Abstract

By understanding minerals as crystals, a crystallization-controlled methodology was performed to enhance the floatability of soluble minerals. Here, aimed strategies were applied to modulate the crystallization of KCl salt to grow crystals with various shapes as cubic-, hopper- and needle-like structure. Stereoscope and scanning electronic microscopy (SEM) helped to unveil the morphologies where X ray diffraction (XRD) characterized their high crystallinities. Afterwards, Atomic Force Microscope (AFM) was performed to research the crystallizing behaviors that cubic-like structure was obtained by turbid fast growth, while hopper-like structure formation was due to the constant high supersaturation and needle-like crystal occurred under still fast crystallization. Flotation tests with octadecylamine hydrochloride (ODA) as collector demonstrated the floatability of samples obeyed the order as needle-like (96.19 %) > hopper-like (81.59 %) > cubic-like (80.08 %) KCl samples. The mechanism was studied by surface area and related interaction tests. BET result demonstrated the highest surface area of needlelike structure than that of hopper-like and cubic-like structure. Besides, induction time combined with adhesion & desorption force tests further explained the better interaction of needle-like sample with bubble than cubic-like sample. While the special structure of hopper-like structure with lower weight but inner filled solution resulted in its near equivalent floatability with cubic-like sample. In conclusion, a new strategy for promoting flotation behavior by designing the crystallization of soluble KCl was proposed, shedding some light on further application on other soluble or semi-soluble minerals.