JPS5973439A - Production of iron oxide from waste hydrochloric acid liquor for pickling - Google Patents

Abstract

PURPOSE:To obtain economically a low-Si iron oxide which is a raw material for high- class ferrite, by roasting or crystallizing a waste liquor obtained by ultrafiltering a waste liquor after pickling a steel material with hydrochloric acid. CONSTITUTION:A waste liquor produced by acid washing of a steel material with hydrochloric acid such as steel plates, molds, rods, wire materials, etc. with the hydrochloric acid is ultrafiltered to reduce the SiO2 content to 2-10ppm. The resultant ultrafiltrate is then roasted and crystallized to give the aimed low-Si iron oxide. In a schematic drawing of an example, the above-mentioned waste liquor of acid washing charged into a waste liquor tank 1 is passed through a preliminary filtration apparatus 3 to a module 4 consisting of ultrafiltration membranes. The resultant ultrafiltrate obtd. in the filtration apparatus 3 is passed through a solenoid valve 5 to a filtrate tank 6. The concentrated solution is then returned to the waste liquor tank 1 and recirculated therethrough. The ultrafiltrate is suitably taken out of an extraction pipe 7, fed to a roasting apparatus and passed through a roasting stage to prepare iron oxide. The back washing necessary for the ultrafiltration is carried out by using a counterflow pump 8 and a check valve 9.

Description

Detailed Description of the Invention The present invention is a method for producing iron oxide from the hydrochloric acid pickling waste liquid (hereinafter simply referred to as pickling waste liquid) generated during hydrochloric acid pickling of steel materials, that is, steel plates, molds, rods, wire rods, etc. Regarding.

As is well known, for steel materials, particularly hot-rolled steel strips, a method of cleaning scale on the surface by pickling with hydrochloric acid is widely employed.

Incidentally, the pickling waste liquid generated at this time contains a large amount of PE and small amounts of metal oxides such as non-ferrous metals and SIO, as shown in Table 1, for example.

Table 1 Accordingly, in order to recover the pe component as iron oxide, roasting methods and crystallization methods are usually used, and the iron oxides obtained by these methods are used as ferrite raw materials and pigments.

It is used in many ways, including as a filler.

However, the iron oxide obtained by the above method has a high 8j (h content) as shown in Table 1 above, so it has the disadvantage that it is not suitable for high-grade applications as a magnetic material.

Therefore, as a result of various studies to reduce the sho content, the present inventors succeeded in reducing the siox content to 2 to ioppm by ultrafiltering the pickling waste liquid, The desired high-grade ferrite raw material, iron oxide, was obtained.

As is well known, ultrafiltration involves applying pressure to a solution to remove polymers,
A means for filtering substances and colloidal substances through a semi-permeable membrane, and allowing water and low-molecular substances contained in the water to permeate through countless fine pores existing on the membrane surface of the semi-permeable membrane. Various types of filtration membranes are commercially available for carrying out this process, and in the present invention, Module 5IP-3013 (for actual equipment) (trade name) manufactured by Mukasei Kogyo Co., Ltd. was used.

In the past, ultrafiltration of pickling waste liquid had never been attempted because it was not considered to be a component whose quality could be improved by ultrafiltration! 5.
This was because they had the foresight to know that iron oxide, which is a raw material for high-grade ferrite, could not be obtained from the nine pickling waste liquid.

Now, the present inventors, who were involved in an operation to produce iron oxide by roasting pickling waste liquid, discovered that sio contained in pickling waste liquid
I learned that , is one of the main causes of low magnetic properties, but since it has properties and composition that are very similar to waste, it is necessary to spend a large amount of equipment costs to improve its properties. However, as a result of many years of research into more economical and efficient methods, the method of the present invention was developed.

FIG. 1 is a schematic diagram of one embodiment of the apparatus for carrying out the method of the present invention, in which the pickling waste liquid obtained from the hydrochloric acid waste washing apparatus (not shown) is charged into the waste liquid tank IK. From the pump 2, the liquid passes through the preliminary filtration device 3 and reaches the module 4 consisting of an ultrafiltration membrane, where the V-treated liquid (hereinafter referred to as the F liquid) enters the P liquid tank 6 via the electromagnetic valve 5. The concentrated liquid returns to the waste liquid tank 1 again and is circulated again. During this time, the pickling waste liquid is replenished as appropriate. FM is taken out from a suitable extraction tube 7 and sent to a roasting device (not shown), where iron oxide is produced through a roasting process.

The torrefaction equipment may be used by the well-known 7 lashing method. Ultrafiltration requires appropriate backwashing.

Pump 8 is a backwash pump, 9 is a check valve, and 10 to 12 are pressure needles.

By the way, when the p liquid obtained by such ultrafiltration was analyzed, the sio was found to be 2 to 10 ppm, and other F
No changes were observed in e, Mn, Na, and K4I.
Why Sin! Although it is not clear why only the 5ins content decreases, it has been demonstrated through numerous experiments that the 5ins content decreases dramatically.

The iron oxide obtained by roasting the V liquid is Fetos;
It was 99% or more, and the Slow was 0.005X or less, of high quality and suitable as a haferite raw material.

As explained above, the present invention provides a useful means for economically producing iron oxide, which is a high-grade ferrite raw material, from acidic waste liquid.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of an apparatus for carrying out the method of the present invention. 1... Waste liquid tank, 4... So4 knee/
l/, 6...P liquid evening/ri. Agent: Patent attorney Masamitsu Akizawa and 2 others 1m

Claims (1)

[Claims] (1) Low-Si iron oxide is obtained by roasting or crystallizing the pickling waste obtained by ultrafiltration of the hydrochloric acid pickling waste of steel materials.Producing iron oxide from the hydrochloric acid pickling waste. Method.