A method for low-temperature reduction of antimony by in-situ pyrolysis of biomass and a special smelting furnace thereof

Abstract

The application belongs to the technical field of non-ferrous pyrometallurgy, and particularly discloses a method for low-temperature reduction of antimony by in-situ pyrolysis of biomass and a special smelting furnace therefor. The special smelting furnace comprises a furnace body, a reduction zone and a preliminary refining zone arranged side by side in the furnace body, and a partition wall is arranged between the reduction zone and the preliminary refining zone. A passage is arranged below the partition wall for the liquid metal in the reduction zone to flow into the preliminary refining zone. A top blowing system is arranged at the top of the furnace body. The top blowing system comprises at least one sleeve-type lance arranged at the top of the reduction zone. The sleeve-type lance has a concentric sleeve structure, comprising a central passage and an outer annular passage surrounding the central passage. The central passage is used to deliver gaseous fuel and combustion-supporting gas into the furnace body, and the outer annular passage is used to deliver powdered biomass fuel into the furnace body. The application has the advantages of low-temperature reduction of antimony, significant energy saving, green environmental protection, low carbon emission, high metal recovery rate, continuous and efficient production, long service life of equipment and high safety, etc.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal pyrometallurgy technology, specifically relating to a method for low-temperature reduction of antimony using in-situ biomass pyrolysis and its dedicated smelting furnace. Background Technology

[0002] Antimony (Sb) possesses irreplaceable application value in flame retardants, lead-acid battery alloys, semiconductor materials, and military applications due to its unique physicochemical properties. Currently, the global industrial production of antimony metal mainly relies on pyrometallurgical technology, among which the "volatile roasting-reduction smelting" process is the most mature and widely used mainstream solution for processing antimony sulfide concentrate (mainly composed of Sb₂S₃). The core steps of this process include: first, oxidizing antimony sulfide to easily volatile antimony trioxide (Sb₂O₃) in a high-temperature roasting furnace, and collecting the antimony oxide powder through a dust collection system; then, feeding the collected antimony oxide powder into a reverberatory furnace or blast furnace, using solid carbonaceous materials such as coke or anthracite as reducing agents, and carrying out carbothermic reduction under high-temperature conditions (usually maintained at >1100℃), ultimately producing crude antimony metal.

[0003] However, in-depth research and long-term industrial practice have shown that the aforementioned traditional pyrometallurgical reduction process has a series of inherent defects and challenges that are difficult to overcome, which seriously restrict the sustainable development and competitiveness enhancement of the industry:

[0004] High energy consumption and poor economic efficiency: Carbothermic reduction reaction ( The furnace itself has limited thermodynamic driving force and unfavorable reaction kinetics. To achieve acceptable reduction rates and metal recovery rates, extremely high furnace temperatures (far exceeding theoretical reaction temperatures) must be maintained in actual operation. This not only leads to huge fossil fuel consumption and low thermal efficiency (a large amount of heat is lost through flue gas and furnace body heat dissipation), but also causes severe corrosion of refractory furnace lining materials in the high-temperature environment, significantly shortening equipment lifespan, resulting in high equipment maintenance costs and persistently high overall production costs.

[0005] Environmental pollution is a significant concern: this process heavily relies on fossil fuels such as coal and coke as its primary energy source and reducing agent, inevitably generating large amounts of carbon dioxide (CO2), a greenhouse gas, resulting in a substantial carbon footprint. Even more serious is the release of sulfur dioxide (SO2) as part of the pre-treatment roasting process for antimony sulfide concentrate. Without efficient desulfurization, SO2 is a major source of acid rain. As global environmental regulations become increasingly stringent (such as carbon taxes and stricter emission standards), traditional processes face mounting environmental compliance pressures and escalating environmental remediation costs.

[0006] Insufficient process efficiency and stability: Existing reduction smelting processes mostly adopt intermittent or semi-continuous operation modes, resulting in discontinuous production processes and low levels of automation. This not only leads to low production efficiency and high labor intensity for workers, but also causes significant fluctuations in the furnace temperature field and atmosphere, making it difficult to precisely control the operating conditions. The consequences are incomplete reduction reactions or over-reduction, resulting in large fluctuations in the quality of crude antimony products (such as grade and impurity content), increasing the burden on subsequent refining, and making it difficult to meet the stable purity requirements of high-end applications.

[0007] In response to the above problems, the industry has attempted to explore alternative technological paths, but all of them have obvious limitations:

[0008] Hydrometallurgical route: Involves complex leaching, purification, electrowinning or precipitation processes, which are lengthy. Not only does it consume a large amount of reagents, but it also generates a large amount of complex and difficult-to-treat acidic wastewater and heavy metal-containing waste residue, which brings the risk of secondary pollution. Its environmental advantages are often offset by the difficulty of end-of-pipe treatment, and its economic efficiency is often not as good as mature pyrometallurgical methods.

[0009] Direct electrolysis and other technologies: Although they are cutting-edge research directions, their technological maturity is insufficient. In particular, for the large-scale processing of antimony oxide powder (i.e., volatile roasting products), a mainstream intermediate form, a mature electrolysis solution that is industrially competitive in terms of investment cost, operating energy consumption, product purity, and economies of scale has not yet been developed.

[0010] In recent years, hydrogen metallurgy has been regarded as a revolutionary direction for solving the high pollution and high energy consumption problems of the metallurgical industry due to its significant advantage that the only reaction product is water (H2O) and it can theoretically achieve "zero carbon" emissions. It uses hydrogen (H2) to replace carbonaceous reducing agents to reduce metal oxides... Hydrogen metallurgy technology has the potential for clean reaction and high reduction efficiency (with some systems allowing for lower reaction temperatures). However, the successful application of hydrogen metallurgy to antimony smelting still faces a key bottleneck: the high cost of "green hydrogen" preparation and storage. Currently, the price of "green hydrogen" produced through renewable energy electrolysis of water is far higher than that of hydrogen produced from fossil fuels. Directly purchasing high-purity hydrogen for large-scale antimony reduction production is not economically feasible under current market conditions, significantly hindering the industrialization of this technology. Therefore, developing an innovative smelting method that effectively utilizes hydrogen or hydrogen-based reducing media, while also being economical and suitable for the efficient reduction of antimony oxide, has become a critical technical challenge that urgently needs to be addressed in this field. Summary of the Invention

[0011] In view of the above-mentioned problems, this invention provides a method for low-temperature reduction of antimony using in-situ biomass pyrolysis and a dedicated smelting furnace thereof. The dedicated smelting furnace of this invention generates hydrogen in-situ within the furnace using a sleeve-type spray gun, and achieves low-temperature, stable antimony reduction in combination with partition walls. This invention has advantages such as low-temperature reduction, significant energy saving, green environmental protection, low carbon emissions, high metal recovery rate, continuous and efficient production, long equipment life, and high safety.

[0012] To solve the above-mentioned technical problems, the present invention provides a special smelting furnace for low-temperature reduction of antimony using in-situ pyrolysis of biomass, including a furnace body;

[0013] The furnace body is provided with a reduction zone and a preliminary refining zone arranged side by side;

[0014] The reduction zone and the preliminary refining zone are separated by a partition wall, and a channel is provided below the partition wall for the liquid metal in the reduction zone to flow into the preliminary refining zone;

[0015] The furnace body is equipped with a top injection system at the top; the top injection system includes at least one sleeve-type spray gun disposed at the top of the reduction zone; the sleeve-type spray gun has a concentric sleeve structure, including a central channel and an outer annular channel surrounding the central channel; the central channel transports gaseous fuel and combustion-supporting gas into the furnace body, and the outer annular channel transports powdered biomass fuel into the furnace body.

[0016] Preferably, the gaseous fuel includes at least one of producer gas, natural gas, coke oven gas, biogas, and syngas; the combustion-supporting gas is oxygen-enriched air; and the biomass fuel includes at least one of sawdust and straw.

[0017] Preferably, the central channel is provided with a first pipe for conveying gaseous fuel and a second pipe for conveying combustion-supporting gas.

[0018] Preferably, the furnace body is provided with a feeding port at one end near the reduction zone and a siphon antimony discharge port at one end near the preliminary refining zone.

[0019] Preferably, the bottom of the furnace body is an inclined bottom surface, which is inclined towards the preliminary refining area; the top of the furnace body is also provided with a flue.

[0020] Preferably, the inner wall of the furnace body is provided with a refractory lining layer; the refractory lining layer includes at least one of an acidic refractory material layer, a neutral refractory material layer, and an alkaline refractory material layer; the acidic refractory material layer includes silica refractory bricks; the neutral refractory material layer includes at least one of high-alumina bricks and chrome corundum bricks; the alkaline refractory material layer includes at least one of magnesia-carbon bricks and magnesia-chrome bricks.

[0021] Preferably, the method for low-temperature reduction of antimony using in-situ biomass pyrolysis includes the following steps:

[0022] S1. Add a mixed charge to the reduction zone of the smelting furnace; wherein the mixed charge includes antimony oxide, solid carbonaceous reducing agent and slag-forming flux;

[0023] S2. Gaseous fuel and combustion-supporting gas are introduced into the furnace through the central channel of the sleeve-type spray gun for contact and combustion, and then the powdered biomass fuel is driven in situ through the outer annular channel of the sleeve-type spray gun to pyrolyze, generating a strong reducing atmosphere; wherein, the strong reducing atmosphere includes H2, CO and CH4;

[0024] S3. Under the synergistic effect of the strong reducing atmosphere and the solid carbonaceous reducing agent, the antimony oxide in the reduction zone of the smelting furnace is reduced at low temperature to obtain liquid metallic antimony and slag; wherein, the temperature of the low-temperature reduction is 850-1000℃;

[0025] S4. The liquid antimony metal enters the preliminary refining zone through the channel.

[0026] Based on the same inventive concept, this invention also provides a method for low-temperature reduction of antimony using in-situ pyrolysis of biomass based on any of the above-described dedicated smelting furnaces, comprising the following steps:

[0027] S1. Add a mixed charge to the reduction zone of the smelting furnace; wherein the mixed charge includes antimony oxide, solid carbonaceous reducing agent and slag-forming flux;

[0028] S2. Gaseous fuel and combustion-supporting gas are introduced into the furnace through the central channel of the sleeve-type spray gun for contact and combustion, and then the powdered biomass fuel is driven in situ through the outer annular channel of the sleeve-type spray gun to pyrolyze, generating a strong reducing atmosphere; wherein, the strong reducing atmosphere includes H2, CO and CH4;

[0029] S3. Under the synergistic effect of the strong reducing atmosphere and the solid carbonaceous reducing agent, the antimony oxide in the reduction zone of the smelting furnace is reduced at low temperature to obtain liquid metallic antimony and slag; wherein, the temperature of the low-temperature reduction is 850-1000℃.

[0030] Preferably, the antimony oxide is in powder form; the solid carbonaceous reducing agent is anthracite; and the slag-forming flux includes at least one of Na2O and SiO2.

[0031] Preferably, in the reduction zone, the content of antimony oxide is 50-70 wt%, the content of slag-forming flux is 10-20 wt%, the content of powdered biomass fuel is less than or equal to 18 wt%, and the content of solid carbonaceous reducing agent is less than or equal to 9 wt%.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The sleeve-type spray gun in the special smelting furnace of the present invention is equivalent to an "in-situ micro pyrolysis reactor". It utilizes the gaseous fuel in the central channel to contact the combustion-supporting gas at the nozzle outlet, thereby burning and providing a high-temperature, oxygen-deficient environment for the powdered biomass fuel in the outer annular channel in an instant and in-situ, driving it to undergo rapid pyrolysis, thereby realizing pyrolysis to produce hydrogen.

[0034] (2) The partition wall inside the special smelting furnace of the present invention not only clearly divides the furnace body into a reduction zone and a preliminary refining zone, but also works with a sleeve-type spray gun to maintain the stability and high concentration of the strong reducing atmosphere (hydrogen-rich atmosphere) in the reduction zone, so that it is not disturbed by the downstream operation, thereby realizing true continuous production, that is, the strong reducing atmosphere (hydrogen-rich atmosphere) is continuously produced, the reduction reaction continues, and the molten metal produced in the reduction zone continuously flows into the preliminary refining zone (liquid antimony metal is below, and slag is above).

[0035] (3) The strong reducing atmosphere (hydrogen-rich atmosphere) of the present invention can suppress the volatilization of antimony, and the presence of the partition wall makes it difficult for the strong reducing atmosphere (hydrogen-rich atmosphere) to enter the preliminary refining zone, thereby stabilizing the temperature of the reduction zone at 850-1000℃ (hydrogen has good reduction kinetics, so the atmosphere inside the furnace is stable); at the same time, the presence of the partition wall allows the molten metal to flow smoothly into the refining zone for clarification, avoiding the metal entrainment into the slag caused by violent airflow agitation in the traditional process, thereby significantly reducing the antimony content in the slag.

[0036] In summary, this invention has advantages such as low-temperature reduction, significant energy saving, environmental friendliness, low carbon emissions, high metal recovery rate, continuous and efficient production, long equipment life, and high safety. Specifically:

[0037] Low-Temperature Reduction and Significant Energy Saving: This invention innovatively utilizes in-situ pyrolysis of biomass in a furnace to generate highly active gaseous reducing agents (H2, CO, CH4). Their excellent kinetic characteristics allow the reduction reaction to proceed efficiently at low temperatures of 850℃-1000℃, significantly reducing energy consumption compared to the traditional process in Comparative Example 1 (>1100℃). Simultaneously, dependence on fossil fuels (anthracite) is reduced from approximately 40% to below 9%, resulting in significant overall energy savings.

[0038] Green and environmentally friendly with low carbon emissions: This invention uses renewable biomass as the main reducing agent and part of the energy source to significantly replace fossil fuels and reduce CO2 emissions significantly from the source.

[0039] High metal recovery rate: By creating a strong reducing atmosphere (hydrogen-rich atmosphere) in the furnace, this invention can effectively suppress the volatilization loss of antimony at high temperatures, and the gas-solid synergistic reduction effect is more thorough. It is expected that the crude antimony recovery rate can be stabilized at over 85%, which is a significant improvement over traditional processes.

[0040] Continuous and efficient production: The special smelting furnace of this invention achieves continuous operation of feeding, reduction, refining and discharge through the structural design of "partition wall zoning + siphon discharge of antimony", which overcomes the drawbacks of traditional intermittent operation, and the production process is more stable and more efficient.

[0041] Long equipment life and high safety: The low-temperature operation of the antimony low-temperature reduction method of the present invention significantly reduces the erosion of the furnace lining by the high-temperature melt, which can greatly extend the service life of refractory materials. Attached Figure Description

[0042] Figure 1 This is a partial longitudinal cross-sectional structural schematic diagram of the front view of the special smelting furnace for low-temperature reduction of antimony using in-situ pyrolysis of biomass as described in Embodiment 1 of the present invention.

[0043] Figure 2 This is a partial longitudinal cross-sectional schematic diagram of the side view of the special smelting furnace for low-temperature reduction of antimony using in-situ pyrolysis of biomass as described in Embodiment 1 of the present invention.

[0044] Figure 3 This is a top view of the special smelting furnace for low-temperature reduction of antimony using in-situ pyrolysis of biomass as described in Embodiment 1 of the present invention.

[0045] Figure 4 This is a schematic diagram of the cross-sectional structure of the sleeve-type spray gun in the special melting furnace described in this invention.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1. Furnace body; 2. Reduction zone; 3. Preliminary refining zone; 4. Partition wall; 5. Passageway; 6. Sleeve-type spray gun; 7. Central passageway; 8. Outer annular passageway; 9. Feed port; 10. Siphon antimony discharge port; 11. Inclined bottom surface; 12. Flue; 13. Refractory lining layer; 14. Slag discharge port. Detailed Implementation

[0048] To make the present invention easier to understand, specific embodiments are described below to further illustrate the invention. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical terms used below have the same meaning as understood by those skilled in the art; unless otherwise specified, the raw materials and reagents involved herein can be purchased commercially or obtained by known methods.

[0049] To develop an innovative smelting method for the efficient reduction of antimony oxide, which breaks away from the traditional "high-temperature-carbon-dependent" mode, effectively utilizes hydrogen or hydrogen-based reducing media, and is also economical, this invention provides a dedicated smelting furnace for low-temperature antimony reduction using in-situ biomass pyrolysis, comprising a furnace body;

[0050] The furnace body is provided with a reduction zone and a preliminary refining zone arranged side by side;

[0051] The reduction zone and the preliminary refining zone are separated by a partition wall, and a channel is provided below the partition wall for the liquid metal in the reduction zone to flow into the preliminary refining zone;

[0052] The furnace body is equipped with a top injection system at the top; the top injection system includes at least one sleeve-type spray gun disposed at the top of the reduction zone; the sleeve-type spray gun has a concentric sleeve structure, including a central channel and an outer annular channel surrounding the central channel; the central channel transports gaseous fuel and combustion-supporting gas into the furnace body, and the outer annular channel transports powdered biomass fuel into the furnace body.

[0053] It should be noted that the gaseous fuel and combustion-supporting gas are collected and burned at the outlet of the sleeve-type spray gun through the central channel (due to the high temperature inside the furnace (850-1000℃), combustion is possible), and the powdered biomass fuel at the outlet of the sleeve-type spray gun is pyrolyzed in situ. That is, the sleeve-type spray gun of the present invention is equivalent to a highly efficient "in-situ micro pyrolysis reactor".

[0054] In some specific embodiments of the present invention, the gaseous fuel includes at least one of producer gas, natural gas, coke oven gas, biogas, and syngas; the combustion-supporting gas is oxygen-enriched air; and the biomass fuel includes at least one of sawdust and straw.

[0055] In some specific embodiments of the present invention, the central channel is provided with a first pipe for conveying gaseous fuel and a second pipe for conveying combustion-supporting gas.

[0056] It should be noted that the first and second pipes are arranged in parallel or concentric sleeves. The purpose of this is to allow the gaseous fuel and combustion-supporting gas to converge at the end of the spray gun and burn and instantly pyrolyze the powdered biomass fuel at the outlet of the outer annular channel under the high temperature conditions inside the furnace.

[0057] In some specific embodiments of the present invention, a feeding port is provided at one end of the furnace body near the reduction zone, and a siphon antimony discharge port is provided at one end of the furnace body near the preliminary refining zone.

[0058] In some specific embodiments of the present invention, the bottom of the furnace body is an inclined bottom surface, which is inclined towards the preliminary refining zone; the top of the furnace body is also provided with a flue.

[0059] In some specific embodiments of the present invention, the inner wall of the furnace body is provided with a refractory lining layer; the refractory lining layer includes at least one of an acidic refractory material layer, a neutral refractory material layer, and an alkaline refractory material layer; the acidic refractory material layer includes silica refractory bricks; the neutral refractory material layer includes at least one of high-alumina bricks and chrome corundum bricks; the alkaline refractory material layer includes at least one of magnesia-carbon bricks and magnesia-chrome bricks.

[0060] In some specific embodiments of the present invention, the method for low-temperature reduction of antimony using in-situ biomass pyrolysis includes the following steps:

[0061] S1. Add a mixed charge to the reduction zone of the smelting furnace; wherein the mixed charge includes antimony oxide, solid carbonaceous reducing agent and slag-forming flux;

[0062] S2. Gaseous fuel and combustion-supporting gas are introduced into the furnace through the central channel of the sleeve-type spray gun for contact and combustion, and then the powdered biomass fuel is driven in situ through the outer annular channel of the sleeve-type spray gun to pyrolyze, generating a strong reducing atmosphere; wherein, the strong reducing atmosphere includes H2, CO and CH4;

[0063] S3. Under the synergistic effect of the strong reducing atmosphere and the solid carbonaceous reducing agent, the antimony oxide in the reduction zone of the smelting furnace is reduced at low temperature to obtain liquid metallic antimony and slag; wherein, the temperature of the low-temperature reduction is 850-1000℃;

[0064] S4. The liquid antimony metal enters the preliminary refining zone through the channel.

[0065] The present invention also provides a method for low-temperature reduction of antimony using in-situ pyrolysis of biomass based on any of the above-described dedicated smelting furnaces, comprising the following steps:

[0066] S1. Add a mixed charge to the reduction zone of the smelting furnace; wherein the mixed charge includes antimony oxide, solid carbonaceous reducing agent and slag-forming flux;

[0067] S2. Gaseous fuel and combustion-supporting gas are introduced into the furnace through the central channel of the sleeve-type spray gun for contact and combustion, and then the powdered biomass fuel is driven in situ through the outer annular channel of the sleeve-type spray gun to pyrolyze, generating a strong reducing atmosphere; wherein, the strong reducing atmosphere includes H2, CO and CH4;

[0068] S3. Under the synergistic effect of the strong reducing atmosphere and the solid carbonaceous reducing agent, the antimony oxide in the reduction zone of the smelting furnace is reduced at low temperature to obtain liquid metallic antimony and slag; wherein, the temperature of the low-temperature reduction is 850-1000℃.

[0069] In some specific embodiments of the present invention, the antimony oxide is in powder form; the solid carbonaceous reducing agent is anthracite; and the slag-forming flux includes at least one of Na2O and SiO2.

[0070] In some specific embodiments of the present invention, the content of antimony oxide in the reduction zone is 50-70 wt%, the content of slag-forming flux is 10-20 wt%, the content of powdered biomass fuel is less than or equal to 18 wt%, and the content of solid carbonaceous reducing agent is less than or equal to 9 wt%, by mass percentage.

[0071] The following detailed explanation is further illustrated with specific examples.

[0072] Example 1

[0073] A specialized smelting furnace for low-temperature antimony reduction using in-situ biomass pyrolysis, such as... Figure 1-4As shown, the furnace includes a furnace body 1; a reduction zone 2 and a preliminary refining zone 3 are arranged side by side within the furnace body 1; the reduction zone 2 and the preliminary refining zone 3 are separated by a partition wall 4, and a channel 5 is provided between the bottom of the partition wall 4 and the bottom of the furnace body for the liquid metal in the reduction zone to flow into the preliminary refining zone; a top blowing system is provided at the top of the furnace body 1; the top blowing system includes four sleeve-type spray guns 6 set at the top of the reduction zone; the sleeve-type spray guns 6 have a concentric sleeve structure, including a central channel 7 and an outer annular channel 8 surrounding the central channel 7; two independent pipes are arranged side by side within the central channel 7, the independent pipes including a first pipe and a second pipe; the central channel 7 transports gaseous fuel and combustion-supporting gas into the furnace body 1 (the first pipe transports gaseous fuel, and the second pipe transports combustion-supporting gas), and the outer annular channel 8 transports powdered biomass fuel into the furnace body 1. The furnace body 1 has a feeding port 9 at one end near the reduction zone 2 and a siphon antimony discharge port 10 at one end near the preliminary refining zone 3. The bottom of the furnace body 1 is an inclined bottom surface 11, which slopes towards the preliminary refining zone 3. A flue 12 is also provided at the top of the furnace body 1. The inner wall of the furnace body is provided with a refractory lining layer 13; the refractory lining layer is made of silica refractory bricks. The side walls of the reduction zone 2 and the preliminary refining zone 3 of the furnace body are also provided with slag discharge ports 14.

[0074] Example 2

[0075] A method for low-temperature reduction of antimony using in-situ biomass pyrolysis (based on the dedicated smelting furnace of Example 1) includes the following steps:

[0076] S1. Add mixed furnace charge to the reduction zone 2 of the smelting furnace; wherein, the mixed furnace charge includes antimony oxide, solid carbonaceous reducing agent and slag-forming flux (based on Na2O⋅2SiO2 slag system).

[0077] S2. Gaseous fuel and combustion-supporting gas are introduced into the furnace through the central channel 7 of the sleeve-type spray gun 6 for contact and combustion, and then the powdered biomass fuel is driven in situ through the outer annular channel 8 of the sleeve-type spray gun 6 to pyrolyze, generating a strong reducing atmosphere; wherein, the strong reducing atmosphere includes H2, CO and CH4.

[0078] S3. Under the synergistic effect of the strong reducing atmosphere and the solid carbonaceous reducing agent, the antimony oxide in the reduction zone of the smelting furnace is reduced at low temperature to obtain liquid metallic antimony (below) and slag (above); wherein the temperature of the low-temperature reduction is 850-1000℃.

[0079] S4. The liquid antimony metal (below) enters the preliminary refining zone through the channel 5; the slag (above) is discharged through the slag discharge port 14.

[0080] Example 3

[0081] A method for low-temperature reduction of antimony using in-situ biomass pyrolysis (based on the dedicated smelting furnace of Example 1) includes the following steps:

[0082] S1. Add a mixed charge to the reduction zone of the smelting furnace; wherein the mixed charge consists of 1000 kg antimony oxide powder (containing 78% Sb), 85 kg anthracite (fixed carbon content 85%), 120 kg soda ash (Na2CO3), and 260 kg quartz sand (SiO2).

[0083] S2. Start the top injection system to inject gaseous fuel (producer gas, injection rate 85 Nm³). 3 Antimony oxide (1 ton) and combustion-supporting gas (oxygen-enriched air, oxygen concentration 26%) enter the furnace through the central channel of the sleeve-type spray gun and come into contact and burn (the furnace top is maintained at a slight negative pressure of -50 Pa). Then, the powdered biomass fuel (150 kg of powdered pine wood chips) enters the furnace through the outer annular channel of the sleeve-type spray gun in situ and is pyrolyzed to generate a strong reducing atmosphere; wherein, the strong reducing atmosphere includes H2, CO and CH4;

[0084] S3. Under the synergistic effect of the strong reducing atmosphere and the solid carbonaceous reducing agent (85 kg anthracite (fixed carbon content 85%)), the antimony oxide in the reduction zone of the smelting furnace is reduced at low temperature (950°C) to obtain liquid metallic antimony and slag.

[0085] S4. The liquid antimony metal (below) enters the preliminary refining zone through the channel; the slag (above) is discharged through the slag discharge port.

[0086] After the aforementioned dedicated smelting furnace operated for 24 hours, it produced 678 kg of crude antimony. Sampling analysis showed that the crude antimony contained 99.0% antimony. The discharged slag contained 1.45% antimony. Calculations show that in this embodiment, the antimony recovery rate reached 86.1%, and the anthracite coal consumption was 85 kg / ton of antimony oxide.

[0087] Comparative Example 1

[0088] The process of antimony reduction using a traditional intermittent reverberatory furnace:

[0089] (1) Charge ratio: Process a batch of 1000 kg of antimony oxide powder (containing 78% Sb) from the same source as in Example 3, and add 400 kg of anthracite (fixed carbon content 85%), 150 kg of soda ash and 300 kg of quartz sand.

[0090] (2) Process parameter control: Add all the furnace charge to the reverberatory furnace and heat it to 1150℃ for reduction smelting.

[0091] (3) Experimental results: After one operating cycle (24h), 610kg of crude antimony was produced. After sampling and analysis, the antimony content of the crude antimony was 98.0%. The discharged slag contained 4.2% antimony. According to calculation, the antimony recovery rate in this comparative example was only 76.7%, and the consumption of anthracite coal was as high as 400 kg / ton of antimony oxide.

[0092] Results analysis:

[0093] As can be seen from the comparison between Example 3 and Comparative Example 1, Example 3 of the present invention demonstrates significant technical progress and comprehensive advantages. Specifically:

[0094] Regarding the melting temperature, Embodiment 3 of the present invention uses a low-temperature melting temperature of 950°C, which is 200°C lower than the 1150°C of Comparative Example 1 (conventional technology), significantly reducing energy consumption and alleviating the heat load on the equipment.

[0095] Regarding the reducing agent, in Example 3 of this invention, biomass and a small amount of anthracite (85 kg / t of material) can replace the pure anthracite (400 kg / t of material) system of Comparative Example 1 (traditional technology) while reducing the consumption of anthracite by 78.8%. This not only significantly reduces the cost of raw materials, but also achieves a green and low-carbon transformation due to the renewable characteristics of biomass.

[0096] In terms of resource utilization, the antimony recovery rate increased from 76.7% in Comparative Example 1 (traditional process) to 86.1% in Example 3 of the present invention, an increase of 9.4 percentage points, significantly improving resource utilization. The antimony content in the slag decreased from 4.2% in Comparative Example 1 (traditional process) to 1.45% in Example 3 of the present invention, effectively reducing metal loss.

[0097] In terms of production mode: the intermittent production of Comparative Example 1 (traditional process) is upgraded to the continuous production of Example 3 of the present invention, which improves production efficiency while ensuring product quality stability.

[0098] In summary, this invention, based on the synergistic innovation of a dedicated smelting furnace, low-temperature smelting, biomass reducing agent coupling, and continuous operation, simultaneously achieves multiple technical effects such as energy conservation and emission reduction, cost control, efficient resource utilization, and production mode optimization.

[0099] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for low temperature reduction of antimony using in-situ pyrolysis of biomass, characterized in that, Includes the following steps: S1. Add a mixed charge to the reduction zone of the smelting furnace; wherein the mixed charge includes antimony oxide, solid carbonaceous reducing agent and slag-forming flux; S2. Gaseous fuel and combustion-supporting gas are introduced into the furnace through the central channel of the sleeve-type spray gun for contact and combustion, and then the powdered biomass fuel is driven in situ through the outer annular channel of the sleeve-type spray gun to pyrolyze, generating a strong reducing atmosphere; wherein, the strong reducing atmosphere includes H2, CO and CH4; S3. Under the synergistic effect of the strong reducing atmosphere and the solid carbonaceous reducing agent, the antimony oxide in the reduction zone of the smelting furnace is reduced at low temperature to obtain liquid metallic antimony and slag; wherein, the temperature of the low-temperature reduction is 850-1000℃; The smelting furnace includes a furnace body; a reduction zone and a preliminary refining zone are arranged side by side inside the furnace body; a top blowing system is provided at the top of the furnace body; the top blowing system includes at least one sleeve-type spray gun disposed at the top of the reduction zone; the sleeve-type spray gun has a concentric sleeve structure, including a central channel and an outer annular channel surrounding the central channel; the central channel transports gaseous fuel and combustion-supporting gas into the furnace body, and the outer annular channel transports powdered biomass fuel into the furnace body.

2. The method for low-temperature reduction of antimony using in-situ biomass pyrolysis according to claim 1, characterized in that, The antimony oxide is in powder form; the solid carbonaceous reducing agent is anthracite; and the slag-forming flux includes at least one of Na2O and SiO2.

3. The method for low-temperature reduction of antimony using in-situ biomass pyrolysis according to claim 2, characterized in that, In the reduction zone, by mass percentage, the content of antimony oxide is 50-70 wt%, the content of slag-forming flux is 10-20 wt%, the content of powdered biomass fuel is less than or equal to 18 wt%, and the content of solid carbonaceous reducing agent is less than or equal to 9 wt%.

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