Overview

Blister Copper via Leaching & Smelting

United Metals produces blister copper (≥98% Cu) through an integrated leaching and smelting process at its Zimbabwe operations, converting copper-bearing oxide ores and secondary feed materials into intermediate-grade copper for downstream anode refinery and industrial applications. The production route yields copper cement as a primary by-product, which feeds directly into the smelting furnace to maximise copper recovery from the leach circuit.

The name "blister" derives from the characteristic surface of the solidified metal — gas bubbles trapped during casting create small blisters on the anode's surface as molten copper solidifies. These large cast anode plates, weighing approximately 300 kg each, represent a key intermediate in the global copper value chain, sitting between concentrate and fully refined cathode, and are traded widely as smelter feedstock by anode refineries across Asia, Europe, and the Middle East.

With a committed monthly production capacity of 500 metric tons from Zimbabwe, United Metals offers buyers a consistent, documented, and competitively priced source of blister copper with full chain-of-custody documentation, origin certification, and per-lot assay reports — supported by our established Southern African export infrastructure.

Production Method

The Leaching & Smelting Process

The leaching and pyrometallurgical smelting route is an integrated hydrometallurgical-pyrometallurgical process that first dissolves copper from oxide ores using dilute sulfuric acid, recovers it as solid copper cement by iron cementation, then smelts the cement in a reverberatory furnace to produce blister copper anodes. This route is particularly effective for oxide ore bodies and secondary copper-bearing materials where SX/EW electrowinning infrastructure is not available or cost-justified.

01
CuO + H₂SO₄ → CuSO₄ + H₂O
Stage One
Acid Leaching
Crushed oxide-copper ore is irrigated with dilute sulfuric acid, dissolving copper into a Pregnant Leach Solution (PLS). Heap or vat leaching is deployed depending on ore grade and particle size. The copper sulfate PLS is routed forward to the cementation circuit for metallic copper recovery.
H₂SO₄ irrigation · Heap / vat · PLS to cementation
02
CuSO₄ + Fe → Cu⁰ + FeSO₄
Stage Two
Cementation
The PLS is contacted with iron scrap in cementation launders, where iron displaces copper through a galvanic exchange reaction. Metallic copper precipitates as copper cement (80–90% Cu). The cement is thickened, filtered, and dried before stockpiling as furnace feed. This process is the source of United Metals' copper cement by-product.
Fe displacement · 80–90% Cu cement · Filtered & dried
03
Cu cement + flux → Blister Cu (≥98%)
Stage Three
Smelting & Casting
Copper cement and flux are charged into a reverberatory smelting furnace at 1,100–1,300°C. Impurities partition into the slag phase; molten blister copper is tapped periodically and cast into large anode-form slabs (~300 kg each). Gas evolution during solidification produces the characteristic blister surface. Slabs are air-cooled and stacked for shipment.
1,100–1,300°C · ≥98% Cu · ~300 kg anode slabs
1,300 °C
Reverb Furnace Peak Temp
98 % Min Cu
Blister Output Purity
500 MT/mo
Zimbabwe Monthly Capacity
80 % Cu
Cu Cement By-product Grade
Why Blister Copper

Advantages of the Product

Blister copper occupies a strategically critical position in the copper value chain — bridging concentrate and fully refined cathode. For buyers operating anode refineries, alloying operations, or fire-refining plants, blister copper delivers compelling value through its purity, flexibility, and cost advantages over upstream alternatives.

Technical & Product
Commercial & Supply
High Impurity Rejection via Smelting
The reverberatory smelting stage drives volatile and slag-forming impurities — arsenic, antimony, lead, and bismuth — into the slag phase, yielding blister copper significantly cleaner than the cement feed chemistry would suggest. High-temperature flux chemistry enables precise impurity partition control.
One Step from Cathode Grade
At ≥98% Cu, blister copper requires only a single additional fire-refining and electrorefining step to reach 99.99% Cu-CATH-1 cathode grade. Anode refineries can process blister with minimal furnace adjustments, compressing the distance from intermediate product to LME-deliverable copper.
Copper Cement Integration
Copper cement — produced as a by-product of the acid leaching circuit — feeds directly into the reverberatory furnace, forming an integrated and self-reinforcing production loop. The cement circuit converts chemical energy in dissolved copper directly to solid metal, reducing energy demand versus wet-concentrate smelting.
Low Sulphur Burden
Unlike sulphide concentrates — which require extensive SO₂ management — cement copper feed carries a very low sulphur content. This significantly simplifies gas-handling requirements at the smelter, reducing environmental compliance infrastructure costs and enabling simpler off-gas treatment systems.
Attractive Discount to LME Cathode
Blister copper trades at a 2–4% discount to LME Grade A cathode, reflecting its intermediate purity. For buyers operating in-house anode refineries, this discount represents a direct margin capture opportunity — purchasing below cathode price and upgrading to 99.99% Cu through internal electrorefining.
Flexible Downstream Applications
Suitable as feed for anode furnaces, electrolytic refineries, and brass or bronze alloying operations where sub-cathode purity is acceptable. The ≥98% Cu content meets the requirements of the majority of secondary smelter blending and alloy casting applications without further refining.
Eliminates TC/RC Exposure
By producing blister copper directly rather than selling concentrate to a third-party smelter, United Metals eliminates Treatment Charge (TC) and Refining Charge (RC) exposure entirely. The copper value is captured at blister price, bypassing the benchmark negotiation cycle that erodes concentrate producer margins.
Consistent 500 MT Monthly Supply
A committed monthly production of 500 MT from our Zimbabwe facility provides buyers with reliable, schedule-able volume for supply-chain planning. Spot, quarterly, and annual off-take structures are available. All shipments include per-lot assay certificates, weight certificates, and origin documentation.
Full Documentation Package
Every shipment is accompanied by a complete documentation set: certificate of origin, fire assay report (Cu, Pb, As, Sb, Bi), certified weight ticket, bill of lading, and OECD conflict-mineral declaration — satisfying the compliance requirements of European and Asian smelter procurement programmes.
Dual Revenue Stream — Cement & Blister
The integrated leach-cement-smelt circuit generates both blister copper and copper cement as saleable products. Copper cement (80–90% Cu) can be marketed independently to secondary smelters when blister production is committed, providing production flexibility and an additional revenue layer within the same circuit.
Physical Format

Anode Slab Configuration & Dimensions

United Metals' copper blisters are produced in anode-form slab castings, typically weighing approximately 300 kg each, cast in standard reverberatory furnace moulds. Slabs are air-cooled on casting beds, stacked on timber bearers, and banded in lots for FCL container or bulk break-cargo shipment.

Top View — Base Layer (2×2 slab arrangement)
Anode
~900mm
Anode
~900mm
Anode
~900mm
Anode
~900mm
Stack Elevation — 3 Layers
L3
L2
L1
12 slabs · ~3,600 kg ±5% total payload per stack
Anode Slab Configuration Data
900mm
Slab Dimensions (typical)
~900 × 700 × 40 mm per blister anode slab. Cast in standard reverberatory furnace moulds. Dimensions may vary ±5% subject to casting conditions and furnace configuration.
300kg
Slab Weight (approximate)
~300 kg per anode slab ±5%. Actual weights certified per lot by calibrated scale ticket issued at point of dispatch from Zimbabwe facility.
12 sl
Slabs per Stack (standard config)
12 slabs in a 3-layer, 4-slab-per-layer arrangement on timber bearers. Steel-banded for container loading in 20ft or 40ft FCL. Break-bulk cargo available for larger volumes.
3.6MT
Stack Payload (12-slab config)
~3,600 kg ±5% per 12-slab stack. Standard 20ft container accommodates 5–6 stacks (18–22 MT). Custom stacking configurations available to match buyer logistics requirements.
Production Origins

Sourced from Zimbabwe

Copper blister production is exclusively anchored to United Metals' Zimbabwe operations, where copper oxide ore bodies and secondary feed materials supply an integrated leach-cement-smelt circuit. Zimbabwe's mining regulatory framework and access to Southern African export corridors supports reliable, documented shipment to global markets.

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Africa — Southern · Primary
Zimbabwe
Primary production and smelting location. Integrated leach-cementation-reverberatory furnace circuit. Copper oxide ore sourced from local mining operations. Monthly output: 500 MT blister copper.
⚗️
Circuit Co-product
Cu Cement
Copper cement (80–90% Cu) manufactured on-site via iron cementation of leach PLS. Serves as primary furnace feedstock for blister production and is available independently for sale to secondary smelters.
🚢
Export Corridor
Beira Port
Primary export gateway via Beira, Mozambique — the nearest deep-water container port to Zimbabwe's central copper-producing region. Direct FCL and break-bulk shipment to Asia, Europe, and the Middle East.
🇮🇳
Asia — Distribution Hub
India
Regional distribution and documentation support hub. Indian Ocean routing enables competitive freight to South and Southeast Asian anode refinery markets. Full export and customs documentation managed from our India office.
Market Intelligence

Market Insight

The blister copper market is driven by capacity expansions at anode refineries across Asia — particularly China and India — where integrated copper producers seek flexible semi-refined feedstock to complement concentrate supply chains. Sub-Saharan Africa is emerging as a key supplier of intermediate-grade copper materials to these growth markets.

Global Refined Copper Demand · 2024
26M MT
Estimated global refined copper demand, with blister and anode-form copper forming a significant share of smelter feedstock traded internationally between producing and refining countries.
ICSG Copper Bulletin · 2024
Blister Discount to LME Cathode
2–4%
Typical blister copper discount to LME Grade A cathode spot price, representing a direct value-add opportunity for anode refineries with in-house electrorefining capacity to upgrade blister to 99.99% Cu.
Market Pricing · Indicative Range
Sub-Saharan Africa Cu Output Growth
+12% CAGR
Sub-Saharan African copper output growth trajectory, with Zimbabwe and the Copperbelt region contributing meaningfully to global supply — and increasingly to intermediate-grade copper trade flows targeting Asian markets.
African Development Bank · 2024

Our Promise

At United Metals, we are committed to delivering consistent, documented, and competitively priced blister copper from our Zimbabwe operations — backed by a fully integrated leach-cement-smelt production circuit and a team with deep expertise in Southern African base metal export logistics.

Partner with United Metals — your trusted source for intermediate-grade copper from Zimbabwe. Contact us today to explore spot supply, term off-take agreements, and custom delivery schedules tailored to your refinery or industrial production requirements.

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