Extraction of gold from seawater

A. I have known of gold being got out off sea water but the cost outweighs the return , I do not know how it was done.

A. Hi, Louis. I can't tell if your question is student homework, a concern about an investment scheme/scam that has been presented to you, or a serious engineering question. But if it was intended as a serious question, the issue is that practically extracting the gold from seawater hasn't been achieved, whereas everyone has known for decades that it's theoretically possible. The problem the incredibly low concentration of gold in seawater :-)

Could you please tell us your real world situation? Hopefully you'll get a better response than I have given you so far. Thanks!

! This is the real world! Louis' question is a serious one. Ted, admit it. You don't know! Dwight [last name deleted for privacy by Editor] - Renton, Washington 2004 I thought I had admitted it Dwight. Exactly what phrasing do you want me to use to "admit" that I don't know how to practically get gold from seawater? :-) Why do you feel that Louis is an engineer trying to design a practical recovery system as opposed to, say, a potential victim investigating the reasonableness of an investment scam presented to him? Thanks. Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey

A. Unfortunately, economy of scale works in the opposite direction, Paul. The smaller the operation, the more impractical. It's been estimated that there is a milligram of gold in a ton of seawater. That means you would have to process (at 100 percent efficiency) two million pounds of seawater to get one gram of gold -- 57 million pounds to get an ounce.

Some day there may be a technology to do it practically (maybe some kind of special magnetic force or laser force or some kind of genetically engineered gold-eating microbe to concentrate it) but the numbers seem daunting for the present.

A. "Gold From the Sea", a web page at http://www.goldfever.com/gold_sea.htm addresses the issue and includes a bibliography with 27 references. Good luck with it, Anna!

My wild guess based on hints in the literature is that a microbe or nanomachine will be engineered which can bioaccumulate gold. If such a creature could concentrate gold even to 1 ppm, that would make the concept a hundred times more practical; if it could concentrate gold to 100 ppm it would be 10,000 times more concentrated than seawater. We live at the cusps of genetic and micromachine revolution, so I think it will happen.

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Ed. note May 2019: Sorry, the web page I mentioned no longer exists.

A. Allowing drops of sea water to float up through Mercury will result in the Gold entering the Mercury. However, some Mercury will dissolve into the sea water, so much so that you spend more money on Mercury than you make from the Gold. Also the process pollutes the ocean with Mercury.

A. Hi, Anna,

Many lab technicians and nurses who wear gold rings have learned to their sorrow that when mercury touches gold it forms an amalgam. Bart was suggesting that you could take a small hose & pump, and pump the water with gold in it to the bottom of a bowl of mercury. As the water floated upwards (water is lighter than mercury), the gold would contact the mercury and form an amalgam. I suspect that you would have to recirculate this water several times for all of the gold to contact mercury.

The gold and mercury can be separated by heating the amalgam but, in leaving the gold behind, this releases toxic mercury gas, so this information is for your general understanding not for actual practice.

Nanoparticles are particles of 1 to 100nm in diameter. Sorry, I don't know if the gold in the ocean might sometimes be in the form of nanoparticles, but I don't think it's important because you don't get the properties of nanoparticles until you somehow classify out the non nanometer sized particles. Once captured in the amalgam, the gold would not be particles at all.

Regards,

A. Hi, Mike. It makes no economic sense to me (with today's technology), as I've said a couple of times. If gold is worth about $400 per ounce then $.75 worth would be $.75/$400 = .001875 oz. of gold. Then if there was .001875 oz. of gold in a gallon (which is 128 oz.), the concentration would have to be .001875/128 = 14.7 ppm. This water would be considered toxic by the EPA on the basis of its gold concentration alone!

If this ground water was at the bottom of a gold mine, I guess it could have that much gold in it (maybe--I really don't know), but why would not the mining companies be extracting it?

A. My Dear Gold seeking friends,

I stumbled over this discussion and want to add a few things. If I am not mistaken the original idea of the discussion was to filter gold out of seawater to sustain a small family.
Even though, there might be a huge amount of gold in seawater, there are more efficient ways of getting your hands on gold (without paying for it in the jewelry shop or the bank). For example, people still make a living of panning for gold which you can find in many areas of the world, the only requirements for that would be a pan, patience, a sense of adventure and knowledge about the area you live in.
But even if you aren't living in an area where gold occurs, looking for minerals might be more profitable than filtering a couple thousand pounds of water for an ounce of gold. For example, a good sized sample of amethyst, a big agate or anything like it is very valuable for collectors (who pay good money up to a few thousand dollars for good specimens).
As conclusion, I would suggest to look for a way to filter gold from seawater as a hobby in your free time where you might get some dollar.

A. Magnetic Activated Carbon Particles for Gold Recovery

Is used to remove heavy metals and toxins from air and water.

"Activated carbon finds use in the extractive metallurgy of gold. In 1999, the amount of activated carbon purchased for gold recovery in the US and the rest of the world was estimated to be 4000 and 7000 metric tons... Activated carbon has been recommended by the EPA as one of the best available technologies for water and wastewater treatment. Activated carbon is also used in the food, automotive, chemicals, and pharmaceutical industries ... This technology has been demonstrated to work in proof-of-concept experiments."
http://www.business.utah.edu/display.php?&pageId=1936

"For example, in a laboratory-scale test, conventional activated carbon with a particle size of 6x12 mesh (3.35 mm x 1.40 mm) adsorbed 60% of the gold in cyanide solution after 8 hours of contact time. A magnetic activated carbon with a particle size of minus 200 mesh (74 mm), under the same experimental conditions, adsorbed more than 96% of the gold in about 15 minutes and 99% of the gold in less than 2 hours."
http://www.umpic.utah.edu/opps2.html

"Gold is recovered from the gold-bearing solution in the carbon process in which pellets of activated carbon, made from charred coconut husks, are added to the slurry and the gold-bearing ions are adsorbed onto the pellet surface. The pellet load is moved through a number of linked tanks containing slurry in a direction opposite to the slurry movement.
Pellets, loaded with gold, are removed and gold is stripped from them by washing in a solution of hot cyanide. Carbon used in the process is recycled. An electric current is passed through the new solution and the gold is deposited on a steel wool cathode."
http://www.australianminesatlas.gov.au/info/factsheets/gold.jsp

The research is just beginning and recovering gold from water may be possible in the future.

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Ed. note May 2019: The three web pages Derek referenced no longer exist.

 Thanks, Derek -- although I am not quite seeing the connection yet.

As you say, activated carbon has been used in many industries almost forever. In the electroplating industry we have linked it to ion exchange media to help it serve as a wastewater effluent polishing material, and we've linked it to various stabilizing materials like cellulose filter aid to try to limit the dustiness of conventional activated carbon. The efficiency improvement that the licensing office at utah.edu claim sounds interesting, and being able to gather it with magnetism sounds like another nice plus, but I am not understanding in your links how it makes recovery of gold from seawater any closer. Maybe you can comment on the specific relationship between this development and recovering gold from seawater? Thanks again!

A. Here is a thought based on one of the last comments: De-desalinization plants are being built like CRAZY and from what I understand the process is practically much the same as RO units? So the water is simply filtered to the extreme and those filtered elements have to be disposed which unfortunately I am just guessing they dump all BACK into the sea that is already becoming too high in saline. I am thinking that since all that GOLD surely is IN that which is disposed of and now at a much increased concentration 'per pound' as they say it ought to more practical than ever before to extract gold from THAT ... and at the same time it could become a requirement to NOT dump the salt back into the sea! Could possibly be a win win win situation? The people get their water, the ocean has all these little salt removing operations going 24/7 that just might make an appreciable difference at some point AND some enterprising Alchemist get either rich in the process or have a lot of fun trying!

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 Personally, I think the extracted salt should go back into the sea, not onto land. While many bays, estuaries, and brackish areas are becoming too salty due to reduced fresh water inflow, I haven't heard that the ocean itself is getting too salty -- but certainly the land is.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. I think it is a promising prospect

A. It seems to me that the cost of separation of gold from seawater will determine the ultimate maximum price of gold. Considering the increase in price of copper and silver: a separation of those elements from seawater may well make the process of separation more practical for gold as a separation byproduct. Copper is about 100,000 times more concentrated in seawater than gold. The value of gold today is about 2000 times the value of copper. So, one dollar of gold would be separated for each $50 of copper. Perhaps this conversation should be more about the separation of copper from seawater.

dumbill

 That sounds true, Bill, only if the selected recovery technology recovers copper, silver, and nickel concurrently. But we are saying that it may become practical with some future technology, and we don't know whether that technology recovers the 3 metals together or only the gold. I mentioned a microbe that might accumulate gold, but we don't know whether it will bioaccumulate copper and silver; maybe not, since these can tend to be biocides. But your posting is certainly great food for thought. Thanks!

A. In theory it is possible to electro plate the metals out of the slurries then smelt out the gold (or if you're smart the copper chrome and other metals).

A. After giving this some thought.
You use eddy current, powered by a water mill mounted on the ocean floor to force gold in seawater into a nonporous receptacle .The concentration of gold increase with time, then all one would need is a constant flow of sea water like the Gulf Stream or tow the whole rig behind a ship.

A. This thread is old and may be dead, but it seems to me you have a better chance of extracting gold from blood of cadavers than sea water.

I am no scientist, but actually an economist and CPA. It seems to me that if a practical way to extract gold from seawater is developed, the price of gold would instantly plummet due to the huge amounts of newly recoverable gold available. Therefore, the expense to research and develop the method would instantly render the goal worthless.

 Hi, Steven and thanks. But, I don't agree with your conclusion. While making gold easier to obtain would reduce its cost, and would thus devalue jewelry, it would not render the goal worthless. Although gold is used in jewelry, it's also used in electronics and for its excellent corrosion protection, etc., and designers would love to apply it almost everywhere but are terribly limited by its cost. Yes, we reduced the value of the aluminum cap on the Washington Monument when we figured out how to make aluminum cheaply, but we didn't render aluminum worthless. Thanks for a thought-provoking discussion.

Regards,

A. I am a doctor at a University and I am attempting another doctorate in order to get my professorship in chemistry.
I have found a way of isolating gold from sea water using a biodegradable ion and a electronic synthesizer that will solidify and attach itself to any metal in the sea water and convert it into a rough ore (if left for a certain amount of time).

This ore can be separated by the elements using their different boiling points; the final products are silver and any other metal that is common in sea water.
The good news that I have made the process 10 pence cheaper than the total price of the yield, I will be publishing the paper in 3 months time as there is still problems with the variables of pure sea water and its corrosive properties.

A. Getting gold from sea water is simple and can be extracted at much lower cost than conventional cost. Its technology of extraction is carrier transported immobilized liquid membrane.

A. "Geothermal brines are passed through a bed of an anionic resin selective to the removal ... 4778597, Process for the separation and recovery of boron compounds from a geothermal brine .... Gold No 0.2. Silver 2.6 0.5. Zinc 1500 500. Lead 650 110 .... The boron-enriched solution can be heated to evaporate water and ..."

www.freepatentsonline.com/5236491.html