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By N. Rowlands

The importance of mineralogical and chemical characterization of fine particles in the fields of mineral and metallurgical processing is discussed. Emphasis is placed on electron beam analysis techniques including electron diffraction and energy dispersive analysis with special reference to the scanning trans- mission electron microscope. The correct choice of instrument depending upon particle size, composition and nature of sample is stressed and the analytica1 capabilities of different types of instruments are evaluated. Recent applications of electron beam equipment to processing problems are presented and the paper concludes with a review of new developments in the fields of surface analysis and micro-diffraction.

Jan 1, 1985

By Osamu Takai, Yoshiki Sato, Nobuhiro Tajima, Hiroyuki Sugimura

"Amorphous carbon thin films doped with nitrogen ( a-C:N) have been synthesized by means of shielded arc ion plating (SAIP). Their electron field emission properties, that is, threshold field strengths for electron emission and maximum emission current densities, were evaluated and compared with those of pure amorphous carbon (a-C) films prepared by the same SAIP apparatus. Among all of the fabricated a-C:N films, the a-C:N films with a N concentration of 23 %, which prepared using Nz arc plasm at a pressure of 1 Pa with applying a sample bias voltage of -100 V, showed the lowest threshold filed of 13.4 V/µm and the highest emission current density of 1.87 µAfcm2 at a field of20 V/µm. These field emission properties of the a-C:N film were much better than those of the a-C films. The best results obtained on the a-C film in this study were the lowest threshold filed of 15.5 V/µm and the highest emission current density of 0.052 µA/cm2 at a field of 20 V /µm. Nitrogen doping to aC was found to be effective for lowering threshold voltage for field emission and for increasing emission current density. The electron field emission characteristics of the a-C:N films depended not only on N concentration but also on chemical bonding state of nitrogen in the a-C:N films. The presence of the ~-C3N4-like phase, which contributes to improve wear resistance of a-C:N as well, distinguished by the NlsXPS peak at 400.5 eV is proved to be crucial in order to enhance field emission properties of a-C:N.IntroductionThere has been much interest in electron field emission from a cold cathode due to its potential applications in vacuum microelectronic devices including field emission displays which are expected as flat panel displays in next generation [l]. It is well known that efficient emission can be rather readily realized using tip-like shape cathodes, e.g., microfabricated three-dimensional electrodes [2], carbon nanotubes [3-5], etc. However, electron emission from planar surfaces is of particular importance since such a type of cathode is· simply fabricated and assembled into microelectronic circuits. Currently, amorphous carbon thin films doped with nitrogen (a-C:N) prepared by plasma processes have attracted attention because their threshold voltages of field emission are relatively low [6]. Among various methods for preparing a-C:N films, the process using arc plasma is of special interest since, in arc plasma, nitrogen is highly activated and new types of carbon nitride phase are expected to be synthesized. However, field emission properties of a-C:N prepared by arc plasma have been studied in less detail compared with that prepared by the other methods such as sputtering."

Jan 1, 2000

By C MacRae, N Wilson

CSIRO Minerals has recently developed an electron microprobe (EMP) based imaging (or mapping) method for characterising ilmenite concentrates. The method requires an electron microprobe analyser to collect elemental X-ray maps which are then processed via an in-house developed software module (CHIMAGE). The type of information readily available from EMP mapping includes; primary phase identification, modal analysis of phases, chemical analysis of individual phases, textural information (eg the alteration stages in the formation of leucoxene or pseudorutile from primary ilmenite and the development of macro-porosity), and the identification of coatings or pore-fill material. All of these parameters will impact on the choice of future downstream processing options considered for any particular ilmenite concentrate. The method has been demonstrated to be a sensitive analytical tool for assessing the distribution of aluminosilicate minor impurities in ilmenite feedstocks from the West Coast of Australia and also for characterising the complex chrome-spinel gangue phases common in East Coast ilmenite concentrates from the Murray Basin.

Jan 1, 2001

By O. E. Omotoso

This study is part of an ongoing investigation to understand the mechanism of stabilization/solidification of hazardous chromium wastes in ordinary Portland cement (OPC). Tricalcium silicate (C3S*),a major component of OPC is mixed with reagent grade Cr(lll) and Cr(VI) solutions, to simulate complex cementiCr waste systems. Scanning electron microscopy (SEM) and energy disperse spectrometry (EDS) were employed to provide microstructural and chemical information. Transmission electron microscopy (TEMlEDS), apart from complimenting the SEM, was used to probe the distribution of Cr in the hydration products of C3S and to provide crystallographic information. 29Si MAS NMR (magic angle spinning - nuclear magnetic resonance) Was used to characterize the influence of Cr on the hydrated silicate structure.

Jan 1, 1995

"Mechanical alloying (MA) synthesizing technology and thennohydrogen processing (THP) were utilized to produce nanocrystalline Ti-MMC's reinforced by TiB intermetallic compound by using TiH2-B powder mixtures. Powders MA'ed up to 8 hours were examined by X-ray diffraction and SEM study. All MA'ed powders afterwards were HIP'ed at 700, 800 and 950EC for 1 hour. Detailed XRD, SEM and TEM study of the samples were carried out to determine the structure and micrography of the Ti-TiB MMC material processed by MA+THP approach followed by HIP'ing at high temperatures.IntroductionThe fiber reinforced titanium base composites [1,2] which possess a great resistance to high temperature have been investigated. In these studies fibers of C and SiC were used as reinforcing materials. However, these fibers react with Ti-matrix at elevated temperature resulting in product formation at the interface between the matrix and the fiber. Because of the chemical reactions, strength of the product MMC material diminishes.In conventional techniques of whisker reinforced composite material production, the mixtures of matrix metal powders and dispersed fibers are consolidated by hot pressing, HIP and/or hot extrusion. These techniques, however, have some shortcomings. Hard and brittle fibers could be broken during mixing cycle of the processing. Consolidation techniques could also be the cause for fiber breakdown. Attaining of the uniform dispersion of fibers into the metal matrix is not an easy process. The chemical reactions at elevated temperature exposures in the interface between the matrix material and fiber reinforcement cause product formations leading to poor mechanical properties."

Jan 1, 1998

By N. S. Dalal, B. Jafari, X. Shi, M. M. Suryan

"It is well known that prevalence and severity of coal worker's pneumoconiosis (CWP) differ markedly in different regions and mines despite comparable exposures. These variations in the pathogenicity of different coal mine dusts can only partially be explained by the mineral composition of the coal mine dust and the rank of coal. Laboratory studies also do not correlate with the human experience. One major difference between human exposure and laboratory studies is that the coal miner breathes dust from freshly broken coal, while the animals or cells are exposed to stale dust. In an effort to find biochemical clues for resolving this apparent paradox, we have carried experiments to detect differences in chemical reactivities of fresh versus stale coal dust from several U.S. coal mines. Electron spin resonance (ESR) was used as a technique for the direct detection of the concentration and reactivity of free radicals. ESR measurements of freshly ground coal dusts of different ranks and composition showed significant differences in the amount and reactivities of the organic free radicals produced. The half-lives and reactivity patterns of these newly formed species of free radicals seem to correlate with the expected toxicity and pathogenicity of the dust, thereby, providing new clues to the biochemical mechanisms and pathogenesis of CWP. Similar detection of free radicals in freshly crushed quartz suggest that free radicals might play a significant role in the pathogenicity of quartz in causing fibrosis and eventually silicosis.IntroductionThe pathogenesis of coal workers' pneumoconiosis (CWP) has been an important topic of concern for decades, but the mechanism of CWP is still not understood. It is well known, for example, that the prevalence and severity of CWP differ markedly in different regions and mines despite com¬parable exposure'(1,2) but these observations can only par¬tially be explained by differences in mineral composition and rank of coal (3-5) Specifically, while epidemiological studies of coal miners indicate (1,2) that the effectiveness of coal in producing CWP correlates roughly with the rank (i.e. %,carbon content) of coal, such correlation has not been established via biological studies.(4-6)"

Mar 1, 1989

By H. L. Ludtke

Microlaminate composites were fabricated by electron-beam physical vapor deposition. The microlaminates consisted of five layers, each 2 to 4 pm thick, and were composed of either pure metal layers (Cu-Ag), or alternated between metal and intermetallic layers (Nb(Al)- Nb3Al). The microlaminates were heat treated in an Ar atmosphere for 2 to 12 hours, at temperatures of 600°C for the Cu-Ag and 1000°C to 1200°C for the Nb(Al)-NbsAl. Microlaminates were examined after deposition and after heat treatment by scanning electron microscopy and energy dispersive x-ray spectrometry. The effects of heat treatment on the morphological stability of these composites will be described.

Jan 1, 1999

By J. G. Debanne

MOST company-employed petroleum engineers have in their accounting departments punch-card computers that can perform engineering calculations thirty to three hundred times faster than desk calculators, or they can rent such machines from Computing Service centres. These machines not only eliminate the drudgery of desk calculation but also the risks of human errors. The I.B.M. t 604 punch-card computer of Texaco's accounting department in Calgary has been used for oil and gas property evaluations, curve fitting by least squares, statistical core analysis studies, unsteady-state water in-flux studies, phase equilibrium performance prediction of oil reservoirs, gravity segregation calculations, etc.

Jan 1, 1958

By Steve Brace

Electronic detonators have been commercially available to the mining industry worldwide for over ten years. It is estimated that total cumulative global sales will have reached 25 million units by the time of the Conference in February 2004. This is below 0.2% of all detonator types sold during this period. Perhaps 20 million will have been used underground in South African gold, diamond and platinum mines. These will have been produced by South African companies, in South Africa for South African customers. Here efforts have met with greater success and in 2003 fully 5 million, or 3% of local detonators sold, could be of an electronic type. However, it is estimated that about US$7.00 (R50.00) has been expended on R & D, manufacturing facilities and marketing, for each unit so far sold. Large sums of money continue to be spent. Despite the apparent success in South Africa, is it justified? Electronic initiation systems have not produced significant technical benefits to the end-user underground nor corporate profits to the supplier. Some doubt they ever will (even from the large surface operations where the price per unit is much higher). A conclusion might be that they have failed. In 1998 Smit and Pistorius wrote a paper titled “Implications of the Dominant Design in Electronic Initiation Systems in the South African Mining Industry”. This ISEE paper seeks to summarise and review the conclusions of the earlier work. These were: that a dominant design had not yet emerged; the type of connector and the way in which detonators are connected and programmed would be a strong determinant influencing the development of a “winning” product; technical aspects rarely solely determine which becomes the dominant design (marketing, social and economic factors often have a strong influence); electronic initiation systems were an emerging technology for the underground gold mining industry in South Africa and because it was under severe cost pressure the mines would look to them to raise productivity and hence profits; finally, as a dominant design begins to emerge, one could expect a number of players to exit from the industry.

Jan 1, 2004

By Laurent Airaud

For around ten years, electronic detonators are available for those who want to use advanced methods and to apply theories promoted by engineers and professors to reduce blast concerns or improve fragmentation and dilution. Furthermore, decision makers can verify the use of electronic detonators to drive down mining costs. Engineers and more specifically blasters are the actual users and have to be convinced of the easiness of electronic detonators. This paper deals with electronic detonators and the notion of easiness. Common feelings about the notion of easiness are discussed. Then, examples of new technologies like, automobile, photography or Information Technology are discussed to observe how they progressed throughout time with new features and sales volume. For the specific explosive initiation industry, each step of the life of an electronic detonator is dealt with concerning the easiness and a table is used to quantify this notion.

Jan 1, 2004

By Tristan Worsey, Nathan Rouse, Evan Thibaud

Electronic detonators allow for variability and accuracy with blast delay selection and timing sequence. However, a single published guideline for selection of electronic timing delays is not available on the OneMine database. There are published documents that present options for timing with electronic detonators, some of which provide great detail and scientific evidence, but there is no single document that presents several different approaches with simple instructions on how to apply the various timing approaches. This paper reviews published electronic timing approaches and results, then presents guidelines for electronic timing for alternative mining methods, which include: bench blasting (ie. quarries) and crater blasting (ie. metals mines). Most of the approaches are based on calculating milliseconds per meter for rock types, as quantified by the rock sonic velocity. Guideline calculations are provided for recommended hole-to-hole delays and row-to-row delays for both free-faced bench blasting and crater blasting approaches. These are the two most common blasting methods for mining operations. Typically, free-faced bench blasting is the approach used in quarries with a bench height to burden ratio of around 4, and crater blasting is typically used in large blasthole diameter/short bench blasting in metals mines with a bench height to burden ratio of around 1. Mines may focus on fragmentation, mucking rates, ore movement distance and movement direction. Recommendations are also included to provide general recommendations based on a mine’s preference for movement and fragmentation. References include twelve studies on bench blasting and six studies on crater blasting. In addition, a discussion is included on the application of these recommendations at a full-scale surface gold mine.

Jan 21, 2025

By Douglas Bartley, Kevin Hachmeister, Rich Barry

The use of explosive energy as a tool in mining and construction is the most effective way to move large amounts of rock that is otherwise unable to be efficiently excavated. Since the early days of explosive engineering utilizing black powder initiated by cap and fuse to the present day diversity of specialty products and technologies the goal has always been to "Break and Move" as much rock for the least expense possible. It has primarily been the competitive nature of our economy that has driven the advancement of technological innovations and practice. However, the concept of removing rock is not specific to the mining and construction industry. Since the dawn of creation, man has used rock as a medium to express his creativity in the form of sculpture. Even though the process of sculpture requires the removal of rock, the final work is defined by the rock that remains intact. This typically necessitates the extreme care of the sculptor to painstakingly chip away the rock allowing the image to emerge from the original mass of stone. The famous sculptor Michelangelo once said, "I saw an angel in the marble and carved until I set him free."

Jan 1, 2004

By C. Zuniga, S. Combrinck, C. Peters

Agnico Eagle Gold have partnered with Enaex Australia at their Fosterville gold mine to leverage a combination of drill and blast technologies to optimise underground development mining. The mine is the first site globally to collaboratively develop and trial Enaex SWIFT electronic development detonators, which utilise a novel approach to the user interface, simplifying implementation and enabling the benefits of electronic initiation without the complexity of a conventional system. This has been combined with the use of a Sandvik 422i smart jumbo, and the Enaex underground emulsion charging unit with the capability to tailor the delivery of explosives as required and report on a hole-by-hole basis. The combination of these technologies enables full engineering oversight of the development cycle, in turn enabling optimisation of this process in a historically conservative application. The methodology for leveraging these technologies is to bore a controlled and defined blast pattern through using a smart jumbo, load the blast holes utilising lace loading to deliver a desired quantity of ammonium nitrate emulsion per hole, with the ability to reduce chargeweight for perimeter control, and utilising Enaex SWIFT electronic detonators with flexible template type pre-defined delays to initiate the blast holes. Subsequent to firing and excavation the performance of the blast in fragmentation, advance efficiency, and overbreak and underbreak is measured and reviewed. This is then used to optimise the development cycle and apply to other parts of the mine.

Feb 6, 2023

By Franz-Werner Gerressen

New developments are required each day as our industry becomes more competitive. To improve performance, continue and to ensure future demands can be met. This requires the development of technical support systems that enable a more constant delivery and quality of installation of pile foundations and other applications. For example: assistance systems capable of relieving the machine operator of automating monotonous or repetitive operations. Real time installation control of the production process to manage quality control, or data transfer and reporting systems capable of keeping pace with the digital future. This paper will describe these new approaches and considerations required for these new developments. The paper also describes the equipment which is needed to execute the work under the various conditions and provides references herein. INTRODUCTION The success of a construction site is influenced by a number of factors. Selecting the most efficient and economic methods during the planning phase to defining the right direction. This means having multifunctional equipment available. To ease the usage of this equipment by the operator, uniform operation and control systems are essential. Systems like this can provide uniform handling procedure for more than 20 different installation techniques. Experienced operators are not always available. Therefore, to ease the start for beginners and to support training, numerous assistance systems were developed. This ranges from simple information for controls shown on the monitor avoiding misuse to systems which can partly automate the construction process. Regardless, the best equipment is not enough when the construction is not running smooth. The control system not only helps to organize and coordinate service of the equipment; moreover, it allows the operator to control the quality during the installation process reacting if needed. It allows process optimization as well as documentation which might be required for later negotiations.

Jan 1, 2019

By William Hume-Rothery

MR. CHAIRMAN, LADIES AND GENTLEMEN: I need not say how much I appreciate the honor of being asked to lecture to you, and how much I would thank you for your kind invitation. It is encouraging to feel that the abnormal restrictions of the war have been relaxed sufficiently to allow a free exchange of scientists between our two countries, and I hope that some of you will be persuaded to go to England, and to visit us at Oxford, so that I may repay a little of the kindness I have received from you. As this is one of the first lectures since the end of the war, I have thought it well to describe some of the advances in the theory of alloys which were made in the years between the two World Wars. From the point of view of theoretical science, these years have been of outstanding interest in the history of metallurgy. They have been years in which the development of new and more accurate experimental methods has led to the revelation of many new facts. At the same time, the theoretical developments have enabled some of these facts to be viewed as parts of a general scheme, and we may say that some of the foundations of metallurgical science have been laid. This work was naturally stopped by the Second World War, and it can therefore be reviewed as one definite stage in the development of our Science. To illustrate the new advances, I shall deal mainly with the alloys of copper and silver, since these have revealed many of the general principles. SOLID SOLUTION At the beginning of our period, the first steps in X-ray crystal analysis had been taken, and copper had been found to crystallize in the face-centered cubic structure (Fig I). The determination of this structure naturally was of immense importance in the understanding of our subject, because it meant that we were at last in a position to appreciate the underlying structure out of which the crystal of copper was built. The earlier science of metallography had shown that in many alloys of copper the addition of a second metal in not too large proportions resulted in the formation of a homogeneous alloy which was regarded as a solid solution of the one metal in copper. Fig 2, for example, shows the so-called equilibrium diagram of the copper-zinc alloys, and here you will see that there is a solid solution of zinc in copper extending to something of the order 35 to 40 at. pct zinc.

Jan 1, 1947

By L. A. Morley, W. T. Parry

Laboratory prepared clay-quartz sand samples and fault gouge from an open pit slope undergoing plane-type failure were tested in the laboratory to determine potential mining applications of electroosmotic stabilization and to provide a better understanding of electrochemical hardening. Experiments with very low current densities and free access of electrolytes to both anode and cathode showed an increase in cohesion. Cohesion in a fault gouge increased by 9.3 to 113%, depending on location with respect to the electrodes. For this, power consumption was equivalent to 0.727 watt-hr per cu ft (25.69 watt-hr per cu m). Regions of electrochemical hardening were determined by pH and the anolyte used. Electroosmotic stabilization appears as a reasonable solution to some types of mining problems.

Jan 1, 1975

By R. Herrera-Urbina

Measurements of the electrophoretic mobility of bastnaesite in aqueous solutions of sodium nitrate reveal that the isoelectric point (iep) of this cerium fluocarbonate occurs at about pH 9.3. These results also indicate that the pH affects significantly the electrophoretic mobility of bastnaesite, which becomes more positive as the pH decreases and more negative as the pH increases from the iep. Computations of solid-solution equilibria for the bastnaesite-H2O system closed to the atmosphere as a function of pH indicate that cerium fluoride precipitates in acidic solutions, whereas cerium hydroxide precipitates in alkaline solutions. When the initial amount of bastnaesite is fixed at 0.05 wt.% (the solids concentration used for electrokinetic experiments), these computations reveal that bastnaesite is the only solid phase in the pH range from 5.75 to 8.55, it coexists with CeF3(s) between pH 5.22 and pH 5.74, and with Ce(OH)3(s) between pH 8.56 and pH 10.12. Cerium fluoride and cerium hydroxide are the only solid phase below pH 5.2 and above pH 10.2, respectively. According to these computations, the dissolution-precipitation processes that occur when bastnaesite is equilibrated in aqueous solutions at different pH values determine the solid phases present in the system. In turn, these processes must affect the electrokinetic potential at the solid-solution interface, and they must be considered for explaining electrokinetic measurements as a function of pH when bastnaesite is the original solid phase in aqueous suspensions.

ELECTROREFINING Canadian 1,023,691 -Removal of bismuth from slime filtrate in the Betts process refining of lead. The filtrate is subjected to electrolysis in a cell having an anode of crude lead and a cathode of refined lead under operating conditions to preferentially deposit bismuth on the cathode. The substantially bismuth-free filtrate is recycled for use in the process as the electrolyte for producing high-purity lead. S. Hirakawa and R. Oniwa, assigned to Mitsui Mining & Smelting Co., Ltd. Jan. 3, 1978. 8 pp. (204-73). Filed: 2-18-74 (192,810). Same: U.S. 4,026,776, dated May 31, 1977.

Jan 1, 1979

By T. Sugawara, H. Sekimoto

Electrorefining of low-grade copper alloys containing various amounts of nickel, lead, antimony, bismuth, arsenic, selenium, silver, and gold in sulfamic acid media was demonstrated. The copper concentration of the alloys used as an anode was 70–90 wt%. The electrolyte contained 100 g L-1 of free sulfamic acid and 40 g L-1 of cupric ion. Galvanostatic electrolysis was conducted at 200–300 A m-2 in the electrolyte using a low-grade copper alloy anode and a stainless steel cathode at 25C. The terminal voltage was approximately 0.8 V at the start of the electrolysis, although it increased periodically to approximately 2.0 V and then shortly returned to its initial value. Nickel, lead, and arsenic from the anode dissolved in the electrolyte and were removed. Antimony, bismuth, selenium, and silver were removed as solids. Consequently, a dense copper cathode was obtained, and the concentration of copper was evaluated by inductively coupled plasma – optical emission spectrometry to be 99.82–99.99 wt%. INTRODUCTION Electrorefining of copper is conventionally carried out in a sulfuric acid electrolyte using crude copper assaying at 99.5 wt% Cu as the anode (Biswas & Davenport, 1994). Elements more noble than copper do not react anodically, and consequently, they are distributed in anode slimes. Elements less noble than copper dissolve from the anode. Nickel and arsenic are stabilized as aqueous species. Lead, antimony, and bismuth react with water, sulfuric acid, or arsenic acid to form barely soluble compounds; thus, they are distributed in anode slimes. An emerging issue in the electrolytic refining of copper is an increase of impurities in crude copper used as the anode (Moats et al., 2013). This is due to an increase in the content of impurities in copper concentrates as well as an increase in the types of secondary copper feedstocks (e.g., E-Scraps, automotive shredder residues, and smelting residues) treated in the copper pyrometallurgical process. An extreme case is a copper smelter that does not use copper concentrates as feedstocks. In such a process, copper-bearing feedstocks are smelted in a top submerged lance furnace to prepare low-grade copper alloys assaying at 80– 90 wt% Cu (Sekimoto et al., 2013). Such low-grade copper is not acceptable as an anode in the conventional copper electrolytic refining process because it is easily passivated during electrolysis. Consequently, electrolytic copper is produced by leaching the atomized low-grade copper in a sulfuric acid solution with oxygen, followed by electrowinning. However, electrowinning should be avoided whenever possible because the electrical energy consumed in electrowinning is 5–10 times higher than that consumed in electrorefining. Therefore, the development of technologies for electrorefining of low-grade copper alloys is desirabl.

Jan 1, 2019

By Olli Hyvärinen

The capacity of Outokumpu Pori Copper Refinery has been increased by 50 % to 70 000 t/a in the last five years by adopting periodic current reversal, reducing spacing and installing some new cells in the old tank house building. Five years operation of PCR has proved that it is possible to achieve additional capacity with PCR and yet produce high quality cathodes. The impurity level in anodes has considerably increased, and recently, arsenic, antimony and sometimes bismuth have displaced nickel as the most critical impurity.

Jan 1, 1987