| 1. |
- Bahrami, Ataallah, et al.
(författare)
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Effect of different reagent regime on the kinetic model and recovery in gilsonite flotation
- 2019
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 8:5, s. 4498-4509
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Tidskriftsartikel (refereegranskat)abstract
- Gilsonite is a natural fossil resource, similar to an oil asphalt high in asphaltenes. To determine the effect of reagent regime on the kinetic order and rate of flotation for a gilsonite sample, experiments were carried out in both rougher and cleaner flotation process. Experiments were conducted using different combinations of reagent: Oil-MIBC; gasoline-pine oil; and one test without any collector and frother. According to results, kinetic in the test performed using the oil-MIBC and without any collector and frother were found to be first-order unlike the kinetic in the test conducted using the gasoline-pine oil. Five kinetic models were applied to the modeling of data from the flotation tests by using MATrix LABoratory software. The results show that all experiments are highly in compliance with all models. The kinetic constants (k) in rougher stage were calculated as 0.1548 (s-1), 0.2300 (s-1) and 0.2163 (s-1) for oil-MIBC, gasoline-pine oil, and test without any collector and frother, respectively. These amounts in the cleaner stage were 0.0450 (s-1), 0.1589 (s-1) and 0.0284 (s-1), respectively. The relationship between k, maximum combustible recovery (R) and particle size was also studied. The results showed that the R and k were obtained with a coarse particle size of (-250 + 106) μm in the rougher and (-850 + 500) μm in cleaner flotation processes.
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| 2. |
- Chelgani, Saeed Chehreh, et al.
(författare)
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A comparative study on the effects of dry and wet grinding on mineral flotation separation : a review
- 2019
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 8:5, s. 5004-5011
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Forskningsöversikt (refereegranskat)abstract
- Water scarcity dictates to limit the use of water in ore processing plants particularly in arid regions. Since wet grinding is the most common method for particle size reduction and mineral liberation, there is a lack of understanding about the effects of dry grinding on downstream separation processes such as flotation. This manuscript compiles various effects of dry grinding on flotation and compares them with wet grinding. Dry grinding consumes higher energy and produces wider particle size distributions compared with wet grinding. It significantly decreases the rate of media consumption and liner wear; thus, the contamination of pulp for flotation separation is lower after dry grinding. Surface roughness, particle agglomeration, and surface oxidation are higher in dry grinding than wet grinding, which all these effects on the flotation process. Moreover, dry ground samples in the pulp phase correlate with higher Eh and dissolved oxygen concentration. Therefore, dry grinding can alter the floatability of minerals. This review thoroughly assesses various approaches for flotation separation of different minerals, which have been drily ground, and provides perspectives for further future investigations.
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| 3. |
- Dalibon, Eugenia. L., et al.
(författare)
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Characterization of DLC coatings over nitrided stainless steel with and without nitriding pre-treatment using annealing cycles
- 2019
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Ingår i: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMRandT. - : ELSEVIER SCIENCE BV. - 2238-7854. ; 8:2, s. 1653-1662
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Tidskriftsartikel (refereegranskat)abstract
- Amorphous hydrogenated diamond-like carbon (DLC) coatings were deposited using plasma assisted chemical vapour deposition (PACVD) on precipitation hardening (PH) stainless steel.Plasma nitriding has been used as pre-treatment to enhance adhesion and mechanical properties. Chemical and mechanical properties of DLC coatings are dependent on the hydrogen content and so on the relation between sp(3)/sp(2) bondings. The bondings and the structure of the DLC film change with temperature. In this work, a study of the thermal degradation and the evolution of the mechanical properties of DLC coatings over PH stainless steel have been carried out, including the effect of an additional nitrided layer. Nitrided and non-nitrided steel samples were subjected to the same coated in the same conditions, and they were submitted to the same thermal cycles, heating from room temperature to 600 degrees C in several steps. After each cycle, Raman spectra and surface topography measurements were performed and analyzed. Nanohardness measurements and tribological tests, using a pin-on-disc machine, were carried out to analyze variations in the friction coefficient and the wear resistance. The duplex sample, with nitriding as pre-treatment showed a better thermal stability. For duplex sample, the coating properties, such as adhesion, and friction coefficient were sustained after annealing at higher temperatures; whereas it was not the case for only coated sample. (C) 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.
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