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By J. Petersen, K. Shaik

The traditional route utilised for the recovery of Platinum Group Minerals (PGMs) in South Africa involves the concentration of ore by flotation, followed by smelting to produce a PGM rich matte, which is then digested hydrometallurgically to solubilise base metals and Platinum Group Elements (PGE). HCl/Cl2 is conventionally used for PGE dissolution from concentrated material, which is an aggressive reagent associated with high maintenance costs as well as environmental concerns. Of interest is the leaching of PGMs directly from mineral ores, low grade concentrates and tailings in a cyanide-ferricyanide system as a more sustainable alternative. This system has shown favourable Pt recoveries among the Pt minerals, but with sperrylite (PtAs2) displaying highly refractory behaviour. The dissolution of sperrylite is investigated in a cyanide-ferricyanide system in the context of an electrochemical study involving OCP, chrono-amperometry and cyclic voltammetry. This approach allows the assessment of leaching characteristics as well as the investigation of surface passivation, which is believed to contribute to poor Pt recoveries. Some evidence is presented that such passivation is related to the formation of arsenide species on the mineral surface. Keywords: Sperrylite, PGMs, cyanide, ferricyanide, electrochemistry

Jan 1, 2020

By Michael J. Messel

The critical shortage of asbestos fiber in the world today brings to the foreground the question of locating and developing new deposits. The object of this paper is to discuss some of the more important factors which should be considered in the examination and valuation of a new asbestos enterprise. Some of the more important uses of asbestos fiber are for textiles, heat insulators, building materials, filters and a series of other uses. The properties of this mineral, such as fibrous structure, color, strength, silkiness and flexibility, coupled with resistance to fire, certain chemical action and decay make its application unique for certain industrial uses which consume over 500,000 tons annually. These same unique properties which make this mineral so valuable also make a deposit one of the most difficult to appraise accurately, because of the many undeterminable and varying factors which must be considered before a deposit can properly be termed commercial. The majority of the asbestos fiber today, having the above mentioned properties, is sold by grades which are based on fiber length. Present day fiber prices vary over a wide range from $800 to $225 for crude fibers and $300 to $20.00 per ton for milled grades. For valuation purposes a careful study should be made of existing fiber prices and markets. Examination of Deposits In carrying out prospecting and examination of a deposit, considerable caution is required to get the necessary information in the form that will have the most value for the final determination. There are two main classes of asbestos fibers, chrysotile and the amphiboles, the chrysotile being, by far, the most important both in abundance and uses. This paper will stress mainly chrysotile deposits, however, the amphiboles have many important uses, especially amosite and crocidalite. Their valuation presents special problems as other factors may be involved, especially as they are not graded according to any well defined and adopted standard but usually according to the use for which they are being supplied. Most chrysotile deposits occur in two main types of rock, (I) mainly in basic igneous, such as dunite and peridotite, (2) to a lesser extent in sedimentary rocks, such as dolomite and limestone. All of these require a certain degree of metamorphism to be favorable to asbestos formation. Approximately 90 pct of the asbestos deposits are derived from serpentinization of dunite or peridotite, whereby the magnesium-silicate olivine was altered to hydrous magnesium-silicate serpentine. Under certain favorable geological conditions, this serpentine takes a fibrous form having a definite crystal structure, probably due to molecular rearrangement, and is known as chrysotile. The fiber veins are usually ir-

Jan 1, 1948

By Michael J. Messel

The critical shortage of asbestos fiber in the world today brings to the foreground the question of locating and developing new deposits. The object of this paper is to discuss some of the more important factors which should be considered in the examination and valuation of a new asbestos enterprise. Some of the more important uses of asbestos fiber are for textiles, heat insulators, building materials, filters and a series of other uses. The properties of this mineral, such as fibrous structure, color, strength, silkiness and flexibility, coupled with resistance to fire, certain chemical action and decay make its application unique for certain industrial uses which consume over 500,000 tons annually. These same unique properties which make this mineral so valuable also make a deposit one of the most difficult to appraise accurately, because of the many undeterminable and varying factors which must be considered before a deposit can properly be termed commercial. The majority of the asbestos fiber today, having the above mentioned properties, is sold by grades which are based on fiber length. Present day fiber prices vary over a wide range from $800 to $225 for crude fibers and $300 to $20.00 per ton for milled grades. For valuation purposes a careful study should be made of existing fiber prices and markets. Examination of Deposits In carrying out prospecting and examination of a deposit, considerable caution is required to get the necessary information in the form that will have the most value for the final determination. There are two main classes of asbestos fibers, chrysotile and the amphiboles, the chrysotile being, by far, the most important both in abundance and uses. This paper will stress mainly chrysotile deposits, however, the amphiboles have many important uses, especially amosite and crocidalite. Their valuation presents special problems as other factors may be involved, especially as they are not graded according to any well defined and adopted standard but usually according to the use for which they are being supplied. Most chrysotile deposits occur in two main types of rock, (I) mainly in basic igneous, such as dunite and peridotite, (2) to a lesser extent in sedimentary rocks, such as dolomite and limestone. All of these require a certain degree of metamorphism to be favorable to asbestos formation. Approximately 90 pct of the asbestos deposits are derived from serpentinization of dunite or peridotite, whereby the magnesium-silicate olivine was altered to hydrous magnesium-silicate serpentine. Under certain favorable geological conditions, this serpentine takes a fibrous form having a definite crystal structure, probably due to molecular rearrangement, and is known as chrysotile. The fiber veins are usually ir-

Jan 1, 1948

By G. A. Moore, D. W. Williams, C. E. Sims

During the past several years, the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture, and the ductility values can often be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging. The cure of such an abnormal condition represents a real improvement in the quality of the steel. Several types of abnormal loss of duetility can be distinguished, of which those caused by excessive amounts of inclusions of undesirable type and those caused by unsuitable grain size and inget structure are well known. The particular type of abnormal lowered ductility currently under consideration may be distinguished by the fact that the low-temperature aging treatment necessary for its relief is insufficient to cause any visible change in the micro-structure as ordinarily observed. As this aging will in fact eventually occur at room temperature, the phenomenon of present interest may be given the symptomatic definition, ''Temporary Abnormal Low Ductility." Some hundreds of previous investigations, largely qualitative in nature, have established, beyond reasonable doubt, that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary abnormal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, The Steel Founders' Society of America has, since Nov. 1, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-duetility effects and porosity. The interest of this investigation thus extends to permanent abnormal losses of ductility, such as are caused by the inclusions which sometimes result from special deoxidizing practices and possibly from metallic nitrides, but as these can he distinguished from the temporary effect of hydrogen, they have been excluded from the work reported here except when they

Jan 1, 1949

By C. E. Sims, G. A. Moore, D. W. Williams

During the past several years, the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture, and the ductility values can often be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging. The cure of such an abnormal condition represents a real improvement in the quality of the steel. Several types of abnormal loss of duetility can be distinguished, of which those caused by excessive amounts of inclusions of undesirable type and those caused by unsuitable grain size and inget structure are well known. The particular type of abnormal lowered ductility currently under consideration may be distinguished by the fact that the low-temperature aging treatment necessary for its relief is insufficient to cause any visible change in the micro-structure as ordinarily observed. As this aging will in fact eventually occur at room temperature, the phenomenon of present interest may be given the symptomatic definition, ''Temporary Abnormal Low Ductility." Some hundreds of previous investigations, largely qualitative in nature, have established, beyond reasonable doubt, that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary abnormal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, The Steel Founders' Society of America has, since Nov. 1, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-duetility effects and porosity. The interest of this investigation thus extends to permanent abnormal losses of ductility, such as are caused by the inclusions which sometimes result from special deoxidizing practices and possibly from metallic nitrides, but as these can he distinguished from the temporary effect of hydrogen, they have been excluded from the work reported here except when they

Jan 1, 1949

By M. K. Seguin

The study described in this paper is first centered on the determination of the physical properties (gravimetric, magnetic, electrical, and electromagnetic) o f metamorphosed iron ores of the Carol Lake-Labrador City District. Different geophysical surveys available in the Carol Lake-Wabush area were interpreted quantitatively and the dimensions, attitude, and tonnage of the ore bodies investigated were determined. A geophysical-statistical study was undertaken which permitted the determination of the grade of iron, magnetite, and, subsequently, specularite in the ore bodies. A discussion of the theory and logical progression of the study and the application of the results to actual geophysical data is presented. The conclusions, which are of real significance from the economic standpoint, may be predicted from the data obtained from geophysical surveys before any diamond drilling is undertaken. An integrated interpretation of this type is useful in planning future exploration work and selecting the most favorable geological structures. It also serves as a guide to minimize and determine tonnage drilling patterns. The general conclusion that a restricted range of residual gravity and magnetic anomalies are a key to exploration is valid. Indeed large depths to the top of deposits are absent since all the ore bodies are overturned synclinal structures with tops located close to the surface. Certain irregular geometries do occur but they are not common and the alignment of the iron ore bodies is sub parallel so that magnetic anomalies are evenly reduced in the earth's magnetic field vector.

Jan 1, 1975

IN carrying out experiments to determine the amount of metal taken away by fume or fine dust the apparatus used requires to be strong and compact, as it is generaIIy necessary to work on a staging fixed at considerable distance above the ground and against a smoke stack or flue. It is essential that the test be carried out at a part of the stack welI away from any bends, to prevent eddies. The method described below has been used for estimating the dust losses from Dwight & Lloyd sintering machines, antimony drossing furnaces, pot sintering trials, etc., and has been founc! satisfaetory. It is welI to bear in mind that the longer the period over which dust coIIection is extended, the more valuable the result is likely to be. The rateof aspiration of the gases through the apparatus is kept as regular as possible by changing the filter thimbles frequently, and the rate of flow should correspond closely with the rate of flow of the gases up the stack.The apparatus required for carrying out a test is as folIows :-{a) Thermometers : two are required, one for taking the temperature of the gas in the stack and one for giving the temperature of the gas in the aspirating drum. If the temperature in the stack is over 400° C., it is advisable to use a pyrometer such as the "Bristol" the couple being standardized before use at about the temperature of the stack.(b) Pilot Tube: The foIIowing sketch (Fig. 1) iIIustrates the principle of the pitot tube. The readings are to be taken in a straight flue, or stack, preferably 20 diam. away from any bend. A, which is open, faces the air current and...

Jan 1, 1922

By J. F. Hutwelker

A pilot plant was constructed and operated to investigate the column flotation of 20 x 200 mesh North Carolina phosphate ore, using high throughput, high solids operating conditions developed at the NCSU Minerals Research Laboratory. Flotation was performed at 45% solids in a 9.5 cm (3.75 in.) diameter by 2.26 m (7.4 ft.) tall column at throughputs of 19.1 t/hr/m2 (2.0 stph/ft2) and 31.7 t/hr/m2 (3.3 stph/ft2). Recoveries in excess of 98% of the phosphate value were obtained at the lower throughput -- while obtaining concentrate grades containing over 28% P205 (61.2% BPL) at that recovery. Recoveries of about 95% of the phosphate value were obtained at the higher throughput, while making a concentrate averaging 27.6% P209 (60.3% BPL). In addition, a better understanding of the variables governing the column flotation of coarse nonmetallic minerals was gained. Low air flow rates adversely affected concentrate grade at the lower throughput. At the higher throughput, phosphate recovery decreased at an elevated air flow rate. An unexpected result of the study was the effect that frother type had upon phosphate metallurgy. Use of Nottingham Econofroth 925 provided better flotation selectivity than American Cyanamid F-65 at the low throughput. This is significant since the high' throughput tests were conducted with F-65 exclusively. It is reasonable to expect further improvement in high throughput performance when the optimal frother type and dosage are determined.

Jan 1, 1993

By H. C. Stumpf, L. A. Willey, V. L. Fink

Very few studies of the aluminum-sodium system have been reported. Heycock and Neville1 were unable to detect any solubility of sodium in liquid aluminum. Mathewson2 prepared an equilibrium diagram consisting of two horizontal lines at the melting points of the two metals. He was unable to detect solubility at either end of the system. Scheuer3 first developed a method for the chemical determination of sodium in aluminum and then studied the solubility of sodium in liquid aluminum. His method involved heating aluminum with excess sodium under hydrogen until the two liquids were at equilibrium, chilling the melt, and analyzing the aluminum-rich layer. He reported the solubility to be 0.10 pct sodium at 700°C, 0.115 pct at 750°C, and 0.128 pct at 800°C. This paper on the aluminum-sodium system is the twenty-first in a series from the Aluminum Research Laboratories describing equilibrium relations in aluminum alloy systems. Materials The alloys for this investigation were prepared from electrolytically refined aluminum (99.99 pct) and sodium of reagent quality conforming to specifications of the American Chemical Society. Chemical analysis of the aluminum showed the fol- lowing impurities: 0.002 pct Si, 0.002 pct Fe, 0.002 pct Cu, <0.001 pct Mn, 0.002 pct Mg and 0.001 pct Na. The sodium content of all alloys was determined by either chemical or spectro-graphic standard procedures5 No. IIA and No. SI I respectively. Determination of Miscibilitv The boundary of the miscibility gap was determined by a modification of the method of Scheuer3 and of that used by Henry and Cordiano. As finally developed the method was as follows: A fused alumina crucible 25 mm id with 75 mm depth and 1.5 mm wall thickness was placed on the bottom of a container made from a 4-in. length of 1 1/2-in. iron pipe and pipe caps. ?&apos;he space around the sides of the crucible was filled with 40 mesh crystalline alun-dum. A charge of 60 g of aluminum and 10 to 15 g of sodium was placed in the crucible, the sodium first being trimmed and rinsed with iso-pentane to remove kerosene. The container was tightly capped, filled with argon (99.6 pct pure), and heated to the desired temperature (between 670 and 800°C). A positive pressure of argon (about 8 mm of mercury) was maintained through a small pipe to the upper cap. After soaking for from 2 to 5 hr, the container was quenched by directing a stream of water onto the base, so that solidification of the aluminum-rich layer was rapid and essentially unidirectional. Analyses were made on drillings taken from the bottom of the ingots after machining off the surface layers. Pre-

Jan 1, 1949

By Ekkehart Mertins, Hans-Dieter Wasmuth

During the last years many new concepts have been presented for magnetic separation of feebly magnetic minerals by using the new high-duty permanent magnetic material especially in Open Gradient Magnet Systems (OGMS). In this respect KHD Humboldt Wedag AG developed an improved version of a drum-type magnetic separator called PERMOS® with a special magnetic field configuration for the NdFeB permanent magnets, which gives a magnetic field strength of at least 0.7 Tesla and a wide working zone outside the drum. The magnet system within the PERMOS® unit is no longer made of relatively large magnet blocks of alternating radial magnetisation; the system is now made up of a multitude of small NdFeB bars with a specially oriented magnetisation. This PERMOS® Open Gradient Magnetic Separator can be used for dry magnetic separations in "top-feed" and &apos;free-fall" feed configuration as well as in the conventional wet "drum-type" feed mode. It allows high throughput rates of up to 40 metric tons of solids per hour and meter of drum length without any clogging problems, even when strongly magnetic com-pounds are present in the feed material. The important design features and the actual machine characteristics of the improved PERMOS® units for dry and wet magnetic separation are described and typical examples for their commercial application for industrial minerals and for martitic iron ores are presented.

Jan 1, 1995

By E S. B Santiago, C P. N Moreto, L V. S Monteiro, G H. C Melo, R P. Xavier

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Iron oxide-copper-gold (IOCG) systems of the Carajás mineral province (Amazon craton, Brazil) are structurally controlled by regional-scale shear zones and have formed by multiple episodes of fluid circulation and hydrothermal alteration in the Neoarchean (2.71–2.68 Ga and 2.56 Ga) and Palaeoproterozoic (1.90–1.87 Ga).Collectively, fluid inclusion, boron, oxygen and hydrogen isotope data and Cl/Br–Na/Cl ratios in fluid inclusions reveal that regional circulation of non-magmatic brines (eg evaporative fluids/evolved sea water) and mixing with other fluid sources (eg meteoric or magmatic) is an important attribute in the genesis of the Carajás IOCG systems. The ?33S and d34S compositions of sulfides from the Neoarchean and Palaeoproterozoic IOCG systems suggest that the ore-bearing fluids have assimilated sulfur from crustal reservoirs. Nevertheless, most ?33S measurements have indicated mass independent fractionation (MIF) effect for both systems which points to the possible involvement of surface sulfur sources.CITATION:Xavier, R P, Monteiro, L V S, Moreto, C P N, Melo, G H C and Santiago, E S B, 2015. Non-magmatic versus magmatic fluids in the genesis of Archean and Palaeoproterozoic iron oxide-copper-gold systems of the Carajás Mineral Province (Brazil), in Proceedings PACRIM 2015 Congress, pp 281–288 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By J Krnmmelbein, T Raab

In Lusatia, lignite mining causes major disturbances on the landscape scale. Reclamation procedures are applied to recover the reconstructed landscape for different land use options. In this study we investigate soil physical properties of an agricultural reclamation/recultivation site directly after site restoration and the development of selected parameters within the first years after site restoration depending on varying recultivation strategies.The sandy substrates used for recultivation stem from depths of several meters. They are unstructured, free of recent organic matter and have high contents of calcium carbonate. During reconstruction and most of all during surface levelling with heavy crawlers, the substrate?undergoes high mechanical stresses. This leads to partly severe soil or substrate compaction, depending amongst others on substrate water content and mechanical stresses during site construction. We investigate the effect of different organic soil amendments, different crop rotations and partly subsoiling on the development of soil structure. We compare results of laboratory measurements directly after site construction before any reclamation measures had been applied to results we gained after three and four years of recultivation. The results show that after the earthworks are completed, the site is strongly heterogeneous in relation to mechanical stability, permeability for air and water, pore volume and bulk density. The results after three and four years show that the heterogeneity of soil physical parameters decreases. The selection of suitable crop rotations superimposes the affects of other reclamation measures, eg varying organic fertilisers or deep loosening.CITATION:Krnmmelbein, J and Raab, T, 2012. Reclaimed lignite mining areas A73 in Lusatia - Development of soil physical parameters of an agricultural site within the first years after site reconstruction, in Proceedings Life-of-Mine 2012 , pp 117-122 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

Controlled Source Audio Magnetotelluric (CSAMT) surveys were carried out by Glass Earth (New Zealand) Limited (Glass Earth) in 2006 - 2007 to investigate epithermal gold targets in the central North Island of New Zealand. The surveys were conducted using a Zonge GDP 32 8-channels receiver and a Zonge XMT 32 transmitter powered by a 16 KW generator. The electric field dipole was maintained at 20 m length (five dipoles per 100 m spread) and the frequency ranged from 4 KHz to 4 Hz. Only scalar (TM mode) signals were recorded, using one magnetic coil per spread. The transmitter bipoles were 1 - 4 km in length and located about 5 to 10 km from each survey area. &nbsp; Sixteen individual target areas were surveyed by June 2007. The CSAMT survey lines (100 - 400 m spacing) were determined mainly on results from previous ultra-detailed airborne magnetic and gravity surveys conducted by Glass Earth in 2005. The data from each CSAMT line was carefully examined to remove any spurious signals and processed using Zonge SCS2D software, which can produce smooth 2D resistivity inversions of the field data. The results were presented as resistivity sections and maps to help the identification of exploratory drilling targets, mainly from the existence of subsurface high resistivity zones (resistors) that can be interpreted as caused by silicification associated with epithermal mineralization. &nbsp; An example of processing and interpretation of the CSAMT data is presented in this paper on results from Glass EarthÆs Tahunaatara target, where CSAMT surveys have identified zones of epithermal mineralization confirmed by exploratory drilling.

Jan 1, 2007

By Enzo Angeles, Desmond Nanchengwa, Lee Julian, Julian Ruiseco

Since the early 1980s, surface hard-rock mining companies have searched for a blast movement model to enable grade control optimization efforts. Significant time and money were spent attempting to create blast simulations to aid post-blast grade control. Despite nearly 40 years of effort, practical blast movement models remained elusive until computing power reached levels that make real-time simulation possible. From the mid-1990s, mines have been creating in-situ grade control polygons and translating the polygon nodes horizontally to account for blast movement. In many cases, objects are placed in the blast volume and located post-blast to provide local vectors for these node translations. This method was always a compromise between practicality (2D) and reality (3D), but it was the only viable solution that matched the needs of operations. This study considers 21 blasts and evaluates the incremental value achieved by new processes unlocked through 3D modelling, while investigating challenges, limitations, and opportunities for each method.

Jan 1, 2023

By T A. Short, P L. Brown

Kestrel Mine co-disposes around 1.5 Mt of fine (2SO4/t and to date around 9 Mt has been deposited. The mine plans to co-dispose of approximately 39 Mt of material, creating a dump with a maximum height of 35 m and a disturbance footprint of 260 ha. Benign materials suitable for rehabilitation are severely limited and no successful rehabilitation strategy has yet been demonstrated. A rigorous measurement and modelling program is resolving outstanding issues associated with acid rock drainage (ARD). The objective of the program is to develop and validate a strategy for dump rehabilitation that will control ARD and allow for mine closure. The strategy includes using a soil cover to reduce water flux into the dump to control the overall oxidation rate and to control effluent release. Monitoring of the oxygen distribution and water flux in the uncovered material commenced in February 2001 and monitoring in waste under a trial cover commenced in February 2002. Carbonaceous and sulfidic oxidation rates have been measured. Initial modelling indicates that the carbonaceous material has the general effect of slowing the rate of pyrite oxidation, lowering the maximum sulfate production rate and extending the time to oxidise all the sulfides. The combined approach of measurement and modelling provides a sound basis for assessing the performance of the trial cover and predicting the long-term quality and quantity of effluent at the base of the rehabilitated waste dump.

Jan 1, 2003

By K. Holmberg, D. Herriot

This paper by Mr. McIvor is yet another contribution to the eternal controversy surrounding the benefits, or otherwise, of high circulating loads in closed circuit grinding. Throughout the paper it is difficult to establish whether the author is referring to effects relating to the mill, classifier, or to the overall circuit. Table 1 is put forward as indicating the advantage of operating at high circulating loads. From the two (it would be interesting to see more) product sizing points provided in each case, the conclusions to be drawn are that cases one and two have very similar size analyses. The third case, however, indicates a much flatter curve, that is to say, higher fines production and a very wide spread of size ranges. If the objective of this circuit is to provide a closely sized product with minimum overground slimes to the downstream process, then it would appear to be the less "efficient" by far. No data is given for product pulp densities either. The term "efficiency" should never be used without a careful and clear definition. In this case, "efficiency" is used to express an apparent percentage reduction in operating work index (Bond) from the measured "standard" at 250% circulating load operation. The Bond calculation is itself based upon

Jan 1, 1990

The copper and zinc contents of herbarium specimens of 11 of the 12 Australian species of Polycarpaea were determined in order to establish background and anomalous values of potential use in biogeochemical prospecting.Cumulative frequency curves were used to establish appropriate threshold concentrations for six species including the &quot;copper plant&quot;&apos; P spirostylis. Collection localities of Polycarpaea specimens with anomalous copper or copper-and-zinc values are under investigation.

Jan 1, 1978

By L Terrusi

The Bungaroo Valley hosts a concealed Tertiary channel iron deposit (CID) along a 17 km stretch of its length. Bungaroo Valley is approximately 0.5 km wide upstream at its easternmost extent, and 3.5 km wide downstream where it joins the Jimmawarrada Creek. The valley follows the axial trace of an anticline that plunges gently to the southeast, and the CID infills the valley. Mineralisation extends to a depth of 230 m below the surface, and almost the entire deposit occurs below the water table. Bungaroo Valley cuts through the Buckland Hills and is bounded to the north and south by steep scarps capped with the resistant Dales Gorge Member of the Brockman Iron Formation. Basement rocks are believed to be mostly Wittenoom Formation shales and dolomites, with Mount McRae Shale and Mount Sylvia Formation also present. Deep, localised depressions appear at the base of the CID sequence towards the north edge of the upstream section of the valley, while downstream the basal CID contact is relatively flat and shallow. In both cases the profile of the CID surface closely mirrors that of the basal contact. The localised depressions seen in the upstream basal CID contact produce significant variations in CID thickness of up to 100 m over short strike distances. This uneven palaeotopography is most likely due to eddying and waterfalls forming within the riverbed prior to CID deposition during a time when the water table was much lower than at present. It may also be associated with possible karsting in an underlying dolomite unit and subsequent syn- or post-depositional collapse of the overlying CID. The irregular basal contact of the Bungaroo CID sequence has implications for mining in terms of pit design and resource accessibility.

Jan 1, 2007

By Monique Nykamp

"INTRODUCTIONTerminal 46 is located just south of downtown Seattle, and is one of the Port of Seattle’s busiest container terminals. The Terminal 46 Redevelopment Project was undertaken to replace the existing 15-m-wide (50 ft) cranes along the apron with 30-m-wide (100 ft) cranes, which can unload larger, post- Panamax ships. The project included upgrading the existing waterside crane rail with new piles and constructing a new land-side rail behind the sheetpile bulkhead. The new piles had to be installed adjacent to the existing apron without causing damage, which was a signifi cant geotechnical challenge due to the soft soil conditions at the site. An instrumentation program performed during the test pile program evaluated this challenge and allowed for the development of specifi c production pile installation procedures that had the least possible effect on construction costs and schedule. SITE HISTORYThe site lies along the west side of Elliott Bay, north of the mouth of the Duwamish Waterway. Prior to development, this area was part of the tide fl ats where the Duwamish River drained into Elliott Bay. Prior to 1970, there were several existing timber piers and structures in the area. In the 1970s, the Port of Seattle constructed a 900-m-long (3,000 ft), 30- m-wide (100 ft) apron to support fi ve, 15-m-wide (50 ft) container cranes. The contained backland area was then fi lled with dredged spoils (sand and silt with organics) and the upper 5 to 20 m (16 to 65 ft) backfi lled with sand and gravel.The existing apron was constructed using 0.4 m (16 in) octagonal prestressed concrete piles to support the precast concrete deck and crane rails. The pile-supported bents were spaced at 6.1 m (20 ft), center-to-center, along the longitudinal direction. Pile lengths typically varied from about 20 to 40 m (65 to 130 ft) with 15 to 26 m penetration below mudline (50 to 85 ft penetration). The slope below the apron was constructed at about 1.75 horizontal to 1 vertical to allow for suffi cient water depth for cargo ships. In most areas, a riprap buttress was placed at the toe of the slope. A typical cross section of the apron is shown on Figure 2.Several stability, settlement and pile driving issues arose during the original construction of T-46 (Pita, 1983). Reportedly, movement of the submarine slope occurred during pile driving, resulting in settlement behind the bulkhead. Pile driving reportedly caused settlement of adjacent piles. In addition, some piles were “running” (dropping quickly under one hammer blow) during installation."

Jan 1, 2007

By O. Porterfield, M. O’Kane, M. Endersby

BHP Iron Ore initiated research programs in January 1995 to develop long-term plans for decommissioning waste rock material at its Mt. Whaleback operation. More than 2 Gt (2.2 billion st) of waste rock were deposited during the past 30 years. Ultimately, a total of 4 Gt (4.4 billion st) will be deposited in waste rock dumps constructed near the open pit. The Mt. Whaleback operation is located in a semiarid climate adjacent to Newman, Western Australia. The primary research program includes the development of technology for the long-term performance of the waste rock dumps with respect to vegetation, slope stability, surface runoff, erosion and water infiltration. This paper focuses on the design and implementation of a cover system to prevent water infiltration to the underlying waste rock. Data obtained from a laboratory program and from soil-atmosphere modeling was used to design horizontal field test plots. The construction of the horizontal surface field test plots is discussed together with the field instruments installed to monitor performance. The cover system is designed to maximize infiltration during wet periods for subsequent evapotranspiration while minimizing surface runoff. The result is a near-zero net infiltration to the underlying waste material. An important feature of the design is the use of run-of-mine waste material as the cover material. Monitoring is in progress and will continue for at least two annual wet/dry cycles. The optimum cover system should minimize the net infiltration of water to the underlying waste rock while maintaining physical and ecological integrity for long-term performance.

Jan 1, 2000