| Oily sludge is a stable suspension emulsion colloid,composed of oil,water and solid particles.The components of oily sludge are quite complicated and it is possible that a high concentration of heavy metals could be found in oily sludge.The viscosity of oily sludge is very high,which makes it difficult to separate the solid and the liquid phase from oily sludge.The improper disposal or insufficient treatment of oily sludge can pose serious threats to the environment.Ti-bearing blast furnace slag is the industrial waste residue,which is produced by vanadium-titanium magnetite in blast furnace smelting in China.The quantity of Ti-bearing blast furnace slag is being generated in an ever increasing amount.However,due to the recalcitrant nature of Tibearing blast furnace slag,few technologies can reach a compromised balance between satisfying strict environmental regulations and reducing treatment costs,so Ti-bearing blast furnace slag is mainly treated by accumulation.Therefore,these two industrial solid wastes is a difficult problem to be solved urgently in the petroleum and iron and steel industries,following the principle of innocuity,minimization and utilization.In this paper,oily sludge and Ti-bearing blast furnace slag are obtained from the bottom sludge of oil tank in Shengli Oilfield and the high temperature metallurgical residue of Panzhihua Iron and Steel Company,respectively.The waste heat of Titaniumbearing blast furnace slag and the catalytic properties of metal oxides are used to the pyrolysis of oily sludge effectively,in order to obtain high-value energy of pyrolysis products.Glass-ceramics made from pyrolysis solid-phase products can stabilize harmful heavy metals to the purpose of product Solidification treatment,which can be used for practical application.Therefore,it is of great significance for realizing the synergistic resource utilization of oily sludge and titanium-bearing blast furnace slag.Firstly,in order to study the pyrolysis characteristics and kinetics of oily sludge under the participation of Ti-bearing blast furnace slag,thermogravimetry was used to describe the process.From TG/DTG curves,the pyrolysis of oily sludge could be divided into two stages: rapid weight loss stage(180-520°C)and slow weight loss stage(520-1000°C),and there possibly existed three independent reaction stages in the fast weight loss stage of oily sludge by Gauss Multi.Peaks Fitting for DTG curves,which were combine the volatilization stage of water and light oil components,hydrocarbon components pyrolysis stage and heavy oil component pyrolysis stage,respectively.The present work focused the effects of heating rate and slag-sludge ratio on the rapid weight loss stage and the kinetic model of oily sludge pyrolysis process.The results showed that higher heating rate and higher Sludge-Sludge Ratio were helpful to enhance the pyrolysis process of oily sludge,meanwhile the presence of Ti-bearing blast furnace slag evidently reduced the apparent activation energy of pyrolysis of oily sludge,and the maximum activation energy decreased by 47 k J/mol.Secondly,the effects of heating rate,slag-sludge ratio and pyrolysis temperature on the product yield and distribution characteristics of pyrolysis products of oily sludge participated by Ti-bearing blast furnace slag are investigated.The results showed that the addition of Ti-bearing blast furnace slag had certain effects on the yield and distribution characteristics of oily sludge pyrolysis products.The increase of pyrolysis temperature was beneficial to enhance the pyrolysis reaction strength,and the yield of three-phase products reached the maximum at 700°C.Proper slag-sludge ratio was favor to improve the heat transfer efficiency,and enhance the recovery of pyrolysis gas and liquid phase.Furthermore,higher heating rate promoted the pyrolysis reaction,which was conducive to the increase of hydrocarbon recovery,but made against the increase of oil yield.Finally,oily sludge pyrolysis solid products were used as raw materials to design the formula for the glass-ceramics without additives,and studied the effects of different crystallization temperatures on the properties of glass-ceramics.The results showed that the optimum heat treatment system of glass-ceramics was nucleation temperature of730°C and hold it for 1 h,then increase the temperature to crystallization temperature at 950°C and hold it for 2 h.Analysis result showed that the main crystalline phases were augite and clinopyroxene and the subordinate phases were Titanite with good structure with uniform grain sizes.Then the bulk density is 2.97g/cm3,the hardness reached to 7.71 Gpa and the acid-alkali resistance is lower than 0.05%.TCLP method was used to investigate the solidification effect of heavy metals by glass-ceramics and the results indicated that the concentration and leaching rate of heavy metals in pyrolysis solid products were higher than the glass-ceramics sample.After solidification treatment,the leaching concentration and leaching rate of heavy metals in the glass-ceramics samples are evidently reduced,especially the leaching rate of Cr from 26% to 1%.It can prove that using pyrolysis products to produce glass-ceramics is a feasible solidification treatment. |
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