Flow Field Evolution in Spiral Concentrator and Separation Index Prediction of Hematite and Quartz with Different Particle Sizes

doi:10.12068/j.issn.1005-3026.2025.20240128

Abstract

Abstract:

The hydrodynamic characteristics serve as fundamental factors in determining the gravity separation effect. Numerical simulations were used to systematically investigate the evolution of fluid dynamics parameters along the longitudinal travel in a $ϕ$ 400 mm spiral concentrator. For the two feeding systems comprising 90 μm hematite with 38 μm quartz and 59 μm hematite with 38 μm quartz，the variations in particle distribution， migration behavior， and separation efficiency were analyzed. The results indicate that the morphology of the flow film， the velocity distribution， and the intensity of the secondary circulation change significantly within the travel of the first turn， and it takes longitudinal travel of 2~3 turns to stabilize； the stabilization travel is positively correlated with the radial position. Hematite and quartz gradually develop a selective distribution， and the maximum separation efficiency improves overall with the travel. The distribution region of 90 μm hematite is more toward the inner edge， and its migration amount reaches the equilibrium in the 2nd turn； the maximum separation efficiency obtained is 82.16%. The distribution region of 59 μm hematite is more outward， and the migration equilibrium is not reached until the 3rd turn. The maximum separation efficiency obtained in the 2nd and 3rd turns is about 6% lower than that of the 90 μm hematite system. The motion behavior of coarse-grained hematite has an obvious correlation with the evolution of the flow film and velocity distribution. However， the motion of fine-grained hematite exhibits a certain degree of randomness. Consequently， it is necessary to extend the travel or adjust related structural parameters to acquire a satisfactory technical index.

Key words: spiral concentrator, fluid dynamics parameter, stabilization travel, migration of particle, maximum separation efficiency

CLC Number:

TD 45

Qian WANG, Shu-ling GAO, Xiao-hong ZHOU, Chun-yu LIU. Flow Field Evolution in Spiral Concentrator and Separation Index Prediction of Hematite and Quartz with Different Particle Sizes[J]. Journal of Northeastern University(Natural Science), 2025, 46(12): 94-103.

Figures/Tables 17

Fig.1 Schematic diagram of cross-sectional shape of spiral concentrator

Table 1 Structural parameters of spiral concentrator

直径 $ϕ$ /mm	外半径R/mm	内半径r₀/mm	下斜角γ/(°)	螺距P/mm	圈数N
400	200	35	12	240	3.25

Table 1 Structural parameters of spiral concentrator

直径 $ϕ$ /mm	外半径R/mm	内半径r₀/mm	下斜角γ/(°)	螺距P/mm	圈数N
400	200	35	12	240	3.25

Fig.2 Fluid domain meshing of single-turn spiral concentrator

Fig.3 Mesh independence verification on spiral concentrator

Table 2 Spatial discretization patterns for different solving models

项目	气-液两相流	气-液-固多相流
梯度	Least Squares Cell Based	Least Squares Cell Based
压力	PRESTO	—
动量	Second Order Upwind	QUICK
体积分数	Compressive	Compressive
湍流动能	Second Order Upwind	QUICK
湍流耗散率	Second Order Upwind	QUICK

Fig.4 Radial distribution of flow film thickness across different turns in the trough

Fig.5 Evolution of maximum tangential velocity

Fig.6 Contour of radial velocity distribution across different turns in the trough

Fig.7 Evolution of maximum inward velocity along

Fig.8 Evolution of maximum outward velocity along

Fig.9 Yield of hematite in various radial regions

Fig.10 Yield of quartz in various radial regions

Table 3 Yield variation of 90 μm hematite particles in different radial regions

纵向行程/圈	内半槽产率变化/%				外半槽产率变化/%
纵向行程/圈	r₁	r₂	r₃	总和	r₄	r₅	r₆	总和
0.25→0.50	-1.14	9.66	15.57	24.09	-2.21	-14.98	-6.90	-24.09
0.5→0.75	1.65	23.89	-7.12	18.42	-15.08	-3.34	0.00	-18.42
0.75→1.0	3.29	5.32	0.57	9.17	-7.48	-1.70	0.00	-9.17
1.0→2.0	13.86	14.34	-20.27	7.92	-7.74	-0.18	0.00	-7.92
2.0→3.0	4.96	-11.99	7.41	0.37	-0.38	0.00	0.00	-0.37

Table 4 Yield variation of 59 μm hematite particles in different radial regions

纵向行程/圈	内半槽产率变化/%				外半槽产率变化/%
纵向行程/圈	r₁	r₂	r₃	总和	r₄	r₅	r₆	总和
0.25→0.50	-0.60	-2.80	-3.26	-6.67	3.49	32.49	-29.31	6.67
0.5→0.75	0.15	36.37	33.60	70.12	-12.02	-51.99	-6.11	-70.12
0.75→1.0	0.35	-30.84	24.35	-6.14	10.79	-4.57	-0.08	6.14
1.0→2.0	1.83	33.27	-27.81	7.29	1.72	-8.82	-0.19	-7.29
2.0→3.0	0.84	-14.40	24.01	10.46	-10.03	-0.32	-0.11	-10.46

Table 5 Yield variation of quartz particles in different radial regions (90 μm hematite and 38 μm quartz

纵向行程/圈	内半槽产率变化/%				外半槽产率变化/%
纵向行程/圈	r₁	r₂	r₃	总和	r₄	r₅	r₆	总和
0.25→0.50	-0.97	-0.14	-2.57	-3.67	-3.39	2.54	4.53	3.67
0.5→0.75	0.38	0.65	0.82	1.85	-4.12	-13.97	16.24	-1.85
0.75→1.0	0.15	-1.05	1.98	1.09	-0.53	-3.57	3.02	-1.09
1.0→2.0	-0.04	1.35	-0.65	0.66	1.49	-4.61	2.46	-0.66
2.0→3.0	-0.44	4.99	3.39	7.93	-1.69	-5.70	-0.54	-7.93

Table 6 Yield variation of quartz particles in different radial regions (59 μm hematite and 38 μm quartz

纵向行程/圈	内半槽产率变化/%				外半槽产率变化/%
纵向行程/圈	r₁	r₂	r₃	总和	r₄	r₅	r₆	总和
0.25→0.50	-0.84	-2.97	-4.84	-8.66	-4.93	-0.24	13.82	8.66
0.5→0.75	-0.02	13.53	9.42	22.93	-3.94	-1.97	-17.02	-22.93
0.75→1.0	0.07	-12.38	7.15	-5.16	9.91	-6.70	1.95	5.16
1.0→2.0	0.13	3.17	-7.26	-3.96	-10.30	-7.57	21.83	3.96
2.0→3.0	0.13	-2.81	4.64	1.96	3.27	-0.42	-4.81	-1.96

Fig.11 Influence of splitter position on particle separation efficiency across different turns in the trough

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