Patent ID: 7056008

Claim:
A system for mixing a cement slurry comprising: i) a liquid material supply ( 101 ) including a device ( 104 ) for measuring the amount of liquid material supplied; ii) a solid cement supply ( 108 ); iii) a mixer including a tub ( 114 ) which receives the liquid and solid cement and includes an output ( 124 ) for delivering materials from the mixer to a delivery system; iv) a flow meter ( 128 ) in the output ( 124 ); and v) a computing device, wherein: the system further comprises a device ( 120 ) for measuring the amount of material in the mixer; the computing device receives the output from the device ( 120 ) for measuring the amount of material in the mixer and from the flow meter ( 104 ) and is arranged to calculate the variation in the amount of material in the tub ( 114 ) over time, and the solid fraction of the mixture; and the calculated solid fraction is used to control the relative amounts of solid and liquid material added to the mixer.