Quality inspection standards and methods for calcined lime in vertical kiln
The quality inspection of calcined lime in shaft kiln shall be comprehensively evaluated from physical, chemical and activity aspects. In terms of physical detection, the particle size analysis adopts the sieving method, and the particle size distribution is measured through 8mm, 4mm, 2mm and other standard sieves to ensure that the proportion of 2-8mm particles meets the requirements of the metallurgical industry; For appearance inspection, the block shape, surface flatness and color shall be observed. The high-quality lime shall be white or offwhite without cracks, holes and impurities. Density detection is based on Archimedes principle. Density value is calculated by weighing in water. Density abnormality may reflect insufficient calcination or raw material problem.
In chemical detection, calcium oxide content is the core index. EDTA complex titration method or acid titration method shall be adopted, and the content shall be ≥ 85%; The content of magnesium oxide shall be controlled below 5% and determined by flame atomic absorption spectrometry; Impurity detection covers SiOAlOFe, etc. Gravimetric or ICP-AES techniques are used to ensure that the total of impurities is ≤ 5%.
The activity is measured by the hydration method. Put 50g lime sample in 40 ℃ water and stir for 10 minutes. Titrate the reacted solution with hydrochloric acid. Express the activity with milliliters of hydrochloric acid consumed in 10 minutes. The activity of high-quality lime should reach 280-330ml. This standard system can fully guarantee the performance requirements of lime in metallurgy, construction and other fields.
