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By K. S. Mortensen

The softwall mining system is a novel, new method of mining mineral deposits in soft, shallow, nonrock ground conditions. This method can mine the ore layer without substantially disturbing the existing overburden. The softwall mining system consists of machinery that is hydraulically controlled and powered, that can be buried (or used on the surface) to extract the ore or mineral from a layered deposit. The method is essentially an application of the longwall mining concept, modified for loose overburden and ore conditions, combined with hydraulic mining.

Jan 1, 2003

By Lorenzo Pellegrini

The respect of EPB reference pressure during TBM advance and hyperbaric activities, the complete and effective filling of the annular gap between tunnel lining extrados and the excavation section and a well organized monitoring system, to control surface settlements and ground distortion, are items of utmost importance in EPB tunnelling process. The paper describes how these concepts have been applied while excavating in the difficult underground conditions found at Sao Paulo (Brazil) during the execution of the Sao Paulo Metro Line 4-Lot 1. In this project, the annular gap has been filled by two components type, cement grouting. The back feed of the extensive monitoring campaign carried out to check the surface settlements during the excavation and hyperbaric maintenance operations will also be described in the paper.

By Emöke Imre

A point-symmetrical linear coupled consolidation model with displacement boundary condition is suggested for the description of the consolidation around the pile tip after pile penetration. Analytical solution is given. Main features of the solutions are predicted by the analysis of the system of differential equations and, the boundary conditions.

Jan 1, 2002

Beaches contain the residue of eroded rocks which have resisted weathering, and it is common to find in all beaches some of the harder, heavy minerals. The natural sorting action of waves and winds tends to concentrate the heavy minerals into banded deposits.The value of such deposits is extremely variable. Even amongst the more concentrated deposits, the principal minerals, in the vast majority of cases, are magnetic, titaniferous magnetite and other forms of iron oxide, which, in the present state of mineral economics and technology, are of little or no value.Valuable minerals of fairly common occurrence in beach sand deposits are rutile, zircon, ilmenite, monazite and chromite, and each of these minerals, as well as others of less common occurrence, is obtained from beach deposits in various parts of the world.Along a stretch of 300 miles of coast from Coff's Harbour in New South Wales to North Stradbroke Island in Queensland, occur unique concentrations of heavy minerals. The principal minerals which occur are rutile, zircon and ilmenite, and for some years these deposits have contributed half to three-quarters of the world's consumption of rutile and zircon 1, ,2. The only other notable beach sand concentrations in Australia are at a number of places in the southwest of Western Australia, where deposits containing highgrade ilmenite are being developed.

Jan 1, 1950

By Harold Price

ONE year ago, that is in January, 1923, there had not been constructed a single oil-storage tank of 55,000-bbl. or more capacity with a completely electric welded roof and bottom. Today, there are at least fifty 80,000-bbl. storage tanks completed, or nearing completion, on which both the roofs and the bottoms are electric welded. It is the purpose of this paper to describe, in a general way, the construction of these FIG. 1.-ELECTRIC-WELDED SEAMS AND RIVETS OF BOTTOM IN 55,000-BBL. TANK AT EL DORADO, KANS., SHOWING ALSO PATCH PLATE WELDED TO BOTTOM. welded roofs and bottoms, and to give their advantages over riveted construction. All of the following data and conclusions were obtained from observations made during the welding of tanks by the Welding Engineering Co. at Texas City, Tex., and Tonkawa and Burbank, Okla. As far as can be determined, the first electric welding on large tankage was completed in May, 1922. At that time the Empire Companies of Bartlesville, Okla., discovered a badly leaking bottom in a 55,000-bbl. tank at El Dorado, Kans. They had considered concreting this bottom, but because of the much smaller cost, decided to try electric welding; so a- contract was given the Welding Engineering Co. of Bartlesville, Okla. In this instance, no new sheets were added, the bottom being repaired by electric welding of all seams and rivets, Fig. 1. In some places where the original rivets were missing, the holes were filled by welding; patch plates were also added at certain badly worn spots. This tank has since been in service over a year and half, but no other

Jan 6, 1924

By Paolo Cavalcoli, Marco Ziller

"ABSTRACT: In the year 2010 the State of Denmark together with the Municipality of Copenhagen, launched a very important and complex Project : the complete construction of a new double Subway Line :the CITYRINGEN.Copenhagen is the capital with a metropolitan population of 1,9 million.This line is like a ring placed in the very town center which includes all the most historical and monumental buildings and churches, with a total length of 17 km, and the presence of 17 stations plus 4 service shafts.The buildings have been built in the last centuries in an area where the groundwater is near to the surface and there are lakes and channels: the techniques adopted were advanced for those times, but limited as far as regards settlements and resistance to horizontal movements.The soil consists in 2 main groups.1.Upper sediments of the glacial ages : thickness total = 5-20 m composed by clay- silt-sand-gravelcobbles- granite boulders and flint in blocs and in layers : frequency and size of these obstacles wherenot determined.2.Limestone layers : 2a. upper limestone : highly fractured ,highly permeable2b.Itermediate limestone : less fractured, medium permeability.2c. Lower limestone : almost not fractured, low permeability.2d Bryozoan limestone : composed by fossils with microscopic dimensionsIn all the limestone formations there are important layers of flint , having thickness variable up to 3 m and important extensions. Water : in a part of the areas of the Cityringen the water is drinkable and utilized in the public waternet.Pollution: there are polluted zones due to previous industrial activities. Benzene areas have been identified, and for those areas special protections against pollution have been implemented.METROSELSKABET ,the public owner of the Cityringen,has set as priority to operate for the construction of the Cityringen the full protection of the environment and the respect of all the stakeholders :Very strong limits for the exhausted gas emissions have been introduced, by far stronger than those applied from the State of Denmark, very strong limits for the acceptable noise emission. And last but not least very important safety measures and procedure to avoid any accident on site."

Jan 1, 2014

Laboratory flotation tests on sized fractions of a certain number of selected minerals with homologous fatty acid derivatives (i.e. sodium salts and amine acetates) confirm that the higher homologues are more efficient collectors than the lower. Tests were carried out on sized material and finer size fractions floated at lower collector concentrations.It is suggested that selective flotation is best achieved with the reagent which most readily floats the most friable mineral in the ore, and that grade of product will be improved with the lowest usable homologue.INTRODUCTIONFlotation of non-sulphide minerals with fatty acids as collectors is usually less selective than the flotation of sulphide minerals with xanthate collectors. It is common to use the gradation in collecting power of homologous series of xanthates, as well as the more specific effects of activators and depressants, to achieve the separation of sulphides.The original aim of the work was to ascertain whether sodium salts of fatty acids (anionic) and fatty amine aceta:tes (cationic) could be selected from a homologous series to achieve better selectivity in separation of nonsulphide minerals by flotation. Subsequently the importance of friability of minerals in selective flotation was observed and the aim was expanded to develop a more practical approach to the testing of ore.MATERIALS USEDMineralsA series of massive mineral specimens, as pure as could be obtained, was procured. The specimens were cleaned by removing extraneous material, and then crushed and dry...

Jan 1, 1965

Except for uranium search, conventional oil well logging techniques are relatively little-used in mining exploration. The main reasons for this are cost and an apparent lack of awareness of the potential use of the methods in the search for ore. However, relatively inexpensive portable units are currently available for performing the simpler electrical and radiometric logs in diamond drill holes.The emphasis in oil exploration logging programmes is largely on the estimation of porosity. In most mineral work, however, porosity is not very significant, and factors such as mineral conductivity and radioactivity assume an important role.The Bureau of Mineral Resources (BMR) during a programme to explore for uranium and associated base metals in the area east of Rum Jungle, N.T., carried out electrical and radiometric logging of diamond drill holes as a routine part of their investigations. Case histories are described in which the logs were used to aid in defining stratigraphic sequences and transgressive structures in base-metal prospects. Some surface geophysicalanomalies were explained by the logging: induced polarization and electromagnetic anomalies were related to black slate; and self-potential anomalies were related to oxidation of pyrite black slate, or apparent electrokineticeffects in the black slate. The logs provided an objective appraisal of the rock units penetrated and thereby helped to differentiate lithologies.Borehole logging, including newer techniques such as downhole analysis, could be done in geological and geophysical investigations in other areas for a relatively small cost with a considerable potential gain of information.

Jan 1, 1978

By W. Pariseau, S. Puri, S. Schmelter

Introduction Joints often have profound effects on elastic properties and strength of rock masses and therefore on rock slope stability. In surface mine slopes, joints are usually too numerous to be taken into account individually, so an equivalent properties approach is necessary. Previous work that treats a jointed rock mass as an equivalent composite material of joints and intact rock between resulted in excellent agreement between estimated and true rock mass elastic moduli in case of fully persistent joints (e.g., Pariseau, 1999) Rock mass failure mechanisms on joints and through intact rock were retained obviating the need for an equivalent rock mass strength. Impersistent joints, which are not continuous on a joint plane, can be accommodated (Pariseau, 2003). However, slope stability analysis of a large, deep copper mine indicated a need for computational efficiency even in two-dimensional analysis of vertical sections through pit walls (Puri, 2006). The analyses by the popular finite element method used small elements of bench size near the pit slopes and much larger elements away from the pit walls. The reasons for the graded meshes were numerical quality (small elements) and computational economy (large elements). Small elements contained only a few joints, while the larger elements contained hundreds of joints and led to impractical computation run times (days!). A new modeling procedure that recognizes sufficiently large elements as representative volume elements (REV’s) overcomes this obstacle. A companion improvement recognizes the concept of a representative area element (RAE) in association with joint impersistence and the probability that joint material occupies a considered site. Both are steps towards greater model realism and a practical slope stability analysis procedure. Consider the open pit mine photo shown in Figure 1(a), a companion plan view in Figure 1(b), and the problem of slope stability where high slope angles favor economics but low slope angles favor safety. These competing factors in surface mining generally result in some sections of the mine that have unstable slopes that require monitoring and perhaps mitigating action to improve stability. Although stability of a given section may not be easy to quantify with a single number, useful design guidance can be obtained from a finite element analysis of a proposed mining sequence leading to future pit slopes and profiles. The presence of water from rain and snow melt indicates a need for a coupled analysis that links water pressure, effective stress and total stress (Schmelter, 2001).

Jan 1, 2007

By Green P. F

Apatite Fission Track Analysis (AFTA) is a thermal history reconstruction tool that enables determination of magnitude and timing of maximum paleotemperature and paleo-geothermal gradient at the time of maximum paleotemperatures. From this information, the amount of section missing at major unconfornities can be estimated and incorporated into basin models. The Gippsland Basin has a number of distinct problems that can be tackled using AFTA. 1. The nature of the regional break between the Late Cretaceous-Tertiary Latrobe Group and the underlying Early Cretaceous Strzelecki Group. 2. The tectonic history of the basement flanking the basin and its effect on sediment composition. 3. The age of igneous activity in the basin, as typified by the widespread basaltic plugs and dykes intruding the outcropping Strzelecki Group. Major uplift and erosion within, and adjacent to, the early Cretaceous rift basin in the Mid-Cretaceous, at -95 to 100 Ma, initially constrained the Latrobe Group depositional area to the central deep of the Gippsland Basin and provided an elevated source of quartz-rich detritus for the Latrobe Group reservoirs. This is in marked contrast to the preceding period in the early Cretaceous when contemporaneous volcanism dominated as a source of detritus, producing quartz-poor lithic sandstones, in which a host of attendant diagenetic reactions destroyed their reservoir potential. Initial uplift and erosion of the volcanogenic Strzelecki Group also occurred in the mid-Cretaceous as revealed by a number of distinct inversion structures, and erosion of this material will have locally provided very poor quality sand to the basal Latrobe Group.

Jan 1, 1992

Optimizing production scheduling in open pit mines is important for managing cash flows of mining operations. This paper describes a new, probabilistic, mixed integer programming (MIP) formulation which has been developed to minimize the risk of not achieving planned production targets, in terms of metal production and ore tonnage feed for the mill during production, while considering maximization of total discounted economic value. The new MIP model also recognizes that to minimize movement of excavators over long distances and accommodate equipment access, the blocks scheduled for mining within a period cannot be spread too widely. The model is applied to a laterite nickel-cobalt deposit, as an example of multi-element deposits that have complex ore quality constraints. The results show that the proposed model generates feasible schedules. When compared with traditional optimization techniques, the new model is superior in terms of minimizing the risk of not meeting production targets, especially at the early stages of production, and in terms of generating practical scheduling patterns.

Jan 1, 2006

THE Phillips River gold and 'copper field is situated on the south coast of Western Australia, about 200 miles east of Albany, 180 miles west of Esperance, and: 250 miles south of Southern Cross, forming the southern extremity of what Mr. H. P. Woodward classes as the fourth belt of Pre-Cambrian rocks, and the first auriferous belt, whicf extends northward through Southern Cross, Mount Magnet, and Cue. The field may be considered the premier copper producer of the State. The first mineral discoveries were made about 1892; when gold, copper, and iron pyrites were found; but, owing to the isolation of the district and the scarcity of water, both in the locality and on the route thereto, little work was done for some years. In1899, however, payable gold reefs were opened up, and the district began to attract attention.The southern portion of the district is composed of limestone and sandstone rocks, forming the coastal series, and is for the most part flat, broken only by a few low hills and ridges, except to the west, where Cape Barren and Eyre's Range stand out...

Jan 1, 1917

By J. Moore, D. Gault, R. V. Lugn

Impact of small projectiles with velocities between 0.9 and 7.3 km per sec on basalt produce craters chiefly by the ejection of fragments. Weight-size distributions of the ejecta are linear for part of the size range of the fragments. Cumulative weight-size distributions of the ejecta from different craters vary because of erratic formation of large fragments and a large percentage of ejecta below 0.1 mm. In the range of velocities studied, the crater depth is approximately proportional to the 0.75 power of velocity of the projectile. This relationship may represent a transition regime between the fluid impact regime and the undeformed projectile impact regime. The volumes per unit of projectile energy of the craters produced are comparable to those reported for lower speed projectile impact and drill bits. An experimental investigation of projectile impact on rock is being conducted jointly by the Ames Research Center of the National Aeronautics and Space Administration and the U.S. Geological Survey. Projectiles are launched with light-gas guns at the Ballistics Range of the Ames Research Center. The craters and ejecta produced in these experiments are being studied by the U.S. Geological Survey. Steel, aluminum and polyethylene projectiles weighing from 0.25 to 0.015 g were accelerated to velocities of 0.88 km per sec (2,900 fps) to 7.3 km per sec (24,000 fps) with a light-gas gun, using hydrogen as the propellant medium. Projectiles impacted the targets normal to plane rock surfaces in an atmosphere of air with a nominal pressure of 25 to 50 mm of mercury. The metal projectiles were mounted in supporting four-piece nylon sabots, which guided the projectiles down the launching tube. After launch, aerodynamic drag acted to separate the sabots from the projectiles. Impact velocities were determined with time measurements and spark photographs of the projectiles in flight. Ejecta were collected in lucite and aluminum containers placed around the target block. A small hole in the containers permitted projectile entry. Impact of projectiles of the size employed produced craters in the rock targets chiefly by ejection of fragments. The craters are small, roughly conical depressions with crushed and intensely fractured rock at the bottoms of the depressions. The ejecta are composed of pieces of the projectile and rock fragments ranging in size from a few tenths of a micron or less to several centimeters in maximum dimension. In this paper, the structural features of the craters, the weight-size distributions of the recovered ejecta, and crater depth and crater volume relationships are described. DESCRIPTION OF CRATERS Typical craters (Fig. 1) produced by experimental projectile impact in basalt are shallow, wide base

Jan 1, 1963

By Michel Massé

Eleonore Project- Agenda ? Purpose and Technical Overview ? SmartEXEC Control Capabilities ? SmartEXEC System Archetecture ? SmartEXEC System Advantage Eleonore Project- Purpose and Technical Overview ? Control air quality while maintaining target production levels at minimum energy operating cost ? Improve safety, work place conditions and operation flexibility ? Reduce energy consumption and green house gases footprint

Aug 1, 2013

By Roy M. Schnabel

The Fashion Island Boulevard Bridge over the Marina Lagoon in San Mateo, California is an eight span precast, prestressed concrete girder bridge. It is approximately 495 feet in length and 61 feet in width. It is supported on 36" diameter octagonal, hollow precast-prestressed concrete pile columns. The bridge was constructed in 1968 and suffered considerable damage during the Loma Prieta Earthquake in 1989. A damage survey report prepared by the State's Office of Emergency Services (OES) recorded that sixteen of the twenty-one pile-columns sustained heavy to moderate damage from the Loma Prieta Earthquake. The damage consisted of cracking and spalling at the tops of the pile-columns. Spalls at the most heavily damaged columns exposed the prestressing strands and confinement reinforcing which also showed signs of corrosion.

Jan 1, 1993

The sphere of operations of dry crushing has been so much enlarged of late years that the following notes with reference to its advantages and limitations, and also some practical results in connection with the crushing of gold ores will probably be of service to the members of the Institute. Until recently, with one notable exception that of the Mt. Morgan Gold Mine, dry crushing has only been practiced to a very limited extent in Australasia, and elsewhere it might be said to belong to industries other than mining Its sphere of usefulness depends on the fact that the' product is delivered in a dry state without the separation of the finer particles from the coarser to any appreciable extent, thus enabling the following advantages to be achieved with different ores.

By R. Kaushik

According to the U.S Department of Energy (DOE), mineral processing activities including comminution (size reduction) uses 4% of the world electrical energy consumption. Such numbers reinforce the need to invest in energy savings initiatives in order to produce more using less. ENERGY EFFICIENCY OPPORTUNITIES AND CHALLENGES IN MINING OPERATIONS In addition, DOE, in its Mining Industry Energy Bandwidth Study, has identified huge potential for energy savings for the coal, metals and mineral industries. Even knowing the overall causes of energy waste and some potential tools for remediation, mining companies may struggle to apply such tools and get the desired results due to the following reasons: ? Limited staff ? Lack of accurate economic and investment analysis to justify energy savings projects ? Lack of knowledge to identify low or no-cost savings opportunities ? Internal competition for resources According to the workforce and talent management experts, the Talent Strategy Advisors, the demand for mining engineers is expected to exceed supply by 30% by 2013. Mining personnel are likely to be burdened with increasing and varied workloads with limited training. This will result in the need for automated and simple tools to support energy efficiency activities. Mining engineers will simply not have the time and resources to create such tools, collect and analyze the data to make decisions, and track results.

Feb 27, 2013

By R Handfield, G Kary, Frieda Project

Recent exploration by the Cyprus Amax-Highlands Pacific-OMRD Joint Venture at the Frieda River project, PNG has demonstrated the extent of igneous phases, alteration and mineralisation, and the relationships between the various mineralisation styles in this major Cu-Au porphyry-epithermal system. The project area is in the obducted volcano-sedimentary section of the New Guinea mobile belt 78 km NE of Ok Tedi. It is between two major NNE dipping faults interpreted to have undergone thrusting then sinistral shear in the Late Miocene to Recent. The Frieda River Igneous Complex is a 15 km +7 km ovoid area with a central pod of basaltic andesite volcanics with cogenetic diorite to quartz diorite subvolcanic intrusions, and flanking clastic sediments. A series of late-stage, hornblende quartz diorite plugs ring the main igneous mass. The igneous rocks have a normal K calc-alkaline character with a very limited compositional variation. The intrusives are exposed on the eastern flank of the complex and have five mappable units and numerous defined phases. The southeastern quarter of the complex is host to a cluster of at least seven stockwork porphyry copper and skarn-hosted deposits within an area of 4.5 +3.5 km. The Horse-Ivaal and Koki deposits have identified resources totalling 804 mt @ 0.46 per cent Cu and 0.3 ppm Au, and the other deposits are in various stages of exploration. All these deposits are related to the Horse Microdiorite phase of the Complex and are outlined by a zone of potassic-propylitic-SCC alteration. Local overprinting argillic and advanced argillic alteration is related to a separate, post-porphyry mineralisation intrusive phase. The recent emphasis has been on the identification of higher-grade zones using ideas of structural control and specific intrusive-alteration-mineralisation relationships within the known resource areas. An elongate area 13 km x 4 km in the centre of the Complex has advanced argillic alteration in the volcanic rocks. This alteration zone hosts the Nena deposit (52.8 mt @ two per cent Cu and 0.7 ppm Au) and approximately 20 prospects of high sulphidation type. These deposits are distributed along two prominent NW-trending siliceous ridges interpreted as regional scale structures. Nena is a pod of vein and replacement sulphides hosted in a tectonically controlled multiphase breccia that overprints the advanced argillic alteration. The Nena deposit is 4 km from the nearest of the major porphyry occurrences. It is underlain by basemetal veins and minor porphyry mineralisation that are related to the Flimtem Trachyandesite intrusive phase. The recent search for additional Nena-type ore has focussed on the siliceous ridges using detailed structural and geochemical ore control criteria. Widespread, but poorly mineralised, basemetal-bearing carbonate and sulphate veins form a ring around the mineralised area. These veins have sericitic selvages, cut the porphyry mineralisation, but are cut by and locally underlie the silica-alunite phase of the advanced argillic alteration. The current model is that there are discrete intrusive phases responsible for each of major hydrothermal events at Frieda. These include from oldest to youngest:the Koki phase has no related alteration or mineralisation; the dominant Frieda phase has the hornfels, early skarn and minor magnetite-chalcopyrite mineralisation; the Horse phase has the bulk of porphyry copper and skarn-hosted mineralisation and minor basemetal veins; the peripheral Knob phase is barren; and the Flimtem phase has the high sulphidation epithermal deposits and minor porphyry and vein mineralisation. The intrusive phases span the interval 17 to 11.5 Ma and are co-magmatic. They represent discrete batches off the parent magma, rather than simple fractionation products.

Jan 1, 1999

By Khamis Y. Haramy

This paper summarizes ground control studies of longwall panel entry systems in two Western U.S. coal mines. Presented are comparisons of in situ pressure change measurements and assessments of chain pillar and entry behavior under a wide range of cover. Results indicate that no one entry system design is universally applicable, and that site-specific factors need to be considered for panel entry design. Relationships between overburden depth, face advance, and magnitude and location of the forward abutment are discussed for western operations. In addition, analysis indicates that use of yield pillars may reduce or eliminate some stress-related problems that plague longwall panel entry design.

Jan 1, 1989

By T. J. Goff

Keywords: accurate control, matte level, smelting operations, process control, tapping, sounding bar, electromagnetic measurement [ ] Accurate control of matte levels during primary matte smelting operations is desirable in order to improve process decision-making. High matte levels in the vessel could have to disastrous consequences, particularly in the new generation of intensive smelting furnace with deep-cooled copper coolers. Knowing when to commence tapping and a better understanding of melt times can only be improved if the furnace levels are monitored correctly. At Lonmin Marikana Smelter Division it has long been understood that the matte level information being provided by the manual sounding bar is only as good as the operators? following of measurement procedure, their skill in assessing what the sounding bar is displaying, and their individual interpretation of what they are looking at. This paper sets out to show how this problem was identified as an area of major concern to the plant, how a solution was sought and how an electromagnetic measurement system was installed as an alternative measurement to the matte sounding bar system. Other areas discussed in the paper are the difficulties to be overcome when first installing new equipment and how these teething problems were solved by close co-operation between Lonmin and equipment suppliers, which led to some design modifications to the delivery system. In conclusion the paper discusses the results between the electromagnetic measurement and the manual sounding measurement and how best to integrate the generated data into the plant?s process control system for improved decision making.

Jan 1, 2011