A smelting process for direct alloying of molybdenum disulfide

Abstract

The invention discloses a smelting process for direct alloying of molybdenum disulfide, which relates to the technical field of steel production. According to the sulfur content of the steel grade, the addition amount of molybdenum disulfide is reasonably controlled. According to the sulfur increase amount, the slag-making and deoxidizing operations for desulfurization and sulfur control are formulated, with high efficiency, reaching the end-point sulfur content of the steel grade. And the calcium treatment requirements for ensuring the fluidity of molten steel are put forward, which can cancel the influence on the composition and the fluidity of molten steel caused by sulfur increase with molybdenum disulfide, and achieve cost savings.

Description

Technical Field

[0001] The present invention relates to the technical field of steel production, and particularly to a smelting process for direct alloying of molybdenum disulfide. Background Art

[0002] In recent years, the price of ferromolybdenum has remained at a relatively high level. As an important raw material for steelmaking alloys, it accounts for a large proportion of the cost in molybdenum-containing steels. In order to reduce the molybdenum addition cost and increase the gross profit per ton of steel, enterprises have been seeking suitable alternative raw materials for ferromolybdenum. The use of molybdenum oxide to directly alloy steel has been widely applied at home and abroad. Compared with using ferromolybdenum to increase molybdenum, the superiority of using molybdenum oxide to increase molybdenum is obvious. As the raw material for producing molybdenum oxide, molybdenum concentrate (MoS2) contains a high content of molybdenum. Finding a method to directly use molybdenum concentrate (molybdenum disulfide MoS2), the raw material for refining molybdenum oxide, for molybdenum addition in the steelmaking process can achieve greater cost reduction.

[0003] The technical problems existing in directly using molybdenum concentrate for alloying are as follows:

[0004] Sulfur is a harmful element in steel grades. Due to the high sulfur content in molybdenum concentrate, it will cause an increase in the sulfur content in steel, resulting in an excessive end-point sulfur;

[0005] If desulfurization is required, it is necessary to increase the amount of refining slag and deoxidizer, increase stirring, resulting in an increase in the consumption of slag materials and deoxidizers. At the same time, if the amount of slag is large and the stirring control is inappropriate, it is also easy to cause slag entrainment;

[0006] 3. The sulfur content control at the refining end-point is on the high side. If the calcium treatment amount is inappropriate, it is easy to generate high-melting-point calcium sulfide inclusions, and the fluidity of the molten steel is poor. Summary of the Invention

[0007] In view of the above technical problems, the present invention overcomes the disadvantages of the prior art and provides a smelting process for direct alloying of molybdenum disulfide, including molybdenum concentrate composition and packaging requirements, converter tapping end-point and alloying control, addition amount and addition timing of molybdenum concentrate in refining, deoxidation and slag formation after addition, composition adjustment, and calcium treatment, as follows:

[0008] (1) Molybdenum concentrate composition requirements: Mo≥44.0%, P≤0.05%, S≤40.0%, moisture≤10.0%;

[0009] (2) Molybdenum concentrate packaging requirements: 20kg±2kg / bag;

[0010] (3) During the alloying process of tapping from the converter or electric furnace, the molybdenum composition is not adjusted. 4 - 5 kg of lime is added during the alloying process of tapping. After tapping, a sample is taken. After sampling, the molten steel is lifted to the refining furnace. According to the molybdenum and sulfur composition requirements of the steel grade, after electrochemically melting the slag, molybdenum concentrate is added, and the addition amount is 1 - 2 kg / ton of steel;

[0011] (4) After adding molybdenite concentrate, power is supplied. During the power supply process, the bottom stirring Ar is increased to 250 - 350 Nl / min, 3 - 4 kg of lime per ton of steel is added. After adding, 0.4 - 0.8 kg of aluminum wire and 0.8 - 1 kg of silicon carbide are used for diffusion deoxidation during the power supply process, and white slag operation is carried out;

[0012] (5) Before sampling, the bottom stirring Ar is increased to 450 - 600 Nl / min. After stirring for 1 - 2 min, sampling is carried out. According to the sample analysis of molybdenum and sulfur components, ferromolybdenum is adjusted according to the target molybdenum component of the steel grade. According to the sulfur requirement of the steel grade, 1 - 2 kg of lime, 0.2 - 0.3 kg of aluminum wire, and 0.4 - 0.6 kg of silicon carbide are continuously added for diffusion deoxidation and desulfurization. During the power supply process, the bottom stirring Ar is increased to 250 - 350 Nl / min;

[0013] (6) Before sampling, the bottom stirring Ar is increased to 450 - 600 Nl / min. After stirring for 1 - 2 min, sampling is carried out. According to the sample analysis of molybdenum and sulfur components, ferromolybdenum is adjusted according to the target molybdenum component of the steel grade. According to the sulfur requirement of the steel grade, 0.4 - 0.6 kg of silicon carbide is continuously added for diffusion deoxidation and desulfurization. During the power supply process, the bottom stirring Ar is increased to 250 - 350 Nl / min;

[0014] (7) When the molybdenum at the refining end reaches the component requirement and the sulfur content needs to be controlled ≤ 0.008%, calcium treatment can be carried out. After calcium treatment, static stirring is carried out for 10 - 15 min and then casting is carried out.

[0015] The further limited technical solution of the present invention is:

[0016] For the smelting process of direct alloying of molybdenum disulfide described above, in steps (3), (4), and (7), the sulfur requirement of the steel grade is ≤ 0.015%.

[0017] For the smelting process of direct alloying of molybdenum disulfide described above, in step (3), molybdenite concentrate is added after 5 - 8 min of power supply for slag melting.

[0018] For the smelting process of direct alloying of molybdenum disulfide described above, in step (4), lime is added in 2 - 3 batches.

[0019] For the smelting process of direct alloying of molybdenum disulfide described above, in step (5), sampling is carried out after 8 - 12 min of power supply.

[0020] For the smelting process of direct alloying of molybdenum disulfide described above, in step (6), sampling is carried out after 8 - 10 min of power supply.

[0021] The beneficial effects of the present invention are:

[0022] (1) According to the sulfur content of the steel grade, the addition amount of molybdenum disulfide is reasonably controlled. Based on the sulfur increase amount, the slag-making and deoxidation operations for desulfurization and sulfur control are formulated, with high efficiency, reaching the end-point sulfur content of the steel grade. And the calcium treatment requirements for ensuring the fluidity of molten steel are put forward, which can cancel the influence of molybdenum disulfide sulfur addition on the composition and the fluidity of molten steel, achieving cost savings.

[0023] (2) Under the condition of ensuring the controllability of the end-point sulfur content and fluidity of the steel grade, the invention realizes the substitution of molybdenum oxide for molybdenum addition to reduce costs. The process flow is simple and clear, with strong operability and easy to control. Embodiment Example

[0024] A smelting process for direct alloying of molybdenum disulfide provided by this example includes the following steps:

[0025] The composition of molybdenum concentrate used: Mo: 45.4%, P: 0.010%, S: 30.96%, moisture: 6.0%;

[0026] The molybdenum concentrate is packaged in bags (packages) of 20 kg ±2 kg per bag to facilitate the control of the addition amount;

[0027] During the alloying process of tapping from the converter or electric furnace, the molybdenum composition is not adjusted. 500 kg of lime is added during the tapping process, and stirring is carried out during the tapping process. After the tapping is completed, it is opened to the ladle position for sampling. After sampling, the molten steel is lifted to the refining furnace. The tapping amount is 120.26 tons. Sampling analysis shows Mo: 0.001%, S: 0.013%;

[0028] After the refining furnace is powered on for slag melting for 5 min, molybdenum concentrate is added, and the addition amount is 120 kg (the sulfur requirement of the steel grade is ≤0.015%);

[0029] After adding the molybdenum concentrate, power is supplied. During the power supply process, the bottom stirring Ar is increased to 250 Nl / min, and 380 kg of lime is added in two batches (the lime addition amount for the steel grade with sulfur requirement ≤0.015% is 4 - 6 kg). After adding, 50 kg of aluminum wire and 100 kg of silicon carbide are used for diffusion deoxidation during the power supply process, and white slag operation is carried out;

[0030] Sampling is carried out 8 min after power supply. Before sampling, the bottom stirring Ar is increased to 450 Nl / min and stirred for 1 min before sampling. The sample analysis shows Mo: 0.044%, S: 0.019%. Ferromolybdenum is adjusted according to the target molybdenum composition of the steel grade, and 120 kg of lime, 25 kg of aluminum wire, and 50 kg of silicon carbide are continuously added for diffusion deoxidation and desulfurization. During the power supply process, the bottom stirring Ar is increased to 250 Nl / min;

[0031] Sampling is carried out after 8 minutes of power supply. Before sampling, the bottom stirring Ar is increased to 450 Nl / min and stirred for 1 minute before sampling. The sample analysis shows Mo: 0.15%, S: 0.012%. According to the molybdenum and sulfur components in the sample analysis, ferromolybdenum is adjusted according to the target molybdenum component of the steel grade. According to the sulfur requirement of the steel grade, 50 kg of silicon carbide is continuously added for diffusion deoxidation and desulfurization. During the power supply process, the bottom stirring Ar is increased to 250 Nl / min;

[0032] Sampling is carried out after 5 minutes of power supply. The sample analysis shows Mo: 0.16%, S: 0.008%. Calcium treatment is carried out, and after calcium treatment, it is statically stirred for 10 minutes and then poured. Example

[0033] A smelting process for direct alloying of molybdenum disulfide provided by this example includes the following steps:

[0034] The composition of molybdenum concentrate used: Mo: 45.4%, P: 0.010%, S: 30.96%, moisture: 6.0%;

[0035] The molybdenum concentrate is packaged in 20 kg ± 2 kg / bag (package) for easy control of the addition amount;

[0036] During the alloying process of tapping from the converter or electric furnace, the molybdenum component is not adjusted. 600 kg of lime is added during the tapping process, and stirring is carried out during the tapping process. After tapping, it is opened to the ladle position for sampling. After sampling, the molten steel is lifted to the refining furnace. The tapping amount is 122.14 tons. The sample analysis shows Mo: 0.001%, S: 0.012%;

[0037] After 8 minutes of slag melting by power supply in the refining furnace, molybdenum concentrate is added, and the addition amount is 244 kg (the sulfur requirement of the steel grade is ≤ 0.015%);

[0038] After adding molybdenum concentrate, power supply is carried out. During the power supply process, the bottom stirring Ar is increased to 350 Nl / min. 500 kg of lime is added in 3 batches (the lime addition amount for the steel grade with sulfur requirement ≤ 0.015% is 4 - 6 kg). After adding, 100 kg of aluminum wire and 120 kg of silicon carbide are used for diffusion deoxidation during the power supply process, and white slag operation is carried out;

[0039] Sampling is carried out after 12 minutes of power supply. Before sampling, the bottom stirring Ar is increased to 600 Nl / min and stirred for 2 minutes before sampling. The sample analysis shows Mo: 0.072%, S: 0.024%. Ferromolybdenum is adjusted according to the target molybdenum component of the steel grade. 240 kg of lime, 40 kg of aluminum wire, and 75 kg of silicon carbide are continuously added for diffusion deoxidation and desulfurization. During the power supply process, the bottom stirring Ar is increased to 350 Nl / min;

[0040] Sampling is carried out after power supply for 10 minutes. Before sampling, the bottom stirring Ar is increased to 600 Nl / min and stirred for 2 minutes, then sampling is carried out. The sample analysis shows Mo: 0.15%, S: 0.012%. According to the sample analysis of molybdenum and sulfur components, ferromolybdenum is adjusted according to the target molybdenum component of the steel grade. According to the sulfur requirement of the steel grade, 75 kg of silicon carbide is continuously added for diffusion deoxidation and desulfurization. During the power supply process, the bottom stirring Ar is increased to 350 Nl / min;

[0041] Sampling is carried out after power supply for 5 minutes. The sample analysis shows Mo: 0.16%, S: 0.006%. Calcium treatment is carried out, and after calcium treatment, it is statically stirred for 15 minutes and then poured.

[0042] After batch tests on molybdenum concentrate, looking at each furnace, the Mo recovery rate of molybdenum concentrate is relatively stable, with an average value of 96.53%, which is similar to the ferromolybdenum recovery rate; the S content is stably controlled, and the average S return rate is 34.05%. Although the S content of molybdenum concentrate is relatively high, under reasonable addition amounts, by tracking deoxidation and increasing the deoxidation of aluminum wire in the early stage of refining and increasing part of the lime amount, normal desulfurization in the refining process can be achieved.

[0043] After comparison, the price difference per ton-degree between the current molybdenum concentrate and ferromolybdenum is 500 yuan. For every 100 kg of molybdenum concentrate added, with a Mo content of 45% and the molten steel amount calculated as 125 tons on average, and the Mo recovery rate calculated as 96.53% according to the above tracking results, the theoretical increase in Mo is 0.035%. The cost reduction per ton of steel due to the substitution price difference of molybdenum is 14 yuan / ton of steel. After removing the deoxidation of aluminum wire in the early stage of refining and the increase in lime amount of 3.41 yuan / ton of steel, every 100 kg substitution of molybdenum concentrate can reduce the cost of molybdenum-containing steel by 10.59 yuan / ton of steel.

[0044] In addition to the above embodiments, the present invention can also have other implementation manners. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A smelting process for direct alloying of molybdenum disulfide, characterized in that: It includes molybdenite concentrate composition and packaging requirements, converter tapping end point and alloying control, addition amount and addition timing of molybdenite concentrate in refining, deoxidation and slag making after addition, composition adjustment, and calcium treatment, which are specifically as follows: (1)Composition requirements of molybdenite concentrate: Mo≥44.0%, P≤0.05%, S≤40.0%, moisture≤10.0%; (2)Packaging requirements of molybdenite concentrate: 20kg±2kg / bag; (3)During the alloying process of converter or electric furnace tapping, the molybdenum composition is not adjusted. 4 - 5kg of lime is added during the alloying process of tapping. After tapping, a sample is taken. After sampling, the molten steel is lifted to the refining furnace. According to the molybdenum and sulfur composition requirements of the steel grade, molybdenite concentrate is added after electrochemically melting the slag, and the addition amount is 1 - 2kg per ton of steel; (4)After adding molybdenite concentrate, power is supplied. During the power supply process, the bottom stirring Ar is increased to 250 - 350Nl / min, 3 - 4kg of lime per ton of steel is added. During the power supply process after addition, 0.4 - 0.8kg of aluminum wire and 0.8 - 1kg of silicon carbide are used for diffusion deoxidation, and white slag operation is carried out; (5)Before sampling, the bottom stirring Ar is increased to 450 - 600Nl / min. After stirring for 1 - 2min, a sample is taken. According to the analysis of molybdenum and sulfur components in the sample, ferromolybdenum is adjusted according to the target molybdenum composition of the steel grade. According to the sulfur requirement of the steel grade, 1 - 2kg of lime, 0.2 - 0.3kg of aluminum wire, and 0.4 - 0.6kg of silicon carbide are continuously added for diffusion deoxidation and desulfurization. During the power supply process, the bottom stirring Ar is increased to 250 - 350Nl / min; (6)Before sampling, the bottom stirring Ar is increased to 450 - 600Nl / min. After stirring for 1 - 2min, a sample is taken. According to the analysis of molybdenum and sulfur components in the sample, ferromolybdenum is adjusted according to the target molybdenum composition of the steel grade. According to the sulfur requirement of the steel grade, 0.4 - 0.6kg of silicon carbide is continuously added for diffusion deoxidation and desulfurization. During the power supply process, the bottom stirring Ar is increased to 250 - 350Nl / min; (7)When the molybdenum at the refining end point meets the composition requirements and the sulfur content needs to be controlled ≤0.008% can calcium treatment be carried out. After calcium treatment, static stirring is carried out for 10 - 15min and then pouring; For the steps (3), (4), and (7) above, the sulfur requirement of the steel grade is ≤0.015%.

2. The smelting process of direct alloying of molybdenum disulfide according to claim 1, characterized in that: For the step (3), molybdenite concentrate is added 5 - 8min after electrochemically melting the slag.

3. The smelting process for direct alloying of molybdenum disulfide according to claim 1, characterized in that: For the step (4), lime is added in 2 - 3 batches.

4. The smelting process for direct alloying of molybdenum disulfide according to claim 1, characterized in that: For the step (5), sampling is carried out 8 - 12min after power supply.

5. The smelting process for direct alloying of molybdenum disulfide according to claim 4, characterized in that: For the step (6), sampling is carried out 8 - 10min after power supply.