PCB waste liquid production huge resource rich disposal mode urgently needs to be upgraded
Traditional PCB enterprises have complex production processes, long process flow, large resource consumption, wide range of chemicals used and large amount, which is one of the typical heavy pollution industries.In general, complex and high-risk waste pollutants will be generated, including waste acid, alkali etching waste liquid, low-copper waste liquid, COD ammonia nitrogen waste liquid, and various electroplating waste liquid, fluoride, cyanide and other secondary pollutants containing copper, nickel, tin and other metals.According to the statistical yearbook of China's electronic information industry, the average water consumption to produce 1 m2 circuit board is over 3.4 tons, and the waste water generated by the PCB industry is 680 million m3 annually.
From the perspective of resource consumption, China consumes about 6.2 million m3 etching solution, 4.6 million m3 microetching solution, and 150,000 m3 tin discharging water every year. The etching solution, microetching solution and tin discharging water used are all disposable.The waste liquid produced by the above consumed solution contains 1 million tons of copper, 15 thousand tons of tin, 75 million tons of ammonium chloride, 1.5 million tons of ammonia, 650 thousand tons of hydrochloric acid, 230 thousand tons of sulfate, 70 thousand tons of nitric acid, and 22 thousand tons of ferric nitrate.
These pollution index is high, resource consumption is fast pollution source, but also valuable potential composite resources.PCB general outsourced transport to units with hazardous waste disposal qualification for processing.The treatment generally adopts the chemical technology method of neutralization precipitation, only extracts some copper ions and heavy metals in the waste liquid. The potential resources contained in the waste liquid, such as ammonia nitrogen, hydrochloric acid, sulfuric acid, chloride, fluoride, thiourea, etc. are also chemically neutralized and directly discharged together with the waste water.
This method, on the one hand, wastes chemical resources, and on the other hand, causes different degrees of secondary pollution.Moreover, this treatment mode is only a reduction treatment of the pollution source, which cannot eliminate the production of waste liquid at the source, and there is a risk of leakage during the pollution source transfer and transportation.