用废雷尼镍(主要成分为NiO、Al,少量Cr、Fe、C、S及有机物)制备Ni(NO3)2·6H2O的实验流程如下：已知：①在实验条件下，Ni2+、Cr3+在溶液中不能被NaClO或HNO3氧化。②

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用废雷尼镍(主要成分为NiO、Al,少量Cr、Fe、C、S 及有机物)制备Ni(NO₃)₂·6H₂O的实验流程如下：

已知：①在实验条件下，Ni²⁺、Cr³⁺在溶液中不能被NaClO或HNO₃氧化。

②NiSO₄易溶于水，NiCO₃难溶于水;Ni(NO₃)₂在20℃、90℃时溶解度依次为79.2、188g/100g 水。

③己知“酸溶”后的溶液中主要的四种离子开始沉淀与沉淀完全的pH 如下：

	Ni²⁺	Fe²⁺	Fe³⁺	Cr³⁺
开始沉淀pH	6.2	7.6	2.3	4.5
沉淀完全pH	8.5	9.1	3.3	5.6

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