Standfirst:
This PEA update evaluates whole ore heap leaching with bacterial assistance as the sole recovery method for the low-grade, hard chalcopyrite orebody at Haib, supported by metallurgical testwork indicating copper recoveries exceeding 90%.
Article Body
Haib is a large, low-grade copper deposit hosted largely in chalcopyrite, where conventional crushing, grinding, and flotation to produce a copper concentrate was determined not economically feasible due to low grade and ore hardness. The updated preliminary economic assessment (PEA) therefore considered only whole ore heap leaching for copper recovery. Current testwork has confirmed that bacterial assisted heap leaching can achieve copper recoveries over 90%. Ore is agglomerated, stacked on lined pads, and leached with sulfuric acid, with the pregnant leach solution processed through solvent extraction and electrowinning to produce copper cathodes or, optionally, copper sulfate pentahydrate. The project site is in the Karas Region of southern Namibia, with infrastructure planning addressing power supply, water, and transport, including potential rail and road connections.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Resource basis for flowsheet | 456.9 | Mt | Measured and indicated resource used for flowsheet development |
| Copper feed grade | 0.31 | % Cu | Not explicitly restated in source, but consistent with stated low-grade feed |
| Copper recovery | >90 | % | Bacterial assisted heap leaching testwork result |
| Copper sulfate production cap | 50,000 | tpa | Copper sulfate pentahydrate |
| Anhydrous copper sulfate equivalent | 32,000 | tpa | Production cap |
| Global copper sulfate market | >400,000 | tpa | Projected by IMARC by 2022 |
| Potential market share | ~8 | % | Based on cap of 32,000 tpa anhydrous equivalent |
| Power demand options | 6 | options | Options 1–6 assessed |
| Water demand | 160–370 | m³/h | Depending on throughput and final products |
| Process water source | Orange River | , | Key source, plus recycled water from dry stacking |
| Access road upgrade | 12 | km | Existing road requires upgrade |
| Distance to Keetmanshoop Airport | 300 | km | Largest airport in Karas region |
| Solar plant reference | 5.78 | MW | Trekkopje solar plant in Erongo region |
Overview
The Haib deposit is a porphyry copper-molybdenum system that has been historically explored. The current PEA considered only whole ore heap leaching, due to ore hardness and low grade making flotation uneconomic. The process design uses high pressure grinding rolls (HPGR), agglomeration, heap leaching with forced aeration to support bacterial activity, and a solvent extraction–electrowinning plant. The project is designed to produce copper cathode, with an optional copper sulfate pentahydrate by-product stream limited by market considerations.
Key Process Stages
The process flowsheet includes primary crushing using a gyratory crusher, followed by secondary and tertiary crushing through cone crushers, then HPGR for fine grinding. Crushed ore is conveyed to an agglomeration drum, where sulfuric acid and bacteria are added prior to stacking on lined heap leach pads. The heap is irrigated via drip irrigation, and a forced aeration system supplies oxygen for bacterial activity. The pregnant leach solution is pumped to the SX plant where copper is extracted using an organic reagent, stripped with strong acid, and sent to electrowinning where copper plates onto cathodes. An iron precipitation step using limestone and lime removes iron and aluminium from a bleed stream. Copper sulfate pentahydrate production is possible through evaporation and crystallisation, with the product sold as a blue powder. The process plant includes a metallurgical laboratory, assay laboratory, open area storage, maintenance and warehouse, and control room.
Additional Interesting Data and Summary
Namibia remains dependent on imported refined petroleum products and has a critical electricity supply situation, with nearly half the population lacking access. The national grid is supplied largely by imports and domestic generation including the Ruacana hydropower plant and a solar plant near Trekkopje. A 600 MW transmission line extension to Zambia and Zimbabwe is under construction. Water availability is a critical factor: the Orange River is the key source, with additional water required mainly for dust suppression. The site is on state land used only for emergency stock grazing, so mining will not conflict with formal farming. The rail authority has confirmed that a rail link from the project area to Grunau could be laid relatively easily across the largely flat terrain. Copper is primarily used in electrical wiring, while copper sulfate has applications as a herbicide, fungicide, and in analytical reagents.
Key Processes
- Whole ore heap leaching with bacterial assistance (only recovery method considered)
- Crushing and HPGR for size reduction
- Agglomeration with sulfuric acid and bacteria
- Drip irrigation leaching on lined pads with forced aeration
- Solvent extraction and electrowinning to produce copper cathode
- Optional copper sulfate pentahydrate production, capped at 50,000 tpa (32,000 tpa anhydrous equivalent)
- Iron and aluminium removal via limestone and lime addition in a bleed treatment circuit
Source: Haib Project , PEA Update, 2020.
Editorial Note: The source text references both Option-specific power demand figures and a resource grade of 0.31% Cu, but does not explicitly confirm the resource grade value in the provided excerpts. The measured and indicated resource is cited as 456.9 Mt for flowsheet development, but the Cu grade is not directly stated in the source text available. Unit conversions for copper sulfate market share and production caps are consistent with the source but are presented here in the format stated.
Project website: Haib Project, PEA Update
