Hello,
A rough procedure to create something like this is:
1) You need to have first the sand model (like a very small cube or whatever you like). Avoid something with a lot of polygons.
2) Create 4 emiters from 4 sides to emit the sand model in the center. This is to simulate the sand coming from all directions. Make the emiters big enough to your liking and set a very high number in birthrate renderer. Also make sure to adjust the particle parameters of the emiter according to your scene.
3) Then you can add dynamics in your scene to make it more like. The most appropriate ones I think are the the turbulence, attraction and rotation.
You will need to fine tune it to match your desired result, by changing the speed or adding also some wind in the scene. Playing then the scene might be hard considering how many particles you have and what kind of computer you have. Keep in minf that there might by plugins that will do this better and easier.