| Both vanadium(V)and chromium(Cr)are my country's important strategic resources.They are metals with excellent physical and chemical properties and are widely used in metallurgy,chemical,aerospace and other fields.Currently,in the existing blast furnace smelting-converter-smelting-vanadium slag sodium roasting/water leaching process of vanadium extraction with vanadium-titanium magnetite as raw materials,the redox properties of vanadium and chromium are highly similar,and the vanadium and chromium in the vanadium slag All are transferred to the vanadium-containing solution.After the vanadium precipitation,chromium is enriched in the vanadium precipitation wastewater,resulting in the production of chromium and vanadium-containing wastewater sludge.The sludge becomes hazardous waste because it contains a large amount of chromium.Currently,there is no resource utilization method and can only be dumped.In addition,for high-chromium vanadium slag(namely vanadium-chromium slag),when a clean calcification roasting/acid leaching process is used,the vanadium extraction tailings obtained after leaching vanadium from the calcification roasting clinker of the vanadium slag contains chromium,but it has not been found yet.This suitable resource utilization method of chromium-containing tailings.Whether it is the dumping of vanadium sinking wastewater sludge or the shelving of chromium-containing vanadium extraction tailings,both have caused a serious waste of chromium resources and also caused a serious threat to the environment.In response to this,this article carried out research on the resource utilization and harmless treatment of vanadium sinking wastewater sludge and vanadium extraction tailings.For the wastewater sludge obtained from different vanadium precipitation wastewater detoxification treatment processes-vanadium chromium reduction slag and chromium sludge,the separation and recovery methods of vanadium and chromium were established based on ion exchange resin method.For the vanadium extraction tailings of vanadium-chromium slag,firstly,the vanadium extraction rate was increased by optimizing the leaching conditions to reduce the residual vanadium rate of the vanadium extraction tailings,and then the vanadium extraction tailings were used to produce chromium-containing pig iron.The slag desulfurization and dephosphorization methods are used to prepare for the subsequent production of pig iron.The waste water sludge vanadium and chromium separation and recovery method and the dephosphorization and dephosphorization method of vanadium extraction tailings established in this paper simultaneously realize or promote the detoxification and resource utilization of waste water sludge and vanadium extraction tailings,and are used for the vanadium industry.The green upgrade has laid the theoretical foundation.The main research contents and results of this topic are as follows:(1)Study on separation of vanadium and chromium from vanadium-chromium reduction slagIn the vanadium-chromium reduction slag,vanadium exists in the form of V(?),and chromium exists in the form of Cr(?).With the goal of leaching vanadium and chromium,the leaching conditions of vanadium-chromium reduction slag were optimized:the liquid-solid ratio was 15:1,the sulfuric acid concentration was 15wt%,the leaching time was 90min,and the leaching temperature was 80°C.At this time,the vanadium leaching rate reached 90%,the chromium leaching rate is 94%.After flocculating and desiliconizing the leachate,H2O2 is used to selectively oxidize V(?)to V(?)to convert vanadium element into vanadate anion,and then use anion exchange resin to adsorb V(?).The static adsorption conditions of ion exchange resin for V(?)are optimized:when the adsorption time is 240min and the temperature is 50?,the adsorption of the resin reaches equilibrium.The SEM characterization results of the ion exchange resin show that the adsorption of vanadium on the surface of the ion exchange resin is achieved by the ion reaction between Cl-and the vanadate anion of V(?).The dynamic adsorption results of the leaching solution of vanadium-chromium reduction slag show that the optimal bed height is 15cm and the feed rate is 5 ml/min,which is conducive to the adsorption and enrichment of V(?).(2)Study on separation of vanadium and chromium from chromium mudVanadium in chromium mud exists in the form of V(?)oxyacid anions,and chromium exists in the form of Cr(?)cations.With the goal of leaching vanadium and chromium in chromium mud,the leaching conditions of chromium mud are optimized;when the liquid-solid ratio is 15:1,the sulfuric acid concentration is 10wt%,the leaching time is 90 min,and the leaching temperature is 80°C,the maximum value of vanadium is The leaching rate is 94%,and the chromium leaching rate at this time is96%.The static ion exchange study results of the chromium mud leachate showed that when the adsorption time was 240min and the temperature was 50?,the adsorption of V(?)on the resin surface reached equilibrium.A dynamic experiment was carried out on the chromium mud leaching solution.The optimized dynamic experiment parameters were bed height of 15cm and feed rate of 5ml/min.At this time,it is most conducive to the adsorption and enrichment of V(?)on the ion exchange column.(3)Study on leaching vanadium from vanadium-chromium slag calcified clinkerThe vanadium-chromium slag is analyzed by XRD and XRF.The main components of the vanadium-chromium slag calcification clinker are(Fe0.6Cr0.4)2O3?SiO2?Ca3(VO4)2,etc.The leaching experiment of vanadium-chromium slag calcification clinker was optimized.The best leaching parameters were:leaching pH2.8,leaching liquid-solid ratio 4:1,leaching temperature 50?,leaching time 60min,and the maximum leaching rate of vanadium was 91.1%.During the leaching process of vanadium chromium slag calcification clinker,the leaching conditions have little effect on the leaching rate of other impurity elements except manganese.Under the best leaching conditions,the leaching rate of chromium is 1%,the leaching rate of phosphorus is 1.2%,the leaching rate of iron is 0.73%,the leaching rate of silicon is10.96%,and the leaching rate of manganese is the highest 29.56%.Vanadium valence analysis was carried out on the leaching solution of vanadium-chromium slag calcification clinker.The results showed that vanadium mainly migrated from the vanadium-chromium slag calcification clinker to the leaching solution in the form of V(?).XPS analysis of the vanadium extraction tailings after leaching showed that chromium is always present in the solid phase in the form of(Fe0.6Cr0.4)2O3 solid solution,and there is no change in valence state,and always exists in the form of Cr(?)and does not exist.Very toxic Cr(?).(4)Study on dephosphorization and desulfurization methods of vanadium extraction tailingsAiming at the problem that the high phosphorus and sulfur content of the vanadium extraction tailings from vanadium-chromium slag affects the subsequent smelting of chromium-containing pig iron,a dephosphorization and desulfurization method for the vanadium extraction tailings is established.The dephosphorization agent of the vanadium extraction tailings is a sulfuric acid solution,and the optimal dephosphorization conditions obtained are:the pH of the leaching solution is 0.5,the ratio of the leaching solution to solid is 1.5:1,and the dephosphorization rate reaches94%;The phosphorus content in the vanadium extraction tailings after dephosphorization treatment is 0.008%.The desulfurization agent of vanadium extraction tailings is ammonium carbonate solution,and the best desulfurization conditions are:ammonium carbonate mass fraction 8%,temperature 25?,time 15min,liquid-solid ratio 1:1,and the desulfurization rate is as high as 99%;The sulfur content in the vanadium extraction tailings after desulfurization treatment is 0.02%.XPS characterization results showed that the vanadium extraction tailings after dephosphorization and desulfurization treatment did not show highly toxic Cr(?). |
PDF Full Text Request