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Improving separation efficiency of galena flotation using the Aerated Jet Flotation Cell

Li Si, Wang Yuhua, Lu Dongfang, Zheng Xiayu, Li Xudong

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 3

513--527

EN

The low separation efficiency of traditional mechanical flotation cells for galena flotation primarily was caused by the low collision probability between bubbles and fine particles and high detachment probability of coarse particles. A flotation device named Aerated Jet Flotation Cell (AJFC) was adopted to improve the separation efficiency of galena flotation. Reducing bubble size and optimizing turbulence distribution were respectively confirmed as effective ways to improve fine galena-bubble collision efficiency and decrease detachment probability of coarse galena. In AJFC, micro-bubbles in diameter of 0.1-0.3 mm were generated by forcing compressed air to pass through porous high-density polyethylene tube, and high shear rate and appropriate turbulence were provided by installing a sparger with holes at the end of downcomer. The key parameters, including sparger hole number, turbulent kinetic energy (TKE), air-slurry ratio and superficial gas velocity (Jg) were optimized to achieve a desired separation performance of galena flotation. Separation efficiency of 62.54 % at a residence time of 2.25 min was achieved by AJFC, while separation efficiency of 59.12 % at a residence time of 7.5 min was achieved by mechanical flotation cell. Besides, AJFC had less loss of Pb in tailings than mechanical flotation cell in the whole particle size range, especially for fine (-25 µm) and coarse (+74 µm) size fractions.

2

Development of an open-gradient magnetic separator in the aerodynamic field

Lu Dongfang, Liu Jianjun, Cheng Zhiyong, Li Xudong, Xue ZiXing, Li Si, Zheng Xiayu, Wang Yuhua

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 2

325--337

EN

Open-gradient magnetic separator in the aerodynamic field named an Aerodynamic Open Gradient Magnetic Separator (AOGMS) was developed for recovering magnetite under the dry condition. In this paper, the principle of AOGMS is discussed, and a continuous lab-scale AOGMS was tested to separate magnetite particles from a material with the particle size of minus 3mm and inadequate liberation degree. The effect of key variables such as magnetic field intensity, the flow rate of air, and the rotation speed of the roller on the separation performance was investigated. The results suggest that the magnetic field intensity and the airflow rate both have the most significant influences on the performance. Under the condition of the magnetic intensity field 1250Gs on roller surface, an increase in the airflow rate can significantly improve concentrate grade with only a slight change of Fe recovery due to enhance the removal of the quartz and mica containing SiO2 and Al2O3. AOGMS process could provide the appropriate competitiveness in the dry separation process, thus, the locked particles and fine non-magnetic particles can be discarded efficiently. This also shows that reasonable matching multiple force fields can effectively strengthen the separation efficiency of complex iron ore.

3

Study on the application of elliptic cross-section matrices for axial high gradient magnetic separation: key considerations for optimization

Zheng Xiayu, Wang Yuhua, Lu Dongfang, Li Xudong

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 3

655--666

EN

To reveal the key optimization considerations for the application of elliptic cross-section matrices in axial high gradient magnetic separation (HGMS), the performance of circular and elliptic matrices was investigated experimentally and theoretically, providing that the short axis of elliptic matrix was equal to the diameter of circular matrix. Three schemes were adopted to investigate the performance matrices with ratio of long axis to short axis λ of 1 (circular matrix), 1.6 and 2. Under the same matrix unit number, hematite recovery of elliptic matrices could be 5~20% higher than that of circular matrices. For the case that the separation space was fully filled under the same matrix unit spacing, elliptic matrices showed higher and lower hematite recovery in low and relatively high magnetic field. The particle capture cross section area of elliptic matrix could be 1.4~1.8 times larger than that of circular matrix. Analyses with particle capture models showed that higher hematite recovery was ascribed to the larger particle capture cross section of the elliptic matrices and overlapping of the capture cross section was responsible for the lower hematite recovery of elliptic matrices in relatively high magnetic field. For substitution of circular matrices with elliptic matrices in axial HGMS, overlapping of capture cross section of target particles should be taken into consideration.