Oil Removal Pretreatment Process for Semi-Coke and Coking Wastewater

Semi-coke wastewater is generated during the carbonization in medium and low temperature  (about 650°C) , primarily source from the circulating water used for cooling and washing coal gas, as well as the water during the process of chemical production. Semi-coke undergoes carbonization in low-temperature , resulting in a high yield of tar and abundant low-molecular organic substance during production. Consequently, the wastewater contains a significant amount of pollutants that have not been oxidized by high temperatures, with a concentration approximately 10 times higher than other coking wastewater, making it more challenging to treat than other coking wastewater.

Looking at the entire process of wastewater treatment for semi-coke , the advantages of biological treatment cannot be fully utilized without the support of effective physicochemical pretreatment technology. To some extent, physicochemical pretreatment technology has become a bottleneck in the treatment of semi-coke wastewater. Especially in the oil-water separation stage of primary treatment, due to the presence of a large amount of oil in semi-coke wastewater (mainly heavy oil consisting of condensed aromatic hydrocarbons and light oil consisting of straight-chain hydrocarbons, as well as a large amount of emulsified oil and dissolved organic substance), conventional oil separation methods cannot meet the normal operation requirements of subsequent dephenolization and ammonia distillation devices.

In the field of wastewater treatment for semi-coke , multiple continuous sedimentation and oil separation tanks are commonly used to remove the waste oil from the wastewater. The wastewater contains heavy oil, light oil, emulsified oil, dissolved oil, as well as some coke powder and mixtures of coke powder and oil, making the  state of waste oil complex. The outlet data from the sedimentation tank of a semi-coke enterprise is as follows:

The data shows that the total oil content is as high as 1200-2000mg/L, and a suitable pretreatment process for oil removal is required to ensure the stable operation of the ammonia distillation and dephenolization unit. Our company's R&D has the technologies coupled and integrated physical oil removal methods (hydrocyclone separation, coarse coalescence, and W-shaped corrugated plate technology) with new materials (oleophobic hydrophilic separation material, oleophilic hydrophobic wetting coalescence separation material) to remove light oil, coke powder, and most emulsified oil from wastewater, standardizing the oil removal treatment process for semi-coke wastewater and ensuring equipment is enclosed. The specific oil removal treatment process for semi-coke wastewater is as follows: