Q: filtering/purifying sea salt & evaporation techniques

Does anyone know a simple DIY way to filter seawater for a fairly cleaner salt? I can get a little more than a average/tall diner salt shakers worth of salt from a 1.5 liter bottle of seawater here (philippines) but that involves heating in a pan (waste of fuel for a cheap product) and the output often has more dirty tinge than I care to have.

Yes, I know about the issues regarding using seawater and its contaminates for getting salt.

Even the local sea salt I buy for 5 php (10 cents) for a large fistfull... well, it has random contaminates when i dissolve it in hot water. Is there some home plan that works for a good and fast evap sys and also one for cleaning out the crap? I'm not talking random algae strands... but when dried, its off colored.

Hi JPeens,

I will speak of ways I would collect salt where I live (Florida). You should be able to adapt this to work for you.

I would first look at what I am using the salt for. There are many edible plants that grow along inland waterways and beaches that retain salt. Parts of these plants are so salty they can simply be chopped fine and used for seasoning, plus you get the added bonus of the nutrients and flavor they can bring to a dish.

If I needed to collect pure salt, I would collect this from the leaves of plants around inland waterways. Salt is evaporated with water which collects on the leaves of nearby plants. Mangroves where I live are an excellent source for collecting salt that has dried on there leaves.

Hope this helps.

sorry for the delay in replying, thanks for the reply!

been under the weather for a while and just plain lazy to be honest.  I live on a beach - literally on it, not 50 feet from the water however there isn't salt collecting on leaves and other surfaces here, possibly due to the near 100% equatorial humidity of being in the middle of the pacific. But I do know what you're talking about and had completely forgotten about it until you mentioned that - odd how I never noticed that missing before. We only get that on glass surfaces and your skin during high winds (enough to make cresting waves) which is rare.

I was thinking more along the lines of evaporating tray styles, perhaps some unique way of folding aluminum foil that encourages evaporation. I know that salt deposits themselves encourage more water vapor evap but i tried some ideas like scoring and abrading the surfaces of plastic to get capillary action drawing the water up but it doesnt seem to work like i remembered from school.

This is more of a hobby, not a necessity and heck, I know that boiling down a 1.5 Liter bottle of seawater here once gave me a about a small fist sized mound of salt. 

I'm going to try this: make a small oil candle from used olive oil. Set a large coffee can around it (with airspace under the lip) and a spare metal grill on top. Use some empty soda cans with tops removed and cover the the grill with them as much as possible over the main coffee can opening.  fill soda can bottoms with the seawater. Light the low-flame oil candle and let simmer.

I figure its a good way to re-purpose waste olive oil and I can get a lot of the water out of the solution with no supervision and mostly zero expense on fuel.

Like I said, its a hobby thats been stuck in my head for months but I just couldnt get evaporation pans to work.

If this works, I'll take pics and post them.

txpc wrote:
Hi JPeens,

I will speak of ways I would collect salt where I live (Florida). You should be able to adapt this to work for you.

I would first look at what I am using the salt for. There are many edible plants that grow along inland waterways and beaches that retain salt. Parts of these plants are so salty they can simply be chopped fine and used for seasoning, plus you get the added bonus of the nutrients and flavor they can bring to a dish.

If I needed to collect pure salt, I would collect this from the leaves of plants around inland waterways. Salt is evaporated with water which collects on the leaves of nearby plants. Mangroves where I live are an excellent source for collecting salt that has dried on there leaves.

Hope this helps.

Does anyone know how to harvest salt from in land? Im in the northeast US, mostly mountains and rolling hills. I doubt there are salt mines per se, but is there another way?

The old way of doing it (like roman era) was to have shallow, terra cotta trays (easy enough to make in a wood fired earthen kiln if you have a clay and wood source). You would dig a shallow pit trough and lay the terra cotta trays over it and seal with clay leaving a vent hole at one end then, fire with low heat from below. Salt water would be put in all trays and then as the first tray evaporated some, the remaining more dense salt water would be put in the the next tray and so forth. This would cause the salt content in the last tray to eventually be so high that the salt would condense out before the water had been completely evaporated out as soon as the salt water from the tray before it is added. This could be ran continuously near a salt water supply as long as you had enough wood to keep a low heat. You just need enough heat to evaporate the water soaking through the terra cotta not high enough to actually boil the water. This method also condenses the salt out before the water is gone so any particulates can be skimmed off the top of the salt water before it hardens.

Hope that helps

P.S.- using a non porous aluminum tray doesn't encourage evaporation it encourages heat loss. You actually want to raise the temperature not lower it. If all you have is an aluminum tray you need to heavily heat it or give the inside a non-toxic black coating to absorb the heat of the sun although that will take longer. All evaporative techniques using air circulation will actually cool the liquid and slow evaporation unless artificial heat is added somehow.Any small quantity of salt made in a metal container will more than likely take on a nasty, metallic taste.

Rob Sigg wrote:Does anyone know how to harvest salt from in land? Im in the northeast US, mostly mountains and rolling hills. I doubt there are salt mines per se, but is there another way?

Salt being elemental, is not produced by a life form that does not have salt in some form in its food supply. If you have no inland salt deposits or salt water the only source is getting it in some salt compound from a living creature or plant that stores it from its minute trace amounts in its surrounding food supply. You can find a plant that grows in a salty soil and, as mentioned earlier in a post, make a salt like substitute. Animal blood is salty but I wouldn't want to use it. In essence the the land creature is nothing more than a bag of salt water in a thick hide that evoled a way to transport the ocean from whence he came while roaming the dry parts of the Earth.

This all being said, one can see that the furthur man pushed inland, away from the sea and before he learned to mine salt from ancient sea deposits, man greatly valued salt as a trade good to the point of the saying, "there is no life without salt" in ancient texts.

I've made my own sea salt before. I collected 14 gallons of sea water from a relatively clean area and with it produced 9 cups of sea salt - equivalent to 6 cups of table salt.

Here's how I did it. I strained the seawater through gold mesh coffee filter into a large canning kettle. I found a number of tiny wigglies in the gold filter. I heated the kettle on the patio with the burner from a turkey deep fryer. As it boiled down I added more. To make the straining easier I cut a round hole that fit my coffee filter in a 1x6 board. Then I just set the board over the kettle and poured straight through the filter.

Once I had it reduced enough that all 14 gallons had been strained I temporarily turned off the heat and skimmed the top of the water. I found oils and likely some other contaminants floated on top of the salt water. Once I got the gunk off the top I started boiling it again.

Soon I started to see salt crystals precipitating out of the liquid. I scooped these up with a slotted spoon and spread them on a non-stick baking sheet and put them in a 150°F oven to dry. I continued boiling down the water and spooning out the salt until I got it down to an amount that I could finish in a smaller pot on my kitchen stove.

When I poured the contents of the canning kettle into the kitchen pot I saw that a hard scale had formed on the canning kettle. That scale is waste not salt. And it's rather difficult to remove. I had to chip some of it off butter knife.

Finishing the salt on the stove was an amazing and surprising process. The pot would ping and pop and jump around a little! I think what was happening was that the salt was caking up on the bottom of the pan and then bursting from the pressure of steam trapped beneath it. It was very strange. I continued straining off the crystals. Eventually the remaining mixture boiled down into a paste. By this time I had already extracted about 75% of the salt. The remaining paste then went onto a baking sheet and got finished in the oven.

The first crystals scooped out were the biggest an flakiest. I suspect they were also the purest though I have no way of testing or confirming this. At any rate they were more pure white in color than the later crystals and final paste product. It all tasted the same, just like store bought sea salt.

It was a fun and gratifying project.

taking the level down, the first thing that drops out is actually not sea salt, till you get past 50% concentration of water.

http://www.seafriends.org.nz/oceano/seawater.htm#composition


edit

think he talks about it here

http://www.seaagri.com/

What's a gold mesh coffee filter?

is a gold covered screen basket for re-use.

make small ones for tea also

I wonder if you could filter salt out of seawater with carbon? If so, there is a YouTube video showing how you just take charcoal from a campfire, put it in the bottom of a bottle, cut the top off the bottle, and let water run through the charcoal. The guy stuffed some grass in the neck of the bottle first, to keep the charcoal from washing out.
I think the Indians were able to locate salt at the base of sandstone cliffs. If you are good at tracking deer, they will lead you to salt licks. You may get hints about where to find salt from the names of places.
When I was in Jemez National Forest, I found a salt lick used by deer once. There were 3 deer there. It was just a rocky place in the middle of a sandy ridge.

Morgan Morrigan wrote:taking the level down, the first thing that drops out is actually not sea salt, till you get past 50% concentration of water.

http://www.seafriends.org.nz/oceano/seawater.htm#composition


edit

think he talks about it here

http://www.seaagri.com/

This is really good info to know. Worth reiterating. Thanks