Sloan, E.D., Koh, C.A., "Clathrate Hydrates of Natural Gases", Third Edition, CRC Press, Taylor & Francis Group, (2008). [3] Karamoddin, Maryam., Varaminian, Farshad., Solubility of R22, R23

One of the effective factors on the efficiency of the flotation process, is bubble size distribution. Bubble size influences the bubble/particle collision, attachment and detachment probability. In this paper, size distribution of bubbles produced in a laboratory mechanical flotation cell, has been investigated by the direct image analysis method. In addition, effect of some important parameters such as frother concentration, pH value and temperature on bubbles size have been studied. In order to sample bubbles for imaging, bubble viewer with a viewing chamber was designed and made. Images were analyzed using Image J Ver. 1.44 software. To reduce number of bubbles in imaging zone and minimizing bubble overlap, the tube diameter was chosen small as much as possible so that quality and accuracy of image analysis were improved. In addition, by covering side walls of viewing chamber, light entrance from these walls was prevented and images quality was enhanced. Moreover, by photography field depth adjustment and also applying suitable lens, existing problems in previous studies such as bubble overlap and error induced by perspective were improved. To minimize bubble diameter standard deviation, 200 images per experiment were taken and some of them were randomly chosen analyzed. Study of frother effect on bubble size showed that with increase of frother concentration from 10 ppm to 60 ppm, Sauter diameter (d32) of bubbles decreased from 910 mm to 706 mm. with increasing pH from 4 to 10.4, in sync with increase of zeta potential absolute value, d32 of bubbles decreased from 1020 mm to 754 mm and bubble size distribution curve became similar to normal distribution. Furthermore, increase of temperature from 10 °C to 47 °C, resulted enlargement of Sauter diameter of bubbles from 611 mm to 830 mm.