THE FLOTATION CHEMISTRY OF POTASSIUM DOUBLE SALTS: SCHOENITE, KAINITE, AND CARNALLITE

摘要

It is known from soluble salt flotation practice thatrnthe K, Mg double salts of kainite (KClMgSO4 3H2 O),rnand carnallite (KClMgCl2 6H2 O) are difficult to floatrnand must be converted to other salts such asrnschoenite (K2 SO4 MgSO4 6H2 O) and sylvite (KCl) inrnorder to recover potash values. The flotationrncharacteristics of these double salts have now beenrnconfirmed in some detail by carefully controlledrnlaboratory experiments with both cationic andrnanionic collectors. The experimental results arerndiscussed in view of recent experimental findingsrnregarding the flotation characteristics of simple salts,rnin which the flotation response was shown to berndetermined by the interfacial water structure andrnwhether the salt could be considered to be a waterrnstructure maker or a water structure breaker. Thernsame approach can be use to explain the flotationrnresponse of the potassium double salts ; schoenite,rnkainite, and carnallite.rnIn addition, the sign of the surface charge ofrnschoenite (K2 SO4 MgSO4 6H2 O), was determined as arnfunction of pH from nonequilibrium electrophoreticrnmobility measurements. Schoenite appears tornexhibit three charge reversals (CR) which can bernexplained based on surface hydrolysis reactions.rnThe flotation behavior of schoenite is furtherrnconsidered based on solution chemistry calculations,rnelectrophoretic mobility measurements, andrnmicroflotation results.