The fine screen of the fine sieving and re-grinding process does not return to the ball mill of the original system, but returns to the specially set regrinder (generally a two-stage or three-stage ball mill). This process is mostly used for the expansion and establishment of the old plant. Newly selected factory. After the United States Erie beneficiation plant in 1965 successfully tested a fine sieve, who first used this process (Figure 1).

The concentrator has 36 beneficiation systems, each of which has a ore supply of 107 t/h and a particle size of -25 mm. The main equipment of each beneficiation system is 1 set of ф3.5×4.3m rod mill, 588KW; 1 set of 1.5×2.4m vibrating screen; 2 sets of 0.9×1.2m double cylinder magnetic separator; 5 sets of ф356mm hydrocyclones; 1 set of ф3.3×4.2m ball mill, 919KW; 4 sets of 0.9×1.5m magnetic separator and 4 sets of 0.76×1.5m three-tube magnetic separator. 3 fine screen regrind systems, each system processing intermediate concentrates of 12 beneficiation systems. These intermediate concentrates were classified by a 0.1 mm fine sieve through a second-stage sieve. The sieve was dehydrated by three 0.9×1.8m dehydration magnetic separators, and then sent to a ф3.5×7.3m regrinder, 919 KW. The discharge of the regrind mill is fed into a three-stage fine sieve with a sieve hole of 0.1 mm, and the sieved material is returned to the mill by a dewatering magnetic separator and then ground. The sieved product is sent to 8 sets of 0.9×1.8m double-tube magnetic separator, the single gangue is discarded, and the first and second-stage sieve products are combined and sent to the rainbow water absorption sorting machine to further discard the quartz and finally concentrate. Use sand pump to lift to the pellet factory. The fine screen regrind system can increase the capacity of the original ore mill by 11% and the mill power by 5.5%.
Following the Yili Concentrator, the US Meramik Concentrator and the Fairline Concentrator have also adopted this selection process. It applies to magnetic micro-fine disseminated iron ore concentrator was a substantial increase iron concentrate grade.

In 1975, the Dagushan Concentrator used this process for industrial testing (Figure 2), which increased the magnetically-selected iron concentrate grade from about 63% to about 65.5%. [next]

In 1977, the fine screen re-grinding and expansion project of Dagushan Concentrator was completed (the process is shown in Figure 3), and the grade of iron concentrate was increased to more than 66%.
The initial selection process of the plant was a closed circuit consisting of a hydrocyclone, a regrinder, and a fine screen, which was replaced by a dewatering magnetic separator, a regrinder, and a fine screening process. In order to solve the problem of excessive circulation on the sieve in the fine screening and regrind process, it was explored to use the spiral chute to treat the sieve tops, and select the concentrate with the operation yield of 44.75% and the grade of 67.69%. The operation recovery rate is 56.43%. , can reduce the amount of regrind by about 40%. The fine screening, re-election, and regrind processes are shown in Figure 4. This process can save 30% of the investment in the selected process part, and reduce production cost and power consumption by 30 to 35%. However, due to difficulties in configuration and complicated processes, it has not yet been adopted by industry.

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