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The word "optimization", refers to the search of an economic optimum, or, more precisely, to the choice of technical parameters which will define the more profitable mining project, knowing the values of the economic parameters. In fact, there is no direct way to perform this optimization, because the extremely large number of technical factors involved, from the type of working and its selectivity to the characteristics of the mill and its flexibility, makes it impossible to make a comprehensive survey of all possible projects. Beside, it would be meaningless to engage in such a task as the deposits themselves are not really known, but only estimated, with sometimes a high level of imprecision. Not to mention the numerical instability which would affect such a computation! In addition, the "best" project is not necessarily the one which strictly maximizes a given profit formula. There also exist human factors which have to be complied with, when choosing the cutoff grades for instance. Finally, there are other non-numerical factors which interfere with the choice between several projects: the shape of the bottom of a pit of the layout of the access road for instance.

Jan 1, 1986

In the late 1970's Western Mining Corporation, Exploration Division considered the purchase of a major multi-element spectrometer as an adjunct to our existing atomic absorption spectrophotometers. The analytical work proposed for the unit included barium, uranium and rare earth elements from Olympic Dam, uranium, sulphur, vanadium and strontium on Yeelirrie type deposits, major element and whole rock analysis, multi-element analysis of samples from the laterite, chromium and manganese exploration programmes and tin and arsenic analysis. These were all analyses that were not readily or easily performed by flame atomic absorption or were where we expected that a simultaneous multi-element instrument would be an advantage. Also the turnaround times for the commercial laboratories was considered unacceptably long for some determinations. Other factors, important when considering the spectrometer were the ability to ensure confidentiality of results and the ability to assign our own priorities and not to have to rely on commercial laboratories. The two techniques considered were X-ray Fluorescence Spectrometry and Inductively Coupled Plasma Optical Emission Spectrometry. The decision was made in favour of the ICP unit for several reasons. The ICP fitted in with our existing methodology, ie samples digested for atomic absorption or colorimetric techniques would also be suitable for ICP analysis and vice versa. The technique was suitable for water samples and for major element analyses and for rare earth elements. X-ray fluorescence spectrometers were installed at the Kambalda and Belmont laboratories and would be available to us for routine checking and for elements not suitable for ICP analysis. The final consideration was price. ICP was considerably cheaper than XRF.

Jan 1, 1987

By Luke K. A

Pressure on production at New Zealand China Clays has led to the development of a dewatering control loop for fine halloysite china clay. The development was based on the analysis of data from the automation of plate and frame filter presses. The analysis of the data has led to process changes, and the ability to quickly solve dewatering problems. As a result of control in the dewatering circuit press times have reduced on average 117% and output has increased proportionally.

Jan 1, 1989

One of the features of modern life has been the increasing speed of change. We see this in many facets of activity, but in few areas more clearly than in the financial sector. The speed of communication and the advent of screen trading have made world markets one.We have titled this presentation "Cycles". It has been the conventional wisdom that Economies, Metal Prices, Equity Markets, etc. move in cycles. The objective of our presentation is to examine these cycles, to comment on the interrelationships, and to postulate where we are in The Current Cycle". We will draw conclusions as to where one should direct effort in the Mineral Scene over the next decade or so.Throughout this discussion we will use various terms to describe Time. The "Short Term" is typically meant to refer to the next six months: the "Medium Term" is one to two years; and the "Long Term" is the three to five year horizon.

Jan 1, 1990

By Yu A. B

An experimental study of the packing of a coal heap has been carried out. The bulk density of a coal heap is considered as a function of a number of variables, viz flow rate, conveyor belt speed, the height of the disengagement point of the conveyor belt, coal particle density, moisture content, the size of the heap and coal particle size distribution. The effects of the dimensionless numbers resulting from dimensional analysis on the packing density of a coal heap have been experimentally examined and analysed. Based on the experimental results, equations have been formulated for the estimation of the bulk density of a coal stockpile. The validity of these equations are checked by comparing the predictions with measurements of real industrial Stockpiles.

Jan 1, 1991

By Lownds C. M

Several classes of commercial explosives and blasting agents behave non-ideally, especially in diameters near their critical diameter. A direct and convenient measure of non-ideal behavior is the detonation velocity (VOD); if the VOD is less than the ideal value, usually obtained by calculation, then the explosive is detonating in the non-ideal mode. Such lowering of the VOD is usually due to both lateral loss of energy and post-CJ release of energy. The second of these factors, namely slow release of chemical energy, is of most interest in blasting. While the observation of a low VOD clearly suggests slow reaction of part of the explosive composition, it does not necessarily mean that the energy is lost to the overall rock-breaking process. The partition of the energy of the explosive into various useful and wasteful categories is considered. Simple models of energy partition in blasting, and of explosive reaction kinetics, are presented. The models consider the effect of explosive type and rock type, the explosive being described in terms of the most common phases namely liquid, air bubbles, porous ammonium nitrate, dense or crystalline ammonium nitrate, and aluminum. Over a range of combinations of the above phases, the model predicts reasonable critical diameters and VOD's. Results are presented which show the effects of non-ideal detonation on fragmentation and heave in different rock types. Conclusions are drawn about those blasting conditions in which ideal behavior is beneficial, or Disadvantageous.

Jan 1, 1990

In the 100 years since the formation of The Australasian Institute of Mining and Metallurgy there have been significant changes in all aspects of the mining industry.A number of the changes have been driven by technical evolution or necessity, others have been driven by developments in the application of the products produced from the mining of minerals. Other changes have been driven by shifts in community values.

Jan 1, 1993

The comparatively low winter rainfall, exposure to heavy salt laden coastal winds, and the consequent high evaporation rate, are important considerations in the rehabilitation of the Maslins Beach Sand Pit. The deficit of rainfall over evaporation is assessed at 1085 mm per annum. Such a coastal environment complicates the establishment of plants. The endemic flora found on the Sand Pit environs is mainly low wind-planed shrubs and mat plants. The dunes near the coast support an association dominated by Atriplex cinerea, Spinifex hirsutus, Scirpus nodosus, and Olearia axillaris. The coastal cliffs carry a more diverse vegetation dominated by Beyeria lechenaultii and Eutaxia microphylla. Overburden is used to develop a new landscape to screen operations, batter final faces, and cover rubbish at the nearby Council dump. The early overburden dumps were built with little regard for stability, but the more recent practice of using scrapers has resulted in more stable dumps. The erosion problems created by poor compaction have been controlled by contour banks, diversion drains, bitumen lined run-off drains, and hay mulching.

Jan 1, 1976

By Gee C. E

Ore reserves at the Kambalda Nickel Operations of Western Mining Corporation are estimated using the polygonal method for calculating areas of influence of drillholes. All raw assay and survey data are stored on one disk pack on the Company's CYBER 73 computer located in Perth, about 600 km from Kambalda. The initial step involving the computer is to search all assay data and calculate all potential ore-grade intersections. As the orebodies are thin, structurally complex and many are in close stratigraphic proximity, the selection of intersections which have the best grade over at least a minimum mining width involves complex logic. The orientation of an ore surface at each drill intersection point and a zone code are added to each intersection by the geologist from geological plans prepared for each ore surface. The orientation data together with downhole surveys enables the calculation of inter- section true widths and the zone code links each recalculated intersection to the appropriate ore surface.

Jan 1, 1977

Portable crushing at Duval Corporation's Sierrita open pit mine has proven both the economics and operability of large, hardrock, portable systems. In-house expertise was utilized to create a system incorporating both operational and maintenance features requested by operating personnel. The monitor/control system involves over 400 channels of information and is based on a DEC 1SI 11/2 microprocessor communicating with seven microprocessor-based data acquisition systems over a 4-wire, multidrop link. The year and one-half successful operation affirms the design philosophy and the hardware/software implementation.

Jan 1, 1985

By S Planeta

The use of explosives in underground mining has its drawbacks, particularly in the case of thin or narrow vein type deposits. Due to that, there is a need to develop more discriminative and safe rock-breaking technologies. Mechanical rock splitting seems to be one of the most promising avenues in this respect. This paper describes briefly principles and features of radial-axial splitters. It reviews a feasibility study done to evaluate a potential of this technology in selective mining. It was intended to compare productivity and cost of ædrill-splitÆ mining with conventional cut-and-fill method. Hypotheses and assumptions adopted, methodology used and the obtained results are presented and discussed. The study has confirmed an interesting potential of radial-axial splitters in mining thin and narrow vein deposits. In conclusion, it is stressed however, that it will take more R&D work to corroborate the results obtained. Some suggestions concerning future research in this field are also given.

Jan 1, 2003

By M Devia, J Rapkoch

This paper is intended to help design engineers, operating staff and plant managers understand the principles of metallurgical gas handling systems design. It also explains operating, safety and energy savings issues that the designer should take into consideration in the design of process off-gas systems for sulfide smelters. Primary smelting reactors, converters, and other off-gas sources impose challenging duty requirements on the various components of the gas handling systems. This paper reviews the design of common system components including the hood for gas capture at the system inlet, gas conditioning, gas cleaning, ductwork, dampers, hot gas fans, and the appropriate use of instrumentation and controls. The engineer must also be aware of how ductwork system effects and heat losses influence system performance. Also, the analysis of a recently-designed gas handling system will be reviewed, which includes high-strength SO2 gas from a smelting reactor, asymmetrically located Peirce-Smith converters, and a gas mixing chamber to mix the gases before they are sent to two acid plants of different sizes.

Jan 1, 2005

By Mitchell M. A

The steeply dipping Mammoth orebody is mined by Gunpowder Copper Limited using a sub- level uphole bench stoping method at a mining rate of 350 000 tonnes per year. of three per cent copper ore. Access to the mine, is provided by 1 in 9 decline which spirals in the footwall connect-, ing all the sublevels, thus maximising mobility and accessibility of trackless mining equipment Sublevels are driven in ore off cross- cuts from the decline every 15 metres vertic- ally. Sublevel drives are stripped out to widths up to 18 metres before cutoff slots are mined at each end. A two boom fan drilling jumbo is used to drill inclined rows of holes to the floor of the sublevel above. Two or three rows are fired at a time which allows broken ore and remnants from the level above to be mucked out by rubber tyred LHD equipment to the brow. Ore widths of up to 80 metres are en- countered at lower levels where ring drilling from longitudinal drill drives will break ore to a draw point system below. Development is carried out with three boom rubber tyred jumbos. All haulage from the mine is in 20 and 35 tonne rear dump trucks. All aspects of the mining operation are discussed including ventilation, pumping and drainage, services and future planning.

Jan 1, 1974

Callide Coalfields produces a sub-bituminous, very subhydrous, low rank, steaming coal with good combustion properties, primarily for domestic power generation. Geological input into planning of coal extraction requires expedient production of detailed structural, lithological, analytical, geophysical and geotechnical data. The CSIRO-developed SIROLOG borehole logging software and hardware system allows for detailed spectrometric analysis of coal/interburden. The gamma-gamma and neutron-gamma SIROLOG techniques both provide improved prediction of ash content over other borehole techniques. The neutron-gamma technique also predicts density and some important ash constituents (especially iron, alumina and silica). The software/hardware configuration allows for quick, easy interpretation of coal seam depth and lithology, parting thickness and ash/ash constituent contents immediately after a borehole has been logged. Within certain mine areas in the Callide Basin, the iron content of mined coal is widely variable in both vertical and lateral extent within and between seams. This variability creates problems in predicting the slagging behaviour of æas-receivedÆ coal during combustion, especially where the iron content of the ash exceeds 19 per cent. Using the SIROLOG tool in co-operation with traditional borehole sample laboratory analysis results, patterns in this variability can be determined and related to geological properties and process of formation of the coal seams. Subsequently, areas of high iron can be predicted in advance of mining. Since 1992, on-going collection and interpretation of SIROLOG downhole geophysical log data has significantly contributed to a number of research projects related to gaining a preliminary understanding of the iron distribution and formation during the Coal MeasuresÆ deposition. Because the probe was able to record variations in coal mineral matter content, it was found to complement more conventional techniques such as reflected light petrography, X-Ray Diffraction and SEM techniques that examine the mineralogy of iron species. Additionally, software has been developed to allow integration of SIROLOG data into existing geology databases, enhancing coal quality modelling and daily prediction of parameters such as raw ash, silica and iron contents that are indicators of ash fusion propensity. The correlation of SIROLOG-derived iron geophysical traces between drillholes and other sample points highlighted lithological and structural controls in the iron distribution in the sequence previously not detected. This work has allowed the development of a methodology for predicting iron in advance of mining and reconciling as-sold coal quality to that predicted. Predictions are currently being assessed at the coal face as mining progresses through high-iron zones.

Jan 1, 2000

By C Sylvestre

For the last 50 years, traditional safety management has improved safety performance by: • Fixing the environment (eliminating the hazard). • Improving the system (more/less rules, procedures etc). • Making safety more conscious (more/better interactions about the importance of safety). Although these approaches certainly have merit, and may be part of an overall solution, they are not enough to prevent many modern-day incidents. Today, these three approaches are used more than before, and are used better than ever before. Yet, workplace fatalities in Australia have stagnated from 2013 to 2019, as have the number of incidents, even serious ones. In the USA, workplace fatalities have increased by 15 per cent in the same period.

May 5, 2022

By J D. Tolley

The shift towards clean energy technologies is having a significant impact on the mining industry, with the demand for minerals such as copper, nickel, cobalt, lithium, manganese, and graphite increasing exponentially. To meet the goals of the Paris Agreement, mineral requirements for clean energy technologies would need to quadruple by 2040, and to achieve net-zero globally by 2050, mineral inputs in 2040 would need to be six times more than today. The most significant driver of mineral demand is electric vehicles (EVs) and battery storage, with lithium seeing the fastest growth, and copper demand doubling over the same period due to the expansion of electricity networks globally. The demand for these minerals is expected to rise significantly as investments in clean energy technologies continue to grow in the future. As the world moves towards a decarbonised economy, the minerals industry is under increasing pressure to reduce its environmental and social impacts and meet the increased demand for minerals. Mining companies are facing additional challenges due to the depletion of near-surface mineral deposits globally, with more mines transitioning from open pits to underground. The transition to underground mining requires the right strategy to economically access deeper mineable inventories and to keep up with future clean energy technology demands to achieve net-zero globally by 2050. One key way to achieve this is through decarbonisation using ‘green’ mining technologies such as replacing current primary diesel mining fleets with battery electric vehicles (BEVs). However, these measures through electrification overlook the bigger opportunity to maximise the socio-economic returns from the mine while also reducing the overall carbon footprint. Corporate cut-off grade policy is one of the most significant influencers on the total environmental and social impacts of the mining industry. The purpose of a corporate cut-off grade policy is to implement strategies aligned with achieving all the mining companies’ corporate goals, with decarbonisation targets becoming a primary driver for mining companies. Table 1 shows the evolution of cut-off theory with the increasing number of dimensions and driving inputs per iteration.

Aug 2, 2023

Some fundamental aspects of recent single-particle fracture studies are reviewed. Findings from this research shed new light on the utilisation of energy during comminution operations and provide useful pointers to new research directions that could lead to significantly better comminution machines. Two methods for quantitatively predicting mineral liberation during comminution are reviewed. These methods have been developed into useful practical procedures, but they are almost unknown in the mineral processing community. Their use should promote the consideration of mineral liberation as an important variable to be considered during the design and operating control of comminution circuits.

Jan 1, 1993

By Fitzpatrick JM

The feed preparation section of the Whyalla iron ore pellet plant includes a screening and crushing plant followed by dry grinding mills. Improvements in the efficiency of the vibrating screen and cone crusher have enabled screening plant throughput to be increased and product size to be decreased. This, in turn, has enabled improvements in the grinding mills' operation.

Jan 1, 1978

By Smith S. F, Terezopoulos N. G

This paper discusses experimental results of physical scale models employed to study the stability of a pillar between rectangular roadways. A programme of laboratory investigations utilising a bi-axial test rig has been undertaken to examine the influence of various stressfields on the stability of pillars between mine roadways. The effect of pillar height/width ratio on the overall stability is studied. Observations of failure characteristics in and around pillars are discussed especially in relation to the various stressfields applied to the models.

Jan 1, 1992

By G W. Wilson, C Panidis

Potentially acid forming (PAF) waste rock contained in dumps formed as a result of open cut mining of metalliferous orebodies are conventionally sealed or covered using a near-saturated, low permeability compacted clay layer, protected with a mulch layer and/or vegetated growth medium. The purpose of the compacted clay layer is to limit oxygen diffusion and the infiltration of rainfall into the dump. Where the aerial extent of the PAF waste rock dump is large, or where suitable clayey material is in short supply, it may be difficult to source sufficient suitable clayey material to form the cover. The paper describes a laboratory-based investigation of combining inert waste rock and tailings to form an alternative seal or cover material. The inert waste rock was sourced from the trafficked surface of a non-acid forming (NAF) waste rock dump, with a maximum particle size of about 100 mm. This was combined with NAF thickener underflow tailings slurry in various mass ratios, and the resulting mixtures tested for their particle size distribution, compaction characteristics, soil water characteristics (relationship between suction and volumetric moisture content), and saturated hydraulic conductivity. The mixtures tested ranged in consistency from those dry enough to be compactable, to those with the consistency of wet concrete that lend themselves to placement without the need for compaction. The laboratory test results showed that the suitability of the mixtures as seal or cover materials is very dependent on the particle size distribution of the mixture, with well-graded mixtures having substantial fines performing best.

Jan 1, 2003