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By S Mitra, D O’Dea, N Barrett, S, T Honey, M M. Hoque

The steel industry is currently exploring hydrogen-enriched blast furnace operations as a means to reduce the greenhouse gas emissions. However, there is a need to investigate the gas permeability behaviour of mixed burdens comprising of lump and sinter as the current knowledge regarding their behaviour is limited, particularly with regards to hydrogen enrichment. In the present study, a series of interrupted softening and melting (S&M) under load tests were carried out in a hydrogen rich gas environment (~15 per cent) in the temperature range from 1000 to 1300°C by placing different types of ferrous ore layer including Newman Blend Lump (NBLL), sinter and sinter-NBLL mixed burden in between two coke layers. X-ray computed tomography (CT) was then used to scan the interrupted test samples. Scanned images were first analysed using an image processing workflow implemented in ImageJ and the material simulator GeoDict (v2022) to segment different phases such as coke, ferrous and void based on their grey scale values. A quantitative analysis was then performed on the segmented images to estimate the phase volume fraction as well as bed permeability. Bed void fraction thus obtained agreed well with the bed contraction data obtained from the S&M test. It was further noted that both ferrous layer void fraction and bed permeability decreased linearly with increasing temperature for all ore samples. The mixed burden voidage changed in a similar fashion to the sinter, demonstrating a high temperature interaction between the two materials

Sep 18, 2023

By Wilson A. F

The use of stable isotopic measurements as a technique for elucidating the origin and history of the water in hydrothermal fluids is relatively new. Recent studies have emphasized the importance of meteoric water in the formation of many hydrothermal ore deposits including many epithermal gold-base metal deposits which occur in faulted volcanic terrane. Other vein-type gold ores are be- lieved to have formed from fluids of magmatic or metamorphic origin and exhibit characteri stic 6180 values. These values also give information regarding temperatures and the degree of equilibrium. Preliminary oxygen data for some important gold deposits of eastern Australia are evaluated in the con- text of styles of mineralization.

Jan 1, 1980

By Mackenzie J. M W

The mechanism of clay slime flocculation in coal washing circuits is considered and it is concluded that polymer flocculants are most suitable. It was found that the addition of sea water with a polymer flocculant improved flocculation and settling, and it was also found that dilution of a flocculated pulp increased floc size and hence settling rate.In predicting plant consumption of reagent it was found that cylinder tests, or even pilot plant tests, could give erroneous results, particularly on flocculated pulps. Different flocculants may, however, be compared in cylinder tests.For filtration, flocculation with Separan plus sea water was much more beneficial than flocculation with Separan alone.INTRODUCTIONDuring the mining of coal, and its subsequent beneficiation by washing, large quantities of minus 10 mesh material are produced. This fine material, which consists of broken down shales and fine coal, causes difficulties in water clarification circuits, in refuse disposal, and in filtration of fine coal.These difficulties can be largely overcome by flocculation, and this paper discusses the mechanism of flocculation, the methods by which a selection of flocculant may be made from the large number available, and the limitation of the prediction of plant performance from laboratory tests. This work applies particularly to the washeries of The Broken Hill Proprietary Co. Ltd. (B.H.P.) and Australian Iron and Steel Ltd. (A.I. & S.) .

Jan 1, 1962

By S Youds

The backfilling operation at Olympic Dam mine supports a 9.8 Mtpa underground Long Hole Open Stoping (LHOS) operation. It involves a combination of Cemented Aggregate Fill (CAF), surface rockfill and underground rockfill. The fill material is introduced from the surface via boreholes into the top of the stopes. Due to the deleterious effects of the dust and the thickness of the atmosphere in the stope it is not possible to view the filling process either at optical or infrared (IR) wavelengths. The need for a means to measure the filling process is driven by the placement of both rock and CAF fill in the stopes. The large volumes and high relative cost of CAF makes the minimisation of CAF fill a business priority. Incorrect filling can lead to the sterilisation of ore reserve. The use of millimeter wave radar to view through the haze to give real-time data on the relative positions of the different fill masses is being developed as an in-stope fill monitoring device. This paper reviews the salient points of the technology and its potential use in the backfilling operation at Olympic Dam. The broader potential of this technology for use in the mining industry by æseeingÆ through water and dust laden environments such as that found in stopes and ore passes is also discussed.

Jan 1, 2002

By Hendon G. W, Carr F, Jiang Y

A vast majority of the operating longwall sections use shield-type face supports to provide ground control in the United States. As a co-operative research program between the University of Alabama (UA) and Jim Walter Resources, Inc.(JWR), a joint research program is underway to study interaction of shields with surrounding rock masses. A series of analyses on the response of shields are performed using monitored data at a longwall face in a deep coal mine. In this paper, various effects of parameters, such as leg pressure, setting load, developing load, maximum loading rate, pressure in capsule, and convergence between canopy and base, are discussed and recommended as stability indices. A microcomputer program is being developed for instantaneous interpretation of the shield monitored data, and for giving warnings of potential problems. The preliminary results define the effects of the setting load, developing load, and rate of developing load or leg closure rate. The objective of the study is to understand the shield characteristics and their interaction with surrounding strata in real time, then develop a reliable program for maintaining longwall stability.

Jan 1, 1992

In the 1890s, The Goldfields Water Supply Department in Western Australia commissioned the diamond drilling of two deep artesian exploratory water bores near Coolgardie (Blatchford, 1899). At the time, in spite of strongly-worded advice to the contrary from the Government geologists, there was a wide popular belief that you could obtain artesian groundwater virtually anywhere providing you drilled deep enough. The first Coolgardie hole was drilled to over 900 m, despite the fact that the bore penetrated granite from a depth of 5 m below the surface. Drilling proceeded for more than 16 months, between July 1896 and November 1897. A small quantity of salt water was struck at a depth of 36 m. The second bore was mercifully terminated at a depth of 50 m, also in granite, with again only a small inflow of salt water. Such were the desperate lengths that were pursued to obtain a reliable water supply for the influx of people in the Eastern Goldfields gold rush. The WA Goldfields continued to rely on huge condensers for water supply until that great engineering feat, the construction of a water pipeline from Mundaring Weir to Coolgardie, was completed in 1903. An enormous network of rail tracks penetrated outwards from Kalgoorlie and Coolgardie for the collection of timber, principally to feed the condensers. Remnants of the rail network are still visible today. The acute shortage of fresh water led to great deprivation, disease and death among the early miners. Today, the water problems faced by the mining industry are thankfully not as severe, but they are nevertheless no less challenging. The southern part of the WA Goldfields is a notoriously difficult area for finding potable quality groundwater. Even as recently as the 1990s, there were occasional serious efforts to find potable groundwater in that area, some very imaginative and innovative. One mining company, working south of Southern Cross, spent many months experimenting with recovery of potable quality water from a shallow freshwater lens overlying hypersaline water in a low permeability weathered granite aquifer. They used very low capacity pumps manufactured from car windscreen washer pumps powered by solar panels.

Jan 1, 2000

By Craw D

The Southern Alps in the South Island of New Zealand are currently rising rapidly as a consequence of continental collision along the Pacific-Australian plate boundary. Rapid uplift has resulted in a major thermal anomaly in the shallow crust beneath the alps. Alpine topography and associated intense precipitation, coupled with the thermal anomaly are responsible for vigorous combined topographic/convective circulation of water through the shallow crust.

Jan 1, 1995

By S F. Simmons

At Broadlands-Ohaaki geothermal system, TVZ, mineral distribution patterns in geothermal wells are analogous to those in epithermal veins. Fluid flow through geothermal wells is focused over vertical intervals >500 m with discharge at rates up to 90 l/s. Focused flow at similar rates also occurs in natural systems where hydrothermal eruption vents provide enhanced vertical permeability. These vents are commonly aligned with the tectonic fabric, indicating fault control at depth. We suggest that host rock strength and structural context exert significant control on the hydrological regime conducive to epithermal mineralisation.

Jan 1, 2005

The Beruang Copper-Gold Deposit is located very near the centre of Kalimantan in Indonesia. It is a dacitic tuff hosted deposit currently being explored by Kalimantan Gold Inc of Canada. Exploration activity to date at Beruang has been focused on the Main Zone, which is defined by a north-south elongate, 1 + 1.5 km zone of anomalous copper and gold, and intense phyllic alteration. The disseminated sulfides responsible for the anomalous copper values produce a moderate to high chargeability signature. Phyllic alteration is overlain at high levels, and on the western edge of the Main Zone, by advanced argillic alteration. The dacite tuffs hosting the mineralisation are cut by post-mineralisation dacite dykes that are delineated by ground magnetics and geological mapping. Base metals, principally zinc and lead, form broad halos around the Main Zone. These metals are incorporated in massive NE-trending, polymetallic mineralisation that outcrops to the north and south of the Main Zone. IP survey results highlight the highly pyritic NNE-trending shear zone, which hosts most of the copper mineralisation in the Main Zone. A high chargeability anomaly at depth in the central-east part of the Main Zone is interpreted to be the source for mineralising hydrothermal fluids. This is suggested by zonations in alteration and mineralisation. A deep chargeability anomaly can be correlated with the downward plunge of a pyritic breccia, encountered at shallow levels in drillholes, and is a potential breccia pipe target. Compilation and inversion modelling of the IP results has yielded some interesting drill targets.

Jan 1, 2004

By N C. Steenkamp

The Northern Cape Province of South Africa is host to the Kalahari Manganese Field (KMF). The northern portion of the KMF hosts high-grade manganese referred to as Wessels’ type ore and is mined mostly from underground operations. WorleyParsons TWP is currently involved with the development of a ventilation shaft for one of these mines. The main challenge is to develop through the unconsolidated Kalahari material and weathered portion of the Karoo formation. These formations are preserved very erratically over short distances. A lack of understanding of the unique challenges presented for developing shafts in this area has resulted in the failed development of a shaft on an adjacent property and over-expended budgets on others.The renowned red sand of the Kalahari forms the top several tens of metres and overlies a horizon of gravels and calcrete that pose seasonally variable water ingress problems. A very stiff red clay horizon is then intersected. The Red Clay is prone to swellling during excavation and has been the main stumbling block on previous constructions. The standard approach has been to develop non-stop through this layer. The red clay is underlain by another horizon of calcrete, gravel and conglomerate that marks the bottom of the formation. The top of the Dwyka Tillite (Karoo Formation) is usually highly weathered and has a distinctive yellow colour. The weathered tillite is highly susceptible to drying and becomes friable. At reef-intersection, the combination of subhorizontal bedding and joints with the dominant subvertical faulting results in potential wedge failures in the manganese and ironstone units.This paper describes the geotechnical issues identified during the planning of the ventilation shaft and the risks associated with development through the Kalahari and weathered Karoo Formations. A new approach to developing ventilation shafts in overcoming these challenges is recommended.CITATION:Steenkamp, N C, 2014. Challenges of developing a ventilation shaft in Kalahari and Karoo formations, Northern Cape, South Africa, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 81–88 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By Z Endut, T F. Ng, G H. Teh, J H Abdul Aziz

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Gold mineralisation at the Penjom gold deposit in the Central Belt of Peninsular Malaysia is hosted in structurally-controlled quartz-carbonate veins that display a variable degree of overprinting events under a ductile-brittle regime. Mineralised veins are categorised into two main types: shear and extension veins. Shear veins are interpreted as forming during the fold and thrust episode (D2 event) along the bedding and the Penjom Thrust ore zone. The shear veins are associated with discordant extension veins. In addition, NE- to NNE-trending splays and Penjom-Thrust-parallel reverse-dextral and locally NNW to N–S reverse-sinistral faults overprint earlier vein events, forming a new episode of extensional veins during the D3 event. This is mostly at the fault contacts of intrusives, either as shallow-dipping or vertical-sheeted stockwork or brecciated veins. At least two episodes of faulting comprising D4-D5 are evident, which postdates the main episodes of veining and mineralisation. This is indicated by a series of late episode N–S-trending sinistral and oblique to normal faults that transect and displace the Penjom Thrust and the folded footwall sequence at low angles, and are interpreted to be responsible for intensive vein deformation along the Penjom Thrust and displacement of the orebody. Structural interpretations of mineralised veins suggest that the veins were formed under a compressional to transpressional regime, with later post-vein displacement in a transtensional to extensional regime. Vein formation in response to deformation observed at Penjom reflects regional structural deformation within the Central Belt of Peninsular Malaysia and specifically along the Bentong-Raub Suture zone.CITATION:Endut, Z, Ng, T F, Abdul Aziz, J H and Teh, G H, 2015. Style of veins in Penjom gold mine, Malaysia – implications for gold mineralisation and structural episodes, in Proceedings PACRIM 2015 Congress, pp 507–514 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

æSustainabilityÆ is one of those words that has gained more usage in popular discourse than in the dictionary. In fact it is not in many dictionaries at all. Typically, given this, it also seems to mean different things depending on whose lips it emerges from. It is now like a code word in that if people say it, you donÆt have to think about its meaning; it is just æthereÆ and is taken for granted. This is a problem for the mining industry as we are now using the term too and to be effective in what we do, we need to have a reality check and see how those outside who have views on us (æstakeholdersÆ maybe) use it. The core issue seems to be æsustainability of whatÆ: the industry?, a company?, the global environment?, particular ecosystems?, the community? At these levels, the term seems almost meaningless. If we do not even agree on what it is, at least broadly, our communication and possible partnerships for going forward will be difficult to say the least. One reference to æsustainÆ in my thesaurus is: æTo keep from failing during stress or difficultyÆ. This may be a clue to something approaching a common notion. I suggest that to use æsustainabilityÆ we make the following assumptions:that we are talking about human activity aimed at making a living that has an impact on the natural and social environment; that humans must make a living (though what this needs to include is problematic); that the impact of particular activities has been problematic to date and needs to be monitored, altered, stopped, etc; that there is stress on both social and natural environments; and that change can be effected in order that particular activities such as mining minimise their negative effects and maximise their positive. This is why we are taking part in sessions such as this one today. Two more initial observations: First, it strikes me that even with the above assumptions laid out, æsustainabilityÆ and æsustainable developmentÆ are too abstract and general as concepts. We have to break these high and mighty ideals down into workable, bite-size chunks, into practical ways of dealing with the world outside our sites and companies. Second, sustainability, on both sides of the fence, too often focuses on nature and environment as though they are independent of people and community. I would argue, perhaps provocatively, that sustainability is primarily a people issue and has to be tackled as such. I want to look at the overall climate for business today and how it has responded before I return to what we can and need to do as the mining industry to make æsustainabilityÆwork.

Jan 1, 2002

By W Zhu, J H. Zhao, H Ma

The permeability coefficient is an essential parameter for the study of seepage flow in fractured rock mass. This paper discusses the feasibility and application value of using readily available RQD (rock quality index) data to estimate mine water inflow and grouting quantity. Firstly, the influence of different fracture frequencies on permeability in a unit area was explored by combining numerical simulation and experiment, and the relationship between fracture frequencies and pressure and flow velocity at the monitoring point in fractured rock mass was obtained. Then, the stochastic function generation program was used to establish the flow analysis model in fractured rock mass to explore the relationship between flow velocity, pressure and analyse the universal law between fracture frequency and permeability. The concepts of fracture width and connectivity are introduced to modify the permeability calculation formula and grouting formula. Finally, based on the on-site grouting water control case study, the rock mass quality index is used to estimate the mine water inflow and the grouting quantity. The results show that it is feasible to estimate the fracture frequency and then calculate the permeability coefficient by RQD. The relationship between fracture frequency and RQD and the relationship between structure surface frequency and permeability follow an exponential function. The calculation results are in good agreement with the field monitoring results, which verifies the rationality of the calculation method. The relationship between the rock mass RQD index and the rock mass permeability established in this paper can be used to invert the mechanical parameters of the rock mass or to evaluate the permeability and safety of the rock mass, which is of great significance to the prediction of mine water inflow and the safety evaluation of water inrush disaster management.

Nov 29, 2022

By M J. Saynor, W D. Erskine an, D R. Moliere

The Jabiluka uranium mine was constructed in the Ngarradj catchment, a right bank tributary of Magela Creek in the Northern Territory. The Jabiluka Mineral Lease is adjacent to Kakadu National Park, near an area listed as Wetlands of International Importance under the Ramsar Convention and recognised under the World Heritage Convention. In the late dry season of 1998 and prior to the 1998 - 1999 wet season, a stream-monitoring program was implemented in the Ngarradj catchment to collect baseline data on sediment transport within the catchment to assess and proactively manage associated impacts caused by mining at Jabiluka. Stream suspended mud concentration, stream discharge and rainfall data were collected for four wet seasons (1998 - 2002) giving an almost continuous data set. The stream system has high natural variability dependent on rainfall intensity and subsequent discharge and pre-wet season fire distribution and intensity. In general, mud concentration is elevated at the commencement of the wet season until about February. This is caused by first-flush removal of surface material detached during the dry season by agents such as bioturbation (including anthropogenic activity), wind erosion and surface desiccation. Water quality trigger values downstream of the mine were derived using upstream percentiles and the before-after-control-impact, paired site design. Both analyses showed no observable impact from mine construction in 1998 or during the study period. However, the impacts of dry season fires could be clearly detected. The data set provides good baseline information for future assessment at Jabiluka and demonstrates the need to view measured parameter values on a catchment-wide basis with knowledge of rainfall, discharge and fire distribution.

Jan 1, 2004

By D J. Black

Ventilation modelling is used to evaluate ventilation system performance. This paper describes modelling to assess potential changes to a single entry longwall ventilation circuit to improve ventilation and gas management. The longwall panel is extracting a 215 metre face in a 1.5 metre coal seam at a depth of 900 to 1000 metres below surface. The 1.5 metre B seam is located approximately 25 metres below the main 3.0 metre A seam and the gas content of both coal seams is approximately 20 to 25 m3/t. The B seam is extracted prior to the A seam and the mine relies on fracturing of the overlying strata to induce gas emission from the A seam to reduce the gas content prior to mining. Longwall operations in the B seam are constrained by limited ventilation and high gas emissions. Due in part to statutory limits on gas concentration and air velocity, the average longwall production rate is approximately 700 t per day.Gate roads in the B seam are single entry, developed using road headers and supported with steel arches. Additional timber cog support is installed to reduce roadway closure from abutment loading. Due to the slow advance of gate road development, mine management were reluctant to consider significant mine design changes, such as two heading gate roads; therefore, the investigation focused on determining the extent to which ventilation and gas emission impacted on longwall production performance, while recommending short-term, low-cost actions to improve ventilation and gas management to support increased longwall production.CITATION:Black, D J, 2017. Application of modelling to improve ventilation and gas management in a single-entry longwall panel, in Proceedings Australian Mine Vent Conference 2017, pp 239–244 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By O K. Paki

A 14/12 millMAXTM pump was installed in the SAG1 grinding circuit as a trial replacement for the existing 12/10 Warman for performance comparison and in an attempt to overcome process difficulties. Krebs Engineers have developed the millMAXTM pump wet end to adapt to a variety of power frames. This system has been developed specifically for coarse material contained in mill discharge. SAG1 discharge screen undersize with a top size of 10 mm is collected in a flat bottom sump. Two 12/10 Warman pumps located on the same side of the sump, pump the screen undersize at 50 to 65 per cent solids to a distributor box which splits into two separate ball mill circuit sumps. One pump is installed towards the screen feed, while the other is towards the screen oversize discharge. The pump located towards the screen oversize discharge is prone to continual operating problems including pump bogging, high impeller and casing wear, and has consequently restricted SAG mill throughput. To rectify this pumping problem, it was decided to change-out the wet end of this pump with a millMAXTM. The design of the new pump enabled the wet end only to be retrofitted to the existing Warman pump frame, thus reducing change-over time. This was undertaken in the workshop under the supervision of a company representative where the pump, complete with bearing frame, new wet end, motor and base frame, was assembled. After installation of the millMAXTM pump during a SAG mill shutdown, performance indicators including motor power draw, sump level, and pump discharge pressure have been monitored. The trends indicate an increase in discharge pressure, low sump level, and low motor power draw. With the improved pumping efficiency there has been minimal pump bogging and no consequent SAG mill throughput restrictions. Pump wear rate has also decreased.

Jan 1, 2000

ITSL Technology group employs around 100 people at Mississauga in Canada. Its long and proud history as a driving force for the worldÆs nickel industry continues, progressively adapting to meet IncoÆs ongoing development needs. The nickel industry, unlike many others in the minerals processing world, has not evolved into one or two narrow technology paradigms. Rather, each process requires a degree of optimisation to meet the characteristics of the ore. Without a competent team to address this complexity, the uncertainties that arise can greatly increase the risk (and costs) associated with the nickel industry developments. The development work carried out at ITSL Technology ranges from milling and metallurgical processing of ores through to development of value added products for the battery and electronics industries. It covers routine evaluation of ores for exploration (mine planning and greenfield), and provides on the ground support to bring specialist technical perspectives to site-based projects. In recent years, ITSL Technology has had as its particular focus the process development and commissioning support for IncoÆs major projects. Over the next several years, Inco will commission its Goro laterite operation, design and construct the further processing facility for VoiseyÆs Bay, undertake major upgrades at Sudbury, Thompson and PT Inco, and bring forward some additional resources currently in the exploration stage. The appropriate mix of both internal and external resources to effectively manage this project portfolio will prove critical to success. The key to ITSL Technology meeting these development challenges has been in working closely with its internal customers to ensure alignment of the value proposition, to identify the critical issues to be managed, and to understand the deliverables required. This paper discusses examples to reinforce these principles in the definition and development for two different projects; processing of VoiseyÆs Bay ores and concentrates and resource optimisation at Thompson.

Jan 1, 2006

By O Salisbury

Ingress of air into the longwall goaf environment needs to be managed appropriately to reduce the risk of creating a spontaneous combustion event. The maingate goaf edge is an area of particular concern in this respect, as air often penetrates for some distance into the goaf along this region inbye of the longwall face. Since the flow rate in this part of the goaf is also quite low, an opportunity exists to disrupt the air pathway by implementing a barrier to the airflow. Previous attempts using plugs made from an assortment of materials have resulted in varying degrees of success. More recently, Narrabri Coal Operations (NCO) has introduced the use of a chemical foam that is mixed with nitrogen to produce a standing barrier with the consistency of shaving cream. The implementation of this practice has consistently proven to be very effective for reducing the oxygen concentration along the maingate goaf edge by systematically retreating the foaming unit with the longwall. This paper presents how the foam is applied in the underground goaf environment to prevent oxygen ingress and uses results from gas monitoring to confirm the foam effectiveness.

Oct 12, 2022

A sequence of ultramafic units, very well exposed in Munro township in the Abitibi areal, of the Cahadian Shield, exhibit features which indicate that they are sub-aqueous extrusions. They occur within a sequence of tholeiitic pillow lavas, thin graphitic sediments. and large differentiated sills. The units range from a few metres to more than 250 m in length and less than 1 m to over 30 m in thickness. Over 60 individual units, occurring as flat pancakes on top of one another, make up a total exposed thickness of 150 m. The units have formed from a magma composed of a very olivine-rich picritic liquid carrying up,to 40 per cent olivine phenocrysts in suspension. Different units display a variety,of cross-sectional profiles. As an example of the most extreme type of profile, a typical unit 2 m thick consists of a cap of highly jointed fine-grained quenched rock, 10-30 cm thick, which becomes coarser downwards, grading into a zone composed of radiating and criss- crossing skeletal olivine crystals forming the well-known spinifex texture. This becomes even coarser-grained downwards, with "books" of parallel platey olivine crystals developing sub-perpendicular to the plane of the units. Beneath this zone, which may be up to 1 m thick, there is an abrupt transition to a cumulus-textured rock composed of rounded

Jan 1, 1973

By Bicer N

Current problems in predicting sub-surface strata movement and fracture development due to longwall mining have highlighted the need for more accurate, dependable methods of physical modelling of rock mechanics problems which are beyond the capabilities of current mathematical techniques. Physical model studies of the caved zone above the working faces up to the base of a water source are of importance in attempting to understand changes in mass permeability due to induced fracture zones and the resulting ground water conditions. Turkey's most important supplies of coking coals are to be found within the hard coal resources of the Black Sea coast. Coal seams up to 9 metres thick, dipping at angles as steep as 90 degrees are being successfully mined at the Kozlu Mine. Since 1956, mining operations have been carried out under the sea in dry conditions. The undersea mining conditions of the Kozlu Mine have been investigated using scaled physical models constructed from artificial materials which satisfied necessary scaling requirements. Models representing the in-situ conditions were tested and the following extraction sequence was employed: 1. The Sulu Seam extraction 2. The Acilik Seam extraction (as two slices) 3. The Piric Seam extraction. The displacement of the fixed reference points were subsequently measured using a high precision photogrammetric technique and induced horizontal and vertical strains were calculated.

Jan 1, 1988