In the mineral processing and metallurgical sectors, the efficient recovery of zinc from industrial waste streams and low-grade ores has become a priority for both economic and environmental reasons. China generates over 50 million tons of zinc-bearing dust annually from steel smelting operations alone, representing a significant secondary resource for the zinc industry .
Henan Hongke Heavy Machinery Co., Ltd. recently designed, manufactured, and commissioned a complete zinc oxide rotary kiln system for a client in Gansu Province, China. With an annual production capacity of 6,000 tons of zinc oxide (ZnO) , this turnkey project demonstrates our capability to deliver high-performance thermal processing solutions tailored to the unique requirements of zinc recovery operations.
The Challenge: Processing Zinc-Bearing Materials
The client operates in a region rich in zinc-bearing industrial waste and low-grade zinc ores. The primary challenge was to establish an efficient, reliable, and environmentally compliant production line capable of:
Processing feed materials with zinc content ranging from 15% to 25%
Achieving high zinc recovery rates with minimal operational downtime
Producing high-purity zinc oxide powder suitable for commercial applications
Operating cost-effectively with reduced energy consumption
Minimizing refractory wear and kiln-ringing issues common in zinc oxide production
Zinc oxide produced by this process serves as a critical raw material across multiple industries, including rubber manufacturing, paints and coatings, ceramics, glass, electronics, and chemical production .
The Solution: Custom-Engineered Zinc Oxide Rotary Kiln System
Henan Hongke Machinery's engineering team conducted thorough material analysis and process modeling before designing a custom solution. The resulting zinc oxide rotary kiln system incorporates the following key elements:
System Components
The complete production line includes:
Raw material batching and mixing system
Feeding and material handling equipment
Main rotary kiln body with supporting structure
Kiln drive and transmission system
Dust collection and gas cleaning system
Slag water quenching system
Flue gas desulfurization unit
Centralized control system
Technical Specifications
The rotary kiln supplied for this Gansu project is a heavy-duty unit designed for continuous 24/7 operation. While specific model parameters are customized for each client's throughput requirements, zinc oxide rotary kilns typically feature :
| Parameter | Typical Range |
|---|---|
| Shell Diameter | 1.8m – 3.2m |
| Shell Length | 40m – 50m |
| Kiln Inclination | 3% – 4% |
| Rotational Speed | 0.6 – 3.48 r/min |
| Calcination Temperature | Up to 1000°C |
The Process: How Zinc Oxide Is Produced
The zinc oxide rotary kiln process follows a well-established reduction roasting route :
Stage 1: Raw Material Preparation
Zinc-bearing materials (zinc ore, zinc-containing industrial slag, steel plant dust, or similar feedstocks) are crushed to below 40 mesh particle size and mixed with anthracite coal or coke fines at a controlled ratio of approximately 1:0.30 to 1:0.35 .
Stage 2: Pelletizing
The mixed material is formed into pellets with an effective diameter of 8-15 mm, ensuring uniform feeding and consistent reduction behavior within the kiln .
Stage 3: Rotary Kiln Reduction
The pelletized feed enters the kiln from the elevated tail end and gradually moves toward the discharge end as the kiln rotates. In the high-temperature zone of the kiln:
Carbon reacts with oxygen to generate CO
CO and solid carbon reduce zinc oxide in the feed to metallic zinc vapor
Zinc vapor is re-oxidized by air within the kiln to form ZnO fume
Stage 4: Collection and Refining
The zinc oxide fume is carried by the exhaust gas stream through a cooling system and collected in dust collectors (typically pulse-jet bag filters). The collected zinc oxide powder is then packaged for sale or further processing.
Stage 5: Slag Disposal
Residual kiln slag undergoes water quenching at the kiln discharge end and can be sold for cement production or further processed for iron recovery .
Key Design Features for Optimal Performance
Advanced Temperature and Atmosphere Control
One of the major challenges in zinc oxide production is maintaining precise control over the temperature and atmosphere within the kiln. Our system features multi-point air injection to maintain optimal reducing conditions in the reduction zone and controlled oxidation conditions in the fume collection area. This technology enables effective treatment of raw materials with high iron and zinc content while improving production efficiency and product quality .
Wear-Resistant Refractory Lining
Zinc oxide feed materials can be abrasive and chemically aggressive. The kiln is lined with high-grade refractory materials selected specifically for zinc oxide service, with particular attention to the high-temperature reduction zone where the most severe conditions exist.
Efficient Dust Collection System
Zinc oxide fume collection efficiency directly impacts both product yield and environmental compliance. Our system incorporates:
A water-cooled or air-cooled flue gas cooling section
Cyclone pre-separators for coarse particle removal
Pulse-jet baghouse filters for fine ZnO recovery
Kiln Ringing Prevention
Kiln-ringing — the formation of hard deposits on the kiln inner wall — is a well-documented challenge in zinc oxide rotary kiln operations . Our design incorporates operational parameters and refractory selection strategies that minimize ring formation, including optimized feed composition, controlled temperature gradients, and appropriate rotational speeds. Advanced designs can increase processing capacity by up to 30% compared to conventional approaches while reducing ring formation .
Performance Results
Following successful commissioning and ramp-up, the Gansu 6,000 TPA zinc oxide rotary kiln system has demonstrated the following operating metrics:
Annual ZnO Production: 6,000 tons
Feed Processing Capacity: Matched to achieve design output with typical feed zinc grades
Zinc Recovery Rate: Consistent with industrial best practices
Product Quality: ZnO product meeting commercial specifications for rubber, paint, and chemical applications
Operation Rate: High availability with minimal unscheduled downtime
Economic and Environmental Benefits
Resource Recovery
The project transforms industrial waste and low-grade zinc materials into a high-value commercial product, supporting circular economy principles in the metals sector.
Energy Efficiency
Careful thermal management and optimized fuel-to-feed ratios help reduce specific energy consumption. When similar advanced control systems are applied, comprehensive energy consumption can be maintained at levels suitable for cost-effective operation .
Environmental Compliance
The integrated dust collection and flue gas treatment systems ensure emissions meet applicable environmental standards, making the operation viable for long-term production.
About Henan Hongke Heavy Machinery Co., Ltd.
Henan Hongke Heavy Machinery Co., Ltd. (Henan Hongke Machinery) is a professional manufacturer of industrial rotary equipment headquartered in Henan Province, China. With decades of experience in rotary kiln design and fabrication, the company serves clients across the metallurgical, chemical, mining, environmental, and building materials industries .
Our capabilities include:
Complete in-house engineering design
Heavy fabrication and precision machining
Turnkey project delivery from concept to commissioning
Installation supervision and operator training
Responsive after-sales support and spare parts supply
Hongke's manufacturing facility spans over 80,000 square meters, and we maintain ISO 9001 and CE certifications to international quality standards .
Conclusion
The Gansu 6,000 TPA zinc oxide rotary kiln project exemplifies Henan Hongke Machinery's ability to deliver customized, high-performance thermal processing solutions for the global metallurgical industry. From material characterization and process design to equipment fabrication and on-site commissioning, our team provides end-to-end support to ensure project success.
Whether you are processing zinc-bearing industrial waste, low-grade zinc ores, or other challenging feed materials, Henan Hongke Machinery has the engineering expertise and manufacturing capacity to deliver a rotary kiln system that meets your production goals.
Contact us today to discuss your zinc oxide rotary kiln requirements.