US2592139A - Continuous process for the production of anhydrous glauber's salt - Google Patents

Continuous process for the production of anhydrous glauber's salt Download PDF

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US2592139A
US2592139A US97414A US9741449A US2592139A US 2592139 A US2592139 A US 2592139A US 97414 A US97414 A US 97414A US 9741449 A US9741449 A US 9741449A US 2592139 A US2592139 A US 2592139A
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sodium sulphate
salt
solution
glaubers salt
tank
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US97414A
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English (en)
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Horace J Hegan
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Akzo Nobel UK PLC
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Courtaulds PLC
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
    • C01D5/18—Dehydration
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F13/00—Recovery of starting material, waste material or solvents during the manufacture of artificial filaments or the like
    • D01F13/02—Recovery of starting material, waste material or solvents during the manufacture of artificial filaments or the like of cellulose, cellulose derivatives or proteins
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
    • Y02P70/62—Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear

Definitions

  • Glaubers salt obtained contains small amounts of sulphuric acid and zinc sulphate and for economic reasons it has been the practice hitherto in the viscose industry to discharge the crystallised salt, together with the small amount of sulphuric-acid and zinc sulphate associated with it, to waste.
  • Glaubers salt can be converted into anhydrous sodium sulphate, which has a higher commercial value than Glaubers salt, by heating it above its transition temperature (about 325 centigrade). either alone or in a saturated solution of sodium sulphate, the mother liquor being run off and cooled to provide further quantities of Glaubers salt.
  • anhydrous sodium sulphate tends to deposit in hard, cakelike form on hot surfaces in the evaporators or heaters used, and also in certain circumstances in the pipes connecting the various pieces of apparatus used in the recovery process.
  • This caking is believed to be mainly due to the fact that sodium sulphate has a negative solubility coefficient and consequently, heating sodium sulphate solutions from a low temperature, for example 32 centigrade to a high temperature, for example 80-90 centigrade, causes deposition of sodium sulphate in the heaters.
  • the object of the present invention is to provide an improved, economic process for converting crude Glaubers salt into anhydrous sodium sulphate in the viscose industry.
  • a continuous process for the production of anhydrous sodium sulphate from Glaubers salt comprises continuously feeding the Glaubers salt into a stream of a saturated aqueous solution of sodium sulphate of gradually increasing temperature, the salt being introduced at a point where the temperature of the solution is below 325 centigrade, converting the Glaubers salt into anhydrous sodium sulphate by drawing it through the stream of solution into a heated zone of solution, that is a zone of solution maintained at a temperature above 32.5 centigrade, in a direction opposite to the direction of flow of the solution, which solution is continuously formed solely as a result of the heating of the Glaubers salt in the heated zone so that it thereafter flows continuously from the heated zone -through the advancing Glaubers salt and so forms the stream of solution of gradually increasing temperature and, while cooling and flowing, it washes the Glaubers salt and also deposits pure Glaubers salt crystals, and continuously recovering the anhydrous sodium sulphate formed.
  • the temperature of the solution at the point where the Glaubers salt at the
  • the present invention also includes apparatus for the production of anhydrous sodium sulphate from Glaubers salt comprising in combination,
  • an elongated vessel mechanism for continuously feeding the Glaubers salt into one end of the elongated vessel, at least one mechanical device for drawing the Glaubers salt through the vessel from one end to the other, and heating means at the other end of the vessel to where the Glaubers salt is fed in, which heating means forms a heating zone to convert the Glaubers salt into anhydrous sodium sulphate and saturated sodium sulphate solution, the vessel being so arranged and constructed that the saturated sodium sulphate solution so formed flows towards the Glaubers salt feeding end of the vessel and forms a stream of solution the temperature of which gradually decreases as it flows through the vessel.
  • cooling means is also provided from the beginning of the heated zone to the Glaubers salt feeding point so that the temperature of the flowing solution may be readily adjusted to give .the desired temperature gradient.
  • Both the heating and .oooling of the vessel are preferably effected by jacketing the vessel and circulating either a heating fluid such as hot water or steam or a cooling medium such as water, as the case may be, through the jackets.
  • the vessel consists of a long tank or trough.
  • the part of the tank or trough which forms the heating zone may be inclined if desired so that the washed crystals are allowed to drain before being converted into the anhydrous salt.
  • the conversion of the washed Glaubers salt to the anhydrous salt is effected in a heated container provided at the end of the tank or trough, and into which the salt is drawn, preferably after draining, by the mechanical device, the sodium sulphate solution which is simultaneously liberated being continuously fed back to the vessel at the beginning of the heated zone for example by an over-flow pipe.
  • the pipe may be jacketed so that the temperature of the liquid can be. adjusted to as near 325 centigrade as possible.
  • the vessel is formed by a series of inter communicating circular tanks connected so that there is a step of the foot of each tank communicating with the succeeding tank.
  • Each tank is provided with a rotating paddle which turns the Glaubers salt crystals round till they fall over the step into the next tank.
  • the Glaubers salt may be drawn through the solution by an Archimedean screw; or a system of rakes, paddles, scrapers or other mechanical devices.
  • the mechanical devices used to draw the Glaubers salt through the solution may also be used to draw the anhydrous sodium sulphate into a suitable collecting device, for example a separating tank or a centrifuge, or a separate mechanical device may be used for this purpose.
  • the liquor adhering to the crystals is separated by the centrifuge and if necessary is reheated and fed back into the stream of sodiumof the anhydrous sodium sulphate.
  • the tank or trough in front of the heated zone is preferably immersed in a stream of cooling water moving in the same direction as the direction in which the Glaubers salt is raked.
  • the process may be carried out so that anhydrous sodium sulphate is collected at one end of the tank while a cooled saturated solution of sodium sulphate of such low concentration runs away at the other end that it is possible continuously to recover about per cent or more of the sodium sulphate in the crude Glaubers salt in the form of the anhydrous salt, depending on the temperature to which the solution is ultimately cooled.
  • the tank extends so that the solution of sodium sulphate flows beyond the feeding point of the crude Glaubers salt so that the'further cooling beyond this point for example to 2-14 centrigrade deposits substantially pure crystals of Glaubers salt and the crystals so deposited are recovered by drawing them by a second mechanical device in the same direction as the direction of the flow of the solution to a suitable collecting device such as a centrifuge.
  • a suitable collecting device such as a centrifuge.
  • the point of addition of the crude Glaubers salt to the tank will be nearer to the heated zone of sodium sulphate solution than in the case in which only sodium sulphate solution is collected beyond the feeding point of the Glaubers salt and the temperature of the solution at the point of entry of the Glaubers salt will be correspondingly higher.
  • This embodiment of the invention permits the simultaneous and continuous production of commercially pure anhydrous sodium sulphate and commercially pure Glaubers salt from crude Glaubers salt such as is obtained by evaporation 1 and crystallisation of viscose spinning
  • sodium sulphate solution may be maintained by withdrawing part of the stream of solution at a point where its temperature is below 325 centigrade, heating the withdrawn solution and feeding it back into the stream at the point where the anhydrous sodium sulphate is recovered.
  • the solution withdrawn in this manner is preferably reheated to a temperature at which the solubility of sodium sulphate in water is not below its solubility at the temperature at the withdrawal point. In this manner deposition of anhydrous sodium sulphate in the heater and in the pipes connecting the heater to the tank may be prevented.
  • the solution may be heated to a temperature of 60 centigrade since the solubility of sodium sulphate in water is 31.2 per cent at both 31.5 centigrade and 60 centigrade.
  • Information on the solubility of sodium sulphate is given by A. Seidell on page 1301 of his book entitled Solubilities of Inorganic and Metal Orgenie Compounds, 3rd edition, volume 1, and published in 1940 by D. Van Nostrand' Co. Inc.
  • the withdrawn solution may also be treated to remove impurities such as sulphuric acid or zinc sulphate before it is returned to the tank.
  • the action of the paddles or rakes should be so adjusted as to bring the crystals of Glaubers salt into substantial equilibrium with the solution at every stage of increasing temperature and concentration; this is particularly important at the last stage where the temperature is at or near to 325v centigrade for at this temperature the solubility of sodium sulphate is at its maximum. If therefore any of the solution is carried over with the Glaubers salt into the heating or decomposition zone, none or only a small proportion of the Glaubers salt is dissolved and a maximum yield of anhydrous sodium sulphate is attained.
  • the process according to the invention differs from any of the known processes of converting Glaubers salt to anhydrous sodium sulphate for in the known processes it is usual to crystallise out the Glaubers salt at relatively low temperatures and therefore any adhering mother liquor when heated above the transition temperature of Glaubers salt is capable of dissolving some of the anhydrous sodium sulphate formed by the decomposition process thus decreasing the yield for a given consumption of heat.
  • the continuous production of anhydrous sodium sulphate, with or without the simultaneous production of pure Glaubers salt is employed as part of a continuous process for the conservation and recovery of chemicals from viscose rayon spinning baths containing sulphuric acid, sodium sulphate and-zinc sulphate.
  • spinning bath liquor may be withdrawn either continuously or intermittently and water evaporated from the liquor so that on cooling, Glaubers salt will crystallise out.
  • the cooling of the liquor is effected in a tank while the liquor is moving in a stream in the same direction as the rakes, scrapers orother device employed to move the Glaubers salt, and when the desired degree of cooling has been obtained, the-mother liquor is allowed to drain away from the tank over a suitably placed weir and is returned to the spinning bath, if necessary after adjustment of its composition, while the crude crystals of Glaubers salt are continuously raked forward past the exit weir of the mother liquor into the moving stream of sodium sulphate solution.
  • the crystallisation of the crude Glaubers salt from the evaporated liquor and also its conversion to anhydrous sodium sulphate may be effected in one long tank.
  • the weak sodium sulphate solution containing any small quantities of acid and zinc sulphate which had adhered to the crude Glaubers salt may be passed over a weir of the tank and may be added to the mother liquor as it returns to the spinning bath.
  • the evaporated spinning bath liquor is preferably introduced into the tank at a temperature of the order of 40-45 centigrade and cooled in the tank to a temperature of about 12-14 centigrade immediately before the weir.
  • Figure 1 is a vertical section of an apparatus for converting Glaubers salt to anhydrous sodium sulphate in a long straight tank
  • FIG. 1 is an enlarged section on the line 11-11 of Figure 1
  • Figure 3 is a vertical section of a modification of the apparatus of Figure 1 in which the washed Glaubers salt crystals are allowed to drain before being converted into the anhydrous salt,
  • Figures 4 and 5 illustrate a further modification in which a series. of intercommunicating cirview of part only of the tanks
  • Figure 6 is a vertical section of an apparatus for producing both pure Glaubers salt and anhydrous sodium sulphate
  • Figure '7 is a vertical section of an apparatus for the continuous recovery of anhydrous sodium sulphate and other chemicals from viscose spinning baths.
  • crude Glaubers salt I is fed continuously from a hopper 2 into a long jacketed tank 3.
  • a series of scrapers 4, carried by a bar 5. is continuously oscillated as shown so that the crystals within the tank 3 are slowly drawn from left to right through a stream of saturated sodium sulphate solution 6 flowing through the tank 3 from right to left and finally are drawn into the heated container 1 in which -the washed Glaubers salt is converted into anhy- -drous sodium sulphate 8.
  • the tank 3 consists of two zones AB and BC,
  • Zone AB being the cooled or crystallizing zone of gradually increasing temperature up to 325 centigrade and the zone BC being the heated or decomposition zone at a temperature above 32.5" centigrade, preferably about centigrade. Higher temperatures may be used but are undesirable as they cause scaling on the container walls as a result of the negative solubility coefficient of sodium sulphate above 325 centigrade.
  • Zone AB is provided with a bafiled jacket 9 through which cooling water is continuously circulated, the water being fed in through an inlet pipe I 0 and flowing out through an exit pipe ii.
  • the heated zone BC has a surrounding jacket I2 which also surrounds the lower part of the container 1. Jacket I2 is heated by steam -or hot Water pipes 13, the heating medium flowing from pipe [4 to pipe l5 at such an initial temperature and at such a rate that at point B the temperature is about 32.5 centigrade.
  • the crude crystals I fed in at the end A are slowly drawn by the scrapers 4 through the stream of solution 6 and as they are advancing they are washed by the solution.
  • the washed crystals enter the decomposition solution formed then flows from the end C towards the end A thus automatically and continuously forming the stream of solution 6.
  • the temperature is regulated at or about 325 centigrade, and washes the advancing crystals and also deposits pure Glaubers salt to augment the crystals I.
  • its temperature gradually decreases as a result of cooling by the advancing crystals and the cooling water in jacket 9, the temperature and rate of flow of which is regulated to give the necessary temperature gradient having regard to the length of the tank.
  • the solution reaches point A its temperature will preferably be about 12-14 centigrade and it then flows away through pipe I! to waste; if desired the pipe i! may be replaced by an open channel so that any crystals which become deposited are accessible for removal.
  • acid-contaminated Glaubers salt it is desirable to neutralise the solution and this is preferably effected at point B just before the washed crystals enter the decomposition zone.
  • Container 20 is provided with a jacket 2
  • the tank is formed by a series of intercommunicating tanks 24 having the desired temperature gradient from about 1244 centigrade at point A up to 325 centigrade at point B.
  • the propulsion of the Glaubers salt crystals is carried out by a series of rotating paddles 25, one for each tank, which turn the crystals round until they fall over a step 26 into the succeeding tank.
  • the paddles as shown are arranged to scrape the sides of the tanks to prevent undue scaling of crystals on the tank walls. The procedure is otherwise the same as that described with. reference to Figures 1 and. 2.
  • crude Glaubers salt'l is fed from a hopper 2 into a jacketed tank 3 as described with reference to Figures 1 and 2 but in this case the hopper is arranged nearer to the heated zone of the tank so that the crude salt I is fed into the stream of solution at a higher temperature, for example about 20 centigrade and the tank 3 and the cooling jacket 3 are extended beyond the Glaubers salt feeding point, that is to the left of the hopper 2.
  • the apparatus to the right of the hopper 2 for producing the anhydrous salt is not shown in full since it corresponds with that shown in either Figure 1 or Figure 3.
  • the saturated sodium sulphate solution 6 after flowing past the hopper 2 continues to cool and in cooling deposits pure Glaubers salt crystals 21.
  • evaporated spinning bath liquor while still hot for example at a temperature of 40 to 45 centigrade is fed from a pipe 33 into one end of a jacketed tank 34.
  • the solution in the tank 34 begins to deposit crude Glaubers salt 35 which is drawn, together with its associated mother liquor, by a system of scrapers 35, carried by a bar 31, towards a weir 38.
  • the crude Glaubers salt and mother liquor while being drawn along by the scrapers 38 are cooled by means of cooling water flowing from an inlet pipe 39 into a jacket '30, out through an exit pipe 4!, and while so cooling further crystals of Glaubers salt are deposited.
  • the temperature of the weir 38 is preferably about 12 to 14 centigrade.
  • a continuous process for the production of anhydrous sodium sulphate from Glaubers salt which comprises heating Glaubers salt to a temperature above 32.5 centigrade to form anhydrous sodium sulphate and a saturated solution of sodium sulphate by passing the Glaubers salt longitudinally through a substantially horizontal tank having at one end a cold zone at a temperature below 32.5 C. and at the other end a hot zone above 325 C., continuously separating the saturated solution from the anhydrous sodium sulphate and recovering the anhydrous sodium sulphate by withdrawing it from the tank at the hot zone, causing the saturated sodium sulphate solution so formed to flow continuously as a confined stream along a substantially horizontal path away from the hot zone to the cold zone,
  • a continuous process for the production of anhydrous sodium sulphate from Glaubers salt which comprises heating Glaubers salt to a temperature above 325 C. in a hot zone to form a saturated solution of sodium sulphate and anhydrous sodium sulphate, causing the saturated sodium sulphate solution so formed to flow as a confined stream along a substantially horizontal path from the hot zone having a temperature above 325 C. to a cold zone at a temperature below 325 C.
  • a process as claimed in claim 2 wherein the temperature of the stream of solution at the point where the additional Glaubers salt is fed in is about 12 to 14 centigrade.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Textile Engineering (AREA)
  • Artificial Filaments (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US97414A 1948-07-02 1949-06-06 Continuous process for the production of anhydrous glauber's salt Expired - Lifetime US2592139A (en)

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GB17869/48A GB646111A (en) 1948-07-02 1948-07-02 Process for producing anhydrous sodium sulphate from glauber's salt

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US (1) US2592139A (pt)
BE (1) BE489948A (pt)
DE (1) DE853937C (pt)
FR (1) FR990016A (pt)
GB (1) GB646111A (pt)
NL (1) NL70236C (pt)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3378339A (en) * 1961-09-07 1968-04-16 Asahi Chemical Ind Method of removing the accompanying liquid of a continuously transferred ion exchange resin
US4179493A (en) * 1977-03-18 1979-12-18 Abraham Sadan Dehydration process
US4209312A (en) * 1976-07-19 1980-06-24 General Electric Company Controlling size in Glauber's salt crystal formation
FR2447218A1 (fr) * 1979-01-26 1980-08-22 Solmat Syst Procede d'utilisation de bassins solaires pour provoquer des variations de temperature controlees de solutions, en particulier dans des procedes impliquant la dissolution et/ou la precipitation de sels

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111533142B (zh) * 2020-06-04 2022-12-09 新疆中泰化学阜康能源有限公司 加热析出元明粉降温结晶浓缩的循环生产方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US400983A (en) * 1889-04-09 Apparatus for the manufacture of salt
US1004858A (en) * 1907-11-11 1911-10-03 Dow Chemical Co Method of producing crystals.
FR518671A (fr) * 1918-06-25 1921-05-28 Balcke Ag Maschbau Dispositif de refroidissement des solutions salines chaudes
US2121208A (en) * 1935-03-30 1938-06-21 American Agricultural Chem Co Production of monocalcium phosphate
US2374004A (en) * 1941-12-02 1945-04-17 American Viscose Corp Glauber's salt conversion
US2459302A (en) * 1942-12-10 1949-01-18 American Viscose Corp Concentration of salts having minimum solubilities at temperatures above those of the initial solutions
US2504097A (en) * 1948-08-30 1950-04-11 West End Chemical Company Process for producing anhydrous sodium sulfate

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE444048C (de) * 1923-08-29 1927-05-14 Bernhard Young Dr Verfahren zur Herstellung von trockenem Natriumsulfat aus Glaubersalz in einem Arbeitsgang
DE424983C (de) * 1924-10-04 1926-02-10 Waldemar Recha Dipl Ing Verfahren zur kontinuierlichen Herstellung von wasserfreiem Natriumsulfat
DE478987C (de) * 1924-10-04 1929-07-08 Waldemar Recha Dipl Ing Verfahren zur kontinuierlichen Herstellung von trockenem Natriumsulfat aus Glaubersalz
GB448007A (en) * 1935-04-26 1936-05-29 Int Paper Co Improvements in or relating to thermal insulation and process of making the same
DE662448C (de) * 1935-10-03 1938-07-13 Zahn & Co G M B H Verfahren zur Entwaesserung von schmelzbaren Salzen, z. B. Glaubersalz, in Drehrohren
DE710373C (de) * 1937-04-13 1941-09-11 I G Farbenindustrie Akt Ges Verfahren zur Regenerierung von Ammoniumsulfat und Natriumsulfat enthaltenden Viskosespinnbaedern
BE452848A (pt) * 1942-10-26

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US400983A (en) * 1889-04-09 Apparatus for the manufacture of salt
US1004858A (en) * 1907-11-11 1911-10-03 Dow Chemical Co Method of producing crystals.
FR518671A (fr) * 1918-06-25 1921-05-28 Balcke Ag Maschbau Dispositif de refroidissement des solutions salines chaudes
US2121208A (en) * 1935-03-30 1938-06-21 American Agricultural Chem Co Production of monocalcium phosphate
US2374004A (en) * 1941-12-02 1945-04-17 American Viscose Corp Glauber's salt conversion
US2459302A (en) * 1942-12-10 1949-01-18 American Viscose Corp Concentration of salts having minimum solubilities at temperatures above those of the initial solutions
US2504097A (en) * 1948-08-30 1950-04-11 West End Chemical Company Process for producing anhydrous sodium sulfate

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3378339A (en) * 1961-09-07 1968-04-16 Asahi Chemical Ind Method of removing the accompanying liquid of a continuously transferred ion exchange resin
US4209312A (en) * 1976-07-19 1980-06-24 General Electric Company Controlling size in Glauber's salt crystal formation
US4179493A (en) * 1977-03-18 1979-12-18 Abraham Sadan Dehydration process
FR2447218A1 (fr) * 1979-01-26 1980-08-22 Solmat Syst Procede d'utilisation de bassins solaires pour provoquer des variations de temperature controlees de solutions, en particulier dans des procedes impliquant la dissolution et/ou la precipitation de sels

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Publication number Publication date
FR990016A (fr) 1951-09-17
BE489948A (pt) 1900-01-01
DE853937C (de) 1952-10-30
GB646111A (en) 1950-11-15
NL70236C (pt) 1900-01-01

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