Research On Interface Separation Of Metal And Nonmetal Materials In Waste Circuit Board

At present,in the global environment of rapid development of science and technology and economy,the acceleration of the upgrading of electronic products has caused a large accumulation of electronic waste.The circuit boards in these waste computers,mobile phones and other wastes are new mineral resources and have great potential for recycling.At present,due to recycling costs and environmental issues,the waste circuit boards have not been effectively and reasonably recycled.This caused a huge waste of resources and caused environmental pollution.Achieving green recycling has become a hotspot in current research.The mechanical physical method is in line with the concept of green environmental protection.Among them,the interface sorting method has the advantages of low cost,low pollution,simple process equipment,and high recycling efficiency.Using it to sort waste circuit boards has broad recycling prospects and application value.This article mainly conducts technological research on the separation of the interface between metal and non-metal in the waste circuit board.Combining research of crushing process and water-based flotation process,one-time crushing is carried out in three time periods,and the crushing properties of powder size distribution,dissociation degree,particle morphology,interface element distribution,etc.are analyzed.The results show that 120 seconds / 200 grams is the best single crushing parameter in the one-time crushing process.If the crushing time is too short,insufficient crushing occurs,and if the crushing time is too long,the particle size becomes too fine.After crushing,the sieve is divided into five grades,of which the metal particles are flat,and the non-metallic particles are long and irregular.After conducting water-based flotation experiments,the results show that the separation of metal and non-metal in a single flotation is not sufficient,and the multi-stage flotation process can effectively classify and separate.In the multi-stage flotation experiment,the flotation process parameters have a great influence on the flotation separation effect.The results show that the multi-stage flotation process with constant speed to decreasing speed parameters is a water-based flotation process with better classification and recovery process effect.The fine particle size of-0.074 mm in the circuit board powder is not suitable for flotation separation,and the metal content of this particle level is very low.After the 0.3 mm-0.45 mm particle size flotation,the metal-rich mass contains more non-metallic particles,and thedissociation degree of this particle level is lower,so it needs to be re-crushed.The separation process under different dispersion media was combined with a multi-stage crushing process.According to the previous research,a short-time multi-stage crushing process was used to prepare the raw materials,which were divided into two particle sizes-0.074 mm and 0.074 mm-0.3 mm.The proportion is greatly reduced,reducing the proportion of particles that are more difficult to recycle.In the study of dispersion media,it was found that the contact angle of deionized water on the split circuit board was greater than 90 °.Absolute ethanol has a contact angle of 0 °,and it has good wettability.Carboxymethyl cellulose can interact with circuit board powder,increasing the dispersion between the powder.The three experimental results of water-based gravity separation,alcohol-based gravity separation and water-based froth flotation show that water-based gravity separation is the worst.The recovery rate of alcohol-based sorting pair-0.074 mm fine-grained metal reaches more than 50%,and that of non-fine-grained metal reaches more than90%.Water-based foam flotation has a poor effect on the recovery of fine-grained grades,but the recovery rate of non-fine-grained metal is over 94%.Process optimization for alcohol-based sorting,adding suspending agent PVB to the alcohol-based matrix,when the proportion of PVB is 0.2wt.%,Alcohol-based sorting of 0.074 mm-0.3 mm non-fine particle grade,metal recovery rate of 97.69%.The alcohol-based gravity sorting process can effectively separate metals and non-metals and realize efficient green recycling of waste circuit boards.