The clinker rotary kiln is a key equipment used in cement production. Its main function is to calcine raw materials (usually limestone, clay and other minerals) into cement clinker. Cement clinker is an intermediate product in cement production and can become the final cement product after grinding. The core function of the clinker rotary kiln is high-temperature calcination. Through a series of complex chemical reactions, the mineral components in the raw materials form the mineral phases required for cement clinker, such as tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF).
Efficient Clinker calcination Solution
A MACHINE YOU CAN DEPEND ON!
Our clinker rotary kiln is ideal for processing high temperature, high strength and highly abrasive materials such as cement clinker, limestone and slag. The equipment provides stable burning and cooling operation throughout the production process, ensuring consistent product quality while being highly energy efficient.
The rotary kiln body is made of high-strength steel, has good rigidity, can withstand the load of hundreds of tons of materials per hour, maintain stability at high speed, and ensure the smooth operation of the equipment during production.
The rotary kiln body undergoes strict polishing and anti-corrosion treatment, such as surface galvanizing or spraying corrosion-resistant coating, which improves corrosion resistance by more than 30%, effectively resists corrosion in harsh environments, and enhances the appearance and durability of the equipment.
When designing the clinker rotary kiln, the thermal expansion coefficient under high temperature operation is taken into account. For example, when the kiln body is operated at 1200°C, the thermal expansion length may increase by about 0.3%. Through reasonable design, structural deformation is avoided, thereby extending the life of the equipment.
xxxxxxx | Capacity (t/h) | Motor Model: | Gearbox Model | Input Moisture (%) | Fuel Coal Calorific Value (kcal) | Output Moisture (%) |
φ1.2x10 | 2.5-3 | M160M-6 → 7.5 | ZQ350Ⅱ-25 | 25±5 | ≥5500 | ≤13 |
φ1.5x14 | 7-9 | Y180L-6 → 15 | ZQ400Ⅱ-31.5 | 25±5 | ≥5500 | ≤13 |
φ1.5x18 | 9.5-12 | Y180L-6 → 15 | ZQ400Ⅱ-31.5 | 27±5 | ≥5500 | ≤13 |
φ1.8x14 | 12-15 | Y200L-6 → 18.5 | ZQ400Ⅱ-31.5 | 25±5 | ≥5500 | ≤13 |
φ1.8x18 | 14-18 | Y200L1-6 → 18.5 | ZQ400Ⅱ-31.5 | 27±5 | ≥5500 | ≤13 |
φ2.0x18 | 18-22 | Y200L2-6 → 22 | ZQ50Ⅱ-31.5 | 25±5 | ≥5500 | ≤13 |
φ2.0x20 | 18-23 | Y200L2-6 → 22 | ZQ50Ⅱ-31.5 | 30±5 | ≥5500 | ≤13 |
φ2.2x18 | 21-25 | Y200L2-6 → 22 | ZQ65Ⅱ-31.5 | 27±5 | ≥5500 | ≤13 |
φ2.2x20 | 22-25 | Y225M-6 → 30 | ZQ65Ⅱ-31.5 | 30±5 | ≥5500 | ≤13 |
φ2.4x20 | 25-29 | Y225M-6 → 30 | ZQ75Ⅱ-31.5 | 27±5 | ≥5500 | ≤13 |
φ2.4x22 | 26-30 | Y225M-6 → 30 | ZQ75Ⅱ-31.5 | 30±5 | ≥5500 | ≤13 |
φ2.6x20 | 28-33 | Y250M-6 → 37 | ZQ85Ⅱ-31.5 | 25±5 | ≥5500 | ≤13 |
φ2.6x24 | 29-35 | Y250M-6 → 37 | ZQ85Ⅱ-31.5 | 30±5 | ≥5500 | ≤13 |
φ3.0x20 | 45-50 | Y280S-6 → 45 | ZQ100Ⅱ-31.5 | 25±5 | ≥5500 | ≤13 |
QUALITY NEVER GOES OUT OF STYLE
The production process of cement clinker includes four main stages: raw material preparation, preheating, calcining and cooling. First, the raw material preparation stage involves the pretreatment and mixing of limestone, clay, iron ore, etc.
The commonly used raw material ratio is 60-65% limestone, 20-25% clay, and 10-15% iron ore and other auxiliary materials. In the preheating stage, the raw materials are heated to about 800°C in a preheater. This stage mainly uses the preheater and decomposition furnace to preliminarily heat the raw materials to decompose the limestone into calcium oxide and carbon dioxide, while improving the energy efficiency of the subsequent calcining stage. The calcining stage is carried out in a rotary kiln, and the temperature usually reaches 1400°C to 1450°C. This high temperature causes the main components in the raw materials to undergo solid-phase reaction to produce cement clinker.
The materials in the rotary kiln will rotate and be heated for up to 60 minutes to form minerals such as calcium silicate (C3S) and dicalcium silicate (C2S). The cooling stage is to quickly cool the high-temperature clinker to below 1000°C, usually using a cooler. Rapid cooling can effectively prevent excessive growth of mineral crystals and ensure the stable performance of cement clinker.
Calcium silicate (C3S): accounts for about 50-60% of cement clinker. It is the main component of cement, which determines the early strength of cement and mainly provides strength in the early stage of hardening.
Dicalcium silicate (C2S): accounts for about 25-30%. C2S hardens slowly, but it contributes greatly to the long-term strength of cement and usually improves the strength of cement in long-term use.
Tricalcium aluminate (C3A): accounts for 5-10% of cement clinker. It gives cement good early strength, but too high C3A will reduce the sulfate corrosion resistance of cement.
Tetracalcium aluminoferrite (C4AF): accounts for about 8-12%. C4AF has a relatively small effect on the strength of cement, but it helps to reduce the firing temperature of cement and reduce production costs.
Raw material selection: High-quality cement clinker production requires the purity and consistency of raw materials. The CaO content of limestone should reach 45-50%, and the Al₂O₃ content of clay should be 20-25%. The quality of raw materials directly affects the chemical composition of clinker and the performance of the final product.
Production process monitoring: During the production process, the temperature, pressure and speed of the rotary kiln need to be monitored in real time. For example, the temperature of the rotary kiln needs to be maintained at 1400°C to 1450°C to ensure that the chemical reaction of the clinker is completely carried out. At the same time, online analytical instruments are used to detect gas components such as CO₂ and NOx to ensure the efficiency and environmental protection requirements of the combustion process.
Final product testing: After the clinker production is completed, detailed quality testing is required, including cement strength testing, chemical composition analysis and particle size testing. Generally, the compressive strength of cement clinker must meet national standards, and the calcium silicate content should be between 50-60% to ensure its performance and stability in use.
Environmental protection technologies for cement clinker rotary kilns include waste gas treatment and emission reduction measures. Effective measures must be taken to control carbon dioxide (CO₂), nitrogen oxides (NOx), sulfur oxides (SOx) and dust emitted during the production process.
The flue gas desulfurization (FGD) system reduces SOx emissions by 50-95% by reacting limestone slurry with sulfur dioxide to produce calcium sulfate. Nitrogen oxide control uses selective catalytic reduction (SCR) technology to add ammonia or urea at high temperature to reduce NOx to nitrogen and water, with an emission reduction rate of 70-90%.
The waste gas recovery system recycles the heat in the waste gas to improve energy efficiency and reduce CO₂ emissions. Using renewable fuels (such as biomass fuels) instead of traditional fossil fuels can reduce CO₂ emissions by 20-30%.
The rotary kiln cooling system uses gas or water cooling to quickly reduce the clinker temperature from 1400°C to below 100°C to prevent over-burning and crystal phase instability. Gas coolers, such as air coolers, use 8 fans to reduce the clinker temperature and recover the heat generated during the cooling process, thereby improving energy efficiency. Water cooling uses cooling water to pass through the clinker bed for uniform cooling, which usually produces a lot of water vapor.
The quality of cement clinker is directly affected by the raw material ratio. The production of cement clinker in a rotary kiln usually involves limestone (providing CaO), clay (providing SiO₂ and Al₂O₃), iron ore (providing Fe₂O₃) and other auxiliary materials. Optimizing the ratio of these raw materials can ensure the generation of stable mineral components such as tricalcium silicate (C₃S), dicalcium silicate (C₂S), tricalcium aluminate (C₃A) and tetracalcium aluminoferrite (C₄AF) during high-temperature calcination, which are essential for cement quality.
The method of optimizing the ratio includes chemical composition analysis of raw materials to ensure that the main components (such as CaO, SiO₂, Al₂O₃ and Fe₂O₃) are within the expected range. In theory, the raw material ratio should make the specific surface area of the final clinker between 4000-5000 cm²/g, the content of tricalcium silicate accounts for 40%-60%, and the content of dicalcium silicate accounts for 20%-30%. The common raw material ratio is about 3:1 by mass ratio of limestone to clay, and the addition of iron ore is usually 1%-2% of the total raw materials. This ratio can ensure that the ratio of C₃S and C₂S meets the standard, thereby ensuring the strength and stability of cement. By adjusting the raw material ratio, the burning characteristics of the raw materials can also be optimized to ensure that the formation of C₃S reaches more than 45%, while controlling C₂S in the range of 25%-30%.
For high-strength cement, the content of C₃A should be moderate, usually 7%-10%. In actual applications, some cement plants have significantly improved the early strength of cement by adjusting the raw material ratio to increase the C₃S content from 40% to 45%. In another case, precise control of the ratio of SiO₂ to Al₂O₃ successfully stabilized the specific surface area of cement at more than 5000 cm²/g, improving the uniformity and performance of the final product. Computational chemistry models and optimization algorithms (such as linear programming or nonlinear programming) can handle complex chemical reaction equations and provide the optimal raw material ratio.
These tools calculate through chemical thermodynamic models to ensure that the raw material ratio can form a suitable liquid phase in the kiln, thereby improving the sintering efficiency of the clinker.
Petroleum coke is used as a fuel in rotary kilns, providing high energy efficiency and temperature control.
Dolomite is added to clinker production to enhance the lime content and adjust the chemical balance in the kiln.
Red mud, a byproduct of bauxite refining, can be used as a raw material to replace some limestone in clinker production.
Waste tires are used as an alternative fuel source in rotary kilns, reducing carbon emissions and energy costs.
Paper sludge is an industrial waste that can be used as an alternative material to improve the sustainability of clinker production.
Spent catalysts from industrial processes can be utilized in clinker production to recycle valuable minerals like aluminum and iron.
Municipal Solid Waste is increasingly being used as a fuel source in rotary kilns, reducing waste and providing a cost-effective energy solution.
Calcium sulfate, often derived from industrial byproducts, helps control the setting time of cement during clinker production.
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