Study On Floc Characteristics Of Sliming Coal Slime Water Sedimentation

Coal slurry system is a key link realizing water closed cycle of coal plant and ensuring preparation on clean water.Its treatment affects seriously concentrator efficiency,separation effect,heavy media consumption,product moisture,and so on,.In especial,it is more difficult for extremely sliming coal slime water because of its high complexity.Based on extremely sliming coal slime water in Shendong coal preparation plant,on the basis of nature of coal slime water and flocculation and sedimentation characteristics,the experiments were carried out selecting four types of flocculations and ten different coagulants to deal with coal slime water,the best Pharmacy and process conditions in laboratory were obtained.Owing to three evaluation indexes,settling velocity,supernatant turbidity and compression layer height,are not corresponding,floc characteristics were ana lysed,floc strength calculation formula was drew by establishing model,the floc strength of above preferred Pharmacy was measured and verified by industrial tests,a single evaluation index,floc strength,was put forward.Finally the effect of 9 kinds of common flocculants on floc strength was researched,the link between the floc strength and sedimentation effect was established,and providing theoretical guidance for medicament optimization of mudding slime water sedimentation.The main results are as follows:1.Applying anionic,cationic,zwitterionic and non-ionic polyacrylamide(PAM)as flocculants and the settling velocity,supernatant turbidity,compression layer height as evaluation indexes,the sedimentation tests of coal slurry was carried out.It is found that:When the dosage of TDX1215 flocculant(cationic PAM)is lOg/t(dry raw coal),the sedimentation rate is 22cm/min,turbidity is 230 NTU.The effect will be more obvious with increase of the dosage;When the dosage is 16g/t(dry raw coal),the sedimentation rate and turbidity is by 24cm/min and 100 NTU.2.Ten different coagulants and four kinds of flocculants were mixed separately to study flocculation and sedimentation effect for high mud slime water,the settling velocity,supernatant turbidity,compression layer height as evaluation indexes,it as found that:the complex optimizations were respectively TDN2109-TDX1213,TDN2108-TDX1216 and TDN2107-TDX1217,the settling velocity,supernatant turbidity,compression layer height was respectively 23cm/min,50NTU,42ml for TDN2109-TDX1213,24cm/min,80 NTU,45ml for TDN2108-TDX1216,28cm/min,70 NTU,31ml for TDN2107-TDX1217.3.Adding respectively TDX1215,TDN2109-TDX1213,TDN2108-TDX1216,TDN2107-TDX1217,the sedimentation effect of coal slurry was studied using the floc strength as evaluation index.It is found that all of the flocs strength are up to 1×10-8N and the supernatant turbidity is lower,about 50 NTU.4.Effect of common anionic flocculants on floc strength:the dosage is larger and floc strength is lower for PAM with molecular weight of 5 million;the floc strength is smaller,a small amount of dosage can not reach the maximum floc strength for PAM with molecular weight of 8 million with the dosage of 0.1 to 1ml;the floc strength is bigger for PAM with molecular weight of 12 million and 16 million,is up to 10-8N with the dosage of 0.2ml.5.When molecular weight is same,the order of floc strength is zwitterionic>cationic>nonionic>anionic adding PAM with a molecular weight of 8 million;it is anionic>cationic adding PAM with a molecular weight of 12 million when the dosage is smaller;in contrary,it is cationic>anionic with the increase of the dosage.6.The particle image velocimetry system(PIV)was used to determine the flow velocity in the tube,it is found that the flocculating effect is different with flow velocity in the tube.When the flow velocity in the tube is 40mm·s-1,the flocs strength are better adding all the anionic PAM,cationic PAM with a molecular weight of 12 million,zwitterionic PAM and nonionic PAM with a molecular weight of 8 million;When the flow velocity in the tube is 20mm·s-1,the flocs strength are better adding cationic PAM with a molecular weight of 5 million and 8 million;and increasing flow velocity,such as 100 mm·s-1,will destroy the structure of the floc resulting in the breakup easier.7.Calculating by the flocs strength formula Fc = 3/4??wWsmDm,the flocs strength are 5 × 10?1×10-8N.8.The industrial experiments were carried out using the novel optimization Pharmacy TDN2109-TDX1213 in Shendong a coal preparation plant,the results show that the dosage of flocculant and coagulant just is respectively 1/2 and 2/3 of the original amount in the f coal slime water treatment system,and overflow water turbidity is below 100 NTU,ensuring water closed cycle,improving the efficiency of the pressure filter and frame filter press.