循环母液配料烧结处理赤泥提取氧化铝研究

Research on extraction of alumina from red mud by sintering process with circulating spent liquor addition

为解决碱石灰烧结法处理赤泥碳排放量高、生产成本高等问题,提出了以循环母液配料烧结处理赤泥提取氧化铝的创新工艺,系统研究了不同循环母液和纯碱配比对熟料烧结性能、浸出性能和浸出料浆沉降性能的影响,结果表明:以循环母液作为碱源配料烧结熟料主要物相组成为Na_(2)O·Al_(2)O_(3)、2CaO·SiO_(2)、2CaO·Fe_(2)O_(3)和CaO·TiO_(2);提高循环母液的配比可提高Al_(2)O_(3)和Na_(2)O的浸出率;同时以循环母液为碱源配料使Fe_(2)O_(3)转化为2CaO·Fe_(2)O_(3),从而改善了浸出料浆沉降性能。在以循环母液为碱源的条件下,熟料烧结过程二氧化碳排放量大幅度降低,熟料Al_(2)O_(3)和Na_(2)O实际浸出率达到89%和96%以上,浸出料浆沉降速率可达10.55 m/h,泥层压缩率可达76%。

In order to address the problems of high carbon emission and high production cost of lime-soda sintering process for treating red mud,a novel process to extract alumina from red mud by the sintering process with the addition of circulating spent liquor is proposed.Effects of different ratios of circulating spent liquor to sodium carbonate on the sintering properties and leaching properties of clinker as well as the settleability of leaching slurry are studied.The results show that the main phases of the sintered clinker produced by using circulating spent liquor as alkali source are Na_(2)O·Al_(2)O_(3),2CaO·SiO_(2),2CaO·Fe_(2)O_(3) and CaO·TiO_(2).Increasing the ratio of circulating spent liquor can improve the leaching rate of Al_(2)O_(3) and Na_(2)O.At the same time,the circulating spent liquor is used as alkali source to convert Fe_(2)O_(3) into 2CaO·Fe_(2)O_(3),and the settleability of leaching slurry can be improved as a result.Under the condition of using circulating spent liquor as alkali source,the carbon dioxide emissions during the sintering process of clinker are significantly reduced,the actual leaching rates of clinker Al_(2)O_(3) and Na_(2)O are above 89%and 96%,the settling rate of the leaching slurry and the compressibility of the mud layer can reach 10.55 m/h and 76%,respectively.