Reaction Behavior of Na2SO4-Containing Copper Matte Powders in a Simulated Flash Converting Process.

Sodium sulfate accumulation in the water system is a common problem in the production of primary metals from sulfide minerals. In flash smelting-flash converting copper smelters, when molten copper matte quenched in industrial water to produce matte granules, Na₂SO₄ precipitated and entered the system, which had negative influence on the matte converting process. The reaction behaviors of copper matte powder containing Na₂SO₄ have been studied through thermodynamic calculation and single-particle experiments. Calculated results showed that a liquid sulfate phase, Na₂S containing copper matte, and Cu–Na alloy may form in the processing conditions of the converting process. The influence of the Na₂SO₄ dosage, fluxing conditions, and processing temperature has been systematically studied, and the results obtained showed that: (1); Na₂SO₄ physically precipitated on matte particles, and the Cu–Na alloy phase was found within copper phase in reacted particles; (2); Na₂SO₄ contamination hindered oxygen transfer by forming a low melting sulfate phase, and the de-sulfuration rate of matte powder changed dramatically along with the variation in Na₂SO₄ amount; (3); CaO flux was able to promote the converting reactions and Na₂SO₄ transformation; (4); Na₂SO₄ melt and formed a sulphate layer on matte particles at 1000 °C, Cu–Na alloy phase was found in samples collected at 1200 °C, and Cu–Na–O phase was detected in blister copper at 1600 °C. [ABSTRACT FROM AUTHOR]