KR20220075376A - Molten iron desulfurization in the Kanbara reactor (KR) process - Google Patents

Abstract

The present invention relates to the desulfurization (DS) of molten iron via the KR process. In particular, the present invention relates to the development of reagents which will produce fluid slag during the desulfurization process in KR by breaking the network of silicate layers, which are generally formed of lime. The present invention also relates to the improvement of efficiency through the introduction of innovative granulometry of powders.

Description

Molten iron desulfurization in the Kanbara reactor (KR) process

The present invention relates to desulphurization (DS) of hot metal through the KR-process. In particular, the present invention relates to the development of reagents which will produce fluid slag during the desulfurization process in KR by breaking the network of silicate layers, which are generally formed of lime. The present invention also relates to the improvement of efficiency through the introduction of innovative granulometry of powders.

background information

Desulfurization of molten iron in KR is related to the removal of sulfur from molten iron as large amounts of sulfur cause cracks during the rolling process.

Sulfur affects both the inner and outer qualities of steel.

The formation of iron sulfide promotes grain fragility and cracking of the steel during solidification (lowering the melting point).

The hot shortness in the presence of sulfur makes rolling and forging very difficult.

A large amount of sulfur also contributes to the brittleness of the steel, and its presence in the sulfide phase acts as a stress enhancer in the steel product.

Conventional slag fluidizers such as lime and fluorspar are used in the KR process.

Fluorite is an environmentally hazardous material, which is avoided in most countries.

Currently used DS reagents result in higher slag production.

The cycle time for DS is long due to the molten iron consumption of 12.7 kg/tonne of DS reagent and therefore more time for slag racking.

US 4198229 discloses a method of using calcium carbide for the formation of refined slag in a ladle. The main purpose of the proposed method is to dephosphorize the steel.

Patent US 4198229 discloses a method for forming refined slag resulting from placing blast furnace slag, lime and dolomite on the surface of molten steel in a ladle.

Carbonate materials are used for the formation of refined slag in the patents discussed. During slag formation these materials decompose and require a certain amount of heat, which may not be possible without the use of a ladle furnace. At the same time, the use of calcium carbide can lead to an increase in the carbon content of low-carbon steel. In addition, the use of fluorspar to lower the slag viscosity is detrimental due to its harmful emissions. In some examples of slag-forming material production, the use of blast furnace slag can be observed, which leads to an increase in the SiO2 content in the formed slag and a decrease in its refining quality.

Other document CN103014217 contains the following components in weight percentages: 25 to 31% calcium oxide, 10 to 20% calcium fluoride, 10 to 25% calcium carbide, 4.5 to 15% calcium carbide, 3 to 6% As a desulfurization agent characterized in that it consists of aluminum and 5 to 8% of aluminum oxide, the particle diameter of which is 2 mm or less, the desulfurization agent is disclosed. The present invention also discloses vanadium-containing molten ion krypton (KR) desulfurization and application of desulfurization agents in molten iron KR desulfurization processes. The desulfurization agent disclosed by the present invention can be applied to the desulfurization of vanadium-containing molten ions.

purpose

1. The main object of the present invention is to increase the reagent efficiency and eliminate the risk of hazards associated with fluorite.

2. Another object of the present invention is to reduce metal loss in the KR process.

3. The third object of the present invention is to shorten the cycle time.

4. The fourth object of the present invention is to reduce the temperature loss.

5. A fifth object of the present invention is to reduce the cost of DS in KR.

Brief description of the invention

According to the present invention, the main object is achieved when the granulometry of the reagents is optimized (100% < 100 microns) and using synthetic cryolite with optimum flowability, which is efficient without causing exclusive dust losses and environmental pollution. This will facilitate the addition. The reagent has the composition mentioned below:

A slag conditioner such as synthetic cryolite: 6-14%, CaO: 70-90%, and LOI: 1-8%.

These reagents reduce reagent consumption by 40-60%, improving desulfurization efficiency by more than 100%, reducing nitrogen consumption by more than 40%, completely eliminating the use of environmentally hazardous fluorite, and reducing metal loss and racking time by 40% reduce over. In addition, the novel reagent is cost effective compared to the cost of conventional desulfurization. These products therefore make the desulfurization process more sustainable.

DETAILED DESCRIPTION OF THE INVENTION:

This innovative desulfurization reagent is highly effective in removing sulfur from molten iron through the Kanbara Reactor (KR) process without the use of fluorspar and reducing reagent consumption by 40 to 60%.

Composition of Desulfurization Reagent:

slag conditioners such as cryolite: 6 to 14%;

CaO: 70 to 90%

LOI: 1 to 8%

The development of innovative reagents involves three steps:

1. Lab Test:

It is well established that the reaction rate increases with decreasing reagent size due to increasing surface area. However, the reduction in particle size must be limited to prevent dust loss. The problem of finding the optimal reagent particle size to provide better efficiencies without incurring dust loss during laboratory testing has been addressed.

Laboratory tests were carried out in the following steps:

수평 밀과 같은 볼 밀에서 5 kg의 각 샘플의 8 로트를 분쇄하는 단계.

Grinding 8 lots of 5 kg each sample in a ball mill such as a horizontal mill.

과도한 분진 손실을 제한하기 위해 응집성을 보장하도록 유량 지수를 측정하는 단계.

Measuring the flow index to ensure cohesiveness to limit excessive dust loss.

시브 쉐이커 머신(Sieve Shaker Machine)을 통해 그래눌로메트리를 측정하는 단계.

Measuring Granulometry by Sieve Shaker Machine.

The results obtained for fluidity and granulometry are shown in Figures 1 and 2, respectively. Compared with the target flow index 0.30 and size 100% < 100 microns, the flow index of the material is greater than the target value, and thus the reagents are more cohesive, which limits excessive dust loss, and also achieves the target granulometry. Thus, it was observed to improve the efficiency of the reagent by increasing the reaction rate.

2. Pilot Industrial Tests:

In the KR process, 20 MT novel reagents were used for desulfurization, industrial tests were organized, and pilot scale tests were successfully carried out with 24 rows. The results obtained using the above reagents are shown in Table no.-1 below.

Table No.-l

The test results were encouraging and showed a clear potential to reduce consumption and eliminate fluorite completely, as a 40% reduction in consumption and 100% removal of fluorite were achieved with the same success rate during pilot scale trials.

3. Extended Industrial Testing:

In the KR process, 100 MT new reagents were used for desulfurization, tests were organized, more data were collected and compared with the existing performance. The results obtained in the extended test are shown in Table no.-2 below.

Table No.-2

Efficiency of DS reagent (η):

시약 소비 47% 감소로 효율 127% 증가

47% reduction in reagent consumption increases efficiency by 127%

형석 100% 제거

100% removal of fluorite

슬래그 발생 및 금속 손실 50% 넘게 감소

Reduced slag generation and metal loss by more than 50%

랙킹 시간 50% 넘게 단축

Reduced racking time by over 50%

Although the present invention has been described in detail with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention.

Claims (10)

a) a slag conditioner such as cryolite: 6 to 14%; A reagent for the desulfurization of hot metal in a Kanbara Reactor, comprising b) CaO: 70-90%, c) LOI: 1-8%. The reagent according to claim 1, which can be added to the top of the molten iron via a chute. The reagent for the desulfurization of molten iron in the Canbara reactor according to claim 1, which can be added for desulfurization in various ways in amounts of 1 to 10 kg/ton of molten iron. Reagent for desulfurization of molten iron in a Canvara reactor according to claim 1, which consists mainly of a slag conditioner comprising sodium, aluminum and fluorine based compounds. The reagent according to claim 1, which improves the DS efficiency of the novel reagent by more than 100%. The reagent of claim 1 , wherein the DS reagent has an optimal Granulometry of less than 100 microns to achieve the DS efficiency. A reagent for the desulfurization of molten iron in a Canvara reactor according to claim 1, which reduces nitrogen consumption by more than 40%. Reagent for desulfurization of molten iron in Canvara reactors, reducing slag generation and metal losses by more than 50%. The reagent for the desulfurization of molten iron in a Canvara reactor according to claim 1, which reduces the temperature loss by more than 15%. The reagent for the desulfurization of molten iron in a Canvara reactor according to claim 1, which reduces the loss of desulfurization by more than 20%.