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(2)2Fe(OH) 3 Fe 2 O 3 +3H 2 O

(3) heating and boiling the obtained filtrate E for a certain time (or adding enough NaOH solution into the filtrate), filtering, washing, drying, and finally burning at high temperature.

(4) According to the data in the table, when the pH value of the solution is controlled between 7 and 8, Mg2+ does not change, Al3+ is transformed into AlO 2-, and only Fe(OH) 3 is precipitated.

(5)8 MgO·Al 2 O 3·Fe 2 O 3·4 SiO 2

The key to this problem is to understand the reaction and principle of each step in the flow chart. Adding hydrochloric acid to the mixture of MgO, Fe 2 O 3, Al 2 O 3 and SiO 2 to obtain solid A as SiO 2, adding sodium hydroxide to the filtrate to obtain precipitate D as Fe(OH) 3, filtering liquid C containing Mg2+ and AlO 2-, and introducing CO 2 to generate Al(OH) 3 precipitate. (1) Glass instruments required for filtration operation: funnel, beaker and glass rod. (2)D The chemical equation for preparing red pigment is 2Fe (OH) 3Fe2O3+3H2O. (3) The obtained filtrate E contains Mg 2+, and alkali can be added to generate magnesium hydroxide precipitate, which is then decomposed by heating to obtain refractory magnesium oxide. (4) According to the data in the table, when the pH value of the solution is controlled between 7 and 8, Mg2+ does not change, Al3+ is transformed into AlO 2-, and only Fe(OH) 3 is precipitated.

(5)n (silica) = =0.04 mol.

2Fe(OH) 3 Fe 2 O 3 +3H 2 O

2 1 4g1mol

2.14g nitrogen (iron oxide)

The solution is: n (Fe2O3) = 0.0 1 mol.

M(Fe 2 O 3 )=0.0 1 mol×160g mol-1=1.60g.

2Al(OH) 3 Al 2 O 3 +3H 2 O

1 56g1mol

1.56g nitrogen (alumina)

The solution is: n (Al2O3) = 0.0 1 mol.

M(Al 2 O 3 )=0.0 1 mol×102g mol-1=1.02g.

M (MgO) = 8.22g-2.40g-1.60g-1.02g = 3.20g.

Nitrogen (magnesium oxide) = =0.08 mol

Then n (MgO): n (Fe2O3): n (Al2O3): n (SiO2) = 0.08 mol: 0.01mol: 0.01mol: 0.04 mol = 8:1.

That is to say, the composition of vermiculite ore is 8mgo Al2O3 Fe2O3 4sio2.