Abstract: Phosphate rock, including low grade phosphate ore, is treated to recover phosphoric acid and other valuable products by a series of steps including contacting phosphate ore with a weak phosphoric acid to form a suspension of at least a portion of the slimes contained in the ore so that the slimes can be separated from the ore, and separating the slimes to provide a deslimed phosphate ore. Deslimed phosphate rock is solubilized with phosphoric acid to convert at least a portion of the calcium contained in the rock and form a solution of monocalcium phosphate and phosphoric acid. After removal of solids, this solution can be treated with sulfuric acid in a gypsum crystallizer to form gypsum and the phosphoric acid product wherein filterable gypsum crystals are obtained by maintaining a total SO.sub.3 content of 1.5-4 wt. % in a first crystallizer and neutralizing the SO.sub.3 in a second crystallizer.

Abstract: A method of treating final products from a flue gas desulfurization. The flue gas desulfurization is carried out by the absorption of sulfur oxide in a spray dryer with a suspension which contains lime, or in a reactor with a dry, fine-grained, absorbent which contains lime. Prior to desulfurization, the fly ash carried along by the flue gas which is to be desulfurized is separated entirely, partially, or not at all from the flue gas, and the final products from the flue gas desulfurization, prior to any further treatment thereof, amount to 1-99% by weight, preferably 1-70% by weight, of fly ash, and 1-99% by weight, preferably 30-99% by weight, of the sum of the desulfurization products, preferably calcium sulfite hemihydrate, and/or calcium sulfite, and/or calcium sulfate dyhydrate, and/or calcium sulfate hemihydrate, and/or calcium sulfate, as well as residue of the absorbent. The reduction of the amount of calcium sulfite is implemented by a dry oxidation with air.

Abstract: A process for the removal of sulfur oxides from two gas streams containing the same. One gas stream is introduced into a spray dryer zone and contacted with a finely dispersed spray of an aqueous medium containing an absorbent for sulfur oxides. The aqueous medium is introduced at a controlled rate so as to provide water to the gas in an amount to produce a cooled product gas having a temperature at least 7.degree. C. above its adiabatic saturation temperature and from about 125-300% of the stoichiometric amount of absorbent required to react with the sulfur oxides to be removed from the gas stream. The effluent from the spray dryer zone comprises a gas stream of reduced sulfur oxide content and contains entrained dry particulate reaction products including unreacted absorbent. This gas stream is then introduced into a particulate removal zone from which is withdrawn a gas stream substantially free of particles and having a reduced sulfur oxide content.

Abstract: A rapid, low temperature process for solubilizing phosphate rocks having high content of foreign matter or a low phosphorus content to obtain: (a) a slow release fertilizer of the NP type; (b) phosphoric acid of high concentration plus MAP; and (c) DAP.

Abstract: In the process for the production of synthetic anhydrite and pure hydrofluoric acid, a reaction is initiated using fluorspar with a mixture containing sulphuric acid, oleum and the reflux of the acidic scrubbing. The aim is to produce synthetic anhydrite which contains only the desired small proportion of CaF.sub.2, while the free H.sub.2 SO.sub.4 is completely neutralized, but other desirable accelerators are still retained. The reaction is so arranged that fluorosulphonic acid does not enter the reactor at all or only in minute quantity and the new formation of fluorosulphonic acid is effectively repressed. For this end, the components of CaF.sub.2 and acid mixture are fed into the reactor at an elevated temperature and the reactor intake is so heated, whereby the reaction is initiated at 100.degree. C. and thus new formation of fluorosulphonic acid is arrested. The exhaust gases from the reactor are hot-dried in a first stage and the dust is expelled, before the material is cooled in the subsequent stages.

Abstract: The disclosure relates to a process for after-treating extraction residues, termed raffinates, originating from the extractive decontamination of crude phosphoric acid. To this end, the disclosure provides for the raffinates to be converted to two separate solid matter fractions of differant chemical composition by admixing the raffinates with a calcium compound so as to establish a pH-value of 1.2 up to 2.5. Next, the resulting precipitate consisting essentially of gypsum is filtered off as a first solid matter fraction, and washed with water. The resulting filtrate and the wash water are made into a mixture and predetermined proportions of calcium compound are added so as to obtain, after complete reaction, a fully reacted filter cake with a pH-value of 9 up to 12, the resulting suspension being filtered off at a pH-value of 6 to 8. The filter cake consisting essentially of calcium phosphate is separated as the second solid matter fraction, and allowed to react completely.

Abstract: An improved double alkali process is disclosed which is useful for the removal of sulfur dioxide from gas streams, especially waste gas streams derived from coal-fired plants which also contain entrained fine particles of ash which contain alkali, which process comprises leaching soluble alkali from said entrained fine particles to establish an aqueous alkali scrubbing solution, scrubbing the resulting gas stream with said scrubbing solution, which circulates between said leaching and scrubbing steps, followed by bleeding off a portion of the resulting scrubber effluent to a regeneration system wherein the alkali scrubbing solution is regenerated.

Abstract: A process for the improved filterability of wet process phosphoric acid which comprises maintaining the ratio of ferric ion to ferrous ion in the wet process phosphoric acid above about 1.0 when the total iron concentration of the product wet process phosphoric acid is in the range of from about 0.5% Fe to about 0.9% Fe. The ratio of ferric ion to ferrous ion may be controlled by controlling the temperature in the final stage of a multi-stage calcining process, addition of iron in the form of a compound which yields ferric ion upon dissolution, the oxidation of the iron in the wet process phosphoric acid, or a combination of the above.

Abstract: In preparing wet process phosphoric acid by decomposing a phosphate rock containing uranium with sulfuric acid and phosphoric acid on condition that hemihydrate gypsum is formed in an acid solution either at the stage of decomposing the phosphate rock or subsequently, uranium contained in the phosphate rock can almost entirely be retained in the obtained phosphoric acid solution by forming the hemihydrate gypsum in the presence of an oxidizing agent, such as a soluble chlorate, hydrogen peroxide or oxygen gas, in the acid solution in a quantity sufficient to render the entire uranium dissolved in the acid solution hexavalent because hemihydrate gypsum adsorbs almost exclusively tetravalent ions of uranium. The uranium is then recovered.

Abstract: A wet process for producing phosphoric acid and phosphohemihydrate by acidulation of phosphate rock. A strong phosphoric acid is obtained with concomitant production of an improved calcium sulfate that is extremely low in radioactivity by operation in Region II for shorter time so as to produce small sized hemihydrate particles, then hydration of a substantial proportion but less than all of the hemihydrate to coarse gypsum substantially free of radioactivity in a dilute acidic aqueous slurry at a temperature and P.sub.2 O.sub.5 concentration selected so as to be within Region I of FIG. 1 and having a substantial weight proportion of coarser gypsum particles that are substantially free of radioactivity.

Abstract: A process for producing dry flue gas gypsum substantially free of hemihydrate and anhydrous calcium sulfate comprises drying wet flue gas gypsum, typically having a free water content of about 4-12% by weight, in direct contact with a partial stream withdrawn from a primary stream of a dry dedusted flue gas. Flue gas gypsum produced in a wet desulfuration stage is fed to contact the partial stream and is separated from this partial stream and removed as dried flue gas gypsum. Remaining superfine flue gas gypsum is then fed to the intake side, or to the delivery side of a booster blower arranged upstream of the flue gas desulfuration device along with the partial flue gas stream discharged from the drying stage, and the superfine particulate flue gas gypsum is conducted from the booster blower into the flue gas desulfurizing device to serve as seed crystals for additional production of gypsum therein.

Abstract: A process for reducing radioactive contamination of phosphogypsum. Phosphogypsum containing radioactive material is calcined to form hemihydrate crystals carrying the radioactive contaminants, and a portion of the crystals is converted to substantially radiation-free gypsum crystals which are readily separated from the hemihydrate crystal relics containing substantially all of the radioactive contamination.

Abstract: A process for desulfurizing an exhaust gas which comprises desulfurizing an exhaust gas containing SO.sub.2 by bringing it into contact with a slurry containing calcium compounds and aluminum compounds, characterized in that the concentration of the dissolved aluminum ion in said slurry is detected and a manganese compound is supplied into said slurry in such a manner that the ratio of the concentration of manganese (including both solid and liquid) to said concentration of the dissolved aluminum ion may be maintained in a molar ratio of less than 1 in said slurry.

Abstract: A dual alkali process and an apparatus for the removal of sulfur oxides from a gas stream containing such sulfur oxides, is disclosed.

Abstract: A flue gas desulfurization method for efficiently removing sulfur oxides from a gas stream with an aqueous sodium sulfite- and sodium bisulfite-containing absorption solution, in which absorber effluent solution at a pH of from 5.8 to 6.6 and having an active sodium concentration of from 0.5 M to 0.9 M is regenerated with sufficient ground limestone to yield a treated solution with a higher pH of from 6.3 to 7.0 and whose bisulfite concentration is reduced by from 35 to 70%.

Abstract: A phosphate rock slurry, which may be used in the production of wet process phosphoric acid, is provided by wet grinding the rock with partially neutralized, acid water.In one aspect, wet process phosphoric acid is made by advantageously recycling mineral acid waste water effluent of the process. All or a portion of the effluent can be at least partially neutralized with neutralizing agent, e.g., by contact with the base-forming constituents of phosphate rock or extraneous neutralizing agent, e.g., preferably ammonia, to provide a mixture which is wet ground to produce a processable slurry. In one particularly preferred aspect, all of the acid water is at least partially neutralized with phosphate rock and a portion of this acid water is advantageously further neutralized with an extraneous neutralizing agent. The slurry is provided by such neutralization at a pH compatible with the milling, e.g., grinding, media utilized.

Abstract: Phosphate rock, including low grade phosphate ore, is treated to recover phosphoric acid and other valuable products by a series of steps including contacting phosphate ore with a weak phosphoric acid to form a suspension of at least a portion of the slimes contained in the ore so that the slimes can be separated from the ore, and separating the slimes to provide a deslimed phosphate ore. Deslimed phosphate rock is solubilized with phosphoric acid to convert at least a portion of the calcium contained in the rock and form a solution of monocalcium phosphate and phosphoric acid. After removal of solids, this solution can be treated with sulfuric acid in a gypsum crystallizer to form gypsum and the phosphoric acid product wherein filterable gypsum crystals are obtained by maintaining a total SO.sub.3 content of 1.5-4 wt. % in a first crystallizer and neutralizing the SO.sub.3 in a second crystallizer.

Abstract: Foam generated during the digestion of phosphate rock is removed from the slurry either by overflow, mechanical sweeps, or by vacuum from strategically located nozzles connected to vacuum lines. The foam, after liquefaction, is returned to the filter where it results in improved filtration and return of soluble P.sub.2 O.sub.5.

Abstract: A double alkali process employs limestone to regenerate spent sodium sulfite and then recirculates the unreacted limestone to attain a high internal stoichiometry and high limestone utilization. The regeneration of the sodium sulfite is carried out in a plurality of reactors and separation of the slurry from the reactors is carried out in at least one hydroclone. The at least one hydroclone has two primary functions: one to promote the reaction of Na.sub.2 SO.sub.3, which reduces the reactor volumes and reduces the temperature of conversion; and two to reduce the concentration of the limestone overflow, thus increasing the limestone utilization.

Abstract: Aluminum fluorophosphate can be produced by the aging of phosphoric acid containing fluorine and aluminum, preferably phosphoric acid analyzing in the range of about 15-45 weight percent P.sub.2 O.sub.5, 2-4% Al.sub.2 O.sub.3 and 1-2% fluorine. One process involves digestion of phosphate ore matrix in recycled phosphoric acid, filtration of the insoluble residue, precipitation and filtration of gypsum, and aging of the product acid to precipitate the aluminum impurity as an aluminum fluorophosphate compound. The aluminum fluorophosphate can be decomposed (as by heating at about 195.degree. C.) to produce HF and aluminum phosphate.

Abstract: A method of recovering molybdenum oxide by oxidation of a molybdenum sulfide concentrate contaminated with impurities wherein the concentrate in an average particle size in the range of 20 to 90 microns is suspended to form an aqueous suspension which is oxidized at elevated temperature and an elevated oxygen partial pressure in an autoclave. The suspension withdrawn from the autoclave is subjected to filtration to remove the molybdenum oxide from the primary filtrate containing sulfuric acid and this filtrate is neutralized with lime to form calcium sulfate which is then removed from the suspension to provide a second filtrate. According to the invention, only this second filtrate is recirculated at a rate such that the suspension density in the oxidation stage is between 100 to 150 g of solids per liter and this suspension density is maintained in the oxidation stage by the recirculation.

Abstract: A process for producing low aluminum content phosphoric acid from high aluminum matrix comprises digesting the matrix in phosphoric acid; adding a flocculant to consolidate gelatinous or fine undigested solids; separating the flocculated solids from the mother liquid comprising monocalcium phosphate; acidifying the monocalcium phosphate with sulfuric acid to precipitate solid calcium sulfate and simultaneously adding at least one sodium or potassium compound or both to co-precipitate some of the soluble fluoride with the gypsum; separating the product phosphoric acid from the precipitated solids; recycling part of the lower fluoride content phosphoric acid back to the digestion step; and, aging the remainder of the product phosphoric acid until a precipitate of aluminum fluorophosphate forms and separating the precipitate to produce a low aluminum content phosphoric acid. Additional fluorine (e.g., a fluoride compound) can be added to accellerate formation of the aluminum fluorophosphate.

Abstract: A process for removing sulfur dioxide from waste gas is provided. The gas is first contacted with an alkaline scrubbing liquor consisting essentially of a sorbent salt in which the cation is sodium or potassium, and one of the anions is borate. The clean gas is vented and the sorbent liquor regenerated for recycle by treatment with lime to precipitate insoluble calcium-sulfur compounds for disposal and regenerate the alkalinity of the scrubbing liquor.

Abstract: A wet process for stack gas treatment wherein the stack gas is scrubbed with a suspension containing calcium hydroxide and/or calcium carbonate to remove sulfur oxides from the gas, characterized in that(1) air or oxygen-containing gas is supplied to the gas scrubber so as to oxidize at least 18% of the sulfur oxides absorbed by the scrub liquid to gypsum, and then part of the gypsum from the gypsum-containing scrub liquid partly taken out is recycled to the scrubber, or(2) part or whole of the scrub liquid is taken out from the scrubber into an oxidizer, where it is oxidized with the supply of air or oxygen-containing gas, and, after the oxidation, part of the scrub liquid from the oxidizer is recycled to the scrubber, whereby at least 18% of the sulfur oxides absorbed from the gas by the scrub liquid is oxidized to gypsum.

Abstract: A process for the removal of SO.sub.X from a gaseous stream is disclosed in which the gaseous stream is contacted (a) with a particulate mixture of a reactive calcium-containing material and activated carbon, or (b) particulate activated carbon, the particulate activated carbon subsequently being mixed with a reactive calcium-containing material.

Abstract: In a process of preparing sinter magnesia from magnesium oxide in a sintering kiln evolving flue gases during sintering, the flue gases are washed before their removal from the kiln to the atmosphere with a portion of the magnesium chloride slurry formed during the preparation of the magnesium oxide and the magnesium chloride slurry used for washing the flue gases is recycled to the slurry wherefrom the magnesium sol for making the magnesium oxide is derived.

Abstract: Phosphate rock is digested with H.sub.2 SO.sub.4 into phosphoric acid and gypsum, the latter is separated off, washed and converted into anhydrite. After this first wash the gypsum is divided into a minor portion of fine crystals, which is discharged, and into a major portion of coarse crystals, which is subjected to a second wash, thereafter recrystallized into anhydrite by means of concentrated H.sub.2 SO.sub.4, the anhydrite being separated and washed and the recrystallization liquor returned to the digestion zone. The washing liquor obtained from the anhydrite wash is used for the second gypsum wash, the washing liquor obtained from this second wash is, together with water, used for the first gypsum wash, whereas the washing liquor obtained in this first wash is returned to the digestion zone. In this way practically all gypsum formed can be converted into anhydrite, while substantially all water can be functionally used without dilution of the H.sub.3 PO.sub.4 -product.

Abstract: A process for the whitening of phosphogypsum comprising treating a phosphogypsum in aqueous suspension with an amount of ozone equal to at least 150 parts by weight per million parts by weight of phosphogypsum calculated as Ca SO.sub.4.2H.sub.2 O, the pH of the aqueous suspension being lower than or equal to 3, to yield a whiteness grade of phosphogypsum higher than 75, according to French Standard NF Q 03-038.

Abstract: Disclosed is a method for treating substantially homogeneous monocalcium phosphate (MCP) solutions that contain undesirable amounts of radium which comprises centrifuging these MCP solutions sufficiently to separate at least a portion of the radium from the solution. Such treated MCP solutions may then be reacted with sulfuric acid to simultaneously produce a phosphoric acid solution and a calcium sulfate precipitate such as gypsum having low levels of radium content.

Abstract: An improved process for desulfurizing combustion exhaust gases of mainly coal containing sulfur oxides, HF and dust containing Al is provided, which process consists of four steps; a first step of contacting the gases with calcium carbonate or hydroxide in the form of slurry to convert the sulfur oxides into CaSO.sub.3 ; a second step of contacting O.sub.2 with the resulting slurry to convert CaSO.sub.3 into CaSO.sub.4 ; a third step of separating CaSO.sub.4 and mother liquor from the resulting slurry; and a fourth step of preparing a slurry of calcium carbonate or hydroxide to be employed in the first step, from the mother liquor, the pHs of the slurry and the mother liquor in the first and fourth steps being adjusted to 5 or higher by adding alkali such as sodium carbonate.According to the present process, it is possible to prevent hindrance of HF and Al contained in dust to the reaction of SO.sub.2 -absorbent (CaCO.sub.3 or Ca[OH].sub.2) with SO.sub.

Abstract: Sulfur dioxide is scrubbed from boiler flue gases in a double-loop alkali scrubber, one a quencher loop and the other an absorption loop. The reagent flow of the two loops is isolated so that none of the reagent from the quencher loop is cycled to the absorber loop and a portion of the make-up water for the quencher loop is received from the absorber loop. By controlling recycled water from a dewatering system and selective utilization of high and low solids streams from the absorber system, the quencher slurry concentration may be controlled and the requirement for new make-up water reduced. The two loop process isolates the main absorber system including the demisters, which are prone to scaling and corrosion, from the evaporative quencher portion of the process. All the recycled water is returned to the evaporative quencher loop and none to the loop controlling the demisters and the primary absorber sections. However, under varying SO.sub.

Abstract: The air cooling of exothermic reaction vessels is improved by providing a cooling air recirculation loop wherein substantial amounts of the cooling air are recycled through the system with but a small fraction thereof being discharged to ambient, and after the condensable/soluble off-gases are depleted therefrom and with addition thereto of but minor amounts of additional feed air. Such technique is well suited for controlling the temperature of the digestion of phosphate rock with sulfuric acid, in the known wet-process for the production of phosphoric acid.

Abstract: An improved method for the production of wet process phosphoric acid wherein the addition of relatively small amounts of gelatin to the reaction system substantially increases the filtration rate of the calcium sulphate crystals without adversely affecting the quality of the acid.

Abstract: An SO.sub.2 flue gas scrubbing system wherein a calcium compound is dissolved in water and recirculated in contact with the flue gases. Calcium sulfite and sulfate formed in this process are also recirculated. A stream of the slurry passing to waste is separated based on the rate of settling of the constituents so that calcium sulfate and undissolved calcium compound is returned to the recirculating system with the calcium sulfite being sent to waste.

Abstract: A method according to this invention is used for washing waste phosphogypsum produced at decomposition of a mineral phosphoric raw material with sulphuric acid, wherein the said washing is carried on in countercurrent on a multi-zone filter; to the last zone of this filter there is supplied water while filter washings with highest concentration of the component being washed-off are returned to the decomposition stage. The essence of this method consists in that to the washing liquids there is introduced sulphuric acid solution of a concentration of sulphuric acid ranging within the limits from 20 up to 98 percent by weight of sulphuric acid in the amount of 1 to 30 percent of sulphuric acid amount used for decomposition of a phosphoric raw material.

Abstract: Disclosed is a process for refining a magnesium and nickel containing ore, comprising the steps of grinding the ore; preparing a slurry of the ground ore in sulfuric acid containing less than ten percent of water; adding water to the acid-ore slurry in an amount which is effective to initiate a sulfation reaction; allowing the sulfation reaction to continue, utilizing the heat of the sulfation reaction to heat the acid-ore slurry, whereby water-soluble metal sulfates and insoluble residue are formed; leaching the sulfation product with water to extract the water-soluble metal sulfates in solution; separating the metal sulfates solution from the insoluble residue; precipitating from the solution metals other than Mg as hydroxides; separating the solution from the metal hydroxide precipitate; concentrating the solution sufficiently to precipitate CaSO.sub.4 ; separating the concentrated solution from the precipitate; recovering dehydrated MgSO.sub.

Abstract: The addition of an excess of asbestos tailings in the course of the extraction of magnesium from asbestos tailings by digestion with an acid greatly facilitates the elimination of silica and other impurities by filtration of the resulting reaction mixture. The improvement reduces the filtration time and the filtration leaves a cake which is much easier to dispose.

Abstract: A process for recovering aluminum from clays associated with coal or bauxite containing iron, siliceous material and titanium which comprises: (a) chlorinating the clay or bauxite in an oxidizing atmosphere to selectively chlorinate and vaporize iron chloride from the remaining chlorides, (b) chlorinating the residue from step (a) in a reducing atmosphere or carbon monoxide and vaporizing the chlorides of aluminum, silicon, titanium, and the residual iron, (c) separating and recovering the formed vaporized chlorides by selective condensation. Silicon tetrachloride may be added to step (b) to suppress the chlorination of silicon. If the clay contains alkali or alkaline earth metals, then the residue of step (b) is treated with sulfuric acid to convert the soluble chlorides, e.g., gypsum, to sulfates and to regenerate a chloridizing and binder solution for pelletizing the clay or bauxite.

Abstract: Disclosed is a process for producing a calcium sulfate product containing low amounts of radium comprising the steps of:(a) adding at least one sequestering agent to a substantially homogeneous radium-containing monocalcium phosphate (MCP) solution, the amount of the sequestering agent added being at least the stoichiometric amount necessary to complex with the radium in the MCP solution;(b) reacting the treated MCP solution with H.sub.2 SO.sub.4 to form a monocalcium phosphate/phosphoric acid solution, to precipitate a first calcium sulfate product, and to precipitate at least a portion of the radium, the amount of said H.sub.2 SO.sub.4 being up to about 50% of the stoichiometric amount necessary to react with the total CA.sup.++ present in the MCP solution;(c) separating the monocalcium phosphate/phosphoric acid solution from the radium-containing calcium sulfate precipitate;(d) then reacting the monocalcium phosphate/phosphoric acid solution with H.sub.2 SO.sub.

Abstract: Disclosed is a process for recovering chromium, vanadium, molybdenum, and tungsten from secondary resources such as alloy scrap comprising a refractory metal and base metals such as cobalt, nickel, iron, and copper. The scrap is calcined with sodium carbonate in air to convert the refractory metal values to MoO.sub.4.sup..dbd., VO.sub.4.sup..tbd., WO.sub.4.sup..dbd., and CrO.sub.4.sup..dbd. and the base metals to water insoluble oxides. A leach of the calcined materials produces a pregnant liquor rich in refractory metals which, after separation of the vanadium, molybdenum and tungsten values, is treated with CO, CHOO.sup.-, CH.sub.3 OH, or HCHO to reduce Cr.sup.+6 to Cr.sup.+3. The carbonate and bicarbonate salts produced as a byproduct of the reduction are recycled to the calcination stage.As a result of the V, W, and Mo partition, a mixed solid comprising CaO.nV.sub.2 O.sub.5, CaMoO.sub.4, and CaWO.sub.4 is produced.

Abstract: Highly pure lithium chloride suitable for use in production of lithium metal by electrolysis is obtained directly from impure natural or other lithium chloride brines by an integrated process in which the brine is first concentrated by solar energy to a lithium chloride concentration of about 3%, after which the brine is treated with lime and calcium chloride to convert such impurities as boron, magnesium and sulfate to a calcium borate hydrate, magnesium hydroxide and calcium sulfate dihydrate, respectively, and separating the precipitated calcium sulfate dihydrate from the brine. The brine is then further concentrated to 40% or more lithium chloride by means of solar or other energy, during which concentration step the calcium borate hydrate, magnesium hydroxide and calcium sulfate dihydrate precipitate from the brine. The highly concentrated brine is subjected to evaporation at a temperature above 101.degree. C. to produce anhydrous lithium chloride which is further heated to a temperature of 200.degree.

Abstract: A process is described for the comminution of a solid material in the presence of a saturated solution of the solid in a liquid in which the solid has a solubility greater than 1%, and also in the presence of an additive dissolved in the saturated solution which can at least partially inhibit regrowth at crystal surfaces of the solid material. The process is of particular interest for the comminution of water-soluble salts in the presence of their saturated aqueous solutions and may be employed to make, inter alia, improved slurry explosives and fluid fertilizer compositions.

Abstract: A continuous process for removing sulfate ions from a substantially water-insoluble organic phase containing phosphoric acid and sulfuric acid is described. The organic phase is treated countercurrently in a first zone with an aqueous solution originating in a third contact zone, the organic phase issuing from the first zone is treated in a second zone with an aqueous solution containing barium ions, then the resultant organic phase is treated in a third zone with water. The aqueous phase exiting from the second zone is separated from the BaSO.sub.4 precipitate, recharged with barium and recycled into the second contact zone. The phosphoric acid thus obtained is suitable for use in human foods and beverages.

Abstract: Boron, as well as magnesium and sulfate impurities, are removed from or at least substantially reduced in a lithium containing brine to minimize lithium losses on further concentration of the brine by adding to the brine an aqueous slurry of slaked lime and a solution of calcium chloride to form a calcium borate hydrate, magnesium hydroxide and calcium sulfate dihydrate, the last named compound being precipitated and separated from the brine. On further concentration of the brine, calcium boron hydrate and magnesium hydroxide precipitate and they are also removed from the brine. In an alternate procedure, the pH of the brine is adjusted to 8.0-8.4 by addition of hydrochloric acid to form a calcium borate hydrate, which on further evaporation, is also separated from the brine. The brine is then concentrated further to recover lithium values.

Abstract: The present invention relates to a process for the recovery of magnesium oxide of high purity in which the magnesium oxide is obtained by thermal decomposition of a magnesium chloride brine previously purified. The magnesium chloride brine itself is obtained by decomposition of impure starting material with hydrochloric acid and purified before the thermal decomposition. In doing so the brine obtained by the decomposition is first concentrated and the separation of the impurities is effected only then. Calcium is separated in form of calcium sulfate. Optionally calcium sulfate and other impurities may be separated together.

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: Sulfur dioxide is scrubbed from boiler flue gases in a double-loop alkali scrubber, one a quencher loop and the other an absorption loop. Preferably, the reagent flow of the two loops is isolated so that none of the reagent from the quencher loop is cycled to the absorber loop. A substantial portion of the make-up water for the quencher loop is received from the absorber loop and solids are concentrated in a dewatering system which includes a hydroclone.

Abstract: A process for removing sulfur oxides from exhaust gas formed by combustion particularly exhaust gas from an electricity-generating power plant. The exhaust gas flows through a reaction zone which operates like a spray dryer. A purifying liquor consisting of an aqueous solution of sodium carbonate and/or sodium bicarbonate is sprayed into the reaction zone, in which the heat content of the exhaust gases causes virtually all of the water content of the purifying liquor to be evaporated. The exhaust gas is subsequently passed through a filter. Anhydrous solids are withdrawn from the reaction zone and the filter and contain at least 75% of sodium sulfite, sodium sulfate and sodium chloride and are processed to form sodium carbonate. To that end the solids are dissolved and sulfite is oxidized to form sulfate so that a solution that contains sodium sulfate and sodium chloride is formed.

Abstract: Improved methods are provided for the efficient and economic removal of sulfur dioxide from gases which comprise contacting the gas with neutralizing values obtained from Type S hydrated lime, i.e. calcined dolomite slaked with water under elevated temperature and pressure. The Type S hydrated dolomitic lime may be used in conjunction with a wet scrubber to provide base and neutralizing magnesium values, in a spray dryer or dry scrubber, or directly introduced into the boiler. The use of Type S hydrated dolomitic lime greatly enhances the efficiency of sulfur dioxide removal, providing for enhanced utilization of base values and more rapid rate of reaction.

Abstract: A method of removing sulfur dioxide from combustion exhaust gas containing sulfur dioxide by contacting the exhaust gas with an aqueous solution containing at least one organic acid salt expressed by the formulaRCOOM(wherein R represents H, CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7, and M represents an alkali metal or NH.sub.4) to efficiently dissolve sulfur dioxide contained in the gas in the form of a sulfite in the aqueous solution by reacting the sulfur dioxide with the salt. The resultant solution which dissolves the sulfite may be contacted with a calcium compound for producing calcium sulfite by reaction of the sulfite with the calcium compound thereby effectively removing the sulfur dioxide in the form of calcium sulfite from the combustion exhaust gas.