staurum,
I would use small batches to experiment with. This way you can try several different things to see what works best. Knowing that what may work on a small batch may need more for a larger batch, like amount of acid rinse, best water temperature for acid rinse (how hot the water), like amount of time for the reaction, amount of stirring and what type of stirring is needed during the reaction, amount of reagents needed for complete conversion, what type of conversion may work better, or if you may make more money and save more time by not making silver chloride but using copper to cement silver wash and melt, small experiments with amount of rinsing needed and how to get the best results, what type of stirring works best, and time, amounts of reactants needed or temperatures needed...
I still do not understand Why you want to make silver chloride, especially in large batches that would be harder to deal with, 1 gram of copper will cement 3.4 grams of silver from AgNO3 solution, so if my math is right one pound of copper (453.5 g) will cement approximately 1,542 grams of silver (3.4g x 453.5g = 1,542g), or 1,542 / 31.103g = 49.57 ounces of silver per pound of copper, the copper cost I am guessing 2 to 3 dollars a pound, at 27 dollar silver spot ($27 x 49.57oz = $1,338.39 of silver for using 3 dollars of copper), copper price compare to the price of silver that is cheap, and you could just be losing more silver than that in your smoke right now, try a few experiments on a few small batch's, the copper could be recovered and reused after washing from the copper nitrate solution, to help save some on the copper you would need to purchase, you may also try and find a cheaper source for your copper.
If your rinses look milky it can be silver chloride (possibly from a still acidic solution using up the NaOH before all of the silver chloride has reacted completely), if you did not rinse the acid out of the silver chloride well, you will have more acid for the sodium hydroxide to convert to salt, this could use up a good portion of your NaOH even before the NaOH has a chance to react with the silver chloride, the silver chloride can also trap acid especially in larger batches that are not stirred well or chopped up well during the rinsing of your acid hot water here can help also, giving enough time for the reaction to occur and a good stirring to break up and mix the solution well so that all of the silver gets converted, each silver atom needs to be freed from the chloride, and each chloride must be freed from the silver to join the sodium to make salt NaCl, if the silver chloride is in lumps or crystals, and not stirred very well for good exposure the reaction may not occur if the reagents and the reactant do not get good contact and stay in contact long enough to react, then the electron will not be able to move to every tiny atom in this large volume of heavy powders that need to give or take those tiny electrons, crystal can be like huge clumps of atoms to a small electron, and the this big clump of silver chloride may need broken up to expose the inside silver chloride atoms to the caustic solution to the tiny electron wanting to free the silver atom from its chloride bond.
Most things are more soluble in hot water than cold water, and hot water will normally do a better job, here the hot water will help with the syrup, and help to free the salt from the powders but NaCl itself is not that much more soluble in hot water compared to cooler water as many of the other salts are.