A method for recovery of precious metal, wherein the method comprising arranging a plurality of adsorption vessels in series, wherein each adsorption vessel comprises a reactor space, a closed retention space within the reactor space, a retention screen between the reactor space and the closed retention space, first inlet means for feeding slurry containing precious metal into the reactor space, second inlet means for feeding adsorption particles into the reactor space, first outlet means for feeding slurry containing precious metal from the closed retention space, and second outlet means for feeding adsorption particles from the reactor space, feeding slurry containing precious metal into the reactor space of each adsorption vessel, feeding adsorption particles into the reactor space of each adsorption vessel, wherein precious metals are adsorbed onto the adsorption particles, moving the slurry through the plurality of adsorption vessels with a first drive system in a first flow direction A so that the slurry moves through the retention screen in the reactor space of at least one adsorption vessel of said plurality of adsorption vessels into the closed retention space of said at least one adsorption vessel, wherein the adsorption particles cannot pass through the retention screen whereas the slurry passes through the retention screen, and moving the adsorption particles with a second drive system through the plurality of adsorption vessels in a second flow direction B that is opposite the first direction, characterized by arranging in said at least one adsorption vessel of said plurality of adsorption vessels first electrodes of a first probe in electrical contact with the slurry downstream of the retention screen in the first flow direction A, by a first measurement step for either (i) supplying with first electrodes of the first probe a first supplied voltage to the slurry downstream of the retention screen in the first flow direction A and receiving with first electrodes of the first probe a first received current from the slurry downstream of the retention screen in the first flow direction A, or (ii) supplying with first electrodes of the first probe a first supplied current to the slurry downstream of the retention screen in the first flow direction A and receiving with first electrodes of the first probe a first received voltage from the slurry downstream of the retention screen in the first flow direction A, by arranging in said at least one adsorption vessel of said plurality of adsorption vessels second electrodes of a second probe in electrical contact with the slurry upstream of the retention screen in the first flow direction A, by a second measurement step for either (i) supplying with the second electrodes of the second probe a second supplied voltage to the slurry upstream of the retention screen in the first flow direction A and receiving with the second electrodes of the second probe a second received current from the slurry upstream of the retention screen in the first flow direction A, or (ii) supplying with the second electrodes of the second probe a second supplied current to the slurry upstream of the retention screen in the first flow direction A and receiving with the second electrodes of the second probe a second received voltage from the slurry upstream of the retention screen in the first flow direction A, by functionally connecting a data processor device with the first probe and with the second probe, by calculating with the data processor device a first electrical property of the slurry downstream of the retention screen in the first flow direction A either (i) based on a first difference between the first supplied current and the first received voltage, or (ii) based on a first difference between the first supplied voltage and the first received current, by calculating with the data processor device a second electrical property of the slurry upstream of the retention screen in the first flow direction A either (i) based on a second difference between the second supplied current and the second received voltage, or (ii) based on a second difference between the second supplied voltage and the second received current, and by calculating with the data processor device the adsorption particle content of the slurry upstream of the retention screen in the first flow direction A based on a difference between the first electrical property and the second electrical property.