Measurement of Bubble Size in Flotation Column using Image Analysis System

Ki-Seon An; Ho-Seok Jeon; Chul-Hyun Park

doi:10.7844/kirr.2020.29.6.104

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2020 Vol.29, Issue 6 Preview Page Next Page

Research Paper

Measurement of Bubble Size in Flotation Column using Image Analysis System 이미지 분석시스템을 이용한 부선컬럼에서 기포크기의 측정

31 December 2020. pp. 104-113

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Abstract

Bubble size in froth flotation has long been recognized as a key factor which affects the bubble residence time, the bubble surface area flux (S_b) and the carrying rate (C_r). This paper presents method of bubble size measurement, relationship between operating variables and gas dispersion properties in flotation column. Using high speed camera and image analysis system, bubble size has been directly measured as a function of operating parameters (e.g., superficial gas rate (J_g), superficial wash water rate (J_w), frother concentration) in flotation column. Relationship compared to measured and estimated bubble size was obtained within error ranges of ±15~20% and mean bubble size was 0.718mm. From this system the empirical relationship to control the bubble size and distribution has been developed under operating conditions such as J_g of 0.65~1.3cm/s, J_w of 0.13~0.52cm/s and frother concentration of 60~200ppm. Surface tension and bubble size decreased as frother concentration increased. It seemed that critical coalescence concentration (CCC) of bubbles was 200ppm so that surface tension was the lowest (49.24mN/m) at frother concentration of 200ppm. Bubble size tend to increase when superficial gas rate (J_g) decreases and superficial wash water rate J_w and frother concentration increase. Gas holdup is proportional to superficial gas rate as well as frother concentration and superficial wash water rate (at the fixed superficial gas rate).

Keywords

Bubble size

Frother

Gas rate

Wash water rate

Flotation column

기포크기는 컬럼부선에서 기포체류시간, 기포표면적플럭스(S_b) 및 운송율(C_r)에 영향을 미치는 중요 변수로 인식되고 있다. 본 논문은 부선컬럼에서 기포크기의 측정방법, 가동변수들의 관계 그리고 가스분산특성을 논한다. 기포크기는 고속카메라와 이미지 분석 시스템을 이용하여 가동변수들(가스속도, 세척수속도, 기포제농도)의 조건에 따라 부선컬럼에서 직접적으로 측정되었다. 각 측정과 산정된 기포크기 값들을 비교한 관계식이 ±15~20의 오차범위 내에서 도출되었고 평균 기포크기(Sauter mean diameter)는 0.718mm로 확인되었다. 본 시스템으로부터 기포크기 및 분포를 조절할 수 있는 경험식이 가동조건들(J_g: 0.65~1.3cm/s, J_W: 0.13~0.52cm/s, frother concentration: 60~200ppm) 하에서 개발되었다. 기포제농도의 증가는 표면장면과 기포크기를 감소시킨다. 임계병합농도는 표면장력이 가장 낮은 49.24mN/m일 때인 기포제농도 200ppm이라고 판단된다. 공기속도의 감소, 기포제농도 및 세척수속도의 증가에 따라 기포크기가 감소하는 경향을 보였다. 가스홀드업은 가스속도와 비례관계에 있으며 고정된 가스속도 조건에서 기포제농도 및 세척수속도와 비례관계였다.

키워드

기포크기

기포제

가스속도

세척수속도

부선컬럼

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Information

Publisher :The Korean Institute of Resources Recycling
Publisher(Ko) :한국자원리싸이클링학회
Journal Title :Journal of the Korean Institute of Resources Recycling
Journal Title(Ko) :자원리싸이클링
Volume : 29
No :6
Pages :104-113
Received Date : 2020-12-10
Revised Date : 2020-12-18
Accepted Date : 2020-12-23
DOI :https://doi.org/10.7844/kirr.2020.29.6.104

Resources Recycling ISSN:2765-3439(Print) 2765-3447(Online) 자원리싸이클링

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