Dewatering and water recycling operations in mineral concentration processes lead to not only cost-effective water use, but also less waste disposal to the environment. In this study, optimization of dewatering process in Zareshouran gold processing plant is carried out using HYDROCYCLONE containing circuit. For this purpose, 12 experiments using 4 spigots with 2, 3, 6, 9 mm diameter, and in 3 operation state of spray discharge, transition state and rope discharge have been conducted. Dewatering capability of HYDROCYCLONE is evaluated based on solid weight percent and solid recovery of underflow stream. The results indicate that in the same operation state, increase in spigot diameter leads to an increase in solid recovery and a decrease in solid weight percent of underflow stream. On the other hand, as the operation state tends to rope discharge solid weight percent and solid recovery of underflow increases simultaneously. Therefore, it can be stated that spray discharge pattern has a higher dewatering capability. Using a spigot with 6mm diameter in the operation state of spray discharge, solid recovery and solid weight percent reaches 75 and 61%, respectively. In this condition, if HYDROCYCLONE is considered as the first step of dewatering process, 75% of the feed solid content can be directly transferred to tailings dam at a lower cost. On the other hand, the overflow stream carries only 25% of feed solid content. If pressure filter present in current dewatering system are considered as the second step of dewatering process, their feed slurry will be reduced by 75%. This means an overall increase in dewatering system capacity by HYDROCYCLONE.