'Threshing floors' in the Bible

Then they told David, saying, Behold, the Philistines fight against Keilah, and they rob the threshing-floors.

Then was the iron, the clay, the brass, the silver, and the gold, broken to pieces together, and became like the chaff of the summer threshing-floors; and the wind carried them away, that no place was found for them: and the stone that smote the image became a great mountain, and filled the whole earth.