Essentially though the fact that you work in a very dusty environment will wreak havoc on ANY folder you have. The Chive is a great knife, and as was said above, the mechanism is about as simple and easy to clean that you're going to find. My suggestion would be to a. Buy a bag of a couple torsion bars, try not to exessively flip it over and over in quick succession, and clean it when you start hearing a crackling dust inside the mechanism (every couple weeks). b. Buy a cheap ass folder you don't care about or, c. Buy a fixed blade.
I really must say that even if you spent $1000 on a sweet custom automatic/assisted opening knife you'd see the EXACT same problems, and probably have more of an issue trying to get new torsion bars, etc...
Oh yeah! If you can't take your Chive apart, check out Benchmade's Blue Box. It's a bit set of Torx that'll let you rip that knife apart and clean it up.
:EDIT: After re-reading your post, I noticed something. Your mention of lubricating the knife made me think you had taken it apart, but it's a distinct possibility you just dropped lube in the joint. If so, that it the exact problem. The opening mechanism for the Chive is a small 'pocket' in one of the handles which houses the torsion bar. When you open/close the knife it flexes and dust can get in the edge of the pocket. When this happens it slows the motion of the torsion bar drastically, and the only way to fix it is to rip the knife apart, remove the torsion bar, clean it all out completely and reapply lubrication and the bar.
Good luck!