【摘要】 钢铁厂冷轧废水污泥中含有10%以上的铬、20%以上的铁和1.5%以上的锌(均以质量分数计)。为了从污泥中回收铬,首先研究了污泥中铬的形态,确定为Cr(Ⅲ);然后以碳酸钠为氧化助剂,将污泥与碳酸钠按一定比例混合后焙烧,再用水浸取。研究了碳酸钠的添加量、焙烧温度和时间、浸取时间和浸取方式对铬回收率的影响。研究表明,每克干污泥中添加0.6g或以上碳酸钠,在固定床上700℃焙烧4h以上,可实现60%以上的总铬浸出率,残渣为Fe2O3基脱硫剂原料。更多还原

【Abstract】 A two-step chromium recovery process was developed to recover Cr from a cold roll wastewater sludge in the steel mill, which contains more than 10%wt of Cr, more than 20%wt of Fe and more than 1.5%wt of Zn. The dry sludge was first roasted under high temperature to oxidize Cr(Ⅲ) to Cr(Ⅵ) with help of sodium carbonate addition and then dissolve in water or diluted NaOH solution to extract Cr(Ⅵ). Influence of the oxidation conditions such as sodium carbonate dosage, roasting temperature & time, and the extraction conditions (i.e. extraction agent, the L/S ratio and extraction time) on extraction effect was studied. The experimental results showed that more than 60%wt of Cr was recovered when roasted under 700 ℃ for more than 4 h with sodium carbonate addition reaching or higher than 0.6 g/g dry sludge. Using water as extraction agent at L/S=10 is good enough for Cr(Ⅵ) extraction. The Cr-removed sludge has a high Fe2O3 content (around 50%wt) and can be a good material for removing H2S from methane produced from different anaerobic processes.更多还原