The present work dealt with the preconcentration of rare earth elements in Saghand ore(Yazd province,Iran)which was achieved by Humphrey spiral using orthogonal optimization method after scrubbing the sample at 45%solid pulp density for 30 min.The pulp was diluted and was fed to a Humphrey spiral for upgrading.The process parameters considered were feed size,feed solids and feed rate,and Taguchi’s L9(34)orthogonal array(OA)was selected for optimization of the process.The results show that the feed rate and feed size were more significant than the other operation parameters of the process.It was also found that under optimal conditions,the concentrate grade of rare earth elements increased from2860 10 6to 6050 10 6and recovery reached to 58%. The present work dealt with the preconcentration of rare earth elements in Saghand ore (Yazd province, Iran) which was achieved by Humphrey spiral using orthogonal optimization method after scrubbing the sample at 45% solid pulp density for 30 min. The pulp was diluted and was fed to a Humphrey spiral for upgrading. The process parameters considered as feed size, feed solids and feed rate, and Taguchi’s L9 (34) orthogonal array (OA) was selected for optimization of the process. The results show that the feed rate and feed size was more significant than the other operation parameters of the process. It was also found that under optimal conditions, the concentrate grade of rare earth elements increased from 2860 10 6to 6050 10 6 and recovery reached to 58%.