Engineering Design and Operation Practice of Softening and Removing Hardness From Wastewater in Gold Smelting Plants
Wet smelting of gold will generate a large amount of cyanide containing wastewater,which still has high hardness and heavy metal content after cyanide breaking treatment.The wastewater cannot be precisely re-used for production.The technological challenge of removing the hardness from gold smelting wastewater is now an urgent matter to address.In response to the production demand of a gold enterprise,the sewage treatment plant adopted the"NaOH-Na2CO3 softening and thickener sedimentation"process to soften and remove hardness from the gold smelting wastewater after cyanide breaking,and the design water intake of this project was 15 m3/h.It was found that the softening and hardness removal effect of the process was remarkable during the stable opera-tion,with an average value of 1399.1 mg/L for hardness influent,210.9 mg/L for average effluent,and the hardness removal rate was stable at 80％～93％.All the final effluent indicators of the treatment plant met the desgin re-quirements,and the treatment cost was 4.18 yuan/m3.In order to facilitate maintenance and replacement by staff,the pipeline was connected by flange.The overall operation effect of this project remained steady,with lower op-erating expenses,which could provide technological support and guidance for the efficient removal of hardness and softening of gold smelting wastewater.
goldcyanide containing wastewaterhardnesssoftening and removing hardnesscoagulation and precipitation
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