Patent ID: 7322433

Claim:
A tool for excavating an object, the tool comprising: a jetting system arranged to impinge the object to be excavated with a jetted stream of a drilling fluid mixed with abrasive particles, the jetting system being provided with at least a mixing chamber with a drilling fluid inlet, a second inlet for abrasive particles, and an outlet nozzle for releasing the drilling fluid mixed with the abrasive particles; a recirculation system ranged to recirculate at least some of the abrasive particles, from a return stream of the fluid mixed with the abrasive particles downstream impingement of the jet with the object back to the jetting system, whereby the abrasive particles comprise a magnetic material, which recirculation system comprises a separator magnet for separating the abrasive particles from said return stream and for transporting the particles to the second inlet; a piece of magnetic material that is provided in or in the vicinity of the mixing chamber such as to draw a part of the magnetic field generated by the separator magnet into the mixing chamber.