Using dolomite calcined powder as raw material,the Ca and Mg elements were separated by ammonium leaching method,and then high-purity nano-MgO was prepared by carbonization method,and the more suitable process conditions for carbonization reaction,heavy magnesium water pyrolysis,basic magnesium carbonate calcination and other processes were investigated and determined as follows:carbonization reaction process:carbonization endpoint pH value of 7.5,CO2 flow rate of 0.4 L/min,reaction temperature of 15℃,stirring rate of 400 r/min;Under these conditions,the conversion rate of MgO could reach 87.79%.Mg(HCO3)2 solution pyrolysis process:pyrolysis temperature of 95℃,pyrolysis time of 40 min;Under these conditions,the pyrolysis rate of Mg(HCO3)2 solution reached 94.46%,and the pyrolysis intermediate product was monoclinic 4MgCO3·Mg(OH)2·4H2O.4MgCO3·Mg(OH)2·4H2O calcination process:calcination temperature of 700℃,calcination time of 1 h.Under the above optimization conditions,the MgO content of the prepared MgO sample reached 99.11%,and the XRD and FE-SEM characterization of the sample showed that the prepared MgO sample was a cubic crystalline nano-MgO with a particle size of about 30 nm.
In order to solve the problems of mineral condensation and algae removal technology,such as asynchronously remove nitrogen and phosphorus,easy loss of minerals,a ldge amount of sediment,and short duration of removal effect.The adsorption and removal properties of NH4+-N,TP,Chl-a and TUB by 11 mineral materials were determined and screened.Five types of unburned green zeolite based composite materials(NGZC)were prepared based on green zeolite with the optimal NH4+-N adsorption effect.The NGZC surface structure was observed,the influences of the amount of foaming agent and cement,the material ratio of green zeolite and the other minerals on the water purification performance were discussed and the effects of factors such as amount of NGZC dosage,reaction temperature and time of water treatment on the removal of multiple pollutants from river sewage were also discussed.The results showed that under the set curing conditions,the optimal preparation conditions were as follows:10%-15%cement,0.25%-0.5%foaming agent,mass ratio of green zeolite and oyster shell,convex clay,active clay,hydrotalatite,red jade soil for 8∶2,4∶6,6∶4,4∶6,4∶6.The optimal water treatment conditions were as follows:adding 4 g NGZC in 200 mL polluted river water at 25℃,and the best treating time was 3 d.This study can provide low-cost composite water purification materials and new technologies for the pollution remediation of algal eutrophic water bodies,the resource utilization of non-metallic minerals,and water and soil conservation,etc.
Laterite-type weathered ilmenite has high mud content in the raw ore due to the more complete weathering degree,which makes the traditional process of sorting more difficult,and the TiO2 grade in the concentrate is more difficult to achieve the quality requirements of the industry standard under the premise of guaranteeing the recovery rate.In this paper,for the rough concentrate of lateritic weathered ilmenite with TiO2 grade of 43.92%,ultrasonic cavitation effect was used to desliming and removing impurities to achieve the purpose of further improving TiO2 grade.The relationship between ultrasonic frequency,stirring time,stirring speed,slurry concentration and the desliming rate and grade of ilmenite crude concentrate was investigated in a conditional test.The results showed that under the ultrasonic frequency of 30 kHz,stirring time of 30 min,stirring speed of 2 000 r/min,and slurry concentration of 30%,a titanium concentrate with a desliming rate of 7.88%,a TiO2 grade of 46.05%,and a recovery rate of 96.58%was obtained.The final product quality met the industry standard YS/T 351-2015"ilmenite concentrate"for grade V quality requirements,providing technical reference for improving the quality and reducing impurities of similar titanium coarse concentrates.
After mixing Na2S2O8 with BaS solution,it will uniformly react to generate crystal forming SO42-,which can then undergo homoge-neous precipitation reaction with Ba2+ to generate BaSO4.BaSO4 powders were prepared using them as raw materials,the crystal phase,morphology and particle size distribution of BaSO4 were characterized,and the factors affecting the particle size of BaSO4 powder were studied.The results showed that changing the addition method of Na2S2O8 from one complete addition to multiple equal additions,or increasing the reaction temperature,or decreasing the concentration of BaS solution,or reducing the amount of Na2S2O8 added,the average particle size of BaSO4 powder will significantly increase.After adding 0.3 mol Na2S2O8 into 0.5 mol/L BaS solution at reaction temperatures of 20℃and 100℃,the average particle sizes of the prepared powders were 0.727 μm and 0.873 μm,respectively.The results indicate that under appropriate reaction temperature,by adjusting the concentration of BaS solu-tion and the amount of Na2S2O8 added,the homogeneous precipitation method can directly prepare submicron BaSO4 powder.
In order to study the pyrolysis process of natural rock asphalt in north Sichuan,and investigate the effects of carbonization temperature and carbonization time on its pore structure and element composition during liquid phase carbonization,Guangyuan rock asphalt was used as raw material to prepare porous carbon materials by carbonation-activation method.The thermogravimetric analysis of raw materials showed that the main weight loss temperature range of rock asphalt was 400-600℃,the maximum weight loss rate present in 450℃,and the residual carbon rate was 56.35%at 1 000℃.Increasing carbonization temperature and extending carbonization time would promote the pyrolysis and polycondensation reaction of asphalt,its aromaticities and hydrophobicity were enhanced,while the polarity decreased,at the same time,its volatile components were continuously expelled and the polycyclic aromatic molecules tended to be arranged in a directional manner.The specific surface area increased during this process.ASUK4-2 had a maximum specific surface area,which was 365.14 m2/g.The nitrogen adsorption-desorption isotherms curve of each sample belonged to type II,and there was a hysteresis loop of type H3.The pore size distribution was mainly mesoporous,with a few large pores and micropore.This research provided a reference significance for investigating the carbonization process and material structure changes of natural rock asphalt under high temperature environment.
