Abstract: Substantially fluoride-free phosphoric acid is produced by the acidulation of phosphate rock with sulfuric acid wherein the acidulation reaction is conducted in the presence of added potassium as K.sub.2 O bearing compounds, e.g. KHSO.sub.4, K.sub.2 SO.sub.4, KH.sub.2 PO.sub.4 or KOH, and additional silica, to precipitate fluorides and silica as potassium silicofluoride and then removed on separation of the gypsum formed. Optionally, additional silica may be added to the phosphoric acid solution recovered after precipitation and removal of the gypsum, to precipitate additional fluoride as potassium silicofluoride to further purify the phosphoric acid. In a further embodiment sufficient potassium may be added along with additional silica in the acidulation step to produce potassium dihydrogen phosphate and phosphoric acid as additional products.

Abstract: Butadiene is produced in relatively pure form by an oxidative dehydrogenation process in which a crude butadiene stream comprising butadiene, butylenes, vinyl acetylene and propylene is first extractively distilled with an extractant consisting of a sulfolane/acetone mixture. From a purified stream consisting essentially of butadiene and vinyl acetylene, the vinyl acetylene in a second extractive distillation step is removed using a sulfolane/acetone mixture as the extractant to produce a pure butadiene stream.

Abstract: A wet phosphoric acid process involving operation of two streams, substantially equivalent, one producing phosphoric acid of a particular level of concentration, and gypsum as a by-product, and the other phosphoric acid of a different concentration, producing calcium sulfate hemihydrate as a by-product, with means for interconnecting and coordinately operating the processes so as to produce a single acid product stream of a higher concentration than the sum of the individual streams. The method consists of employing acid from one process as a wash in the second and balancing the flow streams to produce the combined product acid of enhanced final concentration and the plants involved in carrying into effect this method of operation.

Abstract: Diammonium hydrazinium tetraperchlorate is made by reacting an ammonium compound and a hydrazinium compound preferably in a 2:1 molar ratio with perchloric acid using aqueous perchloric acid containing about 60% to 70% by weight of the acid as a reaction medium. The diammonium hydrazinium tetraperchlorate crystallizes from the solution and may be recovered therefrom by filtration, decantation or centrifuging. The tetraperchlorate formed is useful as the oxidizer component of solid rocket propellants, pyrotechnic compositions and gas generators.

Abstract: Water immiscible organic acid phosphates used in conjunction with water immiscible organic sulfonic acids results in an improved process for the purification of phosphoric acid. An increase in the extraction of ionic metallic impurities and a decrease in the extraction of P.sub.2 O.sub.5 values from the aqueous phosphoric acid phase is observed in the improved solvent extraction process.

Abstract: A method for heat recovery in the processes of the removal of nitrogen oxides from exhaust gases containing sulfur oxides and nitrogen oxides by a catalytic or non-catalytic reduction thereof with ammonia. After passing through the reaction zone for the reduction of nitrogen oxides the down flow gases are subjected to the submitted air in a heat exchanger. The process is characterized in that the molar ratio of ammonia to sulfuric anhydride and the concentration of steam in the gases at the inlet of the heat exchanger is controlled in the range of O<NH.sub.3 /SO.sub.3 <2, preferably O<NH.sub.3 /SO.sub.3 <1.5 and more than 12% by volume, preferably more than 15% by volume, respectively, and thereby the process can continuously proceed without the production of ammonium sulfate and the deposition or adhesion thereof onto the surface of the various devices in the apparatus therefor.

Abstract: .alpha.-Alkylbenzyl alcohol and substituted .alpha.-alkylbenzyl alcohols are converted in high yield and purity to styrene and substituted styrenes by contacting the alcohol in vapor phase with silica gel and steam.

Abstract: Impure wet-process phosphoric acid is stabilized against sludge formation by adding to a solution of said acid about 0.1 to 1% by weight of an inorganic oxidizing agent and about 0.1 to 1% by weight of silica, aging the thus treated solution concentrated to a P.sub.2 O.sub.5 content of 35% to 42% by weight for a time sufficient to form a solid phase and a substantially solid-free liquid phase of phosphoric acid improved in stability and separating the liquid and solid phases.

Abstract: A process for recovery of urea from a phenolic solution thereof which comprises adding an organic solvent selected from the group consisting of aliphatic amides, ethers, carbon disulfide and dimethylsulfoxide to the said phenolic solution and collecting the separated crystals of urea from the resultant mixture. The process is characteristic in recovering urea in the solid state without the use of water but a particular organic solvent.

Abstract: A process is provided in which a gas, particularly a sulfur-free natural gas, that contains mercury is contacted with an amount of hydrogen sulfide in excess of the stoichiometric amount of hydrogen sulfide necessary to precipitate sulfides of mercury with further contact with an amine that is an absorption agent for hydrogen sulfide. Hydrogen sulfide precipitates sulfides of mercury from the gas stream while the amine absorbs the excess hydrogen sulfide to produce a gas stream of minimal sulfur content with a reduced mercury content that can be below the range of detection.

Abstract: A process for removing organic material from extracted phosphoric acid comprises contacting extracted phosphoric acid with a chlorate and hydrochloric acid at a temperature higher than 100.degree. C while maintaining the concentration of the extracted phosphoric acid at a value higher than 90 wt% as H.sub.3 PO.sub.4. Hydrochloric acid may also be included with the chlorate.

Abstract: Wet process phosphoric acid is made by grinding phosphate rock as a slurry in water, and digesting the ground rock slurry with sulfuric acid which has been diluted by spent calcium sulfate wash water before being combined with the ground slurry.

Abstract: A method of removing NO.sub.x and SO.sub.2 from an exhaust gas containing NO.sub.x and SO.sub.2 which comprises contacting an exhaust gas containing NO.sub.x and SO.sub.2 with an aqueous solution containing M.sub.2 SO.sub.3, an iron ion and an aminopolycarboxylic acid to absorb NO.sub.x and SO.sub.2 in the aqueous solution and treating the resulting absorbing solution while preventing a contact of the solution with the exhaust gas, thereby to form M.sub.2 S.sub.2 O.sub.6 in the absorbing solution and reducing NO.sub.x to N.sub.2. The M.sub.2 S.sub.2 O.sub.6 formed in the absorbing solution can be easily removed by crystallization separation. With such method, NO.sub.x and SO.sub.2 can be removed from exhaust gases at high rates and the absorbing solution can be easily regenerated and recycled to the absorbing zone.

Abstract: A method of forming a silicon carbide article is disclosed. Selected weight percentages of silicon carbide particles, graphite particles, if desired, and a thermosetting binder are mixed together and molded into an article by molding techniques which operates on the basis that the thermosetting binder forms a continuous medium about all the particles supported therein. The molded article is heated in the absence of oxygen and the thermosetting binder breaks down to form a low density, vitreous carbon phase. The article is heated in an oxygen containing environment to remove excess surface carbon. The article is silicided at an elevated temperature by penetration of the article through its pore structure with a reactable form of silicon.

Abstract: The present invention provides a method of converting NO.sub.3.sup.- ions which are contained in denitration waste liquids to nonpoisonous N.sub.2 gas or to valuable by-products. In the method of the invention, concentrated sulfuric acid is added to the waste liquid which results from denitration of exhaust gases which contains calcium nitrate and calcium chloride to obtain a mixed solution of nitric acid, hydrochloric acid, sulfuric acid and calcium sulfate. The ratio of the chloride ions to nitrate ions in the mixed solution is adjusted within the range of Cl.sup.- /NO.sub.3.sup.- = 2-3; the mixed solution is heated to 110.degree. to 150.degree. C after adjusting the concentration of sulfuric acid in the solution to 10 to 70% by weight to thereby convert the mixed solution to a mixed gas essentially including NOCl, Cl.sub.2 and nitrogen oxides. The mixed gas is then passed through concentrated sulfuric acid having a concentration higher than 80% which is maintained at a temperature of 80.degree. to 150.

Abstract: In a method of treating clay-containing phosphate rock comprising at least mining the phosphate rock, reducing the phosphate rock to a predetermined size range, adding water to the phosphate rock, and storing the admixture containing at least the phosphate rock and water; the improvement characterized by adding to the admixture an amount effective to control problems associated with the swelling of residual clays of a chemical treatment selected from the class consisting of aliphatic hydroxy acids containing 2-6 carbon atoms, inclusive, of which citric acid and tartaric acid are members; the aliphatic hydroxy acid salts, and effective blends of the aliphatic hydroxy acid or the aliphatic hydroxy acid salts with a strong caustic, or base. The chemical treatment prevents a build up of viscosity such that the admixture remains pumpable even with a concentration of solids in excess of 66 percent by weight.

Abstract: A process for removing sulfate ions from extracted phosphoric acid which is substantially free of metallic ion contaminants, which comprises adding less than the stoichiometric equivalent of a barium compound relative to the amount of dissolved sulfate ion to said extracted phosphoric acid to form barium sulfate crystals, adding active carbon to the resulting slurry, separating the solid components from the slurry and recovering purified phosphoric acid.

Abstract: This invention concerns the solubilization of phosphate values in phosphate bearing rock which contains high contents of aluminium and/or iron by attacking the phosphate rock with a nitric acid leach solution for a time suitable to produce a phosphate rich leach solution containing no more than 10 parts Fe and Al in solution calculated as R.sub.2 O.sub.3 per 100 parts of P.sub.2 O.sub.5 in solution.

Abstract: A process for the dehydrogenation of alkylaromatic hydrocarbons, such as ethylbenzene, in which a water stream formed by condensing and separating the effluent of the reaction zone is treated for the removal of alkenylaromatic hydrocarbons by passage through a liquid-liquid extraction zone, and the alkenylaromatic hydrocarbons are then recovered by admixing the extract stream with the effluent as part of the cooling performed before the effluent is passed into a liquid phase separation zone.

Abstract: A process for the recovery of selenium from a urethane solution containing selenium compounds which may be in the form of metallic selenium, inorganic selenium and/or organoselenium compounds which comprises contacting the selenium-containing urethane solution at suitable temperatures with a supported metal or a mixture of metals and/or metal oxide compounds, said metal selectively chosen from Group B metals, i.e., Group IB through VIIIB, metals of the Periodic Table and particularly supported copper and mixtures of copper and other metal oxide compounds of said group.