Hydrometallurgical Recycling of Copper Anode Furnace Dust for a Complete Recovery of Metal Values

Copper anode furnace dust is waste by-product of secondary copper production containing zinc, lead, copper, tin, iron and many other elements. Hydrometallurgical Copper Anode Furnace dust recycling method was studied theoretically by thermodynamic calculations and the proposed method was verified experimentally on a laboratory scale. The optimum condition for leaching of zinc from dust was identified to be an ambient leaching temperature, a liquid/solid ratio of 10 and H2SO4 concentration of 1 mol/L. A maximum of 98.85% of zinc was leached under the optimum experimental conditions. In the leaching step, 99.7% of lead in the form of insoluble PbSO4 was separated from the other leached metals. Solution refining was done by combination of pH adjustment and zinc powder cementation. Tin was precipitated from solution by pH adjustment to 3. Iron was precipitated out of solution after pH adjustment to 4 with efficiency 98.54%. Copper was selectively cemented out of solution (99.96%) by zinc powder. Zinc was precipitated out of solution by addition of Na2CO3 with efficiency of 97.31%. ZnO as final product was obtained by calcination of zinc carbonates.

Instabilities of electrical properties of He-induced W “fuzz” within the pre-breakdown and breakdown regimes

The investigation of the He-induced W “fuzz” electrical properties was carried out. For the research, an automated experimental setup was designed. The setup was based on a vacuum chamber operated under high vacuum conditions (~ 10−7 Pa). The vacuum diode under investigation comprised of a flat W “fuzz” cathode with an area of about 1 cm2 and a 2 mm radius cylindrical copper anode with a hemisphere tip. The cathode-anode distance was about 100 μm. The voltage applied was up to 10 kV. A DAC/ADC module controlled an HV power supply and automatically registered currents and voltages in the circuit. The effect of a spontaneous change in the emissive ability of the investigated surface area was observed. These changes can vary significantly in magnitude. Large-scale changes can lead to a permanent increase in the emissive ability of a specific area or to a breakdown of the gap. Small changes, as a rule, are reversible, have a stepped nature, and make it difficult to record and interpret the current-voltage characteristics of the field emitter.