Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G9/00—Compounds of zinc
  • C01G9/06—Sulfates
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES, NOT OTHERWISE PROVIDED FOR; PREPARATION OR TREATMENT THEREOF
  • A23L21/00—Marmalades, jams, jellies or the like; Products from apiculture; Preparation or treatment thereof
  • A23L21/10—Marmalades; Jams; Jellies; Other similar fruit or vegetable compositions; Simulated fruit products
  • A23L21/18—Simulated fruit products
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B17/00—Sulfur; Compounds thereof
  • C01B17/69—Sulfur trioxide; Sulfuric acid
  • C01B17/90—Separation; Purification
  • C01B17/901—Recovery from spent acids containing metallic ions, e.g. hydrolysis acids, pickling acids
• • 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
  • C01D5/006—Recovery of sodium sulfate from coagulation baths for the spinning of viscose
• • 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

• This invention relates to the recovery of chemical substances from viscose rayon spinning bath liquors containing sulphuric acid, sodium sulphate and also zinc sulphate in a proportion of less than 2 per cent. It also includes such recovery from liquors which contain additional compounds such as magnesium sulphate.
• a process for the recovery of chemical substances from viscose rayon spinning baths containing sulphuric acid, sodium sulphate and also zinc sulphate in a proportion ofless than 2 per cent includes the steps of removing water by evoporation from the spinning bath liquor and if necessary adding acid to the bath liquor until the total proportion by weight of sodium sulphate, calculated as NazSO4, present in the liquor and as precipitated crystals exceeds 30 per cent of the weight of the concentrated liquor and the percentage by weight of acid in the concentrated liquor exceeds 1'?
• the evaporation is preferably carried out until the weight of sodium sulphate present exceeds 35 per cent and the acid concentration exceeds 25 per cent. In order to enable this acid concentration to be reached, it may be necessary to add sulphuric acid to the spinning bath before or during the evaporation.
• the separated complex sodium sulphate, sulphuric acid, and zinc sulphate salts particularly if the sulphuric acid and zinc sulphate contents are not very high may be subjected to a single step treatment with spinning bath or channel liquor evaporated to a high content of sodium sulphate if suilicient of these solutions be available when the decomposition and solution will take place in one stage.
• Channel liquor is the name given to the drip liquor from the formed filaments. Care must be taken that the acid concentration does not rise about 17 per cent because acid solutions containing above 17 per cent sulphuric acid will not completely decompose the complex salts; v
• the mother liquor after the separation of the complex crystals may be returned to the spinning bath; alternatively as its acid content is high a proportion or all of it may be added to the spinning bath about to be evaporated so as to increase the acid content.
• the decomposing solutions may be made up from the. spinning bath liquor itself or from evaporated spinning bath liquor, or from channel liquor or from a mixture of any of these.
• solutions resulting from the decomposition step in particular those of high acid content for example of about or abovel'lper cent, can be added to the spinning bathor can be added to the liquor in the evaporator for the purpose of adjusting the acid content of the evaporated liquor as required. Adjustment of the acid content of the liquor in the evaporator can also be made by the addition of concentrated sulphuric acid in quantities less than the equivalent of anhydrous sodium sulphate removed.
• the solid residue remaining from the decomposing steps is'largely anhydrous sodium sulphate.
• crystals which have been treated with acid washing solution with an acid content below 1'? per cent sulphuric acid at a temperature above 32 cen-tigrade and containing only a small proportion of acid and zinc sulphate are washed with water at 32 centigrade or above, or with a saturated solution of sodium sulphate at 32 centigrade or above.
• the percentag proportions referred to in this specification are based on the weights of H2804, Na'zSU; and ZIlSOa. present in the solutions.
• Example 1 2000 grams of spinning bath containing '9 per cent H2304, 0.8 per cent ZnSOr, 25 per cent Na2SO4 and 64.2 per cent H2O was mixed with 150 grams of concentrated sulphuric acid grams of mother liquor obtained from a vious batch and containing 28 per cent lit-S04, 27 per cent Na2SO4, 1.5 per cent ZnSO4 and per cent 20. The mixture was evap orated to 70 centigrade until 1000 grams of water had been removed. At this point crystallisation was about to begin and th hot evaporated solution contained 29.4 per cent H2804, 37.5 per cent Nae-S02, 1.4 percent ZnSO4 and 31.6 per cent H2O.
• the solution was then cooled to 21 centigrade and the precipitated crystals separated by drainon a coarse filter.
• the filtrate which drained from the crystals during this percolation process gradually decreased in acid concentration from 29 per cent to 18 per cent while the ZnSO4 decreased from 1.9 per cent to 1.1 per cent and the total quantity of washings obtained was 1400' grams. Part of this was added to some of the mother liquor to adjust the strength of H280; and ZnSOr for use in the evaporation of the next batch and the remainder of the mother liquor and washings was returned to the spinning bath.
• the quantity of acid added to adjust the concentration of the solution in the evaporator was less than the equivalent of the sodium sulphate recovered.
• Example 2 1330 grams of spinning bath containing 10 per cent H2804, 24 per cent Na2SO4 and 0.6 per cent ZnSO4 were mixed with 4000 grams of wash liquor from a previous batch, containing 18 per cent H2504, 35' per cent Na2SO4 and 1.0 per cent ZnSOr and the mixture was evaporated to 3460 grams with loss'of nearly 40 per cent of its weight of water.
• the mag-ma of mother liquor and crystals was cooled to 20 centigrade with further precipitation of crystals.
• the mother liquor was separated by decantation and filtration. It weighed 1670 grams and contained about 29 per cent H2SO4. This liquor was returned to the spinning bath.
• the treatment was continued by agitation at 50 centigrade until the H2804, Na2SO4, ZnS04 complex was completely decomposed.
• the wash liquor was then removed by filtration and amounted to approximately 4000 grams and contained about 18 per cent H2804. It was then available for addition to the next batch of spinning bath to be run into the evaporator.
• the decomposed crystals amounting to about 1000 grams and containing only small proportions of H2804 and ZnS04 were washedfree from acid and ZnSO4 by hot saturated sodium sulphate solution.
• a process for the recovery of chemical substances from viscose rayon spinning baths containing sulphuric acid, sodium sulphate and zinc sulphate, said zinc sulphate being present in an amount greater than 0 and less than about 2 per cent which comprises removingwater by evaporation from the spinning bath liquor until the total proportion by weight of sodium sulphate calculated as Na2SO4 present in the liquor and as precipitated crystals exceeds 30 percent of the weight of the concentrated liquor and adjusting the sulphuric acid content of the concentrated liquor until it is in excess of 17 per cent by weight temperature below 32 centigrade with aqueous satunated sodium sulphate liquors containing sulphuric acid in a concentration of at least 1'7 per cent by weight, and then washing the crystals at a temperature above 32 centigrade with aqueous saturated sodium sulphate liquors containing sulphuric acid in a concentration greater than 0 per cent but below 17 per cent by weight whereby the complex sodium sulphates present in the

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Polymers & Plastics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Nutrition Science (AREA)
• Food Science & Technology (AREA)
• Health & Medical Sciences (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Textile Engineering (AREA)
• Artificial Filaments (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)

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Publications (1)

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Cited By (7)

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Citations (3)

• 1946
  • 1946-12-23 GB GB37654/46A patent/GB620738A/en not_active Expired
• 1947
  • 1947-11-03 US US783846A patent/US2521367A/en not_active Expired - Lifetime
  • 1947-11-20 NL NL136175A patent/NL65959C/xx active
  • 1947-12-04 BE BE477858D patent/BE477858A/xx unknown
  • 1947-12-05 FR FR956908D patent/FR956908A/fr not_active Expired
• 1948
  • 1948-12-02 DE DEP23270D patent/DE856690C/de not_active Expired

Patent Citations (3)

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