The process of producing PVC will adots acetylene, which is made from calcium carbide. Nromally 1 ton PVC will consum 1.5 tons of calcium carbide. However, the acetylene is comes from the reaction between water and calcium carbide. So it will produce 15 tons of industrial wastewater containing about 12% solid. The waste water is commonly known as calcium carbide slurry.
Calcium carbide slag wastewater is highly alkaline and suspended. It contains toxic substances, such as: sulfur compounds. So it's forbidden to discharge directly, becuse can not meet the national liquid discharging standard. Additionally, if discharge, suspended solids will precipitate and cause pipe blockage or even causes siltation of the river bed.
While industrial producing, the slurry discharged by acetylene generator is pumped to the concentration pool and then sent to the side beam filter press to dewater. After sludge dewatering from chamber filtet press, filter cake solid content can be around 70%. At present, calcium carbide slag is used to produce epoxy propane instead of hydrated lime. In this way, it can turn waste into treasure, and epoxy propane produced has better quality to get good price.