Abstract: A process for in situ immobilization of metals in waste stack affected zones including a waste stack and any adjacent boundary zone.

Abstract: A process for in situ immobilization of metals in waste stack affected zones including a waste stack and any adjacent boundary zone.

Abstract: Ores containing mineral values are separated into two slurries, one having primarily fine particles and gangue and the other having primarily coarse particles. The slurry having fine particles and gangue is adjusted to a solids content of less than about 15 percent, as necessary, and then conditioned by the addition of appropriate promoter reagents, a flotation collector, and a froth modifier. The gangue, containing a disproportionate share of impurities, is floated in a column flotation cell wherein the fine particulates are not mechanically agitated, and removed. The remaining fine particulate underflow, containing a disproportionate share of the minearl values, is then processed directly, or combined with the slurry containing the coarse particulate to yield a flow having reduced impurity content and increased recovery of the mineral values.

Abstract: A process for the selective recovery of cadmium, molybdenum, zinc, nickel and other metal values from wet process phosphoric acid and other acidic to slightly basic carrier solutions, wherein the metal-bearing solution is contacted with an organophosphene extractant to precipitate the metal values for subsequent separation from the solution. Separation may be effected by mechanical means or by scrubbing with a water-immiscible organic solvent such as kerosene for subsequent recovery of the metal values. The metal specie recovered is determined by the concentration of the organophosphene, which may be selectively adjusted to recover a series of metal values in a sequence of stages.

Abstract: Methods for control of excessive corrosion in wet process phosphoric circuits are effected by oxidation of reduced ion species in the acid with maintenance of EMF value of the acid above about 190 millivolts (S.C.E. reference) through the digestion circuit. Supplementary monitoring is by a ceric red-ox titration procedure. In one embodied form, the present invention is utilized to control corrosion in a phosphoric acid plant digestion system (and subsequent processing equipment) operating by a dihydrate (gypsum) process even when such a process employs a calcined western U.S. phosphate ore feed from a relatively highly carbonaceous ore. The invention is also applicable for treating wet process phosphoric acid in phosphoric acid plants having a digester system operating by a hemihydrate process.

Abstract: Methods for control of excessive corrosion in wet process phosphoric circuits are effected by oxidation of reduced ion species in the acid with maintenance of EMF value of the acid above about 190 millivolts (S.C.E. reference) through the digestion circuit. Supplementary monitoring is by a ceric red-ox titration procedure. In one embodied form, the present invention is utilized to control corrosion in a phosphoric acid plant digestion system (and subsequent processing equipment) operating by a dihydrate (gypsum) process even when such a process employs a calcined western U.S. phosphate ore feed from a relatively highly carbonaceous ore. The invention is also applicable for treating wet process phosphoric acid in phosphoric acid plants having a digester system operating by a hemihydrate process.