Study On The Separation Of Silica From Copper Smelting Slag And Preparation Of Silica

Owing to the huge production of copper smelting slag and the lower efficiency and fewer increment space of the current comprehensive utilization,it can only be stored open in the natural environment,which pollutes the soil,water and air environment,and also brings great potential danger to the survival of human beings.It is urgent to seek efficient and comprehensive methods for disposal the copper smelting slag.In this paper,the acid leaching residue,which is obtained after oxygen pressure acid leaching was perfomed on the water quenched copper slag produced in a copper smelting plant in Yunnan Province is used as the research object,and a process of atmospheric alkaline leaching was proposed and studied for treating the acid leaching residue.The optimal process conditions of silica enrichment and recovery in the alkaline leaching process were invest igated,and the response surface methodology was used to optimize the alkaline leaching process of acid leaching residue under atmospheric pressure,and the conversion behavior of silica was investigated.The leaching kinetics of silica under alkaline conditions at atmospheric pressure was described.The white carbon black product was prepared with the leaching solution as raw material.The results obtained in the present study show that the alkaline leaching process of acid leaching residue under atmospheric pressure is feasible.Under the condit ions of leaching temperature of 130?,sodium hydroxide concentration of 20 wt%,ultrasonic intensity of 315 W,stirring rate of 500 rpm,liquid-solid ratio of 6 m L/g,leaching time of 60 min and adding 2.5 g sodium nitrate,the leaching rate of silica is 94.5 wt%.The leaching rate of silica can be increased by 7.8 wt% with the introduction of ultrasonic.The composit ion and phase analysis of the leached slag show that the main mineral phase of the leached slag is hematite,and it also contains a small amount of CaO.After certain treatment,it can be used as a high quality raw material for ironmaking operations.Response surface methodology(RSM)has been used to optimize the alkaline leaching process of acid leaching residue under atmospheric pressure.The model has high reliab ilit y,small fitting deviation,and good prediction results.The optimal experimental parameters after optimization are:the leaching temperature is 150?,the sodium hydroxide concentration is 25 wt%,and the liquid-to-solid ratio is 6.73 m L/g.Under these condit ions,the leaching rate of silica is greater than 99 wt%,which is significantly improved compared with the unoptimized process.The process result has been significant ly improved.The alkali leaching process of silica in acid leaching residue conforms to the JMA model.The characteristic parameter n of the leaching process is 0.0879,the apparent activation energy of the reaction E=10.42 k J/mol,the frequency factor of the reaction process A=42.6,and the kinetic equation is-ln(1-X_t)=42.6exp[-10420/(RT)]t^0.0879,and the alkali leaching process belongs to diffusion control.Using the leaching liquid as the raw material and the sulfuric acid solution as the acid source,the white carbon black product was prepared by adjust ing the reaction tempera ture and the ending pH,and the preparation conditions with good effects were determined:the stirring rate was 200 r/min.The leach solution was heated to 85? in a water bath,6 g sodium chloride was added,and then kept warm for a period of time.The pr epared sulfuric acid solution is dropped into the leaching solution to pH=3,after reaction for 1 hour,the product is aged at room temperature for 2 hours,and then washed with anhydrous ethanol and dist illed water to precipitate,filter and dry to prepar e white carbon black product.The oil absorption value of the white carbon black product is 2.2 m L/g,and the specific surface area reaches 295.588 m²/g,which meets the national level A standard of white carbon black.