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 the simultaneous recovery of substantially pure alumina and silica from an aluminosilicate. The process comprises the following steps: (i) heating the aluminosilicate with hydrated CaCl.sub.2 to obtain calcium-alumino-silicate and calcium-aluminate products, wherein the CaCl.sub.2 is substantially free of MgCl.sub.2 ; (ii) leaching the products with HCl to form a solution comprising AlCl.sub.3 and CaCl.sub.2, and insoluble silica; (iii) separating the insoluble silica from the solution; and (iv) crystallizing AlCl.sub.3 from the solution and recovering the alumina from the crystallized AlCl.sub.3. The process may further comprise the following steps: (v) substantially removing MgCl.sub.2 from the CaCl.sub.2 solution of step (iv); and (vi) recycling the CaCl.sub.2 solution for use in step (i).

Abstract: A process for treating spent potliner material from aluminum reduction cells and recovering useful products. In the process, spent potliner material is introduced into an acid digester containing, for example, sulfuric acid. A gas component is produced which includes hydrogen fluoride and hydrogen cyanide. A slurry component is produced which includes carbon, silica, alumina, sodium compounds such as sodium sulfate, aluminum compounds such as aluminum sulfate, iron compounds such as iron sulfate, magnesium and calcium compounds such as magnesium and calcium sulfate. The slurry component remains in the digester after the gas component is removed. The gas component is recovered and heated an effective amount to convert or decompose the hydrogen cyanide to a remaining gas component including CO.sub.2, H.sub.2 O, and nitrogen oxides, as well as HF gas. The remaining gas component is directed through a water scrubber in which the HF gas is converted to liquid hydrofluoric acid.

Abstract: The present invention relates to a process for reducing and/or removing inorganic matter from a material containing inorganic matter which comprises the steps of:(i) (a) treating the material with a source of hydrogen fluoride so as to form a first residue and a first solution containing inorganic matter;(b) separating the first residue from the first solution containing the inorganic matter;(c) treating the first residue with an acid so as to form a second residue and a second solution containing further inorganic matter; and(d) separating the second residue from the second solution containing the further inorganic matter; or(ii) (a) treating the material with an acid so as to form a first residue and a first solution containing inorganic matter;(b) separating the first residue from the first solution containing the inorganic matter;(c) treating the first residue with a source of hydrogen fluoride so as to form a second residue and a second solution containing further inorganic matter; and(d) separating the

Abstract: The present invention relates to a process for the preparation of solutions of aluminum salts, characterized in that an aluminate of an alkali metal and/or alkaline earth metal is dissolved in an acid solution to the formation of a solution which is used as such or is diluted to a suitable concentration.

Abstract: The invention relates to a method for treating waste water sludge comprising at least one metal originating from a waste water treatment coagulant, and phosphorus and heavy metals in order to recover said at least one metal and phosphorus and to discharge said heavy metals. In this method said waste water sludge is acidified to dissolve metals contained in the sludge thereby yielding an acidified sludge solution containing at least 1% by weight of at least one metal to be recovered. In a first precipitation stage the pH of said acidified sludge solution is raised to precipitate at least one metal to be recovered as a phosphate, and thereafter the phosphate precipitate is separated, thereby leaving a solution comprising heavy metals. In a second precipitation stage the pH of said solution comprising heavy metals is raised and, if necessary, an appropriate chemical is added to precipitate heavy metals, and thereafter the precipitate is discharged.

Abstract: Substantially crystalline kaolin clays having varying morphological properties are produced by the hydrothermal treatment, in an acidic environment, of substantially amorphous calcined kaolin clay.

Abstract: Kaolin clay materials containing discoloring impurities can be beneficiated by microwave irradiation in the presence of water and a polyprotic acid component to produce a beneficiated kaolin clay material having improved color and brightness.

Abstract: A process for the treatment of aqueous acidic liquors containing dissolved aluminum and/or iron compounds to produce an aluminum and/or iron sulfate water-treatment product is characterized by the combination of steps comprising contacting the liquor with a basic material capable of reacting with the dissolved aluminum and/or iron compound to precipitate aluminum and/or iron values, separating the precipitate in the form of a cake or slurry from the remaining liquor, treating the cake or slurry with sulfuric acid to re-dissolve aluminum and/or iron values and to produce a solution of aluminum and/or iron sulfate and separating suspended solid matter from the solution. The liquor may be a waste product from industrial processes or may be a mine effluent and the process avoids the need to dispose of these to waste.

Abstract: The invention provides an autoclave configuration for pressure leaching lateritic ores at elevated temperatures. The autoclave configuration includes at least one primary autoclave. The primary autoclave includes a slurry inlet port for receiving slurries of lateritic ore from a lateritic slurry supply, an acid inlet port for receiving leaching acids, an agitation means for agitating the slurries of lateritic ore, and an outer port for removing partially leached slurries of lateritic ore. A multi-compartment autoclave follows the primary autoclave. The multi-compartment autoclave is divided into at least two chambers connected in series. The chambers contain a means for agitating the partially leached slurries and divider walls for separating the chambers. An inlet port is connected to the first of the chambers for receipt of the partially leached slurries. An outlet port is connected to the last of the series of chambers for removal of the finally leached slurries.

Abstract: Aluminum and fluorine are recovered from fluorine containing waste materials from the production of aluminum metal (FCWM) as ALF.sub.2 OH hydrate by a process comprising: leaching FCWM with dilute sulphuric acid at a pH value within the range of 0-3; if needed adding aluminum in an acid soluble form; adjusting the pH value of the aqueous phase to a value within the range 3.7-4.1 at the end of the leaching period by addition of a caustic aqueous solution; precipitating silica at a temperature not exceeding 60.degree. C.; separating the reaction mixture into a solid phase containing precipitated silica and non-soluble residues of the FCWM and a purified solution; and precipitating AlF.sub.2 OH hydrate from the purified solution at a temperature within the range 90.degree.-100.degree. C. and at a pH value not exceeding about 4.1 by controlled continuous addition of an aqueous caustic solution. Reducing and/or non-oxidizing operating conditions are maintained during all these process steps. The precipitated AlF.

Abstract: An aqueous alumina dispersion prepared from high quality, submicrometer alumina powder, suitable for manufacturing fine ceramic products, is disclosed. The sub-micrometer alumina particles have a surface area of 2.5 to 50 m.sup.2 per gram of the alumina particles. There are three components in the dispersion: sub-micrometer alumina particles (10 to 68 percent based on weight of the colloidal dispersion), semicarbazide hydrochloride derivative (0.1 to 5 percent based on the weight of the alumina particles), and water (the balance).

Abstract: A process for recovering valuable metals from a waste catalyst based on an alumina carrier includes (a) roasting the waste catalyst at a temperature range of 400.degree. to 1,000.degree. C. to obtain a roasted product; (b) preparing a reduction dissolution by dissolving the roasted product with sulfuric acid in the presence of a metal as a dissolution catalyst; (c) separating a large part of the aluminum from the reduction dissolution solution and recovering aluminum as ammonium aluminum sulfate from the solution, optionally after subjecting the reduction dissolution solution to a treatment of removing iron; (d) extracting molybdenum as a molybdate by solvent extraction from the solution after separating and recovering aluminum from the solution; (e) extracting vanadium as a vanadate by solvent extraction from the solution obtained as a residue after extracting molybdenum; and (f) recovering nickel and cobalt each as a hydroxide from the extraction residue after recovering vanadium.

Abstract: A process for dissolving used catalyst includes the steps of roasting, after subjecting to an optional deoiling treatment, the used catalyst at a temperature lower than 1,000.degree. C. but not lower than the temperature at which any of the residual components in the used catalyst undergoes ignition and combustion where the residual components are selected from the group consisting of oils, sulfur components, and carbon components; and dissolving the roasted product using sulfuric acid after adding a metal to the roasted product as a catalyst for accelerating dissolution. The process provides a simple and efficient method for completely dissolving a used catalyst having a carrier containing alumina as the principal component.

Abstract: A mercury-free dissolution process for aluminum involves placing the aluminum in a dissolver vessel in contact with nitric acid-fluoboric acid mixture at an elevated temperature. By maintaining a continuous flow of the acid mixture through the dissolver vessel, an effluent containing aluminum nitrate, nitric acid, fluoboric acid and other dissolved components are removed.

Abstract: Process for the recovery of aluminum and fluoride values from spent pot lining materials comprising the steps of calcining spent pot lining material to produce an ash having environmentally acceptable levels of cyanide contamination, subjecting the ash to a leaching step in a solution containing a mineral acid and a corresponding aluminum salt in such proportions as to dissolve the aluminum and fluoride values, and subjecting the leached liquid to thermal hydrolysis to cause precipitation of an aluminum fluoride product.

Abstract: A process of treating metal chloride wastes produced by chlorination of titanium ore comprises the steps of:(a) leaching said metal chloride wastes in a hydrochloric acid (HCl)-containing solution to obtain a solution containing solids and dissolved metals,(b) separating said dissolved metals from said solids present in the solution obtained in step (a) to obtain a liquid and a residue,(c) selectively precipitating the metals as their hydroxides by adding a neutralizing agent to the liquid obtained in step (b),(d) separating the precipitate of metal hydroxides obtained in step (c) from the liquid to obtain a residue, and(e) dewatering the residue obtained in step (d).

Abstract: The present invention is directed to a method for treating a sludge containing substantial amounts of chromium, aluminum, calcium, iron, and phosphorous. The method comprises forming a slurry of the sludge; reacting the slurry with an acid to dissolve substantially all the aluminum and chromium and provide a solids residue comprising mostly calcium sulfate; separating the chromium/aluminum-containing solution from the solids residue; raising the pH of the chromium/aluminum solution to precipitate chromium as chromium hydroxide; and separating the chromium hydroxide from the remaining aluminum-containing solution. The chromium hydroxide is then enriched with an alkali or earth alkali compound and calcined in an oxidizing atmosphere to convert the chromium to a chromate. The calcine is leached in an aqueous medium at a controlled pH to yield a high concentration, high purity chromate solution suitable for producing metallic chromium or a variety of chromium chemicals.

Abstract: A process is disclosed for producing high brightness kaolin from ore containing silica, other types of clays, minerals such as ilmenite micas, feldspars and various metal silicates as well as organic matter. The process consists of sizing, a double floatation step, magnetic separation, leaching and oxidative brightening steps. This is a novel combination of conventional unit operations and in particular the use of a double floatation step to remove quartz and various trace minerals that interfere with achieving high optical brightness for kaolin.

Abstract: A method of eliminating the foam above a slurry of a corrosive liquid and solid matter where the foam is caused by a gas evolved by the reaction between the heated corrosive liquid and the solid matter comprising providing the heating energy by microwaves. This method has been found to be particularly useful in the sulphuric acid leaching of an ore concentrate in the production of beryllium hydroxide.

Abstract: The method of the invention is advantageously applicable to realize a multistage chemical process during which liquid clarifiers suitable for the purification of water and sewage, furthermore, fine-disperse pulverulent solid products utilizable as pait pigments and fillers may be recovered. Each final product of the multistage chemical processes is a useful material, so the whole technology is waste free.

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: A method is provided for treating sludge containing substantial amounts of chromium, aluminum and iron and residuals of other elements. The method comprises forming a slurry of the sludge in water at a temperature ranging from ambient to 150.degree. F. with the specific gravity of the slurry ranging from about 1.05 to 1.25, and adding a mineral acid to the slurry to provide a pH ranging from about 0.1-3 to dissolve selectively the aluminum and the chromium and leave a solids residue containing gangue material comprising an oxidized iron compound, calcium sulfate, calcium fluoride, calcium silicate among other solids. The pH of the solution is controlled at range of about 2 to 3.5 to precipitate undesirable elements, including iron, without substantially adversely affecting the dissolved chromium and aluminum.

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: There is disclosed a method of treating phyllosilicate materials by exposing the materials to a source of hydrogen ions to hydrate hydroxyl ions on and in the phyllosilicate structure. The source of hydrogen ions may be a simple organic, or mineral, acid, preferably formic or hydrochloric acid. The hydrated phyllosilicate may then be dehydrated and delaminated by thermal treatment.

Abstract: A process for the production of a refractory compound, e.g. a carbide or nitride, of a metallic or non-metallic element, by reacting a mixture of a compound of the metallic or non-metallic element having at least two groups reactive with hydroxyl groups and an organic compound having at least two hydroxyl groups to produce an oxygen-containing polymeric product, and pyrolysing the polymeric product, e.g. in an inert atmosphere to produce a carbide or in an atmosphere of reactive nitrogen compound to produce a nitride, in which the reaction mixture contains an aluminium compound containing at least one group reactive with hydroxyl groups.The presence of the aluminium compound in the reaction mixture leads to an increase in the proportion of carbon in the product initially produced by pyrolysis, and to a higher purity in the refractory compound which is ultimately produced.

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: Disclosed in a process for recovering aluminum flouride, caustic, and carbon from spent potlining retrieved from an aluminum electrolytic reduction cell. Spent potlining is treated by leaching with a caustic solution to produce a fluoride-rich basic liquor and carbonaceous solid residue followed by contacting the carbonaceous solid with an acid bath of aluminum sulfate and sulfuric acid to produce a fluoride-rich acid liquor.

Abstract: Chromium free cleaning compositions for cleaning aluminum and aluminum alloy surfaces comprisingA. from 0.2-4 g/l ferric ion andB. sufficient sulfuric and/or nitric acid to produce a pH of 2 or less.The invention also relates to compositions containing from 0.001-0.5 g/l of fluoride ions.

Abstract: A method for producing materials having a high purity, which comprises forming an oxidation reaction product of a parent metal and an oxygen-containing vapor-phase oxidant, comminuting the resulting ceramic body and leaching any non-oxidation reaction product and/or corresponding filler materials therefrom, and recovering said substantially pure materials.

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: Metal values including those of cobalt, vanadium, aluminum, molybdenum and tungsten are recovered from spent petroleum refining catalyst by acid leaching the metal values except those of molybdenum or tungsten, separating the resulting solution from the leach residue and selectively recovering the cobalt, vanadium and aluminum values from the solution and recovering the molybdenum and tungsten values from the leach residue.

Abstract: Methods of producing monocalcium phosphate and products created therefrom are provided. The method includes the steps of mixing phosphoric acid and water with brown mud. Preferably, the phosphoric acid is added to water so that it comprises approximately 3% to about 50% of the phosphoric acid/water mixture by weight, and the water comprises approximately 50% to about 97% of the phosphoric acid/water mixture by weight. The brown mud is added to the phosphoric acid/water mixture in a weight ratio of approximately 1:1 to about 1:3. The method of the present invention results in improved monocalcium phosphate products.

Abstract: A method for producing an alumina of high purity, which comprises forming an oxidation reaction product of an aluminum parent metal and an oxygen-containing vapor-phase oxidant, comminuting the resulting ceramic body, and leaching any non-alumina materials therefrom, and recovering said substantially pure alumina material.

Abstract: A method of dissolving aluminum hydroxide gel formed in situ in water heaters having aluminum anode rods therein, comprising contacting the aluminum hydroxide gel with phosphoric acid, said phosphoric acid being present in the range of from about 9% to about 35% by volume at a temperature in the range of from about 138.degree. F. to about 160.degree. F.

Abstract: Gallium is recovered from gallium arsenide by reacting and dissolving the gallium arsenide with an oxidant and a complexing agent, especially with water insoluble hydroxamic acids with mild conditions, e.g. with aqueous hydrogen peroxide and mild temperature, to effect separation of gallium hydroxamic acid chelates from water soluble arsenic compounds.

Abstract: Aluminum smelting dust is leached with mineral acids such as sulfuric acid, hydrochloric acid and nitric acid. Oxidizing agents such as potassium permanganate, manganese dioxide, hydrogen peroxide, ozone, potassium chromate, potassium dichromate, ammonium persulfate, sodium hypochlorite, sodium chlorite and sodium chlorate are added to the leach solution. The addition of an oxidizing agent remarkably improves the gallium extraction.

Abstract: 5 to 50 wt. % of an alkaline flux such as sodium carbonate, sodium hydroxide, potassium carbonate and potassium hydroxide is added and mixed to aluminum smelting dust. The mixture is roasted, the roasted mixture is acid-leached with mineral acids such as sulfuric acid, hydrochloric acid and nitric acid, and then gallium is preferentially extracted at a high yield compared to other components of the dust.

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 method of the present invention is a novel comprehensive process for maximizing the recovery of valuable mineral values from coal ash. Options may also be included for the production of saleable inorganic chemical by-products. The process employs both physical and chemical extraction techniques that maximize the yield of products while reducing the quantity of waste produced. Valuable minerals and chemicals such as cenospheres (hollow microspheres), carbon, magnetite (Fe.sub.3 O.sub.4), alumina (Al.sub.2 O.sub.3), iron oxide (Fe.sub.2 O.sub.3) and iron chloride (FeCl.sub.3) may be produced. Due to removal of carbon, magnetite, and iron oxide from the coal ash, the processed ash comprises a quality pozzolan.

Abstract: The invention relates to a method for recovering rare metals from the combustion residues of various coals, in particular brown coals. The recovery is performed by digestion, more particularly by aqueous and/or dilute alkaline and/or dilute acidic digestion, where two or three of these steps can be combined in any desired order or they may be carried out separately. During digestion the concentration of the solution is monitored and the subsequent digestion steps are terminated at a desired concentration. The solid and liquid phase are then separated and the rare metals are isolated from the liquid phase while the solid phase, optionally after neutralization and/or washing can be utilized for example as a source of energy.

Abstract: A process is described for the formation of high purity alumina from Bayer Process alumina trihydrate (gibbsite). The solid hydrated alumina is reacted with concentrated HCl to cause partial or complete conversion to aluminum chloride hexahydrate (ACH). The ACH or mixture of ACH and unreacted hydrated alumina is recovered as a solid and calcined in a single or multistage calcination to high purity alumina. Soda contents in the product anhydrous alumina can be reduced by 98% or greater. Contents of other impurities, such as silica, iron, magnesium, etc., are also markedly reduced. Different degrees of impurity reduction can be obtained by controlling the degree of conversion of the hydrated alumina to ACH and by recycling and treating the acid after solid/liquid separation. The purified products find use in the specialty ceramics field, as catalyst supports, as adsorbents, in electronic components, in prosthetic devices or other applications in which alumina of controlled degrees of purity offers an advantage.

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: Disclosed is a process for dissolving halogen in a bath having an aluminum sulfate/sulfuric acid ratio in the range of about 0.75 to 1.0. The process is useful in extracting fluorine in high yield from spent cell linings recovered from an electrolytic reduction cell for the production of aluminum.

Abstract: A method is disclosed for the recovery of iron, aluminum and titanium from coal ash. The method comprises magnetically extracting magnetite from the ash, leaching the ash with a solution of a mineral acid, precipitating and removing titanium and iron hydroxides from the leach solution by adding thereto a solution of a strong base, and precipitating and removing aluminum hydroxide by contacting the remaining solution with carbon dioxide or aluminum hydroxide seeding.

Abstract: A process is described for the formation of high purity alumina from aluminas such as Bayer Process alumina trihydrate (gibbsite) which contain both acid-soluble and -insoluble impurities, notably soda and silica. The solid hydrated alumina is reacted with a stoichiometric quantity of concentrated HCl to form a reaction product comprising of dissolved aluminum chloride and solid aluminum chloride hexahydrate (ACH). The acid and/or aluminum chloride concentration of the solution is then adjusted (as by water addition) to dissolve the solid ACH and form a solution at or near saturation in aluminum chloride, but with the remaining solid materials undissolved. The solution is then subjected to solid/liquid separation to eliminate the insoluble impurities, such as silica.

Abstract: Mercury can be recovered from nitric acid-containing fluids by reacting the fluid with aluminum metal to produce mercury metal, and then quenching the reactivity of the nitric acid prior to nitration of the mercury metal.