Recycling Utilization Of Indonesian Oil Sand Tailings

Based on the increasing status of the oil sands industry,a large number of oil sands tailings can not be properly managed,which leads to serious wasting of resources and environmental pollution issues.Therefore,the method of comprehensive treatment of tailings was systematically analyzed and studied by means of the laboratory preparation of ? hemihydrate gypsum and water glass(Na2Si O3).Results are deeply analysed to found the combinations of the experimental conditions and operating processes on products in this study.Dihydrate gypsum is obtained by adding sulfuric acid to the filtrate separated from hydrochloric acid dissolved tailings,and ? hemihydrate gypsum is prepared through salt solution method.Through single factor experiments and orthogonal experiments,considering of reaction rate?material cost?crystal water content stability?crystal morphology of the product,the optimum experimental conditions are as follow: the concentration of salt solution was 25%,the temperature was 98 ?,the ratio of solid-liquid was 1:6,and the order of influencing factors was: salt solution concentration>reaction temperature>solid-liquid ratio.SEM scanning electron microscopy was used to observe the product under the optimum conditions.Image shows that crystal was hexagonal columnar form,and grains are thick?compact?smooth on the surface and within less gypsum crystal particles.The optimum amount of sodium citrate as crystal modifier is 0.1%,and at this time ? hemihydrate gypsum crystals are short columns with 1?2 aspect ratio,which is considered as best ? hemihydrate gypsum form within less gypsum crystal particles.The residue separated from hydrochloric acid dissolved tailings is treated with different roasting treatment,and water glass is obtained through dry roasting method.The best operating conditions obtained by single factor and orthogonal experiment are as follow: the reaction temperature was 800?,the reaction time was 2h,the mass ratio of material(Na OH:Si O2)was 4:3.Under the above conditions,the Si O2 reaction rate was 72.15%.The influence order of each factor is: reaction temperature> roasting conditions> mass ratio> reaction time?The results of XRD showed that the raw Si O2 materials roasted before dissolution with acid is most conducive to the experiment,and the main constituents are present in two crystalline forms of Hexagonal and Tetrahedral.High temperature roasting removes the residual organic phase and the acid-soluble process dissolves the metal oxide.The treatment method destroyed part of the Si O2 crystal structure,reduced the activation energy needed by the reaction,and promoted the reaction of Si O2 with alkali at high temperature,which made it possible that the Si O2 reaction rate was increased from about 30% to 60%?70%.