Evaporation Behaviors of Cu(In,Ga)Se₂ Semiconductor Compound via Pyrometallurgical Chlorination Process Utilizing Ammonium Chloride

Abstract

The chlorination process utilizing ammonium chloride as chlorination reagent has been employed for the recovery of elements from a promising photovoltaic semiconductor material, copper indium gallium diselenide, Cu(In,Ga)Se 2 , through vaporization of the chlorides of the elements. It was found that the chlorination took place by heating of the model sample in the presence of ammonium chloride. The influence of process parameters, such as oxygen partial pressure in the gas phase, the composition of ammonium chloride and the reaction temperature, has been investigated. The increase in the oxygen partial pressure resulted in the substantial increase in the recovery. The chlorides of indium and gallium deposited in the temperature zone around 400 K, while selenium chloride concentrated in the lower temperature zone below 320 K, for the reaction at 673 K. Copper was detected mostly in residue. At 1073 K, on the other hand, the evaporation of copper chloride was observed. These phenomena result from the difference in vapor pressure of metal chlorides.

Pyrometallurgical Recovery of Gallium from GaN Semiconductor through Chlorination Process Utilizing Ammonium Chloride

“…4 Recovery of gallium plotted against the composition of NH 4 Cl at the nitrogen ow rate of 100 mL/min. isfactorily in accordance with that of the chlorination reaction of CIGS 5) . The present result suggests that the complex formation does not play an important role, as it is not the case for the chlorination of GaN.…”

“…The present result shows that excess amount of NH 4 Cl is necessary for the suf cient evaporation of gallium chloride. However, the recovery of 70% could be achieved at the stoichiometric composition for the GaN chlorination, which was considerably higher than the reactions in our past study 5) , where only 40% of gallium recovery was achieved for the chlorination reaction of CIGS at over 10 times more amount of NH 4 Cl composition than the stoichiometric composition.…”

“…Spatial separation of the elements is one of the major advantages of the chlorination metallurgy. Our previous work on the chlorination of CIGS revealed that the gallium deposition took place close to that of indium, though the vapor pressures of gallium (III) chloride and indium (III) chloride are different from 3-4 orders of magnitude 5) . We deduced the complex formation of indium and gallium chlorides.…”

“…The chlorination reactions were carried out in a quartz horizontal reactor (inner diameter 26 mm, length 700 mm) heated in an electric furnace 5) . Schematic gure of the reactor is shown in Fig.…”

“…In our previous paper 5) , we reported the recovery process of elements from copper indium gallium diselenide, CIGS, through pyrometallurgical chlorination method utilizing ammonium chloride, NH 4 Cl. Hydrogen chloride and ammonia are formed in thermal decomposition of NH 4 Cl, the former of which is responsible for the chlorination of elements.…”