Method and device for activating a physical and/or a chemical reaction in a fluid medium

A process for activating a physical and/or chemical reaction in a mixture subjected to agitation and comprising a solution charged with a noble metal in ionic form and a reactive metal introduced in solid form and freely dispersed in the solution so as to obtain a cementation from the reactive metal reacting to the noble metal present in the solution, comprising:

• injecting the solution via the bottom of a reactor having two walls facing one or another and close to one another, the mixture filling the space between the two walls and forming therein a layer of small thickness and of great length in a direction defined by a geometric axis parallel to the walls, an agitating means movably attached to the reactor including a plurality of electromagnets, the electromagnets being arranged outside the reactor to act through said walls on an agitation zone covering a part of said layer and having a small dimension in the direction of the geometric axis;
• causing an ascending flow of the solution in a vertical direction parallel to the walls so as to form a fluidised bed;
• introducing solid ferromagnetic particles, at the top part of the fluidised bed, which particles are the seat of a disposition when the cementation reaction takes place, agitating the mixture by activating the electromagnets sequentially supplied with periodic currents to create an electromagnetic field able to direct the ferromagnetic particles alternately in two distinct directions;
• moving the agitating means in an alternating movement between a first extreme position and a second extreme position so that the agitation zone spans appreciably the whole of said space located between the two walls;
• and
• cementing the noble metal from the mixture.