For that reason, we don't put raw eggshells into the compost, because the chickens are our compost turners. Instead, we save up the shells until we have a big bowlful, then we bake them in the oven for 30 minutes, and finally crush them into bits and either then put them into the compost or feed them back to the chickens. (This may sound a little cannibalistic to those of you new to chickens, but it's a good way to keep calcium in the chickens' diet.)
Yesterday was eggshell baking day. And here is the song of the eggshells, right from the oven.