A process and apparatus for smelting chromite

Abstract

The application discloses a method and equipment for smelting chromite, and the method comprises the following steps: adding raw materials containing chromite, a reducing agent and a slagging agent into a smelting equipment to perform high-temperature bath smelting, spraying oxygen-rich air and fuel into a bath to combust and supply heat to the bath, and obtaining a chromium-iron alloy, a molten slag and flue gas; and delivering an oxygen-containing gas to the top of the bath to combust with reducing gas in the flue gas and supply heat to the bath. In the method, the chromite powder or lump ore does not need to be pretreated and can be directly smelted in a furnace, so that the processes of fine grinding, balling, drying and pre-reduction are omitted, and the treatment process flow is short. The method does not use electric energy as an energy source, solves the problem that the smelting of chromite depends on electric energy only, and reduces the cost. The technology uses coal as the reducing agent, and solves the problem that the traditional technology uses coke which is expensive.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, specifically to a method and equipment for smelting chromite. Background Technology

[0002] Chromium is an important strategic metal resource, one of the 24 strategic mineral resources listed in the "National Mineral Resources Plan (2016-2020)". Globally, it is mainly distributed in South Africa, Zimbabwe, Kazakhstan, and other regions. my country's chromium resources are relatively scarce, with an import dependency rate exceeding 99%. Approximately 90% of chromium ore is used to produce ferrochrome alloys, about 5% is used in refractory materials, and about 5% is used as a raw material for chromium salts in military, coating, and other chemical industries.

[0003] Currently, the main process for smelting ferrochrome from chromite is the pre-reduction-electric furnace smelting process, which includes rotary kiln-electric furnace, vertical shaft furnace-electric furnace, and blast furnace smelting technologies. After beneficiation, chromite is mostly in powder form, requiring multiple processes such as fine grinding, pelletizing, drying, pre-reduction, and electric furnace smelting to obtain ferrochrome alloy. Each ton of ferrochrome requires more than 3000 kWh of electricity from the grid, making the smelting process heavily reliant on electricity. Coke is also required during electric furnace smelting.

[0004] Existing ferrochrome alloy smelting technologies suffer from long processes, large land footprints, and heavy reliance on electricity. This significantly impacts ferrochrome smelting site selection. my country's dependence on imported chromium is extremely high, and companies building smelters at overseas mines must also construct power plants, resulting in substantial fixed asset investments. Furthermore, electric arc furnace smelting has a relatively limited daily ore processing capacity per unit furnace area, ranging from 2 to 8 tons per day. Therefore, it is necessary to develop a ferrochrome ore smelting method and equipment that does not rely on electricity and coke, thus reducing investment costs. Summary of the Invention

[0005] To address the problems of high investment, high energy consumption, and high smelting costs resulting from the current reliance on electricity and coke in chromite smelting, this invention proposes a method and equipment for chromite smelting. The above objective can be achieved through the following technical solution:

[0006] A method for smelting chromite includes the following steps:

[0007] Raw materials containing chromite, reducing agent and slag-forming agent are added to smelting equipment for high-temperature molten pool smelting. Oxygen-enriched air and fuel are side-blown into the molten pool for combustion to heat the molten pool, resulting in ferrochrome alloy, slag and flue gas.

[0008] Oxygen-containing gas is transported above the molten pool and combusted with reducing gases in the flue gas to reheat the molten pool.

[0009] Optionally, the chromite is untreated powder or lump ore, which is directly added to the smelting equipment.

[0010] This invention allows for the direct feeding of powdered or lump ore into the furnace for smelting, eliminating the need for fine grinding, pelletizing, drying, and pre-reduction processes. Oxygen-enriched air and fuel are injected into the molten pool, creating intense agitation and resulting in high processing capacity and reaction efficiency. The energy source is the direct combustion of pulverized coal and other materials with oxygen-enriched air in the molten slag, eliminating the need for electricity and overcoming the drawback of relying solely on electricity in chromite smelting.

[0011] Optionally, the reducing agent is a carbon-based reducing agent;

[0012] Optionally, the carbon-based reducing agent is selected from at least one of anthracite, bituminous coal, lignite, coke, graphite, semi-coke, and waste carbon electrode;

[0013] Optionally, the carbon-based reducing agent is anthracite;

[0014] Optionally, the weight ratio of the reducing agent to chromite is 1-5:10.

[0015] This invention can use coal as a reducing agent, which solves the problem that existing technologies must use large quantities of expensive and highly polluting coke.

[0016] Optionally, the slag-forming agent is at least one of magnesite, quartz, dolomite, limestone, pebbles, magnesium oxide, quartz, and lime.

[0017] Preferably, in the high-temperature molten pool smelting, the slag type is controlled by a slag-forming agent to be MgO / Al2O3 = 0.5-1.5 and the ternary basicity of the slag is 0.5-2.

[0018] Optionally, the volume fraction of oxygen in the oxygen-enriched air is 30% to 99%;

[0019] Optionally, the fuel is selected from at least one of pulverized coal, natural gas, coal gas, coke powder, graphite powder, heavy oil, gasoline, coal gasification, hydrogen, granular coal, and graphite particles;

[0020] Optionally, during the high-temperature smelting process, the ratio of oxygen to fuel in the oxygen-enriched air can be adjusted to a molar ratio of carbon dioxide to carbon monoxide produced during combustion of 0 to 1:10. This ensures a strong reducing atmosphere in the slag, preventing the re-oxidation of reduced metallic iron and chromium. For example, if pulverized coal is used as fuel, the ratio of carbon atoms in the pulverized coal to oxygen atoms in the oxygen-enriched air should be adjusted to approximately 1:1, ensuring that the combustion fuel is mostly or entirely carbon monoxide, with virtually no carbon dioxide produced.

[0021] Optionally, the melting temperature is 1500℃-1850℃;

[0022] Optionally, the melting temperature is 1600℃-1780℃.

[0023] Optionally, the oxygen-containing gas is air or oxygen-enriched air;

[0024] Optionally, the oxygen content in the oxygen-containing gas is 21%-99%.

[0025] Optionally, during the smelting process, the negative pressure in the furnace of the smelting equipment is -5 to -200 Pa.

[0026] In existing technologies, positive pressure is generally used. In this invention, negative pressure of -5 to -200 Pa is used in the furnace. The furnace body and the feeding system do not need to be sealed, so there is no carbon monoxide leakage during the smelting process. The environment around the smelting furnace is good, and safety accidents are avoided.

[0027] The present invention also provides

[0028] A chromite smelting equipment, characterized in that it comprises:

[0029] The furnace body for melting raw materials;

[0030] The first spray gun is located at the bottom of the furnace body, with its nozzle submerged in the molten slag. It is used to side-blow oxygen-enriched air and fuel into the molten pool for combustion.

[0031] The second spray gun is located on the upper part of the furnace body or the top of the furnace and is used to transport oxygen-containing gas to the top of the molten pool to burn with the reducing gas in the flue gas.

[0032] The flue gas exhaust port is located at the top of the smelting furnace body and is used to discharge the flue gas inside the smelting furnace body.

[0033] The slag discharge port is located on the lower side wall of the smelting furnace.

[0034] Optionally, the chromite smelting equipment also includes a waste heat recovery device for recovering waste heat from the flue gas. The recovered waste heat can be used to generate electricity or for other purposes, reducing overall energy consumption by 10%-25% compared to existing technologies.

[0035] Optionally, the chromite smelting equipment also includes a raw material inlet, which is located at the top of the smelting furnace body and is used to add raw materials into the smelting furnace body;

[0036] Preferably, the number of the first spray guns is 2 to 100; the number of the second spray guns is 1 to 20.

[0037] The height of the first spray gun is 1 / 100-99 / 100 of the height of the molten slag layer. The nozzle of the spray gun is immersed in the molten slag, and the fuel and oxygen-enriched air are directly sprayed into the molten slag layer.

[0038] The reducing agent can be added to the molten pool in block or granular form (particle size > 1mm) through the charging port on the top of the furnace, or it can be finely ground into powder and directly sprayed into the slag layer through the first spray gun.

[0039] Chromite and slag-forming agent can be added through the charging port at the top of the furnace, or through the second spray gun arranged at the top of the furnace to be added to the surface of the molten pool or into the molten pool, or directly sprayed into the molten pool through the first spray gun.

[0040] Optionally, the slag-gold discharge port can be located on the side of the furnace body, slightly higher than the furnace bottom, allowing slag and gold to be discharged together. Alternatively, slag and alloy discharge ports can be provided separately, with the slag port located in the molten slag layer and the alloy discharge port located in the alloy layer. Discharge can be continuous using a siphon or intermittent.

[0041] The technical solution of this invention has the following advantages:

[0042] In this invention, ferrochrome powder or lump ore requires no pretreatment and can be directly fed into the furnace for smelting, eliminating the processes of fine grinding, pelletizing, drying, and pre-reduction, resulting in a shorter processing flow. The energy source is the direct combustion of pulverized coal and oxygen-enriched air in the molten slag, releasing heat and simultaneously creating vigorous stirring in the molten pool, leading to high thermal efficiency and smelting intensity. The strong reducing gases overflowing from the molten pool are burned to reheat the melt, improving fuel utilization. This method does not use electricity as an energy source, overcoming the drawback of relying solely on electricity in ferrochrome ore smelting and reducing costs. This technology uses coal as a reducing agent, overcoming the disadvantage of expensive coke used in traditional technologies. This invention's method for processing ferrochrome ore to smelt ferrochrome alloys achieves high smelting intensity, with a processing capacity 5-10 times that of traditional submerged arc furnaces; the overall energy consumption for processing ferrochrome ore is reduced by 10%-25% compared to existing technologies.

[0043] The device of this invention features a short process, low cost, low energy consumption, and environmental friendliness. It generates electricity from side-blown waste heat, requiring no external power source. Independent plant construction is not dependent on external social infrastructure, making it particularly suitable for areas with underdeveloped power system infrastructure. The process has low requirements for plant construction conditions and flexible site selection. It boasts low investment costs, a short process flow, low overall energy consumption, high efficiency, high smelting intensity, and environmental friendliness. The recovered waste heat can be used for power generation or other purposes, reducing overall energy consumption by 10%-25% compared to existing technologies. It can be widely applied to new ferrochrome alloy smelting enterprises or the upgrading and renovation of existing enterprises. Attached Figure Description

[0044] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0045] Figure 1 This is a flowchart of the invention;

[0046] Figure 2 This is a schematic diagram of the structure of the smelting equipment of the present invention. Detailed Implementation

[0047] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0048] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0049] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0050] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0051] This invention provides a method for smelting chromite, such as... Figure 1 As shown, it includes:

[0052] Raw material preparation and batching: Ferrochromite powder or lump ore, slagging agent, and reducing agent (added at the top charging port). The particle size of the material entering the furnace is <50mm, and the moisture content is <10%. The raw materials are added to the intensified smelting furnace via conveyor belt according to the batching scheme based on metallurgical calculations. The slagging agent is one or more of magnesite, quartz, dolomite, limestone, etc., controlling the slag type MgO / Al2O3 = 0.5–1.5 and the ternary basicity to 0.5–2. Materials are added through 1–20 charging ports located at the top of the furnace.

[0053] Oxygen-enriched air and fuel are side-blown into the molten pool for combustion to smelt the raw materials. At the same time, the materials are added into the furnace and directly enter the violently stirred molten pool, where melting, slag formation, reaction, and slag-metal separation are quickly completed. The molten slag and ferrochrome alloy separate, and the alloy settles to the bottom, forming a bottom alloy layer and an upper slag layer in the molten pool inside the furnace.

[0054] The smelting temperature of the molten pool is 1500℃~1850℃, with the preferred temperature range being 1600℃~1780℃. The reducing agent can be carbon-containing materials such as anthracite, bituminous coal, lignite, coke, graphite, semi-coke, and waste electrodes. The reducing agent can be added to the molten pool in block or granular form (particle size > 1mm) through the charging port at the top of the furnace, or it can be finely ground into powder or granules smaller than 5mm and directly side-blown into the molten pool through the first spray gun.

[0055] When oxygen is injected into the furnace and fuel is burned, to ensure a strong reducing atmosphere in the molten slag and prevent the reduced iron and chromium from re-oxidizing, the combustion should produce mostly or entirely carbon monoxide, with carbon dioxide production less than 10% of the carbon monoxide. For example, if pulverized coal is used as fuel, the ratio of carbon atoms in the pulverized coal to oxygen atoms in the oxygen-enriched air should be adjusted to approximately 1:1, so that the combustion produces mostly or entirely carbon monoxide, with virtually no carbon dioxide production.

[0056] A second spray gun is installed above the furnace top or side wall above the molten raw material to spray air or oxygen-enriched air (oxygen concentration 22%-99%) to burn the strong reducing gas overflowing from the molten pool, and to reheat the vigorously stirred molten pool. The reheating efficiency is 40%-80%. The reducing gas such as CO overflowing from the molten pool is burned, with a combustion ratio of 50%-100%.

[0057] The process involves injecting oxygen-enriched air and fuel. The oxygen concentration of the oxygen-enriched air is 50% to 99%, and the fuel can be pulverized coal, natural gas, coal gas, coke powder, graphite powder, heavy oil, gasoline, coal gasification, hydrogen, etc. The height of the first spray gun is 1 / 100 to 99 / 100 of the height of the molten slag layer, and the nozzle of the spray gun is immersed in the molten slag. The fuel and oxygen-enriched air are directly sprayed into the molten slag layer.

[0058] The negative pressure in the furnace chamber of the side-blown furnace is -5 to -200 Pa. The negative pressure is adjusted according to the furnace structure. If the negative pressure is too low, the flue gas will easily leak from the charging port. If the negative pressure is too high, the secondary combustion will have a poor effect on the heat replenishment of the molten pool, and the temperature of the flue gas exiting the furnace will be high.

[0059] After combustion and reheating, the flue gas exiting the furnace first passes through an ascending flue, where forced air is blown in to reduce the temperature of the flue gas and dust to 1000℃~1500℃. The cooled flue gas and dust then enter a waste heat recovery device to recover waste heat; the steam is used for power generation or other purposes, and dust is collected by bag filters. The temperature of the flue gas and dust exiting the waste heat recovery system drops to 350℃, then passes through a surface cooling flue to below 200℃. Finally, the dust is collected by bag filters and returned to the system. The treated flue gas meets emission standards.

[0060] The ferrochrome smelting method and apparatus involved in this case involve smelting ferrochrome ore in an intensified smelting furnace, with iron and chromium recovery rates exceeding 98% and 95%, respectively. The products are ferrochrome alloy, smelting tailings, flue gas, and dust. The dust is collected and returned to the system for re-entry into the furnace for smelting.

[0061] like Figure 2 The chromite smelting equipment shown includes:

[0062] Furnace body 1, used for melting raw materials;

[0063] The first spray gun 2 is located at the bottom of the smelting furnace body and is immersed in the molten slag. It is used to side-blow oxygen-enriched air and fuel into the molten pool for combustion. The number of first spray guns is set from 2 to 100.

[0064] The second spray gun 3 is located on the upper part of the furnace body of the first spray gun, and is used to transport oxygen-containing gas to the top of the molten pool to burn with the reducing gas in the flue gas; specifically, 1 to 20 second spray guns can be set on the furnace top or the slag layer on the side of the furnace body above the molten pool to spray air or oxygen-enriched air.

[0065] Flue gas outlet 5 is located at the top of the smelting furnace body to discharge the flue gas inside the furnace. The outlet is situated at one end along the length of the furnace body, with the flue gas and dust temperature at the outlet being 1600℃-1800℃. After exiting the furnace, the flue gas first passes through an ascending flue, where air is forcibly introduced. Within the ascending flue or secondary combustion chamber, all unburned CO is completely combusted and cooled to 1000℃-1500℃. The cooled flue gas and dust then enter a waste heat recovery device to recover waste heat. The steam is used for power generation or heating, and dust is collected by bag filters. The temperature of the flue gas and dust exiting the waste heat recovery system drops to 350℃. After surface cooling, the dust is collected by bag filters and returned to the system. The treated flue gas meets emission standards.

[0066] Slag and alloy discharge port 4 is located on the lower side wall of the smelting furnace. Slag and alloy are discharged together and separated in the ladle. Alternatively, two discharge ports can be set at the bottom and middle to discharge the alloy and slag respectively. During smelting, materials are continuously added, while slag and alloy are discharged intermittently or continuously using a siphon method. If only one discharge port is set, it should be located at the end furthest from the feed port; if two discharge ports are set, the slag discharge port should be located at the end furthest from the feed port.

[0067] Raw material inlet, located at the top of the smelting furnace body, is used to add raw materials into the smelting furnace body;

[0068] The side-blown furnace body is rectangular. The first spray gun is arranged on both sides along the length direction. The second spray gun can be arranged on both sides along the length direction if it is set on the side wall, or it can be arranged on the top of the furnace.

[0069] A copper cooling water jacket is installed on the side of the smelting furnace body, lined with refractory bricks. Alternatively, a cooling water jacket can be used for slag hanging.

[0070] The first spray gun can be a single-channel spray gun, a dual-channel spray gun, or a multi-channel spray gun; the second spray gun can be a single-channel spray gun or a dual-channel spray gun.

[0071] The smelting equipment of the present invention can also be combined according to the process production needs, such as a pre-reduction furnace (rotary kiln, vertical furnace) + intensified molten pool smelting furnace, a pre-reduction furnace (rotary kiln, vertical furnace) + intensified molten pool smelting furnace + electric arc furnace (DC furnace, AC furnace), a side-blown melting furnace + a side-blown reduction furnace, a side-blown melting furnace + a side-blown reduction furnace + electric arc furnace (DC furnace, AC furnace), etc. The process layout is flexible, and ladle or hot slag chute conveying can be used. The oxidation or reduction atmosphere inside the furnace can be controlled according to the requirements of different sections.

[0072] In addition, chromite and slag-forming agents can be added through the charging port on the top of the furnace, or through the second spray gun arranged on the top of the furnace to be added to the surface of the molten pool or into the molten pool, or directly sprayed into the molten pool through the first spray gun.

[0073] The composition of the chromite powder processed in each embodiment is shown in Table 1.

[0074] Table 1 Composition of chromite powder

[0075]

[0076] Example 1

[0077] Using chromite ore as shown in Table 1, chromite powder with 8% moisture content, anthracite with a particle size <30mm, silica, and magnesite are added to the furnace via a conveyor belt through the top charging port. The smelting temperature in the molten pool is 1700℃. Pulverized coal is used as fuel, and the oxygen-enriched air concentration is 80%. The second lance is evenly positioned at the top of the furnace, injecting oxygen-enriched air at a concentration of 30%. The MgO / Al2O3 ratio is 1, the ternary basicity is 1.2, and air is used as the carrier gas to inject the fuel coal powder into the slag through the first lance. Each ton of ferrochrome alloy consumes 1385.8 Nm³ of 80% oxygen-enriched air. 3 The furnace uses 0.488 tons of anthracite and 1.1 tons of pulverized coal. The iron and chromium content in the smelting slag is reduced to 1.5% and 3%, respectively, resulting in a ferrochrome alloy with a chromium content of 50.05%. The flue gas overflowing from the molten pool is burned in the furnace by a second spray gun, providing 65% reheating efficiency to the molten pool. The flue gas and dust exit temperature is 1650℃, which is reduced to 1300℃ by forced draft through the flue. The flue gas then enters a waste heat recovery device to recover waste heat. The steam is used for power generation or heating, and the ash collected by the bag filter is returned to the system. The produced ferrochrome alloy and tailings are discharged through the bottom discharge port and clarified and separated in the ladle.

[0078] The plant processes 60,000 tons of wet-based chromite ore annually, with a processing capacity of 21 tons per day per unit furnace area. It consumes 13,438 tons of coal for reduction and 30,175 tons of pulverized coal for fuel annually, producing 27,432 tons of ferrochrome alloy. The grade of the ferrochrome alloy is consistent with that of traditional technology. Waste heat is comprehensively recovered for power generation or steam generation. In addition to meeting the plant's own needs, the rest is sold externally. The overall energy consumption is reduced by 18.1% compared with traditional technology.

[0079] Example 2

[0080] Using chromite ore as shown in Table 1, chromite powder with 8% moisture content, anthracite with a particle size <30mm, silica, and magnesite are added to the furnace via a conveyor belt through the top charging port. The smelting temperature in the molten pool is 1730℃. Pulverized coal is used as fuel, and the oxygen-enriched air concentration is 95%. The second lance is evenly positioned at the top of the furnace, injecting oxygen-enriched air at a concentration of 30%. The MgO / Al2O3 ratio is 1, and the ternary basicity is 1.2. Air is used as the carrier gas to inject fuel coal powder into the molten slag through the first lance. Each ton of ferrochrome alloy consumes 1106.8 Nm³ of 95% oxygen-enriched air. 3 The furnace used 0.49 tons of anthracite and 1.03 tons of pulverized coal. The iron and chromium content in the smelting slag was reduced to 1.3% and 2.5% respectively, resulting in a ferrochrome alloy with a chromium content of 50.30%. The flue gas overflowing the molten pool was burned in the furnace by a second spray gun, providing 65% reheating efficiency to the molten pool. The flue gas and dust exit temperature was 1650℃, which was reduced to 1300℃ by forced draft through the flue. The flue gas then entered a waste heat recovery device to recover waste heat. The steam was used for power generation or heating, and the ash collected by the bag filter was returned to the system. The produced ferrochrome alloy and tailings were discharged through the bottom discharge port and clarified and separated in the ladle.

[0081] The plant processes 60,000 tons of wet-based chromite ore annually, with a processing capacity of 25 tons per day per unit furnace area. It consumes 13,608.52 tons of coal for reduction and 28,801.7 tons of pulverized coal for fuel annually, producing 27,753 tons of ferrochrome alloy. The grade of the ferrochrome alloy is slightly higher than that of traditional technology. Waste heat is comprehensively recovered to generate electricity or steam. In addition to meeting the plant's own needs, the rest is sold externally. The overall energy consumption is reduced by 19.2% compared to traditional technology, and no external power is required.

[0082] Example 3

[0083] Using chromite ore as shown in Table 1, chromite powder with 8% moisture content, silica and magnesite with a particle size <30mm are added to the furnace via a conveyor belt through the top charging port. Anthracite is injected into the molten pool through a lance. The smelting temperature in the molten pool is 1650℃. Pulverized coal is used as fuel, and the oxygen-enriched air concentration is 95%. A second lance is evenly distributed at the top of the furnace, injecting oxygen-enriched air at a concentration of 30%. The MgO / Al2O3 ratio is 1, and the ternary basicity is 1.2. Air is used as the carrier gas to inject fuel coal powder into the molten slag through the first lance. Each ton of ferrochrome alloy consumes 1665.6 Nm³ of 70% oxygen-enriched air. 3The furnace used 0.489 tons of anthracite and 1.16 tons of pulverized coal. The iron and chromium content in the smelting slag was reduced to 2% and 3.5% respectively, resulting in a ferrochrome alloy with a chromium content of 50.09%. The flue gas overflowing the molten pool was burned in the furnace by a second spray gun, providing 65% reheating efficiency to the molten pool. The flue gas and dust exit temperature was 1650℃, which was reduced to 1300℃ by forced draft through the flue. The flue gas then entered a waste heat recovery device to recover waste heat. The steam was used for power generation or heating, and the ash collected by the bag filter was returned to the system. The produced ferrochrome alloy and tailings were discharged through the bottom discharge port and clarified and separated in the ladle.

[0084] The plant processes 60,000 tons of wet-based chromite ore annually, with a processing capacity of 18 tons per day per unit furnace area. It consumes 13,258.38 tons of coal for reduction and 31,456.05 tons of pulverized coal for fuel annually, producing 27,063 tons of ferrochrome alloy. The grade of the ferrochrome alloy is slightly higher than that of traditional technology. Waste heat is comprehensively recovered for power generation or steam generation. In addition to meeting the plant's own needs, the rest is sold externally. The overall energy consumption is reduced by 15.6% compared to traditional technology.

[0085] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for smelting chromite, characterized in that, Includes the following steps: Raw materials containing chromite, reducing agent and slag-forming agent are added to smelting equipment for high-temperature molten pool smelting. Oxygen-enriched air and fuel are side-blown into the molten pool for combustion to heat the molten pool, resulting in ferrochrome alloy, slag and flue gas. During the high-temperature molten pool smelting process, the ratio of oxygen to fuel in the oxygen-enriched air is adjusted so that the molar ratio of carbon dioxide to carbon monoxide generated by combustion is 0~1:10; The weight ratio of the reducing agent to chromite is 4.88~4.9:10; Oxygen-containing gas is transported above the molten pool and burned with reducing gases in the flue gas to reheat the molten pool; The chromite is untreated powder or lump ore, which is directly added to the smelting equipment, eliminating the need for fine grinding, pelletizing, drying and pre-reduction processes; The smelting method does not use electricity as an energy source.

2. The chromite smelting method according to claim 1, characterized in that, The reducing agent is at least one of anthracite, bituminous coal, lignite, coke, graphite, semi-coke, and waste carbon electrode.

3. The chromite smelting method according to claim 2, characterized in that, The reducing agent is anthracite.

4. The chromite smelting method according to claim 1, characterized in that, The slag-forming agent is at least one of magnesite, quartz, dolomite, limestone, pebbles, magnesium oxide, quartz, and lime.

5. The chromite smelting method according to claim 4, characterized in that, In the high-temperature molten pool smelting process, the slag type is controlled by slag-forming agent to be MgO / Al2O3=0.5~1.5, and the ternary basicity of the slag is 0.5~2.

6. The chromite smelting method according to claim 1, characterized in that, The oxygen volume fraction in the oxygen-enriched air is 30% to 99%.

7. The chromite smelting method according to claim 6, characterized in that, The fuel is selected from at least one of pulverized coal, natural gas, coal gas, coke powder, graphite powder, heavy oil, gasoline, coal gasification, and hydrogen.

8. The chromite smelting method according to claim 1, characterized in that, The temperature of the high-temperature molten pool is 1500℃-1850℃.

9. The chromite smelting method according to claim 8, characterized in that, The high-temperature molten pool melting temperature is 1600℃-1780℃.

10. The chromite smelting method according to claim 1, characterized in that, The oxygen-containing gas is air or oxygen-enriched air.

11. The chromite smelting method according to claim 10, characterized in that, The oxygen content in the oxygen-containing gas is 21%-99%.

12. The chromite smelting method according to claim 1, characterized in that, During the high-temperature molten pool smelting process, the negative pressure in the furnace of the smelting equipment is -5 to -200 Pa.

13. The chromite smelting method according to any one of claims 1 to 12, characterized in that, The implementation is carried out using chromite smelting equipment, which includes: The furnace body for melting raw materials; The first spray gun is located at the bottom of the furnace body, with its nozzle submerged in the molten slag. It is used to side-blow oxygen-enriched air and fuel into the molten pool for combustion. The second spray gun is located on the upper part of the furnace body or the top of the furnace and is used to transport oxygen-containing gas to the top of the molten pool to burn with the reducing gas in the flue gas. The flue gas exhaust port is located at the top of the smelting furnace body and is used to discharge the flue gas inside the smelting furnace body. The slag discharge port is located on the lower side wall of the smelting furnace.

14. The chromite smelting method according to claim 13, characterized in that, The chromite smelting equipment also includes a waste heat recovery device for recovering waste heat from the flue gas.

15. The chromite smelting method according to claim 13, characterized in that, The chromite smelting equipment also includes a raw material inlet, which is located at the top of the smelting furnace body and is used to add raw materials into the smelting furnace body.

16. The chromite smelting method according to claim 15, characterized in that, The number of the first spray gun is 2 to 100; the number of the second spray gun is 1 to 20.

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