Abstract: Gas feed streams containing sulfur dioxide such as flue gas streams are first contacted with an aqueous solution of inorganic sulfites and bisulfites having a pH range from about 2 to about 6.5 to remove a minor amount of sulfur dioxide. The same gas stream is then contact with a second aqueous solution of sulfites and bisulfites having a pH range from about 7.0 to about 12.5. Alkali metal hydroxide or ammonium hydroxide solution is added to the liquid inlet of the second contactor and the solution of the second contactor is pumped to the liquid inlet of the first contactor.

Abstract: Adding sodium sulfite in the slurry of the iron oxide slurry process for scavenging hydrogen sulfide described in U.S. Pat. No. 4,246,244, eliminates excessive foaming on start-up, stabilizes the suspension of the oxide particles in the slurry, lessens clogging of reacted particles, which otherwise interferes with cleaning out the reactor vessel, and so materially buffers the slurry as to minimize corrosion of the reactor vessel and piping. Further, adding small amounts of oxygen to the gas stream, which would be expected to cause corrosion, does not do so; instead it prolongs the usefulness of the reactant oxide particles and affords increased acid-stability to the reaction products.

Abstract: A method for the separation of anhydrous HCl and HBr from mixtures of the two acids comprising treating the mixture with a hindered pyridine to form a mixture of hindered pyridine salts of the acids, and heating the mixture of salts to a temperature at which thermal cleavage of at least the hydrochloride salt is induced. The hindered pyridines are defined as aromatic compounds having one or more nitrogen atoms in an aromatic ring, or a polymer with pendant aromatic moieties having one or more nitrogens in an aromatic ring, having an appropriate degree of steric hindrance such that the salt formed by the nitrogen atom of the aromatic compound and a strong protic base will undergo dissociation to the aromatic compound and the protic acid at a temperature below the decomposition temperature of the aromatic compound. The formation of salts and their cleavage can be done as either a one-step or two-step process.

Abstract: A process is disclosed for producing a solid material which, in some cases, may have a resultant purity of 99.999% or better which comprises contacting the solid material at a temperature approaching the melting point of the solid material with a purifying agent which is substantially nonreactive with the solid material to cause the impurities in the solid material to enter the material. After cooling, the purified solid material may be separated from the purifying agent and the impurities therein by leaching.

Abstract: In the production of an article of extremely pure synthetic silicon dioxide, wherein silicon tetrachloride is mixed with water to effect hydrolysis, the resulting hydrolysis product is dried, and the resulting dried particulate product is further processed into the desired article, the improvement which comprises employing a ratio of silicon tetrachloride to water so that the hydrolysis product is in the form of a gel, distilling by-product hydrochloric acid out of the gel, preliminarily drying the gel at 100.degree. to 1000.degree. C. to produce an initial product, milling the initial product into a fine granulate at room temperature, separating from the milled granulate a fraction with a particle size of about 40 to 1000 .mu.m, and drying the screened-out granulate fraction while slowly heating to no more than 1400.degree. C. to form the resulting dried particulate product that is further processed into the desired article. As a result, high quality bubble free articles are produced.

Abstract: What is disclosed is a method for treating a reaction residue from the preparation of organochlorosilanes or chlorosilanes from the reaction of metallic silicon with a chlorinated hydrocarbon or hydrogen chloride, said method comprising (A) combining the reaction residue with water, and (B) granulating the mixture of water and silicon from (A).

Abstract: A method and apparatus for removing carbon dioxide from a body of air by using a regenerative solid amine material arranged in beds 14(A-D) is disclosed. Air is directed through a first bed to adsorb the carbon dioxide theefrom. Steam is impelled by a compressor (24) into the first bed to desorb that bed, the steam forming a condensate on that bed. The compressor then creates a vacuum in the first bed which vaporizes the condensate therein, dewatering the first bed so that it may be reused to adsorb carbon dioxide. The compressor impels the vaporized condensate into a second bed to desorb the adsorbed carbon dioxide in the second bed.

Abstract: Silicon of high purity is made by decomposing silane in a fluidized bed reactor. To obtain good process economics, two modes of operation are used. In a first mode, the reactor is operated under high productivity conditions which also result in co-production of silicon dust or fines. The dust on the particles can cause problems in handling. For example, in bagging the particles, or removing the particles from a bag, the dust can become airborne from the larger particle surfaces and form an objectionable cloud of silicon dust. The invention provides a method for uniting dust to the larger silicon particles. In a second process mode, a thin (0.1-5.0 micron) layer of high purity silicon is deposited on the dust laden particles. This second mode is most preferably carried out by (a) treating the dust-laden particles with a deposition gas comprising 1 to 5 mole % silicon admixed with an inert carrier gas such as hydrogen, (b) in a fluidized bed reactor, and (c) at a process temperature of 620.degree.650.degree. C.

Abstract: The disclosed process separates impurities, including admixed minerals other than quartz and quartz particles having relatively high levels of lattice impurities, from a quartz containing particulate material to recover a high purity quartz product. The process involves treatment with a solvent to reduce the size of the impurities relative to the quartz product and the thus treated material is then classified by size to recover the purified product. If impurities less soluble than the quartz product are also present, a second solvent treatment is conducted to reduce the size of the quartz particles relative to the less soluble impurity and a second classification by size is conducted. In a preferred embodiment, the quartz is subjected to a heat/quench cycle to fracture quartz particles thereby exposing occluded and interstitial impurities to the solvent leach. The intermediate product exiting the final solvent treatment and classification steps is dried, blended and roasted in a vacuum to remove gases.

Abstract: A method of removing hydrogen sulfide from a sour gaseous stream in a contact zone by contacting the sour gaseous stream with a H.sub.2 S selective absorbent in an aqueous alkaline solution containing a polyvalent metal chelate at a pH of about 7 to about 10 wherein the polyvalent metal chelate is in one embodiment of the invention in the reduced or lower valence state in a contact zone and is oxidized to the oxidized or higher valence state in an oxidation zone so as to convert absorbed hydrogen sulfide, hydrosulfide and/or sulfide salts present in the contact zone to sulfur. In a second embodiment, the aqueous alkaline solution and H.sub.2 S selective absorbent in contact with the gaseous stream is a mixture containing a higher valence polyvalent metal chelate together with a lower valence polyvalent metal chelate.

Abstract: The present invention relates to a cyclic continuous process and a composition for the removal of hydrogen sulfide from a variety of sour gas streams. The sour gas stream is contacted with an aqueous solution of a water-soluble organic polymeric chelate containing an oxidizing polyvalent metal, e.g., Fe(III). The sulfur in the hydrogen sulfide is converted to elemental sulfur and the iron in the polymeric chelate is reduced. The process includes removal of the elemental sulfur, and an inexpensive method for removing water and excess low molecular weight materials, e.g., materials having molecular weights below 500, preferably using ultrafiltration or dialysis, regeneration and recycle of the reactive polyvalent metal.

Abstract: A method of producing synthetic silica which is characterized by hydrolyzing a tetraalkoxysilane under a basic condition in the presence of an ammonium salt.

Abstract: A method of producing submicron size boron carbide powder by heating a reactive mixture containing a boric oxide source and a carbon source at a high temperature for a sufficient length of time to form submicron particles of uniform size.

Abstract: Efficient removal of sulfur dioxide from a flue gas stream is achieved in a scrubber using a recirculating aqueous stream containing magnesium hydroxide and magnesium sulfite which together act as SO.sub.2 absorbents. Magnesium sulfite is derived from magnesium hydroxide, which is the product of a reaction between soluble magnesium from the seawater and calcium hydroxide added to the scrubbing system. Magnesium sulfite and bisulfite are oxidized to magnesium sulfate by the introduction of air. Magnesium sulfate is converted back to magnesium hydroxide by reaction with additional calcium hydroxide, with gypsum as a by-product. Gypsum is soluble in large amounts of seawater and may be returned to the ocean without adverse environmental impact.

Abstract: An improved process for preparation of silicon nitride powder having a low carbon content comprises treating silicon nitride powder with an atmosphere containing chlorine gas at temperatures from 600.degree. to 1050.degree. C. and then with an atmosphere containing gaseous oxygen.

Abstract: What is described is an improvement to a process for the preparation of silicon from the reduction of silicon dioxide with a solid carbonaceous reducing agent, the improvement comprising feeding calcium compounds into the reaction zone of a silicon furnace, and controlling and maintaining a desired calcium level in the reaction zone of the silicon furnace. The calcium compounds may be fed to the silicon furnace as a constituent of either the silicon dioxide or solid carbonaceous reducing agent feeds, as a separate feed, or as a combination of two or more of these feeds.Also described is an improvement to a process for the preparation of silicon carbide from the reduction of silicon dioxide with a solid carbonaceous reducing agent.

Abstract: The invention relates to the selective and sequential reduction of halodisilanes by reacting these compounds at room temperature or below with trialkyltin hydrides or dialkyltin dihydrides without the use of free radical intermediates. The alkyltin hydrides selectively and sequentially reduce the Si-Cl, Si-Br or Si-I bonds while leaving intact the Si-Si and Si-F bonds present.

Abstract: Chlorine dioxide is generated from chlorate salt and introduced into a treatment stream. Initially following dissolution of the salt in aqueous medium, the solution is subjected to ion exchange for producing intermediate chloric acid. The acid is next converted to chlorine dioxide by electrolysis. The chlorine dioxide produced can then be extracted for use with a treatment stream. The chlorine dioxide generated can be free from unwanted by-products. The total generation system lends itself to recycling of unused product for obtaining virtually complete conversion of chlorate salt to useful chlorine dioxide.

Abstract: A GaAs growth crystal comprises a Si substrate, an intermediate layer formed on the substrate and a GaAs layer grown on the intermediate layer. The intermediate layer includes constituent GaP/GaAsP and GaAsP/GaAs superlattice layers and additionally AlP and AlGaP thin films.

Abstract: A method of manufacturing silicon carbide whiskers in which silicon and carbon containing feedstock is placed on a series of gas permeable supports and passed through a reaction zone. The feedstock is maintained at 1500.degree. C. to 1700.degree. C. between forty to eighty minutes while the off gases from other reacting feedstock is permitted to pass from one support to another. In this manner uniformity of environment is maintained to produce high quality silicon carbide whiskers having average diameters by mass between 1 and 1.5 microns.