Process

Although zinc mining focusses mainly on zinc sulphide deposits, non-sulphide zinc deposits still have an important economical potential. Known methods for processing non-sulphide zinc ores include pyro-metallurgical methods, flotation and leaching. Each of these processes has its drawbacks. The Waelz pyrometallurgical process is the most common method. It is also the standard process for recycling zinc-containing secondary materials like electric arc furnace dust (EAFD). Its final products are “washed Waelz oxides” which are sold to zinc smelters. Disadvantages of the Waelz process are its high energy consumption and high CO2 emissions.

BelZinc has now developed a highly efficient hydrometallurgical method for producing a high-grade zinc oxide from non-sulphide zinc ores and secondary materials. The process does not have the drawbacks of other methods. Compared with washed Waelz oxides used by zinc smelters, BelZinc’s oxide has a higher Zn content and an extremely low content of Cl–, F– and other deleterious elements.

For zinc smelters, using BelZinc oxide has several operational advantages, increases efficiency and reduces the cost per ton of zinc metal produced. BelZinc is now evaluating options to valorise its technology, including the acquisition of non-sulphide zinc ore deposits and secondary zinc-containing materials, like EAFD and zinc containing slag. BelZinc has applied for all the necessary patents to protect its intellectual property.

To summarize, BelZinc’s hydrometallurgical process has several advantages, compared to Waelz and other technologies:

  • Lower cost per ton zinc produced: both lower CAPEX and OPEX
  • Much lower CO2 emissions (75-85% reduction)
  • Much lower energy consumption
  • Lower consumption of reagents
  • Zinc recovery >80%
  • Less sensitive to the feed composition (low impact of feed Zn grade and impurities on the final product quality and on CAPEX)
  • Higher quality end-products, thus lowering bleed requirements in the leaching circuit
    • Significantly lower content of Cl–, F– and other deleterious elements)
    • Lower iron residue weight and toxicity
  • Does not require to be roasted, thus the possibility for roaster capacity debottlenecking

Applications

Ideal for developing non-sulphide Zn deposits

90% of the world’s zinc metal is produced from zinc sulphide concentrates and most zinc mining activity is focussed on zinc sulphide deposits. Due to this focus on sulphide deposits, zinc oxide (or non-sulphide zinc) deposits are undervalued or overlooked. BelZinc’s process is developed for processing these non-sulphide zinc ores. The lower CAPEX and OPEX of BelZinc’s process also allow to mine and process smaller and lower grade non-sulphide zinc deposits.
BelZinc can produce a ZnO product containing >96% ZnO (>77% Zn) from most non-sulphide Zn deposits.

Examples of non-sulphide zinc deposits:

  • Lone Mountain (US): 3,25 million tonnes @ 7.57% Zn
  • Bongara (Peru): 2,94 million tonnes @ 14.4% Zn
  • Jabali (Yemen): 12,60 million tonnes @ 8.9% Zn

Ideal for zinc recycling

Lower grade zinc-containing secondary materials, like Pb-smelter slag and lower grade EAFD (<15% Zn), are often ignored by the recycling industry. BelZinc can process these lower grade secondary materials to produce zinc oxide with >96% ZnO (>77% Zn). BelZinc’s process is relatively insensitive to impurities in the feed material and can produce a high grade ZnO product with low impurities from most Zn containing secondary materials.

Zn-containing secondary materials:

  • Mount Isa Pb-slag (Australia): 20-25m tonnes @ 11% Zn
  • Tsumeb Pb-slag (Nambia): 2m tonnes @ 9% Zn
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