Abstract: Gold in Gouliang gold ore of Chifeng gold plant is mainly associated with chalcopyrite. According to this characteristics of the ore，pre-concentration tests by X-ray radiation were carried out to select the separation threshold values according to the copper content for the particle sizes of 150~90 mm，90~30 mm after the ore was crushed to 150~0 mm. The results demonstrated that when the separation threshold value for 150~90 mm ore is 0.1 and 0.07 respectively，with one roughing and one scavenging，Cu grade of 1.26%，Au grade of 9.80 g/t，Cu recovery of 96.27% and Au recovery of 90.61% were obtained. When the separation threshold value for 90~30 mm ore is 0.06 and 0.04 respectively，with one roughing and one scavening,Cu grade of 1.32%，Au grade of 6.77 g/t，Cu recovery of 98.69% and Au recovery of 96.75% were obtained by preconcentration. The yield of pre-concentration reached 35.08%. The tests results indicated that Au is mainly associated with chalcopyrite，the separation threshold can be determined according to the copper content.

Key words: X-ray radiation separator, Pre-concentration, Au-Cu associated ore, Threshold value