In the field of new energy and battery materials, lithium carbonate is an important raw material for lithium battery cathode materials, and its production process is particularly critical. Today, we will discuss in depth an important link in the production process of lithium carbonate - the roasting of spodumene in the rotary kiln, and bring you a super comprehensive guide.

Lithium carbonate rotary kiln
In the process of producing lithium carbonate in a lithium carbonate rotary kiln using spodumene as raw material, the sulfuric acid production process demonstrates the maturity and efficiency of its technology. The core of this process lies in the replacement reaction of sulfuric acid and spodumene at 250~300°C to generate lithium sulfate. However, this reaction has certain requirements on the structure of spodumene, and spodumene with a looser structure is more suitable for this reaction.
In the process flow, the selected spodumene ore needs to be roasted at high temperature in a lithium carbonate rotary kiln to make its structure more loose and create conditions for subsequent reactions. The roasted ore is cooled and mixed with a sufficient amount of sulfuric acid, and then roasted with sulfuric acid in an acidified rotary kiln at 250°C to ensure that the sulfuric acid reacts fully with spodumene and displaces lithium ions.
After the reaction is completed, lithium ions are gradually purified through steps such as water immersion, pH adjustment, and impurity removal. In particular, we will use chemical reagents such as limestone and sodium carbonate to finely adjust the pH value of the solution to remove impurities such as calcium, magnesium, iron, and aluminum in the solution to ensure the purity of the final product.
Finally, through evaporation concentration, precipitation, centrifugal dehydration and other process steps, we obtained high-quality lithium carbonate products. It is worth mentioning that the recovery rate of the entire sulfuric acid production process is as high as about 90%, which is due to its efficient and precise chemical reaction control and physical separation technology.

Lithium carbonate rotary kiln production process principle
Raw materials such as lepidolite and spodumene mixed with other mixtures enter the cylinder from the kiln tail barrel at high temperature for roasting. In the accompanying kiln, the materials move radially and horizontally due to the inclination and rotation of the kiln body. The materials are brought to a high place and exchange heat with the high-temperature flue gas, thereby producing a thermal reaction, thereby achieving the roasting process. Purpose. The kiln speed is adjusted by a variable frequency motor, and the residence time in the kiln can be adjusted according to the reaction time requirements of the reaction materials. The burner is equipped with natural gas flow and air volume monitoring and adjustment functions to meet the adjustment functions of flue gas temperature and flow rate, thereby adapting to the roasting of raw materials. Interval temperature.
The 6% spodumene concentrate containing Li2O is heated at a temperature of 1070 to 1100°C to transform from α type to β type. p spodumene is mixed with 40% excess sulfuric acid according to theoretical calculation, and roasted at a temperature of 250 to 300°C. The roasting material is leached with water, the liquid-to-solid ratio is 1.5 to 2, the temperature is 80°C, the net leaching time is 30 minutes, and the material fineness is 0.074mm (+200 mesh) accounting for 10% to 15%. The leaching slurry is filtered, and the filter residue is sent to the residue yard after 4 to 5 reverse washes. After adding soda ash to the leach solution to remove calcium, magnesium, silicon, iron and other impurities at room temperature, it will contain Li2O 50~60g/l. Concentrate to 180~200g/L. Add soda ash with a theoretical excess coefficient of 1.05 to the concentrated solution, and stir to precipitate lithium carbonate at a temperature of 95°C. The crude lithium carbonate was washed with 95°C pure water and dried at 350°C. The lithium precipitation mother liquor recovers sodium sulfate and then returns to the evaporation process to further recover lithium.
Lithium carbonate rotary kiln is used for transformation roasting and sulfation roasting of spodumene concentrate respectively, and is heated directly by heavy oil or gas. The calculation of the lithium carbonate rotary kiln used for transformation roasting can be estimated based on the actual production capacity of the clinker unit of 20-30kg/(m2.h). The calculation of the lithium carbonate rotary kiln used for sulfation roasting can be estimated based on the actual production capacity of the acidizing material unit 82 ~95kg/(m2.h) estimated.
For the filtration of the leaching slurry in the lithium carbonate rotary kiln production process flow chart, an external filter drum vacuum filter is used in production. The common specifications are 20 to 100m2 based on the filter area, and its production capacity is calculated based on the filter residue (dry basis). 200220kg/(m2.h).
In the lithium carbonate rotary kiln production process flow chart, the evaporator is used to concentrate the purification liquid for lithium precipitation. The natural circulation external heating type is used in the production. For three-effect vacuum evaporation, according to production experience data, the evaporation intensity is 15~20kg/(m2.h), and the steam consumption per kilogram of water evaporated is 0.4~0.45kg.
The infrared dryer in the lithium carbonate rotary kiln production process flow chart is domestically produced LH-1 and LH-3 types, with an actual production capacity of 300kg/h. Some also use turbine dryers, with a production capacity of 2 to 3t. /h.

Lithium carbonate rotary kiln production process workshop configuration
In our lithium carbonate rotary kiln production process workshop, the entire production layout is strictly divided into the fire process area and the wet process area to achieve an efficient and professional operation process.
The fire method area is mainly responsible for the two key links of transformation roasting and sulfation roasting. This area is equipped with advanced roasting equipment, which can ensure that raw materials complete precise chemical reactions at high temperatures, laying a solid foundation for subsequent processes. At the same time, considering the impact of dusty flue gas and sulfur dioxide generated during the roasting process on the environment, we have specially installed efficient dust removal and desulfurization equipment to ensure that exhaust gas emissions comply with environmental standards.
The wet process area covers many important steps such as leaching filtration, purification, evaporation, lithium precipitation, product drying, packaging and mother liquor recovery. In order to ensure the smooth progress of these processes, we use corrosion-resistant materials and equipment. Especially for the sodium sulfate recovery process, we designed an independent operating area to avoid interference with the main product production line. In addition, we have also introduced an automated control system to accurately control various process parameters, thereby improving product quality and production efficiency.
In terms of workshop layout, we fully considered factors such as wind direction, ventilation and exhaust. The exhaust gas treatment system, purification equipment and sodium sulfate recovery device of the lithium carbonate rotary kiln are strategically placed on the upper floors of the workshop to ensure timely discharge of waste gas and maintain air circulation inside the workshop. This layout not only helps improve the quality of the work environment but also ensures production safety.

Technical characteristics of lithium carbonate rotary kiln production process
The technical characteristics of the lithium carbonate rotary kiln production process are mainly reflected in the following aspects:
First of all, it has excellent environmental performance. We use efficient purification treatment technology for the flue gas generated during transformation roasting and sulfation roasting. After careful treatment, the dust content of the flue gas generated by transformation roasting can be reduced to less than 150 mg/m3, ensuring that the emissions comply with strict environmental protection standards. For the sulfur dioxide-containing tail gas produced by sulfation roasting, we also use advanced purification technology to reduce its concentration to below 250mg/m3 before discharging it to minimize the impact on the environment. In addition, flue gas washing water must undergo special purification treatment before being discharged, which further reflects our commitment to environmental protection.
Secondly, production stability and continuity are another major feature of our process. In order to ensure the stability of the production environment and the long-term safe operation of the lithium carbonate rotary kiln, we pay special attention to the stability of power supply and water supply in the fire method part. This is because any power or water outage can cause production disruptions, which can impact product conversion and leaching rates. Therefore, we are equipped with multiple backup power and water sources to ensure the continuity and stability of the production process.
Furthermore, we have taken professional anti-corrosion measures in view of the corrosiveness of lithium precipitation mother liquor and sodium sulfate-containing solution to the concrete structure of general factory buildings. By using high-performance anti-corrosion coatings, corrosion-resistant building materials, and regular testing and maintenance, we effectively extend the service life of our plants and equipment, while also ensuring the safety of the production process.

Advantages of lithium carbonate roasting rotary kiln for roasting lithium ore
The technical advantages of lithium carbonate roasting rotary kiln in roasting lithium ore are very significant, which are reflected in the following aspects:
First, its high output characteristics make the rotary kiln very suitable for large-scale industrial production. Through a continuous and efficient calcination process, large quantities of ore can be processed to meet the high market demand for lithium carbonate.
Secondly, the open calcination method adopted by the rotary kiln gives it unique advantages. The kiln body design is simple and efficient, ensuring smooth air flow. This design allows the sulfur-containing flue gas to be discharged in time, effectively avoiding the adhesion of sulfur to the product, thus ensuring the low sulfur content of the product, fully complying with the strict requirements of the steelmaking industry. At the same time, the uniform rolling and heating of materials in the rotary kiln ensures the stability and uniformity of product quality and greatly reduces the ratio of raw and over-fired.
In addition, the rotary kiln is equipped with a vertical preheater at the end of the kiln, which is an innovative technology. It can make full use of the high-temperature flue gas generated in the rotary kiln to effectively preheat the ore from a normal temperature state to an initial decomposition state. This preheating mechanism not only significantly increases the output of the rotary kiln, but also significantly reduces the heat consumption per unit product, achieving efficient use of energy.
In the kiln head part, the configuration of vertical cooler further improves production efficiency. It can quickly reduce the temperature of high-temperature materials and increase their activity, providing great convenience for subsequent transportation and storage. At the same time, the vertical cooler can also generate high-temperature secondary air, which is effectively used to increase the firing temperature in the kiln, further reducing fuel consumption.
Finally, the environmental performance of the rotary kiln is also worthy of praise. The temperature of the flue gas discharged from the vertical preheater at the end of the kiln is controlled between 280-350°C, and the dust content is extremely low, only about 20g/Nm3. This feature makes the subsequent flue gas treatment process simpler and more efficient, and can easily meet environmental protection standards, achieving a dual victory of economic benefits and environmental responsibility.

In summary,
The process of roasting spodumene in a lithium carbonate rotary kiln is an important part of modern industrial production of lithium carbonate. By in-depth understanding and mastering the process, technical characteristics and advantages of this process, we can better optimize the production process, improve product quality, reduce production costs, while achieving environmentally friendly and sustainable development.


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