Experimental Study Of Preparing Humic Acid From The Coal Slime Oxidation

With the improvement of raw coal production and the selected proportion, the coal slime output is rising. At present, the primary treatment methods include burned and open dumps, this not only bring environmental pollution, and it is a waste of resources. Coal slime was prepared humic acid, which solved the problem of coal slime using single and raised its economic value.This topic researches the preparation of humic acid by huangling coal slime oxidation. The first,coal slime pickling remove metal ions, measuring the amount of metal ions in hydrochloric acid of after pretreatment, and confirming hydrochloric acid p H. Then it was oxidized through heating in air and H₂O₂, to determine content of humic acid in coal slime after oxidation by titration method, to determine the best oxidation method. Finally the humic acid sodium salt was extracted of from oxidation coal slime by Na OH, and added hydrochloric acid or strong acid type cation exchange resin by acid precipitation technology to gain the humic acid product.In pretreatment experiment of coal slime, the better effect is that p H=1 hydrochloric acid treatment soak coal slime, which can get rid of about 3% of the metal ion（Fe, Al, Mg, Ca）. In experiments coal slime oxidized, it was oxidized by two ways: one is in the heating oxidation, oxidation temperature 310 ℃, oxidation time 6 h, content of humic acid is 34.64%; The other is H₂O₂ oxidation, 30% H₂O₂ oxidation coal slime, oxidation temperature 40 ℃, oxidation time 48 h, content of humic acid is 2.21%. Obviously, heating oxidation method is better. In alkali extraction and acid precipitation preparing humic acid experiment, through the single- factor and orthogonal tests, the influence of oxidation temperature, oxidation time, lye concentration, solid- liquid ratio, reaction time, reaction temperature, acid precipitation p H on humic acid production rate were studied. Using the coal slime in the huangling, the optimum reaction conditions are oxidation temperature 310℃, oxidation time 6 h, lye concentration 1.5%, solid-liquid ratio1:25, reaction temperature 95℃, reaction time 2 h, acidification p H 1.5, and humic acid production rate was 26.84%. The priority of the influence factors by the orthogonal tests is as follows: the lye concentration, oxidation time, oxidation temperature, extraction temperature, extracting time. In alkali strong acid type cation exchange resin preparation experiment, humic acid production rate was 24.37% under the optimal conditions.Products was humic acid through the analysis of IR and UV spectra. And it was separated, results showed that content of black rot acid was more than 95%. It was prepared humic acid that humic acid purity is 85.4%, the total acidity is 7.761 mmol/g, carboxyl content is 5.625 mmol/g hydroxyl content is 2.136 mmol/g, ash content is 4.56% by alkali extraction and acid precipitation, humic acid purity is 92.54%, the total acidity is 8.013 mmol/g, carboxyl content is 5.804 mmol/g hydroxyl content is 2.209 mmol/g, ash content is 2.44% by alkali strong acid type cation exchange resin preparation.