Wilderness Technology, Inc. is currently designing a system to meter by weight the bag house fines and return them to the Asphalt mix. With the new mix designs that use more open grade mixes, it can be a problem with too many fines. It may make it more difficult to get the voids necessary.
At the present in California, CALTRANS requires all bag house fines to be rejected or returned 100%. Anything in between must be metered by weight. Problem with measuring is the temperature of the material, small amount less than 10% of mix and the lightweight of the fines. Central to the system we are working on is a scale auger as opposed to a scale belt. This scale auger or auger scale, will handle the high temperature of the material and enclose it. Accuracy for CALTRANS has to be +- 1%. I have seen several systems that attempt this but can not hold the accuracy requirements.
The basic system will have a small silo or hopper to receive the fines from the bag house. The total fines collected will be weighted, so you know what came out of the cold feeds. The scale auger will meter out the fines that your asphalt plant controller calls for and injects the fines back into the drum or mixing device.
We are in the design phase on this right now, if you would like to offer any inputs or needs relating to this please call or email. I would like to talk to you and get your input.