WO2010035289A1

WO2010035289A1 - A method of agglomeration of ferroalloy fines such as ferromanganese, ferrochrome and ferrosilicon fines

Info

Publication number: WO2010035289A1
Application number: PCT/IN2009/000532
Authority: WO
Inventors: Veerendra Singh; Saripalli M. Rao; Prasanta Mallick; Srivivas Dwarapudi; P. K. Mishra
Original assignee: Tata Steel Limited
Priority date: 2008-09-29
Filing date: 2009-09-29
Publication date: 2010-04-01
Also published as: EP2329050A1; JP2012504189A; CN101910427A; ZA201004347B; EP2329050A4; CN101910427B

Abstract

A method of agglomeration of ferroalloy fines such as ferromanganese, ferrochrome and ferrosilicon fines comprising the steps of: Providing ferroalloy fines below 10mm size; Sieving <3mm size fraction and crushing 3-10mm to produce <3mm fines; mixing the resulted fines with a phenol formaldehyde resol resin binder in a vessel; compacting the mixed fines in a compressive machine in batches to form agglomerates; curing the agglomerates on heating in a furnace maintained at a temperature range 150-200°C for about 60 to 90 minutes.

Description

A method of agglomeration of ferroalloy fines such as ferromanganese, ferrochrome and ferrosilicon fines

FIELD OF THE INVENTION

The present invention relates to a method of agglomeration of Ferroalloy fines such as Ferromanganese, Ferrosilicon, Silicomanganese and Ferrochrome fines. More particularly, the present invention relates to a method of agglomeration of Ferromanganese fines from sized ferromanganese cake.

BACKGROUND OFTHE INVENTION

In order to produce better quality of steel in open Hearth furnaces, it is necessary to add silicon, chromium, phosphorus etc. in the form of ferroalloys containing from as little as 5 to as much as 85 percent of the input to the charge, bath, ladle and the mold. Important ferroalloy product are Ferrosilicon, high carbon Ferromanganese and ferrochromium, silicomanganese, and calcium suicide which are usually manufactured in electric furnace. However low grade ferroalloys are produced more cheaply in the blast furnace, from silicon, manganese or chromium bearing ores or concentrates. Such ferroalloys are produced in the form of cake. The ferroalloys cake such as Ferromanganese, ferrosilicon or ferrochromium are generally broken down to 10 to 150 mm size lumps. The ferroalloy fines of < 10mm size are generated by crushing different sizes of lumps. The ferroalloy fines thus produced are relatively cheaper.

In the state of art agglomeration of ores and concentrates through the routes of nodulizing, palletizing or briquetting and sintering are known. But agglomeration of ferroalloy fines is yet to be developed in this field of technology.

OBJECT OF THE INVENTION

It is therefore an object of the invention to propose a method of agglomeration of Ferro-alloy fines specifically Ferromanganese, ferrochrome and Ferrosilicon fines to produce cheaper ferroalloys.

Another object of the invention is to develop agglomerate from Ferroalloy fines via expropriate sizing of .fines, mixing the fines with a specific binder and compacting.

A further object of the invention is to select a specific binder for the agglomeration through test evolution having its materials characteristics different from conventional sodium silicate or Bentonite binder.

SUMMARY OF THE INVENTION The proposed invention has been exemplified by an embodiment for agglomeration of Fe-Mn fines, which is however applicable to agglomerate Fe-si and Fe-cr fines also, with the same method steps and conditions maintained in the method disclosed in respect of Ferromanganese fines agglomeration.

There are various kind of binders available in the market for agglomeration of ore fines. The nature of Ferromanganese fines (0-3mm) being very different as that from iron ore and the conventional binder (Sodium Silicate, Bentonite), the known method is not capable to produce agglomerate of Ferroalloy with suitable handling properties (Tumbler Index, Compressive, and Tensile Strength) for plant scale operations. Phenol formaldehyde according to the invention for resin is selected for use as a binder for Ferromanganese fines (0-3mm) to produce agglomerate through characterized testing for a desired strength.

Various proportions in weight % in the range of 2 to 10% of the binder were tested for the ferromanganese fines and it was found that 3 to 5% binder content is the optimum content to achieve the desired properties with minimum cost.

Accordingly, there is provided a method of agglomeration of ferroalloy fines comprising the steps of crushing the ferroalloy cakes to 3mm size; mixing at least binder such as phenol-formaldehyde resin (Resol Resin) selected through characterized evaluation of agglomerates having desired strength according to tumbler index, compressive and tensile strength; compacting the mixture in a compression machine of at least 5 ton load Capacity; curing the compact in a furnace maintained at 150° to 200° C, for a period of 60 to 90 minutes.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The proposed invention will be better understood from the accompanying drawing in which Figure 1 relates to a Process flow sheet to produce ferromanganese agglomerate with desired strength.

DETAILED DESCRIPTION OF THE INVENTION

The step of the agglomeration of ferroalloy fines as shown in figure 1 are as follows:

a. Sizing and Crushing the oversize (>3mm) particles: In the process of sizing of casted ferromanganese cakes, the material generated below 10mm is termed as fined in ferroalloy industry. The fines <3mm can be agglomerate directly but the fines >3mm cannot be agglomerated suitably by conventional agglomeration methods and crushing is required to reduce <3mm size range. b. Binder Mixing: the binder in wt% is mixed with the fines for proper distribution of binder in the material. Binder properties are given in table- 1. Table - 1: Binder properties

c. Compacting: The 60 to 80 gm of mixed material is kept in a die of diameter of 3 cm, and compressed by using compressive machine upto 5- ton load. The prepared agglomerate is removed and stored for further processing.

The green strength of the agglomerate is 7 drops from 500cm height. The agglomerate is a cylindrical briquette of 3 cm diameter and 2.0 cm length.

d. Curing: The prepared agglomerate is cured at 150°C to 200°C for 60 to 90 minutes. This product is then stored and can be used in place of ferromanganese lumps.

e. Testing: The handling properties of the agglomerated material play a vital role for plant scale operations and generation of fines is undesired. The compressive strength of the agglomerate has been tested using a UTM machine and its properties are listed below in Table-2.

Table - 2: Agglomerate properties

A comparative test result of strength characteristics between the resulted agglomerates of ferromangaήese produced according to the invention, and that of known ferromanganese lumps are enumerated below in table 3.

Table - 3:

Advantages of the Invention

The prepared agglomerates according to the invention can be used as a replacement of ferromanganese lumps. The physical properties of the agglomerates are comparable to commercially available ferromanganese lumps. These agglomerates can be used in the process like refining the steel in the ladle vessel. The bulk density of agglomerates has been found to be between5208 - 5210 kg/m³ and those do not float on the slag, sink properly in the metal, and shows better dissolving characteristics. The compressive strength and tumbler index (TI) of material are suitable for the transportation circuit and do not generate excessive fines.

The proposed invention as narrated herein should not be read in restrictive manner as various adaptations, modifications and alterations regarding process steps and process conditions are possible within the scope and ambit of the invention as defined in the appetent claims.

Claims

WE CLAIM

1. A method of agglomeration of ferroalloy fines such as ferromanganese, ferrochrome and ferrosilicon fines comprising the steps of:

Providing ferroalloy fines below 10mm size;

Sieving <3mm size fraction and crushing 3-10mm to produce <3mm fines;

mixing the resulted fines with a phenol formaldehyde reso! resin binder in a vessel;

compacting the mixed fines in a compressive machine in batches to form agglomerates;

^' curing the agglomerates on heating in a furnace maintained at a temperature range 150-200°C for about 60 to 90 minutes.

2. A method of agglomeration of ferroalloy fines as claimed in claim 1, wherein the binder is selected as a phenol-formaldehyde resin (Resol Resin) of with PH (1% solution) - 7.15, specific gravity 1.18, solid content 70.65%, viscosity at 25°C, 200cps. Min and carbon 38%.

3. A method of agglomeration of ferroalloy fines as claimed in 1 or 2, wherein the binder is mixed with the ferroalloy fines in a proportion of 3 - 5% by wt.

4. A method of agglomeration of ferroalloy fines as claimed in claim 1, wherein the mixed fines is compressed in the compressive machine to obtain the agglomerates with green strength of 7 drops from 500 cm height.

5. A method of agglomeration of ferroalloy fines as claimed in claim 1 wherein the cured agglomerates has cylindrical size of 3cm dia and 2cm height, area 0.0007065, volume 0.000014, weight 0.073 gm, bulk density 5208 - 5210 kg/M³, breaking load - 39, 000 Newton, compressive strength 55 Mpa_f tumbler index - 94%, abrasion index - 3%.

6. A method of agglomeration of ferroalloy fines as claimed in any of the preceding claims, wherein the agglomerates have compressive strength of 55 to 70 MPa, bulk density 5208-5210 kg/M³.