Inquartation will require silver twice the amount of gold content to make it susceptible to reaction with Nitric acid.
Proper inquartation would require three times the nitric soluble metals to one part of gold. The Silver is the preferred method because it will use over 3 times less nitric acid to accomplish the same thing.
10% Silver can be dealt with with aqua regia refining but with tumbling not mixing. The tumbling action mechanically removes any Silver Chloride encrustation but simple stirring, no matter how powerful the mixing, is not as effective. While tumbling does allow aqua regia to be more effective with Silver concentrations approaching 10% it still leaves the issue of dealing with the silver chlorides which can hold as much as 1% of your gold with the chlorides. And the reducing of Silver Chloride to Silver metal is a more time consuming task than cementation on copper. And you have yet to address any platinum group metals that will dissolve in the acid and need recovery.
I have gold and silver jewellery business. For me refining is a side hustle.
Aside from the fact that I never considered refining a hustle, the OP is gainfully employed as a jeweler. And a silver jeweler as well. This makes attaining any Silver easier because he likely deals in sterling scrap as well. But inquarting will greatly simplify the process and eliminate chasing down all of the "losses" to get complete recovery if he uses aqua regia.
If he were to process the biggest lot he mentioned, 2 kg, that would require 6 kg of Silver or sterling silver to make an 8 kg melt. A number 6 bilge crucible in an inexpensive gas furnace would handle that quickly in a single melt. Shotting the entire melt, the parting process can be done in 2 kg lots in beakers small enough to handle. Two kg of the shot would require about 6,600 ml of a 2 part distilled water 1 part (68%) nitric acid mixture. This can be done in a stainless steel 10 liter pot which is easy to handle and resists cracking (unlike glass). The second parting is done with stronger nitric acid 50% distilled water, 50% nitric (68%) acid. For the second parting the insolubles from the first parting need only be covered by a few CM of the acid before heating. This process will get you to 99.5%+ gold with the major impurities (typically the only impurities when refining karat scrap) are silver and copper. Small jewelers using this gold to return to product can easily figure out the new proportions to make quality karat alloys in the karat of their choice.
Without going into it here the cementing out of the Silver from the parting solution is quite easy and fast.
Transferring the hot acids after parting, if lifting and pouring into a filter is too intimidating, can be done by using a vacuum transfer jug to suck out smaller quantities of the acid and pour them through a filter. If you need more details on making a simple vacuum transfer jug just ask and I will give you more details.
If the OP needs 99.99 pure gold, an aqua regia refine at this point will produce the purity he needs with no worries of PGM losses or Silver Chloride to deal with. We have members using the parting as described here and their XRF reads 9999 before any aqua regia refining. I do not know if that is a result of an inexpensive XRF, or the parting process producing a good enough reading for the buyer using XRF to call it 99.99.
Industry standard is ICP analysis and gold purity by difference to determine purity. A technique often bypassed by smaller buyers. (Much to the advantage to folks like the OP)
