Research Of Microfiltration And Removing Iron Process Of Titanium Dioxide

Titanium dioxide is a kind of important inorganic chemical paint, and there is avery key step in its production process, that is washing and bleaching. The quality ofthe washing directly decide the pigment properties and optical properties of titaniumdioxide. Industrial washing equipments generally include the centrifuge、vacuumdrum leaves filter machine,、vacuum leaves filter、the diaphragm pressure filter, etc.The use of these traditional equipments takes a lot of manpower and materialresources, and generally is the intermittent operation, and we need to regular maintainthe equipments, and the production process needs a long time. The majordisadvantage is water consumption, and it causes the waste of water resources.Firstly vacuum pump was used to filter for removing iron ion. we Investigatewashing water content how to effect the removing of iron ion. At the start of theprocess, the iron ion is easier to eliminate, to the last, the remove of iron ion isdifficult. To reach the washing requirements,1g of titanium dioxide need about42.0532g water. Adding acid in water contribute to remove iron ion, the mostappropriate acid concentration is:20g/L in water,and the right operationtemperature is55℃, and the most appropriate proportion ofdissolving water is40%total washing water, and ultrasonic oscillations15minutes is the best.Ceramic membrane equipment was used to research the microfiltration of thetitanium dioxide. First with water as the research object, we get pure waterpermeability coefficient and Original filtering flux through microfiltration membrane.Then we filter different concentration of titanium dioxide,and investigate pressure、temperature、 flow velocity、 concentration how to effect the flux of ceramicmembrane equipment. The pressure for microfiltration process is the main drivingforces behind, and we increase the pressure, the flux increased significantly. To filterwater, the relationship of flux and pressure is linear. Filtering low concentrationtitanium dioxide grout, the relationship between flux and pressure is a linearrelationship. Filtering high concentration of titanium dioxide grout, we add pressure,in the later flux ascension is not obvious. However, when the pressure is high, theoperation stability of membrane equipment is worse.0.2-0.4MPa can meet theproduction requirements. Improving the flow velocity, membrane flux will alsoincrease. Especially filtering high concentrations of titanium dioxide slurry, we improve the flow velocity and the flux increase quickly. In high flow velocities,membrane equipment operation stability is good. But in high velocity, the energy lossis bigger. Generally2-4m/s can meet the production requirements. Increasingtemperature help membrane flux ascension, but the influence is not very big.,generally, increasing10℃, the flux improve16.47-20.59Lm-2h-1. The higher theconcentration, the lower the membrane flux. The membrane permeability flux andmaterial liquid concentration logarithm has certain linear relation between them.Joining a small amount of iron ion, the impaction to membrane flux is not big, but tojoin a large amount of iron ion, membrane flux decline rapidly. After filteringtitanium dioxide slurry, we use physical cleaning, namely moisture recoil form, andmembrane flux can return to more than95%. But filtering titanium dioxide groutcontaining iron ion, we must use the chemical cleaning way, and join sulfuric acid toclean, and membrane flux can return to more than88%.We adopt ceramic membrane washing equipment for removing iron research.0.2um ceramic membrane can’t intercept iron ions, which can all pass through film hole.But in the filtration of titanium dioxide grout containing iron ion, titanium dioxide canadsorb iron ion in the operation process. Adopting ceramic membrane washingequipment for removing iron, water consumption is low, and it can save water by15.15%compared with the traditional method.