Rust stain on concrete

I have a balcony where I left an old shovel outside too long after the winter. The 'floor' of the balcony is made of concrete. There is now a stain from the rust of the shovel on the concrete. I noticed that even through a relatively rainy spring, the stain is still there. Is there a way to remove this rust stain?
Clint
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1. Mix 1 ounce of tri-sodium phosphate (TSP) in a gallon of hot water. This chemical can be found at hardware and paint stores. Wet the concrete and use a scrub brush to apply the solution. Scrub vigorously and let the solution soak into the concrete for 10 to 15 minutes. Rinse well.
2. Try a product called Iron Out, which is sold in plumbing supply stores.
3. Combat really bad stains with a pressure washer and muriatic acid. Apply the acid as directed by the manufacturer, leave it to soak for a few seconds, and follow with a pressure washer set at 2,500-3,000 psi. Sprinkle baking soda over the cleaned area to neutralize the acid and wash again.
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Clint wrote:

Start with CLR (grocery store item). If that doesn't do it you can use a diluted solution of muratic acid (pool store item). Don't leave the muratic acid on too long (just long enough for the stain to vanish) and wash VERY throughly.
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wrote:

CLR, sold in a gray plastic bottle. Possibly ZUD, a cleanser that contains oxalic acid. Bar Keeper's Friend and Naval Jelly are other products. Use a wire brush and follow the product directions.
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Oxalic acid is also packaged as wood bleach, read the label to be sure of contents.

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Okay thanks very much for the tips guys -- I will try it out and see what happens. I won't leave the shovel out there anymore - better yet, I'll get a shovel that doesn't rust.
Clint
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Hi,
If you can find it, you can mix up a solution of oxalic acid and water and apply it to the stain. Hard scrubbing is required.
For definitive answers to concrete problems, look at this site:
http://www2.worldofconcrete.com/ThisMonth/default.asp?PubID=1
Best of luck,
David

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Packaged as one of the wood bleaches, check the label, also in Barkeepers Friend.
wrote:

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