Method for producing sodium lignosulphonate by utilizing residues obtained by producing ethanol with crop straws as raw materials

The invention discloses a process for producing sodium lignosulphonate by utilizing residues obtained by producing ethanol with crop straws as raw materials and belongs to the field of comprehensive utilization of biological energy and resources. According to the process, the residues obtained by producing ethanol with crop straws are utilized as raw materials, and filtration, evaporation concentration, sulfonation modification and spray drying are performed on the raw materials so as to produce the high-quality sodium lignosulphonate product. The process has the following advantages: the crop straw resources are fully utilized; the residues are prevented from polluting the environment; the sodium lignosulphonate product produced by the method is used as a concrete water reducing agent; and the performance indexes of the sodium lignosulphonate product meet the requirements of first-grade products of high efficiency concrete water reducing agents.