Abstract: A technique is provided for leaching particulate ores for recovering metal values. Ore is crushed to less than about one inch with at least 25% being greater than 4 mesh. The crushed ore is mixed with a small amount of acid and the moistened mixture is kept in a curling pile for about two days for dehydration and induration of the ore. The induration is sufficient that the ore can sustain the weight of a thin layer of about one-half to one meter thick without appreciable compacting. The indurated ore is spread on a permeable substrate in a thin layer about one-half to one meter thick. A leaching solution is then percolated through this thin layer to remove the metal values. The initial effluent leach liquor has high metal values and low acid content and is passed to a solvent extraction system where the metal values are recovered. The solvent extraction raffinate, which is high in acid, is recirculated as a leach liquid.

Abstract: Two liquids of different density and which are mutually insoluble are temporarily contacted with each other by flowing them countercurrently through a series of contactor units which each includes a mixing sump, a retention channel, and a settling tank. The two liquids are mixed with a pumping type impeller in a mixing sump connected by a retention channel to a settling tank where the mixed liquids separate into upper and lower layers, which are separately removed and fed to the respective sumps of the next succeeding units. The retention channel is relatively long and narrow to provide the required interaction time between the two liquids in the mixture, and still prevent any substantial separation of the two liquids within the channel. The retention channel is also relatively shallow so the sump, channel, and settling tank bottoms are at substantially the same level.

Abstract: A mixture of a first liquid of one density and a second liquid of a different density and which is substantially insoluble in the first liquid is separated by flowing the mixture through a gravity settler tank where the mixture separates into a clear upper layer of the lighter liquid, a clear lower layer of the heavier liquid, and an intermediate layer of uncoalesced droplets of one of the liquids dispersed in a continuous phase of the other at the interface between the upper and lower layers. Clear liquid from the upper layer is withdrawn through an overflow, and clear liquid from the lower layer is withdrawn through an underflow. An impediment or baffle extends across the settler tank transversely to the direction of liquid flow, and is disposed in the intermediate layer of the mixture of the two liquids to impede the flow of the intermediate layer away from the tank inlet.