Method for preparing high purity silver nitrate from crude silver powder

The invention relates to a method for preparing high purity silver nitrate from crude silver powder. The method comprises that excess crude silver powder and nitric acid subjected to distillation purification undergo a continuous reaction at a temperature of 30-50 DEG C to produce silver nitrate solution with pH greater than or equal to 4, wherein a refined nitric acid concentration is controlled in a range of 65-75% and a mole ratio of silver to nitric acid is 1: 0.65-0.85. The electrolysis crude silver powder is directly dissolved by nitric acid so that a silver nitrate solution is obtained, the silver nitrate solution is directly added into a high purity water adjustment system with pH greater than or equal to 5, the mixed solution undergoes a hydrolysis reaction, base metal impurities in the system are removed, the filtrate subjected to precision filtration is subjected to evaporation and crystallization, and the crystals are dried to form high purity silver nitrate products.