separating almond flour from almond meal

Any good hardware store will sell screen in a variety of mesh sizes. Pick one out that matches your dome-sieve, and buy a couple square feet. Make a wooden frame with say six inch sides, and tack the screen solidly to the bottom. Sieve into a clean dishpan. Your sifting rate will increase substantially over what you're getting now.

For really fine flour, head to the fabric store, or buy a pair of nylons, and frame as I've already described.

The main differences between almond meal and almond flour are that almond meal is generally more coarsely ground and more likely be made from the whole almond with its skin (the brown flecks you see in the meal), while almond flour is almost always made from blanched almonds and is ground more finely. Both contain the whole almond (except the flour will never contain the skin), so both should have pretty much the same oil level. There's a limit to how finely you can grind the almonds before they release all their oil and turn into paste/butter, so I don't think you will find almond flours that are as fine as the finer wheat flours.

The coarse grind of almond meal and the almond skin contributes to the grittiness. I don't think it would affect the fat content, though, unless the oil that is released tends to be absorbed in the skins and come out with them when you sift.

Have you considered making your own almond flour? If you grind your own you can control how finely you grind it, although if you grind it too much you will end up with an oily paste (almond butter, essentially), so this is definitely something that takes some attention and care. You may need to sift it partway through and continue grinding only the parts that are still too coarse.

BTW, the Bob's Red Mill brand claims their "almond meal/flour" is from blanched almonds and "finely ground", so technically I do think it qualifies as almond flour, at least by the definitions I have found. Perhaps you could simply dry-grind it further to get it to a consistency that works for you. Sift with a regular sieve (your current process), then grind the part that gets held back, repeat.

King Arthur Flour also sells an "almond flour" that is from blanched almonds and "very finely ground". It's been a while since I used it, but I think it is actually finer than the bob's mill, but also pricier and not as easy to find in stores, so shipping makes it pricier. (It looks like they offer a toasted almond flour, too, now, but of course that's not the same thing.)

I've also seen almond flour at some Indian markets, but that would vary in texture from store to store (they were pretty much bulk-packaged things, non-branded).

As a non-almond alternative, you might try coconut flour, or perhaps mixing it in with your almond flour. The ones I've tried do have a bit of a toasted-coconut flavor but I think at a 50-50 ratio it should be reasonably masked by the wheat. The texture is dryer and I don't find it to be gritty. (It does absorb a lot of liquid, though.) I believe it is lower in starch than almond flour.

Buy the almond flour from Safeway goes through my sift like confectioners' sugar. I do this thing where I keep my almond flour in the freezer; i feel like it prevents the almonds from turning into an oily paste if you need to keep processing it because of the bigger chunks.