Abstract: To process vanadium-containing residues, the residues are leached in an aqueous slurry with introduction of SO.sub.2, the undissolved solids are removed. To effect a processing which is simple, economical and ecologically satisfactory, vanadium content is precipitated as a tetravalent vanadium compound from the sulfate solution at a pH from 7 to 9 by an addition of alkali metal hydroxide and the precipitate is removed from the alkali metal sulfate solution.

Abstract: The process of removing dust, sulfur compounds and nitrogen oxides from combustion exhaust gases, comprising mixing a combustion exhaust gas with ammonia; feeding Ca(OH).sub.2 and FeSO.sub.4 to a fluidized bed reactor containing mixed solids including fly ash, iron sulfates and calcium compounds, especially Ca(OH).sub.2, CaCO.sub.3, CaO, CaSO.sub.4 and CaSO.sub.3 ; supplying an ammonia-containing exhaust gas mixture to the fluidized bed reactor as a fluidizing gas; operating the fluidized bed reactor at a temperature between 300.degree. and 450.degree. C. to form a reacted exhaust gas; supplying the reacted exhaust gas to a multistage electrostatic precipitator having a first stage and additional stages; recycling solids collected in the first stage to the fluidized bed reactor; and recycling one portion of additional solids collected in the additional stages to the fluidized bed reactor and discharging another portion of the additional solids.

Abstract: Disclosed is a process of removing zinc from a phosphating process sludge wherein the phosphating process sludge is mixed with an additive adapted to form slaglike compounds of iron, calcium and/or barium with the phosphorus component of the phosphating process sludges. The mixture is reacted at temperatures of at least 800.degree. C. under reducing conditions. A previous agglomeration, particularly pelletizing, of the mixture will be of advantage. For a formation of iron compounds it will be particularly desirable to employ reaction temperatures of at least 900.degree. C., preferably of at least 1000.degree. C. and most preferably of at least 1100.degree. C. Metallurgical dusts are particularly suitable additives. For a formation of iron compounds it will be desirable to select a Fe:P molar ratio of at least 1.0 in case of a reaction temperature of .ltoreq.950.degree. C., of at least 1.5 in case of a reaction temperature of 950.degree. to 1050.degree. C., and of at least 2.

Abstract: A catalyst which contains vanadium oxide and alkali compounds and serves to oxidize SO.sub.2 to SO.sub.3 is produced in that prefabricated carrier bodies are impregnated with impregnating solutions which contain vanadium and alkalis, the impregnated carrier bodies are thermally treated at elevated temperature and this is followed by an activation under oxidizing conditions at a temperature from 750.degree. C. to 1000.degree. C. In the production of the impregnating solutions, fine-grained V.sub.2 O.sub.5 is dissolved in an acid aqueous medium with addition of a reducing agent and a reduction to form VO.sup.2+ is effected, acid and reducing agent are used in approximately stoichiometric amounts for the dissolution and reduction of V.sub.2 O.sub.5. The alkalis are used in the form of salts. The solution is adjusted to contain SO.sub.4 in an amount which is sufficient to combine the entire amount of the alkalis in neutral sulfates during the drying and activation.

Abstract: A process is disclosed wherein NO contained in a gas is reduced by means of NH.sub.3 as a reducing agent. A mixture of the NO-containing gas and NH.sub.3 is reacted at 290.degree. to 450.degree. C. in the presence of a catalyst, which comprises a support of SiO.sub.2 and contains 5 to 15% by weight manganese sulfate and iron sulfate. The mole ratio of manganese sulfate and iron sulfate, which is calculated as FeSO.sub.4, is between 1:10 and 10:1. The support has a pore volume of 0.6 to 1.6 ml/g and an average pore diameter of 10 to 100 nm.

Abstract: A process is disclosed for the regeneration of pickling solutions which contain ZrF.sub.4 by addition of a Na compound in which a charge of the pickling solution to be regenerated is analyzed and heated. The amount of Na required for the regeneration is determined in each case and is admixed with intense stirring. Then the mixture is cooled, the precipitated NaZrF compounds are separated and a regenerated pickling solution is recovered.

Abstract: Disclosed is a process of simultaneously removing nitrogen oxides and sulfur dioxide from an oxygen-containing exhaust gas.An exhaust gas containing NO.sub.x and SO.sub.2 is mixed with NH.sub.3 and is then introduced as a fluidizing gas into a fluidized bed, which consists of a catalyst for effecting a reduction of NO with NH.sub.3 to form N.sub.2 and an oxidation of SO.sub.2 with O.sub.2 to form SO.sub.3. The catalyst consists of a carrier and of catalytically active substances consisting of V.sub.2 O.sub.5 and of Fe.sub.2 O.sub.3, FeSO.sub.4 and/or Fe.sub.2 (SO.sub.4).sub.3, and alkali sulfates. The SO.sub.3 formed by oxidation may be recovered as sulfuric acid or may be combined with a desulfurizing agent, which consists of Na.sub.2 CO.sub.3, MgO, MgCO.sub.3, CaO, CaCO.sub.3 and/or Ca(OH.sub.2).

Abstract: Flue gases or other contaminated humid exhaust gases which contain SO.sub.3 are cooled by an indirect heat exchange in a heat exchanger to a temperature below the dew point temperature of sulfuric acid and are cooled further to a predetermined temperature in an SO.sub.3 condenser by means of dilute sulfuric acid, which is sprayed to flow in a countercurrent to the gas, whereby dilute sulfuric acid having a predetermined concentration is condensed. The gas leaving the SO.sub.3 condenser is scrubbed and cooled to a temperature from 40.degree. to 55.degree. C. in a fine scrubber by a treatment with a sprayed aqueous liquor. The exit gas is reheated to a predetermined temperature in a reheater by a treatment with sprayed dilute sulfuric acid from the SO.sub.3 and after the condensation of SO.sub.3 is passed through a filter. Dilute sulfuric acid from the reheater is sprayed into the SO.sub.3 condenser.

Abstract: A catalyst is produced in two stages in that prefabricated carrier bodies are impregnated with solutions which contain vanadium and alkalies. When the impregnated carrier bodies have been dried, the conversion activity of the catalyst is increased further in that the catalyst is activated under oxidizing conditions at a temperature of 700.degree. C. to 1000.degree. C.

Abstract: A catalyst is produced in two stages in that prefabricated carrier bodies are impregnated with solutions which contain vanadium and alkalies. When the impregnated carrier bodies have been dried, the conversion activity of the catalyst is increased further in that the catalyst is activated under oxidizing conditions at a temperature of 700.degree. to 1000.degree. C.

Abstract: A process of removing pollutants from exhaust gases in a circulating fluidized bed, in which solids are circulated through a fluidized bed reactor, separated in a separator and returned via a return line, to the reactor. The exhaust gas is introduced as a fluidizing gas into a fluidized bed which consists of two solid fractions differing in particle size, namely, a coarse-grained fraction having a particle size d.sub.p 50 in the range of 150 to 500 microns and a fine-grained fraction having a particle size d.sub.p 50 below 10 microns.

Abstract: A catalyst for oxidizing SO.sub.2 to SO.sub.3 and containing V.sub.2 O.sub.5 and alkali sulfate in a molar ratio below 1 is produced by impregnating prefabricated support bodies with a solution of the active substances in sulfuric acid and the impregnated support bodies are dried and moved at the same time.

Abstract: An improved process for the recovery of substantially anhydrous zirconium tetrafluoride from an aqueous solution of hydrofluoric acid and zirconium fluoride is disclosed wherein the aqueous solution of hydrofluoric acid and zirconium fluoride is sprayed, preferably continuously, into a fluidized bed furnace having a bed comprising zirconium fluoride granules.

Abstract: A process for regenerating a spent HF-HNO.sub.3 pickle which contains ZrF.sub.4, which comprises heating said spent pickle to above 40.degree. C., adding dissolved NaOH to said so-heated pickle, thereafter cooling said so-treated pickle to a temperature below 20.degree. C. whereby to precipitate Na.sub.2 ZrF.sub.6 and removing said Na.sub.2 ZrF.sub.6 from said so-cooled pickle whereby to regenerate the same.