Patent ID: 8177411

Claim:
A mixing system, comprising: a first mixing tub; a first actuator to control flow of a carrier fluid into the first mixing tub; a sensor to determine a rate of flow of the carrier fluid; a second actuator to control flow of a dry material into the first mixing tub, wherein the carrier fluid and the dry material mix in the first mixing tub to form a mixture; an at least one weight sensor to determine a weight of the first mixing tub; a second mixing tub, wherein the first mixing tub is configured to flow the mixture into the second mixing tub; and a controller to automatically modulate the second actuator based on the rate of flow of the carrier fluid, based on the weight of the first mixing tub, and based on one of a sensed height of the mixture in the second mixing tub and a sensed weight of the second mixing tub to provide the mixture at substantially a commanded density and/or at substantially a commanded flow rate to a well bore, wherein the controller determines a weight of the mixture in the first tub based on using the weight of the first mixing tub to index into a look-up table and wherein the controller automatically modulates the second actuator based at least in part on the weight of the mixture in the first tub, wherein the look-up table takes account of mechanical coupling of the first mixing tub to other structures.