CN114875206A - Phosphorus removal and chromium protection double process for smelting chromium-containing high-phosphorus metal liquid from laterite-nickel ore - Google Patents
Phosphorus removal and chromium protection double process for smelting chromium-containing high-phosphorus metal liquid from laterite-nickel ore Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
- C21C7/0645—Agents used for dephosphorising or desulfurising
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- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
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Abstract
The invention discloses a phosphorus and chromium removing dual process for smelting chromium-containing high-phosphorus metal liquid from laterite-nickel ore, belonging to the technical field of ferrous metallurgy. The dual process method for removing phosphorus and protecting chromium comprises the following steps: the method is characterized in that the P is respectively added into and on the surface of the chromium-containing high-phosphorus metal liquid obtained by smelting the laterite-nickel ore 2 O 5 Is lower than Cr 2 O 3 Generating free energy additives, namely dephosphorized core-spun yarns and top slag, so that chromium and phosphorus in the interior and on the surface of the chromium-containing high-phosphorus metal liquid smelted from the laterite-nickel ore are selectively oxidized; wherein: the chromium is retained in the molten metal, the phosphorus oxide generated in the molten metal floats to the top slag, and the phosphorus oxide generated on the surface layer of the molten metal is directly retained in the top slag. The invention has the advantages of high comprehensive utilization value of the laterite-nickel ore, high quality of stainless steel and alloy steel, simple and convenient process operation, good rhythm matching property, multi-stage dephosphorization, rich slag system resources, no toxicity and harm and phosphorus content energyCan be reduced to below 0.05 percent, and has the beneficial effect that the chromium retention rate is above 84 percent.
Description
Technical Field
The invention belongs to the technical field of ferrous metallurgy, and relates to a phosphorus and chromium removing and preserving double process for smelting chromium-containing high-phosphorus metal liquid from laterite-nickel ore.
Background
At present, dephosphorization is carried out in a conventional mode under the condition of molten iron in an oxidizing atmosphere, so that chromium in the molten iron is inevitably removed at the same time, and the waste of chromium element is caused.
The reason is that the phosphorus and the chromium have similarity in the redox thermodynamic conditions of the molten iron, namely under the condition of 1350-; in the reduction state of the molten metal, the chromium enters the molten metal and phosphorus enters the molten metal at the same time, which causes serious deterioration of the quality of the molten metal. In particular to smelting chromium-containing high-phosphorus molten iron from laterite-nickel ore.
The laterite-nickel ore is a metal resource with extremely large stock of iron, nickel, chromium and cobalt, and with the increasing demand of nickel, nickel in the laterite-nickel ore can be well utilized, but chromium and phosphorus with higher content in the laterite-nickel ore cannot be effectively applied.
Wherein, when nickel is obtained from the laterite-nickel ore, chromium and iron of the laterite-nickel ore need to be removed in order to obtain higher nickel purity; because the process is completed under the oxidation condition, phosphorus, iron and chromium enter into a slag phase together, and the phosphorus in the laterite-nickel ore is removed along with the removal of the chromium and the iron. However, nickel, chromium and iron are the main components of alloy steels and stainless steels in the smelting process for obtaining raw materials of alloy steels and stainless steels, and the value of chromium is great, which is unfortunately removed for dephosphorization and enters into slag phase.
In the existing comprehensive utilization method of laterite-nickel ore, when smelting is carried out by adopting an ore furnace, only the yield of iron is reduced and the yield of chromium is not considered in order to remove phosphorus or enrich nickel, so that molten metal (molten iron and molten steel) with low phosphorus content is obtained. During blast furnace smelting, iron, chromium and nickel can be completely recovered, and harmful element phosphorus can be also recovered, so that the following difficult problems in the steelmaking process are caused: the contradiction between chromium retention and phosphorus removal.
Since the seventies of the last century, dephosphorization processes have been widely studied. For example, dephosphorization studies under reducing conditions have been conducted in China and Japan. Although the reduction dephosphorization has a good dephosphorization effect, the generated Ca 3 P 2 With water vapourContact to produce highly toxic pH 3 Therefore, the research is not practical in the end.
At the same time, Japan iron and steel enterprises seek to adopt alkali metal oxides for slagging, oxidizing and dephosphorizing. E.g. using Li 2 CO 3 10％、CaO 14％、CaF 2 And in the slag system containing 47 percent and 29 percent of FeO, 70kg of dephosphorization slag is added into each ton of molten iron as a stainless steel raw material containing 2.5 to 6.0 percent of carbon, 11 to 25 percent of chromium and less than 8 percent of nickel at the temperature of 1400 ℃ and 1500 ℃ for dephosphorization pretreatment, and the dephosphorization rate can reach 60 percent.
The decarburization, dephosphorization and chromium preservation in CN 112375974A are realized by complex operations such as molten iron smelting of high-chromium molten iron, blowing of a top-bottom combined blown converter, constant oxygen pressure lance position changing operation and the like, and are not suitable for large-scale industrial production.
In a large steelmaking process, the methods cannot be widely used in an industrial scale due to poor rhythm matching or scarcity and toxicity of slag resources.
In an enterprise adopting laterite nickel ore resources to smelt stainless steel, the current method for protecting chromium and reducing phosphorus is to add prefabricated iron or steel with low phosphorus content into metal liquid with high phosphorus content and high chromium content, which can increase the process cost.
Therefore, in view of the existing technical problems of huge storage of laterite nickel ore resources and chromium and phosphorus conservation, the process which can realize the good matching of the process rhythm of phosphorus and chromium removal in the large steel-making process, rich and non-toxic slag system resources, the reduction of the phosphorus content to below 0.05 percent and the chromium conservation rate to above 84 percent is found, and the purposes of ensuring the smooth production and reducing the cost are very necessary.
Disclosure of Invention
The technical problem solved by the invention is that in the process of smelting laterite-nickel ore resources, phosphorus and chromium can be removed simultaneously in order to remove phosphorus or enrich nickel, thereby causing the waste of chromium resources; during blast furnace smelting, iron, chromium and nickel can be simultaneously obtained together with harmful element phosphorus, and although chromium resources are not wasted, the defect that the performance of molten metal is deteriorated due to high phosphorus content exists.
In order to solve the technical problems, the invention provides the following technical scheme:
a phosphorus and chromium removing and maintaining double process for smelting chromium-containing high-phosphorus metal liquid from laterite-nickel ore comprises the following steps: the method is characterized in that the P is respectively added into and on the surface of the chromium-containing high-phosphorus metal liquid obtained by smelting the laterite-nickel ore 2 O 5 Is lower than Cr 2 O 3 Generating free energy additive to selectively oxidize chromium and phosphorus in the interior and on the surface of the chromium-containing high-phosphorus metal liquid obtained by smelting the laterite-nickel ore; wherein: the chromium is retained in the molten metal, and the phosphorus oxide formed in the molten metal is reacted by the additive to release CO 2 Forming bubbles, dragging and floating to the top slag, and directly remaining the phosphorus oxide generated on the surface layer of the molten metal in the top slag.
Preferably, the additives respectively added into and on the surface of the chromium-containing high-phosphorus metal liquid obtained by smelting the laterite-nickel ore are dephosphorized cored wires and top slag respectively.
Preferably, the dephosphorized cored wire comprises a wire core and an outer-coated steel strip; the core contains an alkali metal compound K 2 CO 3 、Li 2 CO 3 、Na 2 CO 3 At least one of the above-mentioned compounds, and other functional compounds CaO and CaF 2 、FeOx。
Preferably, the composition of the top dross comprises K 2 CO 3 、Li 2 CO 3 、Na 2 CO 3 At least one of them, and a compound CaCO having other functions 3 、CaF 2 、FeOx。
Preferably, in the wire core, the mass of the alkali metal compound accounts for 25-40% of the total mass, and the mass of the compounds with other functions accounts for the following ratio: CaO 10-15%, CaF 2 20-30% of FeOx, 30-40% of FeOx and the balance of inevitable impurities; in the impurities, the content of sulfur, phosphorus, lead, tin, arsenic, antimony and bismuth is as low as possible; strict control of water content<0.5％。
Preferably, the alkali metal compound K 2 CO 3 、Li 2 CO 3 、Na 2 CO 3 The function of (1): the dephosphorization enhancer reduces the free energy of dephosphorization reaction and leads phosphorus to be oxidized preferentially to chromium;
the effect of other functional compounds is as follows:
CaO: the dephosphorization regulating agent is provided by more than one-grade metallurgical lime (CaO > 90%);
CaF 2 : the flux reduces the melting temperature of the dephosphorized top slag and accelerates the melting of the synthetic slag, and is provided by fluorite;
FeOx: oxidizing the phosphorus at the interface of the molten metal slag into P 2 O 5 Provided by low-phosphorus iron oxide scale and hematite;
Cr 2 O 3 : can improve the Cr content of slag phase 2 O 3 The action concentration (activity) of the chromium-containing metal can be reduced, and the Cr generated from the chromium in the metal liquid can be reduced 2 O 3 Oxidation potential.
Preferably, in the top slag, the mass of the alkali metal compound accounts for 10-20% of the total mass; the mass ratios of the compounds with other functions are as follows: ca 2 CO 3 15-25％、CaF 2 20-30 percent of FeOx, 30-40 percent of FeOx and the balance of inevitable impurities.
Preferably, the dual process for removing phosphorus and retaining chromium comprises the following steps: in the initial stage of smelting, the phosphorus content is higher, surface slag is removed, a layer of top slag with the thickness of 200-300mm is covered on the surface layer of the molten metal, and a core-spun yarn is fed into the molten metal by a wire feeding machine; wherein: the speed of feeding the core-spun yarn is determined by the depth of the molten metal and is 90-120 m.min -1 。
Preferably, the dual process for removing phosphorus and retaining chromium comprises the following steps: when AOD molten steel enters LF refining, phosphorus exceeds the standard or does not meet the requirement, a layer of top slag with the thickness of 200-300mm is covered on the surface layer of the molten metal, a cored wire is fed into the molten metal by a wire feeding machine, and the phosphorus content is detected until the phosphorus content reaches the standard.
Preferably, the dual process for removing phosphorus and retaining chromium comprises the following steps: during the smelting process of AOD or other stainless steel, in the middle period of dephosphorization blowing, or for better dephosphorization, replacing top slag with high content of alkali metal compound, and feeding dephosphorization core-spun yarn with higher content of alkali metal compound.
Preferably, the wire cores are uniformly mixed in a powder form, the particle size of the powder is 0.9-1.5mm, and the deeper metal liquid is determined by the depth of the metal liquid and has a larger particle size; the diameter of the dephosphorized cored wire is 14-16mm, and the thickness of the outer-coated steel strip is 0.2-0.4 mm.
Preferably, in the smelting process, the metal liquid needs to be stirred to promote the dephosphorization product to float upwards; wherein the stirring power is 50-150W per ton of molten metal, and the reference is that the surface of the molten metal does not fluctuate greatly.
Compared with the problems of chromium and phosphorus conservation and reduction in the existing laterite-nickel ore smelting process, the technical scheme provided by the invention has the beneficial effects of low phosphorus and chromium removal cost, good efficiency and suitability for large-scale steel smelting:
the phosphorus-removing and chromium-retaining dual process for smelting chromium-containing high-phosphorus metal liquid from laterite-nickel ore overcomes the technical defects of waste of chromium resources and deterioration of performance of metal liquid due to high phosphorus content in the laterite-nickel ore resource smelting process.
The invention utilizes the alkali metal compound to greatly reduce P at 1300-1500 DEG C 2 O 5 So that P is free energy of formation 2 O 5 Is much lower than Cr 2 O 3 Free energy is generated, thereby realizing the selective oxidation of chromium and phosphorus and realizing the thermodynamic condition requirement of chromium-retaining dephosphorization.
The dephosphorizing cored wire is fed into the molten metal, and the cored wire has the best dephosphorizing thermodynamic condition and kinetic condition in the melting and floating process, so that ideal preferential dephosphorization can be realized; alkali metal compound K in the core 2 CO 3 、Li 2 CO 3 、Na 2 CO 3 For reducing P in molten metal 2 O 5 Promotes the preferential oxidation of phosphorus over chromium; CO evolution 2 Gas is generated to form bubbles, and the dephosphorized product is dragged to float upwards from the metal liquid phase to enter the top slag and be absorbed by the top slag.
The invention has the function of covering the top slag on the surface of the molten metal, firstly, the dephosphorization product floating on the molten metal is absorbed, and secondly, the dephosphorization reaction is generated at the interface of the molten metal and the top slag.
The technical scheme provided by the invention has the beneficial effects of high comprehensive utilization value of the laterite-nickel ore, high quality of stainless steel and alloy steel, simple and convenient process operation, good rhythm matching property, multi-link dephosphorization, rich and non-toxic slag system resources, capability of reducing the phosphorus content to be below 0.05 percent and chromium retention rate of above 84 percent.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic flow diagram of a phosphorus removal and chromium retention dual process for smelting chromium-containing high-phosphorus metal liquid from laterite-nickel ore in embodiment 1 of the invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
Example 1:
dephosphorization pretreatment for producing chromium-containing high-phosphorus molten iron in a blast furnace.
60 tons of molten iron are smelted by a blast furnace, the compositions of the discharged iron are shown in Table 1, the phosphorus content is 0.094 percent, and the chromium content is 4.32 percent.
The molten iron has high silicon content, so that the temperature rises quickly during AOD blowing, and even if chromium is lost during blowing, phosphorus is difficult to be effectively removed.
The dual process method for removing phosphorus and protecting chromium comprises the following steps:
s1, determining the final phosphorus content after dephosphorizing the chromium-containing high-phosphorus molten iron
In order to reduce the loss of chromium in the subsequent AOD converting process, as shown in figure 1, the process of double pre-dephosphorization treatment of top slag and dephosphorization core-spun yarn in a foundry ladle during blast furnace tapping is adopted, and dephosphorization is carried out until the phosphorus content is lower than 0.05%.
S2, determining the component content selection and the adding amount of the top slag and the dephosphorized cored wire according to the final content of phosphorus after dephosphorizing the chromium-containing high-phosphorus molten iron
The top slag comprises the following components in percentage by mass：K 2 CO 3 10％、Na 2 CO 3 10％、CaCO 3 20％、CaF 2 20 percent and FeOx 40 percent, and the powder is prepared into powder with the powder granularity of 4mm and bagged, and each bag weighs 50 kg.
The dephosphorized cored wire comprises the following components in percentage by mass: k is 2 CO 3 20％、Na 2 CO 3 20％、CaO 10％、CaF 2 20 percent of the dephosphorized cored wire and 30 percent of FeOx, wherein the diameter of the dephosphorized cored wire is 14-16mm, the granularity of powder is 1.5mm, and the thickness of an externally-coated steel strip is 0.2-0.4 mm.
S3 adding mode of top slag and dephosphorized cored wire
The total mass of the top slag was 2.4 tons calculated as 4% of the tapped amount. Before tapping, 1.2 tons of top slag are added into the bottom of the ladle, and 1.2 tons of top slag are continuously added into the iron flow in the tapping process. And (4) moving the ladle to a molten iron treatment station and feeding the dephosphorized cored wire.
Blowing nitrogen gas at the bottom of the ladle and stirring to expose the liquid level of the molten iron to the diameter of 60-100 cm. Feeding 350m long dephosphorized core-spun yarn at a speed of 100m min -1 。
S4 dephosphorization and chromium protection performance of chromium-containing high-phosphorus molten iron
After treatment, the phosphorus content in the molten iron is reduced to 0.045%, the chromium content is reduced to 3.69%, and the chromium retention rate is 85.4%.
TABLE 1 Mass percents of components before and after treatment of the chromium-containing high-phosphorus molten iron in example 1
| Element(s) | C | Mn | Si | S | P | Cr | Ni |
| The amount before treatment% | 4.05 | 0.71 | 2.48 | 0.058 | 0.094 | 4.32 | 2.33 |
| The amount after treatment is% | 4.00 | 0.65 | 2.35 | 0.045 | 0.045 | 3.69 | 2.33 |
Example 2:
and (4) treating excessive phosphorus in molten steel in the nickel-containing stainless steel produced by AOD.
60 tons of AOD molten steel enters LF to find that phosphorus exceeds the standard, the components are shown in Table 2, the phosphorus content is 0.07 percent, and the chromium content is 16.3 percent.
The dual process method for removing phosphorus and protecting chromium comprises the following steps:
s1, determining the final content of phosphorus after dephosphorization of molten steel in the nickel-containing stainless steel
Clearly, the phosphorus content required from the standard to be 0.05% does not vary much, corresponding to the need to strip 0.2kg of phosphorus per ton of steel. Therefore, the dual dephosphorization process of top slag and dephosphorization core-spun yarn is adopted in LF, and the amount of top slag required by top slag dephosphorization is small.
S2, determining the component content selection and the adding amount of the top slag and the dephosphorized cored wire according to the final content of phosphorus after dephosphorizing the molten steel in the nickel-containing stainless steel
The top slag comprises the following components in percentage by mass: k 2 CO 3 10％、Na 2 CO 3 10％、CaCO 3 20％、CaF 2 20 percent and FeOx 40 percent, and the powder is prepared into powder with the powder granularity of 4mm and bagged, and each bag weighs 50 kg.
The dephosphorized cored wire comprises the following components in percentage by mass: li 2 CO 3 10％、K 2 CO 3 10％、Na 2 CO 3 10％、CaO 15％、CaF 2 25% of FeOx and 30% of FeOx, wherein the diameter of the dephosphorized cored wire is 14-16mm, the granularity of the powder is 0.9mm, and the thickness of the coated steel strip is 0.2-0.4 mm.
S3 adding mode of top slag and dephosphorized cored wire
The surface layer of the molten steel was covered with 200mm thick top slag. And (5) stirring by blowing argon strongly for 5 minutes, wherein the power for stirring molten iron is 80W per ton.
Feeding 300m long dephosphorized core-spun yarn at 120 m.min -1 。
S4 dephosphorization and chromium protection performance of molten steel in nickel-containing stainless steel
After treatment, the phosphorus content in the molten iron is reduced to 0.045%, the chromium content is reduced to 16.0%, and the chromium retention rate is 98.1%. And meets the standard requirements.
TABLE 2 Mass percents of components before and after treatment of the nickel-containing stainless steel in example 2
| Element(s) | C | Mn | Si | S | P | Cr | Ni |
| The standard requirement% | ＜0.06 | ＜1.00 | ＜1.00 | ＜0.015 | ≤0.05 | ＞16.0 | ＞1.0 |
| The amount before treatment% | 0.05 | 0.89 | 0.56 | 0.008 | 0.07 | 16.3 | 1.33 |
| The amount after treatment is% | 0.05 | 0.65 | 0.55 | 0.005 | 0.045 | 16.0 | 1.33 |
Example 3:
and (4) treating the excessive phosphorus in the molten steel in the high-end nickel-chromium alloy steel produced by AOD.
60 tons of AOD molten steel enters LF to find that phosphorus exceeds the standard, the components are shown in Table 3, the phosphorus content is 0.07 percent, and the chromium content is 2.10 percent.
The dual process method for removing phosphorus and protecting chromium comprises the following steps:
s1, determining the final content of phosphorus after dephosphorization of molten steel in high-end nickel-chromium alloy steel
High-end nickel-chromium alloy steel requires ultra-low phosphorus and sulfur content, wherein the phosphorus content is lower than 0.02%. Therefore, the dual dephosphorization process of the top slag and the dephosphorization core-spun yarn is adopted in the LF, the thickness of the top slag and the length of the dephosphorization core-spun yarn are higher, and the content of alkali metal compounds is also higher.
S2, determining the component content selection and the adding amount of the top slag and the dephosphorized cored wire according to the final content of phosphorus after molten steel dephosphorization in the high-end nickel-chromium alloy steel
The top slag comprises the following components in percentage by mass: k 2 CO 3 10％、Na 2 CO 3 10％、CaCO 3 20％、CaF 2 20 percent and FeOx 40 percent, and the powder is prepared into powder with the powder granularity of 4mm and bagged, and each bag weighs 50 kg.
The dephosphorized cored wire comprises the following components in percentage by mass: k 2 CO 3 20％、Na 2 CO 3 20％、CaO 10％、CaF 2 20 percent and 30 percent, the diameter of the dephosphorized cored wire is 14 to 16mm, the granularity of powder is 1.2mm, and the thickness of an outer-coated steel strip is 0.2 to 0.4 mm.
S3 adding mode of top slag and dephosphorized cored wire
The surface layer of the molten steel was covered with 300mm thick top slag. And (5) stirring by blowing argon strongly for 5 minutes, wherein the power for stirring molten iron is 150W per ton.
Feeding 350m long dephosphorized core-spun yarn at 120m min -1 。
S4 dephosphorization and chromium-protection performance of molten steel in high-end nickel-chromium alloy steel
After treatment, the phosphorus content in the molten iron is reduced to 0.015 percent, the chromium content is reduced to 1.99 percent, and the chromium retention rate is 94.8 percent.
Table 3 mass percentages of components before and after treatment of high-end nickel-chromium alloy steel in example 3
| Element(s) | C | Mn | Si | S | P | Cr | Ni |
| Amount before treatment% | 0.30 | 0.28 | 0.08 | 0.006 | 0.07 | 2.10 | 3.00 |
| The amount after treatment is% | 0.30 | 0.28 | 0.08 | 0.002 | 0.015 | 1.99 | 3.00 |
Example 4:
and refining the high-phosphorus stainless steel liquid by AOD.
The phosphorus content of the low-nickel iron blocks which are purchased in the market and smelted by the laterite-nickel ore is uncertain, and the phosphorus removal and chromium protection effects are required to be adjusted according to the phosphorus content when the stainless steel is smelted.
When the phosphorus content in the low-nickel iron block is higher than 0.06% and less than 0.1%, the total mass of the alkali metal compounds in the top slag accounts for 10% of the total mass of the slag, and the total mass of the alkali metal compounds in the dephosphorization cored wire accounts for 25% of the total mass of the slag. The surface layer of the molten steel is covered with 200mm thick top slag, and 300m long dephosphorization core-spun yarn is fed.
When the phosphorus content in the low-nickel iron block is higher than 0.1 percent, the total mass of the alkali metal compounds in the top slag accounts for 20 percent of the total mass of the slag, and the total mass of the alkali metal compounds in the dephosphorized cored wire accounts for 40 percent of the total mass of the slag. Covering the surface layer of the molten steel with top slag with the thickness of 300mm, and feeding the dephosphorized cored wire with the length of 350 m.
The specific operation of the phosphorus and chromium removal dual process is described in example 2.
In the scheme, the phosphorus and chromium removing and maintaining double process for smelting the chromium-containing high-phosphorus molten metal from the laterite-nickel ore overcomes the technical defects of waste of chromium resources and deterioration of performance of molten metal due to high phosphorus content in the laterite-nickel ore resource smelting process.
The invention utilizes the alkali metal compound to greatly reduce P at 1300-1500 DEG C 2 O 5 So that P is a free energy of generation 2 O 5 Is much lower than Cr 2 O 3 Free energy is generated, thereby realizing the selective oxidation of chromium and phosphorus and realizing the thermodynamic condition requirement of chromium-retaining dephosphorization.
The invention sends the dephosphorized cored wire into the molten metal, the cored wire has the best dephosphorizing thermodynamic condition and kinetic condition in the melting and floating process,can realize ideal preferential dephosphorization; alkali metal compound K in the core 2 CO 3 、Li 2 CO 3 、Na 2 CO 3 For reducing P in molten metal 2 O 5 Promote the preferential oxidation of phosphorus over chromium; CO evolution 2 Gas is generated to form bubbles, and the dephosphorized product is dragged to float upwards from the metal liquid phase to enter the top slag and is absorbed by the top slag.
The invention has the function of covering the surface of the molten metal with the top slag, firstly, the molten metal is absorbed with the upward-floating dephosphorization product, and secondly, the dephosphorization reaction is generated at the interface of the molten metal and the top slag.
The technical scheme provided by the invention has the beneficial effects of high comprehensive utilization value of the laterite-nickel ore, high quality of stainless steel and alloy steel, simple and convenient process operation, good rhythm matching property, multi-link dephosphorization, rich and non-toxic slag system resources, capability of reducing the phosphorus content to be below 0.05 percent and chromium retention rate of above 84 percent.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A phosphorus and chromium removing and maintaining double process for smelting chromium-containing high-phosphorus metal liquid from laterite-nickel ore is characterized by comprising the following steps of: the method is characterized in that the P is respectively added into and on the surface of the chromium-containing high-phosphorus metal liquid obtained by smelting the laterite-nickel ore 2 O 5 Is lower than Cr 2 O 3 Generating free energy additive to selectively oxidize chromium and phosphorus in the interior and on the surface of the chromium-containing high-phosphorus metal liquid obtained by smelting the laterite-nickel ore; wherein: the chromium is retained in the molten metal, and the phosphorus oxide formed in the molten metal is reacted by the additive to release CO 2 Forming bubbles, dragging and floating to the top slag, and directly remaining the phosphorus oxide generated on the surface layer of the molten metal in the top slag.
2. The dual process for removing phosphorus and retaining chromium of the metal liquid containing chromium and high phosphorus in the smelting of the nickel laterite ores according to the claim 1, is characterized in that the additives respectively added into and on the surface of the metal liquid containing chromium and high phosphorus in the smelting of the nickel laterite ores are dephosphorized cored wires and top slag respectively.
3. The dual process of removing phosphorus and protecting chromium of the metal liquid containing chromium and high phosphorus in the smelting of the lateritic nickel ores according to the claim 2, wherein the dephosphorizing cored wire comprises a wire core and an outer-coated steel strip; the core contains an alkali metal compound K 2 CO 3 、Li 2 CO 3 、Na 2 CO 3 At least one of the above-mentioned compounds, and other functional compounds CaO and CaF 2 、FeOx。
4. The dual process of removing phosphorus and retaining chromium of the chromium-containing high-phosphorus molten metal smelted from the lateritic nickel ore according to claim 2, characterized in that the component of the top slag comprises K 2 CO 3 、Li 2 CO 3 、Na 2 CO 3 At least one of them, and a compound CaCO having other functions 3 、CaF 2 、FeOx。
5. The dual process of removing phosphorus and retaining chromium of the chromium-containing high-phosphorus metal liquid from the smelting of the lateritic nickel ores according to the claim 3, wherein the mass of the alkali metal compound in the wire core accounts for 25 to 40 percent of the total mass, and the mass ratios of the compounds with other functions are as follows: CaO 10-15%, CaF 2 20-30% of FeOx, 30-40% of FeOx and the balance of inevitable impurities; strict control of water content<0.5％。
6. The dual process of removing phosphorus and retaining chromium of the chromium-containing high-phosphorus metal liquid from the smelting of the lateritic nickel ores according to the claim 4, characterized in that the mass of the alkali metal compounds in the top slag accounts for 10 to 20 percent of the total mass; the mass ratio of the compounds with other functions is as follows: ca 2 CO 3 15-25％、CaF 2 20-30 percent of FeOx, 30-40 percent of FeOx and the balance of inevitable impurities.
7. The dual process of removing phosphorus and retaining chromium of the chromium-containing high-phosphorus molten metal smelted from the lateritic nickel ore according to the claim 2, is characterized by comprising the following steps of: in the initial stage of smelting, the phosphorus content is higher, surface slag is removed, a layer of top slag with the thickness of 200-300mm is covered on the surface layer of the molten metal, and a core-spun yarn is fed into the molten metal by a wire feeding machine; wherein: the speed of feeding the core-spun yarn is determined by the depth of the molten metal and is 90-120 m.min -1 。
8. The dual process of removing phosphorus and retaining chromium of the chromium-containing high-phosphorus molten metal smelted from the lateritic nickel ore according to the claim 2, is characterized by comprising the following steps of: when AOD molten steel enters LF refining, phosphorus exceeds the standard or does not meet the requirement, a layer of top slag with the thickness of 200-300mm is covered on the surface layer of the molten metal, a cored wire is fed into the molten metal by a wire feeding machine, and the phosphorus content is detected until the phosphorus content reaches the standard.
9. The dual process of removing phosphorus and retaining chromium of the chromium-containing high-phosphorus molten metal smelted from the lateritic nickel ore according to the claim 2, is characterized by comprising the following steps of: during the smelting process of AOD or other stainless steel, in the middle period of dephosphorization blowing, or for better dephosphorization, replacing top slag with high content of alkali metal compound, and feeding dephosphorization core-spun yarn with higher content of alkali metal compound.
10. The dual process for removing phosphorus and maintaining chromium of the metal liquid containing chromium and high phosphorus in the smelting of the lateritic nickel ores according to the claim 3, wherein the wire cores are uniformly mixed in a powder form, and the particle size of the powder is 0.9-1.5 mm; the diameter of the dephosphorized cored wire is 14-16mm, and the thickness of the outer-coated steel strip is 0.2-0.4 mm.
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