| Oil shale slag is the waste come from the process of industrial extracting oil from the shale, burning shale as fuel, and generating electricity from shale. At present, most of China’s oil shale slag is stacked in open-air except for only a small amount being used, this not only causes environmental pollution but also wastes nature resources. Oil shale slag is a promising recyclable resource composed of varieties of hydrous alumina silicate mineral, and its major component is Al2O3 and SiO2. It will cause pollution and damage to the environment given that the oil shale slag is directly abandoned. Therefore, it is very important to economy, environment and industrial production, for that we take the oil shale slag as raw material to extract Al2O3 and silica from it.This paper aims at integrate utilization of oil shale slag to preparation of alumina and silica hydrated, to find and explore a practical technology for integrate utilization of oil shale slag. The work takes residue of Fushun oil shale as raw material, on the basis of full studied the oil shale slag content and phase composition, we first put forward extracting alumina by acid leaching, and then melting the enriched SiO2 containing residual with alkali to extract the silica hydrated. In this paper, first of all, the hydrochloric acid leaching process is studied to extract Al2O3 from the oil shale slag, and the optimum condition has been obtained; and then the extracting silica hydrated from the oil shale slag remain leached by hydrochloric acid before hand was studied. The results show as follow:(1) To process under the calcination condition of 700℃ is beneficial to improve the leaching rate of alumina from oil shale slag, and the appropriate calcination time is 2h.(2) In controlling the acid leaching temperature is 90-95℃ condition, the orthogonal experiment analysis find that hydrochloric acid concentration is the most significant factor on the leaching rate of alumina, secondarily is liquid-solid ratio of raw material, and the third is acid leaching time. Finally, we determine the optimum extracting alumina condition is that the concentration of hydrochloric acid is 7%, the liquid-solid ratio is 7:1, and the acid leaching time is 2h. In condition of the optimum extracting technology, the leaching rate of Al2O3 is 50.41%, and the utilization for hydrochloric acid is 50.13%.(3) Study on two step of countercurrent extraction technology using hydrochloric acid, we get the results that the optimum technology of two step countercurrent extraction process conditions is the concentration of hydrochloric acid is 9%, the liquid-solid ratio is 6:1, and the acid leaching time is 2.5h. On this condition, the leaching rate for AI2O3 is 73.26%, the utilization of hydrochloric acid can reach 69.31%. Compared with one step leaching dipping pickling process, the two step of countercurrent extraction can obviously increase the AI2O3 leaching rate and the utilization of hydrochloric acid. With the increasing of dosage of hydrochloric acid, the utilization of the hydrochloric acid is in downward trend.(4) Prepared AI2O3 from secondary leach liquor is 96.38% purity γ-AI2O3, the product structure is the prismatic crystal form, and the particle size is between 10 to 20 microns.(5) Prepared silica hydrated from leaching remaining behaves a form of typically mixed crystal, the SiO2 content reaches 97.58%, and the silica hydrated particle is not uniform for there are some reunion phenomenon occurred. Analysis By granularity assessment the median diameter of the product is 11.25 microns. |
PDF Full Text Request