Focusing on the occurrence of vanadium in carbonaceous shale,the important role of roasting in the process of extracting vanadium from carbonaceous shale is discussed,and the technical conditions of various roasting processes during extracting vanadium from carbonaceous shale are introduced as well as their advantages and disadvantages.The development trends are forecasted of extracting vanadium from carbonaceous shale in the aspects of comprehensive utilization,beneficiation-metallurgy combination and environment protection.

Experimental study was made on the influence of Na2CO3 as the additive and leaching agent on roasting-leaching of vanadium-bearing carbonaceous shale from Hunan.The results show that vanadium leaching rate changes with different roasting temperature and time and Na2CO3 dosage.The optimal roasting conditions are 800 ℃×2h and 2% Na2CO3 relative to the amount of ore.

The experimental study of vanadium extraction was carried out by direct acid leaching from the burning ash of low-calorific-value vanadium-bearing carbonaceous shale blended with coal.Based on single factor tests,the process conditions were determined including leaching liquid-solid ratio,dosage of sulfuric acid and aid leaching agent,leaching temperature,leaching time and stirring speed.Under the optimum leaching conditions,the leaching rate of vanadium in the ash is over 79%.

The static reducing process was studied for producing V2O3 in the resistance furnace using V2O5 as the raw material and solid carbon material as the reducing agent.The process has the advantages of low consumption of reducing agent,easy operation and high safety factor.Meanwhile,two-stage reduction was carried out during operational control with the first temperature of 650 ℃ and the second temperature of 1050 ℃,reducing vanadium loss and improving conversion speed of V2O5.And then high quality V2O3 can be obtained to provide high quality raw material for the production of high vanadium ferrovanadium and significantly reduce its production cost.

The feasibility was studied of leaching rare earth by column leaching from a low-grade rare metal complex ore containing a small amounts of rare earth and new-found in southwest China.The results show that weathered-crust elution-deposited rare earth ore in adsorption state is only about 30% in the above rare metal complex ore,and most of the rare earth exists in the presence of unweathered independent mineral deposit.After the above ore is processed by roasting-acid leaching,the leaching rate of rare earth is above 81%,the leaching rate of Nb is above 88%,and the leaching rate of Ga reaches 99.08%,with good leaching results of rare earth,niobium and gallium.

The process was studied of rare earth and niobium extraction from tailings of beneficiated complex rare metal associated ore.The results indicate that rare earth and niobium can be efficiently leached by sulfuric acid acidification-staged leaching.When the mass ratio of acid to ore is 1.8,acidification temperature is 350℃,acidification time is 120 min,the liquid-solid ratio of the first leaching stage is 1∶1,leaching temperature is 80℃,leaching time is 90 min,the liquid-solid ratio of the second leaching stage is 8∶1,leaching temperature is 25 ℃ and leaching time is 9 0min,the REO and Nb2O5 contents in the leached tailings are 0.96% and 0.75%,respectively,and the leaching rates of rare earth and niobium are 85.03% and 80.88%,respectively.Niobium leaching rate is 80.26% in the first stage and rare earth leaching rate is83.85%in the second stage.The recovery of niobium and rare earth can be realized by separately treating with the leaching solution from the first stage and the second stage.

Based on 60 kA bottom-cathode rare earth electrolysis cell,mathematical model was built of threedimensional electric field in rare earth electrolysis cell using finite-element analysis software.The electric filed distribution was simulated with different polar distances of 90 mm,100mm,110 mm and 120 mm,and the simulation results were analyzed.The results show that 100 mm is the best polar distance.

Extractive metallurgical technologies of tantalum-niobium are comprehensively introduced including alkalization decomposition,chlorination process,acid decomposition,fluoride fractional crystallization,solvent extraction,ion exchange and new extractive metallurgical technologies of tantalum-niobium.

Review is made of the main purification methods of gallium metal and their principles and characteristics,and the technical routes adopted by domestic companies for producing high-purity gallium.The advantages and disadvantages of various preparation technologies of high-purity gallium are compared.And the attentions are pointed out during high-purity gallium preparation.

Calcium,magnesium and boron were separated from lithium hydroxide completed liquid during carbonization with Bys-201 complexing reagent.Investigation is made on the effects of carbonization temperature and time,CO2 gas flow rate and dosage of complexing agent on complexation separation of calcium,magnesium and boron.And the optimal technical conditions were determined.The extraction rates of calcium,magnesium and boron can reach above 98% with the above process,and the produced lithium carbonate reaches the national standard for battery-grade lithium carbonate.