由含铝酸及铝渣制备聚氯化铝铁净水剂

以含铝酸和铝渣工业废弃物为原料，无需加热装置，一步法制备出价廉高效的液体聚合氯化铝铁（PAFC）净水剂，考察了与PAFC净水剂伟4备有关的因素（新老铝渣活性、液固比、盐基度、固液分离等），提供了合理的生产工艺及操作条件，实现了废物资源化再利用。制备PAFC最佳工艺条件为：利用含铝酸与新铝渣反应，控制液固比3．0，添加催化剂，保温（96-105℃）反应5h后，加入阳离子聚丙烯酰胺（CPAM）除悬浮物即得到液体成品PAFC。将制备的PAFC产品应用于弱酸性染整洗水混凝脱色处理。结果表明，PAFC产品盐基度对混凝脱色效果影响显著，盐基度越高，矾花出现速度快，且矾花颗粒大，沉淀速度快，脱色效果好。

Variation of soda content in fine alumina trihydrate by seeded precipitation

High soda content in fine alumina trihydrate（ATH） limits its application and increases the soda consumption. The variation of soda content in the fine ATH by seeded precipitation was determined by detection of electric conductivity of solution, soda content in ATH, measurement of particle size distribution and microscopic analysis. The results show that high concentration of sodium aluminate solution, ground circulative seed, low temperature or fast initial precipitation rate increases the soda content in ATH. Soda mainly exists in lattice soda and less soda in desilication product （DSP） exists in the fine ATH precipitated from sodium aluminate solution with concentration of Al2O3 （ρAl2O3） more than 160 g/L and mass ratio of alumina to silica （μSiO2） of 400, and lattice soda decreases with increasing initial precipitation temperature, aging seed, and low precipitation rate and precipitation time. Results also imply that -＋ 4）Na Al（OH ion-pair influences lattice soda content in ATH on the basis of electric conductivity variation.

Dissolution kinetics of aluminum and iron from coal mining waste by hydrochloric acid

The extrartion of aluminum from coal mining waste(CMW) is an important industrial process.The two major problems in applications are low aluminum dissolution efficiency and high iron content in the raw material,which affect the quantity and quality of products.To improve the aluminum recovery process,the leaching kinetics of CMW with hydrochloric acid was studied.A shrinking core model was used to investigate aluminum and iron dissolution kinetics.Based on the kinetic characteristics,a process for recovering aluminum was proposed and tested experimentally.It is found that the aluminum leaching reaction is controlled by surface reaction at low temperatures(40-80℃) and by diffusion process at higher temperatures(90-106℃).The iron dissolution process is dominated by surface reaction at 40-100℃.The results show that iron could be dissolved or separated by concentrated hydrochloric acid.Fine grinding will improve aluminum dissolution significantly.

Effects of iron-containing phases on transformation of sulfur-bearing ions in sodium aluminate solution

Sulfides in the high-sulfur bauxite lead to serious steel equipment corrosion and alumina product degradation via theBayer process,owing to the reactions of sulfur and iron-containing phases in the sodium aluminate solution.The effects ofiron-containing phases on the transformation of sulfur-bearing ions(S2?,223S O?,23SO?and24SO?)in sodium aluminate solutionwere investigated.Fe,Fe2O3and Fe3O4barely react with23SO?and24SO?,but all of them,particularly Fe,can promote theconversion of223S O?to23SO?and S2?in sodium aluminate solution.Fe can convert to3Fe(OH)?in solution at elevatedtemperatures,and further react with S2?to form FeS2,but Fe2O3and Fe3O4have little influence on the reaction behavior of S2?insodium aluminate solution.Increasing temperature,duration,dosage of Fe,mole ratio of Na2Ok to Al2O3and caustic sodaconcentration are beneficial to the transformation of223S O?to23SO?and S2?.The results may contribute to the development oftechnologies for alleviating the equipment corrosion and reducing caustic consumption during the high-sulfur bauxite treatment bythe Bayer process.

Effects of MgO content and CaO/Al_2O_3 ratio on surface tension of calcium aluminate refining slag

Surface tension of calcium aluminate refining slag was measured by the Slide method at 1823 K.Based on different levels of the MgO content and the mass ratio of CaO to Al_2O_3,the effects of MgO content and the mass ratio of CaO to Al_2O_3 on surface tension were investigated.The results indicate that surface tension decreased with increasing MgO content(from 0 to 4.86%),followed by an increase with further increasing MgO content up to 11.33%.The trend that surface tension changed with the mass ratio of CaO to Al_2O_3 was the same as the trend that surface tension changed with the MgO content.The surface tension was varied from 0.617 N/m to 0.710 N/m,for the mass ratio of CaO to Al_2O_3 varying between 0.60 and 1.28.An attempt was made to estimate surface tension of CaO-Al_2O_3-MgO slag and its sub-system,and the application showed that the model worked well.