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By D Teyhan, J Kirsch

Traditionally, most Australian iron ore mining operations have been surface-based. Processing plants were designed to handle dry ores. In recent years mining operations in the Pilbara have progressively moved below the water table exposing wet, sticky ores which have caused lost efficiency in screening operations as particles tend to agglomerate and adhere, blinding screening media. Miners and vibrating screen manufacturers have experimented with a shift from linear motion to elliptical motion screens. Elliptical motion conveys and lifts particles. Effective on flat deck (horizontal and inclined) or sloping decks it can be configured to provide a controlled transport rate, applying pressure in all directions to maximise screening efficiency. In practice, elliptical motion screens have proven to be effective in dislodging sticky particles from screening media, reducing blinding rates and improving screen efficiency. Moisture and clay content change during the life of a mine. These changes are sometimes the effect of seasonal rainfall, in other cases due to increased groundwater and clay content as mining operations go deeper. To compensate for such changes and optimise screen efficiency, changing the ‘shape’ of elliptical screen motion is required. This has traditionally required shutting down processing plants and making mechanical screen adjustments. Plant downtime is costly and machine adjustment has been a ‘trial and error’ practice. This paper will explore the results of a field trial that is currently underway in Brazil of a next generation elliptical motion screen design that allows operators to make changes to exciter rotational direction, speed and screen stroke angle, through electronic drive phase control. The machine’s electronic drive system synchronisation is enhanced for stability with a unique mechanical timing system. Operating at up to 6 g, screen adjustments can be made on the fly without stopping production. Early trial results are showing up to 50 per cent improvement in screen efficiency compared with traditional elliptical motion machines under certain feed conditions.

Nov 8, 2021

By B Y. Luan, Y Tian, W Zhou, X Lu, Q X. Cai

The unmanned driving technology in open pit coalmines is an important technology that relies on innovation to drive the development of the open pit coal mining industry in China’s transformation of growth drivers and industrial structure upgrading. It is an important path to solve the shortage of mine truck drivers in the future mining, an important way to improve the working environment of open pit mining personnel, and an important foundation for achieving flexible production capacity in open pit mining to cooperate with the coordinated development of new energy. The communication rules at intersections are key to ensuring the safety and efficiency of unmanned driving in open pit coalmines. This paper proposes a collaborative traffic strategy between unmanned trucks for the single bucket unmanned truck intermittent process system in open pit coalmines. Based on the gap theory, this paper analyses the conflict characteristics and establishes a coordinated traffic strategy for the common intersection and merging conflicts of unmanned truck trucks in open pit coalmines, A multi-agent system simulation platform was built to evaluate the coordinated traffic efficiency under different initial average gap sizes of vehicles, with intersection traffic density, vehicle speed, and gap changes as key indicators. The results show that under the simulation conditions of this article, when the initial average gap of vehicles reaches three (four) times or more of the safe distance, the coordinated traffic performance of intersection conflicts (merging conflicts) is better, and the traffic capacity of intersections is close to the traffic capacity without conflicts.

Sep 1, 2024

By M J. Nugus

The structural models developed by exploration and mining geologists are most commonly concerned with the ‘main structures’ or key constituents that pertain to the associated mineralisation. To this end, it is recognised that the geological and exploration models, which are developed, are essentially ‘fit for task’ and the scale-related variances are not always realised at an early stage. In fact, in many cases anomalous intercepts along different trends and of variable apparent continuity have often been neglected as ‘back scatter’ and not important. Recognition of the importance of subordinate structures as mineralising hosts suggests that additional opportunities exist outside the primary and main structures. History shows that opportunities are often not realised where gold is hosted in orientations not parallel to the predominant trend of the schistosity, main fault or shear zone.Another reason for the importance of subordinate structures can be understood from their roles in a percolation network. Subordinate structures can access the large fluid fluxes provided by backbone elements, but, as dangling elements, they provide greater opportunities for gold precipitation mechanisms and hence may constitute essential parts of the resource. Therefore, the role, understanding and consideration of the smaller-scale and orthogonal structures should be considered during all facets of exploration, resource development, delineation and mining.

Aug 22, 2011

By Bronson B

The geotechnical and environmental aspects of heap leaching are very closely tied during design, operations and closure. Potential environmental impacts from heap leaching are mostly due to land disturbance and water quality issues, including both groundwater and surface water. Water quality issues are mostly related to containment design, which is primarily a function of proper sizing of the facilities and site specific liner design. Geotechnical analyses is the dominant discipline in providing cost efficient, operationally effective and environmentally sound heap leach facility designs. Much has been published on geotechnical aspects of heap leach design, for example Van Zyl, Hutchison and Kiel (1988) and Van Zyl (1987). This paper will emphasize a few specific aspects related to the geotechnical and environmental consideration for heap leach projects. These aspects are: ò site investigation; ò containment design; ò slope stability; ò heap flow dynamics; and ò closure design. Design of a heap leach project must consider not only the operating life but also closure and post-closure considerations. As a matter of standard practice, designing for closure is an extremely important concept. Not only is it important for environmental aspects, but experience also shows that projects designed for closure will be overall more economical for the total life cycle of the project. Closure considerations are also important during project feasibility evaluations to ensure that total life cycle costs are evaluated.

Jan 1, 1994

The Electricity Generating Authority of Thailand own and operate an opencut mine supplying coal to on-site power stations at Mae Moh, 600 km North of Bangkok. The mine is being expanded from an annual production of 1.5 million tonnes per year in 1982 to over 9.5 million tonnes per year by 1991. The mine will be amongst the largest open pit operations in the world. It is technically difficult to operate and plan due to complex geology, weak strata and surface constraints including reservoirs, forests and traditional villages. This paper presents a case study of mine planning for the above project including associated collection and processing of geological and geotechnical information. The existing operation is described, as well as the strategy adopted for the mine at expanded production. The planning covers various phases of mine planning including a Conceptual Study, a Definitive Study and detailed short term planning. Each stage incorporated new information and reflected a higher level of confidence in the data and resulting plan. Sophisticated computer techniques were required including geological modelling, calculation of volumes, geotechnical analysis, scheduling and costing. The planning was undertaken on site by a team of Australian and Thai Engineers as part of the Thailand-Australia Lignite Mines Development Project which is a four year programme of assistance funded by the Australian Government.

Jan 1, 1986

By J Chßvez, J Rosa del Castillo, J Rui

Environmental Impact Assessment (EIA) and Feasibility Studies (FS) were carried out to evaluate the potential use of treated acid mine drainage (AMD) occurring at the Kingsmill Tunnel in the Central Andes of Peru. The 11 km long tunnel drains the underground works of the Morococha Mining District and discharges about 1.25 m3/sec of AMD directly into the Yauli River in the Amazon Basin. The communities living downstream cannot use the Yauli River water due to its low pH and elevated concentrations of metals (eg Cu, Zn, Fe, Mn, As, Cd) and sulfate. Studies carried out for this project included technical feasibility, EIA, economic viability and social impact assessment phases. During the æTechnical FeasibilityÆ phase, the treated AMD was produced by simulating a high density sludge (HDS) lime neutralisation/ precipitation process and was evaluated for various potential uses. Mining companies located in Morococha, in particular Centromin Peru SA, and the Water Works Company of the City of Lima (Sedapal) collaborated with Golder Associates during the studies. The Canadian International Development Agency (CIDA) provided the financial assistance. The results of the physical, chemical, biological and toxicological analyses demonstrated that the AMD could be sufficiently treated to be potentially used to supplement the drinking water supply of Lima, and for agricultural (eg irrigation and livestock) and recreational purposes. Process design and scale-up parameters were also determined for implementation of the full-scale treatment facility at the site. The use of the treated AMD as a drinking water supplement would be economically feasible.

Jan 1, 2003

By M R. Asef

Although generation of environmentally harmful hydrogen sulfide is considered to be related to sour gas fields, sweet gas reservoirs and waste fluids, travertine springs and geothermal fields may also produce acid gas (H2S and CO2) under certain conditions. The potential parameters influencing such a possibility need to be fully investigated to evaluate the extent of the consequences and predict hydrogen sulfide generation accordingly. Reports on hydrogen sulfide production at different regions and fields were gathered worldwide for the cases when some of them did not have such a problem previously. In order to inspect different aspects of these case studies, some other regions with no hydrogen sulfide content were selected as control. In all cases water samples were taken carefully for chemical analysis in the laboratory. Besides, mineral compositions were characterised in some cases for better evaluation. In order to give a thorough prospect of hydrogen sulfide production, a geochemical model was prepared. In situ engineering geological conditions, especially pressure and temperature, were assigned in the model to investigate the possibility of H2S generation using PHREEQC software. The results of modelling revealed that although many similarities existed between mineral compositions of the cases, certain formations were particularly prone to hydrogen sulfide generation. For better evaluation, important exchangeable cation ratios such as potassium/sodium, calcium/magnesium and ion proportions like sulfate and chloride were calculated as trends of the formations. As expected, the model could successfully monitor a higher ratio of SO42- and Cl- in potential H2S generator formations. Wide variation in percentage of HCO3- was considered as a secondary observatory parameter for better estimation. In addition, it was noticed that higher anion content created an environment ready to absorb any cations and this makes H2S generation easier. Finally, using correlations between predictors and estimators for low depth and deep samples defined the degree of effectiveness for every sample.

Sep 26, 2011

By C Young

The identification of Critical Risks, their associated Critical Controls, and the implementation of processes to ensure their ongoing management can be difficult and resource intensive. Answering the following Critical Risk Management related questions can be challenging: • What is a Critical Risk? • What is a Bow-tie Analysis and when should it be used? • What is Critical Control? • How is the effectiveness of a Critical Control assured, and how is this measured? • Who is responsible for managing Critical Controls? • What are the implications if a Critical Control is not effective? It appears that in the mining industry’s efforts to implement the Critical Control Management Process outlined by the International Council on Mining and Metals (ICMM), instead of embedding an integrated, well understood, value adding process, we have instead created a resource hungry monster that is poorly understood by numerous layers of the organisation.

May 5, 2022

By R Schiller, E Chait

"Quebrada Blanca is a porphyry copper deposit located in the Eocene-Oligocene belt of Chilean Andes. Operation started in 1994 and original reserves for supergene mineralisation gave a life-of-mine (LOM) of 20 years; however, further exploration extended the LOM until 2020.In order to optimise the remaining five years of supergene resource, geometallurgical variables were added to the geological model including copper recovery and acid consumption. LOM plan encompasses finishing the phase number eight and the future development of phases 11 and 13.LOM lithologies include diorites, quartz monzonites, porphyries, igneous and tourmaline breccias. Main alterations are: potassic, phyllic and argillic. Litho-alterations or geometallurgical units were formed by combining five types of rocks with three types of alteration. According to statistical information, the deposit can be represented with 12 litho-alteration units, which cover 98 per cent of the LOM volume.For copper recovery information, there were 40 mini-columns tests made in order to obtain kinetics curves and copper recovery values after comparing the difference between head and tails grades. Acid consumption was obtained using an automatic neutraliser device-based test.Historical data said that copper recovery in pads after 450 days of irrigation is around 75 per cent of recoverable copper while acid consumption is around 5.5 kg/t.According to this study, lower recoveries are related with potassic-altered diorites and argillic-altered quartz monzonites with values around 60 per cent. On the other hand, best recoveries could be found in potassic-altered quartz monzonites and argillic-altered diorites with values closer to 80 per cent.It was also revealed that the most reactive rock is the potassic-altered diorite with 12 kg/t of acid consumption. This rock covers approximately 40 per cent from phases 11 and 13.The final geomet model was calculated using a program that relates each geometallurgical unit with a specific copper recovery and acid consumption value. Results found after comparing model-obtained information with historical leached pads data were used to validate the model.CITATION:Chait, E and Schiller, R, 2016. Adding Copper Recovery and Acid Consumption Variables to the Geological Model of Quebrada Blanca, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 257–266 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By C Simpson, J M. F Clout, G Plummer

Detrital iron deposits (‘DID’) in the Hamersley Province of Western Australia have been successfully mined and processed as small quantities of saleable standalone or blended lump and fine ore products over many decades. Despite their past, present, and potential future exploitation, they have received far less geological attention than the economically more significant higher grade bedded iron deposits (BID) or channel iron deposits (CID). DID are composed of Pliocene to Quaternary unconsolidated colluvial/alluvial hematite gravels with minor sand, silt, and ferruginous clay, as well as minor iron rich hematite clast conglomerates. DID mineralisation at Solomon has been subdivided into six distinct stratigraphic units, DID-5 (lowermost) to DID-0 (uppermost) based on differences in clast and matrix textures and mineralogy, degree of consolidation/lithification, particle size distribution and replacement textures. The most significant accumulations of DID-1 to DID-5 are in tributary valleys that have been cut through the Joffre Member of the Brockman Iron Formation on either side of the main Kings-Queens valley which contains the CID. DID-5 and DID-4 are ferruginous conglomerate, referred to as canga, with four subtypes recognised. DID-4 is composed of BID hematite clasts cemented by hematite or goethite. DID-5 is characterised by partial to complete replacement of BID hematite clasts and matrix by the yellow ochreous and brown to black vitreous forms of goethite. DID-3 to DID-0 are unconsolidated hematite detritals composed of largely (>80 weight per cent) fine to coarse gravel, minor sand and little silt or clay. The gravel clasts are largely composed of hematite and hydrohematite that replace BID, micro-nanoplaty hematite-martite-ochreous goethite (m-nplH-M-oG) BID, reworked canga, hematite pisoids, siliceous hematite BID (micro-nanoplaty hematite-martite-quartz, m-nplH-M-quartz), chert (~10–20 per cent) and minor (<5 per cent) Banded Iron Formation (BIF). Hematite abundance decreases from DID-3 to DID-0 whilst siliceous hematite BID is highest in abundance in DID-0 and lowest in DID-3. A key finding of the study is that >90 per cent of mineralised detrital clasts are derived from hypogene altered BID micro-nanoplaty hematite-martite with subsequent later supergene ochreous goethite mineralisation hosted by the Joffre Member. The DID genesis model entails interpreted Palaeoproterozoic siliceous hematite hypogene microplaty BID mineralisation of the Joffre Member undergoing Cenozoic supergene leaching of quartz and replacement by ochreous goethite to form low phosphorous BID micro-nanoplaty hematite-martite-ochreous goethite clasts. BID martitenanoplaty hematite-martite-ochreous goethite clasts and detritus eroded from hill slopes were deposited in the valleys as an initial single DID-5-DID-4 unit over a weathered pre-CID basal conglomerate. DID-5 and DID-4 underwent goethite cementation of the matrix followed by replacement by hydrohematite, hematite, and maghemite. DID-3 formed during subsequent periods of erosion of largely DID-4 hematite clasts and pisoids. Groundwater flow-through hematite canga resulted in partial to complete hydration replacement of DID-4 hematite clasts and matrix by ochreous and vitreous goethite to form DID-5. Deposition of DID-2 to DID-0 was via reworking and deposition of DID-5 to DID-4 canga and DID-3 as clasts and pisoids/ooids, as well as siliceous hematite and BIF sourced from the Joffre Member in the hill slopes.

Nov 8, 2021

The paper describes the studies conducted to date on the short term adsorption/desorption of gases in coal from the point of view of developing techniques to predict imminent outbursting conditions in coal mines. A number of different parameters such as&apos;dP express, K&apos; and AV 0/60 etc. which have been effectively used overseas were studied on samples of coal from Westcliff and Leichhardt Colliery. Results indicate that these do not seem to be valid indices for predicting an outbursting condition. Based upon desorption isotherms, a new index defined as "L" has been developed which shows promising results. This index is in a position to differentiate the changes in the structures of coal and its proness to outbursts. The "LZ value determinations and its usefulness opens a new field where it would be possible to determine outbursting conditions from existing drill cores obtained during exploration studies or from long holes drilled in advance from underground workings. The index is more or less independent of the time elapsed between the extraction of a sample and the conduct of the test. The test for "L" can be conducted&apos;on site or in the laboratory. The test is simple, easy to carry out and the "L" value for a sample can be calculated in less than 20 minutes. It could be adapted as a routine test for monitoring outburst conditions in mines.

Jan 1, 1980

By P N. Holtham

Magnetic separation is routinely used in the processing of titanium minerals, and the efficiency of these operations can be determined by measuring the magnetic properties of the process streams. The valuable components in the feed to a titanium minerals plant have specific magnetic susceptibilities ranging from -10-9 m3 kg-1 (zircon) to 10-6 m3 kg-1 (ilmenite). However, in an industrial environment, in which the mineral temperature may range from 20 to 120¦C, it is difficult to measure susceptibilities lower than about 10-7 m3 kg-1. Hence laboratory testing of spot samples from magnetic separators is currently required to obtain accurate performance data. This is an inherently slow process and where feed grades are variable, optimum performance of magnetic separators is generally not achieved. This paper describes the development of an inductance-based instrument for measuring very low levels of magnetic susceptibility on-line. The signal from the instrument can be used for process control purposes to maintain optimum magnetic separator performance. A prototype instrument has been installed in the zircon scavenger circuit in an Australian titanium minerals plant. The circuit consists of a roll magnetic separator treating a feed consisting mainly of monazite and stained zircon. The monazite-rich magnetic fraction is returned to the mine site for disposal, while the non-magnetic fraction is recycled to the zircon wet circuit. Splitter positions in the separator are adjusted when the final zircon product fails to meet specification, or the magnetic fraction contains more than 30 per cent zircon. Weekly composite grain counts show that sub-optimal operation of the magnetic separator results in significant zircon losses into the magnetics fraction. Using the instrument, the zircon content of this stream can now be accurately determined from the measured magnetic susceptibility, provided a correction for the effect of mineral temperature is applied using the Curie - Weiss relationship.

Jan 1, 2001

By Jagger ND

Pressure filters were found to be necessary to produce Elura silver/lead and zinc concentrates at sufficiently low moisture contents for bulk cargo shipment by sea to smelters.The difficulty in obtaining low moistures was due to the fine primary grind, 80% passing 45 microns, and resultant fine concentrates, 97% passing 45 microns.The filtration system was designed to filter up to 90,000 tonnes/year silver/lead concentrates and up to 130,000 tonnes/year zinc concentrates.This paper details the preliminary test work to select Larox automatic pressure filters, and the commissioning and operation of these filters to achieve design criteria for both concentrates. The design criteria for both concentrates have been bettered due to the concentrates being coarser than the design sizing.

Jan 1, 1985

By G Turner-Saad

An improvement to cut-off grade optimisation theory based on geometallurgy has been completed. The improvement fundamentally consisted of taking into account mineralogical and textural characteristics instead of grades. These characteristics are related to the spatial variability of mineral abundance, association, particle size and liberation properties. Additionally, the improve- ment considered the spatial variability of mineral processing liberation and selectivity properties associated with mineralogy and texture. The enhanced optimisation enables estimation of the economic value of mining operations based on an optimum cut-off policy attributed to liberated and selected ore minerals.The enhanced optimisation was developed as an essential component of a joint cut-and-fill mining and mineral processing methodology based on mixed integer mathematical programming. The formulation considers static and dynamic modifying factors that vary over the projected life of mining. The objective function of the mathematical formulation consists of maximising the realistic expected economic value of concentrates or products of liberated and selected ore minerals, whilst minimises liberated and selected gangue minerals. The optimal solution is obtained when the objective function is subject to geological, mining, processing, marketing, smelting, refining, environmental and financial constraints. The methodology accesses geometallurgical multivariate resource models, which integrate the spatial variability of mineralogical and textural characteristics and mineral processing liberation and selectivity properties.The geometallurgical process concurrently optimises stope geometries, ore reserves, mining sequences, and mining and mineral processing production based on the enhanced cut-off of liberated and selected ore minerals. In addition, the process considers additive and non-additive transfer functions associated to mutually exclusive geometallurgical spatial domains. The transfer functions also take into consideration the blending of mineralogical and textural characteristics with mineral processing liberation and selectivity properties.This contribution presents an example of cut-off grade optimisation via mineralogical and textural characteristic, and liberation and selectivity processing parameter optimisation for a spatially variable orebody.

Sep 5, 2011

By Rokot M

In a little over three years, Chevron Niugini has built up a team of relatively young, hard working men and women, mostly Papua New Guineans, who spend most of their working days out among people in the Southern Highlands and Gulf Provinces who are directly affected by the Kutubu Petroleum Development Project. These are Land and Community Relations officers, or LACROs. They take on a huge responsibility, not only representing Chevron but also being friend, advisor and negotiator, frequently dispensers of medicines, and agricultural advice and more. When things go well, others get the praise, when things go wrong, LACROs are the martyrs. Just as the geologists who locate the oil, the drillers who find it, the engineers who design the facilities, the construction gangs who build them, the landowners who claim it, and the Government who monitor it, so are the LACROs part of a team.

Jan 1, 1991

By Huleatt M, Perkin D, McLeod I, Mock C, Pratt R, Gourlay A, Timoney E, Knight N, Ward J

Generally speaking, Australia&apos;s reserves of its more important minerals (in terms of export earnings) are adequate to sustain forecast rates of production to the year 2000. The rate of forecast production increases of these commodities (aluminium - whether as bauxite, alumina or metal, black coal, iron ore and ferro-alloy minerals, base metals, tin, uranium, and mineral sands) reflects a well- ordered and sustained growth phase of Australia&apos;s mineral industry.

Jan 1, 1981

By M Francoeur

Oct 12, 2022

By G W. Wilson, P Ritchie, N A. Currey

The design and rehabilitation of potentially acid forming (PAF) waste rock dumps is site specific, being a function, among other factors, of the rock types, the dumping and storage method employed, and the climatic setting. The æstore and releaseÆ cover system developed to manage acid rock drainage (ARD) from mineralised waste rock dumps at Kidston Gold MinesÆ open pit operations in the semi-arid climate of North Queensland, Australia, has been monitored for seven years. The paper describes the philosophy behind the design of the PAF dump and æstore and releaseÆ cover system and the adaptation of the cover system over time to suit KidstonÆs conditions. The results of monitoring over the seven years since the first cover was constructed are presented, and the approach being taken at Kidston to ensure that the risk of impacts from any residual ARD is accommodated and to facilitate lease surrender are described. The Kidston story is a valuable case study of a successful approach to remediating an identified source of ARD in a semi-arid climate, which has actively engaged all Stakeholders.

Jan 1, 2003

Employing gravity recovery for coarsely liberated gold and sulfide ores has potential to lead to a signifi cant reduction in the energy required for comminution and ultimately can have a significant impact on gold processing. Most of the recognised metallurgical tools at our disposal currently have been designed around recovery of relatively finely ground minerals. In order to change the paradigm of fine grind for liberation, a new set of tools need to be recognised that are capable of separations in the coarser size fractions. Some of these tools already exist and some need to be developed but the key is the way in which the fl ow sheets are arranged. A very strong understanding is required in the existing tools and their capabilities before these new flow sheets can be optimised. Only when we understand the existing gaps in technology can we start to fill these positions with new candidates. Many ores when crushed liberate their gold bearing minerals at coarser sizes than current practice would suggest (Figure 1). In order to characterise this response in ores it is necessary to utilise some new techniques in the lab such as gravity separation and ore sorting at the sizes greater than 15 mm followed by gravity recovery on fractions from 15 mm down to 150 ¦m. The most difficult range has been the mid-sized fraction from 4.0 mm down to around 150 ¦m. This is the size range in which many ores show economic liberation starting to occur and coincidentally this is the range in which many commonly used metallurgical processes reach their operational limits due to physical constraints. Examples of these processes are flotation, hydrocyclones and whole ore leach in agitated tanks which are currently the mainstays of the processing fraternity. This is an ABSTRACT ONLY. No paper was prepared for this presentation.

Aug 1, 2010

By I Gray

Other than being reasonably certain of the average vertical stress being lithostatic, there can be little certainty about stress in the ground. The stresses and strains in rock are a function of gravitational effects, external load, thermal changes, diagenesis and their mechanical properties including elastic, creep and post failure behaviours. It is highly desirable to measure stress where mining is going to take place, even if the virgin stress condition has already been changed by mining. The concept of some far field stress value that is more or less constant is usually invalid and can be dangerous to use in mine design. Measuring stress is not simple. The basic processes are broken into two categories, one where the rock will not fail around the borehole in which the stress is being measured and one where the rock has failed or will fail. Because of the complexity and cost in obtaining a single, precise stress measurement it is highly desirable to have some system to be able to obtain an idea of the uniformity, or otherwise of the stress situation between precise measurements. Table 1 shows the methods for measuring stress. The first five methods work on the basis of some fairly direct measurement of mechanical rock behaviour while the last three are attempts to get some idea of stress out of core long after it is removed from the host rock. While these latter methods appear to tick all the boxes for applicability there is a great deal of uncertainty in the results that they deliver. This paper reviews the methods for measuring stress and presents two new methods. These are a three dimensional overcore system to provide precise stress measurements in rocks that will not fail around the borehole and a core ovality system. The latter can be used to provide information on the stress difference orthogonal to the core. It is particularly useful because it can be used every metre of core length.

Nov 29, 2022