First dissolve the crude salt in water,

and then filter (pay attention to a paste two low three leaning),

Then add an excess of BaCl2 solution, to remove Na2SO4: BaCl2 + Na2SO4 == BaSO4↓ + 2NaCl

Then add an excess of NaOH solution, to remove MgCl2: MgCl2+2NaOH==Mg(OH)2↓+2NaCl

Then add excess Na2CO3 solution to remove CaCl2 and BaCl2 (two reaction equation): Na2CO3+CaCl2==CaCO3↓+2NaCl

Na2CO3+BaCl2==BaCO3↓+2NaCl

BaCO3↓+2NaCl

Na2CO3+BaCl2==BaCO3↓+2NaCl. 2NaCl

Filter

Finally, add appropriate amount of hydrochloric acid drops to exactly no longer produce gas, remove NaOH and Na2CO3 (you can use PH paper to detect the acidity and alkalinity of the two reaction equations): HCl + NaOH = = NaCl + H2O

2HCl + Na2CO3 = = = 2NaCl + H2O + CO2↑< /p>

Evaporate the solution to precipitate NaCl crystals.