Contact process sulphuric acid with reduced mercury content - pref. below 5 ppm by adding sulphur to hot precessed gas

摘要

Conc. H2SO4 is mfd. by a contact process in which the hot gases arising from calcination of metal sulphides contg. Hg or its cpds. are passed through the stages of cooling and purificn., then drying, conversion and absorption. Elemental S is injected into the current of hot gases just prior to the cooling and purificn. stage, the gases pref. being in the temp. range 150 degrees to 400, (esp. 180 to 400) degrees C and the rate of injection being 5 x 10-6 to 5 x 10-3 (esp. 5 x 10-6 to 5 x 10-4) Kg of sulphur per m3 of gas.