DE3212120A1 - Process for treating oil-containing sludges - Google Patents

Abstract

In the process for treating oil-containing sludges, and in particular highly oiled metallic sludges, the material to be treated is dissolved with continuous agitation using a variable excess amount of solvent and water at elevated temperature to give a mobile mass, from which the volatile and the flowable constituents are separated off and then the solvents are removed from the water and oil separated off, while the residual solids are dried separately. This process is carried out in three stages in a closed alkaline circulation and uses for example chloride solvents. Both the water and the solvents are in a closed circulation and can accordingly be continuously reused without needing to be disposed of.

Description

Process for treating oily sludge

The invention relates to a method for processing oily sludge and in particular highly oily metallic sludge in which the Material under constant agitation with a variable excess amount of solvent and water is dissolved to a thin liquid mass at elevated temperature, from which the volatile and the flowable components are separated and then the Solvents are separated from the separated water and oil while the retained solids are dried separately and, if necessary, melted down. This method is in particular for the recovery of steel refiners from oil-based grinding and Manufacturing waste determined.

In a known method of the type mentioned (DE-OS 30 11 782) the water is added in vapor form.

With this known method, results are quite useful for an environmentally friendly and largely residue-free processing of oily metallic sludge achieved, so that both the solids as even the oil component can be reused separately from one another without major environmental pollution are. The means used for processing and especially the water can, however cannot simply be drained for reasons of environmental pollution. Rather is at least a neutralization of the wastewater is required. Furthermore, the solvents used are before they can be used again. This known method is therefore relatively costly when considering pollution from polluted Wants to prevent sewage and the like.

Another cost factor results from the relatively high Solvent consumption.

The invention is based on the object of an inexpensive method for the environmentally neutral processing of oily sludge and especially oil-rich sludge to create metallic sludge and the like, with which one residue-free recover solids and oils contained in such sludges and a new one Can supply use.

According to the invention, this object is achieved in a method as described at the outset named genus with the merlunals of the characterizing part of the main claim solved. A preferred development of the invention is the subject of the subclaims.

The invention makes it possible to leave even heavily oily sludge free of residues and environmentally friendly or even environmentally neutral to work up in such a way that the in them un- hold metals, for example, as raw materials for manufacture of master alloys for stainless steels are to be used. Since the solids through the Process according to the invention are almost completely separated from the oil, developed There is practically no soot-containing smoke when the solids are melted down the known roasting or calcining of oily metal sludge occurs and must be cleaned by filter. Such filters are not required for further processing of the substances recovered by the process according to the invention.

It is known that metal parts and the like with chlorinated hydrocarbons to degrease or de-oil. Especially with smaller metal parts that need to be degreased This is possible on surfaces and in the case of metal chips and pieces of metal because usually the oil content is only about 3 to 5%. However, one has largely the use of aqueous solvents (alkaline or acidic) is dispensed with, as one the subsequent chemical reaction (saponification, pickling) was not finished and recovery of the solvent used is either not possible or was uneconomical. In addition, there were wastewater problems that could only be resolved through great effort or have a major environmental impact solved. Previously known methods of this type are described in H. J. Seng et al.

in volume 42 "Disposal through residual material recycling" - ~ recycling in the metal processing industry ", Expert-Verlag, pages 89 to 109. By the invention Processes the disadvantages of the known processes for processing oil-containing Sludge overcome in a simple and economically justifiable manner.

The method according to the invention works in three stages. The one to be de-oiled Sludge is first treated with an alkaline deoiling solution (hereinafter also referred to as "Fissure water" referred to) mixed, preferably in a mixing drum, which is rotated around its horizontal longitudinal axis.

The mixture of sludge to be de-oiled and de-oiling liquor is increased about 4000 (311 K) heated, whereupon cleavage agent is added. In the triggered During the demulsification phase, the splitting agent and oil are separated, i.e. at one total temperature at over 40 ° C the silicate phosphate surfactants added as splitting agents dissolve, which are preferably oil soluble. The split water is separated from the separated oil and fed back to the sludge to be further de-oiled in the next process stage. In this process stage, demulsification takes place again at one temperature of at least 4000 (311 K), in which case cracking agent and oil are again separated. In this case, the non-ionic phosphate-free added in the second stage become Wetting agent combinations and phosphate-free silicate combinations solved. In the third Process stage is withdrawn from the second process stage and split off Oil-separated crack water to correct the residual oil removal of the oily sludge this together with an H20 addition at an increased temperature of at least evwa 4000 supplied. The now separated crack water is fed back into the cycle, while the separated oil can be reused, if necessary. after an additional preparation.

The desired effect occurs at temperatures above approx. 600C (231 K) of the process according to the invention, i.e. takes place in the first process stage a splitting of material (solids) and oil as well as a subsequent demulsification, while in the second stage of the process oil removal followed by demulsification takes place and in the third process stage the residual oil removal. It surrenders a chemical and a procedural reaction. The content of the spinning The drum is split up into a cloudy oil phase, an intermediate layer (unstable Emulsion), a cloudy lye (crack water) and in solids to be recovered (back material).

After the treated material has rested for a short time, the floats cloudy oil phase and can be removed.

The unstable emulsion and the cracked water (cloudy lye) pick them up Reaction in about 24 hours after. The prerequisite for this is that in all three procedural stages Cleaving agent is added. After the unstable emulsion has dissolved and the oil released in the process has also been removed, all that remains is oil-free lye that can be returned to the cycle.

After that, the concentration of this lye to be returned is determined by titration has been established, it is supplemented in a corresponding ratio, so that the lye bath is not exhausted and, accordingly, a bath disposal becomes superfluous.

Since the emulsion is unstable, it can also be with a special separator be processed if there is not enough space for the approximately 24 hours required Settling process is present.

At the end of the processing, a splitting oil with a maximum of 1% water content is obtained after xylene in the oil phase, which is used directly as heating oil in specially approved systems can be incinerated or is suitable for a second refinery without any problems.

The cracked liquor (cracked water) with solvent components of all three Process stages can be reused in a closed cycle and is used to supplement the solvent components discharged from the bath. With Virtually no solvent components are discharged from the fission oil, just as little as with the processed solids. The majority of the solvents remains in the crack water, so that only the one carried out with the crack oil and the residual material Loss on drying of the bath must be supplemented, in a ratio that excludes bath exhaustion. The extraordinarily low concentration required the lye promotes the process carried out according to the invention in a closed circuit.

The method according to the invention thus runs in three stages, namely first in a mechanical stage, then in a chemical-process-technical stage Reaction stage with separation into cloudy oil phase, intermediate layer with unstable emulsion, cloudy lye (crack water) and solids (residue). In contrast to known methods such as ultrafiltration, reverse osmosis, sedimentation, flotation, smoke fumigation and the like the method according to the invention works only with crevice water instead of pure water or purest water, because the liquid goes back into the cycle and only a transport function for introducing the solvents and discharging them of oil shares. The splitting oil obtained is of higher quality than with. all known method achievable.

Even such complex processes as ultrafiltration are still working with water / oil emulsions of up to 50:50, with this extract usually still being disposed of must become.

The absolutely closed circuit proposed by the invention avoids sewage, landfill, waste, exhaust air, neutralization and a failure of Metals in the lye, filter cake, sedimentation residues, emulsion disposal, bath depletion and periodic disposal. The process works economically and is unproblematic away.

The de-oiling takes place with a previously unattainable degree of efficiency and is residue-free. Official rules and regulations on wastewater and Waste disposal need not be considered because the process is a cycle Works residue-free and accordingly no waste water or waste is generated. Only the extracted oil and the purified solid are discharged while the lye used (gap water) can be used again and again.

The oil content of the to be processed with the method according to the invention The starting material is not limited.

The process according to the invention is particularly economical Oil content of the starting material between 50 and 60%. The drawing is schematic an embodiment of the process sequence according to the invention is shown.

The drawing shows that after the residual oil removal (third process stage) a free-flowing residue, i.e. solids in a free-flowing consistency, is obtained, from which exhaust air can be discharged through a cyclone. It can cause drying connect, whereby a dry and oil-free residue is obtained. This can be remelted to form products such as pellets.

Due to the treatment in a closed circuit, the use of solvents can be avoided be roughly halved. In the case of alkaline operation, there is no need for distillation as well as neutralization, which contributes to a further reduction in costs.

Insofar as there are still solids in the lye (a portion of about 0.2 percent by volume), these are determined with the lye or the cracked water returned to the process flow.

The free-flowing residual material obtained after the residual oil has been removed quantitatively an oil content of not more than 0.5% and qualitatively an oil content of practical Zero. This residual material can then be dried and, for example, pressed into pellets will.

Claims (3)

Claim: 1. Process for processing oily and in particular highly oily metallic Schlänsume and the like, in which the to be processed Material under constant agitation with a variable excess amount of solvent and water is dissolved to a thin liquid mass at elevated temperature, from which the volatile and the flowable components are separated and then the solvents are separated from the separated water and oil while one the remaining solids separately dry = net, d u r c h e k e n n z E i c h n e t that it is processed in three stages that alkaline solvents are used and that the water and the solvent are all in one closed Crei.s run and is therefore always reused. 2. The method according to claim 1, characterized in that the oil-containing Sludge in a first, mechanical treatment stage with variable temperature setting of at least 40 ° C crack water (lye) and a preferably oil-soluble crack water combination added and thereby achieved a demulsification for splitting off oil and oil and fissure water is discharged that the material is then in a second, chemical-process- technical Stage again with cracked water and with a water-soluble cracked water combination and a three-stage combination of wetting agents with variable temperature settings de-oiled from at least 40 ° C and the whole thing is demulsified again, so that again oil and crack water are separated, and that the material finally in one third stage for residual deoiling H 20 with a variable temperature setting of at least 400 ° C. and preferably at least 60 ° C. and again added cracking water for correction will and crack water and oil are removed before the so de-oiled free-flowing Material dried and if necessary. Shaped into shaped bodies such as pellets, for example is remelted. 3. The method according to claim 1 or 2, characterized in that the Processing without organic substances (alkaline) when completely closed Solvent cycle is carried out residue-free.