for crushing and grinding of various ore types including æhard rockÆ applications. HPGR technology is mature enough to be considered as an ideal debottlenecking device. HPGRÆs are versatile, they have a low installation footprint and they are flexible in its machine settings (pressure, roll speed), which can be adjusted to react to ore variations whilst maintaining a high throughput. Examples for the benefits of using HPGR in terms of energy efficiency and operating costs are presented by this paper. æEco-efficientÆ flow sheets and sustainable development initiatives are linked to energy savings as an æenergy costÆ and benefit to the environment. Energy savingsÆ can also be analysed in terms of the ædollar costÆ (OPEX) savings. This paper demonstrates that HPGR is more energy efficient and may reduce the overall grinding energy requirements in the order of 16 per cent depending on the target grind size and ore properties. The HPGR is more cost efficient and may reduce overall grinding costs by as much as 19.3 per cent depending on the cost of energy, grinding media and the rate of grinding media wear in the comminution circuit.

Jan 1, 2009

A study of drilling data at various stages of development of an orebody show that the semi-variogram, used for calculating the accuracy of block estimates can be ill-defined if too few data are available. The consequencesin this case are to have blocks supposedly more accurately known than is possible at the early drilling stage; such a result being potentially dangerous. However, as the amount of data increases the recalculated, semi-variograms approach the underlying semi-variogram of the deposit and the calculations made using them become more reliable and robust.

Jan 1, 1977

THERE are certain facts that the mining industry in Australia is faced with at the present moment which may be accepted as axioms. The industry is at a low ebb, as evidenced by statistics. Metals form the basis of all modern industries, and are necessaryfor the welfare of Australia. Mining is a wasting asset. Every ton of ore extracted is one ton less which c.annot be made good, and it should be our duty to get as much profit froin that ore as possible, otherwise there is a permanent loss to the country.The metal market cannot be controlled by Australia; it is more or less an international matter. Australia has not been thoroughly prospected. There are no mines being developed that are likely to replace those which are being depleted.Our mining engineers are as capable as those in other parts of the world, and have made good where they have been given a chance. There is no one cause for the present depression; there are several, more or less, interwoven. Of course, the war has had an adverse effect, but that has only dislocated things temporarily; it upset our markets, influenced the price of metals, and affected the labour market and cost of stores. Labour troubles made their appearance before the wave of unrest swept over the world. The cause of labour discontent must be investigated, and if possible removed. As each industry has .its·own problems, miners must inquire into their special problems, as there is no sovereign remedy that will suit all cases.It is obvious that we cannot mine ore if we do not know where it is; therefore, the first thing is to discover workable deposits.

Jan 1, 1919

By Misra V. N

Davis tube tests were conducted on a Koolanooka magnetite iron ore sample, supplied by Kingstream Steel Ltd, to determine the optimum grind size, maximum iron recovery and the cleanness of the products from low intensity magnetic separation (LIMS). The ore sample contained 38.6 per cent iron, 37.8 per cent silica, 6.5 per cent magnesia and 0.54 per cent alumina. XRD and microscopic examination showed that the main minerals in the ore were amphibole (42 per cent), magnetite (39 per cent), and quartz (14 per cent). Amphibole, (Mg, Ca, Fe),Si8O22.2(OH), containing 50.3 per cent SiO2, 35 per cent FeO and 11.5 per cent MgO is the main gangue mineral in the ore, and about 30 per cent of the total iron in the ore is contained in the amphibole. Heavy liquid separation tests showed that it is very difficult to separate iron from silica by gravity separation to obtain a high quality iron concentrate. Three grind sizes were initially tested, ie 45, 38 and 20 ¦m. It was found that grinding to 100 per cent -38 ¦m (P80 of 29 ¦m) appeared to be the best option for liberating the magnetite from gangue minerals. The iron recovery to the LIMS magnetic product for the 100 per cent -38 ¦m sample reached 73 per cent and the iron content was 65 per cent. Further test work suggested that the optimum grind size was a Psu of 25 ¦m.

Jan 1, 1999

By Innes J. A

The structural variations occurring in pellets of finely divided mixtures of iron ore and coke breeze, metallized by firing at elevated temperatures, have been examined microscopically. For any given pellet composition, time and temperature are the two most important factors in determining the development of the bonding processes.INTRODUCTIONThe success of sintering and pelletizing processes in the agglomeration of fine iron ores for blast furnace use has brought about rapid changes in thinking relative to methods of preparing furnace burdens. Increases in productivity with the use of sinter emphasize the advantages of a stable, uniformly sized furnace feed. Current practice is to produce a self-fluxing sinter containing most of the lime requirements of the furnace incorporated as a stable medium (Figgis and Charker, 1962). The elimination of fine material from the burden allows greater stack permeability and smoother operation.Sintering and pelletizing of iron ores with or without the incorporation of fluxing compounds has conditioned operators to the extent that it is now considered possible that all components of the burden may eventually be beneficiated in one form or another. Investigations are in hand to improve the quality and sizing of coke, which occupies the major part of the burden volume (Callcott, Innes and Brown, 1961; Innes, Gregory and Worner, 1963). Interest is also being revived in methods of pre-reducing iron ores prior to charging to the furnace (Hansen, Melcher and Fine, 1961). Recent experiments in a small experimental blast furnace (Melcher, 1963) show that charging of semi-metallized pellets can give rise to a production increase of 55 per cent...

Jan 1, 1963

By P Lever, D Hainsworth, H Gurgenci

The ACARP Landmark initiative has created the opportunity to advance the level of automation in the coal industry by first focusing on the core production area of longwall mining. A Landmark Longwall Automation project was commenced in July 2001. The major outcome of automation using on-face observation has been divided into ten outcome areas that have been fully scoped for a three-year initial project life. A major facilitating technology has been the implementation inertial navigation system (INS) technology that can map the shearer position in 3D. A focus of the project is to deliver a system that is at least as productive as the current most productive manually controlled longwall face.

Jan 1, 2002

Innovative Technology for Optimised Thickening Sedimentation

Sep 13, 2010

By Larkin F, Farrer E, McGhie R. R

The Electrolytic Zinc Company of Australasia Limited commenced productive operations during February, 1936, at the- Rosebery and Hercules mines, which are situated near Rosebery, Tasmania. At this time it was decided that before re-organizing the steel sharpening shop a test should be made of the relative merits of conventional drill-steel and detachable bits. For this purpose Ingersoll-Rand type"I" thread centre hole.jackbits were selected and seventy-two of these were tested against conventional steel. Results indicated that, under the conditions pertaining at these mines, j ackbits should prove more economical than conventional drill-steel bits, and that a large-scale test, under working conditions, should be made. This was done by gradually replacing conventional drill-steel with jackbits at the Rosebery mine. Results were satisfactory and by the end of 1936 both mines were using only the jackbits.

Jan 1, 1939

By M Fallon

The full history of exploration successes, failures and related costs from initial greenfield exploration in 1987 to the current brownfield stages was analysed for the Plutonic Marymia Gold Belt of Western Australia. This belt, which had escaped the attention of turn-of-the-century prospectors and had not produced any gold until 1990, is an ideal area for a collectively exhaustive, progressive value and risk case study of expected return on gold exploration. The study analyses the progressive screening of over 200 greenfield and near mine prospects, through various stages of exploration to the establishment of 38 mining sites, ranging from a few large mines to small satellite operations. It provides empirical estimates of the historical Bayesian probability of projects advancing to successive stages of exploration, eg from reconnaissance, to systematic drill testing, resource delineation, feasibility and mine development, given a successful outcome in any exploration phase. The ratio between the estimated value of the gold discovered and the corresponding historical exploration expenditure in each year and cumulatively, ie the average cost of discovery per ounce of gold, are then computed as measures of historical return on the exploration investment in this belt. These, together with an estimate of the æresidualÆ gold endowment, ie of the number and size of possible as yet undiscovered deposits, generated through the use of rank statistics (ie ZipfÆs law), provide a basis for future strategic consideration in exploration targeting in this and similar geological terranes.

Jan 1, 2009

The Hishikari gold deposit, discovered by the Metal Mining Agency of Japan, has become a giant class epithermal gold deposit with the highest grade of gold yet recorded in the world through detailed exploration and development by the Sumitomo Metal Mining Co Ltd. The exploration strategy involved a regional approach combining geological and gravity surveys over a 900 km2 area which had historically produced over 120 t of gold. These surveys were carried out to grasp the common geologic features of epithermal gold deposits in the survey area. A genetic model for epithermal gold deposits in the area under regional survey was also considered based on detailed research of the Kushikino epithermal gold deposit which was in operation at that time. This model was applied to the targeted areas, and important relationships between mineralisation, host lithology, intensive propylitic alteration and gravity highs became apparent. The Hishikari block was selected in this way and bonanza gold was discovered during drilling. Since the development of the Hishikari mine, information useful for further exploration for the same type of deposit has been accumulated.

Jan 1, 1995

This paper deals with the application of table flotation to two unusual mineral dressing problems. Both problems involved the removal of interfering minerals at sizes too coarse to normal froth flotation.The first problem was the removal of arsenical minerals from Broken Hill gravity concentrates without further size reduction. Table flotation without grinding of the original concentrates gave almost complete rejection of the arsenic from the concentrates. A typical test result was a reduction of arsenic in jig concentrate from 0.75% arsenic to 0.007% arsenic.The second problem was to develop a method to produce a high grade calcium carbonate concentrate from coastal dune sands containing about 10% silica and about 80% calcium carbonate. The sands were about 30 mesh British Standard Screen (B.S.S.), and for economic and other reasons it was stipulated that the separation be made without grinding. Again, table flotation gave excellent results. A concentrate was produced containing 99.62% acid soluble material, representing a recovery of 98.69% of the calcium carbonate in the feed with a rejection of 96.44% of the silica.The investigations' were carried out at the Kalgoorlie Metallurgical Laboratory, under the Department of Mines...

Jan 1, 1954

This paper presents an analysis of the production data for the period 1861 - 1953 from hydrothermal gold-silver deposits of the Hauraki Goldfield. To directly compare the metal content of the deposits a figure of ounces of gold equivalents (oz gold equivalent) is calculated from the value of the gold-silver bullion produced from each deposit. Frequency distributions for ore tonnage and oz gold equiv. appear to be lognormal and show a high proportion of very small deposits, with 90 per cent less than 100 000 tonnes. The deposits when plotted in order of size fall roughly on a smooth curve which suggests that the size distribution is not random. A large proportion (68 per cent) of the total gold-silver extracted from the Hauraki district was contained in the largest deposit û Waihi. A technique used for predicting undiscovered mineral resources is ZipfÆs law, which relates the size of an item to its rank order. The figures for ounce gold equivalents from the major Hauraki deposits fit ZipfÆs law remarkably well. Taking Waihi at 6.8 million oz gold equivalent as the rank one deposit, Thames is number five and Karangahake number seven. A Zipf plot indicates that down to rank 100 (68 000 oz gold equivalent) only 28 per cent of the total gold-silver resource in the Hauraki Goldfield has been extracted. A further 72 per cent or 25.4 million oz gold equivalent, including the deposits of rank 2, 3, 4, 6, 8, 9 and 10, are undiscovered. However, since some deposits will be deeply buried under younger rocks and others will be under the sea only a proportion of the total resource will be discoverable.

Jan 1, 1981

By J Wallis

The stability of a raise bore is often assessed using the rock mass classification system published by McCracken and Stacey as a modification of the Q system. Often the assessment is done using a spreadsheet to manipulate geotechnical log(s) of boreholes. This paper discusses the inherent difficulties with this approach. Recent work by others to provide guidelines to the classification system is discussed. A recent example of the design and raise bore performance at Macraes Gold Mine, New Zealand is presented. A key issue is that a visual assessment of the drill core and/or core photographs is necessary to æground-truthÆ the classification.

Jan 1, 2008

By D A. Cuello, G B. Sharrock

The Prince Lyell orebody at Mount Lyell Mine has a rich mining history commencing with the open pit in 1935, which transitioned underground in 1972. Between 1972 and 2014 a total of 64 Mt was mined underground as the mine extended from 210 m to 1100 m below surface. As the depth increased, three separate transitions in the mining method occurred to meet the changing geotechnical conditions, ore grade, mining costs and metal prices. The first was open stoping with pillar recovery in 1972, followed by front caving and longitudinal sublevel caving (1995), and finally transverse sublevel caving (2004 to 2014). This paper provides an overview of key geotechnical and planning milestones relating to the evolution of the mining method including underground stability, gravity flow, cavability and subsidence. Key aspects of the mine design, geotechnical parameters and rock mass response are described and critiqued with reference to observational, numerical and empirical methods.CITATION:Sharrock, G B and Cuello, D A, 2016. Geotechnical milestones at Mount Lyell Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 427–438 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By A S. Derrington

There are several long-standing rules of thumb that are often quoted in mine ventilation studies. They include airway ‘carrying velocities’ and the critical upcast air velocity range that must be avoided to prevent a water blanket forming. Quoting these rules of thumb may lend an air of legitimacy to a ventilation design, and allow the design engineer to avoid having to study a problem from first principles. But how valid are these shortcuts in today’s rapidly changing world? This paper summarises research into the genesis of several commonly quoted rules of thumb. It finds that they were very specific to the local conditions, practices and economics at the time they were developed. It also presents examples where applying these rules of thumb outside of their original context can lead to unexpected and erroneous results.CITATION:Derrington, A S, 2017. Ventilation rules of thumb – friend or foe? Focusing on design upcast air velocities for shafts and raise bores, in Proceedings Australian Mine Vent Conference 2017, pp 253–260 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

ignitions caused by cutting tools have occurred at a rate of some 14 per year in UK coal mines since 1965, mostly on the coalface. The rate has held steady despite reducing output and number of collieries. Investigations were carried out over this period into factors affecting both the concentration of firedamp in the cutting zone and the igniting source. A study into detecting and suppressing ignitions on shearers has been undertaken and it is feasible to prevent certain ignitions from spreading outside the cutting zone. Practical measures have been adopted by British Coal to identify frictional ignition sites and to lay down working procedures to minimise risk.

Jan 1, 1988

When a thin film of volatile matter is deposited under vacuum on a polished coal surface, and the coated surface is examined microscopically in plane-polarized reflected light, colour changes are observed which are characteristic of the various macerals present. The colour changes appear to be mainly due to interference between light reflected at the upper surface of the film and at the film!coal interface. A variety of source materials for the volatile matter required have been tested, including powdered bituminous coal, coal tars, boron oxide, and certain resins. Bituminous coal gave the best results.

Jan 1, 1970

The West Coast region of the South Island is situated astride the Pacific û Australian plate boundary zone. The most significant component of this zone is the Alpine Fault. A variety of reconstructions of the pre-Alpine Fault plate tectonic configuration of the New Zealand continental area have been attempted over the past 25 years or so. Most of these have not been closely constrained by a regional compilation of field data related to the age and horizontal displacement history of the Alpine Fault. A model in which the Alpine Fault was initiated no earlier than the interval 18 - 16.5 Ma (B.P.) is proposed, a significantly younger age of inception than has been widely accepted as the onset of dextral displacement along the plate boundary through the South Island. A subsequent history of displacement is presented consistent with the West Coast basin stratigraphy. The alluvial gold content of some parts of the Miocene to Pleistocene conglomerate sequences is also discussed.

Jan 1, 1996

By H Thanasekaran, J Kohmuench, B Seaman

To achieve an efficient separation in the flotation process, valuable particles need to be selectively segregated from the gangue while utilising a minimum number of flotation stages. TodayÆs existing flotation technologies are effective for fine particle size classes; however, limitations due to particle buoyancy and bubble-particle detachment restrict the effectiveness of traditional flotation approaches on coarser particles. As a result, flotation circuits are generally configured to process only fine particle size classes in order to maximise recovery in the primary stages. Eriez has invented a novel flotation technology, the HydroFloat, which overcomes these limitations by carrying-out flotation in a dense, fluidised-bed medium allowing for the recovery of coarse particles (>0.250 mm). Over the last 15 years, this technology has been successfully applied to industrial minerals with several full-scale units installed to recover particles up to and exceeding 3 mm diameter in primary flotation circuits. This paper includes discussions on the history of this technology, process theory, existing applications, and a review of recent sulphide-based laboratory test work conducted for Newcrest mining and others. Benefits of this approach, such as improved recovery, low energy consumption and reduced reagent addition will also be reviewed.CITATION:Kohmuench, J, Thanasekaran, H and Seaman, B, 2013. Advances in coarse particle flotation - Copper and gold, in Proceedings MetPlant 2013 , pp 378-386 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

The main factors which influence disposal of mine waste under New Zealand conditions are identified and discussed: namely, geological conditions which produce soft weather-sensitive waste, wet and cold winters which affect productivity in such waste, elevated seismicity which affects stability and the need for water rights which involve public participation. The waste disposal scheme for the Martha Hill Project is described, thereby illustrating how these factors influence the planning of a current mine strippings and tailings disposal scheme.

Jan 1, 1986