Surface Modification Of Metallurgical Solid Waste Iron Oxide Obtained By Dry Process And Its Application

Metallurgical solid waste iron oxide obtained by dry process is a by-product of acid regeneration process in the cold rolling production of steel,and its output is increasing year by year.However,the iron oxide is produced at high temperatures,which lacks organic functional groups on the surface,and its dispersibility in the medium is poor.Therefore,the price is lower and the scope of application is narrower.Seeking a low-cost,large-scale use of the iron oxide is a problem that needs to be solved urgently.In this paper,the iron oxide obtained from Maanshan NO.1 steel plant was taken as the research object,and its basic physical and chemical properties were analyzed and compared with iron oxide obtained by wet process.The surface modification of the iron oxide was carried out by coupling agent method,organic acid method and electrochemical method.Finally,the modified iron oxide was added to natural rubber for application research.Main conclusions are as follows:The purity of the iron oxide was 99.27%,which was hexagonal crystal structure.The crystal growth was uneven,and the iron oxide particle cluster phenomenon was serious.The iron oxide by dry process had poor dispersibility in xylene,and its aqueous suspension had a pH of 3.16 and an oil absorption of 40.0 mL/100g.The iron oxide by wet process had a purity of 98.75%,and its particles were uniformly round and had a particle size of about 200 nm.It exhibited-OH hydroxyl out-of-plane bending vibration peaks at 802cm^-1,893cm^-1,and 1122cm^-1,respectively.The iron oxide by wet process had good dispersibility in xylene,the aqueous suspension had a pH of 5.13 and the oil absorption was 42.5 mL/100g.After the modification by coupling agent,dispersibility of iron oxide by dry process was improved.No new functional groups were produced,and the pH value of iron oxide aqueous suspension and the oil absorption did not change significantly.After the modification by organic acid,dispersibility of iron oxide was slightly better than that by coupling agent,and no new functional groups were produced.The pH of all sample aqueous suspensions increased in varying degrees,with oxalic acid modified samples being 4.49,acetic acid 3.75,and citric acid 3.60.No new functional groups appeared in the electrochemically modified acetic acid system,and the dispersibility was improved.The pH value of the aqueous suspension increased first and then decreased with the energization time,and the voltage tended to increase gradually.In the oxalic acid system,a new infrared absorption peak appeared at 818 cm^-1,1317 cm^-1,and 1357 cm^-11 at a concentration of 0.1 mol/L,which may be Fe-COOH or Fe-OH bond.The pH value of the aqueous suspension increased with the energization time,oxalic acid concentration and current,and the oil absorption had not changed significantly.In the citric acid system,the sample had new absorption peaks around 910cm^-1,1047cm^-1,and 1382cm^-1,its dispersibility and oil absorption increased with the power-on time,which may be related to the generation of new functional groups.The pH value of the sample aqueous suspension gradually increased with the concentration of citric acid and voltage,and it had gradually approached the value of iron oxide by wet process?5.13?.The electrochemically modified iron oxide was well dispersed in rubber,and the dispersion rate was above 62%.However,the dispersion rate of iron oxide by wet process in rubber was only 58.91%,and the white block particles in the dispersed photos were obvious.After adding modified iron oxide to rubber,the vulcanization property,rebound resilience,compressive stress strain and tensile properties of rubber were improved compared with iron oxide by wet process rubber,and there was no significant improvement in the compression heat build-up of rubber.