I heard You can clean using coke. http://youtu.be/z7OdX42NjWQ

Edited/Updated : 
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1.Have a new bottled coke - which has carbonated gas. <br />
2.Pour coke on the rusted surface. <br />
3.Give it a few minutes, and then take a piece of sponge or a coarse cloth and rub off the rusted surfae.<br />
4. <b>NOTE : </b>Only coke which has the carbonated gas works. If it does not have the gas, it does not work. <br />
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@michaelpri, @subjectivist - <b>Thank you</b> and I will remember to write better answers from the next time.