| Under the overall environmental protection requirements of"promoting green development and cultivating harmony between humans and nature",it is the core and key to solving the problem of industrial solid waste utilization that insisting on the comprehensive utilization and recycling of waste.The industrial solid waste containing Mg,Al,Fe,Ti,Si,etc.has the characteristics of many valuable components,complex composition,and difficult comprehensive utilization.Guided by physics and chemistry,based on related theoretical knowledge of reaction thermodynamics,kinetics,interfacial mass transfer,chemical precipitation,crystal chemistry,etc.,these contents like the influence law of factors,thermodynamics,kinetic models and parameters,interfacial mass transfer and enhancement,chemical precipitation behavior and law,new leaching-separation technology for Ti-bearing blast furnace slag and asbestos tailings in the leaching-separation process were studied by theoretical calculation analysis and experimental verification.1)The technological mineralogical characteristics of titanium-bearing blast furnace slag and asbestos tailings were ascertained.The possible reactions of sulfuric acid roasting activation and the distribution dominant area map of leaching components for Ti-bearing blast furnace slag and asbestos tailings were obtained,which laid the foundation for Ti-bearing blast furnace slag and asbestos tailings.The results showed that sulfuric acid roasting has a good activation effect on Ti-bearing blast furnace slag and asbestos tailings.The leaching ratio of titanium,aluminum,magnesium and iron can be improved.2)The factors such as reaction temperature,reaction time,extractant concentration,stirring speed,liquid-solid ratio effect on the leaching of Ti-bearing blast furnace slag roasted with sulfuric acid was revealed,and the kinetic parameters of the its main components leaching process were obtained.The control factors of the leaching reaction rate for each component in the slag are mainly diffusion control,which is also affected by crystallization,adsorption and other factors.Under different conditions,the reaction rate control factors of different components are different,such as at low temperature,the iron components leaching rate conrol factor is the liquid film diffusion control,titanium components leaching is controlled by chemical reaction,etc.3)The precipitation law and kinetics of Fe components in the sulfuric acid system is obtained,which lays the separation foundation of Fe components in the industrial solid waste acid leaching solution.The simulation solution was used to study,and the results showed that the hydroxide precipitation has a good separation effect on the iron component in the acidic solution.When the p H>3.5,the iron removal ratio can reach more than 95.0%,but the aluminum loss is about 10.0%,and with the p H rise,the loss increases sharply.When the N,N-Diethylammonium O,O'-Dicyclohexyldithiophosphate(DADCDP)is used for complex precipitation to separate the iron component in the acidic solution,the iron removal ratio is as high as 99.84%,while the loss of aluminum is less than 2.01%.The whole coordination reaction mainly underwent two stages:fast reaction and slow reaction.In the fast reaction process,coordination reaction was mainly controlled by chemical reaction,its activation energy was 2161.71 J·mol-1.While in the slow reaction stage,it was mainly controlled by solid-phase diffusion,its activation energy was 5208.41 J·mol-1.The complex precipitation method has been well applied in the separating process of iron from the Ti-bearing blast furnace slag or asbestos tailings leachate.4)The continuous countercurrent enhanced leaching technology was proposed.The continuous countercurrent leaching technology was used to strengthen the target components leaching for the Ti-bearing blast furnace slag roasted with sulfuric acid.Compared with the leaching results under a optimized condition,the leaching ratios of titanium,magnesium,aluminum,and iron were increased by 6.65%,2.11%,2.07%and 26.80%,respectively,and the leaching was operated under the low extractant concentration and low reaction temperature.The leaching ratio of Mg component in asbestos tailings is as high as 99.32%,which has the advantages of lower reaction temperature and less acid consumption than the reported results.5)The valuable components separation in the sulfuric acid solution system by the hydroxide precipitation method and the complex precipitation method has been established,to realize the selective/step-by-step separation of the target components in the polymetallic acid solution system.The results showed that when using complex precipitation to separate the Ti-bearing blast furnace slag leachate,the iron component separation effect is good.In order to obtain high-whiteness products containing aluminum and magnesium,it is necessary to add complexed iron separation steps.When using hydroxide precipitation to separate the Ti-bearing blast furnace slag leachate,the Ti,Al,Mg and Fe components can be separated step by step,and the product quality is high.In the asbestos tailings leachate separation process,the combination of complex precipitation method and hydroxide precipitation method was used to successfully realize the high-efficiency separation of Mg components.The prepared Mg-containing product had a whiteness of 83.5 and a purity of 95.68%.6)According to the gas-liquid mass transfer double membrane theory,the Reynolds number(Re)correction factor was introduced,and the leaching rate equation was optimized,and a new interface mass transfer rate equation is obtained.Its general expression is as follows.(?),where kd=CReb.Based on the experimental data of leaching valuable components of Ti-containing blast furnace slag by sulfuric acid roasting and complex precipitation separation of Fe components in the leaching solution.The newly established mass transfer rate equation is used for application.Its linear correlation coefficient is higher than 0.96,and it has a good fitting result,indicating its applicability is favourable. |
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