Papers by Author: Xu Ming Wang

Abstract: Four industrial wastes: iron scraps, ceramsite, fly ash and steel slag were studied as reactive media for COD removal from the Fenhe River. Leaching tests demonstrated that iron scraps and ceramsite were relatively stable compared to steel slag and fly ash. Ca²⁺ was the main leaching ion. Batch experiment results showed that iron scraps and steel slag had better COD removal efficiency than ceramsite and fly ash. It was also found that the initial pH was important for COD removal and the COD removal efficiency of iron scraps was linearly correlated with the initial pH (R²=0.982). Compared to batch experiments, COD removal was much higher in column tests, which were about 70%, 54%, 46% for iron scraps, steel slag and ceramsite respectively.

Abstract: Three methods, sodium hydroxide hydrothermal treatment, sodium carbonate calcination-hydrothermal treatment, and sodium hydroxide calcination-hydrothermal treatment, were used to modify fly ash as an adsorbent for wastewater treatment. Results from XRD analysis show that the fly ash with sodium hydroxide hydrothermal treatment the fly ash has a porous structure in which alumina disappear and silica is dissolved. With sodium carbonate calcination-hydrothermal treatment exhibits nepheline and Na₇Al₇SiO₁₆ structures. With sodium hydroxide calcination-hydrothermal treatment a zeolite-like new phase and porous structure can be observed. Results from SEM and BET indicate that the specific surface area increases from 0.160 m²/g for the raw material to 7.22 m²/g, 1.05m²/g and 276 m²/g for the respectively modified by sodium hydroxide hydrothermal treatment, sodium carbonate calcination-hydrothermal treatment and sodium hydroxide calcination-hydrothermal treatment. The three modified fly ash were used to treat a concentration of 80 mg/L of ammonia-nitrogen wastewater. The removal capacity for the three modified ash was 58%, 44% and 94% respectively that was significant higher than 14% for the original fly ash. These results show that fly ash by alkali modification can improve the activity and enhance the ability of ammonia-nitrogen wastewater treatment.

Abstract: In this work, the crystallization of Carnallite from waste brine of Qaidam Basin in Qinghai province was studied based on NaCl-KCl-MgCl₂-H₂O phase diagram. According to this study, a new crystallization pathway to recycling waste brine was developed. The carnallite salt was formed by using this technology during the waste brine evaporation. The experiment data shows that 5 tons of waste brine was required to form one ton of the carnallite. The average grade of carnallite prepared by using this procedure was about 19.40 % of KCl, 16.92% of NaCl, 28.80% of MgCl₂, and 0.82% of CaSO₄. This study provides an opportunity to utilization of the waste brine.

Abstract: The run-of-mine of complex lead-zinc ores in Yunnan contains 3.26% lead and 2.54% zinc. When traditional selective flotation flowsheet was adopted, 3.77% yield and 61.92% grade of lead concentrate as well as 5.65% yield and 38.67% grade of zinc concentrate were achieved. Simultaneously, 72.39％ lead recovery and 3.83% zinc grade in lead concentrate as well as 80.64% zinc recovery and 6.39% lead grade in zinc concentrate were obtained. Lead concentrate and zinc concentrate obtained from selective flotation contain each other severely, resulting in low recovery of lead and zinc and severe loss of metal, which influences subsequent smelting flowsheet. In addition, due to requirement of large amount of depressant and activator while separating lead and zinc in the process of mineral processing, the cost is very high and the compositions of tail water which can not be recycled by the plant are very complicated. For the combined flowsheet of beneficiation and metallurgy, bulk flotation flowsheet was adopted. Therefore, 11.22% yield of combined lead and zinc concentrate with 25.55% lead grade, 18.33% zinc grade and 86.36% lead recovery were obtained. Gravity separation technology was utilized to separate combined concentrate of lead and zinc. After selecting out part of high quality lead concentrate, the remaining combined concentrate of lead and zinc was treated by acid leaching under high pressure. The final leaching efficiency of zinc was able to reach 97%. The new combined flowsheet has lots of advantages such as shorter flowsheet of beneficiation, simpler reagents, more direct reuse of backwater and higher recovery of metals.