When the steel framework of a cross-sea bridge stands tall against salt fog for a century without
corrosion, when a car chassis remains sturdy through rain, snow, and mud, and when a tiny button
battery powers precision equipment, behind it all lies the relentless passion of zinc smelting plants
working day and night. Here, ore and waste materials undergo a rebirth through the fiery and chemical
processes, transforming into pure zinc ingots—this unsung “corrosion-resistant guardian” embodies a
unique spirit of sacrifice and exceptional performance, forming the durable foundation and safety
barrier of modern industry.
The Initial Forge of the Mine: The Transformation from Ore
to Concentrate
Zinc's journey begins with sphalerite (ZnS) deep within the Earth's crust. The first step in the smelting process
is to awaken the dormant ore:
Boiling Roasting: The concentrate is fed into a boiling furnace, where it violently churns in high-temperature air
exceeding 900°C. Zinc sulfide (ZnS) reacts vigorously with oxygen, converting into zinc oxide (ZnO), which is
soluble in acid, while releasing sulfur dioxide (SO₂) gas—this is not waste but the core raw material for
subsequent acid production.
Flue gas acid production: The high-temperature flue gas rich in SO₂ is sent to the conversion tower after
efficient dust removal and cooling. Under the action of a catalyst, SO₂ is precisely oxidized into SO₃, which
then combines with water to form the precious industrial lifeblood—concentrated sulfuric acid. This not only
eliminates pollution but also maximizes resource value.
The essence of the wet process: the art of leaching and purification
The mainstream method in modern zinc smelting is the wet process, a precise purification process conducted
in an aqueous solution:
Leaching and dissolution: Calcined zinc oxide (ZnO) is added to dilute sulfuric acid solution, where zinc dissolves
into the solution in the form of zinc sulfate (ZnSO₄). Temperature, acidity, and stirring intensity are precisely
controlled to achieve efficient zinc dissolution while suppressing impurities.
Deep Purification: The leaching solution is like a “metal soup” containing unwanted impurities such as copper,
cadmium, cobalt, and nickel. The smelter acts as an experienced “chemical hunter,” employing multi-stage
purification processes—zinc powder replacement (using zinc's reactivity to replace copper, cadmium, etc.)
and deep cobalt and nickel removal (special reagent precipitation)—to progressively eliminate impurities
until the solution is as clear as a spring, laying the groundwork for pure electrolysis. Each purification step
is a solemn commitment to metal purity.
Electrolysis Rebirth: Crystallization in the Current
The purified solution flows into the electrolysis workshop, where zinc undergoes its final transformation:
Cathode Deposition: When direct current is applied, the pure zinc sulfate solution undergoes a remarkable
reaction within the electrolysis cell. Zinc ions (Zn²⁺) gain electrons on the aluminum cathode plates,
crystallizing uniformly and densely layer by layer to form shiny cathode zinc plates.
Anode Mission: Under the influence of the current, water molecules are oxidized and release oxygen on the
lead alloy anode plates, maintaining the charge balance of the electrolysis system. The anode and cathode
work in perfect harmony to continuously produce high-purity zinc (purity often exceeds 99.995%).
Melting and Casting: The Solidification of Liquid Metal
The zinc sheets separated from the cathode are remelted in a reverberatory furnace:
Refining and impurity removal: The molten zinc solution is further treated through settling or the
addition of small amounts of additives to remove trace impurities such as lead and iron.
Ingot casting: Molten zinc is injected into an automated ingot casting line, where it cools and solidifies
into standard-sized zinc ingots (such as 0# and 1# zinc). These shimmering “metal bricks” serve as the
foundation for global industrial applications.
Circular regeneration: The responsibility of green metallurgy
Zinc smelters are not only creators of primary metals but also practitioners of the circular economy:
Waste zinc “reborn”: Zinc-containing waste materials such as hot-dip galvanizing slag, zinc alloy scrap,
and used batteries are scientifically recycled, pre-treated, and reintroduced into furnaces or leaching
systems, giving zinc a second life.
Treasure in the slag: Leaching slag is rich in valuable elements such as iron, lead, silver, and indium.
Through processes like magnetic separation, flotation, and volatilization, these “sleeping” resources are
efficiently extracted, while the tailings are safely stored or used in construction materials after harmless
treatment. Every ton of slag processed is a testament to respect for Earth's resources.
Innovation-driven: The eternal pursuit of efficiency and
environmental protection
Modern zinc smelters continue to evolve with the empowerment of technology:
Process optimization: Exploring new technologies such as oxygen-enriched roasting and atmospheric
direct leaching to improve efficiency and reduce energy consumption.
Smart control: Sensor networks and intelligent algorithms monitor leaching acidity, electrolyte composition,
and current efficiency in real time, enabling precise regulation and stable production.
Environmental Upgrades: More efficient flue gas desulfurization and denitrification, advanced wastewater
treatment for “zero emissions,” and solid waste resource utilization technologies are continuously iterated,
driving the realization of a “green zinc plant.”
Choosing Partners: Building a Sustainable Future for the Zinc Industry
Zinc, this critical metal that safeguards steel, drives energy, and integrates into daily life, requires both high quality
and stable supply. A reliable zinc smelting partner should possess:
Exceptional quality foundation: Strict adherence to international standards (such as GB/T 470-2008, LME-registered
brands) to ensure the absolute reliability of zinc ingot purity and physical specifications.
Stable supply assurance: Advanced production systems and mature process control capabilities to establish robust
production capacity and stable delivery capabilities.
A commitment to green smelting: Leading environmental protection facilities and technological investments to achieve
efficient resource utilization and clean production.
An innovative technological foundation: Continuous R&D investments to enhance efficiency, reduce energy
consumption, and lead the industry toward sustainable development.
The zinc smelter, this industrial sanctuary where flames, chemistry, and electricity converge, continues to supply
the world with pure, durable power. It is the “invisible armor” that protects skyscrapers from wind and rain, the
“rust-proof foundation” that enables cars to traverse landscapes, and the “miniature engine” that connects us
to the future's energy. Every flickering of the furnace flames and every flow of electricity silently reinforces the
solid foundation of modern civilization.