Research On Preparing Ultra-fine Copper Powder With Liquid Phase Reduction Method From The Waste Cupric Liquor

With advantage of non-toxic and low cost, glucose and thiourea dioxide were applied as the reductants of liquid chemical reduction for preparation of ultrafine copper powder from waste cupric liquor. Copper sulfate solution was used first as raw material, the effect of the dosage of reductant, reaction time,reaction temperature and complexing agent on the product particle size and morphology of ultrafine copper were examined, the optimum preparing condition was obtained. Afterwards,recovery of copper from acidic and alkaline etching waste liquid was conducted by liquid chemical reduction, and ultrafine high-purity ultrafine copper powder was prepared, the preparation conditions and the effecting factors of particle size and morphology of the copper powder were investigated.The results showed that small particles with good dispersebility could be prepared by glucose and urea sulfur dioxide from copper sulfate solution. cupric ion was reduced to cuprous oxide by glucose, which made the particle size of copper powder smaller. The optimum preparing condition for copper sulfate as a raw material was: glucose was employed as pre-reductant, with the dosage of twice of the copper ion concentration, polyvinylpyrrolidone was used as dispersant, with the dosage of 1g/L, molar concentration ratio of thiourea dioxide to copper ion was 2:1,reaction temperature was 75℃, reaction time was 15 min. The optimum preparing condition for acid etching waste solution a raw material was: glucose was employed as pre-reductant, with the dosage of twice of the copper ion concentration, polyvinylpyrrolidone was used as dispersant, with the dosage of 1g/L, molar concentration ratio of thiourea dioxide to copper ion was 3:1,reaction temperature was 75℃, reaction time was 10 min. The optimum preparing condition for alkaline etching waste solution a raw material was: glucose was employed as pre-reductant, with the dosage of twice of the copper ion concentration, polyvinylpyrrolidone was used as dispersant, with the dosage of 1g/L, molar concentration ratio of thiourea dioxide to copper ion was 2:1,reaction temperature was 65℃, reaction time was 10 min. When acid etching waste solution was applied as a raw material, the ultrafine copper powder particle size was 100-300 nm, and its morphology is spherical, which showed in SEM and TEM photos. While alkaline etching waste solution was applied as a raw material, the ultrafine copper powder particle size was 200-500 nm, and its morphology is flake, which showed in SEM and TEM photos. Characterization,of XRD, EDS, UV, FI- TR revealed that the ultrafine copper powder was very high purity. The copper concentration in filtrate was about 2 g/L, so the copper recovery was more than 98%. The morphology of ultrafine copper powder would be changed when the complexing agent was added into the solution.The formation mechanism of ultrafine copper powder was discussed, the redox reaction was the base of the solution reduction process, and the electrode potentials determine whether the redox reaction can occur or not. When the reaction products comes to an oversaturated in solution, the precipitation will be form by composed of homogeneous or heterogeneous nucleation process.