What Is the Contact Process for Sulfuric Acid?

The raw materials for producing sulfuric acid by contact method are sulfur, pyrite, gypsum, and non-ferrous metal smelting plants.

Contact method for producing sulfuric acid

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The raw materials for producing sulfuric acid by contact method are sulfur, pyrite, gypsum, and non-ferrous metal smelting plants.

Sulfuric acid production by contact method can be divided into three stages: gas generation, contact oxidation, and absorption of sulfur trioxide.

Chinese name

Contact method for producing sulfuric acid

Foreign name

contact process

Raw materials

Sulfur, pyrite, gypsum

Main

Pyrite

three phases

Gas production, contact oxidation, sulfur trioxide absorption

I. Sulfuric acid production by contact method

Key induction

1.The equipment used for gas production is a boiling furnace. The sulfur or the crushed pyrite and air should enter the combustion furnace. The reaction equation is

S (s) + O2 (g) == Ignite == SO2 (g) H = -297kJ / mol

FeS2 (s) +11/4 O2 (g) == High temperature == 1/2 Fe2O3 (s) + 2SO2 (g); H = -853kJ / mol

4FeS2 (s) + 11O2 (g) == High temperature == 2 Fe2O3 (s) + 8SO2 (g); H = -3412kJ / mol

The gas coming out of the combustion furnace is called furnace gas. The purpose of removing impurities and ore dust is to prevent catalyst poisoning, and the reason for drying is to prevent the water vapor and sulfur dioxide from forming acid to corrode the equipment and the adverse effect on catalytic oxidation in the contact chamber.

2 Purified, dry furnace gas enters the contact chamber and contacts the catalyst to react. The reaction equation is SO2 (g) + 1 / 2O2 (g) == catalyst == SO3 (g); H = -98.3kJ / mol (reversible reaction (The reaction conditions are 400 ° C to 500 ° C, with vanadium pentoxide as the catalyst.)

3 Absorb sulfur trioxide. It is carried out in an absorption tower with ceramic rings stacked in it. In order to prevent the formation of acid mist, 98.3% sulfuric acid is generally used to absorb sulfur trioxide to form sulfuric acid, which is then diluted to the desired concentration of sulfuric acid.

Environmental protection and comprehensive utilization of raw materials

1.Three wastes refer to waste gas, waste water, waste residue.

The treatment of the three wastes in the sulfuric acid plant mainly includes:

(1) tail gas can be absorbed by ammonia

(2) sewage can be treated with lime milk

(3) Waste residue can be used as raw material for making cement or used for making bricks

Three. Full use of energy

A large amount of energy is consumed in the production of sulfuric acid by the contact method, and the energy mainly comes from a large amount of waste heat generated in the production. In addition, the use of energy includes: setting up a waste heat boiler beside the boiling furnace, and setting a heat exchange device in the contact chamber, which can fully Use energy.