Dale Hodgins wrote:I think starting with liquid slows the whole process down because of the limited surface area. And the way it's set up, the humidity is always very high, which limits evaporation speed. Consider this. Start with a bunch of granular salt, either stuff you've made or stuff you bought. Let's say we start with 20 lb. Lay it out roughly in the bottom of your evaporation container with lots of humps and bumps. You want most of it to rise above the surface of water that you're adding. Now instead of trying to reach a high temperature, use a flat plate collector and send lots of warm air over the granular material. The air will pick up lots of moisture and the granular material will continue to wick water from beneath until it's all gone. Top up regularly. If your pile of salt eventually settles into a relatively smooth shape, break it up to maintain the high surface area. You might want to filter incoming air so it doesn't give you a mixture of salt, dust and bugs.
You wouldn't have to start with salt. You could start with a pile of really nice clean black basalt pebbles. They would get covered in salt crystals soon enough and you would have the rough surface without having to start with any salt.