A hydrometallurgical process for the recovery of terbium from fluorescent lamps. Experimental design, optimization of acid leaching process and process analysis

Terbium and rare earth recovery from fluorescent powder of exausted lamps by acid leaching with hydrochloridic was the objective of this study.In order to investigaste the factors affecting leaching a series of experimens was performend in according a full factorial plan with four variables and two levels. The fators studied were temperature, concentration acid, pulp density and leachin time. The results showed that temperature and pulp density were significant with positive and negative effect, respectively. The empirical mathematical model deduced by experimental data demonstrate that tebium content was completely dissolved under the following conditions: 90 °C, "M hydrochloridic acid and 5% pulp density; while when the pulp density was 15% an extraction of 83% could be obtained at 90 °C and 5% hydrochloridic acid. The mass balance of the process was calculated: from 1 ton of of initial powder it was possible to obtain 160 kg of a concentrate of rare earths having purity of 99%. The main rare earths elements in the final product was yttrium oxide (86.43%) following by cerium oxide (4.11%), lanthanum oxide (3.18%), europiumoxide (3.08%) and terbium oxide (2.20%).