Sand is a common material, and relevant certificates are needed when buying and selling. Operators are legal if they have legal documents, otherwise they are illegal. Crime of illegal business operation: Whoever, in violation of state regulations, commits one of the following illegal business operations and disrupts the market order, if the circumstances are serious, shall be sentenced to fixed-term imprisonment of not more than five years or criminal detention, and shall also, or shall only, be fined not less than one time but not more than five times the illegal income; If the circumstances are especially serious, he shall be sentenced to fixed-term imprisonment of not less than five years, and shall also be fined not less than one time but not more than five times the illegal income or his property shall be confiscated: he engages in franchise, monopoly goods or other commodities whose business is restricted by laws and administrative regulations without permission; Buying and selling import and export licenses, import and export certificates of origin and other business licenses or approval documents stipulated by laws and administrative regulations; Illegal operation of securities, futures and insurance business, or illegal operation of fund payment and settlement business without the approval of the relevant competent departments of the state; Other illegal business practices that seriously disrupt market order. Legal basis: Article 225 of the Criminal Law of People's Republic of China (PRC): Crime of illegal business operation: in violation of state regulations, one of the following illegal business operations is committed, disrupting market order and the circumstances are serious; Be sentenced to fixed-term imprisonment of not more than five years or criminal detention, and concurrently or exclusively be fined not less than one time but not more than five times the illegal income; If the circumstances are especially serious, he shall be sentenced to fixed-term imprisonment of not less than five years, and shall also be fined not less than one time but not more than five times his illegal income or his property shall be confiscated: (1) dealing in franchise, monopoly goods or other commodities whose business is restricted by laws and administrative regulations without permission; (2) buying and selling import and export licenses, import and export certificates of origin and other business licenses or approval documents stipulated by laws and administrative regulations; (three) without the approval of the relevant competent departments of the state, illegally engaged in securities, futures, insurance business, or illegally engaged in fund payment and settlement business; (four) other illegal business activities that seriously disrupt the market order.