rajkumarkp
Member
i desolve the 500grms of silver in nitric acid,then add 1kg salt to recover the silver,it comes like cement type,then i melt the powder,and its not melt,it came look like water, wat can i do now?
how to disolve the salt in silver
- Thread starter rajkumarkp
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Dissolve salt in water. 500g silver is like 5moles Ag. You need then 58,5*5= like 300g of salt. So about 1liter of water is needed to make the solution. There are many ways to reduce silver chloride to metalic silver. Look at the forum for silver chloride reduction. I personally just add hydroxide to get silver oxide and melt it to metal, it decomposes above 200 centigrade. But this is not common method as I noticed.
rajkumarkp,
It probably made no difference, but that's a lot of salt. Theoretically, for 500 grams of silver, it would take about 271 grams. Practically, it will take a bit more, since the salt probably contains moisture and may not be pure.
Was the silver pure to start with or was it part of an alloy. If an alloy, what was the alloy? If it was pure to start with, why did you dissolve it?
What is your plan? Do you want to end up with pure silver (999 or better) or is 98-99% silver adequate.
When you say "melt", I assume that you mean melting with heat. Some people wrongly use the term to mean "dissolve" in chemicals. If you actually "melted" the silver chloride, that was a huge mistake. The silver chloride melts at a fairly low temperature - 455 C. If you got it much hotter, you could evaporate it, where it comes off as a white smoke and is quite dangerous to breathe. Also, when it melts, it becomes very fluid and, when cooled, it forms a solid waxy substance which is extremely difficult to convert to silver metal. You will be very lucky to recover it all at this point.
Here's what you should have done. With two exceptions that I know of (see below - Kunda and ander), you must convert the silver chloride to silver metal before melting it. After filtering and rinsing the silver chloride very well, you have several ways of converting it to metal, all of which have been covered in detail on this forum - study these before you leap ahead. You can use a metal, such as iron or zinc plus an acid, such as sulfuric, or you can use corn sugar or corn syrup (or other types of sugar) plus sodium hydroxide.
You can convert the silver chloride powder to metal in a furnace with the addition of sodium carbonate. You will have problems if you overheat this - you could get a lot of fumes and the conversion will probably be incomplete. An excellent method for doing this at a controlled low temperature is contained in the patents of Kunda.
http://www.google.com/patents/about?id=qxQwAAAAEBAJ&dq=4306902
http://www.google.com/patents/about?id=Mj06AAAAEBAJ&dq=4388109
If the silver was impure to start with, it will be difficult to get 999 silver from any method using silver chloride, since it's hard to eliminate all the base metal impurities by rinsing. Also, if you use zinc or iron for conversion, you will likely introduce some contamination.
The method that ander just mentioned in the previous post - converting the silver chloride to silver oxide with sodium hydroxide and then decomposing it at a low temperature - works quite well, also.
No matter what silver chloride method you choose, there is always the problem of not getting 100% conversion to silver metal. When you finally melt the silver, unconverted silver chloride will form in a layer between the silver metal and the slag, after cooling. It is usually quite visible.
The simplest way to do all this was to not produce silver chloride to start with. Assuming you used a minimum amount of nitric acid to dissolve the silver, you could have simply cemented the silver, as metal, onto copper bars. If you used too much nitric, no cementation will occur until the excess is used up by the dissolving of copper. With proper rinsing, you could end up with about 98-99% silver, depending on the type of copper you used. This method has been covered many times on the forum. I've written it up about 10 times.
If you use the above methods, you will probably not be able to reach a purity of 999 Fine, or better. The standard method of purifying this silver, to at least 999 Fine is to use an electrolytic silver cell.
4metals outlined a method of getting pure silver directly, from a nitric solution containing base metal contamination, using sodium formate. He claims a purity of 999.9 Fine, or very close to it.
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=1275&p=39590&hilit=sodium+formate#p39590
Chris Owen
It probably made no difference, but that's a lot of salt. Theoretically, for 500 grams of silver, it would take about 271 grams. Practically, it will take a bit more, since the salt probably contains moisture and may not be pure.
Was the silver pure to start with or was it part of an alloy. If an alloy, what was the alloy? If it was pure to start with, why did you dissolve it?
What is your plan? Do you want to end up with pure silver (999 or better) or is 98-99% silver adequate.
When you say "melt", I assume that you mean melting with heat. Some people wrongly use the term to mean "dissolve" in chemicals. If you actually "melted" the silver chloride, that was a huge mistake. The silver chloride melts at a fairly low temperature - 455 C. If you got it much hotter, you could evaporate it, where it comes off as a white smoke and is quite dangerous to breathe. Also, when it melts, it becomes very fluid and, when cooled, it forms a solid waxy substance which is extremely difficult to convert to silver metal. You will be very lucky to recover it all at this point.
Here's what you should have done. With two exceptions that I know of (see below - Kunda and ander), you must convert the silver chloride to silver metal before melting it. After filtering and rinsing the silver chloride very well, you have several ways of converting it to metal, all of which have been covered in detail on this forum - study these before you leap ahead. You can use a metal, such as iron or zinc plus an acid, such as sulfuric, or you can use corn sugar or corn syrup (or other types of sugar) plus sodium hydroxide.
You can convert the silver chloride powder to metal in a furnace with the addition of sodium carbonate. You will have problems if you overheat this - you could get a lot of fumes and the conversion will probably be incomplete. An excellent method for doing this at a controlled low temperature is contained in the patents of Kunda.
http://www.google.com/patents/about?id=qxQwAAAAEBAJ&dq=4306902
http://www.google.com/patents/about?id=Mj06AAAAEBAJ&dq=4388109
If the silver was impure to start with, it will be difficult to get 999 silver from any method using silver chloride, since it's hard to eliminate all the base metal impurities by rinsing. Also, if you use zinc or iron for conversion, you will likely introduce some contamination.
The method that ander just mentioned in the previous post - converting the silver chloride to silver oxide with sodium hydroxide and then decomposing it at a low temperature - works quite well, also.
No matter what silver chloride method you choose, there is always the problem of not getting 100% conversion to silver metal. When you finally melt the silver, unconverted silver chloride will form in a layer between the silver metal and the slag, after cooling. It is usually quite visible.
The simplest way to do all this was to not produce silver chloride to start with. Assuming you used a minimum amount of nitric acid to dissolve the silver, you could have simply cemented the silver, as metal, onto copper bars. If you used too much nitric, no cementation will occur until the excess is used up by the dissolving of copper. With proper rinsing, you could end up with about 98-99% silver, depending on the type of copper you used. This method has been covered many times on the forum. I've written it up about 10 times.
If you use the above methods, you will probably not be able to reach a purity of 999 Fine, or better. The standard method of purifying this silver, to at least 999 Fine is to use an electrolytic silver cell.
4metals outlined a method of getting pure silver directly, from a nitric solution containing base metal contamination, using sodium formate. He claims a purity of 999.9 Fine, or very close to it.
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=1275&p=39590&hilit=sodium+formate#p39590
Chris Owen
