JPS6199638A - Manufacture of iron powder from pig iron-containing slag - Google Patents

Abstract

PURPOSE:To obtain the iron powder for a concrete reinforcing aggregate, a chemical body warmer, or the like, by refining the metallic iron content of a pig iron-contg. slag until the iron content gives >=90%, and subjecting the refined metallic iron content to screening, particle size regulation, or the like, to gain the stabilization of properties. CONSTITUTION:The pig iron-contg. slag is subjected to crush and magnetic separation, required times, repeatedly, to be recovered by separation, and is refined until the metallic iron content gives >=90% in total. The refined matter is subjected either to screening and grain size regulation or to pulverization and air classification. In this way, pulverized iron of each particle size having uniform and stable quality can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses metallic iron recovered from pig iron-containing slag generated at a steelworks as a raw material, and uses physical methods such as crushing, air mixing, and magnetic separation at room temperature. ! This invention relates to a method for producing iron powder for use in concrete reinforcement aggregates, chemical body warmers, oxygen scavengers, etc. by adding minerals to the iron powder.

[Conventional technology]

In recent years, industrial iron powder has been used for welding, chemical warmers, oxygen absorbers,
Its use as concrete reinforcement aggregate has expanded, and various research and development efforts have been made on manufacturing methods, but the main manufacturing methods currently include the reduction method and the atomization method. Looking at its production method, in the reduction method, high-grade iron ore or mill scale and a reducing agent are mixed together and a reduction reaction is performed at a predetermined temperature to produce sea iron, followed by crushing, magnetic separation, and if necessary, reaction of iron powder. Water retention treatment is carried out to improve performance. In the atomization method, molten steel is atomized with high-pressure water or inert gas to obtain small iron particles, which are then annealed to facilitate crushing and decarburization.

[Problems that the invention attempts to solve]

The above-mentioned manufacturing methods have the problem that the steps are complicated and high-quality raw materials are required, resulting in high costs. The applicant of the present invention uses slag generated from steelworks as a raw material to crush and crush into 9 meter classes.

It has been used in combination with magnetic sorting to produce iron sources for steel and cement production, road base materials, etc.
Using our technology and experience, we have researched and found a method for producing iron powder by a physical beneficiation method that does not involve metallurgical or chemical treatment using the products of the slag treatment system mentioned above as raw materials.

[Means to solve the problem]

The above-mentioned manufacturing method involves crushing metallic iron, which is a magnetic material with a total iron content of around 80% produced from a conventional slag processing system, at room temperature and physical beneficiation such as magnetic separation, to convert the magnetic material into iron powder. It consists of a selection process to remove slag contaminants until it reaches a quality sufficient to exert its function, and a process to sieve and adjust the particle size of the tf1 selected product depending on the purpose of the iron powder, or to finely crush and air classify it. ing. Also, depending on the application, the particle size is vR'! Add rust prevention treatment to the iron powder after i.

[For production]

In the first selection step of the method of the present invention, the metallic iron component of the raw material is magnetically separated using a magnetic separator, and then only the magnetic material is subjected to a high-speed impact crusher. Here, the slag interposed in the magnetic particles is destroyed by the impact and peeled off.

t The entire amount of the crushed material containing the crushed slag' is magnetically separated again in the original magnetic separator to remove the slag.

This magnetic separation and high-speed crushing are usually carried out by an electric circuit that cycles through the process a certain number of times to obtain a selected product with a predetermined total iron grade.

The small steps are divided into pulverizing the selected product, adjusting the particle size tlJ, and adjusting the iron powder WtJ according to the purpose. That is, sieving and particle size adjustment are performed for concrete reinforcement aggregate, and fine pulverization and air classification are performed for chemical use and oxygen scavenger use.

Regarding iron powders for Chemical Kai U and Oxygen Absorber 1, which require an oxidizing ability of a certain level or higher, the factors that influence the ability are not only the total iron grade, but also the particle size and specific surface area. It has been discovered. In the method of the present invention, fine powder iron powder of stable quality with little variation can be efficiently extracted at any particle size by fine pulverization using a ball or rod mill accompanied by air classification.

〔Example〕

Examples of the present invention will be described based on the manufacturing process shown in FIG.

Raw material granulated iron (&! selected product of pig iron-containing slag obtained in another processing system) has a maximum particle size of 1.2 m + *lIf! The upper part of the sieve was cut and returned to another system, the lower part of the sieve was subjected to magnetic separation, the non-magnetic material was used as a source of iron for cement production, and the magnetic material was passed through a high-speed impact crusher. In the process of magnetic separation and high-speed impact crushing, cyclic crushing was performed 10 times so that the total iron content of the selected product was 92% or more, and the results are as follows.

Table 1: Chemical analysis values of raw materials and selected products (weight %) Table 2: Particle size distribution of raw materials and selected products (weight %) After quality inspection, the selected products proceed to the process of preparing iron powder according to their use. In the production of iron powder for concrete reinforcement aggregate, it is sieved in two stages III (upper sieve size 0.6a+w+, lower sieve size 0.3i+m), and the products of size above the sieve and intermediate size are mixed at a constant ratio. A vaporizable water i3' liquid type rust preventive agent is applied to the ear to prevent rust until use, and the mold is pressed.

When crushing pig iron grains, free carbon contained in the structure, so-called quiche graphite, precipitates and causes problems during the iron powder preparation process and product use.However, in the first stage of high-speed impact crushing by the method of the present invention, slag Because only the fraction is impact-destructed to #JH1, a clean product with less graphite generation can be obtained. Constant particle size (0,3
The reason why iron powder with a high content of −0.15 mm particle size is excluded is that iron powder with a high content of −0.15 mm particle size causes early strength phenomenon of concrete and makes curing management difficult.

Iron powder for chemical body warmers and oxygen scavengers was obtained by feeding the selected products to a ball mill equipped with an air classification mechanism. In addition, the lower sieve product (−0,3+u
+) may also be supplied to the above ball mill. The outline of the fine pulverization method in this example is shown in Figure 2, and the pulverization conditions are the ball mill used: 3490avLX 2540m
mφ medium 45mmφ ball 13 rotation speed 21rpi Feed weight it/ch Air classification air volume 30m”/win, 50m’/
In win, the result is as follows.

Table 3 Yield Note: The fine particles from the mill outlet to the dust collector In the middle of the fine iron powder flow duct, A is the front collection tank, B is the cyclone, and C is the Each with bag filter of collection machine what was collected.

Table 4: Particle size distribution (wt%) Note: Samples are AB total in Table 3 (the same applies hereinafter) Table 5: Total iron content by particle size: 41%) Also, the chemical analysis value of the sample collected by the bag filter of the dust collector is As shown in Table 6.

Table 6 Chemical Composition (% by Weight) The results of measuring the heat generation properties of iron powder for chemical body warmers and the oxygen scavenging ability as iron powder for oxygen scavengers for iron powders having the above properties are as follows.

Table 7: Pyrogenicity test (according to the Tokyo Metropolitan Ordinance method) Note:
The table above shows a mixture of vermiculite or wood powder as a water retention agent. P iron powder is iron powder obtained by finely pulverizing the same selected material as in the present invention using a vibration mill.

Table 8 Oxygen scavenging ability test (residual oxygen concentration %) Note: The specimen subjected to vR preparation under the same conditions was sealed in a gas barrier bag, and
00 ml of air was introduced and the oxygen concentration over time was measured.

Regarding the oxidizing power of iron powder, which is the common basic ability of heat generation and deoxidization in Tables 7 and 8, even if the grade of T-Fe is high, for example, if the size is 0.044cm or less,
It has been experimentally found that the initial oxidizing power is low when cut, and this is also clear from Tables 5 and 7. Air volume as mentioned above: 30m3/win, 50m'
The results of elucidating the variation in p degree and total iron content of /+in and P iron powder are shown in Tables 9, 10, and 11.
Compared to iron powder, this iron powder has less variation in particle size, has an appropriate particle size structure, is very stable, and has superior oxidizing power compared to other iron powders.

Table 9: Dispersion of product particle size Table 10: Dispersion ratio of product particle size As shown in the above sample, in fine pulverization accompanied by air classification, it is possible to produce fine iron powder with a high yield. 6 By changing the air blower I, this particle size can be reduced to 1':J.

〔Effect of the invention〕

As explained in detail above, according to the method of the present invention, metallic iron obtained from pig iron-containing slag is used as a raw material, without using any metallurgical or chemical treatment, and at low cost and by means of physical beneficiation at room temperature. It is possible to produce iron powder for use in body warmers, oxygen absorbers, and concrete reinforcement aggregates with stable performance.

Incidentally, the by-product from the treatment system of the method of the present invention is the first
As shown in the figure, it is used as an iron source for steel manufacturing layers and cement factories, and it is also a product that can be collected in a dust collector by closed circuit crushing (product C in Tables 3 and 6).
Contains graphite in concentrated form and serves as a raw material for graphite recovery.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet explaining the method of the present invention. FIG. 2 is a schematic diagram of the pulverization method in the method of the present invention. In the figure, (1) two-ball mill (2): front collection tank (3): cyclone (4): collector 1 machine (5): duct (6): fan (Δ): front collection tank collected material ( B): Cyclone collected material IC'):! 146 Copper catch patent applicant: Japan Magnetic Separation Co., Ltd. No. 1 Prisoner No. 2

Claims (1)

[Claims] 1. The metal iron separated and recovered from the pig iron-containing slag is carefully selected by repeating crushing and magnetic separation the required number of times until the total iron content is 90% or more, and the selected material is subjected to sieving and particle size adjustment, or pulverization and air classification. A method for producing iron powder from pig iron-containing slag, which is characterized by subjecting it to the following treatment.