I would recommend to you make your risotto in 3 batches of 10 quarts each.
You could do it all at once, but you loose control over the quality.
This is only my opinion and you might get different answers from other chefs???
This curdling happens less if you mix in your eggs one at a time after the creaming of your butter and sugar.
It is also important that your eggs are at room temperature.
No need to make a paste first.
I take my copper pot upside-down and pour a little heap of table salt in the center of it and then wet the salt with a bit of vinegar before spreading this mix with my finger-tips over the whole outside...
Half regular table salt and half white vinegar is the cheapest way to go. Actually you can use any salt , even kosher salt and any kind of vinegar you feel like using
