Thanks for the recall WilliamSlayer!
Codge...Mass processing of oranges. Well, in commercial arena the whole orange is 'squished', my fancy word of the day, and then the entire orange pulpy chunky mess is filtered to immediately capture/remove the peel, seeds and pulpy fiber & and then the juice is extracted. I would definitely choose NOT to ferment the whole orange. In fact, I would not even ferment on the orange peels unless you can remove all of the pith, and then it would be peels in moderation and even then it could be a crap shoot because not all orange varieties have a peel that you want to cook/bake/ferment with. As WmS mentioned, the pith does impart such a bitter and astringent component that it is almost impossible to correct... so avoid that at all costs. I would consider hand peeling some oranges, as in with a knife or veggie peeler, with the goal of getting strips of pith-free peel, zesting would be a PITA.
Avoid bleach products anywhere in/around/near your winemaking. Do not even clean things with bleach or bleach components. If you have heard of cork taint, well, a bleach product is typically in use somewhere on the premises. You have other alternatives to clean your fruit, k-meta being a great choice.
I do not even have words to express my concern about using a concrete mixer to clean/process fruit--perhaps my mind is in overdrive--but obviously you are wanting a tumbling motion to clean your fruit? Is the mixer powerwashed and clean, no toxic contents? I initially imagined a concrete TRUCK and oranges rolling down the chute! I read that someone put oranges in washing machine(which had been cleaned/sanitized) then turned on a gentle rinse cycle, using cold water, and used k-meta...they said it worked--I have no clue, no experience...but wouldn't that be awesome?
But for a grinder you can mount a new garbage disposal system over your collection container (5gal bucket, etc) which has been lined with a fine mesh straining bag-you can find schematics on YouTube, etc, and then using a fruit press (or improvise with buckets) you can extract the juice. Do any of your area grocery/health food stores have a 'fresh squeezed OJ extractor' on site? Perhaps you can make a deal and have them press your oranges for you? Put an ad in Craigslist, you may find someone willing to rent it to you--especially in today's economy.
As far as recipes for orange wine, results/reports from others have been hit or miss on the success of fermenting with oranges. I do know there is a Cuties Spiced Mead in the mead section which is noted as a success, and there have been posts noting variation in the recipe..you may want to check that out.
Chocolate orange port is good. A batch of JMAO mead. Imagining a grapefruit-orange blend. Man I wish I had a box of your oranges!!
In closing, be sure to inspect your fallen fruit and do not use damaged goods. Quality in, quality out is the goal.
Please, keep us posted. I want to read all about your escapades!
My apologies for the novella,
Sara