Hydrometallurgical Separations by Solvent Membranes

Abstract

Comparing the schedule of the present symposium on industrial membrane processes with similar meetings a few years ago, i.e., the NATO Symposium on Membrane Applications in Ravello in 1966, one is positively surprised at the progress that has been made and also to what extent was justified the optimism of those who foresaw a few years ago a new chemical unit operation in the field of membrane separations. Reverse osmosis is today a leading process in the desalination of brackish water. Its use in various other industrial applications has successfully been proven in various installations of pilot-plant size. The same seems to be true of various ultrafiltration processes in the pharmaceutical industry and in food processing. The expectations attached today to the membrane field are well demonstrated by the exclusive forecast of the Mellon Institute which foresees by 1975 a five—fold increase of the annual expenditure volume in membrane rates, presently estimated at 15 million dollars. When mentioning this list of successful membrane processes one should, as a matter of fairness, mention some of the processes which have not completely lived up to the expectations held a few years ago. It is probably no coincidence, but representative for the present state of the art, that processes such as liquid permeation and gas separation, both of which were once considered of large potential interest to the oil-processing industry, do not appear on the program of the present symposium.