Abstract: A redundant automation system including a set of redundant PLCs including of a pair of PLCs each equipped with two communication couplers. The first coupler in the first PLC is connected to the first coupler in the second PLC through a first Ethernet network and the second coupler in the first PLC is connected to the second coupler in the second PLC through a second Ethernet network, connecting them to at least one remote equipment. Each of the PLCs has a hardware address and an IP address, the set of redundant PLCs being accessible from outside by a single IP address assigned to a first normal PLC, and a switching mechanism assigns the address related to normal operation to the second PLC, the IP address of the standby operation being assigned to the first PLC.

Abstract: In a treatment of carnallitic ores by treatment with a decomposition-brine containing amounts of MgCl.sub.2, KCl and NaCl suitable for precipitating artificial sylvinite in a solution of MgCl.sub.2 saturated in KCl and NaCl, the improvement of adding to said decomposition-brine a collector, e.g., a fatty amine acetate, for the flotation of KCl and a source of gas, preferably a gas-liberating additive such as H.sub.2 O.sub.2, so as to contact newly formed crystal nucleii of KCl selectively with said collector and to contact bubbles of said gas with said collector so as to form a froth enriched in KCl simultaneously with the decomposition of said carnallite, the process being particularly useful for treatment of underground carnallitic ore whereby the froth and brine are withdrawn at the surface, separated, and the brine, after make-up additions, is recycled to the ore formation.