Process for extracting tin from blast furnace sludge and for sulfur fixation

Abstract

This invention relates to a method for antimony extraction and sulfur fixation using blast furnace gas sludge, belonging to the field of non-ferrous metallurgical smelting technology. The invention involves separately crushing, grinding, and sieving antimony-containing stibnite concentrate and blast furnace gas sludge; uniformly mixing the stibnite concentrate and blast furnace gas sludge and placing them in a ceramic crucible in the center of a microwave reactor cavity; blowing N2 into the microwave cavity to purge it; turning on the microwave source and heating the mixture of stibnite concentrate and blast furnace gas sludge to 650-900℃ at a rate of 10-30℃ / min, holding at this temperature for 40-120 minutes; after the holding period, turning off the microwave source and skimming off the scum from the crucible surface to obtain sulfur-fixed slag; pouring metallic antimony into a mold to cast ingots to obtain crude antimony. This invention utilizes the thermal reduction of stibnite concentrate by blast furnace gas sludge to extract antimony and simultaneously fix sulfur, solving the problem of low-concentration sulfur dioxide flue gas pollution during the pyrometallurgical smelting of stibnite concentrate, and providing a new approach for large-scale disposal of blast furnace gas sludge, achieving the goal of treating waste with waste.

Description

Technical Field

[0001] This invention relates to a method for antimony extraction and sulfur fixation using blast furnace gas mud, belonging to the field of non-ferrous metallurgical smelting technology. Background Technology

[0002] Publicly available technology CN 108004421A discloses a method for smelting stibnite in an oxygen-enriched molten pool. First, oxygen-enriched air is blown into the molten pool. Then, stibnite material is mixed with red mud, lime, and a reducing agent and fed into the oxygen-enriched molten pool for reduction smelting to obtain antimony oxide containing 86% antimony. Although this invention has strong raw material adaptability and low energy consumption, it is difficult to recover low-concentration sulfur dioxide for acid production. Publicly available technology CN CN101942575A discloses a continuous antimony production method for bottom-blown molten pool smelting of stibnite. Using stibnite, iron ore, gravel, and anthracite as raw materials, these are metered and added to a bottom-blown oxidation smelting furnace for melting and reaction, producing flue gas and melt. The melt enters an electrothermal forebed for sedimentation and separation, producing waste slag, antimony matte, and precious antimony. This method has complex processing steps and is difficult to process gold-containing materials. Luo Zhengli et al. mixed antimony concentrate with lime, granulated the mixture, and after natural drying, added it to a blast furnace along with coke and flux. The material underwent drying, decomposition, volatilization, oxidation, and slagging reactions within the furnace. Sb entered the flue gas as antimony oxide, which was then reduced, smelted, and refined to obtain metallic Sb. While the blast furnace volatilization smelting process offers strong raw material adaptability and high metal recovery, it also results in large flue gas volumes, high coke consumption, and high overall energy consumption.

[0003] To address the high energy consumption and severe environmental pollution caused by low-concentration sulfur dioxide in the pyrometallurgical process of antimony sulfide concentrate, Liu Xiaowen proposed a low-temperature sulfur fixation clean antimony smelting process using a stibnite Na2CO3-KCl molten salt system. Under optimal process conditions, the direct antimony recovery rate is 91.3%, the crude antimony grade is 92.4%, the slag sulfur fixation rate is 74%, the molten salt sulfur fixation rate is 21.7%, and the total sulfur fixation rate is 95.7%. Using iron oxide waste slag as a sulfur fixative, in the presence of Fe2O3 and Na2CO3, Sb2S3 can be rapidly converted into Sb2O3, which is then continuously reduced to metallic Sb, achieving an antimony recovery rate of over 92.6%. 97.3% of the sulfur is fixed and converted into sulfides such as iron sulfide and sulfates, reducing SO2 emissions by 97.3%. Although the above-mentioned sulfur fixation process by adding pure metal oxides can achieve antimony smelting and sulfur fixation, it is costly and economically inefficient.

[0004] Blast furnace gas sludge is a byproduct of blast furnace ironmaking and belongs to the category of bulk industrial solid waste. Approximately 20 kg of blast furnace gas sludge is generated for every ton of steel produced. Simultaneously, the gas sludge is used to capture and solidify antimony separated from stibnite concentrate, achieving simultaneous sulfur fixation and solving the problem of low-concentration sulfur dioxide flue gas pollution during the pyrometallurgical smelting of stibnite concentrate, thus achieving the goal of treating waste with waste. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention proposes a method for antimony extraction and sulfur fixation using blast furnace gas sludge, the specific steps of which are as follows:

[0006] (1) The antimony concentrate and blast furnace gas mud are dried, crushed, ground and sieved to obtain antimony concentrate powder and blast furnace gas mud powder, respectively, for later use.

[0007] (2) Mix the antimony concentrate powder and blast furnace gas mud powder obtained in step (1) in a mass ratio of 1:3 to 1:8 and then put them into a ceramic crucible and place it in the center of the microwave reactor cavity.

[0008] (3) Turn on the atmosphere control system and blow N2 into the microwave cavity to purge the cavity.

[0009] (4) Turn on the microwave source to feed microwave energy into the microwave cavity, and heat up and keep the mixture of antimony concentrate powder and blast furnace gas mud powder.

[0010] (5) After the heat preservation is completed, turn off the microwave source, remove the scum on the surface of the crucible, and obtain solid sulfur slag; the remaining liquid in the crucible is metallic antimony liquid, pour the metallic antimony liquid into the mold to cast ingot to obtain metallic crude antimony, the density of metallic antimony is greater than that of slag, and the two naturally settle and separate.

[0011] Preferably, the drying temperature in step (1) is 80°C, the drying time is 12 hours, and the product is passed through an 80-mesh sieve after grinding.

[0012] Preferably, the ceramic crucible in step (2) is made of SiO2-MgO-Al2O3 material, with a dielectric constant of less than 3 and a coefficient of thermal expansion of 2.5 × 10⁻⁶ at 20-1000℃. -6 / ℃.

[0013] Preferably, in step (2), the ceramic crucible is wrapped with a 3cm thick aluminum silicate insulation material, and the dielectric constant of the aluminum silicate insulation material is less than 2.

[0014] Preferably, in step (3), N2 is blown into the microwave cavity at a flow rate of 0.5 L / min and the cavity is purged for 3-5 minutes.

[0015] Preferably, in step (4), the mixture of antimony concentrate powder and blast furnace gas mud powder is heated to 650-900℃ at a rate of 10-30℃ / min and held for 40-120min.

[0016] Beneficial effects of the present invention

[0017] (1) This invention utilizes blast furnace gas mud to achieve carbothermic reduction of antimony-sulfurization of antimony concentrate, thereby achieving simultaneous sulfur fixation and solving the problem of low-concentration sulfur dioxide flue gas pollution during the pyrometallurgical smelting of antimony concentrate.

[0018] (2) This invention utilizes blast furnace gas mud in conjunction with antimony concentrate for carbothermic reduction of antimony and simultaneous sulfur fixation, providing a new approach for large-scale disposal of blast furnace gas mud and achieving waste treatment.

[0019] (3) Microwave heating characteristics enhance heat and mass transfer. Compared with conventional methods, the production cycle is shortened by more than 60%, the production efficiency is increased by 3 times, and the sulfur fixation rate is high. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. However, the scope of protection of the present invention is not limited to the content described. Unless otherwise specified, the operations in the embodiments are operations known to those skilled in the art, and all reagents used can be obtained through commercial purchase.

[0021] The ceramic crucibles used in all embodiments were made of SiO2-MgO-Al2O3 material, with a dielectric constant of less than 3 and a coefficient of thermal expansion of 2.5 × 10⁻⁶ at 20-1000℃. -6 / ℃. Example 1:

[0022] (1) Stibnite concentrate containing 52% antimony and blast furnace gas mud were dried at 80°C for 12 hours, then crushed and ground through an 80-mesh sieve to obtain stibnite concentrate powder and blast furnace gas mud powder for later use.

[0023] (2) Weigh 30g of the antimony concentrate powder obtained in step (1) and weigh 240g of the blast furnace gas mud powder obtained in step (1). Mix the antimony concentrate powder and the blast furnace gas mud powder evenly and put them into a ceramic crucible, and then place it in the center of the microwave reactor cavity.

[0024] (3) Turn on the atmosphere control system and blow N2 into the microwave cavity at a flow rate of 1.5 L / min for 4 min.

[0025] (4) Turn on the microwave source and feed 2kW of microwave energy into the microwave cavity. Heat the mixture of antimony concentrate powder and blast furnace gas mud powder to 650℃ at 10℃ / min and keep it at that temperature for 120min.

[0026] (5) After the heat preservation is completed, turn off the microwave source, skim off the scum on the surface of the crucible to obtain solid sulfur slag; the remaining liquid in the crucible is liquid antimony metal, pour the liquid antimony metal into the mold to cast ingot to obtain crude antimony metal.

[0027] The obtained crude antimony metal and sulfur-fixing slag were analyzed and characterized. The crude antimony contained 97.6% antimony, and the sulfur-fixing slag had a sulfur fixation rate of 98.3%. Example 2:

[0028] (1) Dry the antimony-containing 52% antimony concentrate and blast furnace gas mud at 80°C for 12 hours, then crush and grind them through an 80-mesh sieve to obtain antimony concentrate powder and blast furnace gas mud powder for later use.

[0029] (2) Weigh 35g of stibnite concentrate and 140g of blast furnace gas mud powder obtained in step (1). Mix the stibnite concentrate powder and blast furnace gas mud powder evenly and place them in a ceramic crucible, then place it in the center of the microwave reactor cavity.

[0030] (3) Turn on the atmosphere control system and blow N2 into the microwave cavity at a flow rate of 2 L / min for 3 min.

[0031] (4) Turn on the microwave source and feed 3kW of microwave energy into the microwave cavity. Heat the mixture of antimony concentrate and blast furnace gas mud to 800℃ at 20℃ / min and keep it at that temperature for 60min.

[0032] (5) After the heat preservation is completed, turn off the microwave source, skim off the scum on the surface of the crucible to obtain solid sulfur slag; pour the antimony metal into the mold to cast ingot to obtain crude antimony metal.

[0033] The obtained crude antimony metal and sulfur-fixing slag were analyzed and characterized. The crude antimony contained 98.2% antimony, and the sulfur-fixing slag had a sulfur fixation rate of 98.7%. Example 3:

[0034] (1) Dry the antimony-containing 52% antimony concentrate and blast furnace gas mud at 80°C for 12 hours, then crush and grind them through an 80-mesh sieve to obtain antimony concentrate powder and blast furnace gas mud powder for later use.

[0035] (2) Weigh 40g of the antimony concentrate powder obtained in step (1) and weigh 120g of the blast furnace gas mud powder obtained in step (1). Mix the antimony concentrate powder and the blast furnace gas mud powder evenly and put them into a ceramic crucible, and then place it in the center of the microwave reactor cavity.

[0036] (3) Turn on the atmosphere control system and blow N2 into the microwave cavity at a flow rate of 3 L / min for 5 min.

[0037] (4) Turn on the microwave source and feed 4kW of microwave energy into the microwave cavity. Heat the mixture of antimony concentrate and blast furnace gas mud to 900℃ at 30℃ / min and keep it at that temperature for 40min.

[0038] (5) After the heat preservation is completed, turn off the microwave source, skim off the scum on the surface of the crucible to obtain solid sulfur slag; pour the antimony metal into the mold to cast ingot to obtain crude antimony metal.

[0039] The obtained crude antimony metal and sulfur-fixing slag were analyzed and characterized. The crude antimony contained 98.8% antimony, and the sulfur-fixing slag had a sulfur fixation rate of 99.2%.

[0040] Comparative Example 1

[0041] In comparison, both this comparative example and Example 3 use stibnite concentrate containing 52% antimony as raw material, and the process parameters, heating rate, reduction time, and holding time are the same as in Example 3. The difference is that the blast furnace gas mud is replaced with an iron oxide-coke combination. The crude antimony obtained in this comparative example contains less than 95% antimony and has a sulfur fixation rate of less than 96%.

[0042] Comparative Example 2

[0043] In comparison, both this comparative example and Example 3 use antimony concentrate containing 52% antimony as raw material, and the process parameters, heating rate, reduction time, and holding time are the same as in Example 3. The difference is that the blast furnace gas mud is replaced with a zinc oxide-coke combination. The crude antimony obtained in this comparative example contains less than 95% antimony and has a sulfur fixation rate of less than 96%.

[0044] The comparison between the examples and the comparative examples shows that the use of blast furnace gas mud can effectively increase the antimony content and sulfur fixation rate of crude antimony.

[0045] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various new fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A method for antimony extraction and sulfur fixation using blast furnace gas sludge, characterized in that: The specific steps are as follows: (1) Dry, crush, grind and sieve the antimony concentrate and blast furnace gas mud respectively to obtain antimony concentrate powder and blast furnace gas mud powder for later use. (2) Mix the antimony concentrate powder and blast furnace gas mud powder obtained in step (1) in a mass ratio of 1:3 to 1:8 and place them in a ceramic crucible, then place it in the center of the microwave reactor cavity. (3) Turn on the atmosphere control system and blow N2 into the microwave cavity to purge the cavity; (4) Turn on the microwave source and feed microwave energy into the microwave cavity to heat up and keep the mixture of antimony concentrate powder and blast furnace gas mud powder. (5) After the heat preservation is completed, turn off the microwave source, remove the slag on the surface of the crucible, and obtain solid sulfur slag; the remaining liquid in the crucible is antimony liquid, and pour the antimony liquid into the mold to cast ingot to obtain crude antimony.

2. The method for antimony extraction and sulfur fixation from blast furnace gas sludge according to claim 1, characterized in that: In step (1), the drying temperature is 80℃ and the drying time is 12 hours. After grinding, the product is passed through an 80-mesh sieve.

3. The method for antimony extraction and sulfur fixation from blast furnace gas sludge according to claim 1, characterized in that: The ceramic crucible in step (2) is made of SiO2-MgO-Al2O3 material, with a dielectric constant of less than 3 and a coefficient of thermal expansion of 2.5 × 10⁻⁶ at 20-1000℃. -6 / ℃.

4. The method for antimony extraction and sulfur fixation from blast furnace gas sludge according to claim 1, characterized in that: In step (2), the ceramic crucible is wrapped with a 3cm thick aluminum silicate insulation material, and the dielectric constant of the aluminum silicate insulation material is less than 2.

5. The method for antimony extraction and sulfur fixation from blast furnace gas sludge according to claim 1, characterized in that: In step (3), N2 is blown into the microwave cavity at a flow rate of 1.5 to 3 L / min and the cavity is purged for 3 to 5 minutes.

6. The method for antimony extraction and sulfur fixation from blast furnace gas sludge according to claim 1, characterized in that: In step (4), the mixture of antimony concentrate powder and blast furnace gas mud powder is heated to 650-900℃ at a rate of 10-30℃ / min and held for 40-120min.