Improve flotation efficiency of refractory tungsten ore and reduce carbon emission in flotation process: A case study of Sandaozhuang deposit in Henan, China

•The mineralogical of scheelite in a strongly altered skarn ore were identified.•A new reagent recipe was proposed to beneficiate the refractory scheelite ore.•The effect and underlying mechanism of the reagent recipe was analyzed.•The reagent recipe had created considerable economic and environmental benefits. With the rapid consumption of tungsten ore resources which were easy to beneficiation, the low-grade refractory scheelite has become the main source of tungsten production. In this study, a new reagent recipe was proposed to improve scheelite flotation efficiency and reduce carbon emission in flotation process by taking Sandaozhuang strongly altered ore as an example. The mineralogical study indicated that the content of WO3 in this ore was 0.0952 %, and 83.16 % of WO3 occurred in scheelite. The high content of calcium-containing gangue, easy-argillation gangue and fine scheelite jointly made it difficult to recover scheelite efficiently. The batch flotation tests shown that under the conditions of Na2CO3 1800 g/t, SS 600 g/t, SG 60 g/t, engine oil 20 g/t and FX-8 180 g/t, a rough concentrate with WO3 grade of 1.503 % and WO3 recovery of 79.40 % can be obtained. The industrial tests and application shown that this new reagent recipe had good industrial applicability and stability, and was conductive to improve the efficiency of the whole flotation process. The economic and environmental benefits analysis found that the application of this new reagent recipe in a 10,000 t/d scheelite flotation plant can create annual additional economic value of more than CNY 20 million, and reduce annual carbon emissions by more than 5000 t. Therefore, this new reagent recipe was worth popularizing and applying in similar refractory scheelite flotation plants.