@simrin-- Yes, black castor oil will help your hair grow faster. Not only that, but the hair grows thicker and stronger.
Castor oil in general is great for hair. Black castor oil is even better because it has more ash which is richer in nutrients. What I do with black castor oil is I apply it from the roots to the ends and leave it on as long as possible. Sometimes I leave it on for a couple of days like a leave-in conditioner, sometimes all day and sometimes three hours. The longer you leave it in, the more time your hair will have to absorb the nutrients. I usually use it one to three times a week depending on how damaged my hair is.
The hair that grows will be healthier and stronger and so will the strands you have now. I love this stuff.