The Three-Product Dense Medium Cyclone (TPDMC) has been widely applied in the coal preparation industry, yet the adaptive optimization of its parameters based on feed characteristics remains under-researched. This study utilizes a semi-industrial experimental platform with a JX300/240 TPDMC to investigate the influence of pump frequency (PF) and four second-stage structural parameters—cylindrical section length (L2cy), overflow pipe insertion depth (Dep2o), overflow pipe diameter (D2o), and conical section length (L2co)—on the separation performance of three feed materials with distinct washability characteristics. Experiments conducted with density tracer particles revealed a distinct hydrodynamic coupling effect: PF and D2o were the only factors modulating inlet pressure (varying from 0.12 to 0.45 bar), which directly altered the clean coal yield. In contrast, L2cy, Dep2o, and L2co primarily influenced the second-stage internal flow field and concentration effect, thereby affecting the yield and ash content of middling coal (gangue). To quantify feed-specific sensitivities, a new index, Near-Gravity-Range Material (NGRM), was proposed. Results demonstrated that Sample-3 exhibited the highest sensitivity to parameter variations, with its middling coal yield variation reaching 41.25% due to its high NGRM of 71%. Furthermore, statistical analyses were conducted to quantify the influence of each parameter on the heavy product partition ratio across different density fractions. Based on these findings, the following targeted optimization strategies are proposed: (1) for feeds rich in the 1.40–1.50 RD range, increasing PF or decreasing D2o is recommended to enhance clean coal yield; (2) for materials dominated by the 1.7 ± 0.10 RD fraction, increasing D2o, PF, or L2cy maximizes middling coal recovery; and (3) for feeds high in the 1.90 ± 0.10 RD fraction, reducing Dep2o, PF, L2cy, or L2co effectively minimizes middling coal contamination by high-density particles.
Zhang et al. (Sat,) studied this question.