Chemistry Forum

Hi,

I am currently doing a literature review and simulation of palladium recovery . I have found book (Extractive metallurgy of nickel, cobalt and platinum group metals from Crundwell, Frank.)

I will be implementing an ignition unit where palladium will be recovered as pure metal while producing NH₄Cl and HCl waste gases from thermal decomposition. This reaction occurs around 1000 celcius due to amonnia chloride sublimation temperature being around 500C.

The ignition reaction will be as follow: 3(NH₄)₂PdCl₆(s) = 3Pd(s) +2 NH₄Cl(g)+16HCl(g) + 2N₂(g)

I wanted to collect this waste gas and treat it by wet scrubbing. My main goal is to turn the waste gas into NH₄Cl(aq) without any additional species so that I can recycle it to my another process unit. From my inverstigation from patents and books for HCl(g), wet scrubbing with NH₄OH(aq) or NH₃ gas is an option according to a russian patent. I opted for NH₄OH as it more available in industrial processes. My initial hypothesis is that waste gas NH₄Cl(g) wont be reactinng with NH₄OH(aq) but only turn into liquid by absorption, thus I have derived the following equation, and wanted to ask forum users if they think this reaction is feasible as well used in industrial wet scrubbing processes for HCl and NH₄Cl waste gases.


The proposed wet scrubbing reaction:

NH₄Cl(g)+ HCl(g) + NH₄OH(aq) = 2NH₄Cl(g)+H₂O

Alternatively the reaction with steps:

NH₄Cl(g) = NH₄(+aq) + Cl(-aq)
HCl(g) + NH₄OH(aq) = Cl(-aq) + NH₄(+aq) + H₂O(l)
NH₄(+aq) + Cl(-aq) = NH₄Cl(aq)

I'm conducting a literature review and simulation on palladium recovery, inspired by Crundwell's book on extractive metallurgy. My focus is on implementing an ignition unit to recover palladium as pure metal, alongside treating waste gases through wet scrubbing. I propose a wet scrubbing reaction converting NH₄Cl(g) and HCl(g) into NH₄Cl(aq) using NH₄OH(aq), aiming for efficient waste gas treatment and recycling.