JPS645923B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recovery and reuse method for recovering and reusing oils and fats attached to metals from among oils and fats used during the processing of metals.

Rolling and drawing of iron plates, iron wire, pipes, etc.
Oils and fats are often used to smoothly perform metal processing such as cutting, polishing, and hardening metals. These oils and fats naturally adhere to the metal surface, but because they cause inconvenience in subsequent steps, they must be removed by washing.

Conventionally, the most common method for removing fats and oils is so-called alkaline cleaning. In this case, the fats and oils are partially decomposed by the alkali, and the remainder produces an emulsified waste liquid. The disadvantages of this method are the relatively long time required for cleaning, the treatment of waste liquid after oil and fat removal, i.e. BOD,
There are troublesome issues such as COD reduction processing and PH adjustment.

Therefore, a method of cleaning using an organic solvent such as perchlorethylene, trichlorethylene, or 1,1,1-trichloroethane has also been proposed. This has improved the rate of removal of oils and fats adhering to metals, but in general, mixtures of organic solvents, especially chlorinated solvents, and oils such as machine and work oils are completely removed, despite the large difference in their boiling points. Separation is not easy. For example, if a mixture of a solvent such as perchlorethylene or trichlorethylene and machine oil is separated by simple distillation under normal pressure, the boiling point will rise when the solvent contains about 30% of the low boiling point component. If you heat this further, it will reach the deterioration temperature of the oil.
The temperature exceeds 130℃, and in some cases exceeds 150℃.

Additionally, machine oil that contains approximately 30% solvent is generally of no use, so it is incinerated as waste oil. That is, of the oil used in the processing of metals, the portion that adheres to the metals and is carried away is considered to be irretrievable.

The present inventors have discovered that in metal processing, that is, metal cutting, drilling, rolling, drawing, pressing, quenching, annealing, surface protection, etc., coatings on the metal for lubrication, cooling, rust prevention, and other purposes, Also, we focused on the surprisingly large amount of oils and fats that adhered, and as a result of investigating ways to recover and use them effectively, we found that when methylene chloride is used as the solvent, its unique characteristics make it difficult to carry out certain distillations. It has been discovered that oils and fats can be recovered with high purity and reused by this method, and the present invention has been achieved. That is, the present invention dissolves and removes fats and oils that adhere to metals during processing by washing with methylene chloride, and then subjects the methylene chloride containing the fats and oils to atmospheric distillation and vacuum distillation at a temperature of 120°C or lower. By sequentially separating and recovering the solvent, the methylene chloride contained in the distillation residue is reduced to 5% by weight or less, and the recovered methylene chloride is
This is a method for recovering and reusing oils and fats for processing metals, characterized in that the oils and fats for processing metals are subjected to the above-mentioned cleaning, and the distillation residue is reused in the above-mentioned processing step after being supplemented with new oils and fats.

In the present invention, first, new oils and fats are added to the distillation residue after recovering methylene chloride by distillation means from methylene chloride in which oils and fats have been dissolved after being subjected to solvent cleaning (hereinafter also simply referred to as an oil and fat solution). In addition, after reducing the methylene chloride content in the resulting mixed oil to a level that can be used as an oil or fat used in the processing of metals, the oil or fat can be used without waste by subjecting it to the processing. becomes possible.

Furthermore, in order to carry out the present invention efficiently, it is necessary to devise a method for distilling the oil and fat solution and to reduce the amount of solvent contained in the distillation residue as much as possible. Generally, by simple distillation under normal pressure, approximately 30% of the solvent cannot be recovered at temperatures below 120°C, taking into account the deterioration temperature of the oil. In this case, for example, if the remaining amount of reusable solvent is 6%, it is necessary to dilute it five times or more with new oil. Generally, the amount of oil recovered is small compared to the total amount of oil used in processing, and it is also necessary to compensate for spills and other losses during processing, so adding this amount of oil is Although it does not break the balance, it is preferable to take measures to sufficiently separate the solvent. Therefore, the present invention uses methylene chloride, which has a low boiling point and good distillation separation properties, as a solvent for cleaning fats and oils, so that the waste liquid obtained by the above cleaning can be heated to 120°C, where there is less deterioration of fats and oils. Atmospheric pressure distillation and reduced pressure distillation are performed sequentially under practical conditions at the following temperatures to reduce the methylene chloride in the distillation residue to 5% by weight or less. The methylene chloride is used for cleaning, and the distillation residue is used to replenish new resin. This enables a process that consists of reusing the material in the processing process.

The present invention will be specifically explained below with reference to FIG.
In the figure, reference numeral 1 indicates a metal processing process, and conceptually shows that processing oil is appropriately supplied from an oil sump 2. 3 is an apparatus for cleaning oils and fats adhering to metals with a solvent and carrying out simple distillation under normal pressure. That is, the metal workpiece 5 with oils and fats adhered to it is immersed in methylene chloride in the solvent cleaning tank 4 to dissolve and remove the oils, and then the metal workpiece is pulled up to the space 6 above the solvent surface and methylene chloride vapor is removed. exposed to steam for cleaning and then removed. The methylene chloride vapor is condensed on the metal workpiece or by the cooling pipe 7 and falls into the solvent bath 4. Therefore, methylene chloride containing a trace amount of oil and fat in the solvent tank 4 increases and moves to the evaporation tank 8 by overflow. In the evaporation tank, the methylene chloride solution is heated by a suitable heating means 9, and solvent vapor is generated and supplied to the space 6 according to the so-called simple distillation principle. In this way, methylene chloride containing highly concentrated oils and fats is accumulated in the evaporator tank 8, and the evaporator is supplied to the evaporator 10 of the vacuum distillation apparatus through the pipeline 20, and the pressure is reduced by an ejector or other means 11. and
Helps evaporate methylene chloride. The evaporated methylene chloride is liquefied by a condenser 12 or the like, and is recovered into a tank 13 via a pipeline 21. This is recycled by pipeline 22 for the cleaning process. On the other hand, the distillation residue is appropriately returned to the oil sump 2 of the metal processing process by a pipeline 23. Here, new oil is supplied from 24, and the methylene chloride concentration in the oil reservoir 2 is maintained within the permissible concentration range during metal processing. Incidentally, the insufficient solvent can be replenished from 25 in the figure. It is also optional to carry out a dehydration and drying process in the middle of each pipeline.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the process of the present invention.
In the figure, 1 indicates a metal processing process, and 2 indicates a reservoir for oils and fats used during metal processing. 3 is a solvent cleaning device, 4 is a cleaning tank, 5 is an object to be cleaned, 8 is a steam tank,
10 represents a steam pressure evaporator, and 13 represents a tank.

Claims (1)

[Claims] 1 The fats and oils that adhere to metals during processing are dissolved and removed by washing with methylene chloride, and the methylene chloride containing the fats and oils is chlorinated by sequentially applying atmospheric distillation and vacuum distillation at a temperature of 120°C or less. By separating and recovering methylene, the methylene chloride contained in the distillation residue is reduced to 5% by weight or less, and the recovered methylene chloride is subjected to the above-mentioned washing, and
A method for recovering and reusing metal processing oils and fats, characterized in that the distillation residue is reused in the above-mentioned processing step after being replenished with new oils and fats.