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以褐铁型红土镍矿为原料,研究了其硫酸熟化过程及其矿物物相转变机理。考察了熟化过程中温度、时间、硫酸量、加水量对熟化过程的影响,结果表明:Ni、Co浸出率随熟化温度的升高、硫酸用量的增加、熟化时间的延长而提高,一定的加水量有利于Ni、Co的浸出。熟化最佳工艺条件为:温度450℃、硫酸量500 kg/t-矿、时间60min、加水量20%,在该条件下,Ni、Co和Fe的浸出率分别为78.1%、91.1%和9.6%。采用TG-DSC、XRD、SEM/EDS对硫酸熟化过程矿物物相转变机理进行了研究,结果表明:200℃下熟化,矿相未被破坏,以针铁矿(Fe OOH)为主;250℃时,部分Fe OOH转变为赤铁矿(Fe2O3)和不溶性的碱式硫酸铁(Fe(OH)SO4);300~350℃时,矿物结构被有效破坏,绝大部分Fe OOH转变为Fe2O3;升温到400℃,Fe(OH)SO4分解为Fe2O3;450℃时,完全可见Fe2O3且其结晶度最好;500℃时,Fe(OH)SO4转变为硫酸铁(Fe2(SO4)3),但仍以Fe2O3为主。大部分Ni、Co矿物转化为可溶性硫酸盐,少量转变为不溶性的铁酸镍(Ni Fe2O4)、铁酸钴(Co Fe2O4),造成Ni、Co的损失。
With the limonitic nickel laterite as raw material, the maturation process of sulfuric acid and the mechanism of its phase transformation were studied. The effects of temperature, time, amount of sulfuric acid and water on the maturing process were investigated. The results showed that the leaching rate of Ni and Co increased with the increase of the curing temperature, the amount of sulfuric acid and the aging time, Water is conducive to Ni, Co leaching. Under these conditions, the leaching rates of Ni, Co and Fe were 78.1%, 91.1% and 9.6%, respectively. The optimum conditions were as follows: temperature 450 ℃, sulfuric acid 500 kg / t- %. The mechanism of phase transformation of minerals during sulfuric acid maturation was investigated by TG-DSC, XRD and SEM / EDS. The results showed that the mineralization was not damaged at 200 ℃, with Fe OOH as the main component and 250 ℃ , Part of FeOOH was transformed into hematite (Fe2O3) and insoluble alkali ferric sulfate (Fe (OH) SO4). At 300-350 ℃, the structure of minerals was effectively destroyed and most of FeOOH was changed to Fe2O3. At 400 ℃, Fe (OH) SO4 was decomposed into Fe2O3. At 450 ℃, Fe2O3 was completely visible and its crystallinity was the best. At 500 ℃, Fe (OH) SO4 was changed to Fe2 (SO4) 3, Fe2O3-based. Most of the Ni and Co minerals are converted to soluble sulfates and small amounts of insoluble nickel ferrite (NiFe2O4) and cobalt ferrite (CoFe2O4), resulting in the loss of Ni and Co.