| The comprehensive utilization can not only recover the source but also control the cinders pollution. Transparent iron oxide pigments have been made from sulfate, which is prepared from cinders. The novel process of the cinders comprehensive utilization has been developed.Transparent iron oxide pigments have been made by air oxidation method and sodium chlorate method. The factors of the pigment preparation and surface treatment have been studied in detail. The pigments have good granularity uniformity and dispersity nature.A good quality transparent yellow iron oxide pigments have been made by air oxidation. The effect of temperature, air flow rate, stirring speed, initial mixing condition on the reaction rate and the speed form have been studied systematically. A large quantity of Fe3O4 is produced during initial reaction, then Fe3O4 is changed gradually into a -FeOOH.Polyethylene glycol as dispersing agent by comparing it with other dispersers when the quantity of polyethylene glycol is 0.45% of FeSO4.7H2O weight, DBS as surface-active agent is 0.5-2.0% of FeSCU.THiO weight, the diphenyl guanidine as flocculating agent is 10% of DBS weight. The modified pigments particles have best dispersity in solvents and the partial size of the pigment has good distribution.TEM proves that yellow iron oxide pigments made by oxidations spindle shape. Major axis is about 75nm, minor axis is about 25nm, XRD discovers that the pigment is a -FeOOH. Air oxidation method has many advantages such as simple technology, low cost and low consume.The best factors of sodium chlorate oxidation are as follows.Fe2"1" concentration is 1.0~1.5mol/L, amount of NaClO3 is 1.05 times of NaClO3 theoretical amount, reaction temperature is 60~65癈. The conversion rate of Fe2+ to Fe3+ is 99% under the above reaction factors.When the reaction temperature is 40-45℃ , its reaction time is 30~45minutes, pH is about 7.0, pure brown Fe(OH)3 colloid is generated.Fe(OH)3 colloid is changed into yellow iron oxide pigments a -FeOOH after putting iron sheet and 30ml of 1.5mol/L Fe2(SO4)3 added hi the colloid, Fe(OH)3 colloid is changed into a -FeOOH when the reaction temperature is 80-85 ℃ and pH value of solution is 3.6-3.8.When the temperature of surface treatment is 80 ℃, the reaction time is l~3h, the quantity of polyethylene glycol is 0.45% of FeSO4.7H2O amount, DBS as surface-active agent is 0.5% of FeSO4.7H2O amount, disphenyl guanidine as flocculating agent is 10% of DBS amount.TEM texts that the particles of transparent yellow iron oxide pigment prepared by sodium chlorate oxidation are spindle shape, too. Major axis is about 65nm, minor axis is 15nm, axis ratio is about 4.3. XRD proves that yellow iron oxide pigments is a -FeOOH. The sodium chlorate oxidation is a better method than air oxidation.TG-DTA tests show there are two TG weight loss peaks and two DTA exothermic peaks hi the TG-DTA curves. The temperature ranges of the perks are respectively 29. 8 ~ 98.6癈 and 214.6~316.7癈, the first loss weight occurs and the second loss weight are resulted from losing free water and losing structural water respectively.When calcinations temperature is 200 ℃ , calculations time is Ih, a -FeOOH does not react. When the temperature is 400 ℃, the reaction time is Ih, the transparent yellow iron oxide pigment is changed into the transparent red iron oxide pigments. |
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