FireDan has emailed me with some questions and I asked him if I could post them, along with my answers.
Here's one way to calculate the amount of silver you need. You could use copper instead of silver but silver works better. You have 10 grams of 14KT gold. 14KT is about 58% gold. Most karat gold is made up of gold, silver, copper, and a little zinc. Therefore, in 10 grams, you would have 5.8 grams of gold and 4.2 grams of mainly copper and silver. To find out how much total silver and/or copper you need, multiply 5.8 times 3. This is 17.4 grams. You already have 4.2 grams in the alloy. Therefore, you need to add 17.4 - 4.2 = 13.4 grams of silver to your 10 grams of 14KT gold to end up with 25% gold. For 10KT, the gold is 40%. For 18KT, it is 75%.
Although it will certainly work, I hate to see you use your superpure 99.99% silver for this purpose. Scrap sterling silver will work as well.
Getting nitric is always a problem. If you're in a city, try to find a company that repackages technical grade chemicals in smaller quantities. Don't buy high purity reagent grade, as it will cost you about 10 times more. Look under chemicals or lab supplies in the yellow pages and call around. You shouldn't have to pay much more than $12 per gallon, in one gallon jugs. You should try to find a place close enough where you could pick it up. It's Hazmat and the shipping could run twice, or more, what you're paying for the acid.
If you can't buy nitric, you'll have to make it. (However, it's a hassle and, if you can find technical grade nitric, in gallon quantities, for sale, I would suggest buying it. A gallon of tech grade nitric will dissolve about 100 ozs. of silver or 30 ozs. of copper). You basically start with battery acid and sodium nitrate. Battery acid, although weak, is about the purest form of sulfuric available from common sources. You first have to increase the strength of the battery acid. Catfish wrote an excellent tutorial on this. This can be dangerous because it can get very hot, so study the safety parts carefully.
http://goldrefiningforum.com/phpBB3/viewtopic.php?t=342&highlight=
Also, read this thread. Especially catfish's and lazersteve's posts. On the 2nd page, Steve wrote up a recipe. Catfish has made several batches using this recipe, with very good success. There's a lot of info on other threads but, you'll have to search them out.
http://goldrefiningforum.com/phpBB3/viewtopic.php?t=315&highlight=
When dissolving silver, always use distilled water to dilute the nitric.I usually cover the metal with water, heat it up, and start feeding in the straight nitric, in increments. If you add too much nitric at one time, it could foam over.
When diluting the aqua regia 3 volumes, tap water is fine.
A fume hood is best but I've done my share of refining out in the sticks. Sometimes, you'll have days of an inverse temperature gradient. This is when the ground is colder than the air. On these days, it's a little harder to get out of the fumes because they tend to cling close to the ground. But still, working outside is fine as far as safety is concerned. The fumes produced from nitric or aqua regia are reddish brown and are quite visible. With small quantities, this is no problem. With very large quantities, someone may see it and turn you in. A little wind is good because it disperses the fumes quickly. The only problem with wind is that it sometimes changes direction and this makes it harder to stay upwind. I'm big on proverbs and, "Look before you leap", is one of the biggest when doing refining.
I would use a welder's type full face shield instead of glasses. The clear plastic type with an adjustable head band - about $7. They're easier to see out of and are more comfortable and safer. When you don't need it, you just flip it up. No matter how careful you are, you're going to get a drop of acid flying in the air. This usually happens when you're pouring the fresh acid. These drops always seemed to land on my nose and I usually had a scab or two there. A face shield is much more protective.
A liter of 70% nitric, the standard strength of industrial grade nitric, contains 15.4 Moles of HNO3. The other 30% is water. Rarely is this information needed for refining. In practice, I consider the 70% product as being 100% and go from there. If I want 50/50, I just double the volume with water.
One of the most important things I've learned is to always put the container you're working with inside of a larger container. Everyone has spills, dribbles, glass breakage, and foamovers. This tip will save you a lot of grief. If the solution needs to be heated in a beaker, the outer container needs to be heatproof. The best is a 5 quart, white, flat-bottomed, Corning Ware dish. New, they cost about $25 but, you can usually find them in resale shops or flea markets. These things are incredibly strong. If you're working in a bucket, without heat, use a plastic tray as the outer container. A 7 gallon tray from WalMart runs about $7.
Here's one way to calculate the amount of silver you need. You could use copper instead of silver but silver works better. You have 10 grams of 14KT gold. 14KT is about 58% gold. Most karat gold is made up of gold, silver, copper, and a little zinc. Therefore, in 10 grams, you would have 5.8 grams of gold and 4.2 grams of mainly copper and silver. To find out how much total silver and/or copper you need, multiply 5.8 times 3. This is 17.4 grams. You already have 4.2 grams in the alloy. Therefore, you need to add 17.4 - 4.2 = 13.4 grams of silver to your 10 grams of 14KT gold to end up with 25% gold. For 10KT, the gold is 40%. For 18KT, it is 75%.
Although it will certainly work, I hate to see you use your superpure 99.99% silver for this purpose. Scrap sterling silver will work as well.
Getting nitric is always a problem. If you're in a city, try to find a company that repackages technical grade chemicals in smaller quantities. Don't buy high purity reagent grade, as it will cost you about 10 times more. Look under chemicals or lab supplies in the yellow pages and call around. You shouldn't have to pay much more than $12 per gallon, in one gallon jugs. You should try to find a place close enough where you could pick it up. It's Hazmat and the shipping could run twice, or more, what you're paying for the acid.
If you can't buy nitric, you'll have to make it. (However, it's a hassle and, if you can find technical grade nitric, in gallon quantities, for sale, I would suggest buying it. A gallon of tech grade nitric will dissolve about 100 ozs. of silver or 30 ozs. of copper). You basically start with battery acid and sodium nitrate. Battery acid, although weak, is about the purest form of sulfuric available from common sources. You first have to increase the strength of the battery acid. Catfish wrote an excellent tutorial on this. This can be dangerous because it can get very hot, so study the safety parts carefully.
http://goldrefiningforum.com/phpBB3/viewtopic.php?t=342&highlight=
Also, read this thread. Especially catfish's and lazersteve's posts. On the 2nd page, Steve wrote up a recipe. Catfish has made several batches using this recipe, with very good success. There's a lot of info on other threads but, you'll have to search them out.
http://goldrefiningforum.com/phpBB3/viewtopic.php?t=315&highlight=
When dissolving silver, always use distilled water to dilute the nitric.I usually cover the metal with water, heat it up, and start feeding in the straight nitric, in increments. If you add too much nitric at one time, it could foam over.
When diluting the aqua regia 3 volumes, tap water is fine.
A fume hood is best but I've done my share of refining out in the sticks. Sometimes, you'll have days of an inverse temperature gradient. This is when the ground is colder than the air. On these days, it's a little harder to get out of the fumes because they tend to cling close to the ground. But still, working outside is fine as far as safety is concerned. The fumes produced from nitric or aqua regia are reddish brown and are quite visible. With small quantities, this is no problem. With very large quantities, someone may see it and turn you in. A little wind is good because it disperses the fumes quickly. The only problem with wind is that it sometimes changes direction and this makes it harder to stay upwind. I'm big on proverbs and, "Look before you leap", is one of the biggest when doing refining.
I would use a welder's type full face shield instead of glasses. The clear plastic type with an adjustable head band - about $7. They're easier to see out of and are more comfortable and safer. When you don't need it, you just flip it up. No matter how careful you are, you're going to get a drop of acid flying in the air. This usually happens when you're pouring the fresh acid. These drops always seemed to land on my nose and I usually had a scab or two there. A face shield is much more protective.
A liter of 70% nitric, the standard strength of industrial grade nitric, contains 15.4 Moles of HNO3. The other 30% is water. Rarely is this information needed for refining. In practice, I consider the 70% product as being 100% and go from there. If I want 50/50, I just double the volume with water.
One of the most important things I've learned is to always put the container you're working with inside of a larger container. Everyone has spills, dribbles, glass breakage, and foamovers. This tip will save you a lot of grief. If the solution needs to be heated in a beaker, the outer container needs to be heatproof. The best is a 5 quart, white, flat-bottomed, Corning Ware dish. New, they cost about $25 but, you can usually find them in resale shops or flea markets. These things are incredibly strong. If you're working in a bucket, without heat, use a plastic tray as the outer container. A 7 gallon tray from WalMart runs about $7.
