Basalt is a basic extrusive rock with a chemical composition similar to that of gabbro or diabase. The silicon dioxide content varies between 45% and 52%. It has high hardness, is difficult to process, and has relatively high requirements on machine performance.

According to the characteristics of basalt, the "four-stage, vertical shaft impact crusher and rod mill combined sand making" process can be adopted, in which the four-stage crushing can be equipped with: jaw crusher + single-cylinder hydraulic cone crusher + multi-cylinder hydraulic cone crusher + vertical shaft impact crusher. The main workshop layout is: coarse crushing workshop, medium crushing workshop, screening workshop, sand making workshop, inspection and screening workshop, coarse and fine aggregate storage yard, etc.

In view of the characteristics of low basalt sand making rate, high fineness modulus of finished sand and low stone powder content, the following corresponding measures can be adopted:

1. Increase the rotor speed of the vertical shaft impact sand making machine, increase the linear speed of the aggregate in the crushing chamber (the system takes 65m/s), increase the sand formation rate and the stone powder content of the crushed sand, and at the same time reduce the fineness modulus of the sand.

2. Adjusting the feed gradation of the vertical shaft impact crusher can greatly improve the sand making effect.

3. The aggregates less than 5 mm produced by the production line system after coarse crushing, medium and fine crushing have a high content of stone chips. The process allows this part of aggregates to not be produced as finished products, and all the aggregates less than 5 mm after medium and fine crushing enter the vertical shaft impact crusher for shaping to control the quality of the finished sand.

4. The aggregates graded by the second screening workshop after vertical shaft impact crushing, some coarse particles <5mm (mainly 3-5mm) are not produced as finished materials, and are sent to the rod mill for re-crushing to adjust the fineness modulus and stone powder content of the finished materials.

5. When the vertical shaft impact crusher makes sand, the lower the moisture content of the processed aggregate, the better the sand making effect. According to this feature, the system adopts full dry production to improve the sand making effect of the sand making machine.