Abstract: A process for cleaning flue gases containing ash and sulfur dioxide produced by burning sulfur-containing coal in the combustion chamber of a circulating fluidized-bed firing system includes delivering a particulate SO2 sorbent into the combustion chamber. A mixture including portions of the ash, the reaction product produced in the reaction of the SO2 sorbent with the sulfur dioxide, and unreacted SO2 sorbent is fed from the combustion chamber to a mixing unit. In the mixing unit, water or an aqueous sodium-containing solution is mixed with this mixture and the unreacted SO2 sorbent is converted into a hydration product (for example Ca(OH)2) at a reaction temperature of 60° to 100° and at atmospheric pressure. The ash, the reaction product, and the hydration product is returned from the mixing unit into the combustion chamber, and the hydration product is reactivated to an SO2 sorbent at a combustion-chamber temperature of 700° to 950° C.

Abstract: A method and system for desulfurizing flue gas in which desulfurization is effected by bringing absorbent slurry containing limestone into contact with flue gas. The method classifies absorbent slurry extracted from a desulfurization absorber, returns a fine-side fluid to the desulfurization absorber, and sends a coarse-side fluid to a solid-liquid separator. Supplied limestone powder is mixed to yield limestone slurry by a solid-liquid mixer, and the limestone slurry is classified, sending the small-particle fluid component thereof to the desulfurization absorber, and sending the large-particle fluid component thereof to a limestone fine grinder. And, limestone contained in the large-particle fluid component is finely ground by the limestone fine grinder and the finely ground limestone is sent to the desulfurization absorber.

Abstract: A method of producing calcium sulfate &agr;-hemihydrate is disclosed, including the steps of exposing a mixture including a calcium sulfate form selected from the group consisting of calcium sulfate dihydrate, calcium sulfate &bgr;-hemihydrate, water-soluble calcium sulfate anhydrite, and mixtures thereof, water, and a crystallization catalyst, to microwave radiation to produce calcium sulfate &agr;-hemihydrate; and separating at least a portion of the calcium sulfate &agr;-hemihydrate to provide a solid comprising calcium sulfate &agr;-hemihydrate and a filtrate and/or remainder that can be recycled to provide at least one of a calcium sulfate form, water, a crystallization catalyst, a crystal habit modifier, and a surfactant for use in production of additional &agr;-hemihydrate.

Abstract: A method and apparatus for recovering calcium sulfate di-hydrate (gypsum) from a precipitation reaction between cement kiln dust and commercial, spent or waste grade sulfuric acid solution. The gypsum recovered from this process acts as a necessary functional additive for use in the production of hydraulic Portland cement. The invention advantageously provides for a method of producing a fertilizer as a byproduct of the gypsum production process. The invention also provides a method of producing Portland cement using the gypsum derived from the cement kiln dust.

Abstract: The invention relates to a method for the preparation of lactic acid and calcium sulphate, in which (a) an aqueous solution that contains lactate is reacted with sulphuric acid at a temperature that is essentially higher than the transition temperature of calcium sulphate dihydrate (CaSO4.2H2O), with the formation of a mixture that contains calcium sulphate hemihydrate and lactic acid, (b) the mixture from step (a) is subjected to at least one recrystallisation step at a temperature that is essentially lower than the transition temperature of calcium sulphate dihydrate, with the formation of a precipitate of calcium sulphate dihydrate and an aqueous solution of lactic acid, and (c) the precipitate of calcium sulphate dihydrate is separated off from the aqueous solution of lactic acid.

Abstract: A method and apparatus for wet flue gas desulfurization in a two-circuit washer having two washers for an absorption agent based on suspensions containing calcium compounds, a sump for supplying the absorption agent to the first washer, and a container for at least partial recovery of the absorption agent from the second washer. The absorption agent, while being returned to the container, is actively brought into contact with oxygen to oxidize calcium sulfite to calcium sulfate. The return line has apparatus for actively blowing in oxygen with only a relatively slight overpressure necessary to blow the air into the absorption agent. The absorption agent to be oxidized is already moving because the difference in elevation along the return line from the recovery apparatus to the container, whereby the absorption agent then arrives more or less completely oxidized.

Abstract: A synthesized compound that is able to neutralize oxidizing agents such as nitrates from water systems, from ground surfaces and other sites. When contaminated water is passed through the synthesized compounds or when the synthesized compounds are applied to contaminated surfaces (such as feedlots), the nitrates are reduced to elemental nitrogen gas and calcium sulfates. The harmless nitrogen gas is vented into the atmosphere while the insoluble sulfate compound is collected and available to use as a soil amendment or other uses.

Abstract: Fluorgyp is converted to calcium sulfate by reacting sulfuric acid in the fluorgyp with calcium carbonate having a small particle size. The resulting product is useful as a set retarding agent for cement.

Abstract: A chemical process for the purification of CaSO4 utilizes the ability of an aqueous solution of a chelating agent to selectively dissolve CaSO4, in that the initial extraction can be carried out at certain pH and CaSO4 can be recovered by titration to a different pH (usually a lower pH) following a mechanical treatment, such as centrifugation or filtration, to separate the aqueous chelate solution from insoluble material. Also claimed are an apparatus and the use of chelating agents therefor.

Abstract: A method of producing calcium sulfate &agr;-hemihydrate, including the steps of exposing a mixture including a calcium sulfate form selected from the group consisting of calcium sulfate dihydrate, calcium sulfate &bgr;-hemihydrate, water-soluble calcium sulfate anhydrite, and mixtures thereof, water, and a crystallization catalyst, to microwave radiation to produce calcium sulfate &agr;-hemihydrate; and separating at least a portion of the calcium sulfate &agr;-hemihydrate to provide a solid comprising calcium sulfate &agr;-hemihydrate and a remainder, is disclosed.

Abstract: A method of producing useful products, for example, gypsum and sugar products, from pulp and paper industry wastes.

Abstract: Sulfur dioxide is removed from a gaseous stream using an aqueous scrubbing slurry of magnesium and calcium scrubbing components where the process is carried out where lime and magnesium hydroxide are blended to give a molar ratio of between about 1.0 to 2.0, so as to provide a solids content in the aqueous scrubbing slurry of between about 12 to 20 percent, which includes about 10 to 15 percent suspended solids and 2 to 5 percent dissolved solids, and a dissolved sulfite content of about 13,000 to 20,000 ppm and a pH of between about 5.8-6.0.

Abstract: A method of making a cesium salt is described and involves reacting a cesium sulfate containing solution with lime to form 1) a solution containing at least cesium hydroxide and 2) a residue comprising calcium sulfate. The method further involves removing the residue from the solution and converting the cesium hydroxide that is present in the solution to at least one type of cesium salt. The present invention further relates to uses of the cesium salt as well as methods of making cesium hydroxide using lime. Also, methods of making alkali metal salts and alkali metal hydroxides are also described.

Abstract: The present invention relates to the improvement of a replenishment method of a magnesium-based compound and to the improvement of a double decomposition method, which can be used in a magnesium hydroxide desulfurization method. In the improved replenishment method, the magnesium-based compound is supplemented with water and the ratio of Mg/H2O is adjusted to the total Mg/H2O in the desulfurization system. In the improved double decomposition method, a tank for use is provided with an inner cylinder which partitions the tank into an inner part and an outer part, but does not reach the bottom of the tank, and a part of the slurry drawn through the bottom of the tank is fed to the outer upper position in the tank.

Abstract: A system for the manufacture of cement clinker from cement raw meal in which the off-gases of the cement clinker production line not only undergo denitrification but also undergo desulfurization, so that even sulfur-rich raw materials and fuels can be employed without exceeding the prevailing pollutant emission limits. A substream of the oversize material (30) discharged from the mixing chamber (29) of the precalcination stage (16) as solid sorbent may be combined with the off-gas (22) and/or with a partial gas discharge (38) of the rotary kiln off-gas in order to convert the sulfur oxides contained in those off-gases to calcium sulfate (34), which is subsequently separated from the system off-gas.

Abstract: Invention relates to a method for the removal of sulfur from the leaching cycle of nickel processes such as leaching of nickel matte. According to the method, anolyte generated in nickel electrowinning is neutralized with the aid of a calcium-based neutralizing agents, wherein sulfur is removed from the leaching cycle as gypsum.

Abstract: A method for purifyiing flue gas derived form incinerators burning refuse, wood, or sludge, in which the flue gas is cooled in a spray drier. A dust remover removes the dust from the flue gas. The flue gas is filtered through a filter-bed adsorber having filtering surfaces and packed with an adsorbent containing calcium hydroxide. The filter-bed adsorber is cleaned at intervals for removing adsorbate from the filtering surfaces. An aqueous suspension is prepared from at least some of the adsorbate that is removed from the filtering surfaces, and the flue gas is brought into contact with the suspension in at least one location upstream of the filter-bed adsorber for further separation of contaminates. The aqueous suspension is supplied to the spray drier for improving the purification of the flue gas.

Abstract: A porous paste, especially a plaster paste or slurry for producing sandwich-type plasterboard, is made in a disk-shaped mixer having a rotor rotatable in a mixing chamber by introducing compressed air or other pressurizable gas through a wall or bottom segment directly into the chamber so that the incoming pressurized gas meets the mixture with a shearing action along the wall or bottom.

Abstract: A new process of preparing potassium sulfate fertilizer and other metal sulfates from the chlorides and other halides of these metals. The process utilizes the discovery that sulfur dioxide or trioxide, when introduced as a fluidizing medium into shallow beds of the halide salts at moderately elevated temperatures (1000° F.-1150° F.) in a counter current process results in the conversion of the metal halides into metal sulfates and the halide gas. The process is carried out in a series of true fluidized beds preferably but not necessarily arranged in a vertical configuration so that the solids flow downward due to the fluidized process and the sulfur dioxide or trioxide gases flow counter currently in an upward direction producing pure metal sulfates at the bottom and pure halide gas at the top.

Abstract: A process is provided for preparing ammonium metavanadate from the combustion ashes resulting from the combustion of petroleum fuels in a boiler by using the ammonium sulfate and vanadium components in the combustion ash. Water is added to the combustion ash to form a slurry. The solids are removed from the slurry. Ammonia and an oxidizing gas, such as air, oxygen or ozone, are added to the aqueous solution obtained from the slurry to oxidize the vanadium, thereby producing an aqueous solution containing ammonium metavanadate. The ammonium metavanadate is crystallized and recovered from the aqueous solution. Calcium hydroxide or calcium oxide is injected into the aqueous solution and reacts with the ammonium sulfate to produce gypsum and ammonia. This gypsum and ammonia containing solution is flowed down a packed column, where it is counter-currently contacted with air or steam which strips the ammonia out of the solution.

Abstract: There is provided a granular absorbent based on calcium sulfate that may be used for absorbing oil and water-based liquids. The absorbent includes calcium sulfate obtained from gypsum, waste gypsum from wallboard, waste gypsum separated from wallboard, synthetic gypsum and mixtures thereof. The granular absorbent is ground and screened to a particle size between 4 mesh and about 100 mesh. In another aspect of the invention, an effective amount of a binder such as a clay, lignin or starch is added to the calcium sulfate to assist the calcium sulfate to pelletize and form granules. The granules are sized and dried. The granular absorbents are effective in absorbing oil or water and are easily disposed of. There is also disclosed processes for making the granular absorbents.

Abstract: There is provided a soil amendment product of agglomerated or compacted calcined calcium sulfate. The soil amendment product is screened to a particle size between 6 mesh and about 100 mesh. In another aspect of the invention, an effective amount of a binder such as a clay, lignin or starch is added to the calcium sulfate to assist the calcium sulfate to pelletize. The pelletized calcium sulfate is sized and calcined. There is also disclosed processes for making the soil amendment products.

Abstract: A method of producing calcium sulfate with a flue gas scrubbing facility having a gas-liquid contactor that uses a calcium-based slurry to absorb sulfur dioxide from a flue gas containing acidic gases, wherein a byproduct containing calcium sulfite precipitate is produced that is accumulated in a reservoir, such as a pond, apart from the gas-liquid contactor. Such a facility is modified to produce calcium sulfate by installing an acidifier vessel and an oxidation receptacle in series between a source of the flue gas and the gas-liquid contactor. The flue gas containing the acidic gases is caused to flow through the acidifier vessel, into which the byproduct is delivered from the reservoir so that some of the acidic gases of the flue gas are absorbed by the byproduct and the pH of the byproduct is sufficiently lowered to allow the calcium sulfite precipitate to dissolve in the byproduct.

Abstract: CaS oxidation has CaS particles oxidized into CaSO4 completely as far as to the interior of the particle. The interior of an oxidation apparatus 1 is partially partitioned by a partition 22 to thereby form a first fluidized bed 20 on the inner side, a second fluidized bed 21 on the outer side and a space portion 23 thereabove. A heat exchanger 27 having a baffle plate is disposed on the inner side of the partition 22 and an in-bed heat exchanger 33 is disposed on the outer side of same. A desulfurizing product-containing fine powder 204 and coarse powder 205 and a mixture gas 206 of nitrogen, oxygen and steam are supplied into the second fluidized bed 21. Also, coal 200 and coal char 201 are supplied into the first fluidized bed 20 from below.

Abstract: After hydrogenation and desulfurization treatment of raw fuel in the desulfurization unit 1, the product is separated in the acidic gas separator 2 into fuel and a hydrogen sulfide-containing gas, and the hydrogen sulfide-containing gas is subjected to combustion together with air in the catalyst converter 3 thereby converting the hydrogen sulfide completely into sulfur dioxide to give a sulfur dioxide-containing gas, and this sulfur dioxide-containing gas is reacted with limestone powder and air in water in the oxidation and neutralization reactor 4, and the resulting slurry is dehydrated in the gypsum slurry solid/liquid separator 5 and then dried in the gypsum heater 6.

Abstract: There is provided a granular absorbent based on calcium sulfate that may be used for absorbing oil and water-based liquids. The absorbent includes calcium sulfate obtained from gypsum, waste gypsum from wallboard, waste gypsum separated from wallboard, synthetic gypsum and mixtures thereof. The granular absorbent is ground and screened to a particle size between 4 mesh and about 100 mesh. In another aspect of the invention, an effective amount of a binder such as a clay, lignin or starch is added to the calcium sulfate to assist the calcium sulfate to pelletize and form granules. The granules are sized and dried. The granular absorbents are effective in absorbing oil or water and are easily disposed of. There is also disclosed processes for making the granular absorbents.

Abstract: The invention relates to a method for the treatment of fluoboric electrolyte resulting from the processes of electro-extraction of metals such as copper and lead comprising a leaching stage with fluoboric acid, in order to recycle said fluoboric acid to be recirculated to said leaching stage devoid of impurities of metals such as Me=Fe, Zn, Ca, Mg, Cd, characterized in that it comprises the stages of: a) treating said fluoboric electrolyte comprising Cu(BF4)2 or Pb(BF4)2 with H2S in order to precipitate CuS or PbS respectively in accordance with the reactions Cu(BF4)2+H2S=>CuS+2HBF4  (1) Pb(BF4)2+H2S=>PbS+2HBF4  (2) thus obtaining a solution of HBF4 containing the fluoborates of said metals Me, said solution being separated, b) treating said Me fluoborates with H2SO4 in accordance with the reaction 2 Me(BF4)n+n H2SO4=>Me(SO4)n+2n HBF4  (3) (where Me=Fe, Zn, Ca, Mg, Cd) it being possible for said sulp

Abstract: A method of purifying a flue gas desulfurization aqueous waste slurry containing calcium-sulfur salts and residual solid grits, fly ash, carbon and oils by supplying the aqueous waste slurry to a screening station to remove the grits, passing the grit-free aqueous waste slurry to a magnetic separator to remove fly ash components, and transferring the aqueous slurry to a floatation cell to remove carbon and oils therefrom. A purified aqueous slurry of calcium-sulfur salts is removed from the floatation cell which can be used in producing quality plaster, wallboard, or feedstock in producing &agr;-hemihydrate gypsum.

Abstract: A method is provided for removing sulfur dioxide and carbon dioxide out of gases from, for example, the combustion of sulfur containing fossil fuels. The sulfur dioxide and carbon dioxide contaminated gas is first contacted with an aqueous solution containing dimethyl sulfoxide and alkaline earth metal ions, wherein the aqueous solution is at an acidic pH, for example, at a pH of from about 2 to about less than 7, so that the sulfur dioxide in the gas is dissolved in the aqueous solution and, subsequently, reacts with the alkaline earth metal ions to form alkaline earth metal sulfates and alkaline earth metal sulfites. The gas is then contacted with an aqueous solution containing dimethyl sulfoxide and alkaline earth metal ions, wherein this aqueous solution is at a pH that is greater than 7 so that the carbon dioxide in the gas is dissolved in the aqueous solution and, subsequently, reacts with the alkaline earth metal ions to form alkaline earth metal carbonates.

Abstract: A method for the reversible agglomeration of fine particles of plaster of Paris (CaSO4.½H2O) and agglomerates made by the method which comprises agitating the fine particles in the presence of an organic polar liquid preferably nearly dry and having some ability to form hydrogen bonds (especially n-propanol) and then drying off most of the liquid whereby the fine particles spontaneously interlink (possibly by mechanical keying) in a way which allows the interlinks to be disrupted so as to release fine particles when the agglomerates are stirred into water by hand. Also a dry precursor mixture comprising the agglomerates containing conventional auxiliary additives for use in mixing with water to make aqueous compositions for use as filler pastes, casting materials or plaster slurries.

Abstract: Flue gas is treated for the presence of SO.sub.3, without resorting to ammonia injection, by adding a powder into the flue gas and subsequently bringing the flue gas into gas-liquid contact with an absorbing fluid, whereby the SO.sub.2 present in the flue gas is removed by absorption into the absorbing fluid. The treatment process may also include introducing the flue gas into a dust collector, whereby dust, including the powder present in the flue gas, is collected, and/or recovering heat from the flue gas by means of a heat exchanger, whereby the flue gas is cooled. A system for treating flue gas is also provided.

Abstract: A method for scrubbing flue gases of furnaces includes subjecting the flue gases with addition of activated carbon particles to wet scrubbing in a wet scrubbing device. Activated carbon particles are mixed with particles of at least one compound selected from slaked lime and limestone to produce a particle mixture that is introduced into the flue gases upstream of a flue gas heat exchanger that is positioned upstream of the wet scrubbing device.

Abstract: The present invention is directed towards a system that makes high quality gypsum from a dry flue gas desulfurization process which utilizes a low temperature regeneration of the carbon adsorbent in the flue gas process. The high quality gypsum is easily filterable with large crystal size and has high purity with few contaminants, such as calcium sulfite and heavy metals. This invention is also directed towards a system that regenerates the carbon used in dry flue gas desulfurization at a temperature below 120.degree. C. and the recycling of sodium hydroxide to form a sodium sulfite reducing solution for carbon adsorbent regeneration.

Abstract: A method is provided for treating ashes from the combustion of petroleum fuels by mixing the combustion ashes with water to produce a slurry; injecting either calcium oxide or calcium hydroxide into the slurry and reacting the calcium oxide or calcium hydroxide with the ammonium sulfate within the ashes to produce a slurry containing gypsum and ammonia; flowing the slurry containing gypsum and ammonia down from the top portion of packed column and air or steam up from the bottom portion of the packed column so that the air or steam strips the ammonia from the gypsum slurry; and separating the gypsum from the resulting ammonia-free slurry using a solid/liquid separator.

Abstract: This invention describes a process for the scrubbing of sulfur oxides from the effluent of conventional wet lime/limestone SOx reduction processes in coal or oil-fired plants. The sulfur oxides are oxidatively sorbed onto solid sorbents such as magnesium aluminate spinel. Reduction with the appropriate reducing gases (such as hydrogen) regenerates the catalyst, also yielding a process stream concentrated in SOx. This concentrated SOx stream can then be refed to the front end of the coal or oil-fired plants, with the SOx thus produced ultimately being removed in the conventional wet scrubbing technology.

Abstract: A process for the recovery of sulfur and carbon monoxide from metal sulfates in which the carbon monoxide is recycled as a reducing agent for reaction with the metal sulfate. Metal sulfates such as gypsum (calcium sulfate dihydrate) are processed to form sulfur dioxide. The sulfur dioxide is contacted with carbonaceous matter at sufficiently high temperature to form elemental sulfur and carbon monoxide. The carbon monoxide is then recycled for use as a reducing agent in the initial processing of the metal sulfate.

Abstract: A method for monitoring the oxidation rate in a flue gas desulfurization system having a slurry comprises locating a monitor in the system for accessing the slurry. A sample is periodically drawn from the slurry by the monitor wherein a titration is performed on each sample. The titration performed on each sample comprises adding a potassium iodate KIO.sub.3 solution, a potassium iodide KI starch solution and an acid solution to the sample in the monitor for causing the sample to exhibit a color corresponding to the oxidation rate.

Abstract: An exhaust gas treatment apparatus for the removal of at least a sulfur dioxide gas and ammonia from an exhaust gas by bringing the exhaust gas into vapor-liquid contact with an absorbing liquid comprises an introduction-side tank to which the absorbing liquid is supplied, a parallel-flow type absorption tower positioned above the introduction-side tank; an ejection side tank positioned adjacent the introduction side tank; a counter-flow type absorbing tower positioned above the ejection side tank; a mist eliminator for removing splash mist from the exhaust gas; and a controller for controlling the pH of the absorbing liquid in one of the introduction-side absorption tower and the ejection-side absorption tower.

Abstract: A process for the removal of a high percentage of NOx and SOx from the gaseous effluent of a metal pickling operation comprising passing the effluent through an aqueous scrubber, treating the gaseous effluent from the scrubber with ozone, passing the effluent from the ozone treatment through a second aqueous scrubber thereby removing at least 80 vol % of the NOx and SOx present in the original effluent. The scrubbing solutions in both of the scrubbers preferably have a pH of from 7 to 14, more preferably 10 to 14. The scrubbing solutions in both scrubbers are caustic solutions containing sodium hydroxide or calcium hydroxide. The NOx and SOx in the scrubbers are converted into nitrate salts and sulfate salts, which are removed from the scrubbers.

Abstract: A process for increasing the water solubility of gypsum in which gypsum is ground to about 5 to 50 mesh U.S. Standard Sieve Size, about 5 to 95 parts by weight of ground gypsum are mixed with about 2 to 25 parts by weight concentrated sulfuric acid having a concentration of about 93 to 98.5% H.sub.2 SO.sub.4, optionally in the presence of about 5 to 20 parts by weight water, and the resulting product is dried at a temperature of about 100-125.degree. C. to form a water-soluble, granular, solid, free-flowing gypsum product having a water solubility increased by about 2- to greater than 350-fold.

Abstract: This invention provides a process for effecting desulfurization and decarbonation in two stages. A gas containing sulfur oxides and carbon dioxide is first treated in a desulfurization step so as to cause sulfur oxides to be absorbed in the form of calcium-sulfur oxide compounds; the gas is then treated in a decarbonation step so as to cause carbon dioxide and any sulfur oxides escaping from the desulfurization step to be absorbed in the form of amine salts; the absorbing solution containing the amine salts is regenerated by liberating carbon dioxide therefrom; a part of the regenerated absorbing solution is recycled to the decarbonation step while the remainder of the absorbing solution is fed to a secondary regeneration step where it is treated with a basic calcium substance to regenerate basic amine compound for recycle and to form a solid containing calcium-sulfur oxide compounds and calcium carbonate.

Abstract: A clear solution and a method for preparing the solution which has a pH in the range of from 10 to 13.9 and containing sulfate ions in a concentration range less than 500 parts per million. The solution is prepared by mixing two solutions in which one solution has one equivalent of magnesium sulfate and an equivalent of sulfuric acid and the second solution has an equivalent of Ca (OH).sub.2 and two equivalents of K.sub.2 OH. It is believed that CaSO.sub.4 precipitates in the mixed solution and causes coprecipitation of potassium, perhaps as double salt with the Ca leaving OH stabilized by hydration and magnesium ions.

Abstract: A process is disclosed for treating lead paste from exhausted batteries. Calcium sulfite and calcium thiosulfite are formed by the reaction:3Ca(OH).sub.2 +4S.degree..fwdarw.2CaS+CaS.sub.2 O.sub.3 +3H.sub.2 O(1).The CaS and CaS.sub.2 O.sub.3 is reacted with sodium sulfate to effect the double exchange reaction:2CaS+CaS.sub.2 O.sub.3 +3Na.sub.2 SO.sub.4 .fwdarw.2Na.sub.2 S+Na.sub.2 S.sub.2 O.sub.3 +3CaSO.sub.4 (2).The sodium sulfide and sodium thiosulfate is then reacted with the lead paste for converting the various lead paste components (PbSO.sub.4, PbO and PbO.sub.2) into PbS with the concomitant production of sodium sulfate. The sodium sulfate can be recycled to reaction (2).

Abstract: A flue gas treating system for removing sulfur dioxide and dust present in flue gas by gas-liquid contact with an absorbing fluid and has an inlet side absorption tower of the liquid column type and an outlet side absorption tower of the liquid column type, each of which has a uniform cross-section over the area of gas-liquid contact, and the cross-section of flue gas in the inlet side absorption tower is smaller than the cross section of flue gas in the outlet side absorption tower. The inlet side absorption tower is constructed in the form of a parallel-flow absorption tower wherein the flue gas flows downward for favorable collection of dust and absorption of sulfur dioxide. The outlet side absorption tower is constructed in the form of a counter-flow adsorption tower wherein the flue gas flows upward for favorable absorption of sulfur dioxide. The absorbing fluid within a tank is injected upward from a plurality of spray pipes.

Abstract: A process for producing sodium bicarbonate and sodium carbonate. The process includes reacting within a reactor sodium sulfate in aqueous solution with ammonia and carbon dioxide to precipitate sodium bicarbonate and form a first mother liquor. The sodium bicarbonate is separated and dried to produce sodium bicarbonate product. Alternatively, the sodium bicarbonate may be calcined to convert it to sodium carbonate. The first mother liquor may be evaporated to precipitate unreacted sodium sulfate, with the formation of a second mother liquor. The second mother liquor may be cooled to precipitate a double salt of sodium sulfate/ammonium sulfate and water. A third mother liquor is formed from this process. The latter-mentioned liquor from the precipitation of the double salt is evaporated to precipitate a substantial pure ammonium sulfate in a purity of greater than approximately 75 wt %. A fourth mother liquor is formed.

Abstract: In the method of scrubbing flue gases, the flue gases are wet-scrubbed in the presence of activated carbon. The activated carbon is separated from a suspension resulting from wet scrubbing. The activated carbon is then divided into a first and a second portion, and the first portion is thermally desorbed. The first portion of the activated carbon is returned to the second portion of the activated carbon. The first and second portions of the activated carbon are recirculated to the wet scrubbing step. The device for scrubbing flue gases includes a flue gas desulfurization scrubber with a flue gas inlet line, a flue gas outlet line, and an adsorption medium line. A treatment device for treating a suspension formed in the flue gas desulfurization scrubber is provided. A thermal desorption device for the activated carbon is provided. The treatment device includes a separator for separating solid material from the suspension.

Abstract: After hydrogenation and desulfurization treatment of raw fuel in the desulfurization unit 1, the product is separated in the acidic gas separator 2 into fuel and a hydrogen sulfide-containing gas, and the hydrogen sulfide-containing gas is subjected to combustion together with air in the catalyst converter 3 thereby converting the hydrogen sulfide completely into sulfur dioxide to give a sulfur dioxide-containing gas, and this sulfur dioxide-containing gas is reacted with limestone powder and air in water in the oxidation and neutralization reactor 4, and the resulting slurry is dehydrated in the gypsum slurry solid/liquid separator 5 and then dried in the gypsum heater 6.

Abstract: Methods and apparatus for the hydrometallurgical separation and recovery of biological nutrients, cadmium, lead, and gypsum from raw materials such as electric arc furnace flue dust. Biological nutrients, including zinc and iron, are selectively separated and recovered from raw materials, including metals and metal oxides, and are selectively and variably recombined, to achieve a biological nutrient product which a desired relative concentration of zinc and iron. The process is a closed system generating no solid waste, no liquid water or acid waste streams, and whereby gypsum, and substantially all hazardous wastes such as lead and cadmium, are separated and recovered from raw material for sale as commercial products.

Abstract: A method and apparatus is disclosed for the continuous calcining of gypsum material in a high-efficiency, refractoryless kettle preferably heated by a multiple series of separate immersion tube burner coils, each coil operating within a specific calcining zone inside the kettle. The lowest, i.e., initial, burner tube coil is formed with a low profile to permit use of a small initial gypsum charge, and hence, a quick kettle start-up cycle. That low profile initial burner design also helps keep the agitator motor's load at a minimum during cycle start-up. Due to the immersion tube burner coil construction, no refractory structure for the kettle is required. Also, no separate hot pit structure is required, as the kettle is used to merely hold the material being calcined and no residual heat is present. A relatively thin kettle can be constructed, as it need only withstand relatively low operating temperatures.

Abstract: A method of improving ground soil irrigation by employing an additive or amendment in the form of an improved synthetic solution grade calcium sulfate dihydrate composition. This composition is formulated by contacting a calcium compound having a calcium cation with a chemical agent enabling the calcium compound to yield calcium ions upon reaction with the chemical agent and which enables the calcium cation to react with an anion of the chemical agent forming a second calcium compound. The second calcium compound is reacted with a sulfur containing acid, such as sulfuric acid, to thereby form a calcium sulfate dihydrate. The compound has improved suspension characteristics and will remain in suspension for a much longer period of time than a conventional solution grade calcium sulfate dihydrate.