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以含镉冶炼废渣浸出液模拟渣场淋浸废水,研究了用不同沉淀剂处理低浓度重金属冶炼废水时在效果和机制上的区别。研究了应用硫化沉淀法和氯化铝絮凝法时的投药量、pH值、温度和反应时间对废水中镉、锌离子沉淀效果的影响规律。结果表明:以硫化钠作为沉淀剂时沉淀反应速度较快,影响镉、锌除去率的主要因素是投药量,pH值、温度和反应时间对其的影响很小;实验条件下的适宜工艺参数为:投药量2g·L~(-1)、pH值8、温度35℃、反应时间18min,镉、锌除去率分别可达98.7%和98.1%。以氯化铝为絮凝剂时由于存在絮凝和水解作用,投药量、pH值、温度、反应时间等因素对沉淀效果的影响均较大,pH值是主要的影响因素;其较优化工艺条件为:投药量2g·L~(-1)、pH值9、温度30℃、反应时间50min,镉、锌除去率为90.8%和88.8%。对大水量低浓度含重金属冶炼废水进行稳定化处理时,药剂加投量和环境pH值是应该重点关注的因素;硫化沉淀法在操作条件和沉淀效果方面比氯化铝絮凝法具有一定的优势。
The leachate containing cadmium smelting slag was used to simulate the leaching wastewater of slag field. The difference in effect and mechanism between the different precipitants for the treatment of low concentration heavy metal smelting wastewater was studied. The effects of dosage, pH value, temperature and reaction time on the precipitation of cadmium and zinc ions in waste water were studied when using sulfidation precipitation method and aluminum chloride flocculation method. The results showed that when sodium sulfide was used as precipitant, the precipitation reaction rate was faster. The main factors affecting the removal rates of cadmium and zinc were the dosage, pH, temperature and reaction time. The optimum process parameters The results showed that the removal rate of cadmium and zinc reached 98.7% and 98.1% respectively when the dosage was 2g · L -1, the pH value was 8, the temperature was 35 ℃ and the reaction time was 18min. In the case of aluminum chloride flocculant, the effect of flocculation and hydrolysis, the amount of dosage, pH, temperature, reaction time and other factors on the precipitation effect are large, pH value is the main influencing factor; the more optimized process conditions are : Dosage of 2g · L ~ (-1), pH value of 9, temperature of 30 ℃, reaction time of 50min, cadmium, zinc removal rate of 90.8% and 88.8%. When the heavy metal containing waste water with large concentration and low concentration is treated by stabilization, the chemical dosage and environmental pH value should be the focus of attention. The vulcanization precipitation method has some advantages over the aluminum chloride flocculation method in operating conditions and precipitation effect .