Showing papers on "Aluminium hydroxide published in 1988"

Preparation of pressureless-sintered SiC-Y2O3-Al2O3

Abstract: Sintering additives were prepared from aluminium hydroxide and yttrium hydroxide. These additives were soluble in water and resulted in a binder. A β-SiC powder was mixed with the additive solution and sintered at 2150° C without pressure. The oxides formed from the additive promoted sintering. The sintered body contained no pores. Aluminium, silicon, and yttrium oxide were precipitated in the sintered body.

Effect of magnesium hydroxide on the absorption of tolfenamic and mefenamic acids.

Abstract: The effect of various antacids on the absorption of tolfenamic and mefenamic acids has been investigated in three separate crossover studies, each consisting of four phases. Single doses of magnesium hydroxide (85 mg, 425 mg and 1700 mg) or of water (150 ml) were given by mouth to 6 healthy volunteers immediately after tolfenamic acid 400 mg (Study 1), and, using an identical study design, after mefenamic acid 500 mg (Study 3). In Study 2 sodium bicarbonate 1 g, aluminium hydroxide 1 g, an antacid preparation containing both aluminium and magnesium hydroxides, or water alone were ingested with tolfenamic acid 400 mg. Plasma concentrations of tolfenamic and mefenamic acids and their cumulative excretion in urine were determined up to 24 h. Magnesium hydroxide greatly accelerated, in a dose-dependent manner the absorption of both tolfenamic and mefenamic acids. The peak times in plasma were shortened by about 1 h by 425 mg and 1700 mg magnesium hydroxide, and the peak plasma concentrations of both fenamates were elevated up to 3-fold. The area under the plasma concentration-time curve between 0 and 1 h of tolfenamic acid was increased up to 7-fold and that of mefenamic acid up to 3-fold. The total bioavailability of tolfenamic and mefenamic acids was only slightly increased. Aluminium hydroxide alone and in combination with magnesium hydroxide significantly retarded the absorption and lowered the peak plasma concentration of tolfenamic acid. Sodium bicarbonate had no significant effect on its absorption. The interaction with magnesium hydroxide leads to higher and earlier peak plasma concentrations of the fenamates.(ABSTRACT TRUNCATED AT 250 WORDS)

Coated inorganic materials

Abstract: An inorganic powdery or granular material which is coated with a coating of an inherently conductive polymeric material, such as a conductive polypyrrole or substituted polypyrrole, a polythiophene or substituted polythiophene, a polyaniline or substituted polyaniline, a polyethylene oxide or an aniline copolymer. The material which is coated is talc, mica, wollastonite, calcium carbonate, aluminium hydroxide, clay or hydroxyapatite.

Aluminium, its use and control, in potable water

Abstract: The paper addresses the presence and use of aluminium in potable water and the need to control final residual levels. As a consequence of the ubiquitous nature of aluminium it is invariably present in many raw waters abstracted for potable use. Therefore even without the necessary use of aluminium flocculants there is a potential for residuals to be present in the water delivered to the consumer. It is generally accepted that the addition of aluminium flocculants is an essential step in the treatment of most raw waters for potable purposes. There are several aluminium flocculants that are used in the treatment of raw water throughout Europe. At working pH values precipitation occurs of highly insoluble chemicals, mainly aluminium hydroxide which is removed during the treatment process. However, some low residual level of soluble aluminium remains in the treated water. The paper considers these different aluminium flocculants ranging from monomeric aluminium sulphate to complex polymeric species a...

Aluminium hydroxide growth on aluminium surfaces exposed to an air/1% NO2 mixture

Abstract: Aluminium samples were exposed to a mixture of 1% NO2 in air at 100%, 52% and <5% relative humidity. Auger electron spectroscopy depth profiling showed that for the 100% and 52% r.h. environments, the thickness of the surface oxide/hydroxide layer increased linearly with exposure time. X-ray photoelectron spectroscopy was used to study the surface composition as a function of exposure time. The XPS data clearly showed that a transformation from AlOOH to Al(OH)3 was occurring with time for high humidity exposures. Thick hydroxide layers which formed after prolonged exposure, were also analysed with scanning electron microscopy, thermogravimetric analysis, and X-ray diffraction.[/p]

Flame-resistant unsaturated polyester resins

Abstract: The compositions contain, as flameproofing system, a phosphorus/nitrogen component, aluminium hydroxide and at least one synergistic component from the series comprising organic nitrogen compounds and polyalcohols or derivatives thereof, where the phosphorus/nitrogen component may be ammonium polyphosphate. … To produce the flame-resistant mouldings, a curable synthetic resin is mixed with a flameproofing system comprising a phosphorus/nitrogen component, aluminium hydroxide and at least one synergistic component from the series comprising organic nitrogen compounds, polyalcohols and derivatives thereof. The mixture is processed by wet pressing at pressures of from 3 to 10 bar either at room temperature (from 20 to 60 DEG C) or at elevated temperature (from 80 to 150 DEG C). Finally, synthetic resin mats can be produced from the mixture at pressures of from 50 to 150 bar and temperatures of from 140 to 160 DEG C.

Serum aluminium measurement by DC plasma emission spectrometry.

Abstract: A serum aluminium assay has been established using a DC plasma emission spectrometer and calibration with serum based standards. The assay is linear between 0.20 and 18.0 mumol/L aluminium. The procedure gives good analytical recovery and precision. The assay was validated by comparison(s) with an electrothermal atomic absorption (ETAAS) procedure which showed good agreement. Serum aluminium concentrations have been compared in normal individuals, in undialysed chronic renal failure patients with or without aluminium hydroxide treatment, and in dialysed patients treated with oral aluminium hydroxide. Non-dialysed patients had higher serum aluminium concentrations if treated with aluminium hydroxide. Haemodialysis patients had the highest serum aluminium concentrations whilst those on peritoneal dialysis had levels similar to those of the non-dialysed chronic renal failure group.

Surface reactions during rapid solidification and handling of Al5Mn2.5Cr powders

Abstract: Rapidly solidified Al powders were analysed in the as-received condition, and after exposure in humid atmospheres, using ESCA and Auger spectroscopy. The composition of the powder is Al5Mn2.5Cr. It was produced by the ultra sonic gas atomization (USGA) technique. The cooling rate was in the range 105–106 K s−1. The surface of the as-atomized powder is partly covered by aluminium oxide particles formed at high temperatures during atomization and by a thin uniform oxide film formed between the oxide particles. The thin film is formed at low temperatures during atomization and during handling of the powder. The average thickness of the oxide is 50 A. The powders were exposed in humid atmosphere at 22°C for 1 day and for 1 week, at relative humidities of 60% and 80%. During the exposure, aluminium hydroxide is formed on the surface of the oxide. The thickness of the hydroxide layer increases with exposure time and the humidity. After exposure for 1 week in relative humidities of 60% and 80% the thicknesses of the hydroxide layers were 10 and 12 A, respectively.

Process for preparing difficultly inflammable polyurethane foams

Abstract: Flame resistant polyurethane foams are prepared by impregnating an open-cell polyurethane foam with a mixture of a carboxyl-containing polychloroprene latex, a zinc salt of a polymetaboric acid and optionally aluminium hydroxide.

Adjuvant for anhydrite-containing mixtures for building materials

Abstract: The adjuvant for cement-free building material mixtures containing anhydrite as a hydraulic binder and sand as a shortening is an aluminium- or silicon-containing fluoride or an aluminium hydroxide/ sulphate complex, to give a cement-free building material mixture obtained with the adjuvant.

Process for producing sandy aluminium hydroxide

Abstract: The present invention solves two problems, i.e., the decomposing rate for producing sand-like aluminium from the seedling separation in combined or sintering method is low, and carbonization decomposition can not produce the sand-like aluminium hydroxide yet. The process adopts a technology consisting of prior seedling separation, seedling carbonization decomposition and after seedling separation, i.e., the powder aluminium hydroxide produced from the prior seedling separation is used as seed crystal of carbonization decomposition, and the product from the latter step is used as seed crystal for the after seedling separation and finally the sand-like aluminium hydroxide from the prior and after seedling separation is sintered into a single grade of sand-like aluminium hydroxide. The decomposition rates of both seedling separations reach 50%. The process is applied to the plant for producing the sand-like aluminium hydroxide by treating ores of the empholite monohydrate type.

Process for preparing boehmite

Abstract: of EP02784691. Process for preparing boehmite. 2.1 To date, boehmite for the use in glass, catalyst and ceramics industry has been prepared by digesting ground aluminium trihydroxide in water at elevated temperatures and pressure in the presence of mineral acid. It is now intended to dispense with the initial step of grinding aluminium trihydroxide and the autoclave treatment. 2.2 The present invention allows a process for converting inexpensive coarse particles of aluminium trihydroxide into finely-particulate boehmite particles, during which process the aluminium hydroxide particles are first heated at a temperature of at least 300 DEG C so as to embed boehmite into a matrix of chi-aluminate. The boehmite product is then separated by dissolving the chi-aluminate, giving boehmite particles of a specific surface area which is greater than that of customary particles of 1 - 2 mu m particle size. 2.3 The field of application is the preparation of boehmite for the glass, catalyst and ceramics industries. 3. Fig. 2 is selected.

A classifier for continuous production of coarse aluminium hydroxide

Abstract: In this invention, a classifier for continuous production of coarse aluminium hydroxide is provided, which consists of shell, driving device, vertical axe with mixing mechanism, feeder overflow pipe and bottom flow pipe. Through the mixing classifier, this machine makes aluminium hydroxide slurry from final seed vessel reach bottom overflow grain grade covtaining 44 u less than 7% of coarse aluminium hydroxide. After separation of the overflow, the fine aluminium hydroxide returns to the decomposition vessel as seed crystal. The structure of this classifier is relatively simple, which possesses higher classification efficiency of two to three folds than that of the foreign single paddle mechanic classifier. It is not adopted for separating various grain grade aluminium hydroxide slurry, but also adopted as ore selection equipment for other fine particulates such as copper. tin and lead etc, before their ore slurries are disposed.

Preparation of aluminas

Abstract: Aluminium hydroxide was prepared by precipitation from aluminium nitrate solution with ammonia solution. Thermal decomposition of the solid hydroxide was studied by means of TG, DTG and DTA.

Preparing aluminium dihydrogen tripolyphosphate dihydrate

Abstract: A process for making aluminium dihydrogen tripolyphosphate dihydrate AlH2P3O10.2H2O comprises: A. adiabatically neutralizing under agitation for from 0.5 to 3.5 hours aluminium oxide or aluminium hydroxide, with a phosphoric acid compound selected from 85% by weight phosphoric acid, ammonium phosphate or phosphorus pentoxide. wherein the molar ratio of phosphorus/aluminium is in the range of from 2 to 3.5 to obtain a translucent liquid having a moisture content of from 15 to 35% by weight; B. calcining the translucent liquid at a temperature in the range of from 250 DEG C to 350 DEG C for 3-20 hours to obtain an anhydrous aluminium dihydrogen tripolyphosphate; C. simultaneously hydrating the tripolyphosphate by adding water thereto at about 150 DEG C and grinding with the water to form polyphosphate dihydrate having a granular size of less than 40 microns. s

A study of the anodic behaviour of aluminium alloys in alkaline electrolytes

Abstract: Recent studies an the discharge performance of aluminium alloys in alkaline media have led to improved alloys with significantly lower corrosion rates and more anodic potentials. Performance, of various alkaline electrolytes have also been examined and considerable progress has been made in this area. A review of the available literature reveals a list of several elements which are suitable for alloying with aluminium as regards reducing corrosion and overpotential. Previous work at the Chemical Energy Research Centre, City University, showed that with an aluminium alloy Q4, which contained additives of bismuth, lead, magnesium, titanium and zinc, improved characteristics were obtained on comparison to the performance of bulk manufactured aluminium. Furthermore, on discharging the alloy in a novel electrolyte developed at City, which consisted of, a 1: 1 mixture of 50% (w%v) sodium hydroxide and 30% (w/v) potassium hydroxide, improvements in performance were observed when compared to the results obtained from discharge in the traditionally used 30-40%. (w/v) potassium hydroxide. Firstly, in full cell discharge ( where the aluminium anode was coupled with an oxygen reduction cathode the operating life of the cell was considerably longer-( up to as much as 50% ). Secondly, and probably-more important, was the fact that the power output was also significantly greater. As for reducing hydrogen evolution, several alloying elements had this effect. However, work done showed that the most effective means of minimising corrosion was to use electrolyte additives. The most suitable electrolyte additive was found to be mercuric oxide. The presence of mercury as an electrolyte additive has a distinct advantage over alloying the metal with aluminium. In the case of the latter, the amalgam formed results in the oxide layer being broken down and the alloy becomes unstable in the atmosphere. Saturation of the electrolyte with mercuric oxide poses no such problems. Also as the solubility of mercury in alkaline solution is so small ( ca. 5x 10-7wt% in 5M potassium hydroxide ) there is no significant toxicity problem. Four commercially available aluminium alloys of varying compositions were obtained from aluminium companies involved in the research and development of aluminium air batteries. It was decided to extend the examination of the mixed alkaline electrolyte to these alloys and study the performances using various electrochemical techniques. The role of mercuric oxide on the discharge process was also further investigated. Study of the anodic behaviour of the aluminium alloys was achieved using the traditional "electrochemical half cell tests employing various alkaline electrolytes. Half cell -tests indicated that the most negative potential and the highest limiting current density values were actually obtained using potassium hydroxide electrolyte. However, this tended to be overshadowed in the full cell tests by the considerably longer operating life of the cells employing the mixed electrolyte. The overall results indicate the superior performance of alloys containing significant quantities of tin and titanium. Also, the full cell performance of the alloy New Q4, containing the same additives as Q4 but in different quantities, was also extremely attractive. These elements are believed to form a layer on the electrode surface during discharge, thereby controlling the dissolution of the aluminium and preventing excessive hydrogen evolution and cause an anodic shift in potential. Evidence of the formation of these layers on the electrode surface was not easily obtained. EDAX mapping of the electrode surface revealed some interesting micrographs in which the quantities of some these elements on the electrode surface appeared to increase after discharge. This evidence was inconclusive however, as the element to aluminium ratio was too small for any value to be recorded. This did suggest though that certain, elements like tin and titanium did form a layer on the surface. It was then decided to carry out ESCA work on the electrode surfaces both prior to and after discharge. ESCA did reveal that certain elements were present on the electrode surface after discharge, and thus suggests that the formation of a layer of an element on the electrode surface during discharge is likely. Some preliminary ellipsometry experiments were performed to study the effect of the various alloying elements on the oxide film present on the aluminum surface. Initial experiments revealed interesting information in that the alloys behaved differently. It seems that the surface structure is extremely sensitive to the composition of the alloy. Further work in this area could lead to more information about the oxide film and the most suitable alloying elements for rapid breakdown of the layer on commencing discharge.The various electrolytes used for the experiments resulted in a different reaction product structure on precipitation of aluminium hydroxide. With potassium hydroxide electrolyte a fine white precipitate is obtained which completely smothers the electrode surface. With the electrolyte mixture, a granular precipitate is obtained which may allow the diffusion of ions to and from the electrode surface after passivation has occurred. This coupled with the greater solubility that the electrolyte mixture has for aluminate, results in longer operating life of the full cell system. Another factor is that the granular, electrolyte is easily removed from the cell by washing, unlike the precipitate from use of potassium hydroxide. This enables the actual cells to be used for longer periods as the active sites on the cathode are not covered by this fine white precipitate. Also'the stability of the mixed electrolyte after passivation is of benefit as complete precipitation from the electrolyte does not occur. With potassium hydroxide electrolyte, complete precipitation occurs as soon as passivation commences. Use of mixed electrolyte in full cell tests always resulted in longer operating life for every alloy. However, only two of the four alloys under test showed a significant. -power output increase. It must be noted though that the build up of precipitate during the operation of the cell affects the performance. Use of a- pump enabling the electrolyte to circulate through the cell and an external reservoir would be expected to reveal the effect of the higher solubility of the mixed electrolyte to a greater extent. The alloys which did show greater power output from use of the mixed electrolyte were numbers 2 and 3, the former being a low corrosion alloy and the latter containing significant proportions of tin and titanium. However, the stability and reaction product structure make it desirable for all alloys in aluminium air cells to be discharged in a mixed electrolyte of sodium and potassium hydroxide rather than the traditionally used potassium hydroxide. Finally the effect of adding mercuric oxide to the electrolyte was examined using a novel electrode microzone scanning current measurement technique. This technique allowed the in situ examination of the current distribution on the electrode surface to be measured. Conclusive new evidence was found regarding the effect of mercury on corrosion current, -current distribution and the superior=characteristics of, the material as an electrolyte additive rather than an alloying element.

Oral pharmaceutical composition of ibuprofen and aluminium hydroxide

Abstract: A pharmaceutical composition for oral administration comprising a mixture of ibuprofen or a pharmaceutically acceptable salt thereof and aluminium hydroxide, the amount of aluminium hydroxide being sufficient to mask the bitter taste of the ibuprofen, or the salt thereof which would be evident in the absence of aluminium hydroxide The ratio of aluminium hydroxide (expressed as equivalent aluminium oxide) to ibuprofen may be in the range 1:50 to 5:1 parts by weight

Process of the production of aluminium oxide by using lime-bayer treament-water-type bauxite

Abstract: This process belongs to the production technique of aluminium hydroxide or aluminium oxide. Its main technic characteristic is that SiO2 contained in the ore is also added with a corresponding amount of lime, pressure-boiled and soaked out from the ore, so that SiO2 may be partially or wholly generated watery calcium aluminosilicate, thus the chemical loss of alkali is decreased or avoided. Additionally, red-mud can be used to produce silicate or other kind of cement, and to ultilize the waste and reduce environmental pollution is rechieved too.

Method of processing bauxites into alumina

Abstract: FIELD: chemistry.SUBSTANCE: invention relates to method of processing bauxites into alumina. Method includes grinding bauxite in spent liquor, leaching, thickening with obtaining aluminate solution and red sludge, washing red sludge, decomposition of aluminate solution with obtaining aluminium hydroxide and mother liquor, evaporation of mother liquor with obtaining spent liquor and calcinations of aluminium hydroxide with obtaining alumina. After grinding bauxite in spent liquor obtained pulp is heated until water is removed from spent liquor and dry residue is obtained, evaporated water is condensed, combined with dry residue and directed to leaching, and after operation of thickening aluminate solution is subjected to operation of desiliconisation with obtaining white sludge and aluminate solution, which is directed to decomposition operation.EFFECT: ensured are increase of chemical output of alumina from 83,8 to 97,1%, reduction of red sludge output from 55,8 to 29,5%, reduction of alumina content in wastes of production in form of red sludge from 14,5 to 4,1%, increase of iron oxide content in red sludge from 46,4 to 75,9%, which makes its application as iron ore raw material promising.

Process for the preparation of sintered alumina ceramics particularly for use in mineral oil mining

Abstract: According to the process of the present invention an aluminium compound - preferably aluminium hydroxide, bohmite, gamma-aluminium oxide or alpha-aluminium oxide or a mixture thereof - is activated with additives and sintered to yield ceramic shaped articles. The process of the present invention comprises adding to the aluminium compound(s) in an amount at least 0.05 % by weight - related to the aluminium oxide content thereof - yttrium oxide or lanthanun oxide or neodymian oxide or an equivalent amount of a salt thereof which can be converted into the corresponding oxide by heating: separately homogenizing the said mixtures by grinding and subjecting the same to thermal treatment at a temperature of at least 1450 C and thus reacting at least 80 % by weight of the said additives with aluminium oxide; thereafer admixing two or three of the activated aluminium oxides thus obtained and grinding the mixture thus obtained having a total additive content of 0.1-1.0 % by weight - expressed in pure oxides - and thereafter converting the ceramic basic materials thus obtained into shaped articles by known methods and finally sintering at a temperature above 1450 C.