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By M Davies, G Theletsane, A H. Gray

Recovery of gold from gold ores has been driven by the available technology and its configuration in the process plant flow sheet.Conventional practice in test work programs has the ore being ground fine (to 106 or 75 microns) to ensure liberation ahead of leaching or flotation. This paper identifies that, in many cases, gold and gold sulfide carriers will liberate and be recovered to a concentrate at much coarser sizes.There is an exponential increase in energy consumption relative to particle size reduction. This impact becomes extreme when comparing crushing a product to 1 mm against grinding to 75?microns.The resultant reduction in energy consumption when liberating and separating at 1 mm or coarser compared to grinding to 75 microns can be in the order of 15 kWh/t or 60 per cent of energy in the comminution circuit.Recovery of free gold and gold sulfide carriers by preconcentration (using continuous gravity devices such as the InLine Pressure Jig), combined with flotation of the fine gold and gold carriers, can result in significant power savings.There are multiple locations within the flow sheet that can be targeted using this process, including recovery in the cyclone underflow of existing plants, preconcentration ahead of the plant or complete greenfield, low-energy process plants designed from first principles based on data from a Gekko developed test work regime.We will describe the process of defining mineralogy in the laboratory and the decision-making process through to actual applications in the field.Several examples will be provided, including a South African Witwatersrand gold ore, several Australian gold ores and others, indicating the benefits of this process and where it has been brought to commercial reality.CITATION:Gray, A H, Davies, M and Theletsane, G, 2014. Coarse liberation and recovery of free gold and gold sulfide carriers for energy reduction in process plants, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 117–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By S McKinley

"The White Mountain sediment-hosted gold deposit is located in north-eastern China. Mineralisation is associated with silica–hematite–altered polymict breccias that occur within dolomite at or near the contact with overlying sandstone. Economic gold grades are controlled by the distribution of the polymict breccias and can transition rapidly to low or zero grade over short distances. This results in sharp and highly irregular ore contacts on whose accuracy proper stope design and ore control is reliant at this blasthole underground mine.Short-term planning and ore control utilise a grade control model created from infill drilling and grade control sampling (ie face and wall sampling). Typically, the grade control model was maintained by time-consuming manual editing of earlier made contacts to incorporate any new data. This approach also was quite error-prone due to: the complexity of the breccia and ore grade contacts irregularly oriented and/or insufficiently dense drill holes inconsistent incorporation of grade control sampling. These errors resulted in unplanned dilution and ore loss due to inaccurate interpretation of the ore contacts.The primary advantage to implicit geological models over conventional, manually-built wireframe models is that they can be updated very quickly and frequently. In a mine setting, the power and efficiency of using an implicit model is greatest where the use of manual inputs or editing can be minimised. Recently a workflow was set-up for the mine geology team to create an implicitly-modelled ore shape for short-term planning needs by using all data, especially all grade control samples. The resultant 3D shapes provided metre-scale accuracy and consistently reconciled complex ore geometries much faster and to a higher degree of quality relative to the wireframe model. The mine stakeholders can now obtain an accurate ore model that will always be in sync with available data.CITATION:McKinley, S, 2017. Application of implicit geological modelling to improve the grade control process at White Mountain gold mine, Jilin Province, China, in Proceedings Tenth International Mining Geology Conference 2017, pp 385–392 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 20, 2017

The last 40 years has seen a dramatic reduction in the prevalence of pneumoconiosis through improved mining engineering associated with continuing medical surveillance of those at risk. Presently the dust particle count standard is being correlated with gravimetric dust standards. Chronic Bronchitis and Emphysema are also coal mining related diseases. Methane is the commonest of a number of coal mine gases. Oxygen deficiency symptoms may result from high gas content of mine air. The explosive nature of methane-air mixtures is well known. Mine gases will always present a potential threat to safety.

Jan 1, 1983

By M J. Begbie, P C. Keall, M P. Simpson

The Golden Cross low sulfidation epithermal deposit occurs in pervasively altered andesite of the Waipupu Formation and in the Waiharakeke Dacite. The unaltered, post-mineral Whakamoehau Andesite overlies these units. The Empire zone of the Golden Cross deposit contains a stockwork which is currently mined by open pit methods, and a series of veins that are mined underground. Alteration envelops both the underground and open pit mineralisation. The core of the alteration zone contains silicification, as quartz veins, and adularia. Shallow portions of the system contain illite-smectite and a thermally unstable chlorite, tentatively identified as corrensite, which pass downward into illite and chlorite, respectively. Replacement calcite occurs widely throughout the altered zone; pyrite is nearly ubiquitous. This alteration assemblage indicates formation from near-neutral alkali chloride waters. A late, post-mineralisation alteration assemblage of calcite, smectite, illitesmectite, kaolinite and siderite presumably formed from weakly acidic, steam-heated CO2-rich waters.   We have identified eight stages of vein formation: (1) sulfide veins, (2) black veins, (3) massive veins, (4) banded veins, (5) thin white veins, (6) crumbly veins, (7) massive/platy calcite veins, and (8) flattened rhomb calcite veins. Gold mineralisation occurred relatively early in the lifetime of the system, dominantly during 2 through 4. The late calcite veins (7 and 8) and early sulfide veins (1) are barren.  

Jan 1, 1997

Sixty years after its inception, after an alternation of periods of admiration and rejection by the industry, Sampling Theory can now be seen as going through its golden age. A brief history of its successive transformations and progresses achieved by its author, Pierre Gy, and his followers, reveals the theoretical as well as practical difficulties that had to be vanquished to reach this point. Its current level of acceptance and corresponding trends are discussed and illustrated, with an insight on its increasing real role in the industry and future prospects for its further development.

Jan 1, 2008

By C W. Davis

Every diesel engine emits approximately 100 million nano diesel particles (nDP) per cubic centimetre of raw exhaust. Each nDP has a diameter of between 50 and 70 nano metres or 1/100th the size of red blood cells (diameter of between 6 and 8 microns). When inhaled, some nDP pass through the lungs and penetrate all body tissue [1]. Europe and North America have recognised and are addressing the long term health problems posed by nano diesel particulate matter (nDPM) across their societies [2.3]. Australia has been slow to recognise the issue, at both a societal and mining industry level. There are chronic health effects for every underground miner and serious legal issues for mining companies with increasingly stringent Occupational Health and Safety legislation being implemented at a state level across Australia. This paper will review progress within Australian society and more particularly the underground hard rock mining industry, particularly in Western Australia (WA).

Mar 15, 2021

By M Jones

Legacy tailings storage facilities exist within operating mine sites across Australia. These tailings storage facilities are often viewed as rehabilitation liabilities but with considered assessment may prove to be a resource. Extraction of such a resource might add value to operations by providing cash flow during the development of new mines; providing supplementary mill feed for existing mines undergoing step changes in operations; and supporting mine closure activities. Hellyer Gold Mines is successfully extracting and reprocessing sub-aqueous material from legacy tailings storage facilities at their Hellyer operation in north-west Tasmania. The Hellyer tailings storage facilities contain poly-metallic material from the Hellyer and Fossey underground deposits dating back to the 1980s as well as material from tailings reprocessing activities by other operators of the Hellyer site. Hellyer Gold Mines is reclaiming sub-aqueous material using cutter-suction dredgers and reprocessing on-site. Hellyer is the only operation of its type in Australia and few such operations exist worldwide. Key learnings around the estimation of a resource for legacy tailings storage facilities have been acquired at Hellyer that can be applied to the assessment of other tailings storage facilities. The application of dredging as a mining method at Hellyer is delivered through collaboration with experts from outside the mining industry under the direction of a mining engineer. Key elements required for the planning and delivery of safe and efficient dredging inside tailings storage facilities have been identified at Hellyer and are presented to provide a road map to the development of other dredging operations.

Sep 1, 2024

By J Planner

As Australia’s coal and iron ore export volumes increase to meet international market growth, port terminals, mining operations and rail transport systems can be the source of increased dust emission. Current and future sustainable expansion must minimise dust emission from bulk handling and transport operations located in close proximity to residential areas. Lower level dust emissions can be controlled by operational measures such as water addition to products, and use of water spray on stockpile surfaces. Recent research has shown that higher levels of dust emission can be more effectively controlled by understanding and treating the dust characteristics of each individual bulk product. Application of this research, progressively being applied at Australia’s coal and iron ore port terminals and rail transport systems, is achieving compliance with health standards and minimising dust nuisance effects to an acceptable level.

Nov 22, 2011

By S Henderson

The Otago Goldfield has produced approximately 8 million ounces of alluvial gold and over 2.5 million ounces of hard rock gold and is currently home to New ZealandÆs largest producing gold mine. In the eyes of explorers this production history makes the goldfield a good place to explore.   Modern exploration in the Otago Goldfield commenced in the late 1970s with the exploration for tungsten. However, a rapid rise of the gold price in the early 1980s saw the focus shift to the exploration for gold which lead to the discovery of the Macraes Gold Project in 1984, which since it came into production in 1990 has been New ZealandÆs largest producing gold mine. With the exception of the Macraes Gold Project, exploration continued in the Otago Goldfield for a further 20 years without further success.   In 2006, Glass Earth (NZ) Limited (Glass Earth) reviewed all the exploration technologies applied to the Otago region and available geological data, including the 1996 OceanaGold Helicopter Electro-Magnetic (HEM) data, and concluded that combined magnetics and HEM were able to delineate the Hyde Macraes Shear Zone (HMSZ) which hosts the Macraes Gold Project. Unlike previous explorers who explored the Otago region in a piecemeal manner, Glass Earth opted to collect a new, region-wide dataset which could be integrated with all previous collected geological information to come up with new exploration concepts and targets. As part of this process, Glass Earth applied in mid 2006 for New ZealandÆs largest on-shore gold Prospecting Permit, PP39-322 which was subsequently granted in November 2006. In mid January 2007, Glass Earth commenced acquisition of approximately 50 000 line kilometres of HEM data, making the Otago regional aerial geophysical survey (survey) the largest aerial geophysical survey ever undertaken in New Zealand.   This paper will report on the progress of the Otago Regional aerial geophysical survey and outline some of the preliminary findings from what is still a work in progress.

Jan 1, 2007

By M Haest, O Dominguez, D Mittrup

With the current focus in the mining industry on reducing costs, while simultaneously improving ore quality, infrared spectroscopy is a tool that can potentially assist companies to meet both challenges. Changes in the nature of infrared spectra are strongly influenced by changes in mineralogy, which is a key input variable for exploration (geology and orebody modelling and ore characterisation) and mining (pit design, mine scheduling and processing plant design/management).Infrared spectroscopic logging of drill holes has been embedded as a standard tool in BHP Billiton Iron Ore exploration, with a process set up to automatically deliver mineralogy and associated imagery to the end users (typically exploration geologists). The availability of consistent and automated mineralogy drill hole logs across a project is improving the output quality and reducing re-work.BHP Billiton Iron Ore is now looking into using the same infrared spectroscopic data for other applications, including improving predictions of geometallurgical and geotechnical parameters. Trials show that addition of infrared spectroscopic data to conventional data sets (element analysis and depth information) is significantly improving the accuracy of regression models to predict the lump-fine ratio.Further initiatives around infrared spectroscopic data in BHP Billiton Iron Ore include the installation of infrared spectroscopic sensors over conveyor belts, infrared spectroscopic mine face scanning and infrared spectroscopic blasthole logging. The ultimate vision is to have consistent, seamless mineralogical data from infrared spectroscopic sensing available throughout the mineral value chain (exploration/mining/processing). This seamless infrared spectroscopic data ‘bridge’ will allow the transfer of knowledge between the different sections of the value chain (exploration, mining and processing). For example, ore handle-ability could be predicted on exploration samples using regression models built from processing plant observations. In the opposite direction, information gathered about the buried stratigraphy by infrared spectroscopy utilised during exploration, could be used to predict the stratigraphy encountered during mining. This collaboration across BHP Billiton Iron Ore is expected to deliver significant savings, while improving the quality of the final product, thus helping to drive efficiency over the next decade.CITATION:Haest, M, Mittrup, D and Dominguez, O, 2015. Reaping the first fruits – infrared spectroscopy: the new standard tool in BHP Billiton Iron Ore Exploration, in Proceedings Iron Ore 2015, pp 277–284 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By N Burgio

Block cave mines are often thought of as rock factories where high volumes of production are mined from a fixed area suggesting little requirement for geological input and control. Yet caving operations have peculiar and specific technical requirements from prefeasibility through to post-mining reconciliation. Whilst essential elements such as resource definition, geological interpretation and sampling strategies are common to all mining methods, planning for a block cave requires a different emphasis and philosophical approach in how we deal with these issues. We will examine why a geoscientist’s input is critical towards the successful planning, design and monitoring of a caving operation.

Aug 22, 2011

By C D. Pocock

Maintaining catch berm capacity in open pit mines through controlled blasting prevents production delays associated with managing risks associated with wall instability. A method has been developed to quantify the drill hole deviation of presplit holes at Century Mine. Different controlled blasting techniques are used to control wall quality and decrease the risk. The performance of presplit drilling, in terms of deviation from design has been investigated. A methodology has been developed to quantify the drill hole deviation in three dimensions. This methodology was converted into a series of algorithms capable of handling an extensive range of data. The methodology was applied to a case study at Century Mine to evaluate the performance of drilling on two presplit blasts. Overall, 67 drill holes were investigated in the case study. The drill hole deviation was quantified in terms of three parameters: skewness, linearity and drill hole deviation parameter. Methods for quantifying each parameter were developed. Skewness, a measure of the amount of curvature and linearity, was defined as the measure of the consistency of the gradient of the drill hole. Drill hole deviation parameter is defined as the average measured deviation of the surveyed drill hole position from the design position. Acceptable drill hole deviation tolerances for each of the defined parameters were developed by analysing drill hole deviation parameters with respect to implications to catch berm capacity. Verification of the methodology was confirmed through the comparing of the completed drill hole deviation results using both visual inspection and cross analysis for each of the three methods. Holes with an R squared value of less than 0.97 for skewed deviation were classified as having skewed deviation, while holes with a difference in gradient of 3.5 were classified as having linear deviation. The results show that 76 per cent of the drill holes had deviation. Of this, 19 per cent were skewed, 57 per cent had linearity and 12 per cent contained both skewed and linearity deviation.

Nov 8, 2011

By T Takayama, R Muroi, M Matsumura

The steel industry occupies 14 per cent of CO2 emissions in Japan, and the sintering process is one of the major emitters. Since most of CO2 released from the sintering process comes from coke fine combustion, replacement of coke fines with biomass char as bonding agent is a potential countermeasure. In order to explore the effective use of biomass char, we chose char made from Palm Kernel Shell (PKS) as a sample. First, the char’s combustion behaviour was examined with varying the char’s particle size by means of admixing the char in alumina ball packed bed placed in an electric furnace. As a result, the finer the PKS char the faster the burning rate and reaching a higher temperature compared to coke fine. In addition, it is also concluded that the optimum size of PKS char was larger than coke fines. Next, the effect of different heat profiles on sinter structure was examined by sintering tablet made of chemical reagents. In this experiment, the chemical composition is designed based on sinter composition. By this sintering test, even at high temperature, rapid cooling is effective to make fine sinter matrix and fine pores, which has possibility for high sinter reducibility. Based on these two experiments, using PKS char as a sinter fine source has the possibility to improve sinter reducibility.

Nov 8, 2021

By R J. Wood

Raise drilling (or raise boring) is not a new technology or methodology. The first raise drilling machine was developed by The Robbins Company (TRC) of the USA in 1962. TRC manufactured the first tunnel boring machine (TBM) in 1952 and Jim Robbins, the founder of the company wanted to ‘turn the TBM concept on its head’ so to speak.Many improvements have ensued in the 50 years since the first machine. Such improvements include advances in the drill rod and thread design, cutters and reaming heads. Raise boring would not have been possible without the development of the tungsten carbide insert cutters and there have been big advances in both the carbide technology and in the mechanical design of the cutters.Over time mines have developed deeper with a greater use of diesel equipment resulting in greater ventilation requirements. This in turn means larger and deeper ventilation shafts. There have also been improvements in directional drilling techniques. This all combines with the need and ability to construct larger shafts using the safe method of raise drilling. With suitable geotechnical conditions the RBR900VF is capable of drilling shafts to a diameter and depth of greater than 8 m and 2000 m respectively. Greater diameters are possible over shorter lengths with suitable ground conditions.The RBR900VF was designed and manufactured to specifications developed by Macmahon. This machine has the greatest thrust and torque capability of any machine in the world. It enables cutters to be more heavily loaded in the larger diameter heads and this is essential for efficient rock excavation. Additional features of the new machine include minimal manual handling to provide a safer working environment and higher strength steel for the drill rods providing additional safety margin.CITATION:Wood, R J, 2014. A revolution in raise boring – the development of the RBR900VF, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 171–178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By V Pfannenstiel

The United States (US) coal mining industry has been working under comprehensive planning, operating and rehabilitation regulatory requirements for nearly 35 years. The public desire for environmental protection during mining and rehabilitation following mining to achieve post-mining land use and sustainability goals has been a major factor and continues to influence the process. Mining companies have evolved operations to achieve outcomes that address the desired goals and regulatory requirements cost-effectively and successfully. Over the 35 year regulatory period, requirements for more diverse topography, specialised revegetation communities, landform stability and assured sustainability have increased and become more complex. These challenges are effectively met by maximising integration of mine planning and operating with the rehabilitation process. Rehabilitation is then implemented in a more timely and efficient manner and with effective results that achieve desired outcomes, commonly with added value. Peabody Energy (Peabody) has taken this approach in its US operations and this paper discusses an integrated approach and illustrates learnings and results with examples from several of its western US operations.CITATION:Pfannenstiel, V, 2012. Integrated planning, mining and rehabilitation for effective results and sustainable land use - A western United States perspective, in Proceedings Life-of-Mine 2012 , pp 219-232 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By P Lukic

The definition of the working sections that will be used in a mine is usually initially made in the field by the geologist supervising the drilling program. These initial definitions are often made on the basis of rules of thumb such as æcoal less than 30 cm thick cannot be mined separatelyÆ; æpartings more than 30 cm thick will be mined separatelyÆ; and æif a coal seam is less than 50 cm thick and the parting above or below is thicker than the coal, the coal will be wastedÆ. These decisions are also often made based on the requirement for a minimum sample mass for analysis, and the desire to collect data at the minimum resolution to conserve the exploration budget.In many cases the geological models based on this data are produced at a resolution that is inadequate to allow the mining engineer to produce a mine plan that will maximise project value. This problem is generally unrecognised.Where data is collected to a higher level of resolution the subsequent processes employed in the production of geological models and mine plans often discards the inherent value that is hidden in this data. Again this problem is generally unrecognised.This paper highlights this problem and then presents a methodology that ensures that the optimal working section is selected and compares the outcomes of applying this methodology versus adherence to the usual rules of thumb.

Sep 26, 2011

By T Baard, A Pieters

This paper deals with the design and implementation of a 17 MW (nominal) surface cooling installation at Impala Platinum No 14 shaft located in Rustenburg, North West Province, South Africa.The cooling requirements included the installation of a surface ammonia refrigeration plant complete with the storage of hot and cold mine service water for underground use. It was also necessary to install a surface bulk air-cooling facility, which cools 400 kg/s of ventilation air going to the underground workings. Primary cooling is to the surface bulk air cooler. The cooling duty of a surface bulk air cooler is heavily dependent on the ambient wet-bulb temperature. Because of the daily wet-bulb temperature variation in this part of the world, use was made of a cold thermal storage facility of four million litres. The excess chilled water is stored during the night, for use by the main drilling shift during the day. This keeps the refrigeration machines as close as possible to full load during the summer, thus maximising the use of the capital expenditure. This paper discusses the control philosophy used to maximise the cooling output, as well as the thermal process. The project consisted of two phases resulting from the underground development phases of the mine. The first phase started in January 1999 and was commissioned by the end of the same year in record time. The final commissioning of the second phase took place at the end of 2002. The most difficult part of the construction phase was the tunnelling of a subsurface air duct from the bulk air cooler to the operating vertical shaft. This was done without disruption to the hoisting of men, material and ore in the shaft. Owing to the size of the refrigeration machines, the ammonia quantities involved and the application on a mine (no ammonia can go underground, either in the service water or in the mine air) special precautions had to be taken. South Africa has developed high standards for ammonia refrigeration plants used on mines, which will be partially dealt with in this paper.

Jan 1, 2005

Australia as a leading producer of mineral sands has also occupied a leading position in many areas of research'in the processing and applications of these minerals. Research in upgrading ilmenite to produce synthetic rutile has resulted in the develop- ment of many processes, e.g,., Becher, Murso, Chlorine Technology, and ICI processes. Studies on the reducibility of ilmenites, aqueous leaching of reduced ilmenites, Fe-Ti-O system, leachability of natural and treated ilmenites in hydrochloric acid and selective chlorination of iron from ilmenites have been carried out in order to develop and improve the efficiency of the above processes. While research on the processing of zircon sand to produce high purity (99.99% ZrO2 zirconia powder and zirconium chemicals started only recently, research by CSIRO in the early 1970s led to the discovery of the phenomenon of transformation toughening in partially stabilized zirconia (PSZ) ceramics. Australia, with very significant resources of lanthanide-containing ores, pro- duces substantial quantities of monazite each year but research in processing and appli- cations of rare earths was neglected in recent years in this country. However, research to improve processes for the recovery of rare earths is now under way and studies on the production and testing of Nd-B-Fe magnets which are 1.5-2 times stronger than the strongest magnets (Sm-Co) currently available, have also commenced.' An overview of the research in the pro- cessing and applications of mineral sands during the last two decades in Australia and its implications for the industry are pre- sented in the paper.

Jan 1, 1986

By B B. Beamish

Long-hole directional drilling for in-seam exploration was introduced to New Zealand at Huntly West Mine in 1989. Following the success of this initial drilling program the Coal Corporation of New Zealand (CoaICorp) purchased its own drilling equipment and proceeded to adopt the technique with in-housetraining. From July 1991 to September 1992 a total of 15 455 metres was drilled at Huntly West Mine. During this period several modifications were made to the drilling technology to suit the ground conditions. The resulting interpretations of the drill information enabled reliable seam definition to be incorporated in mine planning. Since January 1993, the technique has been transferred to the Huntly East Mine to assist with seam definition for the planned development westwards under the Waikato River. The benefits of this drilling technique to coal mine planning are now well documented in Australia and New Zealand as well as other overseas countries. The possibilities of adapting the long-hole drilling technique to hard rock applications has been illustrated recently with successful cross-measure drilling at Huntly East Mine.

Jan 1, 1993

Experimental Study of Ore Characterisation Methods for AG/SAG Mills Mining companies have long recognised the importance of ore breakage characterisation in design and optimisation of their crushing and grinding circuits. In one of the industry standard methods relevant to AG/SAG milling, ore is characterised using mainly high energy single impact tests. However recent DEM studies have suggested that breakage in AG/SAG mills is mainly due to low energy repetitive (or multiple) collisions rather than single high energy impacts. Hence a study was initiated at the JKMRC to investigate the behaviour of ores under such conditions. Carefully designed experiments have been performed using two laboratory mill sizes (0.6 m and 1.1 m diameter) to mimic the reported low energy repetitive impact breakage under low load conditions. The breakage characterisation parameters derived from standard high energy single impact tests on the same ores was then used to predict the low energy repetitive impact breakage. Significant bias was found in the simulations which clearly warranted further investigation. The extensive experimental program which followed employed three separate methods: the JKRBT (JK Rotary Breakage Tester) for high energy single impact and low energy repetitive impacts, gravity drops for low energy repetitive impacts, and laboratory mills to provide an extended number of low energy repetitive impacts. The breakage energies associated with these experiments were accurately measured with a high speed video camera. Two breakage indices, the degree of breakage (t10) and the breakage probability (S) were used to describe the breakage test results. This paper summarises the major results from this experimental study, which has facilitated the development of a new breakage characterization method relevant to AG/SAG mill modelling.

Sep 13, 2010