Hydrometallurgy Of Zinc Leach Residue Gallium Recovery Process And Mechanism

In order to recover gallium in zinc-leaching residues produced during zinc hydrometallurgy process effectively, the process of cold-bonded agglomeration ?coal-based direct reduction梞agnetic separation was developed to enrich gallium, and the enriching behaviors and separation mechanisms of gallium had been studied systematically by means of electron microscopy, SEM and energy sepectrograph ect.The results show: zinc-leaching residues are characteristized by fine, porous and low apparent density, it is a material of worse briquettability. When agglomerated directly, the strength of zinc-leaching residues cold-bonded briquette is low, and can not meet the requirement of reduction roasting. However, the strength of zinc residue briquette improves obviously with the presence of C-5 binder. The impact strength of 54.2 X 105Pa and drop strength of 19.2 times/1 m of cold-bonded zinc residues briquette were obtained respectively under the conditions of 5% C-5 binder, pressure 255 X 105Pa and moisture 17.5%.The investigations of agglomeration methods show pelleting is a suitable method for zinc residues agglomeration, and both disc pellitizer and cylindrical pelletizer can be used as pelleting machine. It is shown that a suitable pelleting time is 10min~15min, moisture is about 21%. The pretreatment with forced mixture is in favor of the agglomeration of zinc-leaching residues, and the suitable mixture time is about 3min.Using rotating tube equipment, the coal-based direct reduction of the zinc-leaching residue briquette was carried out. The results of 2164g/t Ga in magnetic product (DRI or direct reduction iron) and Ga recovery of 92.42% during the magnetic separation were obtained when the residue bearing gallium 527g/t was reduced with coal at 1100癈 for 120min~150min. And when the residue bearing gallium 436g/t was reduced under the same conditions, a product of DRI with 1696g/t Ga and a Ga recovery of 89.42% was obtained respectively. Using a simulation equipment of rotary kiln, the results of concentration of Ga above 1600g/t in magnetic product and recovery of Ga over 82% can be obtained when the residuce containing 436g/t Ga was reduced at HOO'C for 90min~ 120min. In addition, the volatization of zinc reaches 98.42% during the reduction.The enriching behaviors of Ga and its separation mechanisms were studied systematically by using SEM, electron microscopy and energy spectrograph. It was shown that the metallic iron is the main carrier of Ga, the gallium is of an affinity to the metallic iron obviously. As a result, the enrichment of Ga in metallic iorn is the basis of new process.