Therefore, the answer is: properly increase the reaction temperature, while constantly stirring, and increase the leaching time.
(2) According to the technological process, sulfuric acid is added to filter the waste residue, and the filtrate contains CaSO4 and MgSO4. According to the solubility-temperature diagram, the solubility of CaSO4 decreases with the increase of temperature, and the solubility of MgSO4 increases with the increase of temperature. The filtrate is heated to separate out CaSO4, so the filter residue B is CaSO4 after heating in operation I..
So the answer is: caso 4.
(3) The solubility of CaSO _ 4 decreases with the increase of temperature, and the solubility of caso _ 4 decreases under the condition of heating. In operation I, the solid is separated from the solution under the condition of heating, and should be filtered while it is hot; Operation ⅱ is to precipitate crystals from the solution, which should be evaporated, concentrated and cooled for crystallization.
So, the answer is: filter while it is hot; Evaporating, concentrating, cooling and crystallizing.
(4) Operation I is filtration and glass rod is drainage; Operation ⅱ is crystallization, and the glass rod is stirring.
So, the answer is: drainage; Stir.
(MgS04 is hydrolyzed to produce magnesium hydroxide and sulfuric acid, which is an acid that is difficult to volatilize, and the sulfuric acid and magnesium hydroxide finally produce magnesium sulfate. After operation II, magnesium sulfate can be obtained by filtration and washing. 7H20 crystal.
So the answer is: no; Sulfuric acid is an acid that is difficult to volatilize.