| 摘要 |
Iron and steel acid pickle liquor is regenerated by continuously adding it to a 40-60 per cent solution of sulphuric acid heated by a submerged flame burner so as constantly to evaporate water, and removing precipitated ferrous sulphate (substantially anhydrous) and accumulated regenerated sulphuric acid as they are formed, the rates of addition of spent liquor &c. of evaporation being regulated to maintain the proportion of sulphuric acid in the solution between 40 and 60 per cent. The liquor is preferably evaporated to a point at which it "boils" at 105-140 DEG C., whilst the heat of the <PICT:0623446/III/1> evaporated water and of the products of combustion from the burner may be used to heat the liquor in the pickling bath. The crystals of ferrous sulphate may contain up to 2 molecules of water. In the apparatus shown, spent liquor from the pickling tank B continuously enters the treating tank 1 having a base 11 sloping downwardly via a valve 15; the submerged flame burner A, fed with gas and air from inlets 20, 22, maintains boiling at between 105-140 DEG C. depending on the strength of acid; substantially anhydrous ferrous sulphate collects at C and is drawn off, together with some acid, by the air lift 16, whence it is led to a centrifuge or separator 17 from which it leaves by a shoot 35, the separated acid returning to the pickling tank B or to a storage tank via the pipe 18. Steam and hot gases from the burner pass through the outlets 13, 14 and are used to heat the pickling acid in tank B. A valve 4 is also provided at the base of tank 1 for the removal of accumulated solids.
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