Dolomite magnesite rotary kiln

Dolomite Magnesite Rotary Kiln is a core industrial equipment specifically designed for calcining carbonate minerals such as dolomite and magnesite. It is widely used in the production of magnesia refractories, magnesium alloys, building materials (such as lightweight partition board raw materials), and the chemical industry. Its core function is to decompose dolomite (primarily composed of CaCO₃ and MgCO₃) and magnesite (primarily composed of MgCO₃) through high-temperature calcination, removing the CO₂ from the carbonates to produce products such as light-burned dolomite (CaO and MgO), light-burned magnesite (MgO), or dead-burned magnesia (high-density MgO) that meet subsequent processing requirements.

I. Core Structure:

The structural design of the dolomite magnesite rotary kiln must be adapted to the calcining characteristics of carbonate minerals (such as high decomposition temperature and the need for uniform heating). It primarily consists of a rotating drum, support system, baffles, transmission, head/tail seals, a combustion system (including burners (pulverized coal, natural gas, or liquefied petroleum gas with secondary air preheating), hot air ducts, and a combustion-supporting fan to provide a stable, high-temperature flame within the kiln, control the calcining temperature (light calcination: 700-900°C; heavy calcination: 1500-1600°C), and ensure sufficient carbonate decomposition. The feed/discharge system also constitutes key components.

II. Operating Principle:

The dolomite magnesite rotary kiln processes minerals through the synergistic effect of "continuous material movement + high-temperature pyrolysis." The specific process is as follows: Feeding Stage: Dolomite is crushed to 8-20mm in diameter. Magnesite ore particles enter the upper end (kiln tail) of the rotating drum through a feeder (with air lock function) at the kiln tail.

Preheating and decomposition stage: As the kiln rotates, the material slowly moves along the inclined drum toward the lower end (kiln head) (movement speed 0.5-1m/h). Simultaneously, high-temperature flue gas generated by the kiln head burner (flowing from the kiln head to the kiln tail) preheats the material (temperature rises to 400-600°C), causing the adsorbed and crystalline water in the mineral to evaporate. Subsequently, the material enters the high-temperature zone (700-1600°C), where carbonate decomposition reactions occur (e.g., MgCO₃ → MgO + CO₂↑, CaCO₃・MgCO₃ → CaO・MgO + 2CO₂↑). CO₂ is discharged from the kiln tail with the flue gas (entering the dust collection system). Cooling and discharge stage: The decomposed calcined products (light-burned powder or dead-burned magnesia) are discharged from the kiln head and enter the cooler (which uses air heat exchange to reduce the temperature from over 1000°C to 2000°C). The kiln is heated to below 200°C and finally transported to the finished product bin via a conveyor.

III. Core Performance Features:

Targeted Adaptation to Mineral Properties:

The inner wall lining bricks are made of alkali-resistant materials such as magnesia-alumina spinel to resist corrosion from alkaline substances such as CaO and MgO produced by the decomposition of dolomite/magnesite, extending the life of the lining bricks (up to 12-18 months). The kiln rotation speed and inclination angle are optimized to ensure that the material residence time in the kiln (1.5-3 hours) matches the decomposition reaction cycle, achieving a decomposition rate of over 95%.

High Efficiency and Energy Saving:

The "secondary air preheating" technology (using hot air discharged from the kiln head cooler as combustion air, raising the temperature to 300-500°C) reduces fuel consumption (saving 15%-20% compared to traditional kilns). Furthermore, a precise temperature control system (using an infrared thermometer to monitor the kiln temperature in real time) prevents over- and under-firing.

Environmentally friendly and stable:

The sealing system utilizes multi-layer flakes and graphite seals, keeping dust emissions below 30mg/m³. The drive system utilizes variable frequency speed regulation, allowing for flexible kiln speed adjustment based on material composition and feed rate, ensuring production stability (equipment availability can exceed 90%).

Versatile adaptability:

By adjusting the calcination temperature, kiln atmosphere, and material residence time, both "light firing" (producing active MgO for desulfurization and building materials) and "heavy firing" (producing high-density magnesia for refractory applications) can be utilized to meet the needs of diverse industries.

IV. Application Areas:

Refractory Industry: Dead-burned magnesia is a core raw material for the production of magnesia refractory bricks and monolithic refractories, used for lining high-temperature equipment such as steel blast furnaces and cement rotary kilns.

Magnesium Alloy Industry: Light-burned magnesia can be electrolyzed to produce metallic magnesium, which is then processed into magnesium alloys (used in lightweight components in the automotive and aerospace industries).

Building Materials Industry: Light-burned dolomite can be used as a raw material for lightweight partition boards and cement admixtures, enhancing the strength and corrosion resistance of building materials.

Environmental Protection Industry: Light-burned magnesia powder can be used for flue gas desulfurization (removing SO₂ from flue gases in power plants and steel mills) and wastewater treatment (adsorbing heavy metal ions).

Dolomite Magnesite Rotary Kiln Equipment Parameters: