63,585 research outputs found

    Study of Some Factors Which Influence Froth Flotation of Deinked Stock

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    Mineral and fiber were concurrently reclaimed from coated waste stock with the froth flotation process. Percentages of ash and fiber reclaimed are included along with the brightness of the deinked stock. A suitable cooking formula and two flotation systems were discovered which respond favorably to froth flotation and yield a relatively high brightness before bleaching

    Beneficiation of rare earth minerals from Bokan Mountain: Dotson Ridge ore

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    Thesis (M.S.) University of Alaska Fairbanks, 2014The purpose of this research work was to study the beneficiation of rare earth ore of the Bokan Mountain -- Dotson Ridge deposit, located near Ketchikan, Alaska. Rare earth element (REE) composite ore samples from the Bokan Mountain -- Dotson Ridge deposit were tested using gravity concentration, magnetic separation, flotation, and leaching techniques to separate the REE. The composite ore sample was a product of a preliminary x-ray sorting process. Qualitative electron microprobe analysis of the ore showed that most of the REE minerals in the ore were silicate minerals. Since the electron microprobe analysis samples were coated with carbon during sample preparation, the carbon element was inactivated for analysis. Because of this, carbonate compounds of minerals' particles could not be detected. 95% of the REE mineral particles appear to be smaller than about 10 μm in size (about 100 μm² in area). For the gravity concentration, light rare earth elements (LREE) and heavy rare earth elements' (HREE) individual elemental recovery values were in the ranges of 49.6-52.8% and 46.3-48.8%, respectively, at 25% of mass yield. In order to separate a larger amount of the REE, a wet high intensity magnetic separation (WHIMS) test was carried out on tailings of the gravity concentration tests. The HREE individual elemental recovery values ranged from 56.3-63.1% at 37% mass yield, while LREE individual elemental recovery values were in the 57.9% - 59.1% range. For the combined gravity and magnetic separation processes, the net individual elemental recovery values of the LREE and the HREE were in the range of 79.6-80.5% and 76.5-80.9%, respectively. The combined mass yield of the gravity and magnetic separation processes was 3%. Direct leaching tests conducted on the composite ground ore feed yielded high individual elemental recovery values of 90-92% of the LREE. The HREE individual elemental recovery values ranged from 56.5-87.3%. In the leaching, 20% HCl was used in the 1st and 2nd stages with a duration of 2 hrs in each stage at 90°C. The solid percentage of the leach slurry was 20% w/w. The composite ground ore sample was tested in conventional flotation using a 2.0 L capacity Denver cell. In the flotation, 0.05 kg/tonne of Cytec Aero 6493 collector, 0.05 kg/tonne of Cytec Aero Froth 88, and 0.1 kg/tonne of sodium metasilicate as a depressant were used. Pulp pH was set around 9. Results showed individual elemental recovery values in the range of 44.6-50.4% or the LREE. The HREE individual elemental recovery values ranged from 27.9-44.5%. The mass yield of the flotation was 23%. The flotation recoveries reported here are significantly lower than what was achieved previously. For the Leach after flotation process, leaching was conducted on the first concentrate of flotation. Individual elemental recovery values of the LREE and HREE were 94.7-96.5% and 61.1-90.5%, respectively. The concentrate was leached using 20% HCl in both the 1st and 2nd stages, with a duration of 2 hrs in each stage at 90°C. Flotation/Leach process net recoveries of LREE by individual elemental values ranged from 42.2-48.5%. HREE net recoveries by individual elemental values ranged from 17.1-41.4%.Chapter 1 Introduction and Objectives -- Chapter 2 Literature Review -- 2.1 Gravity separation of REE ore -- 2.2 Magnetic separation of REE ore -- 2.3 Froth flotation of REE ore -- 2.4 Leaching of REE -- 2.5 Mineral processing of Bokan Mountain: Dotson Ridge REE ore -- 2.5.1 Mineralogical property -- 2.5.2 Froth flotation -- 2.5.3. Leaching -- 2.5.3.1 Direct leaching -- 2.5.3.2 Leach after flotation -- Chapter 3 Methods and Materials -- 3.1 Materials -- 3.2 Gravity separation tests -- 3.3 Wet high intensity magnetic separation tests -- 3.4 Froth flotation tests -- 3.5 Leaching tests -- 3.5.1 Direct leaching -- 3.5.2 Leach after flotation -- 3.6 Electron microprobe analysis of REE mineralogy -- Chapter 4 Results and Discussion -- 4.1 Gravity separation -- 4.2 Wet high intensity magnetic separation -- 4.3 Froth flotation -- 4.4 Leaching -- 4.4.1 Direct leaching -- 4.4.2 Leach after flotation -- 4.5 Electron microprobe analysis -- 4.5.1 Mineralogy of the ore -- 4.5.2 Mineralogy of flotation concentrate -- Chapter 5 Conclusions and Recommendation -- 5.1 Conclusions -- 5.2 Recommendation for future work -- References -- Appendices

    Ferric chloride leaching of the Delta sulfide ores and gold extraction from the leaching residue

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    Conventional differential and bulk flotation processes have difficulties in achieving high recoveries with acceptable grades far zinc, lead and copper from the complex sulfide ores found at Tok, Alaska. Furthermore, gold and silver, which account for a significant fraction of total value of the ores, are distributed evenly in the flotation tailings and concentrate. Therefore, processing both flotation tailings and concentrate would be necessary to obtain high recoveries of gold and silver. A mineralogical study revealed that the economic sulfide minerals are interstitially associated with a large preponderance of pyrite. The economic sulfide minerals are 10 to 40 microns in size. These mineralogical facts explain the difficulties encountered in the flotation process. A hydrometallurgical method involving ferric chloride leaching and subsequent steps to recover lead, zinc, silver and copper from the leach liquor has been studied at the Mineral Industry Research Laboratory, University of Alaska Fairbanks for the treatment of Delta ores. This alternative is attractive for processing complex sulfide ores which conventional flotation and smelting cannot handle. In addition, the liberation of sulfur in the environmentally acceptable elemental form, rather than as sulfur dioxide, may prove a major advantage of this hydrometallurgical method because of stringent environmental regulations

    Stock market liquidity and the rights offer paradox.

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    This paper contributes to the resolution of the rights offer paradox, using a database of French SEOs. We first document higher direct flotation costs, but also improved stock market liquidity after public offerings and standby rights relative to uninsured rights. We find that blockholder renouncements to subscribe to new shares and stock market liquidity are important determinants of flotation method choice. After controlling for endogeneity in the choice of flotation method, we find that public offerings are cost effective and more liquidity improving than standby rights whereas an uninsured rights offering is the best choice for low liquidity, closely held firms. Our results provide new insights as to why firms choose public offerings despite apparently higher costs.bid-ask spread; Security offering; SEO; flotation method; flotation costs; rights issues; public offerings; liquidity;

    Hydro tropes as promoters in soap flotation

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    Soaps, the salts of fatty acids are generally used as collectors in the flotation process to separate salt type minerals. Some times light diesel oil is mixed with soaps and the emulsion is used as collector. Addition of detergents to soaps not only enhances the collector efficiency but also reduces the consumption of soap. Urea a known hydro trope is found to improve the flotation efficiency of soaps. Our current testing is indicating that other hydro tropes such as tri sodium citrate and sodium salicylate are also effective in improving the flotation efficiency of soap and also the soap-LDO emulsion

    Hydrometallurgy of the delta sulfide ores, first stage report

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    This report presents the results of hydrometallurgical research carried out from September 16, 1985 to June 30, 1986 on metals recovery from complex sulfide ores from the Delta deposit near Tok, Alaska. The leaching characteristics performed for 6 different ore samples indicate that the most valuable components form the following order: Zn > Au > Pb > Ag > Cu > So. Further study demonstrates that direct leaching of the ore is effective both in chloride as well as in sulfate oxidizing solutions coupled with separating of leached solid components by flotation. Three variants of the ore processing with ferric chloride or fenic sulfate leaching are analyzed: one flowsheet with direct ore leaching in ferric chloride solution followed by leaching-flotation step, with subsequent zinc separation in a solvent extraction step and electrolysis in chloride solution; and two flowsheets of direct ore leaching with ferric sulfate solution followed by a leaching-flotation step, with zinc sulfate electrolysis and other metals recovery in chloride leaching sreps. In two last flowsheets silver is recovered during the chloride leaching steps and gold h m flotation products during the cyanide leaching. Preliminary economic and technical evaluation is presented. The engineering study on apparatus for the fast leaching- flotation processing and on better accumulation of gold and silver in one semi-product are concluded for the next year of research

    Stock market liquidity and the rights offer paradox.

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    This paper contributes to the resolution of the rights offer paradox, using a database of French SEOs. We first document higher direct flotation costs, but also improved stock market liquidity after public offerings and standby rights relative to uninsured rights. We find that blockholder renouncements to subscribe to new shares and stock market liquidity are important determinants of flotation method choice. After controlling for endogeneity in the choice of flotation method, we find that public offerings are cost effective and more liquidity improving than standby rights whereas an uninsured rights offering is the best choice for low liquidity, closely held firms. Our results provide new insights as to why firms choose public offerings despite apparently higher costs.Bid-ask Spread; Public Offerings; Rights Issues; Flotation Costs; Flotation Method; SEO; Security Offering; Liquidity;

    TEST OF MICROBIAL TRANSFORMATION OF FLOTATION TAILINGS TO CONSTRUCTION MATERIAL

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    The use and recycling of secondary raw materials increases resource efficiency. An interesting option would be the use of flotation tailings in the production of building materials. One of challenges is the content of mobilizable metals in the residues for ecological quality reasons of building material. Since flotation residues contain low metal concentration they are suitable for bioleaching approaches

    Utilization of flotation in copper extraction from polymetallic ore

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    The aim of this study was to examineflotation of utility metals from poor polymetallic ores and verify the potential for profitable yields in connection withpotentially economic deposits of non-ferrous metals.The paper describes results in flotation concentrate research to recover copper from polymetallic ore. The polymetallicore from Zlate Hory deposit (Czech Republic) was subjected to crushing, grinding, and screening to prepare feed for separation with mesh size under 200 microns. The heavy medium separation was performed in tetrabromethane with a density of 2.967 g.cm-3. The float and sink products were obtained and tested for chemical composition. Next, the treated polymetallic ore sample was subjected to flotation. In flotation,various dosages of collector (PAX) and various pH were tested, at which pyrite was depressed. The recovery of metallic copper in the concentrate increased with the collector dose. As the pH of the medium increased, the pyrite content in the concentrate dropped. The lowest contentof pyrite, i.e. 4.01%,was obtained at pH 10. In the original polymetallic ore, the Cu content was 0.41% after subsequent treatment and flotation tests, the Cu content increased to 1.38 % with Cu recovery 86.18%

    Evaluation of laboratory methodologies for froth flotation of feldspar and kaolin

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    This report describes work carried out to establish and evaluate methodologies for the laboratory froth flotation of feldspar and kaolin. One of the main aims was to ascertain the feasibility of separating glass-grade feldspar from granite quarry dust and [meso As part of this, a method for HF-free froth flotation of feldspar was evaluated. This work was carried out as part of the ongoing 'Maintenance of capability in Mineral Sciences' project, 75C
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