Nanjing, a zinc sulfide mines lead to Director river, output per day from about 3500t mineral waste (abbreviated wastewater), since no building tailings, coagulation - activated carbon adsorption of wastewater reuse after treatment. After long-term operation of the process, the organic flotation reagents in the wastewater accumulate continuously, resulting in the continuous increase of COD in the wastewater. The wastewater reused after treatment affects the normal operation of the production process of the concentrator. Therefore, how to improve the wastewater treatment process and ensure the smooth progress of mineral processing is a production and environmental protection problem that the concentrator needs to solve urgently.
NaClO has strong oxidizing properties and can oxidize and decompose pollutants in wastewater. NaClO is widely used in the treatment of cyanide-containing wastewater, and is also used in the treatment of sulfide malodorous wastewater. It is widely used, but it has not been reported in the application of mineral wastewater. This work uses the NaClO method to treat the ore dressing wastewater to provide a scientific basis for the design of wastewater treatment process.
First, the experimental part
(1) Wastewater quality
Experimental from Nanjing, a field concentrator effluent after the aluminum-salt coagulation with mineral waste. The wastewater is colorless and odorous, pH 6.4-7.2, COD 900～1200mg/L, Pb mass concentration 2.55mg/L, Zn mass concentration 0.032mg/L, Cu mass concentration less than 0.02mg/L, Cr mass concentration 0.55 The mass concentration of mg/L and Cd is 0.009 mg/L, and the mass concentration of Ag is less than 0.008 mg/L. The content of Pb and Cr in wastewater exceeds the standard, and COD is the super-emission standard. The main purpose of this experiment is to reduce the COD of wastewater and provide a reference for the discharge of wastewater. The COD of the wastewater used in the experiment is 800 to 870 mg/L.
(two) 1.2 instruments and reagents
PHS-25 pH meter, Shanghai Hongyi Instrument Co., Ltd.; magnetic stirrer, Guohua Instrument Factory; COD rapid tester, Guangdong Medical Instrument Factory; photoelectric analysis balance, Changshu Shuangjie Test Instrument Factory.
In the experiment, the removal rate of wastewater COD was 98.3%. From the economic point of view, for the treatment of actual wastewater, it is best to directly add the agent to the reaction without adjusting the pH of the wastewater. When the pH is l1, the reaction time is 10 min, and the NaClO addition amount is 1 g/L, the COD removal rate is 39.4%, the cost of NaClO treatment for 1m3 wastewater is about 30 yuan, and for wastewater with COD removal rate close to 100%, the cost of adding NaClO agent is too high and can only be used as a theoretical reference.
Second, the conclusion
(1) The ore dressing wastewater is treated by sodium hypochlorite method. Under the condition of pH 4 of the wastewater, 100g/L of NaClO and 30min reaction time, the COD removal rate of the ore dressing wastewater can reach 98.3%.
(2) When the pH of the wastewater is 11, the reaction time is 10 min, and the amount of NaClO added is lL, the COD removal rate of the ore dressing wastewater is 39.4%, and the cost of the NaClO treatment for the 1 m wastewater is about 30 yuan.
(3) According to the results of the range calculation, among the selected influencing factors, the amount of NaClO added has the greatest influence on the COD removal rate of wastewater, followed by the reaction time and pH again.
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