Unlock instant, AI-driven research and patent intelligence for your innovation.

Method for producing briquettes, method for producing reduced metal, and method for separating zinc or lead

a technology of briquettes and sintering, which is applied in the direction of metal processing, furnace types, furnaces, etc., can solve the problems of reduced yield, reduced plant operating ratio, and inability to use methods for enhancing strength of agglomerates by sintering, and achieve efficient production, enhanced apparent density of primary granular materials, and high strength

Inactive Publication Date: 2012-07-26
KOBE STEEL LTD
View PDF3 Cites 1 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a method for producing agglomerates (briquettes) using dust containing metal oxides and an iron oxide raw material. The method involves enhancing the strength of the agglomerates by using a bonding agent such as starch or molasses. The agglomerates are used as a raw material in a rotary hearth furnace for producing reduced iron. The technical effects of the invention include improving the strength of the agglomerates to prevent operational problems and increasing the yield of the reduced metal. The invention also addresses the difficulty of uniformly mixing the binder with the fine powder raw material to enhance the strength of the agglomerates.

Problems solved by technology

However, when a carbonaceous material is contained, a method for enhancing strength of agglomerates by sintering cannot be used because carbon is burnt even at a relatively low temperature.
The agglomerates having low strength cause operational problems (1) that the plant operating ratio is decreased due to difficulty in storage of the agglomerates, (2) yield is decreased due to powdering of the agglomerates, (3) the performance of reduction treatment of the powered agglomerates is decreased due to low reactivity, and (4) the strength of a reduced metal (reduced iron: DRI) produced by reducing the agglomerates is decreased, and thus the reduced metal is unsuitable for a shaft furnace type, such as a blast furnace, and a melting process, which require high-strength DRI, thereby limiting the application of DRI.
However, it is very difficult to produce agglomerates of fine powder raw materials for the following two main reasons.
One of the reasons is that it is difficult to produce agglomerates having strength because a fine powder dust material has a low bulk density and many voids.
If agglomerates have low strength, the agglomerates may be broken by pressure and thus cannot be stored in a large amount or cause cracking or the like during transport.
The other reason is that a fine powder raw material is mixed with a binder in order to enhance the strength of agglomerates, but it is difficult to uniformly mix the binder.
In addition, a binder material is expensive, and the binder has an adhesive function and thus causes material clogging during production or a supply process (for example, an intermediate hopper) of the agglomerates.
The material clogging stops the supply of the raw material to a rotary hearth furnace or the like or abruptly causes the supply of a large amount, thereby destabilizing the operation of a reducing furnace.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Method for producing briquettes, method for producing reduced metal, and method for separating zinc or lead
  • Method for producing briquettes, method for producing reduced metal, and method for separating zinc or lead
  • Method for producing briquettes, method for producing reduced metal, and method for separating zinc or lead

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0071]An electric furnace dust (may be simply referred to as a “dust raw material” hereinafter) having a total iron content of 22.7% by mass (may be simply referred to as “%” hereinafter), a zinc oxide content of 38.4% by mass, a lead oxide content of 2.1% by mass, and a titanium oxide content of 0.1% by mass was used as a steel-making dust material. The grain size distribution of the dust raw material is as shown in each of FIGS. 3(a) and 3(b) and has a peak grain diameter of about 4.3 p.m. In addition, the bulk density of the electric furnace dust raw material was 760 kg / m3. In addition, coke breeze (fixed carbon: 86%) was mixed as a reducing agent. The amount of the dust raw material mixed was 85.7%, and the amount of the coke breeze mixed was 14.3%.

[0072]In a raw material mixing step before a pelletizing step, the raw material was mixed for 5 minutes using a biaxial ribbon stirrer (manufactured by Chemical Engineering Co., Ltd.), and then 4% of water and 2% of a binder (molasses...

example 2

[0078]Pellets were produced by the same method as in Example 1, and briquettes were formed from the pellets. A difference from Example 1 was that in Example 1, 4% of water and 2% of a binder (molasses) were mixed in the raw material mixing step before the pelletizing step, while in Example 2, 6% of water was mixed without using a binder.

[0079]With respect to the grain size, the produced pellets included 23.0% of pellets having a diameter in the range of 3.0 to 6.0 mm and 77.0% of pellets having a diameter in the range of 6.0 to 9.5 mm. Since the binder was not used in Example 2, the bulk density of the pellets was 1,360 kg / m3 (apparent density: 2,480 kg / m3) which value was slightly lower than that in Example 1 (1,390 kg / m3). However, the bulk density was sufficiently increased from 760 kg / m3 at the stage of the dust raw material. The water content of the pellets was 11.0% which was slightly higher than that in Example 1.

[0080]The apparent density of the briquettes produced in Exampl...

example 3

[0086]Pellets were produced by the same method as in Example 2, and briquettes were formed from the pellets. A difference from Example 2 was that the type of steel-making dust used as the raw material was variously changed.

[0087]Table 1 shows the results of the same experiment as in Example 2 using 13 different types of dust raw materials.

TABLE 1Test of Example 3 (passing through pellets)Dust raw material No.12345678910111213Dust bulkKg / m310108209806701030117075010307908301040——densityIron oxide% by19.022.927.014.926.819.419.123.223.924.615.738.942.8mass(a) Zinc oxide% by26.723.414.819.915.118.217.424.324.720.634.99.44.7mass(b) Lead oxide% by0.20.31.51.00.60.81.40.21.81.80.20.70.4mass(c) Titanium% by0.10.10.10.10.10.10.10.10.10.10.10.00.0oxidemass(a) + (b) + (c)% by27.023.816.420.915.819.118.824.626.522.435.210.15.1massAgglomerates12345678910111213ApparentKg / m32910296028202890298029602790300031203040308026102530density beforedryingDrop strengthNumber30309302930303030243031before dry...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
apparent densityaaaaaaaaaa
apparent densityaaaaaaaaaa
apparent densityaaaaaaaaaa
Login to View More

Abstract

Disclosed is a method for producing briquettes, by which briquettes having enhanced strength can be produced even when the amount of a binder used therefor is reduced as much as possible. Specifically disclosed is a method for producing briquettes, which comprises: a step of forming a primary granular material having an apparent density of 1,000 to 4,000 kg / m3 using a powder of metal oxides including iron oxide and one or more oxides selected from among of zinc oxide, lead oxide, and titanium oxide; and a step of forming a secondary granular material by compressing a plurality of primary granular materials, while having the primary granular materials contain one or more metal oxides selected from among the zinc oxide, lead oxide, and titanium oxide.

Description

TECHNICAL FIELD[0001]The present invention relates to a method for producing agglomerates (briquettes) using dust raw materials containing metal oxides (particularly iron oxide) and can be applied to a method for producing a reduced metal from the resultant agglomerates and to a method for separating and recovering volatile metals such as zinc, lead, and the like.BACKGROUND ART[0002]Although iron ore raw materials are, of course, used as raw materials for producing reduced iron, recycling of dust containing iron raw materials, which is produced in iron mills, attracts attention because of the recent price increases with increases in demand for iron ore raw materials. In pig iron making or steel making processes, dust containing powdery iron and iron oxide blown up in a blast furnace, a converter, a melting furnace, etc. is recovered with a dust collector. The recovered powder (hereinafter referred to as the “steel making dust”) contains iron and iron oxide and is thus used as an iro...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(United States)
IPC IPC(8): C22B5/00C22B13/00C22B19/20C22B1/24
CPCC21B13/0046C21B13/006C22B1/24C22B1/243C21B2100/02C22B7/02C22B19/30C21B13/105C22B1/248Y02P10/20C21B13/10C22B1/16C22B5/16
Inventor HARADA, TAKAOMICHISHITA, HARUYASUMIYAKAWA, YUTAKAFUJI, KOIJIROMIZUTANI, NORIAKI
Owner KOBE STEEL LTD