Изучение фазового состава продуктов электрохимического окисления сульфидных гранул системы Cu1.96S–Ni3S2–Cu–Ni

Abstract

The crystallization rate of copper and nickel sulfides influences on the phase formation processes. The high crystallization rate (about 103 degrees/s), achieved through granulation of the sulfide copper-nickel melt, leads to the stabilization of non-stoichiometric phases, the formation of ultrafine structures, which are grains and partial dissolution of the metal component in the sulfide. The structure of the granules is formed by nickel sulfide (Cu1.96S) phases in the form of dendritic inclusions of 2-20 µm in size in the nickel sulfide phase (Ni3S2). According to the phase diagram of the state of Cu – Ni – S, a solid solution of Cu – Ni may be present in the composition of eutectic compounds with copper and nickel sulphides. The electrochemical oxidation of copper and nickel sulfides in a solution of sulfuric acid occurs through a series of successive phase transformations described in the work, during which the conversion of sulfides occurs in intermediate oxidation states oxidizing to the elemental state: Cu1.96S → Cu1.8S → Cu1.75S → CuS → S; Ni3S2 → NiS → S. The non-stoichiometric composition of compounds suggests the presence of excessive or deficient sulfur and metal contents in the crystal lattice, which can affect the mechanism and sequence of phase transformations during the electrochemical oxidation of sulfide granules. Dissolution occurs not only on the surface of the granules, but also along the grain boundaries. The leached areas form capillaries inside the granules, through which electrolyte enters the electrochemical reactions. Porous sulfur sulfide sludge forms on the surface of the granules. The phase composition of the sludge was studied. The main phase components of poorly soluble products are nickel granules Ni3+хS2–Cu2-хS.