Process of smelting waste catalyst into palladium

Process of smelting waste catalyst into palladium
      1. Raw material pretreatment
          (Dissolution and conversion: Waste catalyst needs to be smelted or

      acid-leached to convert into chloropalladic acid (H₂PdCl₄) solution.

     2. Oxidation and precipitation:

          Reaction formula: Pd + 4HNO₃ + 6HCl → H₂PdCl₆ + 4NO₂↑ + 4H₂O

Step 1 – Oxidation:

Operators first pump chlorine gas or inject hydrogen peroxide into the

chloropalladic acid solution containing Pd²⁺, actively driving the oxidation

of Pd²⁺ to Pd⁴⁺.

Step 2 – Precipitation:

Subsequently, they add an excess of 10-15% ammonium chloride (NH₄Cl)

to the solution, triggering the formation of a deep red crystalline ammonium

chloropalladate ((NH₄)₂PdCl₆) precipitate. This reaction selectively traps

base metal impurities (e.g., Cu, Fe), enabling their physical separation via filtration.

Step 3 – Redox Cycling:

Next, the team boils the collected precipitate in a controlled reactor, reducing it

to soluble ammonium chloropalladate ((NH₄)₂PdCl₄). To further enhance purity,

they reoxidize the solution through additional chlorine gas exposure, completing

a redox purification cycle.

     3. Ammonia complexation:

         Heat the chloropalladic acid solution to 80°C, add ammonia water to adjust the pH

      to 8-9, generate soluble dichlorotetraamminepalladium ([Pd(NH₃)₄]Cl₂), which can

     separate the impurities. Therefore, this process requires multiple repetitions to achieve

     purification.

     4. Calcination-hydrogen reduction:

         The calcination process decomposes the purified palladium salt into palladium oxide (PdO)

         From waste to wealth: Through cutting-edge hydrometallurgy paired with smart reactors,

    spent catalysts are transformed into 99.99% pure palladium. Key innovations include

   (1) precision impurity removal via redox cycling;

   (2) AI-controlled pH adjustment for ammonia complexation;

   (3) energy-efficient hydrogen reduction. Together, these advancements slash processing

     Process of smelting waste catalyst into palladium