Influence on fine coal flotation produced by the quality of water used by Qipanjing Coal Preparation Plant

Due to use of mine water as washwater by Qipanjing Plant, the fine coal flotation process is rendered difficult to control, causing the cleaned small coal to go over the limit in ash. To tackle the problems, following an analysis of the properties of the high salt-containing water and domestic water obtained through treatment of mine water and those of the process water and overflow of thickener using the XRD and inductively coupled plasma atomic emission spectrum (ICP-AES) analysis techniques, the influence of water quality on fine coal flotation, and the factors attributing to the high ash of flotation concentrate are investigated. As revealed by study result, the various types of water bodies in Qipanjing mining area all contain chiefly Ca²⁺ , Na⁺, and Cl^- ions; and when flotation test is made with different types of water samples and diesel oil and sec.-capryl alcohol at a respective dosage of 150 g/t and 75 g/t, the yield and ash content values of flotation concentrate are seen to increase in an order of high-salt water> process water> thicker overflow water> domestic water, indicating that the use of the former two types of water are conducive to increase of concentrate yield yet unfavorable to the reduction of concentrate ash. It is observed through analysis that the high concentration of calcium ions in high salt-containing water and process water is the main factor causing the high ash of flotation concentrate, and the use of thickener overflow water alone is favorable to improvement of fine coal flotation result.