What's the use of flame crystallization in fairyland legend?

In chemistry, after the hot saturated solution is cooled, the solute precipitates in the form of crystals, which is called crystallization. The crystallization process of pure metal occurs in the horizontal line segment of the cooling curve. The experiment shows that when metal crystallizes, liquid metal spontaneously forms several crystal nuclei, and some foreign refractory particles can also act as crystal nuclei, forming non-spontaneous crystal nuclei; With the passage of time, the formed crystal nuclei grow up and continue to produce new crystal nuclei until all the liquid metals disappear and the crystals contact each other. Therefore, the crystallization process is a process of continuous nucleation and growth. Because China's industrial civilization is relatively late, most people don't know much about mineral crystals. As a business card of an international city, Shanghai has held the mineral crystal exhibition for three consecutive years, striving to become an internationally influential exhibition as soon as possible, on a par with the Tucson mineral crystal exhibition in the United States, the Munich mineral crystal exhibition in Germany and the Saint Mary's mineral crystal exhibition in France. Crystallization refers to the process of solid solute precipitation from (supersaturated) solution. Solute precipitated from solution can be roughly divided into crystalline precipitation and amorphous precipitation. Crystalline precipitate can be easily filtered out of the solution. When the crystal particles are larger and more uniform, less mother liquor is entrained, which is easy to wash; Too fine and uneven crystals usually form a sticky paste.