CN104805253A - Desulfurizing agent for RH deep desulfurization processing of weakly-deoxidized low-carbon steel and preparation method of desulfurizing agent - Google Patents

Abstract

The invention discloses a desulfurizing agent for the RH deep desulfurization processing of weakly-deoxidized low-carbon steel and a preparation method of the desulfurizing agent. The desulfurizing agent comprises the following components in percentage by weight: 50% to 56% of CaO, 18% to 22% of Al2O3, 10% to 15% of CaF2, 4% to 8% of BaO, 3% to 5% of Na2O, and the rest of impurities. The preparation method of the desulfurizing agent for the RH deep desulfurization processing of the weakly-deoxidized low-carbon steel comprises the following steps of (1), weighing to take the raw materials with corresponding masses according to the percentage, of each component, by weight; (2), crushing and mixing the raw materials which are weighed to be taken in the step (1); (3), fusing the mixed raw materials in an electric furnace, and carrying out water quenching processing on slag to form blocky slag; (4), finally, crushing the blocky slag obtained in the step (3) by adopting a crusher until particle sizes are 3mm to 10mm. The desulfurization fusing point of a CaO-Al2O3 slag system provided by the invention is low, and the desulfurization efficiency is high.

Description

A kind of weak deoxidation soft steel RH dark desulfurization process sweetening agent and preparation method thereof

Technical field

The present invention relates to molten steel furnace external refining field, particularly relate to weak deoxidation soft steel refining art, specifically, relate to a kind of weak deoxidation soft steel RH dark desulfurization process sweetening agent and preparation method thereof.

Background technology

In various external refining equipment, RH vacuum refinement has become one of most important means of smelting high quality variety steel.From its refining function, except the basic function of vacuum outgas, also effectively can be used for decarburization and deoxidation.In low-carbon (LC) and ultra low-carbon steel are produced, converter tapping adopts weak deoxidation, carries out oxygen decarburization or carbon deoxidation at RH.But, weak deoxidation molten steel due to dissolved oxygen content in steel high, slag beneficiation is comparatively strong, and therefore before RH operation, slag does not have sweetening power substantially, and this brings problem to the production of some ultra-low sulphur steel.Although can adopt the dark desulfurization of hot metal pretreatment and converter control sulphur technology, considerable iron and steel enterprise is limited by the restriction of starting material condition, and molten iron pretreatment slag pulls out the impact that sulphur is returned in the converter caused not to the utmost, and in steel, sulphur content still may be in higher level.

At present, in the process of steel-making, conventional sweetening agent mainly contains CaO-CaF ₂, CaO-Al ₂o ₃slag system, wherein CaO-CaF ₂be the slag system with the highest sweetening power of generally acknowledging at present, under same task, sorbent consumption amount is minimum.But in actual production, adopting throw-in play, using this sweetening agent when entering desulfurization process to weak deoxidized steel, slagging speed is slow, and sweetening effectiveness is undesirable and unstable.Notification number be CN 101736133 patent discloses pre-melted type RH vacuum refining desulfurizing agent and using method thereof, to weight percentages of components be: CaO 65 ~ 80%, CaF ₂the sweetening agent of 20 ~ 35% carries out fritting process to be made its uniform composition and reduces its fusing point.But CaO-CaF ₂in fluorochemical can Eroded dipping tube, cause environmental pollution.Therefore people have developed low fluorine and floride-free sweetening agent in succession.

For CaO-Al ₂o ₃slag system, for improving sweetening power, sweetening agent basicity is high, and the fusing point of sweetening agent will increase substantially.Notification number is the floride-free RH sweetening agent of a kind of high alkalinity of patent disclosure of CN 102051443, by adding BaO 6 ~ 8%, B ₂o ₃4 ~ 5% improve sweetening agent optical basicity and reduce its fusing point.Notification number is a kind of preliminary melting type vacuum smelting desulfurizing agent of patent disclosure of CN 101314806 and preparation method thereof, after unslaked lime and sintered bauxite fritting, then adds quickened lime, magnesia, aluminum shot, technical pure BaCO ₃, fluorite mechanically mixing makes sweetening agent, it is by fritting and add technical pure BaCO ₃improve it and improve its desulfuration efficiency.Notification number is a kind of non-oriented electrical steel RH of patent disclosure vacuum-treat sweetening agent of CN 102199687 and preparation method thereof and sulfur method, and it is by adding CaF ₂5 ~ 10% reduce its fusing point as fusing assistant.

Notification number be CN 1389579 patent discloses a kind of pre-molten low-melting point composite calcium aluminate desulfurizer and preparation method thereof, sweetening agent mainly consists of: bauxitic clay is (with Al ₂o ₃content meter) 30 ~ 60%, calcium oxide 40 ~ 70%.Notification number be CN 1804055 patent discloses a kind of RH vacuum treatment deep desulfurization pre-melted slag used for ultra-low-carbon steel and preparation method thereof, it mainly consists of: CaO 48 ~ 56%, Al ₂o ₃33 ~ 43%, MgO 0.2 ~ 5.0%, SiO ₂2.5 ~ 6.0%, TiO ₂≤ 1.9, C≤0.05.Notification number be CN 101463412 a kind of RH vacuum oven of patent disclosure in pre-melted slag deep desulfuration method, sweetening agent mainly consists of: CaO 55 ~ 60%, Al ₂o ₃15 ~ 25%, MgO 0 ~ 5.0%, SiO ₂2.0 ~ 8.0%, S 0 ~ 0.06%, moisture 0 ~ 0.5%.Above three patents by fritting, but from its composition, still have higher fusing point, these patent CaO/Al simultaneously ₂o ₃ratio or CaO/SiO ₂lower, the needs of the dark desulfurization of RH vacuum refining process can not be met.In addition, weak deoxidation soft steel adopts Al final deoxygenation can cause more Al after RH decarburization terminates ₂o ₃enter in slag, the composition of sweetening agent can be changed, thus reduce desulfuration efficiency.

Summary of the invention

For prior art above shortcomings, the object of the present invention is to provide a kind of weak deoxidation soft steel RH dark desulfurization process sweetening agent, to solve CaO-Al ₂o ₃slag system desulfurization fusing point is high, the problem that desulfuration efficiency is low; The invention also discloses the preparation method of weak deoxidation soft steel RH dark desulfurization process sweetening agent.

In order to solve the problems of the technologies described above, the technical solution used in the present invention is such: a kind of weak deoxidation soft steel RH dark desulfurization process sweetening agent, is characterized in that: its compositions in weight percentage is, CaO 50 ~ 56%, Al ₂o ₃18 ~ 22%, CaF ₂10 ~ 15%, BaO 4 ~ 8%, Na ₂o 3 ~ 5%, surplus is impurity.

Further, its component also comprises SiO ₂and MgO, and SiO ₂, MgO is by weight percentage: SiO ₂≤ 4%, MgO≤3%.

Further, the particle diameter of described sweetening agent is 3 ~ 10mm; Thus its burn-off rate can be accelerated, and sweetening agent is made not to be inhaled into vacuum webmaster because particle diameter is too small when RH uses.

A preparation method for above-mentioned weak deoxidation soft steel RH dark desulfurization process sweetening agent, is characterized in that: comprise the steps:

1) according to the weight percent of each component, the calcite of corresponding mass, barium carbonate, fluorite, soda ash, sintered bauxite raw material is taken;

2) raw material crushing step 1) taken also mixes, and wherein, each raw material adopts crusher in crushing to below particle diameter 3mm, then adopts mechanical stirring mixing;

3) by the melting in electric furnace of mixed raw material, keep after fusing slagging tap after at least 1 hour completely, and Water Quenching is carried out to slag form block slag;

4) last, block slag step 3 obtained adopts crusher in crushing to particle diameter to be 3 ~ 10mm.

Compared with prior art, tool of the present invention has the following advantages:

1, consider that weak deoxidation soft steel adopts Al final deoxygenation can cause more Al after RH decarburization terminates ₂o ₃enter in slag, can change the composition of sweetening agent, the present invention improves (CaO%)/(Al in sweetening agent ₂o ₃%), thus improve desulfuration efficiency; Meanwhile, due to sweetening agent during the desulfurization of RH throw-in play and molten steel short for action time, therefore the present invention can be applicable to the desulfurization of RH throw-in play better.

2, the present invention adds a small amount of CaF in sweetening agent ₂, BaCO ₃with the Na with strong sweetening power ₂cO ₃and carrying out fritting process to reduce its fusing point, the particle diameter reducing sweetening agent reduces fusing time to accelerate its burn-off rate, to strengthen its reacting dynamics condition, thus improves desulfuration efficiency.

Embodiment

Below in conjunction with embodiment, the invention will be further described.

In order to meet the needs of dark desulfurization, sweetening agent must have higher sulfur capacity Cs, and weak deoxidation soft steel adopts Al final deoxygenation can cause more Al after RH decarburization terminates ₂o ₃enter in slag, the composition of sweetening agent can be changed, therefore require that sweetening agent has higher (CaO%)/(Al ₂o ₃%).A kind of weak deoxidation soft steel RH of the present invention dark desulfurization process sweetening agent, its compositions in weight percentage is, CaO 50 ~ 56%, Al ₂o ₃18 ~ 22%, CaF ₂10 ~ 15%, BaO 4 ~ 8%, Na ₂o 3 ~ 5%, surplus is impurity.With addition of a small amount of CaF in sweetening agent ₂and reduce its fusing point by fritting process; Finally obtain sulfur capacity high, low-melting sweetening agent.The present invention is guaranteeing (CaO%)/(Al in sweetening agent ₂o ₃%) in the sufficiently high situation of ratio, take into account sweetening agent simultaneously and have lower fusing point, thus make desulfuration efficiency high, desulfurization time is short, thus is applicable to the desulfurization of RH throw-in play better.

During concrete enforcement, its component also comprises SiO ₂and MgO, and SiO ₂, MgO is by weight percentage: SiO ₂≤ 4%, MgO≤3%.In the course of processing, the particle diameter of described sweetening agent is 3 ~ 10mm.

Embodiment, the composition of sweetening agent is in table 1.

The chemical composition (% by weight) of table 1 sweetening agent

Formula	CaO	Al 2O 3	CaF2	BaO	NaO	SiO 2	MgO
								A	55.72	18.94	10.73	7.78	3.36	1.21	1.56
B	51.48	21.67	12.12	6.21	4.92	2.05	1.32
								C	50.08	18.55	13.78	5.10	3.78	3.89	2.87
D	52.78	19.05	14.51	4.02	3.10	3.13	0.86

Field experiment is carried out with Ultra-low carbon electrical steel for testing steel grade according to weak deoxidation soft steel RH sulfur method provided by the invention, often bag Metal Weight about 200 tons, in RH molten steel Al final deoxidation alloy, steel after [O]≤5ppm, sweetening agent adds vacuum chamber by 4 ~ 6Kg/t steel in two batches from hopper and carries out desulfurization, often criticizes feeding interval time 2 ~ 3min.Specifically add desulfurization dosage to enter the station sulphur content adjustment according to RH.RH enters the station molten steel and desulfurizer therefor composition in table 2, and RH sets off molten steel composition and desulfurization degree in table 3.

Table 2 RH enters the station molten steel composition (% by weight) and desulfurizer therefor

Table 3 RH departures molten steel composition (% by weight) and desulfurization degree

Heat	C	Si	Mn	P	S	Als	Al	Desulfurization degree/%
									1	0.0065	0.713	0.267	0.014	0.0022	0.295	0.287	26.67
2	0.0053	0.694	0.266	0.016	0.0034	0.301	0.291	29.17
									3	0.0054	0.714	0.186	0.016	0.0052	0.268	0.261	25.71
4	0.0053	0.729	0.208	0.014	0.0036	0.291	0.276	36.84
									5	0.005	0.738	0.234	0.022	0.0037	0.267	0.261	26.00
6	0.0051	0.728	0.228	0.016	0.006	0.3	0.291	25.00
									7	0.005	0.69	0.23	0.014	0.0049	0.33	0.329	24.62
8	0.006	0.7	0.22	0.014	0.0042	0.33	0.33	30.00
									9	0.055	0.719	0.193	0.014	0.0057	0.29	0.282	22.97
10	0.006	0.725	0.198	0.014	0.005	0.309	0.295	21.88
									11	0.0049	0.734	0.198	0.014	0.005	0.301	0.146	28.57
12	0.0062	0.696	0.208	0.014	0.0072	0.295	0.284	34.55

As can be seen from above embodiment, the sweetening agent adopting present method to prepare and sulfur method carry out dark desulfurization at RH to the weak deoxidized steel of low-carbon (LC) and S can be controlled in lower level.

A preparation method for above-mentioned weak deoxidation soft steel RH dark desulfurization process sweetening agent, comprises the steps:

1) according to the weight percent of each component, calcite (or Wingdale), barium carbonate, fluorite, soda ash, the sintered bauxite raw material of corresponding mass is taken.

2) raw material crushing step 1) taken also mixes, and wherein, each raw material adopts crusher in crushing to below particle diameter 3mm, then adopts mechanical stirring mixing.

3) by the melting in electric furnace of mixed raw material, keep after fusing slagging tap after at least 1 hour completely, and Water Quenching is carried out to slag form block slag.

4) last, block slag step 3 obtained adopts crusher in crushing to particle diameter to be 3 ~ 10mm.

Finally it should be noted that, above embodiment is only in order to illustrate technical scheme of the present invention but not restriction technologies scheme, those of ordinary skill in the art is to be understood that, those are modified to technical scheme of the present invention or equivalent replacement, and do not depart from aim and the scope of the technical program, all should be encompassed in the middle of right of the present invention.

Claims (4)

1. a weak deoxidation soft steel RH dark desulfurization process sweetening agent, is characterized in that: its compositions in weight percentage is, CaO 50 ~ 56%, Al ₂o ₃18 ~ 22%, CaF ₂10 ~ 15%, BaO 4 ~ 8%, Na ₂o 3 ~ 5%, surplus is impurity.

2. weak deoxidation soft steel RH according to claim 1 dark desulfurization process sweetening agent, is characterized in that: its component also comprises SiO ₂and MgO, and SiO ₂, MgO is by weight percentage: SiO ₂≤ 4%, MgO≤3%.

3. weak deoxidation soft steel RH according to claim 1 dark desulfurization process sweetening agent, is characterized in that: the particle diameter of described sweetening agent is 3 ~ 10mm.

4. a preparation method for weak deoxidation soft steel RH dark desulfurization process sweetening agent as claimed in claim 1, is characterized in that: comprise the steps:

1) according to the weight percent of each component, the calcite of corresponding mass, barium carbonate, fluorite, soda ash, sintered bauxite raw material is taken;

2) raw material crushing step 1) taken also mixes, and wherein, each raw material adopts crusher in crushing to below particle diameter 3mm, then adopts mechanical stirring mixing;

3) by the melting in electric furnace of mixed raw material, keep after fusing slagging tap after at least 1 hour completely, and Water Quenching is carried out to slag form block slag;

4) last, block slag step 3 obtained adopts crusher in crushing to particle diameter to be 3 ~ 10mm.