Patent ID: 9744537
Date: 2017-08-29
CPC Classifications: B03B

Claim:
1. A process for refining sand for use as frac sand, the method comprising the steps of: passing the sand through a first fines separation stage to remove fine particles of contaminant from the sand; reducing the water content of the sand to less than 20%; passing the sand into an attrition scrubber unit containing moving blades to delaminate clay and other contaminants from the sand; passing the sand from the attrition scrubber unit through a second fines separation stage to separate fine contaminants from the sand; dewatering the resulting sand product in a further dewatering stage; and controlling the water content of the sand upstream of the attrition scrubber unit such that the sand entering the attrition scrubber unit has a water content of between 20% and 25%; wherein the water content of the sand is controlled by determining the water content of the sand and adding water to the sand to achieve the required water content, and wherein the water content of the sand is determined by monitoring the torque demand of the attrition scrubber unit.