Walk into any electroplating workshop or electrolytic metallurgy plant, and you will find a type of metal plate
silently fulfilling a core mission within the massive electrolytic cells—these are the anode plates. When current
flows through the electrolyte, oxidation reactions occur on the surface of the anode plates, continuously dissolving
metal ions to provide the “raw material” for the formation of cathode products. Without efficient anode plates,
the entire production process would grind to a halt.
Why is the selection of anode plates so critical?
Purity determines quality: Trace impurities such as lead and iron in anode plates can dissolve into the electrolyte
and ultimately form pits, nodules, or brittle layers on the cathode product. A large copper foil manufacturer once
suffered significant losses when an entire batch of high-end electronic copper foil was scrapped due to pinholes
caused by excessive impurities in the anodes.
Uniform dissolution ensures efficiency: An ideal anode plate should dissolve uniformly across its entire surface. If
localized overconsumption or passivation occurs, it not only reduces current efficiency and increases energy
consumption but also causes an imbalance in metal ion concentrations in the electrolyte. A zinc smelting company
improved current efficiency by 3.5% and saved millions of kilowatt-hours annually by optimizing anode
composition and process.
Structural strength supports production: In large electrolytic cells, a single anode plate can weigh hundreds of kilograms.
Under high-temperature, strong acid (or strong alkali) conditions, sufficient mechanical strength and deformation
resistance are critical. Once deformation occurs, uneven electrode spacing can cause short circuits or abnormal
current distribution.
Breaking through bottlenecks: The cutting-edge evolution of anode
plate materials and processes
The Rise of Specialized Alloys:
Lead-Based Alloy Innovations: Traditional lead-antimony alloys are being replaced by multi-component alloys such as
lead-calcium-tin-silver. A project test demonstrated that the new lead-silver-calcium alloy anode in zinc sulfate
electrolysis reduced oxygen evolution overpotential by 15%, extended lifespan by 40%, and significantly lowered
energy consumption and maintenance costs.
Breakthrough in Titanium-Based Coatings: In highly corrosive environments (such as chlor-alkali industries and chrome
plating), coatings of precious metal oxides (DSA) such as iridium-tantalum or ruthenium-iridium on a titanium substrate
have become the preferred choice for insoluble anodes. Their core advantage lies in their excellent dimensional stability,
which prevents metal impurity contamination, making them particularly suitable for high-purity metal extraction
(such as electrolytic copper foil and electronic-grade nickel).
Advancements in casting and processing technologies:
Melting control: Using a medium-frequency furnace combined with argon gas protection during melting, coupled
with online composition analysis, ensures precise distribution of alloy elements and reduces segregation. A certain
factory improved the hardness uniformity of lead-calcium alloy anode plates by 50% through optimized melting processes.
Precision rolling and flattening: Multi-pass precision rolling combined with hydraulic flattening ensures surface
flatness errors of less than 0.5 mm/m². This is critical for maintaining uniform electrode spacing and preventing
short circuits.
The magic of surface treatment:
Special Sandblasting Treatment: Controlling surface roughness (Ra value) increases the reaction surface area while
optimizing the uniformity of initial dissolution, preventing “crusting.”
Pre-filming Technology: For specific alloys (such as aluminum-based anodes used in zinc electrolysis), electrochemical
pre-filming treatment is performed before use to form a stable protective layer, significantly reducing the risk of
initial passivation and extending service life.
Anode Plate Practical Handbook: Lifecycle Management of Selection,
Installation, and Maintenance
Three Key Factors for Precise Selection:
Process Compatibility: High-purity copper anodes (>99.99%) are preferred for copper electrolysis; pure aluminum or
aluminum alloys are selected for acidic zinc plating; nickel plating requires sulfur-containing nickel anodes (S 0.02-0.04%)
to inhibit passivation; titanium-based DSA is used in highly corrosive environments (chromium plating, chlor-alkali).
Assessing Process Conditions: Consider current density levels, electrolyte temperature, acid/alkali concentration, and the
presence of strong corrosive ions such as fluoride or chloride. Higher current densities may require thicker plates or
reinforced coatings.
Balancing Cost and Lifespan: Calculate the total cost (initial purchase + energy consumption + maintenance + replacement
costs). While DSA anodes are more expensive, they may offer greater advantages over the long term.
Golden Rules for Installation and Operation:
Electrode spacing: Strictly set according to process requirements (typically 80–150 mm), with an error tolerance of
±2 mm. Use a laser distance meter to assist with installation.
Conductive contact points: The contact surfaces between the copper busbar and anode tabs must be polished to a
mirror finish, coated with conductive grease, and secured with bolts at the specified torque. Poor contact is a common
cause of abnormal voltage spikes.
Initial Activation: Some anodes (e.g., DSA) require low-current-density activation according to the supplier's guidelines
to form a stable active layer.
Maintenance and Failure Warning:
Daily Inspections: Check the uniformity of plate surface dissolution, any abnormal bending, and the temperature of
conductive points (using an infrared thermometer) daily.
Thickness Monitoring: Regularly (e.g., monthly) measure the remaining thickness at critical locations using an ultrasonic
thickness gauge, plot consumption curves, and predict replacement cycles. When the thickness drops to 50%-60% of
the initial value, it requires special attention.
Failure Signal Identification:
Uneven Dissolution: The plate surface exhibits “pits” or “nodules.”
Passivation: Abnormal sustained increase in cell voltage, with a decrease in the quality of cathode deposits.
Physical damage: Obvious bending, cracking, or peeling of the coating.
Impurity contamination: Unidentified impurity points or brittleness in the cathode product.
Senior Engineer's Field Notes:
“The ear is the critical point”: Anode plate fractures almost always occur at the junction between the ear and the
plate body. Selecting a cast monolithic structure or a special reinforced welded structure is crucial.
“Temperature fluctuations are an invisible killer”: Frequent temperature changes accelerate thermal fatigue of the
coating/substrate, leading to cracking and peeling. Maintaining stable electrolyte temperature is key to
extending DSA lifespan.
“Anode sludge is also valuable”: Anode sludge from precious metal electrolysis (e.g., gold and silver) contains
valuable materials. Collection and processing processes must be optimized simultaneously to maximize
resource recovery.
Anode plates are by no means a “supporting role” in the electrolytic cell; their performance directly impacts the
quality of the final product, energy consumption and costs during production, and the stability of the entire
production line. From the creation of high-purity copper foil, to the formation of bright coatings, to the production
of millions of tons of non-ferrous metals, every successful electrochemical process relies on a high-performance
anode plate silently releasing energy. In the precision chain of industrial production, the anode plate is the silent
foundation, using its own dissolution to forge the essence of countless products. When current flows through
the electrolyte, the selection and maintenance of anode plates are the key to unlocking efficient and stable
production.