DD266600A1 - METHOD OF RECOVERING AND CLEANING THE NATURAL LIQUID IN MERCERIZING AND LAGGING MACHINES - Google Patents

Abstract

Process for the recovery and purification of caustic soda in mercerising and Laugiermaschinen. The invention relates to the mercerizing and curating process in the textile industry. In the process, a diaphragm is used by which the Na and OH ions migrate into an electrolysis vessel of mercury. The sodium amalgam formed is washed with water in a separate Auswaschgefaess so that caustic soda is formed.

Description

Field of application of the invention

The application is intended for the textile industry. The invention includes "the recovery of caustic soda from thin lauo which is sold to Morcorisiermaschinon et al. Laugiormaschinen in the textile equipment accumulates.

Characteristic dos bekannton state of the art

From the literature (International Toxtil-Hulletin-finishing), the membrane separation process is known. The basis for this process is the different particle size of impurities, ie NaOH.

By suitable and strictly selected membranes, the NaOH can be recovered.

Dioses demonstrations, however, has not gained practical importance, because the membranes and the apperative effort is very large. Furthermore, there is a lack of membranes with appropriate life.

Furthermore, the concentration is described by evaporation. This procedure is currently used most frequently. In this method, the waste liquor is concentrated without special purification, only by evaporation, and then returned to the production process. By this type of concentration all impurities present in the waste liquor are also concentrated so that thickening of the recovered liquor with waste products occurs. However, this concentration of the impurities, which leads after a short 2'nit to uselessness, as well as by high Amohaffungskoston the recovery plants This method is unprofitable.

Concentration by evaporation may be associated with purification of the spent liquor. This is done, for example, by means of a centrifuge. With this centrifuge it is easy to remove impurities based on lint, fibers, dirt particles, fats and oils.

Impurities that are really dissolved or gel-like, are difficult or impossible to remove.

Di 2s are z. As salts (Na ₂ COj), adjuvants, paints, sizing and their degradation products.

With the same disadvantages of the Siebbandfiltor (DD 228423) afflicted.

In EP 0150023 the cleaning is described by means of flotation, whereby by the addition of H ₂ O ₂ gas bubbles are generated, which cause a floating of the impurities, which are mechanically entfen it, due to the specific nature of this process can be removed only the ingredients here , which foam up by flotation or can be settled by chemical degradation.

At the same time, losses of NaOH occur through the elimination of the foamed impurities. The apparatus and space required for this cleaning process is very large.

Object of the invention

The object of the invention is to develop a process which allows reuse of the high purity mercorization liquor, achieving a high level of recovery and low-alkali and environmentally friendly.

Explanation of the essence of the invention

The invention has for its object to provide a recovery ancestor for caustic soda, which eliminates all disturbing dissolved and undissolved impurities and achieves a high degree of recovery. Dio existing waste products are low in alkyd and lead to no burden on the environment.

According to the invention, the object is achieved in that the waste liquor or thin liquor is freed from fluff and other suspended particles by a simple sieve filter (drum sieve for continuous operation). Thereafter, it enters the anode compartment with the anode (eg, nickel).

The anodon space is separated from the cathodia by a diaphragm. This diaphragm has the task, the Allow ionic migration of Na ⁺ + OH "ionone, while retaining any other impurities from the cathode compartment

(Reducing mercury pollution).

In the cathode compartment, the cathode is mercury. When creating a cloktrolyslerspannung it comes as a result of the high Overvoltage of hydrogen at the Quocksilberkatode to a discharge dee Na ⁺ ion and thus to olnor gasless Separation of Na from mercury. This is how oin amalgam is formed. Diose NaHg (sodium amalgam) is then washed out in an oil-sapural Au & washing vessel so that caustic soda (NaOH)

disfigured.

This NaOH can be returned to the Morcorisier- or Laugiermaschine after adjusting the required concentration

become.

To improve the Effizienzos dos method, it is also possible, instead of the washout leachate, which only

pre-cleaned, to use,

This leads to a rapid concentration of the sodium hydroxide solution and a saving of electrical energy. Since O _{2 occurs} at the anode and H ₂ in the wash-out vessel during electrolysis, gases can be used for other purposes

become.

For example, they can be used for * auxiliary heating. Ausführungsbelsplel An amalgam Elektrolysogefäß is rebuilt so that the mercury electrode through a diaphragm before Impurities dor waste liquor is protected. Dio size of the electrolysis vessel must be in its dimensions of the rejection which is to be electrolyzed,

met.

After this change and the onset of the anode (eg nickel) the required electrolysis voltage is applied. The amalgam formed is washed out as usual and recycled after adjusting the required concentration.

Claims (3)

1. A process for the recovery and purification of sodium hydroxide solution on Mercerlsler- and Laugiermaschinen, the Voreinlguny for removing lint and other Schwooeteilen via a simple sieve filter, characterized in that the Na ⁺ and OH ~ ions migrate in an electrolysis vessel through a diaphragm , wherein the interfering impurities are retained and formed by the gasless deposition of Na on the Qnecksilberkatode a sodium amalgam, which is washed in a separate Auswaschgefäß with water, so that caustic soda is formed, which returned after setting the required concentration to the Laugier- and Mercerisiermaschine becomes. 2. The method according to claim 1, characterized in that waste liquor is used instead of waste water, which is only pre-cleaned. 3. The method according to claim 1, characterized in that the released during the electrolysis at the anode O ₂ and m Auswaschgofäß resulting H2 can be used for additional heating.