The wet-type gravel production process is generally adopted in the south of China or the places where there are abundant water resources. The traditional production processes are coarse crushing process, secondary crushing process, and fine crushing process. Stones are processed by crushers. The particle size of the processed stones is less than 25mm. Then they are ground by the rod grinding mills. And the mud and stone powder are removed by the spiral classifiers in the gravel production line. This kind of process was widely used in the artificial sand making in various hydroelectric construction sites in the mid 1990s. With the application of the PL vertical shaft impact crushers in artificial gravel making, many industries which adopt the PL vertical shaft impact crushers have developed fast, such as the hydroelectric industry, the construction industry, and so on.
Nowadays, the PL vertical shaft impact crushers, vibrating screens, and sand washers are adopted in most hydroelectric industry and construction industry, which can replace the secondary crushers, the fine crushers, and the spiral classifiers. On one hand, in the gravel production line, the small weathered stones and clay of the materials can be removed by the vibrating screens. On the other hand, the big blocks of stones are fed into the coarse crushing equipment. After the coarse crushing process, the crushed stones are sent into the secondary crushing equipment. Then they are screened previously. The big blocks of stones should be sent into the secondary crushing equipment again for recycling process.