(2) In the process of acid leaching, the measures that can be taken to improve the leaching rate are: prolonging the leaching time and accelerating the dissolution rate.
Therefore, the answer is: increase the reaction temperature; Increasing the surface area of solid particles;
(3) Hydrogen peroxide has strong oxidizability and can oxidize reducing substances, and Cr3+ has reducibility, and Cr3+ can be oxidized by hydrogen peroxide into high valence ions, thus being separated from impurity ions. The ionic equation of the reaction is 2cr3+3H2O2+H2O = cr2o72-+8h+;
Therefore, the answer is: 2cr3+3H2O2+H2O = cr2o72-+8h+;
(4) When PH=8 exceeds 8, aluminum hydroxide is amphoteric and will dissolve in strong alkali solution, which will affect the recovery of chromium ions; The ions exchanged by sodium ion exchange resin are calcium ions and magnesium ions;
So the answer is: When the pH exceeds 8, part of Al(OH)3 will dissolve to form AlO2-, which will eventually affect the recovery and reuse of Cr(III); Ca2+、Mg2+；
(5) According to the data given in the above table and the drug crystals provided, the experimental steps of removing Fe3+ and Fe2+ from CuCl2 solution are as follows: introducing enough chlorine to oxidize Fe2+ into Fe3+, adding CuO to adjust the PH value of the solution to 3.2-4.7, and filtering.
So the answer is: introducing enough chlorine to oxidize Fe2+ into Fe3+; Adding CuO to adjust the PH value of the solution to 3.2-4.7.