Effect of minerals in coal used for producing acetylene from calcium carbide on lime burning

In Inner Mongolia, many kilns used for burning lime rely on coal as fuel; our company plans to switch to water gas for the calcination of limestone. The magnesium oxide content in limestone is very high, much higher than that of impurities in coal. This leads to coking and nodulation in gas-fired kilns, which affects the yield of lime, increases the amount of uncalcined limestone, and in severe cases can render the gas-fired kilns unusable.

“It is mainly manifested in the fact that gas-fired kilns are prone to coking and nodulation, which does not affect the lime production but increases the amount of uncalcined limestone; in severe cases, this can render the gas-fired kilns unusable. ”Does this sentence mean that directly calcining lime using coal causes the calcination kiln to be prone to coking, resulting in an increased amount of uncalcined limestone in the resulting lime? Furthermore, what impact will directly calcining minerals with coal have on using calcium carbide slag as building material? Are there any process equipment available for indirectly heating limestone for calcination using coal at present? What are the advantages of using water-gas to calcine limestone? Please give me some advice. Thank you!

“It is mainly manifested in the fact that gas-fired kilns are prone to coking and nodulation, which does not affect the lime production but increases the amount of uncalcined limestone; in severe cases, this can render the gas-fired kilns unusable. ”Does this sentence mean that directly calcining lime using coal causes the calcination kiln to be prone to coking, resulting in an increased amount of uncalcined limestone in the resulting lime? Yes. Additionally, what impact will the minerals resulting from direct calcination with coal have on using calcium carbide slag as a building material? Limestone needs to be screened, with little impact on calcium carbide slag. Are there any process equipment available for indirectly heating limestone for calcination using coal at present? Isn’t indirectly calcining limestone just converting it into water gas? What are the advantages of using water-gas to calcine limestone? Please give me some advice. Thank you! From the overall development trend, China’s production equipment for active lime should be based domestically. Whether in terms of the adaptability of production capacity or the ability to make full use of high-quality limestone mine resources, rotary kilns have excellent prospects for development. Advantages of using rotary kilns for calcining active lime. From an overall development perspective, the production equipment for active lime in China should be developed domestically. Whether in terms of the adaptability of production capacity or the ability to make full use of high-quality limestone mine resources, rotary kilns have excellent prospects for development. The advantages of using a rotary kiln for calcining active lime are as follows: 1. Rotary kilns have high production capacities, making them highly suitable for large-scale active lime production lines; currently, there are already rotary kilns capable of producing 2,200 tons of lime per day in use around the world ； Many rotary kilns with a daily production capacity of 150–300 tons of lime have been built both domestically and internationally; they operate well and are also suitable for use in small and medium-sized lime manufacturers. 　　2. The rotary kiln is used for open-type calcination; it has a simple structure and smooth air flow, which allows sulfur-containing flue gas to be discharged promptly. Sulfur from the fuel does not tend to accumulate, as a result of which the sulfur content in the product is low, meeting the requirements for steel production. At the same time, the material rolls forward evenly within the kiln, ensuring uniform heating and stable product quality; the rates of underburning and overburning are very low, allowing for the calcination of lime with high reactivity for use in steelmaking. Under the same conditions, the activity of lime produced in rotary kilns is higher than that produced in gas-fired kilns, being on average more than 30 ml higher; the activity level is generally between 340 and 380 ml, and can even reach 400 ml. 　　3. Rotary kilns can directly calcine limestone in the fine particle size range of 10–50 mm. In general, limestone with a fine particle size of 0–30 mm accounts for 30–40% of the total output from mines; this type of limestone cannot be utilized in other types of kilns. Furthermore, with the ‘refinement’ of steel raw materials, sintering increasingly uses quicklime instead of limestone, resulting in fine-grained limestone not being utilized comprehensively. Building a rotary kiln production line not only allows for the full utilization of high-quality limestone mine resources but also aligns with the sustainable development principles of the lime industry. 　　4. Installing a vertical preheater at the tail end of the kiln allows for the full utilization of the high-temperature flue gas generated during calcination in the rotary kiln, thereby preheating the limestone from room temperature to its initial decomposition state. This not only **increases the output of the rotary kiln, but also significantly reduces the heat consumption per unit of product. 　　5. Installing a vertical cooler at the kiln head not only allows for the rapid cooling of hot lime, thereby increasing its reactivity, but also facilitates its transportation and storage. At the same time, secondary air entering the kiln at a higher temperature can also be obtained. It can effectively increase the firing temperature inside the kiln and reduce fuel consumption. 　　6. The flue gas discharged from the vertical preheater at the end of the kiln has a low temperature, ranging between 280–350°C, and a low dust content of about 20 g/Nm3. This makes the subsequent flue gas treatment processes simpler and more efficient, enabling compliance with environmental regulations. 　　7. The stable quality of lime in the rotary kiln is its greatest advantage.