Preparation And Modification Of Silica Using Residue Of Oil Shale

Residue of oil shale is a kind of industry waste, which are used for producing oil,burning and generating electricity. Preparation of silica using residue of oil shale is trying tofind suitable methods in the industry area. Through the research, the optimum conditions arefound. In this paper, the activation temperature, dosage of acid, concentration of H₂SO₄ andreaction time are investigated. Besides, the sample is modified to improve its hydrophobicity.This paper introduces the technological conditions of preparing silica using four kinds ofresidues, which are semicoke of Longkou oil shale, semicoke of Huadian oil shale,Fushun-type retorting residue of Huadian oil shale and residue of Huadian oil shale fromcogeneration plant. Impurities, such as Al, Fe, Ti, can be effectively removed from the wasteresidue, adopting such purification operations as calcination, acid leaching and secondaryedulcoration to find a proper condition. Through the XRD, leaching rates of impurities atdifferent calcinating temperature, it's found that semicoke of Longkou oil shale and Huadianoil shale need to be calcinated, and the temperature separately are 650℃～800℃and 700℃～800℃,and the calcinating time is 1.5h. But burned residue of Huadian oil shale and theresidue from cogeneration plant, which have suffered high temperature processing, needn't tobe calcinated. The acid leaching conditions of calcinated semicoke of Longkou oil shale are:acid concentration 60%, the ratio of liquid to solid 5:1, reaction time 60min; and the acidleaching conditions of calcinated semicoke of Huadian oil shale are: acid concentration 50%,the ratio of liquid to solid 5:1, reaction time 90rain. The results indicate that the residuewithout suffering high temperature processing can be as the raw material to prepare silica. Inaddition, the sample of silica is modified by surfactant and silane coupling agent. The IRspectrogram of modified silica exhibits absorption bands assigned to the C-H stretchingvibration at 2913cm^-1 and broad absorption bands assigned to the C-N stretching vibration at1000-1100cm^-1. The results of contact angle show that the contact angle of two kinds ofmodified silica are greater than 90°, separately 150°and 109°. The results show that the surfaceof modified silica was alkylated, which indicates that the surface modification to silica issuccessful.The results show that the suitable raw materials for preparing silica are semicoke ofLongkou oil shale, semicoke of Huadian oil shale, Fushun-type retorting residue of Huadianoil shale. However, the silica prepared from residue of Huadian oil shale from cogeneration plant can't meet the national requirements, and it can be used to be ingredients of concrete,preparing brick and so on. The silica prepared from retorting residue contains thity percent ofquartz, and the lower crystallinity silica can be got by separation, which laid the foundationsof industrialization of preparing silica from retorting residue. Compare to the old method, it ismuch cheaper. The comprehensive utilization of the waste material has been achieved, andremarkable economic, environmental and social benefits are yielded.