04/01/2011
PCB-Gold-Recovery.Doc
Note - CASA's notes are added / inserted in BLUE below:
Introduction:
It is considered that CASA has higher than average grade of PCB and connectors that those founf in CLONE PCs - Compaq and other servers and PCs and an array of industrial/commercial telecoms equipments and un-used gold plated connectors are included in our range of recoverable stocks of electronics materials.
Current Stocks:
CASA's current bulked scrapping components (some estimated/equivalents) include:
7 x 1000 litre stillages of PCB - estimated weight 250~350kg = 2000kg (estimated minimum)
1 x 1000 litre stillages of Contactors and Circuit breakers (silver contacts) - estimated weight 450~550kg
1 x 1000 litre stillage (equivalent) of Relays (gold & palladium plated contacts)
1 x 1000 litre stillage (equivalent) of new and used gold-plated connectors
1 x 1000 litre stillages (equivalent) of PCB (yet to be dis-assembled fro systems/servers etc.)
Note - 20 x 1000 lit stillages (2 rows of 5 @ 2 high) will fit in 1 x 20ft container
Sundry resources of background information include:
http://www.ami.ac.uk/courses/topics/0113_prei/index.html

Some prospective refining resources include:
http://www.pmt.net.au/

Possible sources of advise/recommendation:
http://www.melbpc.com.au/
Sourse of basic text (Richard Alcorn):
http://www.finishing.com/188/89.shtml
Hello, I am going to have to agree with some of the things that have been said in this post in reference to the "hobbyist" and chemicals and the inherent danger involved in these processes. That said, it can be economically viable to process SOME electronic scrap utilizing a variety of different methods. In answer to questions relative to the quantities and types of recyclable materials from electronic scrap:
One ton (2000 lbs) of "average" circuit board from modern computers and electronics generally yields (in a very good system) between 8 and 11 troy ounces of 24k gold.
Note - based upon current prices of Gold @ over US$1250/oz these above estimations quantify as follows:
1 Tonne = 1000kg (assorted computer/server/mini/mainframe/telecoms and sundry other complete PCB assemblies with Gold edge connectors and other associated gold plated connectors/contacts/pins/headers etc.) 
10 Troy ounces = US$12,500 (1 Troy oz = 31.10gms is currently listing on World markets @ US1300~1400/oz)
The average potential value for un-processed PCB is:
US$12.50/kg (gross PCB) 
This equates to about US$40/gm for the post-process/refined recovered Gold
Allowing the cost to transport to the refinery this $12.50/kg figure may be discounted by 25%
Interim Conclusion:
A realistic average/value for CASA's PCB & connector stocks is US$12.50 x 0.75(75%) / 0.75(exch) = NZ$12.50/kg
The Bonuses:
Yield from associated metals including Copper, Solver, Tin and Lead etc. may well off-set the transport and refining costs and the yield to CASA may be improved.
This gold is found in a number of places, including the plated gold leads referred to earlier, on plated pins inside the connectors and on the board in a number of places and on and within the ic (integrated circuits) on the board itself. In addition, there will generally be around 10 to 20 times this amount in silver from the solder and other components (although depending upon the method of recovery, this yield may not be reached). Some types of electronic board have greater yields of silver and almost no gold; this is generally the board without connector ends and major ics. There are also minute amounts of palladium, platinum and other pgms (mostly in certain capacitors, but also in some chips and connectors). Your highest yields of gold in computer scrap especially are rarely from clipped plated leads, but from the processor/cpu, memory and other ics (which can yield 2 gm/lb or more, depending upon the type and age). Many of the older electronics and early computer equipment will be much much higher in volume, while the newest (97 and newer) I would surmise would be lower, although I have not processed enough to tell you for sure. There are, of course, many other places (like automotive catalytic converters) where you can find precious metals that may be recycled, but the scope of this section seems to be on electronic board/PCB so I will stay on that subject.
There are several ways to process these materials. Personally, I have used an electrolytic method utilizing cyanide leaching and Aqua Regia methods with success. I am still relatively new to the electrolytic method and have been using some cyanide alternatives recently, but with varying success and without much yield in silver. With Aqua Regia processing, you are able to process out each material by selectively precipitating from solution after absorbing in the acid. AR is a mixture of nitric acid and hydrochloric acid; it may also be manufactured using sodium nitrate (nitrate of soda available as a fertilizer) and Muriatic Acid [link is to product info at Amazon] (used as a concrete cleaner among other things). I first burn the materials, then crush them and dissolve in the acid and then let settle, filter, precipitate and then refine my metals. THIS IS DANGEROUS. DO NOT DO IT UNLESS YOU HAVE SOME KNOWLEDGE OF CHEMISTRY, UNDERSTAND THE DANGERS AND HAVE THE FACILITIES. Certainly, never try this in a confined area or around open flame AND DON'T GET ANY OF IT ON YOU and don't breathe the fumes. Also, you have to be careful about how you get rid of the afterproducts. If you really want to get into that, you can check out some info at shor.com's website and there are other resources as well if you do a search on the net. For most of you, THE DANGERS WILL GREATLY OUTWEIGH THE BENEFIT if you don't have SIGNIFICANT KNOWLEDGE and quite a bit of common sense. A little bit of AR on you (or fumes in your lungs) and you will wish you had never heard of gold (or at least that you had taken your stuff to a refiner). That is, of course, if you have any wishes left. Because I don't believe most of the posters here are fully ready for this process, I have purposely left out the details on how to mix the chems, but I wanted to point out that there are significant quantities of precious content in these items and that it can be economically viable. So, for most of you, you will want to sell your whole populated computer board to a recycler or, if you have large quantities, think about a refinery.
Local Scrapmetal dealers may pay based upon this scale:
486 and older processors should bring at least a US$1~5 each
Pentium and newer scrap processors at least US$0.65 each
Assorted clean plated pins US$15.00 and up per lb (US$33/kg)
Clipped plated connectors at least US$12.00/lb (US$26/kg)
Whole pcb (not clipped or cleaned of pins) should bring at least US$0.60/lb (US$1.32/kg).
These are prices selling to a reputable recycler, who will take bulk to a refiner. You won't get the maximum profit this way, but it is safe and pretty easy. If you go to a refinery, you should get higher returns, but bear in mind that there are additional costs and really check out the refinery you will use. In order to make it worthwhile at a refinery, you should have at least a couple of tons of material (10-15,000 lbs would be best) and you will be expected to provide transportation of the materials to the refinery and, generally, pay between US$0.10 and US$0.50/lb for the refining expenses.
Refining costs allow between US$0.22 and $1.1/kg (US$0.10 ~ 0.50/lb).
The refinery will do an assay or assays of your scrap and will pay you out based on those assays, so your materials should be sorted by the type of material to maximize your profits. Generally, you will be paid for between 90 and 97% of the gold, silver and maybe platinum/palladium depending on the refinery, based on the assay. You have to look for a good refinery, as many are less scrupulous than others. I have found that a refinery usually pays me out based on about 90% of what I would have been able to recover had I done it myself. I figure this is probably due to filter loss and a variety of other factors and not due to their being inherently dishonest, but you should keep these numbers in mind when figuring out what is the best method for you.
Okay, so that is my little bit of info. on this area of interest. Like I said, processing yourself can be dangerous; I hope I haven't made too many of you want to go that route, as it is easier and can be just as profitable to use recyclers and refineries (you have more time and less expense). If you have any questions, excepting exact methodology for processing yourself (as I don't intend to help anyone hurt themselves), I will try to help. 
Richard Alcorn
Research - Roland, Oklahoma