1、1 英文翻译原文Effects of simultaneous ultrasonic treatment on flotation of hard coal slimes Safak Gokhan Ozkan Istanbul University, Engineering Faculty, Mining Engineering Department, 34320 Avcilar, Istanbul, Turkeya r t i c l e i n f o Article history: Received 19 January 2011 Received in revised form 18
2、 October 2011 Accepted 18 October 2011 Available online 1 November 2011Keywords: Hard coal slimes Coal flotation Simultaneous ultrasonic treatment Physico-chemical propertiesa b s t r a c t In this study, effects of simultaneous ultrasonic treatment on flotation of original and aged hard coal slimes
3、 were investigated with aiming to recover more combustible and good quality products. Conventional and ultrasonically assisted flotation tests of original and aged coal slimes were performed by using Montanol-531, a special coal flotation reagent, at variable dosages. The results of the batch flotat
4、ion tests revealed that simultaneous ultrasonic treatment increased combustible recovery and lowered ash values of concentrates compared to the conventional flotation conditions despite using similar reagent dosages. These results were also verified by testing some physico-chemical properties of the
5、 samples, i.e. temperature, pH, oxidationreduction potential, and zeta potential. Finally, it is concluded that a thorough surfacecleaning by cavitation due to power ultrasound might improve the flotation recovery compared with the conventional flotation conditions, even though very slight changes w
6、ere also observed in some physico- chemical properties of the treated samples.1. Introduction Flotation is influenced by a large number of material, chemical, equipment and operational variables. Changing of one of these variables significantly affect flotation performance such as grade and recovery
7、. Ultrasonic treatment is one of the important pretreatment methods, which is used to advance flotation process 18. Main effects of ultrasonic treatment on a flotation system are characterized by cavitation, and are accompanied by a local increase in pressure and temperature. As solidliquid interact
8、ions are weaker than liquid cohesion forces, solidliquid interfaces are more amenable to the formation of cavitation. The unsettled conditions caused at a solidliquid interface might modify surface properties of minerals, leading to changes in adsorption of reagents at mineral surfaces, hence their
9、flotation responses. For this reason, ultrasonic pre-treatment might improve effectiveness of reagent molecules at surfaces due to their more uniform distribution insuspension, and this causes an enhancement of activity of chemicals used 918. In this study, effects of simultaneous ultrasonic treatme
10、nt on froth flotation of original and aged hard coal slime samples were investigated in detail. The optimization of hard coal slimes flotation parameters was conducted by comparison of yield, ash value, and combustible recovery produced by conventional and ultrasonically assisted flotation cells. Ad
11、ditionally, some physicochemical properties of the samples, i.e. temperature, pH, oxidation reduction and zeta potential were taken into considerationin order to explain the effects of ultrasonic treatment on the Process.2. Materials and methods2.1. Materials Representative hard coal slime samples i
12、n pulp used in this study were previously supplied from the flotation feed section of Prosper-Haniel Coal Preparation Plant situated in Bottrop, Ruhr Region of Germany. The samples were stored at a suitable atmosphere in their original conditions for approximately 4 years in order to obtain the aged
13、 coal samples for the consequent flotation experiments. Fig. 1 presents the particle size distribution, calorific value, ash and sulfur contents of the original (as received) and aged (stored for 4 years) hard coal slime samples on dry basis. As seen from Fig. 1, the aging process caused considerabl
14、e changes on the properties of the samples. Comparison of weight, ash content, calorific value, and sulfur content of original and aged coal samples according to different particle size fractions can be seen from Fig. 1ad, respectively. Although these values for original and aged coal samples follow
15、 the similar trends against particle size fractions, the aging process certainly increase the weight portion of finer particle size fractions (below 125 lm) than the larger particle size fractions (above 125 lm). While the aging process negatively affects calorific values, sulfur contents are slight
16、ly affected. In terms of ash content, aged coal contains higher values for larger particle size fractions, whereas finer particle size fractions have lower ash contents after the aging processFig. 1. Comparison of the original and the aged hard coal slime samples (a) size distribution, (b) ash content (c) sulfur content (on dry basis), and (d) calorific value.
