With the development of the steel and non-ferrous metals industries. The amount of zinc-containing waste materials such as electric arc furnace dust (EAF dust), zinc ash, and zinc slag is increasing. The Waelz kiln (zinc oxide rotary kiln) has become one of the most widely used zinc recycling equipment in the world, due to high recovery rates, stable operation, and large processing capacity. waelz kiln process uses high-temperature reduction and volatilization. The zinc in zinc-containing materials is converted into zinc vapor, which is then collected through an oxidation and dust removal system, the final product was waelz zinc oxide. The zinc recovery rate of this waelz kiln process can typically easily exceed 90%.
Step-by-Step Waelz Kiln Process Flow
- Step 1 — Raw Material Preparation and Granulation
Zinc-containing electric arc furnace dust and a reducing agent are mixed in strict proportions. It is then processed into uniform pellets using a granulator. Before being sent into the kiln, the material is properly dried to reduce its moisture content.
- Step 2 — High Temperature Reduction
The granulated material is then fed into the Waelz kiln (zinc oxide rotary kiln). The kiln body rotates slowly, maintaining a high-temperature environment of approximately 1,000–1,200°C. Under the action of a reducing agent, the zinc oxide in the material is reduced to zinc vapor. This is the core step of the entire waelz kiln process.
- Step 3 — Zinc Vapor Oxidation and Gas Cooling
After the zinc vapor leaves the kiln, it rapidly reoxidizes upon contact with air, forming fine zinc oxide particles. The high-temperature flue gas is cooled by the cooling system, creating the necessary conditions for dust removal.
- Step 4 — Collect Zinc Oxide Using a Bag Filter
The cooled flue gas enters the baghouse dust collector. Fine zinc oxide particles are collected by the filter bag and eventually yield waelz zinc oxide.
- Step 5 — Packaging the Finished Product
After the collected waelz zinc oxide passes the inspection, it is placed in the storage silo. Packaging options include ton bags, bulk packaging, or other forms, depending on customer requirements.
Key Waelz Kiln Technology Advantages
1. High Recovery Rate (≥92%): Modern Waelz kiln Technology uses optimized kiln design and a stable high-temperature reduction process. It can fully recover zinc from materials such as electric arc furnace dust, zinc slag, and zinc ash. The zinc recovery rate can typically reach over 92%.
2. Energy Consumption Reduced by 15%: Modern Waelz kiln technology enables more precise control of kiln temperature and fuel consumption. Compared to traditional processes, overall energy consumption can be reduced by approximately 15%. It saves on production costs and reduces energy waste.
3. Advanced Sealing Technology: Waelz kiln uses advanced kiln head and kiln tail sealing structures. This can effectively reduce the amount of cold air entering the kiln, preventing high-temperature flue gas leakage. To meet stricter environmental protection requirements.
4. Continuous Operation (180–800 tons/day): The modern Waelz kiln can operate stably 24 hours a day. This reduces the number of shutdowns and improves production efficiency. The equipment’s processing capacity can reach 180–800 tons per day.
Key Equipment for Modern Waelz Kiln Technology
The Waelz kiln, also known as a zinc oxide rotary kiln, is the core piece of equipment in the entire Waelz process.
Production capacity: 180 t/d – 800 t/d.
Raw materials: Zinc concentrate, zinc sludge, zinc tailings, zinc-bearing flue dust, steel plant dedusting dust, electric arc furnace (EAF) dust.
Product specifications: Ø2.5 × 40 m – Ø3.0 × 60 m.
Slope: 3% – 4%.
Choosing the Right Waelz Kiln for Your Operation
1. Select according to raw material type:
Different zinc-containing raw materials have different equipment configuration requirements. When selecting a Waelz kiln, the kiln dimensions, combustion system, and process parameters should be designed based on the characteristics of the raw materials.
2. Select according to processing capacity:
Determine equipment specifications based on the enterprise’s daily production output. If the processing volume is small, a medium-sized Waelz kiln can be selected. For large-scale zinc recycling projects, it is recommended to choose a large-scale continuous production line with a capacity of 800 t/d.
3. Choose highly automated equipment:
The automated control system can monitor key parameters such as kiln temperature, rotation speed, and combustion status in real time. This makes the production process more stable and reduces manual operation. This improve product quality and operational efficiency.
4. Choose an experienced supplier:
In addition to the equipment itself, the supplier’s technical expertise and service capabilities are equally important. Manufacturers with extensive project experience can provide process design, equipment manufacturing, installation, commissioning, and after-sales service based on the characteristics of the raw materials. It helps the production line operate stably in the long term.
Summary
For companies planning to build or upgrade zinc recycling production lines. Choose mature and reliable Waelz kiln equipment and professional process solutions, it not only improves the quality of waelz zinc oxide products but also enables resource recycling and enhances the company’s market competitiveness.
