IJE TRANSACTIONS B: Applications Vol. 30, No. 8 (August 2017) 1215-1222   

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M. Akhondizadeh, M. Khosravi and V. Khalili
( Received: April 12, 2017 – Accepted in Revised Form: July 07, 2017 )

Abstract    A number of considerations should be taken into account in design stage to avoid the foregoing malfunctions of vertical silos containing ore concentrate. One of the silo problems is obstruction at the outlet which blocks the material flow. There are procedures, depending on the material properties and silo dimensions, to solve this problem. A common way is impacting the silo wall by manual hammering or pneumatic impacting. In the present work, the hopper of a laboratory silo containing the magnetite concentrate, for obstruction solution is impacted by single ball. Impacts lead to the bulk fracture and material discharge. Capturing the new arc profile after discharge and registering the required number of impacts which provide the continuous material flow helps us to determine the optimum impacts. Results show that the wall displacement due to the impact is a governing factor in obstruction solution and the best impact position is near the outlet. It is also concluded that at a constant kinetic energy the impacts by higher mass balls are more effective than the impacts by higher velocity balls.


Keywords    Silo, Obstruction, Impact, Magnetite powder


چکیده    برای پیشگیری از کارکردهای نامناسب سیلوهای حاوی کنسانتره معدنی باید ملاحظاتی در مرحله طراحی در نظر گرفته شود. یکی از مشکلات عملکردی این سیلوها انسداد دهانه است که جریان مواد را متقف می کند. با توجه به خواص مواد و ابعاد سیلو راهکارهایی برای رفع این مشکل بکار گرفته می­شود. یک راه رایج، ضربه زدن به بدنه سیلو با چکش دستی و یا پنوماتیکی است. در کار حاضر بدنه یک سیلوی آزمایشگاهی حاوی کنسانتره مگنتیت، جهت رفع انسداد، مورد اصابت گلوله قرار می­گیرد. ضربات موجب شکست توده مواد و تخلیه آنها می­شود. ثبت پروفیل انسداد بعد از هر برخورد و تعیین تعداد برخورد لازم جهت برقراری جریان پیوسته مواد، بعنوان معیارهایی در تعیین شرایط بهینه ضربه جهت رفع انسداد مورد استفاده قرار می­گیرد. نتایج نشان می­دهد که جابجایی بدنه در اثر ضربه فاکتور مهمی در تاثیرگذاری ضربات بر رفع انسداد بوده و ضربات نزدیک دهانه خروجی مناسب تر از دیگر محل های برخورد است. همچنین مشخص شد در انرژی جنبشی ثابت، گلوله­های با جرم بیشتر بهینه­تر از گلوله­های با سرعت بالاتر در رفع انسداد عمل می­کنند.


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