Henan Hongke Heavy Machinery Co., Ltd. ("Henan Hongke Machinery") has designed, manufactured, and delivered a lime rotary kiln production line with an annual capacity of 15,000 tons of quicklime for a client in Yangquan City, Shanxi Province, China. The system is fully operational, producing high-quality quicklime (CaO) for the local coal chemical, steel, construction, and environmental treatment industries.
Yangquan — one of China's historically significant coal mining and industrial cities — is undergoing a strategic industrial transformation. As the city shifts from coal-dependent heavy industry toward diversified, cleaner manufacturing, lime production has emerged as a key supporting industry. Quicklime is essential for coal chemical processing, steel refining, flue gas desulfurization, and wastewater treatment — all sectors experiencing growing demand in the Shanxi region.
The client selected Henan Hongke Machinery after evaluating multiple equipment suppliers, ultimately choosing the company for its proven lime kiln expertise, integrated preheater design, and comprehensive project execution capability.
Background: Lime Industry in Shanxi Province
Shanxi Province is China's largest coal-producing region and a major center for coal chemical industry, steel production, and heavy manufacturing. These industries consume enormous quantities of quicklime:
The Yangquan project was conceived to serve this diverse regional market — producing multiple lime grades for steelmaking, coal chemical processing, and environmental applications, using locally sourced limestone with minimal transport cost.
Raw Material: Yangquan Limestone
The Yangquan area possesses substantial high-calcium limestone reserves suitable for lime production. The limestone used in this project has the following characteristics:
The high CaCO₃ content (> 93%) and low impurity levels make this limestone ideal for producing high-activity, high-purity quicklime. The low MgCO₃ ensures the product remains high-calcium lime (not dolomitic lime), which is preferred by steel mills and coal chemical plants.
Equipment Specification
The rotary kiln system delivered by Henan Hongke Machinery has the following specifications:
Complete System Scope
The production line includes the following integrated subsystems, all designed and manufactured by Henan Hongke Machinery:
Working Principle: From Limestone to Quicklime
Step 1: Limestone Crushing and Sizing
Quarry limestone (blocks up to 600 mm) is reduced to 40–100 mm by a jaw crusher. The crushed stone is screened to remove fines (< 30 mm) and oversize (> 120 mm), then conveyed to the covered storage hopper.
Why remove fines and oversize:
- Fine fragments over-calcine, creating excess dust and reducing product quality
- Oversize fragments under-calcine in the center, resulting in high residual CaCO₃ and wasted energy
Step 2: Preheating (Vertical Preheater)
The crushed limestone is fed into the vertical preheater via a hydraulic push-rod feeder. Inside the preheater, limestone moves slowly downward through multiple channels while hot kiln exhaust gas (1,000–1,100 °C) flows upward through the material bed.
This counter-current heat exchange preheats the limestone to approximately 900 °C and initiates 25–35% calcination before the material enters the rotary kiln. Benefits:
- 25–30% fuel savings compared to a kiln without preheater
- Shorter kiln required — significant calcination already completed before kiln entry
- Pre-separation of dust — the preheater acts as a gravity separator, reducing the load on the downstream bag filter
Step 3: Calcination (Rotary Kiln)
The preheated limestone enters the elevated end of the rotary kiln. As the drum rotates at 0.5–3.5 rpm, the material moves toward the discharge end through two zones:
- 1.Transition zone (900–1,100 °C): Remaining CaCO₃ decomposition accelerates. CO₂ is visibly released.
- 2.Burning zone (1,100–1,250 °C): Calcination is completed. Residence time in the burning zone: 15–25 minutes.
The kiln operates under slight negative pressure maintained by the induced draft fan, ensuring counter-current gas flow from burner to preheater — maximizing heat transfer efficiency.
Step 4: Cooling (Vertical Cooler)
Hot quicklime (~1,100 °C) falls into the vertical cooler, where cold air blown upward through the descending lime bed cools the product to below 80 °C. The air, preheated to 400–600 °C, is used as secondary combustion air at the burner — recovering significant thermal energy.
Rapid cooling prevents re-carbonation (CO₂ re-absorption from the atmosphere), preserving quicklime activity.
Step 5: Product Handling and Storage
Cooled quicklime is conveyed to graded storage bins and dispatched as:
- Lump lime (20–100 mm): For steelmaking and construction
- Crushed lime (0–20 mm): For coal chemical and environmental applications
- Hydrated lime: Produced on-site using a hydrator (optional system)
Design Highlights
Vertical Preheater — The Efficiency Driver
The vertical preheater is the most impactful design feature. By preheating limestone to 900 °C and completing 25–35% of calcination before kiln entry, it reduces the kiln's thermal burden by approximately 25–30%. This directly translates to:
- Lower fuel consumption (850–1,050 kcal/kg vs. 1,100–1,300 kcal/kg without preheater)
- Shorter kiln length (40 m vs. 55+ m without preheater for the same capacity)
- Lower capital cost and smaller footprint
Vertical Cooler — Heat Recovery and Product Quality
The vertical cooler performs dual functions:
- 1.Product quality: Rapid cooling locks in the high-activity crystal structure of quicklime
- 2.Energy recovery: Preheated secondary air (400–600 °C) reduces fuel consumption at the burner
Multi-Channel Burner — Precise Temperature Control
The multi-channel burner provides:
- Long, adjustable flame for uniform heat distribution across the 15 m burning zone
- Temperature control within ±20 °C
- Low NOx formation through staged combustion
- Dual-fuel capability (pulverized coal primary, natural gas backup)
Kiln Shell Temperature Scanner — Safety and Maintenance
An infrared line-scanning system continuously monitors the kiln shell surface temperature around the full circumference, detecting:
- Hot spots from refrailure failure (critical early warning)
- Cold spots from ring formation or material buildup
- Temperature trends for predictive maintenance planning
Integrated Environmental Systems
Process Control Parameters
Performance Results
Based on operating data from the Yangquan installation:
Multiple Product Grades for Diverse Markets
The Yangquan production line is designed to serve multiple end-markets simultaneously:
The ability to produce multiple grades from a single kiln — by adjusting the crushing and screening stages — maximizes market flexibility and revenue potential.
Benefits to the Client
Why Yangquan for Lime Production?
The Yangquan location offers several strategic advantages:
- Rich limestone resources: High-calcium limestone (CaCO₃ > 93%) available locally, minimizing raw material transport cost
- Strong regional demand: Steel mills, coal chemical plants, and environmental projects in the Shanxi–Hebei–Inner Mongolia region consume large volumes of quicklime
- Transportation infrastructure: Well-connected by highway and rail to major industrial centers in Shanxi and neighboring provinces
- Industrial workforce: Yangquan's long industrial history provides experienced operators and maintenance personnel
- Government support: Shanxi Province encourages diversification of traditional coal-dependent industries into supporting manufacturing sectors like lime production
Henan Hongke Machinery's Lime Kiln Range
Henan Hongke Machinery manufactures lime rotary kiln systems across a wide capacity range:
Every system is engineered for the client's specific limestone chemistry, fuel type, capacity target, and product quality requirements. Henan Hongke Machinery supplies the complete production line — from limestone crushing through preheating, calcination, cooling, and product handling — as a turnkey package.
Client Feedback
"We chose Henan Hongke Machinery because they demonstrated real expertise in lime kiln engineering during the proposal stage — they asked the right questions about our limestone chemistry, fuel supply, and market requirements. The vertical preheater design has delivered exactly the fuel savings they promised. The quicklime quality is excellent — our steel mill and coal chemical customers are very satisfied. The project was managed professionally from manufacturing through commissioning."
About Henan Hongke Heavy Machinery Co., Ltd.
Henan Hongke Heavy Machinery Co., Ltd., based in Henan Province, China, is a professional manufacturer of rotary kiln systems for lime, cement, magnesium, zinc oxide, and environmental applications. The company's production facility is equipped with plate rolling machines, CNC machining centers, welding stations, and quality control laboratories, enabling complete in-house manufacturing of all major kiln components.
Henan Hongke Machinery serves clients worldwide, providing engineering, manufacturing, shipping, installation supervision, commissioning, and after-sales support as an integrated service.
Have a lime production project? Contact us to discuss your requirements.