Investigation of the processes of extraction of targeted silicon dioxide nanofractions by coagulation and electrocoagulation methods

The article presents the results of studies on the extraction of target nanofractions of amorphous silica from a chamber product after flotation using coagulation and electrocoagulation. The subject of research in this work is cyclone dust and sludge from the silicon production of JSC Kremniy, located in the Irkutsk region. The original cyclone dust contains 44.59% carbon and 52.55% silicon dioxide. The granulometric composition ranges from a micrometer to hundreds of micrometers. Studies performed on a JEOL JIB-Z4500 scanning electron microscope show that the particles consist of conglomerates of nanometer-sized silica particles. The material balance of dust flotation from silicon production cyclones is presented. As a result of flotation, a chamber product was obtained - a stable fine suspension (sol) enriched with SiO2 (pH = 8.74–8.36). The lifespan of sol is several months. Coagulants and flocculants have been proposed that ensure complete extraction of amorphous silica. The amounts of coagulants and flocculants that ensure this extraction have been established. Data on the flocculation of a chamber product coagulate with a C12H25SO4Na (SDS) solution at a concentration of 4 mmol/l, as well as a solution of Magnaflok at a concentration of 0.1 g/l are presented. To determine the charge, the suspension was treated with 10% solutions of sodium phosphate (Na3PO4) and aluminum sulfate (Al2(SO4)3). The dependence of the mass of the coagulate on the current density during electrocoagulation of a model chamber product on aluminum electrodes was obtained. It has been established that the mass of the cathode and anode decreases. It is shown that at a current density of 0.1 A/cm2 the greatest loss of electrode mass and the highest anodic current efficiency are observed (η = 2.242). The results of a study of the modification of gray cast iron with the obtained modifier are presented