JPH0931486A - Purification of rolling oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for purifying a rolling oil, by treating a rolling oil discharged from a metal rolling equipment, containing foreign matters such as fine metal powder, scum and a hydraulic fluid, etc. and efficiently removing the foreign matters to purify the rolling oil into one having required rolling performances. SOLUTION: In treating an emulsion type rolling oil discharged from a metal rolling equipment containing foreign matters, removing the foreign matters and recycling and using the purified rolling oil, the rolling oil is purified by passing through the processes shown below. (1) A floating and separating process for treating the rolling oil occurring from the rolling equipment by a floating and separating means to separate a floating substance consisting essentially of a working fluid and scum. (2) A centrifugal separation process for treating the floating substance, obtained by the floating and separating process, by a centrifugal separator to separate the sludge component and a liquid phase component. (3) A filtering process for treating the rolling oil flowing out from the floating and separating process by a filtering means to separate and remove a solid content such as metal powder, etc., in the rolling oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying rolling oil, and more particularly to a method for purifying by removing various foreign matters in emulsion rolling oil.

[0002]

2. Description of the Related Art Emulsion type rolling oil is mainly used as rolling oil for rolling thin metal sheets or for making cans.
The emulsion type rolling oil referred to in the present invention is a 1 to 20% oil-in-water emulsion obtained by adding and blending an oiliness improver, an antioxidant and the like to a suspension prepared by dispersing oil in water with an emulsifier or other substance. It means liquid (hereinafter referred to as rolling oil). The rolling oil includes fine metal powder generated during rolling, scum content produced by the various organic compounds added to the rolling oil over time, and hydraulic oil used in rolling equipment. Various foreign substances are mixed.

Since this rolling oil is used in a large amount and is expensive, it is circulated and used in a closed system. Therefore, if the above-mentioned foreign matter is not always removed, the content gradually increases, the performance as rolling oil deteriorates, and further it has a bad influence on the rolling process such as surface defects of rolled products. Several methods have been proposed to date for removing the foreign matter, and a representative method thereof is the method proposed in Japanese Examined Patent Publication No. 4-64723.

The summary of the above method is as follows. That is, the rolling oil returned from the rolling equipment is separated by flotation, and the floating material with a low specific gravity, such as floating hydraulic oil and scum, is treated with a centrifuge, and mainly metal powder and sludge are added to the heavy side. The working oil and the like are separated and collected on the light side of the mixture. On the other hand, the rolling oil extracted from the lower layer of the flotation tank, from which the substance with a low specific gravity is removed, is processed by another centrifuge to separate and remove metal powder and sludge, and then rolled as purified rolling oil. This is a method of circulating supply to equipment.

The applicant of the present invention has the above-mentioned Japanese Patent Publication No. 4-64723.
As a result of diligent examination of the method proposed in the issue, it was found that this method has the following problems. That is, in the above method, the rolling oil from which the floating substances have been separated and removed in the flotation tank is entirely processed by the centrifuge, but since the fine metal powder is removed, a high acceleration (G ), The emulsion particles in the rolling oil are broken under the action of this high G pressure, and the performance required as the rolling oil is reduced.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and is generated from a metal rolling facility containing fine particles of metal, scum, and foreign matter such as hydraulic oil. It is an object of the present invention to provide a method of treating a rolling oil to remove the foreign matter efficiently and purifying the rolling oil as a rolling oil having a required rolling performance.

[0007]

[Means for Solving the Problems] When emulsion type rolling oil generated from metal rolling equipment containing foreign matter such as metal powder, hydraulic oil and scum content is treated, and the foreign matter is removed and recycled, A method for purifying rolling oil, comprising a process. (1) A flotation separation step in which rolling oil generated from rolling equipment is treated by a flotation separation means to separate hydraulic oil and a floating substance mainly composed of scum. (2) A centrifugal separation step of treating the floating substance obtained in the floating separation step with a centrifuge to separate it into a sludge component and a liquid phase component. (3) A filtration step of treating the rolling oil flowing out from the floating separation step with a filtering means to separate and remove solid contents such as metal powder in the rolling oil.

[0008]

[Function] The emulsion type rolling oil containing foreign matter such as metal powder, hydraulic oil and scum is first subjected to floating separation treatment,
Components with low specific gravity such as hydraulic oil and scum are removed.
At this time, part of the metal fine powder also adheres to the scum and is removed as a floating material. Next, the rolling oil is subjected to a filtration treatment, and solid components such as fine metal powder are mainly captured and removed on the filter medium.
As described above, by treating various foreign substances in the emulsion type rolling oil by a method in which the separating and removing means suitable for each property is optimally combined, the rolling oil can be purified without destroying the emulsion particles.

[0009]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram of an embodiment of the present invention. In the figure, reference numeral 1 denotes a rolling facility including a thin plate rolling machine made of aluminum, stainless steel or the like or a can making machine. Reference numeral 2 is a return line for rolling oil (hereinafter referred to as dirty rolling oil) generated from rolling equipment used in a rolling mill or the like, and its downstream end is connected to a dirty oil tank 3. This dirty rolling oil contains fine particles of metal generated during rolling, hydraulic oil used in a rolling mill and mixed in, and scum generated by oxidation of various organic compounds added to rolling oil as foreign matter. To be done.

The rolling oil in the dirty oil tank 3 then flows into the floating separation tank 4. As the model of the floating separation tank,
There is no particular limitation as long as it can float and remove components with low specific gravity such as hydraulic oil and scum in rolling oil, but a sloping plate type flotation separation tank commonly used for removing oil from oil-containing wastewater is particularly preferable. Is suitable. The dirty rolling oil descends in the stack composed of the inclined plates 5, and the working oil contained therein,
Efficiently separates components with low specific gravity such as scum and leaves the bottom of the flotation tank.

The floating component having a low specific gravity concentrated near the liquid surface of the floating separation tank 4 is selectively taken up by a float type skimmer 6, flows down to a floating substance tank 7, and is temporarily stored. Next, the floating component is supplied to the centrifuge 9 by the pump 8. As the centrifuge, a centrifuge capable of separating into three phases of fine metal powder, water in rolling oil and oil such as hydraulic oil is most preferable, but a centrifuge may be separated into two phases of solid and liquid. In any case, a high-speed rotating separation plate type centrifugal separator is particularly suitable.

The solid content mainly composed of the separated metal powder is
The liquid phase component discharged to the sludge tank 10 and composed of the water content of the hydraulic oil and the rolling oil is discharged to the recovery liquid tank 11. When the amount of the liquid phase component is large, it is possible to further separate water and the like and return it to the dirty tank for reuse.

The rolling oil leaving the lower part of the flotation tank 4 is then supplied to the filter 20 by the pump 12. The filter 20 is not particularly limited as long as it is a type that captures solids such as metal powder in the rolling oil, but permeates emulsion particles, but a suitable sheet-shaped filter medium can be optionally used. Moreover, a horizontal filter plate type filter, which has many advantages such that the filtration pressure can be appropriately increased, is particularly suitable.

In the figure, 13 is a horizontal filter plate which is laminated in multiple stages, and 14 is a sheet-like filter medium which is inserted between the filter plates and is automatically replaced by a filter medium replacement means (not shown). The dirty rolling oil enters each stock solution chamber 16 through the stock solution header 15, solids such as metal powder are trapped on the filter medium 14, and water and emulsion oil components constituting the emulsion type rolling oil are filtered by the filter medium 14. Permeate into the filtrate chamber 17,
It is stored in the clean oil tank 19 via the filtrate header 18. Then, the pump 21 circulates and supplies it to the rolling equipment 1 via the pipe line 22 as clean rolling oil which has been cleaned.

[0015]

EFFECTS OF THE INVENTION According to the present invention having the above-described structure and action, a method of optimally combining the separating and removing means suitable for each property of the foreign matter in the emulsion type rolling oil circulated and used in the rolling equipment is used. By treating it, the emulsion particles can be purified without breaking it, so that the required performance as a rolling oil can be maintained, and further the rolling oil can be used for a long period of time without adversely affecting the rolled product. .

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

[Explanation of symbols]

1; rolling equipment, 2; pipeline, 3; dirty oil tank, 4;
Flotation tank, 5; inclined plate, 6; skimmer, 7; float tank, 8; pump, 9; centrifuge, 10; sludge tank, 11; recovered liquid tank, 12; pump, 13; horizontal filter plate, 14: filter medium, 15: stock solution header, 16; stock solution chamber,
17; filtrate chamber, 18; filtrate header, 19; clean oil tank, 20; filter, 21; pump, 22; pipeline.

Claims (1)

[Claims] 1. When an emulsion type rolling oil generated from a metal rolling equipment containing foreign matter such as metal powder, hydraulic oil and scum content is treated, and the foreign matter is removed and reused,
A method for purifying rolling oil, comprising the following steps. (1) A flotation separation step in which rolling oil generated from rolling equipment is treated by a flotation separation means to separate hydraulic oil and a floating substance mainly composed of scum. (2) A centrifugal separation step of treating the floating substance obtained in the floating separation step with a centrifuge to separate it into a sludge component and a liquid phase component. (3) A filtration step of treating the rolling oil flowing out from the floating separation step with a filtering means to separate and remove solid contents such as metal powder in the rolling oil.