Study On Natural And Freezing Evaporation Of Yiliping Brine

The study on evaporation of Yiliping salt lake will make great contribution to mastering the minerals precipitation regular of potassium, lithium, boron in salt lake.Yiliping lake whose concentration of sulfate radical is not enough to produce directly potassium sulfate contains too sulfate radical to apply to existing mature potassium chloride production technique immediately. Therefore, in order to match the brine with the potassium chloride production technique, the study managed to crystalize the sulfate radical by magnesium sulfate ect. in advance through freezing condition,which would transform the chemical type of brine from sulfate type to chloride type by decreasing the concentration of sulfate radicals in the raw brine.(1) The simulated evaporation and natural evaporation have been conducted in field and laboratory respectively. The evaporation path of simulated evaporation is basically in conformity with the meta-stable diagram of Na+、K+、Mg2+//Cl-、SO42-—H2O quinary system at 25℃. Meanwhile, a great quantity of Kainite salts have been sampled during the natural evaporation in field, which prove the necessity of freezing mirabilite techniques.(2) Pilot study of optimal freezing condition was conducted under different brine density, freezing temperature and time. It increased as the temperature down as well as the density increased. When the concentration of sulfate radicals decreased to about 1/3 of that in raw brine, it would stop falling continuously. Meanwhile the speed of desulfurization would reduce dramatically as the mass of brine increased.(3) The simulated natural evaporation on Yiliping salt lake brine pretreated by freezing at-15 ℃ has been conducted in laboratory. The evaporation behavior of liquid point could be in conformity with the Na+ 、K+、Mg2+//Cl- —H2O quaternary system at 25 ℃, which means that the chemical type of magnesium sulfate sub-type brine can be converted from quinary to quaternary by freezing process.