Legal analysis: If the operator has legal documents, it is legal, otherwise it is illegal. It may constitute the crime of illegal business operations, which refers to a crime that violates national regulations and commits one of the following illegal business activities. (1) Operating franchises, monopoly items or other restricted items stipulated in laws and administrative regulations without permission; (2) Buying and selling import and export licenses, import and export certificates of origin, and other business licenses stipulated in laws and administrative regulations or approval documents; (3) illegally operating securities, futures or insurance businesses, or illegally engaging in fund settlement business without the approval of the relevant national competent authorities; (4) engaging in other illegal business activities, disrupting market order, and committing serious acts . Whether it is illegal to buy or sell illegally mined river sand shall be determined based on the amount of business: 1. The amount of illegal business for individuals is more than 50,000 yuan, and the amount of illegal business for units is more than 150,000 yuan; 2. The amount of illegal income for individuals is more than 20,000 yuan , the unit’s illegal income exceeds 50,000 yuan.

Legal basis: Article 225 of the "Criminal Law of the People's Republic of China" The following fixed-term imprisonment or criminal detention, together with or solely a fine of not less than one time but not more than five times the illegal income, shall be imposed; if the circumstances are particularly serious, the sentence shall be not less than five years of fixed-term imprisonment and concurrently fined not less than one time but not more than five times the illegal income, or property confiscation:

(1) Operating special items or other restricted items stipulated in laws and administrative regulations without permission;

(2) Buying and selling import and export licenses, import and export origins Certificates and other business licenses or approval documents stipulated in laws and administrative regulations;

(3) Illegal operations of securities, futures, and insurance businesses without approval from relevant national competent authorities, or illegal fund payment and settlement Business;

(4) Other illegal business activities that seriously disrupt market order.