Abstract: Disclosed herein, is a process for recovering valuable metals and/or their oxides from red mud bauxite residues or similar. The process comprises: calcining a red mud residue having a pH of less than about 10 to provide a calcinated red mud residue; acid leaching the calcinated red mud residue to provide a silica rich solid component and an acid leachate; separating the silica rich solid component and the acid leachate; precipitating an iron rich solid component from the acid leachate; and separating the precipitated iron rich solid component from the acid leachate to provide an aluminium rich liquor.

Abstract: As population density increases, the transportation of hazardous chemicals, including acids and disinfectants, lead to an increased incidence of spills while the consequences of spills become more serious. While solutions of halide acids, hypohalites and halites are safer disinfectants for transportation, handling, storage and use than traditional gaseous chlorine, the manufacturing cost of these disinfectants has here-to-fore limited their use. Economical processes are presented for the manufacture of O2, halogen oxides, halide acids, hypohalites, and halates; as well as polynucleate metal compounds, metal hydroxides and calcium sulfate hydrate (gypsum). The instant invention presents methods and processes that incorporate the use of sulfur. This is while environmental regulators, such as the US EPA, require an increased removal of sulfur from hydrocarbon fuels, thereby creating an abundance of sulfur, such that the refining industry is in need of a way to dispose of said abundance of sulfur.

Abstract: A method for preparation of iodizing agent for the use in the formulation of iodized salt that offers excellent stability of iodine in iodized salt is developed and the unrefined salt iodized with this compound was tested for its stability in presence of moisture, temperature and metal salts at higher temperature. The hydrotalcite type layered compound was used to prepare such compound and part of carbonate was substituted with iodate anion. The iodizing agent exhibited excellent stability of iodine in iodized salt.

Abstract: A process for the removal and causticisation of sodium oxalate and/or sodium sulphate from a Bayer process liquor containing sodium carbonate and one or both of sodium oxalate and sodium sulphate in an alumina refinery is described. The process is based on the observation that to efficiently causticise sodium oxalate solutions, it is first necessary to remove the aluminate ion from solution, optionally with recovery of the aluminate ion in some later step. This is effected by removing aluminate ions from the Bayer liquor through the formation of a carbonate bearing hydrocalumite and/or sulpha-bearing hydrocalumite. The liquor may then be treated with sufficient lime to remove and causticise any residual carbonate ions and some or all of the oxalate ions present so that any reacted lime solids thus formed can be separated and safely disposed of.

Abstract: A method for preparing aluminum sulfate which comprises subjecting sulfuric acid and aluminum hydroxide to reaction, wherein the reaction is advanced in the presence of at least one member selected from the group consisting of nitric acid and a peroxide. An industrial composition comprising aluminum sulfate. By the method of the present invention, aluminum sulfate can be efficiently and commercially advantageously prepared. Further, the industrial composition of the present invention can be advantageously used in various industrial fields as, for example, a waste water treatment agent, a paper sizing agent, a tanning agent for hides, a clarifying agent for fats and oils, or a catalyst for industrial use.

Abstract: The present disclosure relates to a method for removing anions such as nitrate ion, sulfate ion, chloride ion, and phosphate ion existing in underground water, surface water or waste water. The method involves adding alumina cement and a calcium compound to the water containing the anion followed by applying an electric field thereto, thereby forming a chemical precipitate which is an insoluble complex salt. The disclosure also relates to a continuous process for removing the anion by continuously performing the above method for removing anions.

Abstract: A process for the removal and causticisation of sodium oxalate and/or sodium sulphate from a Bayer process liquor containing sodium carbonate and one or both of sodium oxalate and sodium sulphate in an alumina refinery is described. The process is based on the observation that to efficiently causticise sodium oxalate solutions, it is first necessary to remove the aluminate ion from solution, optionally with recovery of the aluminate ion in some later step. This is effected by removing aluminate ions from the Bayer liquor through the formation of a carbonate-bearing hydrocalumite and/or sulphate-hearing hydrocalumite. The liquor may then be treated with sufficient lime to remove and causticise any residual carbonate ions and some or all of the oxalate ions present so that any reacted lime solids thus formed can be separated and safely disposed of.

Abstract: This invention relates to a process for removing sulphates and calcium from a water stream which includes the steps of: combining the water stream and an amount of amorphous aluminum trihydroxide (Al(OH)3); allowing the formation of ettringite (3CaO.Al2O3.3CaSO4.31/32H2O) as a precipitate; and removing the precipitated ettringite from the water stream.

Abstract: The smelting of aluminum from alumina in the Hall-Heroult process can be dramatically improved by lowering power consumption and in the use of carbon free anodes by using a feed of positively charged alumina. Laboratory experiments have shown that the apparent solubility and reactivity of alumina in molten fluoride baths is surprisingly increased by altering the negatively charged aluminum hydroxide Al(OH)4− particles, at about pH of nine, to positively charged particles containing Al+++ with a pH of less than two, by using acid solutions. The alumina thus produced is referred to as Al+++ alumina, or positively charged alumina. In particular, sulfuric acid is used to convert aluminum hydroxide using the Bayer process to a family of basic aluminum sulfates, 3Al2O3.4SO3.9H2O, which are dehydrated and calcined to produce Al+++ alumina.

Abstract: The object of this invention is to provide a new low-cost method of production of the Aluminum Sulfate (Alum, Type 1, Class 1 and 2) from any alumina contained raw material, which comprises of selective precipitation of ferric ions from aluminum sulfate solution by adding a soluble phosphate compound at pH at least of 2.0.

Abstract: The invention relates to a process for recovering metals from used nickel/hydride storage batteries, in which storage battery scrap has been mechanically comminuted and divided into at least a coarse fraction and a fine fraction capable of being treated separately from one another. The process comprises the steps of digesting and dissolving the fine fraction with a mixture of sulfuric acid and hydrogen peroxide, performing a double sulfate precipitation of the rare earths by raising the pH, performing a precipitation of the iron and of the aluminum by further raising the pH, performing a solvent extraction of other metals to separate nickel and cobalt which remain in the aqueous phase from the other metals which are extracted into the organic phase. Optionally, the nickel and the cobalt can be separated from each other and, if desired, the mixed-metal rare earth component which has been recovered can be melted together with cobalt and nickel alloy for the fabrication of new batteries.

Abstract: A process for extraction of alumina from ore bodies containing aluminum is disclosed. The process comprises the steps of acid leaching an aluminum bearing ore to produce a leach liquor that includes aluminum values and silicon values. Any ferrous sulfate in the leach liquor is oxidized with an oxidizing agent comprising ozone to ferric sulfate. The oxidized leach liquor is hydrolyzed at about 130.degree. C. to form a gel of ferric values which are then removed. Any ferric sulfate remaining in the leach liquor after hydrolyzing is reduced to ferrous sulfate. The reduced leach liquor is then hydrolyzed at 165-180.degree. C. to remove precipitated basic aluminum alkali sulfate. The basic aluminum alkali sulfate is then dried and calcined at around 950.degree. C. to produce alumina and alkali sulfate which releases any SO.sub.2 and any SO.sub.3. The alumina is washed to remove any alkali sulfate and the washed alumina is then agglomerated and dried.

Abstract: A process for treatment of hazardous liquid waste comprising trace amounts of hazardous elements in solution as oxyanions by oxyanion fixation within ettringite and related minerals. In accordance with the disclosed process, reagents for forming ettringites are mixed with the waste stream resulting in the formation of oxyanion-substituted ettringite and related materials. The resulting ettringite and related minerals are separated by filtration from the liquid. Thereafter, the liquid, having an elevated pH, is neutralized by carbon dioxide sparging resulting in precipitation of excess reagents in the liquid. Thereafter, the precipitates are filtered, producing a clean liquid.

Abstract: A method for producing an anion intercalated hydrotalcite without first forming hydrotalcite and then having to activate the hydrotalcite prior to substituting anions in the hydrotalcite structure. The method includes reacting an activated magnesia with an aqueous solution of aluminate, anion, such as bromide, chloride, sulfate, borate and combinations thereof and hydroxyl ions. The method can be carried out at atmospheric pressure to form hydrotalcite in high purity and high yield. In a preferred embodiment of the invention, the aluminate solution is formed from sodium aluminate, sodium bromide and sodium hydroxide and the aqueous solution is substantially carbonate free. Other anion intercalated hydrotalcites can also be produced by the method of the present invention.

Abstract: Aluminum sulfate that is less colored is prepared by adjusting the concentration of hydrogen peroxide in sulfuric acid to 0.1% by weight or less, and contacting the sulfuric acid with an alumina-containing compound.

Abstract: A method for the processing of fly ash scrubber sludge or the like is provided. The method yields unique products, including a usable calcium silicate material and a high purity alumina material. The process involves a plurality of stages including a first magnetic separation in an acid leach. During the acid leach, valuable mineral components are converted into soluble sulfates. The leach residue, containing calcium materials, is extracted with ammonia solution to yield a desirable calcium silicate product. The leach liquor is treated in a preferred manner to precipitate relatively acid free aluminum sulfate. The aluminum sulfate is then converted into a desirable alumina product.

Abstract: The invention relates to a process for the recovery of metal values contained in a ferric gangue.The process comprises the following stages:(a) dissolution of the metal values from the ferric gangue with sulphuric acid;(b) recovery of the metal value or values by a method which is known per se,(c) evaporation of the acid ferric solution resulting from stage (b) so as to increase the acidity to a value of between about 50 and 100%,(d) crystallization from this solution, at a temperature of between -10 and 50.degree. C., of a hydrated iron sulphate of formula Fe.sub.2 (SO.sub.4).sub.3.9H.sub.2 O.Application to the recovery of strategic metals.

Abstract: Transparent conductive coatings excellent in transparency are provided on substrates such as glass, plastics, etc. by the use of conductive coating materials obtained by maintaining aqueous solutions of hydrolyzable tin containing or indium containing compounds at pH of 8-12, and gradually hydrolyzing said compounds in the solutions to form sols containing colloidal particles, followed by drying and calcining.

Abstract: A process for the treatment of waste materials such as spent cathode liners involving combustion of the contained carbonaceous material, decomposition of the contained cyanides, sulphides and nitrides, and recovery of fluoride values by a sulpholysis reaction, is characterized in that the sulpholysis reaction is carried out in a separate stage. The process enables a recovgery of fluoride values from smelter wastes which is especially favourable environmentally. A further advantage of the invention is that recovery of the contained fluoride values, initially in the form of gaseous fluoride species, may subsequently be treated with alumina to produce aluminium trifluoride, which is of significant economic importance.

Abstract: The present invention relates to a process for the preparation of a poly aluminum sulphate product having the following formula:[Al.sub.A (OH).sub.B (SO.sub.4).sub.C (H.sub.2 O).sub.E ].sub.nin whichn is a positive integer;A is 1.0;B ranges from 0.75-2.0;C ranges from 0.5-1.12; andE is 1.5 to 4 when the product is in solid form; andE is larger than 4 when the product is in aqueous form, and whereinB+2C=3,said process comprising reacting an Alum solution with a suitable alkali aluminate under high shear mixing and recovering the desired product.

Abstract: A method for recovering gallium, which comprises a capturing step of contacting an aqueous solution containing gallium to a chelating agent containing a water-insoluble substituted quinolinol as the active ingredient, to let the chelating agent capture gallium, and an eluting step of contacting an eluting solution composed of an aqueous solution of an acid or strong base containing said substituted quinolinol, to the chelating agent from the capturing step, to elute gallium therefrom.

Abstract: A nickel-containing ore is leached with sulfuric acid to dissolve nickel and associated metallic values into the sulfuric acid to form a leachate, the sulfuric acid further containing a source of the monovalent cations sodium, potassium or ammonium to suppress solubilization of aluminum ions in the ore. The leaching process is conducted at elevated temperatures of from about 200.degree. C. to about 300.degree. C., and at elevated pressures. In such leaching process, the monovalent cations are present in the leaching liquid prior to the initiation of leaching, to achieve an aluminum content of the leachate of less than about 0.5 grams per liter.

Abstract: Spent catalysts from hydrocarbon refining processes, comprising transition metal compounds on aluminum oxide-containing supports, are subjected to an oxidative roasting and are treated with sulfuric acid in a counter-current digester to dissolve metals. Following operations to separate compounds of the various transition metals, a solution containing approximately stoichiometric equivalents of aluminum and sulfate is obtained.

Abstract: A process for the recovery of aluminum and at least one other metal selected from the group consisting of molybdenum, nickel and cobalt from a spent hydrogenation catalyst comprising (1) adding about 1 to 3 parts H.sub.2 SO.sub.4 to each part of spent catalyst in a reaction zone of about 20.degree. to 200.degree. C. under sulfide gas pressure between about 1 and about 35 atmospheres, (2) separating the resultant Al.sub.2 (SO.sub.4).sub.3 solution from the sulfide precipitate in the mixture, (3) oxidizing the remaining sulfide precipitate as an aqueous slurry at about 20.degree. to 200.degree. C. in an oxygen-containing atmosphere at a pressure between about 1 and about 35 atmospheres, (4) separating the slurry to obtain solid molybdic acid and a sulfate liquor containing said at least one metal, and (5) recovering said at least one metal from the sulfate liquor in marketable form.

Abstract: A process of producing a flocculating agent useful for water purification technology and as a substitute for aluminium sulphate in the rosin sizing of paper is described. In this process, about 100-150 parts by weight, preferably about 130 parts by weight of hydrochloric acid, calculated as 100% HCl, and 140-200, preferably 160-190 parts by weight of a sulphate-containing, aluminium hydroxide-containing sludge, calculated on the solids content of the sludge, are mixed. To obtain the sludge, alkaline pickles used in the pickling of aluminium profiles in connection with the anodization of aluminium are neutralized with sulphuric acid or aluminium sulphate. The sludge may also contain up to about 10% by weight of aluminium hydroxide. The mixture is heated and stirred at a temperature of from about 80.degree. C. to the boiling point of the mixture, preferably 95.degree.-100.degree. C., for a combined time of about 3-15 hours, preferably about 4-6 hours.

Abstract: The invention relates to basic chromium aluminum sulfates which are soluble in cold water and are of the general formulaCr.sub.x Al.sub.2-x (OH).sub.2 y. (SO.sub.4).sub.3-y.n H.sub.2 Owhere x is from 0.1 to 1.9, y is from 0.01 to 2 and n is from 4 to 24, and a process for the preparation thereof. The process comprises reacting chromium (III)--containing waste sulfuric acid having a water content of 20-50% by weight with aluminum oxide and/or aluminum oxide hydroxide and/or aluminum hydroxide at a temperature of 100.degree. to 200.degree. C. The molten product is converted to droplet form and allowed to solidify in free fall.

Abstract: A process is provided for selectively recovering zinc from steel plant dust containing substantial amounts of iron. The process comprises atmospherically leaching the steel plant dust in a first stage wherein an amount of steel plant dust is mixed with an amount of acidic zinc sulfate solution to leach zinc therefrom, the leaching of the dust being such that the solution is controlled to a terminal pH ranging from about 2 to 3.5 and preferably from about 2.5 to 3.5, thereby limiting iron dissolution. The mixture is then subjected to a crude liquid/solid separation step whereby a thickened pulp is produced containing zinc and iron values and a separated liquid containing low iron and substantial amounts of zinc, the solution being sent to zinc recovery.

Abstract: A process is provided for hydrometallurgical processing of steel plant dusts containing cadmium, lead, zinc, and iron values, along with impurities such as chloride and fluoride salts of sodium, potassium, magnesium, etc. The first step in the process involves leaching the dust in a mixed sulfate-chloride medium that dissolves most of the zinc and cadmium. Any iron and aluminum dissolved in this step is precipitated by oxidation and neutralization. Zinc is recovered from the resulting solution by solvent extraction which provides a raffinate which is recycled to the leaching step with a bleed stream also provided for recovery of cadmium and removal of other impurities from the circuit. The lead sulfate residue from the leaching step is leached with caustic soda, and zinc dust is used to cement the lead out from the caustic solution, which then joins the main solution for zinc recovery.

Abstract: The present invention relates to a method for producing a polyaluminium hydroxide complex of a chloride and sulphate type in solid form, an aqueous solution of the polyaluminium hydroxide complex being admixed with at least one water-miscible organic solvent having 1-4 C, the weight ratio of the aqueous solution to the solvent being at least 1:0.70, preferably 1:1-2, to crystallize the complex.The method provides a highly stable, amorphous crystalline product.

Abstract: A hydrometallurgical process is provided to electrogalvanize steel, utilizing primary and secondary zinc sources. The process consists of leaching the feed in a mildly acidic solution. The zinc is selectively recovered from the leach liquor in a solvent extraction system and thereafter stripped from the solvent using a stronger acidic solution to provide a strip solution which is fed to an electrogalvanizing bath for electrogalvanizing steel products, e.g., sheet steel, using insoluble anodes. Acidic solutions and organic solvent are recycled in the process.

Abstract: According to the present invention, processes are provided for recovery of nickel, cobalt and like metal values from laterite ores wherein the ores are separated into high and low magnesium containing fractions, the low magnesium fraction is leached with sulfuric acid at elevated temperatures and pressure to solubilize the metal values. The pregnant liquor resulting from the high pressure which also contains solubilized Fe, Al and acid is then contacted with a low magnesium fraction of the ore in a low pressure leach under conditions such that at least some of the acid is neutralized and substantially all of the solubilized Fe and Al is removed as hematite and alunite precipitate.In one embodiment, the pregnant liquor from the high pressure leach and the high magnesium fraction are contacted at atmospheric pressure and a temperature of about 80.degree. C. prior to low pressure leaching. In other embodiments, various process streams are separated by size and otherwise, and recycled to within the processes.

Abstract: According to the present invention, Ni- and Co-rich, low Mg fines may be advantageously separated from the coarse fractions of lateritic ores by atmospheric or low pressure leaching. In particular, the process of the present invention comprises contacting a lateritic ore or ore fraction at temperatures from about 20.degree. C. to about 200.degree. C. and pressures from about atmospheric to about 200 psig with an aqueous acid solution to form a leach liquor, a leach residue and a fines fraction. The fines fraction which can be separated from the residue with the leach liquor by conventional means such as cycloning is found to be richer in Ni and Co and lower than the remainder of the residue.

Abstract: The invention relates to an improved process for reducing the iron content of iron-, silicon- and aluminium-containing raw materials and for producing ferric oxide, optionally along with an alumina concentrate. According to the invention the iron content of mineral raw materials, e.g. bauxites, clay minerals, colliary rocks, red muds, etc. is eliminated by passing through one or more beds prepared from the unground but preferably prebroaken and sized raw material an aqueous hydrochloric acid solution, the concentration of which exceeds 100 g./lit., at a temperature below 90.degree. C., preferably at room temperature, optionally in the presence of a flocculating agent. By pyrolytic decomposition of the ferric chloride prepared ferric oxide can be produced.

Abstract: In a process for the production of alumina from aluminous raw material, an ammonoalunite intermediate is formed. The raw material is preferably a clay which is leached with sulfuric acid to form an aluminous solution which is separated from the solid materials. After any required extraction of iron, such as by liquid ion exchange, the solution is subjected to elevated temperatures and pressures in the presence of ammonium ions to form ammonoalunite which is recovered as a precipitate. The liquor is recycled to leach the clay, while the ammonoalunite is thermally decomposed to alumina. Gases liberated during decomposition are scrubbed with recycled liquor to form clay leach liquor. The alumina may be purified by washing with sulfuric acid to obtain a purity suitable for aluminum electrolysis.

Abstract: A process for producing basic aluminum sulfate of the general formulaAl(OH).sub.a (SO.sub.4).sub.b.nH.sub.2 Owherein a, b and n are positive numbers satisfying a+2b=3, 2.30.ltoreq.a.ltoreq.2.56, 0.22.ltoreq.b.ltoreq.0.35 and O.ltoreq.n.ltoreq.10, which comprises reacting a water-soluble basic aluminum salt of the general formulaAl(OH).sub.c X.sub.dwherein X represents a monovalent anion, and c and d are positive numbers satisfying c+d=3 and 0.5.ltoreq.c.ltoreq.2.55, with a water-soluble sulfuric acid salt in an aqueous medium at a temperature of less than 90.degree. C. This process gives novel basic aluminum sulfate which is either fibrous, spherical or prismatic depending upon the reaction conditions.

Abstract: A process for the recovery of valuable metals from roasted crude-oil sulfur-extraction catalyst waste is disclosed. In this process the value metals can be separated from aluminum in a single stage by treating the waste at elevated temperature and pressure with such an amount of sulfate solution that the waste dissolves and the aluminum simultaneously precipitates as alunite, which is separated from the solution which contains the other value metals. A sulfate solution is preferably added in such an amount that the concentration of sulfuric acid in the solution is 2-30 g/l at the end of the stage.

Abstract: Bayer process caustic liquors are purified by treating the liquors with an organic solvent of relatively low boiling point, such as methanol, which causes the precipitation of inorganic carbonate and/or sulfate salt from the treated liquor. The treating solvent can be readily recovered for reuse.

Abstract: Aqueous aluminum sulfate solution is hydrolyzed at temperatures above about 300.degree. C. to produce a basic aluminum sulfate product that is readily purified and converted to Al.sub.2 O.sub.3.

Abstract: Flue gas containing sulfur dioxide is purified (and the sulfur content thereof is recovered in elemental form) by scrubbing the gas with aqueous sodium aluminate-sodium hydroxide solution thereby forming an underflow suspension consisting essentially of sodium and aluminum sulfites and sulfates and fly ash; oxidizing the sulfites to sulfates; evaporating the free water present; reducing the resulting apparently dry mixture of sodium and aluminum sulfates by the action of reactive hydrogen and a carbonaceous reducing agent thereby forming a solid mixture of a sodium oxide and sodium aluminate and a gaseous mixture comprising sulfur dioxide, sulfur, and hydrogen sulfide; condensing said sulfur; and inter-reacting said sulfur dioxide and hydrogen sulfide to provide elemental sulfur. The solid mixture is dissolved in water to regenerate the scrubbing solution, which is then recycled. The solution is filtered at any convenient point to remove fly ash and any other solids present.

Abstract: The invention concerns a process for the preparation of alumina and ferric oxide from low-grade aluminium and iron carriers. The processes, in addition to conventional technological steps, comprises the steps of dissolving the iron content of a ground, mineral material in an aqueous hydrochloric acid solution containing 200 to 420 g./lit. of hydrochloric acid at 90.degree. to 130.degree. C., eliminating the iron from the slurry of from a solution obtained by filtration of the slurry, with an anion exchange resin or semipermeable membrane or cloth, continuously or discontinuously, eluting the iron from the ion exchange resin and recycling hydrochloric acid and sulfuric acid in a closed system.

Abstract: Recovery of fluoride values from carbonaceous waste cathode materials is achieved by reacting the waste materials with oxygen, water, and sulfur dioxide at temperatures between about 600.degree. C. and 1200.degree. C.

Abstract: A process for commercially producing sulfates useful in the water treatment and papermaking industries from by-product aluminum oxides is taught. The process comprises feeding the aluminum oxide by-product and weak process liquor into digester vessel to form a slurry which is then heated. Sulfuric acid and additional oxide feed is added into the slurry mixture allowing the reaction to go to completion. Specific variables such as temperature, pH, reactant concentrations, reaction times and process liquor recycle are controlled to substantially eliminate certain heavy metals in any form whatsoever from contaminating the final sulfate product.

Abstract: A non-evaporative process for the production of drier aluminum sulfate is disclosed. A purified alum liquor containing 6 to 11% alumina as Al.sub.2 O.sub.3 is contacted with aluminum trihydrate and additional sulfuric acid in amounts sufficient to produce drier, low iron aluminum sulfate.

Abstract: There is disclosed a method for the elimination of the chief impurities in aluminum dross tailings. The method can be used as a pretreatment in the manufacture of aluminum sulfate from aluminum dross tailings in a continuous flow reaction zone in which the dross tailings prior to reaction with sulfuric acid are pretreated to reduce the more objectionable contaminants contained therein to acceptable levels. The most objectionable contaminant in the dross tailings is aluminum metal which, in the invention, is oxidized with water or steam at elevated temperatures. The dross tailings, which are chiefly particles of aluminum oxide, are suspended in an aqueous slurry and the slurry is heated to a temperature from 185.degree.-225.degree. F. and maintained under liquification pressures and sufficient agitation to insure particle-to-particle attrition that removes an aluminum hydroxide coating which would otherwise inhibit the reaction.

Abstract: A process and installation for the integrated treatment of concentrated residual solutions resulting from the anodization of aluminium parts is described, in which caustic soda is employed in the pickling process and sulphuric acid in the anodization bath.The process comprises three sets of operations:(1) Production of aluminium sulphate in concentrated solution or in hydrated crystals, by the treatment of part of the residual solution from the anodization.(2) Production of precipitated aluminium hydroxide and a solution of sodium sulphate from residual anodization and pickling solutions.(3) Production of sodium aluminate from residual pickling solutions and aluminium hydroxide producted in (2). (FIG. 1.

Abstract: This disclosure deals with ettringite whiskers, methods of synthesizing such whiskers and ettringite whisker composites. The ettringite whiskers, having a new crystal form, are 1-2 .mu.m in diameter, 50-100 .mu.m in length and approximately 30-50 of aspect ratio. The ettringite whiskers are especially useful in industry as a high tensile strength reinforcement, they increase self-extinguishability and the productive capacity of making sheets, boards of the like.

Abstract: The invention described herein relates to a method for improving the acid leachability of aluminum and other metal values found in fly ash which comprises sintering the fly ash, prior to acid leaching, with a calcium sulfate-containing composition at a temperature at which the calcium sulfate is retained in said composition during sintering and for a time sufficient to quantitatively convert the aluminum in said fly ash into an acid-leachable form.

Abstract: The invention concerns a process for sulfuric acid treatment of clays or aluminiferous minerals to obtain pure aluminum oxide via a basic intermediate. The process finds application in the production of aluminum through fusion electrolysis and for the production of different types of alumina. The process provides a mass production method which is economically and technically superior over the prior art methods.The mechanically and/or thermally pretreated raw material is subjected to a two-step pressure treatment with sulfuric acid solution. The aluminum sulfate solution is treated to reduce the iron with SO.sub.2 and hydrolytic precipitation of basic aluminum sulfates. After separation of the salts from the mother liquor, which is returned to the process, the aluminum sulfate is thermally decomposed. The SO.sub.2 /SO.sub.3 -containing waste gases from the decomposition are used to renew the treatment acid.

Abstract: Processes for the production of alumina and cement constituents from fly ash, in which the fly ash is subjected to magnetic separation removing magnetic constituents; the remaining non-magnetic fraction of fly ash is then mixed with a calcining agent and water, pelletized, dried and calcined, cooled, and then either acid cured or subjected to a hydrothermic shock treatment in sulfuric acid; the mixture is then diluted with water, filtrated, purified by a solvent extraction process, and evaporated yielding aluminum sulfate, which is then subjected to liquid-solid separation and decomposed at an increased temperature at which the sulfur in the form of sulfur oxide gases and the water vapor is driven off, alumina remains. The leach residue of the alumina extraction yields useful material for cement production.

Abstract: A process for obtaining pure alumina comprising the combination of chlorosulphuric attack of calcined aluminous ores containing impurities, followed by concentration of the liquor obtained after the attack and separation of the sterile material, sulphuric acid treatment of the concentrated liquor followed by chlorination to precipitate almost all the hexahydrated aluminum chloride, separation of the precipitate of hexahydrated aluminum chloride and of the chlorosulphuric mother liquor charged with impurities, pyrohydrolysis of the precipitate to give the desired pure alumina with recycling of released hydrochloric acid, degassing of the chlorosulphuric liquor of impurities with recycling of the gaseous HCl for chlorination, yielding a sulphuric liquor of impurities, finally the elimination of the impurities present in this latter liquor in the form of a sulphuric precipitation by concentration in the presence of potassium ions.