FUNDMENTAL STUDY ON FLOTATION OF PRECIPITATES FORMED IN NEUTRALIZATION PROCESS OF WASTEWATER

Research Project

Project/Area Number	60550437
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	資源開発工学
Research Institution	AKITA UNIVERSITY
Principal Investigator	MAMIYA MITSUO MINING COLLEGE, AKITA UNIV., 鉱山学部, 教授 (00006628)
Co-Investigator(Kenkyū-buntansha)	FUJITA TOYOHISA MINING COLLEGE, AKITA UNIV., 鉱山学部, 講師 (70124617)
Project Period (FY)	1985 – 1986
Project Status	Completed (Fiscal Year 1986)
Budget Amount *help	¥1,100,000 (Direct Cost: ¥1,100,000) Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1985: ¥700,000 (Direct Cost: ¥700,000)
Keywords	Flotation / Recycling / Wastewater treatment / 中和殿物 / リサイクリング
Research Abstract	ACID EFFLUENT FROM SOME PROCESS IN ZINC HYDROMETALLURGY IS NEUTRALIZED WITH SLAKED LIME AND THE PRECIPITATES FORMED, WHICH MAINLY CONSIST OF ZINC HYDROXIDE AND GYPSUM, ARE DUMPED INTO DAM. IN ORDER TO UTILIZE THESE PRECIPITATES SELECTIVE FLOTATION OF ZINC HYDROXIDE FROM GYPSUM HAS BEEN INVESTIGATED. AS A FUNDAMENTAL STUDY, FLOATABILITY OF ZINC HYDROXIDE WAS EXAMINED USING DODECYL AMMONIUM ACETATE (DAA) OR SODIUM DODECYLSULFATE (SDS) AS A COLLECTOR. IT WAS FOUNED THAT ZINC HYDROXIDE WAS RELATIVELY FLOATABLE WITH DAA OR SDS AT WIDE PH RANGE IN ALKALINE MEDIUM. THEN THE EFFECTS OF SOLUBLE STARCH AND SODIUM SILICATE ON THE FLOATABILITY OF ZINC HYDROXIDE AND GYPSUM WERE EXAMINED. IT WAS SHOWN THAT SODIUM SILICATE TENDED TO DEPRESS ZINC HYDROXIDE EFFECTIVELY WHEN SDS WAS USED AS A COLLECTOR. FROM THE SELECTIVE FLOTATION FOR THE MIXTURE OF ZINC HYDROXIDE AND GYPSUM, IT WAS SHOWN THAT SATISFACTORY SEPARATION COULD BE ACHIEVED ONLY WHEN SDS WAS USED AS A COLLECTOR AND SODIUM SILICATE AS A DEPRESSANT FOR ZINC HYDROXIDE. SYNTHETIC WATER OF PH 5.0 CONTAINING 1000MG/L OF ZINC IONS, 7328MG/L OF SULFATE IONS AND 603MG/L OF CALCIUM IONS WAS NEUTRALIZED WITH SLAKED LIME UNTIL PH 8.5. THE FLOTATION TESTS WERE CONDUCTED FOR THE PRECIPITATES THUS FORMED. ZINC HYDROXIDE WAS EFFECTIVELY SEPARATED FROM GYPSUM WITH SDS COLLECTOR WHEN SODIUM SILICATE WAS ADDED IN BOTH PROCESS OF NEUTRALIZATION AND FLOTATION, AND SOME 90% OF GYPSUM WAS RECOVERED IN THE FROTH AND 87% of zinc HYDROXIDE IN THE TAILING SOLUTION.