Abstract: In order to verify the stability of the small-scale test process of an ultra-pure iron con⁃ centrate and the rationality of the technical indicators，an expanded continuous test is carried out for the high-grade iron concentrate.The test results show that under the optimum test conditions of grinding fine⁃ ness of -0.038 mm 95%，magnetic field strength of one roughing and one cleaning of low intensity mag⁃ netic separation of 126 kA/m and 80 kA/m respectively，water rising of 1.0 m3 /h of elutriation magnetic separation，dosage of reverse flotation roughing adjusting agent Na2CO3 and collector MK618 of 253 g/t and 54 g/t respectively，dosage of cleaning collector MK618 of 18 g/t，the process of grinding-one rough⁃ ing one cleaning low intensity magnetic separation-elutriation-reverse flotation is used in the expanded continuous separation test，and the ultra-pure iron concentrate with yield of 37.31%，total iron grade of 71.54% and SiO2 content of 0.129% is obtained.The technical indexes of the continuous separation test are basically the same as those of the laboratory test. The operation of the continuous separation process is sta⁃ ble，which can provide reliable technical support for the subsequent design of the industrial production line of the ultra-pure iron concentrate.

Key words: ultra-pure iron concentrate, magnetic separation, flotation, expanded continuous separa? tion test