There are many applications of pressure leaching, mature technology of aluminum oxide extraction, nickel extraction from nickel sulfide ore and lateriate-nickel ore as well as zinc leaching especially from sphalerite. It is further prolonged to copper metallurgy, rare metal extraction like tungsten, molybdenum and precious metal recovery from anode slime.

Metalcess has been working on pressure leaching for years and accumulated rich engineering experience from zinc pressure leaching smelters. We are able to offer related service for zinc pressure leaching, copper pressure leaching and anode slime pressure leaching.

Zinc pressure leaching (ZPL) treats zinc concentrate directly in the autoclave where specific temperature and oxygen partial pressure is given to leach zinc and generates zinc sulfate solution while sulfur, lead and iron remain in the residue (leaching residue). The leaching residue is further treated with flotation and hot filtration to separate sulfur, lead sulfide residue and tailings. Part of iron may goes with zinc sulfate solution and the said solution has to be naturalized for iron removal by precipitation method. Zinc pressure leaching has a high leaching efficiency and is flexible to high iron sphalerite and lead-bearing zinc concentrate. Compared with conventional zinc leaching method, zinc pressure leaching requires no roasting and produces sulfur which is suitable for storage and transportation. 

Characteristics 

1.    Direct recovery of sulfur, easy in stocking, transportation and sales, superior to acid sulfuric.

2.    Adaptable to various material including low grade high iron zinc sulfide concentrate, lead-zinc concentrate, zinc ferrite and other smelting slag/leaching residue.

3.    Favorable to recover scatter metal. 

4.    Good flexibility to be integrated with existing roasting system to expand production capacity while using the existing facilities to a large extent.      

5.    Perfect match with goethite precipitation. Iron exists in the form of Fe²⁺ from oxygen pressure leaching. Goethite residue can be treated by flash roasting to make it suitable for iron-smelting instead of being disposed as solid waste.