I'm seeing an infinite zirconia generation cycle in the form of : 1 zirconia + 5 sulfuric-acid -> 1 zirconium-sponge, 1 zirconium-sponge + 1 silica -> 1 zircon, and 1 zircon -> 1.9 zirconia + 0.1 titanium-ore (average). So this is basically transmuting 1 silica and 5 sulfuric acid into 0.9 extra zirconia (and 0.1 titanium) which seems very powerful and potentially unintended since 1 silica is worth less than 1 stone and sulfuric acid is usually infinite. In particular it seems to outclass the "sort stone for zircon" recipe by a lot.

I'm playing with multiple mods, but Factoriopedia indicates that only Zirconium has touched these three recipes.