JPH0380525B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for capturing iron in an oil suspension using an electromagnetic filter.

As is already known, electromagnetic filters are
A multilayer mesh filter made of thin magnetic wires is placed in the magnetic field of an electromagnet, and raw water containing magnetic particles such as iron is passed between the thin magnetic wires, so that the magnetic particles are magnetically captured by the thin magnetic wires. It is used for iron removal from hot rolling wastewater from steel materials, steel wastewater such as converter dust collection wastewater, other industrial wastewater, and domestic wastewater, recovery of useful substances, and pollution prevention.

By the way, in steel cold rolling, a steel rolling coolant (oil suspension) in which 1 to 6% of oil such as mineral oil or beef tallow is suspended in water is used for cooling and lubrication, but iron particles When the above-mentioned electromagnetic filter is used to remove iron, 3 to 8 times as much oil as iron is captured, and as the oil is used in circulation, the oil concentration gradually decreases. Materials of the 14th meeting of the academic society (1972)
(published on March 7, 2016), using the electromagnetic filter described above to remove iron from oil suspensions would result in inconvenient results. was not used, and the oil suspension was currently disposed of in a relatively short period of time.

The present invention has been made in view of the above, and involves passing an oil suspension between magnetic thin wires magnetized by an electromagnet, and magnetically trapping iron particles contained in the oil suspension on the magnetic thin wires. , a method for capturing iron in an oil suspension, characterized in that the magnetic nanowires are not washed until the ratio (weight ratio) of captured iron particles to the magnetic nanowires exceeds at least 0.1, This allows the oil suspension to be reused for long-term cold rolling by reducing only the oil capture rate without reducing the iron particle capture rate. The present invention was completed due to the recognition of the following phenomenon regarding the capture of iron particles in oil suspensions. In other words, when an oil suspension containing iron particles is passed between magnetized magnetic thin wires, the iron particles and oil are similarly captured by the magnetic wires for a certain period of time after passing, but after a certain period of time, It was discovered that while the rate of oil capture suddenly decreases, the rate of iron particle capture only gradually decreases, but does not suddenly decrease. Figure 1 shows a multilayer mesh filter using SUS430 (ferrite stainless steel) as the magnetic wire (the weight of the magnetic wire is 2.70 kg), and its diameter is 0.18 kg.
The experimental results of the change in oil capture rate in an electromagnetic filter with a magnetic field strength of 3 KOe and a magnetic field strength of 3 KOe are shown in the graph. As a stock solution, an oil suspension was used in which 51,000 mg of oil was suspended in water and 254 mg of iron particles were added thereto. The captured iron weight ratio on the horizontal axis in Figure 1 represents the ratio of the weight of the trapped iron particles to the weight of the magnetic thin wire (2.70 kg), which is the weight of trapped iron/magnetic thin wire weight.

In addition, the oil capture rate on the vertical axis is expressed as a percentage of the oil content that is captured relative to the oil content that has passed through the magnetic thin wire, and is calculated as follows: captured oil weight/undiluted oil concentration x passing flow rate x 100.

As can be seen from the figure, when the captured iron weight ratio increases to 0.1, the oil capture rate decreases to less than 1%. When the captured iron weight ratio is low, as shown in Figure 2, as the iron particles are attracted to the magnetic wire a by magnetic force, the oil droplets attached to the iron particles are also captured at the same time. However, when the captured iron weight ratio exceeds a certain value, as shown in Figure 3, even if the oil droplets are captured, more and more of the oil gradually separates from around the magnetic wire a. It is presumed that this is the case.

A specific example of cleaning will be explained according to the oil suspension treatment system shown in FIG. 4. In the figure, 1 is an electromagnetic filter, 2 is an electromagnet thereof, and 3 is a magnetic thin wire magnetized by the electromagnet. The oil suspension containing iron particles passes through a water supply pump 4, a water supply pipe 5, and a valve 6, is supplied into the electromagnetic filter 1 from the bottom thereof, passes between the magnetic thin wires 3, and is discharged through a valve 7.
8 is a backwash water storage tank provided on the secondary side of the electromagnetic filter 1, 9 is an air compressor, 10 is an air tank, 11 is an air supply valve, 12
13 is a backwash water discharge valve provided on the primary side of the electromagnetic filter 1, 13 is a backwash water supply valve to the electromagnetic filter 1, and 14 is a valve for pressurizing the backwash water in the backwash water storage tank 8. It is. When cleaning the magnetic fine wire 3, the magnetic fine wire 3 is demagnetized, the valves 6 and 7 are closed, and the valves 11, 12, 1 are closed.
3 and 14 are opened, the pressure of the compressed air in the air tank 10 is applied to the backwash water storage tank 8, and the backwash water in the tank 8 flows back from the secondary side to the primary side of the electromagnetic filter 1 and adheres to the magnetic thin wire 3. The iron particles and oil contained therein are washed away and discharged from the valve 12. After washing, open the valves 6 and 7 again, close the valves 11, 12, 13, and 14, and turn on the water supply pump 4.
The oil suspension is supplied to the electromagnetic filter 1 by the power of , and the magnetic wire 3 is magnetized to continue capturing the iron content in the oil suspension. 15 is a valve for supplying backwash water to the backwash water storage tank 8, and during the process of capturing iron, valve 1 is
5 is opened and the tank 8 is filled with industrial water, etc.

As explained above, in the present invention, the cleaning of the magnetic fine wire is not carried out until the captured iron weight ratio exceeds 0.1, and the area where the captured iron weight ratio is 0.1 or more and the oil capture rate is low is used. Even when oil suspensions are used in circulation, the oil concentration does not drop as suddenly as in the past, making it possible to remove iron from oil suspensions used for steel rolling and use them repeatedly. This will have a significant economic effect.

[Brief explanation of drawings]

Figure 1 is a diagram showing the change in oil capture rate by an electromagnetic filter, Figures 2 and 3 are explanatory diagrams of the situation in which iron particles and oil are captured by magnetic fine wire, and Figure 4 is an oil suspension diagram. It is a piping system diagram showing an example of a liquid processing system. 1... Electromagnetic filter, 2... Electromagnet, 3... Magnetic thin wire, 8... Backwash water storage tank.

Claims (1)

[Claims] 1 Pass an oil suspension between magnetic thin wires magnetized by an electromagnet so that the iron particles contained in the oil suspension are magnetically captured by the magnetic thin wires, and determine the ratio of captured iron particles to the magnetic thin wires. 1. A method for capturing iron in an oil suspension, characterized in that the magnetic fine wires are not washed until the weight ratio (weight ratio) exceeds at least 0.1.