US4033838A - Recovery of copper from waste .
An electrolytic process for the recovery of copper and regeneration of nitric acid from a waste liquor containing the same comprising adjusting the nitrate and hydronium ion concentrations in the liquor to between about 2 to 12 moles per liter and between about 0.5 to 6 moles per liter, respectively, and subjecting the liquor to electrolysis at a temperature of between about 0° to 55° C ...