酸洗污泥含碳球团渣铁浴处理过程中硫的分布

 不锈钢硫酸酸洗过程产生大量的酸洗污泥,其成分中含有高含量的CaSO₄以及铁、铬等有价金属。活性炭经过多次吸附会丧失活性,但仍保持还原性能。由酸泥、活性炭混匀并焙烧制成含碳球团,在高炉过程渣铁混出时将该球团掷入渣铁熔池进行还原处理,酸泥中的Fe、Cr被还原后进入铁水,其他物质进入高炉渣,实现酸洗污泥的去毒、消纳和资源化利用的目标。鉴于硫酸酸洗后的污泥中含有大量硫元素,重点探讨以上工艺技术中球团焙烧温度、配碳量及球团在熔炼过程的添加量等因素对硫在各相中分配行为的影响趋势,主要采取热力学理论计算、实验室试验等研究手段。结果表明,球团C/S物质的量比为2、球团焙烧温度为400 ℃时,向渣铁浴熔池中加入1%占比的球团可控制渣铁浴终点铁水硫质量分数w([S_f])为0.010%左右,此时熔渣固硫率可达到50%;球团C/S物质的量比为0.5、球团焙烧温度为400 ℃或800 ℃时,向渣铁浴熔池中加入3%占比的球团,也可降低渣铁浴终点铁水硫质量分数,w([S_f])为0.01%左右,且酸泥中Fe/Cr回收率达88.27%,但熔渣固硫率较低。本研究说明,利用渣铁浴工艺处理酸洗污泥,通过合理调控试验参数,可有效控制终点铁水硫含量至较低水平,达到深脱硫效果,同时Fe/Cr具有较高的回收效率,渣铁浴前后炉渣成分变化极小,不会影响高炉渣安全性及后续利用,具有较高的环境和经济效益。

Sulfur distribution in slag-iron bath process of treating carbon-containing pellets of pickling sludge

The sulfuric acid pickling process of stainless steel produces a large amount of pickling sludge, which contains high content of CaSO₄, and valuable metals such as Fe,Cr. Activated carbon will lose its activity after several adsorption, but it still maintains reducing performance. The pellet containing carbon is made by mixing acid sludge and activated carbon and roasting. When the slag and iron are mixed out of the blast furnace, the pellet is thrown into the slag-iron bath for reduction. The Fe, Cr in the acid sludge are reduced and enter the molten iron, and other substances enter the blast furnace slag to achieve the goal of detoxification, absorption and resource utilization of the pickling sludge. In view of the fact that the pickling sludge contains a large amount of S, the paper focuses on discussing the effect of the roasting temperature of pellets, the amount of C, and the amount of pellets added in the smelting process on the distribution behavior of S in each phase, mainly by thermodynamic theoretical calculation, laboratory test and other research methods. The results show that when the pellet C/S is 2 and the roasting temperature is 400 ℃, adding 1% pellets to the slag-iron bath, the w([S_f]) of molten iron at the end of the molten iron bath can be controlled at about 0.01%, and the slag fixation rate can reach 50%. When the pellet C/S is 0.5 and the roasting temperature is 400 ℃ or 800 ℃, adding 3% pellets into the slag-iron bath can also reduce the w([S_f]) to about 0.010%,and the recovery of Fe/Cr in sludge reaches 88.27%, but the sulfur fixation rate of the slag is lower. The study demonstrates that slag-iron bath process of treating pickling sludge can effectively control the w([S_f]) to lower level through reasonable adjustment of the test parameters, and achieve deep desulfurization effects. Meanwhile, Fe/Cr has a high recovery efficiency, before and after the reaction, the slag composition changes is extremely small, which will not affect the safety and subsequent utilization of the blast furnace slag, and has high environmental and economic benefits.