Technical Gate valve next to ball valve?

I have been working on this over the past few months, but I believe this question warrants an entirely different discussion. It was advised to me a month ago, that I may want to use a gate valve next to my ball valve to regulate blasting sand. Some have told me not to use a gate valve at all, and others have told me it won't work unless I use a gate valve.

A gate valve would make it easier to fine tune the flow at the bottom of my tank. This is the contraption I have made so far and I can put them at any order. It's a ball valve that runs into a gate valve that will going into a blaster hose. Is this a bad idea or could it work?

 

a gate valve will get packed w/ sand and be a MAJOR annoyance to you.

 

It has to be a gate valve, not a seat valve.
1/4 turn on off ball valve at the tank, gate valve below the ball valve, just like you have it.
If the gate valve blocks up, simply close the ball valve and full open the gate valve. The obstruction will pass, then throttle back the gate valve