Abstract: Process for the production of anhydrous calcium fluosilicate from anhydrous calcium chloride and impure fluosilicic acid solution, a by-product of the acid treatment of phosphorus ores containing fluorine, characterized in that a calcium fluosilicate dihydrate is precipitated at low temperature and quantitatively by suitable adjustment of the fluosilicic acid concentration and the molar ratio CaCl.sub.2 /H.sub.2 SiF.sub.6 and that after filtration, washing and drying of the precipitate, an anhydrous calcium fluosilicate which can be easily decomposed by heat treatment is obtained to restore calcium fluoride and silicon tetrafluoride suitable for the manufacture of pure hydrofluoric acid and fluosilicic acid.For gravimetric concentrations of H.sub.2 SiF.sub.6 >25% and molar concentration ratios CaCl.sub.2 /H.sub.2 SiF.sub.6 between 2 and 5, the yields of the anhydrous calcium fluosilicate obtained are greater than 94%.

Abstract: A process is described for producing crystalline copper aluminum borate by forming an aqueous composition comprising a volatile organic liquid having at least partial miscibility with water, a source of copper(II) ions, a source of alumina, and a source of boria at a pH in range from about 4 to about 12 to form a homogeneous gel, drying the gel to form a superficially dry solid, and calcining the dry solid at a sufficiently high temperature to form crystalline copper aluminum borate. Also described is a method for producing a copper aluminum borate precursor which when dried and/or calcined to a sufficiently high temperature forms crystalline copper aluminum borate.

Abstract: Catalysts susceptible to deactivation by free oxygen or to reactions involving free oxygen are protected by scavenging the oxygen in the presence of an oxidation catalyst, so as to remove commingled oxygen from the reactants to be converted in the presence of the catalyst suscepticle to oxygen attack.

Abstract: Disclosed is a process for producing .beta.-form Si.sub.3 N.sub.4 comprising firing amorphous or .alpha.-form Si.sub.3 N.sub.4 of high chemical purity in a non-oxidizing atmosphere under an elevated pressure at a temperature of at least about 1600.degree. C., as well as a process for producing an article comprising such .beta.-form Si.sub.3 N.sub.4.

Abstract: A starting hydrogen sulfide-containing gas is purified by way of a two-stage oxidation to elemental sulfur with oxygen which is supplied in an amount of 100-110% of the stoichiometric quantity necessary for oxidizing hydrogen sulfide to elemental sulfur. Oxidation at the first stage is carried out in a fluidized bed of a granular catalyst containing 10-20% by mass of magnesium chromite on aluminium oxide. At the second oxidation stage, the unreacted hydrogen sulfide and oxygen from the first stage are reacted at 140.degree.-155.degree. C. in the presence of a catalyst to form elemental sulfur.The invention may be used in decontamination of natural gases high in hydrogen sulfide, gas releases of oil refinery and coke chemical plants.

Abstract: A process for preparing silica comprising:(a) acidifying a basic aqueous solution containing silicate ions and molybdate ions to produce silicomolybodic acid;(b) adding to the acidified solution an organic base to precipitate a silicomolybdate; and,(c) heating the resulting precipitate to drive off volatile components and leave a purified form of silica is disclosed. The process is particularly useful for producing purified silica from dilute aqueous media.

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.

Abstract: Silicon having a low carbon content is produced by removing carbon from molten silicon by heating the molten silicon to temperatures of 1420.degree. to 1900.degree. C. and establishing a temperature gradient of 30.degree. to 400+ K. in the melt.

Abstract: Precipitation silicas, in the form of aggregates as shown in FIG. 1, having a mean projected area of the aggregates which is higher than about 8,000 nm.sup.2 and preferably is higher than about 15,000 nm.sup.2. The present invention also concerns a process for the production of precipitation silica by maintaining a constant-volume reaction medium to provide suitable colloids of silica, reacting the colloids with an electrolyte and consolidating the resulting product by the addition of a solution of silicate and an acidifying agent to obtain a precipitation silica.

Abstract: A process for producing silicon carbide whiskers by heating a react solid silicon-containing starting material and carbon-containing starting material in a reaction vessel, wherein a molding material, which is prepared by previously molding the silicon-cotaining starting material into a predetermined shape, and a powdery carbon starting material are heated to a predetermined reaction temperature under a hydrogen gas atmosphere. Silicon carbide whiskers which are linear with no bendings, long fiber length, high aspect ratio and low silicon dioxide impurity can be obtained at a high yield of greater than 90% based on silicon vaporized from the silicon-containing starting material.

Abstract: Sulfur species are removed from a Claus plant tail gas stream by contacting with ZnO producing ZnS which is regenerated to ZnO by dilute O.sub.2. Following regeneration, fresh regenerated ZnO in one ZnO absorber is purged with an effective reducting gas stream producing SO.sub.2 emissions while another ZnO absorber is downstream operating under effective absorption conditions for removing thus produced SO.sub.2 from the first ZnO absorber effluent.

Abstract: A process for removal of H.sub.2 S from gas streams is described, the process being characterized by use of a novel iron chelate treating solution containing a specified ferric to ferrous chelate ratio, aqueous ammonia, and thiosulfate ion.

Abstract: Undesirable conversion of a silicon source, such as silane, in the freeboard above a fluidized bed of silicon particles in a fluidized bed reactor, can be reduced by cooling the gas within the freeboard. Preferably, the reduction in temperature is achieved by introducing into the freeboard, a stream of relatively cool quench gas such as hydrogen, which also reduces the concentration of silane in the freeboard. As a result of these two factors, the invention improves the service factor of the fluidized bed apparatus, and reduces the amount of silane conversion to undesired by-products.

Abstract: A process is presented for the reduction of nitrogen oxides in the effluent from the combustion of a carbonaceous fuel. The process comprises introducing a treatment agent comprising a compound selected from the group consisting of five or six-membered heterocyclic hydrocarbons having at least on cyclic nitrogen into an effluent under conditions effective to reduce the concentration of nitrogen oxides in the effluent.

Abstract: A novel, reformed, inorganic polysilazane which is liquid or solid at room temperature and soluble in o-xylene at room temperature and which has (a) a number-average molecular weight of 200-500,000, (b) contents of Si, N and H of 50-70% by weight, 20-34% by weight and 5-9% by weight, respectively; and (c) --SiH.sub.2 -- and --SiH.sub.3 groups, the molar ratio of the --SiH.sub.2 -- groups to the --SiH.sub.3 groups being 2.0:1 to 8.4:1. The reformed polysilazane is obtained by reaction of a solution of a polysilazane in an organic base-containing solvent to polycondense the polysilazane.

Abstract: Chloropolysilanes can be produced in high yield without forming solid waste materials by contacting silicon materials with chlorine at a temperature of 140.degree..about.300.degree. C. in the presence of copper compound or a mixture thereof.

Abstract: The present invention provides a coating for electrodes for use in electrochemical cells having an electrochemically active species and an electrolyte. The coating contains active species material and is selectively permeable allowing for the diffusion of the active species through the coating during operation of the cell while providing a substantially impervious barrier to the electrolyte. The coating optionally further includes a polymer layer over the active species containing coating or layer for maintaining the mechanical integrity of the active species layer.Electrodes utilizing the coatings described herein may be used in primary and secondary cells over a wide range of operating temperatures to deliver better electrochemical performance even at room temperature.Methods of making the coating and an apparatus for performing these methods on a continuous basis are disclosed.A novel composition of matter is disclosed comprising lithium, silicon, and fluorine prepared by exposing lithium metal to SiF.sub.

Abstract: Silicon nitride powder is prepared in a gas-phase reaction by reacting silicon tetrachloride with ammonia at above 500.degree. C. in a fluidized bed of silicon nitride particles. An amorphous silicon nitride having a BET specific surface area of greater than 50 m.sup.2 /g is used at the beginning of the reaction. The resulting silicon nitride is then separated from the ammonium chloride simultaneously formed.

Abstract: A process for removal of H.sub.2 S from gas streams is described, the process being characterized by use of a novel iron chelate treating solution containing a specified ferric to ferrous chelate ratio and aqueous ammonia.

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.