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By Wilfred P. Schmoe

Introduction An integrated oil company has two options in approaching strategic planning. It has to decide whether it is in business for the long-term. I state this in all seriousness. Those who help manage public companies have the responsibility of good stewardship of other people's money. We must decide whether continued investment in our basic business will generate a reasonable rate of return. With a world surplus of petroleum production capacity, and continuing downward pressure on prices, this question should be addressed by all oil companies. And a positive answer is not necessarily a foregone conclusion in all cases. The decision should be made based on proven competence in finding and developing petroleum reserves on a cost-competitive basis with other producers, and on a frank analysis of future prospects. This should include a realistic assessment of the projected rate of return on specific investment projects. If a company did not pass these tests, its strategy could take one of four paths. Diversification First, it could diversify. But recent history suggests that oil companies are not good at managing other businesses. Second, it could seek a buyer for its business at the optimum return for its owners. Third, it could sell its assets on a piecemeal basis. And, fourth, it could adopt a longer-range plan of self-liquidation by living off current recoverable reserves. In other words, by not investing in exploration and development, it could maximize short-term profit and pass the money back to shareholders in the form of dividends. The Conoco component of DuPont has a below-average cost of finding petroleum, a good track record of efficient production, and a full plate of projects that pass the test of return-on-investment. In short, Conoco is in business for the long-term. That fact, in itself, determines at least one key element in strategy. This is to extend the life of the petroleum reserve base while at the same time maintaining maximum efficient rates of production to provide a strong cash flow. A company that is able to maintain a strong reserve base will ultimately see the value of those reserves escalate as world oil supplies tighten. Our planners expect this tightening to occur within the next decade as demand grows and production in non-OPEC areas of the world begins to decline. An exploration program tailored to meet the requirements of reserve replacement and current production should have two basic parts. The first is relatively low-risk exploration in proven oil provinces. This is augmented by

Jan 6, 1985

By Robert B. Fulton

Commercially, celestite (SrSO,) is the only significant strontium mineral. Among other strontium-bearing minerals, only strontianite (SrCO,) occurs commonly; however, it is not an item of commerce. The principal production of celestite is in England, Mexico, and Spain. New production is now coming on stream in Canada. Consumption is mainly in the United States. Lesser quantities are consumed in Japan and Europe. Main uses are for the manufacture of strontium carbonate and nitrate. The carbonate is used in glass for TV tube face plates and in ferrites for magnets. The nitrate is used in pyrotechnics to which it imparts a characteristic brilliant red color, mainly in safety flares. Minor amounts of strontium compounds are used in electrolytic zinc manufacturing and very small quantities in greases, ceramics, soaps, alloys, and pharmaceuticals. Specifications and Prices Typical celestite specifications for the carbonate and nitrate markets are as follows: [ ] Celestite currently shipped from Mexico for carbonate manufacture tends to be slightly better than these industry specifications, assaying about 92-93% SrSO, with less than 1% BaSO, but it is generally below the 95% minimum required for nitrate production. Contract prices for celestite are approximately $32-34 per st at U.S. Port of Entry in 50 to 60-ton carload lots for Mexican material. Spot prices are generally reported as low as $20 per st but are for minor volumes. A recent sale of surplus from the U.S. stockpiles, announced by the General Service Administration (GSA), was 4005 st sold to Du Pont for $140- 455 or $35.07 per st. British celestite, ground, washed, and graded, 95% SrSO, bulk, ex- works, 240 mesh, is quoted at £ 28.75 per mt in British trade journals, and a recent figure quoted for crushed lump material was $36.00 per st f.0.b. vessel Bristol Channel port (1973). Specifications of manufactured carbonate made from celestite and sold in two grades, one to the glass industry, the other to the electronic industry for ferrites, are given in [Table 1]

Jan 1, 1975

By Ernest G. Enck

"The Rockets' Red Glare" of the Fourth of July is produced by strontium compounds. However, strontium has a number of less spectacular uses; i.e. in, or in connection with, the manufacture of ceramics, caustic soda, glass, railway and truck signal flares, beet sugar and steel. The principal ore of strontium for use both as the mineral and for production of compounds is celestite (SrSO4). This mineral varies in color from white to pink or blue depending on presence of impurities. It has a hardness of about 3.5 and specific gravity of 3.9. It is brittle and has perfect basal and prismatic cleavages. The high grade ore is obtained from England, hence it has become the standard for all other producing areas. (See analyses, Table 1.) The most objectionable impurity in English celestite is iron, coming mostly from adhering clay. On the other hand, Mexican celestite, while no higher in strontium sulfate content, is extremely low in iron (less than 0.2 pct), hence it is more desirable for certain uses. Most of the celestite in Spain and in the United States is high in calcium and barium, and commonly high in iron, and requires some form of beneficiation in order to be equal to English ore. The natural carbonate (SrCO3), or strontianite, is less important than celestite as a source of strontium, because it is less abundant and is not so widespread in its occurrence. Furthermore, it generally occurs with calcite (CaCO3) and lead sulfide (PbS), and for most uses these impurities are detrimental. This mineral is generally white or yellowish, forming needle-like crystals. It has a hardness of about 3.7 and a specific gravity of 3.68-3.8. The mineral is brittle and has an imperfect cleavage. A typical analysis of German strontianite is shown in Table 1. [ ] Distribution of Deposits UNITED STATES Occurrences of strontium minerals are known in Arkansas, Arizona, California, Illinois, Ohio, Pennsylvania, Tennessee, Texas, and Washington. Celestite occurs in the Vulture Mountains, Maricopa County, Arizona in beds three to ten feet thick associated with sandstone, gypsum, and barite. Because of the low strontium content, approximately 86 pct SrSO4, it has no commercial value. A large deposit of celestite occurs in San Bernardino County, California, in the Cady Mountains near Argus Station, about eight miles west of Ludlow. The celestite here is interbedded with shaly and clayey tuff in a zone about 300 ft thick. Massive, finely crystalline ore has been recovered with an analysis

Jan 1, 1960

By Robert B. Fulton

Commercially, celestite (SrSO4) is the predominant strontium mineral. Among other strontium-bearing minerals, only strontianite (SrCO3) occurs commonly; however, it is rarely an item of commerce. Production of celestite is principally in Mexico, Spain, and Turkey. An attempt to produce celestite in Canada was unsuccessful. The United States, which is wholly dependent on imports, chiefly from Mexico (99%), is the largest consumer of strontium. Lesser quantities are consumed in Japan and Europe. The Federal Republic of Germany is the principal source of strontium compounds imported to the US. Uses The principal uses of strontium are for the manufacture of strontium carbonate and nitrate. Carbonate is used in glass for TV tube face plates and in ceramic ferrites for magnets. Nitrate is used in pyrotechnics, mainly in safety flares, to which it imparts a characteristic brilliant red color. Minor amounts of strontium compounds are used in electrolytic zinc manufacturing where the carbonate is used to remove unwanted lead. Small quantities are consumed in greases, ceramics, soaps, alloys, and pharmaceuticals. Specifications Typical celestite specifications for the carbonate and nitrate markets are shown in Table 1. Specifications of manufactured carbonate, sold in two grades, one to the glass industry and the other for ceramic ferrites, are shown in Table 2. Both grades of carbonate are shipped in palletized 50-lb bags. Glass grade material is shipped in bulk by rail. [ ] Manufacturing Processes The following description is adapted from Anon. (1980) . The manufacturing process for strontium carbonate and strontium nitrate chemicals is conceptually simple. Strontium nitrate is made from strontium carbonate in two additional steps. The production process begins with celestite, the natural form of strontium sulfate. In the first step the ore is crushed, ground, and mixed with coke. This mixture is then fed into a kiln where the ore is reduced at high temperatures to strontium sulfide; the coke is added to the ore as a source of energy and carbon. The carbon combines with the oxygen [ ]

Jan 1, 1983

By L. Sun

In this work, strontium doped lanthanum ferrite (LSF) and their composite cathodes were fabricated by screen printing on yttria-stabilized zirconia (YSZ) electrolytes. Their electrochemical properties were evaluated by using electrochemical impedance spectroscopy and steady-state polarization methods. All the cathodes were screened by comparing their total polarization resistances before and after activation processes at different temperatures. The improved LSF composite cathodes were also screen-printed on YSZ/NiO half cells to fabricate solid oxide fuel cells (SOFCs), which have reached the output power densities of 170 mW/cm2 at 650 °C, 230 mW/cm2 at 700 °C, 304 mW/cm2 at 750 °C and 388 mW/cm2 at 800 °C.

Jan 1, 2005

By Charles L. Harness

STRONTIUM is an essential constituent of celestite (strontium sulphate), of the rarer strontianite (strontium carbonate), and of a few very rare minerals. Celestite is the chief ore but strontianite is more valued except for making the purest strontium salts, because of its ease of processing. The public knows strontium mainly as the source of the red flame in fireworks but it has many other uses. PROPERTIES The celestite of commerce is a massive mineral of varying texture: coarsely crystalline, fibrous, bladed, very fine grained or earthy. The color varies greatly with the nature of the impurities but the purer specimens are light blue (Latin, caelum, sky) or white. The strontianite of commerce is a massive mineral, more or less coarsely crystalline. The color varies with the impurities. Distinctive characteristics are effervescence with acids, density (3.68 to 3.71), and crimson strontium flame. A typical British celestite before World War II analyzed: SrSO4, 96.55 pct; SrCO3, 0.17; BaSO4, 0.25; CaSO4, 0.54; MgCO3, 0.15; R20,, 0.90; Si02, 1.38.10 A German strontianite analyzed: SrCO3, 90.9 pct; CaCO3, 7.5; BaCO3, 0.1; Fe2O3, 0.05; A1203, 0.1; SiO2, 0.04; S, 0.1; P, 0.005.10 ORIGIN AND MODE OF OCCURRENCE According to Clarke,9 strontia forms about 0.02 pct of the crust of the earth and is present in most igneous rocks, but in smaller quantities than barium. Under certain conditions, large masses of celestite are deposited from sea water with anhydrite. The presence of large amounts of celestite in some saline deposits and its absence in others suggests that the deposition of celestite depends on whether certain as yet undetermined concentrations of sulphate and chloride ions are reached in the brines. The most extensive of these sedimentary deposits are those of the Keuper (Triassic) in England, of the Zechstein (Permian) in Germany, and of various Cretaceous formations in Texas, Arkansas, and Utah. Of the deposits of southeastern California and western Arizona,

Jan 1, 1949

By Joyce A. Ober

Strontium occurs commonly in nature, averaging 0.034% of all igneous rock; however, only two minerals, celestite and strontianite, contain strontium in sufficient quantities to make its recovery practical, and these minerals are found in sedimentary rocks. Of the two, only celestite has been found to occur in deposits of sufficient size to make development of mining facilities currently attractive. Celestite, the most common strontium mineral, consists primarily of strontium sulfate (SrSO,). Strontianite, the second most common mineral, consists primarily of strontium carbonate (Sr CO3). Strontianite would be the more useful of the two common minerals because strontium is used most commonly in the carbonate form, but few deposits have been discovered that are suitable for development. The physical properties of strontium ores are listed in [Table 1].

Jan 1, 1994

By N Arrys, A Jani, S Shahin

Optimising pit slope stability and reducing strip ratio of a mining operation are two key tasks in geotechnical engineering. With a growing demand for minerals and an increasing cost associated with extraction, companies are constantly re-evaluating the viability of mineral deposits and challenging their geological understanding. Within Rio Tinto Iron Ore (RTIO), the Structural Geology (SG) team investigate and collect critical data, such as point based orientations, mapping and geological inferences from adjacent pits to remodel deposits where previous interpretations have failed to account for structurally controlled slope failures. This work outlines the key methods utilised by the Structural Geology team which form the foundations of informed orebody knowledge and subsequent geotechnical design recommendations. This publication utilises the results from a recent analysis to highlight the benefits of this methodology and how it has impacted the economics of an operation through optimisation of a pit wall ‘cutback’ and crest relocation.

Sep 1, 2024

By R M. Stephenson

Large diameter raise boring is a common raise excavation method in the Australian mining industry. Geotechnical investigations were conducted on several large diameter raise bore projects at Gwalia Mine to assess the potential for instability and potential back-reaming problems. A thorough geotechnical analysis and subsequent back-analysis was conducted on a vent raise excavated at 5.5 m diameter and 810 m length.The geotechnical investigation for the vent raise included collection of data from an acoustic televiewer survey that was conducted on the pilot hole. The survey results provided structural data and an insight into the effects of stress on the pilot hole. Structural analysis was conducted using a combination of information obtained from the acoustic televiewer survey and geotechnical logs of the diamond drill core drilled close to the site.Further information was collected from drillers’ plods from pilot hole drilling and back-reaming to conduct a back-analysis of the completed shaft, and this was compared with the structural analysis.The key finding from this review was that the acoustic televiewer survey of the pilot hole accurately identified locations with blocky conditions. This is an important supplement to the information available from the main geotechnical investigation hole, as this was offset from the shaft location over most of its path.CITATION:Stephenson, R M and Sandy, M P, 2014. Structural analysis of acoustic televiewer logs for large diameter raise bored shafts, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 89–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By Jung-Joo Kim, Jong-Uk Kim, Turab H. Jafri, Han-Kyu Yoo

"INTRODUCTION Steel sets such as H-type and lattice girders are often installed in the tunnels before the hardening of shotcrete to ensure the stability of conventional tunnels in soft ground conditions. In practice, while designing the tunnels with the help of numerical analysis, steel sets are generally considered only as temporary support elements. Only a few studies propose the direct application of composite support in the tunnel design, based on large-scale experiments and numerical analysis. In order to assess the structural performance of the composite support consisting of shotcrete and steel sets, large-scale experiments were performed on two types of arch-shaped specimens by applying the combined effects of axial forces and bending moments. Based on the experimental results, numerical analysis was performed to assess the application of composite support in tunnel design. The crown settlement, axial forces, bending moments, and load distribution in the composite support were analyzed in the light of different structural patterns. LARGE-SCALE EXPERIMENTS USING COMPOSITE SUPPORT Preparation and Procedure of the Experiments The preparation setup as well as the organized procedure of the large-scale experiments using composite support is shown in Figure 1. An appropriate geometry of the specimens was selected by considering the standard cross-section of a two-lane highway tunnel in South Korea. Under the loading conditions meant to develop the axial forces and bending moments simultaneously, arch-shaped specimens were assembled with the ends of the specimens subtending a 60° arc angle at the center of the arc circle as shown in Figure 2. The fabrication of six specimens was completed in two groups based on the dimensions of steel sets, with the first group of three specimens being reinforced by H100 (No.1, No.2, No.3) and the other three by H125 (No.4, No.5, No.6). In order to reduce the voids on the boundary of the shotcrete and steel sets, concrete was casted over the steel sets instead of using shotcrete. The specimens were designed to incorporate the uniaxial compressive strength of 21 MPa. Shear keys and steel plates were installed at the ends of the specimens, so that shear failure could be avoided at the ends and the specimens could also be protected from detachment at the fixation. Translational and rotational movements at the ends of specimens were fixed."

Jan 1, 2016

By Peter Ay, Vincenz Mehlstaubl, Satyanarayana Narra

"This study gives an insight into non-destructive testing methods suitable for porosity analysis at a small scale, firstly summarizing relevant state-of-the-art technology and pending patents, secondly realizing and documenting the start-up of the VHX-2000 digital microscope by the manufacturer Keyence and thirdly demonstrating practical application with the extended analysis of three fundamentally different agglomerates for which important application-related parameters are determined. Various analysis procedures on the different agglomerates the efficient and timesaving operational features of the digital microscope are outlined. Firstly an analysis of flax fibre agglomerates determines the process conditions best suited to produce agglomerates with specific properties by determining sphericity, cubicity, density and porosity as well as fibre damage and alteration. Secondly the production of iron-hydroxide - hemp-fibre agglomerates serves to obtain information on porosity values as a result of a cauterization of the fibres. The third analysis provides estimations of porosity values for acid-treated lignin agglomerates. Measurements were carried out with compact dry agglomerates and with soaked, expanded agglomerates, determining factors for total water carrying capacity. Practicability of non-destructive testing by digital microscopy is demonstrated and explained concerning the applications in this study by obtaining definite structural findings about the analysed agglomerates. Information on its operation is made available by a practice-oriented manual for the VHX-2000 digital microscope. Further suggestions for more in-detail analysis results with different instruments are given."

Jan 1, 2014

By M. A. H. Shuva, M. A. Rhamdhani, G. A. Brooks, S. H. Masood, M. A. Reuter

Ferrous-calcium-silicate (FCS) based slag has been used in the copper industry over the last two decades. The FCS slag has also been used in a secondary copper processing such as in black copper smelting which has different operation conditions compared to that of typical primary copper processing. In the process, a variety of copper bearing scraps from sources such as industrial waste, consumer waste and electronic waste (e-waste) are used. The valuable metals in these sec- ondary resources are distributed in different phases during the process. Understanding the behaviour of the valuable elements at the relevant conditions is vital for optimizing the process and to maximize the recovery of the elements. In this study, we investigated the structure of Ge-containing FCS-based slag at different conditions (oxygen partial pressure and temperature) using Fourier-Transform Infrared (FTIR) spectroscopy to explore the effect of the polymerization on the behaviour of the valuable element Ge in the slag. It was found that experimental parameters significantly in fluence the slag structure, and therefore, the partitioning of Ge in the slag. A correlation between the distribution ratio of Ge and the slag structure has developed in the current study.

Mar 1, 2018

By D. H. Y. Tang, S. S. Peng

Three-dimensional finite element modeling (3-D FEM) was performed to analyze the safety factors of stump pillars, 5.5 m x 5.5 m, under a cover of 63 m using the Modified Drucker-Prager Theory. The results showed that they were safe. This was substantiated by underground observations. But the safety factors predicted by three commonly used pillar design formulae showed otherwise. This paper discusses the modeling details and analyzes the difference between 3-D FEM method and traditional pillar design formulae.

Jan 1, 1987

By D. H. Y. Tang

3-dimensional finite element modeling was performed to analyze the safety factors of stump pillars, 18 ft. x 18 ft., under a cover of 208 ft. using the Modified Drucker-Prager Theory. The results showed that they are safe. This was substantiated by underground observations. But the safety factors predicted by three commonly used pillar design formulae showed otherwise. This paper discusses the modeling details and anlyze the difference between 3-D FEM method and traditional pillar design formulae.

Jan 1, 1987

By H. Urata, K. Ishii

To determine the effect of F ions in the molten alkali silicate systems on their structures, quenched Na2O-SiO2-NaF systems were investigated by Raman spectroscopy and molecular dynamics simulation. The systematic increase of 1100 cm-1band intensity in the Raman spectra of the silicate melts accompanying the replacement of F for O provides the evidence for concomitant polymerization of melts. From the molecular dynamics simulation, it was confirmed that most of substituted F was mainly coordinated to Na+ ions but not Si4+ions. These results were consistent with the mechanism in which F associated with otherwise network-modifying Na rather than with network-forming Si. Since F was associated to Na+ ions, the replace of O ion by two F ions promote the polymerization of silicate melts. Keywords: fluorine; molten flux; slag structure; molecular dynamics simulation; Raman spectroscopy.

Jan 1, 2004

By George H. Davis

The Caribou sulfide deposit near Bathurst, New Brunswick (Figure 1) is illustrative of one variety of strata-bound sulfide deposits. It consists of numerous near-vertical sulfide lenses which are concordant to the foliation and lithologic layering of low-grade metamorphic host rocks. Pyrite is the chief mineral in these lenses, but appreciable quantities of sphalerite, chalcopyrite, and galena are also present. Rocks in the Caribou mine area belong to the Tetagouche Group of Ordovician age. They consist chiefly of (1) quartz-sericite and quartz- sericite- feldspar schists, (2) greenschists, and (3) slate and phyllite. The trends of these steeply dipping rocks define the trace of a tight, steeply plunging fold structure, the Caribou fold (Figure 2). This fold plunges approximately 750 to the north-northwest; its axial plane strikes N.20°E. and dips steeply westward. Sulfide lenses of the Caribou deposit are associated spatially with the Caribou fold. The deposit is located in the fold along the contact between quartz-sericite and quartz-sericite-feldspar schists on the hanging wall and quartz-chlorite-sericite phyllites and graphitic schist on the footwall (Figure 3). Genesis of the Caribou deposit is ambiguous because its strata-bound form suggests syngenetic sulfide deposition, whereas its location within a fold suggests structurally controlled epigenetic mineralization. Acceptability of a particular genetic model rests on establishing the time of mineralization relative to deposition, deformation, and metamorphism of the associated rocks. To establish the timing for Caribou mineralization, the deformational histories of rock and sulfide, respectively, were compared. Epigenetic and syngenetic models can be tested against this interpreted structural history of the Caribou deposit.

Jan 1, 1971

By Igor Zh. Bunim, Valentine A. Chanturiya, Alexey T. Kovalev, Irina A. Khabarova, Elizaveta V. Koporulina

This paper presents new theoretical and experimental data on possible mechanisms for the formation of micro- and nanophases on the surface of sulfide minerals un der the effect of high-power nanosecond electromagnetic pulses (HPEMP). The gas outflow from nanosecond breakdown channels of sulfide minerals under the effect of HPEMP is considered, with allowance for the condensation of iron vapors. The condensation of matter in an outflowing jet is shown to be an effective mechanism for structureal and chemical transformations of sulfide surfaces. It is established that electrode potential of pyrrhotite is moved together in the negative party owing to formation of iron oxides (hydroxides) and iron sulfates by HPEMP, that provides decrease of xanthate sorption and reduction flotation extraction of this sulfide, whereas electrode potential of pentlandite gets more positive values at the expense of additional formation of element sulfur, that causes increase of xanthate sorption and, as a consequence, increase of nickel sulfide extraction.

Jan 1, 2012

By V. A. Chanturiya

The application of High-Power Nanosecond Electromagnetic Pulses (HPEMP) irradiation in dressing of resistant gold- containing ores appears attractive as this technique provides for a significant increase in precious metal recovery (30-80% for gold and 20-50% for silver), therewith helping reduce both energy consumption and the cost of products. The prospects for applying pulsed power technologies in the mineral processing in order to increase the contrast between the flotation properties of raw minerals dictate the need to perform special studies of the effect of HPEMP on the structural state, phase composition, and physical and chemical properties of surfaces of sulfide minerals as the main carriers of precious metals. This study deals with plausible mechanisms of the micro- and nanophases formation on the surfaces of sulfide minerals under the effect of high-power nanosecond electromagnetic pulses (HPEMP) with high electric field strength ~107 V/m. This paper discusses reasons for the changing of flotation behavior of natural pyrite and arsenopyrite during the pulsed-power treatment. It was concluded that HPEMP treatment may be regarded as a tool to change the surface composition and sorption ability of collector (xanthate) onto mineral surface, and, therefore, it allows to control the hydrophobic-hydrophilic surface balance. Single mineral flotation tests have been shown the significant increasing of the pyrite recovery while the arsenopyrite was depressed. The results of gold containing pyrite (pyrrhotite)-arsenopyrite ore flotation in batch approve the decreasing of arsenic recovery in sulfide concentrate. Keywords: pyrite, arsenopyrite, high power nanosecond pulses, activation, selective flotation

Sep 1, 2012

By C. B. van den Berg

n this study, silver and palladium nanoparticulate inks with different metal-binder ratios were screen-printed onto a paper substrate. The printed layers comprised the metal nanoparticles and an ethylcellulose binder. The layers are not typical metal composites due to the low concentration of binder and high porosity. The electrical sheet resistivity of each particle concentration was measured, and the data fitted using the scaling law of percolation theory and the general effective media (GEM) equation. The percolation parameters, i.e. the percolation threshold and the critical exponent, for each system were determined from the fits and compared. The percolation threshold for the palladium layer (39.8 wt%) was lower than that found for the silver layer (44.9 wt%). The critical exponents determined for the palladium and silver layers were both lower than the universal value for three-dimensional percolation systems. Microscopy observations indicate that the difference in the percolation threshold for the two layers can be attributed to variations in their microstructure.

Jan 1, 2014

By Chen Ya

Layered LiMn0.5Ni0.3Co0.2O2 was prepared from Mn(NO3)2, Ni(NO3)2, Co(NO3)2 and LiOH by co-precipitation and solid state reaction. XRD, C-V and galvanostatic charge-discharge methods were used to examine the structural and electrochemical characteristics. The LiMn0.5Ni0.3Co0.2O2 delivered a high discharge capacity of 167 mAh/g between 2.5 and 4.3 V with excellent cycling stability.

Jan 1, 2006