Search Documents

Productivity of mines can be improved by taking fewer, but larger blasts. The initial blasts taken in starting a mining block are restricted by the low amount of void or space to fire into. Block cave mines are using a blasting technique to blast areas that have less than the normally accepted minimum void to establish drawbells for their orebody development. This technique used in block caving mines can be used to improve productivity in mining operations that utilise other mining methods. Some larger blasts have been done in mines, using open stoping methods, which have had void ratios as low as 13 per cent. This has been possible with the use of the explosive gases to transport the broken rock out of the area normally considered to be available to blasts. This trapping of the explosive gases in the broken rock has allowed rock to be moved over 30 m, horizontally, to allow for more void to be available in the blast area. This gives the necessary void ratio allowable to fire larger blasts. This paper will discuss the blasts where this technique has been used in mines to increase the tonnes fired in low void situations. It will also discuss where this type of blasting may improve the productivity of underground mines. Figure 1 shows the how explosive gases have enabled the broken rock to flow out of a draw point without the typical air blast and fly rock that would normally cause a rope suspended sign to be damaged beyond use.

Jan 1, 2008

By B R. Olsson, N Marinopoulos

To establish the design and the capacity of the Stanwell Magnesium Plant, Australian Magnesium Corporation Ltd (AMC) with Fluor Australia has modelled the operation of the magnesium plant using ARENA Simulation Modelling. The reliability model has been used to evaluate: surge capacities required between different sections of the plant; critical equipment requiring standby capacity; the number of trains required for different sections of the plant; and potential capital cost reduction options. The reliability model was established using the detailed Process Flow Diagrams, reliability information from literature and maintenance, operation and start-up experience from the Demonstration Plant. The model was run with different plant configurations to assist AMC in determining the most effective configuration to provide the production capacity at the lowest capital cost. The model was not only able to confirm the plant capacity to the independent technical expert but was able to minimise quantitative risk by minimising the quantities of hazardous materials on site. Fluor Australia provided the ARENA simulation expertise and has used this software for optimising new plant design and to establish improvements in operating plants. Reliability modelling is a normal feature of chemical plant design but is rarely used in the resource industry. The experience gained by AMC in the modelling system has indicated that metallurgical plant design can be improved by the application of reliability modelling.

Jan 1, 2002

Material hardness and environmental factors can limit or restrict conventional blasting techniques and this has led to advancements in the performance and efficiency of ripping. Not all materials can be ripped, however today's technology and experience can help make a reasonable prediction. A ripping versus blasting decision will depend on the total volume of material to be moved, the production capabilities and costs of the ripping tractor(s) and on the size and relative efficiency of drilling and Blasting.

Jan 1, 1995

By S La Brooy, C Fountain

Throughout its history the mining industry has focused on the highest-grade deposits sited in the most convenient locations. The burgeoning global population and higher standards of living not only increase the demand for mineral products but also make it harder to mine and process them. The future will include the development of lower-grade, more complex orebodies, and orebodies in difficult locations. The industry will be expected to provide for humanityÆs needs while reducing its environmental footprint and maintaining profitability. This paper reviews some of the likely adaptations in mineral processing that will occur over the next 20 years. The challenges inherent in adapting to lower grade and more complex materials might be exacerbated by such factors as the availability of water and low-cost energy. In underground mining, higher energy costs are likely to foster further developments in underground preconcentration, especially for ores that can be upgraded at relatively coarse sizes. The adoption of underground crushing could also render material amenable to semi-dry preconcentration options such as might be achieved by the rotary classifier developed by CSIRO and being commercialised by RCR Tomlinson, or more modern versions of the hand-sorting of ore that use sensors based on colour or other suitable rock properties. The cement industry and some gold roasters have used the alternative of dry grinding and classification, which might also have a part to play in dry processing. There is also likely to be increased interest in options such as in situ leaching that further minimise the surface disturbance. Underground operations will have to balance the energy savings from reducing the amount of material brought to the surface and reduced surface disturbance against the practical limitations of installing and maintaining processing equipment underground. On the other hand, surface disturbance and energy issues in open cut operations will be balanced by potentially lower mining costs and higher overall recovery from the deposit.

Jan 1, 2008

In engineering applications of explosives for rock breaking, the released energy is expended mainly into heat, rock crushing and fracturing, seismic waves, air blast, and noise. Those parts of energy which pass into seismic waves and air wave create environmental problems since they are transmitted away from the blast site. In order to predict the environmental effects accurately, one must be able to predict the energy distribution at the source. The energy distribution at the source is significantly controlled by the blast constriction. Consequently, the accuracy of prediction and control of ground vibrations generated by blasting is affected by various matrices of blasting constriction.

Jan 1, 1986

By Boyack DJ

DEFINING AN ECONOMIC TARGETExploration usually begins with the corporate goal of finding a minimum tonnage and grade of a selected mineral. Sometimes this is expressed more simply as a minimum quantity of contained metal without any indication of the desired grade or implied profitability. Such a goal is useful in the selection of exploration areas and the planning of initial drilling programs. However, it should be reviewed as soon as significant mineralisation has been identified. To make rational decisions about exploration expenditure, the potential return from a deposit must be estimated from the outset and re-esti-mated frequently.The potential return will depend on:1. The proportion of mineral which can be economically recovered from the deposit by mining (the mining recovery).2. The quantity of valuable constituent that can be recovered after dilution with waste rock during mining and losses due to incomplete metallurgical recovery.3. Expectations of price and markets.4. Capital and operating costs applying to the selected mining and processing methods, and to transportation and marketing. Increasingly, environmental costs and constraints must also be considered.

Jan 1, 1990

By Fourney W. L, Weaver T. A

A large number of single borehole crater-forming shots were analyzed in terms of correlating the crater parameters with explosive weight. The objective was to determine a scaling rule for which the explosive weights varies over many orders of magnitude and covers many different geologic materials. Included in the data base are type and weight of the explosive, geologic medium and degree of saturation, charge depth-of-burial, crater dimensions, and crater rim (lip) measurements. An alternative scheme to the usual plot of scaled depth-of-burial versus scaled volume removed was desired. The proposed technique uses a plot of the logarithm of the explosive weight, Y, versus the logarithm of the slant length, R', calculated from the known depth-of-burial of the explosive and the measured crater radius. A plot of Log Y in kilotons versus Log R' in meters from all the crater tests in this data base resulted in a straight line with a of slope 0.31 and showed good correlation between the variables Log Y and Log R'. Since the crater data includes many geologic materials, different explosives (including nuclear tests), and large differences in charge weight, the straight line fit suggests that the type and strength of the geologic materials play a subordinate role to explosive energy in crater formation.\

Jan 1, 1990

Attention is given to three possible alternative structures namely corporate joint venture, partnership joint venture and unincorporated joint venture. A corporate joint venture involves the formation of a separate and distinct legal entity with limited liability. The shareholders of the Company will be the members of the consortium. A partnership joint venture involves the members of the consortium joining a formal partnership. The partners will conduct the business in common with each other and will share the profits and losses of the project activities. The partners will be jointly and severally liable. An unincorporated joint venture is distinct from a partnership. The members of the venture will not be jointly and severally liable. Taxation and accounting aspects are examined and an outline provided of a typical joint venture agreement. The two main advantages of an unincorporated joint venture are considered to be a favourable treatment for income tax purposes and a greater degree of flexibility when compared with the corporate joint venture and the partnership joint venture.

Jan 1, 1983

In the new refinery, at the works of the Broken Hill Associated Smelters Proprietary Limited, situated at Port Pirie, South Australia, the refining routine is similar to that carried on in the old one in that bullion is progressively refined first for arsenic and antimony, then for copper and gold, then for silver, and finally for zinc. However, actual procedure differs in that each refining operation is now conducted continuously, whereas in the old refinery intermittent batch treatment was practised.The early experimental work was concerned solely with the development of the continuous desilverising process, which, in addition to continuous treatment, embraces the novel feature of conjugate solution formation with consequent production of a silver product relatively high in silver and low in lead.

Jan 1, 1932

The design and construction of a 2.5 million tonne per annum ship unloading system at the PWCS export coal terminal in Newcastle, NSW, has further increased the flexibility and sophistication of Australia's largest coal export facility. The system comprises a new unloading wharf serviced by a self unloading vessel, conveyor stream and multi compartment ground level storage shed. Coal is reclaimed from this shed by the largest portal scraper ever installed under cover. The system also provides additional flexibility by receiving coal from the existing PWCS road receival to improve scheduling. The PWCS can now simultaneously handle 11 coal types and receive from rail, road and sea at almost 15000 tonnes per hour.

Jan 1, 1987

By M F. Navarrete

During 2003, different plastic stemming plugs (Cats«, Stemtite«, and Taponex«) were tested in EscondidaÆs Mina Sur, to determine the effect on gas retention time when used in conjunction with drill cuttings in production shots with a blasthole diameter of 10 5/8ö. Longer retention times were expected to provide greater fragmentation and muckpile looseness. In order to determine which plug showed the greatest enhancement of stemming retention, 17 trials were carried out û in the first seven tests, only the Cats were used, in the following five tests, a combination of Cats, Taponex and Stemtite were used, and in the last three tests, only the Taponex plug was used. In the last two blasts, drill cuttings were used without stemming plugs as a benchmarking exercise. Blasts were filmed with a high-speed camera, which could record the detonation times of holes using rolls of shock tube tied to stakes at the hole collars, to act as flash indicators. The camera allowed measurement of the time between charge detonation and the commencement of stemming ejection. In order to obtain the statistical parameters of each one of the stemming plugs used in the 17 trials carried out, the Minitab software was used and a data base was created for it, corresponding to each stemming configuration with the retention time obtained from the filming. Once it was determined which stemming plug provided the greatest enhancement of stemming retention, the impact on the fragmentation was analysed using the WipFrag image analysis software to estimate the muckpile size distribution.

Jan 1, 2004

Reliable predictions of the long-term water quality and water level fluctuations in a final void are vital if mine operators propose to decommission final voids in open cut mining operations. The catchments feeding final voids typically comprise a large proportion of coal placed or re-shaped spoil piles. Spoil piles from open cut coal mining operations have distinctive hydrological characteristics, which result in unique run-off behaviour. There is a need to understand the nature of spoil hydrology processes in order to predict the long-term hydrological behaviour and water quality responses of such systems. Preliminary estimates indicate that it may take 20 or more years for a void to flood. It is impractical for mine owners and operators to wait until long-term hydrological and water quality conditions have been established in a void, before reaching agreement with regulators about mine closure conditions. Reliable simulation of the long-term water quality and water level fluctuations in a void are therefore. The adoption of an agreed modelling approach and sharing of results from field data programs could result in the establishment of a database that could be used, with regulatory approval, for assigning parameter values, without the need for a specific data collection program for every individual void. Industry and regulators should agree on the model adopted for predicting post-closure behaviour of spoil/void systems. This will require reliable, robust methods for field data collection. This paper describes the field monitoring, data collection, model preparation and simulations undertaken over a three year period for Australian Coal Association Research Projects (ACARP) Project C7007. It presents the findings of that research, and provides comment on aspects of the project that were undertaken well and on aspects that could have been done better. Limited data is presented in this paper due to confidentiality arrangements with the relevant mine sites.

Jan 1, 2003

An account of milling "methods and costs at Mount Isa Mines Limited up to the year 1938 has been published. The present paper outlines the methods since adopted in the milling of lead-zinc ores and presents a description of the equipment now being provided for the milling of copper ore.The programme approved for the mining, milling and smelting of both lead-zinc and copper ores involves the milling 9f 50,000 tons of lead-:-zinc ore and 35,000 tons of copper ore per month.The crushed ores will be delivered to the surface from alternate levels through No. 2 Ore shaft and conveyed to their respective crude ore bins at the crushing plant. The ores will be crushed and milled in separate circuits in common buildings and the tailings will be stored on a common tailings dump. The water services to the two circuits will be separate.LEAD ZINC PLANTCrushing PlantThe crushing plant described in the previous paper was located adjacent to the Urquhart shaft. The crushing plant had grown considerably over the years by the addition of a 4ft. BY-mons shorthead crusher and a set of Traylor 72 in. x 20 in. crushing rolls and, whilst operating satisfactorily, was difficult to maintain and cramped in many places. As a satisfactory layout for the new copper crushing plant could not be made in the vicinity of the, existing plant, it was decided to construct a new plant on the western side of theconcentrator building and provide identical equipment in...

Jan 1, 1953

Opencast blasting is notoriously subject to variable blasting conditions, some of which are related to changes in ground conditions and some to human and equipment factors. As drilling and blasting constitute a high proportion of working costs, control in this area is crucial for good management. During a recent exercise, wireline logging of blastholes was shown to have the potential to provide invaluable data for optimising blasting control and design. The paper reports on the exercise undertaken, showing that serious misconceptions as to the borehole diameters, explosive densities and posi- tions of decking were quickly corrected using the method. Potential use in blast design is discussed, as are the cost implications.

Jan 1, 1988

By M E. Pierce

Recent advances in comminution and heap leach technology have resulted in the development of many large-scale, low-grade open pit mines that coincide with areas of historical underground workings. Twoand three-dimensional numerical modelling has been conducted to assess the interaction between open pit slope stability and remnant underground voids. Most design analyses for open pit slopes assume a two-dimensional problem geometry. This is not the condition encountered in practice ù particularly when remnant underground voids interact with a large-scale open pit slope. Three-dimensional numerical models have been shown to provide a more realistic representation of the interaction between overall open pit slope stability and remnant underground voids.

Jan 1, 2003

By McKenzie C. K

During a programme of explosive performance evaluation at Hamersley Iron, Mount Tom Price Mining Operations, the relative performances of a range of heavy ANFO explosives were compared during normal production blasting operations. In addition, a number of heavily instrumented single hole blasting trials were conducted with each product type. The blasts were monitored in terms of blasthole velocity of detonation (VOD), measured using multi-point plasma conductivity probes with up to 16 measurements per blasthole. Up to 16 blastholes were monitored in each production blast. The results of measurements show a marked difference in performance of all heavy ANFO products between single blastholes and full production blasts, indicating a significant degree of interaction between blastholes in production blasting. The interaction is shown to result in a loss of detonation pressure of explosive, and considered to lead to a loss of fragmentation. The degree of interaction is seen to increase with increasing emulsion content in the products, and is more pronounced in some explosive types than others. The paper presents the methods of measurement and analysis, and the results of monitoring, together with implications on blast design and application of heavy ANFO products.

Jan 1, 1990

The paper describes a computer model developed within the State Electricity Commis- sion of Victoria for use in open cut planning. The purpose of the model is to simulate all the typical occurrences in, and influences on, the coal supply and overburden disposal systems in order to be able to assess their performance. The model incorporates much of the long term and day-to-day operations planning logic required for the allocation of resources within an open cut. This logic takes account of power station demands, bunker stocks, plant and crew availability, the balance of reserves between dredgers, planned maintenance, etc. The perfor- mance of plant within the system is simulated using random selections from statistical distri- butions of Time to Failure and Time of Failure for each plant item. The application of the model in selecting a suitable bunker capacity in a notional open cut development is described to illustrate the potential of the model in optimising plant selection.

Jan 1, 1982

By Chavant G, Begis D, Gunther J

To study the ventilation of a mine (improve on the existing situation, examine extension projects) the calculation program used must take into account all the resistance values in the branches of the network. These resistance values are generally determined by measurements, which are accurate to a greater or lesser extent. In order to arrive by calculation at the flowrates measured :n the mine at a given moment, the resistance values have tto be adjusted experimentally. This manual operation is lengthy and delicate.

Jan 1, 1988

Mine geologists have access to an economic mineral deposit, production parameters and secure exploitation title. They are well placed to understand ore formation and should contribute to the effective exploration of company mine property. Application of their special skills has been curbed by pre-occupation with production duties and by company re-engineering, including staff reductions. Contributions to exploration have been diminished and personal development inhibited. Modified management is required. Participation in mineral system studies and in exploration research comprise part of the basis for the re-emergence of mine geologists on the exploration scene. Changes in investment strategies in the minerals industry may create new employment opportunities. With regard to estimation of resources and reserves, the competence of practitioners who are incapable of disclosing their methods in transparent terms is under question. Ethical standards are also under public scrutiny because of some notable malpractice. Independent auditing may hecome more intrusive. While understandable in a market context, it reflects poorly on the profession. More substantial effort in public communications can improve the credihility ofthe industry and equip practising mine ceolouists for snider responsihility.

Jan 1, 1997

By Pinn N

Geosynthetics is an all encompassing word to describe a number of man-made products usually from hydrocarbons which are used in conjunction with the soil. The specific products are:Geotextiles Geomembranes GeonetsGeogrids GeocompositesIn mine establishment and associated construction work, Geosynthetics have proven to be successful in a wide range of applications. For example, geotextiles are now used to assist with the establishment of access roads, site preparation, haul roads and in connection with the construction of embankments for storage ponds and dams as well as for general hydraulic and foundation engineering problems.

Jan 1, 1990