Study On Resource Utilization Of Red Mud And Chromite Ore Processing Residue

The status of non-ferrous metal smelting industry is extremely important in the process of modern industrial production,but it will produce a lot of waste slag in the process of construction and development.At present,the comprehensive utilization rate of these wastes is relatively low and cannot meet the standards and requirements of national planning,and the comprehensive utilization of resources is facing a severe test.According to the actual situation of the non-ferrous smelting market in Chongqing,it is found that the storage of Bayer process red mud and chromite calcium-free roasting slag are large and difficult to consume on a large scale.Therefore,how to find a reasonable direction for comprehensive utilization of resources according to the actual situation of the market and combining the characteristics of red mud and Chromite ore processing residue.On the basis of theoretical research,it is the main problem to be solved urgently at this stage to continuously develop,improve and upgrade the existing technology,equipment and process to maximize the utilization value of non-ferrous metal smelting waste residue.(1)In this study,combined with the characteristics of strong alkalinity of red mud and strong acidity of waste acid produced by titanium dioxide,acid leaching of red mud was carried out with titanium dioxide waste acid to reduce alkalinity.The effects of acid leaching temperature,acid leaching time,waste acid concentration,liquid-solid ratio and stirring speed on the alkali reduction rate of red mud were studied,and the leaching of aluminum,silicon,iron and calcium in red mud during the alkali reduction process was investigated.characteristic.The results showed that when the acid leaching temperature was 40℃,the reaction time was 10 min,the liquid-solid ratio was 4:1,the concentration of waste acid was 0.6238 mol/L,and the stirring rate was 300 r/min,the leaching rate of sodium in red mud was improved.It reaches 92.3591%,and the sodium content in the red mud after alkali reduction is only 0.2674%,which meets the requirement of building materials raw materials for the sodium content to be less than 1%.(2)In this study,the reducing substances produced by the pyrolysis of rice husks were used to detoxify chromium residues by dry detoxification.The rice husks and chromite processing residues were mixed for bulk and tablet preparation,and then placed in a muffle furnace for pyrolysis and reduction of chromite processing residues for detoxification.The detoxification effect of chromite processing residues was investigated under different process parameters such as sample preparation technology,rice husk addition amount,pyrolysis temperature,pyrolysis holding time and pyrolysis heating rate.The optimal parameters were determined as follows:under the tableting process,the addition amount of rice husk was 1 g/g,the pyrolysis temperature was 500℃,the pyrolysis holding time was 20 min,and the heating rate was 10℃/min.Under these conditions,it was found that the detoxification rate of the chromite processing residue after pyrolysis reduction in the tableting process was better than that in the bulk process,and the total Cr(VI)content in the chromite processing residue was reduced from 1000.89 ppm to 52.54 ppm,and the detoxification rate was the rate increased from 93.76%in the bulk process to 96.75%in the tableting process,an increase of nearly 3%.At the same time,the phase of the chromite processing residue before and after detoxification was compared,and it was found that the phase of the chromite processing residue before and after detoxification hardly changed,and the main structure was spinel.The detoxified chromite processing residue has reached the hazardous waste identification standard of Cr(VI)stipulated in the national standard"GB 5085.3-2007",and belongs to the second category of general industrial solid waste in the national standard"GB 18599-2001"(Cr(VI)below 3 mg/L and total chromium below 9 mg/L).(3)Using the reducing substances produced by the pyrolysis of rice husks,the iron-containing oxides dispersed in the chromium slag are pyrolytically reduced by the method of pyrolysis,which is used to prepare a catalyst for catalytic ozonation,and the simulated phenol wastewater is used to Its catalytic performance,reuse times and safety were evaluated.The effects of different rice husk addition amount,reduction temperature,holding time and heating rate on the catalytic effect of the prepared ozone catalyst were investigated.Under the experimental conditions that the reaction temperature was room temperature,the reaction pressure was 0.1 MPa,the ozone concentration was 50 g/m3,the ozone flow rate was 2 L/min,and the amount of ozone catalyst was 1 g/L,200 mg/L phenol wastewater was used to the prepared ozone catalysts were evaluated.The optimal process parameters were determined as follows:the addition amount of rice husks was 0.75 g/g,the reduction temperature was 1000℃,the holding time was 15 min,and the heating rate was 20℃/min.Under these conditions,the prepared ozone catalyst has excellent performance,which can degrade 99%of phenol in phenol wastewater within 60 min,and the degradation rate of TOC can also reach 92.69%.At the same time,the ozone catalyst has excellent catalytic performance in repeated experiments for 8 times,and the Cr(VI)concentration in the treated wastewater is also far lower than the requirements of the national comprehensive wastewater discharge standard.(3)Using the reducing substances produced by the pyrolysis of rice husks,the iron-containing oxides dispersed in the chromite processing residues are pyrolyzed and reduced by the method of pyrolysis,which is used to prepare a catalyst for catalytic ozonation,and the simulated phenol wastewater is used to its catalytic performance,reuse times and safety were evaluated.The effects of different process parameters such as the addition amount of rice husk,reduction temperature,holding time and heating rate on the catalytic effect of the prepared ozone catalyst were investigated.Under the experimental conditions that the reaction temperature was room temperature,the reaction pressure was 0.1 MPa,the ozone concentration was 50g/m~3,the ozone flow rate was 2 L/min,and the amount of ozone catalyst was 1 g/L,200 mg/L phenol wastewater was used to the catalytic ozonation ability of the prepared ozone catalysts was evaluated.The optimum process parameters were determined as follows:the addition amount of rice husk was 0.75 g/g,the reduction temperature was 1000℃,the holding time was 15 min and the heating rate was20℃/min.Under these conditions,it was found that the prepared ozone catalyst had excellent performance,which could degrade 99%of phenol in phenol wastewater within 60 min,and the degradation rate of TOC could also reach 92.69%.At the same time,the ozone catalyst has excellent catalytic performance in repeated experiments for 8 times,and the Cr(VI)concentration in the treated wastewater is also far lower than the requirements of the national comprehensive wastewater discharge standard.