The Study Of Chromium Slag' Detoxification And Solidifying

The chromium slag has been greatly concerned as the chromium slag's large quantity of producing and its high toxicity. The use of conventional curing treatment,. hexavalent chromium often exceed national standard. This paper first use hydrazine hydrate for reducing agent, to reduce hexavalent chromium, to became trivalent chromium and reduce the hexavalent chromium of chromium slag content;then use cement solidifying the chromium slag of having been reduced. Distilled water is leaching agent in experiment.The phase of reducing chromium slag, study the chromium slag moisture^ temperature,reaction time,chromium residue particle size,the amount of reducing gent that affect reducing; the soaking time on returning the previous state. The results show when the chromium slag scale is 0.220-0.150mm; the water is controlled about 8 percent; temperature is controlled 60℃; the reaction time is controlled 10min; the result is best. At the same time, the greater size chromium slag particle is, the more hexavalent chrome will be exposured, if the hexavalent chromium does not exceed the national standard, the reaction need more reducing agent. Because of the strong alkaline chromium slag, after the detoxification of chromium slag, if not further treatment, chromium slag will gradually back to yellow.The phase of hydrazine hydrate reduction of the mechanism of chromium residue, through the mutual relations between Nernst equation and the electrode potential, study the hydrazine hydrate, oxygen, carbon dioxide'electrode potential of the curve with pH. According to the interrelationship between hexavalent chromium and trivalent chromium, it can be judged that hydrazine hydrate reduction chromium slag will be not controlled by pH.The phase of the chromium slag, study the effect of the amount of chromium slag and fly ash,the time of conservation on solidifying;the effect of the rate of salt and soaking on leaching. The results showed when the conservation time for 3 d, the amount of fly ash about 2 percent, chromium slag under 40 percent, the solidifying slag will not exceeded the national standard; adding 2.5 percent of fly ash can be significantly enhanced solidifying effect; the solidifying slag will be stabilization by conservation 12days; salt has damaging effects to the slag, the higher concentration of salt has leaching hexavalent chromium and trivalent chromium from the slag; the soaking time has less effect on leaching.