Difference between wet mica powder and dry mica powder

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The identification of wet mica powder and dry mica powder in order to use mica powder correctly, it is often necessary to identify the intrinsic quality of mica powder in industry. Although the granularity, whiteness and moisture of mica powder are easy to determine, the identification of the morphological characteristics and purity of mica powder has become a headache for the production enterprises. Conditional enterprises can use element analysis (such as X-ray fluorescence analysis) to determine the content of various elements, determine the purity of mica; use particle size distribution instrument (such as Coulter particle size meter) to determine the size distribution and specific surface area of important data, determine morphological characteristics. But it is difficult for general factories to meet these requirements.

　　The morphology of dry and wet mica powders differs greatly. Several simple methods for identifying dry and wet mica powders are introduced based on their morphological differences.

　　1. Settlement method: take 10 ml measuring cylinder, add 1 g mica powder, add water 5 ml, shake well, add water to 10 ml scale, shake well. The settlement velocity is observed at rest. Dry mica powder usually settles to the bottom in about 60 minutes, forming about 7 ml of upper clear night. On the contrary, wet mica powder usually forms only about 1.5-3 ml upper layer of clear night, which takes several hours to form about 7 ml upper layer of clear night. The principle is that the wafer of wet mica powder is very thin and has good suspension, while the wafer of dry mica powder is thick and contains more quartz powder, which has poor suspension.

　　2. Density method: The principle is that the wafer of wet mica powder is very thin, and it is difficult to form compact accumulation.

　　A. Loose density method: the powder is fully dispersed, poured into the weighing barrel to a certain scale, weighed and calculated density. The bulk density of wet mica powder is usually about 0.25g/ml, while that of dry mica powder is usually 0.5g/ml.

　　B. Real density method: pour the powder into the weighing barrel, weigh and vibrate (such as tapping lightly on the table) so as to reduce the powder volume until the powder volume no longer drops (usually about 10-15 minutes). Calculate density. The real density of wet mica powder is usually about 0.50g/ml, and that of dry mica powder is between 0.70 and 0.80g/ml.

　　3. Pearlescent effect: take about 0.1-0.2g powder, put it in colorless transparent glass, add water about 60-80ml, stir. The pearlescent effect of wet mica powder is obvious, but that of dry mica powder is poor.