Abstract: An improved, substantially more energy efficient, thermal treatment process for use on relatively high organic content phosphate rock is herein taught wherein such rock is heated in two stages under controlled conditions to thereby yield an improved calcined product rendered more suitable for subsequent processing into wet-process phosphoric acid by, for example, acidulation with a mixture of phosphoric and sulfuric acids. The two-stage thermal treatment of the instant invention has been demonstrated to be especially beneficial when applied to an apatitic phosphate rock possessing a high content of organic matter and a high degree of carbonate substitution in the apatite crystal lattice thereof.

Abstract: Phosphate rock, containing appreciable quantities of organic impurities, is thermally treated under controlled conditions to fully utilize the fuel values of the organic matter contained therein. This process is beneficial for treating deposits of unaltered Idaho rock containing both higher grade phosphate rock and lower grade phosphatic shales and recovering therefrom substantially all the phosphate values as a rock product rendered more acceptable for acidulation to wet-process phosphoric acid.

Abstract: A flotation process is taught for beneficiating phosphate ores containing, as impurities, silica and alkaline earth metal carbonates, particularly dolomite. Using a single flotation stage, the phosphate values are recovered in the overflow and quite unexpectedly both the siliceous and the carbonate gangue minerals are simultaneously removed in the underflow. Prior to flotation, surfaces of the minerals in the phosphate ore are selectively sulfidized with an insoluble copper-containing metal sulfide, permitting use of sulfide mineral collecting reagents such as alkyl xanthates in the flotation step to achieve a high degree of selectivity.

Abstract: A flotation process is taught for beneficiating phosphate ores containing, as impurities, silica and alkaline earth metal carbonates, particularly dolomite. Using a single flotation stage, the phosphate values are recovered in the overflow and quite unexpectedly both the siliceous and the carbonate gangue minerals are simultaneously removed in the underflow. Prior to flotation, surfaces of the minerals in the phosphate ore are selectively sulfidized with an insoluble copper-containing metal sulfide, permitting use of sulfide mineral collecting reagents such as alkyl xanthates in the flotation step to achieve a high degree of selectivity.

Abstract: Phosphate rock is heated under controlled conditions to essentially eliminate organic impurities and sulfides from the rock and subsequently leached with water to substantially increase the porosity and surface area of the calcined solid and remove any traces of sulfide still remaining in the calcine. This process yields an improved calcined product rendered more suitable for acidulation to wet-process phosphoric acid and is beneficial for apatitic phosphate rocks possessing a moderate to high content of organic impurities and a high degree of carbonate substitution in the apatite crystal lattice.

Abstract: Phosphate rock is heated in two stages under controlled conditions to yield an improved calcined product rendered more suitable for subsequent acidulation by wet-process phosphoric acid. The two-stage thermal treatment of the instant invention is especially beneficial when applied to an apatitic phosphate rock possessing a high content of organic matter and a high degree of carbonate substitution in the apatite crystal lattice. By using heating conditions milder than those proposed by prior-art teachings, the instant process requires less externally supplied energy than such prior art calcination processes and yet yields calcined products of at least, and in most cases, greater than equivalent quality. For phosphate rock from the Pungo River Formation of North Carolina, a first-stage heating temperature in the range of 350.degree. C. to 400.degree. C.

Abstract: Phosphate rock is heated under controlled conditions to essentially eliminate organic impurities and sulfides from the rock when subsequently leached with water to thereby substantially increase the porosity and surface area of the calcined solid and remove any traces of sulfide still remaining in the calcine. This process yields an improved calcined product rendered more suitable for acidulation to wet-process phosphoric acid and is of benefit for unweathered apatitic phosphate rocks of the mineral class known as francolites posessing a moderate to high content of organic impurities and a high degree of carbonate substitution in the apatite crystal lattice, such as that rock originating from the Pungo River Formation of North Carolina. For North Carolina rock, inclusion of the leaching step after calcination at about 800.degree. C. may beneficially provide up to a twentyfold increase in calcine surface area to a level of at least 2 m.sup.2 /g and a sulfide content decreased to less than about 0.

Abstract: A flotation process is taught for beneficiating phosphate ores containing, as impurities, silica and alkaline earth metal carbonates, particularly dolomite. Using a single flotation stage, the phosphate values are recovered in the overflow and quite unexpectedly both the siliceous and the carbonate gangue minerals are simultaneously removed in the underflow. Prior to flotation, surfaces of the minerals in the phosphate ore are selectively sulfidized with an insoluble copper-containing metal sulfide, permitting use of sulfide mineral collecting reagents such as alkyl xanthates in the flotation step to achieve a high degree of selectivity.

Abstract: Phosphate rock, containing appreciable quantities of organic impurities, is thermally treated under controlled conditions to fully utilize the fuel values of the organic matter contained therein. This process is beneficial for treating deposits of unaltered Idaho rock containing both higher grade phosphate rock and lower grade phosphatic shales and recovering therefrom substantially all the phosphate values as a rock product rendered more acceptable for acidulation to wet-process phosphoric acid.