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Production scheduling of open pit mining is a key area as it deals with the management of operating cash flows of mining companies. The efficiency of long-term schedules is usually assessed with economic criteria such as net present value (NPV), discounted cash flow rate of return (DCFROR) and payback period, which are not sufficient on their own for revealing the complex picture of the decision-making process.This paper offers a thorough analysis of the most important contemporary criteria of long-term production scheduling, as way to provide the mining practice with a new approach to the decision-making process. The list of criteria includes technological, economic and probabilistic ones. A detailed case study is provided aiming to illustrate the applicability of the criteria for comparing the scheduling approaches regarding the economic interests of a mineÆs owner and contractor. The results obtained can be used for revealing new trends in the current methodology of open-pit production scheduling optimisations.

Sep 26, 2011

By R R. Lovel, G J. Sparrow

Currently there are large reserves of good quality iron ore near to existing infrastructure that are not being developed because the phosphorous levels are above acceptable market specifications. Since the high phosphorous content is considered to be mainly associated with the goethite fractions of the ore, attempts were made to leach the phosphorous from the ore after a heat treatment to dehydroxylate the goethite. Heating the ore and leaching with 40 g/L NaOH lowered the phosphorous levels from 0.145 wt per cent P to 0.075 wt per cent P or lower, but a heating temperature over 800¦C was required to achieve this reduction in phosphorous levels. However, when sodium hydroxide was added to the iron ore before the heat treatment, similar phosphorous removal was achieved with a heating temperature of 300 - 350¦C. It was considered that dehydroxylation of the goethite in the presence of the hydroxide makes the phosphorous available for removal with a water leach. As well, 50 per cent of the silica and 60 per cent of the alumina in the ore were also removed in the leach, but some sodium remained in the leach product. Further work is required to remove the residual sodium to produce a marketable product.

Jan 1, 2009

By McMullen P. H

Mining of copper ore at Mount Lyell has been continuous since 1893. The operation has always been marginal and the depressed copper Market over the last decade has seen mining continue on the basis of a series of short term plans. In 1985 it was determined that the mine would close in 1989 on completion of the 40 Series mining block. Significant changes in the value of the Australian dollar in 1986 and the subsequent effect on profitability dictated a review of the Company's operations. Lower level ore reserves, mining methods and ore handling systems were re-examined and a plan proposed for mining of the 50 and 60 Series mining blocks. The improved economics of this plan, together with workforce and State Government initiatives resulted in an extension of mine life to 1994.

Jan 1, 1988

By Filmer AO

In contrast to the '50s and '60s, the period of the '80s and '90s seems likely to have low growth in demand but much greater levels of technological change. In such a climate there will be pressure on costs, productivity will continue to rise and competitiveness will be closely associated with maintenance of the most effective technology. The penalties for inappropriate investments, whether short sighted or mistakenly based on a particular view of the future, will be greatly enhanced. Accordingly, there will be a need for significantly improved anticipation of technical change and thus for better planning. Study of the funding and direction of the world's R&D effort can provide a useful input to the planning processes within industries and individual firms. Such a study also suggests some insights into the characteristics of those countries which have achieved substantial growth and high standards of living over the past two decades. These characteristics may offer significant reminders for our own development. The particular implications for the Australian minerals industry include the need for direction that is sensitive to changing market requirements and customer practice. This is not simply "more of the same." In particular it appears essential for both basic and applied R&D to provide a sound basis for the purchase and ongoing development of the new technology required to achieve international Competitiveness.

Jan 1, 1986

The last decade has seen a dramatic change in the. size and complexity of mining and mineral processing projects in Austral- asia. Major projects of today are vastly different from major projects of the 19.50's. This change has in turn resulted in a change in the role-of consultants whose contributions have been increasingly in the provision of specialist services and less in the form of overall project design and construction supervision. It is anticipated that, the specialist function will continue to represent the principle mode for consultant participation in major, projects. However, by means' of international affiliation, the development of comprehensive engineering and project management capabilities and possibly as a result of Government intervention, it is expected ,that local consultants will assume an increasing degree of participation in.the overall project design and supervision Function.

Jan 1, 1975

By I C. Carrasco, V G. Mirada, J F. D Domingo, F S. Leite

This paper investigates ore loss and dilution produced by rock movement in bench blasting. A total of four blasts, in which electronic detonators have been used, were monitored in Cobre Las Cruces Open Pit Mine (FQM Ltd) in Gerena (Sevilla, Spain). Rock motion has been obtained in 137 points of the free face and 6 points inside the block. Multiple liner regression has been applied to predict rock motion and estimate ore dilution as a function of hole coordinates, rock contacts, powder factor/hole, amount of explosive per blasthole, burden, spacing, hole length, stemming length, explosive energy, hole row, subdrilling, blast sequence, stiffness ratio, blasthole distance to free face, rock density and Young’s modulus. The model is statistically significant with a determination coefficient over 0.8. Rock motion measurements in 31 more points have been used to validate the model and to show a reduction in ore dilution.CITATION:Domingo, J F D, Leite, F S, Mirada, V G and Carrasco, I C, 2015. Dilution, ore grade and blast movement calculation model, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 71–78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By OÆGrady P

Finite element analysis is becoming a routine component of design of longwall extractions, now superseding more traditional somewhat intuitive approaches. Finite element modelling is relatively inexpensive and provides an adequate degree of similitude to give satisfactory analysis. The physical modelling of two decades ago is now largely replaced by numerical methods of which finite element is the best known. Important data for finite element work are physical properties, including creep aspects, introducing the non-linearity of stress response.Various computer packages are available and some were used to model two specific UK examples, using both linear and non-linear approaches. It appears that non-linear approaches will yield most benefit. The use of materially non-linear analysis is merited by the greater similitude it provides between model output and real mine situations.

Jan 1, 1991

The genesis of the Bulong Laterite Ni/Co deposit spans some 60 per cent of earth history: from development of the parent rocks in the Archaean to lateritic weathering in the Cainozoic. In a man's term, the discovery and evaluation history of the deposits has also been protracted and, at any given time, the perceived value of the deposits has depended upon the available technology and world markets.

Jan 1, 1996

In recent years a large amount of work has been done at various plants overseas, and also at Broken Hill Associated Smelters, Port Pirie, South Australia, on the use of Dwight Lloyd sintering plant gases for sulphuric acid manufacture by the contact process.Several plants have modified their sintering machines and operating procedure, and some have adopted gas recirculation techniques, to obtain a relatively high proportion of the sintering plant gas at an S02 concentration acceptable to a contact acid plant 1.These adaptations were investigated at Port Pirie, and it was found that gases of suitable S02 concentration could be obtained. The results justified installation of a contact acid plant and a decision was accordingly made in 1949 to construct such a plant.However, the local conditions presented some difficulties not generally encountered at other plants, the chief differences being:a. For maintenance of production of 98% H2S04 , an unusually high S02 concentration is required, because of the prevailing high temperature 'of the purification train cooling water.b. The entire sintering operation is conducted on two large machines, 55ft. x 10ft., operating in series as "First" and "Second over" machines (a two-pass roast.) Any interruption" to either machine causes a complete interruption of plant operation and gas flow.

Jan 1, 1951

By Fermino R

Reduction of waste oxides from steel plant operations was investigated in a laboratory tube furnace at different temperatures and furnace atmospheres. The results have shown that the waste oxide pellets are reduced rapidly to very high degrees of metallization irrespective of the furnace atmosphere and that the reduction is simultaneously accompanied by significant low- ering of the original impurities. It is shown, for example, that treatment at 1000¦C for 30 min. can reduce the Zn content from 0.98% to 0.0065% and K and Na contents from 0.19% and 0.76% respectively, to less than 0.01%. However, pellet strength at 1000¦C was low but this, as shown in the paper, can be very significantly improved by treatment at 1250¦C. The results indicate that the reduction of the waste oxide pellets of this investigation proceeds almost certainly by a chain reaction mechanism and that this principle could be advantageously extended to the reduction of iron ores and other oxides in general.

Jan 1, 1984

The paper presents the results of laboratory blasting and grinding experiments on a low-grade iron ore, investigating how blasting will influence the subsequent crushing and grinding operations. Increased blasting energy will lead to a reducti

Jan 1, 1998

By Goldstone A

The paper introduces a newly developed multi-function test rig for fracture grouting. This test rig has many functions and its performance is consistent. It can control and adjust accurately the opening degree of fissures and static pres- sure; it can measure automatically the quantity of grout injected; it can measure precisely pressure drop of grout in fissures; it can test the results of injection, including effective dispersed distance, anti-filtration capacity of consolidated body, mechanical strength, etc. It can inject a single or two grouts into one or several fissures at a pressure of 16 MPa. Therefore, it is an ideal test rig for fracture injection. The paper depicts all the components of the test rig, its performance and application of the results obtained from fracture grouting tests. Examples are briefly described.

Jan 1, 1988

By Smith T. N, Wild M. B, Elliot B. J

The process of flash smelting of nickel sulphide ores, as practised at the Kalgoorlie Nickel Smelter, is described. The critical variables in the operation of this process are identified. The design of a pilot-scale, turbulent-jet flash reactor which models the essential features of the industrial smelter is described. A report of its operation and application to an investigation of the ignition of particles of sulphide species is given.

Jan 1, 1991

By Wu Y, Qu Q

The Central Coal Mining Research Institute has developed the MAE acoustic emission monitoring system, the BD4-1 portable acoustic emission monitor and the MRB rock burst monitoring system. In the MAE system there is an IBM-PLAT, a receiver and 16 channels and the investigating range is 100 m. The main functions are detecting acoustic events from the working faces, periodically making statistics, prints, displays and storing of the results, and performing the off-line process such as drawing the curves of acoustic activity. The BD4-1 instrument has four channels, it works for more than 24 hours continuously, and keeps the data for more than 30 days after power tum-off. The BD4-1 is suited to the monitoring for a long or a short time as a fixed point where the system is invalid, especially to the monitoring of the acoustic activity promoted by the blasting. There is an IBM-PC/AT, a receiver and 16 channels spread 10 km in the system MRB. The system could on-line collect microseismic events throughout the whole mine, calculate the source location and the energy, and off-line draw the seismic activity draft of time-based or distribution in space. In practice, the forecasting is successful by using the acoustic emission and microseismic monitoring system and the portable instrument.

Jan 1, 1991

By Braaksma M, Dudley K

The Girilambone Copper Mine is located in central New South Wales and has been operational since May 1993. Girilambone is operated by the Girilambone Copper Company (GCC) which is a joint venture between Straits Resources (60 per cent) and Nord Resources (40 per cent). The mine complex consists of an open cut pit, ore crushing and stacking, heap leaching, solvent extraction (SX) and electrowinning (EW) allowing for the recovery of 14 600 tpa of LME grade A cathode copper. The leaching and SX-EW plant have been described previously by Rear, Taylor and Busby (1994) and Miller (1994).

Jan 1, 1996

By Hebbard GJ

Vertical crater retreat mining is being used at Zinc Corporation, Limited and New Broken Hill Consolidated, Limited for pillar recovery between previously mined and filled stopes. In order to increase productivity in the older lead lode areas of the mine, particularly in the lower grade sections around the keel of the orebody, score form of longhole stoping was considered necessary.Due to poor ground conditions in the country rock surrounding the ore and the requirement to provide sane wall support during mining, primary VCR mining has been utilised in these areas.At Zinc Corporation, several stopes have thus far been mined by a hybrid longhole stripping - VCR method.

Jan 1, 1985

By Terlich R. E, Finlayson J. M

A combination of high virgin rock temperatures, deep workings and extensive utilisation of heavy diesel equipment has presented North Mine (A Division of North Broken Hill Limited) with challenging ventilation problems. These problems have been addressed in a variety of ways which include in the order of 6000 kM of underground refrigeration. The future of North Mine depends on the successful development and extraction of ore in excess of 1100 m below the shaft collar using mechanised cut and fill mining. The success of this will depend on the installation of a complex chilled water reticulation circuit in this area. This will involve planning and constriction of a number of large dams, installation of pups and turbines, and the successful commissioning of several large water to air heat exchangers.

Jan 1, 1988

By T P. Hynes

Submarine tailings disposal is conceptually an attractive option for managing reactive mine wastes in coastal regions by virtue of reduced sulfide oxidation under a water cover and no infrastructure to maintain after mine closure. However, the lack of detailed knowledge of metal leaching, dispersal of fine tailings and biological impacts in the marine environment has led to no operating permits currently in effect in Canada. Detailed chemical and ecotoxicological assessments at two historic copper mine sites (Little Bay and Tilt Cove) in the north coast of Newfoundland with tailings disposed in an estuarine to shallow (=100 m) marine environment have demonstrated reduced reactivity of sulfidic tailings when submerged under water. Only non-acute toxicity is detected in biota inhabiting the immediate vicinity (A review of another historic shallow marine tailings operation in the southern tip of Vancouver Island (Jordon River) with a high-energy setting also reveals problems with unconfined tailings dispersal and temporal biological impacts. Documented studies at two deeper (140 - 360 m) marine tailings disposal operations at the northern tip of Vancouver Island (Island Copper) and northwestern coast of British Columbia (Kitsault) again illustrate imperfect predictions of tailings re-suspension and dispersal. At these sites, bioaccumulation of tailings-derived metals appears to be minimal. There is evidence of rapid re-colonisation of the tailings surface by benthos but of different species than the original population. Integrating these observations with reported metal fluxes and biological diversity associated with submarine hydrothermal vents, the risks and benefits of deep-sea (>1 km) tailings disposal are discussed. To determine if submarine tailings disposal in deep, confined basins on the seafloor is environmentally friendly, detailed multi-disciplinary research incorporating physical, chemical, biological and toxicological components will be indispensable.

Jan 1, 2003

By D Burgess

Since the days of mandatory high cost pilot plant testing in 6 ft + 2 ft SAG mills autogenous griding/semi-autogenous grinding (AG/SAG), mill specific energy is now calculated by various empirical formulae and pilot testing carried out in small laboratory mills. Barratt (1989) described a method using Bond Indices than adding a single factor of 1.25 to arrive at the AG/SAG specific energy. In 1991 the Canadians developed the SAGPower Index (SPI), test using 2 kg of material in a 300 mm diameter mill. This test has been further developed by Starkey, Hindstrom and Orser (2006). This test now includes a Bond Ball mill work index test.The Macpherson test is still being offered by some testing facilities. This dry test requires at least 180 kg of material.Morrell (2004) formulated an AG/SAG specific energy generator based on a drop weight index Value (DWi). This DWi value is related to the Ab parameter and the material specific gravity. Morrell reconfigured the BondÆs Third Theory formula to cause extra power requirements to be inputed. This technique incorporates the material specific gravity (SG). The AG/SAG specific energy values produced using this method are susceptible to higher values of crushing and rod mill work indices.This paper offered describes a more simple method to generate AG/SAG specific energies. This programme incorporates Bond work indices, the JKMRC parameter Ab measuring impact breakage and the parameter ta measuring the abrasion rate, then employs a series of efficiency values nominated for each transition size (AG/SAG T80). These efficiency values have been compiled over the years from actual operating plants and documented reports.CITATION:Burgess, D, 2012. A method of calculating autogenous/semi-autogenous grinding mill specific energies using a combination of bond work indices and Julius Kruttschnitt parameters, then applying efficiency factors, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 37-44 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Depletion of shallow ore reserves is forcing the South African gold mining industry to exploit reefs at ever-increasing depths. By 2010 around 30 per cent of South African gold production probably will come from depths greater than 3 km (Johnson and Schweitzer, 1996). At such depths, virgin stresses will rise significantly, producing complex rock engineering problems (Malan and Basson, 1998). Concern over structural instability at depth has led planners to seek a technology capable of ædetection of geological structures with a displacement of 2 m or greater (or as appropriate to the mining technique) 200 m ahead of mining at an acceptable costÆ. Borehole radar probably is such a technology. Cover holes are drilled routinely ahead of development. The evaluation of its candidacy for a tactical role in ultra-deep gold mining dependsùamong other thingsùupon establishing the electromagnetic characteristics of the environment hosting significant gold reefs. The Ventersdorp Contact Reef (VCR) is one such reef. Recent borehole radar field trials, presented here, suggest that the VCRÆs overburden is a remarkably translucent, clutter-free dielectric with a Q of ~35 and that the VCR itself is the dominant radar reflector.

Jan 1, 2002