Abstract: In a continuous process for reacting particulate ore with a liquid reagent in a counter-current vertical column the improvement comprising:(a) providing an upper and lower chamber for the vertical column;(b) maintaining sufficient upward flow of liquid reagent in The upper chamber so that the particulate ore is wetted and deaerated, at least some fine particles thereof are carried overhead for removal, and the remainder thereof settle and enter the lower chamber; and(c) maintaining sufficient fluidization and retention time in the lower chamber so that the desired amount of reaction with the ore takes place, at least some of the fine ore particles which are generated from the reaction process and/or which are introduced with the particulate ore are entrained and carried upward for removal, and the reacted particulate ore exits the lower chamber.