Thermodynamic calculations of restoration of the oxidized copper minerals in a pulp are resulted by formaldehyde are presented. Boundary conditions of metal copper formation on a surface of the oxidized minerals is characterised by equality of Eh-potentials of halfreactions of formaldehyde oxidation and restoration of malachite, azurite, cuprite. Experimental data of determination of optimum conditions of chrysocolla restoration have shown that its maximum floatability is reached at Eh pulps from 0 to +50 мВ. The developed principle diagram of automation for flow adjustment of the reagent will allow to lower essentially the general expense of reagents and to improve technological indices.