Showing papers on "Aluminium hydroxide published in 1970"

Continuous production of aluminium sulphate

Abstract: A CONTINUOUS PROCESS FOR THE PRODUCTION OF ALUMINIUM SULPHATE, EITHER AS ALUM CRYSTALS OR ALUM SOLUTIONS IN COMMERCIAL CONCENTRATIONS AT AMBIENT TEMPERATURE IN WHICH SULPHURIC ACID AT CONCENTATIONS OF 20100% AND DRY ALUMINA HYDRATE OR BAUXITE OR OTHER FORM ALUMINIUM HYDROXIDE, TOGETHER WITH DILUENT FEED WATER AS MAY BE REQUIRED DEPENDING UPON THE CONCENTRATION OF THE SULPHURIC ACID USED, ARE SEPARATELY FED TO THE INLET OF A MULTI-PASS HEAT-EXHANGE TUBULAR REACTOR, THE MIXTURE OF REACTANTS BEING AT A TEMPERATURE OF 70-120*C. WHEN FED INTO SAID REACTOR AND BEING RAPIDLY BROUGHT TO A TEMPERATURE OF 110-120*C. AFTER ENTERING SAID REACTOR AND BEING MAINTAINED AT A TEMPERATURE OF 110-120*C. IN TRAVERSING SAID REACTOR TO THE OUTLET.

Spectrophotometric determination of yttrium in chromium and chromium-base alloys with arsenazo III

Abstract: A method has been developed for determining yttrium in the range 50 p.p.m. to about 4 per cent. in chromium and chromium-base alloys. The procedure involves the separation of yttrium from chromium(VI) by precipitation of yttrium hydroxide from an ammoniacal chloride solution; aluminium hydroxide is used as a “collector.” The mixed hydroxides are dissolved in dilute nitric acid, and yttrium is subsequently determined spectrophotometrically by a procedure based on the formation of a bluecoloured complex with arsenazo III. Absorbance of the complex is measured at a wavelength of 660 nm.The effects of common alloying constituents and likely impurities have been investigated, and modifications to the method have been introduced to overcome interference by aluminium, iron, titanium, zirconium, hafnium, niobium and tantalum.

Studies on amorphous aluminium hydroxide precipitates (gels)

Abstract: Amorphous (and partly micro-crystalline) aluminium hydroxide precipitates were prepared by controlled hydrolysis of aluminium isopropoxide and aluminium sulphate solutions: the kinetics of their dissolution in well-stirred sodium hydroxide solutions (0.25 to 3 g ion/l) in large excess was studied at 5° to 35°C.

Electrode position of refractory oxides on - aluminium panels

Abstract: Abrasion-resistant, refractory, heat reflecting and insulating coatings resistant to bending are produced by depositing onto the article a layer of colloidal aluminium hydroxide (1) in an electric field in an aqueous solution. By spark discharge (1) is dehydrated and changed to difficulty melting aluminium oxide. (1) originates from the aqs. solution and the metal article coated, and is a molecular compound of both sections of (1). Specif, hydroxycarboxylic acids, alkali or alkaline earth salts of carbonic, boric or phosphoric acid and colloids of the metal to be coated or of silicon are added to the solution.

DETERMINATION OF pH, LIME POTENTIAL, AND ALUMINIUM HYDROXIDE POTENTIAL OF ACID SOILS

Abstract: Summary pH values in CaCl2 suspensions of some acid Scottish soils increase with time, in some cases by 0·4 units in 24 h. This is attributed to proton uptake by a complex ion displaced into solution, and to obtain unambiguous values, pH in CaCl2 suspensions should be measured within an hour of making up the suspensions. In moderately to strongly acid soils, lime potential (LP) and aluminium hydroxide potential (AHP) vary with salt concentration and soil: solution ratio. Unique values for these ion-activity ratios can be obtained by equilibration with a single solution only when the reference cations, i.e. (Ca2++Mg2+) for LP, and Al3+ for AHP, are the dominant exchangeable cations. Otherwise, equilibrium values should be obtained by interpolation from an exchange isotherm at the point where no exchange occurs, i.e. where Δ(Ca+Mg) = o for LP values and ΔA1 = o for AHP values.

A process for the preparation of Mordenite, Catalysts prepared therefrom, and their use

Abstract: 1,181,188. Isomerization. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 27 Sept., 1968 [29 Sept., 1967], No. 46039/68. Heading C5E. [Also in Division C1] Hydrocarbons may be isomerized in the presence of a catalyst comprising at least one metal or compound of Groups VIA, VII A or VIII of the Mendeleef Periodic Table deposited on a synthetic mordenite carrier prepared by heating a co-gel of aluminium hydroxide on silica hydrogel in an aqueous alkaline solution under its autogenous pressure, the co-gel having a silica/alumina molar ratio in the range 9A5:1 to 12A5:1 and sodium hydroxide being present in an amount in excess of that calculated from the formula of mordenite by an amount of 7-30 mg Na 2 O per gram of water, the total quantity of water present being at least 50 moles/mole Al 2 O 3 . In Example VI, n-pentane is isomerized in the presence of hydrogen and a Pt/mordenite catalyst.