PL104851B1 - METHOD OF REMOVING HYDROGEN FROM GASES - Google Patents

Description

The invention relates to a removal method hydrogen fluoride from the resulting waste gases in the production of artificial fertilizers, feed phosphates, aluminum or enamel.

Thorough removal of fluorine compounds from gases departure is necessary because they provide serious threat to the environment.

Hitherto known methods of removal of fluorine of exhaust gas rely on aibsorption of this ingredient in water or in an aqueous solution alkaline substances or suspensions, e.g. what it can be used as an alkaline substance alkali metal hydroxide, carbonate alkaline meital or calcium hydroxide.

The alkali metal is usually sodium. Absorption takes place in an acidic environment when active the leaching fluid is water, or in the environment the effect of aflkalic gidy leaching agent alkali metal compounds or calcium in the form of an aqueous solution of aqueous iuib suspensions.

Working up of the absorbent solutions for and above the lower methods are difficult because of the small ones the concentration of fluorine compounds in these solutions is due to the low solubility of sodium fluoride and calcium in water.

In the case of waste gas treatment, usually with a low concentration of hydrogen fluoride of less than 6 g / Nm3 and elevated temperature rature at 200 ° C water washing method no it is possible to obtain concentrated solutions hydrofluoric acid due to high pres Carrying of Capable Hydrogen Fluoride in TeiruperAurach 50 to 70 ° C solution.

The method of removing hydrogen fluoride from exhaust gases according to the invention is two hundred truncated absorption with aqueous solutions ammonium fluoride and ammonium hydrofluoride new one.

Total concentration in the first degree of absorption of fluoride and ammonium hydrofluoride is 1 to 40% by weight, molar ratio of hydrogen fluoride to ammonium fluoride in solution eluting cym ranges from 0.2 to 2.5.

However, in the second stage * total absorption the concentration of fluoro and oman hydrofluoride it is 1 to 25% by weight and the molar ratio hydrogen fluoride to ammonium fluoride in solution the leaching temperature ranges from 0.05 to lfi. Solution leaching from the second degree of absorption into it is poured into a solution washing v first stage of absorption, niatomliast solution from the first absorption stage is carried out outside the absorption system. Appropriate the molar ratio of hydrogen fluoride to ammonium fluoride persistence in the washing solutions by introducing ammonia water or gas new amOniiak.

Ammonium fluoride and ammonium hydrofluoride are well soluble in water, which enables 104851104851 absorption with large solutions a bad concentration of fludru. Absorption of hydrogen fluoride by na¬ tapping even with strong acidification tiwoirui, because it forms compounds of the type (NH4F) n "((HiF) m, with the quotient m: n being possible wear 2 or more. It is a phenomenon that because in this way a solution can be obtained postabsorption formations with a high content of fluoride, the amount of ammonium ion introduced to the absorption system can be small.

The obtained absorption solution can be transformed into rabiany nai hydrogenofJjuoirek ammonium in the form crystalline or alloy or sodium fluoride.

Example. We take gas from the dust collector of the furnace to production of feed thermophosphate wpTOwadzo.no within an hour to the first degree of absorption of a two-stage absorption plant modeling in the amount of 500 Nm3 it contained 1.06 kg HF. Introduce as the absorption solution 3L, 9L23 kg of water, 0.3-2 kg of ammonia and 8.774 kg were added a solution from the second absorption stage composed of: 0.0% NH4HF2 and 0.6% NH4tF. As a result of absorption carried out at the temperature of 76 ° C, obtained no 690.30 kg of gas containing 0.105 kg of HF and 7.006 kg of a solution containing 17/7% NH4HF2 and 2.3% HF. The gas was diverted to the second * stage absorption absorption device to which Also 8.642 kg of water and 0.0477 kg were introduced ammonia.

The treatments were carried out at 57 ° C.

The obtained absorbent solution in the amount of 8.774 kg and containing 0.0% NH4HF2 and 0.6% NH4F as directed up to the first degree of absorption. Equipment absorptive gas leaves the gas in an amount of 669.30 kg per 0.021 kg HF. Fluoride Washout Rate hydrogen is * 98%.

Claims (2)

Disclaimers p a <t e m t o w e A method of removing hydrogen fluoride from industrial gases, characterized in that the hydrogen fluoride is absorbed with aqueous solutions of fluorides and ammonium hydrofluorides in two stages, the total concentration of fluoride and ammonium hydrofluoride in the first absorption stage being 1 to 40% by weight, a molar ratio of hydrogen fluoride! to ammonium fluoride in the elution solution is from 0.12 to 2.5, while in the second stage of absorption the total concentration of fluoride and ammonium hydrofluoride is from 1 to> 25% by weight, and the molar ratio of fluoride hydrogen to ammonium fluoride1 in the scrubbing solution ranges from 0.05 to 1.5. 2. The method according to claim A method according to claim 1, characterized in that the washing solution from the second absorption stage is introduced into the washing solution in the first absorption stage, and the solution from the first absorption stage is discharged outside the absorption system, the appropriate molar ratio of hydrogen fluoride to The ammonium fluoride in the scrubbing solutions is maintained by introducing ammonia water or gaseous ammonia. National Printing House, Plant No. 6, residing in 553/79 Price PLN 45