Investigation of bubble velocity profile in the column flotation cell by computational fluid dynamics simulation

Document Type : Research Article

Authors

1 Shahrood University of Technology

2 Dept. of Mining Engineering, Petroleum and Geophysics, Shahroud University of Technology, Iran

3 Kashan Azad Unicersity

Abstract

Summary
Hydrodynamic components play an important role in the process performance of column flotation. CFD as a numerical method can help analyze and predict flow components. In this paper, the single-bubble rising velocity profile in the flotation column is studied in two-phase with CFD. Simulations have been performed in Fluent software using a two-phase VOF model. A computational column with a square cross-section of 10 cm and a height of 100 cm has been considered. The air is taken in by a single bubble from the bottom of the column by an internal sparger. To validate the simulation results, a series of experiments were performed exactly according to the mentioned conditions, while imaging was used to record hydrodynamic components such as inlet airflow, bubble diameter, and bubble rise velocity, etc. The experimental results are consistent with previous observations that studies by others. Also, the results of the simulations performed are qualitatively and quantitatively consistent with the experimental results. The results show that CFD simulation can well predict the rise of the bubble and its related parameters in the flotation column, including the bubble rise rate with a difference of less than 5% compared to the experimental values. In this paper, the single-bubble rising velocity profile in the flotation column is studied in two-phase with CFD.
 
Introduction
This article consisted of two parts: the experimental tests and the CFD simulations. The authors tried to present a set of setting to simulate the bubble rising velocity as well as possible by their facilities.
 
Methodology and Approaches
Simulations have been performed in Fluent software using a two-phase VOF model. A computational column with a square cross-section of 10 cm and a height of 100 cm has been considered. The air is taken in by a single bubble from the bottom of the column by an internal sparger. To validate the simulation results, a series of experiments were performed exactly according to the mentioned conditions, while imaging was used to record hydrodynamic components.
 
Results and Conclusions
The results showed that CFD simulation can well predict the rise of the bubble and its related parameters in the flotation column, including the bubble rise rate with a difference of less than 5% compared to the experimental values.

Keywords

Main Subjects

Full Text

با کاهش عیار مواد معدنی در عصر حاضر، استفاده​ی حداکثری از منابع و معادن طبیعی اهمیت زیادی پیداکرده و این مهم باعث شده که معدنکاری و صنایع وابسته به آن جایگاه ویژه​ای را در اقتصاد به خود اختصاص دهد؛ به همین دلیل افزایش کارایی عملیات فرآوری و بهینه​سازی سیستم‌های مرتبط با آن از اهمیت ویژه​ای برخوردار است. شناخت مکانیسم و نحوه​ی انجام فرآیندهای فیزیکی در ارتقاء عملکرد یک سیستم مؤثر است. علم سیالات و به‌طور خاص "دینامیک سیالات محاسباتی" ازجمله ابزارهایی است که در این راستا می‌تواند به کار گرفته شود. تاکنون نمونه​هایی از شبیه​سازی CFD بر روی تجهیزات فرآوری با رویکردها و اهداف مختلف انجام‌شده است [1]. در جدول 1 عناوین و خلاصه​ای از مطالعات و بررسی​های انجام‌شده با این روش روی ناحیه​ی جمع​آوری ستون فلوتاسیون آمده است.

در اغلب پژوهش​های انجام‌شده تلاش شده تا کلیت عملیات فلوتاسیون بررسی شود؛ حال‌آنکه با توجه به نقش ویژه​ی حباب​ها در شناورسازی ذرات و حمل آن​ها به فاز کف و به‌منظور درک بهتر تأثیر مؤلفه‌های هیدرودینامیکی لازم است بررسی​های بیشتری بر روی آن​ها انجام شود. از طرفی برای دستیابی به نتیجه​ی مناسب در شبیه​سازی، ابتدا فهم کامل فیزیک حاکم بر پدیده و سپس انتخاب مدل ​فیزیکی مناسب (مدل چند فازی، مدل آشفتگی و...) جهت اعمال در ابزار شبیه​سازی (به‌عنوان‌مثال نرم​افزار فلوئنت) لازم است. این پژوهش با توجه به اهمیت انکارناپذیر ارتقاء کارایی بخش فلوتاسیون به‌عنوان کارآمدترین واحد کانه‌آرایی و باهدف هم‌افزایی علوم مرتبط با فلوتاسیون در دو بخش تجربی و شبیه​سازی تعریف و انجام‌شده است. به‌منظور ساده​سازی مسئله در گام اول به شبیه​سازی تک حباب پرداخته‌شده تا بعد از اعتبارسنجی نتیجه و اطمینان از صحت مدل​های فیزیکی اعمال‌شده و روش حلی که به کار گرفته‌شده است، بتوان با اطمینان خاطر بیشتری شبیه​سازی​ها را به شرایط آزمایش​های تجربی و فلوتاسیون واقعی نزدیک کرد. در ادامه ابتدا آزمایش‌های تجربی و جزییات و نحوه انجام آن و سپس روش بکار گرفته‌شده در شبیه​سازی و مراحل انجام آن توضیح داده‌شده است. درنهایت نتایج تجربی و شبیه​سازی ارائه‌شده و با مقایسه​ی این دو، جمع​بندی نهایی انجام‌گرفته است.

 

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Journal of Analytical and Numerical Methods in Mining Engineering
Volume 11, Issue 27
July 2021
Pages 43-54

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History

  • Receive Date: 17 August 2020
  • Revise Date: 27 November 2020
  • Accept Date: 02 January 2021

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