At present, the process of closed-circuit recycling of calcium carbide slurry wastewater has been used in China to recycle the supernatant of the slurry. The concentrated calcium carbide slurry is pressed and dehydrated by pp filter press, and the residue filter cakes can be made as raw material for epoxy propane production instead of hydrated lime.
Then the filtrate is recycled and can be used as reaction water. And in the output, the content of H2S and PH3 in acetylene gas did not change. And there was no change in the load for the clean tower also. Additionally, the content of sulfide in supernatant was stable and did not accumulate and the water temperature of the supernatant meets the water requirements of acetylene generator. All those specifications shows the recycled water performs well.
In this way, 1.2 million tons of water can be saved every year, saving 900000 yuan of water cost and reducing sewage fee by 1 million yuan. The production cost of epoxy propane was reduced by 2.5 million yuan per year by replacing hydrated lime with calcium carbide slag. Not only eliminated the main source of pollution, but also saved a lot of water resources. The application of chamber filter press can greatly reduce production cost and obtain remarkable economic and social environmental benefits.