Search Documents

By Wang J, Ma Y, Jia H

The Hedong Gold Mine is located in the Yan(ai area, tihandong hroo%ill, e. China. It is an underground mine with an annual gold output of some 700 0(H) grams. The orebody is located on the edge of the Wanger Shan metamorphism zone, and the hangingwall of orebodies is thus defined by a prominent set of fractures. The proximity of the metamorphism zone and the inclusion of the fracture set ensure that both the orebody and the country rocks are unstable. The main orebodies dip at an angle of between 40 to 45¦, with a strike length of 160 metres and a horizontal width of 50 metres. Surface subsidence in the area is not permitted. Cut and fill mining is usually practiced. As the mining operation proceeds to greater depths, the ore grade is diminishing and it is necessary to find a more efficient stoping method. Sublevel open stoping with sequential extraction and filling of each sublevel has been designed and applied in situ. This new mining method is called 'sublevel open and fill stoping method' in the mine. Experience to-date is that new mining method is Satisfactory.

Jan 1, 1998

By V Yadi

Geostatistics has been widely used for more than four decades as a powerful tool in ore resource/reserve estimates and grade control. This method has gradually replaced the conventional method such as polygon and cross-section for grade estimation by more mathematical techniques such as kriging. The advances in geostatistical understanding and the availability of appropriate software packages have given much more contribution in speed and high accuracy during production. However, in many cases, these techniques are sometime applied without support with a good thorough understanding of the geological controls on metal distribution. To produce the result close to actual, the geological control in interpretation and appropriate geostatistical task is a must. Geological logging was described in the core must be consistent with the level plan produced by commercial modelling software used as a guide for grade control during production. Experience gained through evaluation of the Central I deposit resulted that the most effective systems continue to be based on geostatistical methods of resource estimation. Computer applications modelling software packages are necessarily as the core of an efficient in undertaking these assignments. They contribute to make a valued to data management and are becoming increasingly effective during processing. The latter role is particularly important to check the actual versus estimated values where will significantly to improve personnel to have a confident with their knowledge combined with experience and complete their jobs satisfy.

Aug 22, 2011

During operations, mining and metallurgical processes may generate effluents such as tailings water, acid mine drainage (AMD) and seepage and process acid streams. Depending on the type of ore and the metallurgical process, these effluents may contain one or more toxic compounds (eg acidity or alkalinity, cyanide, ammonia and/or nitrate, heavy metals, total suspended solids (TSS), sulfate) in elevated concentrations requiring treatment before their discharge to the environment or recycle/reuse in the process. Natural oxidation of sulfide minerals present in mining wastes (eg tailings and waste rock) at mining sites may generate AMD, which is characterised as a low pH, high acidity effluent containing heavy metals and sulfate. If generation of AMD cannot be controlled and/or prevented, AMD needs to be collected and treated for neutralisation of acidity and reduction of metals and TSS to meet regulated water quality standards. It is important to note that some of these compounds may persist in run-off from mine sites, even after the mine and processing facilities are decommissioned. Treatment of mining and metallurgical process effluents can be accomplished by means of various physical, chemical and/or biological methods. The mode of process application may vary from the use of either specifically designed, controlled and automated facilities or passive systems. Lime neutralisation and precipitation is the most common method used in the mining industry to treat AMD. To reduce the problems associated with disposal and long-term storage of the resulting sludge, the use of a high-density sludge process (HDS) has become a preferred option. The use of other chemical reagents, waste or by-products from other industries, and biological sulfate reduction methods can also be considered as viable options for site-specific situations. Recently, several passive treatment systems have been designed and successfully operated, even in the cold North American climate. This paper will discuss available options and provide insights for selecting a suitable method for a given situation using case studies from projects conducted by Golder Associates around the world over the last decade.

Jan 1, 2006

By W D. Rech, K W. Keskimaki

As an integral part of the conversion from rail haulage to conveyor haulage at Henderson, over six kilometres of drifting and several large complex openings were mined. The deepest of these areas was nearly two kilometres beneath the surface, bringing all of the challenges of rock stress and heat that come with mining at these depths. Though many mines operate at these depths, the development of the infrastructure necessary to support a 36 000 tonne per day caving operation brought some unique challenges to the development mining activity. The issues handled include: finding experienced staff for a æfast trackÆ development program; rock bursts and ground conditions; inflow of 50 degree centigrade water; acceleration of the project completion; large diameter raise boring and difficult muck handling.

Jan 1, 2000

By P Stoker

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Mining and exploration properties have a unique set of technical risks. Privately-owned companies considering investing in the resources sector can optimise their investment decisions by adopting a systematic technical assessment of acquisition assets, similar to the approach commonly adopted by public financial institutions and publicly-listed companies.Technical due diligence provides a process to identify key geological, mining, geotechnical, metallurgical, environmental and social risks and opportunities and determine the most likely business case and valuation of assets. Technical due diligence is commonly carried out in parallel with legal, commercial and financial due diligence, often involving the acquirer, to maximise the understanding of the investment.There are significant advantages in investors conducting a comprehensive technical due diligence, which typically involves site visits and project assessment to international standards by an independent, multidisciplinary team of experts. The outcomes provide the opportunity for the investor to make early, informed decisions and to understand and manage risks.Technical due diligence may be carried out at several stages: when considering and weighing up a number of investment options, prior to and during a transaction or immediately post-transaction. In the first stage, the outcomes will inform the choice of investment and, more particularly, whether there are any fundamental flaws in the projects being considered. In the second stage, due diligence outcomes can inform the level of investment and approach to risk management and planning. In the third stage, risks and opportunities can be investigated in more detail, allowing the investor to consider the best options to reduce risk and maximise the benefit of the investment.This paper presents a summary of the technical due diligence assessment process, its benefits to investors, common risks in mining and exploration projects known to cause mining asset write-downs and principal technical due diligence approaches.CITATION:Keogh, A, Stoker, P and Thomas, M, 2015. Benefits of due diligence in private equity mining investments – maximising value and unearthing common risks , in Proceedings PACRIM 2015 Congress, pp 115–126 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By R Dunne, G Lane, S Ha, D Dreisinger

The paper outlines the 17 Mt/a Telfer Project plant process design from sample selection to feasibility study design. The 366 Mt Telfer mine reserve consists of a diverse range of copper and gold mineralisation, from massive sulfide reef ores to stockwork ore, oxide copper minerals to chalcopyrite, siltstone to competent quartzite, all with relatively high levels of gravity recoverable gold. The complexity of the orebody demanded a flexible plant that could recover copper and gold values by a combination of gravity recovery, flotation and concentrate leaching. The demands of treating ore from a high grade underground mine and a variable grade open pit (that includes underground old mine workings) necessitated a dual train approach from primary crushing to concentrate production in order to minimise the requirement for campaigning of different ore types. An extensive sampling, testwork and technical evaluation program was undertaken to identify processing characteristics and the optimum process route for each ore type. The design experience included: the development of robust primary stockpiling and pebble crushing concepts; detailed review of scale-up of SAG and ball mill pilot plant data to plant scale; the selection of two 15 MW SAG mills and two 13 MW ball mills for the grinding circuit; and detailed modelling of the pyrite concentrate carbon-in-leach (CIL)/sulfidisation acidification recovery thickening (SART)/acidification volatilisation recovery (AVR) process to optimise design for copper and cyanide recovery from leach liquors. The Telfer plant design also measures the development of process design based on experiences at the Cadia Hill Cu/Au concentrator, commissioned in 1998. The differences between the two plants are compared and contrasted.

Jan 1, 2003

By T J. V Duffy, L H. D Siahaan, P G. Albert

G-ResourcesÆ Martabe Mine in North Sumatra, Indonesia, is a US$700 M world-class and world-scale operation in a country which, with a few notable smaller scale exceptions, has had no significant hard rock mining development in more than ten years.The mine was commissioned in the middle part of 2012 and poured first gold on 24 July. At full production Martabe will produce 250 000 oz/a of gold and 2 - 3 Moz/a of silver at cash costs in the lowest quartile. The mine location is on the west coast of North Sumatra, which experiences annual rainfall of 4 m with no notable dry season, adjacent to seismically active fault zones, and relatively close to a rural community of 31 000 people with no significant industrial experience.The management team has successfully forged strong links with the various government departments and levels in Jakarta, North Sumatra Province and the local Regencies; developed long-term relationships with the various community groups within the local district of Batangtoru to build a sustainable social licence; has dealt with the physical and environmental challenges presented by the project location, and has successfully raised more than US$900 M over a period of three years for the original acquisition then the development of the project.Whilst in its infancy of operation, the mine is set up to deliver a long-term sustainable future for the company, the shareholders, and the people of Batangtoru and all stakeholders generally. The quality of the project execution and commitment by the company will ensure that maximum value can be delivered from Martabe, not just for the current mine life but from the significant exploration potential that exists on the large tenement area that the company has access to for 30 plus years.This paper will deal with the physical challenges associated with the design, the Indonesian government regulatory requirements for mine development, the social aspects of building a world-class project in a developing area, the in-country commitment necessary for any project development anywhere in the world and the successful funding arrangements for the mine development.CITATION:Albert, P G, Siahaan, L H D and Duffy, T J V, 2012. Building AsiaÆs latest hard rock mine, in Proceedings International Mine Management 2012, pp 189-204 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By Grady B. V, Ault A. R, Newman O. M G, Fraser R. J, Malcolm J. McPhersqn

In all electrolytic zinc plants cadmium is removed as an impurity prior to the zinc electrowinning stage of the process. Cadmium metal is the favoured form of this by-product and most plants use an electrolytic route for its production. The formation of dendrites in cadmium electrowinning processes is the major limitation to deposition rates. There is an economic incentive, therefore, to better understand the factors affecting their growth. A technique that has been used by others to examine fundamental aspects of dendrite growth has been applied to industrial strength electrolytes. It involves potentiostatic deposition in a cell containing the electrolyte of interest. The variation in the current with time at a given overpotential allows the determination of the dendritic growth induction time. A method was developed (the Locus method) from the investigation of a set of such potentiostatic curves, obtained over a range of applied overpotentials, that appears to give a measure of electrolyte quality with respect to dendritic growth in galvanostatic deposition. The Locus technique predicts that zinc at industrial concentrations in cadmium electrolytes should have a significant effect on morphology and that deterioration of morphology will occur as the zinc concentration in the electrolyte is increased. This effect is consistent with literature prediction and was shown to relate to a reduction of the diffusion limiting current density. Magnafloc R333 is used as an additive at Pasminco Metals-EZ to control the morphology of cadmium deposits and the Locus method was successful in predicting its dendrite inhibiting properties. A possible mechanism is discussed. This work has opened avenues for future research with respect to a technique that may have an industrial application in electrolyte characterisation and has pointed to a direction in which better understanding of galvanostatic dendritic growth may be found.

Jan 1, 1993

By A Mooney, J Marsden, H Grosser, G Dunstan

Carrapateena is a copper-gold deposit hosted in a brecciated granite complex, located 500km North of Adelaide, South Australia. The deposit is being mined using the Sub Level Caving (SLC) Mining method at a rate of 4.25 MTPA. The Carrapateena SLC construction was completed in Q4 2019, with ramp up to a mine production rate of 4.25 MTPA completed within 12 months; ~ 6 months earlier than originally planned (OZ Minerals, 2020b). Traditional SLC designs have had issues with safety interactions on production levels, namely at the perimeter drive, as well as presented challenges for the application of automation due to frequency of activity required to achieve ring turnover rates. Safety in design provides an opportunity to learn from experience at recent modern SLC operations and by considering hazards early in the design process minimise exposure and improve safety, productivity and automation of mining activity. This paper discusses the work carried out during the Carrapateena feasibility study and optimised during project execution; to update the SLC production level mine design, with a layout known as the Carrapateena Crows Foot Level Layout. This paper focuses on: • An introduction to the Carrapateena Operation and mine plan. • An overview and historical challenges of traditional level layout. • An introduction to the Carrapateena Crows Foot level layout, including production level design parameters as well as development metres and productivity comparisons. • Outlines the benefits of the Crows Foot design for safety in design of SLC operations. Provides a roadmap for improved production efficiency, level operational philosophy and the application of automation within the SLC.

Mar 15, 2021

By Butler I. K, Nicholson P. M

There are four main types of base metal and gold mineralisation recognised in the central Pine Creek Geosyncline. These are stratiform, polymetallic veins, stockwork/concordant gold-quartz veins and unconformity related uranium-gold-platinoid mineralisation. The stratigraphy of the central Palaeoproterozoic Pine Creek Geosyncline has been simplified into three groups comprising the Batchelor, Frances Creek and Finniss River Groups in ascending order. Stratiform mineralisation occurs within the Frances Creek Group. The earliest mineralisation is found adjacent to circular faults ringing basement highs. Higher in the stratigraphy, stratiform mineralisation is often associated with zones of high compression in the vicinity of basement highs. A synsedimentary-diagenetic origin for stratiform mineralisation is proposed. Polymetallic vein mineralisation occurs within the Frances Creek and Finniss River Groups. Its composition changes systematically through the stratigraphy similar to the stratiform mineralisation. The mineralisation is structurally controlled and usually occurs in the vicinity of basement highs. Stockwork-concordant gold-quartz vein mineralisation is hosted by the upper Frances Creek and Finniss River Groups. It occurs within compressional zones and along the Pine Creek Structure corridor around, above and particularly between basement highs. Mineable reserves occur in thick continuous semi concordant quartz-sulphide veins and/or stockworks. Unconformity related uranium-gold-platinoid mineralisation shows a close spatial relationship with the Palaeoproterozoic/Mesoproterozoic unconformity. The mineralisation is localised by structures formed during Mesoproterozoic deposition and is commonly adjacent to Archaean basement or its remobilised equivalents. The type of mineralisation (stratifom/polymetallic vein) is a reflection of local stress regimes, structure and physio-chemical conditions. An initial phase of stratiform mineralisation is postulated to have occurred with the first significant marine transgression in a tensional regime. A second phase occurred later during a compressive regime. "Ihermochemical sulphate reduction of mineralising fluids by hydrocarbons is invoked as the precipitation mechanism for the polymetallic vein type of mineralisation. Hydrocarbon generation is postulated to have occurred within the Frances Creek Group, in many places contemporaneously with the movement of mineralising fluids and basin compression. Polymetallic veins formed from the interaction of mineralising fluids and hydrocarbons which were trapped in suitable structures. An abundant, continuing supply of hydrocarbons was necessary to form significant deposits. Where these conditions were not net, the mineralising fluids largely continued their ascent to the near surface environment to form stratiform deposits. The stockwork/concordant gold-quartz vein mineralisation is a later event and occurred during the relaxation of compressional defonnation after deposition of the 1-inniss River Group.

Jan 1, 1994

By A Remes, A Dennis, M Talikka, T Kotiranta, S Horn

A mine project combines vast amounts of information from various disciplines including but not limited to geology, mining, metallurgy, technology, environment and economics. In many cases, all relevant information is not fully shared between all disciplines. Thus, project performance (technical, economical and sustainability) may be evaluated on basis of insufficient information resulting in non-optimal decisions, project execution and risk management. Advances in computing power and simulation software enable various data sets to be incorporated in a single digital platform enabling more efficient and transparent data sharing. In addition, linked data sets and simulation can support assessment and optimization of the project as a whole rather than focusing on optimization of individual events. CITATION:Horn, S, Remes, A, Kotiranta, T, Talikka, M and Dennis, A, 2018. Evaluation of sustainability of copper production value chain from ore to metal using advanced simulation, in Proceedings Life-of-Mine 2018, pp 87–89 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By M J. Nimmo

extremely powerful tools for building predictive and generative models. ML can be used for building highly accurate regression and classification models. But without careful data science and statistical analysis, a regression or classification model could be highly biased and completely wrong – and we may not even realise. An example rock density estimation task will be used to illustrate the potential gains and possible pitfalls in using ML and AI in Mineral Resource estimation. What could possibly go wrong? Nothing! For most simple regression or classification problems, very little. For density estimation, using the global mean may be all that is possible, but the resource classification would need to reflect the uncertainty in global estimation of tonnage. Everything! From data collection and measurement, from selecting ML and AI techniques and designing the analysis workflow to our own cognitive bias. The things that could go wrong are vast and may include but not limited to asking the wrong question, not asking questions, data bias, measurement errors, insufficient data coverage, not collecting the right variables, not collecting enough observations, collecting clustered samples, unbalanced data, filtering out data without reason (outliers), clipping data (outliers), relying on automatic feature selection, including irrelevant variables, excluding relevant variables, geological interpretation, changing context, blindly following best practice, splitting small data sets, subsetting large data sets, using the wrong tool for the task, insufficient budget to complete the analysis, not allowing enough time for testing and experimentation (the science), focusing too much on building the model (the engineering), not learning from the data, our assumptions, our preconceptions, and our skill. This paper will explore the question of how training regression models to predict rock density are affected by gaps in the data (missing observations and missing variables). What could possibly go wrong?

May 24, 2023

By K Haga, G Danha, A Shibayama, L L. Godirilwe

The hydrometallurgical separation and enrichment processes provide an effective way to selectively recover metals from relatively dilute multicomponent sulfuric acid leach solutions. The multicomponent leach solution utilised in this study contained 0.3 g/L Cu, 0.34 g/L Ni, 0.13 g/L Co, and 2.96 g/L Fe, which was obtained after high-pressure oxidative acid leaching (HPOAL) of the copper-nickel smelter slag. The solvent extraction (SX), precipitation, and xanthate complexation processes were employed to recover and upgrade Cu, Ni, and Co from the leach solution. Batch SX tests were carried out using a countercurrent two-stage mixer settler extraction column, and LIX 984N (10 per cent v/v) as a copper extractant. Fundamental parameters influencing the extraction process such as pH, mixing speed, H2SO4 concentration, and organic/aqueous (O/A) phase ratio were investigated. For copper enrichment in solution, a combination of two extraction stages and two stripping stages were employed. Copper was successively separated from Fe, Ni, and Co under optimised extraction conditions (pH 2, 400 rev/min, O/A 0.25, and 20 min contacting) and stripping conditions (175 g/L H2SO4, 400 rev/min, O/A 4, and 20 min contacting). About 97 per cent of copper was extracted with low co-extraction of Fe, Ni, and Co of about 5.90 per cent, 1.47 per cent, and 2.53 per cent, correspondingly. A final Cu-rich solution containing 23 g/L Cu was obtained with a very low Fe concentration of 0.05 g/L. Additionally, for iron removal from the Ni/Co raffinate solution, more than 99 per cent of iron was precipitated at pH 4 by the addition of a calcium carbonate (CaCO3) suspension, with low co-precipitation of nickel and cobalt of around 3.68 per cent and 2.27 per cent, respectively. Furthermore, about 83.6 per cent of nickel and 99.4 per cent cobalt were co-precipitated from the solution by potassium amyl xanthate (PAX) solution at pH 6. The Ni and Co xanthate complexes were thermally decomposed and recovered as cobalt oxide (CoO) and nickel sulfide (NiS) solids.

Aug 24, 2022

By Y Shougu

Many mine accidents will affect the mine ventilation system when they occur. At present, there is a lack of monitoring means to capture the occurrence of accidents in time by monitoring the ventilation system, so as to take emergency measures to reduce the loss of personnel and property. Pressure wave is an elastic wave existing in air. Most accidents in mine will cause obvious changes of pressure wave. It is an innovative idea to monitor the occurrence of accidents in mine by measuring pressure wave. The development and functions of the pressure monitoring device and related software are introduced in detail. The pressure wave monitoring test is carried out in San Xavier underground mining laboratory, and the D-wave and S-wave waveform data are collected. The waveform characteristics are analysed, and the main frequency distribution of the pressure wave is found to be within 1 Hz by using FFT. At the same time, the influence of the propagation distance of the pressure wave on the waveform is analysed. The propagation velocity of D-wave and S-wave are roughly calculated, and they are 279.6 m/s and 397.3 m/s respectively. S-wave is slightly faster than D-wave. Although there are errors and uncertainties in the test, the test verified the feasibility of the existence and collection of pressure waves in the ventilation roadway, and provides a method for the future study of the propagation of pressure waves in the mine ventilation system.

Oct 12, 2022

By A G McLean

This paper will first discuss the fundamental requirements for reliable discharge of backfill by gravity alone at high per cent solids. This discussion will include brief mention of the underlying principles of saturated solids flow contrasted to that of stirred tank or dilute discharge systems. Here the need to possess full knowledge of the flow properties of the stored material will be highlighted. In regard to attainment of reliable discharge it will he revealed flow from a backfill silo will only occur provided: ò the flowing material in the converging channel is yielding throughout; ò slip is occurring along the walls; ò an arched stress field is present in the vicinity of the outlet; ò the flowing backfill must be dilating to flow in response to the dilating stress field; ò sufficient dilation water is injected, in the hopper, to eliminate the formation of adverse interstitial pressure gradients; ò sufficient dilution water is injected, downstream from the hopper outlet, to generate a pumpable slurry of maximum per cent solids; ò the silo level must be sufficient to prevent the pump suction forming a rathole; ò the system must be configured and operated to generate stable discharge density; and ò the system must be configured and operated to minimise damage to the pump liners. In addition proper account must be made of the silo overflow weir and settling capacity to match plant throughput. Here opportunity will be taken to highlight the complexity of this multi-phase flow situation as well as the general yet paramount requirements for reliable solids flow. It will be shown that by proper attention to the multi-phase considerations gravity discharge of slurries as a consolidated bed with minimal water content is possible. Such high solids discharge results in greatly reduced demand for process water. In addition pumping costs are reduced as is the delay time associated with the mine drainage operation. Confirmation of successful applications will be highlighted by reference to several recent case studies. In the concluding phase mention will be made of the key yet very simple and effective operation techniques which enhance reliable Discharge.

Jan 1, 1998

By B Small

CSA Mine, named after the nationalities of the mines first owners being Cornish, Scottish, Australian, is one of Australia’s deepest and highest-grade copper mines. A combination of the modified Avoca method and shrinking was a standard practice where production rings were fired against and bogged to waste fill. This method resulted in dilution and involved rehandling of waste material to refill the bogged stopes in the Western region and the QTS Central. The introduction of pre-charging blastholes using a wireless initiating system (WebGen™) has enabled CSA to design and fire stopes in reverse. This involves the use of a pre-charged Temporary Rib Pillar (TRP) against the waste fill material in a previously mined stope. The temporary pillar reduces dilution and improves conventional bogging as material is blasted towards the drawpoint rather than towards the waste fill material. Additional drill, prep and blast re-work is reduced or completely removed as rings can be charged prior to, in conjunction with, or after, charging of the slot. This is a safer practice as the charge crew spend no time working adjacent to a brow or open void. A TRP trial was conducted in the western orebody at CSA. The risk of exposure to a brow or open void while charging underground, and the bogger rehandling of waste material was successfully eliminated. Once reverse stoping was established in modified avoca stopes at CSA, two TRPs were implemented in challenging ground conditions in the QTS Central region. The TRPs were utilised in a retreating four-way intersection to extract a central diminishing pillar to close the level out. The ore recovered in this stope provided 5 per cent of CSA’s copper for the year. Without pre-charging with a wireless initiating system, two 5 m pillars totalling 6936 t of ore at 7 per cent either side of the stope would not have been recovered. CSA has implemented the practice of reverse stoping in modified avoca stopes using TRP for ten stopes since the successful trial. The development of additional blasting techniques enabled by precharging with wireless initiating systems is currently underway in the QTS North orebody at CSA Mine.

Mar 29, 2023

The current boom being experienced by mining, coupled with a shortage of professionals, will mean those in the industry will have many choices. It may be easy to become carried away and run with the highest bid or the biggest promise. Without planning, however, the ærightÆ opportunity may be missed and there may be some long-term consequences. There are many choices of paths in the industry to suit work preferences, life cycles and to achieve a balanced life. People in mining have changed jobs and companies frequently û which means new leaders need to take greater responsibility in charting their own direction. Career options need to be carefully assessed and aligned to personal values and preferences. Emphasis is given on gaining site experience early on.This paper examines strategies for career planning, which incorporate life cycles, education and what is meant by a balanced lifestyle. Two tools are identified as being helpful in ensuring strategies can be successfully executed. They are ævisioningÆ and æinfluenceÆ.To make the mining industry more attractive, we need more creative solutions around advances in technology and organisation of work. It also needs the input and leadership of new entrants in to the industry to assist in its survival. New leaders are encouraged to voice a vision and effectively influence their companies. New leaders have little authority and need to learn how to effectively influence. We as a mining industry need to listen, be open-minded and give it a go.

Jan 1, 2004

By J Kuva, M Parian, B I. Pålsson

One of the main factors affecting the suitability of an ore for autogenous grinding is the ore’s competency, ie providing enough critical stones for the grinding process. Several experimental test routines exist and are used for assessing the viability of the ore for autogenous grinding. However, very little attention is given to the generation of fatigue in large stones experiencing repeated shocks in the mill. To investigate this, large pebbles sampled from an industrial autogenous grinding mill running hard and soft ores were categorised based on the grinding energy. From the pebbles, small drill core samples were prepared and went through a series of fatigue cycle tests. Both hard and soft ores showed similar average resistance to failure in compression tests, but the hard ore had a consistent resistance with lower variations. The cores were scanned by XCT before and in-between fatigue tests at the highest reachable resolution, 1.5 µm voxel size. The outcome showed that a higher number of micro-cracks were visible in the soft ore compared to the hard ore. The frequency of micro-crack development in the soft ore may be the reason for its lower specific grinding energy compared to the hard ore. It is obvious that for realistic conditions in an autogenous grinding mill, stones are pre-weakened by fatigue before they fracture. Therefore, shortcut methods focusing only on running tests on fresh and small samples may operate in unrealistic conditions by ignoring the fatigue phenomenon. This is even more important for ores that are on the borderline to be considered as competent for autogenous milling.

Aug 24, 2022

By L Nicholls, A Parbhakar-Fox

Reprocessing Queensland’s historical copper tailings for critical minerals is an opportunity to circularise the state’s mining industry by converting waste liabilities into assets. Mine waste valorisation enables economic rehabilitation of legacy mining sites, improves environmental outcomes, and can establish a secondary resources sector that produces a sustainable supply of critical minerals to supplement growing global demands (Australian Government, 2023). The North-West Queensland Minerals Province (NWQMP) hosts numerous copper mines with known cobalt mineralisation (Degeling, 2020). Cobalt is a critical metal essential for green energy and battery technologies, however its global supply is at risk due to geopolitical and ethical concerns (Rachidi et al, 2021). Historically mining in the NWQMP has focused on copper, leaving cobalt to theoretically accumulate in the mine waste. First-pass geometallurgical characterisation of waste repositories by the Sustainable Minerals Institute identified Capricorn Copper as a key site for further investigation into cobalt deportment and recovery potential.

Aug 2, 2023

By P Jere

Mechanically coupled rock bolts encapsulated in cementitious or polyester cartridge resin grouts have been widely adopted for various underground rock reinforcement applications. Resin grouts are considered a superior product, however, both systems have their advantages and limitations, with the relative performance, quality installation cost and cycle time as the most notable parameters. Both applications have optimal rock bolt combinations and preferred ground conditions. Cementitious grouts are favourable for use with secondary deep embedment anchors. These are installed using various equipment with a series of autonomous tasks required to complete the installation cycle. The cartridge resin system can be utilised by a bolting or face boring rock drill to complete the full support installation cycle. This reduction in equipment changeouts mid-cycle generally deems it the more practical application and popular choice for primary support. Self-drilling anchors (SDAs) and hollow bolts have been a viable alternative to traditional rock reinforcement in variable and challenging ground conditions. Using a pumpable post installation grouting system, SDAs have proven to aid the quality of installation, but due to the additional equipment and cycle steps associated with application, the cycle time is increased. In recent years, fully mechanised bolting equipment designed to utilise a combination of self-drilling anchors and a thixotropic pumpable resin installed in a single pass has entered the market. This innovation is anticipated to deliver the advantages described above, with fewer limitations, and significantly improved development and rehabilitation rates. St Barbara Mining and Byrnecut Australia, supported by Master Builders Solutions, were first to conduct extensive trials and implement this rock bolting approach in an Australian hard rock underground mine and record the actual performance.

Mar 29, 2023