DD295171A5 - METHOD FOR OBTAINING A SOLID CONCENTRATE FROM LATEX-BASED RECEIVABLES - Google Patents

Abstract

The invention relates to a process for obtaining a solid concentrate from latex-containing aqueous liquors, which can be added proportionally to coating compositions or can be disposed of without violating environmental protection regulations. The process according to the invention is based on the treatment of the liquor with a vacuum evaporator under conditions which avoid cross-linking of the latex and the difficulties caused thereby. Fig. 1 {latex; Fleet; Coating; Evaporator; Environmental Protection}

Description

When cleaning the evaporator tubes, the caking of the latex is prevented by the discharge of subsets from the Evaporator and brushes of pipes at the same time fresh water is refilled. Dia cleaning is thus much easier

and the time required minimized. The vapor condensate obtained during the evaporation process can be used as needed for more

Be used for washing purposes or discharged into the sewage. By applying a vapor compressor (jet apparatus), a favorable utilization of the Heizdampfenergie. By

appropriate level control in the feed tank can be ensured that no false air gets into the evaporator, which would lead to strong foaming and thus disruption.

The accumulated as a result of sedimentation solid concentrate is withdrawn and collected before it in the mixing process for Preparation of coating compositions is included. If, for operational reasons, no return to the coating process takes place, the obtained, on a fraction

Concentrate concentrated concentrate of the original volume, without representing a pollution of the environment with pollutants. Furthermore, with the described solution, the rotting process which had previously started after 2 to 3 days and the associated odor nuisance was counteracted.

embodiment

The Beiiiebsrückstand 1, an aqueous liquor with about 0.2-1% solids part. is collected in a container 2. The solid consists of about 20% PVAC latex and about 80% of chalk and pigment.

By present in the evaporator system 3 vacuum of about -8OkPa be continuously drawn from the container 2 via a pipe and tubing about 600-800kg / h residue in the circulation evaporator 3 and there evaporated at a temperature of 50- 60 ⁰ C. , The vapor passes through a separator 4 in a condenser 5 is condensed there and flows continuously through the discharge nozzle of the vacuum pump β in the wastewater 7. By optical control of the level in the container 2 and in the separator 4, the feed rate is regulated with a ball valve. The Heizdampfzufuhr 8 to the circulation evaporator 3 via a vapor compressor 9. By using the Brüdendampfes for Baheizung the specific steam consumption of about 0.5 kg / kg can be guaranteed.

After about 6h evaporation process about 4 pounds of latex concentrate with about 20-30% solid fraction are deducted at shut off evaporator system via the common drain line 10 for the circulation evaporator 3 and the separator 4. As a result of the sedimentation, the solid collects preferentially in the bottom region of these two plant parts 3 and 4. The solid concentrate is collected in a transport vessel 11 and admixed in the mixer 12 to the primer mass. In this case, a proportional addition without quality impairments of the primer composition is possible.

If, for operational reasons, there is no supply for mixing, e.g. when changing the color of the coating, the concentrate is safe to deposit in the usual way. The disposal on special landfills, combined with additional transport, is not required. Environmental protection moods are not mislaid.

Claims (1)

Process for obtaining a solid nitrogen concentrate from latex-containing residues in aqueous liquors obtained during the operation and cleaning of feed systems, wherein the obtained, dumpable solid concentrate can be admixed proportionally with primer compositions for latex-based coatings, characterized in that the latex-containing liquor is applied to the evaporator surfaces of a vacuum evaporator ( 3) is concentrated in a continuous operation to a solids content of 5 to 30% and in a discontinuous process, the solid concentrate is withdrawn, the evaporator surfaces are always completely covered by liquid or the interruption of the complete liquid lavage is shorter than that to form a Latex film necessary time. For this 1 page drawing Field of application of the invention The invention relates to a process for obtaining a Festetoffkonzentrates from latex-containing residues in aqueous liquors, which can be used or deposited in the production of coating compositions for floor coverings, artificial leather and similar products. Characteristic of the known technical readings In the production of floor coverings, artificial leather, etc. on the basis of latex-containing coating systems accumulate residual liquors whose preparation is laden with significant problems. The introduction of untreated residual liquors contradicts the requirements of environmental protection. The possible deposit on special landfills is associated with high costs, in particular the necessary transport capacity, the property of these fleets, after a few days cause strong odor nuisance due to rot, represents an additional disadvantage. Some users practice chemical precipitation processes for enrichment and separation of the solids. For example, DD-WP134952 describes a precipitation method with the addition of sawdust. However, this will only create better conditions for landfilling without solving the fundamental problems. Until now, it was not possible to supply the technologically related latex-containing residues for an economically advantageous use, since these residues were due to their properties no practicable extraction technology accessible. The strong tendency to sedimentation and crusting, variations in the liquor composition in terms of latex, filler and pigment content and the relatively rapid transition to putrefaction prevented the use of known recovery processes. Particularly troublesome for the preparation, the principal disadvantage of the latex-containing residual liquors was to block, bond and cough up all contacted surfaces and fittings during storage, filling, transporting and depositing. The inherent nature of the coating latices was therefore always associated, in practical consequence, with the inability to recover the economically valuable raw materials or unacceptable consequences of landfilling. Object of the invention The aim of the invention is the avoidance of raw material losses in the coating industry while saving storage and transport capacity. Furthermore, compliance with the requirements of environmental protection should be ensured. The disadvantages of the prior art should be remedied. Essence of the invention The object of the invention is to recover from latex-containing residual liquors a solid concentrate which Grundierungsmaseon latex-based can be added proportionally. The product obtained should be landfillable in the event that no further processing in the coating industry should take place. According to the invention, this object is achieved by a method in which the solids content of latex-containing residual liquors incurred in the operation and cleaning of feed systems is enriched so that an approximately spade-resistant solid concentrate is obtained with a solids content of 5-30%. It is essential that this concentrate never gets into conditions during the entire extraction technology, which facilitate or facilitate its drying or crosslinking. For this purpose, the latex-containing liquor is concentrated in a continuous process on the evaporator surfaces of a vacuum evaporator and withdrawn in a discontinuous process, the enriched concentrate. The evaporator surfaces are always completely surrounded by liquid. Unavoidable interruptions of the liquid rinsing are to be measured in mrer period of time that the necessary time to form a drying latex film is not achieved. In practice, by appropriate temperature control and constant level, the encrustation of evaporator is prevented.