Research And Improvement On Separation Of Waste And Old ABS/HIPS By Flotation

At present,the plastic electronic waste materials containing HIPS and ABS have not been effectively used,and the recycling and reuse of these waste materials can produce high social value.In the process of recycling and reuse of waste plastics,they should be selected first,but because of the close density and charge properties of the two kinds of ABS and HIPS plastics,it is difficult to separate the mixture of the two by the traditional separation method.Plastic floatation can achieve separation of plastic with similar charge density and close density,and good separation effect can be obtained.However,the problem of high flotation cost and further improvement of flotation efficiency has not been well solved.This paper uses tap water instead of distilled water to configure floatation solution to reduce the cost of flotation.The flotation separation of plastics is carried out on a laboratory specially made flotation device with a high recovery value and an inseparable mixture of waste ABS and HIPS as the research object.The effect of flotation process,pH value of floatation solution and type of floatation wetting agent on flotation effect is investigated,and the practical problems of high cost and poor flotation effect are studied.It is found that the flotation liquid with different wetting capacity and different foaming ability can be raised by multistage flotation.High floatation effect.It is found that when using tap water to make flotation,tannic acid is used as a wetting agent.The optimum flotation conditions are:the pH value of the floatation solution is 6 and the concentration of the pine oil alcohol is 70 mg/L,the stirring time is 6 min,the flotation time is 10 min,the tannic acid concentration is 25 mg/L,and the hydrochloric acid and acetic acid are used respectively at this time.The effect of pH value on flotation effect is studied.The results show that the pH value of hydrochloric acid is 5 as a suitable flotation environment.In this case,the recovery rate of HIPS is 85.93%,the purity is 68.35%,the recovery rate of ABS is 91.40%,and the purity is 67.11%.When the sodium carboxymethyl cellulose is used as the wetting agent,the results of flotation separation obtained by using acetic acid to adjust the pH value of the flotation solution are 3 and the stirring time is 60 min.The recovery rate of HIPS is 54.06%,purity is 68.04%,the recovery rate of ABS is 74.06%,and the purity is 61.89%.It is found that it is related to carboxymethyl cellulose slowly converted to acidic component carboxymethyl cellulose under acidic conditions.Through the flotation of the flotation liquid for different time,it is found that the volatilization of the pine oil leads to the gradual deterioration of the flotation effect,but the flotation effect can be improved by adding the release of pine oil alcohol.At the same time,the effect of floating material quality on the flotation results is also studied.It is concluded that the flotation effect is guaranteed and the flotation cost is reduced by the ratio of 750 mL floatation liquid to the waste plastic with a total mass of 40 g.The JC2000D1 contact angle tester is used to test the contact angle of the waste ABS and HIPS used in the flotation experiment.In the tannic acid concentration gradient experiment,when the pure tannic acid concentration is 200 mg/L,the difference of the contact angle is the largest,which is 7.79.The difference between the butt contact angle difference is little and the difference is the maximum of 7.in the addition of the release of the pine oil alcohol as the foaming agent.80,when the sodium alkyl sulfate was added as a foaming agent,different sodium alkyl sulfate gradient was set,and the contact angle of the flotation solution on the surface of ABS could be significantly reduced when the concentration of sodium alkyl sulfate was 20 mg/L,indicating that the wettability of tannic acid to ABS could be further enhanced by the sodium alkyl sulfate.Through the experiment,the best conditions for further flotation of the first grade floatation are two mg/L,70 mg/L,30 cm,1 min and 1 min flotation time.The best flotation conditions for floatation of the first grade flotation are two mg/L,20 mg/L,3 min,3 min and 5 L/min.Finally,the purity and recovery rate of ABS obtained by two stage flotation reached 92.21%and 93.32%respectively,and the purity and recovery rate of HIPS reached 93.24%and 92.12%respectively.