Sampaio R M M, Timmers R A, Xu Y, Keesman K J, Lens P N L
Sub-department of Environmental Technology, Wageningen University, Biotechnion, Wageningen, The Netherlands.
J Hazard Mater. 2009 Jun 15;165(1-3):256-65. doi: 10.1016/j.jhazmat.2008.09.117. Epub 2008 Oct 7.
Copper was continuously and selectively precipitated with Na(2)S to concentrations below 0.3 ppb from water containing around 600 ppm of both Cu and Zn in a Continuously Stirred Tank Reactor. The pH was controlled at 3 and the pS at 25 (pS=-log(S(2-))) by means of an Ag(2)S sulfide selective electrode. Copper's recovery and purity were about 100%, whereas the total soluble sulfide concentration was below 0.02 ppm. X-ray diffraction (XRD) analysis showed that copper precipitated as hexagonal CuS (covellite). The mode of the particle size distribution (PSD) of the CuS precipitates was around 36 microm. The PSD increased by high pS values and by the presence of Zn. Depending on the turbulence, the CuS precipitates can grow up to 200 microm or fragment in particles smaller than 3 microm in a few seconds. Zn precipitation with Na(2)S at pH 3 and 4, in batch, always lead to Zn concentrations above 1 ppm. Zn precipitated as cubic ZnS (spharelite).
在连续搅拌釜式反应器中，通过硫化钠（Na₂S）将铜从同时含有约600 ppm铜和锌的水中连续且选择性地沉淀，使铜浓度降至0.3 ppb以下。借助硫化银（Ag₂S）硫化物选择性电极将pH控制在3，pS控制在25（pS = -log(S²⁻)）。铜的回收率和纯度约为100%，而总可溶性硫化物浓度低于0.02 ppm。X射线衍射（XRD）分析表明，铜以六方硫化铜（辉铜矿）形式沉淀。硫化铜沉淀物的粒度分布（PSD）模式约为36微米。高pS值和锌的存在会使PSD增大。根据湍流情况，硫化铜沉淀物在几秒钟内可生长至200微米或破碎成小于3微米的颗粒。在pH为3和4的条件下，分批用硫化钠沉淀锌时，锌浓度始终高于1 ppm。锌以立方硫化锌（闪锌矿）形式沉淀。
