随着可开发利用的硫化镍矿资源日渐枯竭，综合开发红土镍矿并提取各组分成为人们关注的焦点。火法冶金处理红土镍矿存在能耗高、渣量大的缺点，而湿法冶金硫酸加压浸出工艺则存在操作条件苛刻的问题。本研究团队提出采用盐酸处理红土镍矿的酸浸-水解耦合新工艺。该新工艺以盐酸为浸出剂，在较温和的浸出条件下实现褐铁型与蛇纹石型两种红土镍矿中Ni与Co的选择性同时高效浸出，并实现盐酸梯级利用，为红土镍矿中Ni、Co、Mn、Fe、Mg等资源的高效综合利用提供了一条新的途径。本论文的主要研究成果如下：1）蛇纹石型红土镍矿中含Ni（1.37 wt.%）较高，主要由蛇纹石、针铁矿和石英构成，Ni主要以Ni(OH)2形式赋存于蛇纹石与针铁矿中。褐铁矿型红土镍矿主要由针铁矿和赤铁矿构成，用常压盐酸浸取时浸出液中Fe(III)和HCl浓度较高，Ni浓度为1.98 g/L，该浸出液中的Fe(III)主要存在形式为FeCl4-与Fe(H2O)63+。2）氯盐的水解热力学研究表明，氯化铁在较高温度下容易发生水解反应生成赤铁矿或针铁矿；NiCl2、CoCl2、MnCl2等在0 ~ 200 °C内能稳定存在于液相。盐酸与FeCl3浸出体系的热力学研究表明，盐酸与FeCl3可以在0 ~ 200 °C内浸出蛇纹石及各有价金属的氢氧化物。对不同体系的E-pH图进行分析研究表明，可以通过控制pH值来实现Fe(III)与Ni(II)、Co(II)、Mn(II)的浸出与分离。3）确定了氯化铁溶液浸出蛇纹石型红土镍矿工艺的浸出条件。在优化浸出条件下，Ni、Co的浸出率分别为82.8%、88.1%；Fe的沉淀率为87.4%。氯化铁溶液浸出蛇纹石-针铁矿的机理研究表明，当氯化铁浸出含有针铁矿的蛇纹石时，氯化铁首先以针铁矿为晶种水解，生成针铁矿与盐酸，盐酸再与蛇纹石及针铁矿晶种发生反应，最后生成的针铁矿通过脱水或溶解-再沉淀生成赤铁矿，溶液中的Fe(III)亦可以赤铁矿为晶种水解并生成赤铁矿。氯化铁溶液浸出红土镍矿的机理与上述机理相同。4）确定了盐酸选择性浸出红土镍矿的条件。在优化条件下Ni、Co、Fe的浸出率分别为89.4%、97.3%、8.7%。该浸出过程机理分析表明，盐酸首先浸出红土镍矿中的蛇纹石与赤铁矿，生成的FeCl4-与Fe(H2O)63+以未浸出的针铁矿为晶种发生水解反应，并由生成的针铁矿通过脱水或溶解-再沉淀生成赤铁矿，FeCl4-与Fe(H2O)63+以所生成的赤铁矿为晶种发生水解反应而生成盐酸进行红土镍矿浸出。5）探讨了HCl与蛇纹石及针铁矿的反应机理，反应路径为：HCl吸附于蛇纹石与针铁矿晶体并进行浸出反应，所生成的H2O从蛇纹石与针铁矿晶体表面脱附。水分子于蛇纹石晶体表面脱附为控制步骤；HCl吸附于针铁矿晶体过程为控制步骤。6）确定了酸浸-水解耦合反应的工艺条件。在优化浸出条件下，Ni、Co的浸出率分别为75.0%、82.5%，Fe的沉淀率为67.9%。酸浸-水解耦合反应的机理为：褐铁型红土镍矿盐酸常压浸出液中盐酸吸附于蛇纹石与针铁矿表面并进行浸出反应，所生成的水分子从蛇纹石与针铁矿表面脱附，蛇纹石与针铁矿被浸出而分解，且Fe(III)与Cl-及H2O络合形成FeCl4-与Fe(H2O)63+；FeCl4-与Fe(H2O)63+以红土镍矿中未反应的针铁矿为晶种水解生成针铁矿及盐酸，所生成的针铁矿通过脱水或溶解-再沉淀而生成赤铁矿，所生成的盐酸又与红土镍矿继续反应。从而实现褐铁型和蛇纹石型两种类型红土镍矿的同时高效浸出。7）确定了碳分除铝的工艺条件，在优化工艺条件下，铝的去除率可达95.1%，铬酸钾对铝的沉淀率影响并不明显；各反应条件对三水铝石的形貌有较大影响。

Hydrochloride acid leaching-hydrolysis process was proposed by our research group to treat laterite ore. The advantages of this process are: limonitic laterite and saprolitic laterite can be treated in one process, hydrochloride acid can be fully utilized, Ni and Co are selectively leached in a high efficiency at mild leaching conditions. The main points are listed as follows:1) Saprolitic laterite ore contains 1.37 wt.% Ni, and 18.80 wt.% Fe. The main mineral phases of this ore are saprolite, goethite, and quartz. Ni is deposited in saprolite and goethite as Ni(OH)2. The concentrations of Fe(III) and HCl are high and the concentration of Ni is 1.98 g/L in the limonitic laterite hydrochloride acid leaching solution. Fe(III) exits in the solution as FeCl4- and Fe(H2O)63+.2) Thermodynamics research for hydrolysis of chlorides indicates that FeCl3 is hydrolyzed at high temperature. NiCl2, CoCl2, and MnCl2 are stable under 200 °C. Thermodynamics research indicates that saprolite and metal hydroxides can be leached by HCl and FeCl3. E-pH diagrams indicate that the pH value of Fe hydrolysis is lower than that of Ni, Co, and Mn; therefore, Ni, Co, and Mn can be selectively leached from laterite ores by controling the pH value.3) Leaching of saprolitic laterite ore by FeCl3 solution was studied. Under the optimal leaching conditions, the leaching of Ni and Co were 82.8% and 88.1%, respectively; the precipitation of Fe was 87.4%. The mechanism of the leaching of saprolite and goethite by FeCl3 solution indicates that FeCl4- and Fe(H2O)63+ being hydrolyzed to α-FeOOH (GG) and H+, with the H+ produced then reacting with Mg3Si2O5(OH)4 and α-FeOOH (OG) to produce Mg2+, mSiO2·nH2O, FeCl4-, and Fe(H2O)63+. The FeCl4- and Fe(H2O)63+ generated are then hydrolyzed to α-FeOOH (GG) or α-Fe2O3, with α-FeOOH (GG) finally transforming to α-Fe2O3.4) Leaching of saprolitic laterite ore by HCl was studied. Under the optimal leaching conditions, the leaching of Ni, Co, and Fe were 89.4%, 97.3%, and 8.7%. The mechanism of selective leaching of laterite ore by hydrochloride acid was studied. Laterite is leached by HCl, FeCl4- and Fe(H2O)63+ generated are then hydrolyzed seeded by α-FeOOH (OG). The α-FeOOH (GG) generated during hydrolysis process then losts H2O and generates α-Fe2O3. The HCl generated during hydrolysis process leaches laterite ore.5) The mechanism of the reaction between HCl and saprolite/goethite was studied by DFT. HCl was absorbed on the crystal surface of saprolite and goethite, HCl reacted with saprolite and goethite, then, the generated H2O was desorbed from the crystal surface of saprolite and goethite.6) The conditions of hydrochloride acid leaching-hydrolysis process were studied. Under the optimal conditions, the leaching of Ni and Co were 75.0% and 82.5%, respectively; and the precipitation of Fe was 67.9%. The mechanism of this process was coordinated with the conclusion obtained in chapter 4.7) The conditions of carbonization were studied. Under the optimal conditions, the precipitation of Al was 95.1%. Carbonization conditions affected the morphology of the particles.