Separation of feldspar and quartz by acid flotation method

The effective separation of feldspar and quartz has always been a major difficulty in the mineral processing industry. In potassium feldspar, common gangue minerals mainly include iron-containing minerals (such as iron oxides, iron-containing amphibole), mica minerals (such as muscovite, sericite) and quartz; quartz sand often Contains non-magnetic associated impurity minerals such as feldspar and mica. 

The main reason why it is difficult to sort feldspar and quartz is that the charging mechanism of feldspar and quartz in aqueous solution is basically the same. Both crystal structures are shelf-like structures, except that 1/4 of Si4+ in the quartz crystal structure is replaced by Al3+ , which is feldspar. Since Al3+ replaces Si4+, K+ or Na+ is charged as a metal counter ion in the corresponding tetrahedral structural unit to maintain the electrical neutrality of the mineral. According to the content of K+ and Na+, it is divided into potassium feldspar and albite. 

Acid flotation

The acid flotation method uses an anionic and cationic mixed collector to preferentially flotate feldspar in an acidic slurry with a pH value of 2-3. Depending on the chemicals used, this method can be divided into fluorine flotation and fluorine-free flotation.

▌Fluorine flotation method

Under the activation of strong acidity and fluoride ions, cationic collectors are used to preferentially flotate feldspar. The key to achieving flotation selectivity is to adjust the pH value of the slurry solution. When pH=2, quartz is near the zero electric point, while feldspar has a general zero electric point of pH=1.4~1.7. Under the activation of fluoride ions, the negative charge on the surface The potential increases and the quartz surface is basically uncharged. Amine cations are the first to be adsorbed on the surface of feldspar, making its surface hydrophobic.

▌Fluorine-free flotation method

Under strong acid conditions, the anionic collector dodecyl sulfonate and the diamine cationic collector are mixed. The anionic collector is then complexed with the diamine collector adsorbed on the feldspar surface to form co-adsorption. , which improves the hydrophobicity of feldspar surface.