Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D3/00—Halides of sodium, potassium or alkali metals in general
  • C01D3/14—Purification
  • C01D3/16—Purification by precipitation or adsorption
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
  • C25B1/01—Products
  • C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B15/00—Operating or servicing cells
  • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes

Definitions

• the invention relates to a method and the matching device for removing silicon compounds from brine, which is intended for electrolysis.
• Silicon is usually included in the form of silicic acid as a companion element in rock salt or sodium chloride, as is present in salt deposits or can be obtained from sea salt. In saline solution, it is present as a monomeric or amorphous form or as polysilicic acid, even in agglomerates and disturbs the electrolysis process.
• a chemical reagent which may be sodium hydroxide, sodium carbonate, calcium hydroxide, calcium chloride, barium chloride, barium carbonate and / or ferrous chloride, is added to the solution for precipitation and separation of impurities and, at the same time, a slurry of impurities in the solution which are present together with the reagent, and thereby the silica precipitates together with the impurities.
• a pH of 8 to 11 is set.
• a disadvantage of the above-cited method is that they are very expensive and the precipitation of the respective silicate must be carried out at an alkaline pH and can not already be carried out in an acidic medium as in the subsequent electrolysis process.
• the object of the present invention is therefore to provide a fast-acting method which has a simplified and improved Procedure, based on the conventional art represents.
• Another object of the invention is to provide a device that can be integrated into existing systems of chlor-alkali electrolysis without great effort.
• the invention solves the problem by a method for removing silicon compounds from aqueous NaCl sol, wherein
• This buffer container is maintained at a pH between 5 and 8,
• the mixed with ferrous chloride dilute brine is passed with a pH between 1 and 2 in the dissolving vessel.
• the dissolving container may also have a further addition point for iron-III chloride or other trivalent iron ions. For example, it is possible first to meter in 0.3 ppm iron ions into the dilute brine and then 1 additional ppm iron ions into the dissolution vessel.
• the discharged filter cake which contains the supplied iron and silicon, is freed of brine in a filter press, wherein the brine is recycled to the process.
• a stirring device in the dissolving vessel an addition device for the batchwise addition of salt into the dissolving vessel,
• dissolving vessel and buffer container form a structural unit, which are separated by an overflow.
• the structural unit of dissolving tank and buffer tank is preferably designed as a trough.
• the feeding of the thin brine into the dissolving tank is expediently carried out by means of lines arranged at the bottom of the dissolving tank, which have upwardly directed openings in the form of holes or nozzles.
• an air jet or brine jet should be arranged and aligned in the dissolution vessel in such a way that a circulation flow can be generated about a vertical axis.
• FIG. 1 shows a schematic diagram of the process with dissolving and buffer container, the addition devices, and the subsequent filtering of the Dicksole.
• Thin brine 1 with a salt concentration of 220 kg / m 3 is adjusted to a pH of 2 with hydrochloric acid 2. Subsequently, depending on the silicon concentration in the fresh salt, a few ppm of iron-III chloride 3 are metered into the acidified dilute sols. It is important that the pH is sufficiently low, since iron-III chloride is only stable below a pH of 4. If the delivered thin brine already has a pH below 4, the further acidification could also take place after the iron-III chloride addition.
• the acidified and provided with ferrous chloride dilute brine is passed into the dissolving vessel 4, in which there is usually always a sediment of unresolved salt.
• a load of fresh salt is poured into the dissolving tank 4 by the adding device 5, which may be a shovel loader. It is important that this addition takes place within a short time, so for example, a full bucket at a time.
• this fresh salt also contains typical admixtures, for example the silicon mentioned, but also magnesium compounds and sodium carbonate, and also sodium hydroxide, which have a strongly basic action.
• typical admixtures for example the silicon mentioned, but also magnesium compounds and sodium carbonate, and also sodium hydroxide, which have a strongly basic action.
• the iron-III chloride begins to disintegrate and reacts to form iron hydroxide, which precipitates out of the solution. From a purely optical point of view, this change from dissolved and greenish-transparent iron-III chloride to iron hydroxide is noticeable because the brine turns slightly brown. The precipitated iron hydroxide binds the silica and the other silicon compounds per se. It is assumed that this could be a process of adsorption, but the invention is not bound to the correctness of this assumption.
• the dicksole runs with a salt content of about 300 kg / m 3 via the overflow 6 in the buffer tank 7, which is dimensioned so that a pH at which iron hydroxide again in iron illumi- Chloride could react back safely avoided.
• a pH range of 5 to 8 has been proven, above a pH value of 9 it has been observed that the co-precipitated SiIi once again went into solution.
• the buffer tank 7 should be stirred, since during some periods of the dissolution process from the dissolving tank 4 Dicksole with a pH below 4 in the buffer tank 7 overflows. During these periods, the precipitation reaction of the iron and the simultaneous integration of the silicon in the buffer tank 7 takes place and the spatial equal distribution must also be ensured in the buffer tank 7.
• the Dicksole 9 is withdrawn by means of the brine pump 8 and filtered in the filter 10.
• the filter residue 11 consists predominantly of iron hydroxide and silica. This filter residue 11 can be squeezed out in a filter press (not shown) and the dicksole recovered there can be returned to the buffer tank.
• the purified Dicksole 12 is largely free of iron and silicon compounds and can, if appropriate, after further treatment steps, for the NaCl electrolysis are used.
• Dissolving container 4 and buffer container 7 are combined in a tub which separates the two containers by the overflow 6 from each other.
• the tub is open at the top.
• the thin brine 1 is a supply line to which the additions for hydrochloric acid 2 and iron-III chloride is connected, is provided, which leads into a resting on the bottom of the dissolving container or just above Dünnsoleverteiler 15.
• the Dünnsoleverteiler 15 consists of closed at the end of the tubes, are embedded in the holes 16.
• the bores 16 point vertically upwards, but can also be aligned so that they support a circulation flow in the dissolving vessel 4.
• the dissolving tank 4 has as stirring means an air-jet or brine jet 13 which is connected to a blower or other pressure-increasing device and has a nozzle from which air can escape under the liquid surface at high speed. He also has a Dicksoleabzug 17, which is connected to the brine pump 8, which leads the Dicksole 9 to the filter 10, which deduction for cleaned Dicksole 12 and a Has deduction for filter residue 11. [0023] List of Reference Numerals

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Metallurgy (AREA)
• Inorganic Chemistry (AREA)
• Silicon Compounds (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)
• Removal Of Specific Substances (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (2)

Family

ID=40637172

Family Applications (1)

Country Status (9)

Cited By (1)

Families Citing this family (5)

Citations (3)

Family Cites Families (14)

• 2007
  • 2007-12-28 DE DE102007063346A patent/DE102007063346A1/de not_active Ceased
• 2008
  • 2008-12-23 RU RU2010131611/05A patent/RU2476379C2/ru not_active IP Right Cessation
  • 2008-12-23 CN CN2008801255301A patent/CN101925535B/zh not_active Expired - Fee Related
  • 2008-12-23 CA CA2710667A patent/CA2710667A1/en not_active Abandoned
  • 2008-12-23 BR BRPI0821812-9A patent/BRPI0821812A2/pt not_active IP Right Cessation
  • 2008-12-23 EP EP08868150A patent/EP2227436A1/de not_active Withdrawn
  • 2008-12-23 US US12/735,233 patent/US8753519B2/en not_active Expired - Fee Related
  • 2008-12-23 JP JP2010540072A patent/JP5323090B2/ja not_active Expired - Fee Related
  • 2008-12-23 WO PCT/EP2008/011079 patent/WO2009083234A1/de not_active Ceased

Patent Citations (3)

Also Published As

Similar Documents

Legal Events