Patent ID: 7370820

Claim:
A method for harvesting weighting agent fines from a commercial-grade weighting agent production process comprising: milling weighting agent into a plurality of weighting agent particles; classifying milled weighting agent in a first classifier to separate weighting agent particles having a particle size less than an acceptable maximum diameter for commercial-grade weighting agent from weighting agent particles having a particle size greater than the acceptable maximum diameter for commercial-grade weighting agent; discharging weighting agent particles having a particle size less than the acceptable maximum diameter for commercial-grade weighting agent into a cyclone; cyclonically removing a portion of fine weighting agent particles from larger weighting agent particles, wherein the fine weighting agent particles have a particle size below an acceptable minimum diameter for commercial-grade weighting agent; trapping the fine weighting agent particles in a baghouse; releasing the fine weighting agent particles to a second classifier; classifying the released weighting agent particles into a coarse particle group and a fines particle group based on particle size, wherein more than 98% of the weighting agent particles in the fines particle group have a particle size less than the acceptable minimum diameter for commercial-grade weighting agent and less than 15% of the weighting agent particles in the coarse particle group have a particle size less than the acceptable minimum diameter for commercial-grade weighting agent.