Jizhong Energy Resources Co., Ltd. Xingtai Mine
Screen machine model: Landsky D5FG1021
Process: coarse slime sorting
Xingtai Mine Coal Preparation Plant is affiliated to Xingtai Coal Mine of Jizhong Energy Resource Co., Ltd, its’ B system was put into operation in 2010. In the coarse slime separation process, coarse slime separator (CSS) had been used. The overflow of CSS was processed by hydrocyclone cluster + sieve bend + slime centrifuge, then the final coarse clean coal product was obtained. However, there were some problems occurred during the operation.
(1) The effect of the hydrocyclones was poor with low classification efficiency, and too much fine particles went to the underflow (Between 30% and 40% in Xingtai Mine Coal Preparation Plant);
(2) Coarse materials passed into undersize easily due to the large slot （0.4~0.6mm）of the sieve bend while removing high-ash and fine slime;
(3) Unfavorable working conditions such as stockpiling and spillage are prone to occur on the sieve bend in different wear cycles, which affects the effect of desliming and ash-reduction.
In order to stabilize the quality of clean coal products and improve the recovery rate of coarse clean coal, Xingtai Mine Coal Preparation Plant carried out technological upgrading for system B on the coarse clean coal desliming and ash reduction process in May 2019. A D5FG1021 Multi-deck high-frequency vibrating screen (δ=0.25mm) is used to replace two 500mm diameter hydrocyclones and one sieve bend (δ=0.6mm) for recycling coarse clean coal.
The process after upgrading is shown in Figure 1
Fig. 1 Flowsheet of coarse coal slime sorting process for system B after upgraded
Process indicators after upgraded
It can be seen from Table 2:
(1) The classification result of the hydrocyclones was poor,the fines went to underflow and the coarse went to overflow. The classification efficiency is low.
(2) The particle size control of the over the curved screen was good, but the coarse was run through the screen with the undersize, causing the loss of fine coal;
(3) The overall screening efficiency of stack screen D5FG1021 is high, its particle size control of the oversize and undersize are both better than that of the first two device stand -alone inspection data, especially in the terms of undersize coarse control.
Based on the test data of three types of equipment, namely classification hydrocyclones, curved screen and high-frequency vibrating stack screen, it can be concluded that the classification effect of high frequency stack screen D5FG1021 is better than the combination of hydrocyclones and curved screen , In particular the particle size of the material entering the flotation system is well controlled, and it has positive effect in the control of the flotation feeding properties and the improvement of the recovery rate of clean coal.
Economic benefits after upgrading.
Technological upgrading the coarse coal slime separation process of system B, on the premise of ash content, about 4,200 tons of extra coarse clean coal can be recovered every year, and the extra benefit after upgrading is about 3.82 million CNY each year.