Abstract: The invention relates to a method for controlling a process operating by means of the electrochemical potential, in which process complex ores and/or concentrates are treated in order to arrange the valuable components in the materials in a form appropriate for further processing and in which method electrodes made of material essentially similar to the materials to be treated in the process. According to the invention an impedance analysis in connection with the measurement of the electrochemical potential is carried out for the material to be treated in process in order to analyze the state of the solid surface and/or the state between the solid material and the intermediary material. The measured values are utilized in the adjustment of the process parameters. In order to carry out the impedance analysis voltage pulses are conducted into the material in at least one frequency and in at least one value of the electrochemical potential of the material.

Abstract: The invention relates to a process for the froth flotation of complex ores. In accordance with this invention, froth flotation is carried out by using a collector and froth flotation conditions for which it has been calculated in advance that the said mineral and the collector form stable surface compounds. The conditions include the electrochemical potential of the system, the concentration of the collector, the pH, and other physical factors. According to this invention it has been observed that by adjusting the potential and the concentration of the collector separately for each mineral, each mineral can be frothed out separately from the slurry, the process being in this case specific for the mineral. When so desired, the different minerals of the ore slurry can also be frothed simultaneously by selecting the conditions where the Pourfaix-type diagrams of all minerals in said complex ore overlap under the conditions in question.

Abstract: The present invention relates to a process for the separation of gold and silver from complex sulfide ores and concentrates which, in addition to the primary metals, contain constituents having an adverse effect on the separation of the noble metals, by heating the sulfide ore or concentrate at a temperature of 600.degree.-900.degree. C. and a sulfur pressure of 0.2-1 atm in order to bring the complex metal compounds to a suitable form for subsequent alkalic cyanide leaching, and by separating the gold- and silver-bearing cyanide solution from the undissolved residue.

Abstract: A process is disclosed for the recovery of lead, silver and gold from the iron-bearing residue of an electrolytic zinc process by froth-flotating a slurry of the iron-bearing residue in the presence of a sulfidic collector agent in order to froth-flotate the sulfides and to separate them from the iron-bearing residue. The iron-bearing residue is sulfidized selectively in order to convert the lead, silver and possibly gold substantially quantitatively to sulfides before the iron-bearing residue is froth-flotated.

Abstract: A process for the separate recovery of phosphate and carbonate minerals from finely-divided phosphate-carbonate-silicate ores or concentrates with a carbonate to phosphate ratio of over 1 is disclosed, in which an anionic collector agent is added to an aqueous slurry of these ores and concentrates, the slurry is then exposed to froth-flotation in order to separate a silicate-bearing residue from phosphate-carbonate concentrate, thereafter(a) the combined phosphate-carbonate concentrate is either treated with a base in order to remove the collector-agent coatings from the surfaces of the mineral particles, whereafter the combined concentrate is froth-flotated with a cationic collector agent using a depressing agent for carbonate in order to recover the phosphate concentrate and the carbonate concentrate separately, or(b) the aqueous slurry to which the anionic collector agent has been added and which has been froth-flotated is treated with sulfur dioxide or carbon dioxide in order to inactivate the collector-a