Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B7/00—Halogens; Halogen acids
  • C01B7/01—Chlorine; Hydrogen chloride
  • C01B7/07—Purification ; Separation
  • C01B7/0706—Purification ; Separation of hydrogen chloride

Definitions

• U.S. patent No. 4 349 525 describes a method for purification of hydrochloric acid that is produced by a reaction between alkali chloride and sulfuric acid. It was found that the colour was caused by Br 2 and that simultaneous removal of S0 2 also resulted in a decrease in the colour level. According to this patent, the acid is purified by stripping with inert gas and oxygen. A colourless acid was obtained. However, this is an expensive process as a stripping tower and the supply of a sufficient amount of inert gas/ oxygen is needed.
• the invention concerns a method for the removal of colouring material as iron and halogens from hydrochloric acid.
• halogens it is especially chlorine and bromine that contribute to the colour
• iron is first removed from the hydrochloric acid preferably by filtration and ion exchange and thereafter a nitrogen containing reduction agent is added to the acid.
• a nitrogen containing reduction agent is added to the acid.
• compounds comprising hydroxyl amine , preferably hydroxylamine hydrochloride (hydroxyl ammonium chloride).
• the reducing agent is supplied in a stoichiometric excess.
• Iron is first removed from the acid for example by filtration and ion exchange.
• An analysis of the produced hydrochloric acid showed that the main source for the yellow colour after the removal of iron, was halogens as free chlorine and bromine. It was found that it was possible to reduce the surplus of free chlorine and bromine by adding a reducing agent.
• the compound should be pumpable or easily being made pumpable (soluble in water).
• Hydroxylamine in hydrochloric acid will occur in the form of the hydroxylammonium ion H 3 NOH + .
• the most probable reactions between the free halogens and hydroxylamine are the following, where reaction 1 is dominant:
• the colour is reduced from 100-125 Hazen to 15-20 Hazen during 1 day and night at 20°C. It can also be seen that the colouring extent is substantially increased during the first half hour after supply of the reducing agent.
• Reduction agent hydroxylamine hydrochloride
• concentration levels 187 mg/l, 375 mg/l, 750 mg/l and 1000 mg/l.
• the colour was measured in intervals of 5 minutes the first 30 minutes, with 10 minutes intervals the next 30 minutes and thereafter each half hour the next 2,5 hours.
• the temperature was 22 °C.
• a correct dosage will be between 375 and 750 mg/l, i.e. about 500 mg/l for this content of halogens.
• This quantity results in a clear acid after about 30-40 minutes and the Cl 2 value is ⁇ 1ppm. With this quantity it is also included that natural variations in halogen/colour content can occur and that the mixing is not as good as in large scale.
• the added dosage of the reducing agent will be dependent on the quantity of halogens present in the acid. However, generally it can be said that the reducing agent is added in excess compared to stoiciometric amount to obtain the wanted effect.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Treatment Of Sludge (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Optical Filters (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Catalysts (AREA)
• Pigments, Carbon Blacks, Or Wood Stains (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

Family

ID=19897144

Family Applications (1)

Country Status (12)

Cited By (1)

Families Citing this family (4)

Citations (3)

Family Cites Families (7)

• 1994
  • 1994-06-03 NO NO19942074A patent/NO179243B1/no not_active IP Right Cessation
• 1995
  • 1995-05-31 JP JP8500697A patent/JPH08509455A/ja active Pending
  • 1995-05-31 EP EP95922008A patent/EP0725759B1/en not_active Expired - Lifetime
  • 1995-05-31 AT AT95922008T patent/ATE184860T1/de not_active IP Right Cessation
  • 1995-05-31 DE DE69512378T patent/DE69512378T2/de not_active Expired - Fee Related
  • 1995-05-31 RU RU96104255A patent/RU2107020C1/ru not_active IP Right Cessation
  • 1995-05-31 US US08/586,874 patent/US6290927B1/en not_active Expired - Fee Related
  • 1995-05-31 CN CN95190500A patent/CN1040865C/zh not_active Expired - Fee Related
  • 1995-05-31 AU AU26843/95A patent/AU2684395A/en not_active Abandoned
  • 1995-05-31 WO PCT/NO1995/000085 patent/WO1995033680A1/en active IP Right Grant
  • 1995-05-31 PL PL95312777A patent/PL179886B1/pl not_active IP Right Cessation
  • 1995-05-31 ES ES95922008T patent/ES2138215T3/es not_active Expired - Lifetime

Patent Citations (3)

Non-Patent Citations (1)

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