Process of purifying or recovering mine drainage waters and the like

Claim 1

THE PROCESS OF PURIFYING MINE DRAINAGE WATER AND THE LIKE CONTAINING SULPHATES OF IRON DISSOLVED THEREIN AND CONTAINING SULPHURIC ACID, WHICH COMPRISES NEUTRALIZING THE SULPHURIC ACID CONTENT OF SUCH WATER WITH METALLIC IRON AND CONVERTING THE IRON SULPHATES ORIGINALLY CONTAINED IN SUCH WATER AND ALSO THE IRON SULPHATES RESULTING FROM THE AFOREMENTIONED ACID-NEUTRALIZATION TO INSOLUBLE IRON COMPOUNDS, BY ADDING METALLIC IRON AND OXYGEN TO SUCH WATER IN AMOUNTS SUBSTANTIALLY IN EXCESS OF THE STOICHIOMETRIC PROPORTIONS THEREOF IN RELATION TO THE IRON CONTENT AND SULPHURIC ACID CONTENT OF THE WATER AND CONCURRENTLY SUBJECTING SUCH WATER TO THE ACTION OF SUCH METALLIC IRON AND OXYGEN UNTIL THE ACIDITY OF THE WATER HAS BEEN REDUCED TO A POINT APPROCAHING NEUTRALITY AND THE ORIGINAL IRON CONTENT AND SULPHATE ION CONTENT OF THE WATER HAVE BEEN CONVERTED TO INSOLUBLE BASIC IRON SULPHATES.