JPS59146913A - Method and device for recovering sodium sulfide from lime pit treatment circulating water for leather tanning work - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for recovering dissolved sodium sulfide from reflux water from a tannery and continuously and automatically delivering it to the associated plant.

One of the basic processes in leather tanning is a process called lime pit, whose purpose is to remove hair and bulges from the raw hide to prepare it for the next process. That's true. In such a process, the raw hide before hair removal is immersed in a drum or paddle wheel containing lime water containing sodium sulfide and surfactants as essential additives. Such treatment causes the hair root to swell and partially detach from the hair bulb.

This processing solution is then discharged, but
It has a high pH value (approximately 12) and contains a significant amount of organic matter in dispersed or dissolved form (BO
Because of its high D value), it was a troublesome by-product for workers and could not be discharged into any waterways or urban water catchments. For this reason, it is essential to adjust the content of the treatment solution before discharging it and to recover the sulfurized IJium content. Various methods have been proposed for treating such waste liquid, but none of them are free from drawbacks. For example, the decant method is known, in which the heavy part of the treated solution is precipitated and the light part is suspended, but this method cannot remove the large amount of organic emulsion contained in the solution, and the decanted solution does not become totally heat clarified. The organic matter content remains high (
BOD value is high). These problems worsen with each cycle and begin to impede normal processing in Limebit, so the processing solution must usually be discarded after three cycles or less. Another known treatment method is reverse osmosis, in which sodium sulfide calcium hydroxide is removed and passed from the treatment solution to the purification water, leaving a colloidal solution. The minute and large diameter minutes are separated. Although it is possible to obtain a high-quality sulfurized IJ solution with this method, the equipment used to carry out this method has the disadvantage that both equipment costs and operating costs are large. In addition, the infiltrator must be replaced periodically, and there remains the problem of dispersing filth containing multiple layers of organic matter and putrefying substances due to backwashing.

The object of the present invention is to provide a method and apparatus for recovering dissolved sodium sulfide from reflux water in tanning operations without causing the above-mentioned disadvantages.

A further object of the invention is to obtain the sodium sulfide solution and the surfactant in a virtually completely reusable state, with low operating and equipment costs;
Another object of the present invention is to provide a method and apparatus for recovering sodium sulfide from reflux water in a leather tanning operation, which makes it possible to conveniently and economically recover organic matter.

In the present invention, the above and other objects are achieved by the following method. That is, this method uses a composite porous material having a water permeability of 1 to 5 Darcy to absorb the reflux water from the tanning operation, which mainly contains sodium sulfide, calcium hydroxide, and organic matter in a dispersed or dissolved state, produced by the lime bit process. It consists of a process of performing filtration using a powder layer, such as a fossil powder layer, as a filtration layer.

Through such filtration treatment, the reflux water is completely and easily purified by the mechanical filtration and adsorption effects exerted by the pore surfaces of the porous material powder. The method of the invention forms a continuous layer of porous material powder on the outer surface of a rotating drum submerged in the solution to be treated, preferably
It can be rationally industrialized by performing a suction action between 5507I and Hg. The layer of porous powder 11 is periodically replaced with a new one by depositing a highly concentrated solution of porous powder onto a drum.

? The vacuum applied to the processing solution during the IM step tends to generate hydrogen sulfide vapors and gases dissolved in the solution. Since the solution to be purified is rich in surfactants, these vapors and gases come out in the form of bubbles. In order to prevent such bubbles from being drawn into the vacuum pump, the solution to be purified and the filtered solution in the present invention are treated with an antifoaming agent, but also drawn in using a rasching ring. There is.

Next, an embodiment of the present invention will be described with reference to the drawings, which schematically show a specific embodiment of the present invention and are merely for illustrative purposes and are intended to be limiting. It's not a thing.

Furthermore, the structures of the individual components of the illustrated apparatus are well known to those skilled in the art, and detailed explanations are omitted.

In the figure, sulfurization +
) The solution to be purified containing calcium hydroxide and dispersed or dissolved organic matter is conveyed to a storage tank 1 and pumped via a motor-driven pump 2 to a feeder 6 to reduce turbulence and remove the The coalescence phenomenon of fatty substances is promoted. The solution to be purified then flows by gravity into a tank provided with a rotating drum 4 due to overflow. A porous material powder layer 4b having a water permeability of 1 to 6.5 Darcy is formed on the outer surface of the rotating drum 4.

The solution is drawn into the rotary drum 4 through the porous powder layer 4b by the vacuum pump 9 and into the tank 6.

The solution is then pumped from there via a self-starting motor-driven pump 7 to a storage tank for titer correction and for reuse in the tanning operation.

Hot air and/or bubbles escaping to the upper part of the recovery tank 6 are drawn in by a multilayer mechanical sieve 8 to prevent mixing of hydrogen sulfide and/or surfactant vapor inside the vacuum pump 9.

Floating organic components, that is, components with a size that does not pass through the porous material powder M4b, are deposited on the outside of the porous material powder layer 4b, and are removed into the container together with the thin porous material powder layer by the movable blade 10 having a side fine advance mechanism. 5 and can be used commercially as nutrients and fillers.

The method according to the invention for recovering sodium sulfide dissolved matter from reflux water in tannery operations offers a number of advantages compared to the known methods mentioned above. For example, it is possible to maximize the use of solutions without technical losses, it is possible to reuse waste organic matter mixed with porous material powder, and it is possible to automate equipment to continuously Operation is possible and can be carried out without adding any kind of additives and flocculants to the solution.

[Brief explanation of drawings]

The figure is a schematic diagram of an apparatus W for recovering sodium sulfide from lime bit treatment reflux water in a leather tanning operation, showing an embodiment of the present invention. 1... Storage tank 2... Pump 6... Feeder 4... Rotating drum 4b... Porous material powder layer 5... Container 6... Recovery tank
7...Pump 8...Machine 11ifi
9... Vacuum pump 10... Movable blade application person Giovanni Dipardi transformation theory
Person -1t1′! f! Shi Oka 1) Hidehiko's Procedural Amendment (f. March 13, 1948 - ``Indication of Case 1 by Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office. 9 years since Showa 9) Relationship with Case No. 344 in Application No. 22 J ,: ,'r% 4.1 hi'・, (missing 4,
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Claims (1)

[Scope of Claims] 1) A method for recovering IJum (sulfurized from lime pit treatment reflux water in a leather tanning operation), wherein said reflux water has a water permeability of, for example, between 1 and 6.5 Darcy. Leather tanning according to claim 1, characterized in that lime pit treatment reflux water is formed in a tanning operation, characterized in that it comprises the step of filtering through a layer of bonded porous material powder having: Method for removing sodium sulfide from lime pit treatment reflux water in operation. 6) Recovery of sulfurized IJium from lime pit treatment reflux water in a tanning operation according to either the first or second item of the patent, characterized in that the filtration is carried out under suction action. How to. 4) A method for recovering sodium sulfide from lime pit treatment reflux water in a tanning operation as claimed in claim 6, characterized in that the filtration is carried out at a pressure between 250 Hg and 550 Hg. Method. 5) The reflux water before and after the filtration treatment? Patent dN-required range item 1~
A method for recovering IJum (sulfurized) from lime pit treatment reflux water in a leather tanning operation according to any one of paragraphs 4 to 4. 6) Claims characterized in that the porous material IF powder layer used for the filtration is periodically replaced by depositing a porous material powder solution of i% concentration on the porous material powder layer. A method for recovering sodium sulfide from lime pit treatment reflux water in a leather tanning operation according to item 2. 7) An apparatus for recovering sodium sulfide from lime pit treatment reflux water in a tanning operation, comprising a storage tank 1, a supply/decant mechanism 6, and a system for transferring the solution to be treated from the storage tank 1 to the A tank mechanism comprising a supply mechanism 2 for supplying to a supply-decant mechanism and a rotating drum 4 having a porous material powder layer 4b formed on its outer periphery having a water permeability of, for example, between 1 and 6.5 darcys. , a vacuum pump 9 that brings the inside of the rotary drum 4 into a negative pressure state, a movable blade 10 equipped with a micromeasuring advance mechanism for the outer surface of the rotary drum 4, and between the rotary drum 4 and the vacuum pump 9. An apparatus for recovering sodium sulfide from limebit processing reflux water in a tannery operation, characterized in that it consists of a recovery tank 6 and a multilayer mechanical sieve 8.