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By N. S. Spence

INTRODUCTION WHILE TITANIUM, the element, has been known for over 150 years, titanium, the metal, is a relative newcomer to the metallurgical and industrial scene. The reasons for this chiefly lie in the refract1Hy nature of titanium compounds; the high melting point of the metal; the great activity of elemental titanium, particularly at temperatures close to .and above the melting point; and the pronounced deleterious influence of certain impurities on its mechanical proper-ties. Early efforts at production of the metal were, consequently, either unsuccessful or resulted in products having sub-metallic properties. With the considerable improvement in equipment, materials, and skills that have developed within the past twenty-five years, later investigators have had a better opportunity to overcome some of the inherent practical obstacles and to come to grips with the essential technical problems. NATURAL ABUNDANCE OF TITANIUM Titanium is one of the most abundant metallic elements. It has been estimated (1) that titanium comp-rises about 0.65 per cent of the earth's crust, and therefore ranks fourth among the structurally useful metals in the order: aluminum, iron, magnesium, titanium. It must be appreciated that the relative abundance of the element is only a crude indication of its potential availability, since a very substantial proportion is present as a minor constituent in practically all igneous rocks. By comparison, present-day ores of titanium are relatively few and are but a minor fraction of the estimated total titanium contained in the earth' s crust.

Jan 1, 1951

By K. Miao, W. Mu, M. Sharma, A. Haas, N. Dogan

"The ever increasing demand for cleaner steels with low inclusion content has highlighted the limits of our current knowledge for controlling and predicting inclusion agglomeration and removal during liquid steel processing. Key knowledge gaps in this area result from the complex nature of the problems associated with measuring and visualizing the phenomena studied. Confocal scanning laser microscope (CSLM) allows for continuous in situ observation of micron-size samples in real time, at high resolution, under conditions relevant to the steelmaking process. This paper summarizes some of recent CSLM applications in our laboratory to illustrate the methods of analyzing transient behavior. The reaction between inclusions and slag is given as an example. The dissolution rate of calcium aluminate inclusions in CaO-SiO2-Al2O3 slags has been studied at elevated temperatures: 1500, 1550 and 1600°C as well as thermodynamic/kinetic analysis. It is found that total dissolution time decreased with increasing temperature. The rate limiting steps are discussed. It is shown that the diffusion through a product layer is responsible for dissolution at 1500°C. At higher temperature, dissolution is most likely controlled by both boundary layer diffusion and chemical reaction at the slag-inclusion interface. In this paper, the evidence for and against the theory will be critically examined and repercussions of the theory to steel refining processes will be discussed.INTRODUCTION Inclusion formation during liquid steel refining is an unavoidable consequence of current ladle steelmaking processes. The nature and quantity of the inclusions formed in steel is critical in steelmaking, as it affects both productivity through clogging, and downstream physical properties of the steel. It is therefore crucial to better understand and control the formation, agglomeration and dissolution behaviour of inclusions in a slag in order to improve the removability of inclusions from liquid steel. Most research (Sandhage & Yurek, 1988; Sandhage & Yurek, 1990a; Sandhuge & Yurek, 1990b; Sandhuge, 1991) relevant to the kinetics of inclusion removal has been obtained by using a technique where simulated inclusion material (ceramic rods) is dipped in slag and the dissolution rate is measured. While much has been learned using this approach, the difference in scale from bulk materials to inclusions is likely to have a significant bearing on the dissolution kinetics of inclusions in a slag and will certainly result in a very different influence of capillary effects. Further, the data obtained using an indirect (dip test) procedure relies on a comparison of the initial and final conditions of a sample rather than in-situ observation which can be achieved in a confocal microscope in real time."

Jan 1, 2017

By M. Dadvand, G. Kipuros, A. Dadvand

"The ability to codeposit fillers within a nickel matrix has led to the production of a new generation of cermet coatings with properties useful for various applications. Hexagonal boron nitride (hBN) is a ceramic-type particulate matter with thermal conductivity, thermal stability, inertness, and lubricity properties that allow it to be codeposited. In this paper, a method was developed for modifying hBN surfaces to allow them to be uniformly dispersed in water-based solutions such as an electroless nickel plating bath. hBN surface modification improved wear performance of the electroless plated cermet due to enhanced interaction between the particulate and nickel matrix. RÉSUMÉ La capacité à effectuer un dépôt simultané de charges dans une matrice nickel a abouti à la production d’une nouvelle génération de revêtements cermet (une combinaison de céramique et de métal) dotés de propriétés très utiles pour diverses applications. Le nitrure de bore hexagonal (h-BN) est une matière particulaire de type céramique utilisée pour ses excellentes conductivité et stabilité thermiques, son inertie ainsi que son caractère lubrifiant, qui permettent son dépôt simultané. Cet article explore une méthode mise au point pour modifier les surfaces du h-BN de manière à ce qu’elles se répandent uniformément dans des solutions aqueuses telles qu’un bain de dépôt autocatalytique de nickel. La modification des surfaces du h-BN a amélioré la résistance à l’usure du placage autocatalytique du cermet en raison d’une interaction accrue entre la matière particulaire et la matrice nickel.INTRODUCTION Electroless nickel alloy coatings can be used for many applications; however, the need for improved tribological properties such as higher wear resistance and better lubricity has increased interest in incorporating particulates (fillers) into the nickel matrix by codepositing the particulates with nickel during the plating process. The selection of the particulate type depends on the desired properties (Sahoo & Das, 2011; Sudagar, Lian, & Sha, 2013). In terms of tribological applications, electroless nickel-based composites are categorized mainly into lubricating and wear-resistant composite coatings depending on the type of particles incorporated. The electroless nickel-phosphorus (Ni-P) composite coatings are composed of codeposited solid lubricants such as polytetrafluoroethylene (PTFE), graphite, WS2, MoS2, and hexagonal boron nitride (hBN) and, compared to nanocomposite electroless Ni-P coatings, they demonstrate a lower coefficient of friction. On the other hand, the nickel-phosphorus wear-resistant composite coatings are composed of hard particles such as silicon carbide (SiC), aluminum oxide (Al2O3), boron carbide (B4C), silicon nitride (Si3N4), diamond, tungsten carbide (WC), and zirconium oxide (ZrO2) and, compared to nanocomposite electroless Ni-P coatings, they have higher hardness and better wear resistance (Sahoo & Das, 2011; Sudagar et al., 2013; Parucker, Klein, Binder, Ristow, & Binder, 2014; Chakarova, Georgieva, Petrova, Dobreva, & Stoychev, 2016)."

Jan 1, 2018

By W. Tse, D. Wong

Dense medium separation (DMS) is one of several preconcentration methods used for early waste rejection from run of mine ores at relatively coarse particle sizes prior to additional milling and beneficiation. DMS has been used extensively in the coal, diamond and iron ore industries but lab scale and pilot test work has demonstrated successful separation and upgrading of other minerals such as lead, zinc, copper and lithium based ores using DMS. This paper reviews historical dense media systems, results from the pilot scale Condor DMS system as well as associated laboratory heavy liquid separation (HLS) test work.

Jan 1, 2014

By G. F. Carr

"IntroductionFLUORSPAR has been found at several •localities in Newfoundland, but all the commercial deposits discovered to date are in the vicinity of St. Lawrence, a town on the southeast coast. Most of the veins are within six miles of St. Lawrence harbour, and between sea-level and an altitude of 400 feet. The St. Lawrence Corporation of Newfoundland, Limited, and Newfoundland Fluorspar, Limited, a subsidiary of the Aluminum Company of Canada. Limited. are the two producers.With the arrival of 1953, the St. Lawrence area entered upon its twenty-second •consecutive year as a producer of fluorspar. Production has increased more or less steadily during this period, as is shown by the fact that approximately one-half of the total shipments to date have been made during the past six years. Between four and five hundred men are employed by the industry, and more than $1,250,000 was paid out in wages and salaries during 1952. Shipments during that year reached an all-time high of 81,283 tons valued at $2,484,943, compared with 67,925 tons valued at $1,966,477 in 1951 (1).As a result of an agreement made in July, 1952, with the United States Defence Materials Procurement Agency, production of the St. Lawrence Corporation, Limited, and St. Lawrence Fluorspar, Incorporated, an affiliated company, will •be increased by .approximately 50,000 tons of acid-grade fluorspar per year. The contract extends over a period of four years, or until 150,000 tons of acid-grade concentrates have been produced."

Jan 1, 1954

By W. Cholewa, T. S. Golosinski, J. Wedzicha

"Power requirements of belt conveyor drives are usually estimated based on the calculated belt tension which equals the sum of unit resistances to motion which the belt has to overcome. In most situations, the value of various unit resistances can be accurately predicted using published information (5,6,8,12). A simpler approach calls for use of standard formula and tabulated values of related factors which reflect various features of both the conveyor and the transported material (2,3,7) . None of these approaches is reliable when materials with unique properties are conveyed, nor if applied to conveyors working in extreme climatic conditions. Such is the case of oil sand mines in northern Alberta.There the bitumen content of oil sand causes it to behave in a unique manner. Furthermore the conveyors operate year around, with winter temperatures often lower than - 40°C. It was the objective of presented investigations to quantify the power requirements of conveyors, and related resistance to motion for the conveyors used in oil sand mines during winter operations.The other objective was to quantify the drive power requirements of oil sand conveyors during start-up. These requirements are usually much higher than those during norm al operation, and their quantification is of paramount importance for operation of large conveyors."

Jan 1, 1992

By F. Pinto, C. A. Prato, R. J. Rocca, P. F. J. Huerta Soaje

"The seismic hazard for civil engineering structures is generally defined in terms of deterministic or probabilistic acceleration response spectra at an equivalent rock outcropping. The design of tunnels, however, requires the definition of demands in terms of accelerations at ground surface (near the portals) and in terms of both accelerations and velocities at different depths within the alignment. The design near the portals is controlled by inertial effects and is often times impacted by the possibility of slope instability and rockfall, whereas the design at deep sections is controlled by kinematic effects. These effects are accounted for in practice by introducing deformation patterns in the structure that are related to an assumed wavefield, often times ignoring the effect of the structural stiffness in the response. This paper presents a study regarding the definition of seismic demands for different sections of 14-km long tunnel in the Andes (Argentina-Chile), with a maximum overburden of 1750 m in a seismically active region. The tunnel will pass through volcanic massifs mainly composed by andesites and rhyolites.The study includes the definition of spectrum-compatible seismograms, deconvolution, and definition of accelerations and peak particle velocities for different overburden conditions. A kinematic interaction study for a 500-m tall ventilation chimney shaft is also described, where a simple formulation for the interaction analysis is considered in order to more accurately evaluate shear and bending demands. INTRODUCTIONThe seismic design of linear underground structures, such as shafts and tunnels, generally considers the inertial forces near the shallow sectors (e.g., portals) and the kinematically imposed deformations for the deep sections (e.g., Hashash et al. 2001). The inertial forces are often times evaluated on the basis of design spectra recommended by seismic hazard studies. The kinematic demands for the deeper sections, however, needs to be defined in terms of additional information which is not always indicated by the seismic hazard studies, e.g.; peak particle velocities and accelerations, and their variation with depth. These parameters can be determined by means of a site response analysis, whereby outcrop motions can be deconvoluted in order to evaluate motions inside the ground mass (e.g., Schnabel et al., 1972). Hashash et al. (2001) defines factors that may be used in order to account for attenuation of motions inside the ground mass. However, these factors are provided for depths up to 30 m only, whereas depths of tunnels structures can range up to thousands of meters."

Jan 1, 2015

By G. M. Carrie

Introduction The subject of basic refractories is daily becoming of increased importance in metallurgical processes, and there is a constantly growing necessity for the development of better materials. This fact, together with the realization that Canada possesses one of the best sources of such refractories in the British Empire, if not in the world, made it appear? advisable that the subject be presented to the Empire Mining and Metallurgical Congress at the 1927 meeting. Having been in close touch with developments in the Canadian product during the past five years, G. M. Carrie was requested to prepare such a paper. The Canadian producers of magnesia refractories have succeeded in developing the product to a place where it has almost entirely displaced imported materials from the Canadian market. These developments were made possible by a close study of the methods of preparation of the material, and by an exceedingly careful control of the manufacturing process so as to obtain a thorough blending of the different constituents with the resultant uniformity of composition. This point is very important to the metallurgist, as un-uniform materials are a potent cause of difficulties in most manufacturing processes and the constant trend is towards their elimination. The temperature at which the Canadian material is burned ensures high specific gravity and thorough shrinkage. The grain size of the product is so controlled that the voids are only just sufficient to allow of proper bonding, thus making possible a dense, hard bottom affording high resistance to erosion and shock. Careful proportioning of the constituent elements absolutely prevents disintegration.

Jan 1, 1927

By R. Argane

In this work we assessed the geochemical behavior of concentrator tailings deposited at the abandoned mines of Zeida and Mibladen (Upper Moulouya, Morocco), using physico-chemical analyses, mineralogical characterization, acid base accounting and weathering cell tests. The aim of the study was to evaluate mine drainage quality and to assess metal mobility from these concentrator tailings. Chemical analyses show that the Upper-Moulouya abandoned tailings contain relatively high quantities of lead (0.261 to 0.594 % wt). Mineralogical analyses reveal the abundance of neutralizing minerals (calcite, dolomite, ankerite, and aluminosilicates) which influence mine drainage and metal mobility in mine tailings. Leachate analyses from weathering cell tests show alkaline conditions, small conductivity values, and low solubility of Pb-mineral phases. According to these results, abandoned mine tailings in the Upper-Moulouya district have very low potential for generation of contaminated mine drainage and for leaching of heavy metals. However, the inhalation of tailings exposed to winds generate dust problem facing the local population and may cause health consequences.

Aug 1, 2013

By L. M. Wang, G. P. Jiang, Y. Jiang, Liao. W. S.

ABSTRACT The authors measured porosities and permeabilities for cores from a low-permeability sandstone uranium deposit in Inner Mongolia. Features studied included fine pore structure, mineral composition, cation exchange capacity, granule appearance, and cementing features. In general, grading of the grains was relatively poor, which decreased the radii of the pore channels. The pore throat distribution was significantly heterogeneous. Pore channels ranged from small to large, but the lack of large pore channels led to low permeability. Cementation by calcite and clays, including montmorillonite, chlorite, and kaolinite, resulted in pore channel narrowing, further decreasing the permeability of the formation.

Jan 1, 2014

By F. Doxey

Introduction Numerous papers have been written dealing with the construction and functions of, and the environmental conditions created by, Diesel locomotives. Therefore, it is not my intention to attempt to deal with these phases of Diesel transportation other than to make reference to them in ?relation to and in connection with actual operation. The rapid expansion of industry during recent years and the necessity of products being made available at competitive prices in home and world markets has made the demand for cheaper coal a very serious factor for the coal industry. This condition has meant each coal producing country looking into ways and means whereby greater productivity and reduction in cost could he achieved. Surveys made show that, in addition to face mechanization, savings, in some cases substantial, can be made in transportation. Ventilation The most efficient mines are in-variably the well ventilated ones, for it is true that, where there is good ventilation, there are usually good roads. These combined factors are very essential where Diesel locomotives are used. Good roadways and track allow speed, and good ventilation dilutes rapidly any disagreeable exhaust gases. Locomotive Development In the older types of auxiliary rope haulage, coal hauled per haul-age hand is usually very low.

Jan 1, 1951

By O. G. Olvera

"Refractory sulfidic ores consist of materials in which gold occurs finely disseminated within metallic sulfides or forming solid solutions, with pyrite and arsenopyrite being the two sulfides most commonly associated with gold. Typical cyanide operations show poor performance and require oxidative pretreatments to increase gold recovery. Pretreatment alternatives include roasting, pre-aeration, acidic and alkaline high pressure oxidation, and bacterial oxidation. The presence of arsenic, however, introduces a serious disadvantage to the use of roasting and bacterial leaching, while high pressure oxidation involves high capital costs. This work focuses on evaluating the effect of the addition of a carbon resin as a sulfur collector on the oxidation of different arsenopyrite concentrates under atmospheric tank leaching (ATL) conditions. The addition of the resin improved the oxidation of sulfides and favored the formation of elemental sulfur over the generation of sulfate. The use of AF5 in ATL resulted in higher gold recoveries under standard cyanide carbon-in-leach and thiosulfate leaching.INTRODUCTION Refractory sulfidic ores consist of materials in which gold occurs finely disseminated within metallic sulfides or forming solid solutions, with pyrite and arsenopyrite being the two sulfides most commonly associated with gold. Gold is not readily accessible to solutions in these types of ores and typical cyanide operations show poor performance, thus making the use of oxidative pretreatments a requirement to increase gold recovery. Pretreatment alternatives include roasting, pre-aeration, acidic and alkaline high pressure oxidation, and bacterial oxidation. The presence of arsenic, however, introduces a serious disadvantage to the use of roasting and bacterial leaching, while high pressure oxidation involves high capital costs. The use of carbonaceous materials to enhance the dissolution of sulfides is not novel, and leaching additives such as coal, activated carbon and carbon powder have been considered for the improvement of bioleaching, atmospheric leaching, and pressure oxidation leaching processes. However, this type of technology has been focused mainly on the recovery of copper from copper concentrates containing chalcopyrite with less attention paid to other sulfides."

Jan 1, 2017

By D. Emadi

The ASTM B108 Mould and a Modified Mould were used to cast test bars under a variety of conditions: mould and pouring temperatures, mould coating and tilt. Mechanical properties were determined in the as-cast and heat-treated conditions. The ASTM Mould is less sensitive to casting variables. Enlarging the gating system and adding additional gates to the ASTM mould can improve properties in the tilt position. The reproducibility of properties in as-cast and T6 heat treated bars was investigated.

Jan 1, 2004

By Technische Universität Braunschweig, K. Saksl, J. Furste, P. Eschenbacher, F. Brunke, D. Wolter, M. Kohnke, C. Siemers, J. Kiese, M. Schlemminger

"In general, titanium alloys combine outstanding mechanical properties with corrosion resistance and biocompatibility and are, therefore, used in many challenging applications. Nevertheless, for special products, well-tailored properties are required which might not be achievable by a specific design so that new or modified alloys are needed. In this overview paper, alloy development strategies performed at the Institute for Materials of the Technische Universitat Braunschweig are discussed at different examples, namely, (1) oxidation-resistant, microstructural-stabilized and cold-workable alloys for exhaust applications, (2) aluminum- and vanadium-free, medium-strength and cold-workable alloys for implants and osteosynthesis applications and (3) free-machining alloys by the addition of particles with low melting points for non-safety critical light-weight constructions to replace heavier steels, e.g. in automotive applications. A special focus is set on the alloy development techniques and the analyses carried out to achieve well-balanced properties by the optimization of the alloy compositions. INTRODUCTIONTitanium belongs to the allotropic metals and can therefore exist in two different equilibrium lattice modifications. Pure titanium crystallizes at 1668°C in a body centered cubic (bcc) structure called ?- titanium which at 882°C transforms to a hexagonal close packed structure (hcp), the a-titanium. A martensitic ?-to-a-transformation is possible at large cooling rates. This thermally induced hexagonal martensite is called the a'-phase. The transformation temperature named ?-transus-temperature (T ?) can be influenced by alloying elements (Peters & Leyens, 2002).For titanium alloy production typical alloying elements are aluminum (Al) and oxygen (O), both a-stabilizers shifting the ?-transus temperature to higher temperatures, whereas tin (Sn) and zirconium (Zr) only show a limited influence on the ?-transus temperature. The ?-stabilizing elements are subdivided into two groups: Niobium (Nb), molybdenum (Mo) and vanadium (V) stabilize the ?-phase between the melting point and room temperature and are therefore called isomorphous -stabilizers. Elements like copper (Cu), iron (Fe) or silicon (Si) also stabilize the ?-phase to lower temperatures but undergo a eutectoid reaction during cooling. ?-titanium then dissociates to a-titanium and an intermetallic compound. Consequently, these elements are called eutectoid ?-stabilizers (Boyer, Welsh & Collings, 1994)."

Jan 1, 2016

By Jamel Sgaoula

During 1998 COGEMA Resources Inc. announced that operations at the Cluff Lake mine will be suspended indefinitely by the end of year 2000 as a result of deteriorating uranium market conditions. To remain profitable, Cluff Lake mine started an aggressive cost reduction program. A cost reduction team was formed to look for ways to lower production costs. The focus of this team was to screen all areas and to come up with ideas to improve the economy of the mine and ensure the viability of the operations over the remaining three years of operations. Among the areas where significant savings were achieved are: (1) replacement of portion of cement with fly ash in backfill; (2) backfill optimization; and (3) new shotcrete plant installation on site for bulk in-house shotcrete production. This paper details the research work carried out by Cluff Lake mine on these projects and results of its application.

May 1, 2001

By P. C. Benedict

"The Island Mountain mine is at the southeast end of Island mountain; across Jack of Clubs lake from the Cariboo Gold Quartz mine.; The orebodies consist of quartz veins and pyritic replacement deposits in limestone. To December 31; 1944; there has been mined 296; 273 tons of quartz-vein ore averaging about 0.34 oz. gold a ton; and 101; 002 tons of sulphide ore averaging about 0.83 oz. gold a ton; a total of 397; 275 tons averaging 0.46 oz. From this; 175; 985 fine oz. of gold and about 26; 450 fine oz. of silver were recovered; having a value of $6; 510; 521.More than 95 per cent of the production has come from a band 500 feet wide along the contact of the Rainbow and overlying Baker members and extending about 100 feet into the latter. Evidence that the Rainbow belongs stratigraphically above the Baker is presented later in this paper. Both members are most variable lithologically, and individual beds and whole series of beds pinch out in short distances. In part, at least, this is due to squeezing out incidentally to intense folding. No section can be claimed with assurance to be really representative. However, both memb.ers are composed predominantly of quartzitic rocks. Both contain argillaceous quartzite, argillite, limy quartzite, limy argillite, limestone (marble), and minor amounts of highly ankeritized rocks believed to be igneous sills possibly originally approaching diorite in composition."

Jan 1, 1954

To determine the optimal circuit configuration for gravity gold recovery consideration should be given to a range of factors in addition to the efficiency of the gravity circuit, including capital costs, ease of operation and impact on comminution. The most common gravity gold circuits utilise a centrifugal concentrator treating a portion of the hydrocyclone underflow. This paper will examine this option and alternative circuit configurations to illustrate the effect of various gravity circuit feed and tailings configurations on the equipment sizing, capital costs, operating costs, water balance, comminution efficiency and gravity gold recovery. The optimum circuit configuration can provide reduced capital and operating costs, maximise gravity gold recovery and improve comminution efficiency.

Jan 1, 2011

By L. Zeng, Q. Feng, Z. Qiu, L. Ou, Central South University

It is well-known that the use of nanobubbles can significantly improve the flotation efficiency of ultra-fine particles. However, this is mainly focused on coal and phosphate rock flotation. In the field of nonferrous metal processing, the related research is few. In this paper, a small laboratory mechanical cell associated with a specially-designed nanobubbles generator was used to investigate the effects of nanobubbles on enhancing ultra-fine scheelite flotation. Nanobubbles were created and based on the hydrodynamic cavitation principle through Venturi tubes. Comparative flotation tests were performed using different tubes to evaluate the nanobubbles impact on the ultra-fine scheelite particle flotation recovery. In order to better understand the nanobubbles enhanced ultra-fine scheelite flotation, nanobubbles potential and size distribution were measured. The effect of nanobubbles on the particle aggregation and scheelite particles potential were also studied through the turbidity tests, microscope tests and zeta potential measurements. According to the results, the mean size of nanobubbles was about several hundred nanometers, and the surface of nanobubbles was of highly negative charge in alkaline conditions. The flotation recovery of ultra-fine scheelite particles was increased in the presence of nanobubbles. The zeta potential measurements indicated that the repulsive forces between scheelite particles decreased when nanobubbles existed. Through the turbidity tests and microscope tests, the promotion effect of nanobubbles on particle coagulation could be verified more directly. The existence of nanobubbles in flotation system promotes the particle aggregation, thus increasing particles apparent size and particles capture by bubbles, which may be the fundamental reason why nanobubbles enhance ultra-fine scheelite flotation.

Jan 1, 2016

By Z. Luo, China University of Mining & Technology, C. Duan

"The magnetic separation removal rate of pyrite could be improved effectively by increasing the susceptibility of pyrite. The electromagnetic characteristics and absorption response performance of high-sulfur fine coal were studied in strengthening the susceptibility of pyrite. In the process of treating the sample through the microwave, electromagnetic energy could be converted into heat energy due to dielectric loss and magnetic loss. The RL(dB) was evaluate the performance of absorption response of coal. The microwave improved the susceptibility was in ultra-high frequency region, which is the most natural resonance. The absorption fine coal to microwave was strengthened and microwave energy was improved by adding the magnetite powder with double loss characteristics as the microwave absorber. The dielectric properties and permeability characteristics of the fine coal trend were investigated by maxing magnetite powder. The microwave absorption in different coal thickness was surveyed through the reflection of energy loss.INTRODUCTIONMicrowave desulfurization is one of the most important research directions (Haque, 1999; Makul, Rattanadecho, & Agrawal, 2014; Su, Tang, Zhang, Jing, & Bai, 2014). The working principle of microwave absorption response can be briefly described as the interaction of the sample with microwave energy, which will result in the microwave energy converting into heat energy loss (Keangin & Rattanadecho, 2013). For specific samples, the polarization effect includes multiple polarization mechanisms(Meikap, Purohit, & Mahadevan, 2005). Different polarization mechanisms have different occurrence time and dominant mechanisms. Meantime, energy consumption will be occurred during the process of polarization effect (Chelgani & Jorjani, 2011; Rowson & Rice, 1990) . The absorption of microwave energy in the fine coal is a process of electromagnetic response (Znamenácková, Lovás, Mockovciaková, Jakabský, & Briancin, 2005). Microwave transfers the electromagnetic waves into the heat energy by microwave dielectric loss and magnetic loss for achieving the absorption of microwave energy in the treatment of samples (Lee, Kim, Kim, Chung, & Kim, 2004). The additive magnetic medium is Fe3O4 belonging to microwave energy absorber of double loss medium (Uslu, Atalay, & Arol, 2003)."

Jan 1, 2016

By G. B. Hudson

Previous papers (1, 2) pertaining to the treatment of uranium-bearing ores were concerned with the flotation of the radioactive minerals. In this investigation, the application of flotation to the removal of acid-consuming minerals from uranium ores was considered. Two pitchblende-bearing ores, which, because of the presence if dolomite were abnormally high acid consumers, were studied. In both in-stances commercial reagents of widely varying fatty acid composition proved satisfactory as flotation col-lectors, particularly at a pH of 10.5, for the carbonate minerals. From an economic viewpoint, however, Neo-Fat 42-12 was favoured. A mixture of sodium tripolyphosphate and citric acid was an effective depressant for the pitchblende in the ores. The tailings remaining after the removal of the dolomite by flotation contained, in one case, 88.5 per cent of the uranium in the original sample, and, in the other, 93.8 per cent. Analyses conducted on these tailings and on the original ores showed that

Jan 1, 1963