Main Factors Affecting Lime Calcination Quality

Main Factors Affecting Lime Calcination Quality

1. Limestone quality and particle size: The CaO  content and crystal structure of limestone are the prerequisites for burning high-quality lime, and the reasonable ratio of limestone particle size (large/small= 2/1) can improve the state of air flow in the furnace and strengthen the material pyrolysis results.

2. Selection of calcination kiln type: A calcination kiln with a reasonable structure can create conditions for the production of "lightly burned" lime. The fire point is evenly distributed, the logistics and the temperature of each section are properly controlled, and the calcined fruit is good.

3. Selection of calcination kiln type: A calcination kiln with a reasonable structure can create conditions for the production of "lightly burned" lime. The fire point is evenly distributed, the logistics and the temperature of each section are properly controlled, and the calcined fruit is good.

4. Other factors: the operation mode of the furnace charge, the way of feeding and ash discharge, the sealing effect of the kiln body, the level of automatic control of production, the technical quality of workers, etc.

B.  Ways to improve the quality of lime used in steelmaking

1. Start from the quality of raw materials and fuels: raw materials are the foundation, and high-quality ores with excellent composition, reasonable particle size and clean surface should be selected from the beginning of ore dressing. The fuel should also be selected according to the specific conditions of the enterprise to choose high-quality fuel with few impurities and easy to obtain, so as to ensure loose raw material and fuel supply conditions. Gas fuel should consider its calorific value and pressure.

2. It is necessary to formulate a reasonable calcination system: theoretical analysis of limestone decomposes at around 900 °C, and the heat supply is ≥630 Kcal/Kg, but it is subject to the specific conditions of the enterprise (such as ore structure, fuel supply, kiln heat transfer rate and CO2 gas diffusion, etc.) Due to environmental constraints, the maximum heating temperature and heating capacity are adjusted accordingly. A reasonable calcination system must be established to ensure the realization of the "light burning" (soft burning) process of limestone.

3. Select an appropriate and reasonable modern advanced kiln type: After various original conditions are met, an advanced kiln type with a certain equipment level should be selected. Now there are many types of calcination kilns, and enterprises should make decisions on the type of lime calcination kiln to be built based on comprehensive analysis of factors such as production scale, lime product quality requirements, general layout, raw material conditions, and investment capabilities.

4. Strict and scientific management, formulating various reasonable rules and regulations: Any advanced production line, as a system engineering, must be people-oriented and cultivate professional talents in order to produce good products. It is necessary to formulate scientific operating procedures and rules and regulations from all aspects of mining, mineral processing, batching, calcination, and automatic control, and strictly implement them.

C. What kind of kiln is needed for calcination of lime

The clinker produced by the lime kiln also has new uses. The main thing that is produced by the lime kiln is quicklime, and the quicklime can be used as a desulfurizer. The iron and steel industry, calcium carbide industry, alumina industry, refractory materials and other industries are all major lime consumers, and these industries have been developing rapidly in the past two years. The annual output is basically growing at a rate of more than 20%. However, lime, the main material (auxiliary material) they need, did not increase correspondingly, which caused a shortage of lime, which stimulated a large number of social soil lime kilns, and the blooming of soil-fired kilns caused serious pollution to the environment. Under such circumstances, national and local governments have successively issued a series of policies and regulations to remediate earth-fired kilns, but it is difficult to achieve the expected results because of the stimulation of demand. Therefore, in order to control the pollution of earth-fired kilns, it is necessary to implement modern new technology lime kilns to solve the problem of demand. In this way, not only the environment can be protected, but also the lime produced by it is not only of good quality but also of low cost. For enterprises utilizing this new technology, the economic benefits will increase significantly. This is the practical significance of promoting new technology lime kiln.
Lime kiln is mainly composed of kiln body, feeding device, material distributing device, combustion device, ash unloading device, electrical appliances, instrument control device, dust removal device and so on. Different forms of lime kilns have different structural forms and calcination forms, and the process flow is basically the same, but the value of equipment is very different. Of course, there must be differences in the results of use.

Its technological process is that limestone and fuel are loaded into the lime kiln (if the gas fuel is fed through a pipeline and a burner), preheated and then decomposed at 850°C, and calcined at 1200°C, and then cooled and discharged out of the kiln. That is, the production of quicklime products is completed. Different kiln shapes have different preheating, calcination, cooling and ash discharge methods. But there are several process principles that are the same: high quality raw materials, good lime quality; high fuel calorific value, low quantity consumption; limestone particle size is proportional to calcination time; quicklime activity is inversely proportional to calcination time and calcination temperature.

石灰窑主要由窑体、上料装置、布料装置、燃烧装置、卸灰装置、电器、仪表控制装置、除尘装置等组成。不同形式的石灰窑，它的结构形式和煅烧形式有所区别，工艺流程基本相同，但设备价值有很大区别。当然使用果肯定也是有差别的。

它的工艺过程为，石灰石和燃料装入石灰窑（若气体燃料经管道和燃烧器送入）预热后到850℃开始分解，到1200度完成煅烧，再经冷却后，卸出窑外。即完成生石灰产品的生产。不同的窑形有不同的预热、煅烧、冷却和卸灰方式。但有几点工艺原则是相同的即：原料质量高，石灰质量好；燃料热值高，数量消耗少；石灰石粒度和煅烧时间成正比；生石灰活性度和煅烧时间，煅烧温度成反比。