Method for recovering lithium from low-context extraction tailwater and recycling extraction tailwater
A method for recovering lithium from low-content extraction tailwater and recycling extraction tailwater is provided. The disclosure is characterized that recovery of lithium from lithium-containing extraction tailwater is achieved by adding calcium to remove fluorine, carrying out evaporative crystallization and precipitating lithium salts. Recycle of extraction tailwater is achieved by adopting the following steps: in the lithium-containing extraction tailwater, adding calcium to remove fluorine, carrying out evaporative crystallization, recovering condensate water, precipitating a lithium salt and recycling mother liquor. According to the disclosure, lithium is recovered from low-content extraction tailwater via enrichment and sodium sulfate and distilled water therein are incidentally recovered, so that zero release of battery waste treatment wastewater is achieved.
1. A method for recovering lithium from low-content extraction tailwater, comprising:
adding calcium into a first extraction tailwater which is lithium-containing to remove fluorine to obtain a second extraction tailwater;
carrying out evaporative crystallization on the second extraction tailwater to obtain a third extraction tailwater;
precipitating lithium salts from the third extraction tailwater to obtain a fourth extraction tailwater which is non-lithium containing; and
recycling the fourth extraction tailwater.
2. The method for recovering lithium from low-content extraction tailwater according to claim 1 , comprising the following steps:
adding calcium to remove fluorine in the first extraction tailwater which is lithium-containing to obtain the second extraction tailwater;
carrying out evaporative crystallization on the second extraction tailwater to obtain the third extraction tailwater;
recovering condensate water;
precipitating the lithium salts from the third extraction tailwater to obtain the fourth extraction tailwater; and
recycling the fourth extraction tailwater.
3. The method for recovering lithium from low-content extraction tailwater-according to claim 1 , wherein, after evaporative crystallization, removing impurities from the third extraction tailwater.
4. The method for recovering lithium from low-content extraction tailwater according to claim 1 , wherein, the step of adding calcium to remove fluorine comprises the following steps:
adding sodium hydroxide to the first extraction tailwater in which cobalt, nickel and manganese is extracted to regulate a pH value to 8-13;
adding a calcium-containing material so that a F/Ca ion mole is 1/(1-5);
reacting for 0.5-4 h;
filtering and washing, wherein filtrate is evaporation stock solution.
5. The method for recovering lithium from low-content extraction tailwater according to claim 1 , wherein, the evaporative crystallization is realized by the following steps:
concentrating the second extraction tailwater-to 1/(4-16) by evaporating the second extraction tailwater and crystallizing sodium sulfate in the second extraction tailwater so that a content of lithium in third extraction tailwater reaches 5-30 g/L, and
recovering the condensate water.
6. The method for recovering lithium from low-content extraction tailwater according to claim 3 , wherein, the step of removing impurities comprises the following steps:
regulating the pH value of the third extraction tailwater to 11-14 with alkali to remove impurities including calcium and magnesium.
7. The method for recovering lithium from low-content extraction tailwater according to claim 1 , wherein, the step of precipitating the lithium salts comprises the following steps:
preparing a saturated carbonate solution with the condensate water;
heating the third extraction tailwater;
adding the saturated carbonate solution to the third extraction tailwater which is heated so that a lithium ion is precipitated as lithium carbonate for recovery.
8. The method for recovering lithium from low-content extraction tailwater according to claim 2 , wherein, the step of recycling the fourth extraction tailwater comprises the following steps:
regulating the pH value of the fourth extraction tailwater to 2.5-6 to remove carbonate radicals therein, and
returning the fourth extraction tailwater back to an evaporation stock solution tank.
9. The method for recovering lithium from low-content extraction tailwater-according to claim 8 , wherein, the pH value of the fourth extraction tailwater is regulated to 3.0-5.5 with acid.