WO2017111260A1 - Method for preparing steelmaking dust briquettes - Google Patents

Abstract

An embodiment of the present invention provides a method for preparing steelmaking dust briquettes, the method comprising the steps of: adding a cellulose ether-containing solution to steelmaking dust to prepare a mixture; stirring the mixture; and molding the stirred mixture.

Description

How to make steel dust briquettes

The present invention relates to a method for manufacturing steelmaking dust briquettes, and more particularly, to a method for preparing briquettes by stirring and molding a mixture in which cellulose ether is added to steelmaking dust in solution form.

The steelmaking process is divided into an iron making process for manufacturing crude steel using iron ore and coal and a steel making process for increasing the purity of the crude steel.

Steelmaking dust can occur in steelmaking processes, for example stainless steel manufacturing processes. The steelmaking dust produced may contain a large amount of iron and optionally metal components such as zinc. Specifically, iron (Fe), carbon (C), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), pentoxide Phosphorus (P ₂ O ₅ ), sulfur (S), molybdenum (Mo), calcium oxide (CaO), magnesium oxide (MgO), chlorine (Cl), zinc (Zn) and the like. Conventionally, all steelmaking dust containing the metal components was discarded, but recently, a technique for reusing the same has been developed.

Steelmaking dust is not uniform in particle size distribution and contains various components. One of the representative technologies for recycling such steelmaking dust is to compress the steelmaking dust into briquettes and re-introduce the steelmaking process. Most steel companies recycle these steel dust into briquettes.

Molasses was used as a binder to prepare briquettes by mixing steelmaking dust. However, when steelmaking dust contains calcium oxide (CaO), a hydration reaction such as the following Chemical Formula 1 occurs due to moisture incorporation, which is a remarkable strength of briquettes. Caused a degradation.

[Formula 1]

CaO + H ₂ O → Ca (OH) ₂

The reaction of Chemical Formula 1 is an exothermic reaction, and heat generated during the reaction causes volume expansion of the briquettes, resulting in tissue cracking of the briquettes due to tensile stress.

Therefore, there is a need for a method for manufacturing steelmaking dust briquettes that can improve the deterioration of strength of briquettes over time without causing tissue breakdown of the briquettes.

One of the technical problems to be achieved by the technical idea of the present invention is to provide a method for manufacturing steelmaking dust briquettes which can prevent tissue collapse of briquettes prepared from steelmaking dust and increase drop strength.

Method for producing a steelmaking dust briquette according to an embodiment of the present invention, adding a solution containing cellulose ether to steelmaking dust to prepare a mixture; Stirring the mixture; And shaping the stirred mixture. The steelmaking dust may include calcium oxide (CaO).

For example, the cellulose ether is selected from the group consisting of methyl cellulose, hydroxypropyl methyl cellulose, hydroxyehtyl methyl cellulose, and hydroxyethyl cellulose. It may be at least one.

For example, the content of the cellulose ether relative to 100 parts by weight of the steelmaking dust may be 0.5 to 20 parts by weight.

As an example, the solution may be a solution of 1 to 40% by weight of the cellulose ether in water.

In the method of manufacturing steelmaking dust briquettes according to an embodiment of the present invention, even when molding steelmaking dust containing a large amount of calcium oxide, it is possible to express high compressive strength according to age and to reduce the drop rate of drop strength over time. It is possible to provide a method of making a briquette.

1 is a process flowchart of a method of manufacturing steelmaking dust briquettes according to an embodiment of the present invention.

Hereinafter, a method of manufacturing steelmaking dust briquettes according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As used herein, the term 'steelmaking dust' refers to blast furnace dust, electric arc furnace dust, and mixtures thereof.

1 is a process flowchart of a method of manufacturing steelmaking dust briquettes according to an embodiment of the present invention.

Referring to Figure 1, the method for producing a steelmaking dust briquette according to an embodiment of the present invention, the step of preparing a mixture by adding a solution containing cellulose ether to the steelmaking dust (S1), stirring the mixture ( S2) and the step (S3) of forming the stirred mixture may be included.

In step S1, the steelmaking dust may contain various kinds of metals or metal compounds, and specifically, may include calcium oxide, which causes a hydration reaction due to moisture incorporation.

In addition, the cellulose ether serves as a binder in the mixture, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyehtyl methyl cellulose and hydroxyethyl cellulose cellulose) may be at least one selected from the group consisting of cellulose.

The content of cellulose ether added to 100 parts by weight of steelmaking dust may be 0.5 to 20 parts by weight, in which case, the solution containing cellulose ether may be dissolved in a concentration of 1 to 40% by weight of cellulose ether in water.

In step S2, the mixture of step S1 may be stirred. The stirring may be performed using a mixer mixer and a kneader mixer, preferably, in a mixer mixer and then again in a kneader mixer.

When a solution containing cellulose ether is added, the cellulose ether has excellent dispersibility and binding as a coking agent in steelmaking dust, thereby reducing the volume expansion caused by the hydration reaction by calcium oxide present in the steelmaking dust and the resulting tensile stress. It is possible to prevent tissue cracking of briquettes that cause.

The stirring may be performed until the mixture is uniform.

In step S3, the stirred mixture may be molded to prepare a briquette. For example, the molding may be performed by applying a constant pressure with a roll press. It is also possible to prepare a briquette in the form of a pocket or strip by charging the mixture between paired rolls rotating in opposite directions.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1-3 and Comparative Examples 1-6

To prepare a mixture having a compounding ratio as shown in Table 1. In Table 1 below, stainless steel dust was obtained by using a known steel oxide content in a domestic steel company.

	Stainless Steel Dust (parts by weight)	Steelmaking Dust Calcium Oxide Content (%)	Distilled water (parts by weight)	bookbinder
				Molasses (part by weight)	Cellulose ether
					Powder (part by weight)	Solution (part by weight)
Comparative Example 1	100	10	10	10.0	0	0
Comparative Example 2	100	15	10	10.0	0	0
Comparative Example 3	100	20	10	10.0	0	0
Comparative Example 4	100	10	15	0	1.0	0
Comparative Example 5	100	15	15	0	1.0	0
Comparative Example 6	100	20	15	0	1.0	0
Example 1	100	10	5	0	0	10
Example 2	100	15	5	0	0	10
Example 3	100	20	5	0	0	10

Molasses: cystronics, molasses

Cellulose Ether: Samsung Fine Chemicals, Mecellose ^®

Cellulose ether solution: 10% by weight cellulose ether solution, Samsung Fine Chemicals, Mecellose ^®

Each mixture having the composition of Table 1 above was stirred for 5 minutes using a mixer (Erich). Thereafter, each of the stirred mixtures was press-molded using a Briquette machine (JCB250T) to prepare an elliptical briquette having a size of 45 mm x 22 mm x 14 mm in thickness.

Evaluation example

(Drop strength evaluation)

Twenty briquettes prepared from the mixtures having the mixing ratios of Examples 1 to 3 and Comparative Examples 1 to 6 were prepared and free-falled 10 times at a height of 165 cm. After dropping, the total weight of the fragments 5 mm or more in length among the remaining fragments of the briquettes was measured. Thereafter, the total weight of fragments of 5 mm or more in length among the remaining fragments of the briquettes after the drop was compared with the weight of the briquettes before the drop, and the value thereof was evaluated as the drop strength. At this time, the larger the value, the larger the drop strength. For reference, the drop strength is a criterion for determining the rate at which debris is lost by falling several times when the briquette is transported by the conveyor belt.

Table 2 below shows the results of the drop strength of each briquette over time.

		Elapsed time after molding (hrs)
		0	3	5	24	48	120
Drop strength (%)	Comparative Example 1	86	83	69	20	32	11
	Comparative Example 2	75	70	53	15	0	0
	Comparative Example 3	62	55	34	0	0	0
	Comparative Example 4	83	83	85	65	62	60
	Comparative Example 5	75	72	69	63	59	60
	Comparative Example 6	75	79	72	67	64	62
	Example 1	98	99	99	86	82	80
	Example 2	99	97	95	77	73	72
	Example 3	92	97	94	79	75	75

Referring to Table 2, the falling strength of Examples 1 to 3 using cellulose ether in solution form compared to Comparative Examples 1 to 3 using molasses as binder and Comparative Examples 4 to 6 using cellulose ether as powder as binder. It can be seen that better, even over time.

(Compression strength evaluation)

Each briquette made of a mixture having a mixing ratio of Examples 1 to 3 and Comparative Examples 1 to 6 was compressed at a speed of 5 mm / min. In a material universal testing machine (Xinjiang Precision Industries, AD-Universal Material Testing Machine-kN). The maximum strength of was measured and evaluated as compressive strength. For reference, the compressive strength is a criterion for determining the rate at which briquettes are broken by their own load when stored in a storage tank.

Table 3 below shows the results of the compressive strength of each briquette over time.

		Elapsed time after molding (hrs)
		0	3	5	24	48	120
Compressive strength (kg f / cm 2 )	Comparative Example 1	27	25	25	9	0	0
	Comparative Example 2	32	28	23	11	0	0
	Comparative Example 3	36	19	0	0	0	0
	Comparative Example 4	11	15	19	24	29	32
	Comparative Example 5	14	19	23	34	38	42
	Comparative Example 6	15	21	28	42	51	58
	Example 1	20	27	32	67	79	85
	Example 2	20	27	29	68	72	85
	Example 3	15	29	36	62	76	82

Referring to Table 3, the compressive strength of Examples 1 to 3 using cellulose ether in the form of a solution compared to Comparative Examples 1 to 3 using molasses as a binder and Comparative Examples 4 to 6 using cellulose ether as a binder in powder form It can be seen that better, even over time.

The present invention described above is not limited to the above-described embodiment, and various substitutions, modifications, and alterations are possible within the scope without departing from the technical spirit of the present invention. It will be obvious to him.

Claims (4)

1. Preparing a mixture by adding a solution containing cellulose ether to steelmaking dust;

   Stirring the mixture; And

   Shaping the stirred mixture; and

   The steelmaking dust manufacturing method of steelmaking dust briquettes comprising calcium oxide (CaO).
2. The method of claim 1,

   The cellulose ether is at least one selected from the group consisting of methyl cellulose, hydroxypropyl methyl cellulose, hydroxyehtyl methyl cellulose and hydroxyethyl cellulose. The manufacturing method of steelmaking dust briquettes characterized by the above-mentioned.
3. The method of claim 1,

   Method for producing a steelmaking dust briquettes, characterized in that the content of the cellulose ether relative to 100 parts by weight of the steelmaking dust is 0.5 to 20 parts by weight.
4. The method of claim 3,

   The solution is a method for producing steelmaking dust briquettes, characterized in that the cellulose ether is dissolved in water at a concentration of 1 to 40% by weight.

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