The physicochemical properties and preparation method of ferrous sulfate

[Physical and chemical properties] Ferrous sulfate , the molecular formula is FeSO ₄ ·7H ₂ O, commonly known as green vitriol, the relative molecular mass is 278.

[Preparation]

(1) Iron filings sulfuric acid method

Dilute sulfuric acid and iron react to produce ferrous sulfate and hydrogen, and release heat

Fe+H ₂ SO ₄ →FeSO ₄ +H ₂ ↑

As shown in Figure 2-10, first dissolve the iron filings in sulfuric acid , heat it until it no longer dissolves (to keep the metal iron in excess), filter, acidify the filtrate with sulfuric acid, and pass hydrogen sulfide to saturation after cooling, and leave it for 2 to 3 days , After heating on a water bath, filter, pour the filtrate into a distillation flask, evaporate to 1/2 under the condition of introducing oxygen-free carbon dioxide , then crystallize it in carbon dioxide gas, suck and filter out the crystal the next day, use first Wash with water, then with ethanol, and dry at 30°C as soon as possible to obtain ferrous sulfate

Figure 2-10 Process flow of ferrous sulfate produced by iron filings sulfuric acid method

(2) Titanium dioxide by-product method

China has abundant titanium resources, accounting for about 50% of the world's reserves

The source of ferrous sulfate produced in the process of producing titanium dioxide by the sulfuric acid method: one is the trivalent iron and divalent iron contained in the ilmenite itself; the other is the iron filings added in the process of reducing the trivalent iron

Ferrous sulfate is mainly produced when the solution of ferrous sulfate and titanyl sulfate is frozen

(3) Pyrite reduction method Chinese patent 03103056.

Figure 2-11 Process flow for preparing iron salt solution

Figure 2-12 Process flow of preparing green vitriol by pyrite reduction method

Table 2-1 FeSO ₄ ·7H ₂ O sample quality

It can be seen from the above table that the quality of the FeSO ₄ ·7H ₂ O obtained is better than the excellent quality of GB 10531-89, and is close to the GB664-93 chemical reagent standard