Study On Treatment Technology Of Acid Fluorine-containing Wastewater In The Graphite Purification Industry

Graphite resources is rich in China,but at present,graphite industry is lack of scientific and technological content,high purity graphite need to be imported,which producing huge trade deficit.The technological difficulties should be solved as soon as possible.High purity graphite production is an important topic of the graphite enterprises in Heilongjiang province,and wastewater treatment related to high purity graphite production is one of the important content of this subject.For reasons of economy and practicality,the high purity graphite production mainly use the hydrofluoric acid method,as a result,a large amount of wastewater containing fluorine is produced,will pollute the environment,do damage to the crops and livestock's normal growth,so process research of removing fluoride in industrial wastewater is particularly important.The main characteristic of graphite industrial fluorine-containing wastewater is strong acidity and high fluorine content.The calcium salt precipitation method is used as primary treatment process in this research.The precipitator is selected and the precipitation process parameters are optimized.A method of treating wastewater dividedly according to wastewater source is put forward,compared with mixed wastewater treatment,better treatment effect is achieved.Common treatment of fluoride-containing wastewater is lime precipitation method,but the effect is not very good when used alone,this experiment explored the calcium oxide precipitated + supernatant coagulation combined process and result in a better treat effects.Through the optimization of process parameters,get the final plan is that,adding CaO 110g/L,PAC 450 mg/L,PAM+ 8mg/L.However,after coagulation treatment the fluoride concentration in diluted effluent is on the high side.The reason of this problem is analysised.It is proposed to measure fluoride concentration after diluted 100 times.In consideration of the phenomenon that coagulation precipitation supernatant fluid contains residual fluoride complex,the fluoride removal is incomeplete,adsorption method is considered as a added process to guarantee water safety.The activated alumina is chosed as adsorbent.The effect of adsorption time,concentration of raw water,initial pH and coexisting anions are studied.The regeneration condition and effect is also studied.Experiments show that activated alumina is an effective fluoride adsorbent for graphite industry wastewater,the decrease of adsorption quantity after regeneration is not obvious.This experiment explored the high-purity graphite producing wastewater treatment rehabilitation programs,finished the ‘Equipment Selection Report' of calcium oxide precipitated + adsorption coagulation combined process,and draw site process layout.By calculating the running costs of pharmaceutical,process improved processes has a lower running costs than the original process with a good economic benefits,The upgrading program can be directly used for Austrian-Graphite Company plant wastewater meeting the emission standards.