Preparation Of Starch Phosphate Flocculates For Treatment Of Fine Coal And Preliminary Study On Their Performances

With the enhancement of mechanization degree and increase of fine-grain coal proportion,a large number of fine coal suspend in the washing waste water from coal Industry,which is very difficult to sink naturally. If it is discharged directly , not only pollute the environment seriously but also waste the resources. Therefore, It is very necessary to find a good, low cost,apparent economic benefits flocculant for modern coal preparation industry.To take full advantage of the plentiful starch resources in our country ,and meet higher demands of flocculant in the coal-bearing wastewater processing ,the preparation conditions of starch-based flocculants were studied,and the flocculant functions of starch phosphate as flocculant in the treatment of fine coal were investigated,and the mechanism of starch-based flocculants were discussed in this paper.Firstly, we studied the preparations of potato starch phosphate, the effect of the types of phosphate, the mass ratio of mixed phosphates, temperature, reaction time, the amount of mixed phosphates, the amount of urea and pH value to substitution degree of potato starch phosphate and reaction efficiency were investigated.Base on the results of single factor experiments,we found out the best optimum conditions to synthesize starch phosphate by five factors and four level orthogonal experiment.Immediately, the effects of adding dosages of the different degree of starch phosphate, pH value of the coal-bearing wastewater and mixing time on the flocculation performance were investigated.The flocculanting effects of different complex flocculants to coal-bearing wastewater and the elimination capacities on SS were also investigated and compared starch phosphate/native starch complex with starch phosphate/polyacrylamide complex flocculants. And the flocculanting effects of complex which native starch is10% of the total mass is very similar to the starch phosphate,and complex that polyacrylamide at the mass rate of 10% showed good flocculanting effects.In the end, the best technical conditions to prepare starch phosphate as flocculants in the treatment of coal-bearing wastewater was determined that the mass proportion of mix phosphates is1:1, (NaH2PO4:Na2HPO4=1:1),the reaction temperature is 155℃,reaction time is 2.5h,amount of urea is 6%, Ph is 5.7, amount of mixed phosphate is 9%. The best amount of the starch phosphate flocculant is 2mL in the treatment of SS 2852mg/L coal-bearing wastewater.To achieve good flocculation effect and economic benefits,We also can add the right amount of starch or polyamine in the treatment of coal-bearing wastewater.