Method For Extracting Potassium Nitrate From Nitrate Soil

The main principle of extracting potassium nitrate from the soil is to replace the sodium ions in the soil with potassium ions in the plant ash to form potassium nitrate. In addition, the carbonate ions and sulfate ions in the ash are combined with the calcium and magnesium ions in the soil to form a poorly soluble salt and precipitate, thereby removing impurities such as calcium and magnesium. The main reaction is
Ca(NO?)?+K?SO?=2KNO?+CaSO?↓
Ca(NO?)?+K?CO?=2KNO?+CaCO?↓
Mg(NO?)?+K?CO?=2KNO?+MgCO?↓


     The nitrate soil itself also contains potassium nitrate. Finally, the difference in solubility of various salts is used to control the temperature and concentration, so that potassium nitrate crystallizes from the mixture.