Zinc Oxide Experience

Technology Development
While SGS Minerals Services has carried out hundreds of programs to process sulphide ores, we have also performed significant process development work for the beneficiation of zinc and lead oxide ores. This has led to operational success in many areas.

FLOTATION PROCESS DEVELOPMENT

• New flotation collector based on amine-modified xanthate successfully applied to float oxide zinc ores from Ireland, British Columbia, Yukon (Canada) and Peru (Accha).
• New flotation collector based on an ester modified mixture of xanthate and mercaptans successfully used to float calamine (Zn silicate).
• New gangue depressants for depression of dolomite and iron oxide gangue commonly found with the oxide zinc lead ores. These depressants are a) either crosslinked oxidized starches or b) low molecular weight acrylic acids modified with vinyl sulphuric acid.

Practical Applications

• Irish Base Metal Consortium, Ireland- two zinc oxide deposits.
• Grupo Mexico: oxide Cu/Pb/Zn ore.
• Phelps Dodge: oxide Pb-Zn ore from Spain.
• Breakwater Resources: beneficiation of Zn oxide ore from Yukon, Canada.
• Savage Resources, Australia: beneficiation of Zn oxide ore from Accha, Peru
• Teckcominco: beneficiation of Pb, Zn ore from British Columbia.

HYDROMETALLURGY PROCESS DEVELOPMENT
In addition to test programs concerning the conventional zinc hydrometallurgical processes (roast-leach-electrowin, Direct pressure or atmospheric leach of sphalerite), SGS Minerals Services has undertaken bench and pilot-scale process testwork to support process development for oxide and silicate zinc ores. We also have experience with the recovery of zinc from secondary sources including electric arc furnace dust.

Together with our expertise in solvent exchange-electrowinning technologies that are now reaching commercial application, SGS Minerals Services has participated in the development and testing of unconventional technologies such as the ferric chloride process.

Practical Applications Zinc oxide ores, dusts and residues

• Leaching zinc oxide ores & concentrates with sulphuric acid (ZincOx, others)
• Leaching zinc carbonate/silicate ore with ammonia, followed by ammonia regeneration and ZnO precipitation (Bongara, Peru, Crown Resources)
• Leaching of zinc oxide calcines from ZnS roasters Heap leaching of an oxidized Cu-Zn ore, followed by Cu solvent extraction and Zn solvent extraction (Sanyati, Reunion Mining)
• Sulphuric acid leach of various zinc dusts
• Pressure leaching of zinc from jarosite residues (Kidd Creek)
• Chloride leaching of EAF dust (NIST process)
• Caustic leach of galvanized scrap followed by caustic regeneration and zinc precipitation (patent applied for)
• Chloride pyrohydrolysis of jarosites and EAF dust  

Leaching of zinc sulphide

• Leaching with ferric (sulphate and chloride) and solution purification to produce high quality zinc oxide
• Leaching of bulk concentrate (Zn-Pb-Cu) with ferric chloride, iron & zinc solvent extraction producing electrowon zinc (ferric chloride process)
• Pressure leaching of ZnS concentrate and Zn-Pb-Cu bulk concentrate  

Solution Purification and Recovery Experience

• Solvent extraction and electrowinning of zinc from Co/Ni solutions (sulphate, chloride)(Boleo project), solvent extraction of iron from Fe/Zn solutions (sulphate, chloride)
• Solvent extraction of zinc from Ni-Zn solutions (mixed sulphate- chloride) (Polymet) Ion exchange to purify/concentrate zinc from brine leach liquors, IX removal of zinc from nickel EW electrolyte
• Zinc sulphide precipitation from various liquors
• Precipitation of basic zinc sulphate (Anglo American, ZincOx)
• Extractants investigated: MEHPA, D2EHPA, CYANEX 272, TBP
• Selective manganese precipitation using SO2-O2 oxidation

DIVERSE OTHER TECHNOLOGIES

• Sulphate roasting/leaching of copper-zinc concentrates
• Production of pure ZnO from chloride leach
• Production of pure ZnO from chloride leach of EAF dust
• Electrowon Zn from chloride liquor