Guangxi is home to considerable reserves of limonite-type iron ore, much of which is characterized by low iron grade, high combined water and silica content, and weak magnetism—properties that make direct magnetic separation inefficient and uneconomical. A mineral processing enterprise in Guangxi, seeking to improve the utilization value of its local limonite resource, decided to build a magnetizing roasting–magnetic separation production line centered on a Φ3.0×45 m rotary kiln. After technical evaluation and supplier comparison, the project selected Henan Hongke Heavy Machinery Co., Ltd. as the rotary kiln equipment supplier, with the kiln serving as the core thermal unit for the reduction roasting stage.
Process Scheme and Kiln Configuration
The production line follows the route of “crushing and screening—batching with reductant—rotary kiln reduction roasting—water quenching—grinding—magnetic separation.” Limonite ore is crushed and screened to a suitable feed size, blended with a carbonaceous reductant, and fed into the rotary kiln. Inside the kiln, under controlled temperature and a reducing atmosphere, the weakly magnetic iron minerals in the limonite are converted into magnetite, which can then be recovered efficiently by magnetic separation after cooling and grinding.
The Φ3.0×45 m rotary kiln supplied by Hongke operates with a typical inclination of 3.5% and a variable rotational speed range suited to the residence time required for reduction. The kiln is equipped with a multi-channel burner and a temperature monitoring system that allows operators to regulate the temperature profile along the kiln length. The reduction zone is maintained in the range of approximately 700–800°C, where the conversion of limonite to magnetite proceeds most effectively, while the preheating zone utilizes kiln tail gas to remove free moisture and begin dehydroxylation before the material reaches the reduction zone.
Refractory lining selection and kiln sealing were addressed with the specific demands of continuous reduction roasting in mind. The kiln shell, riding rings, support rollers, and drive system are sized for stable operation under the thermal load of iron ore processing. Hongke’s manufacturing scope for this project covered the rotary kiln body and its core mechanical components, with the balance of the production line—feed preparation, cooling, grinding, and magnetic separation—coordinated to match the kiln’s throughput.
Operational Results and Customer Feedback
Since commissioning, the line has operated with the Φ3.0×45 m kiln as the thermal core of the beneficiation circuit. The reduction roasting step has successfully converted the weakly magnetic limonite into a form amenable to magnetic separation, and the downstream magnetic separation stage produces an iron concentrate with a markedly higher grade than the raw ore. The customer reported that the kiln’s temperature regulation and residence time control were key to achieving consistent conversion, and that the equipment has demonstrated stable mechanical performance under continuous operation.
The project team noted that Hongke’s experience with rotary kilns for mineral processing applications was a deciding factor in the equipment selection. The kiln’s ability to maintain a controlled reducing atmosphere and uniform material bed temperature directly affects the magnetic conversion rate, and therefore the overall recovery of the beneficiation circuit. The customer also valued the practical engineering support during installation and commissioning, particularly in aligning the kiln’s operating parameters with the specific characteristics of the Guangxi limonite feed.
Case Summary
The Guangxi Φ3.0×45 m limonite rotary kiln project demonstrates the application of magnetizing roasting technology to a low-grade, weakly magnetic iron ore resource. By integrating a properly sized and controlled rotary kiln into the beneficiation flowsheet, the project converts what would otherwise be a difficult-to-process ore into a magnetic concentrate suitable for further use. Henan Hongke Heavy Machinery Co., Ltd. supplied the kiln as the central thermal unit, with the equipment configuration and operating parameters tailored to the reduction roasting requirements of limonite. For regions with similar low-grade iron ore deposits, this case offers a reference for evaluating rotary kiln-based magnetizing roasting as a route to improved resource utilization.