How to evaluate the purity of lime production raw materials
The purity of raw materials for lime production (mainly limestone, mainly composed of CaCO3) directly determines the quality and production efficiency of quicklime (CaO) products. It needs to be evaluated through multidimensional indicator testing and scientific methods. The core evaluation system is as follows:
1、 Core component content detection
The primary method for evaluating the purity of CaCO3 is through chemical analysis and instrumental analysis. Chemical method is used to measure the content of calcium carbonate through hydrochloric acid titration, accurately calculating the proportion of effective ingredients in the raw material. The content of CaCO3 in high-quality raw materials should be ≥ 90%; The instrument rules use X-ray fluorescence spectrometer (XRF) to quickly determine the content of elements such as Ca, Mg, Si, etc., which intuitively reflects the purity of raw materials. At the same time, it is necessary to detect impurity content, with a focus on MgCO3 (≤ 2% is recommended, too high will reduce the activity of quicklime), SiO ₂ (≤ 3%, excessive can easily form refractory silicates and affect calcination), as well as harmful elements such as S and P (content should be ≤ 0.1% to avoid corrosion of equipment or environmental pollution of finished products).
2、 Auxiliary evaluation of physical characteristics
Based on the appearance and density, the purity of high-purity limestone can be preliminarily determined. It is mostly greenish gray or grayish white in color, with a uniform texture and no obvious spots or interlayers; Raw materials with high impurity content often contain yellow and brown patterns, and have low density (high-quality limestone has a density of about 2.6-2.8g/cm ³). In addition, a simple calcination experiment can be used to assist in evaluation: taking a small amount of raw material and calcining it at high temperature, if there is less residue and uniform volume shrinkage after calcination, it indicates high purity; If there are many residues and the texture is hard, it indicates that the impurity content exceeds the standard.
3、 Production adaptability verification
Evaluate the purity of raw materials based on the production process requirements of lime, for example, in the production of high activity quicklime, the purity of raw material CaCO3 should be ≥ 92% and impurities should be ≤ 5% to ensure sufficient calcination; The standard for producing lime for ordinary buildings can be appropriately relaxed (CaCO ∝ ≥ 85%). At the same time, it is necessary to test the particle size distribution of the raw materials to avoid insufficient calcination due to uneven particle size, which may affect the purity of the finished product. Through systematic testing and process adaptability evaluation, the quality of raw materials can be accurately controlled, laying the foundation for lime production.
